title: Obesity modifies the association between plasma phospholipid polyunsaturated fatty acids and markers of inflammation: the Multi-Ethnic Study of Atherosclerosis.
abstract: OBJECTIVE
  Systemic inflammation is a well-known risk factor for diseases such as atherosclerosis and is augmented by the presence of obesity. In addition, it has been shown that inflammation may be negatively influenced by certain macronutrients, specifically the omega-3 and omega-6 fatty acids. The primary aim of this study is to determine whether obesity modifies the association between plasma phospholipid polyunsaturated fatty acids (PUFAs) and markers of inflammation and endothelial activation in Multi-Ethnic Study of Atherosclerosis (MESA) participants.
  
  
  METHODS
  A sample of 2848 adults (25% African American, Chinese, Hispanic, and White) randomly selected from the MESA cohort.
  
  
  METHODS
  Relative plasma PUFA concentrations were determined using gas chromatography-flame ionization detection. Levels of three inflammatory markers (high-sensitivity C-reactive protein, interleukin (IL)-6 and tumor necrosis factor-receptor 1) and two endothelial activation markers (soluble intercellular adhesion molecule-1 (sICAM-1) and E-selectin) were determined with enzyme immunoassays. Linear regression analysis was used to evaluate the relationship between these markers and plasma PUFAs.
  
  
  RESULTS
  Obesity modified the associations of linoleic acid (P(int)=0.01), dihomo-γ-linolenic (P(int)=0.07) and eicosapentaenoic acid (EPA) (P(int)=0.04) with sICAM-1 concentrations; in addition, obesity modified the association of IL-6 with dihomo-γ-linolenic (P(int)=0.01). In obese individuals, sICAM-1 was inversely related to EPA levels (P=0.02), but directly related to linoleic acid levels (P<0.001). Conversely, sICAM-1 was inversely related to linoleic acid levels in normal weight individuals (P=0.04). IL-6 concentrations were significantly and directly related to dihomo-γ-linolenic acid (DGLA) in normal weight (P=0.01) and obese participants (P<0.001), but the scale of increase across tertiles was greater in obese adults. Main effects of fatty acid and inflammatory marker associations are also reported.
  
  
  CONCLUSIONS
  The modifying effect of obesity on the association of plasma PUFAs with IL-6 and sICAM-1 suggests differences in fatty acid metabolism and may also have implications in dietary fatty acid intake for obese individuals, particularly for linoleic and EPAs. Further study is warranted to confirm and explain the strong associations of DGLA with inflammatory and endothelial activation markers.
authors.affiliation: Department of Laboratory Medicine & Pathology, University of Minnesota, 420 Delaware Street SE, Minneapolis, MN, USA.
authors.forename: B T
authors.initials: BT
authors.lastname: Steffen
authors.forename: L M
authors.initials: LM
authors.lastname: Steffen
authors.forename: R
authors.initials: R
authors.lastname: Tracy
authors.forename: D
authors.initials: D
authors.lastname: Siscovick
authors.forename: N Q
authors.initials: NQ
authors.lastname: Hanson
authors.forename: J
authors.initials: J
authors.lastname: Nettleton
authors.forename: M Y
authors.initials: MY
authors.lastname: Tsai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000097:blood* / Q000208:ethnology / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D015331:Cohort Studies; D018450:Disease Progression; D019040:E-Selectin / Q000097:blood*; D004730:Endothelium, Vascular / Q000378:metabolism*; D015525:Fatty Acids, Omega-3 / Q000097:blood*; D043371:Fatty Acids, Omega-6 / Q000097:blood*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000097:blood*; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D016014:Linear Models; D019787:Linoleic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000208:ethnology / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D019040:E-Selectin; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; C573420:ICAM1 protein, human; D015850:Interleukin-6; C546936:SELE protein, human; D018799:Intercellular Adhesion Molecule-1; D002097:C-Reactive Protein; D019787:Linoleic Acid