1. TRPA1 is required for TGF-β signaling and its loss blocks inflammatory fibrosis in mouse corneal stroma
- Author
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Okada, Yuka, Shirai, Kumi, Reinach, Peter S, Kitano-Izutani, Ai, Miyajima, Masayasu, Flanders, Kathleen C, Jester, James V, Tominaga, Makoto, and Saika, Shizuya
- Subjects
Physical Injury - Accidents and Adverse Effects ,Eye Disease and Disorders of Vision ,Aetiology ,2.1 Biological and endogenous factors ,5.2 Cellular and gene therapies ,Development of treatments and therapeutic interventions ,Animals ,Corneal Diseases ,Eye Burns ,Fibrosis ,Inflammation ,Mice ,Mice ,Knockout ,Real-Time Polymerase Chain Reaction ,Signal Transduction ,TRPA1 Cation Channel ,Transforming Growth Factor beta ,Transient Receptor Potential Channels ,Wound Healing ,Clinical Sciences ,Pathology - Abstract
We examined whether the loss of transient receptor potential ankyrin 1 (TRPA1), an irritant-sensing ion channel, or TRPA1 antagonist treatment affects the severity inflammation and scarring during tissue wound healing in a mouse cornea injury model. In addition, the effects of the absence of TRPA1 on transforming growth factor β1 (TGF-β1)-signaling activation were studied in cell culture. The lack of TRPA1 in cultured ocular fibroblasts attenuated expression of TGF-β1, interleukin-6, and α-smooth muscle actin, a myofibroblast the marker, but suppressed the activation of Smad3, p38 MAPK, ERK, and JNK. Stroma of the healing corneas of TRPA1(-/-) knockout (KO) mice appeared more transparent compared with those of wild-type mice post-alkali burn. Eye globe diameters were measured from photographs. An examination of the corneal surface and eye globes suggested the loss of TRPA1 suppressed post-alkali burn inflammation and fibrosis/scarring, which was confirmed by histology, immunohistochemistry, and gene expression analysis. Reciprocal bone marrow transplantation between mice showed that KO corneal tissue resident cells, but not KO bone marrow-derived cells, are responsible for KO mouse wound healing with reduced inflammation and fibrosis. Systemic TRPA1 antagonists reproduced the KO phenotype of healing. In conclusion, a loss or blocking of TRPA1 in mice reduces inflammation and fibrosis/scarring in the corneal stroma during wound healing following an alkali burn. The responsible mechanism may include the inhibition of TGF-β1-signaling cascades in fibroblasts by attenuated TRPA1 signaling. Inflammatory cells are considered to have a minimum involvement in the exhibition of the KO phenotype after injury.
- Published
- 2014