Trappc1 intrinsically prevents ferroptosis of naive T cells to avoid spontaneous autoinflammatory disease in mice

Abstract T lymphocytes are pivotal in adaptive immunity. The role of the trafficking protein particle complex (TRAPPC) in regulating T‐cell development and homeostasis is unknown. Using CD4 cre ‐Trappc1 flox/flox (Trappc1 cKO) mice, we found that Trappc1 deficiency in T cells significantly decreased cell number of naive T cells in the periphery, whereas thymic T‐cell development in Trappc1 cKO mice was identical as WT mice. In the culture assays and mouse models with adoptive transfer of the sorted WT (CD45.1 + CD45.2 + ) and Trappc1 cKO naive T cells (CD45.2 + ) to CD45.1 + syngeneic mice, Trappc1‐deficient naive T cells showed significantly reduced survival ability compared with WT cells. RNA‐seq and molecular studies showed that Trappc1 deficiency in naive T cells reduced protein transport from the endoplasmic reticulum to the Golgi apparatus, enhanced unfolded protein responses, increased P53 transcription, intracellular Ca 2+ , Atf4‐CHOP, oxidative phosphorylation, and lipid peroxide accumulation, and subsequently led to ferroptosis. Trappc1 deficiency in naive T cells increased ferroptosis‐related damage‐associated molecular pattern molecules like high mobility group box 1 or lipid oxidation products like prostaglandin E2, leukotriene B4, leukotriene C4, and leukotriene D4. Functionally, the culture supernatant of Trappc1 cKO naive T cells significantly promoted neutrophils to express inflammatory cytokines like TNFα and IL‐6, which was rescued by lipid peroxidation inhibitor Acetylcysteine. Importantly, Trappc1 cKO mice spontaneously developed severe autoinflammatory disease 4 weeks after birth. Thus, intrinsic expression of Trappc1 in naive T cells plays an integral role in maintaining T‐cell homeostasis to avoid proinflammatory naive T‐cell death‐caused autoinflammatory syndrome in mice. This study highlights the importance of the TRAPPC in T‐cell biology.