Characterization of sex-related differences in allergen house dust mite-challenged airway inflammation, in two different strains of mice.

Biological sex impacts disease prevalence, severity and response to therapy in asthma, however preclinical studies often use only one sex in murine models. Here, we detail sex-related differences in immune responses using a house dust mite (HDM)-challenge model of acute airway inflammation, in adult mice of two different strains (BALB/c and C57BL/6NJ). Female and male mice were challenged (intranasally) with HDM extract (~ 25 µg) for 2 weeks (N = 10 per group). Increase in serum HDM-specific IgE showed a female bias, which was statistically significant in BALB/c mice. We compared naïve and HDM-challenged mice to define immune responses in the lungs by assessing leukocyte accumulation in the bronchoalveolar lavage fluid (BALF), and profiling the abundance of 29 different cytokines in BALF and lung tissue lysates. Our results demonstrate specific sex-related and strain-dependent differences in airway inflammation. For example, HDM-driven accumulation of neutrophils, eosinophils and macrophages were significantly higher in females compared to males, in BALB/c mice. In contrast, HDM-mediated eosinophil accumulation was higher in males compared to females, in C57BL/6NJ mice. Differences in lung cytokine profiles indicated that HDM drives a T-helper (Th)17-biased response with higher IL-17 levels in female BALB/c mice compared to males, whereas female C57BL/6NJ mice elicit a mixed Th1/Th2-skewed response. Male mice of both strains showed higher levels of specific Th2-skewed cytokines, such as IL-21, IL-25 and IL-9, in response to HDM. Overall, this study details sex dimorphism in HDM-mediated airway inflammation in mice, which will be a valuable resource for preclinical studies in allergic airway inflammation and asthma.

Sex Dimorphism of Allergen-Induced Secreted Proteins in Murine and Human Lungs.

Biological sex influences disease severity, prevalence and response to therapy in allergic asthma. However, allergen-mediated sex-specific changes in lung protein biomarkers remain undefined. Here, we report sex-related differences in specific proteins secreted in the lungs of both mice and humans, in response to inhaled allergens. Female and male BALB/c mice (7-8 weeks) were intranasally challenged with the allergen house dust mite (HDM) for 2 weeks. Bronchoalveolar lavage fluid (BALF) was collected 24 hour after the last HDM challenge from allergen-naïve and HDM-challenged mice (N=10 per group, each sex). In a human study, adult participants were exposed to nebulized (2 min) allergens (based on individual sensitivity), BALF was obtained after 24 hour (N=5 each female and male). The BALF samples were examined in immunoblots for the abundance of 10 proteins shown to increase in response to allergen in both murine and human BALF, selected from proteomics studies. We showed significant sex-bias in allergen-driven increase in five out of the 10 selected proteins. Of these, increase in eosinophil peroxidase (EPX) was significantly higher in females compared to males, in both mice and human BALF. We also showed specific sex-related differences between murine and human samples. For example, allergen-driven increase in S100A8 and S100A9 was significantly higher in BALF of females compared to males in mice, but significantly higher in males compared to females in humans. Overall, this study provides sex-specific protein biomarkers that are enhanced in response to allergen in murine and human lungs, informing and motivating translational research in allergic asthma.