Changes caused by extracellular vesicles from obese adipose tissue and their implications for the effector and cytotoxic activity of NK cells against TNBC.

Obesity is associated with alterations in immune function and with a poorer prognosis in different types of cancer, including breast cancer. Extracellular vesicles (EVs) derived from adipose tissue have been described as important mediators of intercellular communication and may contribute to the modulation of immune responses. In this study, we evaluated the effect of large EVs (>200 nm, according to ISEV criteria), isolated from the adipose tissue of individuals with grade III/IV obesity (n=5), on natural killer (NK) cells in a co-culture model with triple-negative breast cancer cells. EVs were isolated by differential centrifugation up to 18,000 × g and characterized by dynamic light scattering and by the presence of CD63 and CD81. NK cells were isolated from peripheral blood of female donors (n=3) by negative selection and characterized as CD3−CD56+ by flow cytometry. The cells were pretreated with EVs for 4 h and then co-cultured with tumor cells for 12 h. Gene expression of NKG7, IFN-γ, perforin-1, and granzyme B was evaluated in NK cells. Treatment with EVs alone did not significantly alter the expression of the genes analyzed. NKG7 expression was reduced in both groups exposed to tumor cells (p<0.05), with no difference between them, suggesting that this effect was mainly associated with the presence of the tumor. However, NK cells pretreated with EVs and subsequently exposed to tumor cells showed lower expression of IFN-γ, perforin-1, and granzyme B compared with NK cells exposed only to tumor cells (p<0.05). These results suggest that EVs derived from the adipose tissue of individuals with obesity may contribute to reducing the effector/cytotoxic response of NK cells against triple-negative breast cancer cells in vitro. The study was approved by the Research Ethics Committee of the Federal University of Juiz de Fora (CAAE: 86845525.1.1001.5147; approval no. 7.725.580).