γδ T cells producing interleukin-17A regulate adipose regulatory T cell homeostasis and thermogenesis

gamma delta T cells are situated at barrier sites and guard the body from infection and damage. However, little is known about their roles outside of host defense in nonbarrier tissues. Here, we characterize a highly enriched tissue-resident population of gamma delta T cells in adipose tissue that regulate age-dependent regulatory T cell (T-reg) expansion and control core body temperature in response to environmental fluctuations. Mechanistically, innate PLZF(+) gamma delta T cells produced tumor necrosis factor and interleukin (IL) 17 A and determined PDGFR alpha(+) and Pdpn(+) stromal-cell production of IL-33 in adipose tissue. Mice lacking gamma delta T cells or IL-17A exhibited decreases in both ST2(+) T-reg cells and IL-33 abundance in visceral adipose tissue. Remarkably, these mice also lacked the ability to regulate core body temperature at thermoneutrality and after cold challenge. Together, these findings uncover important physiological roles for resident gamma delta T cells in adipose tissue immune homeostasis and body-temperature control.