Development Of Chronic Allograft Injury Research Articles

Diarrhea after kidney transplantation: A study of risk factors and outcomes.

Diarrhea in kidney transplant recipients (KTRs) can be associated with significant morbidity. We evaluated 198 KTRs for a history of diarrhea post-kidney transplant at a tertiary care center in western India over 1 year. A protocol-based evaluation of diarrhea was done with respect to clinical features, diagnostic evaluation, associated acute allograft dysfunction, and its impact on long-term allograft function. Primary outcomes of interest were: chronic allograft injury (CAI) and the need for mycophenolate mofetil (MMF) withdrawal. We also assessed the effect of MMF withdrawal on the risk of the development of CAI. Eighty-five of 198 (42.5%) recipients experienced diarrhea and a total of 140 diarrheal episodes were evaluated. The mean age of these 85 recipients was 38 ± 12 years and 72 (84.7%) were males. 73 of 85 recipients were on MMF at the time of diarrhea and in 35 (48%) of them MMF withdrawal was needed for chronic and persistent symptoms. Diarrhea was attributed to infective etiologies in 90 of 140 (64.2%) cases. Among the microbiologically confirmed infective diarrheal episodes, giardia and cryptosporidium were the common pathogens in 11/28 (39%) and 6/28 (21.4%) episodes respectively. One hundred and twenty-eight episodes out of 140 (91.4%) episodes were complicated by acute allograft dysfunction. Forty-one of 85 recipients (48.2%) developed chronic allograft injury and 12 (14.1%) developed allograft rejection (acute and/or chronic). Probability of chronic allograft injury was higher in those with MMF withdrawal. Diarrhea post-kidney transplant adversely affects graft function, especially after MMF withdrawal.

240.3: Detection of CMV Mediated Sub-Clinical Rejection by Urine Biomarkers

Methods: Research on early detection of Cytomegalovirus (CMV) mediated sub-clinical rejection (sAR) is in its nascence. This study explores the efficacy of urine-based biomarkers for sAR risk prognostication. Urine samples were serially collected (1 week- 2yrs) across 125 unique renal allograft recipients from UCSF and UCLA. These CMV+ (blood CMV-PCR) patients received valganciclovir therapy until CMV- for 3 consecutive months. Analysis: We computed a machine-learning based rejection prediction score incorporating urine cell-free DNA (cfDNA), methylated cfDNA, total protein, CXCL10, clusterin and creatinine. Rejection was determined between scores of 32-100; higher score associated with biopsy severity (Yang et al, STM 2021). In a cross-sectional analysis, Kruskal-Wallis test was performed on the urine-score distribution, to determine sAR during CMV+. Subsequently UCSF samples were analyzed longitudinally to establish the relationship between CMV and sAR; this was validated independently in UCLA samples. Results: Significant differences were observed in scores >32 between biopsy-confirmed AR vs. stable (p: 0.0034) and CMV vs. stable (p=0.003). Longitudinal analysis yielded 3 primary sAR patterns following CMV infection; (i)persistence of sAR leading to new development of chronic allograft injury; (ii)early sAR (score >32) followed by a further increase in score (>55) with biopsy confirmed cAR; (iii)sAR (>32) followed by recovery of injury with CMV resolution and a decline in score <32). Conclusions: We provide a urine-based method for detecting sAR at the time of CMV infection, and its potential clinical utility for titrating use of anti-viral therapy and recipient immunosuppression load.

Role of Magnetic Resonance Elastography as a Noninvasive Measurement Tool of Fibrosis in a Renal Allograft: A Case Report

A major reason for poor long-term kidney transplant outcomes is the development of chronic allograft injury, characterized by interstitial fibrosis and tubular atrophy. Currently, an invasive biopsy that samples only <1% of the kidney is the gold standard for detecting kidney allograft fibrosis. We report the use of magnetic resonance elastography (MRE) to quantify tissue stiffness as a noninvasive and whole-kidney measurement tool of allograft fibrosis in a kidney transplant patient at 2 time points. The MRE whole-kidney stiffness values reflected the changes in fibrosis of the kidney allograft as assessed by histologic examination. To our knowledge, this technique is the first observation of change over time in MRE-derived whole-kidney stiffness in an allograft that is consistent with changes in histology-derived fibrosis scores in a single patient.

