Surfactant Protein A, Exposure to Endotoxin, and Asthma in Garbage Collectors and in Wastewater Workers

Abstract

Endotoxin causes an inflammation at the bronchial and alveolar level. The inflammation-induced increase in permeability of the bronchoalveolar epithelial barrier is supposed to cause a leakage of pneumoproteins. Therefore, their concentrations are expected to increase in the bloodstream. This study aimed at examining the association between occupational exposure to endotoxin and a serum pneumoprotein, surfactant protein A, to look for nonoccupational factors capable of confounding this association, and examine the relation between surfactant protein A and spirometry. There were 369 control subjects, 325 wastewater workers, and 84 garbage collectors in the study. Exposure to endotoxin was assessed through personal sampling and the Limulus amebocytes lysate assay. Surfactant protein A was determined by an in house sandwich enzyme-linked immunosorbent assay (ELISA) in 697 subjects. Clinical and smoking history were ascertained and spirometry carried out according to American Thoracic Society criteria. Multiple linear regression was used for statistical analysis. Exposure was fairly high during some tasks in wastewater workers but did not influence surfactant protein A. Surfactant protein A was lower in asthmatics. Interindividual variability was large. No correlation with spirometry was found. Endotoxin has no effect on surfactant protein A at these endotoxin levels and serum surfactant protein A does not correlate with spirometry. The decreased surfactant protein A secretion in asthmatics requires further study.

Pneumoproteins in sewage workers exposed to sewage dust

“…In contrast to the present study where exposure measurements and blood sampling were performed on the same day , the exposure measurements were carried out at the beginning of that study. The authors concluded that exposure to organic dust containing endotoxins did not affect the lung-specific proteins, although earlier reports from the same cohort found increased serum concentrations of CC16 and lower SP-A concentrations in asthmatics (Steiner et al 2005; Widmeier et al 2007). This is contradictory to the findings in the present study where lower concentrations of CC16 were observed in exposed workers and no group differences were found in the SP-A concentrations.…”

“…Higher concentrations of CC16 compared to a control group were found among sewage workers (Steiner et al 2005), and a lower SP-A was found among asthmatic workers (Widmeier et al 2007). However, no associations between the exposure measurements and surfactant proteins were reported (Steiner et al 2005; Widmeier et al 2007; Tabrizi et al 2010; Tchopp et al 2011). …”

Surfactant protein-D and exposure to bioaerosols in wastewater and garbage workers

“…All workers were informed about the purposes of the risk assessment and gave written consent. A detailed description of population and methods has been given previously with the results of the SP-A, SP-B, and CC16 measurements (Steiner et al 2005;Widmeier et al 2007), so only the main aspects will be brieXy summarized here.…”

“…Determinations of serum creatinine (S-creatinine), CC16, SP-B, and SPA have been described elsewhere (Steiner et al 2005;Widmeier et al 2007). …”

Health Effects Associated with Wastewater Treatment, Reuse, and Disposal

“…A health survey was conducted in Wood County, Ohio, near farm fields that were permitted to receive biosolids (Khuder et al, 2007). The statistical analysis showed significantly elevated risks for certain respiratory, A study was conducted to examine the possible association between occupational exposure to endotoxin and a serum pneumoprotein, surfactant protein A (Widmeier et al, 2007). Although the exposure was high during some tasks in wastewater workers, that did not affect the levels of surfactant protein A, as measured by an enzyme-linked immunosorbent assay.…”