Published online Sep 21, 2018. doi: 10.3748/wjg.v24.i35.4036
Peer-review started: May 16, 2018
First decision: June 13, 2018
Revised: July 6, 2018
Accepted: July 22, 2018
Article in press: July 22, 2018
Published online: September 21, 2018
To investigate the anti-fibrotic effects of the traditional oriental herbal medicine Daikenchuto (DKT) associated with transient receptor potential ankyrin 1 (TRPA1) channels in intestinal myofibroblasts.
Inflammatory and fibrotic changes were detected in a 2,4,6-trinitrobenzenesulfonic acid (TNBS) chronic colitis model of wild-type and TRPA1-knockout (TRPA1-KO) mice via pathological staining and immunoblotting analysis. Ca2+ imaging experiments examined the effects of DKT and its components/ingredients on intestinal myofibroblast (InMyoFib) cell TRPA1 channel function. Pro-fibrotic factors and transforming growth factor (TGF)-β1-associated signaling were tested in an InMyoFib cell line by qPCR and immunoblotting experiments. Samples from non-stenotic and stenotic regions of the intestines of patients with Crohn’s disease (CD) were used for pathological analysis.
Chronic treatment with TNBS caused more severe inflammation and fibrotic changes in TRPA1-KO than in wild-type mice. A one-week enema administration of DKT reduced fibrotic lesions in wild-type but not in TRPA1-KO mice. The active ingredients of DKT, i.e., hydroxy α-sanshool and 6-shogaol, induced Ca2+ influxes in InMyoFib, and this was antagonized by co-treatment with a selective TRPA1 channel blocker, HC-030031. DKT counteracted TGF-β1-induced expression of Type I collagen and α-smooth muscle actin (α-SMA), which were accompanied by a reduction in the phosphorylation of Smad-2 and p38-mitogen-activated protein kinase (p38-MAPK) and the expression of myocardin. Importantly, 24-h incubation with a DKT active component Japanese Pepper increased the mRNA and protein expression levels of TRPA1 in InMyoFibs, which in turn negatively regulated collagen synthesis. In the stenotic regions of the intestines of CD patients, TRPA1 expression was significantly enhanced.
The effects of DKT on the expression and activation of the TRPA1 channel could be advantageous for suppressing intestinal fibrosis, and benefit inflammatory bowel disease treatment.
Core tip: Active ingredients of the famous Chinese medicine Da-Jian-Zhong-Tang (Daikenchuto; DKT), i.e., hydroxy α-sanshool and 6-shogaol, induced Ca2+ influxes in intestinal myofibroblast (InMyoFib), which were antagonized by co-treatment with a selective transient receptor potential ankyrin 1 (TRPA1) channel blocker HC-030031. DKT counteracted the transforming growth factor (TGF)-β1-induced expression of Type I collagen, α-smooth muscle actin (α-SMA), and this was accompanied by a reduction in fibrosis signaling downstream of the TGF-β1 receptor. Importantly, a 24-h incubation with another DKT active ingredient of Japanese Pepper increased mRNA and protein expression in TRPA1, which in turn negatively regulated collagen synthesis in InMyoFibs. In stenotic regions of the intestines of patients with Crohn’s disease, TRPA1 expression was significantly increased.