title: C3 and C4 are strongly related to adipose tissue variables and cardiovascular risk factors.
abstract: BACKGROUND
  In several reports, C3 and C4 have been linked to diabetes and cardiovascular disease (CVD). Here, we investigate this link and the degree of C3 activation in elderly individuals.
  
  
  METHODS
  In this study, C3 and C4 and the activation fragment C3a-desArg were analysed in 1016 subjects aged 70, in which blood pressure, lipid variables and fasting blood glucose were assessed.
  
  
  RESULTS
  C3 levels were related to all the investigated classical cardiovascular risk factors and the metabolic syndrome (BMI, waist circumference, fat distribution, blood pressure, blood glucose levels, TG) except total cholesterol and LDL cholesterol in a highly significant fashion (Spearman up to 0,5; P < 0·0001). C4 and C3a-desArg were associated in the same fashion but less significantly, while the ratios C4/C3 or C3a-desArg/C3 were not, indicating that the association was not directly related to complement activation. The levels C3 and to a lesser degree C4 and C3a-desArg were associated particularly with CRP, but also with E-selectin and ICAM-1. In addition, C3 and C4 levels were shown to decline significantly in 15 female subjects enrolled in a weight-reduction programme over 4 months.
  
  
  CONCLUSIONS
  A strong relation between C3, C4 and C3a-desArg levels, adipose tissue and risk factors of CVD was established. The data support that the adipose tissue produces complement components and generates initiators of inflammation, such as C3a and C5a, able to trigger a cyto/chemokine response, in proportion to the amount of adipose tissue. This corroborates the concept that complement contributes to the low-grade inflammation associated with obesity.
authors.affiliation: Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
authors.forename: Bo
authors.initials: B
authors.lastname: Nilsson
authors.forename: Osama A
authors.initials: OA
authors.lastname: Hamad
authors.forename: Håkan
authors.initials: H
authors.lastname: Ahlström
authors.forename: Joel
authors.initials: J
authors.lastname: Kullberg
authors.forename: Lars
authors.initials: L
authors.lastname: Johansson
authors.forename: Lars
authors.initials: L
authors.lastname: Lindhagen
authors.forename: Arvo
authors.initials: A
authors.lastname: Haenni
authors.forename: Kristina N
authors.initials: KN
authors.lastname: Ekdahl
authors.forename: Lars
authors.initials: L
authors.lastname: Lind
mesh_terms: D050153:Abdominal Fat / Q000378:metabolism*; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000378:metabolism; D003176:Complement C3 / Q000378:metabolism*; D003181:Complement C4 / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism; D009765:Obesity / Q000150:complications / Q000378:metabolism; D012307:Risk Factors; D049629:Waist-Hip Ratio; D015431:Weight Loss / Q000502:physiology
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D003176:Complement C3; D003181:Complement C4; D016207:Cytokines
keywords: C3; C3a-desArg; C4; cardiovascular disease; metabolic syndrome