The effect of chitosan on the migration of neutrophil-like HL60 cells, mediated by IL-8

Research interest in chitosan stems in part from the demonstrated wound healing properties. The benefits of chitosan as a therapeutic agent appear to be paradoxical because chitosan also elicits neutrophil infiltration indicative of an inflammatory response. While the affinity between chitosan and neutrophils has been well documented, the underlying mechanism is unclear. To our knowledge, no studies have investigated the consequences of chitosan–neutrophil interaction to explain neutrophil migration. To that end, transwell migration assays to chitosan of varying extent of acetylation were conducted using a differentiated model cell line (HL60-PMN) in order to assess the effect of chitosan chemistry and the resultant physical properties such as charge and hydrophobicity on neutrophil migration. As chitosan N-acetylation increased, neutrophil migration increased and chitosan became less positively charged and more hydrophobic. Moreover, HL60-PMN cells secreted the potent neutrophil chemokine IL-8, also known as CXCL8, when exposed to chitosan and IL-8 levels increased with N-acetylation, and migration was inhibited by anti-IL-8 antibodies. Collectively these results suggest that chitosan–neutrophil interaction is encouraged by material properties, results in IL-8 secretion, and causes migration of neutrophils to chitosan. The implication is that the wound healing properties of chitosan may be enhanced through the attenuation of overabundant neutrophils, and thus the inflammatory response, simply by changing chitosan N-acetylation.