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CVD remains the major cause of mortality with graft functioning in Kidney transplant recipients (KTRs), with an estimated risk of CV events about 50-fold higher than in the general population. Many strategies have been considered to reduce the CV risk such as the use of mTOR inhibitors. We evaluate whether chronic mTOR inhibition might influence CV aging in KTRs studying the molecular mechanisms involved in this effect. We retrospectively analyzed 210 KTRs with stable graft function on therapy with CNI and mycophenolic acid (Group A, 105 pts.), or with CNI and mTORi (Everolimus, Group B, 105 pts.). The presence of mTOR inhibitor in immunosuppressive therapy was associated to increase serum levels of Klotho with concomitant reduction in FGF-23, with a significant decrease in left ventricular mass. In addition, KTRs with mTORi improved mitochondrial function/biogenesis in PBMC with more efficient oxidative phosphorylation, antioxidant capacity and glutathione peroxidase activity. Finally, group B KTRs presented reduced levels of inflammaging markers such as reduced serum pentraxin-3 and p21ink expression in PBMC. In conclusion, we demonstrated that mTOR inhibition in immunosuppressive protocols prevents the occurrence and signs of CV aging in KTRs.

Primary membranous nephropathy (PMN) is a renal-specific autoimmune disease caused by circulating autoantibodies that target glomerular podocyte antigens (PLA2R/THSD7A). However, very little is known on the molecular mechanisms controlling B cell response in this nephropathy. The present study was aimed at correlating the serum levels of B cell activators BAFF/BLyS and APRIL with the presence of anti-PLA2R antibodies in PMN patients and with long-term clinical outcome. To this aim, 51 patients with anti-PLA2R-positive biopsy-proven PMN and nephrotic range proteinuria (>3.5 g/24 hours) were enrolled between January 2009 and December 2015 and treated with conventional 6-month immunosuppressive therapy. After 6 months, 29 patients (56.9%) cleared circulating anti-PLA2R, while in remaining 22 (43.1%), they persisted. Intriguingly, in the first group, baseline serum levels of BAFF/BLyS and APRIL were significantly lower than those in the second one. Moreover, after 6 months of immunosuppressive therapy, an overall reduction in both cytokine serum levels was observed. However, in PMN patients with anti-PLA2R clearance, this reduction was more prominent, as compared with those with anti-PLA2R persistence. When related to clinical outcome, lower baseline BAFF/BLyS (<6.05 ng/mL) and APRIL (<4.20 ng/mL) serum levels were associated with significantly higher probability to achieve complete or partial remission after 24-month follow-up. After dividing the entire study cohort into three groups depending on both cytokine baseline serum levels, patients with both BAFF/BLyS and APRIL below the cut-off showed a significantly higher rate of complete or partial remission as compared with patients with only one cytokine above the cut-off, while the composite endpoint was achieved in a very low rate of patients with both cytokines above the cut-off. Taken together, these results provide new insights into the role of BAFF/BLyS and APRIL in both the pathogenesis of anti-PLA2R-positive PMN and the response to immunosuppressive therapy., Competing Interests: The authors have nothing to disclose., (Copyright © 2019 Giuseppe Stefano Netti et al.)

ILT3(high)ILT4(high) dendritic cells (DCs) may cause anergy in CD4(+)CD45RO(+)CD25(+) T cells transforming them into regulatory T cells (Tregs). Here, we tested whether chronic exposure to rapamycin may modulate this immunoregulatory pathway in renal transplant recipients. Forty renal transplant patients with biopsy-proven chronic allograft nephropathy and receiving calcineurin inhibitors were randomly assigned to either calcineurin inhibitor dose reduction or withdrawal with rapamycin introduction. At conversion and 2 years thereafter, we measured the rapamycin effects on circulating DCs (BDCA1/BDCA2 and ILT3/ILT4 expression), CD4(+)/CD25(high)/Foxp3(+) Tregs, CD8(+)/CD28(-) T cells, and the Th1/Th2 balance in graft biopsies. In rapamycin-treated patients, peripheral BDCA2(+) cells were significantly increased along with ILT3/ILT4(+) DCs. The number of circulating CD4(+)/CD25(high)/Foxp3(+)/CTLA4(+) Tregs, CD8(+)CD28(-) T cells, and HLA-G serum levels were higher in the rapamycin-treated group. The number of ILT3/ILT4(+)BDCA2(+) DC was directly and significantly correlated with circulating Tregs and CD8(+)CD28(-) T cells. ILT3/ILT4 expression was increased in kidney biopsies at the end of the study period along with a significant bias toward a Th2 response within the graft only in the rapamycin-treated patients. Thus, rapamycin induces the upregulation of ILT3 and ILT4 on the DC surface, and this effect is associated with an increase in the number of Tregs and expansion of the CD8(+)CD28(-) T cell population. This suggests that mTOR inhibition may promote a novel immunoregulatory pathway.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most common form of cystic kidney disease. An inappropriate stimulation of mammalian target of rapamycin may represent the converging point in the molecular pathways leading to renal cyst growth., Methods: The primary objectives of this prospective, open-label, randomized clinical trial were to assess whether rapamycin may reduce the progressive increase in single cyst and total kidney volume in type I ADPKD and the decline in renal function and to identify the optimal rapamycin dose. Fifty-five patients with type I ADPKD were enrolled and randomized to receive ramipril (Group A), ramipril + high-dose rapamycin (Group B, trough level 6-8 ng/mL) and ramipril + low-dose rapamycin (Group C, trough levels 2-4 ng/mL). Rapamycin efficacy was monitored measuring p70 phosphorylation in peripheral blood mononuclear cells., Results: Both rapamycin doses significantly reduced p70 phosphorylation. Nevertheless, total kidney volume increased in all groups after 24 months, although only in Groups A and B, was the final volume significantly higher compared with the baseline. Single cyst final volume was not significantly different in the three groups, although it was increased in Group A compared with the baseline, whereas in Groups B and C, it was significantly reduced. We did not observe any difference in renal function at 24 months among the three study groups. Group A presented a significant worsening of renal function that remained stable in both Groups B and C., Conclusions: Our study would suggest that rapamycin does not influence the progression of type I ADPKD, although the higher drug dose tested prevented both the increase in kidney volume and the worsening of renal function (RAPYD-study, EUDRACT No. 2007-006557-25).

Rapamycin, an immunosuppressive drug used to prevent rejection after kidney transplantation, influences phosphate homeostasis, induces insulin resistance and has been shown to prolong lifespan in animal models. Because Klotho is an aging-suppressor gene controlling phosphate metabolism and insulin sensitivity, we investigated the influence of rapamycin on Klotho expression. A total of 100 kidney transplant recipients, 50 chronically treated with rapamycin and 50 with calcineurin inhibitors, were enrolled; 20 healthy subjects were employed as control. In the rapamycin group, serum phosphate was lower than in the CNI group with an increase in phosphate excretion and a reduction in its reabsorption. In addition, rapamycin increased insulin resistance as shown by HOMA index. Rapamycin treatment of an immortalized proximal tubular cell line induced the expression of Klotho, the phosphorylation of AKT in Ser473, downstream target of mTORC2 and the expression of RICTOR, mTORC2 main component. AKT inhibition reduced the rapamycin-induced expression of Klotho. In vivo rapamycin treatment induced higher degree of RICTOR and AKT Ser(473) expression directly correlating with long-term rapamycin exposure, FE(PO4) and HOMA index. In conclusion, our data would suggest that rapamycin may influence phosphate homeostasis and insulin resistance modulating Klotho expression through mTORC2 activation., (©2011 The Authors Journal compilation©2011 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Background: The mechanisms underlying the development of proteinuria in renal-transplant recipients converted from calcineurin inhibitors to sirolimus are still unknown., Methods: This is a single-center cohort study. One hundred ten kidney transplant recipients converted from calcineurin inhibitors to sirolimus in the period from September 2000 to December 2005 were included in the study. All patients underwent a graft biopsy before conversion (T0) and a second protocol biopsy 2 years thereafter (T2), according to our standard clinical protocol. On the basis of the changes observed in proteinuria between T0 and T2 (median 70%), the patients were divided into two groups: group I (<70%) and group II (>70%). The authors blinded the sirolimus blood trough levels. We investigated in vivo the effects of sirolimus on nephrin, podocin, CD2ap, and actin protein expression. Slit diaphragm (SD)-associated protein expressions were evaluated in T0 and T2 biopsies. The same analysis was performed in cultured human podocytes treated with different doses of sirolimus (5, 10, 20, and 50 ng/mL)., Results: The SD protein expression in group II T2 biopsies was significantly reduced compared with the T0 biopsies and with T2 group I biopsies. In addition, sirolimus blood trough levels directly and significantly correlated with the SD protein expression at T2 graft biopsies. Group II patients presented significantly higher sirolimus blood levels than group I. In vitro study confirmed that sirolimus effect on podocytes was dose dependent., Conclusions: Our data suggest that sirolimus-induced proteinuria may be a dose-dependent effect of the drug on key podocyte structures.

