Augmentation of lymphoid tissues in the human immune system mouse to advance host directed therapies for HIV

The study of HIV infection and pathogenicity in physical reservoirs requires a biologically relevant model which resembles the human immune system and physiology. The human immune system (HIS) mouse is well established as a model of HIV, but defects in immune tissue reconstitution remain a challenge for examining pathology in tissues. Herein we show that exogenous injection of the human cytokine FLT-3L into the HSC cord blood HIS mouse model significantly expanded the total area of axial lymph nodes and the circulating percentage of human T cells, thus enabling us to visualize and quantify HIV infectivity in the secondary lymphoid tissues of the spleen and axial node. Further, we detected cell death and T cell depletion in tissues, consistent with HIV pathogenesis. Treatment with the caspase-1 inhibitor VX-765 significantly decreased viral load as measured by gag qPCR, and apoptosis as measured by TUNEL assay, in the spleen. A significant restoration of CD4+ T cells in the spleen due to VX-765 treatment was observed via flow cytometry. In situ hybridization further demonstrated a significant decrease in viral RNA in both the spleen and axial lymph nodes. Transcriptomic analysis further revealed an upregulation in host HIV restriction factors such as APOBR, SAMHD1 and APOBEC3A as a result of VX-765 administration. These findings demonstrate FLT-3L as a mechanism whereby the human immune environment in HIS mice can be enhanced to support investigations of HIV pathogenesis and immune outcomes in tissue compartments. Preliminary results indicate that targeting inflammasome pathways with VX-765 in HIS mice treated with FLT-3L, and infected with HIV, preserved T cell populations and decreased viral load. Supported by R01 A1HL129881, NIH/NHLBI