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Purpose The existence of CD8+cells with pro-inflammatory properties referred to as Tc17 cells has recently been acknowledged. While it is evident that CD4+pro-inflammatory IL-17-producing Th17 cells are important in the regulation of chronic viral infections, the role of Tc17 cells is largely unknown. Tc17 cells are characterized by expression of high levels of CD161 (CD161high). We hypothesized that Tc17 cells are involved in immune regulation in HIV- infection. Methods 67 HIV-infected patients were included in a cross-sectional study. All patients had nadir CD4 counts<200 cells/µL, fully suppressed viral loads, and had been on cART for at least 2 years. Three groups were defined: Immunological Non Responders (INR, CD4 counts<200 cells/µL), Intermediate Responders (IR, CD4 counts 200-500 cells/µL), and Responders (RES, CD4 counts>500 cells/µL). Percentages of CD8+cells expressing CD3+CD8+CD161high were evaluated using flow cytometry. Additionally, Production of IL-17 in phytohaemagglutinin(PHA)-stimulated peripheral blood was determined by Luminex. For statistics Kruskall Wallis test followed by Mann-Whitney U test was used. Data are given as medians. Summary of results INR had lower levels of Tc17 cells compared to IR, RES and controls (0.4%, 1.0%, 2.1%, 6.1%, p values<0.05). All HIV-infected patients had lower levels than controls (p values<0.0001). Furthermore, all HIV-infected patients displayed lower production of IL-17 in peripheral blood compared to controls (p values<0.001). [ABSTRACT FROM AUTHOR]

The aim of this study was to examine regulatory T cells (Tregs) in peripheral blood and liver tissue in patients with chronic hepatitis C virus (HCV) mono-infection and in patients with HIV/HCV co-infection. In a cross-sectional study were included 51 patients with chronic HCV infection, 24 patients with HIV/HCV co-infection and 24 healthy individuals. CD4+ and CD8+ Tregs were determined using flow cytometry. Fibrosis was examined by transient elastography. Inflammation, fibrosis and Tregs were determined in liver biopsies from 12 patients. Increased frequency of CD4+ and CD8+ Tregs was found in HIV/HCV co-infected patients [median: 6.4% (IQR: 5.7-6.9) and 1.0% (0.7-1.2), respectively] compared to HCV mono-infected patients [5.6% (4.2-6.3), P = 0.01 and 0.5% (0.3-0.7), P < 0.001, respectively]. Furthermore, HCV mono-infected patients had increased frequencies of Tregs compared with healthy controls ( P < 0.05). However, no associations between the frequency of Tregs and fibrosis were found. Furthermore, characterization of CD4+ Tregs using CD45RA demonstrated a higher frequency of activated Tregs in both HCV mono-infected and HIV/HCV co-infected patients compared with healthy controls. Finally, number of intrahepatic Tregs was associated with both peripheral CD8+ Tregs and intrahepatic inflammation. In conclusion, HCV mono-infected patients and particularly HIV/HCV co-infected patients have increased the frequency of CD4+ and CD8+ Tregs compared with healthy controls. Furthermore, CD4+ Tregs in infected patients displayed an active phenotype. Tregs were not associated with fibrosis, but a positive correlation between intrahepatic Tregs and inflammation was found. Taken together, these results suggest a role for Tregs in the pathogenesis of chronic HCV infection. [ABSTRACT FROM AUTHOR]