Severe SARS-CoV-2 infections are characterized by lymphopenia, but the mechanisms involved are still elusive. Based on our knowledge of HIV pathophysiology, we hypothesized that SARS-CoV-2 infection-mediated lymphopenia could also be related to T cell apoptosis. By comparing intensive care unit (ICU) and non-ICU COVID-19 patients with age-matched healthy donors, we found a strong positive correlation between plasma levels of soluble FasL (sFasL) and T cell surface expression of Fas/CD95 with the propensity of T cells to die and CD4 T cell counts. Plasma levels of sFasL and T cell death are correlated with CXCL10 which is part of the signature of 4 biomarkers of disease severity (ROC, 0.98). We also found that members of the Bcl-2 family had modulated in the T cells of COVID-19 patients. More importantly, we demonstrated that the pan-caspase inhibitor, Q-VD, prevents T cell death by apoptosis and enhances Th1 transcripts. Altogether, our results are compatible with a model in which T-cell apoptosis accounts for T lymphopenia in individuals with severe COVID-19. Therefore, a strategy aimed at blocking caspase activation could be beneficial for preventing immunodeficiency in COVID-19 patients.

The acute-phase C-reactive protein binds to phosphorylcholine-expressing Neisseria meningitides and increases uptake by human phagocytes.

Persistent immune activation in virologically suppressed HIV-1 patients, which may be the consequence of various factors including microbial translocation, is a major cause of comorbidities. We have previously shown that different profiles of immune activation may be distinguished in virological responders. Here, we tested the hypothesis that a particular profile might be the consequence of microbial translocation. To this aim, we measured 64 soluble and cell surface markers of inflammation and CD4+ and CD8+ T-cell, B cell, monocyte, NK cell, and endothelial activation in 140 adults under efficient antiretroviral therapy, and classified patients and markers using a double hierarchical clustering analysis. We also measured the plasma levels of the microbial translocation markers bacterial DNA, lipopolysaccharide binding protein (LBP), intestinal-fatty acid binding protein, and soluble CD14. We identified five different immune activation profiles. Patients with an immune activation profile characterized by a high percentage of CD38+CD8+ T-cells and a high level of the endothelial activation marker soluble Thrombomodulin, presented with higher LBP mean (± SEM) concentrations (33.3 ± 1.7 vs. 28.7 ± 0.9 μg/mL, p = 0.025) than patients with other profiles. Our data are consistent with the hypothesis that the immune activation profiles we described are the result of different etiological factors. We propose a model, where particular causes of immune activation, as microbial translocation, drive particular immune activation profiles responsible for particular comorbidities.

Immune activation in HIV-1-infected individuals is reduced under antiretroviral therapies, but persists, resulting in various morbidities. To better characterize this phenomenon, using a panel of 68 soluble and cell surface markers, we measured the level of activation in circulating CD4+ and CD8+ T cells, B cells, monocytes, NK cells, polynuclear and endothelial cells as well as of inflammation and fibrinolysis in 120 virologic responders over 45 years of age. As compared with age- and sex-matched uninfected individuals, we observed a persistence of activation in all the cell subpopulations analyzed, together with marks of inflammation and fibrinolysis. Two independent hierarchical clustering analyses allowed us to identify five clusters of markers that varied concurrently, and five patient groups, each with the same activation profile. The five groups of patients could be characterized by a marker of CD4+ T cell, CD8+ T cell, NK cell, monocyte activation or of inflammation, respectively. One of these profiles was strongly associated with marks of metabolic syndrome, particularly with hyperinsulinemia (OR 12.17 [95% CI 1.79–82.86], p = 0.011). In conclusion, our study unveils biomarkers linked to metabolic syndrome that could be tested as predictive markers, and opens the way to new therapeutic approaches tailored to each patient group.

Key Points• Immunologic and virologic factors are associated with monoclonal gammopathy persistence in HIV-infected patients.• B lymphocytes activation and EBV replication are key features of monoclonal gammopathy.A high prevalence of monoclonal gammopathy (MG) has been observed in HIV-infected patients. We explored the conditions associated with long-term persistence of serum monoclonal protein (M protein) in HIV-infected patients on antiretroviral therapy (ART

Chronic immune activation persists in persons living with HIV-1 even though they are aviremic under antiretroviral therapy, and fuels comorbidities. In previous studies, we have revealed that virologic responders present distinct profiles of immune activation, and that one of these profiles is related to microbial translocation. In the present work, we tested in 140 HIV-1-infected adults under efficient treatment for a mean duration of eight years whether low-level viremia might be another cause of immune activation. We observed that the frequency of viremia between 1 and 20 HIV-1 RNA copies/mL (39.5 ± 24.7% versus 21.1 ± 22.5%, p = 0.033) and transient viremia above 20 HIV-1 RNA copies/mL (15.1 ± 16.9% versus 3.3 ± 7.2%, p = 0.005) over the 2 last years was higher in patients with one profile of immune activation, Profile E, than in the other patients. Profile E, which is different from the profile related to microbial translocation with frequent CD38+ CD8+ T cells, is characterized by a high level of CD4+ T cell (cell surface expression of CD38), monocyte (plasma concentration of soluble CD14), and endothelium (plasma concentration of soluble Endothelial Protein C Receptor) activation, whereas the other profiles presented low CD4:CD8 ratio, elevated proportions of central memory CD8+ T cells or HLA-DR+ CD4+ T cells, respectively. Our data reinforce the hypothesis that various etiological factors shape the form of the immune activation in virologic responders, resulting in specific profiles. Given the type of immune activation of Profile E, a potential causal link between low-level viremia and atherosclerosis should be investigated.

Objectives Behçet disease (BD) is a chronic systemic inflammatory disorder of unknown aetiology. The aim of this study was to determine the orientation of T cell subpopulations in pediatric BD and more precisely to look for a regulatory T lymphocytes (Tregs)/Th17 imbalance. Methods T cell subpopulations were analyzed by flow cytometry in the peripheral blood of pediatric patients with acute (aBD, n = 24), remitting (rBD, n = 12) BD, and in healthy controls (HC, n = 24). Tregs (CD4+CD25hiCD127-/loFoxp3+), activated Tregs (GITR, LAP, CTLA-4, and HLA-DR expression), CD4+ and CD8+ T cells producing interferon-g (Th1 and Tc1) or interleukin (IL)-17 (Th17 and Tc17) under polyclonal (OKT3/IL-2) or antigenic (Streptococcus sanguis KTH-1 peptides and HSP-60) stimulation, were numerated. Results Th17 (1.9 and 5.1 fold) and Tc17 (4.0 and 2.0 fold) frequency under mitogenic stimulation was significantly increased in aBD and rBD patients as compared with HC. Th17 frequency under antigenic stimulation was also higher in patients than in HC. The percentage and number of Tregs and activated Tregs in patients and in HC were similar. However, when Tregs were removed, antigen-driven differentiation into Th1 and Th17 was significantly boosted in BD but not in HC CD4+T cells. Conclusion There is a bias toward a Th17 polarization in acute and remitting BD children. Although we did not observe an increase in the number of Tregs in these patients, their Tregs limit CD4+T cell differentiation into Th1 and Th17 cells. Thus, in pediatric BD, Tregs seem to incompletely counterbalance a Th17 orientation of the helper T cell response.

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