TGF-beta expression in renal transplant biopsies: a comparative study between cyclosporin-A and tacrolimus

Calcineurin inhibitors: a double-edged sword

Recently, research has directed its interests into identifying molecular pathways implicated in calcineurin inhibitor (CNI)-induced renal fibrosis. An emerging body of studies investigating calcineurin (CnA) activity has identified distinct actions of two main ubiquitously expressed isoforms: CnAα and CnAβ. CNIs have the capacity to inhibit both of these CnA isoforms. In the kidney, CnAα is required for development, whereas CnAβ predominantly modulates the immune response and glomerular hypertrophic signaling powered by activation of the transcription factor, nuclear factor of activated T lymphocytes (NFAT). Interestingly, data have shown that loss of CnAα activity contributes to the expression of profibrotic proteins in the kidney. Although this finding is of great significance, follow-up studies are needed to identify how loss of the CnAα isoform causes progressive renal damage. In addition, it is also necessary to identify downstream mediators of CnAα signaling that assist in upregulation of these profibrotic proteins. The goal of this review is to provide insight into strides taken to close the gap in elucidating CnA isoform-specific mechanisms of CNI-induced renal fibrosis. It is with hope that these contributions will lead to the development of newer generation CNIs that effectively blunt the immune response while circumventing extensive renal damage noted with long-term CNI use.

Cardiomyocyte calcineurin is required for the onset and progression of cardiac hypertrophy and fibrosis in adult mice

Previous studies have demonstrated that activation of calcineurin induces pathological cardiac hypertrophy (CH). In these studies, loss-of-function was mostly achieved by systemic administration of the calcineurin inhibitor cyclosporin A. The lack of conditional knockout models for calcineurin function has impeded progress toward defining the role of this protein during the onset and the development of CH in adults. Here, we exploited a mouse model of CH based on the infusion of a hypertensive dose of angiotensin II (AngII) to model the role of calcineurin in CH in adulthood. AngII-induced CH in adult mice was reduced by treatment with cyclosporin A, without affecting the associated increase in blood pressure, and also by induction of calcineurin deletion in adult mouse cardiomyocytes, indicating that cardiomyocyte calcineurin is required for AngII-induced CH. Surprisingly, cardiac-specific deletion of calcineurin, but not treatment of mice with cyclosporin A, significantly reduced AngII-induced cardiac fibrosis and apoptosis. Analysis of profibrotic genes revealed that AngII-induced expression of Tgfβ family members and Lox was not inhibited by cyclosporin A but was markedly reduced by cardiac-specific calcineurin deletion. These results show that AngII induces a direct, calcineurin-dependent prohypertrophic effect in cardiomyocytes, as well as a systemic hypertensive effect that is independent of calcineurin activity.

De novo lung cancer diagnosed 32 months after liver transplantation: report of a case

Patients who undergo organ transplantation are now known to be at increased risk of the development of de novo malignant tumors. This is primarily a consequence of immunosuppression, which may promote tumor development and progression by a variety of mechanisms. It was also reported recently that the relative ratio of lung tumors developing in orthotopic liver transplantation patients was 3.7 times greater than in the general population. We report a case of de novo lung cancer diagnosed in a 65-year-old man 32 months after he underwent liver transplantation for hepatocellular carcinoma secondary to hepatitis C virus cirrhosis. He had received tacrolimus as immunosuppressive therapy after the liver transplantation. The tumor was resected, and he remains well almost 3 years later. Previous reports provide evidence that immunosuppressive therapy is a risk factor for de novo lung cancer; thus, it is important to reduce immunosuppression for orthotropic liver transplantation patients, and to screen them carefully to detect the tumor at an early stage.

Renal function and cardiovascular risk profile after conversion from ciclosporin to tacrolimus: prospective study in 80 liver transplant recipients

BACKGROUND

Increased risk of cardiovascular and cerebrovascular disease in liver transplant recipients results in particular from the side effects of calcineurin inhibitor-based immunosuppressive therapy. Several studies have demonstrated a more favourable outcome for patients receiving tacrolimus (TAC) as compared with ciclosporin (CS).

AIM

To investigate the effects of conversion from CS to TAC on cardiovascular risk factors and renal function in liver transplant recipients.

METHODS

In a prospective study, all except two patients had chronic kidney disease stages 2-4 (n = 80), according to estimated glomerular filtration rate using the abbreviated Modification of Diet in Renal Disease equation.

RESULTS

Conversion was accompanied with a mean decrease of total cholesterol from 194.6 +/- 54.0 mg/dL to 175.8 +/- 44.2 mg/dL (P < 0.001), low density lipoprotein cholesterol from 106.7 +/- 39.2 mg/dL to 90.9 +/- 28.6 mg/dL (P < 0.001) and mean arterial blood pressure values from 102.2 +/- 13.2 mm Hg to 95.9 +/- 11.7 mm Hg (P < 0.001). Renal function remained stable. No cases of de novo diabetes mellitus were identified. The Framingham risk score was significantly reduced from 5.2 +/- 4.4 at baseline to 4.4 +/- 5.3 after 12 months (P = 0.006).

CONCLUSIONS

Conversion from CS to TAC has been shown to improve the cardiovascular risk profile and may retard further decline of renal function after liver transplantation.

Randomized controlled study comparing reduced calcineurin inhibitors exposure versus standard cyclosporine-based immunosuppression

BACKGROUND

Immunosuppressive regimens based on low doses of cyclosporine A (CsA) or tacrolimus (TAC) may improve short-term outcome after kidney transplantation (KT), but the optimal immunosuppressive protocol is currently unknown.

METHODS

This study compared the 24-month efficacy and safety of two immunosuppressive regimens using reduced calcineurin inhibitors (CNIs) exposure with standard dosage of CsA in 240 patients who were randomized into three groups: group A (n=80): Thymoglobulin, CsA (4 mg/kg twice daily) plus azathioprine (1.5 mg/kg once daily); group B (n=80): basiliximab, CsA (2 mg/kg/ twice daily) plus mycophenolate mofetil (MMF; 1 g twice daily); and group C (n=80): basiliximab, TAC (0.05 mg/kg/ twice daily) plus MMF (1 g twice daily). Steroid administration was identical for all groups.

