Scott Ames

Donor Toll-like receptor 4 contributes to ischemia and reperfusion injury following human kidney transplantation

While studies in animal models have linked Toll-like receptor (TLR) 4 signaling to kidney injury induced by ischemia and reperfusion, the relevance of TLR4 activation to allograft injury in human kidney transplants is unknown. Here we show that TLR4 is constitutively expressed within all donor kidneys but is significantly higher in deceased-, compared with living-donor organs. Tubules from deceased- but not living-donor kidneys also stained positively for high-mobility group box-1 (HMGB1), a known endogenous TLR4 ligand. In vitro stimulation of human tubular cells with HMGB1, in a TLR4-dependent system, confirmed that HMGB1 can stimulate proinflammatory responses through TLR4. To assess the functional significance of TLR4 in human kidney transplantation, we determined whether TLR4 mutations that confer diminished affinity for HMGB1 influence intragraft gene-expression profiles and immediate graft function. Compared with kidneys expressing WT alleles, kidneys with a TLR4 loss-of-function allele contained less TNFα, MCP-1, and more heme oxygenase 1 (HO-1), and exhibited a higher rate of immediate graft function. These results represent previously undetected evidence that donor TLR4 contributes to graft inflammation and sterile injury following cold preservation and transplantation in humans. Targeting TLR4 signaling may have value in preventing or treating postischemic acute kidney injury after transplantation.

Immune Reconstitution Following Rabbit Antithymocyte Globulin

Depletional induction therapies are routinely used to prevent acute rejection and improve transplant outcome. The effects of depleting agents on T‐cell subsets and subsequent T‐cell reconstitution are incompletely defined. We used flow cytometry to examine the effects of rabbit antithymocyte globulin (rATG) on the peripheral T‐cell repertoire of pediatric and adult renal transplant recipients. We found that while rATG effectively depleted CD45RA+CD27+ naïve and CD45RO+CD27+ central memory CD4+ T cells, it had little effect on CD45RO+CD27− CD4+ effector memory or CD45RA+CD31−, CD45RO+CD27+ and CD45RO+CD27− CD8+ T cell subsets. When we performed a kinetic analysis of CD31+ recent thymic emigrants and CD45RA+/RO+ T cells, we found evidence for both thymopoiesis and homeostatic proliferation contributing to immune reconstitution. We additionally examined the impact of rATG on peripheral CD4+Foxp3+ T cells. We found that in adults, administration of rATG‐induced peripheral expansion and new thymic emigration of T cells with a Treg phenotype, while CD4+Foxp3+ T cells of thymic origin predominated in children, providing the first evidence that rATG induces Treg in vivo. Collectively our data indicate that rATG alters the balance of regulatory to memory effector T cells posttransplant, providing an explanation for how it positively impacts transplant outcome.

Favorable Long-Term Outcome after Liver-Kidney Transplant for Recurrent Hemolytic Uremic Syndrome Associated with a Factor H Mutation

A male child initially presented with atypical hemolytic uremic syndrome (HUS) at the age of 4 months and progressed within weeks to end stage renal disease (ESRD). At the age of 2 years he received a live‐related kidney transplant from his mother, which, despite initial good function, was lost to recurrent disease after 2 weeks. Complement factor H analysis showed low serum levels and the presence of two mutations on different alleles (c.2918G > A, Cys973Tyr and c.3590T > C, Val1197Ala). His survival on dialysis was at risk because of access failure and recurrent bacteremic episodes. Therefore, at the age of 5 years he received a combined liver‐kidney transplant with pre‐operative plasma exchange. Initial function of both grafts was excellent and this has been maintained for over 2 years. This report suggests that despite setbacks in previous experience, combined liver‐kidney transplantation offers the prospect of a favorable long‐term outcome for patients with HUS associated with complement factor H mutations.

Post‐liver transplant acute renal failure: factors predicting development of end‐stage renal disease*

Abstract:  Background:  Acute renal failure (ARF) occurs in 5–50% ofpatients undergoing orthotopic liver transplantation (OLT). The aim of this study was to determine factors that might predict the development of end stage renal disease (ESRD) in patients who had ARF after OLT.

