Background: A defective autophagy is involved in the pathogenesis of inflammatory disorders such as IBD. Cross talk interactions between autophagy and inflammation have been reported and we analyse the effects of autophagy stimulators on murine colitis.
Methods: Mice were treated with intrarectal administration of TNBS (3.5 mg/20 mg mice) and body weight was measured every day (and expressed as a percentage of starting weight), and histological damage score analysed two or four days after treatment. Some mice received trehalose (3% in drinking water three weeks before TNBS administration) or a daily administration of rapamycin (1.25 mg/kg, i.p.), betanin (1g/kg, i.p.) or betanin + 3MA (10mg/kg, i.p.). Mucosal protein levels of p-mTOR, p62, LC3, BCL10, NF-κB, IκBα and p-IκBα were determined by WB and mRNA expression of TNFα, IL1β, IL6, IL10, COX2, CCR7, CD11c, iNOS and CD86 by qRT-PCR.
Results: An impaired autophagy associated with body weight loss and intestinal damage was detected in the mucosa of TNBS-treated mice. Administration of trehalose, rapamycin or betanin prevented the impaired autophagic flux induced by TNBS and decreased the expression of pro-inflammatory cytokines and M1 macrophage markers (Fig. 1A) and mucosal protein levels of BCL10, p-IκBα and NF-κBp65. Blockade of the autophagosome formation by treatment of mice with 3MA prevented the reduction in both body weight loss (Fig. 1B) and protein levels of p62, BCL10, p-IκBα and NF-κBp65 (Fig 1C) induced by betanin in TNBS-treated mice and weakened the protective effects of betanin on murine colitis.
Conclusions: Our results demonstrate that pharmacological stimulation of mucosal autophagy reduces intestinal inflammation and ameliorates murine colitis.