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The emergence of SARS-CoV-2 variants will change the landscape of what we already know about COVID-19, making it important to understand the immunological and molecular mechanism of this illness. The virulent nature of the virus, disease outcomes and lack of suitable facilities for studying virus-infected samples has made the need for small animal models urgent. Staphylococcus enterotoxin B (SEB)-induced Acute Respiratory Distress Syndrome (ARDS) mimics the cytokine storm presented in patients with severe COVID-19 and is a safer alternative than working with infected samples. To identify pathways in pulmonary cells that potentially cause ARDS, we utilized single-cell RNA sequencing (scRNASeq) to profile the whole lung cells of C3H/HeJ mice treated with SEB and healthy controls. While it is well established that SEB induces robust proliferation of CD4+ T cells with the receptor Vβ8.2 by binding of these cells with antigen presenting cells, effects in other cell types is not well described. We found that intranasal administration of SEB induced the proliferation of three subsets of macrophages, neutrophils, and cytotoxic T cells in the lungs. Our data also illustrated a loss of multiple cell types including resident macrophages, multiple subsets of B cells, and club cells. Macrophage subsets displayed increased expression of genes related to interferon signaling and lipid metabolism. This data emphasizes the importance of understanding the role of macrophages in ARDS, and can further provide insights into elucidating the mechanisms not only in SEB-induced ARDS but also in severe COVID-19. This may serve as a model for severe case of the disease. (Supported by NIH P01AT003961, P20GM103641, R01AI129788, R01 ES030144 and R01AI123947)

Over thirty percent of individuals infected with human immunodeficiency virus type 1 (HIV) worldwide suffer from HIV-associated neurocognitive disorder (HAND). GFAP-gp120 transgenic (Tg) mice serve as an excellent model system for HAND because they manifest the same neuropathological attributes observed in the brains of AIDS patients. In this study, we sought to identify novel genes associated with the GFAP-gp120 neurodegenerative mouse model. Von Frey filament and hot plate tests on 8 month old GFAP-gp120 mice resulted in a significant increase in mechanical and thermal nociception in Tg versus wild-type mice. Neuropathology was confirmed via immunohistochemistry of MAP2, Synaptophysin, Iba-1, and GFAP. The MAP2 and Synaptophysin allowed us to visualize dendritic density and synaptic loss. Infiltration of macrophages was observed with anti-Iba-1 and astrocytosis with anti-GFAP Abs. Additionally, single cell RNA sequencing (scRNASeq) of encephalitogenic mononuclear cells illustrated 10 distinct clusters of cells. These clusters included: astrocytes, neurons, oligodendrocytes, endothelial cells, microglia, and macrophages. Differential expression analysis showed decreased expression of GM42031 in Tg macrophages and microglia. This locus is currently unclassified and thought to be either a long non coding RNA (lncRNA) or a gene for a NYNRIN-like protein. Until now, this particular RNA has not been associated with the GFAP-gp120 disease model. However, there has been some association of GM42031 with macrophage regulation in Parkinson’s disease and colitis models. Together our study provides novel insights into the immunopathology of HAND that may form the basis for development of effective therapeutics.