TITLE:
Transient Receptor Potential Ankyrin 1 Ion Channel Facilitates Acute Inflammation Induced by Surgical Incision in Mice
AUTHORS:
Maiko Hasegawa-Moriyama, Keika Mukaihara, Tomotsugu Yamada, Tomoyuki Kuwaki, Yuichi Kanmura
KEYWORDS:
Transient Receptor Potential Ankyrin 1, Surgical Incision, Macrophage, Inflammation
JOURNAL NAME:
Open Journal of Anesthesiology,
Vol.7 No.5,
May
25,
2017
ABSTRACT: Background: Transient receptor potential ankyrin (TRPA) 1 is known as a peripheral initiator of acute inflammation and hyperalgesia. However, its role in the facilitation of innate immune responses followed by resolution of the inflammation triggered by a surgical incision has not been fully investigated. Therefore, we evaluated the mechanism by which TRPA1 regulates the inflammatory responses mainly facilitated by neutrophils and macrophages in the early course of wound repair after an incision. Methods: Plantar incision was performed in wild-type and TRPA1-/- mice. The infiltration of polymorphonuclear neutrophils, macrophage phenotype, and induction of inflammatory mediators were assessed for 7 days postoperatively. Results: TRPA1-/-mice exhibited decreased infiltration of polymorphonuclear neutrophilscompared with wild-type mice on day 1. Consistently, the influx of F4/80+ iNOS+ proinflammatory M1 macrophages to incised sites was markedly decreased on day 2. Similarly, F4/80+ CD206+M2 macrophages, which regulate the resolution of inflammation and promote wound healing in the later phase of acute inflammation, were significantly decreased in TRPA1-/- compared with those in wild-type mice on day 7. In addition, the induction of heme oxygenase-1, which promotes wound healing by switching phenotype of macrophages, was decreased in the early phase of acute inflammation, whereas the expression of proinflammatory mediators such as tumor necrosis factor and cyclooxygenase-2, and 15-lipoxygenase, which are involved in the resolution of inflammation was increased in the late phase in TRPA1-/- mice. Conclusions: Early innate immune responses including neutrophil infiltration and macrophage polarization at incised sites were inhibited in TRPA1-/- mice, associated with increased pro-inflammatory mediators in later phase. Peripheral TRPA1 may facilitate the acute inflammatory process, leading to the promotion of macrophage-mediated resolution of inflammation and wound repair after a surgical incision.