Tuesday, July 31, 2012

Pros and cons for C4d as a biomarker

The introduction of C4d in daily clinical practice in the late nineties aroused an ever-increasing interest in the role of antibody-mediated mechanisms in allograft rejection. As a marker of classical complement activation, C4d made it possible to visualize the direct link between anti-donor antibodies and tissue injury at sites of antibody binding in a graft. With the expanding use of C4d worldwide several limitations of C4d were identified. For instance, in ABO-incompatible transplantations C4d is present in the majority of grafts but this seems to point at 'graft accommodation' rather than antibody-mediated rejection. C4d is now increasingly recognized as a potential biomarker in other fields where antibodies can cause tissue damage, such as systemic autoimmune diseases and pregnancy. In all these fields, C4d holds promise to detect patients at risk for the consequences of antibody-mediated disease. Moreover, the emergence of new therapeutics that block complement activation makes C4d a marker with potential to identify patients who may possibly benefit from these drugs. This review provides an overview of the past, present, and future perspectives of C4d as a biomarker, focusing on its use in solid organ transplantation and discussing its possible new roles in autoimmunity and pregnancy (read more and comment)

Sunday, July 29, 2012

HLA and predisposition to infectious diseases

A) viruses

EBV : individuals carrying the HLA-A*02 allele have a reduced risk of developing EBV+ HL, while individuals carrying the HLA-A*01 allele have an increased risk. It is known that HLA-A*02 can present EBV-derived peptides and can evoke an effective immune response, which may explain the protective phenotypE (ref)

HIV-1 :
  • HLA-B*57 (Migueles et al., 2000; Altfeld et al., 2003; Miura et al., 2009) and HLA-B*27 (Goulder et al., 1997; Feeney et al., 2004; Altfeld et al., 2006; Schneidewind et al., 2007): lower viral loads in the chronic phase and slow disease progression
  • HLA-B*35-Px alleles including HLA-B*35:02, B*35:03, and B*35:04 associate with rapid disease progression, whereas the latter HLA-B35-Py alleles including HLA-B*35:01 and HLA-B*35:08 associate with relatively slower progression (Gao et al., 2001). Such differences in disease progression among HLA-B subtypes are also known in HLA-B*58 (Leslie et al., 2010).
  • the HLA-B*57, -B*14, -C*8 alleles, and mainly -B*27, were found to be negatively associated with progression of the disease, and they are possible protective factors
  • HLA-B*18 allele was associated with a significantly lower risk of early HIV-1 vertical transmission. An increase in the early acquisition of HIV-1 was also observed in children who had the HLA-A*29 allele. Transmission is increased if the fetus or the newborn has the HLA-DRB1*03:011 allele, while the HLA-DR13 antigen and the HLA-DRB1*1501 allele would appear to protect against infection
  • HLA-A*3601 allele was associated with greater risk of developing tuberculosis in HIV-positive patients
  • HLA-A*6802 appears to facilitate rapid progression to pleural disease and to allow mycobacterial replication that is difficult to control
  • HLA-A1, -B8, -DR3 antigens are protective factors against infection by cytomegalovirus and by the Mycobacterium avium Complex (MAC) in HIV patients with severe immunodeficiency and that have not yet been submitted to highly effective antiretroviral therapy
HIV-2 :
  • HLA-B*53 allele and HLA-B*35-Cw*4 and -A*23-Cw*7 haplotypes were associated with a greater risk of progression to AIDS [92].
Dengue virus :
  • in Thail patients who acquired the disease after a second infection, the HLA-A*02:03 allele was associated with dengue fever, irrespective of the viral serotype; -A*02:07 with severe hemorrhagic dengue by serotypes 1 and 2; -B*51 with hemorrhagic dengue on second exposure to the virus; -B*52 with dengue fever in patients with secondary infection by serotypes 1 and 2, and the antigens HLA-B*44, -B*62, -B*76 and -B*77 were negatively associated with the development of the disease after secondary infection.
  • in Mexico, individuals who had the HLA-DR4 antigen had 3.6 times less chance of developing hemorrhagic dengue after primary infection, when compared with individuals who did not have this antigen
  • in Brazil with patients who had contracted dengue fever after the first infection with serotype 1, the HLA-DQ1 antigen was associated with this disease, while no significant association was found with the HLA-DR1 antigen
HTLV-1 :
  • HLA-DR15 and -DQ1 antigens were found with greater frequency in patients with the virus when compared with healthy controls, while the HLA-DRB1*1501, -DRB1*1101 and -DQB1*0602 alleles were observed with greater frequency in patients with leukemia/lymphoma of adult T cells than in those with tropical spastic paraparesis
  • HLA-DRB1*1101-DQB1*0301 and -DRB1*1501-DQB1*0602 haplotypes were more frequent in patients with neoplasia than in those with myelopathy
  • patients with a HLA-A*02 allele had a 50% lower risk of developing myelopathy, while the presence of -DRB1*0101 conferred a risk two times greater, in the absence of the protective HLA-A*02
  • HLA-Cw*08 allele with protection against the disease and low viral load in asymptomatic patients
  • HLA-A*02 and -Cw*08 alleles prevented 36% of the potential cases of myelopathy and that HLA-B*54:01 was associated with a greater risk of developing myelopathy
Hepatitis B virus (HBV)
  • HLA-DPB1*05:01 homozygotes have significantly lower post-booster anti-HBs titers (ref)
  • HLA-DRB1*1302 [100,102] and -A*0301[100] alleles were found to be associated with greater elimination of the viral infection.
  • persistence of infection was associated with HLA-B*08 and with the haplotypes HLA-A*01-B*08-DRB1*03, -B*44-Cw*1601 and -B*44-Cw*0501
  • HLA-DRB1*0301, -DQA1*0501 and -DQB1*0301 alleles are associated with susceptibility to chronic liver disease by the B virus
  • HLA-DRB1*1101, -DRB1*1104 and -DQA1*0301 are associated with less evolution to chronicity
  • HLA-A24 and -Cw1 antigens were found to be associated with a lower risk of developing chronic hepatic disease, as were HLA-B13, -B8, -DR7, -DR13 and -DQ3
  • HLA-DR6 antigen, more specifically -DR13, appears to be associated with self-limiting hepatitis B
Hepatitis C virus (HCV) :
  • HLA-A*03, -B*27, -DRB1*0101, -DRB1*0401 and -DRB1*15 alleles are associated with eliminating the virus in the acute stage of the disease.
  • HLA-A*2301 and -Cw*04, on the contrary, are associated with the persistence of HCV in the hepatic cells. The HLA-DRB1*13 allele is associated with progression to chronic liver disease [108], whereas the absence of hepatic disease or the light form of the disease is associated with HLA-DRB1*11.
  • HLA-DQB1*0301 allele was associated with more effective viral elimination in Blacks
  • in Whites, viral suppression was associated with the HLA-DRB1*0101 allele and with the HLA-DRB1*0101-DQB1*0501 haplotype, while the permanence of the virus was associated with the HLA-DRB1*0301 allele and with the HLA-DRB1*0301-DQB1*0201haplotype
  • HLA-DR13 antigen is negatively associated with the risk for vertical transmission
  • HLA-DQB1*0301 and -DRB1*11 alleles with a self-limiting infection
  • supertype DRB3 (prevalence ratio (PR)=0.4; P=0.004) was associated with HCV persistence, whereas DR8 (PR=1.8; P=0.01) was associated with HCV clearance. HLA-B*57:03 (PR=1.9; P=0.008) and DRB1*07:01 (PR=1.7; P=0.005)ref
HHV-6 encephalopathy after allo-HSCT : HLA-B*40:06 (P=0.027), in linkage with HLA-A*26:01 and HLA-C*08:01  (P<0.001)ref

JCV : alleles within the HLA-DR1*15 haplotype are associated with a protective effect on JCV infection. Alleles within the DQB1*06:03 haplotype show an opposite associationref.

BKV : HLA C7 negative donors and recipientsref, and  HLA-A28 and A68 positive recipientsref have sustained viremia, while recipient HLA-A2 and donor HLA-A9 increased the risk of BKPyVANref. HLA-B51-positivity reduced the risk of viremia approximately five-fold (HR 0.18) (Wunderink et al. 2018)

VZV : HLA-A*33 and HLA-B*44 are significantly enriched in PHN patients, while HLA-A*02 and HLA-B*40ref.

