Chronic renal transplant loss

Proteomics for Biomarker Discovery for Diagnosis and Prognosis of Kidney Transplantation Rejection

Renal transplantation is currently the treatment of choice for end-stage kidney disease, enabling a quality of life superior to dialysis. Despite this, all transplanted patients are at risk of allograft rejection processes. The gold-standard diagnosis of graft rejection, based on histological analysis of kidney biopsy, is prone to sampling errors and carries high costs and risks associated with such invasive procedures. Furthermore, the routine clinical monitoring, based on urine volume, proteinuria, and serum creatinine, usually only detects alterations after graft histologic damage and does not differentiate between the diverse etiologies. Therefore, there is an urgent need for new biomarkers enabling to predict, with high sensitivity and specificity, the rejection processes and the underlying mechanisms obtained from minimally invasive procedures to be implemented in routine clinical surveillance. These new biomarkers should also detect the rejection processes as early as possible, ideally before the 78 clinical outputs, while enabling balanced immunotherapy in order to minimize rejections and reducing the high toxicities associated with these drugs. Proteomics of biofluids, collected through non-invasive or minimally invasive analysis, e.g., blood or urine, present inherent characteristics that may provide biomarker candidates. The current manuscript reviews biofluids proteomics toward biomarkers discovery that specifically identify subclinical, acute, and chronic immune rejection processes while allowing for the discrimination between cell-mediated or antibody-mediated processes. In time, these biomarkers will lead to patient risk stratification, monitoring, and personalized and more efficient immunotherapies toward higher graft survival and patient quality of life.

Fenofibrate Improved Interstitial Fibrosis of Renal Allograft through Inhibited Epithelial-Mesenchymal Transition Induced by Oxidative Stress

The best treatment for end-stage renal disease is renal transplantation. However, it is often difficult to maintain a renal allograft healthy for a long time following transplantation. Interstitial fibrosis and tubular atrophy (IF/TA) are significant histopathologic characteristics of a compromised renal allograft. There is no effective therapy to improve renal allograft function once IF/TA sets in. Although there are many underlying factors that can induce IF/TA, the pathogenesis of IF/TA has not been fully elucidated. It has been found that epithelial-mesenchymal transition (EMT) significantly contributes to the development of IF/TA. Oxidative stress is one of the main causes that induce EMT in renal allografts. In this study, we have used H₂O₂ to induce oxidative stress in renal tubular epithelial cells (NRK-52e) of rats. We also pretreated NRK-52e cells with an antioxidant (N-acetyl L-cysteine (NAC)) 1 h prior to the treatment with H₂O₂. Furthermore, we used fenofibrate (a peroxisome proliferator-activated receptor α agonist) to treat NRK-52e cells and a renal transplant rat model. Our results reveal that oxidative stress induces EMT in NRK-52e cells, and pretreatment with NAC can suppress EMT in these cells. Moreover, fenofibrate suppresses fibrosis by ameliorating oxidative stress-induced EMT in a rat model. Thus, fenofibrate may effectively prevent the development of fibrosis in renal allograft and improve the outcome.

Chronic allograft nephropathy in rats is improved by the intervention of rhein

AIM

In this study, we investigated the therapeutic efficacy and potential mechanisms of rhein to mitigate chronic allograft nephropathy (CAN) in rats.

MATERIALS AND METHODS

Fisher rat donors and Lewis rat recipients were used to establish the CAN model. Thirty rats with transplanted kidneys were randomly divided into two groups: 16 untreated and 14 rhein = treated rats. Five Lewis rat controls underwent removal of their right kidneys. The Intervention group was administered rhein oral solution (100 mg kg(-1) d(-1)) by gavage after transplantation. The untreated and control groups were given 0.5% sodium carboxymethyl cellulose. Blood and urine samples were collected at 4, 8, and 16 weeks to examine renal function and total urine protein. Half of the rats in each group were sacrifice at 8 or 16 weeks to examine renal pathology. Immunohistochemical examination and real-time polymerase chain reaction of renal tissues were performed to detect expressions of transforming growth-β1(TGF-β1), hepatic growth factor (HGF), bone morphogenetic protein 7 (BMP7), frobronectin, and collgen IV.

RESULTS

Rhein improved renal function and significantly reduced renal fibrosis and interstitial inflammation. The levels of BMP7 and HGF were significantly elevated in the renal tissues of the rhein intervention group. In the meantime, fibronectin and collagen IV were decreased in the extracellular matrix. The expression of TGF-β1 was similar between these two groups.

CONCLUSION

Rhein improved renal function and reduced renal fibrosis and interstitial inflammation by inducing production of HGF and BMP7.

Acidosis and hyperkalemia caused by losartan and enalapril in pediatric kidney transplant recipients

OBJECTIVES

To evaluate the efficacy and safety of losartan and enalapril in pediatric kidney transplant recipients.

MATERIALS AND METHODS

A retrospective review was performed in 31 pediatric kidney transplant recipients who were treated with losartan (50 mg/d, oral) for 1 to 6 months because of mild hypertension and persistent proteinuria. All patients were treated concurrently with enalapril (5 or 10 mg daily, oral), and 12 patients (39%) also were treated with amlodipine (5 or 10 mg daily, oral). Demographic and clinical characteristics of the patients were reviewed.

RESULTS

Losartan use was associated with a significant decrease in mean systolic (before losartan was started, 123 ± 14 mm Hg; before losartan was stopped, 111 ± 10 mm Hg; P ≤ .001) and diastolic blood pressure (before losartan was started, 78 ± 11 mm Hg; before losartan was stopped, 69 ± 10 mm Hg; P ≤ .001) and urinary protein excretion (before losartan was started, 51 ± 45 mg/m2/h; before losartan was stopped, 28 ± 34 mg/m2/h; P ≤ .001). However, losartan therapy was associated with a significant mean increase in serum potassium level (before losartan was started, 4.0 ± 0.4 mmol/L; before losartan was stopped, 5.7 ± 0.5 mmol/L; P ≤ .001) and decrease in pH (before losartan was started, 7.35 ± 0.0; before losartan was stopped, 7.23 ± 0.0; P ≤ .001). Losartan was stopped because of hyperkalemia and acidosis earlier in patients who were on tacrolimus than cyclosporine immunosuppression (tacrolimus, 3 ± 1 mo; cyclosporine, 4.7 ± 0.8 mo; P ≤ .001).

CONCLUSIONS

Losartan and enalapril may be beneficial in pediatric kidney transplant recipients by decreasing blood pressure and proteinuria, with maintenance of stable graft function, but may be associated with serious adverse events including hyperkalemia and life-threatening acidosis.

Reduction of osteopontin in vivo inhibits tubular epithelial to mesenchymal transition in rats with chronic allograft nephropathy

OBJECTIVE

Chronic allograft nephropathy (CAN) is an important etiological factor causing graft loss. However, the mechanism of CAN is unclear. Osteopontin (OPN), a proinflammatory and profibrosis molecule, plays a key role in late stages of renal diseases. We investigated the potential role of OPN in the pathogenesis of CAN.

