High frequencies of PMN-MDSCs are associated with low suppressive capacity in advanced stages of HIV-1 infection

Background Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are an immature cell type that inhibits the effector functions of T lymphocytes in chronic HIV infection. A well-known immunological feature of the disease course is the development of immune exhaustion, which is correlated with excessive immune activation in late-stage disease. Here, we hypothesized that immune exhaustion would also affect PMN-MDSCs in late-stage HIV-1 infection. Methods We evaluated untreated chronically HIV-infected patients (progressors, n = 10) and control groups (controllers, patients with non-small cell lung carcinoma and healthy controls, n = 16) with regard to levels of PMN-MDSCs and their inhibitory potential. Additionally, we studied CD8 T cell effector functions (interferon-gamma, TNF alpha, IL-2 and CD107) and parameters of CD8 T cell activation (CD38 and HLA-DR) and exhaustion (PD-1 and LAG-3) by flow cytometry. Plasma inflammation markers analyzed here were IL-6, IL-8, soluble CD14, highly sensitive CRP, and cystatin C. Results Coincubation experiments with isolated PMN-MDSCs led to a significant inhibition of CD8 T cell proliferation (p < 0.0001), with a significant correlation between PMN-MDSC frequency and suppressive capacity: the higher the frequency of PMN-MDSCs was, the lower the suppressive capacity (rho = 0.51, p = 0.0082). Stratifying all study subjects into subgroups with PMN-MDSC frequencies above or below 2.5% resulted in a significantly increased suppressive capacity in patients with frequencies below 2.5% (p = 0.021). While there was no correlation with the cellular activation markers CD38 and HLA-DR, high IL-8 levels were significantly associated with high PMN-MDSC frequencies (rho = 0.52, p = 0.0074) and low suppressive capacity (rho = 0.47, p = 0.019). Conclusions In this study, we demonstrate for the first time that PMN-MDSCs show limited effector functions in advanced disease stages of HIV infection. The hyperactive immune state is associated with this loss of function. However, we show an association with the proinflammatory cytokine IL-8, which is an important factor for the migration and adhesion of polymorphonuclear cells

One year after mild COVID-19: the majority of patients maintain specific immunity, but one in four still suffer from long-term symptoms

After COVID-19, some patients develop long-term symptoms. Whether such symptoms correlate with immune responses, and how long immunity persists, is not yet clear. This study focused on mild COVID-19 and investigated correlations of immunity with persistent symptoms and immune longevity. Persistent complications, including headache, concentration difficulties and loss of smell/taste, were reported by 51 of 83 (61%) participants and decreased over time to 28% one year after COVID-19. Specific IgA and IgG antibodies were detectable in 78% and 66% of participants, respectively, at a 12-month follow-up. Median antibody levels decreased by approximately 50% within the first 6 months but remained stable up to 12 months. Neutralizing antibodies could be found in 50% of participants; specific INFgamma-producing T-cells were present in two thirds one year after COVID-19. Activation-induced marker assays identified specific T-helper cells and central memory T-cells in 80% of participants at a 12-month follow-up. In correlative analyses, older age and a longer duration of the acute phase of COVID-19 were associated with higher humoral and T-cell responses. A weak correlation between long-term loss of taste/smell and low IgA levels was found at early time points. These data indicate a long-lasting immunological memory against SARS-CoV-2 after mild COVID-19

Treatment Intensification in HIV-Infected Patients Is Associated With Reduced Frequencies of Regulatory T Cells

In untreated HIV infection, the efficacy of T cell responses decreases over the disease course, resulting in disease progression. The reasons for this development are not completely understood. However, immunosuppressive cells are supposedly crucially involved. Treatment strategies to avoid the induction of these cells preserve immune functions and are therefore the object of intense research efforts. In this study, we assessed the effect of treatment intensification [=5-drug antiretroviral therapy (ART)] on the development of suppressive cell subsets. The New Era (NE) study recruited patients with primary HIV infection (PHI) or chronically HIV-infected patients with conventional ART (CHI) and applied an intensified 5-drug regimen containing maraviroc and raltegravir for several years. We compared the frequencies of the immune suppressive cells, namely, the myeloid-derived suppressor cells (MDSCs), regulatory B cells (Bregs), and regulatory T cells (Tregs), of the treatment intensification patients to the control groups, especially to the patients with conventional 3-drug ART, and analyzed the Gag/Nef-specific CD8 T cell responses. There were no differences between PHI and CHI in the NE population (p &gt; 0.11) for any of the studied cell types. Polymorphonuclear myeloid-derived suppressor cell (PMN-MDSC), monocytic myeloid-derived suppressor cell (M-MDSC), and the Breg frequencies were comparable to those of patients with a 3-drug ART. However, the Treg levels were significantly lower in the NE patients than those in 3ART-treated individuals and other control groups (p ≤ 0.0033). The Gag/Nef-specific CD8 T cell response was broader (p = 0.0134) with a higher magnitude (p = 0.026) in the NE population than that in the patients with conventional ART. However, we did not find a correlation between the frequency of the immune suppressive cells and the interferon-gamma+ CD8 T cell response. In the treatment intensification subjects, the frequencies of the immune suppressive cells were comparable or lower than those of the conventional ART-treated subjects, with surprisingly broad HIV-specific CD8 T cell responses, suggesting a preservation of immune function with the applied treatment regimen. Interestingly, these effects were seen in both treatment intensification subpopulations and were not attributed to the start of treatment in primary infection