RESULTS

A significantly better creatinine clearance at 12 months, estimated by Cockcroft-Gault (57+/-12, 65.2+/-20, 73.5+/-27 ml/min, P=0.044), the Jelliffe-2 (51.5+/-16, 56+/-19, 59.4+/-19 ml/min/1.73 m2, P=0.041) and the Modification of Diet in Renal Disease equations (53+/-17, 58.5+/-20, 61.6+/-22 ml/min/1.73 m2, P=0.035), was observed in group C compared with group A. No significant differences were observed between groups B and C. The incidence of biopsy-proven acute rejection was similar between groups (15%, 13.8%, and 16.3%). In addition, patient and graft survival at 24 months were not different between groups. Adverse effects were similar among groups, but cytomegalovirus infections was significantly higher in group A (41% vs. 20% vs. 25%; P=0.008).

CONCLUSIONS

Immunosuppressive regimens with reduced CNI exposure provide similar preservation of renal function compared with standard dose of CsA after KT and do not lead to underimmunosuppression.

Mechanism of HDAC inhibitor FR235222-mediated IL-2 transcriptional repression in Jurkat cells

Interleukin (IL)-2 is an essential cytokine in T cell proliferation and homeostasis. The importance of IL-2 down-regulation in preventing acute rejection in organ transplantation and the development of autoimmune diseases has been demonstrated by the therapeutic usefulness of the widely used immunosuppressants cyclosporine A and FK506. Recently, a histone deacetylase (HDAC) inhibitor, FR235222, has been shown to inhibit IL-2 gene expression and to possess immunosuppressive activity in vivo. To elucidate the inhibitory mechanism of FR235222 in IL-2 gene expression, we performed Affymetrix GeneChip analysis of activated Jurkat cells treated with or without FR235222. Here, we show that many NF-kappaB-regulated genes are transcriptionally down-regulated by FR235222 in activated Jurkat cells. Further, luciferase reporter assays revealed that FR235222 selectively inhibits NF-kappaB activity without impairing NF-AT or AP-1 at the concentrations at which it potently inhibits IL-2 promoter activation. These results indicate that FR235222 inhibits IL-2 gene expression via a different mechanism to CsA and FK506, and that FR235222 has the ability to inhibit NF-kappaB activity, which may be partly related to the potent inhibition of IL-2 gene expression by FR235222. Our findings may help our understanding of the molecular mechanism of the inhibition of IL-2 gene expression by HDAC inhibitors and provide insight into the development of more effective and safer new immunosuppressants.

Hepatic stellate cell activation in liver transplant patients with hepatitis C recurrence and in non-transplanted patients with chronic hepatitis C

The pathogenic mechanisms of accelerated graft fibrosis in hepatitis C recurrence after liver transplantation (LT) are not well established. The aim of the study was to assess whether a greater activation of hepatic stellate cells (HSC), the major collagen-producing cells in the liver, can occur in these patients as compared to non-LT patients with chronic hepatitis C. We determined the amount of activated HSC by computer-based morphometric analysis of alpha-smooth muscle actin (alphaSMA)-positive cells and the hepatic TGFbeta(1) expression by immunohistochemistry in 46 LT patients with hepatitis C recurrence, 35 non-LT patients with chronic hepatitis C, and 16 controls. Hepatic alphaSMA and TGFbeta(1) expression was higher in LT patients with hepatitis C recurrence than in controls and was correlated with fibrosis stage and progression rate. No significant difference in alphaSMA and TGFbeta(1) expression was observed between LT and non-LT patients with hepatitis C, with the exception of a higher transforming growth factor beta-1 (TGFbeta(1)) expression in non-LT patients in the early stages of fibrosis. LT patients receiving cyclosporine (CsA) or tacrolimus (FK) had a similar fibrosis progression rate and alphaSMA and TGFbeta(1) expression. In conclusion, the accelerated fibrosis observed in LT patients with hepatitis C recurrence does not seem to be related to a greater amount of activated HSC and TGFbeta(1) expression in the grafts of these patients as compared to non-LT patients with chronic hepatitis C. In LT patients, the amount of activated HSC and TGFbeta(1) expression correlated with fibrosis stage and progression, without any apparent influence of the type of calcineurin inhibitor administered.

Tacrolimus in the treatment of idiopathic nephrotic syndrome

The immunosuppressant tacrolimus (FK-506) is a calcineurin inhibitor with a widespread use for the prevention of graft rejection in transplantation medicine. Tacrolimus inhibits the activation of an essential transcription factor for the transcription of cytokine genes in T cells leading to a decreased production of cytokines such as IL-2 and IFN-gamma. As T-cell activation plays a crucial role in the pathogenesis of inflammatory glomerular diseases, there is an increasing number of reports on the use of tacrolimus in nephrotic syndrome. In idiopathic nephrotic syndrome, corticosteroid treatment constitutes the first-line therapy to achieve remission. In the case of steroid resistance or steroid dependence, alternative immunosuppressive strategies are needed. Cyclophosphamide and ciclosporin are well-established drugs in this condition. The present article reviews the pharmacodynamics, pharmacokinetics, safety and clinical efficacy of tacrolimus in steroid-resistant and steroid-dependent nephrotic syndrome.

Rapamycin enhances the number of alloantigen-induced human CD103+CD8+ regulatory T cells in vitro

BACKGROUND

Regulatory T cells (T(reg) cells) may be operational in both the induction and maintenance of transplantation tolerance. We recently showed that alloantigen-induced CD103+ CD8+ T cells strongly suppressed T-cell proliferation in mixed lymphocyte culture (MLC) via a contact-dependent mechanism. CD103 directs T lymphocytes to their ligand E-cadherin, which is expressed on renal tubular epithelial cells, and CD103+ CD8+ T cells have been described to be present in late renal allograft rejection.

METHODS

We studied the influence of prednisolone, cyclosporin, tacrolimus, CD25 monoclonal antibodies, rapamycin, and mycophenolate mofetil (MMF) on the development and functional activity of alloantigen-activated CD103+ CD8+ T cells in MLC.

RESULTS

Calcineurin inhibitors, MMF, and CD25mAb did not influence the number of CD103 expressing CD8+ T cells. In contrast, corticosteroids diminished CD103 expression on alloactivated CD8+ T cells, which appeared to be caused by their inhibitory action on myeloid dendritic cells. Addition of rapamycin to allocultures led to an increased percentage of CD103+ CD8+ alloreactive T cells. Moreover, in the presence of rapamycin, these cells tended to show higher suppressive capacity.

CONCLUSIONS

Alloreactive CD103+ CD8+ T(reg) cells may expand and exert their suppressive function during immunosuppressive treatment with rapamycin. These data are relevant in the design of immunosuppressive drug regimens intended to induce and/or maintain transplantation tolerance.

