title: TRPA1 is required for TGF-β signaling and its loss blocks inflammatory fibrosis in mouse corneal stroma.
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.
authors: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.
authors: Yuka
authors: Y
authors: Okada
authors: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.
authors: Kumi
authors: K
authors: Shirai
authors: Wenzhou Medical University School of Ophthalmology and Optometry, Wenzhou, China.
authors: Peter S
authors: PS
authors: Reinach
authors: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.
authors: Ai
authors: A
authors: Kitano-Izutani
authors: Laboratory Animal Center, Wakayama Medical University, Wakayama, Japan.
authors: Masayasu
authors: M
authors: Miyajima
authors: Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
authors: Kathleen C
authors: KC
authors: Flanders
authors: University of California, Irvine, CA, USA.
authors: James V
authors: JV
authors: Jester
authors: Division of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institute of Natural Science, Okazaki, Aichi, Japan.
authors: Makoto
authors: M
authors: Tominaga
authors: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.
authors: Shizuya
authors: S
authors: Saika
mesh_terms: D000818:Animals; D003316:Corneal Diseases / Q000473:pathology / Q000517:prevention & control*; D005126:Eye Burns / Q000503:physiopathology; D005355:Fibrosis / Q000517:prevention & control*; D007249:Inflammation / Q000517:prevention & control*; D051379:Mice; D018345:Mice, Knockout; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D000074025:TRPA1 Cation Channel; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D014945:Wound Healing
chemical_list: D000074025:TRPA1 Cation Channel; D016212:Transforming Growth Factor beta; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse