Bidirectional crosstalk between neutrophils and adipocytes promotes adipose tissue inflammation

Chronic activation of the IL-1β system in adipose tissue on metabolic disorders is well demonstrated. However, a mechanism for its expression and activation in the tissue has remained unexplored. Here, we demonstrate that IL-1β transcript was enriched in neutrophils of white adipose tissue (WAT) from lean mice. Mechanistically, the interaction of neutrophils with adipocytes induced IL-1β expression <i>via</i> NF-κB pathway. Lipolysis of adipocytes accumulated neutrophils prior to macrophages in WAT and produced high levels of IL-1β <i>via</i> an inflammasome pathway. Leukotriene B₄ (LTB₄) production in WAT also contributed to neutrophil accumulation. Furthermore, an LTB₄-inflammasome axis contributed to the expression of chemotactic molecules involved in high-fat diet-induced macrophage infiltration into WAT. We have identified previously unappreciated roles for neutrophils in the development of adipose tissue inflammation: robust IL-1β production and infiltration of macrophages to initiate chronic inflammation.-Watanabe, Y., Nagai, Y., Honda, H., Okamoto, N., Yanagibashi, T., Ogasawara, M., Yamamoto, S., Imamura, R., Takasaki, I., Hara, H., Sasahara, M., Arita, M., Hida, S., Taniguchi, S., Suda, T., Takatsu, K. Bidirectional crosstalk between neutrophils and adipocytes promotes adipose tissue inflammation.