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OP03 Inhibition of autophagy exacerbates intestinal fibrosis and EMT

J. Cosin-Roger*1,2, D. Ortiz-Masia3, F. Canet1, A. Trescoli-Garcia1, S. Calatayud1, M. D. Barrachina1

1University of Valencia, Pharmacology, Valencia, Spain, 2Hospital Dr Peset, Valencia, Spain, 3University of Valencia, Medicine, Valencia, Spain

Background

Intestinal fibrosis is a common complication of Crohn’s disease (CD) patients and it requires surgery. GWAS studies have identified several polymorphisms in genes involved in autophagy, which predispose to CD. It has been reported that this process is impaired in IBD patients, but the relevance of autophagy in intestinal fibrosis remains unclear. We aim to analyse the effect of pharmacological inhibition of autophagy in the development of murine intestinal fibrosis.

Methods

Intestinal fibrosis was induced in vivo using the heterotopic transplant model. Segments of 1 cm colon from mice were subcutaneously transplanted into the neck of a recipient mice and collected after 7 days. Recipient mice were treated with a daily injection of 3-MA (10 mg/kg). Expression of intestinal inflammation, fibrosis, and EMT markers were analysed by qPCR and protein levels of autophagy markers by western blot. Collagen layer was evaluated by Sirius Red Staining. Intestinal resections from CD patients were obtained and expression of p62, Col1a1, α-SMA, Snail1, and Snail2 was analysed by qPCR. Results are expressed as fold induction (mean ± SEM, n ≥ 5). Statistical analysis was performed with one-way ANOVA followed by Newman–Keuls test. Correlations were analysed with the Spearman coefficient.

Results

Grafts obtained 7 days after surgery from 3-MA treated mice vs. vehicle-treated mice exhibited: (a) a significant increase in the expression of proinflammatory genes such as TNF-α (102.90 ± 22.94 vs. 50.46 ± 7.47), IL-1β (425.4 ± 84.92 vs. 243.70 ± 35.85), IL-6 (735.7 ± 235.0 vs. 339.90 ± 137.5) and INOS (325.7 ± 75.85 vs. 166.2 ± 23.64); (b) an increase in the expression of profibrotic genes such as Col1a1 (74.21 ± 9.18 vs. 41.27 ± 9.34), Vimentin (9.98 ± 4.54 vs. 6.73 ± 0.64) and TGF-β (6.69 ± 1.91 vs. 6.62 ± 0.60); (c) a significant increase in the expression of EMT genes such as Snail1 (21.10 ± 4.60 vs. 11.61 ± 1.49), Snail2 (7.32 ± 1.87 vs. 3.70 ± 0.73) and Itgb6 (7.70 ± 1.89 vs. 2.65 ± 0.43); (d) a significant thicker collagen layer after Sirius Red Staining. Autophagy inhibition by 3-MA was confirmed by western blot showing an increase of p62 and phospho-mTOR and a reduction in LC3. In intestinal resections from CD patients, the expression of p62 positively correlates with the expression of Col1a1 (rSpearman = 0.6098, p = 0.004), α-sma (rSpearman = 0.5168, p = 0.041), Snail1 (rSpearman = 0.4112, p = 0.0003) and Snail2 (rSpearman = 0.4410, p = 0.0009).

Conclusion

Pharmacological inhibition of autophagy exacerbates murine intestinal inflammation, fibrosis, and EMT. In intestinal resections from CD patients the expression of autophagy markers correlates with the expression of pro-fibrotic and pro-EMT genes, which led us to suggest that pharmacological modulation of autophagy might be a new therapeutic option for intestinal fibrosis.