Rajil Mehta

Cross-species comparison of gene expression between human and porcine tissue, using single microarray platform--preliminary results.

Abstract:  Introduction:  Xenotransplantation is a potential solution for inadequate supply of donor organs. Pigs are considered the ideal donor for kidney transplantation to human recipients, therefore it is important to understand the gene regulation in the porcine organs. Oligonucleotide array technology has been utilized largely for human, mouse and rat gene expression studies only. Its use with porcine genes has not been reported. We investigated the possibility of studying gene regulation in porcine kidney with a human GeneChip microarray® platform.

Soluble interleukin 2 receptor (sIL-2R) levels in renal transplant recipients.

Abstract:  Background:  Allograft rejection is associated with T cell activation. T cell activation leads to secretion of soluble IL‐2 receptor and elevated serum soluble IL‐2 receptor (sIL‐2R) levels. However, the clinical implication of individual elevated sIL‐2 receptor levels is unclear. We followed levels of sIL‐2R pre‐ and post‐transplantation to determine if sIL‐2R levels predict rejection episodes or degree of graft function.

Kidney allograft surveillance biopsy practices across US transplant centers: A UNOS survey

The approach to the diagnosis and management of subclinical rejection (SCR) in kidney transplant recipients remains controversial.

Subclinical Rejection in Renal Transplantation: Reappraised

Abstract Short-term outcomes in renal transplantation have improved significantly in the past few years. However, the improvement in long-term outcomes has been modest. The reasons for graft failure beyond the first year of transplantation have been attributed to several different factors. We believe that subclinical rejection (SCR) may be 1 of the factors that contribute to graft loss in the long run. We also believe that there are data to suggest that SCR leads to progressive fibrosis and loss of graft function. This has been demonstrated even in patients who have mild degrees of subclinical inflammation. This review outlines the major studies that have been published on this important topic. It also outlines potential risk factors for the development of SCR. The current approach and diagnostic methods are discussed as well as their pros and cons. Newer noninvasive methods of diagnosis as well as molecular diagnostics and their merits and shortcomings are also discussed in some depth. Thus, the proposed state of the art review on SCR will create a renewed interest at all levels including transplant clinicians, transplant researchers, pharmaceutical industries as well as regulatory organizations.

Cytomegalovirus infection in high-risk kidney transplant recipients receiving thymoglobulin induction-a single-center experience.

The burden of cytomegalovirus infection in CMV high‐risk (donor positive to recipient negative) kidney transplant recipients getting thymoglobulin induction and six months of valganciclovir is not well characterized. Additionally, the role of post‐prophylaxis surveillance remains unclear.

Kidney Transplant Outcomes After Primary, Repeat and Kidney After Nonrenal Solid Organ Transplantation: A Single-Center Experience.

Background Improvements in renal allograft outcomes have permitted kidney transplantation after prior kidney allograft failure as well as after nonrenal solid organ transplantation. This study compares renal allograft outcomes in the 3 groups, that is, primary, repeat, and kidney after nonrenal solid organ transplantation, where transplant group was coded as a time-dependent variable. Methods We retrospectively reviewed registry data for kidney transplant recipients at University of Pittsburgh Medical Center from January 2000 to December 2011. We compared overall graft survival between the 3 groups using Cox regression modeling. We calculated 1-, 3-, and 5-year graft survival and half-lives for each group where feasible. Results The study cohort (N = 2014) consisted of group A (primary kidney transplant, n = 1578, with 7923.2 years of follow-up time), group B (repeat kidney transplant, n = 314, with 1566.7 years of follow-up time) and group C (kidney post-nonrenal solid organ transplant, n = 176, with 844.8 years of follow-up time). Of the 1578 patients in the primary kidney transplant group, 74 later received a repeat transplant and thus also have follow-up counted in the repeat kidney transplant group. The median follow-up was 56, 53, and 55 months, respectively. The 5-year actuarial and death-censored graft survival was 68.69%, 68.79%, and 66.48% and 65.53%, 67.68%, and 62.92%, respectively (P = 0.70). There was no difference in overall graft survival in the Cox-adjusted analysis (group B: odds ratio, 1.02; 95% confidence interval, 0.84-1.26; P = 0.79; group C: odds ratio, 0.96; 95% confidence interval, 0.75-1.23; P = 0.76). Conclusions The adjusted kidney graft survivals in the 3 groups were similar.

