Boosting mTOR-dependent autophagy via upstream TLR4-MyD88-MAPK signalling and downstream NF-κB pathway quenches intestinal inflammation and oxidative stress injuryResearch in context
Mingxia Zhou,
Weimin Xu,
Jiazheng Wang,
Junkai Yan,
Yingying Shi,
Cong Zhang,
Wensong Ge,
Jin Wu,
Peng Du,
Yingwei Chen
Affiliations
Mingxia Zhou
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Weimin Xu
Department of Colorectal Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
Jiazheng Wang
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Junkai Yan
Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Yingying Shi
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Cong Zhang
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Wensong Ge
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
Jin Wu
Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
Peng Du
Department of Colorectal Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Corresponding author at: Department of Colorectal Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
Yingwei Chen
Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China; Correspondence to: Yingwei Chen, Department of Gastroenterology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China.
Background and aims: Defective autophagy has been proposed as an important event in a growing number of autoimmune and inflammatory diseases such as rheumatoid arthritis and lupus. However, the precise role of mechanistic target of rapamycin (mTOR)-dependent autophagy and its underlying regulatory mechanisms in the intestinal epithelium in response to inflammation and oxidative stress remain poorly understood. Methods: The levels of p-mTOR, LC3B, p62 and autophagy in mice and LPS-treated cells were examined by immunoblotting, immunohistochemistry, confocal microscopy and transmission electron microscopy (TEM). We evaluated the expression of IL-1β, IL-8, TNF-α, MDA, SOD and T-AOC by quantitative real time-polymerase chain reaction (qRT-PCR) and commercially available kits after silencing of mTOR and ATG5. In vivo modulation of mTOR and autophagy was achieved by using AZD8055, rapamycin and 3-methyladenine. Finally, to verify the involvement of TLR4 signalling and the NF-κB pathway in cells and active ulcerative colitis (UC) patients, immunofluorescence, qRT-PCR, immunoblotting and TEM were performed to determine TLR4 signalling relevance to autophagy and inflammation. Results: The mTOR-dependent autophagic flux impairment in a murine model of colitis, human intestinal epithelial cells and active UC patients is probably regulated by TLR4-MyD88-MAPK signalling and the NF-κB pathway. Silencing mTOR remarkably attenuated, whereas inhibiting ATG5 aggravated, LPS-induced inflammation and oxidative injury. Pharmacological administration of mTOR inhibitors and autophagy stimulators markedly ameliorated experimental colitis and oxidative stress in vivo. Conclusions: Our findings not only shed light on the regulatory mechanism of mTOR-dependent autophagy, but also provided potential therapeutic targets for intestinal inflammatory diseases such as refractory inflammatory bowel disease. Keywords: Autophagy, mTOR, Inflammation, Oxidative stress
