Transforming growth factor (TGF)-beta mimics and anti-TGF-beta antibody abrogates the in vivo effects of cyclosporine: demonstration of a direct role of TGF-beta in immunosuppression and nephrotoxicity of cyclosporine

NFAT-Specific Inhibition by dNP2-VIVITAmeliorates Autoimmune Encephalomyelitisby Regulation of Th1 and Th17

Nuclear factor of activated T cells (NFATs) is an important transcription factor for T cell activation and proliferation. Recent studies have highlighted the role of NFATs in regulating the differentiation of effector CD4 T helper (Th) subsets including Th1 and Th17 cells. Because controlling the effector T cell function is important for the treatment of autoimmune diseases, regulation of NFAT functions in T cells would be an important strategy to control the pathogenesis of autoimmune diseases. Here, we demonstrated that an NFAT inhibitory peptide, VIVIT conjugated to dNP2 (dNP2-VIVIT), a blood-brain barrier-permeable peptide, ameliorated experimental autoimmune encephalomyelitis (EAE) by inhibiting Th1 and Th17 cells, but not regulatory T (T_reg) cells. dNP2-VIVIT negatively regulated spinal cord-infiltrating interleukin-17A (IL-17A) and interferon (IFN)-γ-producing CD4⁺ T cells without affecting the number of Foxp3⁺ CD4⁺ T_reg cells, whereas dNP2-VEET or 11R-VIVIT could not significantly inhibit EAE. In comparison with cyclosporin A (CsA), dNP2-VIVIT selectively inhibited Th1 and Th17 differentiation, whereas CsA inhibited the differentiation of all T cell subsets including that of Th2 and T_reg cells. Collectively, this study demonstrated the role of dNP2-VIVIT as a novel agent for the treatment of autoimmune diseases such as multiple sclerosis by regulating the functions of Th1 and Th17 cells.

Revisiting the Concept of Targeting NFAT to Control T Cell Immunity and Autoimmune Diseases

The nuclear factor of activated T cells (NFAT) family of transcription factors, which includes NFAT1, NFAT2, and NFAT4, are well-known to play important roles in T cell activation. Most of NFAT proteins are controlled by calcium influx upon T cell receptor and costimulatory signaling results increase of IL-2 and IL-2 receptor. NFAT3 however is not shown to be expressed in T cells and NFAT5 has not much highlighted in T cell functions yet. Recent studies demonstrate that the NFAT family proteins involve in function of lineage-specific transcription factors during differentiation of T helper 1 (Th1), Th2, Th17, regulatory T (Treg), and follicular helper T cells (Tfh). They have been studied to make physical interaction with the other transcription factors like GATA3 or Foxp3 and they also regulate Th cell signature gene expressions by direct binding on promotor region of target genes. From last decades, NFAT functions in T cells have been targeted to develop immune modulatory drugs for controlling T cell immunity in autoimmune diseases like cyclosporine A, FK506, etc. Due to their undesirable side defects, only limited application is available in human diseases. This review focuses on the recent advances in development of NFAT targeting drug as well as our understanding of each NFAT family protein in T cell biology. We also discuss updated detail molecular mechanism of NFAT functions in T cells, which would lead us to suggest an idea for developing specific NFAT inhibitors as a therapeutic drug for autoimmune diseases.

Activation of renal profibrotic TGFβ controlled signaling cascades by calcineurin and mTOR inhibitors

The calcineurin inhibitors (CNI) cyclosporine A (CsA) and tacrolimus represent potent immunosuppressive agents frequently used for solid organ transplantation and treatment of autoimmune disorders. Despite of their immense therapeutic benefits, residual fibrosis mainly in the kidney represents a common side effect of long-term therapy with CNI. Regardless of the immunosuppressive action, an increasing body of evidence implicates that a drug-induced increase in TGFβ and subsequent activation of TGFβ-initiated signaling pathways is closely associated with the development and progression of CNI-induced nephropathy. Mechanistically, an increase in reactive oxygen species (ROS) generation due to drug-induced changes in the intracellular redox homeostasis functions as an important trigger of the profibrotic signaling cascades activated under therapy with CNI. Although, inhibitors of the mechanistic target of rapamycin (mTOR) kinase have firmly been established as alternative compounds with a lower nephrotoxic potential, an activation of fibrogenic signaling cascades has been reported for these drugs as well. This review will comprehensively summarize recent advances in the understanding of profibrotic signaling events modulated by these widely used compounds with a specific focus put on mechanisms occurring independent of their respective immunosuppressive action. Herein, the impact of redox modulation, the activation of canonical TGFβ and non-Smad pathways and modulation of autophagy by both classes of immunosuppressive drugs will be highlighted and discussed in a broader perspective. The comprehensive knowledge of profibrotic signaling events specifically accompanying the immunomodulatory activity of these widely used drugs is needed for a reliable benefit-risk assessment under therapeutic regimens.

Reducing Adverse Effects of Immunosuppressive Agents in Kidney Transplant Recipients

Success in solid organ transplantation with minimal complications can now be achieved for most patients, and a remarkable rate of graft and patient survival can also be expected. However, the potential for adverse events and comorbid conditions increases with longer graft survival. Although the immunosuppressive regimen is central to the outcome of the transplant recipient and directly impacts the survival of the graft, chronic use of immunosuppressive agents is associated with metabolic disturbances such as hypertension, hyperlipidemia, loss of bone density, nephrotoxicity, and diabetes, which may contribute to other comorbid conditions. In addition, changes in appearance, gingival hyperplasia, hirsutism, alopecia, and weight gain disrupt quality of life and may lead to noncompliance with the immunosuppressive regimen. New immunosuppressive medications, including mycophenolate mofetil, sirolimus, basiliximab, and daclizumab, have allowed for experimentation with new regimens designed to reduce or allow discontinuation of corticosteroids and calcineurin inhibitors. This review highlights the impact and cost of immunosuppressive side effects and the potential for new immunosuppressive regimens to reduce this substantial clinical burden in transplantation.

Increased gene expression of TGF-β in peripheral blood mononuclear cells from renal transplant patients with polyomavirus BK viremia

We aimed to investigate the roles of cytokines during polyomavirus BK (BKV) reactivation in renal transplant patients. Forty-eight renal allograft recipients were enrolled, and their sera BKV viral load and mRNA expression levels of cytokines in peripheral blood mononuclear cells were measured by real-time polymerase chain reaction. Patient's age and gene expression levels of interleukin (IL)-2 (10.04 ± 2.63 vs. 8.70 ± 2.40, p = 0.049) and transforming growth factor (TGF)-β (12.58 ± 2.59 vs. 10.89 ± 1.91, p = 0.015) were significantly higher in BKV viremia (+) renal transplant patients. Multivariate logistic regression analysis revealed that age and mRNA expression levels of TGF-β, but not IL-2, significantly correlated with the presence of BKV viremia. Sera BKV viral loads showed a positive correlation with patient age and the levels of TGF-β and IL-6 mRNA. After adjusting for age and sex in the regression model, both age and TGF-β mRNA levels maintained a significant positive association with sera BKV viral loads. Serum TGF-β concentration tended to be higher in BKV viremia (+) patients (p = 0.079). In conclusion, expression levels of TGF-β were found to correlate with both BKV viremia positivity and sera BKV viral loads in renal transplant patients.

Renal allograft fibrosis: biology and therapeutic targets

Renal tubulointerstitial fibrosis is the final common pathway of progressive renal diseases. In allografts, it is assessed with tubular atrophy as interstitial fibrosis/tubular atrophy (IF/TA). IF/TA occurs in about 40% of kidney allografts at 3-6 months after transplantation, increasing to 65% at 2 years. The origin of renal fibrosis in the allograft is complex and includes donor-related factors, in particular in case of expanded criteria donors, ischemia-reperfusion injury, immune-mediated damage, recurrence of underlying diseases, hypertensive damage, nephrotoxicity of immunosuppressants, recurrent graft infections, postrenal obstruction, etc. Based largely on studies in the non-transplant setting, there is a large body of literature on the role of different cell types, be it intrinsic to the kidney or bone marrow derived, in mediating renal fibrosis, and the number of mediator systems contributing to fibrotic changes is growing steadily. Here we review the most important cellular processes and mediators involved in the progress of renal fibrosis, with a focus on the allograft situation, and discuss some of the challenges in translating experimental insights into clinical trials, in particular fibrosis biomarkers or imaging modalities.

Recent advances in renal interstitial fibrosis and tubular atrophy after kidney transplantation

Although kidney transplantation has been an important means for the treatment of patients with end stage of renal disease, the long-term survival rate of the renal allograft remains a challenge. The cause of late renal allograft loss, once known as chronic allograft nephropathy, has been renamed “interstitial fibrosis and tubular atrophy” (IF/TA) to reflect the histologic pattern seen on biopsy. The mechanisms leading to IF/TA in the transplanted kidney include inflammation, activation of renal fibroblasts, and deposition of extracellular matrix proteins. Identifying the mediators and factors that trigger IF/TA may be useful in early diagnosis and development of novel therapeutic strategies for improving long-term renal allograft survival and patient outcomes. In this review, we highlight the recent advances in our understanding of IF/TA from three aspects: pathogenesis, diagnosis, and treatment.

Biological pathways and potential targets for prevention and therapy of chronic allograft nephropathy

Renal transplantation (RT) is the best option for patients with end-stage renal disease, but the half-life is limited to a decade due to progressive deterioration of renal function and transplant failure from chronic allograft nephropathy (CAN), which is the leading cause of transplant loss. Extensive research has been done to understand the pathogenesis, the biological pathways of fibrogenesis, and potential therapeutic targets for the prevention and treatment of CAN. Despite the advancements in the immunosuppressive agents and patient care, CAN continues to remain an unresolved problem in renal transplantation. The aim of this paper is to undertake a comprehensive review of the literature on the pathogenesis, biological pathways of RT fibrogenesis, and potential therapeutic targets for the prevention and therapy of CAN.

The experimental treatment of corneal graft rejection with the interleukin-1 receptor antagonist (IL-1ra) gene

PURPOSE

To investigate the protective effects of interleukin-1 receptor antagonist (IL-1ra) gene transfer in a rat model of corneal graft rejection.

METHODS

We constructed a recombinant plasmid (pcDNA3.1-hIL-1ra) with high IL-1ra expression in eukaryotic cells. Using a Wistar-SD rat model of corneal graft rejection, we examined the effects of IL-1ra in vivo after cationic polymer jetPEI-mediated nonviral gene delivery. Four groups were included: negative controls (group I, n = 20), pcDNA3.1-hIL-1ra corneal stromal injection (group II, n = 34), pcDNA3.1-hIL-1ra anterior chamber injection (group III, n = 34), and 500 µg/ml IL-1ra protein subconjunctiva injection (group IV, n = 20). IL-1ra expression after transfection was evaluated by real-time polymerase chain reaction (RT-PCR) and western blotting. The rejection indices of corneal grafts were analysed in the different groups. The expression levels of transforming growth factor β1 (TGF-β1), inflammatory chemokines including RANTES, interleukin-1 (IL-1) and the numbers of CD4+ and CD8+ T cells in the grafts were determined by biochemical assays at different time points after corneal transplantation.

RESULTS

Various degrees of inflammatory cell infiltration and graft neovascularisation were observed by histopathology. After injecting the pcDNA3.1-hIL-1ra plasmid into the cornea, IL-1ra mRNA and protein expression was detected in the corneal stroma and reached a peak on day 3. The graft survival curves indicated that the corneal transparency rates of grafts in the IL-1ra gene-treated group and the IL-1ra protein-treated group were higher compared with the untreated group (P<0.05). During the period of acute rejection, TGF-β1, RANTES, IL-1α and IL-1β levels in the grafts in the IL-1ra treatment groups were lower than the control group (P<0.05). CD4+ and CD8+ T cell counts were reduced significantly in the corneal grafts of groups II, III and IV compared with group I (P<0.05).

CONCLUSION

Interleukin-1 receptor antagonist (IL-1ra) gene transfer treatment inhibits graft rejection after corneal transplantation through the downregulation of immune mediators.

TGF-β1 Expression in Kidney Allograft Protocol Biopsies during Cyclosporine: a Therapy

Background

TGF-β1 expression has been described to increase along with time from transplantation and has also been linked to allograft dysfunction and toxic effects of cyclosporine. Our aim was to correlate intragraft TGF-β1 expression with cyclosporine exposure after kidney transplantation.

Methods

Altogether 53 kidney allograft protocol biopsies from 42 patients on a low-dose cyclosporine-based regimen obtained at 3, 6, and 12 months were classified according to Banff and the chronic allograft damage index (CADI). TGF-β1 expression in tubules, glomeruli, vessels, and inflammatory cells was semi-quantitatively scored and correlated with cyclosporine concentrations (C0 and C2), CADI, and graft function.

Results

TGF-β1 expression was mildly increased along time from transplantation, but the results were not statistically significant. TGF-β1 expression was neither related to CADI nor to the use of ACE inhibitors/ARB. TGF-β1 expression in the kidney was not correlated with C0 or C2 levels or kidney graft function during follow-up.

Conclusion

In protocol biopsies from patients on low-dose cyclosporine regimen, expression of TGB-β1 was not significantly increased along time since transplantation, and did not correlate with cyclosporine exposure. Our findings suggest that the toxic effects of low-dose cyclosporine on TGF-β expression may be milder than previously thought.

Nox2 is a mediator of chronic CsA nephrotoxicity

We hypothesized that Nox2, the classical phagocytic NADPH oxidase, plays an important role in calcineurin inhibitor (CNI)-induced renal fibrosis. We tested this hypothesis in vitro, in animal and in human studies. Cyclosporine A (CsA) and tacrolimus (TAC) were associated with greater levels of Nox2 mRNA and epithelial to mesenchymal transition (EMT) in NRK52E cells. CsA increased Nox2, α-SMA and phosphorylated-p38MAPK, Smad3 and NFκB proteins. Nox2 upregulation and EMT were inhibited in TGF-β1 knockout cells suggesting that TGF-β1 is required for Nox2 activation. Fisher344 rats treated with high dose CsA showed increased Nox2 in the tubulointerstitium and greater Nox2, α-SMA, phosphorylated Smad3 and nitrotyrosine by immunoblot analyses. Inhibition of Nox2 by coadministration of apocynin or diphenyleneiodonium was associated with reduced fibrogenesis. We validated these findings by treating wild type and Nox2 null (B6.129S-Cybb(Tm1Din)/J) mice with high dose CsA. Western blot analyses confirmed the absence of Nox2 and significantly lower levels of α-SMA and 4-hydroxynonenal (HNE) in CsA-treated knockout mice. These findings were clinically relevant since Nox2 and α-SMA were increased in the tubulointerstitium of kidneys from 15 liver transplant recipients with biopsy-confirmed chronic CsA or TAC nephrotoxicity. In conclusion, specific Nox2 inhibition strategies may improve chronic CNI nephrotoxicity in solid organ transplantation.

TGF-β1 mediates sirolimus and cyclosporine A-induced alteration of barrier function in renal epithelial cells via a noncanonical ERK1/2 signaling pathway

The immunosuppressant drugs cyclosporine A (CsA) and sirolimus (SRL) used in combination demonstrated beneficial effects in organ transplantation, but this combination can also result in increased adverse effects. We previously showed that not only CsA treatment but also its combination with SRL decreased paracellular permeability in renal proximal tubular cells by modification of the tight junction proteins, claudins, through ERK1/2 signaling pathway. In this present study, evidence is presented that not only CsA but also the combination of CsA/SRL may have adverse effects on the barrier function of renal proximal cells, at least in part, through the expression of the cytokine transforming growth factor (TGF)-β1. CsA treatment upregulated TGF-β1 gene expression and this upregulation was enhanced when CsA and SRL were applied together. Addition of TGF-β1 (5 ng/ml) altered the barrier function with increased transepithelial electrical resistance (TER) and claudin-1 expression. Use of a TGF-β1-blocking antibody or blockage of TGF-β1 receptor kinase activity with SD208 prevented the CsA- and CsA/SRL-induced increase in TER. No evidence was found in the present studies to indicate that CsA or CsA/SRL treatment activated the TGF-β1 Smad canonical signaling pathway, whereas addition of TGF-β1 (5 ng/ml) did activate the Smad pathway. Addition of the ERK1/2 signaling inhibitor U0126 was able to prevent the TGF-β1-mediated increase in TER and claudin expression. It is most likely that the CsA- and CsA/SRL-induced increases in TGF-β1 expression may not be sufficient to trigger the Smad pathway but however may trigger other TGF-β1 receptor-mediated signaling including the ERK1/2 signaling pathway.