Mycophenolic acid (MPA) appears to have anti-fibrotic effects, but the molecular mechanisms underlying this are unknown. We prospectively studied 35 stable kidney transplant recipients maintained on cyclosporine and azathioprine. We converted 20 patients from azathioprine to enteric-coated mycophenolate sodium (EC-MPS) and continued the remaining 15 patients on azathioprine. Exploratory mRNA expression profiling, performed on five randomly selected EC-MPS patients, revealed significant upregulation of neutral endopeptidase (NEP), which is an enzyme that degrades angiotensin II. We confirmed these microarray data by measuring levels of NEP expression in all subjects; in addition, we found that NEP gene expression correlated inversely with proteinuria. In an additional 33 patients, glomerular and tubular NEP protein levels from renal graft biopsies were significantly higher among the 13 patients receiving cyclosporine + EC-MPS than among the 12 patients receiving cyclosporine + azathioprine or 8 patients receiving cyclosporine alone. Glomerular NEP expression inversely correlated with glomerulosclerosis and proteinuria, and tubular NEP expression inversely correlated with interstitial fibrosis. Incubation of human proximal tubular cells with MPA increased NEP gene expression in a dose- and time-dependent manner. Moreover, MPA reduced angiotensin II-induced expression of the profibrotic factor plasminogen activator inhibitor-1, and a specific NEP inhibitor completely reversed this effect. Taken together, our data suggest that MPA directly induces expression of neutral endopeptidase, which may reduce proteinuria and slow the progression of renal damage in kidney transplant recipients.

Background: Chronic allograft nephropathy (CAN) is characterized by deposition of extracellular matrix (ECM) in all renal compartments. PAI-1 seems to play a pivotal role in ECM turnover in CAN. Rapamycin has been shown to improve long-term graft survival in patients with CAN. The aim of the study was to evaluate the molecular mechanisms underlying the beneficial effects of rapamycin on CAN progression at glomerular and tubulointerstitial level., Methods: After a biopsy-proven CAN diagnosis (T0), 18 patients on calcineurin inhibitors (CNI) were randomly assigned in a 2:1 ratio to continue CNI (6 patients) or to receive rapamycin (RAPA; 12 patients). After 2 years of treatment (T24), all patients underwent a second renal biopsy. Morphometric analysis was conducted at T0 and at T24. PAI-1 expression was evaluated at T0 and T24 by immunohistochemistry. We evaluated the effect of rapamycin on PAI-1 gene expression in cultured proximal tubular cells incubated with CD40L or thrombin, two potential CAN pathogenic mediators., Results: The RAPA group showed a significant regression of glomerulosclerotic lesions and only a 26% increase in interstitial fibrosis after 2 years compared to baseline, whereas the CNI group showed progression of glomerulosclerosis and 112% increase in fibrosis. Glomerular and tubulointerstitial PAI-1 expression was reduced compared to the baseline in the RAPA group, while they were unchanged in the CNI group. In vitro data showed that rapamycin significantly reduced PAI-1 gene expression induced by both CD40L and thrombin in proximal tubular epithelial cells., Conclusions: These data suggest that rapamycin may modulate ECM deposition in CAN reducing PAI-1 expression.