B) bacteria

Mycobacterium tuberculosis :
  • HLA-DRB2*1501 and -DRB1*1502 is associated with the development of severe and multibacillary forms of tuberculosis, as well as with the greater prevalence of forms resistant to drug therapy. The HLA-DRB1*07 and -DQA1*0101 alleles are associated with greater susceptibility to the development of pulmonary tuberculosis and the HLA-DQA1*0301 and -DQA1*0501 alleles are associated with protection against this infection
  • HLA-DPB1*04 allele with protection against tuberculosis, while -DRB1*1501 and -DQB1*0601 are associated with susceptibility. Mehra et al. (1995) reported association of the HLA-DRB1*1501 allele with susceptibility to tuberculosis, emphasizing the importance of the HLA-DRB1*1501-DRB5*0101-DQA1*0103-DQB1*0601 haplotype. The diversity of the HLA antigens in populations from different ethnic-racial origins can be demonstrated by means of a few examples. In Poles, it was suggested that the HLA-DR16 antigen increases the risk of developing tuberculosis, while the antigen HLA-DR13 protects against the disease. In India, the results are controversial. One study showed that the HLA-A10, -B8 and -DR2 antigens presented with greater frequency in persons with tuberculosis than in healthy controls, while another did not find any association between HLA class II antigens and pulmonary tuberculosis.
Mycobacterium leprae (Hansen's disease, leprosy) :
  • Some studies suggest associations of the HLA-DR2 and -DR3 antigens with the tuberculoid form and the HLA-DQ1 antigens with the virchowian form of Hansen's disease.
  • contaminated individuals had a greater frequency of the alleles HLA-A*0203, -A*0206, -A*1102, -B*1801, -B*4016, -B*5110, -Cw*0407 and -Cw*0703 and a lower frequency of HLA-A*0101, -A*0211, -B*4006, -Cw*03031, -Cw*04011 and -Cw*0602 [22].
  • HLA-DRB1*1502 allele is positively associated with the development of Hansen's disease, and that the HLA-DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0502 haplotype is associated with protection
  • HLA-DRB1*1501-DQA1*0102-DQB1*0602 haplotype was associated with susceptibility to leprosy
  • high frequency of the HLA-DRB1*1501 and -DRB1*1502 alleles in patients with the multibacillary and tuberculoid form and of -DQA1*0103 in those who had the virchowian form. The HLA-DQA1*0102 allele was more frequent in patients with the light form of the disease. On the other hand, the HLA-DRB1*0701, -DQB1*0201 and -DQB1*0503 alleles were less frequent in patients with the multibacillary form, when compared with patients with the tuberculoid form; in this latter group there was a low frequency of the HLA-DQB1*0503 allele. Thus, patients that presented with HLA-DR2 and -DQ1 antigens, especially the HLA-DRB1*1501, -DQB1*0601 and -DQA1*0103 alleles, are considered to be more susceptible to developing severe forms of this disease, multibacillary lepromatous leprosy. The HLA-DRB1*0701, -DQB1*0201 and -DQA1*0201 alleles would appear to protect against the severe forms of the disease and -DQB1*0503 against the lighter forms.
  • the HLA-A*1102-B*4006-Cw*1502, HLA-A*0203-B*4016-Cw*0703 and HLA-A*11-B*40 haplotypes were associated with protection against the multibacillary form
  • in Brazil, Marcos et al. (2000) found no association of the ulcerated type 1 hansen reaction (manifestation of hypersensitivity due to bacillary multiplication) with HLA class II antigens [10]. However, Miller et al. (2004) suggested an association of molecules coded by genes from the HLA-DQA region with the occurrence of this disease. Another study, also conducted on Brazilians, found a positive association between the HLA-DR2 antigen and the tuberculoid form of Hansen's disease.
C) Parasites
Plasmodium spp. (malaria) :
  • increased frequency of the HLA-B46 and -B56 antigens and of the HLA-DRB1*1001 allele were found among groups of patients with severe non-cerebral and cerebral malaria [40]. An association with the HLA-B53 antigen and protection against severe forms of the disease is well established, reducing the risk of death by up to 40%. The HLA-DRB1*1302-DQB1*0501 haplotype appears to protect against severe forms. As this association is related to parasitic antigens present in the hepatic stage of the illness, it may influence the development of vaccines that use this antigen as one of their components. In India, increased frequency of the HLA-A3, -B27 and -B49 antigens and of the HLA-DRB1*04 and -DRB1*0809 alleles were found. In the same population the HLA-A19, -A34, -B18, and -B37 antigens and the HLA-DQB1*0203 allele were associated with protection. Johnson et al. (2000) suggested that immunity against Plasmodium falciparum varies in accordance with the individual's age. They indicated that the HLA-DQB1*0301 and -DQB1*03:03:2 alleles only showed age-dependent association with the levels of antibody against rRAP1 proteins of the plasmodium in children from 5 to 15 years old. After this age, immunity against malaria becomes independent of these two alleles. The HLA-DRB1*03:011 allele is associated with higher levels of antibody against the parasite's rRAP2 protein in adults over 30 years of age. These data suggest that the effect of HLA on the evolution of infection by malaria differs in accordance with age, that it is stimulated by different antigens of the plasmodium, and that HLA is able to influence the quantity of antibodies to be produced against the parasite.
Leishmania donovani (cutaneous and visceral leishmaniasis)
  • HLA-Cw7 antigen as a marker of susceptibility to cutaneous leishmaniasis
  • HLA-A11, -B5, -B7, -Bw2 and -DQw3 antigens were found to be associated with an increased susceptibility to cutaneous leishmaniasis
  • HLA-DR2, with greater protection
  • HLA-A26 antigen is associated with the occurrence of kala-azar
  • hepatosplenomegaly and its severity to the occurrence of the HLA-A1 (HLA-A*01) and -B5 (HLA-B*5106) antigens 
  • greater degree of hepatic fibrosis with the HLA-A2 (HLA-A*02) and -B12 (-B*4409) antigens
  • lower degree of hepatic fibrosis with the HLA-DR2 (HLA-DRB1*1603 or -DRB1*1605) antigen 
  • HLA-B5 (-B*85106) and -DR3 (-DRB1*0306) antigens with schistosomiasis mansoni [61].
  • HLA-DRB1*12:02 and -DQA1*06:01 alleles are considered to be protectors against the advance of hepatic fibrosis, since these two alleles frequently co-occur, although their individual protective effects have not yet been explained. In patients with an advanced degree of hepatic fibrosis, the presence of the HLA-DQB1*05:031 allele is common, while the HLA-DQA1*06:01 allele is considered to be protective. The HLA-DRB1*15:01-DRB5*01:01 haplotype is associated with an advanced degree of hepatic fibrosis, and the HLA-DRB1*11:01-DQA1*05:01-DQB1*03:01, -DQA1*01:03-DPB1*02:01 haplotypes are associated with protection against fibrosis. Recently McManaus et al. (2001) associated the HLA-DRB1*0901, -DRB1*13:02, -DQB1*03:03 and -DQB1*06:09 alleles with greater susceptibility to advanced hepatic fibrosis. The HLA-DRB1*15:01 and -DQB1*06:01 alleles appear to be protective. Although many factors are involved in the inflammatory process of hepatic fibrosis, the HLA genes, mainly the HLA-DRB5*01:01 allele, seem to be among the main factors that affect its prognosis. The heterogeneity of the studies available till now on hepatic fibrosis does not allow consistent conclusions to be drawn
Trypanosoma cruzi (Chagas' disease)
  • HLA-A30 antigen confers increased susceptibility
  • HLA-DQB1*06 allele confers protection, irrespective of whether its form of presentation is cardiac or digestive [66].
  • a greater frequency of HLA-B39 and -DR4 antigens was found in patients with Chagas' disease [67]. The patients with cardiomyopathy exhibited a greater frequency of HLA-B35 antigens [67]. In these same patients, there was an increased frequency of the HLA-DR16 antigen when compared with asymptomatic patients and with healthy controls. Thus, the HLA-DR4 and -B39 antigens may be associated with infection by T. cruzi; -DR16 with susceptibility to the cardiac condition, and -A68 with protection against cardiomyopathy [67]. In Venezuelans, a greater frequency of the HLA-C*03 allele was observed in patients with the cardiac form of Chagas' disease [69], and a low frequency of the HLA-DRB1*14 and -DQB1*0303 alleles was found in seropositive patients, inhabitants of an endemic region, suggesting the protective effect of these alleles against chronic infection [70]. Among seropositive patients, when comparing those with and without cardiomyopathy, high frequencies of the HLA-DRB1*01, -DRB1*08 and -DQB1*0501 alleles and low frequencies of-DRB1*1501 [69] were found in the cardiomyopathic group. Another study on this population in an endemic region revealed an association of the HLA-DRB1*01-DQB1*0501 haplotype with cardiomyopathy [71]. The HLA-DRB1*01-DQB1*0501-DPB1*0401 haplotype is mentioned by Fernández-Mestre et al. (2002) as a marker of susceptibility to Chagas' disease in Venezuela [72], while HLA-DRB1*14-DQB1*0301 was associated with non-infection by T. cruzi in individuals inhabiting a highly endemic area in Peru [73]. Overtvelt et al. (2002) demonstrated that HLA class I also participates in the escape mechanism of T. cruzi from the immune response, associating greater expression of some of these molecules with longer persistence of the parasite in the host organism without eliciting an immune response [74]. In Chile, high levels of HLA-B40 and -Cw3 antigens were found in seropositive patients without cardiac disease, suggesting a protective function of the HLA genes responsible for the expression of these antigens [75]. When comparing chronic cardiomyopathy patients with others that presented with cardiac transplant rejection and with a third group, made up of patients with dilated cardiomyopathy secondary to another etiology, greater expression of HLA class I was perceived in the cardiomyocytes of the first two groups [76]. In contaminated but asymptomatic patients, when compared with those that developed Chagas' disease cardiomyopathy, a greater frequency of the HLA-A68 and -B39 antigens was observed in the former
Podoconiosis :
  • HLA-DRB1*0701 (odds ratio, 2.00), DQA1*0201 (odds ratio, 1.91), and DQB1*0202 (odds ratio, 1.79) and the HLA-DRB1*0701–DQB1*0202 haplotype (odds ratio, 1.92) were risk variants for podoconiosis.

