Antiretroviral therapy (ART) during the earliest stage of acute HIV infection (Fiebig I) might minimize establishment of a latent HIV reservoir and thereby facilitate viremic control after analytical treatment interruption (ATI). We show that 8 participants, who initiated treatment during Fiebig I and were treated for a median of 2.8 years, all experienced rapid viral load rebound following ATI, indicating that additional strategies are required to control or eradicate HIV.

CD8+ T cells play a critical role in controlling HIV viremia and could be important in reducing HIV-infected cells in approaches to eradicate HIV. The SIV model provided the proof of concept for a CD8+ T cell-mediated reservoir clearance but showed conflicting evidences on the role of these cells to eliminate HIV-infected cells. In humans, HIV-specific CD8+ T cell responses have not been associated with a reduction of the HIV-infected cell pool in vivo. Here we studied HIV-specific CD8+ T cells in the RV254 cohort of individuals initiating ART in the earliest stages of acute HIV infection (AHI). We showed that the HIV-specific CD8+ T cells generated as early as AHI stage 1 and 2 prior to peak viremia are delayed in expanding and acquiring effector functions but are endowed with higher memory potential. In contrast, the fully differentiated HIV-specific CD8+ T cells at peak viremia in AHI stage 3 were more prone to apoptosis but were associated with a steeper viral load decrease after ART initiation. Importantly, their capacity to persist in vivo after ART initiation correlated with a lower HIV DNA reservoir. These findings demonstrate that HIV-specific CD8+ T cell magnitude and differentiation are delayed in the earliest stages of infection. These results also demonstrate that potent HIV-specific CD8+ T cells contribute to reducing the pool of HIV-producing cells and the HIV reservoir seeding in vivo and provide the rationale to design of interventions aiming at inducing these potent responses to cure HIV infection.

Despite the overwhelming benefits of antiretroviral therapy (ART) in curtailing viral load in HIV infected individuals, ART does not fully restore cellular and humoral immunity. HIV infected individuals under ART show reduced responses to vaccination and infections and are unable to mount an effective anti-viral immune response upon ART cessation. There are many factors that contribute to these defects including persistent inflammation, especially in lymphoid tissues, where T follicular helper (Tfh) cells instruct and help B cells launch an effective humoral immune response. In this study we investigated the phenotype and function of circulating memory Tfh cells as a surrogate of Tfh cells in lymph nodes and found significant impairment of this cell population in chronically HIV infected individuals leading to reduced B cell responses. We further show that these aberrant memory Tfh cells exhibit an IL-2 responsive gene signature and are more polarized towards a Th1 phenotype. Treatment of functional memory Tfh cells with IL-2 was able to recapitulate the detrimental reprogramming. Importantly, this defect was reversible, as interfering with the IL-2 signaling pathway helped reverse the abnormal differentiation and improved antibody responses. Thus, reversible reprogramming of memory Tfh cells in HIV infected individuals could be utilized to enhance antibody responses. Altered microenvironmental conditions in lymphoid tissues leading to altered Tfh cell differentiation could provide one explanation for the poor responsiveness of HIV infected individuals to new antigens. This has important implications for the development of therapeutic interventions to enhance HIV- and vaccine-mediated antibody responses in patients under ART.

IL-17 is rapidly produced during lung injury and significantly contributes to early immunopathogenesis. This is orchestrated largely by a distinct population of pILC3s. Modulation of the activity of pILC3s may potentiate early control of the inflammatory dysregulation seen in ARDS, opening up new therapeutic targets.

Acute respiratory distress syndrome (ARDS) is a devastating disorder characterized by increased alveolar permeability with no effective treatment beyond supportive care. Current mechanisms underlying ARDS focus on alveolar endothelial and epithelial injury caused by products of innate immune cells and platelets. However, the role of adaptive immune cells in ARDS remains largely unknown. Here we report that expansion of antigen-specific αβT helper 17 (αβTH17) cells contribute to ARDS by local secretion of IL-17A, which in turn directly increases alveolar epithelial permeability. Mice with a highly restrictive defect in antigen-specific αβTH17 cells were protected from experimental ARDS induced by a single dose of endotracheal lipopolysaccharide (LPS). Loss of IL-17 receptor C or antibody blockade of IL-17A was similarly protective, further suggesting that IL-17A released by these cells was responsible for this effect. LPS induced a rapid and specific clonal expansion of αβTH17 cells in the lung, as determined by deep sequencing of the hypervariable CD3RβVJ region of the T cell receptor. Our findings could be relevant to ARDS in humans, since we found significant elevation of IL-17A in bronchoalveolar lavage (BAL) fluid from patients with ARDS and recombinant IL-17A directly increased permeability across cultured human alveolar epithelial monolayers. These results reveal a previously unexpected role for adaptive immune responses that increase alveolar permeability in ARDS and suggest that αβTH17 cells and IL-17A could be novel therapeutic targets for this currently untreatable disease.