title: Metformin Improves Ileal Epithelial Barrier Function in Interleukin-10 Deficient Mice.
abstract: OBJECTIVE
  The impairment of intestinal epithelial barrier is the main etiologic factor of inflammatory bowel disease. The proper intestinal epithelial proliferation and differentiation is crucial for maintaining intestinal integrity. Metformin is a common anti-diabetic drug. The objective is to evaluate the protective effects of metformin on ileal epithelial barrier integrity using interleukin-10 deficient (IL10KO) mice.
  
  
  METHODS
  Wild-type and IL10KO mice were fed with/without metformin for 6 weeks and then ileum was collected for analyses. The mediatory role of AMP-activated protein kinase (AMPK) was further examined by gain and loss of function study in vitro.
  
  
  RESULTS
  Compared to wild-type mice, IL10KO mice had increased proliferation, reduced goblet cell and Paneth cell lineage differentiation in the ileum tissue, which was accompanied with increased crypt expansion. Metformin supplementation mitigated intestinal cell proliferation, restored villus/crypt ratio, increased goblet cell and Paneth cell differentiation and improved barrier function. In addition, metformin supplementation in IL10KO mice suppressed macrophage pro-inflammatory activity as indicated by reduced M1 macrophage abundance and decreased pro-inflammatory cytokine IL-1β, TNF-α and IFN-γ expressions. As a target of metformin, AMPK phosphorylation was enhanced in mice treated with metformin, regardless of mouse genotypes. In correlation, the mRNA level of differentiation regulator including bmp4, bmpr2 and math1 were also increased in IL10KO mice supplemented with metformin, which likely explains the enhanced epithelial differentiation in IL10KO mice with metformin. Consistently, in Caco-2 cells, metformin promoted claudin-3 and E-cadherin assembly and mitigated TNF-α-induced fragmentation of tight junction proteins. Gain and loss of function assay also demonstrated AMPK was correlated with epithelial differentiation and proliferation.
  
  
  CONCLUSIONS
  Metformin supplementation promotes secretory cell lineage differentiation, suppresses inflammation and improves epithelial barrier function in IL10KO mice likely through activation of AMPK, showing its beneficial effects on gut epithelial.
authors.affiliation: School of Food Science, Washington State University, Pullman, Washington, United States of America.|School of Food Science, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Yansong
authors.initials: Y
authors.lastname: Xue
authors.affiliation: School of Food Science, Washington State University, Pullman, Washington, United States of America.
authors.forename: Hanying
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Food Science, Washington State University, Pullman, Washington, United States of America.|School of Food Science, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Sun
authors.affiliation: School of Food Science, Washington State University, Pullman, Washington, United States of America.|School of Food Science, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Mei-Jun
authors.initials: MJ
authors.lastname: Zhu
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D052006:Bone Morphogenetic Protein Receptors, Type II / Q000235:genetics / Q000378:metabolism; D018938:Caco-2 Cells; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D062465:Claudin-3 / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D020397:Goblet Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D016753:Interleukin-10 / Q000172:deficiency* / Q000235:genetics*; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008687:Metformin / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010539:Permeability / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D055372:AMP-Activated Protein Kinases; D051792:Basic Helix-Loop-Helix Proteins; D055415:Bone Morphogenetic Protein 4; D052006:Bone Morphogenetic Protein Receptors, Type II; D015820:Cadherins; D062465:Claudin-3; D016207:Cytokines; D016753:Interleukin-10; D008687:Metformin; D014409:Tumor Necrosis Factor-alpha; C500943:Atoh1 protein, mouse; C525810:Bmp4 protein, mouse; C498219:Bmpr2 protein, mouse