Donor kidney microthrombi and outcomes of kidney transplant: a single-center experience

The kidney wait list has outgrown the supply of available organs every year. Efforts are being made to minimize discard rate of organs. One such area is the use of kidneys with glomerular microthrombi (MT). We retrospectively examined graft/patient outcomes in 28 cases with MT in pre‐implantation biopsies. All patients had follow‐up of at least 36 months, or until graft loss or death. In total, 17 of the 18 patients who underwent follow‐up biopsy within 90 days of transplantation had cleared all MT. Most patients had excellent long‐term graft function. On a closer review of the biopsies included in our study, we found that even in the organs with the most widespread thrombosis, the median percentage of glomeruli with more than 50 percentage of the capillary loops occluded was 8% (range 0–17%). The current practice of mentioning the % of glomeruli with thrombi cannot adequately capture the extent of donor organ pathology, as the actual % glomerular area involved can vary greatly from case to case. Future studies should attempt to quantify donor thrombi by a more robust method and revisit the issue of using clinico‐pathologic parameters to predict allograft function in the setting of MT.

Short-term adverse effects of early subclinical allograft inflammation in kidney transplant recipients with a rapid steroid withdrawal protocol

The impact of subclinical inflammation (SCI) noted on early kidney allograft biopsies remains unclear. This study evaluated the outcome of SCI noted on 3‐month biopsy. A total of 273/363 (75%) kidney transplant recipients with a functioning kidney underwent allograft biopsies 3‐months posttransplant. Among those with stable allograft function at 3 months, 200 biopsies that did not meet the Banff criteria for acute rejection were identified. These were Group I: No Inflammation (NI, n = 71) and Group II: Subclinical Inflammation (SCI, n = 129). We evaluated differences in kidney function at 24‐months and allograft histology score at 12‐month biopsy. SCI patients had a higher serum creatinine (1.6 ± 0.7 vs 1.38 ± 0.45; P = .02) at 24‐months posttransplant, and at last follow‐up at a mean of 42.5 months (1.69 ± 0.9 vs 1.46 ± 0.5 mg/dL; P = .027). The allograft chronicity score (ci + ct + cg + cv) at 12‐months posttransplant was higher in the SCI group (2.4 ± 1.35 vs 1.9 ± 1.2; P = .02). The incidence of subsequent rejections within the first year in SCI and NI groups was 24% vs 10%, respectively (P = .015). De novo donor‐specific antibody within 12 months was more prevalent in the SCI group (12/129 vs 1/71, P = .03). SCI is likely not a benign finding and may have long‐term implications for kidney allograft function.

Pro-inflammatory B Cells Predict Progressive Minimal Early Renal Allograft Inflammation Which Is Associated with Poor Graft Outcomes

Introduction The clinical significance of minimal tubulointerstitial inflammation (MTI: ‘t’+’i’ scores 0.5-1.5) and Banff Borderline changes (BBC: ‘t’ + ‘i’ scores 2-3.0) in early renal allograft biopsies is unclear. The rate and significance of progression of these lesions to late acute rejection (AR) also remains unknown. In this study, we assessed the clinical significance of early tubulointerstitial inflammation (< Banff 1A rejection). Methods Our center performs 2 protocol biopsies (3 & 12 months) along with for-cause biopsies. This allowed us to assess the clinical impact of early (0-4 months) MTI and BBC on graft outcomes. Furthermore, we examined the relationship between peripheral blood B cell cytokines and early MTI and BBC. Results 208/372 patients transplanted between 1/13-11/14 had either no inflammation (NI, 36%, 76/208), MTI (34%, 70/208) or BBC (30%, 62/208) on early biopsies (0-4 months). Patients with NI (17%), MTI (24%) and BBC (34%) at 0-4 months exhibited increasing rates (in parentheses) of progression to AR (≥Banff 1A) by 12mo. Further, patients with MTI or BBC (0-4 months) had increased graft loss or impending graft loss (eGFR<30ml/min and >30% decline from baseline) by 50 months when compared to those with NI (Fig. 1A). While graft outcome in the NI group was not affected by progression to late AR (p=0.85), patients with early MTI (Fig 1B) or BBC (Fig 1C) had significantly worse outcomes if they developed late AR. Thus, early allograft inflammation (either MIT or BBC) was not only associated with increased progression to late AR, but those who progressed had worse outcomes. Thus, MTI and BBC, particularly in patients who will progress, represent a clinical phenotype at risk for poor outcomes. Clinical factors, including 3 months histology, could not predict progression of MTI or BBC to late AR. Based on previous results, we asked whether peripheral blood B cell cytokines could predict progression to AR in these patients. 72 patients with either MTI (n=26) or BBC (n=46) had their B cells and cytokines analyzed at 3 months. IL-10:TNF&agr; expression ratio within T1 transitional B cells was significantly lower in both the MTI (6.3X) and BBC (4.6X) patients who progressed compared to those who were stable (p<0.0004). Finally, a low T1 B cytokine ratio strongly predicted late progression to AR (ROC AUC 0.94 p<0.0001, Sen 92%, Spec 88%) in patients with early allograft inflammation (MIT or BBC). Conclusion Patients with early minimal allograft inflammation that progress to AR at 1 year represent a high-risk cohort for graft dysfunction. This group could be identified by 2-4 mo, using the T1 B IL-10:TNF&agr; ratio – allowing early intervention.