The predictive value of resistive index obtained by Doppler ultrasonography early after renal transplantation on long-term allograft function.

DUSG is a useful diagnostic tool for the follow-up of renal transplant recipients. The measurement of intrarenal arterial RI by DUSG has been proven to predict short-term AF. The aim of the study was to evaluate the predictive value of DUSG performed during the early after RTx on long-term AF. Seventy patients were enrolled into study. DUSG was performed at third and seventh days after RTx. Patients were divided into two groups according to rate of recovery of graft function as patients with normal graft function and abnormal graft function. Although the RI values were correlated with the AF early after transplantation, they were not correlated with long-term AF. However, the rate of recovery of graft function at early period after RTx was correlated with creatinine level at first year and with glomerular filtration rate at first year and last visit. Although the RI has no predictive value for long-term AF, the rate of recovery of graft function at early post-transplantation period has predictive value for long-term AF; patients with higher RI values early after RTx should be followed carefully for the development of chronic allograft injury.

The role of renin–angiotensin system in the chronic allograft nephropathy: an immunohistochemical study

Background: Evidences suggest a role of renin–angiotensin system (RAS) in the development of chronic allograft injury. Methods: We correlated intrarenal angiotensin-converting enzyme, angiotensin II (Angio II) and transforming growth factor β1 (TGFβ1) expression in 58 biopsies-proven chronic allograft nephropathy (CAN) with tissue injury and allograft survival. Results: The biopsies with CAN were graded according to Banff classification as I (22 cases), II (17) and III (19); 27 biopsies also showed a mononuclear inflammatory infiltrate in scarred areas. There were increased expression of angiotensin converting-enzyme (ACE), Angio II and TGFβ1 mainly in tubulointerstitial compartment in the group with CAN; there was no association of Angio II and TGFβ1 expression with interstitial fibrosis. There were no significant differences of ACE, Angio II and TGFβ1 expression between the patients treated and untreated with RAS blockade, and with the graft outcome. Interstitial inflammatory infiltrate had positive correlation with interstitial fibrosis and significant impact on graft survival at 8 years. Conclusions: Our study showed in a group of cases with CAN a high percentage of inflammatory infiltrate that correlated with interstitial fibrosis and graft outcome. The chronic inflammatory changes in these cases did not show significant association with local RAS expression.

Epidermal growth factor receptor inhibition by erlotinib prevents vascular smooth muscle cell and monocyte–macrophage function in vitro

IntroductionVascular smooth muscle cells (VSMCs) and monocyte–macrophages play a central role during the development of chronic allograft injury, which still remains an important challenge in organ transplantation. Inflammation, fibrosis and accelerated arteriosclerosis are typical features for chronic allograft injury. Growth factors participate in cell proliferation, differentiation and migration in this pathological process. ObjectiveHere we studied the role of epidermal growth factor receptor (EGFR) in VSMC and monocyte–macrophage function in vitro. EGFR inhibition by erlotinib, a selective EGF tyrosine kinase inhibitor, was studied in VSMC proliferation and migration as well as monocyte–macrophage proliferation and differentiation. Materials and methodsRat coronary artery SMCs were used for VSMC studies. As a model for monocyte–macrophage proliferation and differentiation human monocytic cell line U937 was used. Phorbol ester TPA was used to induce these cells to differentiate into macrophages. ResultsPlatelet-derived growth factor (PDGF)-B, a known VSMC inducer, caused 2.1-fold stimulation in VSMC proliferation compared to non-stimulated VSMC. Erlotinib prevented this VSMC proliferation in a dose-dependent manner, p<0.001 in all groups compared to controls. PDGF-B stimulation increased VSMC migration to 2.5-fold when compared with non-stimulated cells. Erlotinib decreased VSMC migration dose-dependently and this effect was significant with all doses, p<0.05. Erlotinib inhibited dose-dependently the proliferation of U937 monocytic cells, p<0.001. Erlotinib prevented also TPA-induced macrophage differentiation in a dose-dependent way, p<0.05. DiscussionErlotinib significantly prevents VSMC proliferation and migration in vitro. Erlotinib inhibited also significantly both monocyte proliferation and differentiation. Our data suggest that EGFR inhibition in VSMC and monocyte function has beneficial effects on chronic allograft injury.