Prospective Evaluation of the Toxicity Profile of Proteasome Inhibitor-Based Therapy in Renal Transplant Candidates and Recipients.

BACKGROUND: A prospective intermediate-term evaluation of toxicities associated with bortezomib therapy for antibody-mediated rejection (AMR) and desensitization was conducted. METHODS: Patients were graded for bortezomib-related toxicities: hematologic and gastrointestinal toxicities by Common Terminology Criteria for Adverse Events and peripheral neuropathy by modified Functional Assessment of Cancer Therapy questionnaire and Common Terminology Criteria for Adverse Events. RESULTS: Fifty-one patients treated for AMR and 19 patients treated for desensitization received 96 bortezomib cycles (1.3 mg/m ×4 doses); mean (SD) follow-up was 16.3 (9.0) months. Patients treated for AMR and patients treated for desensitization were similar in age, gender, ethnicity, and baseline peripheral neuropathy. Patients treated for AMR received a mean (SD) of 4.9 (2.0) bortezomib doses in 1.3 (0.5) cycles; and patients treated for desensitization, a mean of 7.3 (1.6) doses in 1.8 (0.4) cycles. Prevalence of diabetes and anemia were higher at baseline in patients treated for AMR. In the AMR cohort, two cases of cytomegalovirus infection, two cases of BK virus infection, and one case of Epstein-Barr virus infection were observed. No cases of viral infection were observed in the desensitization cohort. Malignancies were not observed. Significant bortezomib toxicities included anemia and peripheral neuropathy, which were manageable. Anemia was more common in patients treated for AMR; and peripheral neuropathy, more common in patients treated for desensitization. CONCLUSIONS: Bortezomib-related toxicities in kidney transplant candidates and recipients are low in incidence and severity and vary based on treatment population (read more)

Saturday, July 28, 2012

Xeno-Kidney Transplantation: From Idea to Reality

Although kidney transplantation is a widely used therapy for chronic renal failure, not all patients can be transplanted due to the limited numbers of organ donations. A possible solution could be xenogenic kidney transplantation. Herein we have described the present state, problems and possible solutions using xenograft treatments (read more).

Pancreas Transplantation From Donors After Circulatory Death From the United Kingdom

This study reports the comparative short-term results of pancreas transplantation from donors after circulatory death (DCD) (Maastricht III & IV), and pancreases from brainstem deceased donors (DBD). Between January 2006 and December 2010, 1009 pancreas transplants were performed in the United Kingdom, with 134 grafts from DCD and 875 from DBD. DCD grafts had no premortem pharmacological interventions performed. One-year pancreas and patient survival was similar between DCD and DBD, with pancreas graft survival significantly better in the DCD cohort if performed as an SPK. Early graft loss due to thrombosis (8% vs. 4%) was mainly responsible for early graft loss in the DCD cohort. These results from donors with broader acceptance criteria in age, body mass index, premortem interventions, etc. suggest that DCD pancreas grafts may have a larger application potential than previously recognized (read more).

Thursday, July 26, 2012

Donor-specific anti-HLA antibody monitoring and removal in solid organ transplant recipients.

Based on our knowledge that donor specific anti-HLA antibodies (DSA) are a major cause of allograft loss, determining how to monitor patients for DSA and how to treat them is important. Current published studies indicate that patients with preformed DSA differ from those without. Approximately 15-18 percent of transplant patients will have preformed DSA, which increases risk for early antibody mediated rejection (AMR) and allograft loss. The fact that nearly all AMR episodes occur in the first 1-2 months, coupled with the finding that a reduction in preformed DSA intensity within the first few weeks post-transplant decreases the risk of AMR, makes early testing important. It has also been shown that clearance of DSA at 6 months and 1 year can result in a decreased risk of transplant glomerulopathy and therefore, these times may be prime testing points. This monitoring schedule differs slightly from that of the patients who do not have performed DSA (i.e. low risk patients). Low risk patients who develop de novo DSA are most likely to do so in the first 6 months. However, more frequent sampling in the early months does not improve predictability of acute rejections in low risk patients and therefore, it is not as essential. Rather, testing at 6 months and then annually or biannually, would be beneficial, as it would serve to identify the 5 percent of new patients who develop DSA annually. Once these patients are identified, studies have shown that preemptive treatment to a goal of antibody clearance can be used to improve graft function and survival. In addition to screening for new DSA, monitoring for clearance of DSA along with histologic reversal of rejection in patients with AMR is important. In sum, there is substantial evidence suggesting that all patients need to have some monitoring for DSA to identify new onset of DSA or clearance of DSA. Additionally, in all DSA scenarios, treatment of persistent DSA is important, as it can lead to improved allograft survival (read more).

Sirolimus and Secondary Skin-Cancer Prevention in Kidney Transplantation

Background : Transplant recipients in whom cutaneous squamous-cell carcinomas develop are at high risk for multiple subsequent skin cancers. Whether sirolimus is useful in the prevention of secondary skin cancer has not been assessed.
Methods : In this multicenter trial, we randomly assigned transplant recipients who were taking calcineurin inhibitors and had at least one cutaneous squamous-cell carcinoma either to receive sirolimus as a substitute for calcineurin inhibitors (in 64 patients) or to maintain their initial treatment (in 56). The primary end point was survival free of squamous-cell carcinoma at 2 years. Secondary end points included the time until the onset of new squamous-cell carcinomas, occurrence of other skin tumors, graft function, and problems with sirolimus.
Results: Survival free of cutaneous squamous-cell carcinoma was significantly longer in the sirolimus group than in the calcineurin-inhibitor group. Overall, new squamous-cell carcinomas developed in 14 patients (22%) in the sirolimus group (6 after withdrawal of sirolimus) and in 22 (39%) in the calcineurin-inhibitor group (median time until onset, 15 vs. 7 months; P=0.02), with a relative risk in the sirolimus group of 0.56 (95% confidence interval, 0.32 to 0.98). There were 60 serious adverse events in the sirolimus group, as compared with 14 such events in the calcineurin-inhibitor group (average, 0.938 vs. 0.250). There were twice as many serious adverse events in patients who had been converted to sirolimus with rapid protocols as in those with progressive protocols. In the sirolimus group, 23% of patients discontinued the drug because of adverse events. Graft function remained stable in the two study groups.
Conclusions : Switching from calcineurin inhibitors to sirolimus had an antitumoral effect among kidney-transplant recipients with previous squamous-cell carcinoma. These observations may have implications concerning immunosuppressive treatment of patients with cutaneous squamous-cell carcinomas. (Funded by Hospices Civils de Lyon and others; TUMORAPA ClinicalTrials.gov number, NCT00133887) (read more)

A report of the epidemiology of de novo donor-specific anti-HLA antibodies (DSA) in "low-risk" renal transplant recipients.

