Overexpression of Fibulin-5 attenuates burn-induced inflammation via TRPV1/CGRP pathway

Fibulin-5, a multifunctional extracellular matrix protein, is up-regulated in response to mechanical injury and can promote dermal wound healing. This study aimed to explore the role and mechanism of Fibulin-5 in the pathogenesis of post-burn inflammation in thermally-injured mice. Here, we found that Fibulin-5 was up regulated in the dorsal root ganglion (DRG) of burn-injured mice. After nociceptive behavioral testing, DRG was isolated and cultured to detect the mechanism of Fibulin-5 in thermal injury models by recombinant adenovirus overexpressing Fibulin-5, RT-qPCR, Western Blot, ELISA, AP20187 (an activator of one kind of kinase phosphorylating the a subunit of eukaryotic initiation factor 2, eIF2 alpha), capsaicin (an agonist of transient receptor potential vanilloid (TRPV)-1), and an anti-CGRP neutralizing antibody. Also, the pathological state of skin tissues and the expression of cyclooxygenase 2 and myeloperoxidase were examined by Hematoxylin-Eosin staining and immunohistochemistry, respectively. We found that overexpression of Fibulin-5 attenuated the pain, inhibited the inflammatory response, and improved the pathologic condition induced by burn injury. Fibulin-5 overexpression significantly down-regulated the phosphorylation level of eIF2 alpha and subsequently inhibited the TRPV1 channel and CREB/CGRP signaling. Additionally, anti-CGRP neutralizing antibody dramatically suppressed the inflammatory response induced by burn injury. The results suggest that overexpression of Fibulin-5 attenuates thermal inflammation via suppressing TRPV1/CGRP pathway. This may provide a potential therapy target to alleviate excessive inflammation in burn patients.