DSA with TCMR Identifies High Risk Renal Transplant Recipients that can be Predicted by Proinflammatory Transitional B Cells

Introduction Post-transplant DSA is strongly associated with poor graft outcomes but has limited predictive value. In this prospective study, we aimed to risk stratify patients with early post-transplant DSA to allow timely identification of individuals at risk for poor clinical outcomes. Methods Patients were screened for DSA at 0, 1, 3, 6, 9 & 12 months and analyzed in relation to protocol biopsies at 3 and 12 months and any for-cause biopsies within the first year. To risk stratify DSA positive patients, we analyzed B cell subsets and cytokines of those who had PBMC available at 3 months. Results 294/ 372 of patients transplanted between 01/2013 and 11/2014 with at least one biopsy in the first post-transplant year were included in the analysis. The immunosuppressive regimen was Thymoglobulin induction followed by MPA and Tacrolimus as maintenance therapy. 67/294 (22.8%) of these patients developed DSA. DSA was detected early (< 3 months) in 76% of the patients. DSA was associated with significantly increased rates of subclinical and clinical TCMR (58%) compared to patients lacking DSA (33%, %; p<0.0001). Importantly, patients with DSA plus TCMR had significantly worse chronic allograft changes (1 year protocol biopsy) and increased graft loss or impending graft loss (eGFR < 30ml/min and > 30% decline from baseline) at 4 years compared to those with DSA or TCMR alone (Fig. 1A). Thus, DSA plus TCMR identifies high-risk patients, in whom early identification would allow pre-emptive intervention. Based on prior findings, we asked whether cytokine expression by peripheral blood B cell subsets could predict TCMR in patients with DSA. 43/67 of DSA positive patients had their B cell cytokines analyzed at 3 months by flow cytometry (after 24 h stimulation with CpG and CD40L). Of the markers analyzed, the ratio of IL-10/TNF&agr; expression by T1 transitional B cells (T1B) was significantly lower in patients with DSA plus TCMR compared to those with DSA alone (ratio: 0.94 vs. 4.9, p<0.0001). A low T1B cytokine ratio was a strong predictor of DSA plus TCMR (ROC AUC 0.94, p<0.0001; Fig. 1B). At a cut-off value of 1.26, the T1B cytokine ratio predicted DSA plus TCMR with a positive predictive value of 81% and a negative predictive value of 94%. Reanalysis of the data after removing the 5/43 patients whose DSA was detected after TCMR again showed that the T1 B cytokine ratio strongly predicted concomitant or ensuing TCMR in patients with DSA (ROC AUC 0.94, p<0.0001). Figure. No caption available. Conclusion Thus, patients with DSA plus TCMR represent a high-risk population for adverse graft outcomes, and this outcome can be predicted in DSA positive patients using the T1B cytokine ratio as a biomarker. Deutsche Forschungsgesellschaft (DFG). American Society of Transplantation (AST).