Anti-Tumor Necrosis Factor Alpha Prevents Bowel Fibrosis Assessed By Messenger Rna, Histology, And Magnetization Transfer Mri In Rats With Crohn'S Disease

Objective: Treatment of Crohn's disease (CD) with anti-tumor necrosis factor alpha (TNF alpha) decreases intestinal inflammation, but the effect on fibrosis remains unclear. We hypothesized that treatment with rat-specific anti-TNF alpha will decrease the development of intestinal fibrosis in a rat model of CD. We further hypothesized that magnetization transfer magnetic resonance imaging (MT-MRI) will be sensitive in detecting these differences in collagen content.Methods: Rats were injected in the distal ileum and cecum with peptidoglycan-polysaccharide (PG-PS) or human serum albumin (control) at laparotomy and then received intraperitoneal injections of rat-specific anti-TNF alpha or vehicle daily for 21 days after laparotomy. Rats underwent MT-MRI abdominal imaging on day 19 or 20. MT ratio was calculated in the cecal wall. Cecal tissue histologic inflammation was scored. Cecal tissue procollagen, cytokine, and growth factor messenger RNAs were measured by quantitative real-time PCR.Results: PG-PS-injected rats treated with anti-TNF alpha had less histologic inflammation, and cecal tissue expressed lower levels of proinflammatory cytokine messenger RNAs than vehicle-treated PG-PS-injected rats (IL-1 beta: 5.59 +/- 1.53 versus 10.41 +/- 1.78, P = 0.02; IL-6: 23.23 +/- 9.33 versus 45.89 +/- 11.79, P = 0.07). PG-PS-injected rats treated with anti-TNF alpha developed less intestinal fibrosis than vehicle-treated PG-PS-injected rats by tissue procollagen I (2.87 +/- 0.66 versus 9.28 +/- 1.11; P = 0.00002), procollagen III (2.25 +/- 0.35 versus 7.28 +/- 0.76; P = 0.0000009), and MT-MRI (MT ratio: 17.79 +/- 1.61 versus 27.95 +/- 1.75; P = 0.0001). Insulin-like growth factor I (2.52 +/- 0.44 versus 5.14 +/- 0.60; P = 0.0007) and transforming growth factor beta 1 (2.34 +/- 0.29 versus 3.45 +/- 0.29; P = 0.006) were also decreased in anti-TNF alpha-treated PG-PS-injected rats.Conclusions: Anti-TNF alpha prevents the development of bowel wall inflammation and fibrosis in the PG-PS rat model of CD. MT-MRI measurably demonstrates this decrease in intestinal fibrosis. (Inflamm Bowel Dis 2013;19:683-690)