Saturday, January 28, 2012

Quantifying the benefit of early living-donor renal transplantation with a simulation model of the Dutch renal replacement therapy population

Background. Early living-donor transplantation improves patient- and graft-survival compared with possible cadaveric renal transplantation (RTx), but the magnitude of the survival gain is unknown. For patients starting renal replacement therapy (RRT), we aimed to quantify the survival benefit of early living-donor transplantation compared with dialysis and possible cadaveric transplantation and to estimate the population benefit from increasing the early transplantation rate. Methods. We used a decision-analytic computer-simulation model, with a lifetime time horizon, simulating patients starting RRT, using data from the Dutch End-Stage Renal Disease Registry and published data. We compared the (quality adjusted) life expectancy (LE) of ‘early living-donor RTx’ and ‘dialysis’ (with possible cadaveric RTx if available). Results. LE and quality-adjusted LE benefits of the early living-donor RTx compared with the dialysis strategy for 40-year-old patients ranged from 7.5 to 9.9 life years (LYs) [6.7–8.8 quality-adjusted life years (QALYs)] depending on the primary renal disease. For 70-year-old patients, the benefit was 4.3–6.0 LYs (4.3–6.0 QALYs). Increasing the early transplantation rate from currently 5.8 to 22.2% (the highest in Europe) would increase average LE by 1.2 LYs and total LE for annual incident cases in the Netherlands by 1800 LYs. Conclusions. Efforts to increase early living-donor RTx could potentially substantially increase LE for patients starting RRT, especially in younger patients (read more).

Renal transplant recipients have elevated frequencies of circulating myeloid-derived suppressor cells

Cancer, particularly cutaneous squamous cell carcinoma (SCC), is a major cause of mortality in renal transplant recipients (RTRs). Myeloid-derived suppressor cells (MDSC) play a central role in suppressing cancer immunosurveillance but their potential mobilisation in RTRs and levels relative to those of other immunoregulatory dendritic cell (DC) populations have not been analysed. Methods. The circulating frequencies of MDSC and DC were analysed by multicolour flow cytometry in immunocompetent patients without (n = 13) or with (ICI-SCCPos, n = 14) current SCC, normal donors (NDs, n = 34), chronic kidney disease patients (CKD patients, n = 22) and RTRs (n = 31). Results. Compared to NDs, RTRs had significantly elevated levels of both CD14Neg and CD14Pos MDSC subsets (P < 0.001), while CKD patients and ICI-SCCPos had significantly elevated levels of only the CD14Neg-MDSC subset. DC frequencies were significantly decreased in RTRs and CKD patients but were at normal levels in ICI-SCCPos. The MDSC/DC ratio was significantly elevated (P < 0.05) in RTRs (median = 5.7), CKD patients (median = 3.2) and ICI-SCCPos (median = 3.5) relative to NDs (median = 0.7). The use of immunosuppressive drugs in CKD patients and past/current occurrence of SCC in RTRs was associated with significantly increased CD14Neg-MDSC frequencies. MDSC enriched from RTRs, when co-cultured with activated NDs T cells significantly suppressed extracellular IL-10 levels and can, when activated with formyl-methionyl-leucyl-phenylalanine, inhibit T-cell proliferation. Conclusions. RTRs, CKD patients and ICI-SCCPos have increased MDSC frequencies and MDSC/DC ratios. These changes may impact on cancer immunosurveillance. Therefore, MDSC represent both a potential therapeutic target and prognostic marker in these patients, with respect to the development of SCC and other malignancies (read more).

Uremia induces functional incompetence of bone marrow-derived stromal cells

[A study with implications for autologous MSC therapy in kidney transplantation]

Chronic kidney disease (CKD) is associated with increased risk for cardiovascular diseases (CVD). We hypothesized that inadequate angiogenic response in uremic patients could result from dysfunction of bone marrow-derived stromal cells [mesenchymal stem cells (MSCs)]. Methods. We investigated whether MSCs are functionally competent in uremia induced by partial kidney ablation in C57Bl/6J mice. Results. Uremic MSCs showed decreased expression of vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)1 and stromal cell-derived factor (SDF)-1α, increased cellular senescence, decreased proliferation, defects in migration in response to VEGF and SDF-1α and in vitro tube formation. Interestingly, the expression of fibroblast-specific protein-1 was higher in uremic MSCs. Uremia decreased hypoxia-inducible factor-1α, VEGF and VEGFR1 expression under hypoxia and Akt phosphorylation in both basal and VEGF-stimulated states. A diminished mitogenic effect on endothelial proliferation was observed in conditioned media from uremic MSCs. In addition, intravital microscopic analysis showed decreased angiogenesis in uremic MSCs. Conclusion. These results clearly demonstrate the functional incompetence in MSCs under uremic conditions and may significantly contribute to the disproportionately high risk for CVD in patients with CKD (read more).

