Early high levels of regulatory T cells and T helper 1 may predict the progression of recurrent hepatitis C after liver transplantation.

BACKGROUND: Immune response failure against hepatitis C virus (HCV) has been associated with an increased regulatory T cell (Treg) activity. After liver transplantation (LT), 80% of patients experience an accelerated progression of hepatitis C recurrence. The aim of this work was to assess the involvement of Tregs, T helper (Th) 1, 2 and 17 cells in recurrent hepatitis C. METHODS: Peripheral blood cells obtained before and one month after LT from 22 recipients were analysed. Forty-four key molecules related to Treg, Th1, 2 and 17 responses, were evaluated using qRT-PCR. Liver recipients were classified in two groups according to graft fibrosis evaluated by the METAVIR score on the biopsy performed one year after LT (mild: F ≤ 1, n = 13; severe: F > 1, n = 9). Patients developing a severe recurrence were compared with patients with a mild recurrence. RESULTS: mRNA levels of Treg markers obtained one month after LT were significantly increased in patients with a severe disease course when compared to patients with a mild recurrence. Markers of the Th1 response were elevated in the same group. No differences in the markers determined before LT were observed. CONCLUSION: These findings suggest that Treg, induced by a multifactorial process, which could include a strong Th1 response itself, may play a role in suppressing the early antiviral response, leading to a severe recurrence of hepatitis C.

Corticosteroids do not reverse the inhibitory effect of cyclosporine on regulatory T-cell activity in contrast to mycophenolate mofetil.

BACKGROUND: Inevitable hepatitis C virus recurrence after liver transplantation, a major barrier to survival of the transplanted liver may be promoted by immunosuppression and by CD4(+)CD25(+) regulatory T cells (Treg). Treg cells are essential for the induction and maintenance of immunologic self-tolerance as well as transplant tolerance. Moreover, we have previously described low doses of cyclosporine (CsA) to inhibit Treg activity by inducing interleukin-2 and interfron-γ. We investigated here in, the effect of mycophenolate mofetil (MMF) and corticosteroids, usually used in combination with a calcineurin inhibitor on human CD4(+)CD25(+) Treg cells. METHODS: Human CD4(+)CD25(+) cells isolated from healthy donors were cultured in the presence of CsA +/- corticoids or MMF. Suppressive activity of regulatory T cells was assessed in mixed leukocyte reactions including CD25(+) solvents with autologous activated peripheral blood mononuclear cells (PBMC). RESULTS: MMF and dexamethasone inhibited PBMC and Treg proliferation in dose-dependent fashing, maintaining the suppressive activity of Treg cells. However, the association of corticoids with CsA could not reverse the inhibitory effects of CsA on Treg activity, unlike the MMF and CsA combination. CONCLUSION: We have previously shown CsA to significantly impair the function of CD4(+)CD25(+) Treg cells. Herein we reports that corticoids were not able to reverse this effect, whereas MMF couterbalanced it, suggesting that the combination of MMF with CsA maintains regulatory T cells activity promoting tolerance.

Cyclosporine inhibits profibrotic effects of interleukin-4 and transforming growth factor ß on human intrahepatic fibroblasts cultured in vitro.

