SHORT REPORTS

Circulating lipopolysaccharides in the blood from "bioprotein" production workers

L I B Sikkeland^1,2, M Skogstad³, R Øvstebø⁴, B Brusletto⁴, K B F Haug⁴, J Kongerud^1,5, W Eduard³, P Kierulf⁴

¹ Department of Respiratory Medicine, Faculty Division Rikshospitalet, University of Oslo, Oslo, Norway
² Centre for Occupational and Environmental Medicine, Rikhospitalet University Hospital, Oslo, Norway
³ National Institute of Occupational Health, Oslo, Norway
⁴ The R&D Group, Department of Clinical Chemistry, Ullevaal University Hospital,Oslo, Norway
⁵ Department of Respiratory Medicine, Rikshospitalet University Hospital, Oslo, Norway

Liv I B Sikkeland, Centre for Occupational and Environmental Medicine, Rikshospitalet University Hospital, 0027 Oslo, Norway; liv.sikkeland{at}rikshospitalet.no

Background: Workers producing bacterial single-cell protein (BSCP), "bioprotein," are exposed to organic dust containing high levels of endoxins (lipopolysaccharides, LPS). Workers in this industry have complained of episodes of fever, fatigue, chest tightness, skin dryness and rubor. The aim of the present study was to quantify LPS and inflammatory mediators in plasma among the workers and non-exposed control subjects.

Methods: We included eight non-smoking production workers, aged 32–51 (median 38), and eight non-smoking, non-exposed controls, aged 30–51 (median 39). Airborne and plasma endotoxin concentrations were measured, as well as plasma hsCRP and different cytokines, chemokines and metalloproteinases.

Results: The workers who did not use personal respiratory protection were exposed to varying airborne levels of endotoxin, 430 (75–15 000) EU/m³ (median, range). The level of plasma LPS was significantly elevated (p = 0.01) among the workers compared to the non-exposed controls. The workers also had elevated levels of MCP-1 (p = 0.02), MIP-1 (p = 0.05) and MMP-3 (p = 0.04). IL-6 and hsCRP were also elevated among the exposed group, but not significantly (p = 0.10 and p = 0.07, respectively).

Conclusions: In this study, we detected LPS in plasma of individuals exposed to high levels of LPS at their workplace. This finding is supported by elevated levels of several inflammatory cytokines among the workers, significantly exceeding that of the non-exposed control group. To the best of our knowledge, this is the first time that plasma LPS, together with increased inflammatory markers in plasma, has been detected in an occupational setting.

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