Outcome of the living kidney donor

Renal transplantation from living kidney donors is still relatively marginal in most of the European countries. However, this source of kidney grafts may help to overcome in part the organ donor shortage of cadaveric donors. The living donor strategy implies correct and objective information about donation risks and completely free acceptance of the living candidate of the donation. In this paper, we reviewed the consequences of kidney donation on the living donor health, considering very short term (linked to the surgery), short term (effect of nephrectomy on glomerular filtration rate) and long term (risk of mortality, chronic kidney disease, proteinuria and hypertension) consequences of kidney donation (read more).

Thursday, January 26, 2012

A Simplified Donor Risk Index for Predicting Outcome After Deceased Donor Kidney Transplantation

Background. We sought to determine the deceased donor factors associated with outcome after kidney transplantation and to develop a clinically applicable Kidney Donor Risk Index.
Methods. Data from the UK Transplant Registry on 7620 adult recipients of adult deceased donor kidney transplants between 2000 and 2007 inclusive were analyzed. Donor factors potentially influencing transplant outcome were investigated using Cox regression, adjusting for significant recipient and transplant factors. A United Kingdom Kidney Donor Risk Index was derived from the model and validated.
Results. Donor age was the most significant factor predicting poor transplant outcome (hazard ratio for 18–39 and 60+ years relative to 40–59 years was 0.78 and 1.49, respectively, P<0.001). A history of donor hypertension was also associated with increased risk (hazard ratio 1.30, P=0.001), and increased donor body weight, longer hospital stay before death, and use of adrenaline were also significantly associated with poorer outcomes up to 3 years posttransplant. Other donor factors including donation after circulatory death, history of cardiothoracic disease, diabetes history, and terminal creatinine were not significant. A donor risk index based on the five significant donor factors was derived and confirmed to be prognostic of outcome in a validation cohort (concordance statistic 0.62). An index developed in the United States by Rao et al., Transplantation 2009; 88: 231–236, included 15 factors and gave a concordance statistic of 0.63 in the UK context, suggesting that our much simpler model has equivalent predictive ability.
Conclusions. A Kidney Donor Risk Index based on five donor variables provides a clinically useful tool that may help with organ allocation and informed consent (read more).

Pretransplant Immune Regulation Predicts Allograft Outcome: Bidirectional Regulation Correlates With Excellent Renal Transplant Function in Living-Related Donor-Recipient Pairs

Background. Tolerance to noninherited maternal antigens has provided clinical advantage when kidney transplants are exchanged between siblings but not when mother herself is the donor. This paradox prompted us to revisit the “two-way” hypothesis of transplant tolerance—that the immune status of both the organ recipient and the organ donor critically influences allograft outcome.
Methods. We obtained peripheral blood monocyte cells from 29 living donor-recipient pairs before transplant and used the trans-vivo-delayed type hypersensitivity assay to measure immune regulation in both the recipient antidonor and donor antirecipient directions.
Results. We found preexisting bidirectional regulation in all human leukocyte antigen (HLA)-identical sibling pairs tested (7/7), and one half (9/18) of the HLA haploidentical pairs. No significant regulation was found in four control living unrelated and two HLA haploidentical living-related donor recipient pairs, whereas unidirectional regulation was found in the remaining seven haploidentical pairs. Of the nine HLA haploidentical transplants with unidirectional or no pretransplant regulation, seven had an acute rejection episode and four of these experienced graft loss. In contrast, of the nine HLA haploidentical transplants with bidirectional regulation, only one had rejection. Renal function for the latter group was similar to HLA-identical kidney recipients at 3 years posttransplant. Significantly (P<0.05) lower mean serum creatinine values in bidirectional regulators were noted as early as 4 months and this difference became more pronounced at 12 (P<0.005) and 36 months (P<0.0001).
Conclusions. Contrary to the belief that only the recipient's immune status matters, the data indicate that pretransplant immune status of both donor and recipient influence posttransplant outcome (read more).

Accommodation: Does it Apply to Human Leukocyte Antigens?

The term “accommodation” was invoked to describe endothelial cell resistance to antibody-mediated rejection after ABO-incompatible kidney or experimental xenograft transplantation. Currently, there is much interest in how to achieve successful human leukocyte antigen (HLA)-incompatible allograft transplantation in HLA-sensitized patients and how to treat antibody-mediated rejection after ABO-compatible HLA-incompatible allotransplantation. The term “accommodation” is often used interchangeably to describe patients who have donor-specific ABO or HLA alloantibodies in the absence of damage to their allograft. Here, we suggest that there are important differences between the immune responses to protein versus carbohydrate antigens and that graft HLA molecules may respond differently to antibodies (and antibody isotypes) than ABO antigens. Neither the mechanisms nor a phenotype of accommodation have been defined fully. Further research is needed to define mechanisms of both resistance and susceptibility to antibody-mediated injury and to predict under which circumstances allograft accommodation may occur (read more).

