The suppressive effect on CD4 T cell alloresponse against endothelial HLA-DR via PD-L1 induced by anti-A/B ligation.

While donor-specific human leukocyte antigen (HLA) antibodies are a frequent cause for chronic antibody-mediated rejection in organ transplantation, this is not the case for antibodies targeting blood group antigens, as ABO-incompatible (ABO-I) organ transplantation has been associated with a favorable graft outcome. Here, we explored the role of CD4 T cell-mediated alloresponses against endothelial HLA-D-related (DR) in the presence of anti-HLA class I or anti-A/B antibodies. CD4 T cells, notably CD45RA-memory CD4 T cells, undergo extensive proliferation in response to endothelial HLA-DR. The CD4 T cell proliferative response was enhanced in the presence of anti-HLA class I, but attenuated in the presence of anti-A/B antibodies. Microarray analysis and molecular profiling demonstrated that the expression of CD274 programmed cell death ligand 1 (PD-L1) increased in response to anti-A/B ligation-mediated extracellular signal-regulated kinase (ERK) inactivation in endothelial cells that were detected even in the presence of interferon-γ stimulation. Anti-PD-1 antibody enhanced CD4 T cell proliferation, and blocked the suppressive effect of the anti-A/B antibodies. Educated CD25+ CD127- regulatory T cells (edu.Tregs ) were more effective at preventing CD4 T cell alloresponses to endothelial cells compared with naive Treg ; anti-A/B antibodies were not involved in the Treg -mediated events. Finally, amplified expression of transcript encoding PD-L1 was observed in biopsy samples from ABO-I renal transplants when compared with those from ABO-identical/compatible transplants. Taken together, our findings identified a possible factor that might prevent graft rejection and thus contribute to a favorable outcome in ABO-I renal transplantation.

Efficacy of Eculizumab Therapy for Atypical Hemolytic Uremic Syndrome Recurrence and Antibody-Mediated Rejection Progress After Renal Transplantation With Preformed Donor-Specific Antibodies: Case Report.

Atypical hemolytic uremic syndrome (aHUS) develops as the result of unregulated complement progression and precipitates de novo thrombotic microangiopathy. Plasma therapy is used to control the progression of the complement cascade, but that therapy is not effective in all patients and is accompanied by risk of infection and/or allergy. Eculizumab has been reported as an efficient therapy for aHUS. We report the case of a 35-year old woman who underwent effective eculizumab therapy for aHUS recurrence and antibody-mediated rejection (AMR) progress after renal transplantation with preformed donor-specific antibodies (DSA). She developed end-stage renal disease due to suspicious IgA nephropathy at age 33 years. Kidney transplantation was performed at age 35 years, and aHUS recurred 2 weeks later, leading to the progressive hemolytic anemia and renal dysfunction. Therefore, she underwent plasma therapy several times. Because it was difficult to continue to plasma therapy for severe allergy, eculizumab was proposed as an alternate therapy. Treatment with eculizumab was initiated 36 days after renal transplantation. After 3 years of eculizumab treatment, and without plasma therapy, schistocytes decreased, haptoglobin increased to within normal limits, creatinine levels stabilized, and no further episodes of diarrhea were reported. At protocol biopsy 1 year after transplantation, she was diagnosed with C4d-negative subclinical AMR. However, her pathologic findings at follow-up biopsy 3 years after transplantation were recovered. We conclude that eculizumab alone, without plasma therapy, is sufficient to treat recurrence of aHUS and AMR due to DSA after renal transplantation and to maintain long-term graft function.

Acute antibody-mediated rejection possibly due to anti-human leukocyte antigen DQB1 antibodies after renal transplantation - case report.

A 61-year-old Japanese woman, who had undergone hemodialysis because of chronic glomerulonephritis, received a living renal transplant from her ABO blood type-compatible spouse. HLA typing of A, B and DRB showed 3/6 mismatches. Complement-dependent cytotoxicity crossmatches, HLA antibody screening with the use of flow panel reactive antibody (PRA), and flow cytometry crossmatches (FCXM) were all negative. Tacrolimus, mycophenolate mofetil, methylprednisolone (MP), and basiliximab induction were used as the standard immunosuppressive therapy. After renal transplantation, her serum creatinine level favorably decreased, but urine output was not sufficiently obtained, contrary to our expectations. Doppler sonography revealed disappearance of diastolic arterial flow on postoperative day 2. The episode biopsy showed acute antibody-mediated rejection (AMR) based on the current Banff classification, although FCXM and flow PRA were still negative. To determine the cause of acute AMR, we expanded the HLA typing at high resolution levels to Cw, DQB1, and DPB1. Retrospective analysis of perioperative sera demonstrated the presence of low levels of donor-specific HLA IgG and moderate levels of IgM antibody against DQB1 before transplantation. There was an elevation of IgM antibody at the time of rejection, whereas IgG antibody showed no remarkable change. AMR was successfully treated with plasma exchange, low-dose intravenous immunoglobulin, high-dose intravenous MP pulse, and rituximab.

