Abstract
Purpose:
To examine if lacking TRPA1 cation channel affects the degree of development of stromal neovascularization (NV) in a mouse cornea. In vitro experiments was performed to investigate the effects of TRPA1 antagonist on vascular endothelial cell behaviors. TRPA1 cation channel is capable of activation upon exposure to various pungent or irritant compounds and mediate pain, hyperalgesia and neurogenic inflammation. TRPA1-derived signal also modulate tissue inflammation (Okada et al, Lab Invest 2014).
Methods:
(1) C57BL/6-backgroud TRPA1-null (KO) and wild-type (WT) mice were used. Central cornea was cauterized to induce stromal NV formation from the limbus. At day 3, 7 and 14 post-treatment the mice were killed and the cornea was processed for cryosectioning and immunostaining for PECAM-1. The length of stroma NV from limbus to the NV tip was measured and statistically analyzed. (2) NV-like tube formation by HUVECs was induced by adding VEGF to culture medium. The effects of further addition of TRPA1 antagonist (HC-030031:10μM) or TRPA1 agonist (AITC:10μM) on the degree of tube formation was examined.
Results:
(1) The loss of TRPA1 retarded the elongation of cauterization-induced stromal NV at day 3 and 14, but not at day 7, as compared with WT mice. (2) Adding the TRPA1 antagonist suppressed NV-like tube formation by HUVECs as judged by the evaluation of length and the number of branching points. Adding the TRPA1 agonist did not exhibit a specific effect on it.
Conclusions:
Lacking TRPA1 signal impairs cauterization-induced stromal NV formation in mice. Cell culture study indicates that the in vivo finding in KO mice is attributable to direct attenuation of TRPA1 signal in vascular endothelial cells.