Wednesday, January 25, 2012

ABO-incompatible kidney transplantation using regenerative selective immunoglobulin adsorption.

Background: ABO-incompatible (ABOi) kidney transplantation is an established procedure relying on the removal of donor-specific isoagglutinine antibodies as part of the recipient preconditioning. At present, current protocols using immunoadsorption apply a single-use selective carbohydrate isoagglutinine adsorber. A regenerative and selective immunoglobulin immunoadsorption could be an alternative but has not been reported for ABOi transplantation.
Methods: Eight patients were treated with the commonly used isoagglutinine carbohydrate epitope adsorber and seven with a regenerative polyclonal sheep anti-immunoglobulin adsorber as part of the preconditioning for ABOi kidney transplantation. An IgG-isoagglutinine titer of less or equal 1:4 qualified for transplantation. Treatment safety, efficiency, length of desensitization, number of postoperative immunoadsorptions, and allograft outcome were retrospectively compared.
Results: With the use of the immunoglobulin adsorber the median initial isoagglutinine IgG titers of 1:64 (range 1:32-1:256) were lowered to the target of 1:4 preoperatively with a mean of 6.2 immunoadsorptions (range 5-11). Mean IgG/IgM titer step reduction per IA was 1.98/1.21 for (range 0-4/0-4) and mean titer step rebound 1.31/0.82 (range 0-4/0-3), respectively. The number of immunoadsorptions and length of desensitization was not different from the use of the specific isoagglutinine adsorbers. After transplantation, no rejection occurred and only one postoperative immunoadsorption was necessary. No adverse events in relation to immunoadsorption were observed. Graft function was comparable to the isoagglutinine adsorber group.
Conclusion: These data suggest that ABOi kidney transplantation can be performed safely and effectively with a selective regenerative immunoglobulin immunoadsorber (read more)

HLA and pharmacogenetics : a quick summary

  • HLA-B*13:01 (present in about 2 to 20% of Chinese persons, 1.5% of Japanese persons, 1 to 12% of Indians, and 2 to 4% of Southeast Asians but is largely absent in Europeans and Africans) is associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy (OR 20.5) (ref)
  • HLA-B*15:02/A*31:01 induces fatal skin reactions (Stevens-Johnson syndrome or toxic epidermal necrolysis) to carbamazepine and phenytoin/fosphenytoin in 10% (ref)
  • HLA-B*57:01 induces fatal hypersensitivity reactions to abacavir in 5-8% (ref) and liver injury due to flucloxacillin (ref)
  • HLA-B*58:01 induces  fatal skin reactions (Stevens-Johnson syndrome or toxic epidermal necrolysis) to allopurinol (ref)
  • HLA-C*04:01 increase the risk for Stevens-Johnson syndrome (OR = 17.5) and all hypersensitivity phenotypes (OR = 2.6) to nevirapine in 2.6% Malawian HIV patients (ref)
  • HLA-DRB1*07 and DQA1*02 induces reaction to ximelagatran in 5-7% (ref)
  • HLA-DRB1*07:01 induces a a higher incidence of hypersensitivity (OR = 1.64) and anti-asparaginase antibodies (OR = 2.92) (ref)
  • HLA-B*35:05 induces benznidazole related cutaneous reaction (45.5% vs 15.4%, P = .033) (ref)

HLA and autoimmune disease association : a quick summary

Celiac disease :
  • CELIAC1 : heterodimers "DQ2" (DQA1*05-DQB1*02) or "DQ8" (DQA1*03-DQB1*03:02). Gradient of RR : DQB1*02/*02 or DQB1*02/*0302 > DQ2 > DQ8 > DQB1*02 (DQA1*05 negativo) >> DQ2/DQ8/DQB1*02 negative
  • DQ2/DQ8/DQB1*02 found in 30% of population => poor positive predictive value (1/30), very high negative predictive value
  • other predisposing genes : CELIAC2, CELIAC3/CTLA4, CELIAC4/MYO9B
  • the risks of celiac disease autoimmunity and celiac disease by the age of 5 years were 11% and 3%, respectively, among children with a single DR3–DQ2 haplotype, and 26% and 11%, respectively, among those with two copies (DR3–DQ2 homozygosity). In the adjusted model, the hazard ratios for celiac disease autoimmunity were 2.09 (95% confidence interval [CI], 1.70 to 2.56) among heterozygotes and 5.70 (95% CI, 4.66 to 6.97) among homozygotes, as compared with children who had the lowest-risk genotypes (DR4–DQ8 heterozygotes or homozygotes). Residence in Sweden was also independently associated with an increased risk of celiac disease autoimmunity (hazard ratio, 1.90; 95% CI, 1.61 to 2.25) (ref)
Type 1 diabetes mellitus :
  • haplotypes DRB1*03:01-DQA1*05:01-DQB1*02:01 or DRB1*04:01-DQA1*03:01-DQB1*03:02
  • RR in double heterozygotes = 20-40 > DR3 homozygotes  or DR4 homozygotes
  • odds ratio (OR) according to "diplotypes" (i.e. combinations of haplotypes) :

