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Mitochondria play a key role in the vital functions of the cell, i.e., energy production, metabolism, respiration, generation of reactive oxygen species, cell division and death. Impairment of these mitochondrial functions is associated with emergence of various diseases. Their amounts and membrane potential are important indices of the mitochondrial condition. To assess these parameters, various fluorochrome-labeled probes are used, which are detectable by flow cytometry. The opportunity of using fluorescent mitochondrial dyes, together with labeled monoclonal antibodies, opens up new prospects for studying the metabolic parameters in various immune cells. The aim of the present study was to assess the mitochondrial state in CD4+T lymphocytes by flow cytometry. To search for the differences in mitochondrial indexes, a group of HIV-infected patients receiving antiretroviral therapy (n = 21) and healthy volunteers (n = 23) were compared. Mononuclear cells isolated from peripheral blood were under the study. Using flow cytometry and commercial mitochondria-selective dyes MitoTracker Green and MitoTracker Orange, we determined, respectively, the mitochondrial mass and membrane charge in the total CD4+T lymphocyte pool, as well as in the naive and memory cell subsets. It has been shown that the mitochondrial mass and charge in naive CD4+T lymphocytes are lower than in memory cells, both in HIV-infected and uninfected subjects. Moreover, we have established that the HIV-infected patients have an increased mitochondrial mass in total CD4+T lymphocyte pool and in their memory cell subset, as compared with healthy donors. That increase, however, was not accompanied by the higher membrane charge. Thus, the analysis of mitochondrial mass and membrane potential using flow cytometry and MitoTracker Green/MitoTracker Orange dyes is relatively easy, fast, and informative for preliminary assessment of the mitochondrial state.

Immune nonresponder (INR) HIV-1-infected subjects are characterized by their inability to reconstitute the CD4+ T cell pool after antiretroviral therapy. This is linked to poor clinical outcome. Mechanisms underlying immune reconstitution failure are poorly understood, although, counterintuitively, INRs often have increased frequencies of circulating CD4+ T cells in the cell cycle. While cycling CD4+ T cells from healthy controls and HIV+ patients with restored CD4+ T cell numbers complete cell division in vitro, cycling CD4+ T cells from INRs do not. Here, we show that cells with the phenotype and transcriptional profile of Tregs were enriched among cycling cells in health and in HIV infection. Yet there were diminished frequencies and numbers of Tregs among cycling CD4+ T cells in INRs, and cycling CD4+ T cells from INR subjects displayed transcriptional profiles associated with the impaired development and maintenance of functional Tregs. Flow cytometric assessment of TGF-β activity confirmed the dysfunction of Tregs in INR subjects. Transcriptional profiling and flow cytometry revealed diminished mitochondrial fitness in Tregs among INRs, and cycling Tregs from INRs had low expression of the mitochondrial biogenesis regulators peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1α) and transcription factor A for mitochondria (TFAM). In vitro exposure to IL-15 allowed cells to complete division, restored the expression of PGC1α and TFAM, and regenerated mitochondrial fitness in the cycling Tregs of INRs. Our data suggest that rescuing mitochondrial function could correct the immune dysfunction characteristic of Tregs in HIV-1-infected subjects who fail to restore CD4+ T cells during antiretroviral therapy.

Currently, immune activation is proven to be the basis for the HIV infection pathogenesis and a strong predictor of the disease progression. Among the causes of systemic immune activation the virus and its products, related infectious agents, pro-inflammatory cytokines, and regulatory CD4+ T cells' decrease are considered. Recently microbial translocation (bacterial products yield into the bloodstream as a result of the gastrointestinal tract mucosal barrier integrity damage) became the most popular hypothesis. Previously, we have found an association between immune complexes present in the bloodstream of HIV infected patients and the T cell activation. On this basis, we propose a significantly modified hypothesis of immune activation in HIV infection. It is based on the immune complexes' participation in the immunocompetent cells' activation. Immune complexes are continuously formed in the chronic phase of the infection. Together with TLR-ligands (viral antigens, bacterial products coming from the damaged gut) present in the bloodstream they interact with macrophages. As a result macrophages are transformed into the type II activated forms. These macrophages block IL-12 production and start synthesizing IL-10. High level of this cytokine slows down the development of the full-scale Th1-response. The anti-viral reactions are shifted towards the serogenesis. Newly synthesized antibodies' binding to viral antigens leads to continuous formation of the immune complexes capable of interacting with antigen-presenting cells.