Sirolimus (SRL) has a concentration-related effect on hematopoiesis. In this study, 430 renal transplant recipients were randomized (1:1) 3 months post-transplantation to continue SRL-cyclosporine (CsA)-steroids (ST) or to have CsA withdrawn (SRL-ST). Over 5 years, on therapy calculated glomerular filtration rate (GFR), hematological indices, erythropoietin (EPO) use, and rates of mild, moderate, and severe anemia were determined. Longitudinal analyses using linear mixed models examined covariates predicting hemoglobin (Hgb) levels. Mean Hgb was significantly lower with SRL-ST at 6 months; but subsequently became significantly higher (at 2 years, 129 vs. 135 g/l, SRL-CsA-ST vs. SRL-ST, P<0.001). Mean corpuscular volume was low with both therapies, and significantly lower with SRL-ST. EPO use was similar in the two groups, approximately 30% during the first year and 10% thereafter. The incidence of anemia was significantly higher with SRL-CsA-ST>or=2 years. At year 5, only 39.1% of SRL-CsA-ST patients had normal Hgb vs. 68.5% of SRL-ST patients. GFR and recipient age as well as the interaction term x treatment time were significant covariates predicting Hgb. CsA withdrawal followed by SRL immunotherapy resulted in significantly less anemia than SRL-CsA-ST, despite twofold higher SRL exposure. This suggests that the improvement in GFR accompanying CsA withdrawal may mitigate the effect of SRL on hematopoiesis. (ClinicalTrials.gov number: NCT00428064).

The increased efficiency of immunosuppressive drugs obtained in the last few years has significantly reduced the incidence of acute rejection, prolonging transplant survival rates. The inevitable trade-off was however an increased rate of post-transplant infections and malignancies. Furthermore, this problem might get more and more serious in the next future due to the increasing incidence of cancer in immunosuppressed transplant recipients; the introduction of new immunosuppressive strategies is expected to extend significantly allograft survival. The inclusion of older recipients in transplant programs will also likely increase this problem. Thus, cancer may represent a serious cause of morbidity and mortality in patients otherwise successfully treated by organ transplantation. Nevertheless, effective approaches to deal with malignancies in immunosuppressed patients are still far from the clinical arena. Therefore, once cancer occurs in a transplant recipient, clinicians only have two options: to reduce or withdraw the immunosuppression eventually causing acute or chronic allograft rejection, or to continue the standard immunosuppressive therapy while beginning specific therapy for the malignancy. Several clinical studies suggest that the use of immunosuppressive drugs may result in increased cancer incidence, in transplant as well as autoimmune disease patients. This clinical observation is supported by experimental data showing that these drugs enhance cancer cell growth characteristics and inhibit DNA repair mechanisms, clearly suggesting that the increased incidence of neoplastic disease in patients treated with several immunosuppressive drugs is at least partially independent of their immunosuppressive action. In this scenario it is of particular interest the fact that some immunosuppressive drugs have both an anti-rejection and anti-neoplastic activity. In this review we focus our attention on this potential dual role of immunosuppressive therapy in the development of neoplasia in transplanted patients.