Study on the Correlations among Disease Activity Index and Salivary Transforming Growth Factor-beta1 and Nitric Oxide in Ulcerative Colitis Patients

Growth factors and nitric oxide (NO) play a major role in dysregulated immune response in ulcerative colitis (UC). Recent evidence has shown increased levels of transforming growth factor-beta(1) (TGF-beta(1)) in UC and suggested an anti-inflammatory effect for this factor. Based on our recent study, dysfunctional immunoregulation is present in saliva of UC patients, we hypothesized that salivary level of NO and TGF-beta(1) may differ by severity of UC and be useful to determine the activity of the disease. Thirty-seven UC patients and 15 healthy controls were enrolled and saliva samples were obtained. Truelove-Witts severity index and modified Truelove-Witts severity index were used to determine the severity of the disease. NO and TGF-beta(1) levels were detected in saliva of all patients and control subjects using enzyme-linked immunosorbent assay. A total of 21 patients had mild disease while 8 had moderate and 8 had severe colitis. Adjusted for baseline characteristics, the levels of NO and TGF-beta(1) in different groups were compared. Salivary NO and TGF-beta(1) levels were higher in UC patients comparing to controls (P < 0.00005 and P = 0.005, respectively). The levels of NO and TGF-beta(1) showed no significant differences among the severity groups (P = 0.46 and P = 0.23, respectively). NO levels linearly increased by age (Coeff = 1.5, r = 0.38, P = 0.02). Gender, extension of disease, and medical treatment did not affect NO and TGF-beta(1) levels. Although UC patients have abnormal amounts of NO and TGF-beta(1) in their saliva, their disease activity cannot be predicted by these factors, which may indicate a pathophysiologic role rather than being nonspecific inflammatory markers for TGF-beta(1) and NO.

Alterations in Salivary Antioxidants, Nitric Oxide, and Transforming Growth Factor-β1in Relation to Disease Activity in Crohn's Disease Patients

It has been postulated that oxidative stress, nitric oxide (NO), and transforming growth factor beta(1) (TGF- beta(1)) have major roles in the pathophysiology of Crohn's disease (CD). The aim of this study was to determine the salivary levels of total antioxidant capacity (TAC), specific antioxidants (i.e., uric acid, albumin, transferrin, and thiol molecules), lipid peroxidation (LPO), NO, and TGF- beta(1) in CD patients and control subjects and to also investigate their correlation with activity of the disease. Twenty-eight patients with confirmed diagnosis of CD were enrolled and whole saliva samples were obtained. Smokers, diabetics, those who suffered from periodontitis, and those who were consuming antioxidant supplements were excluded from the study. The Crohn's Disease Activity Index (CDAI) was used to determine the severity of the disease. Twenty healthy subjects were also recruited. In CD patients significant reductions in salivary levels of TAC (0.248 +/- 0.145 vs. 0.342 +/- 0.110 mmol/L), albumin (1.79 +/- 0.42 vs. 2.3 +/- 0.2 microg/mL), and uric acid (3.1 +/- 1.4 vs. 4.1 +/- 2.0 mg/dL) were found. TGF-beta(1) was significantly increased in CD patients compared to healthy subjects (3.02 +/- 1.54 vs. 2.36 +/- 0.52 ng/mL). A fourfold increase in NO levels (198.8 +/- 39.9 vs. 50.2 +/- 21.3 micromol/L) along with a fivefold increase in LPO concentration (0.146 +/- 0.064 vs. 0.027 +/- 0.019 micromol/L) was documented in CD patients in comparison to the control group. CDAI significantly correlated with the TAC, LPO, and the interaction between TAC and LPO (r(2) = 0.625, r(2) = 0.8, F-test's P < 0.00005). Saliva of CD patients exhibits an abnormal feature with respect to oxidative stress, NO, and TGF-beta(1). TAC and LPO modify the effect of each other in determination of CD severity, which underlines the importance of oxidative stress in the pathogenesis of CD.

Impaired erythropoietin production in liver transplant recipients: the role of calcineurin inhibitors

Anemia is common following liver transplantation. Because cyclosporine inhibits erythropoietin (Epo) production in experimental models, we investigated whether Epo production was impaired in liver transplant recipients receiving a cyclosporine- or tacrolimus-based immunosuppressive regimen. First, serum Epo levels were measured before and 1 year after transplantation in 35 liver transplant recipients. Second, serum Epo levels were compared in a large series of liver transplant recipients with stable graft and renal functions: 27 receiving a cyclosporine-based and 31 receiving a tacrolimus-based immunosuppressive regimen. A reference group was made up of 22 blood donors and 21 nontransplanted subjects with iron-deficiency anemia. Serum Epo levels were significantly lower after than before liver transplantation, especially in cyclosporine-treated patients. Serum Epo concentrations correlated with hematocrit values in both transplant recipients and control subjects. Using multiple linear regression models, the polynomial relationship between hematocrit and serum Epo values was similar to the control group in patients under tacrolimus, whereas Epo production was significantly reduced in patients under cyclosporine-based immunosuppression. Hematocrit values and the type of calcineurin inhibitor were the only parameters independently related to Epo levels. In conclusion, cyclosporine, but not tacrolimus, inhibits Epo production at the doses used in clinical practice.

The role of tacrolimus in inflammatory bowel disease: a systematic review

Therapeutic management of inflammatory bowel disease remains beyond the limits of conventional therapy in many cases. Novel therapies used include tacrolimus, a new powerful immunosuppressive drug, employed in some case reports and a few studies that have tried to evaluate its effectiveness in Crohn's disease and ulcerative colitis with promising results, but its role in the management of inflammatory bowel disease remains controversial. We performed a systematic review that analyzed a total of 23 reported experiences in 286 patients with inflammatory bowel disease treated with tacrolimus. Although most of the published studies are uncontrolled, short, and heterogeneous, promising results have been obtained in fistulizing disease, unresponsive cases of both ulcerative colitis and Crohn's disease, and even extraintestinal manifestations. The overall outcome was good enough to consider tacrolimus as a rationale therapeutic option. However, comparative studies with standard therapeutic options like infliximab are needed to assess the correct role that tacrolimus may play in these patients.