METHODS

Using a F344 to Lewis rat CAN model, we injected short hairpin RNA (shRNA) constructs targeting OPN or negative control plasmids through the renal vein following electroporation. At 12 weeks after the transplantation, we determined interstitial fibrosis (IF) and tubular atrophy (TA) of the tubular epithelial cells (TECs). OPN expression was examined using Western blots and immunohistochemistry (IHC). Molecules involved in epithelial to mesenchymal transition (EMT) of TECs were examined using IHC and Western blots.

RESULTS

OPN expression in kidney grafts was decreased by the RNA interference (RNAi) group. Histology observations showed IF and TA to be mild with stable renal function in the RNAi-treated group. EMT of TECs was significantly lessened after reducing OPN.

CONCLUSION

Reduction of OPN in vivo inhibited progression of CAN. OPN may be of therapeutic value in transplantation settings.

Interplay between immune responses to HLA and non-HLA self-antigens in allograft rejection

Recent studies strongly suggest an increasing role for immune responses against self-antigens (Ags) which are not encoded by the major histocompatibility complex in the immunopathogenesis of allograft rejection. Although, improved surgical techniques coupled with improved methods to detect and avoid sensitization against donor human leukocyte antigen (HLA) have improved the immediate and short term function of transplanted organs. However, acute and chronic rejection still remains a vexing problem for the long term function of the transplanted organ. Immediately following organ transplantation, several factors both immune and non immune mechanisms lead to the development of local inflammatory milieu which sets the stage for allograft rejection. Traditionally, development of antibodies (Abs) against mismatched donor HLA have been implicated in the development of Ab mediated rejection. However, recent studies from our laboratory and others have demonstrated that development of humoral and cellular immune responses against non-HLA self-Ags may contribute in the pathogenesis of allograft rejection. There are reports demonstrating that immune responses to self-Ags especially Abs to the self-Ags as well as cellular immune responses especially through IL17 has significant pro-fibrotic properties leading to chronic allograft failure. This review summarizes recent studies demonstrating the role for immune responses to self-Ags in allograft immunity leading to rejection as well as present recent evidence suggesting there is interplay between allo- and autoimmunity leading to allograft dysfunction.

Plasma glutathione peroxidase activity in kidney recipients with and without adverse outcome

Kidney function is routinely monitored utilizing classic biochemical parameters including serum or plasma creatinine (Cr), and blood urea nitrogen (BUN) concentrations. This study demonstrates that the simultaneous assessment of plasma glutathione peroxidase (pGPx) and Cr levels provides a better strategy for the immediate follow-up of kidney function in organ recipients. Kidney recipients (Krs; n = 22) were recruited. Blood sampling schedule commenced at day 1 (pre-transplantation) and post-transplantation days (i.e., everyday from 1 until day 14, and thereafter on days 21, 28, 35, 42, 49, and 56). pGPx was measured spectrophotometrically. Candidates for transplantation exhibited lower pGPx than control subjects (42 ± 24 vs. 143 ± 31 U/L; p < 0.005). In Krs with a stable post-transplant outcome, pGPx increased to a maximum at day 28 (214 ± 61 U/L). In a Kr diagnosed with acute tubulonecrosis, pGPx provided a better predictive value (threefold increase) than Cr. In a Kr diagnosed with acute rejection, the increment in Cr values was found to be more pronounced than in pGPx values. The pGPx test is simple, inexpensive and automatable, and should be a valuable diagnostic tool of kidney function in organ recipients with and without troublesome outcome for the follow-up during hospitalization period.

The loss of renal dendritic cells and activation of host adaptive immunity are long-term effects of ischemia/reperfusion injury following syngeneic kidney transplantation

Ischemia/reperfusion injury associated with kidney transplantation induces profound acute injury, influences early graft function and affects long-term graft outcomes. To determine whether renal dendritic cells play any role during initial innate ischemia/reperfusion injury and the subsequent development of adaptive immune responses, we studied the behavior and function of renal graft and host infiltrating dendritic cells during early and late phases of renal ischemia/reperfusion injury. Wild type to GFP-transgenic rat kidney transplantation was performed with and without 24 hours cold storage. Ischemia/reperfusion injury in cold stored grafts resulted in histopathological changes of interstitial fibrosis and tubular atrophy by 10 weeks accompanied by upregulation of mRNAs of mediators of interstitial fibrosis and inflammation. In normal rat kidneys we identified two populations of renal dendritic cells, predominant CD103⁻CD11b/c⁺ and minor CD103⁺CD11b/c⁺ cells. After transplantation without cold storage, grafts maintained CD103⁻ but not CD103⁺ GFP-negative renal dendritic cells for 10 weeks. In contrast, both cell subsets disappeared from cold stored grafts, which associated with a significant GFP-expressing host CD11b/c⁺ cell infiltration that included CD103⁺ dendritic cells with a TNF-α producing phenotype. These changes in graft/host dendritic cell populations were associated with progressive infiltration of host CD4⁺ T cells with effector/effector-memory phenotypes and IFN-γ secretion. Thus, renal graft ischemia/reperfusion injury causes graft dendritic cell loss and was associated with progressive host dendritic cell and T cell recruitment. Renal resident dendritic cells might function as a protective regulatory network.

Hepatitis C and kidney transplantation

Hepatitis C virus (HCV) infection is relatively common among patients with end-stage kidney disease (ESKD) on dialysis and kidney transplant recipients. HCV infection in hemodialysis patients is associated with an increased mortality due to liver cirrhosis and hepatocellular carcinoma. The severity of hepatitis C-related liver disease in kidney transplant candidates may predict patient and graft survival after transplant. Liver biopsy remains the gold standard in the assessment of liver fibrosis in this setting. Kidney transplantation, not haemodialysis, seems to be the best treatment for HCV+ve patients with ESKD. Transplantation of kidneys from HCV+ve donors restricted to HCV+ve recipients is safe and associated with a reduction in the waiting time. Simultaneous kidney/liver transplantation (SKL) should be considered for kidney transplant candidates with HCV-related decompensated cirrhosis. Treatment of HCV is more complex in hemodialysis patients, whereas treatment of HCV recurrence in SLK recipients appears effective and safe.

Pathogenesis of tubulointerstitial fibrosis in chronic allograft dysfunction

The term chronic allograft nephropathy (CAN) was originally coined in 1991 to replace chronic rejection which was used too generalized. However, the revised Banff classification, published in 2007, eliminated the term CAN again because it was felt that the term was used too broadly and prevented the search for the underlying cause. Interstitial fibrosis and tubular atrophy are integral parts of chronic allograft dysfunction and represent in the new classification a separate entity with or without the identification of a specific etiology. Myofibroblasts are the key, albeit not exclusive, effector cells in renal fibrogenesis resulting in upregulated extracellular matrix synthesis and eventually in interstitial fibrosis. These cells are formed mainly by stimulation of resident interstitial fibroblasts but also by differentiation processes of periadventitial cells, bone marrow derived cells and by a process entitled epithelial mesenchymal transition (EMT) of tubular epithelial cells. EMT has been described by many groups to be of high prevalence in renal allograft dysfunction contributing to matrix accumulation and renal function deterioration. This is of particular interest because immunosuppressive therapy has differential effects on EMT with calcineurin inhibitors in particular inducing the process. Moreover, specific therapies inhibiting EMT have been applied in experimental studies although the effects of their application in chronic allograft dysfunction remain to be studied. At the same time, immunosuppression may interfere with physiologic clearance of myofibroblasts by apoptosis, explaining in part the high prevalence of interstitial fibrosis in allograft biopsies. The Fas system has been identified to be mainly responsible for this physiologic apoptosis in non-renal scarring models; however, its relevance for renal fibrosis and particular fibrosis in renal allograft dysfunction remains to be determined. These findings point to a cautious and individualized use of immunosuppressive therapy in patients with allografts and particular those with chronic allograft dysfunction not because of rejection processes. Protocols using CNI-free immunosuppression are interesting options to prevent fibrosis in chronic allograft dysfunction.

