Characterization of Allergic Inflammation Gene Expression Profiles in the Four Core Genotype Mouse Model
Authors: Ekpruke Carolyn , Alford Rachel , Sharma Shikha , Rousselle Dustin , Babayev Maksat , Commodore Sarah , Silveyra Patricia 
Published: May 2023

The mechanisms underlying the differential allergic inflammation phenotype observed in males and females remain unknown, however, both sex hormones and sex-specific genes have been suggested to play a role. This study aimed to identify differentially expressed genes, associated cellular functions, and regulatory pathways in lung tissue from the combination of the Four Core Genotype (FCG) model with a mouse model of allergic inflammation triggered by HDM.For this, FCG adult mice (10 weeks old) of all genotypes (XXM, XXF, XYM, XYF) were challenged intranasally by administering 50 μl of HDM solution (25 μg of HDM extract from two species, Dermatophagoides pteronyssinus, and Dermatophagoides farinae) or vehicle (phosphate-buffered saline, PBS) five times in a week for 5 weeks. At 72hrs after the last exposure, airway hyperreactivity (AHR) was assessed through methacholine challenge (MCh) using the Flexivent rodent ventilator system (SCIREQ), and lung inflammation was determined via Bronchoalveolar Lavage Fluid (BALF) cytospin analysis and histological assessment of fixed lung tissue. Lung tissue was harvested, and RNA was extracted using the Direct-zol kit (Zymo). Samples (n=3/group) underwent RNA-Seq analysis. Differential expression of replicated count data was examined using the edgeR package on the R software and gene enrichment analysis was done using the Ingenuity Pathway Analysis (IPA) system with a threshold of ‑Log (P‑value)>2.Increased AHR and neutrophilic inflammation were observed in groups, XYF and XXF mice challenged with HDM (vs Control). RNA-Seq analysis showed 3154 differentially expressed genes in the FCG mice challenged with HDM among which are 38 downregulated and 151 upregulated genes in the XXF group, 87 downregulated and 1 upregulated gene in the XXM group, 35 downregulated and 279 upregulated genes in the XYF group, and 150 upregulated genes in the XYM group using the threshold of fold changes ≥1.2 and P<0.05. KRT4 gene was highly upregulated in XYF and XXF. IPA revealed the most activated upstream regulators in XXM, XXF, XYM, and XYF are EBI3, TGFB1, IL11RA, and STAT3 respectively. Canonical pathways that are found to be enriched in groups with female gonads only (XXF and XYF) was nicotine degradation III while PXR-RXR activation was found in XXF, XYF, and XYM. Interestingly, the pathways activated in groups XYF and XXF were associated with inflammatory response, organismal injury and abnormality, and respiratory disease while activated pathways in XYM and XXM were associated with cellular development, growth, proliferation and movement, and immune cell trafficking.These findings showed a fundamental difference in the gene expression profiles of FCG mice challenged with HDM. In addition, this study identified different pathways that are involved in the sex disparities in allergic airway inflammation model of asthma which may serve as targets for the development of sex-specific therapeutic prevention and treatment of asthma.

Public grant: NIH R01HL159764 and R03HL141618

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.