A GDF-15-GFRAL axis controls autoimmune T cell responses during neuroinflammation.

Inflammatory activity during multiple sclerosis (MS) often improves during pregnancy, suggesting that pregnancy-related immune adaptations affect the disease. Here we show that growth/differentiation factor-15 (GDF-15) increases during pregnancy and correlates with a reduced rate of MS relapses. GDF-15 also accumulates in the inflamed central nervous system, and its absence impairs inflammation resolution in a mouse model of MS. GDF-15 suppresses autoimmune T cell responses through an indirect signaling pathway involving the activation of GDNF family receptor α-like (GFRAL) on brainstem neurons. Therapeutic approaches, including neuronal gene delivery, recombinant GDF-15 administration and targeted chemogenetic activation of GFRAL-positive neurons induce β-adrenergic signaling and norepinephrine synthesis in the spleen, leading to decreased expression of integrins on T cells required for transmigration across the blood-brain barrier and confer protection against neuroinflammation in preclinical models of MS. These findings position GDF-15 as a crucial neuroimmune mediator and the GDF-15-GFRAL axis as promising target for MS.