Cyclosporin A and tacrolimus induce renal Erk1/2 pathway via ROS-induced and metalloproteinase-dependent EGF-receptor signaling

We previously demonstrated that the widely used immunosuppressive drugs cyclosporin A (CsA) and tacrolimus (FK506), independent of immunophilin binding, can activate profibrogenic transforming growth factor β (TGFβ)/Smad signaling cascades in rat renal mesangial cells (MC). Here we report that both peptidyl-prolyl cis/trans isomerase (PPIase) inhibitors activate the extracellular-signaling regulated kinase (ERK) a member of the mitogen activated protein kinase (MAPK) and induce a rapid and transient increase in ERK phosphorylation. The MEK inhibitor U0126, the reactive oxygen species (ROS) scavenger N-acetyl-cysteine (NAC), a cell-permeant superoxide dismutase (SOD) and stigmatellin, an inhibitor of mitochondrial cytochrome bc1 complex strongly attenuated the increase in ERK1/2 phosphorylation triggered by PPIase inhibitors. Moreover, neutralizing antibodies against heparin binding-epidermal growth factor (HB-EGF), and inhibition of the EGF receptor by either small interfering (si)RNA or AG1478, demonstrate that ERK activation by both PPIase inhibitors is mediated via HB-EGF-induced EGF receptor (EGFR) tyrosine kinase activation. The strong inhibitory effects achieved by GM6001 and TAPI-2 furthermore implicate the involvement of a desintegrin and metalloproteinase 17 (ADAM17). Concomitantly, the PPIase inhibitor-induced ADAM17 secretase activity was significantly reduced by SOD and stigmatellin thus suggesting that mitochondrial ROS play a primary role in PPIase inhibitor-induced and ADAM17-mediated HB-EGF shedding. Functionally, both immunosuppressants caused a strong increase in MC proliferation which was similarly impeded when cells were treated in the presence of NAC, TAPI-2 or AG1478, respectively. Our data suggest that CsA and FK506, via ROS-dependent and ADAM17-catalyzed HB-EGF shedding induce the mitogenic ERK1/2 signaling cascade in renal MC.

The relationship between interferon-γ gene polymorphism and acute kidney allograft rejection

Cytokine gene polymorphisms have been associated with modified gene expression and cytokine production. Gamma interferon (IFN-γ) plays an important role in the pathogenesis of kidney transplant rejection. This study evaluated the association between IFN-γ gene polymorphisms and the history of acute allograft rejection in 53 adult first-transplant recipients receiving cadaveric kidney grafts. They were followed up in a single centre until 2006, for a median time of 4 years after transplantation (1-22 years). IFN-γ gene polymorphisms +874 T/A (rs2430561) were determined by polymerase chain reaction (PCR). T/T high IFN-γ genotype was found in 12, intermediate T/A in 29 and low A/A in 12 patients. Twenty-six acute kidney rejection episodes were evidenced in 20 patients, of which none occurred in the 12 patients with low IFN-γ genotype A/A. Age, gender, number of HLA (human leukocyte antigen) mismatches, ABO blood groups, HLA, time after transplantation, creatinine clearance and immunosuppressive regimens were excluded as confounding factors associated with IFN-γ genotype distribution between rejectors and non-rejectors. IFN-γ gene polymorphisms could be an important risk factor for acute kidney transplant rejection, whereas the low A/A IFN-γ genotype could be protective against rejection.

Nonimmune complications after transplantation

As posttransplant longevity has increased, nonimmune complications related to the transplant and posttransplant course have emerged as important factors in defining long-term outcomes. The incidence of, and risk factors for these complications may vary by transplanted organ based on immunosuppressive protocols and preexisting risk factors. This article discusses the relevant nonimmune complications associated with posttransplant care, with a focus on risk factors and management strategies.

Fibrogenesis in kidney transplantation: potential targets for prevention and therapy

Kidney allograft fibrosis results from a reactive process mediated by humoral and cellular events and the activation of transforming growth factor beta1. It is a process that involves both parenchymal and graft infiltrating cells and can lead to organ failure if injury persists or if the response to injury is excessive. In this review, we will address the role of preventive and therapeutic strategies that target kidney allograft fibrogenesis. We conclude that in addition to preventive strategies, therapies based on bone morphogenetic protein 7, hepatocyte growth factor, connective tissue growth factor, and pirfenidone have shown promising results in preclinical studies. Clinical trials are needed to examine the effect of these therapies on long-term outcomes.

Transforming growth factor-beta-mediated regulation of BK virus gene expression

The increasing prevalence of BK virus (BKV)-associated diseases in immunosuppressed patients has prompted an investigation of the immune response to BKV, especially the role of cytokines in regulating viral replication. We examined the effect of TGF-beta, a cytokine that is stimulated by certain immunosuppressive therapies, on BKV gene expression during lytic infection of renal proximal tubule epithelial cells. Viral gene expression, and specifically the activity of the BKV early promoter, is regulated by TGF-beta in a strain-dependent manner. Promoter activity is upregulated in the presence of TGF-beta for the TU strain of BKV, and not for the Dik, Dunlop, or Proto-2 strains. Using site-directed mutagenesis, we have identified a small segment of the TU promoter that is required for stimulation in response to TGF-beta. These results demonstrate that BKV strains can respond differently to cytokine treatment and suggest that TGF-beta may play a role in the reactivation of BKV.

A search for cyclophilin-A gene variants in cyclosporine A-treated renal transplanted patients

BACKGROUND

The cyclophilin A (CypA)-cyclosporine (CsA) complex promotes immune response. The variation at the CypA gene could explain CsA-pharmacokinetics and clinical outcomes among CsA-treated patients.

METHODS

The study included 290 kidney transplanted patients (65% male; mean age 51 +/- 15 yr), treated with CsA. The five CypA- exons and the promoter region were analysed through single-strand conformation analysis, denaturing high performance liquid chromatography, and direct sequencing. The effect of a promoter polymorphism (-11 G/C) on gene expression was analysed in cell-cultures.

RESULTS

We found two polymorphisms in the promoter (-11 G/C) and exon 1 (+36 G/A). Genotype frequencies did not differ between patients according to their pharmacokinetics status. In vitro studies showed that -11 G/C affected gene expression. The -11 G allele was significantly associated with clinical nephrotoxicity (p = 0.006). The strongest predictors for nephrotoxicity were a donor age > or =55 yr, and the promoter GG + GC genotypes.

CONCLUSIONS

Our work suggests that a CypA-promoter polymorphism (-11 G/C) could be associated with clinical nephrotoxicity. Replication of this study in other populations is necessary to define the role of CypA-variants in the main clinical outcomes among CsA-treated kidney-transplanted patients.

Transforming growth factor-beta1 gene expression and cyclosporine A-induced gingival overgrowth: a pilot study

AIMS

The relationship between gingival overgrowth (GO) induced by cyclosporine A (CsA) and transforming growth factor-beta1 (TGF-beta1) remains unclear. The aims of the present study were to evaluate TGF-beta1 gene expression under different immunosuppressive treatments and its association with TGF-beta1 gene functional polymorphism and GO in renal transplant recipients.

MATERIAL AND METHODS

The study included 98 CsA-treated renal transplant recipients (with and without GO) and 44 tacrolimus-treated transplant patients (without GO). TGF-beta1 mRNA expression was measured using a real-time quantitative polymerase chain reaction assay. The levels were correlated with TGF-beta1 gene polymorphisms at codons 10 and 25, with different immunosuppressive treatment and GO.

RESULTS

The level of TGF-beta1 gene expression was insignificantly lower in the CsA-treated group compared with the tacrolimus group, and significantly lower in the group with GO compared with patients without GO. In tacrolimus- and CsA-treated patients, but not in patients with GO, the level of TGF-beta1 gene expression was associated with functional phenotypes of TGF-beta1. The incidence, degree and extent of GO were higher in recipients with lower TGF-beta1 gene expression.

CONCLUSIONS

Lower level TGF-beta1 gene expression, not functional polymorphism, in patients treated with CsA may be considered to be a risk factor for GO.

The challenge of renal function in heart transplant children

Renal dysfunction may occur after pediatric heart transplantation and impacts on long-term prognosis. This study aims to review the incidence and mechanisms of chronic nephropathy following heart transplantation, and suggest therapeutic directions. The proportion of pediatric heart-transplant recipients with impaired renal function varies from 22 to 57%, and end-stage renal failure from 3 to 10%, depending on the method used for estimating the glomerular filtration rate. The pathophysiology of renal dysfunction is in part due to calcineurin inhibitor-induced renal vasoconstriction, through activation of the intrarenal renin-angiotensin system, TGF-beta1 upregulation and TGF-beta1 gene polymorphisms. Overproduction of angiotensin II, associated with angiotensin-converting-enzyme genotype, might be associated with poor prognosis and pharmacological factor gene polymorphisms, and may contribute to variation of calcineurine inhibitor exposure in the kidney. Strategies to prevent renal dysfunction include reducing calcineurine inhibitor exposure or delaying calcineurine inhibitor administration from the early post-transplant period. Calcium channel blockers and angiotensin-converting-enzyme inhibitors, blockade of angiotensin II, or anti-TGF-beta1 antibodies might limit nephrotoxicity. No accurate marker can predict the potential of renal lesions to develop. Lowering calcineurine inhibitors levels with immunosuppressive agents that are either less nephrotoxic or non-nephrotoxic should be formally studied. Of high interest is the impact of genetic polymorphism on the development of renal dysfunction.

