title: High-fat diet: bacteria interactions promote intestinal inflammation which precedes and correlates with obesity and insulin resistance in mouse.
abstract: BACKGROUND
  Obesity induced by high fat (HF) diet is associated with inflammation which contributes to development of insulin resistance. Most prior studies have focused on adipose tissue as the source of obesity-associated inflammation. Increasing evidence links intestinal bacteria to development of diet-induced obesity (DIO). This study tested the hypothesis that HF western diet and gut bacteria interact to promote intestinal inflammation, which contributes to the progression of obesity and insulin resistance.
  
  
  RESULTS
  Conventionally raised specific-pathogen free (CONV) and germ-free (GF) mice were given HF or low fat (LF) diet for 2-16 weeks. Body weight and adiposity were measured. Intestinal inflammation was assessed by evaluation of TNF-alpha mRNA and activation of a NF-kappaB(EGFP) reporter gene. In CONV but not GF mice, HF diet induced increases in body weight and adiposity. HF diet induced ileal TNF-alpha mRNA in CONV but not GF mice and this increase preceded obesity and strongly and significantly correlated with diet induced weight gain, adiposity, plasma insulin and glucose. In CONV mice HF diet also resulted in activation of NF-kappaB(EGFP) in epithelial cells, immune cells and endothelial cells of small intestine. Further experiments demonstrated that fecal slurries from CONV mice fed HF diet are sufficient to activate NF-kappaB(EGFP) in GF NF-kappaB(EGFP) mice.
  
  
  CONCLUSIONS
  Bacteria and HF diet interact to promote proinflammatory changes in the small intestine, which precede weight gain and obesity and show strong and significant associations with progression of obesity and development of insulin resistance. To our knowledge, this is the first evidence that intestinal inflammation is an early consequence of HF diet which may contribute to obesity and associated insulin resistance. Interventions which limit intestinal inflammation induced by HF diet and bacteria may protect against obesity and insulin resistance.
authors.affiliation: Department of Cell & Molecular Physiology, University of North Carolina at Chapel Hill, North Carolina, United States of America. shengli_ding@med.unc.edu
authors.forename: Shengli
authors.initials: S
authors.lastname: Ding
authors.forename: Michael M
authors.initials: MM
authors.lastname: Chi
authors.forename: Brooks P
authors.initials: BP
authors.lastname: Scull
authors.forename: Rachael
authors.initials: R
authors.lastname: Rigby
authors.forename: Nicole M J
authors.initials: NM
authors.lastname: Schwerbrock
authors.forename: Scott
authors.initials: S
authors.lastname: Magness
authors.forename: Christian
authors.initials: C
authors.lastname: Jobin
authors.forename: Pauline K
authors.initials: PK
authors.lastname: Lund
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001419:Bacteria; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight; D004041:Dietary Fats; D005786:Gene Expression Regulation; D007249:Inflammation / Q000150:complications / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D007333:Insulin Resistance; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D009765:Obesity / Q000150:complications* / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013047:Specific Pathogen-Free Organisms; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D015415:Biomarkers; D004041:Dietary Fats; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha
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