Addition of Plasmapheresis Decreases the Incidence of Acute Antibody-Mediated Rejection in Sensitized Patients with Strong Donor-Specific Antibodies

BACKGROUND AND OBJECTIVES The objective of this study was to investigate the effects of desensitization protocols using intravenous Ig with or without plasmapheresis in patients with donor-specific anti-HLA antibodies on prevention of antibody-mediated rejection and downregulation of donor-specific antibodies. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Thirty-five complement-dependent cytotoxicity T cell cross-match-negative but complement-dependent cytotoxicity B cell and/or flow cytometry cross-match-positive kidney transplant recipients were treated with high-dosage intravenous Ig plus Thymoglobulin induction treatment. Donor-specific antibody strength was stratified as strong, medium, or weak by Luminex flow beads. Group 1 patients had weak/moderate and group 2 strong donor-specific antibodies RESULTS Whereas no group 1 patients had acute rejection, 66% of group 2 had acute rejection (44% antibody-mediated rejection, 22% cellular rejection). The protocol was then changed to the addition of peritransplantation plasmapheresis to patients with strong donor-specific antibodies (group 3). This change resulted in a dramatic decrease in the acute rejection rate to 7%. During a median 18 mo of follow-up, patient survival was 100, 100, and 93% and graft survival was 100, 78, and 86% in groups 1, 2, and 3, respectively. During follow-up, 17 (52%) patients lost donor-specific antibodies completely, and 10 (30%) lost some of donor-specific antibodies and/or decreased the strength of existing donor-specific antibodies. CONCLUSIONS These results indicated that in patients with strong donor-specific antibodies, the addition of plasmapheresis to high-dosage intravenous Ig decreases the incidence of acute rejection. The majority of the patients, whether they received intravenous Ig alone or with plasmapheresis, lost their donor-specific antibodies during follow-up.

Intravenous immunoglobulin and thymoglobulin facilitate kidney transplantation in complement-dependent cytotoxicity B-cell and flow cytometry T- or B-cell crossmatch-positive patients.

Background. The aim of this study was to investigate the effect of Thymoglobulin and intravenous immunoglobulin (IVIG) therapy on the clinical outcome of a putatively high-risk group of kidney transplant recipients who have positive B-cell complement-dependent cytotoxicity (CDC) along with positive T- or B-cell flow cytometry (FC) crossmatch results. Methods. We prospectively studied the effects of IVIG and Thymoglobulin induction treatment in B-cell CDC, and T- or B-cell FC crossmatch-positive kidney transplant recipients (seven women and one man; mean age, 43±12 years). Results. Mean peak panel-reactive antibody (PRA) was 47±32. Three patients had donor-specific antibody by flow PRA (two anti-DR4 and one anti-A2). Each recipient received induction treatment with IVIG 100 mg/kg for 3 days and Thymoglobulin 1.5 mg/kg for 5 days after transplantation. No acute cellular rejections occurred during a median follow-up of 15 months (range, 12–17 months). Only one acute humoral rejection occurred 8 days after transplantation, which responded to plasmapheresis, IVIG, and rituximab. One allograft was lost because of polyoma nephritis. Patient survival was 100% and allograft survival was 88%. Conclusion. Our results indicate that IVIG and Thymoglobulin induction treatment may facilitate kidney transplantation in B-cell CDC and T- or B-cell FC crossmatch-positive patients.

Antibodies Reactive to Non-HLA Antigens in Transplant Glomerulopathy

Although T and B cell alloimmunity contribute to transplant injury, autoimmunity directed at kidney-expressed, non-HLA antigens may also participate. Because the specificity, prevalence, and importance of antibodies to non-HLA antigens in late allograft injury are poorly characterized, we used a protein microarray to compare antibody repertoires in pre- and post-transplant sera from several cohorts of patients with and without transplant glomerulopathy. Transplantation routinely induced changes in antibody repertoires, but we did not identify any de novo non-HLA antibodies common to patients with transplant glomerulopathy. The screening studies identified three reactivities present before transplantation that persisted after transplant and strongly associated with transplant glomerulopathy. ELISA confirmed that reactivity against peroxisomal-trans-2-enoyl-coA-reductase strongly associated with the development of transplant glomerulopathy in independent validation sets. In addition to providing insight into effects of transplantation on non-HLA antibody repertoires, these results suggest that pretransplant serum antibodies to peroxisomal-trans-2-enoyl-coA-reductase may predict prognosis in kidney transplantation.