  • non DR-DQ HLA alleles predispose (A*24, B*39, B*18) or protect (B*27, A*01, A*11, A*31) (typing not recommended)
  • other genes : INS/IDDM2 VNTR, PTPN22/Lyp, CTLA4, IL2RA, IFIH1, CLEC16A, PTPN2, CYP27B1
Rheumatoid arthritis  :
  • prevalence = 0.5-1% worldwide (commonest autoimmune disease); M:F ratio 1:3
  • position 70-74 in HVR3 of HLA-DRB1 alleles : predisposing shared epitope (*01:01, *01:02, *04:01, *10:01, *14:02)) or   protective (*01:03, *04:02, *11:02, *11:03, *13:01, *13:02)
  • DRB1*03 correlates with lack of anti-CCP autoAb
  • other predisposing genes :  PTPN22/Lyp C1858T,  CTLA4, PADI4, MIF, TRAF1-C5, 6q23
Juvenile idiopathic arthritis (JIA) :
  • A*02 predisposes to early-onset JIA
  • B27 predisposes to enthesitis-associated JIA
  • DRB1*01, *08, *11, *13, DPB1*02 and DQB1*04 predispose to oliogoarticular JIA, while DRB1*04 and *07 protect from it
  • DRB1*08 and DPB1*03 predispose to polyarticular RF-negative JIA
  • DRB1*04, DQA1*03 and  DQB1*03 predispose to polyarticular RF-positive JIA
  • DRB1*01 and DQA1*0101 predispose to psoriatic JIA
  • non-HLA genes : TNFA-857A/G, MIF, SLC11A1, PTPN22
Ankylosing spondylitis / Bechterew disease and reactive arthritis :
  • all B27 alleles other than *27:06 (Sardinia) and *27:09 (South-East Asia) (OR > 100; PPV : 5%), B60 (OR 3.6), and DRB1*01
  • non-HLA genes : IL-1 family, CYP2D6, CARD15/NOD2, ANKH, ARTS1 and IL23R.
Uveitis :
  • acute anterior uveitis : B27 (expecially HLA-B*2705)
  • Behçet disease : B51
  • birdshot-like chorioretinopathy : A29 (RR = 50-250)
  • glaucomacyclitic crisis (Posner-Schlossman syndrome) : B54
  • pars-planitis : DR15
  • juvenile arthritis-related uveitis : DPB1*0202
  • tubulointerstitial nephritis and uveitis : DRB1*01:02 and DQA1*01
  • Vogt-Koyanagi-Harada syndrome : DR1 and DR4 in Caucasians and DRB1*04:05 in Asia
Behçet disease : B*510101 (RR = 6-10)
Multiple sclerosis :
  • "HLA-DR15" haplotype :
  1. DRB1*15:01, DRB5*01:01, DQA1*01:02, DQB1*06:02) and B18 (OR 2.6 or OR 6.2)
  2. DRB1*03:01 (OR = 1.4)
  • HLA-A*02:01; B*44:02; C*05:01 is a protective haplotype (OR : 0.2)
Myasthenia gravis : B8, B7, DR3 in Caucasians
  • DR9, DR13, DQ3, B12 and A10 in Japanese
  • HLA-DRB1*16,-DRB1*14 and -DQB1*05 with MuSK-MG (ref)
  • HLA A1-B8-DR3 haplotype in female patients with thymus hyperplasia and early onset MG, while HLA B7-DR2 haplotype was found in late onset MG (ref1, ref2). HLA-DQB polymorphism has also been linked to MG in earlier studies (ref). More recently, associations betweenHLA-DRB1*14, HLA-DRB1*16 and DQ5 have been observed with the small MuSK-MG subgroup in two different studies (ref1, ref2).
Löfgren's syndrome : DRB1*03

Takayasu's arteritis : B*52
  • DQA1*01:02-DQB1*06:02 haplotype (in combination with DRB1*15:01 in Caucasians); more severe in homozygous
  • DQB1*03:01 worsens
  • DQB1*05:01 and *06:01 protect
  • non-HLA genes : hypocretin/orexin
Psoriasis :
  • B13, B57, B37, B39, C*06:02 (RR = 2-5 in homozygous), DR7 and DR4
  • psoriatic arthritis : B27 (interphalangeal), B38 and B39 (peripheral joints), DR4 (symmetric) and DR7
Fetal neonatal alloimmune thrombocytopenia (FNAIT) :  the immune-dominant antigen leading to severe FNAIT is the human PLT antigen (HPA)-1, whose polymorphism constitutes an epitope for human leukocyte antigens (HLAs) DRB3*0101 and DRB4*01:01

Moyamoya angiopathy (MMA) : HLA-DRB1*03, DRB1*13

Parkinson's disease (PD) : HLA-DRB1*04

Primary biliary cirrhosis (PBC) :
  • HLA-DRB1*08 (P=1.59 × 10−11), HLA-DRB1*14, and  the DPB1 association (DPB1*03:01; P=9.18 × 10−7) are predisposing risk alleles
  • HLA-DRB1*11 is protective (P=1.42 × 10−10) (ref)
ANCA-associated vasculitis (AAV) : HLA-DRB1*0405 might be an independent risk factor for the poor response to treatment and the deterioration of renal function, whereas DPB1*0402 might be an independent risk factor for all-cause mortality (ref).

