Single-cell RNA sequencing of lung leukocytes from cystic fibrosis mice after mucosal vaccination reveals differential gene expression in leukocyte subsets and links to dysregulated Th17 responses 4056

Abstract Description Chronic Pseudomonas aeruginosa lung infection poses a significant threat to individuals with cystic fibrosis (CF), yet effective vaccine strategies remain elusive. Our previous work demonstrated that an intranasal (IN) vaccine using the P. aeruginosa protein PopB elicits Th17 cell-dependent protection in wild-type mice. Here, we tested the PopB vaccine in CF mice and hypothesized that CF mice would have dysregulated T cell responses. Homozygous (hom) delF508 CF mice (FVB/N background) and littermate heterozygous (het) controls were immunized IN with PopB mixed with curdlan as adjuvant. Th17 responses were measured by IL-17A secretion from splenocytes 3 weeks after the third immunization. We investigated lung WBC-specific transcriptomic changes in CF mice versus controls using scRNA-seq (10x Genomics) of flow-sorted CD45+ cells from lungs 24 hours post vaccination. CF mice immunized with PopB showed 2-fold lower Th17 responses compared to control mice (P < 0.05 by ANOVA). DEG by scRNA-seq of lung leukocyte subsets from hom CF mice (2502 cells) compared to het controls (5013 cells) were identified in monocytes (38 up/2 down), neutrophils (44 up/15 down), B cells (11 up/0 down), and T cells (29 up/3 down). Genes upregulated in CF monocytes possibly associated with dysregulated Th17 priming included Saa3, Rbm3, Socs3, and Hp (haptoglobin). The imbalance of leukocyte transcripts in the CF lung post immunization may underlie dysregulated Th17 cell priming and low vaccine responsiveness. Topic Categories Vaccines and Immunotherapy (VAC)