Urinary Transforming Growth Factor-β–Induced Gene-h3 (βig-h3) as a Sensitive Predictor in Chronic Cyclosporine Nephrotoxicity

Transforming growth factor (TGF)-beta is involved in the pathogenesis of chronic cyclosporine nephrotoxicity (CyAN). Since the expression of TGF-beta induced gene h3 (betaig-h3) is up-regulated by TGF-beta, we evaluated the potential role of betaig-h3 as a sensitive urinary marker to monitor the progression/regression of chronic CyAN. Urinary betaig-h3 levels were determined using an enzyme-linked immunosorbent assay in nine patients with chronic CyAN and 13 patients with stable graft function. We scored the extent of tubulointerstitial fibrosis (TIF) and using immunoperoxidase labeling, determined betaig-h3 expression in renal tissues of patients with chronic CyAN. Urinary betaig-h3 excretion was higher in chronic CyAN compared to control subjects (173.4+/-26.0 vs 62.6+/-5.0 ng/mg creatinine, P<.01). In chronic CyAN, the degree of TIF correlated with increased urinary betaig-h3 levels (r=.785, P<.05). In kidneys with chronic CyAN, betaig-h3 labeling was more prominent at the basement membranes (BM) of the tubules where inflammatory cells had infiltrated the surrounding interstitium. Moreover, the BM of the atrophied tubules and their surrounding interstitium were strongly labeled. Urinary betaig-h3 levels decreased from 173.4+/-26.0 to 64.9+/-14.4 ng/mg creatinine at 1 month after discontinuation of CyA or reduction in CyA dosage (P<.01) despite unchanged serum creatinine levels. Urinary betaig-h3 levels increased in patients with chronic CyAN and decreased after discontinuation or reduction of CyA dosage. Our results suggested that urinary betaig-h3 levels could be used as a sensitive urinary marker to monitor the progression or regression of chronic CyAN.

A randomized long-term trial of tacrolimus/sirolimus versus tacrolimums/mycophenolate versus cyclosporine/sirolimus in renal transplantation: three-year analysis

BACKGROUND

We report three-year (interim) effects of combining sirolimus (Siro) vs. mycophenolate mofetil (MMF) as adjunctive therapy with calcineurin inhibitors (CI) in renal transplantation in the three different CI-based regimens.

METHODS

Between May 2000 and December 2001, 150 recipients of deceased donor (DD) and living donor (LD) kidney transplants were randomized into three groups (n=50/group): Group A (Tacro/Siro), Group B (Tacro/MMF) and Group C (CsA/Siro). This report details drug dosing and monitoring, protocol discontinuance, biopsy-proven rejection, graft failure, other adverse events, and death at 36 months postoperatively.

RESULTS

Actual patient and graft survival respectively in Group A was 90% and 82%, in Group B was 92% and 88%, and in Group C was 96% and 88% (not significant). Biopsy-confirmed acute rejection incidents showed a trend in favor of Group B (10%) vs. Group A (26%) and Group C (20%) combined (P=0.07). The geometric mean */SE serum creatinine concentration and arithmetic mean +/- SE Cockroft-Gault creatinine clearance calculations, respectively, were 1.39*/1.1 and 72.8+/-4.3 for Group A, 1.36*/1.1 and 72.1+/-4.1 for Group B, and 1.60*/1.1 and 61.8+/-3.8 for Group C, a statistically favorable difference for Group B over Group C (P=0.04). There was also less de novo development of posttransplant diabetes mellitus and lipid disorders in Group B vs. A and C (P<0.04).

CONCLUSIONS

This three-year (interim) analysis has indicated a trend towards better graft function, fewer endocrine disorders, and fewer acute rejection episodes comparing adjunctive MMF and Tacro vs. Siro and Tacro or Siro and CsA, in the dosages used.

Profibrotic cytokines and lymphocyte proliferation in stable renal allograft recipients treated with or without cyclosporine A

Profibrotic cytokines such as transforming growth factor-beta 1 (TGF-beta1) and endothelin-1 (ET-1) are involved in the pathogenesis of chronic allograft nephropathy. We assessed the effect of maintenance immunosuppression with or without cyclosporine A on TGF-beta1 and ET-1 expression as well as lymphocyte proliferation in renal allograft recipients. Patients were divided into groups according to their maintenance immunosuppression: A, azathioprine + methylprednisolone; B, cyclosporine A + azathioprine + methylprednisolone. TGF-beta1 and ET-1 plasma concentrations were not different between both groups. TGF-beta1 concentrations in cell culture supernatants and lymphocyte proliferation were higher in group B as compared to group A. No correlation was found between TGF-beta1 plasma concentrations and lymphocyte proliferation. Multiple linear regression analysis revealed that patient characteristics influence TGF-beta1 and ET-1 expression. In conclusion, plasma levels of profibrotic cytokines do not reflect the existing profibrotic potential of immunosuppressive drugs. Demographic factors and the employed co-medication confound the results.

Increased urinary excretion of transforming growth factor-beta(1) in renal transplant recipients during cytomegalovirus infection

AIMS

Cytomegalovirus (CMV) is a suggested risk factor for chronic allograft nephropathy, and transforming growth factor-beta (TGF-beta) is a key fibrogenic molecule in this process. CMV has been shown to induce the expression of TGF-beta and several cytokines. We analyzed the impact of CMV on urinary excretion of TGF-beta, ICAM-1, TNF-alpha and correlated findings with biopsy histology.

MATERIAL

Urine samples from 46 renal transplant recipients were available for the study. Urine samples were taken when CMV infection was suspected, or for controlling of proteinuria or bacteriuria.

METHOD

CMV was diagnosed by antigenemia and viral cultures. Patients with previous CMV infection were excluded from the analysis. Urine samples were analyzed by ELISA-method to detect the levels of TNF-alpha, ICAM-1 and TGF-beta(1). Banff '97 criteria were used for scoring of protocol biopsies taken 6 months after transplantation.

RESULTS

At the time of the urine collection, 13/46 patients had CMV infection. Eight patients with no CMV infection were used as controls. TGF-beta(1) was significantly increased in the CMV group (samples taken mean 137+/-79 days post-transplantation) compared to controls (samples 139+/-64 days post-transplantation) (51.1+/-28.0 vs. 13.3+/-6.7 ng/mmol crea, p<0.001). No differences in the levels of other molecules were recorded. In the biopsies, interstitial fibrosis was significantly increased in the CMV group compared to controls.

CONCLUSIONS

Urinary excretion of TGF-beta(1) was increased in patients during CMV infection. This was associated with increased fibrosis in the biopsies.

Calcineurin inhibitor effects on growth and phenotype of human airway epithelial cells in vitro

Calcineurin inhibitors (CIs) cyclosporin and tacrolimus form the basis for immunosuppression in lung transplantation, yet also exert biological effects on nonlymphoid tissue. With the advent of inhaled cyclosporin, we hypothesize that the airway epithelium is also subject to CI effects at high doses. The aim of this study was to identify human tracheobronchial epithelial cell (hTBEC) calcineurin gene expression and quantify effects of CIs on hTBEC growth, interleukin-1-beta stimulated IL-8 production and hTBEC phenotype. Cyclophillin B and FK-associated binding protein, calcineurin A (alpha and beta), and NFATC3 and NFAT5 were detected in hTBEC cultures by RT-PCR. Acute and chronic cyclosporine treatment 1000 ng/mL significantly inhibited hTBEC proliferation, while tacrolimus did not (range of 10 ng/mL to 1000 ng/mL for acute treatment, 50 ng/mL for chronic treatment). Cyclosporin at 10,000 ng/mL significantly increased LDH release by well-differentiated hTBEC cultures (n = 6) and trended towards significance at 1000 ng/mL. IL1-beta stimulated IL-8 production was significantly increased in rapidly growing hTBEC cultures (n = 8) treated with cyclosporin (p = 0.049). Prolonged treatment of well-differentiated hTBECs at air-liquid-interface (ALI) with cyclosporin 1000 ng/mL significantly reduced intact multilayered mucociliary epithelium (p = 0.009). Inhibition of hTBEC growth, stimulation of IL-8 production and long-term effects on mucociliary phenotype and intact multi-layered epithelium suggest that cyclosporin may have a direct toxic effect on airway epithelium after transplantation.

