title: Adipocyte P2X7 receptors expression: a role in modulating inflammatory response in subjects with metabolic syndrome?
abstract: OBJECTIVE
  P2X(7) receptor (P2X(7)R), upon its stimulation with extracellular ATP, modulates several inflammatory responses in different cell types. No information is available on its presence in human adipocytes and its potential involvement in the chronic inflammation associated with metabolic syndrome (MS). Therefore, we evaluated P2X(7)R presence and functional activity in adipocytes from visceral (VAT) and subcutaneous (SAT) adipose tissue of patients with MS and controls (CTL).
  
  
  METHODS
  Adipocyte gene expression of TNFα, IL-6 and PAI-1 (by realtime-PCR) and their plasma concentrations (ELISA); P2X(7)R expression (realtime-PCR, Western blot and immunofluorescence); P2X(7)R functional activity (intracellular calcium fluxes by fluorimetry); cytokine release from adipocytes (ELISA). The inflammasome components were also determined.
  
  
  RESULTS
  In VAT, TNFα, IL-6 and PAI-1 were more expressed in MS than in CTL. These differences were confirmed in SAT for IL-6 and PAI-1. Plasma IL-6, PAI-1 and TNFα levels were higher in MS. P2X(7)R mRNA and protein, identified in both VAT and SAT, were more abundant in MS than in CTL. Immunofluoresce confirmed the typical "ring-like" arrangement of P2X(7)R at the plasma membrane. Benzoyl-benzoyl-ATP raised intracellular calcium both in VAT and SAT, and induced IL-6, TNFα and PAI-1 release in both MS and CTL cells. This effect was partially inhibited by KN62, specific human P2X(7)R blocker, or by P2X(7)R gene silencing. The inflammasome was more activated in MS than in CTL adipocytes.
  
  
  CONCLUSIONS
  Human adipocytes express functionally active P2X(7)R, which modulate the release of inflammatory cytokines, at least in part via inflammasome activation. Adipocytes from MS patients show an enhanced P2X(7)R expression, which might contribute to the subclinical inflammatory status characterizing these patients and conferring them an increased CV risk.
authors: Department of Internal Medicine University of Pisa, Italy.
authors: Stephanie
authors: S
authors: Madec
authors: Chiara
authors: C
authors: Rossi
authors: Massimo
authors: M
authors: Chiarugi
authors: Eleonora
authors: E
authors: Santini
authors: Antonio
authors: A
authors: Salvati
authors: Ele
authors: E
authors: Ferrannini
authors: Anna
authors: A
authors: Solini
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D017667:Adipocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D000368:Aged; D015153:Blotting, Western; D020013:Calcium Signaling; D016022:Case-Control Studies; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018836:Inflammation Mediators / Q000097:blood; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics; D050152:Intra-Abdominal Fat / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D007558:Italy; D024821:Metabolic Syndrome / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood / Q000235:genetics; D058911:Purinergic P2X Receptor Agonists / Q000494:pharmacology; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D058486:Receptors, Purinergic P2X7 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050151:Subcutaneous Fat / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000235:genetics; D015854:Up-Regulation
chemical_list: C508600:IL6 protein, human; D058847:Inflammasomes; D018836:Inflammation Mediators; D015850:Interleukin-6; D017395:Plasminogen Activator Inhibitor 1; D058911:Purinergic P2X Receptor Agonists; D058920:Purinergic P2X Receptor Antagonists; D012333:RNA, Messenger; D058486:Receptors, Purinergic P2X7; C051321:SERPINE1 protein, human; D014409:Tumor Necrosis Factor-alpha; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; C063302:KN 62; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate