Male-specific IL-33 expression regulates sex-dimorphic EAE susceptibility

Area of Science:

• Immunology
• Neuroscience
• Endocrinology

Background:

• Sex-dimorphic autoimmune diseases, including multiple sclerosis (MS), have unclear cellular and molecular underpinnings.
• Experimental autoimmune encephalomyelitis (EAE) in SJL mice serves as a model for MS research.

Purpose of the Study:

• To investigate the role of sex-determined differences in interleukin-33 (IL-33) expression in regulating EAE susceptibility.
• To elucidate the mechanisms by which IL-33 influences T-helper cell responses in the context of CNS autoimmunity.

Main Methods:

• Utilized the SJL mouse model of EAE induced by myelin peptide immunization.
• Analyzed sex-specific differences in IL-33 expression by innate immune cells.
• Investigated the activation of type 2 innate lymphoid cells (ILCs) by IL-33.
• Examined the effects of testosterone on IL-33 gene expression in mast cells.

Main Results:

• IL-33 was selectively induced in male mice following immunization, activating ILC2s.
• Activated ILC2s promoted a nonpathogenic Th2 myelin-specific immune response, attenuating EAE.
• Female mice, lacking this IL-33 response, developed an encephalitogenic Th17-dominant response.
• Testosterone directly induced IL-33 expression in mast cells, a source of IL-33.

Conclusions:

• IL-33 acts as a key mediator in sex-specific regulation of EAE susceptibility.
• Mast cells and ILC2s play a sex-specific role in attenuating pathogenic T-helper responses in CNS inflammatory diseases.
• Testosterone influences IL-33 production, contributing to sex dimorphism in autoimmune responses.