Reciprocal role of cyclins and cyclin kinase inhibitor p21WAF1/CIP1 on lymphocyte proliferation, allo-immune activation and inflammation

Background

Immune activation that results due to the aberrant proliferation of lymphocytes leads to inflammation and graft rejection in organ transplant recipients. We hypothesize that the cell cycle control and inflammation are parallel events, inhibition of cellular proliferation by cyclin kinase inhibitor specifically p21 will limit inflammation and prevent allograft rejection.

Methods

We performed in vitro and in vivo studies using lymphocytes, and rat heart transplant model to understand the role of cyclins and p21 on mitogen and allo-induced lymphocyte activation and inflammation. Lymphocyte proliferation was studied by ³H-thymidine uptake assay and mRNA expression was studied RT-PCR.

Results

Activation of allo- and mitogen stimulated lymphocytes resulted in increased expression of cyclins, IL-2 and pro-inflammatory cytokines, which was inhibited by cyclosporine. The over-expression of p21 prolonged graft survival in a completely mismatched rat heart transplant model resulted by inhibiting circulating and intra-graft expression of proinflammatory cytokines.

Conclusion

Cyclins play a significant role in transplant-induced immune activation and p21 over-expression has potential to inhibit T cell activation and inflammation. The results from this study will permit the design of alternate strategies by controlling cell cycle progression to achieve immunosuppression in transplantation.

Protective Effect of Oral L-arginine Supplementation on Cyclosporine Induced Nephropathy in Rats

BACKGROUND

One of the major adverse effects of long term cyclosporine A (CyA) administration is chronic nephrotoxicity. Several studies have suggested that alterations of the L-arginine (L-Arg) nitric oxide (NO) pathway may be involved in the pathogenesis of CyA-induced kidney damage.

AIM

We postulated that in vivo activation of L-Arg-NO pathway might have a beneficial effect on CyA-induced renal damage. Conditions of chronic NO enhancement was established with L-Arg supplementation and chronic NO blockade with N-nitro-L-Arg methyl ester (L-NAME). We tested the hypothesis that, if CyA administration alters intrarenal NO synthesis, then exogenous L-Arg supplementation could limit renal injury, on the contrary, L-NAME, a potent competitive inhibitor of NO synthesis, could enhance CyA nephrotoxicity. Harmful effect of NO blockade indirectly supports the beneficial effect of NO in a model of CyA nephrotoxicity.

METHODS

Rats were administered vehicle (VH), CyA (7.5 mg/kg/day), CyA + L-Arg (2g/kg/day), CyA + L-NAME (5 mg/100 ml/day), CyA + L-Arg + L-NAME, VH + L-Arg, VH + L-NAME and were sacrificed at the end of the experiment. Body weight, serum creatinine, blood urea nitrogen (BUN) and NO levels were determined. Tubular injury and interstitial fibrosis were evaluated semiquantitatively using scoring systems on paraffin sections stained with hematoxylin/eosin (H/E), Masson's trichromic and periodic acid-Schiff (PAS).

RESULTS

The CyA group developed marked renal injury, characterized by a significant increase in serum creatinine and BUN, and histopathological alterations including tubular dilatation, vacuolization, necrosis, interstitial cell infiltration and tubulointerstitial fibrosis. CyA reduced serum NO level. L-Arg treatment significantly enhanced NO biosynthesis and protected animals from CyA-induced kidney damage. In contrast L-NAME strikingly reduced serum NO level, and worsened biochemical and histopathological alterations.

CONCLUSION

Chronic CyA nephrotoxicity can be aggravated by NO blockade and ameliorated by NO enhancement suggesting that L-Arg supplementation may be protective in CyA nephrotoxicity.

Tacrolimus and Cyclosporinein vitro and in vivo Induce Osteopontin mRNA and Protein Expression in Renal Tissues

The mechanism of immunosuppression-linked nephrotoxicity in organ transplantation remains to be solved. Expression of osteopontin (OPN), a multifunctional secreted glycoprotein, has been associated with various forms of renal injuries. In this study, using in vitro and in vivo models, we examined the effects of cyclosporine (CsA) and tacrolimus (TAC) on OPN mRNA and protein expression. We also examined if CsA- and TAC-induced OPN expression is dependent on transforming growth factor (TGF)-beta expression. For in vivo experiments mice and rats were injected with CsA (25 mg/kg) and TAC (0.2 mg/kg). For in vitro experiments, human proximal tubular epithelial (PTE) cells were treated with CsA and TAC for 4 h. To study the in vivo effect of TGF-beta on OPN mRNA, mice were injected with recombinant TGF-beta protein (3 mg/kg). The expression of OPN was also studied in CsA-treated PTE cells with and without anti-TGF-beta antibody. At the end of in vitro and in vivo treatments, RNA was isolated from kidney tissue and renal cells reverse transcribed to cDNA and amplified for OPN mRNA. Using immunochemistry and Western blot analysis OPN protein expression was also studied in vivo and in vitro, respectively. Both in vitro and in vivo treatment with CsA and TAC resulted in significantly increased OPN mRNA and protein expression. TGF-beta treatment in vivo also resulted in a significantly increased OPN mRNA expression and anti-TGF-beta antibody but not the control antibody in vivo in CsA-treated mice, and in vitro in CsA-treated PTE cells inhibited OPN mRNA expression. OPN may contribute to the CsA- and TAC-induced nephrotoxicity in organ transplant recipients and the increased OPN expression might be mediated by TGF-beta.

Impact of TGFβ1 gene polymorphisms on late renal function in pediatric heart transplantation

Late renal dysfunction may affect long-term outcome of nonrenal transplant recipients. We hypothesized that transforming growth factor beta1 (TGFbeta1) might play a role in the fibrogenic mechanisms leading to renal dysfunction. The aim was to determine whether TGFbeta1 gene polymorphisms are associated with renal outcome in pediatric heart recipients. Eighty-eight patients underwent a first heart transplantation at the age of 7.1 +/- 6.5 years, received tacrolimus-based immunosuppression, and were followed for > or =1 year (6.7 +/- 3.2 years). Creatinine clearance (CrCl; ml/mn/1.73 m2) was calculated (Schwartz) before transplant, then at 1 month, 6 months, and 1 year, and yearly up to 7 years. Impaired function was defined as CrCl <80 ml/mn/1.73 m2. Mean CrCl decreased from 120 +/- 53 ml/mn/1.73 m2 before transplant to 98 +/- 40, 96 +/- 37, 102 +/- 30, and 101 +/- 38 ml/mn/1.73 m2 at, respectively, 6 months and 1, 5 (n = 58), and 7 years (n = 33). The TGFbeta1 high-producer genotype had worse CrCl than intermediate and low producers at every time point, despite similar pretransplant CrCl (pretransplant = 120 +/- 53 vs 118 +/- 55 ml/mn/1.73 m2 [p = 0.8], 1 year = 92 +/- 38 vs 113 +/- 30 ml/mn/1.73 m2 [p = 0.03]) and similar tacrolimus levels. The TGFbeta1 high-producer genotype was associated with CrCl < 80 ml/mn/1.73 m2. The TGFbeta1 high-producer genotype is associated with renal dysfunction in pediatric heart recipients.

Anti-transforming growth factor antibody at low but not high doses limits cyclosporine-mediated nephrotoxicity without altering rat cardiac allograft survival: potential of therapeutic applications

BACKGROUND

Long-term treatment of cardiac transplant recipients with cyclosporine results in a progressive decline in kidney function in a large number of patients. This complication is one of the most important prognostic parameters that determine the outcome of cardiac transplantation. Transforming growth factor-beta (TGF-beta) is one of the most potent mediators of the fibrogenic effects of cyclosporine.

METHODS AND RESULTS

With the use of an experimental rodent model, heterotopic heart transplantation was performed, creating histocompatibility-disparate allografts. Because TGF-beta in part mediates both the immunosuppressive and nephrotoxic effects of cyclosporine, recipients were treated with cyclosporine with and without anti-TGF-beta antibody to determine whether anti-TGF-beta antibody could reduce the nephrotoxic effects of cyclosporine. Intrarenal expression of TGF-beta, collagen, fibronectin, matrix metalloproteinase-2, and tissue inhibitor of metalloproteinase-2 was studied with the use of reverse transcription-polymerase chain reaction. Intrarenal expression of TGF-beta protein was studied by immunohistochemistry and with the use of ELISA to quantify circulating levels of TGF-beta protein in plasma. Cyclosporine-induced graft survival (immunosuppressive effect) was abrogated with a higher concentration (2.5 mg/kg) of anti-TGF-beta antibody, whereas a lower concentration (1 mg/kg) inhibited both cyclosporine-induced expression of fibrogenic molecules and renal toxicity.

