title: Inactivation of C/ebp homologous protein-driven immune-metabolic interactions exacerbate obesity and adipose tissue leukocytosis.
abstract: Successful adaptation to periods of chronic caloric excess is a highly coordinated event that is critical to the survival and propagation of species. Transcription factor C/ebp homologous protein (Chop) is thought to be an important molecular mediator that integrates nutrient signals to endoplasmic reticulum (ER) stress and innate immune activation. Given that aberrant ER stress response is implicated in inducing metabolic inflammation and insulin resistance, we hypothesized that ER stress target gene Chop integrates immune and metabolic systems to adapt to chronic positive energy balance. Here we report that inactivation of Chop in mice fed a high fat diet led to significant increase in obesity caused by a reduction in energy expenditure without any change in food intake. Importantly, ablation of Chop does not induce metabolically healthy obesity, because Chop-deficient mice fed a high fat diet had increased hepatic steatosis with significantly higher insulin resistance. Quantification of adipose tissue leukocytosis revealed that elimination of Chop during obesity led to substantial increase in number of adipose tissue T and B lymphocytes. In addition, deficiency of Chop led to increase in total number of myeloid subpopulations like neutrophils and F4/80(+) adipose tissue macrophages without any alterations in the frequency of M1- or M2-like adipose tissue macrophages. Further investigation of inflammatory mechanisms revealed that ablation of Chop increases the sensitivity of macrophages to inflammasome-induced activation of IL-β in macrophages. Our findings indicate that regulated expression of Chop during obesity is critical for adaptation to chronic caloric excess and maintenance of energy homeostasis via integration of metabolic and immune systems.
authors.affiliation: From the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808 and.
authors.forename: Ryan
authors.initials: R
authors.lastname: Grant
authors.affiliation: the Section of Comparative Medicine and Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520.
authors.forename: Kim Y
authors.initials: KY
authors.lastname: Nguyen
authors.affiliation: the Section of Comparative Medicine and Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520.
authors.forename: Anthony
authors.initials: A
authors.lastname: Ravussin
authors.affiliation: From the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808 and.
authors.forename: Diana
authors.initials: D
authors.lastname: Albarado
authors.affiliation: the Section of Comparative Medicine and Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520.
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Youm
authors.affiliation: From the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana 70808 and the Section of Comparative Medicine and Department of Immunobiology, Yale School of Medicine, New Haven, Connecticut 06520 Vishwa.Dixit@yale.edu.
authors.forename: Vishwa Deep
authors.initials: VD
authors.lastname: Dixit
mesh_terms: D000273:Adipose Tissue / Q000276:immunology*; D000818:Animals; D004734:Energy Metabolism; D017353:Gene Deletion; D058847:Inflammasomes / Q000378:metabolism; D007964:Leukocytosis / Q000276:immunology* / Q000378:metabolism*; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D009765:Obesity / Q000276:immunology* / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology; D051742:Transcription Factor CHOP / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D058847:Inflammasomes; D051742:Transcription Factor CHOP
keywords: Adipose Tissue Metabolism; Cell Metabolism; Energy Metabolism; Immunology; Inflammation; Insulin Resistance