Apoptosis of peripheral blood cytotoxic T lymphocytes in chronic hepatitis C virus infection: relation to disease severity and response to therapy

More than 80% of HCV-infected individuals develop chronic disease, which can progress to liver cirrhosis and hepatocellular carcinoma. T cell-mediated protection against HCV depends on constantly activated effector CD8+ T cells that control emergence, spread and expansion of the virus. Why these cells fail to contain HCV replication in 70-80% of the individuals who develop persistent viremia is not clear. Fas receptors [APO-1 or CD95] and the Fas ligand system [Fas/FasL] have been implicated in the induction of apoptosis which is related with the pathogenesis of hepatitis C. Was to assess the expression of CD95 [Fas/APO-1] [as an apoptotic marker] on peripheral blood cytotoxic T lymphocytes from patients with chronic HCV infection and to correlate this with disease severity in the liver, response to antiviral therapy and extrahepatic autoimmune manifestations. Thirty patients with evidence of chronic HCV infection and 10 healthy age and sex matched volunteers with negative HCV antibodies sera serving as controls were enrolled into the present study. Our patients were classified into two main groups according to antiviral therapy, Group A: They were 17 patients not receiving treatment and Group B: They were 13 patients who received antiviral therapy for 24 weeks. Group A patients were further subdivided according to the presence or absence of extrahepatic manifestations into two groups: Group I: They were 11 patients not receiving therapy and had no extrahepatic manifestations. Group II: They were 6 patients not receiving therapy and had extrahepatic manifestations. Group I patients were also subdivided according to the necroinflammatory score in liver biopsy into three groups with: Mild, moderate and severe disease activity. They were also subdivided as regard fibrosis stage in liver biopsy into groups with: Moderate and severe fibrosis. Group B patients were further subdivided according to their response to antiviral therapy into: Group III: 6 patients received therapy and were non responders and Group IV: 7 patients received therapy and showed good response. After detailed history taking and thorough clinical examination, the following investigations were done: CBC, AST and ALT, serum cryoglobulins [for patients with extrahepatic disease] and flowcytometric estimation of the percentage of apoptotic peripheral blood cytotoxic T lymphocytes [CD8+CD95+] and non apoptotic cytotoxic T lymphocytes [CD8+ CD95-]. Current liver biopsy was performed in patients of Group I and examined histopathologically. There was highly statistically significant difference between HCV patients and controls as regard ALT, percentage of apoptotic cytotoxic T lymphocytes [CD8+ CD95+] and non apoptotic cytotoxic T lymphocytes [CD8+ CD95-] [p<0.001]. There was statistically significant difference between patients of Group I, II, III, IV and controls in percentage of CD8+CD95+ and CD8+CD95- cells. Comparison between Group I and II revealed non significant difference in percentage of CD8+CD95+ and CD8+CD95- cells or in percentage of CD8-CD95+ cells [apoptotic non cytotoxic T] [p>0.05]. Comparison between Group III and IV revealed statistically significant difference in percentage of CD8+CD95+ and CD8+CD95- cells [p<0.05]. In Group I the percentage of CD8+CD95+ tended to correlate with activity index of liver biopsy but significantly correlated with serum ALT in Group III. In Group II significant positive correlation between percentage of CD8+CD95+ and AST with tendency toward correlation with ALT was found. Also percentage of CD8+CD95+ correlated with purpura and arthritis but not with cryoglobulinemia. Percentage of CD8+CD95+ showed non statistically significant correlation except with serum prothrombin time in group IV. There was increase in the percentage of CD8+CD95+ cells in higher grade of necroin-flamatory activity and in higher stage of fibrosis in liver biopsy in group I. Our findings support the suggestion of major role of peripheral blood CD8+ T cells in elimination of HCV and suggest that cellular immune response plays a key role not only in viral elimination, but also in liver pathology associated with HCV-infection. Monitoring apoptosis of CD8+ T cells by measuring FAS expression is useful in follow-up of antiviral response in these patients. Finally, Fas/FasL pathway is critical in persistent HCV infection in humans and represents a potential target for restoring function of exhausted HCV-specific CTLs