CONCLUSIONS

These results provide credence to the pivotal role of TGF-beta in immunosuppression-associated renal toxicity in recipients of cardiac transplantation. Furthermore, these findings support a potentially significant therapeutic use of optimal concentration of anti-TGF-beta antibody to ameliorate cyclosporine-associated nephrotoxicity in cardiac transplant recipients.

Inhibition of nitrosylation, nitration, lymphocyte proliferation, and gene expression in acute and delayed cardiac allograft rejection by an orally active dithiocarbamate

Dithiocarbamate derivatives sequester metals such as iron and may have benefits in inflammatory diseases. We examined the actions of a new dithiocarbamate-based oral formulation, NOX-700, on protein modification by nitric oxide (NO), gene expression, and lymphocyte proliferation in a model of acute and delayed cardiac rejection. Chronic treatment with NOX-700 prolonged graft survival. In combination with low-dose cyclosporine (CsA), NOX-700 produced a synergistic action to prolong graft survival. NOX-700 decreased myocardial heme nitrosylation. A single bolus injection with NOX-700 in untreated recipients did not decrease heme nitrosylation but normalized NO metabolites and caused the formation of a mononitrosyl iron complex indicating NO scavenging in vivo. NOX-700 alone given with CsA inhibited protein nitration. NOX-700 or CsA each alone decreased intragraft inflammatory cell infiltration. NOX-700 also potentiated the CsA-induced inhibition of splenocyte proliferation ex vivo stimulated by concanavalin A. In splenocytes derived from treated rats but stimulated ex vivo in a mixed lymphocyte response (MLR), interferon-gamma and cyclin D3 gene expression was inhibited by NOX-700 suggesting down-regulation of lymphocyte activation and proliferation by in vivo treatment. These studies suggest that NOX-700 is protective in cardiac rejection, in part, by scavenging of NO and by limiting lymphocyte activation infiltration.

Late calcineurin inhibitor withdrawal as a strategy to prevent graft loss in patients with suboptimal kidney transplant function

Chronic allograft nephropathy is a major cause of progressive renal failure in renal transplant recipients. Its etiology is multifactorial and may include both immunologic and nonimmunologic causes. In this observational cohort study we set out to see if calcineurin inhibitor withdrawal would reduce the likelihood of graft loss.

METHODS

One hundred and five renal transplant recipients with impaired kidney function (mean serum creatinine 3.0 +/- 0.1 mg/dl) and biopsy-proven chronic allograft nephropathy had the dose of their calcineurin inhibitors, cyclosporine (CSA), or tacrolimus (FK), reduced or discontinued with either the addition of, or continuation of mycophenolate mofetil and low-dose corticosteroids. This intervention occurred at a mean of 29.0 +/- 2.7 months after transplantation. Follow-up after intervention was 54.3 +/- 4.1 months in the reduced CSA group (n = 64), 41.6 +/- 3.2 months in the reduced FK group (n = 28), and 75.5 +/- 6.7 months in the calcineurin inhibitor withdrawal group (n = 13).

RESULTS

There were 24 graft failures in the reduced CSA group, 9 graft failures in the reduced FK group, and 1 graft lost in the calcineurin inhibitor withdrawal group. The unadjusted relative risk for graft failure in the CSA and FK groups combined (confidence interval 1.05-31.6), was 4.07 using the calcineurin inhibitor withdrawal group as the reference, p = 0.05. A Cox proportional hazards model adjusting for baseline covariates including age, gender, race, type of transplant, delayed graft function, baseline blood pressure and random serum glucose and cholesterol demonstrated that only calcineurin inhibitor dose reduction but not withdrawal, older age, delayed graft function, higher serum creatinine at the time of intervention, and higher diastolic blood pressure and serum glucose, correlated with graft loss. Only 6 of the 105 patients developed Banff grade acute rejection. All responded to steroid therapy. We conclude that although this observational cohort study may have a selection bias, late calcineurin inhibitor withdrawal in patients with chronic allograft nephropathy and impaired kidney function appears safe and durable as a treatment strategy to reduce the likelihood of graft failure.

CYCLOSPORINE A MEDIATES FIBROPROLIFERATION THROUGH EPITHELIAL CELLS

BACKGROUND

Obliterative bronchiolitis (OB) is the major cause of morbidity and mortality after lung transplantation. The potential role of immunosuppressive drugs in the development of OB is uncertain, but there are limited data indicating that cyclosporine A (CsA) may have a direct fibrogenic effect on various human cell types. Epithelium-fibroblast interactions have been suggested to play a crucial role in the course of fibroproliferation, which is a major feature of OB.

METHODS

We studied the effect of CsA and FK506 on primary human lung fibroblast proliferation in a human epithelial-fibroblast interactive model.

RESULTS

Clinically relevant concentrations of CsA (0.1-1 microg/mL) and FK506 (0.001-0.01 microg/mL) did not affect fibroblast proliferation in monocultures. Conditioned medium (CM) from untreated epithelial cells (Calu-3) stimulated fibroblast proliferation. CM from FK506-treated (0.001-0.1 microg/mL) epithelial cells had no significant additive effect on fibroblast proliferation compared with CM of untreated epithelial cells. In contrast, CM obtained from epithelial cells treated with 0.1 microg/mL CsA significantly enhanced fibroblast proliferation compared with CM of untreated epithelial cells. This proliferative effect of 0.1 microg/mL CsA was mediated by epithelial-derived factors greater than 100 kDa.

CONCLUSIONS

These data demonstrate that a clinically relevant concentration of CsA stimulates fibroblast proliferation through mediators produced by airway epithelial cells, raising the possibility that CsA may contribute to the development of OB after lung transplantation.

Differential effects of rapamycin, cyclosporine A, and FK506 on human coronary artery smooth muscle cell proliferation and signalling

BACKGROUND

Immunosuppressive agents are at the forefront of preventing organ rejection after transplantation. However, their effects on vascular smooth muscle cell-mediated intimal hyperplasia that occurs in post-transplant coronary artery disease are less well known.

METHODS AND RESULTS

We investigated the in vitro effects of three immunosuppressive agents cyclosporine A (CsA), FK506 (tacrolimus), and rapamycin (sirolimus, Rapa) on cultured human coronary artery smooth muscle cells (cSMC). CsA inhibited both platelet-derived growth factor (PDGF)-stimulated DNA synthesis and serum-induced proliferation at high concentrations (> or =1000 ng/ml). The growth-inhibitory effect of CsA was not altered by anti-TGF-beta neutralising antibodies nor was autocrine TGF-beta release detected in CsA-treated culture medium. At inhibitory doses, CsA inhibited ERK kinase activation by PDGF, although cytotoxicity was also apparent. Most notably, CsA visibly prevented PDGF-induced altered cell morphology. Rapa was a highly potent and effective inhibitor of cSMC proliferation (reduction in DNA synthesis by >50% from 0.01 ng/ml), acting through inhibition of 70-kDa S6 kinase (p70S6k). FK506 (1-1000 ng/ml) did not affect cSMC proliferation alone, although a > or =250-fold excess of FK506 over Rapa completely reversed the inhibitory effect of Rapa, confirming that these two agents share a common intracellular receptor, the FK506-binding protein (FKBP).

CONCLUSION

Rapa is a powerful inhibitor of cSMC proliferation, while CsA slighly inhibits cSMC proliferation, although only at higher concentrations that may be toxic. These results indicate that therapeutic immunosuppression with Rapa may be additionally useful in prevention or delay of posttransplant coronary artery disease.

SUPPRESSION OF CYCLOSPORINE A NEPHROTOXICITY IN VIVO BY TRANSFORMING GROWTH FACTOR β RECEPTOR-IMMUNOGLOBULIN G CHIMERIC PROTEIN

BACKGROUND

Transforming growth factor (TGF)beta is implicated in the pathogenesis of cyclosporine A (CsA) nephrotoxicity. We examined the efficacy of TGF beta receptor (R)II/immunoglobulin (Ig)G Fc, a soluble chimeric protein consisting of the extracellular domain of human TGF beta RII and IgG1 Fc, on CsA nephrotoxicity in mice.

METHODS

Subcutaneous injection of CsA (25 mg/kg/d) was given daily to mice maintained on a low-sodium diet. On days 1 and 7, an expression vector carrying cDNA for either TGF beta RII/IgG Fc or beta-galactosidase was transfected into the skeletal muscles by electroporation. At 2 or 3 weeks of CsA administration, plasma and renal TGF beta 1 levels, and tubulointerstitial injury and fibrosis were evaluated.