Effects of metalloproteinase inhibition in a murine model of renal ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a leading cause of acute tubular necrosis (ATN) and delayed graft function in transplanted organs. Up-regulation of matrix metalloproteinases (MMPs) propagates the microinflammatory response that drives IRI. This study sought to determine the specific effects of Marimastat (Vernalis, BB-2516), a broad spectrum MMP and TNF-alpha-converting enzyme inhibitor, on IRI-induced ATN. Mice were pretreated with Marimastat or methylcellulose vehicle for 4 d before surgery. Renal pedicles were bilaterally occluded for 30 min and allowed to reperfuse for 24 h. Baseline creatinine levels were consistent between experimental groups; however, post-IRI creatinine levels were 4-fold higher in control mice (p < 0.0001). The mean difference between the post-IRI histology grades of Marimastat-treated and control kidneys was 1.57 (p = 0.003), demonstrating more severe damage to control kidneys. Post-IRI mean (+/-SEM) MMP-2 activity rose from baseline levels in control mice (3.62 +/- 0.99); however, pretreated mice presented only a slight increase in mean MMP-2 activity (1.57 +/- 0.72) (p < 0.001). In conclusion, these data demonstrate that MMP inhibition is associated with a reduction of IRI in a murine model.

Association of C-509T and T869C polymorphisms of transforming growth factor-beta1 gene with chronic allograft nephropathy and graft survival in Korean renal transplant recipients

PURPOSE

Transforming growth factor-beta1 (TGF-beta1) has been associated with the promotion of renal allograft interstitial fibrosis and thereby chronic allograft nephropathy (CAN). The literature on TGF-beta1 polymorphisms and their importance in graft survival and CAN is not conclusive.

METHODS

TGF-beta1 gene polymorphisms (C-509T and T869C) were examined in a group of 207 Korean renal transplant recipients using real-time polymerase chain reaction assays. The CAN group (n = 18) was defined by a typical biopsy confirming CAN or chronic calcineurin inhibitor nephrotoxicity. The rest of the patients were classified into the No CAN group (n = 189).

RESULTS

No significant differences were observed in the genotype distributions of both C-509T and T869 polymorphisms between the two groups. Allele frequencies and age-, sex-, HLA mismatch-adjusted odds ratio of each genotype as assessed by logistic regression analysis were also not significantly different between the two groups. Linkage disequilibrium coefficients between polymorphisms indicated that investigated polymorphisms of TGF-beta1 (D' = 0.98) were in tight linkage. However, there were no significant differences in the frequencies of the reconstructed haplotypes between the two groups. Kaplan-Meier method and log-rank tests did not indicate any statistically significant effects of TGF-beta1 gene polymorphisms on graft survival.

CONCLUSION

TGF-beta1 gene polymorphisms (C-509T, T869C) are not significantly associated with an increased risk of development of CAN and graft survival in Korean renal transplant recipients.

Role of NKT cells in allogeneic islet graft survival

Although NKT cells expressing CD1d-reactive TCR exerted protective role in autoimmune diseases, the regulatory function of CD1d-dependent NKT cells in alloimmune responses has not been investigated thoroughly. Here, we demonstrated the regulatory effects of NKT cells using a pancreas islet transplantation model. CD40/CD154 blocking induced long-term graft survival in most B6 recipients, but B6.CD1d(-/-) recipients showed co-stimulation blockade-resistant rejection. Adoptive transfer of NKT cells into B6.CD1d(-/-) restored tolerizing capacity of co-stimulatory blockade. Activation of NKT cells was effective for the prolongation of graft survival and up-regulated membrane-bound TGF-beta expression transiently on their cell surface. The activated CD1d-dependent NKT cells inhibited alloantigen-driven cell proliferation through cell contacts and the beneficial effect of CD154 blocking for allograft survival was related to TGF-beta pathway. Thus, we can conclude that NKT cells are essential for the stable allograft survival and the regulatory function is dependent on, at least in part, TGF-beta engagement.

Intrarenal Cytokine and Chemokine Gene Expression and Kidney Graft Outcome

AIMS

Proinflammatory cytokines are thought to play an important role in various kidney graft diseases resulting in interstitial fibrosis and tubular atrophy frequently found in case biopsies. To explore the role of various cytokines and chemokines in the long-term graft outcome, the transcription patterns of their genes in kidney allograft biopsies were evaluated.

METHODS

The real-time RT-PCR was used to identify intragraft mRNA expression of cytokines and chemokines in 74 kidney graft recipients and the results were correlated with histological and clinical parameters and long-term graft outcome.

RESULTS

We observed up-regulated IL-10 (p < 0.001), TGF-beta1, IL-6, MCP-1, RANTES (p < 0.01) and TNF-alpha (p < 0.05) mRNA expression in patients with chronic allograft nephropathy (CAN) as compared to controls. There were positive correlations between the mRNA expression of IL-6 (p < 0.001), IL-10 (p < 0.01), TNF-alpha, MCP-1 (p < 0.05) and the proteinuria. The up-regulation of intrarenal MCP-1 in patients with CAN increased the risk for the graft failure within the next 42 months (OR 5.1, p < 0.05). Kaplan-Meier survival analysis revealed that proteinuria and higher intragraft expression of TGF-beta1 and MCP-1 predict a poor kidney graft outcome.

CONCLUSION

Expression patterns of intrarenal proinflammatory genes might discriminate patients at a higher risk for the earlier allograft failure.

Reversal of loss of glomerular filtration rate in children with transplant nephropathy after switch to everolimus and low-dose cyclosporine A

Until now there have been no good therapeutic options in children with biopsy-proven transplant nephropathy (TN) and loss of glomerular filtration rate (GFR) while receiving cyclosporine A (CsA), mycophenolate mofetil (MMF) and prednisolone (Pred). In 13 kidney transplanted children (mean age 13 yr, SD 4) with CsA/MMF/Pred immunosuppression, renal biopsy revealed significant TN. MMF was discontinued, CsA dose was reduced to 50% and Everolimus was started (1.6 mg/m(2)/day). Pred was stopped in 10 of 13 patients. The mean GFR was 55 mL/min/1.73 m(2) (SD 24) one yr before switch, 45 mL/min/1.73 m(2) (SD 16, p < 0.05) at the time of switch and 47 mL/min/1.73 m(2) (SD 18, p < 0.05) 12 months later. There were no severe side-effects or acute rejections. Lactate dehydrogenase, cholesterol, creatine kinase, and U-albumin/creatinine ratio did not increase significantly. After six months, the mean certican-C0 level was 4.0 microg/L (SD 1.5) and mean CsA-C0 level was 52 ng/mL (SD 23). The GFR of transplanted kidneys in children with TN improved by changing immunosuppression from CsA/MMF/Pred to everolimus and low-dose CsA.

