ABSTRACT
ObjectiveTo investigate the relationship between plasma surfactant protein⁃A （SP⁃A） expression level and silicosis progression， and to provide early evidence for exploring whether SP⁃A can be used as a biomarker for clinical monitoring of silicosis disease progression. MethodsWe recruited 187 silicosis patients in Guangdong Province hospital for occupational disease prevention and treatment between November， 2019 and November，2020. Their peripheral venous blood samples were collected for the plasma isolation. The level of pulmonary SP⁃A was detected by enzyme-linked immunosorbent assay. ResultsThere was a statistically significant difference in the level of SP⁃A among the silicosis groups （P<0.05）， and the plasma SP-A level of the silicosis patients in stage Ⅲ was higher than that in stage Ⅰ and stage Ⅱ （P<0.05）. Smoking had effect on plasma SP⁃A levels， Age， working years and drinking had no effect on plasma SP⁃A levels. ConclusionThe expression level of SP⁃A in the plasma of silicosis patients is increased， which has a certain correlation with the disease stage， and plays a certain early warning role in the occurrence and development of silicosis， and may be a potential biomarker for the diagnosis and prognosis of silicosis.
ABSTRACT
A pulmonary surfactant reduces surface tension at the air/liquid interface of the alveoli and stabilizes alveoli at low lung volumes. Surfactant deficiency and dysfunction were shown to be present in a number of pulmonary diseases, and surfactant replacement therapy is the common clinical conduct. The hydrophilic SP-A (surfactant protein A) is absent when solvent extraction was used during exogenous surfactant production. Addition of SP-A to the surfactant preparation increases the surface activity and completely counteracts inhibition by blood proteins. SP-A recognizes and binds to carbohydrate structures on the surfaces of pathogenic micro-organisms, and acts as opsonins or cross-linking molecules by binding to a variety of cells that participate in the pulmonary immune response. The purification procedure yielded 206 mg of high-purity SP-A/kg of porcine lung, as judged by gel filtration, SDS/PAGE and Western blotting. The electrophoretic profiles obtained showed that pure SP-A consists of proteins of wide molecular mass in the range 26-36 kDa and a dimer in the range 56-60 kDa. The Western-blot results displayed the same band pattern profile after incubating the membrane using a commercially available polyclonal anti-SP-A antibody produced in goat. Gel-filtration experiments confirmed the molecular mass of SP-A in 10 mM NaCl solution. The isolated SP-A showed mannose-binding ability, representative of its functionality.