Chronic allograft nephropathy: intraepithelial signals generated by transforming growth factor-beta and bone morphogenetic protein-7

It has been suggested that TGFbeta can cause chronic allograft nephropathy by inducing epithelial to mesenchymal transition (EMT); some studies show a reverse transition can be produced by bone morphogenetic protein-7 (BMP7). The current study assessed the relative contribution of signals generated within tubular epithelial cells by TGFbeta and BMP7 in normal kidney and after transplantation. Epithelial cells in normal human kidneys expressed phosphorylated forms of both Smad2/3 and Smad1/5/8 within their nuclei; cell culture experiments showed that these signaling molecules were generated in response to TGFbeta and BMP7, respectively. Phospho(p)-Smad2/3 was expressed at increased levels by tubular epithelial cells during acute renal allograft rejection and chronic allograft nephropathy but pSmad1/5/8 was expressed at very low levels; this staining profile was associated with induction of the EMT marker, S100A4. Further in vitro experiments demonstrated that this pattern of Smad signaling was a consequence of the stimulation of tubular epithelial cells with TGFbeta in the absence of BMP7. Importantly, addition of BMP7 to TGFbeta-stimulated cells enhanced the expression of pSmad1/5/8 and reduced expression of S100A4. These results suggest that exogenous BMP7 could restore the homeostatic balance of pSmad signaling found in normal kidneys, thereby preventing or reversing the development of chronic allograft nephropathy.

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

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

Apoptosis of allospecifically activated human helper T cells is blocked by calcineurin inhibition

BACKGROUND

Classical transplantation immunosuppression relies heavily upon the interruption of interleukin-2 (IL-2) signaling by calcineurin inhibition. However, recent evidence in murine models suggests that IL-2 is necessary for activation-induced cell death (AICD) of allograft-specific lymphocytes.

METHODS

We examined the apoptotic effects of the calcineurin inhibitor cyclosporine A and mTOR inhibitor rapamycin on the apoptotic alterations that occur in allospecifically activated human lymphocytes in a one-way mixed lymphocyte culture (MLC).

RESULTS

Cyclosporine increased caspase-3 activation in MLC, which corresponded with a decrease in lymphocyte apoptosis in MLC. Cyclosporine also reduced apoptosis in the CD4+ helper T cell subset, while CD8+ cells had similar or increased apoptosis when compared to controls. In contrast, rapamycin-treated cultures had normal levels of CD4+ T cell apoptosis when compared to control MLC, with decreases seen in CD8+ T lymphocytes.

CONCLUSIONS

In humans, blockade of IL-2 receptor signal with rapamycin allows apoptosis of allospecifically activated CD4+ lymphocytes to occur, while blockade of IL-2 production with cyclosporine results in decreased apoptosis in this T cell subset. As helper T cells are integral to the immune response, these results may explain the tolerogenic effects of rapamycin.

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.

Effects of long-term cyclosporin therapy on gingiva of rats: analysis by stereological and biochemical estimation

Cyclosporin A (CsA) is used as an immunosuppressive agent and its prominent side effect is the induction of gingival overgrowth, which remains a significant problem. The risk factors appraised include the duration of treatment. However, there are no stereological and biochemical studies exploring the effects of long-term CsA therapy on gingival tissue. The purpose of the present study was to investigate the level of TGF-beta1 in saliva and describe the densities of fibroblasts and collagen fibers in the gingival tissue of rats treated with CsA for long periods. Rats were treated for 60, 120, 180 and 240 days with a daily subcutaneous injection of 10 mg/kg of body weight of CsA. At the end of the experimental periods, saliva was collected for the determination of TGF-beta1 levels. After histological processing, the oral epithelium and the connective tissue area were measured as well as the volume densities of fibroblasts (Vf) and collagen fibers (Vcf). After 60 and 120 days of CsA treatment, there was a significant increase in Vf and Vcf as well as a significant increase in TGF-beta1 levels. After 180 and 240 days, reduction in the gingival overgrowth associated with significant decreases in the level of TGF-beta1, and also decreased Vf and Vcf, were observed. The data presented here suggest that after long-term therapy, a decrease in TGF-beta1 levels occurs, which might contribute to an increase in the proteolytic activity of fibroblasts in the gingiva, favoring the normality of extracellular matrix synthesis.

The effect of different immunosuppressive regimens on TGF-beta1 expression in kidney transplant patients

Transforming growth factor (TGF)-beta1 is a key profibrogenic cytokine associated with the pathogenesis of chronic allograft nephropathy (CAN). The primary aim of this study was to evaluate TGF-beta1 expression in protocol kidney graft biopsy in patients treated with different immunosuppressive regimens. Protocol kidney graft biopsies were carried out in 77 patients with stable graft function at 1 year after kidney transplantation, treated with a triple-drug regimen based on cyclosporin A (CyA; n = 49) or tacrolimus (TAC; n = 28). Morphological findings were assessed using the Banff 97 classification. TGF-beta1 expression was analysed using immunochemistry, and semiquantitatively scored in different renal structures (total score 0-18). Clinical data were analysed at the time of biopsy, and 12 months thereafter. No significant relation was found between the used immunosuppressive regimen and the histomorphological picture in the graft. TGF-beta1 expression within graft tissue was significantly higher in patients treated with CyA when compared with TAC (9.94 +/- 4.2 vs. 5.0 +/- 3.2; P < 0.001). Serum creatinine and glomerular filtration rate (GFR; Cockroft-Gault calculation) were comparable in both groups but, in the course of the next 12 months, GFR significantly decreased only in the CyA-treated group (from 1.03 +/- 0.33 to 0.96 +/- 0.37 ml/s) while not changing in the TAC-treated group. Patients treated with TAC had significantly lower diastolic blood pressure and serum cholesterol. The significantly lower TGF-beta1 expression in 1-year protocol kidney graft biopsy in TAC-treated patients with stable renal function, and the different development of graft function in both groups suggest a possible benefit of TAC for long-term graft acceptance.

The Experimental Agent Pirfenidone Reduces Pro-Fibrotic Gene Expression in a Model of Tacrolimus-Induced Nephrotoxicity

BACKGROUND

Tacrolimus nephrotoxicity is thought to contribute to renal allograft dysfunction and subsequent failure, a process that is underpinned by alterations in mRNA expression of genes involved in matrix metabolism. The new anti-fibrotic pirfenidone was tested for its potential to reverse markers of renal dysfunction.

MATERIALS AND METHODS

Rats were salt-depleted before tacrolimus and pirfenidone treatment. Serum creatinine, urinary protein/creatinine ratio, extracellular matrix deposition (ECM), and mRNA expression of genes involved in matrix turnover were assessed.

RESULTS

Tacrolimus reduced TGF-beta mRNA expression below control levels and treatment with pirfenidone at all doses did not alter this effect. Likewise, TIMP-1 mRNA expression was depressed by the addition of tacrolimus and pirfenidone caused a further decrease in expression. Collagen III, MMP-2, and MMP-9 expression was unchanged by tacrolimus, but pirfenidone reduced collagen III below control levels. ECM was slight (1-4%) and not significantly different between groups.

