title: Interactions between smoking, pulmonary surfactant protein B, and atherosclerosis in the general population: the Dallas Heart Study.
abstract: OBJECTIVE
  Pulmonary surfactant protein B (SP-B), an alveolar protein normally detectable at only very low concentrations in blood, circulates at higher levels among smokers and those with alveolar injury and inflammation. We hypothesized that SP-B may serve as a marker of the vascular effects of smoking and would thus be associated with subclinical measures of atherosclerosis.
  
  
  RESULTS
  Plasma levels of SP-B were measured in 3294 subjects, ages 30 to 65, enrolled in the Dallas Heart Study, a probability-based population sample of Dallas County adults. Coronary artery calcium (CAC) was measured by computed tomography and abdominal aortic plaque (AP) by magnetic resonance imaging. The cohort comprised 29% current and 17% former smokers. The overall prevalence of CAC was 22%, and that of AP was 39%. Median SP-B levels were 5-fold higher among current versus never smokers (P<0.0001) and were significantly correlated with estimated pack-years smoked (Spearman ρ=0.35, P<0.0001). Increasing levels of SP-B also associated with other traditional cardiac risk factors and higher levels of inflammatory biomarkers. In univariable analyses, increasing SP-B quartiles associated with higher prevalence of both CAC and AP (P(trend)<0.0001 for each). In multivariable analyses adjusting for traditional cardiovascular risk factors, SP-B remained associated with AP (OR 1.87 for the 4th versus 1st quartiles, 95% confidence interval 1.39 to 2.51; P<0.0001) but not CAC. An interaction was observed between SP-B, smoking status, and AP (P(interaction)=0.01), such that SP-B associated with AP in current smokers (adjusted OR 2.15 for the 4th versus 1st quartile, 95% confidence interval 1.26 to 3.67; P=0.005) but not in former or never smokers.
  
  
  CONCLUSIONS
  Circulating levels of SP-B increase with greater smoking burden and independently associate with abdominal AP among current smokers. Our findings support further investigation of the role of SP-B as a marker of the vascular effects of smoking.
authors.affiliation: Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9047, USA.
authors.forename: Ann B
authors.initials: AB
authors.lastname: Nguyen
authors.forename: Anand
authors.initials: A
authors.lastname: Rohatgi
authors.forename: Christine K
authors.initials: CK
authors.lastname: Garcia
authors.forename: Colby R
authors.initials: CR
authors.lastname: Ayers
authors.forename: Sandeep R
authors.initials: SR
authors.lastname: Das
authors.forename: Susan G
authors.initials: SG
authors.lastname: Lakoski
authors.forename: Jarett D
authors.initials: JD
authors.lastname: Berry
authors.forename: Amit
authors.initials: A
authors.lastname: Khera
authors.forename: Darren K
authors.initials: DK
authors.lastname: McGuire
authors.forename: James A
authors.initials: JA
authors.lastname: de Lemos
mesh_terms: D000328:Adult; D000368:Aged; D001018:Aortic Diseases / Q000209:etiology; D050197:Atherosclerosis / Q000097:blood / Q000209:etiology*; D015415:Biomarkers; D002318:Cardiovascular Diseases / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000209:etiology; D037701:Pulmonary Surfactant-Associated Protein B / Q000097:blood*; D012907:Smoking / Q000009:adverse effects / Q000097:blood*
chemical_list: D015415:Biomarkers; D037701:Pulmonary Surfactant-Associated Protein B