Defense Date
2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Microbiology & Immunology
First Advisor
John Ryan
Abstract
Many allergic diseases are more common and severe in women than in men. A key component of allergic inflammation is IL-33, a cytokine released by epithelial cells after allergen exposure. Because mast cells are a central early responder in allergic disease and are activated by IL-33, we investigated sex differences in mast cell responses to IL-33. We first found that male mast cells expanded poorly in standard RPMI-based culture media containing phenol red, which has estrogenic properties. Male cells also responded poorly to IL-33 when cultured with in media containing phenol red. In contrast, female mast cells expanded 3-fold less in the absence of phenol red. Therefore, male and female cells were cultured in media that differed by the presence or absence of phenol red. Female primary mast cells cultured from the bone marrow of C57BL/6, C3H/HeJ, and BALB/cJ mice produce higher levels of cytokines in response to IL-33 than those from male cells. Peritoneal mast cell cultures yielded similar results. Female-dominant cytokine production was consistent when measuring IL-33-induced arachidonic acid metabolites that amplify inflammation. Mechanistically, we found robust IL-33-induced JNK activation in female mast cells that was absent in male cells. JNK inhibitor treatment significantly decreased IL-33-induced IL-33 responses in female mast cells, with no effect on male cells. Furthermore, administration of a JNK inhibitor in vivo decreased IL-33-induced eosinophilic infiltration, a key hallmark of allergic disease. These data led to subsequent studies in which we found that the IL-33 receptor, ST2, must be expressed on eosinophils to elicit their infiltration into the peritoneum. Surprisingly, IL-33 is not an eosinophil chemoattractant, as neither we nor others could induce eosinophil migration in vitro with IL-33. Finally, we found that eosinophils cultured from male and female mice produced similar levels of inflammatory cytokines when stimulated with IL-33, showing no sex differences. These data demonstrate that IL-33-induced inflammation is more pronounced in females and that while the IL-33 receptor must be expressed on eosinophils for their migration, IL-33 appears to sensitize eosinophils to migration, rather than directly induce it. Importantly, female-dominant IL-33 effects on mast cells were consistent across genetic backgrounds and mediated at least partly via selective JNK activation. Sex-restricted effects were not evident on eosinophils, suggesting some lineage specificity. These data offer new insight into sexual differences in the allergic response, a well-documented aspect of allergic disease that has lacked cellular and molecular insight. Our results point to JNK as a molecular target that might be inhibited selectively in females.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
8-5-2026