Chronic allograft nephropathy (CAN) represents the main cause of renal allograft loss after 1 yr of transplantation. Calcineurin inhibitor (CNI) use is associated with increased graft expression of profibrotic cytokines, whereas rapamycin inhibits fibroblast proliferation. The aim of this randomized, prospective, open-label, single-center study was to evaluate the histologic and clinical effect of rapamycin on biopsy-proven CAN. Eighty-four consecutive patients who had biopsy-proven CAN and received a transplant were randomized to receive either a 40% CNI reduction plus mycophenolate mofetil (group 1; 50 patients) or immediate CNI withdrawal and rapamycin introduction with a loading dose of 0.1 mg/kg per d and a maintaining dose aiming at through levels of 6 to 10 ng/ml (group 2; 34 patients). The follow-up period was 24 mo. At the end of follow-up, 25 patients (group 1, 10 patients; group 2, 15 patients) underwent a second biopsy. CAN lesions were graded according to Banff criteria. alpha-Smooth muscle actin (alpha-SMA) protein expression was evaluated in all biopsies as a marker of fibroblast activation. Graft function and Banff grading were superimposable at randomization. Graft survival was significantly better in group 2 (P = 0.0376, chi2 = 4.323). CAN grading worsened significantly in group 1, whereas it remained stable in group 2. After 24 mo, all group 1 biopsies showed an increase of alpha-SMA expression at the interstitial and vascular levels (P < 0.001); on the contrary, alpha-SMA expression was dramatically reduced in group 2 biopsies (P = 0.005). This study demonstrates that rapamycin introduction/CNI withdrawal improves graft survival and reduces interstitial and vascular alpha-SMA expression, slowing down the progression of allograft injury in patients with CAN.

Background: Recipients of organ transplants are susceptible to Kaposi's sarcoma as a result of treatment with immunosuppressive drugs. Sirolimus (rapamycin), an immunosuppressive drug, may also have antitumor effects., Methods: We stopped cyclosporine therapy in 15 kidney-transplant recipients who had biopsy-proven Kaposi's sarcoma and began sirolimus therapy. All patients underwent an excisional biopsy of the lesion and one biopsy of normal skin at the time of diagnosis. A second biopsy was performed at the site of a previous Kaposi's sarcoma lesion six months after sirolimus therapy was begun. We examined biopsy specimens for vascular endothelial growth factor (VEGF), Flk-1/KDR protein, and phosphorylated Akt and p70S6 kinase, two enzymes in the signaling pathway targeted by sirolimus., Results: Three months after sirolimus therapy was begun, all cutaneous Kaposi's sarcoma lesions had disappeared in all patients. Remission was confirmed histologically in all patients six months after sirolimus therapy was begun. There were no acute episodes of rejection or changes in kidney-graft function. Levels of Flk-1/KDR and phosphorylated Akt and p70S6 kinase were increased in Kaposi's sarcoma cells. The expression of VEGF was increased in Kaposi's sarcoma cells and even more so in normal skin cells around the Kaposi's sarcoma lesions., Conclusions: Sirolimus inhibits the progression of dermal Kaposi's sarcoma in kidney-transplant recipients while providing effective immunosuppression., (Copyright 2005 Massachusetts Medical Society.)

Angiotensin converting-enzyme inhibition (ACEI) is a widely accepted treatment during established renal diseases and beneficial effects have also been reported in IgA nephropathy (IgAN). Immunosuppression with myco-phenolate mofetil (MMF) has recently been introduced in the treatment of immune-mediated renal diseases showing promising results. Preliminary clinical reports are also suggestive that MMF is effective in severe forms of IgAN. We propose a randomised prospective trial aimed to compare long-term renal survival of early IgAN in the course of ACEI therapy with or without MMF immunosuppression.

