title: Sfrp5 correlates with insulin resistance and oxidative stress.
abstract: BACKGROUND
  Secreted frizzled-related protein 5 (Sfrp5) has been described as novel adipokine in mice with insulin-sensitising and anti-inflammatory properties similar to adiponectin. The aim of this study was to compare serum concentrations and determinants of Sfrp5, its pro-inflammatory antagonist wingless-type MMTV integration site family member (Wnt)5a and adiponectin in humans and their regulation by coffee.
  
  
  METHODS
  Serum concentrations of Sfrp5, Wnt5a and adiponectin were measured in 47 individuals who participated in a coffee intervention study. Associations with demographic, metabolic and immunological variables and regulation of serum levels by different amounts of daily coffee intake were analysed.
  
  
  RESULTS
  At baseline, fasting serum Sfrp5 levels ranged between 96 and 4056 ng/mL. Sfrp5 was directly correlated with a surrogate of insulin resistance (homeostasis model assessment of insulin resistance/HOMA-IR; r = 0·32, P < 0·05) and with the oxidative stress markers 8-isoprostane (r = 0·44, P < 0·01) and nitrotyrosine (r = 0·52, P < 0·001). Adiponectin showed inverse correlations with several indices of insulin resistance (e.g. HOMA-IR, Stumvoll index; all P < 0·05) and a direct correlation with the anti-atherogenic apolipoprotein A-I (r = 0·56, P < 0·001). Coffee did not affect serum concentrations of Sfrp5. Serum Wnt5a concentrations were below the detection limit (0·02 ng/mL) in 81% of the study participants.
  
  
  CONCLUSIONS
  In contrast to obese mouse models, serum Sfrp5 was directly related to HOMA-IR and oxidative stress in humans, but not with apolipoproteins, and thus, associations differed from those found for circulating adiponectin. These differences between Sfrp5 and adiponectin might be explained by differences in the investigated species.
authors: Institute for Clinical Diabetology, German Diabetes Center, Düsseldorf, Germany.
authors: Maren
authors: M
authors: Carstensen
authors: Christian
authors: C
authors: Herder
authors: Kerstin
authors: K
authors: Kempf
authors: Iris
authors: I
authors: Erlund
authors: Stephan
authors: S
authors: Martin
authors: Wolfgang
authors: W
authors: Koenig
authors: Jouko
authors: J
authors: Sundvall
authors: Siamak
authors: S
authors: Bidel
authors: Suvi
authors: S
authors: Kuha
authors: Michael
authors: M
authors: Roden
authors: Jaakko
authors: J
authors: Tuomilehto
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D052242:Adiponectin / Q000097:blood; D000818:Animals; D015992:Body Mass Index; D002986:Clinical Trials as Topic; D003069:Coffee; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D005136:Eye Proteins / Q000097:blood*; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008565:Membrane Proteins / Q000097:blood*; D051379:Mice; D008875:Middle Aged; D023421:Models, Animal; D009765:Obesity; D018384:Oxidative Stress / Q000187:drug effects*; D011518:Proto-Oncogene Proteins / Q000097:blood; D013223:Statistics as Topic; D014443:Tyrosine / Q000031:analogs & derivatives / Q000097:blood; D051153:Wnt Proteins / Q000097:blood; D060449:Wnt Signaling Pathway / Q000187:drug effects; D000071818:Wnt-5a Protein; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D052242:Adiponectin; D003069:Coffee; D015237:Dinoprost; D005136:Eye Proteins; D007328:Insulin; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; C118511:SFRP5 protein, human; D000094742:Secreted Frizzled-Related Proteins; C085389:WNT5A protein, human; C075750:8-epi-prostaglandin F2alpha; C002744:3-nitrotyrosine