Immune-mediated bone marrow aplasia : HLA-DR15 allele in patients with MDS appeared to be associated with a good response to immune-suppressive therapy, suggesting that this allele may be a specific predisposing factor for the development of immunemediated bone marrow failure (ref). Secondary graft failure rate at 2 years was lower in patients who were HLA DR15+ (hazard ratio = 0.46, P = .01) (ref).

Chronic beryllium disease (CBD) / beryllium sensitization (BeS) : HLA-DPB1 alleles with a glutamic acid residue at position 69 (E69). Results suggest that the less-frequent E69 variants (non-*0201/*0202 alleles) might be associated with greater risk of CBD (ref).

Acute lymphoblastic leukemia (ALL) : HLA-DPB1*01:01 (ref).

Pemphigus vulgaris : DRB1*04–DQB1*03 or HLA-DRB1*14–DQB1*05 (ref)

Endemic pemphigus foliaceus (EPF) : rs3087456 in the CIITA gene promoter is associated with susceptibility (OR =2.6 and OR=2 for genotypes G/G and G/A)

Autoimmune thrombotic thrombocytopenic purpura (TTP) : DRB1*11 (ref)

Insulin autoimmune syndrome (IAS) / Hirata disease : HLA DRB1*04:06 (expecially in Japanese) and DRB1*04:03 (expecially in Caucasians) (ref)

Idiopathic membranous nephropathy (IMN) : HLA-DQA1 (ref)

Monday, January 23, 2012

Mechanism of transfer of functional microRNAs between mouse dendritic cells via exosomes

Dendritic cells (DCs) are the most potent APCs. Whereas immature DCs down-regulate T-cell responses to induce/maintain immunologic tolerance, mature DCs promote immunity. To amplify their functions, DCs communicate with neighboring DCs through soluble mediators, cell-to-cell contact, and vesicle exchange. Transfer of nanovesicles (< 100 nm) derived from the endocytic pathway (termed exosomes) represents a novel mechanism of DC-to-DC communication. The facts that exosomes contain exosome-shuttle miRNAs and DC functions can be regulated by exogenous miRNAs, suggest that DC-to-DC interactions could be mediated through exosome-shuttle miRNAs, a hypothesis that remains to be tested. Importantly, the mechanism of transfer of exosome-shuttle miRNAs from the exosome lumen to the cytosol of target cells is unknown. Here, we demonstrate that DCs release exosomes with different miRNAs depending on the maturation of the DCs. By visualizing spontaneous transfer of exosomes between DCs, we demonstrate that exosomes fused with the target DCs, the latter followed by release of the exosome content into the DC cytosol. Importantly, exosome-shuttle miRNAs are functional, because they repress target mRNAs of acceptor DCs. Our findings unveil a mechanism of transfer of exosome-shuttle miRNAs between DCs and its role as a means of communication and posttranscriptional regulation between DCs (read more).

Sphingosine-1-phosphate facilitates trafficking of hematopoietic stem cells and their mobilization by CXCR4 antagonists in mice

CXCL12 and VCAM1 retain hematopoietic stem cells (HSCs) in the BM, but the factors mediating HSC egress from the BM to the blood are not known. The sphingosine-1-phosphate receptor 1 (S1P1) is expressed on HSCs, and S1P facilitates the egress of committed hematopoietic progenitors from the BM into the blood. In the present study, we show that both the S1P gradient between the BM and the blood and the expression of S1P1 are essential for optimal HSC mobilization by CXCR4 antagonists, including AMD3100, and for the trafficking of HSCs during steady-state hematopoiesis. We also demonstrate that the S1P1 agonist SEW2871 increases AMD3100-induced HSC and progenitor cell mobilization. These results suggest that the combination of a CXCR4 antagonist and a S1P1 agonist may prove to be sufficient for mobilizing HSCs in normal donors for transplantation purposes, potentially providing a single mobilization procedure and eliminating the need to expose normal donors to G-CSF with its associated side effects (read more).

Tuesday, January 17, 2012

Mesenchymal stromal cells for tissue-engineered tissue and organ replacements

Mesenchymal stromal cells (MSCs), a rare heterogeneous subset of pluripotent stromal cells that can be easily isolated from different adult tissues, in vitro expanded and differentiated into multiple lineages, are immune privileged and, more important, display immunomodulatory capacities. Because of this, they are the preferred cell source in tissue-engineered replacements, not only in autogeneic conditions, where they do not evoke any immune response, but especially in the setting of allogeneic organ and tissue replacements. However, more preclinical and clinical studies are requested to completely understand MSC’s immune biology and possible clinical applications. We herein review the immunogenicity and immunomodulatory properties of MSCs, their possible mechanisms and potential clinical use for tissue-engineered organ and tissue replacement (read more).

Monday, January 16, 2012

Saturday, January 14, 2012

Life expectancy by country

An interactive chart with implications for deceased donor transplantation acitivity : life expectancy by country. Countries with higher life expectancy are expected to experience a decline in deceased donor transplantation, and should invest on living donor transplantation.

Friday, January 13, 2012

Prolonged cold ischemia accelerates cellular and humoral chronic rejection in a rat model of kidney allotransplantation

One of the leading causes of long-term kidney graft loss is chronic allograft injury (CAI), a pathological process triggered by alloantigen-dependent and alloantigen-independent factors. Alloantigen-independent factors, such as cold ischemia (CI) may amplify the recipient immune response against the graft. We investigated the impact of prolonged cold ischemia and the subsequent delayed graft function on CAI in a fully MHC-mismatched rat model of kidney allotransplantation. Prolonged CI was associated with anticipation of proteinuria onset and graft function deterioration (ischemia: 90d; no ischemia: 150d), more severe tubular atrophy, interstitial fibrosis, and glomerulosclerosis, and increased mortality rate (180d survival, ischemia: 0%; no ischemia: 67%). In ischemic allografts, T and B cells were detected very early and were organized in inflammatory clusters. Higher expression of BAFF-R and TACI within the ischemic allografts indicates that B cells are mature and activated. As a consequence of B cell activity, anti-donor antibodies, glomerular C4d and IgG deposition, important features of chronic humoral rejection, appeared earlier in ischemic than in non-ischemic allograft recipients. Thus, prolonged CI time plays a main role in CAI development by triggering acceleration of cellular and humoral reactions of chronic rejection. Limiting CI time should be considered as a main target in kidney transplantation (read more).

Thursday, January 12, 2012

Profiling Posttransplant Circulating Antibodies in Kidney Transplantation Using Donor Endothelial Cells.

BACKGROUND: Pathogenesis of antibody (Ab) responses to transplant are yet not well defined. This study aimed to detect and to analyze posttransplant circulating allo-Abs reacting toward graft endothelial cells (ECs) using primary EC cultures prospectively isolated from the transplant donor at the time of transplantation.
METHODS: This study shows a retrospective analysis performed using a dedicated EC crossmatch (ECXM) assay that we developed for the experimental assessment of donor-specific EC-reactive Abs. Donor-specific ECXM was performed by flow cytometry on posttransplant sera (n=256) from an historical cohort of 22 kidney allograft recipients.
RESULTS: In this study, we show that 27.3% (6/22) of recipients have a positive ECXM that strictly correlates (100%, 6/6) with the presence of anti-human leukocyte antigen (HLA) Abs posttransplantation. ECXM identifies both donor-specific Abs (DSA; 50%) and non-DSA (50%) reactive to EC. DSA and non-DSA are mostly IgG1 and exhibit peak titers ranging from 1/8 to 1/1024. ECXM indicates that DSA correspond to anti-HLA class II Abs; this immunization is late (M3-M60) but persistent (still detected at M60). In contrast, non-DSA are non-HLA-type Abs reacting with third-party EC and reflecting an early but transient immunization (ended at M3-M12). Our findings demonstrate selective regulatory pathways initiated by anti-HLA class II and non-DSA in graft EC reflected by CCR4 and interleukin 1β up-regulation, respectively.
CONCLUSIONS: We provide evidence that circulating Abs in HLA-sensitized transplant recipients include both DSA and non-HLA/non-DSA able to bind to graft EC and induce specific gene transcription (read more).

Recipient nonhematopoietic antigen-presenting cells are sufficient to induce lethal acute graft-versus-host disease

The presentation pathways by which allogeneic peptides induce graft-versus-host disease (GVHD) are unclear. We developed a bone marrow transplant (BMT) system in mice whereby presentation of a processed recipient peptide within major histocompatibility complex (MHC) class II molecules could be spatially and temporally quantified. Whereas donor antigen presenting cells (APCs) could induce lethal acute GVHD via MHC class II, recipient APCs were 100–1,000 times more potent in this regard. After myeloablative irradiation, T cell activation and memory differentiation occurred in lymphoid organs independently of alloantigen. Unexpectedly, professional hematopoietic-derived recipient APCs within lymphoid organs had only a limited capacity to induce GVHD, and dendritic cells were not required. In contrast, nonhematopoietic recipient APCs within target organs induced universal GVHD mortality and promoted marked alloreactive donor T cell expansion within the gastrointestinal tract and inflammatory cytokine generation. These data challenge current paradigms, suggesting that experimental lethal acute GVHD can be induced by nonhematopoietic recipient APCs (read more).

Wednesday, January 11, 2012

Comparative Study on Signal Transduction in Endothelial Cells After Anti-A/B and Human Leukocyte Antigen Antibody Reaction: Implication of Accommodation.

BACKGROUND: Recent development of immunosuppressive therapy has provided a platform for clinical human leukocyte antigen (HLA)- and ABO-incompatible kidney transplantation. However, the prognosis seems to be different between the two. Accommodation, the condition of no injury even in the presence of antidonor antibody, is one of the key factors for successful transplantation with antidonor antibody. The purpose of this study was to compare signal transduction between anti-A/B and anti-HLA antibody reaction and to elucidate the mechanisms underlying accommodation.METHODS: Blood type A- or B-transferase gene was transfected into human EA.hy926 endothelial cells. After cell sorting, A- or B-expressing cells at high levels were obtained. The effects of anti-HLA and anti-A/B antibody binding on complement-mediated cytotoxicity and signal transduction were examined. RESULTS: Preincubation with anti-HLA antibodies only at low levels (<10% of saturation level) or anti-A/B antibodies at high levels (even at near saturation levels) for 24 hr resulted in resistance to complement-mediated cytotoxicity. Anti-A/B antibody ligation inactivated ERK1/2 pathway and increased complement regulatory proteins such as CD55 and CD59, whereas anti-HLA ligation activated PI3K/AKT pathway and increased cytoprotective genes such as hemeoxygenase-1 and ferritin H. CONCLUSION: Complement inhibition by upregulation of CD55 and CD59 through ERK1/2 inactivation might play a substantial role in accommodation after ABO-incompatible transplantation, which could also explain the intriguing finding of C4d deposition in the graft without rejection (read more)

Development of Donor-Specific Isohemagglutinins Following Pediatric ABO-Incompatible Heart Transplantation

Graft acceptance following pediatric ABO-incompatible heart transplantation has been associated with a deficiency of donor-specific isohemagglutinins (DSI) due to B-cell elimination. Recent observations suggest that some of these patients do produce DSI. The purpose of this study was to examine the pattern of, risk factors for development and clinical impact of DSI. All children who underwent an ABO-incompatible heart transplant (1996–2009) were included. Serial postheart transplantation DSI titers and clinical outcomes were reviewed. DSI were produced in 27% of the patients (n = 11/41). Anti-A production was significantly greater in “at risk” patients than Anti-B (39% vs. 8%; p = 0.04). Risk factors associated with the development of DSI included: older age at transplantation (HR: 1.15/month, p = 0.04), pretransplant Anti-B level ≥ 1:8 (HR: 9.61, p = 0.004) and HLA sensitization (HR: 2.80, p = 0.11). The presence of DSI did increase the risk of cellular rejection but not antibody-mediated rejection, allograft vasculopathy, graft loss or death. Although these antibodies do not result in any significant clinical consequences, their presence suggests that B-cell tolerance is not the sole mechanism of graft acceptance (read more, including excellent editorial).

Bone Marrow of Multiorgan Donors Underutilized: Implications for Improvement of Accessibility of Hematopoietic Cells for Transplantations

Background. The demand for human hematopoietic stem and progenitor cells (HSPCs) for transplantation is increasing. Thus, effective alternative sources of HSPCs are required. Consequently, we sought to expand the accessibility of hematopoietic cells for clinical purposes by the investigation of hematopoietic reconstitution after transplantation of human HSPCs harvested from the bone marrow (BM) of heparinized deceased organ donors (HDODs).
Methods. For multipart research comparison, human BM HDODs-, healthy donor-derived, umbilical cord blood nuclear cells, or CD34+ cells were transplanted into sublethally irradiated NOD/SCID mice. Twenty-eight days after transplantation nuclear cells were isolated from the murine BM, spleen, and peripheral blood and were used to quantitatively detect human CD45 antigen by quantitative real-time reverse transcriptase–polymerase chain reaction and flow cytometry. The clonogenic growth of human colony-forming units was also investigated.
Results. We found that umbilical cord blood-derived HSPCs showed the greatest transplantation potential in our in vivo model. Interestingly, the transplantation potential of HSPCs collected from the BM of HDODs was of the same quality as cells obtained from healthy BM donors.
Conclusion. Based on these results, we conclude that HDODs are a strongly underappreciated source of HSPCs that are ready to use for clinical purposes (read more).

