Sexual Dimorphism in Innate Immunity

Michael Scally MD

Doctor of Medicine
10+ Year Member
Jaillon S, Berthenet K, Garlanda C. Sexual Dimorphism in Innate Immunity. Clin Rev Allergy Immunol. https://link.springer.com/article/10.1007%2Fs12016-017-8648-x

Sexual dimorphisms account for differences in clinical manifestations or incidence of infectious or autoimmune diseases and malignancy between females and males. Females develop enhanced innate and adaptive immune responses than males and are less susceptible to many infections of bacterial, viral, parasitic, and fungal origin and malignancies but in contrast, they are more prone to develop autoimmune diseases.

The higher susceptibility to infections in males is observed from birth to adulthood, suggesting that sex chromosomes and not sex hormones have a major role in sexual dimorphism in innate immunity. Sex-based regulation of immune responses ultimately contributes to age-related disease development and life expectancy.

Differences between males and females have been described in the expression of pattern recognition receptors of the innate immune response and in the functional responses of phagocytes and antigen presenting cells. Different factors have been shown to account for the sex-based disparity in immune responses, including genetic factors and hormonal mediators, which contribute independently to dimorphism in the innate immune response.

For instance, several genes encoding for innate immune molecules are located on the X chromosome. In addition, estrogen and/or testosterone have been reported to modulate the differentiation, maturation, lifespan, and effector functions of innate immune cells, including neutrophils, macrophages, natural killer cells, and dendritic cells.

In this review, we will focus on differences between males and females in innate immunity, which represents the first line of defense against pathogens and plays a fundamental role in the activation, regulation, and orientation of the adaptive immune response.


 

Attachments

Testosterone Attenuates Group 2 Innate Lymphoid Cell-Mediated Airway Inflammation

Highlights
· The number of ILC2 is increased in women with asthma compared to men with asthma
· Sex hormones regulate IL-2-dependent ILC2 proliferation and cytokine expression
· Testosterone intrinsically and extrinsically attenuates ILC2 airway inflammation

Sex hormones regulate many autoimmune and inflammatory diseases, including asthma. As adults, asthma prevalence is 2-fold greater in women compared to men.

The number of group 2 innate lymphoid cells (ILC2) is increased in patients with asthma, and we investigate how testosterone attenuates ILC2 function. In patients with moderate to severe asthma, we determine that women have an increased number of circulating ILC2 compared to men. ILC2 from adult female mice have increased IL-2-mediated ILC2 proliferation versus ILC2 from adult male mice, as well as pre-pubescent females and males.

Further, 5alpha-dihydrotestosterone, a hormone downstream of testosterone, decreases lung ILC2 numbers and IL-5 and IL-13 expression from ILC2. In vivo, testosterone attenuated Alternaria-extract-induced IL-5+ and IL-13+ ILC2 numbers and lung eosinophils by intrinsically decreasing lung ILC2 numbers, as well as by decreasing expression of IL-33 and thymic stromal lymphopoietin (TSLP), ILC2-stimulating cytokines.

Collectively, these findings provide a foundational understanding of sexual dimorphism in ILC2 function.

Cephus JY, Stier MT, Fuseini H, et al. Testosterone Attenuates Group 2 Innate Lymphoid Cell-Mediated Airway Inflammation. Cell Rep 2017; 21:2487-2499. http://www.cell.com/cell-reports/fulltext/S2211-1247(17)31590-5
 
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