The donor specific anti-HLA antibody (DSA) has been increasingly recognized as the major cause of allograft loss. Despite this, no published reports exist describing the true epidemiology of de novo DSA.Here we describe the epidemiology of DSA based on the results of one of the longest running antibody study in consecutive renal transplant recipients. The study includes 224 non-sensitized, non-HLA-identical patients who received a primary kidney transplant between 3/1999-3/2006. Protocol testing for DSA was done pre-transplant, at 1, 3, 6, 9, and 12 months, and then annually. DSA was tested using single antigen beads. Data from the East Carolina University transplant cohort indicate that the prevalence of DSA in the first year post-transplant is 12.1 cases per 100. The average annual incidence of DSA is 4.7 per 100 cases, per year. The highest incidence of DSA was in the first year post transplant. Although deceased donors and African-Americans have a higher incidence rate of DSA than the comparator living donors and non-African American groups, respectively, these factors were not associated with DSA onset. The one factor found to be predictive of DSA was DQ mismatch (p = 0.036). Based on these epidemiologic findings in combination with previous reports showing DSA is a cause of allograft failure, it seems reasonable that at least annual testing should be done even in "low-risk" transplant patients, because every year a new 5% of patients will develop DSA (read more)

Wednesday, July 25, 2012

De Novo DQ Donor-Specific Antibodies Are Associated With a Significant Risk of Antibody-Mediated Rejection and Transplant Glomerulopathy

Background: The importance of human leukocyte antigen (HLA) matching in renal transplantation is well recognized, with HLA-DR compatibility having the greatest influence. De novo DQ donor-specific antibodies (DSAbs) are the predominant HLA class II DSAb after transplantation. The aim of this study was to establish the incidence and outcomes after the development of DQ DSAbs along with the impact of class II HLA mismatch on their development.
Methods: We retrospectively analyzed 505 patients who received a renal-alone transplant between 2005 and 2010. We excluded patients who received an ABO- and HLA-incompatible allograft, which we defined as those with a positive crossmatch or preformed DSAbs detected by single-antigen beads only.
Results: Of 505 patients, 92 (18.2%) developed DSAbs, with 50 (54.3%) of these 92 patients having DQ DSAbs. Patients who developed DQ DSAbs were at significant risk for antibody-mediated rejection, transplant glomerulopathy, and allograft loss (P<0.0001). Of 505 patients, 108 (21.4%) were matched at both the DR and DQ loci, 284 (56.2%) were mismatched at both loci, 38 (7.5%) were matched at DR alone, and 75 (14.9%) were matched at DQ alone. Patients mismatched at both DR and DQ were at risk for developing class II DSAbs when compared with those mismatched at either DR or DQ alone, P=0.001, and were at risk for antibody-mediated rejection, P=0.001.
Conclusions: DQ DSAbs are associated with inferior allograft outcomes. This study shows the importance of establishing the DQ match before transplantation to define immunologic risk (read more).

The Comparison of Interleukin 6–Associated Immunosuppressive Effects of Human ESCs, Fetal-Type MSCs, and Adult-Type MSCs

Background: Although human embryonic stem cells (ESCs) and mesenchymal stem cells (MSCs) from various sources display immunomodulatory effects, direct comparisons among these classes of stem cells have not been reported.
Methods: Peripheral blood mononuclear cell suppression assays and carboxyfluorescein diacetate succinimidyl ester assays were used to assess the immunosuppressive effects of stem cells. Gene expression was measured using DNA microarrays. Enzyme-linked immunosorbent assays were used to determine interleukin (IL)-6 levels.
Results: We found that fetal-type MSCs proliferated significantly faster than adult-type MSCs. Compared with ESCs grown on feeder cells, ESCs grown in feeder cell–free conditions exhibited decreased immunosuppressive effects. The suppressive effects of ESCs were significantly stronger than those of MSCs, and the suppressive effects of fetal-type MSCs were significantly stronger than those of adult-type MSCs at each tested dose level. Analysis of gene expression by microarray and MetaCore pathway mapping revealed changes in eight different immune response pathways; we observed that IL-6 gene expression was highly significantly involved in all eight pathways. Significantly higher IL-6 elevation ratios (IL-6after:IL-6before) were found in ESCs compared with fetal-type MSCs, and these were also found in fetal-type MSCs compared with adult-type MSCs. Furthermore, IL-6 levels were found to correlate with cell dosages of MSCs and the suppressive effects.
Conclusions: The ease of obtaining fetal-type MSCs and their rapid proliferation make these cells ideal candidates for cell-based therapies, especially for diseases associated with immune responses, given the immunosuppressive effects of these cells. IL-6 might play an important role in the immunosuppressive effects of various stem cells (read more).

The Eurotransplant Donor Risk Index in Liver Transplantation: ET-DRI

Recently we validated the donor risk index (DRI) as conducted by Feng et al. for the Eurotransplant region. Although this scoring system is a valid tool for scoring donor liver quality, for allocation purposes a scoring system tailored for the Eurotransplant region may be more appropriate. Objective of our study was to investigate various donor and transplant risk factors and design a risk model for the Eurotransplant region. This study is a database analysis of all 5939 liver transplantations from deceased donors into adult recipients from the 1st of January 2003 until the 31st of December 2007 in Eurotransplant. Data were analyzed with Kaplan–Meier and Cox regression models. From 5723 patients follow-up data were available with a mean of 2.5 years. After multivariate analysis the DRI (p < 0.0001), latest lab GGT (p = 0.005) and rescue allocation (p = 0.007) remained significant. These factors were used to create the Eurotransplant Donor Risk Index (ET-DRI). Concordance-index calculation shows this ET-DRI to have high predictive value for outcome after liver transplantation. Therefore, we advise the use of this ET-DRI for risk indication and possibly for allocation purposes within the Eurotrans-plant region (read more).

Monitoring of Immunoglobulin Levels Identifies Kidney Transplant Recipients at High Risk of Infection

We aimed to analyze the incidence, risk factors and impact of hypogammaglobulinemia (HGG) in 226 kidney transplant (KT) recipients in which serum immunoglobulin (Ig) levels were prospectively assessed at baseline, month 1 (T1), and month 6 (T6). The prevalence of IgG HGG increased from 6.6% (baseline) to 52.0% (T1) and subsequently decreased to 31.4% (T6) (p < 0.001). The presence of IgG HGG at baseline (odds ratio [OR] 26.9; p = 0.012) and a positive anti-HCV status (OR 0.17; p = 0.023) emerged as risk factors for the occurrence of posttransplant IgG HGG. Patients with HGG of any class at T1 had higher incidences of overall (p = 0.018) and bacterial infection (p = 0.004), bacteremia (p = 0.054) and acute pyelonephritis (p = 0.003) in the intermediate period (months 1–6). Patients with HGG at T6 had higher incidences of overall (p = 0.004) and bacterial infection (p < 0.001) in the late period (>6 month). A complementary log–log model identified posttransplant HGG as an independent risk factor for overall (hazard ratio [HR] 2.03; p < 0.001) and bacterial infection (HR 2.68; p < 0.0001). Monitoring of humoral immunity identifies KT recipients at high risk of infection, offering the opportunity for preemptive immunoglobulin replacement therapy (read more).

Lack of Effect in Desensitization With Intravenous Immunoglobulin and Rituximab in Highly Sensitized Patients.

