Circulating plasma surfactant protein type B as biological marker of alveolar-capillary barrier damage in chronic heart failure.
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.
Magrì
Damiano
D
Centro Cardiologico Monzino-IRCCS, Istituto di Cardiologia, Università di Milano, Milan, Italy.
Brioschi
Maura
M
Banfi
Cristina
C
Schmid
Jean Paul
JP
Palermo
Pietro
P
Contini
Mauro
M
Apostolo
Anna
A
Bussotti
Maurizio
M
Tremoli
Elena
E
Sciomer
Susanna
S
Cattadori
Gaia
G
Fiorentini
Cesare
C
Agostoni
Piergiuseppe
P
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
D015415:Biomarkers; D037701:Pulmonary Surfactant-Associated Protein B; D002245:Carbon Dioxide