Neutrophil secretion modulates neutrophil and monocyte functions during hyperglucose and/or hyperinsulin conditions in vitro

Abstract

Neutrophils, the first cells that come to the infection site, regulate the recruitment and functioning of monocytes. Alteration in neutrophil secretions during pathological conditions result in altered neutrophil and monocyte functions. As hyperglucose and hyperisulin conditions are known to prime cells of innate immune system, the role of neutrophil secretion in activating or priming neutrophils and monocytes during these conditions was studied.

Neutrophils were isolated and treated with hyperglucose, hyperinsulin or hyperglucose + hyperinsulin conditions in vitro and the neutrophil supernatants were collected. Neutrophil and monocyte cells treated with these supernatants were then studied for their functions such as chemotaxis, phagocytosis, NBT reduction and killing ability.

Secretions of unstimulated neutrophils suppressed chemotaxis, phagocytosis and killing ability of monocytes but it did not affect the functions of neutrophils. Hyperinsulin and hyperglucose + hyperinsulin-induced neutrophil secretions caused reduction in phagocytic index of neutrophils without affecting other functions. Neutrophil secretions collected during hyperglucose or hyperinsulin did not alter monocyte functions significantly when compared to secretion collected from unstimulated neutrophils. In conclusion, the study reveals the role of neutrophil secretions in modulating neutrophil and monocyte functions in hyperglucose and hyperinsulin conditions.