Potent immunosuppression for ABO-incompatible renal transplantation may not be a risk factor for malignancy.

ABO-incompatible (ABOi) renal transplantation has been increasing, but malignant tumor is a troubling complication of kidney transplantation due to potent immunosuppression. Few previous studies, however, have demonstrated that potent immunosuppression for ABOi living-donor renal transplantation (LDRT) is a risk factor for malignancy. In the present research, data on 252 LDRT patients ftom 2003 to 2008 were retrospectively analyzed to clarify whether ABOi LDRT was associated with malignancy. A potent immunosuppressive regimen for ABOiLDRT consisted of splenectomy, cyclophosphamide, and double-filtration plasmapheresis to minimize the risk of antibody-mediated rejection, in addition to conventional immunosuppresssants including calcineurin inhibitor, prednisolone, and anti-CD25 monoclonal antibody. A total of 11 incidences of malignancy were observed during a median follow-up of 48 months. The incidence rates in ABO-compatible (ABOc; n = 189) and ABOi (n = 63) LDRT groups were 4.2 % (8/189) and 4.8 % (3/63), respectively. Kaplan-Meier survival analysis showed no statistical difference in event-free survival for malignancy between ABOc and ABOiLDRT groups (log-rank P = .73). Multivariable Cox regression analyses identified no associations of malignancy with ABOi LDRT or any immunosuppressant use. In conclusion, our investigation suggested that potent immunosuppression with splenectomy and cyclophosphamide for ABOi LDRT may not be a risk factor for malignancy.

Clinical characteristics and outcomes of renal transplantation in elderly recipients.

BACKGROUND: Elderly renal transplant candidates constitute one the fastest-growing populations among end-stage renal disease patients. Since the impacts of advanced recipient age have not yet been fully defined, we evaluated the clinical characteristics and outcomes of elderly renal transplant recipients. METHODS: Among 564 adult renal transplant recipients, at our center between 2000 and 2009, 64 were at least 60 years of age (Elderly group), and 500 were younger than 60 years (Young group) at the time of the procedure. We compared their clinical features and surgical management. RESULTS: There were significant differences in mean donor age (55.6 years vs. 53.2 years, P = .030) and gender mismatch (77.0% vs. 63.4%, P = .035). However, there were no significant differences between the two groups in patient and graft survivals (P = .177 and P = .365, respectively). Malignancy after transplantation was a significant risk factor upon univariate evaluation but only ABO incompatibility upon multivariate analysis of patient and graft survival. The main cause of graft loss among the Elderly group was death with a functioning graft due to heart failure. CONCLUSIONS: Renal transplantation is a feasible, safe option for the elderly and should be actively implemented. However, screening for cancer and heart disease should be mandatory to improve outcomes.

Microdialysis measurement of ascorbic acid in rabbit vitreous after photodynamic reaction.

A method for long-term intravitreous microdialysis was used to measure endogenous reduced ascorbic acid in the vitreous of rabbits by HPLC-ECD before and after exposure to intense visible light in the presence of fluorescein. Cellulose microdialysis probes were implanted into the vitreous humor of each eye and after stabilization ascorbic acid measurements were recorded over a 14 day period. Under this experimental condition, normal ascorbic acid concentrations in vitreous varied from 98.0 +/- 9.8 to 106.9 +/- 20.3 microM(mean +/- S.D.). The eyes received light irradiation (25 000 lux) for 2 hr and fluorescein was used as the photosensitizer once or twice. No immediate effects on ascorbic acid concentrations could be observed in the eyes irradiated twice without fluorescein i.v. injections and in the twice fluorescein injected without irradiation. However, in the eyes irradiated once with fluorescein (30 mg kg(-1)), ascorbic acid concentration after irradiation significantly decreased from day 2 and continued over a period of 10 days compared with that before irradiation and maximal reduction was 32.6% (P < 0.005) on day 6 after irradiation. By day 13, the ascorbic acid concentration returned to control levels (P > 0.01). In the eyes irradiated twice with fluorescein injections, ascorbic acid concentration after irradiation decreased even more over the experimental period and the maximal reduction was 65.5% (P < 0.005) on day 5 after irradiation and did not recover over the next 9 days. In the eyes irradiated twice with fluorescein injections plus administration of ascorbic acid (150 mg kg(-1)) 30 min before irradiation, a significant increase (52.5%) of ascorbic acid (P < 0.005) was found on day 1 and control levels of ascorbic acid were maintained from day 2 onward. The protective role of ascorbic acid in the vitreous humor against photodynamic reaction is suggested.