Laparoscopic donor nephrectomy

BackgroundSeveral large series of laparoscopic donor nephrectomy (LDN) have been published, largely focusing on immediate results and short-term complications. The aim of this study was to examine the results of LDN and collect medium-term and long-term donor followup.MethodsWe examined the results of two surgeons who performed 500 consecutive LDNs from 1996 to 2005. Prospective databases were reviewed for both donors and recipients to record demographics, medical history, intraoperative events, and complications. Patients were followed between 1 month and 9 years after surgery to assess for delayed complications, especially hypertension, renal insufficiency, incisional hernia, bowel obstruction, and chronic pain.ResultsLeft kidneys were procured in 86.2% of cases. Mean operative time was 3.5 h, and warm ischemia time averaged 3.4 min. Hand-assistance was used in 13.8%, and conversion rate was 1.8%. Intraoperative complication rate was 5.8% and was predominantly bleeding (93.1%). Most (86.2%) of the operative complications occurred during the initial 150 cases of a surgeon, compared with 10.3% in the subsequent 150 cases (p = 0.003). Operative time decreased by 87 min after the initial 150 cases (p < 0.001). Immediate graft survival was 97.5%. Delayed graft function occurred in 3.0% of recipients, and acute tubular necrosis occurred in 7.0%. Thirty-day donor complication rate was 9.8%. Mean donor creatinine was 1.24 on the first postoperative day, 1.27 at 2 weeks, and 1.24 at 1 year. At a mean followup of 32.8 months, long-term donor complications consisted of 11 cases of hypertension, 9 cases of prolonged pain or paresthesia, 2 incisional hernias, 1 small bowel obstruction requiring laparoscopic lysis of adhesions, and 1 hydrocele requiring repair.ConclusionsLDN can be performed with acceptable immediate morbidity and excellent graft function. Operative time and complications decreased significantly after a surgeon performed 150 cases. Long-term complications were uncommon but included a likely underestimated incidence of hypertension.

The First Decade of a Laparoscopic Donor Nephrectomy Program: Effect of Surgeon and Institution Experience with 512 Cases from 1996 to 2006

BACKGROUND Although the procedure is generally safe, significant morbidity and even mortality have occurred after laparoscopic donor nephrectomy (LDN). The learning curves for both surgeons and institutions with LDN have not been well delineated, and longterm donor data are not well reported. STUDY DESIGN A retrospective study of the initial 512 patients undergoing LDN performed at Mount Sinai Medical Center between October 1996 and March 2006 was performed. Intraoperative and immediate postoperative surgical outcomes were reviewed. Univariate analysis and multivariate logistic regressions were performed to identify predictors of outcomes, including the experience level of individual surgeons and of the institution. Longitudinal followup data of donor patients between 1 month and 9 years were obtained. RESULTS Mean donor age was 39.2 years, and 54.6% of patients were women. Left kidneys were procured in 84.0%. Operative time averaged 215.2 minutes, and warm ischemia time, 166.6 seconds. The conversion rate was 1.4%, and hand-assistance was used in 49.9%. The intraoperative complication rate was 5.5%, 30-day complication rate 9.4%, and 1.4% of patients required reoperation. Immediate graft survival was 97.1%, acute tubular necrosis occurred in 8.5%, and delayed graft function in 3.7%. At a mean followup of 37.2 months, delayed donor complications were infrequent, but included chronic pain, hypertension, incisional hernia, and small bowel obstruction. Although individual surgeons and our institution gained experience, operative and warm ischemia times decreased significantly, but complication rates were unchanged. CONCLUSIONS Although a learning curve was discovered for operative time and warm ischemia time, excellent results can be achieved during the early experience of both surgeons and institutions with LDN, and maintained over time. Younger, female, and nonobese donors were associated with fewer complications. Longterm donor morbidity is uncommon, but mandates better followup.

The hemodynamic effects of Cremophor-EL.

A problem associated with parenteral cyclosporine has been the increased incidence of renal toxicity. Cremophor-EL, the vehicle for parenteral cyclosporine has been associated with massive histamine release and anaphylaxis in certain animal models. We investigated the effects of Cremophor-EL on the cardiac output (CO); mean arterial pressure (MAP); and hepatic, renal and pancreatic blood flow in the anesthesized canine model. Doppler flow probes were utilized to calculate individual organ blood flow. Profound adverse affects were noted on the CO, MAP, and hepatic blood flow. There were negative trends noted in the renal and splenic arterial flow that did not reach statistical significance. It was noted that the changes in organ blood flow were partially independent on MAP and the total dose of Cremophor-EL. We therefore conclude that it is prudent to consider the possible adverse hemodynamic role of Cremophor-EL in canine allograft dysfunction.