Outcome of Pregnancy in Renal Allograft Recipients: SIUT Experience

The course of pregnancy and its outcome was studied in renal allograft recipients. Between November 1985 and November 2005, a total of 1481 renal transplants were carried out at the Sindh Institute of Urology and Transplantation (SIUT); among them were 348 females, with 73 potential females for pregnancy. All patients received cyclosporine and prednisolone, with 82% also receiving azathioprine and 4 patients mycophenolate mofetil as a third immunosuppressant drug. We evaluated incidence of hypertension, diabetes, pre-eclampsia, urinary tract infection (UTI), rejection during pregnancy and during 3 months' postdelivery as well as outcomes of pregnancy. Among 73 potential candidates, 31 had 47 pregnancies, after an average of 31 months (8-86 months). Of 31 subjects, 21 subjects were hypertensive on one or two drugs prior to conception. A rise in blood pressure during pregnancy was noticed in 7 patients. Albuminuria from trace to 3+ appeared in 13 patients and glycosuria in one other. Blood sugar levels remained within normal range in all subjects. UTIs occurred during pregnancy in 7 patients. Among 47 pregnancies, 9 had abortions (7 spontaneous, 2 therapeutic) and 6 had preterm deliveries. The others were full-term deliveries: 12 via a lower segment caesarean section and 20 were normal vaginal deliveries. Average birth weight was 4.8 lbs. At an average follow-up of 38 months the serum creatinine values ranged from 0.94 to 2.3 mg %. One patient developed acute irreversible graft dysfunction soon after delivery. Our study demonstrated that pregnancy did not reduce renal graft survival, but newborns are at greater risk of premature birth and low birth weight.

TGF-β1 mRNA upregulation influences chronic renal allograft dysfunction

Acute rejection (AR) is a dominant risk factor for developing chronic allograft nephropathy (CAN) after kidney transplantation. CAN is characterized by progressive interstitial fibrosis. It has been associated with increased transforming growth factor (TGF)-beta1 expression, however, kinetic studies are absent. We investigated whether intragraft TGF-beta1 expression in various causes of early graft dysfunction may influence late renal allograft dysfunction. A total of 174 human renal biopsies were quantified for TGF-beta1 mRNA expression using real-time reverse transcriptase-polymerase chain reaction. Expression levels were correlated with the Banff histopathological grades, TGF-beta1 immunohistology, and clinical follow-up. TGF-beta1 was most markedly upregulated in AR, CAN, and acute tubular necrosis - delayed graft function compared to non-rejecting controls (P < 0.001). TGF-beta1 expression was heightened in borderline changes (P < 0.01), recurrence of glomerulonephritis, and cyclosporine toxicity (P < 0.05). There was no correlation between intragraft TGF-beta1 expression during AR and short-term outcome of a rejection episode. TGF-beta1 gene overexpression during CAN has been shown to be associated with the increased risk for renal allograft dysfunction 18 months after biopsy (odds ratios 9.9 vs 3.2, respectively). Intragraft TGF-beta1 mRNA expression is significantly upregulated in both AR and CAN. Thus, our results support the hypothesis that TGF-beta1 might play a key role in chronic allograft dysfunction.

Heart allograft protection with low-dose carbon monoxide inhalation: effects on inflammatory mediators and alloreactive T-cell responses

BACKGROUND

Carbon monoxide (CO), a byproduct of heme catalysis, has lately received considerable attention as a regulatory molecule in cellular and biological processes. CO has been shown to provide potent protection against a variety of tissue injuries. We hypothesized in this study that low concentration CO would be beneficial for organ allografts, which frequently undergo several types of injury such as ischemia/reperfusion, alloimmune reaction, and inflammation

METHODS

The efficacy of low-dose CO was examined in a fully allogeneic LEW to BN rat heterotopic heart transplantation (HHTx) model. Recipients were kept in air or exposed to low-dose CO (20 ppm) for 14, 28, or 100 days after HHTx under short-course tacrolimus

RESULTS

CO treatment (d0-28, 0-100) was remarkably effective in prolonging heart allograft survival to a median of >100 from 45 days in the air-control group, with significant reductions of arteritis, fibrosis, and cellular infiltration, including macrophages and T cells. CO inhibited intragraft upregulation of Th1 type cytokines (IL-2, IFNgamma), proinflammatory mediators (IL-1beta, TNFalpha, IL-6, COX-2), and adhesion molecule. Shorter CO exposure in early (0-13d) and late (14-28d) posttransplant periods also prolonged graft survival, with a significant inhibition of inflammatory mediators

CONCLUSIONS

These results show that low dose CO inhalation protects heart allografts and can considerably prolong their survival. CO appears to function via multiple mechanisms, including direct inhibition of Th1 type cytokine production and regulation of inflammatory responses.

Molecular comparison of calcineurin inhibitor-induced fibrogenic responses in protocol renal transplant biopsies

The calcineurin inhibitor cyclosporine (CsA) induces a fibrogenic response that may lead to scarring of the renal allograft. This study investigated whether tacrolimus, a novel calcineurin inhibitor, exerts fibrogenic effects to a similar extent. Sixty patients were enrolled in a randomized study: 29 received CsA, and 31 received tacrolimus. Patients were subjected to tailored exposure-controlled calcineurin inhibitor regimens. Protocol biopsies were obtained at the time of transplantation and 6 and 12 mo after transplantation. Cortical TGF-beta and collagens alpha1(I) and alpha1(III) mRNA steady-state levels were determined with real-time PCR. The extent of protein deposition of TGF-beta, alpha-smooth muscle actin, and interstitial collagens in the renal cortex was quantified with computer-assisted image analysis. The extent of interstitial collagen deposition measured with Sirius red and the accumulation of alpha-smooth muscle actin and TGF-beta protein after 6 and 12 mo were similar for both immunosuppressive regimens. mRNA levels of TGF-beta and collagens alpha1(I) and alpha1(III) were not significantly different in the treatment groups either. It is concluded that the fibrogenic response in renal allografts is similar in patients who receive CsA-based regimens and patients who receive tacrolimus-based regimens.

Posttransplantation chronic renal damage in nonrenal transplant recipients

BACKGROUND

The growing problem of relentless deterioration of renal function in patients who undergo transplantation of nonrenal solid organs is bound to have an increasingly important impact as it may not only worsen patient morbidity and mortality but also increase transplantation costs.