BACKGROUND: We conducted a prospective cohort study in highly sensitized kidney transplant candidates with a calculated panel reactive antibody (cPRA) greater than 50% and on the deceased-donor waiting list for more than 5 years to investigate the effects of intravenous immunoglobulin (IVIG) and rituximab treatment. METHODS: Desensitization protocol included two doses of IVIG (2 g/kg, max 120 g each dose) and a single dose of rituximab (375 mg/m). Patients were followed up monthly by Luminex single antigen beads. Whole blood gene expression profiles were studied by Affymetrix Human 1.0 ST GeneChips before and after treatment. RESULTS: Forty patients were eligible for desensitization treatment. Thirteen of these patients agreed to participate, and 11 completed the treatment. After a mean follow-up of 334 ± 82 days, two desensitized patients (18%) received a kidney transplant compared with 14 patients (52%) in the nondesensitized group. Comparing with 14 patients who received transplants without any desensitization treatment, desensitized patients showed higher class I (99% vs. 80%) and class II (98% vs. 69%) cPRA levels and more unacceptable antigens (32 vs. 8). Desensitization treatment did not lead to any significant reduction in patients' class I and II cPRA levels and any change in the mean number of unacceptable antigens or their mean fluorescence intensity values. Whole blood gene expression analysis by microarrays demonstrated down-regulation of immunoglobulin and B-cell-associated transcripts after treatment. CONCLUSION: These results suggested that pretransplant desensitization with IVIG and rituximab was not successful in highly sensitized kidney transplant candidates with cPRA levels higher than 90% (read more)

Saturday, July 21, 2012

Induction Therapy With Autologous Mesenchymal Stem Cells in Living-Related Kidney Transplants (A Randomized Controlled Trial)

CONTEXT: Antibody-based induction therapy plus calcineurin inhibitors (CNIs) reduce acute rejection rates in kidney recipients; however, opportunistic infections and toxic CNI effects remain challenging. Reportedly, mesenchymal stem cells (MSCs) have successfully treated graft-vs-host disease.
OBJECTIVE: To assess autologous MSCs as replacement of antibody induction for patients with end-stage renal disease who undergo ABO-compatible, cross-match-negative kidney transplants from a living-related donor.
DESIGN, SETTING, AND PATIENTS: One hundred fifty-nine patients were enrolled in this single-site, prospective, open-label, randomized study from February 2008-May 2009, when recruitment was completed.
INTERVENTION: Patients were inoculated with marrow-derived autologous MSC (1-2 x 10(6)/kg) at kidney reperfusion and two weeks later. Fifty-three patients received standard-dose and 52 patients received low-dose CNIs (80% of standard); 51 patients in the control group received anti-IL-2 receptor antibody plus standard-dose CNIs.
MAIN OUTCOME MEASURES: The primary measure was 1-year incidence of acute rejection and renal function (estimated glomerular filtration rate [eGFR]); the secondary measure was patient and graft survival and incidence of adverse events.
RESULTS: Patient and graft survival at 13 to 30 months was similar in all groups. After 6 months, 4 of 53 patients (7.5%) in the autologous MSC plus standard-dose CNI group (95% CI, 0.4%-14.7%; P = .04) and 4 of 52 patients (7.7%) in the low-dose group (95% CI, 0.5%-14.9%; P = .046) compared with 11 of 51 controls (21.6%; 95% CI, 10.5%-32.6%) had biopsy-confirmed acute rejection. None of the patients in either autologous MSC group had glucorticoid-resistant rejection, whereas 4 patients (7.8%) in the control group did (95% CI, 0.6%-15.1%; overall P = .02). Renal function recovered faster among both MSC groups showing increased eGFR levels during the first month after surgery than the control group. Patients receiving standard-dose CNI had a mean difference of 6.2 mL/min per 1.73 m(2) (95% CI, 0.4-11.9; P=.04) and those in the low-dose CNI of 10.0 mL/min per 1.73 m(2) (95% CI, 3.8-16.2; P=.002). Also, during the 1-year follow-up, combined analysis of MSC-treated groups revealed significantly decreased risk of opportunistic infections than the control group (hazard ratio, 0.42; 95% CI, 0.20-0.85, P=.02)
CONCLUSION: Among patients undergoing renal transplant, the use of autologous MSCs compared with anti-IL-2 receptor antibody induction therapy resulted in lower incidence of acute rejection, decreased risk of opportunistic infection, and better estimated renal function at 1 year.
TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00658073 (read more).

The Peptide-Receptive Transition State of MHC Class I Molecules: Insight from Structure and Molecular Dynamics [MOLECULAR AND STRUCTURAL IMMUNOLOGY]

MHC class I (MHC-I) proteins of the adaptive immune system require antigenic peptides for maintenance of mature conformation and immune function via specific recognition by MHC-I–restricted CD8+ T lymphocytes. New MHC-I molecules in the endoplasmic reticulum are held by chaperones in a peptide-receptive (PR) transition state pending release by tightly binding peptides. In this study, we show, by crystallographic, docking, and molecular dynamics methods, dramatic movement of a hinged unit containing a conserved 310 helix that flips from an exposed "open" position in the PR transition state to a "closed" position with buried hydrophobic side chains in the peptide-loaded mature molecule. Crystallography of hinged unit residues 46–53 of murine H-2Ld MHC-I H chain, complexed with mAb 64-3-7, demonstrates solvent exposure of these residues in the PR conformation. Docking and molecular dynamics predict how this segment moves to help form the A and B pockets crucial for the tight peptide binding needed for stability of the mature peptide-loaded conformation, chaperone dissociation, and Ag presentation (read more).

Transplantation of an allogeneic vein bioengineered with autologous stem cells: a proof-of-concept study

Background : Extrahepatic portal vein obstruction can have severe health consequences. Variceal bleeding associated with this disorder causes upper gastrointestinal bleeding, leading to substantial morbidity and mortality. We report the clinical transplantation of a deceased donor iliac vein graft repopulated with recipient autologous stem cells in a patient with extrahepatic portal vein obstruction.
Methods : a 10 year old girl with extrahepatic portal vein obstruction was admitted to the Sahlgrenska University Hospital in Gothenburg, Sweden, for a bypass procedure between the superior mesenteric vein and the intrahepatic left portal vein (meso Rex bypass). A 9 cm segment of allogeneic donor iliac vein was decellularised and subsequently recellularised with endothelial and smooth muscle cells differentiated from stem cells obtained from the bone marrow of the recipient. This graft was used because the patient's umbilical vein was not suitable and other strategies (eg, liver transplantation) require lifelong immunosuppression.
Findings : The graft immediately provided the recipient with a functional blood supply (25—30 cm/s in the portal vein and 40 mL/s in the artery was measured intraoperatively and confirmed with ultrasound). The patient had normal laboratory values for 9 months. However, at 1 year the blood flow was low and, on exploration, the shunt was patent but too narrow due to mechanical obstruction of tissue in the mesocolon. Once the tissue causing the compression was removed the graft dilated. We therefore used a second stem-cell populated vein graft to lengthen the previous graft. After this second operation, the portal pressure was reduced from 20 mm Hg to 13 mm Hg and blood flow was 25—40 cm/s in the portal vein. With restored portal circulation the patient has substantially improved physical and mental function and growth. The patient has no anti-endothelial cell antibodies and is receiving no immunosuppressive drugs.
Interpretation : An acellularised deceased donor vein graft recellularised with autologous stem cells can be considered for patients in need of vascular vein shunts without the need for immunosuppression (read more).

Transmaternal cell flow leads to antigen-experienced cord blood

Umbilical cord blood (UCB) is used for HSCT. It is known that UCB can comprise Ag-specific T cells. Here we question whether solely transmaternal cell flow may immunize UCB. Twenty-three female UCB samples were collected from healthy mothers and analyzed for minor histocompatibility Ag HY-specific responses. Forty-two of 104 tetramerpos T-cell clones, isolated from 16 of 17 UCB samples, showed male-specific lysis in vitro. Male microchimerism was present in 6 of 12 UCB samples analyzed. In conclusion, female UCB comprises HY-specific cytotoxic T cells. The immunization is presumably caused by transmaternal cell flow of male microchimerism present in the mother. The presence of immune cells in UCB that are not directed against maternal foreign Ags is remarkable and may explain the reported clinical observation of improved HSCT outcome with younger sibling donors (read more)

Surgical prevention and management of vascular complications of kidney transplantation

The main surgical changes in kidney procurement, preparation, and transplantation procedures occurred 20 years ago and were undertaken despite the inability to design randomized studies. The objective was to assess the evolution of vascular complications after kidney transplantation in a setting of surgical preventive measures in a historical series. A monocentric series of 3129 consecutive kidney transplantations performed over 3 decades was reviewed. The occurrence of arterial or venous thromboses, stenoses, and aneurysms was analyzed in relation with kidney procurement, preparation, and transplantation techniques. Vascular complications occurred in 13.5% of the recipients with a mean 3-year decrease in kidney graft function. The transplantation of a right kidney without renal vein extension, multiple renal arteries, ex vivo vascular repairs, and end-to-end arterial anastomoses were the unfavorable surgical vascular factors. It was possible to manage Transplant Renal Artery Stenosis (TRAS) nonsurgically in 80% of the cases. The prevention of vascular complications begins from the time of organ procurement by skilled surgeons. The aims of organ preparation are to evaluate the vascular risk, select the organs, and to simplify the anatomical constraints of vascular implantations. The three surgical steps of kidney transplantation are determinant in postoperative vascular complications and the duration of graft function (read more).

