title: Influence of serum amyloid A on the decrease of high density lipoprotein-cholesterol in active sarcoidosis.
abstract: OBJECTIVE
  We have previously observed low levels of high density lipoprotein (HDL) cholesterol in active sarcoidosis. The aim of this study was to analyze the role of serum amyloid A (SAA) on this lipid disorder.
  
  
  METHODS
  Eighty five untreated sarcoid patients, 40 with active disease and 45 with inactive disease, were recruited. Sarcoidosis activity was evaluated by means of clinical, chest X-ray, gallium-67 scan, serum angiotensin converting enzyme (peptidyl-dipeptidase A) values, and pulmonary function tests. Analysis of lipoprotein metabolism included: serum cholesterol, low density lipoprotein (LDL)-cholesterol, HDL-cholesterol, HDL(2)-cholesterol, HDL(3)-cholesterol, apolipoprotein A-I (apo A-I), apolipoprotein B (apo B), and triglyceride concentrations. Serum amyloid A protein and lecithin-cholesterol acyltransferase (LCAT) activity were measured.
  
  
  RESULTS
  In active sarcoidosis we found significantly reduced levels of HDL-cholesterol (1.17+/-0.36 vs. 1. 44+/-0.39 mmol/l, P=0.002), HDL(3)-cholesterol (0.78+/-0.23 vs. 1. 02+/-0.21 mmol/l, P<0.0001), and apo A-I (1.36+/-0.29 vs. 1.61+/-0. 27 g/l, P<0.0001) and significantly increased levels of triglyceride (1.51+/-0.64 vs. 1.03+/-0.46 mmol/l, P<0.0001), and apo B (1.14+/-0. 25 vs. 0.99+/-0.27 g/l, P=0.012) versus inactive sarcoidosis. Serum amyloid A concentrations were significantly increased in the patients with active disease (155.45+/-154.01 mg/ml) compared to the inactive sarcoid patients (89.70+/-65.36 mg/ml) (P=0.011). There were no significant differences in cholesterol, LDL-cholesterol, HDL(2)-cholesterol or LCAT values between groups. Multivariate logistic regression analysis showed that HDL-cholesterol (regression coefficient b=-1.96; S.E.=0.87; P=0.02) and SAA (regression coefficient b=0.01; S.E.=0.004; P=0.01) were the two variables independently associated with disease activity. Moreover, a significant negative correlation was observed between SAA levels and both HDL-cholesterol (r=-0.39; P=0.01) and apo A-I (r=-0.35; P=0.03) levels, in the active sarcoid group. Conversely, no correlation was found in the inactive sarcoid group.
  
  
  CONCLUSIONS
  The low HDL-cholesterol and apo A-I concentrations seen in active sarcoid patients are associated with a significant increase of SAA levels. We suggest that the displacement of apo A-I by SAA on HDL accounts for the lower level of HDL-cholesterol seen in active sarcoidosis.
authors.affiliation: Internal Medicine Service, Ciutat Sanitària de Bellvitge, University of Barcelona, C/Consell de Cent 218, 3 degrees 1a, 08011, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Salazar
authors.forename: J
authors.initials: J
authors.lastname: Maña
authors.forename: C
authors.initials: C
authors.lastname: Fiol
authors.forename: I
authors.initials: I
authors.lastname: Hurtado
authors.forename: J M
authors.initials: JM
authors.lastname: Argimon
authors.forename: R
authors.initials: R
authors.lastname: Pujol
authors.forename: X
authors.initials: X
authors.lastname: Pinto
mesh_terms: D000328:Adult; D008076:Cholesterol, HDL / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood; D012507:Sarcoidosis / Q000097:blood*; D000685:Serum Amyloid A Protein / Q000032:analysis*
chemical_list: D008076:Cholesterol, HDL; D000685:Serum Amyloid A Protein; D007862:Phosphatidylcholine-Sterol O-Acyltransferase