METHODS

We reviewed the literature in order to provide a sum of the most important data on the incidence, clinical picture, renal pathology pattern, damage mechanisms, and risk factors, along with strategies for prevention and treatment of chronic renal damage following nonrenal solid organ transplantation.

RESULTS

Literature data report that 10% to 80% of transplanted patients have some degree of renal dysfunction and that they share a common clinical picture characterized by relentless asymptomatic progression, frequent hypertension, mild urinary abnormalities, and pathology features of vascular, glomerular, tubular, and interstitial involvement. These changes are very similar to those reported for chronic nephrotoxicity from calcineurin inhibitors. The occurrence of end-stage renal disease (ESRD) requiring chronic dialysis has been reported in up to 20% of nonrenal transplant recipients. Although there are some organ-specific differences, a group of common risk factors has been recognized, including the use of calcineurin inhibitors as immunosuppressive agents, age, pretransplantation renal function, intraoperative/perioperative factors, concomitant use of other nephrotoxic drugs, infections, and posttransplantation acute renal failure.

CONCLUSION

Calcineurin inhibitor-induced nephrotoxicity is a growing problem and, as the age of recipients of nonrenal organs is increasing, this problem is destined to increase. It would therefore be advisable for nephrologists to share their experiences in immunomodulation with other specialties, so as to favor the cautious extension of calcineurin inhibitor-sparing protocols to the area of life-saving transplants.

Possible Involvement of Urokinase-Type Plasminogen Activator Release From Human Peripheral Blood Lymphocytes in the Pathophysiology of Chronic Allograft Nephropathy

BACKGROUND

Little is known of the fibrinolytic host immune mechanisms responsible for induction of chronic allograft nephropathy (CAN), defined as a loss in glomerular filtration rate (GFR) caused by tubular atrophy and interstitial fibrosis, often with fibrous intimal thickening in the small arteries. However, chronic rejection has been reported to be associated with decreased activity of the fibrinolytic system. In our previous study, [Deamino-Cys1, D-Arg8]-vasopressin (dDAVP) induced urokinase-type plasminogen activator (uPA) release from human peripheral T lymphocytes via arginine vasopressin (AVP) V2-receptor-mediated reaction enhanced by an AVP V1-receptor antagonist. Therefore, we examined the level of uPA released from peripheral T lymphocytes by AVP in transplant patients with CAN in comparison with control groups.

PATIENTS AND METHODS

In this study, we evaluated in vitro uPA releasing activity of lymphocytes obtained from renal allograft patients with well-functioning grafts (n = 9), CAN (n = 5), or acute rejection episodes (n = 5) compared with lymphocytes from healthy volunteers with normal renal function (n = 12) or patients with renal insufficiency (n = 5).

RESULTS

Lymphocytes prepared from patients with chronic allograft nephropathy showed a significantly lower increase in uPA release induced by the combination of the V1-receptor antagonist and dDAVP compared with those from the other groups.

CONCLUSION

This finding suggested that a decrease in uPA release from human peripheral blood lymphocytes by AVP-related peptides may be potentially involved in the pathophysiology of CAN.

What we CAN do about chronic allograft nephropathy: Role of immunosuppressive modulations

Given the potency of modern immunosuppressive agents, kidney transplantation across alloantingen barriers is a routine phenomenon with excellent 1-year graft survival in most centers. However, the improvement in 1-year graft survival has not been matched by improvements in long-term graft function and chronic allograft nephropathy (CAN) remains the second commonest cause of graft attrition over time. Calcineurin inhibitors, namely cyclosporine A (CyA) and tacrolimus, have been implicated as causal agents in the development of the fibrotic processes that are the hallmarks of CAN. Many studies have, therefore, concentrated on the improvement of long term graft function through the modulation of immunosuppressive therapy. It is the purpose of this review to describe and appraise the available evidence for the prevention and management of CAN through modulation of immunosuppressive agents.

Prevention of chronic allograft nephropathy with vitamin D

Chronic allograft nephropathy (CAN) is the leading cause of late allograft loss in kidney transplantation. Interstitial fibrosis and glomerulosclerosis are characteristic of CAN. Transforming growth factor beta-1 (TGFbeta-1) is associated with both of these histologic findings in the transplant setting. Recent studies have suggested that vitamin D signaling pathways may interact with and regulate TGFbeta-1 mediated events. We examined the efficacy of 1,25-dihydroxyvitamin D(3), the active metabolite of vitamin D [1,25-(OH)(2)D(3)], the active metabolite of vitamin D, as monotherapy to prolong allograft survival and preserve renal function in a rat model of CAN, the Fisher 344 to Lewis model. Recipients went without treatment or were treated with cyclosporine A (CSA; 10 days) or 1,25(OH)(2)D(3) (1000, 500 or 250 ng/kg/day). Grafts were harvested at the time of rejection or at 24 weeks post-transplant. A portion of the graft was processed for histology and immunohistochemistry and a second portion was analyzed for protein expression by western blotting. Not only did 1,25-(OH)(2)D(3) treatment significantly prolong graft survival, but it also prevented histological changes associated with CAN. 1,25-(OH)(2)D(3) treatment significantly decreased Smad 2 expression. This TGFbeta signaling molecule is likely involved in fibrosis. Moreover, 1,25-(OH)(2)D(3) treatment increased Smad 7 expression, an important feedback molecule in the TGFbeta-1 signaling pathway. This suggests that 1,25-(OH)(2)D(3) interacts with TGFbeta-1 in limiting histological injury in this model of CAN. Furthermore, 1,25-(OH)(2)D(3), treatment increased expression of matrix metalloproteinase 2 (MMP-2), thus directly affecting levels of another important matrix molecule. Taken together our data suggests that 1,25-(OH)(2)D(3) mitigates CAN in this model by altering TGFbeta-1 and matrix-regulating molecules.

Genetic profiling of aortic allografts: prothymosin alpha as potential target?

Transplant arteriosclerosis is the result of intima proliferation in large vessels upon organ transplantation. Obliteration of the vascular lumen will ultimately lead to ischemia and late graft failure. Gene array analysis was performed to identify factors involved in the pathogenesis of transplant arteriosclerosis. Aortic transplants from Dark Agouti to Wistar Furth rats were performed to identify potential target genes. Hierarchical clustering of genes specifically upregulated in allogeneic but not in syngeneic aortas revealed 19 genes. A gene that fulfilled these criteria is prothymosin alpha (PTMA), a regulator of estrogen receptor transcriptional activity. PTMA gene and protein expression levels were confirmed by PCR and immunohistochemistry. Estrogen receptor staining was increased in allogeneic aortas. Furthermore, cyclin D1 a downstream target of PTMA, was also up regulated in allogeneic aortas. In conclusion, PTMA was identified as potential candidate gene involved in transplant arteriosclerosis.

Angiotensin-Converting Enzyme and Endothelial Constitutive Nitric Oxide Synthase Polymorphisms in Turkish Renal Transplant Population and Possible Influence on Renal Artery Atherosclerosis and Graft Survival

BACKGROUND

Renal transplant recipients are prone to accelerated atherosclerosis secondary to immunosuppressants, which may decrease graft survival. We sought to analyze the effects on renal graft survival of atherosclerotic degeneration in the renal artery and the influence of angiotensin-converting enzyme (ACE) endothelial constitutive nitric oxide synthase (ecNOS) gene polymorphisms.