BACKGROUND: Hepatic fibrosis, an outcome of chronic liver diseases, is characterized by an accumulation of collagen, which is produced by activated human intrahepatic fibroblasts (HIF). Transforming growth factor (TGF) ß is an important inducer of fibrogenesis, in collaboration with other cytokines, such as interleukin (IL) 4. IL-4 is overexpressed in severe recurrent hepatitis C after liver transplantation, exerting profibrotic effects. In contrast, cyclosporine (CsA) had been shown to decrease fibroblast activation and collagen production. We therefore investigated the effects of CsA on TGF-ß and IL-4 profibrotic activities on HIF in vitro. METHODS: Isolated HIF were cultured without or with human TGF-ß, human IL-4, CsA, or combined TGF- ß+CsA or IL-4+CsA. We performed real-time polymerase chain reaction for collagen types I, III, and IV and alpha-SMA, a marker of fibroblast activation we also measured total collagen in supernates. TGF-ß and IL-4 increased the expressions of alpha smooth muscle action (SMA) collagen I, III, and IV mRNAs (P < .05 vs untreated cells) as well as the overall collagen level in the supernates (P < .01). CsA decreased the expression of mRNAs encoding alpha-SMA and collagens (P < .01). Expressions of alpha-SMA and collagens I, III, and IV mRNAs were significantly lower under combined treatments (TGF-ß vs TGF-ß+CsA [P < .01] and IL-4 vs IL-4+CsA [P < .01]). Collagen level was decreased by combined treatments (TGF-ß vs TGF-ß+CsA [P < .05] and IL-4 vs IL-4+CsA [P = .05]). CONCLUSION: CsA inhibited the profibrotic effects of TGF-ß and IL-4 by decreasing the activation and production of collagen by HIF. CsA may decrease fibroblast activation and collagen accumulation, exerting beneficial effects on fibrosis progression, particularly among patients with recurrent hepatitis C.

Increased expression of regulatory Tr1 cells in recurrent hepatitis C after liver transplantation.

Immune response failure during HCV infection has been associated with the activity of regulatory T cells. Hepatitis C-related cirrhosis is the main reason for liver transplantation. However, 80% of transplanted patients present an accelerated recurrence of the disease. This study assessed the involvement of regulatory T-cell subsets (CD4+CD25+ cells: 'Treg' and CD49b+CD18+ cells: 'T regulatory-1' cells), in the recurrence of HCV after liver transplantation, using transcriptomic analysis, ELISA assays on serum samples and immunohistochemistry on liver biopsies from liver recipients 1 and 5 years after transplantation. Three groups of patients were included: stable HCV-negative recipients and those with mild and severe hepatitis C recurrence. At 5 years, Treg markers were overexpressed in all HCV+ recipients. By contrast, Tr1 markers were only overexpressed in patients with severe recurrence. At 1 year, a trend toward the overexpression of Tr1 was noted in patients evolving toward severe recurrence. IL-10 production, a characteristic of the Tr1 subset, was enhanced in severe recurrence at both 1 and 5 years. These results suggest that Tr1 are enhanced during severe HCV recurrence after liver transplantation and could be predictive of HCV recurrence. High levels of IL-10 at 1 year could be predictive of severe recurrence, and high IL-10 producers might warrant more intensive management.

Cadmium induces mitochondria-dependent apoptosis of normal human hepatocytes.

The heavy metal cadmium, an environmental pollutant, has been widely demonstrated to be toxic, in particular for liver. In murines, cadmium induces apoptosis of hepatocytes and hepatomas. In human cells, apoptosis induced by cadmium has been exclusively demonstrated in tumoral cell lines. Nothing was known in normal liver, in vitro or in vivo. In the present study, we examined the effects of cadmium in nonmalignant human hepatocytes. For that purpose, we investigated whether cadmium was able to induce apoptosis of normal human hepatocytes (NHH) in primary culture and of a SV40-immortalized human hepatocyte (IHH) cell line. Treatment of IHH and NHH with cadmium induced the presence of a sub-G(1) population at 10 and 100 micromol/L, respectively. DAPI staining of both cell types treated with cadmium 100 micromol/L revealed the induction of nuclear apoptotic bodies, supporting the hypothesis of apoptosis. In IHH and NHH, cadmium 100 micromol/L induced PARP cleavage into a 85 kDa fragment. In order to investigate the involvement of mitochondria in cadmium-induced apoptosis, we measured the mitochondrial membrane potential (Delta(Psim)). We observed that in IHH and NHH, cadmium 100 micromol/L induced a decrease of Delta(Psim). As expected, cadmium under the same conditions enhanced caspase-9 and caspase-3 activities. In addition, cadmium from 1 to 100 micromol/L induced the expression of p53 and phosphorylation of its Ser15 in IHH and NHH. In conclusion, we showed in this study that human hepatocytes were sensitive to cadmium and apoptosis induced at concentrations suggested in the literature to inhibit p53 DNA-binding and DNA repair.