Gestational Hypothyroxinemia Shifts Th1/Th17 Immunity and Innate Lymphoid Cell Balance in the Adult Offspring during the Presymptomatic Stage of Experimental Autoimmune Encephalomyelitis.

Introduction: Thyroid hormone homeostasis during pregnancy is crucial for proper neurodevelopment and cognitive capacity during adulthood. Accumulating evidence reveals that gestational hypothyroxinemia (HTX) modulates the immune response of the adult offspring.

Methods: In the present study, adult mice gestated in HTX and their euthyroid counterparts were induced with a mild form of experimental autoimmune encephalomyelitis (EAE), a widespread model of multiple sclerosis, and analyzed at baseline and 7 days after EAE induction.

Results: Levels of circulating IL-17 were significantly lower in mice gestated in HTX at both timepoints, while circulating IFN-γ was significantly higher only in mice gestated in HTX, 7 days after EAE induction. A significant increase in type 1 innate lymphoid cells (ILC1) was found only in mice gestated in HTX 7 days after EAE induction, while type 3 innate lymphoid cells (ILC3) populations showed no variation. Interestingly, a significant increase of Th17 CD4+ cells was found only in mice of euthyroid gestation, 7 days after EAE induction.

Conclusion: These results highlight the repercussions of thyroid hormone impairment in utero at adult ages while dissecting on the pathogenesis of EAE in terms of Th1/Th17 balance from an innate immune perspective. These findings contribute to the advancement of our comprehension of the presymptomatic stage of EAE, unveiling new paths for basic and translational research in the field of neuroinflammation.