RESULTS

After 2 weeks of CsA administration, plasma and renal TGF beta 1 levels increased to the maximum and then declined toward the baseline levels. Renal TGF beta 1 mRNA remained elevated until 3 weeks. Tubulointerstitial alterations became appreciable in 2 weeks and intensified by 3 weeks. At 2 weeks, the TGF beta RII/IgG Fc intervention abolished the increase in plasma TGF beta 1, attenuated the increase in renal TGF beta 1 by 50%, and markedly suppressed the histologic alterations. At 3 weeks, the histologic alterations remained markedly suppressed by the intervention, with no appreciable effects on the renal TGF beta 1 mRNA and protein.

CONCLUSION

The introduction of TGF beta RII/IgG Fc by gene transfer effectively abrogated CsA-induced tubulointerstitial alterations. Suppression of tubulointerstitial changes was evident at 3 weeks when renal TGF beta 1 mRNA and protein were comparable to those with CsA alone, indicating that early anti-TGF beta intervention is effective in suppressing the progression of CsA nephrotoxicity despite persistent increases in renal TGF beta 1 expression.

Impact of donor and recipient cytokine genotypes on renal allograft outcome

Allelic differences in gene promoter or codifying regions have been described to affect regulation of gene expression, consequently increasing or decreasing cytokine production and signal transduction responses to a given stimulus. This observation has been reported for interleukin (IL)-10 (-1082 A/G; -819/-592 CT/CA), transforming growth factor (TGF)-beta (codon 10 C/T, codon 25 G/C), tumor necrosis factor (TNF)-alpha (-308 G/A), TNF-beta (+252 A/G), interferon (IFN)-gamma (+874 T/A), IL-6 (-174 G/C), and IL-4R alpha (+1902 G/A). To evaluate the influence of these cytokine genotypes on the development of acute or chronic rejection, we correlated the genotypes of both kidney graft recipients and cadaver donors with the clinical outcome. Kidney recipients had 5 years follow-up, at least 2 HLA-DRB compatibilities, and a maximum of 25% anti-HLA pretransplantation sensitization. The clinical outcomes were grouped as follows: stable functioning graft (NR, n = 35); acute rejection episodes (AR, n = 31); and chronic rejection (CR, n = 31). The cytokine genotype polymorphisms were defined using PCR-SSP typing. A statistical analysis showed a significant prevalence of recipient IL-10 -819/-592 genotype among CR individuals; whereas among donors, the TGF-beta codon 10 CT genotype was significantly associated with the AR cohort and the IL-6 -174 CC genotype with CR. Other albeit not significant observations included a strong predisposition of recipient TGF-beta codon 10 CT genotype with CR, and TNF-beta 252 AA with AR. A low frequency of TNF-alpha -308 AA genotype also was observed among recipients and donors who showed poor allograft outcomes.

Withdrawal of cyclosporine or tacrolimus after addition of mycophenolate mofetil in patients with chronic allograft nephropathy

There has been a need for a prospective, randomized, controlled trial to determine whether the addition of mycophenolate mofetil (MMF) to a calcineurin inhibitor (CNI)-based regimen or MMF addition followed by CNI withdrawal is an effective treatment for chronic allograft nephropathy (CAN). We conducted the first randomized, prospective study to compare the introduction of MMF with or without CNI withdrawal in long-term transplant recipients with histologically proven CAN and deteriorating renal function. The primary endpoint was renal function as indicated by the slope of the inverse serum creatinine vs. time at 32 weeks after randomization. After an interim analysis found a greater-than-expected difference between groups in the slopes of the inverse serum-creatinine, the study was stopped for ethical reasons. There were 20 patients in the MMF/CNI continuation and 19 patients in the MMF/CNI withdrawal groups (mean time post-transplant 7 years). Renal function improved in the dual-therapy compared with the triple-therapy group (p=0.002). Blood pressure decreased in the dual-therapy group with a significant difference between groups at 35 weeks (p=0.04). No acute rejections occurred. Long-term patients with CAN experience a significant improvement in renal function and blood pressure when CNIs are replaced by MMF.

Immunosuppression and transplant vascular disease: benefits and adverse effects

Cardiac allograft vasculopathy (CAV) occurs within 5 years of transplantation surgery and represents the main cause of death in long-term heart transplant survivors. The detailed pathogenesis of CAV is unknown, but there are strong indications that immunologic mechanisms, which are regulated by nonimmunologic factors, are the major cause of this phenomenon. Cyclosporine A (CsA) is a frequently used immunosuppressive agent in transplant medicine to prevent rejection. The mechanism of action of CsA involves initial binding to cyclophilin to form a complex that then inhibits calcineurin (CN), leading to reduced interleukin (IL)-2 production as part of the signal transduction pathway for the activation of B-lymphocytes and T-lymphocytes. Based on this proposed mechanism, it was expected that CsA should be an effective strategy in attenuating the host immune response against transplanted allograft tissue; however, CsA has not changed the outcome of CAV. Several mechanisms have been suggested for the ineffectiveness of CsA in long-term prevention of CAV. For example, routine therapeutic doses of CsA may block CN incompletely (50%), whereas complete blockade requires doses that are not clinically tolerable. Another explanation is the possible activation of T-cell receptors directly (CN independent) by the immune response, which induces protein kinase C theta (PKCtheta) and leads to IL-2 production and immune rejection. Moreover, there may be a role for nonimmunologic mechanisms, such as complement, which cannot be controlled by CsA, or CsA may cause hypercholesterolemia or induce overexpression of transforming growth factor-beta (TGF-beta). This review also compares the effect of CsA with other immunosuppressants in allograft artery preservation and their clinical efficacy.

Survival of mitomycin C-treated pancreatic islet xenografts is mediated by increased expression of transforming growth factor-β1

BACKGROUND

Mitomycin C (MMC) can trigger various intracellular signals. The authors previously showed that pretreatment of highly immunogenic crude pancreatic islets with MMC improved their survival in a rat-to-mouse transplantation model. The aim of this study was to investigate the role of transforming growth factor (TGF)-beta in mediating MMC-induced survival of islet xenografts.

METHODS

: Collagenase-digested islets obtained from WS rats (RT1k) were incubated for 30 min with 10 microg/mL MMC and then transplanted into streptozotocin-induced diabetic C57BL/6 (H-2b) mice after 20 hr of culture at 37 degrees C.

RESULTS

Survival of xenografts was enhanced by pretreatment of islets with MMC. MMC-treated xenografts showed a mild inflammatory cell response and significantly minimal infiltration of macrophages, CD4 T cells, and CD8 T cells compared with untreated grafts. TGF-beta mRNA was increased at 20 hr after MMC treatment, and TGF-beta protein expression was also increased compared with untreated islet xenografts. TGF-beta concentration in blebs formed around the xenografts (but not in the serum) was higher in animals that underwent transplantation with MMC-treated islets than with untreated islets. Simultaneous transplantation of MMC-treated and untreated islets separately in each kidney of recipient mice showed that protection was only found in MMC-treated islets. Treatment of islets before transplantation by neutralizing anti-TGF-beta antibody suppressed the MMC-protective effects on graft survival, whereas no such effect was noted with isotype-matched immunoglobulin.

CONCLUSIONS

: The authors' results indicate that MMC treatment effectively reduces local inflammatory response and that such effects are mediated by increase of TGF-beta during the early period of islet transplantation.

Cyclosporine renal dysfunction

Cyclosporine (CsA), introduced as an immunosuppressive agent in the 1980s, quickly become the first-line treatment in organ transplantation. However, these improvements were associated with an increased incidence of renal dysfunction. CsA causes histopathological changes in renal transplants that are often difficult to distinguish from other processes, especially chronic allograft nephropathy. Enhanced angiotensin II, transforming growth factor-beta, and vascular endothelial growth factor expression together with down-regulation of nitric oxide synthesis may play roles in chronic CsA nephropathy. Efforts have recently focused upon protocols that minimize the risk of CsA nephrotoxicity while preserving low rates of acute rejection. Four types of CsA-sparing studies have emerged from recent clinical experience: (1) conversion studies in which a nonnephrotoxic drug is substituted to allow CsA reduction, (2) minimal CsA exposure studies in which reduced CsA doses are combined with nonnephrotoxic drugs, (3) withdrawal studies in which CsA is completely discontinued at some time after transplantation, and (4) CsA-free studies in which the drug is completely avoided from the time of transplantation. Monitoring of CsA immunosuppression according to C2 blood levels, which better correlate with the area under the time-concentration curve than trough concentrations, should reduce the risk for toxicity; however, the most appropriate target range has not yet been clearly established. Because of interindividual differences in CsA absorption and susceptibility to renal dysfunction, the current therapeutic drug monitoring should be supplemented with pharmacogenetic information on genetic variability of relevant genes for pharmacokinetic parameters and therapeutic targets. This approach may guide choices for immunosuppressants for particular patients, with low toxicity. Thus, despite of 20 years of its history, CsA renal dysfunction remains an important clinical challenge.

