T lymphocytes from patients with primary biliary cirrhosis produce reduced amounts of lymphotoxin, tumor necrosis factor and interferon-gamma upon mitogen stimulation

Primary biliary cirrhosis (PBC) is considered an autoimmune disease characterized by destruction of small intrahepatic bile ducts by lymphocytes. Altered functions of these lymphocytes might reflect an abnormal immune response leading to tissue damage. We investigated lymphokine secretion by mitogen-stimulated T lymphocytes from the liver biopsies of patients with PBC and for comparison also peripheral blood. In PBC, diminished synthesis of lymphotoxin (TNFP), tumor necrosis factor (TNFa) and interferon-y (IFIVy) was found both in T-cell lines from liver tissue and in peripheral blood. The reduction was most prominent for TNFP in early histological stages of PBC, and appeared to be a stable phenomenon when T cells were tested after long-term tissue culture. Analysis of mRNA levels indicates a possible link between reduced TNFP production and a defect in interleukin-2 transcription. The data suggest that diminished lymphokine production in patients with PBC may play ;In important role in the immanopathogenesis of this disease

Tracking Virus-Specific CD4+ T Cells during and after Acute Hepatitis C Virus Infection

CD4+ T cell help is critical in maintaining antiviral immune responses and such help has been shown to be sustained in acute resolving hepatitis C. In contrast, in evolving chronic hepatitis C CD4+ T cell helper responses appear to be absent or short-lived, using functional assays. Here we used a novel HLA-DR1 tetramer containing a highly targeted CD4+ T cell epitope from the hepatitis C virus non-structural protein 4 to track number and phenotype of hepatitis C virus specific CD4+ T cells in a cohort of seven HLA-DR1 positive patients with acute hepatitis C in comparison to patients with chronic or resolved hepatitis C. We observed peptide-specific T cells in all seven patients with acute hepatitis C regardless of outcome at frequencies up to 0.65% of CD4+ T cells. Among patients who transiently controlled virus replication we observed loss of function, and/or physical deletion of tetramer+ CD4+ T cells before viral recrudescence. In some patients with chronic hepatitis C very low numbers of tetramer+ cells were detectable in peripheral blood, compared to robust responses detected in spontaneous resolvers. Importantly we did not observe escape mutations in this key CD4+ T cell epitope in patients with evolving chronic hepatitis C. During acute hepatitis C a CD4+ T cell response against this epitope is readily induced in most, if not all, HLA-DR1+ patients. This antiviral T cell population becomes functionally impaired or is deleted early in the course of disease in those where viremia persists

Effect of sitagliptin on cardiovascular outcomes in type 2 diabetes

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P = 0.98). There were no significant between-group differences in rates of acute pancreatitis (P = 0.07) or pancreatic cancer (P = 0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events

Analysis of T cell activation pathways in patients with liver cirrhosis, impaired delayed hypersensitivity and other T cell-dependent functions

Patients with cirrhosis of the liver frequently demonstrate anergy in intracutaneous tests and fail to respond to vaccination, suggesting impaired delayed hypersensitivity and other T cell-dependent functions in vivo. T cell activation through the coordinated interaction of different cells of the immune system (B cell, antigen-presenting cells (APC)) is an important step in the induction of cellular and humoral immune responses. Impaired T cell-dependent functions in patients with liver cirrhosis may thus be explained by defective T cell activation. We prospectively investigated T cell activation pathways in 12 patients (nine males, three females) with alcoholic liver cirrhosis (seven Child Pugh stage A and B (CP A+B), five Child Pugh stage C (CP C)) and five healthy controls and compared the in vitro results of T cell activation with data obtained in vivo, e.g. intracutaneous tests and vaccination against hepatitis B surface antigen (HBs-Ag). Five out of eight patients who completed vaccination against hepatitis B virus infection were non-responders; one of the three responders had a non-protective anti-HBs titre. Moreover, three of five patients with alcoholic liver cirrhosis CP A+B, and two out of three with CP C were anergic in intracutaneous tests to a set of diverse antigens. All parameters of T cell activation were normal, including proliferation mediated by CD2, CD3–T cell receptor (TCR) complex, and CD28; acquisition of responsiveness to exogenous IL-2 and IL-4; activation of proteinkinase C (PKC) by phorbol ester and calcium influx by addition of ionomycin. The ability of monocytes to deliver costimulatory signals was preserved in patients with alcoholic cirrhosis. In addition, serum of patients with alcoholic liver disease did not inhibit T cell proliferation. We conclude that, although in patients with alcoholic liver cirrhosis T cell-dependent functions are impaired in vivo, T cell activation pathways are not responsible for the observed immune defect

Minimal T-Cell-Stimulatory Sequences and Spectrum of HLA Restriction of Immunodominant CD4(+) T-Cell Epitopes within Hepatitis C Virus NS3 and NS4 Proteins

The hepatitis C virus (HCV)-specific CD4(+) T-cell response against nonstructural proteins is strongly associated with successful viral clearance during acute hepatitis C. To further develop these observations into peptide-based vaccines and clinical immunomonitoring tools like HLA class II tetramers, a detailed characterization of immunodominant CD4(+) T-cell epitopes is required. We studied peripheral blood mononuclear cells from 20 patients with acute hepatitis C using 83 overlapping 20-mer peptides covering the NS3 helicase and NS4. Eight peptides were recognized by ≥40% of patients, and specific CD4(+) T-cell clones were obtained for seven of these and three additional, subdominant epitopes. Mapping of minimal stimulatory sequences defined epitopes of 8 to 13 amino acids in length, but optimal T-cell stimulation was observed with 10- to 15-mers. While some epitopes were presented by different HLA molecules, others were presented by only a single HLA class II molecule, which has implications for patient selection in clinical trials of peptide-based immunotherapies. In conclusion, using two different approaches we identified and characterized a set of CD4(+) T-cell epitopes in the HCV NS3-NS4 region which are immunodominant in patients achieving transient or persistent viral control. This information allows the construction of a valuable panel of HCV-specific HLA class II tetramers for further study of CD4(+) T-cell responses in chronic hepatitis C. The finding of immunodominant epitopes with very constrained HLA restriction has implications for patient selection in clinical trials of peptide-based immunotherapies