title: Circulating plasma surfactant protein type B as biological marker of alveolar-capillary barrier damage in chronic heart failure.
abstract: BACKGROUND
  Surfactant protein type B (SPB) is needed for alveolar gas exchange. SPB is increased in the plasma of patients with heart failure (HF), with a concentration that is higher when HF severity is highest. The aim of this study was to evaluate the relationship between plasma SPB and both alveolar-capillary diffusion at rest and ventilation versus carbon dioxide production during exercise.
  
  
  RESULTS
  Eighty patients with chronic HF and 20 healthy controls were evaluated consecutively, but the required quality for procedures was only reached by 71 patients with HF and 19 healthy controls. Each subject underwent pulmonary function measurements, including lung diffusion for carbon monoxide and membrane diffusion capacity, and maximal cardiopulmonary exercise test. Plasma SPB was measured by immunoblotting. In patients with HF, SPB values were higher (4.5 [11.1] versus 1.6 [2.9], P=0.0006, median and 25th to 75th interquartile), whereas lung diffusion for carbon monoxide (19.7+/-4.5 versus 24.6+/-6.8 mL/mm Hg per min, P<0.0001, mean+/-SD) and membrane diffusion capacity (28.9+/-7.4 versus 38.7+/-14.8, P<0.0001) were lower. Peak oxygen consumption and ventilation/carbon dioxide production slope were 16.2+/-4.3 versus 26.8+/-6.2 mL/kg per min (P<0.0001) and 29.7+/-5.9 and 24.5+/-3.2 (P<0.0001) in HF and controls, respectively. In the HF population, univariate analysis showed a significant relationship between plasma SPB and lung diffusion for carbon monoxide, membrane diffusion capacity, peak oxygen consumption, and ventilation/carbon dioxide production slope (P<0.0001 for all). On multivariable logistic regression analysis, membrane diffusion capacity (beta, -0.54; SE, 0.018; P<0.0001), peak oxygen consumption (beta, -0.53; SE, 0.036; P=0.004), and ventilation/carbon dioxide production slope (beta, 0.25; SE, 0.026; P=0.034) were independently associated with SPB.
  
  
  CONCLUSIONS
  Circulating plasma SPB levels are related to alveolar gas diffusion, overall exercise performance, and efficiency of ventilation showing a link between alveolar-capillary barrier damage, gas exchange abnormalities, and exercise performance in HF.
authors.affiliation: Centro Cardiologico Monzino-IRCCS, Istituto di Cardiologia, Università di Milano, Milan, Italy.
authors.forename: Damiano
authors.initials: D
authors.lastname: Magrì
authors.forename: Maura
authors.initials: M
authors.lastname: Brioschi
authors.forename: Cristina
authors.initials: C
authors.lastname: Banfi
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Schmid
authors.forename: Pietro
authors.initials: P
authors.lastname: Palermo
authors.forename: Mauro
authors.initials: M
authors.lastname: Contini
authors.forename: Anna
authors.initials: A
authors.lastname: Apostolo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bussotti
authors.forename: Elena
authors.initials: E
authors.lastname: Tremoli
authors.forename: Susanna
authors.initials: S
authors.lastname: Sciomer
authors.forename: Gaia
authors.initials: G
authors.lastname: Cattadori
authors.forename: Cesare
authors.initials: C
authors.lastname: Fiorentini
authors.forename: Piergiuseppe
authors.initials: P
authors.lastname: Agostoni
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002199:Capillary Permeability; D002245:Carbon Dioxide / Q000378:metabolism; D016022:Case-Control Studies; D002908:Chronic Disease; D004058:Diffusion; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000503:physiopathology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011650:Pulmonary Alveoli / Q000098:blood supply*; D037701:Pulmonary Surfactant-Associated Protein B / Q000097:blood*; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D037701:Pulmonary Surfactant-Associated Protein B; D002245:Carbon Dioxide