CONCLUSIONS

These findings suggest that pirfenidone can attenuate the limited fibrotic potential of tacrolimus.

Mycophenolate Mofetil but Not the Type of Calcineurin Inhibitor (Cyclosporine vs Tacrolimus) Influences the Intragraft mRNA Expression of Cytokines in Human Kidney Allograft Biopsies by In Situ RT-PCR Analysis

The aim of the study was to assess the molecular background of the alloimmune response by the detection of low-abundance mRNA of cytokines in 34 core needle biopsies from kidney allografts with histopathological findings of acute rejection (AR). Recipients were immunosuppressed with a calcineurin inhibitor (CNI), cyclosporine or tacrolimus, and prednisone and azathioprine or mycophenolate mofetil (MMF). Tubular and glomerular expression of IL-2, IL-6, IL-10, IFN-gamma, TGF-beta1, and PDGF-B mRNA were assessed using semiquantitative evaluations of RT-PCR in situ on paraffin tissue sections. This procedure resulted in light microscopy visualization of granular precipitates at the sites of the corresponding mRNA chains. The tubular expression of mRNA for IL-6 and TGF-beta1 was significantly lower in biopsies with AR (n = 34) obtained from patients treated with MMF (n = 12) than in biopsies obtained from patients treated with azathioprine (n = 22) (P < .02). Responsiveness to corticosteroids tended to be more frequent among the MMF group (11 of 12 recipients vs 15 of 22 recipients, P = ns). Moreover, 8 of 12 recipients in the MMF-treated group displayed serum creatinine levels equal or less than 167 mmol/L 1 year after biopsy compared to 7 of 22 recipients in the azathioprine-treated group. There was no significant difference between the groups that had or had not received corticosteroids or between those treated with each type of CNI. These results suggest stronger inhibition of humoral responses and down-regulation of fibrosis by MMF among recipients with AR.

Concentrations of cyclosporin A and FK506 that inhibit IL-2 induction in human T cells do not affect TGF-beta1 biosynthesis, whereas higher doses of cyclosporin A trigger apoptosis and release of preformed TGF-beta1

Cyclosporin A (CsA) and FK506 suppress T cell activation by inhibiting calcineurin and the calcineurin-dependent transcription factors nuclear factor of activated T cells (NFATc), which are central regulators of T cell function. It was reported that CsA up-regulated the transcription of transforming growth factor-beta1 (TGF-beta1) in lymphocytes and other cells and activated its promoter in A549 lung carcinoma cells, but the mechanisms involved are poorly understood, and it is unclear whether calcineurin plays any role. We have studied the regulation of TGF-beta1 in normal human lymphocytes and cell lines. In Jurkat T cells, the TGF-beta1 promoter was activated by calcineurin and NFATc and inhibited by CsA and FK506. However, the promoter was insensitive to both drugs in A549 cells. In human T cells preactivated with phytohemagglutinin, biosynthesis of TGF-beta1, induced by the T cell receptor (TCR) or the TGF-beta receptor, was not substantially affected by CsA and FK506 concentrations (< or = 1 microM) that effectively inhibited interleukin-2 production. However, pretreatment of fresh lymphocytes with CsA or FK506 during primary TCR stimulation reduced their production of TGF-beta1 during secondary TCR activation. Finally, high concentrations of CsA (10 microM), in the range attained in vivo in experiments in rodents, caused apoptosis in human T cells and the release of preformed, bioactive TGF-beta1. These effects are unlikely to owe to calcineurin inhibition, as they were not observed with FK506. Our results indicate that CsA and FK506 are not general inducers of TGF-beta1 biosynthesis but can cause different effects on TGF-beta1 depending on the cell type and concentrations used.

Immunosuppression and gingival overgrowth: gene and protein expression profiles of collagen turnover in FK506-treated human gingival fibroblasts

AIM

FK506 is an immunosuppressive agent that, unlike cyclosporin A (CsA), does not induce gingival overgrowth (GO). CsA-induced GO is caused by quantitative modifications of the extracellular matrix components, particularly collagen (COL). Up to now, clinical trials have only investigated FK506 in relation with GO, so we aimed at analysing the effect of FK506 on COL turnover using a molecular approach, to evaluate the expression of genes and proteins related to this process.

MATERIALS AND METHODS

Human gingival fibroblasts were incubated with FK506 or its vehicle (VH) for 24, 48 and 72 h. COL type I (COL-I), matrix metalloproteinases (MMP)-1 and 2, tissue inhibitor of MMP (TIMP)-1 and transforming growth factor (TGF)-beta1 mRNA were assayed by Reverse transcriptase polymerase chain reaction; COL-I protein levels were determined by dot blot, MMP-1 and MMP-2 activity by zymography.

RESULTS

Fibroblast proliferation decreased 48 and 72 h after treatment. COL-I gene and protein expression, TGF-beta1 and TIMP-1 mRNA levels were not significantly affected, whereas MMP-1 gene and protein expression and MMP-2 mRNA levels rose significantly in treated fibroblasts compared with VH.

CONCLUSIONS

These findings suggest that increased MMP-1 gene and protein expression may be important for regulating COL-I homeostasis in the gingival connective compartment of FK506-immunosuppressed subjects.

Overview of tacrolimus-based immunosuppression after heart or lung transplantation

Transplantation has evolved into an accepted treatment for end-stage heart or lung disease. Acute rejection, complications related to immunosuppressive protocols, and the development of chronic rejection continue to challenge the long-term success of heart and lung transplantations. Wide acceptance of tacrolimus as an important immunosuppressant in renal and hepatic transplantations has led subsequently to its investigation as primary immunosuppression in heart and lung transplant recipients, either combined with azathioprine or with the newer agents mycophenolate mofetil or rapamycin. Studies have shown that tacrolimus is an effective therapeutic alternative to cyclosporine for primary immunosuppression in heart or lung transplantation and demonstrates equivalent if not improved prophylaxis of acute rejection, and more recently demonstrates a potential influence on chronic rejection, particularly in lung transplant recipients. Of importance, the enhanced immunosuppressive activity of tacrolimus is achieved without increased risk of infection or malignancy. Differences in tolerability profiles and side effects between tacrolimus and cyclosporine may be used in selecting the optimal immunotherapy after thoracic transplantation. In particular, the lesser propensity of tacrolimus to cause hypertension and hyperlipidemia potentially offers decreased cardiovascular risk for heart and lung transplant recipients.

