Chemotactic effect of melatonin on leukocytes

Abstract

Melatonin seems to be an important stimulatory factor of the immune system. This indolamine is capable of inducing activation of leukocytes. Tissue leukocyte infiltration is a key feature of inflammatory and immune responses; however, there is no information about the effect of melatonin on leukocyte chemotaxis. Therefore, the aim of this study was to examine the in vitro and in vivo effects of melatonin on leukocyte chemotaxis, on modulation of leukocyte chemotaxis to other chemoattractants and on the in vivo induction of leukocyte chemokines. Neutrophils and mononuclear leukocytes (PBMC) were isolated by a discontinuous gradient on Hystopaque. Chemotaxis was performed in blind well Boyden's chambers. In vivo chemotaxis was determined after intraperitoneal injection of melatonin into rats. Leukocyte chemotactic response and leukocyte chemokine expression were determined in human volunteers treated with 20 mg daily of melatonin. Increased neutrophils and PBMC chemotaxis in response to 1.2 nm melatonin was observed in vitro. Peritoneal leukocytes were found increased after melatonin injection. Humans treated with melatonin showed an increased neutrophil chemotactic response to a physiological chemoattractant and increased expression of intracellular chemokines; however, decreased chemotactic response and no chemokine expression were observed in PBMC. These data suggest that melatonin could have a relevant role during the tissue leukocyte infiltration in inflammatory and immune responses.

Exogenous melatonin inhibits neutrophil migration through suppression of ERK activation

“…that melatonin could play a positive (Pena et al 2007, Ren et al 2015 or negative (Lotufo et al 2001) effect in neutrophil function. By incorporating the inconsistent effects of melatonin in previous studies (Lotufo et al 2001, Pena et al 2007, we inferred that the ultimate role of melatonin could result from the initial pathophysiological conditions and the various application concentrations.…”

“…By incorporating the inconsistent effects of melatonin in previous studies (Lotufo et al 2001, Pena et al 2007, we inferred that the ultimate role of melatonin could result from the initial pathophysiological conditions and the various application concentrations.…”

“…The inconsistent role of melatonin in previous studies indicates that the endogenous and exogenous melatonin may execute discrepant function in immune stabilization (delGobbo et al 1989, Lotufo et al 2001, Pena et al 2007. Our latest study demonstrated that the pineal melatonin plays a positively regulating role in neutrophil migration (Ren et al 2015), and this finding motivated us to further explore the potential effect of exogenous melatonin on neutrophil function.…”

“…Recently, melatonin has also been proved to modulate leukocyte behavior in physiological chemoattractants, but the studies were short of consistently functional results (Lotufo et al 2001, Pena et al 2007. The inconsistent role of melatonin in previous studies indicates that the endogenous and exogenous melatonin may execute discrepant function in immune stabilization (delGobbo et al 1989, Lotufo et al 2001, Pena et al 2007.…”

Leucocyte Infiltration in Lymphoid Organs and Peritoneal Cavity upon Immunization: Dependence on Circadian Rhythmicity and Melatonin 24-H Profile

“…In the presence of TNFa, melatonin promoted RANTES and eotaxin expression in a dose-dependent manner in human A549 cells (24). Melatonin increases the number of rat peritoneal leukocytes after a melatonin injection, and increases chemotaxis of neutrophils and PBMC in vitro and expression of chemokines in humans (25). Hriscu et al described that constant light decreased the adherence ability of rat neutrophils (26).…”