Lacking TRPA1 cation channel impairs primary closure of a stromal incision injury in a mouse cornea.

Abstract

The cornea is a high sensory, innervated, avascular tissue that consists of epithelium, keratocytes, endothelium, and extracellular matrix. We evaluated the effects of gene knockout of the transient receptor potential ankyrin 1 (TRPA1), a membrane cation channel potentially activated by various external stimuli on the wound-healing process in corneal stroma following an incision injury in mice. TRPA1 protein was detected markedly in corneal epithelium and cells in the stroma in a healthy uninjured wild-type (WT) cornea. Deletion of TRPA1 gene function delayed wound closure of a full-thickness incision injury in corneal stroma. Peak of appearance of Sox10 (Schwann cell marker)-positive and Sox2- or p75- (both repair-type Schwann cell markers) expressing cells, in the healing stroma was at day 2 post-incision injury in a WT mouse, that was delayed in a TRPA1-knockout (KO) mouse during the healing process. Expression of TGFβ1 mRNA was suppressed, in association with reduction of p-Smad3 expression in stromal cells, by TRPA1 gene deletion. We also observed that the loss of TRPA1 suppressed the appearance of myofibroblasts and expression of collagen Ia1 and fibronectin in the healing stroma. In vitro gel culture study showed that chemical TRPA1 inhibition attenuated TGFβ-induced fibroblast contractility. These results indicate that TRPA1 is involved in the process of corneal stromal wound healing in response to tissue laceration in mice. The phenotype was associated with attenuation of generation of repair Schwann cells, of TGFβ signaling in stromal cells, keratocyte-myofibroblast transformation, and collagen type I expression. (241 words).