Induction of IL-13 Triggers TGF-β1-Dependent Tissue Fibrosis in Chronic 2,4,6-Trinitrobenzene Sulfonic Acid Colitis

In this study, we show that a single intranasal dose of a plasmid encoding active transforming growth factor β1 (pCMV-TGF-β1) prevents the development of T helper cell type 1 (Th1)-mediated experimental colitis induced by the haptenating reagent, 2,4,6-trinitrobenzene sulfonic acid (TNBS). In addition, such plasmid administration abrogates TNBS colitis after it has been established, whereas, in contrast, intraperitoneal administration of rTGF-β1 protein does not have this effect. Intranasal pCMV-TGF-β1 administration leads to the expression of TGF-β1 mRNA in the intestinal lamina propria and spleen for 2 wk, as well as the appearance of TGF-β1–producing T cells and macrophages in these tissues, and is not associated with the appearances of fibrosis. These cells cause marked suppression of interleukin (IL)-12 and interferon (IFN)-γ production and enhancement of IL-10 production; in addition, they inhibit IL-12 receptor β2 (IL-12Rβ2) chain expression. Coadministration of anti–IL-10 at the time of pCMV-TGF-β1 administration prevents the enhancement of IL-10 production and reverses the suppression of IL-12 but not IFN-γ secretion. However, anti–IL-10 leads to increased tumor necrosis factor α production, especially in established colitis. Taken together, these studies show that TGF-β1 inhibition of a Th1-mediated colitis is due to: (a) suppression of IL-12 secretion by IL-10 induction and (b) inhibition of IL-12 signaling via downregulation of IL-12Rβ2 chain expression. In addition, TGF-β1 may also have an inhibitory effect on IFN-γ transcription.

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Study on the effect of Periplaneta americana on ulcerative colitis in rats induced by 2,4,6-trinitrobenzene sulfonic acid

European Journal of Inflammation ◽

10.1177/2058739220942629 ◽

2020 ◽

Vol 18 ◽

pp. 205873922094262

Author(s):

Yi-Hao Che ◽

Zhi-Bin Yang ◽

Han-Chao Zhang ◽

Xiu-Mei Wu ◽

Min-Zhe Sun ◽

...

Keyword(s):

Ulcerative Colitis ◽

Sulfonic Acid ◽

Periplaneta Americana ◽

Treated Group ◽

Normal Control Group ◽

Control Group ◽

Trinitrobenzene Sulfonic Acid ◽

Tnf Α ◽

Ifn Γ ◽

Tgf Β1

Ulcerative colitis (UC) is a chronic inflammatory disease of intestinal tract, and Periplaneta americana has been found to be effective in the treatment for UC. The purpose of the study was to investigate the therapeutic effect of Periplaneta americana extract Ento-A on UC in rats induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) and to explore its mechanism. The Sprague-Dawley (SD) rats were randomly divided into normal control group; TNBS-treated group; sulfasalazine (SASP) treated group; Ento-A low- (50 mg/kg), medium- (100 mg/kg), and high-dose (200 mg/kg) groups, respectively. The UC model of rats was induced via TNBS. Disease activity index (DAI) was used to evaluate the severity of UC in rats. The macroscopic and microscopic damages of colon were accessed by colon mucosa damage index (CMDI) and histopathological score (HS), respectively. The levels of interleukin-4 (IL-4), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in serum and the contents of myeloperoxidase (MPO), transforming growth factor-β1 (TGF-β1), and epidermal growth factor (EGF) in colonic mucosa were measured by enzyme-linked immunosorbent assay (ELISA). Compared with the normal control group, the TNBS-treated group showed increase in DAI, CMDI, HS, IL-17, TNF-α, IFN-γ as well as MPO and decrease in the levels of IL-4, EGF, and TGF-β1. However, Ento-A-administrated groups reversed the changes in the DAI, CMDI, HS, and the cytokines caused by TNBS. The study indicates that Periplaneta americana extract Ento-A can effectively alleviate the inflammation in TNBS-induced UC of rats, and the mechanism of that may be related to restoring the balance of T helper 1 (Th1)/Th2/Th17/T regulatory (Treg) cytokines.

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