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The relationship between NK cell counts during primary infection and disease progression or immune restoration after antiretroviral treatment (ART) was explored. We followed 462 individuals with HIV infection and measured their NK, CD4+ T, CD8+ T cell counts and viral loads. Our data showed that individuals with high NK cell counts had much lower viral loads and higher CD4+ T cell counts. NK cell counts during primary infection were negatively correlated with viral set-point and viral loads at one-year-infection point, and positively correlated with CD4+ T cell counts at one-year-infection and one-year-ART point. Moreover, the NK cell counts during primary infection can predict HIV disease progression and immune restoration after ART. In conclusion, NK cell counts during primary infection represents a potential predictive biomarker to predict HIV disease prognosis in the clinic.

The profound deficiency of Th17 cells contributes to HIV disease progression. The mechanisms of their perturbation remain unclear. Recently, CCR6+CD95+CD4+ naive T cells (CCR6+CD95+CD4+ TNA), identified as pre-committed Th17 precursors, were recognized as a subpopulation of CD4+ T cells with stem cell properties. Following phenotypical identification, we evaluated their level in patients during chronic HIV infection and following antiretroviral therapy (ART) using flow cytometry. The levels of CCR6+CD95+CD4+ TNA were decreased during chronic HIV infection and correlated with CD4+ T cell counts. Immunological responders harbored higher frequency of CCR6+CD95+CD4+ TNA, which was associated with CD4/CD8 T cell ratio. Immunological non-responders with lower frequency of CCR6+CD95+CD4+ TNA failed to exhibit a correlation between CCR6+CD95+CD4+ TNA and CCR6+CD95+CD4+ TCM, and displayed elevated ratio of CCR6+CD95+CD4+ TCM/TNA. The number of CCR6+CD95+CD4+ TNA was increased following early ART. These findings shed light on the importance of targeting pre-committed Th17 precursors that enhance immune reconstitution.

Summary HIV-1 infects blood CD4 T cells through the use of CD4 and CXCR4 or CCR5 receptors, which can be targeted through blocking viral binding to CD4/CXCR4/CCR5 or virus-cell fusion. Here we describe a novel mechanism by which HIV-1 nuclear entry can also be blocked through targeting a non-entry receptor, CD2. Cluster of differentiation 2 (CD2) is an adhesion molecule highly expressed on human blood CD4, particularly, memory CD4 T cells. We found that CD2 ligation with its cell-free ligand LFA-3 or anti-CD2 antibodies rendered blood resting CD4 T cells highly resistant to HIV-1 infection. We further demonstrate that mechanistically, CD2 binding initiates competitive signaling leading to cofilin activation and localized actin polymerization around CD2, which spatially inhibits HIV-1-initiated local actin polymerization needed for viral nuclear migration. Our study identifies CD2 as a novel target to block HIV-1 infection of blood resting T cells., Graphical abstract, Highlights • CD2 is highly expressed on human blood CD4 T cells, particularly memory T cells • Prestimulation of CD2 rendered resting T cells highly resistant to HIV infection • CD2 signaling activates cofilin and actin polymerization blocking HIV nuclear entry • CD2 may serve as a novel target to inhibit HIV-1 infection of blood resting T cells, Immune response; Immunology; Virology

Summary Although peripheral B cell dysfunction in early HIV infection is established, how B cell subsets are altered by HIV infection is poorly understood. While investigating B cell subsets among individuals recently infected with HIV, we observe an accumulation of CD27−CD38+ B cells and find that these cells can directly facilitate HIV infection of primary CD4+ T cells in vitro. Comprehensive analyses of the phenotype, function, and transcriptome of the CD27−CD38+ B cell subset is conducted compared with memory and naive B cells. We find that the CD27−CD38+ B cells exhibit a transitional B cell phenotype and an extremely high turnover rate. Importantly, individuals with higher proportions of CD27−CD38+ B cells during early HIV infection tend to become rapid progressors in the chronic infection stage. In this study, we identify a peripheral transitional B cell subset that accumulates during early HIV infection and may contribute to disease progression.

Introduction IL-21 enhances T and natural killer cells survival and antiviral functions without promoting T cell activation during HIV infection, which makes it a better adjuvant in anti-HIV immunotherapy. Due to the pleiotropy and redundancy of cytokines, it is vital to have a comprehensive knowledge of the role of IL-21 in the regulation of immune responses. Regulatory T cells (Tregs) play an important role in immune regulation and are a determinant of immune therapeutic efficacy in certain circumstances. In this study, we explored the direct effect of IL-21 on Tregs during HIV infection, which has not been addressed before. Methods Thirty-four HIV treatment-naive patients were enrolled and the relationship between CD4 + IL-21 + T cells and Tregs were studied. The effects of IL-21 on CD4 + CD25 + CD127 low Tregs’ apoptosis, proliferation, and CTLA-4 and TGF-β expression in HIV-infected patients was investigated and compared with the effect of other common γ-chain cytokines. Results We found the percentage and absolute numbers of CD4 + IL-21 + T cells were positively related to the frequency or absolute numbers of CD4 + CD25 + or CD4 + CD25 + CD127 low Tregs. Compared with the media-alone control, IL-21, IL-7, and IL-15 could significantly reduce apoptosis of Tregs (p In vitro experiment showed that pretreatment with IL-21 significantly enhanced the suppressive effect of Tregs on CD8+ T cells’ IFN-γ expression. Conclusion We conclude that IL-21 promotes the survival and CTLA-4 expression of Tregs and enhanced the suppressive capacity of Tregs during HIV infection. These results broaden the understanding of HIV pathogenesis and provide critical information for HIV interventions.

Background HIV rapid progressors (RPs) present with a rapid decline of CD4+ T cells within a few years of infection. Determining the underlying mechanisms throughout this decline is important to identify prognostic biomarkers and intervention strategies. Determining the numbers of CD4+ and CD8+ T cells is essential for monitoring the immune status of HIV infected patients. There are additional kinds of cell subtypes in T cells, but their relationship to the rapid progression of HIV disease is not well defined. Methods Nineteen RPs and twenty-one chronic progressors (CPs) were enrolled in this study. Based on the intensity of CD4 and CD8 expression, different T cell subtypes were identified, including CD4+CD8+T cells, CD4−CD8− T cells, CD4+CD8low T cells and CD4−CD8low T cells. Alterations in these T cell subtypes in early HIV infection (within 120 days of infection) between RPs and CPs were measured, and the relationships between these subtypes and HIV disease progression were investigated. In addition, expression of IFN-γ in T cell subtypes after PMA stimulation was analyzed by flow cytometry. Results We found that during early HIV infection, CD4+CD8low T cells both significantly decreased in numbers and percentages in RPs compared to CPs. Furthermore, baseline CD4+CD8low T cells positively correlated not only with baseline CD4+T cells but also with CD4+T cells 12 months after infection. Moreover, survival analysis indicated that low levels of baseline CD4+CD8low T cells significantly accelerated the decline in CD4+ T cells as well as increased viral loads. CD4+CD8low T cells secreted significantly more IFN-γ after PMA stimulation compared to CD4+CD8−T cells and CD4−CD8+T cells, which may be beneficial for the prevention of disease progression. Conclusions Our results identified that in early stage HIV-1 infection, a subtype of T cells, CD4+CD8low, are associated with subsequent disease progression.