Chain Transplantation: Initial Experience of a Large Multicenter Program

We report the results of a large series of chain transplantations that were facilitated by a multicenter US database in which 57 centers pooled incompatible donor/recipient pairs. Chains, initiated by nondirected donors, were identified using a computer algorithm incorporating virtual cross-matches and potential to extend chains. The first 54 chains facilitated 272 kidney transplants (mean chain length = 5.0). Seven chains ended because potential donors became unavailable to donate after their recipient received a kidney; however, every recipient whose intended donor donated was transplanted. The remaining 47 chains were eventually closed by having the last donor donate to the waiting list. Of the 272 chain recipients 46% were ethnic minorities and 63% of grafts were shipped from other centers. The number of blood type O-patients receiving a transplant (n = 90) was greater than the number of blood type O-non-directed donors (n = 32) initiating chains. We have 1-year follow up on the first 100 transplants. The mean 1-year creatinine of the first 100 transplants from this series was 1.3 mg/dL. Chain transplantation enables many recipients with immunologically incompatible donors to be transplanted with high quality grafts (read more).

Citrulline Level Is a Potent Indicator of Acute Rejection in the Long Term Following Pediatric Intestinal/Multivisceral Transplantation

Citrulline has been advocated as a marker for acute cellular rejection (ACR) in intestinal transplantation; however, its significance as a forewarning in the long-term follow-up remains unknown. This study aimed to investigate the association between citrulline levels and the grading of ACR to establish a cutoff point that accurately predicts ACR beyond 3 months posttransplant in the pediatric patient population. During a 16-year period (1995–2011), a total of 13 499 citrulline samples were prospectively collected from 111 consecutive pediatric intestinal/multivisceral transplant recipients: 2155 were obtained concurrently with intestinal biopsies. There were 185 ACR episodes observed among 74/111 (67%) patients (median follow-up: 4.4 years). Citrulline levels were inversely proportional to the severity of ACR. Negative predictive values for any type of ACR (cutoff, 20 μmol/L) and moderate/severe ACR (cutoff, 10 μmol/L) were 95% and 99%, respectively. When patients were divided according to graft size, diagnostic accuracy using the same cutoff was identical. Similarly, subgroup analysis by the timing of citrulline measurement prior to biopsy varying from 1 to 7 days demonstrated comparable results. Citrulline is a potent indicator as a danger signal for ACR, being an exclusionary, noninvasive biomarker with excellent negative predictive values in the long term after pediatric intestinal/multivisceral transplant (read more).

Wednesday, July 18, 2012

Plasma cell densities and glomerular filtration rates predict renal allograft outcomes following acute rejection

The contribution of T cells and graft-reactive antibodies to acute allograft rejection is widely accepted, but the role of graft-infiltrating B and plasma cells is controversial. We examined 56 consecutive human renal transplant biopsies classified by Banff schema into T-cell-mediated (N = 21), antibody-mediated (N = 18), and mixed (N = 17) acute rejection, using standard immunohistochemistry for CD3, CD20, CD138, and CD45. In a predominantly African-American population (75%), neither Banff classification nor C4d deposition predicted the return to dialysis. Immunohistochemical analysis revealed CD3+ T cells as the dominant cell type, followed by CD20+ B cells and CD138+ plasma cells in all acute rejection types. Using univariate Cox Proportional Hazard analysis, plasma cell density significantly predicted graft failure while B-cell density trended toward significance. Surprisingly T-cell density did not predict graft failure. The estimated glomerular filtration rate (eGFR) at diagnosis of acute rejection also predicted graft failure, while baseline eGFR ≥6 months prior to biopsy did not. Using multivariate analysis, a model including eGFR at biopsy and plasma cell density was most predictive of graft loss. These observations suggest that plasma cells may be a critical mediator and/or an independently sensitive marker of steroid-resistant acute rejection (read more).

Monday, July 16, 2012

Hematologic, immunologic reconstitution, and outcome of 342 autologous peripheral blood stem cell transplantations after cryopreservation in a −80°C mechanical freezer and preserved less than 6 months

BACKGROUND: Controlled-rate freezing and storage in nitrogen is the standard technique for cryopreservation of peripheral hematopoietic progenitor cells (PHPCs) but presents high cost and dimethyl sulfoxide (DMSO) toxicity. Cryopreservation at −80°C, by uncontrolled rate freezing with only 3.5% DMSO, preserves the functional capacities of PHPCs, produces successful engraftment, and reduces toxicity during infusion.
STUDY DESIGN AND METHODS: Long-term hematopoietic and immunologic reconstitution for 342 autografts (311 adults, 31 children) after PHPCs were cryopreserved at −80°C was studied at 3, 6, and 12 months. The median (range) storage time of PHPCs cryopreserved was 1.7 (0.1-5.99) months.
RESULTS: Hemoglobin (Hb), white blood cells, and platelets (PLTs) reach normal values to trilineage at 12 months for 39% patients. Multivariate analysis shows a significant impact on CD34+ infused and on conditioning regimen for PLTs. Hb was influenced by growth factor administration at 3 months. Long-term recovery is also highly dependent on blood counts (Hb, PLT, and neutrophil) at start of high-dose chemotherapy. Only 43% of patients had reached normal lymphocyte values at 12 months after transplant, and a profound CD4+ T-lymphocyte deficit remained, as others reported.
CONCLUSION: Transplantation with PHPCs cryopreserved at −80°C for no more than 6 months is satisfactory for long-term hematopoietic and immunologic reconstitution, even if a profound CD4+ T lymphocyte deficit persists at 1 year. This easier and cheaper cryopreservation method also leads to successful engraftment (read more).

Sunday, July 15, 2012

Cell Population in Spleens During Antibody-Mediated Rejection: Pathologic and Clinical Findings.

BACKGROUND: In the treatment of refractory antibody-mediated rejection (AMR), splenectomy has been associated with surprisingly rapid recovery of renal function. The mechanism is still unclear. METHODS: We review 11 recipients, who underwent rescue splenectomy (RS) as a treatment of AMR within 3 months after kidney transplantation. At transplantation, all patients had undergone desensitization for initially positive crossmatch to their prospective donors. The cellular populations of the spleen were analyzed by immunohistochemistry. For comparison, we obtained spleen specimens from eight controls who were nontransplantation patients. RESULTS: Rejection occurred in all the patients early after transplantation (mean [SD], 7.1 [5.7] days). One graft was lost 4 weeks after kidney transplantation. A significantly higher number of plasma cells (PCs) (P=0.049) and lower number of T and B lymphocytes (P=0.02 and P=0.005, respectively) were detected in the RS group compared with the control group. By analyzing the PC variations in the RS group, significantly lower numbers of PCs were detected in the spleens of patients who received rituximab before splenectomy (P=0.0004). In contrast, a higher number of PCs were found in patients (n=3) who did not respond to splenectomy and subsequently underwent bortezomib treatment and recovered their renal function (P=0.02). CONCLUSIONS: Splenectomy may reverse AMR by debulking PCs. Our analysis suggests that patients with a very high load of PCs may not be rescued by splenectomy alone and may need additional treatments (read more)

Friday, July 13, 2012

Cytomegalovirus exposure, immune exhaustion and cancer occurrence in renal transplant recipients.