A study of HIV-infected patients coinfected with hepatitis C virus and receiving antiretroviral therapy (ART) but not treated with interferon was performed. Patients were divided into two groups-with standard and inefficient recovery of CD4(+) T cells. It was found that patients with discordant response of CD4(+) T cells to ART showed heavier destructive processes in the liver than the successfully recovered subjects. They had increased levels of ALT and AST. In these patients, the risk of development of liver cirrhosis is greater.

Background & objectives: Under the lymphopenic condition, T-cells divide to maintain their peripheral pool size. Profound chronic lymphopenia in some treated HIV-infected patients, characterized by poor T-cell recovery, might result in intensive homeostatic proliferation and can cause T-cell exhaustion and/or senescence. The present study was undertaken to evaluate the homeostatic proliferation of CD4+ T-cells in treated HIV-infected individuals, and to determine the amount of phenotypically exhausted and senescent CD4 T-lymphocytes. Methods: Thirty seven treated HIV-infected patients with suppressed HIV viral load (350/μl (n=21). T-cell subsets [naïve, central memory (CM), and effector memory (EM)] and proportions of cycling (Ki-67+), senescent (CD57+) and exhausted (PD-1+) T-lymphocytes were assessed using flow cytometry. Results: CD4+ T-cell cycling rate was higher in INRs than in IRs due to more extensive proliferation of CM, 4.7 vs 2.7 per cent (P 0.05)] was more pronounced in the INR group than in the IR group. The frequency of CD4+ Ki-67+ CM T-cells was related to the proportion of CD4+ PD-1+ cells of the same subset, r=0.789 (P

Objectives Chronic hepatitis C virus (HCV) and HIV viral infections are characterized by systemic inflammation. Yet the relative levels, drivers and correlates of inflammation in these settings are not well defined. Methods Seventy-nine HIV-infected patients who had been receiving antiretroviral therapy (ART) for more than 2 years and who had suppressed plasma HIV levels (< 50 HIV-1 RNA copies/mL) were included in the study. Two patient groups, HCV-positive/HIV-positive and HCV-negative/HIV-positive, and a control group comprised of healthy volunteers (n = 20) were examined. Markers of systemic inflammation [interleukin (IL)-6, interferon gamma-induced protein (IP)-10, soluble tumour necrosis factor receptor-I (sTNF-RI) and sTNF-RII], monocyte/macrophage activation [soluble CD163 (sCD163), soluble CD14 and neopterin], intestinal epithelial barrier loss [intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide (LPS)] and coagulation (d-dimers) were analysed. CD4 naive T cells and CD4 recent thymic emigrants (RTEs) were enumerated. Results Plasma levels of IP-10, neopterin and sCD163 were higher in HCV/HIV coinfection than in HIV monoinfection and were positively correlated with indices of hepatic damage [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the AST to platelet ratio index (APRI)]. Levels of I-FABP were comparably increased in HIV monoinfection and HIV/HCV coinfection but LPS concentrations were highest in HCV/HIV coinfection, suggesting impaired hepatic clearance of LPS. Plasma HCV levels were not related to any inflammatory indices except sCD163. In coinfected subjects, a previously recognized relationship of CD4 naive T-cell and RTE counts to hepatocellular injury was defined more mechanistically by an inverse relationship to sCD163. Conclusions Hepatocellular injury in HCV/HIV coinfection is linked to elevated levels of certain inflammatory cytokines and an apparent failure to clear systemically translocated microbial products. A related decrease in CD4 naive T cells and RTEs also merits further exploration.