IFNγ-producing NK cells in adipose tissue are associated with hyperglycemia and insulin resistance in obese women

Background/objectives Innate lymphoid cells (ILCs) play an important role in the maintenance of immune and metabolic homeostasis in adipose tissue (AT). The crosstalk between AT ILCs and adipocytes and other immune cells coordinates adipocyte differentiation, beiging, glucose metabolism and inflammation. Although the metabolic and homeostatic functions of mouse ILCs have been extensively investigated, little is known about human adipose ILCs and their roles in obesity and insulin resistance (IR). Subjects/methods Here we characterized T and NK cell populations in omental AT (OAT) from women (n = 18) with morbid obesity and varying levels of IR and performed an integrated analysis of metabolic parameters and adipose tissue transcriptomics. Results In OAT, we found a distinct population of CD56(-)NKp46(+)EOMES(+) NK cells characterized by expression of cytotoxic molecules, pro-inflammatory cytokines, and markers of cell activation. AT IFN gamma(+) NK cells, but not CD4, CD8 or gamma delta T cells, were positively associated with glucose levels, glycated hemoglobin (HbA1c) and IR. AT NK cells were linked to a pro-inflammatory gene expression profile in AT and developed an effector phenotype in response to IL-12 and IL-15. Moreover, integrated transcriptomic analysis revealed a potential implication of AT IFN gamma(+) NK cells in controlling adipose tissue inflammation, remodeling, and lipid metabolism. Conclusions Our results suggest that a distinct IFN gamma-producing NK cell subset is involved in metabolic homeostasis in visceral AT in humans with obesity and may be a potential target for therapy of IR.