Ischemia-reperfusion (I-R) injury in transplanted kidney, a key pathogenic event of delayed graft function (DGF), is characterized by tubular cell apoptosis and interstitial inflammation. Akt-mammalian target of rapamycin-S6k and NF-kappaB-inducing kinase (NIK)-NF-kappaB axis are the two main signaling pathways regulating cell survival and inflammation. Rapamycin, an immunosuppressive drug inhibiting the Akt axis, is associated with a prolonged DGF. The aim of this study was to evaluate Akt and NF-kappaB axis activation in patients who had DGF and received or not rapamycin and in a pig model of I-R and the role of coagulation priming in this setting. In graft biopsies from patients who were not receiving rapamycin, phosphorylated Akt increased in proximal tubular, interstitial, and mesangial cells with a clear nuclear translocation. The same pattern of activation was observed for S6k and NIK. However, in rapamycin-treated patients, a significant reduction of S6k but not Akt and NIK activation was observed. A time-dependent activation of phosphatidylinositol 3-kinase, Akt, S6k, and NIK was observed in the experimental model with the same pattern reported for transplant recipients who did not receive rapamycin. Extensive interstitial and glomerular fibrin deposition was observed both in pig kidneys upon reperfusion and in DGF human biopsies. It is interesting that the activation of both Akt and NIK-NF-kappaB pathways was induced by thrombin in cultured proximal tubular cells. In conclusion, the data suggest that (1) coagulation may play a pathogenic role in I-R injury; (2) the Akt axis is activated after I-R, and its inhibition may explain the prolonged DGF observed in rapamycin-treated patients; and (3) NIK activation in I-R and DGF represents a proinflammatory, rapamycin-insensitive signal, potentially leading to progressive graft injury.

Background: Cyclosporin (CsA) level obtained 2 h after the morning dose (C(2)) has been shown to accurately predict total CsA exposure and acute rejection (AR) risk, whereas conventional trough levels (C(0)) do not. The impact of C(2) monitoring on long-term kidney graft function, independent from AR risk, is still unclear, however, and it was assessed in the present study., Methods: We enrolled 39 CsA-treated renal transplant recipients and used 1 year graft function and histological structure as surrogate markers of graft outcome. CsA dose was adjusted according to C(2) levels., Results: In the first 7 days after grafting, 40-51% of patients failed to reach target C(2) levels; nevertheless, at 1 year the incidence of AR was only 2.5% and graft and patient survival was 100%. The decrease of serum creatinine (12-6 months) was associated with significantly higher C(2) levels over time (P = 0.0003) and lower intrapatient variability of CsA relative absorption (CV) (P = 0.0006). One year graft biopsy showed chronic tubulointerstitial lesions in 54.5% of patients. Both C(2) mean levels and the percentage CV independently predicted the severity of chronic histological lesions (R = 0.69, P<0.0001)., Conclusions: Higher C(2) levels, within the proposed target range values, seem to be associated with better renal function and structure.

Delayed graft function (DGF) has long been identified as one of the main correlates of poor graft survival in cadaveric renal transplantation, but the factors that affect its onset and duration are not fully elucidated. The impact of two immunosuppressive protocols on the incidence and length of DGF among kidney transplant recipients of a suboptimal organ was evaluated. Patients were randomly treated with corticosteroids (CS); low-dose cyclosporine (CsA) and sirolimus (SRL; group 1; n = 42); or CS, full-dose CsA, and mycophenolate mofetil (group 2; n = 48). All recipients received immunoprophylaxis with basiliximab. After 3 mo, group 1 discontinued CsA and continued with SRL, whereas group 2 continued the same treatment. The incidence of DGF was similar in the two groups (group 1 = 52.4%; group 2 = 58.3%), whereas its duration was significantly higher in the group 1 (19.0 +/- 6.0 versus 10.3 +/- 3.2 d; P = 0.001). Both groups showed 100% actuarial graft and patient survival at 1-yr. Among DGF patients, serum creatinine (sCr) at discharge was significantly worse in group 1 (sCr, 3.0 +/- 1.0 versus 1.5 +/- 0.2 mg/dl; calculated creatinine clearance, 31.2 +/- 9.3 versus 61.1 +/- 10 ml/min; P = 0.001). During the first year, the former group displayed a significant improvement of graft function, such that at 1-yr, no difference could be measured between groups (sCr, 1.8 +/- 0.5 versus 1.7 +/- 0.4 mg/dl; calculated creatinine clearance, 51.5 +/- 10.2 versus 53.3 +/- 9.4 ml/min). In conclusion, in de novo renal transplanted patients, the administration of SRL, in combination with low-dose CsA, is associated with a delayed recovery from DGF but does not worsen 1-yr graft function.

