IGSF3 (immunoglobulin superfamily 3) and glycosphingolipids associated with lung cell proliferation during recovery from respiratory SARS-CoV-2 infection

RATIONALE: IGSF3, a transmembrane tetraspanin interacting protein, is required for lung epithelial scratch wound repair and migration via inhibition of glucosyl ceramide synthase. However, as a result, a decrease in glycosphingolipids such as lactosylceramide may decrease cell proliferation and impair lung recovery from infections such as SARS-CoV-2 (CoV2). We hypothesized that recovery from CoV2 is associated with downregulation of lung IGSF3, increased glycosphingolipid synthesis, and enhanced lung cell proliferation. METHODS: Lung IGSF3, sphingolipid levels, and cell proliferation were measured in Golden Syrian hamsters harvested during the early recovery (at 7 days) following a single intranasal exposure to CoV2 (strain WA01; 10E4 pfu). Lung cell proliferation was measured in mice with constitutive deletion of IGSF3 (KO). Immunofluorescence (IF) was performed for cell-specific markers CD11b and CD11c, as well as CD31. Lipids were quantified using LC-MS/MS. RESULTS: CoV2 infection was associated with decreased Igsf3 [log2FC (fold change) -0.914; p<0.01] expression and immunostaining in the lung tissue and increased glucosylceramide (FC 11, p<0.001), lactosylceramide (FC 5, p<0.01), and lysophosphatidic acid (FC 6, p<0.001) in the BALF. Lung cell proliferation was increased, with high Proliferation Marker Protein Ki-67 expression (Ki-67; log2FC 2.17; p<0.0001). In mice, compared to control, IGSF3 KO mice exhibited increased lung Proliferating Cell Nuclear Antigen (PCNA; FC 2.44; p=0.03) and Ki-67 (FC 1.71; p=0.03) IF and enhanced EdU incorporation (in female mice only, FC 1.9; p=0.007), predominantly in the lung epithelium. Of the Ki-67+ cells in the IGSF3 KO lung parenchyma, the populations of cells that had higher proliferation rates than in control mice were alveolar epithelial (>70% of all proliferating cells) followed by recruited monocytes/macrophages, and vascular cells. CONCLUSIONS: Inhibition of IGSF3 may accelerate lung epithelial cell proliferation and lung repair during recovery from respiratory viral infections such as with CoV2 by a mechanism that may involve enhanced glycosphingolipid production. DOD W81XWH-21-PRMRP-IIRA, ALA ETRA736704 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.