Effect of immunosuppressive agents on long-term survival of renal transplant recipients: focus on the cardiovascular risk

In the control of acute rejection, attention is being focused more and more on the long-term adverse effects of the immunosuppressive agents used. Since cardiovascular disease is the main cause of death in renal transplant recipients, optimal control of cardiovascular risk factors is essential in the long-term management of these patients. Unfortunately, several commonly used immunosuppressive drugs interfere with the cardiovascular system. In this review, the cardiovascular adverse effects of the immunosuppressive agents currently used for maintenance immunosuppression are thoroughly discussed. Optimising immunosuppression means finding a balance between efficacy and safety. Corticosteroids induce endothelial dysfunction, hypertension, hyperlipidaemia and diabetes mellitus, and impair fibrinolysis. The use of corticosteroids in transplant recipients is undesirable, not only because of their cardiovascular effects, but also because they induce such adverse effects as osteoporosis, obesity, and atrophy of the skin and vessel wall. Calcineurin inhibitors are the most powerful agents for maintenance immunosuppression. The calcineurin inhibitor ciclosporin (cyclosporine) not only induces these same adverse effects as corticosteroids but is also nephrotoxic. Tacrolimus has a more favourable cardiovascular risk profile than ciclosporin and is also less nephrotoxic. It has little or no effect on blood pressure and serum lipids; however, its diabetogenic effect is more prominent in the period immediately following transplantation, although at maintenance dosages, the diabetogenic effect appears to be comparable to that of ciclosporin. The diabetogenic effect of tacrolimus can be managed by reducing the dose of tacrolimus and early corticosteroid withdrawal. The effect of tacrolimus on endothelial function has not been completely elucidated. The proliferation inhibitors azathioprine and mycophenolate mofetil (MMF) have little effect on the cardiovascular system. Yet, indirectly, by inducing anaemia, they may lead to left ventricular hypertrophy. MMF is an attractive alternative to azathioprine because of its higher potency and possibly lower risk of malignancies. Sirolimus also induces anaemia, but may be promising because of its antiproliferative features. Whether the hyperlipidaemia induced by sirolimus counteracts its beneficial effects is, as yet, unknown. It may be combined with MMF, however, initial attempts resulted in severe mouth ulcers.

Current and future immunosuppressive strategies in renal transplantation

The past decade has witnessed the introduction of several new immunosuppressive agents. The availability of these new pharmacologic offerings has not diminished the challenge of achieving a balance of adequate graft protection while minimizing the consequences of excessive immunosuppression. For renal transplant recipients, maintenance immunosuppression generally consists of a calcineurin inhibitor in combination with an antiproliferative agent and a corticosteroid; more recently, mammalian target of rapamycin inhibitors have been used. Excellent results have been achieved at many transplant centers with combinations of these agents in a variety of protocols. Regimens designed to limit or eliminate calcineurin inhibitor and/or corticosteroid therapy are actively being pursued in the transplant community. Allograft tolerance and xenotransplantation are being studied, and the knowledge gained from the effort may help in the development of innovative strategies and new immunosuppressive agents.

Plasma TGF-beta1 as a risk factor for gingival overgrowth

BACKGROUND AND AIMS

Induction of the pro-fibrotic growth factor TGF-beta1 has been suggested as a possible mechanism through which immunosuppressant drugs may induce gingival overgrowth. This study aims to investigate plasma levels of TGF-beta1 and relate them to the development and severity of gingival overgrowth in immunosuppressed transplant patients.

MATERIALS AND METHODS

One hundred and thirty-two ciclosporin-treated and 13 tacrolimus-treated transplant patients and 24 drug-free control subjects underwent a full periodontal examination including a determination of the presence and severity of gingival overgrowth.

RESULTS

Plasma TGF-beta1 concentrations were determined by ELISA, and were found to be significantly elevated in samples from the transplant patients (mean=29.1 ng/ml) as compared with controls (mean=6.1 ng/ml, p<0.0001). There was no significant difference between the levels of plasma TGF-beta1 in the ciclosporin- and tacrolimus-treated patient groups.

CONCLUSIONS

Furthermore, concomitant treatment with calcium channel blockers did not influence the levels of plasma TGF-beta1 in the patients group. The relationship between gingival overgrowth, independent periodontal variables and TGF-beta1 plasma concentrations was examined using univariate and multivariate regression analyses; low TGF-beta1 plasma concentrations were found to be a risk factor for gingival overgrowth in immunosuppressed patients concomitantly receiving a calcium channel blocker.

Extracellular glycosaminoglycan changes in healthy and overgrown gingiva fibroblasts after cyclosporin A and cytokine treatments

BACKGROUND

It has been demonstrated that cyclosporin A (CyA) blocks the immune system, acts on cytoskeleton and stimulates the production of extracellular matrix (ECM) and transforming growth factor-beta1 (TGF-beta1). This cytokine, such as transforming growth factor-alpha (TGF-alpha), induces deposition of glycosaminoglycans (GAG), proteoglycans and collagen fibres in the ECM.

METHODS

In this work, we examined the effect induced by CyA, TGF-beta1 and TGF-alpha on cultures of healthy and overgrown human gingival fibroblasts in order to evaluate the glycosaminoglycan, cytoskeletal changes and the behaviour of fibroblasts after concanavalin A (Con A) treatment. Moreover, we examined gingival biopsies by Alcian blue histochemical staining and electron transmission microscopy.

RESULTS

Total and extracellular sulphated GAG in overgrown gingiva specimens and in derived fibroblast cultures treated with CyA and cytokines were significantly higher than controls. The action of cytokines was increased (P < or = 0.01) compared with CyA with a greater effect of TGF-alpha in comparison with TGF-beta1; the electron microscopy showed ECM accumulation. The agglutinations showed the heterogeneity of fibroblast populations.

CONCLUSIONS

Stimulation with Con A showed that the fibroblast population had cell surface heterogeneity, and could respond in a different way to both CyA and cytokine stimulus. Moreover, increased synthesis of GAG in overgrown gingiva compared with synthesis in normal fibroblasts before CyA treatment suggests a possible genetic origin of damage. As not all CyA-treated patients develop gingival overgrowth, a genetic predisposition may explain the different responses of gingival fibroblast populations.

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.

