B107-17 High Exacerbators in Cystic Fibrosis Have Sex-Specific Monocyte Transcriptomes

Abstract Rationale People with Cystic Fibrosis (CF) often experience acute clinical deteriorations known as pulmonary exacerbations (PEx). PEx can be associated with increased airway inflammation, leading to lung function decline and mortality. Untreated females with CF experience more frequent and severe PEx than their male counterparts, suggesting sex-specific pathogenesis. Using single-cell RNA sequencing (scRNAseq), we previously identified CF-specific impairments in host defense and proinflammatory gene expression in immature airway monocytes. Prior analysis demonstrated sex-specific pulmonary neutrophil transcripts in people with CF who had frequent vs. infrequent PExs. Here, we sought to determine if there are sex-specific transcripts in monocytes of patients with CF who experience frequent vs. infrequent exacerbations. Methods We conducted a cross-sectional study of 31 sputum samples collected from untreated adults with CF at the Yale Adult CF Program (13 male M, 18 female F) over the course of 2 years. Following sputum induction, we generated cDNA libraries from single cells following our previously established scRNAseq protocols. Sequencing was completed at the Yale Genomics and Bioinformatics Core. We defined four analysis groups based on sex (M, F) and the frequency of patient exacerbations per year, characterized as two or more per year (high exacerbators, HE) or less than two per year (low exacerbators, LE). We compared differentially expressed genes (DEG) by group while adjusting for a false discovery rate (FDR) of 0.05 using a standardized pipeline with the R package Seurat 5.1.0. Results Volcano plots were used to visualize gene expression differences in monocytes between HE and LE groups for both males and females. HE females displayed increased expression of the proinflammatory genes CCL20, HIF1A, and RHOA (FC 3.2, p 10-16), however multiple proinflammatory genes were downregulated (CXCL9, ALCAM, CCL3, FC -0.54, p 10-5), suggesting a dysfunctional inflammatory transcriptional program. HE males demonstrated increased expression of several proinflammatory genes (e.g., CXCL10, CCL2, CCL4L2, FC1.6, p 0.001), which are distinct from the upregulated proinflammatory genes in HE females (Figure 1). Conclusion These findings suggest that sex- and cell-specific transcriptional abnormalities are associated with PEx frequency in patients with CF and contribute to sexually dimorphic clinical presentations. These subgroup-specific DEGs show promise for the development of personalized therapeutic approaches to reduce PEx frequency and narrow the sex gap in sexually dimorphic features of CF. This abstract is funded by: CFF, NIH