The role of Cytomegalovirus (CMV) in carcinogenesis is controversial. We studied whether CMV may contribute to cancer occurrence in renal transplant recipients. We studied a prospective cohort of 455 consecutive patients who received a kidney transplant between January 1995 and December 2006. All cancers and types of cancers were assessed. Lymphocyte phenotype and cytokines production were analysed according to CMV status in a subset population of this cohort. Mean follow-up was 84 ± 29 months. One hundred and nineteen cancers (26.2%) occurred during the study follow-up. There was a higher cumulated incidence of cancers in CMV-exposed patients (30.4% vs. 20%; P = 0.018). Mean time to cancer occurrence was shorter in CMV-exposed patients than in CMV-naïve patients (4.7 ± 2.6 vs. 6.7 ± 2.8; P = 0.001). Cox regression analysis revealed that both pretransplant CMV exposure (HR, 1.83; 95% CI, 1.17-2.88; P = 0.009) and post-transplant CMV replication (HR, 2.17; 95% CI, 1.02-4.59; P = 0.044) were risk factors for cancer. Among CD8+ T cells, exhausted T cells assessed as CD57+CD28- were expanded in CMV-exposed patients (26 ± 20 vs. 9 ± 8%; P < 0.0001), whereas CD8+CD57+IL2- cells were more frequent in CMV-exposed patients. Our results highly suggest that CMV increases the risk of cancer after transplantation (read more)

Thursday, July 12, 2012

Persistently low transplantation rate of ABO blood type O and highly sensitised patients despite alternative transplantation programs

ABO blood type O and highly sensitised patients have the smallest chance to receive kidney transplantation. Do alternative donation programs increase this chance? In the period studied: 2323 patients were enlisted on the Rotterdam waiting list for a renal transplantation: 435 patients still waiting (WL), 464 delisted without transplantation (DWT). 1424 received deceased donor (DD, 535) or living donor (LD, 889, including 204 alternative) transplantation. Alternative LD programs in our centre are: paired kidney-exchange, altruistic with domino-paired donation and ABO-incompatible donation (ABOi). Compared to populations not transplanted, blood type O recipients are significantly underrepresented in DD and all LD transplantation populations, except the ABOi program. Highly sensitised patients are overrepresented in DD, but underrepresented in all LD transplantation populations. The high transplantation rate of highly sensitised patients was the result of Eurotransplant Acceptable mismatch program (AM). The LD ABOi and DD AM programs are the only alternative donation programs favourable for patients with low chances. While the contribution of direct LD transplantations will increase in time, the relative success rate of low-chance patients will decrease. Beside increasing LD ABOi transplantation, a new DD allocation model favouring both highly immunised and blood type O patients is essential (read more).

Sunday, July 8, 2012

Platelets Present Antigen in the Context of MHC Class I

Platelets are most recognized for their vital role as the cellular mediator of thrombosis, but platelets also have important immune functions. Platelets initiate and sustain vascular inflammation in many disease conditions, including arthritis, atherosclerosis, transplant rejection, and severe malaria. We now demonstrate that platelets express T cell costimulatory molecules, process and present Ag in MHC class I, and directly activate naive T cells in a platelet MHC class I-dependent manner. Using an experimental cerebral malaria mouse model, we also demonstrate that platelets present pathogen-derived Ag to promote T cell responses in vivo, and that platelets can be used in a cell-based vaccine model to induce protective immune responses. Our study demonstrates a novel Ag presentation role for platelets (read more).

Terminally Differentiated CD8+ Temra Cells Are Associated With the Risk for Acute Kidney Allograft Rejection

End-stage renal disease (ESRD) is associated with T-cell dysregulation, leading to a variable degree of lymphopenia and increased T-cell differentiation. This may cause a relevant reduction in T-cell immunity, yielding a lowered risk for acute rejection (AR) of kidney allografts.
Methods: Before kidney transplantation, circulating CD4+ and CD8+ T-cell differentiation was established by determining the frequency of naive T cells, central memory and effector memory T cells, and the highly differentiated CD8+ Temra cells. In addition, the frequency of differentiated T cells without expression of the costimulatory molecule CD28 was measured.
Results: In 47 patients of the 185 patients included, a biopsy-proven AR occurred. Compared with healthy controls, T cells of patients with ESRD were significantly more differentiated. Patients with AR showed the least signs of T-cell dysregulation with significantly more T cells, more naive T cells, and less terminal differentiation of memory T cells compared with nonrejecting patients. After multivariate analysis, only the frequency of terminally differentiated CD8+ Temra cells (per percent, 4% decrease of risk [P=0.006]; per tertile, 34% decrease in risk [P=0.002]) and the number of human leukocyte antigen mismatches (per mismatch, 33% [P=0.005]) predicted the risk for AR. Functional analysis showed that CD8+ Temra cells have a highly proinflammatory and cytotoxic profile. In vitro T-cell proliferation assays did not reveal a suppressor function of these cells.
Conclusions: Advanced ESRD-related T-cell dysregulation that is associated with a relative increase of terminally differentiated CD8+ Temra cells protects against AR after kidney transplantation (read more).

Telomere shortening and karyotypic alterations in hepatocytes in long-term transplanted human liver allografts

The long-term fate of aged liver allografts in young recipients who received grafts from older donors is unknown. We evaluated graft aging by analyzing hepatocytic telomere length and karyotypic changes. Seventeen pediatric individuals who underwent living-donor liver transplantation for congenital biliary diseases were selected. At a median of 10.4 years post-transplant, ten had tolerated grafts with weaned off immunosuppressants, and seven had idiopathic post-transplantation hepatitis. Fluorescence in situ hybridization was used to evaluate the telomere signal intensity (TI) and karyotypic changes. First, we measured predictive age-dependent TI decline with regression analysis of donor livers. The mean TI at the earliest (within a year) and latest biopsies was significantly lower than the predicted TI of the studied allografts. With univariate analysis, a higher abnormal karyotype ratio in the donor liver was correlated with development of idiopathic post-transplantation hepatitis. With multivariate analysis that included clinical parameters, a greater TI decline at the earliest biopsy was correlated with the development of idiopathic post-transplantation hepatitis. In conclusion, graft aging as measured by TI decline and donor abnormal karyotype ratio was associated with idiopathic post-transplantation hepatitis of long-term transplanted liver allografts (read more).

Significance of low-level DSA detected by solid-phase assay in association with acute and chronic antibody-mediated rejection

We sought to clarify the controversial issue of whether detecting low-level anti-donor-specific HLA antibody (HLA-DSA) by single-antigen flow-bead assay (SAFB) may have a potential role in reducing acute and chronic antibody-mediated rejection (AMR). We retrospectively studied the preoperative serum of ABO-compatible living kidney transplantation recipients transplanted between 2001 and 2004 by SAFB using a Luminex platform. HLA-DSA was detected only by SAFB in 24 patients, although all of them showed negative T-cell and B-cell complement-dependent cytotoxicity (CDC) crossmatches. The HLA-DSA patients went on to have surprisingly high levels of acute and chronic AMR despite being only weakly sensitized (acute AMR, 33.3%; chronic AMR, 41.7%). After 2005, we implemented SAFB routinely and any patient having a positive HLA-DSA was considered to be a desensitization candidate. The 52 patients found to have HLA-DSA underwent kidney transplantation after prior treatment with a single dose of rituximab (RIT) and three or four sessions of double-filtration plasmapheresis (DFPP) in addition to regimens commonly used between 2001 and 2004. After 2005, there was a significant reduction in the occurrence of acute and chronic AMR (acute AMR, 4.7%, P < 0.001; chronic AMR, 4.7%, P < 0.001). The 5-year graft survival rate also improved after implementing SAFB (83.3–98.1%, P = 0.032). The RIT/DFPP-induction protocol may improve graft survival even in patients with low-level DSA (read more).

Thursday, July 5, 2012

Identification and therapeutic management of highly sensitized patients undergoing renal transplantation.