METHODS AND PATIENTS

Thirty three renal transplant recipients (25 men) of mean age 28.4 +/- 9.6 years, received organs from 11 living related donors and were followed for at least 36 months. Genotyping was performed for the insertion/deletion ACE (I/D), angiotensin (AGT) (M-->T, 235), angiotensine 1 receptor (A-->C, 1166), angiotensin 2-receptor (A-->G, 1223), and ecNOS (b-->a, intron4) gene polymorphisms. Renal artery biopsies were performed during transplantation surgery to analyze the presence of atherosclerosis.

RESULTS

Pathological examination indicated that 18 donor specimens and nine recipient specimens had atherosclerotic degeneration. Survival analysis (36 months) indicated that graft survival rates of recipients who had atherosclerosis in the renal artery and who received an organ from donors with an atherosclerotic renal artery were shorter than in their counterparts (P = .02, P = .04, respectively). Comparison of genetic variations of recipients revealed that CC/TC variation of AGT was higher in patients with atherosclerosis (81% vs 53%, P = .03). There was no significant difference between groups in means of other gene polymorphisms.

CONCLUSION

Renin-angiotensin system gene polymorphism analysis of patients in renal transplantation waiting list may provide information about allograft survival and posttransplant atherosclerotic degeneration at graft vasculature of young transplant recipients.

Mast cell numbers and protease expression patterns in biopsy specimens following renal transplantation from living-related donors predict long-term graft function

In human kidney transplantation the main cause of declining long-term graft function is chronic allograft nephropathy (CAN). Recent studies have implicated human mast cells (MC) in chronic inflammation and fibrosis, MC can be subtyped according to protease content: MC(T) containing tryptase only and MC(TC) containing both tryptase and chymase. We investigated immunohistochemically whether numbers and subtypes of MC in biopsy specimens 100 d after transplantation could predict subsequent fibrosis and graft dysfunction. The total number of MC/high-power field at 100 d after transplantation correlated significantly with change in creatinine clearance (DeltaCcr), defined as (Ccr at 100 d) - (Ccr at 3 yr) (R = 0.597, p = 0.0021); fibrosis index (FI) at 100 d (R = 0.583, p = 0.0066); and DeltaFI, defined as (FI at 3 yr) - (FI at 100 d) (R = 0.406, p < 0.05). The ratio of MC(TC) to total MC at 100 d also correlated with DeltaCcr (R = 0.491, p = 0.0148), FI at 100 d (R = 0.527, p = 0.0081), and DeltaFI (R = 0.417, p < 0.05). Thus, increases in number of total MC and the ratio of MC(TC) to total MC in early biopsy specimens were related to decline of long-term graft function and fibrosis.

C4d peritubular capillary staining in chronic allograft nephropathy and transplant glomerulopathy: an uncommon finding

The true incidence of positive C4d staining in the peritubular capillaries of biopsies with chronic allograft nephropathy (CAN) and transplant glomerulopathy (TGP) remains controversial. We retrospectively reviewed all transplant biopsies performed at Saint Louis University Hospital between June 2002 and May 2004. We examined the incidence of positive C4d staining in the peritubular capillaries of biopsy specimens with pure CAN with or without features of TGP. We identified 54 biopsies in 43 patients showing CAN. The average age was 46 +/- 13 years. The average creatinine at the time of biopsy was 308 +/- 211 micromol/l (3.5 +/- 2.4 mg/dl). Twenty (37%) biopsies exhibited features consistent with TGP. Only two biopsies had positive C4d staining in the peritubular capillaries. The C4d positive biopsies were from two different patients; one patient had donor specific antibodies (DSA) against HLA class 1 at the time of biopsy and the other patient had no detectable DSA. None of the TGP biopsies showed peritubular C4d staining. C4d staining of the peritubular capillaries appears to be rare in patients with pure CAN with and without TGP features.

Increased Expression of Renin in Chronic Allograft Nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN) is the main cause of renal transplant failure in the first decade posttransplant. The precise pathogenetic mechanism for CAN is not completely understood. A possible role of renin-angiotensin system for CAN has been suggested through clinical observations that angiotensin-converting enzyme inhibition and angiotensin II receptor blockers prevent CAN.

METHODS

Distribution of renin-positive cells in allograft biopsy specimens was examined immunohistochemically in 23 renal transplant recipients diagnosed with CAN Biopsy specimens obtained from seven recipients with stable renal function were examined as controls. Histologic evaluation was performed based on the Banff 97 classification.

RESULTS

Renin-positive cells were found in the juxtaglomerular apparatus (JGA) adjoining the afferent arterioles in both groups. When the number of renin-positive cells in JGA was defined as a renin index, it was significantly higher in the CAN than the control group (P = .007). There was no significant difference in age, interval between transplantation and biopsy, and blood pressure between groups. Only a significantly higher serum creatinine was found in the CAN group.

CONCLUSIONS

The increased renin-positive cells in JGA suggest a significant role of the intrarenal renin-angiotensin system activation in the development of CAN.

Interferon therapy in hemodialysis patients with chronic hepatitis C: study of tolerance, efficacy and post-transplantation course

BACKGROUND

The potential benefit of pre-transplant treatment of chronic hepatitis C on long-term evolution after renal transplantation is not clear.

METHODS

Fifty successive renal transplant candidates had their sera positive for HCV RNA and a biopsy-proven chronic hepatitis. Out of these, 18 patients received a standard course of interferon-alpha2b (IFN; 3 MU three times weekly after hemodialysis sessions for 6 months).

RESULTS

IFN was discontinued in 2 patients (11%) due to persistent leukopenia. HCV RNA turned negative in 10 patients of the treatment group and in none of the control group. Two patients of the IFN group had a virological relapse post-transplantation. Post-transplant follow-up periods were 41.5 +/- 15 and 50 +/- 16 months for the treated and control groups respectively. Transaminases remained normal in all patients of the IFN group after transplantation. In contrast, biochemical evidence of acute and chronic hepatitis was observed in 5 (p = 0.03) and 13 (p = 0.002) patients, respectively, of the control group. Logistic regression analysis identified non-receiving IFN before transplantation as a risk factor for post-transplant hepatic dysfunction (odds ratio = 11.7, p = 0.003) and for chronic allograft nephropathy (odds ratio = 11.6, p = 0.02).

CONCLUSIONS

IFN-treated patients had a significantly better post-transplant hepatic function and significantly lower rates of chronic allograft nephropathy.