Fas expression on peripheral blood t lymphocytes in systemic lupus erythematosus [SLE]: relation to disease activity and lupus nephritis

Introduction: Systemic lupus erythematosus [SLE] is an autoantigen driven T cell dependent autoimmune disease. Lupus nephritis is one of the most serious complications in SLE, occurring in up to 60% of the patients. SLE patients show increased apoptosis of peripheral blood mononuclear cells [PBMCs], especially T lymphocytes and decreased resistance of activated T cells to apoptosis. Fas, also known as APO-1 or CD95, is a cell surface protein that triggers apoptotic cell death with characteristic cytoplasmic and nuclear condensation and DNA fragmentation. The aim of this work was to evaluate Fas expression [as an apoptotic marker] on peripheral blood T lymphocytes in SLE patients in relation to disease activity and lupus nephritis

Subjects and methods: Thirty-five SLE patients and 15 normal controls were studied. Disease activity was assessed by SLAM score and patients were divided according to: a] disease activity [mildly active group with SLAM score <6, moderately active group from 6-12 and severely active group >12], b] the clinical presentation including the presence or absence of either lung, cardiac, neurological affection or nephritis as well as regard, c] WHO classes of lupus nephritis. Laboratory investigations included CBC, ESR, serum creatinine, urine examination, 24 hours urinary proteins, ANA and Anti-dsDNA, flowcytometric analysis of percentage of Fas expression [CD95+] on peripheral blood T lymphocytes [CD3+] and percutaneous renal biopsy in indicated patients with evidence of nephritis

Results: Percentage of CD3+CD95+ cells from SLE patients was statistically significantly increased compared to healthy controls [p<0.05]. Comparative study among the patients according to SLAM score was statistically significant [p<0.05] using ANOVA test with the highest percentage of apoptotic T lymphocytes in severely active group. When comparing each group with the control one, results showed statistically significant more apoptotic T cells in severely active SLE patients compared with controls. However, although the apoptotic T cells were increased in moderately active SLE patients, the data did not reach statistical significance in comparison with healthy controls nor with the mildly active group [p > 0.05]. Apart from nephritis [p<0.05], Fas expression was not associated with the clinical presentation of the patients, as regard the presence or absence of lung, cardiac or neurological affection [p>0.05]. The percentage of Fas expression was higher in class IIb than either class III or IV as well as patients without nephritis and those with nephritis without indication for renal biopsy [27.32+/-13.62 vs. 19.8, 19.14+/-5.12, 14.8+/-3.57 and 17.2+/-6.8]. However, on comparing only the patients who did renal biopsy, the renal parameters as well as the percentage of CD3+CD95+ cells was statistically non significant [P > 0.05]. Correlation between the percentage of CD3+CD95+ cells and different parameters revealed highly significant positive correlation as regard ESR, current steroid treatment dose and SLAM scoring, [p<0.001], statistically significant positive correlation as regard platelets, nephritis, arthritis, fever, lymphadenopathy and chronicity index in renal biopsy [p < 0.05], and tendency toward urinary albuminuria and casts. [p= 0.061 and 0.056 respectively]

In conclusion: The increased CD3+ CD95+ cells from patients with SLE and its correlation with disease activity suggests that abnormalities of apoptosis may be related to the pathogenesis of the disease [especially with high grades of activity] and its serious complication, nephritis. In patients with nephritis, the lower Fas expression [CD95+] on peripheral blood T lymphocytes [CD3+] in patients with class IV nephritis than those with class IIb nephritis could be possibly explained by the effect of treatment or by the natural process of the proliferative disease itself. However, further studies including large number of SLE patients, evaluating apoptosis both systemically and locally in tissue biopsies and studying various apoptotic pathways are needed to understand its role in the pathogenesis of the disease and its value as a therapeutic target