title: Human monocytes accelerate proliferation and blunt differentiation of preadipocytes in association with suppression of C/EBPΑ mRNA.
abstract: Obesity, type 2 diabetes, and HIV-associated lipodystrophy are associated with abnormalities in adipocyte growth and differentiation. In persons with these conditions, adipose depots contain increased numbers of macrophages, but the origins of these cells and their specific effects are uncertain. Peripheral blood mononuclear cells (PBMC)-derived monocytes, but not T cells, cocultured via transwells with primary subcutaneous preadipocytes, increased proliferation (approximately twofold) and reduced differentiation (~50%) of preadipocytes. Gene expression analyses in proliferating preadipocytes (i.e., prior to hormonal induction of terminal differentiation) revealed that monocytes down-regulated mRNA levels of CCAAT/enhancer binding protein, alpha (C/EBPα) and up-regulated mRNA levels of G0/G1 switch 2 (G0S2) message, genes important for the regulation of adipogenesis and the cell cycle. These data indicate that circulating peripheral blood monocytes can disrupt adipogenesis by interfering with a critical step in C/EBPα and G0S2 transcription required for preadipocytes to make the transition from proliferation to differentiation. Interactions between preadipocytes and monocytes also increased the inflammatory cytokines IL-6 and IL-8, as well as a novel chemotactic cytokine, CXCL1. Additionally, the levels of both IL-6 and CXCL1 were highest when preadipocytes and monocytes were cultured together, compared to each cell in culture alone. Such cross-talk amplifies the production of mediators of tissue inflammation.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, The University of Texas Medical School at Houston, Houston, Texas, USA.
authors.forename: Jacob
authors.initials: J
authors.lastname: Couturier
authors.forename: Sanjeet G
authors.initials: SG
authors.lastname: Patel
authors.forename: Dinakar
authors.initials: D
authors.lastname: Iyer
authors.forename: Ashok
authors.initials: A
authors.lastname: Balasubramanyam
authors.forename: Dorothy E
authors.initials: DE
authors.lastname: Lewis
mesh_terms: D017667:Adipocytes; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism; D015153:Blotting, Western; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D049109:Cell Proliferation; D054360:Chemokine CXCL1 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D039682:HIV-Associated Lipodystrophy Syndrome / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; C475829:CXCL1 protein, human; D054360:Chemokine CXCL1; D016207:Cytokines; D015850:Interleukin-6; D016209:Interleukin-8; D012333:RNA, Messenger