Epidermal Growth Factor Inhibition, a Novel Pathway to Prevent Chronic Allograft Injury

Chronic allograft injury remains a major problem in clinical kidney transplantation and different growth factors participate in its development. Epidermal growth factor (EGF) affects cell proliferation and mitogenesis through its tyrosine kinase receptor. Erlotinib is an orally administered tyrosine kinase inhibitor used in clinical oncology to inhibit EGF signaling. We investigated its effect on the development of chronic allograft injury in an experimental kidney transplantation model. Kidney transplantations were performed between Dark Agouti and Wistar Furth rats. Recipients were immunosuppressed either with cyclosporine A (CsA, 1.5 mg/kg/day subcutaneously) or with CsA and erlotinib (10 mg/kg/day orally). Kidney grafts were harvested after 5 and 90 days for histology and immunohistochemistry. Aorta denudation model was used for the erlotinib dose response study to define the optimal dose for the transplantation study. Epidermal growth factor expression was increased in CsA-treated allografts which developed intense chronic changes on day 90. Erlotinib ameliorated neointimal formation in the dose response study. In addition, erlotinib decreased chronic rejection changes and maintained better graft function in kidney transplantation model. Late posttransplant EGF and EGF receptor levels were reduced with erlotinib. Based on these findings, EGF mediates in part the development of chronic allograft injury. Its inhibition with erlotinib prevents chronic rejection and maintains better allograft function. Therefore, EGF blocking by erlotinib provides a novel pathway to prevent chronic allograft injury.

T helper subsets &amp; regulatory T cells: rethinking the paradigm in the clinical context of solid organ transplantation

Recent years have witnessed remarkable expansion in the knowledge of how various immune/inflammatory cells and T helper (Th) cell subsets, including Th1, Th2, Th9, Th17, Th22, follicular T helper (Tfh) and Treg subpopulations, reciprocally regulate each other. This review highlights current understanding of the Th subsets paradigm, who are the old school players, who are the new kids on the block and how does each come to play in different clinical contexts in solid organ transplantation. The article commences with a brief overview of the development and characteristic cytokine profiles of individual members of the paradigm. However, the main focus of this review is on the current understanding of the Th subset paradigm, and how these unique subpopulations impact host responses towards solid organ allografts. More specifically, it will highlight the recent findings that implicate the paradigm in transplantation. The interplay among different subsets is discussed collectively in the clinical context of pretransplant immunological risk factors such as alloimmunization as well as post-transplant immunological consequences such as rejection. Accumulating evidence suggests that Th17 cells play a role in the development of chronic allograft injury in transplantation of various organs. In vitro, tacrolimus suppressed Th1 and Th2 cells but not Th17 cells. Animal studies suggest that regulatory T cells (Treg)-based therapies could be effective as mechanisms of long-term drug-free transplant tolerance in humans. Indeed, a dual role for TGF-β and Foxp3 in induced tolerance has been proposed, in which TGF-β stimulates Foxp3 expression and is associated with the induction of Treg-facilitating acquisition of tolerance. Exploiting Th subsets' regulatory functions could potentially offer opportunities for immunological interventions in solid organ transplantation.

Expression of acetylcholine receptors by experimental rat renal allografts.

Chronic allograft injury (CAI) is a major cause for renal allograft dysfunction and characterized by vasculopathies, tubular atrophy, and fibrosis. We demonstrated that numerous leukocytes interact with vascular endothelial cells of allografts and produce acetylcholine, which contributes to vascular remodeling. The cholinergic system might be a promising target for the development of novel therapies. However, neither the cellular mechanisms nor the acetylcholine receptors involved in CAI are known. Kidney transplantation was performed in the Lewis to Lewis and in the Fischer-334 to Lewis rat strain combination, which is an established experimental model for CAI. Expression of nicotinic and muscarinic acetylcholine receptors mRNA was quantified in renal tissue by real-time RT-PCR on days 9 and 42 after surgery. We detected CHRNA2–7, CHRNA10, CHRNB2, CHRNB4, and CHRM1–3 mRNA in normal kidneys and in renal transplants. In contrast, CHRNA9, CHRM4, and CHRM5 mRNA remained below the threshold of detection. In renal allografts, CHRNA3 and CHRNB4 mRNA expression were dramatically reduced compared to isografts. In conclusion, we demonstrated that most acetylcholine receptor subtypes are expressed by normal and transplanted kidneys. Allograft rejection downmodulates CHRNA3 and CHRNB4 mRNA. The role of different acetylcholine receptor subtypes in the development of CAI remains to be established.