[Immunological tolerance and liver transplantation]

The induction of tolerance to allografts has traditionally been one of the basic aims of transplantation research. Multiple data obtained in experimental models indicate that the outcome of transplantation (rejection versus acceptance/tolerance) depends on the balance between allo-reactive cytopathic lymphocytes and immunoregulatory lymphocytes. Thus, most tolerance-inducing treatments aim to reduce the number of allo-aggressive lymphocytes and, at the same time, to increase the population of regulatory lymphocytes, which ensure graft viability once drug therapy has been withdrawn. Liver allografts are singular in that they are accepted without the need for treatment in most experimental models. Likewise, in humans, liver grafts also show a lower susceptibility to rejection than any other organ and immunosuppressive treatment can be completely eliminated in approximately 25% of recipients. Many mechanisms have been proposed to explain the tolerogenic properties of the liver. Notable among these are the effects derived from the large number of passing leukocytes present in the liver and its peculiar anatomy that maximizes contact among blood lymphocytes and liver cells with tolerogenic potential. Although there are many cases of tolerance in human allograft recipients, therapeutic strategies that would allow predictable tolerance induction and without a high risk of adverse affects are still lacking. Therefore, most studies in humans have traditionally aimed to minimize doses of immunosuppressive drugs rather than eliminate them. However, recent results in preclinical models and pilot studies indicate that therapeutic protocols for tolerance induction may become available in the not too distant future.

Reduction of postischemic immune inflammatory response: an effective strategy for attenuating chronic allograft nephropathy

BACKGROUND

Ischemia added to the allogeneic background accelerates the cellular mechanisms involved in alloresponsiveness, supporting the influence of early nonspecific inflammatory injury on chronic allograft nephropathy (CAN). The authors hypothesize that reinforcing initial immunosuppressive regimens may prevent immunogenicity derived from postischemic inflammatory responses, attenuating CAN.

METHODS

Lewis rats engrafted with Fischer kidneys received for 15 days overimmunosuppressive doses of rapamycin, a standard cyclosporine regimen, or both, and were followed functionally for 24 weeks. Animals were grouped according to the initial immunosuppressant or cold-ischemia period. Grafts were evaluated for acute inflammatory response at 1 week and for chronic histologic damage at 24 weeks.

RESULTS

Rats under cyclosporine alone displayed the highest mortality, which was decreased in the long term by reducing cold ischemia or by strengthening immunosuppression. At 24 weeks, all rapamycin-treated groups displayed much less severe tubulointerstitial and vascular damage. The combination of both immunosuppressants offered better functional outcome and a global reduction in chronic histologic damage. After 1 week, ATN and profibrotic features appeared in all 5-hr ischemic animals, indicating that cyclosporine and rapamycin co-treatment did not induce further nephrotoxicity. Treatment with rapamycin, alone or combined with cyclosporine, greatly reduced the severe immune-inflammatory damage, including vessels, shown in cyclosporine-treated ischemic grafts.

CONCLUSIONS

Strengthening initial immunosuppression attenuates the intensity and extent of the early postischemic immune-inflammatory response as well as later function and structure of renal allografts. Severe CAN may be prevented by reducing cold ischemia or strengthening immunosuppression. Because the former approach is not always possible, reinforcement of early immunosuppression constitutes an excellent alternative.

Contribution of CD4+ and CD8+ T cells and interferon-gamma to the progress of chronic rejection of kidney allografts: the Th1 response mediates both acute and chronic rejection

T cells mediating chronic rejection (CR) of human kidney allografts were characterized by comparing them with those mediating acute rejection (AR). Two lines of analysis were performed using biopsy specimens (23 CR and 8 AR). First, the extent of infiltration of CD4+ and CD8+ T cells into allografts was assessed from mRNA expression of CD4 and CD8. The group of CR specimens was not significantly different from the group of AR specimens in terms of the extent of CD4+ and CD8+ T cell infiltration, underlining the importance of the immunological contribution to the progress of CR. Second, Th1/Th2 polarization in infiltrating T cells was investigated by measuring mRNA expression of interferon gamma (IFN-gamma; a Th1 cytokine) and interleukin 4 (IL-4; a Th2 cytokine). IFN-gamma expression was detected in most CR specimens, and was not significantly different between the group of CR specimens and the group of AR specimens. On the other hand, IL-4 expression was detected in only two CR specimens and one AR specimen; from its pathological features, the AR in this last case was concomitant with CR. These results suggest that most cases of CR and of AR are mediated by Th1 mechanisms, although some cases of CR show features of both Th1 and Th2.

Antibody response against the glomerular basement membrane protein agrin in patients with transplant glomerulopathy

Chronic allograft nephropathy (CAN) of renal allografts is still the most important cause of graft loss. A subset of these patients have transplant glomerulopathy (TGP), characterized by glomerular basement membrane (GBM) duplications, but of unknown etiology. Recently, a role for the immune system in the pathogenesis of TGP has been suggested. In 11 of 16 patients with TGP and in 3 of 16 controls with CAN in the absence of TGP we demonstrate circulating antibodies reactive with GBM isolates. The presence of anti-GBM antibodies was associated with the number of rejection episodes prior to diagnosis of TGP. Sera from the TGP patients also reacted with highly purified GBM heparan sulphate proteoglycans (HSPG). Indirect immunofluorescence with patient IgG showed a GBM-like staining pattern and colocalization with the HSPGs perlecan and especially agrin. Using patient IgG, we affinity purified the antigen and identified it as agrin. Reactivity with agrin was found in 7 of 16 (44%) of patients with TGP and in 7 of 11 (64%) patients with anti-GBM reactivity. In conclusion, we have identified a humoral response against the GBM-HSPG agrin in patients with TGP, which may play a role in the pathogenesis of TGP.

The Impact of Age on Rejection in Kidney Transplantation

The time to failure of a renal allograft is determined by the initial function achieved after transplantation, the number and severity of insults to the graft, and a number of tissue characteristics. The insults a graft usually encounters include ischaemia/reperfusion injury, acute rejection episodes, drug-related nephrotoxicity, hypertension and hyperlipidaemia. Important tissue characteristics include susceptibility to injury and the ability of the tissue to repair damage. Elderly transplant recipients are considered poor immune responders but if a single acute rejection episode occurs this is more likely to significantly shorten graft and patient survival in this age group. Two issues have been identified with the use of old (>50 years of age) donor kidneys. First, compared with kidneys from younger donors, they have an increased incidence of acute interstitial rejection. Secondly, once a rejection episode occurs, the ability to mount a tissue repair process seems impaired. An explanation for the increased loss of grafts from old donors that have experienced acute rejection episodes is that such kidneys have fewer nephrons that function adequately and that the cumulated effect of damage results in an earlier demise of the graft compared with younger donor kidneys. Alternatively, graft parenchymal cells may undergo premature senescence or aging as a result of multiple injuries and repair. If progressive loss of renal mass or senescence is the mechanism responsible for increased graft loss, then it is expected that grafts from older donors will show a progressive decrease in function over time and that the rate of decline of function will correlate with donor age. We have suggested that increased graft loss of older donor kidneys results from increased incidence of acute rejection episodes in the early post-transplantation months together with a partly impaired ability to repair the tissue. Drug pharmacokinetic parameters are generally little influenced by age. However, the degree to which drugs suppress the immune system, and the extent to which kidneys from older donors are susceptible to the nephrotoxic effects of certain drugs, are unpredictable. There appears to be a more delicate balance between adequate immunosuppression and excess nonimmune toxicity in patients receiving older kidneys. Outcome parameters in elderly renal transplant recipients are currently dominated by increased death from infectious disease and drug-related (cardiovascular) causes. Increased susceptibility to nephrotoxic drugs, and to calcineurin inhibitors in particular, may be related to the increased risk of allograft failure experienced by the elderly as a surrogate for chronic allograft nephropathy.

