Regulatory T cells (Tregs) subdue immune responses. Central to Treg activation are changes in lipid metabolism that support their survival and function. Fatty acid binding proteins (FABPs) are a family of lipid chaperones required to facilitate uptake and intracellular lipid trafficking. One family member, FABP5, is expressed in T cells, but its function remains unclear. We show that in Tregs, genetic or pharmacologic inhibition of FABP5 function causes mitochondrial changes underscored by decreased OXPHOS, impaired lipid metabolism, and loss of cristae structure. FABP5 inhibition in Tregs triggers mtDNA release and consequent cGAS-STING-dependent type I IFN signaling, which induces heightened production of the regulatory cytokine IL-10 and promotes Treg suppressive activity. We find evidence of this pathway, along with correlative mitochondrial changes in tumor infiltrating Tregs, which may underlie enhanced immunosuppression in the tumor microenvironment. Together, our data reveal that FABP5 is a gatekeeper of mitochondrial integrity that modulates Treg function.
Bibliographical noteFunding Information:
E.L.P. is a SAB member of Immunomet, and E.L.P. and E.J.P. are founders of Rheos Medicines. B.R.B. receives remuneration as an advisor to Kamon Pharmaceuticals, Inc., Five Prime Therapeutics Inc., Regeneron Pharmaceuticals, Magenta Therapeutics, and BlueRock Therapeutics; research support from Fate Therapeutics, RXi Pharmaceuticals, Alpine Immune Sciences, Inc., Abbvie Inc., BlueRock Therapeutics Leukemia and Lymphoma Society, Childrens’ Cancer Research Fund, and KidsFirst Fund and is a co-founder of Tmunity.
We thank G. Hotamisligil for sharing the Fabp4/5 dKO mice and Johan Friden for assistance with the graphical abstract. This work was supported by grants from the National Institutes of Health R01 HL11879 and R37 AI34495 (B.R.B.), P01 CA065493 (B.R.B.; K.L.H.), R01 AI110481 (E.J.P.), R01 CA181125 (E.L.P.), and the Max Planck Society . F.B. and M.C. are supported by a Humboldt Fellowship from the Humboldt Foundation . D.J.P. is supported by a Sir Henry Wellcome Fellowship from the Wellcome Trust .
© 2019 The Authors
- type I IFN
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, Non-U.S. Gov't