Conversion from cyclosporine to tacrolimus improves quality-of-life indices, renal graft function and cardiovascular risk profile

Long-term use of cyclosporine after renal transplantation results in nephrotoxicity and an increased cardiovascular risk profile. Tacrolimus may be more favorable in this respect. In this randomized controlled study in 124 renal transplant patients, the effects of conversion from cyclosporine to tacrolimus on renal function, cardiovascular risk factors, and perceived side-effects were investigated after a follow-up of 2 years. After conversion from cyclosporine to tacrolimus renal function remained stable, whereas continuation of cyclosporine was accompanied by a rise in serum creatinine from 142 +/- 48 micromol/L to 157 +/- 62 micromol/L (p < 0.05 comparing both groups). Conversion to tacrolimus resulted in a sustained reduction in systolic and diastolic blood pressure, and a sustained improvement in the serum lipid profile, leading to a reduction in the Framingham risk score from 5.7 +/- 4.3 to 4.8 +/- 5.3 (p < 0.05). Finally, conversion to tacrolimus resulted in decreased scores for occurrence of and distress due to side-effects. In conclusion, conversion from cyclosporine to tacrolimus in stable renal transplant patients is beneficial with respect to renal function, cardiovascular risk profile, and side-effects. Therefore, for most renal transplant patients tacrolimus will be the drug of choice when long-term treatment with a calcineurin inhibitor is indicated.

Effect of inhaled fluticasone propionate on BAL TGF-β1 and bFGF concentrations in clinically stable lung transplant recipients

BACKGROUND

Inhaled fluticasone propionate (FP) therapy decreases inflammation and sub-basement membrane thickness in asthmatic airways. Bronchiolitis obliterans syndrome (BOS) in lung transplant recipients (LTRs) involves progressive airway fibrosis and obliteration. Therefore, augmented immunosuppression may be of some benefit in treating BOS. In this study, we examined the effect of 3 months of treatment with high-dose inhaled FP on the concentrations of 2 fibrogenic factors, transforming growth factor (TGF)-beta(1) and beta fibrogenic growth factor (bFGF) in bronchoalveolar lavage (BAL) fluid from clinically stable LTRs.

METHODS

We conducted a randomized, double-blind, placebo-controlled, parallel group study with inhaled FP (750 microg, twice/day for 3 months) in 28 LTRs (15 FP and 13 placebo). We recruited 23 healthy controls. We performed spirometry, bronchoscopy, and bronchoalveolar lavage procedures before treatment and after 3 months of treatment. We used commercially available enzyme-linked immunosorbent assay kits to measure BAL fluid TGF-beta(1) and bFGF concentrations.

RESULTS

In LTRs before treatment, BAL TGF-beta(1) concentrations (but not bFGF concentrations), total cell counts, and neutrophil percentage increased compared with controls (p < 0.05). We found no significant differences between FP and placebo groups at baseline measurements. After treatment, BAL TGF-beta(1) concentrations significantly increased in the FP group (p = 0.03), but we found no difference between FP and placebo groups; BAL bFGF concentrations increased during treatment in both groups compared with controls (p < 0.05), but not significantly within either patient group (p > 0.05). We found a reverse correlation between forced expiratory volume in 1 second (FEV(1)) and BAL TGF-beta(1) concentration in the FP group (r = -0.53, p = 0.04), and between FEV(1) and BAL TGF-beta(1) concentration in the placebo group (r = -0.74, p = 0.004). Multivariable analysis indicated no significant independent effects of inhaled FP in either BAL TGF-beta(1) or bFGF concentrations.

CONCLUSIONS

Bronchoalveolar fluid TGF-beta(1) concentrations increased in LTRs after transplantation and may correlate with the decrease in lung function. Inhaled FP added to conventional immunosuppression had no effect on TGF-beta(1) or bFGF production in BAL fluid.

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

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

High urine sIL-6R as a predictor of late graft failure in renal transplant recipients

BACKGROUND

Chronic allograft nephropathy is an important cause of late renal transplant failure. Although numerous studies on cytokines have been carried out, the pathogenetic role of cytokines in chronic renal allograft nephropathy remains unclear.

METHODS

In a retrospective study, the authors compared posttransplant plasma and urine cytokine levels (interleukin [IL]-1alpha, IL-1beta, soluble [s] IL-1 receptor [R] antagonist [A], IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-10, tumor necrosis factor-alpha, transforming growth factor-beta2, and interferon-gamma) in 34 matched pairs of patients with or without late graft failure and in 50 matched pairs with either normal or increased serum creatinine levels and continued stable graft function.

RESULTS

Twelve and 6 months before late graft failure, urine levels of sIL-6R were significantly increased (P=0.003 and P=0.01, respectively). Serum creatinine levels were not associated with increased urine sIL-6R.

CONCLUSION

High urine sIL-6R appears to be predictive of late graft failure in renal transplant recipients.

Urinary transforming growth factor-beta1 excretion in renal allograft recipients during the early post-transplantation period

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1), the major fibrogenic growth factor, is implicated in the pathogenesis of renal scarring in experimental and clinical nephropathies as well as in chronic allograft nephropathy. In this study we examined the pattern of changes of TGF-beta1 excretion in the urine and the sites of TGF-beta1 expression in the kidney of transplanted patients during the early post-transplantation period.

METHODS

Eighteen renal allograft recipients were included in the study. In all patients urinary TGF-beta1 levels were determined by ELISA in sequential measurements during the first two postoperative months and compared to that of 14 healthy subjects. The renal expression of TGF-beta1 protein was studied in 4 patients that underwent a biopsy of the transplanted kidney at the same period. All patients were treated with prednisolone, cyclosporin, and mycophenolate mofetil.

RESULTS

Urinary TGF-beta1 levels were increased during the first postoperative days. Although they were gradually reduced during the first two post-operative months, they remained significantly higher compared to those of normal subjects (580 +/- 148 ng/24 h vs. 310 +/- 140 ng/ 24 h p < 0.01). The decline of urinary TGF-beta1 excretion followed that of serum creatinine. TGF-beta1 protein expression was identified within the cytoplasm of tubular epithelial cells of transplanted patients.

CONCLUSIONS

Elevated urinary TGF-beta1 levels are observed during the early post-transplantation period in renal allograft recipients and are maintained high even after restoration of renal function to normal.

Differential effects of interleukin-2 blockade on apoptosis in naïve and activated human lymphocytes

BACKGROUND

Certain transplantation immunosuppressive strategies are primarily based on the interruption of interleukin (IL)-2 signaling by calcineurin inhibition or anti-IL-2 receptor-antibody blockade. However, recent evidence suggests that IL-2 is necessary for peripheral deletion of allograft-specific lymphocytes.

