The TRIM37 variants in Mulibrey nanism patients paralyze follicular helper T cell differentiation.

The Mulibrey (Muscle-liver-brain-eye) nanism caused by loss-of-function variants in TRIM37 gene is an autosomal recessive disorder characterized by severe growth failure and constrictive pericarditis. These patients also suffer from severe respiratory infections, co-incident with an increased mortality rate. Here, we revealed that TRIM37 variants were associated with recurrent infection. Trim37 FIN (a representative variant of Mulibrey nanism patients) and Trim37 knockout mice were susceptible to influenza virus infection. These mice showed defects in follicular helper T (T) cell development and antibody production. The effects of Trim37 on T cell differentiation relied on its E3 ligase activity catalyzing the K27/29-linked polyubiquitination of Bcl6 and its MATH domain-mediated interactions with Bcl6, thereby protecting Bcl6 from proteasome-mediated degradation. Collectively, these findings highlight the importance of the Trim37-Bcl6 axis in controlling the development of T cells and the production of high-affinity antibodies, and further unveil the immunologic mechanism underlying recurrent respiratory infection in Mulibrey nanism.