Background: Chronic allograft nephropathy (CAN) represents the most common cause of late graft loss. Nephrotoxicity from chronic use of calcineurin inhibitors (CNI) has the potential to contribute to CAN. The present investigation aimed to evaluate the impact of early CNI withdrawal on kidney graft function and structure at 1 year in sirolimus (SRL)-treated patients., Methods: Forty consecutive kidney transplant recipients were initially treated with corticosteroids, cyclosporine A (CsA), and SRL (2 mg/day). After 3 months, patients were randomly assigned to either continue the same treatment (group I) or to withdraw CsA and continue SRL (group II). All patients underwent kidney graft biopsy immediately after graft reperfusion (0-hr biopsy) and 12 months after engraftment., Results: Baseline graft biopsy showed a higher degree of renal damage in group II patients (total score, 4+/-1.6 vs. 2+/-0.9; P<0.05). Twelve months after engraftment, CAN was diagnosed in 55% of all patients, of whom 64% were in group I and 36% in group II. CAN lesions were scored as moderate to severe in 90% of group I patients but only 32% of group II patients (P<0.05). A vascular score greater than or equal to 2 occurred in 90% of group I patients and in 38% of group II patients (P<0.05). At 1 year, group I patients showed a significantly worse kidney graft function (serum creatinine, 2.0+/-0.3 vs. 1.3+/-0.3 mg/dL; creatinine clearance, 54+/-14 vs. 66+/-17 mL/min; both P<0.002)., Conclusions: These results suggest that early withdrawal of CsA is a safe option, which allows a significant reduction of chronic histologic damage, particularly vascular injury, of cadaveric kidney allografts.

Background: Angiotensin (Ang) II blockade has been shown to prevent the development of renal injury in immunologically mediated diseases, but the mechanism whereby it exerts its protective effect has not been clearly defined. Transforming growth factor (TGF)-beta1 is a multifunctional cytokine with a potent immunomodulatory activity that has the potential to counteract many of the pro-inflammatory effects apparently evoked by the activation of renin-angiotensin system (RAS) in immune cells., Methods: We set up an ex vivo and in vitro model to evaluate the effect of the angiotensin converting enzyme inhibitor (ACEi) captopril on the gene and protein expression of TGF-beta1 in human peripheral blood mononuclear cells (PBMC)., Results: In 20 kidney transplant recipients chronically treated with cyclosporine (CsA), 1-month treatment with captopril increased TGF-beta mRNA by 120% and TGF-beta1 protein release by 140% upon stimulation of PBMC with phytohemagglutinin (PHA) and phorbol myristate acetate (PMA) ( P<0.01). PBMC from healthy controls, when exposed in vitro to 5 microM captopril, showed a significant increase of TGF-beta1 release, whereas the ACEi enalapril failed to modify the expression of the cytokine. Ang II (100 pM) strongly inhibited TGF-beta1 synthesis by PBMC, and such effect was completely abolished by the addition of 200 ng/mL CsA, as well as by 1 micrpM losartan. Thus, captopril enhances TGF-beta1 gene and protein expression by PBMC by way of a mechanism independent, at least in part, from ACE inhibition, while CsA abrogates the inhibition of TGF-beta1 expression induced by Ang II., Conclusion: Collectively, these findings support the utility of combined treatment with captopril and CsA in the multitherapeutic management of organ transplant and, possibly, a strategy to decrease the dose of the calcineurin inhibitor in kidney-transplant recipients.