Sensitization is generally referred to as the development of alloantibodies, specifically anti-human leukocyte antigen (HLA) immunoglobulin G (IgG) antibodies, most commonly caused by pregnancy, blood transfusion or a previous transplant. Despite being a well known phenomenon, there has not been a general consensus on its definition, monitoring or management. Today, 25% of the patients waitlisted for kidney transplant in the US have a panel reactive antibody (PRA) of >10% while, in the Eurotransplant zone, 14% have a PRA of >5%. Sensitized patients have more difficulty in finding a well HLA-matched donor, and have a higher risk of experiencing longer waiting times, more rejection episodes and eventually inferior long-term graft or patient survival. We review the currently available strategies in identifying and managing highly sensitized patients undergoing renal transplantation. We discuss the progress and limitations in laboratory techniques to elaborate on challenges in defining sensitized patients. The main management options (i.e. the Acceptable Mismatch Program, donor exchange programmes and the desensitization approach) and their mechanisms, related policies, advantages and outcomes, as well as medications and methods being investigated, are updated. In addition, particular emphasis is given to sensitization prevention, a practice that is neglected with our increasing ability to suppress the immune system (read more)

Wednesday, July 4, 2012

Preformed Donor HLA-DP-Specific Antibodies Mediate Acute and Chronic Antibody-Mediated Rejection Following Renal Transplantation

Donor-specific HLA alloantibodies may cause acute and chronic antibody-mediated rejection (AMR) and significantly compromise allograft survival. The clinical relevance of antibodies directed against some HLA class II antigens, particularly HLA-DP, is less clear with conflicting reports on their pathogenicity. We report two patients with high levels of pretransplant donor-specific HLA-DP antibodies who subsequently developed recurrent acute AMR and graft failure. In both cases, there were no other donor-specific HLA alloantibodies, suggesting that the HLA-DP-specific antibodies may be directly pathogenic (read more)

The humanized anti-HLA-DR moAb, IMMU-114, depletes APCs and reduces alloreactive T cells: implications for preventing GVHD

In contrast to the conventional immunosuppressive agents and nonselective T-cell-depleting antibodies, selective depletion of donor alloreactive T cells and/or host APCs, particularly DCs, represents a novel approach that can effectively control GVHD with less or no impairment of T-cell-mediated antiviral and GVL immunity. Here we report that IMMU-114, a humanized anti-human leukocyte antigen-DR (HLA-DR) moAb, efficiently depleted human PBMCs of all APCs, including B cells, monocytes, myeloid DC type-1 (mDC1), mDC2 and plasmacytoid DCs (pDCs). Early and late apoptosis of mDC1, mDC2 and pDCs, and late apoptosis of all APC subsets, were increased by IMMU-114 treatment. Although IMMU-114 had little, if any, effect on the survival and apoptosis of non-B lymphocytes (>80% of which are T cells and ~1-2% of T cells express HLA-DR), it selectively inhibited the proliferation of purified HLA-DR+ T cells rather than HLA-DR T cells. As a consequence, IMMU-114 treatment resulted in suppressed T-cell proliferation and reduced CD25+ alloreactive T cells in allogeneic MLRs. Given the critical roles of APCs and alloreactive T cells in the pathogenesis of GVHD, these results suggest that IMMU-114 may have therapeutic potential against GVHD (read more)

Patterns of De Novo Allo B Cells and Antibody Formation in Chronic Cardiac Allograft Rejection After Alemtuzumab Treatment

Even though the etiology of chronic rejection (CR) is multifactorial, donor specific antibody (DSA) is considered to have a causal effect on CR development. Currently the antibody-mediated mechanisms during CR are poorly understood due to lack of proper animal models and tools. In a clinical setting, we previously demonstrated that induction therapy by lymphocyte depletion, using alemtuzumab (anti-human CD52), is associated with an increased incidence of serum alloantibody, C4d deposition and antibody-mediated rejection in human patients. In this study, the effects of T cell depletion in the development of antibody-mediated rejection were examined using human CD52 transgenic (CD52Tg) mice treated with alemtuzumab. Fully mismatched cardiac allografts were transplanted into alemtuzumab treated CD52Tg mice and showed no acute rejection while untreated recipients acutely rejected their grafts. However, approximately half of long-term recipients showed increased degree of vasculopathy, fibrosis and perivascular C3d depositions at posttransplant day 100. The development of CR correlated with DSA and C3d deposition in the graft. Using novel tracking tools to monitor donor-specific B cells, alloreactive B cells were shown to increase in accordance with DSA detection. The current animal model could provide a means of testing strategies to understand mechanisms and developing therapeutic approaches to prevent chronic rejection (read more).

Monday, July 2, 2012

Clinical and pathological analysis of transplant glomerulopathy cases

Transplant glomerulopathy (TG) is involved in the criteria of chronic active antibody-mediated rejection (c-AMR) in Banff ‘09 classification.
Patients : TG was diagnosed in 58 renal allograft biopsy specimens (BS) from 37 renal transplant patients.
Results : Among 58 BS of TG, 27 BS were mild (cg1), 16 were moderate (cg2), and 15 were severe (cg3). Peritubular capillaritis was present in 49 (84%), transplant glomerulitis was seen in 47 BS (81%), interstitial fibrosis and tubular atrophy in 47 (81%) and the thickening of the peritubular capillary (PTC) basement membrane (PTCBM) in 44 (76%), and interstitial inflammation was present in 26 BS (45%). C4d deposition in PTC was presented in 32 BS (55%). The circulating anti-HLA alloantibody was detected in 38 times (76%), of which 27/38 (54%) were donor-specific antibodies. Deterioration of renal allografts’ function after biopsies was seen in 12 patients (32%) with six of them lost their graft.
Conclusions : We suggest that histopathological changes of TG accompanying by transplant glomerulitis, peritubular capillaritis, the thickening of the PTCBM, and circulating anti-HLA antibodies might indicate c-AMR, even if C4d deposition in PTC is negative. The prognosis of the graft exhibiting TG was relatively good under the present immunosuppression protocol in short time (read more).

Acute vascular rejection after renal transplantation and isolated v-lesion

Histopathological changes of acute vascular rejection (AVR) are characterized by intimal arteritis and transmural arteritis. According to the Banff 1997 classification, the quantitative criteria for intimal arteritis (v score) are classified: v0, v1, v2, and v3. According to Banff ‘09 classification, AVR may fall into one of four categories: acute T cell-mediated rejection (ATMR) Type IIA, ATMR Type IIB, ATMR Type III, and acute antibody-mediated rejection (AAMR) Type III.
Both cellular and humoral immunity play roles in vascular rejection, and in some cases, AVR may be provoked by anti-donor antibodies. Anti-rejection therapies were effective in most of the v1 cases but were less effective in the v2 cases and were ineffective in the v3 cases. Some reports have indicated that the prognosis of grafts exhibiting AVR is poor, but in our series, the outcome of AVR was relatively good using recent immunosuppressive protocols.
A definition for “isolated v-lesion” was originally characterized by arteritis with minimal interstitial inflammation and tubulitis. The 11th Banff conference was concluded that “isolated v1-lesions” comprised two types, T cell-mediated rejection and injury, and did not have any independent prognostic significance. However, we speculate that “isolated v-lesion” might be regarded as AAMR and ATMR (read more).

Significance of C4d deposition in antibody-mediated rejection

The C4d staining as a special tissue marker for humoral immunity has served criteria of pathological diagnosis for antibody-mediated rejection (ABMR) in Banff classification since 2003. However, the sensitivity and specificity of C4d staining have been questioned, and recently, C4d-negative ABMR has been more focused in renal allograft pathology. The aim of this study was to make certain of C4d staining for ABMR that was diagnosed by clinical and morphological findings. C4d staining was employed by immunofluorescence. This study included 14 patients with acute ABMR and 16 with chronic active ABMR. Eight of acute ABMR were ABO-blood-type-incompatible renal transplantation (ABOinRTx) pre-treated by DFPP and splenectomy or rituximub. In acute ABMR after ABOinRTx, C4d staining along peritubular capillary (PTC) was positive in five of them (62.5%). Only one graft biopsy of five acute ABMR with donor-specific antibody (DSA) showed C4d positive. We assembled 16 graft biopsies showing typical transplant glomerulopathy and thickened PTC basement membrane with peritubular capillaritis as a suspicious pathological chronic active ABMR. Four of eight DSA-positive patients were C4d negative in PTC; however, three of four DSA-positive and C4d-negative patients in PTC chronic active ABMR were C4d positive in only glomerular capillaries. C4d positivity could not come to a specific marker of ABMR diagnosing based on clinically and ordinary morphological findings (read more).