Dysregulation of Th17 Cells during the Early Post-Transplant Period in Patients under Calcineurin Inhibitor Based Immunosuppression

Accumulating evidence suggests that Th17 cells play a role in the development of chronic allograft injury in transplantation of various organs. However, the influence of current immunosuppressants on Th17-associated immune responses has not been fully investigated. We prospectively investigated the changes in Th17 cells in peripheral blood mononuclear cells (PBMCs) collected before and 1 and 3 months after KT in 26 patients and we investigated the suppressive effect of tacrolimus on Th17 in vitro. In the early posttransplant period, the percentage of Th17 cells and the proportion of IL-17-producing cells in the effector memory T cells (TEM) were significantly increased at 3 months after transplantation compared with before transplantation (P<0.05), whereas Th1/Th2 cells and TEM cells were significantly decreased. The degree of increase in Th17 during the early posttransplant period was significantly associated with allograft function at 1 year after transplantation (r = 0.4, P<0.05). In vitro, tacrolimus suppressed Th1 and Th2 cells in a concentration-dependent manner, but did not suppress Th17 cells even at high concentration. This suggests that current immunosuppression based on tacrolimus is inadequate to suppress Th17 cells in KTRs, and dysregulation of Th17 may be associated with the progression of CAD.

Non-HLA Antibodies to Immunogenic Epitopes Predict the Evolution of Chronic Renal Allograft Injury

Chronic allograft injury (CAI) results from a humoral response to mismatches in immunogenic epitopes between the donor and recipient. Although alloantibodies against HLA antigens contribute to the pathogenesis of CAI, alloantibodies against non-HLA antigens likely contribute as well. Here, we used high-density protein arrays to identify non-HLA antibodies in CAI and subsequently validated a subset in a cohort of 172 serum samples collected serially post-transplantation. There were 38 de novo non-HLA antibodies that significantly associated with the development of CAI (P<0.01) on protocol post-transplant biopsies, with enrichment of their corresponding antigens in the renal cortex. Baseline levels of preformed antibodies to MIG (also called CXCL9), ITAC (also called CXCL11), IFN-γ, and glial-derived neurotrophic factor positively correlated with histologic injury at 24 months. Measuring levels of these four antibodies could help clinicians predict the development of CAI with >80% sensitivity and 100% specificity. In conclusion, pretransplant serum levels of a defined panel of alloantibodies targeting non-HLA immunogenic antigens associate with histologic CAI in the post-transplant period. Validation in a larger, prospective transplant cohort may lead to a noninvasive method to predict and monitor for CAI.

Chronic allograft injury by subclinical borderline change: evidence from serial protocol biopsies in kidney transplantation

PurposeThis study investigated the impact of subclinical borderline changes on the development of chronic allograft injury in patients using a modern immunosuppression protocol.MethodsSeventy patients with stable renal allograft function and who underwent protocol biopsies at implantation, 10 days and 1 year after transplantation were included and classified based on biopsy findings at day 10. The no rejection (NR) group included 33 patients with no acute rejection. The treatment (Tx) group included 21 patients with borderline changes following steroid pulse therapy, and the nontreatment (NTx) group included 16 patients with borderline changes nontreated.ResultsThe Banff Chronicity Score (BChS) and modified BChS (MBChS) were not different among the three groups at implantation (P = 0.48) or on day 10 (P = 0.96). Surprisingly, the NTx group had more prominent chronic scores at the 1-year biopsy, including BChS (3.07 ± 1.33, P = 0.005) and MBChS (3.14 ± 1.41, P = 0.008) than those in the Tx and NR group, and deterioration of BChS was more noticeable in the NTx group (P = 0.037), although renal function was stable (P = 0.66). No difference in chronic injury scores was observed between the Tx and NR groups at the 1-year biopsy.ConclusionSubclinical borderline changes can be a risk factor for chronic allograft injury and should be considered for antirejection therapy.

