Conditioned medium derived from human obese adipose tissue induces neutrophil activation via Toll-like receptor 4

Obesity is an alarmingly increasing global public health issue. In Brazil, in 2019, 26.8% of the adult population was already obese (BMI >30) and 60.3% overweight (BMI >25). Both obesity and overweight are characterized by an abnormal or excessive accumulation of fat capable of compromising health. This abnormal development of adipose tissue functions leads to an inflammatory site, reflecting in the increase of the number of immune system cell infiltrates, such as neutrophils. Traditionally, neutrophils are cells of the immune system considered protective of the body, eliminating both microbial infections and potential cancer cells. In the tumor context, these cells can be classified as N1 (proinflammatory) and N2 (anti-inflammatory). Recently, other groups have shown that neutrophil polarization, initially described in cancers, can also occur in other diseases.