title: A potential role for dendritic cell/macrophage-expressing DPP4 in obesity-induced visceral inflammation.
abstract: Dipeptidyl peptidase-4 (DDP4) inhibitors target the enzymatic degradation of incretin peptides and represent a major advance in the treatment of type 2 diabetes. DPP4 has a number of nonenzymatic functions that involve its interaction with adenosine deaminase (ADA) and other extracellular matrix proteins. Here, we assessed the nonenzymatic role of DPP4 in regulating dendritic cell (DC)/macrophage-mediated adipose inflammation in obesity. Both obese humans and rodents demonstrated increased levels of DPP4 expression in DC/macrophage cell populations from visceral adipose tissue (VAT). The DPP4 expression increased during monocyte differentiation to DC/macrophages and with lipopolysaccharide (LPS)-induced activation of DC/macrophages. The DPP4 colocalized with membrane-bound ADA on human DCs and enhanced the ability of the latter to stimulate T-cell proliferation. The DPP4 interaction with ADA in human DC/macrophages was competitively inhibited by the addition of exogenous soluble DPP4. Knockdown of DPP4 in human DCs, but not pharmacologic inhibition of their enzymatic function, significantly attenuated the ability to activate T cells without influencing its capacity to secrete proinflammatory cytokines. The nonenzymatic function of DPP4 on DC may play a role in potentiation of inflammation in obesity by interacting with ADA. These findings suggest a novel role for the paracrine regulation of inflammation in adipose tissue by DPP4.
authors.affiliation: Davis Heart & Lung Research Institute, The Ohio State University Medical Center, Columbus, Ohio, USA.
authors.forename: Jixin
authors.initials: J
authors.lastname: Zhong
authors.forename: Xiaoquan
authors.initials: X
authors.lastname: Rao
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Deiuliis
authors.forename: Zachary
authors.initials: Z
authors.lastname: Braunstein
authors.forename: Vimal
authors.initials: V
authors.lastname: Narula
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hazey
authors.forename: Dean
authors.initials: D
authors.lastname: Mikami
authors.forename: Bradley
authors.initials: B
authors.lastname: Needleman
authors.forename: Abhay R
authors.initials: AR
authors.lastname: Satoskar
authors.forename: Sanjay
authors.initials: S
authors.lastname: Rajagopalan
mesh_terms: D000243:Adenosine Deaminase / Q000378:metabolism; D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology; D003713:Dendritic Cells / Q000502:physiology*; D018819:Dipeptidyl Peptidase 4 / Q000502:physiology*; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000494:pharmacology; D006801:Humans; D007249:Inflammation / Q000209:etiology*; D050152:Intra-Abdominal Fat / Q000473:pathology*; D008213:Lymphocyte Activation; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000150:complications*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D054873:Dipeptidyl-Peptidase IV Inhibitors; D018819:Dipeptidyl Peptidase 4; C545245:Dpp4 protein, mouse; D000243:Adenosine Deaminase