STUDY DESIGN

In this study, we examined the apoptotic effects of the calcineurin inhibitor, cyclosporine A, the chimeric anti-interleukin-2 receptor monoclonal antibody, basiliximab, and the rabbit antihuman thymocyte preparation Thymoglobulin (rATG) on phytohemagglutinin-activated human lymphocyte models designed to simulate initial exposure to the graft or ongoing rejection of the graft.

RESULTS

We found that rATG increases Fas expression, decreases Bcl-2 expression, and induces early apoptosis in naïve lymphocytes. However, rATG has more of a necrotic effect on activated lymphocytes. Basiliximab and cyclosporine had little effect on apoptosis, but did alter Bcl-2 and Fas expression.

CONCLUSIONS

Compared with IL-2 pathway inhibitors, rATG increases lymphocyte apoptosis, probably via Bcl-2 pathway inhibition. Because apoptosis is required for the development of graft tolerance, induction strategies that use IL-2-independent pathways may be advantageous.

CD8(+) T cells induce graft vascular occlusion in a CD40 knockout donor/recipient combination

BACKGROUND

It has recently been shown that treatment of animals with antibodies to CD154 (CD40L), allows for prolongation of cardiac allograft survival, but does not inhibit development of graft vasculopathy. CD8(+) T cells have been implicated in this effect. In this study we assess the role of CD40-CD154 interactions and CD40-independent CD8(+) T cells in the permanent and complete absence of CD40 by using donors and recipients genetically deficient in CD40.

METHODS

Hearts from BALB/c CD40(-/-) donors were transplanted into C57BL/6 CD40(-/-) recipients in the presence or absence of CD8(+) T-cell depletion. At Day 60, hearts were examined for vasculopathy using quantitative morphometry and numbers of infiltrating T cells were counted. The intragraft expression of interferon-gamma (IFN-gamma), transforming growth factor-beta1 (TGF-beta1), interleukin-4 (IL-4), eotaxin and CCR3 was assessed using competitive reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

In the absence of CD8(+) T-cell depletion, the mean percent intimal occlusion was 28% (with 50% of vessels showing no intimal occlusion). This figure was reduced significantly to 12% and 80% of vessels showing no intimal occlusion in mice receiving anti-CD8 antibody. Depletion of CD8(+) T cells was associated with significantly reduced intragraft IFN-gamma, TGF-beta1 and CCR3 expression, whereas mRNA production of IL-4 and eotaxin was increased.

CONCLUSION

Vascular intimal occlusion progresses in the complete absence of CD40-CD154 interactions, albeit to quite a small degree. The residual disease is significantly reduced by anti CD8(+) T-cell treatment, confirming the importance of CD40-CD154-independent CD8(+) T cells in the genesis of this disease.

Centrilobular fibrosis in long-term follow-up of pediatric liver transplant recipients

BACKGROUND

Centrilobular fibrosis after liver transplant in adults is caused mainly by viral hepatitis, chronic rejection, and azathioprine toxicity. The aim of this study was to investigate possible etiologies and the long-term outcome of this lesion in children.

METHODS

We identified centrilobular fibrosis in 12 of 117 pediatric liver transplant recipients who were investigated for persistent elevations in aminotransferases. Etiologic factors, histologic features on serial biopsies, and clinical and biochemical changes over time were noted for 8 recipients in whom a readily identifiable cause was not apparent.

RESULTS

Centrilobular fibrosis developed a mean of 1.7 years (range: 30 days-3.6 years) posttransplantation in patients receiving cyclosporine, azathioprine, and prednisone. Centrilobular fibrosis was always associated with portal fibrosis and, in six recipients, with persistent, low-grade, cellular rejection. None demonstrated chronic cholestasis, ductopenia, or identifiable vasculopathy. Ischemic, viral, and autoimmune etiologies were excluded. Discontinuing azathioprine did not lead to biochemical or histological improvement. After changing to tacrolimus, aminotransferases normalized in three recipients and repeat biopsies in six were unchanged during a further 2 years of follow-up.

CONCLUSIONS

Centrilobular fibrosis may develop in a small number of pediatric liver transplant recipients, resulting in considerable difficulties in biopsy interpretation. It is not associated with viral hepatitis nor with classical features of chronic rejection. The prognostic significance of centrilobular fibrosis is uncertain, although no child has required retransplantation in up to 12 years of follow-up. A role for a low-grade, chronic form of cellular rejection heralded by persistent, variable, and otherwise unexplained elevations in aminotransferases is suggested.

Cyclosporin A and transforming growth factor beta modify the pattern of extracellular glycosaminoglycans without causing cytoskeletal changes in human gingival fibroblasts

Cyclosporin A is a powerful immunosuppressive drug that has had a major impact on transplant therapy. It apparently links to different enzymatic pathways, and affects multiple enzymatic systems. Transforming growth factor beta induces the deposition of glycosaminoglycans, proteoglycans, and collagen fibers in the extracellular matrix. The aim of this study of normal and hypertrophic human gingival fibroblast cultures was to evaluate the cytoskeletal and extracellular changes in glycosaminoglycan secretion due to the presence of cyclosporin A and transforming growth factor beta. The results showed that there is an increase in total and individual classes of extracellular glycosaminoglycans in the presence of cyclosporin A and transforming growth factor beta, but the action of the latter was significantly greater. Immunohistochemical analysis of the cytoskeleton did not reveal any morphological differences between treated and control cells. Our data suggest that the biochemical changes in the extracellular matrix are caused more by cytokine, and that cyclosporin A does not induce any morphological changes in fibroblast cultures derived from hypertrophic and normal gingiva.

De novo malignancies after liver transplantation: a major cause of late death

1. Recurrent and de novo malignancies are the second leading causes of late death in liver transplant recipients, following age-related cardiovascular complications. 2. The increased incidence of de novo malignancies in liver transplant recipients compared with the general population reflects their demographic makeup, known preexistent risk factors for cancer, greater rate of chronic viral infection, and actions of exogenous immunosuppression. 3. The greatest incidence of de novo malignancies is seen in cancers associated with chronic viral infections, such as Epstein-Barr virus-associated posttransplant lymphoproliferative disease, and skin cancers, including squamous cell carcinoma and Kaposi's sarcoma. 4. Although a greater incidence of such malignancies as oropharyngeal malignancy and colorectal cancer was noted, there did not appear to be an increased risk for liver transplant recipients matched for age, sex, and length of follow-up using modified life-table technique and Surveillance Epidemiology End Result data with a similar at-risk group. However, they may present with more advanced stages of disease. 5. An increased incidence of de novo cancers in chronically immunocompromised liver transplant recipients demands careful long-term screening protocols to help facilitate diagnosis at an earlier stage of disease.