Enteroscopic Biopsies in the Management of Pancreas Transplants: A Proof of Concept Study for a Novel Monitoring Tool

Background. Although percutaneous biopsies are considered to be the gold standard in diagnosing pancreas graft rejection, they are not performed routinely because of their association with severe complications. On the other hand, correct diagnosis of rejection is essential but may be difficult in cases of enteric drainage, particularly in patients with a pancreas transplant alone or a pancreas after kidney transplant.
Methods. Pancreas recipients who underwent enteroscopy between May 2005 and September 2009 were included in this retrospective analysis. Biopsies were graded 0 to 4 for interstitial and vascular changes.
Results. During the study period a total of 65 simultaneous pancreas-kidney transplants, 13 pancreas after kidney transplants and 4 pancreas transplants alone were performed. Sixty-three patients underwent a single enteroscopy, 10 had two, and 6 had three or more. Indications were protocol graft monitoring (n=73), graft dysfunction (n=17), enteric hemorrhage (n=9), or other (n=3). The duodenal segment was accessed in 76 instances (75%) with abnormal findings in 23. A total of 69 biopsies were obtained and revealed normal mucosa in 49 cases (71%). Histology showed signs of acute rejection in 11 cases. The upper gastrointestinal tract was also assessed, and, in 13 cases, additional pathologies were identified including gastroduodenitis (n=10), gastric/duodenal ulcer (n=2), and hemorrhagic esophagitis (n=1). No procedure-related complication occurred.
Conclusions. This series of enteroscopies demonstrates that the duodenal segment of a pancreatic graft is accessible using our implant technique, and thus permitting biopsies to be obtained and endoscopic interventions to be performed (read more).

Saturday, January 7, 2012

Preservation Solutions for Static Cold Storage of Kidney Allografts: A Systematic Review and Meta-Analysis

Static cold storage is the most prevalent method for renal allograft preservation. Several solutions have been designed to counteract the detrimental effects of cold ischemia and reperfusion. The aim of this study was to appraise the evidence for the currently available preservation solutions. We performed a systematic literature search using MEDLINE, EMBASE, the Cochrane Library, the Transplant Library and trial registries. Inclusion criteria specified any comparative, prospective study for deceased donor renal allografts. Studies were assessed for methodological quality. The primary outcome was delayed graft function (DGF). Fifteen trials with a total of 3584 kidneys were included. Eurocollins was associated with a higher risk of DGF than University of Wisconsin solution (UW) in two randomized controlled trials (RCTs) and histidine–tryptophan–ketoglutarate (HTK) in two RCTs. UW was associated with an equal risk of DGF compared with Celsior in three RCTs and HTK in two RCTs. There was limited data regarding other comparisons and outcomes. The choice of preservation solution has an effect on the incidence of DGF, which might, in turn, affect long-term outcomes. Both UW and HTK have lower rates of DGF than Eurocollins. There is no difference in the incidence of DGF with the use of Celsior, HTK and UW. These findings are supported by registry data (read more).

Epidemiology of Posttransplant Lymphoproliferative Disorders in Adult Kidney and Kidney Pancreas Recipients: Report of the French Registry and Analysis of Subgroups of Lymphomas

A registry of posttransplant lymphoproliferative disorders (PTLD) was set up for the entire population of adult kidney transplant recipients in France. Cases of PTLD were prospectively enrolled between January 1, 1998, and December 31, 2007. Ten-year cumulative incidence was analyzed in patients transplanted after January 1, 1989. PTLD risk factors were analyzed in patients transplanted after January 1, 1998 by Cox analysis. Cumulative incidence was 1% after 5 years, 2.1% after 10 years. Multivariate analysis showed that PTLD was significantly associated with: older age of the recipient 47–60 years and >60 years (vs. 33–46 years, adjusted hazard ratio (AHR) = 1.87, CI = 1.22–2.86 and AHR = 2.80, CI = 1.73–4.55, respectively, p < 0.0001), simultaneous kidney–pancreas transplantation (AHR = 2.52, CI = 1.27–5.01 p = 0.008), year of transplant 1998–1999 and 2000–2001 (vs. 2006–2007, AHR = 3.36, CI = 1.64–6.87 and AHR = 3.08, CI = 1.55–6.15, respectively, p = 0.003), EBV mismatch (HR = 5.31, CI = 3.36–8.39, p < 0.001), 5 or 6 HLA mismatches (vs. 0–4, AHR = 1.54, CI = 1.12–2.12, p = 0.008), and induction therapy (AHR = 1.42, CI = 1–2.02, p = 0.05). Analyses of subgroups of PTLD provided new information about PTLD risk factors for early, late, EBV positive and negative, polymorphic, monomorphic, graft and cerebral lymphomas. This nationwide study highlights the increased risk of PTLD as long as 10 years after transplantation and the role of cofactors in modifying PTLD risk, particularly in specific PTLD subgroups (read more).

Thursday, January 5, 2012

Final results for the Luminex polls

Final results for the Luminex poll : briefly, OneLambda is the favourite platform (with a growing number of labs using both platforms, mostly for collaborative studies), and most labs use MFI > 1,000 as cutoff. Please check our new polls about chimerism monitoring on the right panel : you can vote until end of January !.