Characterization of a gene encoding two isoforms of a mitochondrial protein up-regulated by cyclosporin A in activated T cells

Cyclosporin A (CSA) is an immunosuppressor used in organ transplantation. A recent proteomic analysis has revealed that activation of T cells in the presence of CSA induces the synthesis of hundreds of new proteins. Here we used representational difference analysis to characterize some of the corresponding induced genes. After cDNA bank screening we focused on one of these genes, which we named CSA-conditional, T cell activation-dependent (CSTAD) gene. This gene produces two mRNAs resulting from alternative splicing events. They encode two proteins of 104 and 141 amino acids, CSTADp-S and CSTADp-L, for the short and long forms, respectively. FK506 had the same effect as CSA, whereas rapamycin did not affect the level of CSTAD gene expression, demonstrating that inhibition of the calcineurin activation pathway is involved in CSTAD gene up-regulation. CSA also led to overexpression of CSTAD in mice immunized in the presence of CSA, confirming the in vitro analysis. Microscopic and cytofluorimetric analysis of cells expressing green fluorescent protein-tagged CSTADp-L and CSTADp-S showed that both proteins colocalize with mitochondrial markers and depolarize the mitochondrial transmembrane potential without causing release of cytochrome c, apoptosis, or necrosis. Both CSTADp isoforms are sensitive to proteinase K, implying that they are located in the mitochondrial outer membrane. These data reveal a new mechanism of action for CSA, which involves up-regulation of a gene whose products are sorted to mitochondria and depolarize the mitochondrial membrane.

Protective effect of the immunosuppressant sirolimus against aortic atherosclerosis in apo E-deficient mice

Atherosclerosis is a chronic inflammatory disease that develops in response to injury to the vessel wall, and is augmented by hypercholesterolemia. To further delineate the role of the immune system and local factors in this process, we assessed the effects of the immunosuppressant sirolimus (Rapamycin, RAPAMUNE, Wyeth, Collegeville, PA) on atherosclerosis in the apoE-deficient (apoE KO) mouse, a well-accepted model of cardiovascular disease. ApoE KO mice were fed a high fat diet and sirolimus was administered. After 12 weeks, atherosclerotic lesions and plasma lipoproteins were measured. The expression of cytokines associated with atherosclerosis was also examined. All groups demonstrated plasma total cholesterol (TC) >1100 mg/dL. Sirolimus treatment was associated with a 30% increase in LDL-cholesterol (LDLc) and a dose-dependent elevation in HDL-cholesterol (HDLc). Despite increased LDLc, aortic atherosclerosis was markedly reduced in all sirolimus-treated groups. Sirolimus treatment resulted in decreased expression of IL-12p40, IFN-gamma and IL-10 mRNA. In contrast, TGF-beta1 was elevated. Sirolimus significantly reduced atherosclerosis in apo E-KO mice; this effect is independent of, and obviates, elevated plasma TC and LDLc. Sirolimus might therefore be of benefit on atherosclerosis in patients undergoing therapy, independent of any impact on circulating lipids.

The immunosuppressive agent tacrolimus induces p21WAF/CIP1WAF1/CIP1 via TGF-beta secretion

Tacrolimus (Tac) is more immunosuppressive drug compared to cyclosporine (CsA). Our previous studies have demonstrated that CsA induces the expression of p21WAF/CIP1 expression. In this study we explored if like CsA, Tac also induces expression of p21WAF/CIP1. We also determined if induction of p21WAF/CIP1 by Tac is dependent on TGF-beta. Using RT-PCR and Western blot analysis, we studied the induction of p21WAF/CIP1 mRNA and protein in human T cells and A-549 cells (human lung adenocarcinoma cells) by Tac. The stimulation of p21WAF/CIP1 promoter activity was studied by luciferase assay using p21WAF/CIP1-luc, chimeric plasmid DNA containing a p21WAF/CIP1 promoter segment and luciferase reporter gene. Using anti-TGF-beta antibody, we studied if induction of p21WAF/CIP1 by tacrolimus is dependent on TGF-beta. The results demonstrate that Tac induced p21WAF/CIP1 mRNA and protein expression as well as stimulated its promoter activity in T cells and A-549 cells. The induction of p21WAF/CIP1 expression by tacrolimus was dependent on TGF-beta since a neutralizing anti-TGF-beta antibody inhibited induction of p21WAF/CIP1in A-549 cells. These data support the hypothesis that cyclin inhibitor p21WAF/CIP1 might represent a unified mediator of the anti-proliferative effects of Tac and other immunosuppressive agents. Strategies involving p21WAF/CIP1 induction should be considered a viable alternative strategy to achieve immunosuppression possibly with reduced toxicity associated with current immunosuppression.

Therapeutic role of TGF-beta-neutralizing antibody in mouse cyclosporin A nephropathy: morphologic improvement associated with functional preservation

TGF-beta is believed to play a central role in the development of Cyclosporin A (CsA)-induced nephropathy. This study investigated the effects of 1D11, a murine pan-specific TGF-beta-neutralizing monoclonal antibody, in an ICR mouse model of chronic CsA nephropathy. Mice were administered a low-salt diet (0.01% sodium) for 1 wk followed by CsA treatment (30 mg/kg, subcutaneously, daily) for 4 wk. 1D11 was administered (2.5 mg/kg, intraperitoneally, 3 times/wk) beginning immediately after the termination of CsA dosing and continued through 8 wk. CsA caused extensive renal histopathologic alterations, including tubular damage, interstitial infiltrates and fibrosis, deposition of collagen III, and apoptosis of tubular epithelial cells. 1D11 ameliorated the CsA-induced histopathologic alterations, with significant reduction in collagen III expression and deposition. Additionally, elevated levels of mRNA encoding TGF-beta1 and TGF-beta2 were significantly reduced. 1D11 also protected tubular epithelial cells from apoptosis by 48% (P < 0.05). In contrast, 13C4 (a control antibody) had no significant effect on any of the endpoints described above. Importantly, the effects of 1D11 on the CsA-induced morphologic alterations were followed by a reduction in serum creatinine level when compared with CsA mice treated with 13C4 (13C4, 0.45 +/- 0.09; 1D11, 0.30 +/- 0.08; P < 0.05) after 8 wk of treatment. Endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), nitrotyrosine, and tissue hypoxia were examined by immunostaining using specific antibodies. eNOS was significantly reduced in the endothelium of arterioles in the kidneys of mice treated with CsA, whereas iNOS was induced in the cortical tubules. Tissue hypoxia was found in both the arterioles and tubules, whereas nitrotyrosine was localized in the tubules. Administration of 1D11 improved tissue hypoxia and reduced nitrotyrosine formation. Moreover, the reciprocal changes in iNOS and eNOS expression were normalized by 1D11. This study demonstrates that 1D11 administration ameliorated morphologic alterations and preserved renal function in the context of existing chronic CsA nephropathy.

Failure of cyclosporin A to induce transforming growth factor beta (TGF-beta) synthesis in activated peripheral blood lymphocytes

Induction of transforming growth factor beta (TGF-beta) by the immunosuppressive drug cyclosporin A (CsA) in activated lymphocytes has been claimed to add to the renal pro-fibrotic effects of CsA. The aim of this study was to evaluate CsA-mediated TGF-beta induction in a larger number of lymphocyte preparations from different donors. Peripheral blood lymphocytes (PBL) were obtained from healthy blood donors. The cells were stimulated with phytohemagglutinin E (PHA) and phorbol ester (tetradecanoyl phorbol acetate, TPA) in the presence or absence of CsA. TGF-beta, interleukin-2 (IL-2) and cyclooxygenase-2 (Cox-2) mRNA were detected by Northern blot analysis or by real time reverse transcriptase-polymerase chain reaction (RT-PCR). TGF-beta and IL-2 protein were determined in the cellular supernatants by enzyme-linked immunosorbent assay. TGF-beta mRNA and protein were up-regulated when the cells were stimulated with PHA/TPA. Cyclosporin A at high concentrations (500 ng/mL) caused a transient increase in TGF-beta mRNA which was significant after 2 h. CsA did not induce sustained TGF-beta protein expression (24-72 h) in any of the preparations (n = 14), whereas the up-regulation of IL-2 mRNA and protein was prevented by CsA in the same preparations. Furthermore, up-regulation of Cox-2 mRNA was inhibited by CsA. Taken together, there was no evidence for TGF-beta as a clinically relevant mediator being induced by CsA in activated peripheral blood T-lymphocytes.