Figure 3.

NK cells in obesity. Alteration of NK cells in obese patients includes (A) reduced NK cell frequency, (B) unbalance between anti- and pro-inflammatory behavior of NK cells, and (C) increased release of both perforin and granzymes B, while IFNγ is found both up and down modulated. At the molecular level, NK cells of obese patients showed a (D) increased number of IL6Rα+ cells that correlated with low-grade inflammation markers, (E) decreased expression of NKp46 and NKG2A/CD94, with subsequently reduced cytotoxicity, (F) increased expression CD69 activation marker correlated with increased release of granzyme B, and (G) reduction of CD16 responsible for the reduced ADCC. Finally, the increased circulating level of leptin in obese patients (H) affects NK cells maturation by the inhibition of mTOR signalling in NK cells precursors, resulting in reduced maturation, thus contributing to reduced NK cell frequency.