Animal Models of Chronic Allograft Injury: Contributions and Limitations to Understanding the Mechanism of Long-Term Graft Dysfunction

Advances in immunosuppression have reduced the incidence of acute graft loss after transplantation, but long-term allograft survival is still hindered by the development of chronic allograft injury, a multifactorial process that involves both immunologic and nonimmunologic components. Because these components become defined in the clinical setting, development of animal models enables exploration into underlying mechanisms leading to long-term graft dysfunction. This review presents animal models that have enabled investigation into chronic allograft injury and discusses pivotal models currently being used. The mechanisms uncovered by these models will ultimately lead to development of new therapeutic options to prevent long-term graft dysfunction.

Role of Peritubular Capillaries and Vascular Endothelial Growth Factor in Chronic Allograft Nephropathy

Objective To investigate the role of peritubular capillary damage and vascular endothelial growth factor (VEGF) in chronic allograft injury and to evaluate their correlation with clinical factors. Patients and Methods The study included 56 patients who underwent transplantation between 1987 and 2004 and experienced chronic graft dysfunction. CD34 (peritubular capillaries) and VEGF were evaluated at histologic analysis. Patients were classified into 3 groups: 47 with chronic allograft injury, 9 with pure cyclosporine toxicity, and 26 who served as the control group (time 0 biopsy). Results Compared with the control group, CD34 total expression in chronic nephropathy was indirectly proportional to Banff stage ( P < .05), and VEGF was increased in chronic allograft injury grade I or II or nephrotoxicity ( P < .05). CD34 expression was correlated with age ( P < .007) and number of acute rejection episodes ( P = .005). A negative correlation was observed between expression of CD34 and of VEGF ( P < .001). Low expression of CD34 was associated with risk of graft loss of 1.45 (95% confidence interval, 1.15–7.24; P = .04). Conclusion Peritubular capillaries decreased progressively with development of chronic allograft injury. The VEGF demonstrated a bimodal behavior, increasing at the onset of nephropathy and decreasing in the final stages. Loss of peritubular capillaries was associated with worse graft survival and overexpression of VEGF.

Investigation of Intrarenal Viral Infections in Kidney Transplant Recipients Unveils an Association between Parvovirus B19 and Chronic Allograft Injury

The relevance of viral infections in the development of allograft lesions is still unclear, although some viruses have been implicated. The present study investigated systemic and intrarenal viral infections in kidney transplant recipients and their association with the risk of acute rejection and chronic allograft injuries that are predictive of long-term dysfunction. The presence of DNA sequences of human herpesviruses, polyomaviruses, and parvovirus B19 was analyzed in renal allograft biopsy specimens obtained at baseline, after acute renal dysfunction, and during follow-up evaluation in 69 transplant recipients who were children or young adults. Results were correlated with clinical data, viral DNAemia, and results of renal function tests and allograft histology analyzed at the same time points. Overall, viral DNA was detectable in 46% of baseline and 70% of follow-up biopsy specimens of kidney allografts, where it generally persisted. The most frequently detected viruses were B19 and human herpesvirus 6, already present in donor kidneys, and BK virus and Epstein-Barr virus, usually involving the allograft during follow-up. Among viruses, only the intrarenal persistence of B19 DNA and B19 DNAemia was associated with the development of chronic allograft injury, whereas human cytomegalovirus DNAemia was a risk factor for acute rejection. Parvovirus B19 seems to target the kidney electively. Its intrarenal persistence is associated with chronic kidney allograft injury.

Mycophenolate mofetil: what is the evidence that it decreases chronic rejection?

Purpose of review The question addressed in the title of this paper iscontroversial because of the lack of clear data and conflicts due to the paucity of existing data. Therefore, the purpose of this review is to summarize some of the relevant clinical and experimental findings. Recent findings It has recently been suggested by a retrospective analysis of the United States Renal Data System data that mycophenolate mofetil (MMF) therapy is associated with a significant decrease in the relative risk of chronic allograft failure. Chronic allograft failure, however, may differ from a biopsy-proven chronic allograft nephropathy (CAN). MMF has been shown to inhibit antibody formation in animal models, and alloantibody does correlate with development of chronic allograft injury. Hence, there is compelling rationale to expect MMF therapy to decrease the incidence of chronic rejection of allografts in humans. Nevertheless, current data are only provocative and suggest a need for further direct study of this important question. Summary In summary, it is unclear at this time whether MMF has a direct salutary or deleterious effect on CAN in human renal transplantation.