Clonality analysis of T cells mediating acute and chronic rejection in kidney allografts

The clonality of T-cell populations mediating acute and chronic rejection (AR and CR, respectively) of kidney allografts was ascertained by investigating the diversity of TCRBV genes expressed by allograft-infiltrating T cells. Both oligoclonality and polyclonality cases were found in biopsy specimens of AR as well as CR. These results indicated that the T-cell clonality in each specimen did not correlate directly with the mode of rejection. When AR and CR specimens were compared, however, the CR specimen group was significantly more polyclonal (or less oligoclonal) than the AR group. This result may reflect the higher chance of epitope spreading in the more slowly progressing CR than in AR.

Clinical experience of mycophenolate mofetil in the treatment of chronic allograft nephropathy in kidney transplantation: Three-year follow-up

BACKGROUND

Mycophenolate mofetil (MMF) in conjunction with calcineura antagonists has been shown to prevent acute rejection in renal allograft recipients. Its role in treatment of chronic rejection or allograft nephropathy is still controversial. We initiated the study to investigate the effect of adding MMF to a cyclosporine plus prednisolone regimen in renal recipients with chronic allograft nephropathy.

MATERIALS AND METHODS

We retrospectively studied 36 patients with chronic allograft nephropathy, defined clinically as increased of serum creatinine, proteinuria, and hypertension. Renal function, cyclosporine level, renal biopsy, and renal scan were regularly done as indicated. MMF was added to 20 recipients after initial treatment with cyclosporine and prednisolone. The other 16 recipients were managed without adding MMF. Serum creatinine was monitored for 3 years.

RESULTS

The demographic characteristics of the patients in the two groups were comparable. The average dose of prednisolone was unchanged throughout the study and the trough level of cyclosporine was maintained in the range of 100 to 150 ng/mL. The serum creatinine decreased initially in the group on MMF, but renal function deteriorated progressively after 6 months. There was a difference in serum creatinine between the two groups but this did not reach statistical significance.

CONCLUSION

MMF therapy tender to improve renal function initially but did not attenuate significantly the impairment in chronic allograft nephropathy.

ACE inhibition limits chronic injury of kidney transplant even with treatment started when lesions are established

BACKGROUND

Inhibition of the renin-angiotensin system (RAS) prevents development of chronic allograft dysfunction in experimental animals. Whether this therapeutic approach is effective even if started when signs of allograft nephropathy are already manifested has not been investigated.

METHODS

To address this issue, we studied the effect of a late treatment with the angiotensin-convertine enzyme (ACE) inhibitor trandolapril in the Fisher 344 to Lewis rat kidney transplant model. Seven months after transplant a renal biopsy was done for graft histology examination. Thereafter rats received either no treatment (allograft-none) or trandolapril until sacrifice at month 13.

RESULTS

All animals were alive at the end of the study with the exception of a rat in the untreated group that died of renal insufficiency at day 292. Despite the fact that the grafts had already signs of structural injury and function impairment at the time treatment was stated, trandolapril completely restored renal function to baseline pretransplant values. Trandolapril also halted the progression of glomerular damage and suppressed intragraft T-lymphocyte infiltration and reduced the expression of the chemokine monocyte chemoattractant protein-1 (MCP-1). However, trandolapril had no direct effect on T cell function, since in vivo treatment did not modify recipient T-cell alloreactivity against donor antigens.

CONCLUSION

These findings provide the basis for a novel treatment intervention with RAS blockade that, together with pharmacologic inhibition of the immune response, could interrupt progression of chronic allograft dysfunction and injury.

The role of the vitamin K-dependent growth factor Gas6 in glomerular pathophysiology

PURPOSE OF REVIEW

The product of growth arrest-specific gene 6 (gas6) is a unique vitamin K-dependent growth-potentiating factor for vascular smooth muscle cells, and anticoagulant warfarin inhibits the activation process of the protein. It has been reported that Gas6 is also a mitogen for mesangial cells, and that warfarin inhibits mesangial cell proliferation by blocking the activation of Gas6. A recent series of studies has revealed the in-vivo roles of Gas6 and its receptor Axl in the progression of various kidney diseases. This review summarizes these studies and discusses the possible interventions targeting the Gas6/Axl pathway to prevent the progression of kidney diseases.

RECENT FINDINGS

The expression of Gas6 and Axl is upregulated in an acute model of glomerulonephritis in rats, and the interference of the Gas6/Axl pathway by warfarin or the extracellular domain of Axl inhibits the progression of diseases. Induction of chronic glomerulonephritis in Gas6 mice results in less mortality, proteinuria, and histological changes of kidneys compared to wild-type mice. Administration of recombinant Gas6 reverses these phenotypes. Expression of Gas6 is also upregulated in streptozotocin-induced diabetic nephropathy, and administration of low-dose warfarin decreases albuminuria and hypertrophy of glomeruli. Possible roles of Gas6 are also reported in renal allograft dysfunction of rats and humans.

SUMMARY

The importance of the Gas6/Axl pathway has been implicated in many types of kidney disease. Further investigations on the role of the Gas6/Axl pathway in human kidney diseases and the development of specific antagonists targeting the pathway are warranted.

The pathobiology of chronic allograft nephropathy: Immune-mediated damage and accelerated aging

Chronic allograft nephropathy includes chronic calcineurin nephrotoxicity, recurrent and de novo glomerulonephritis and a group of disorders with graft dysfunction of unknown etiology designated chronic rejection. Review of risk factors of the latter category show that the chronic rejection lesions emerge in organs that have undergone injury. Despite the relevance of nonalloantigen-dependent progression factors in the tissue injury, alloantigen-dependent factors predominate in the pathogenesis. Lately, B cell responses have received increasing interest in transplant rejection and include responses against both major histocompatibility complex (MHC) and tissue-specific antigens, mainly on the endothelium and in the glomeruli. These humoral responses are thought to be involved in the development of vascular and glomerular lesions. Furthermore, at the tissue level, markers of senescence are found in the tubular epithelium contributing to the lesions of tubular atrophy and interstitial fibrosis.

Strategies for ensuring effective surveillance in post-transplant patients: practical organization and clinical evaluation

Results of renal transplantation have improved steadily over the years. This article reviews the current status of patient and graft survival and discusses major causes of mortality and renal allograft failure. Review of recent literature demonstrates that the traditional enemies of transplantation, acute rejection and opportunistic infections are no longer major problems facing transplantation. Chronic graft nephropathy and death with functioning graft due to cardiovascular disease are the main challenges in the current era. An impact of an early graft thrombosis, recurrent renal disease and post-transplant malignancies are also reviewed. Chronic graft nephropathy is examined in a context of differences between two calcineurin inhibitors, cyclosporin microemulsion and tacrolimus. Strategies of post-transplant surveillance are suggested.