Monocyte CD14 response following endotoxin exposure in cotton spinners and office workers

Endotoxin and occupational airway disease

PURPOSE OF REVIEW

This review provides an update on the role of bacterial endotoxin in occupational airway disease, a problem of importance from diagnostic and preventive points of view.

RECENT FINDINGS

Data from human inhalation studies have increased our understanding of the cell mechanisms underlying diseases related to endotoxin exposure. In addition, knowledge from molecular genetics may help us to identify individuals at risk. Several investigations have demonstrated that, apart from endotoxin, other microbial cell wall agents are also related to the risk for symptoms of occupational lung diseases, with pathogenic mechanisms different to those caused by endotoxin. Diagnostic methods have progressed from traditional lung function measurements to sampling of indicators of inflammation in the blood, nasal lavage and induced sputum. Investigations of a longitudinal design have provided important findings on the relationship between acute and chronic effects as well as exposures of risk and risk factors among individuals.

SUMMARY

Endotoxin, as well as other agents derived from microbes, are important causative agents for occupational respiratory and other diseases, and exposure may occur in a large variety of occupational environments. Recent data from longitudinal studies provide important information on diagnostic and preventive measures.

Occupational exposures and risks of liver cancer among Shanghai female textile workers--a case-cohort study

BACKGROUND

Liver cancer is the fifth most frequent malignancy worldwide. Viral hepatitis B and C, alcohol, and aflatoxin are the major established risk factors. Little is known about the aetiological contributions of occupational exposures, as previous occupational epidemiological studies of liver cancer suggest few agent-specific associations. We investigated associations of occupational exposures to dusts and chemicals in a cohort of female textile workers.

METHODS

Cancer incidence was determined among 267,400 female textile workers in Shanghai, China, who had been enrolled in an intervention trial of breast self-exam efficacy during 1989-98. Subjects were interviewed at baseline regarding basic demographics, smoking habits, alcohol consumption, and contraceptive practices. A case-cohort study of 360 liver cancer cases and 3,186 age-stratified randomly chosen subcohort subjects was conducted within this cohort. Exposures to workplace dusts and chemicals were reconstructed from complete work history data, historical exposure monitoring data for selected agents, and a specially designed job-exposure matrix for the textile industry. Relative risks and dose-response trends were estimated by Cox proportional hazards modelling, adapted for the case-cohort design. Latency analyses with different lag years were also applied.

RESULTS

2,095,904 person-years were contributed by this female cohort. The results of the case-cohort analysis revealed a protective effect of cotton fibre exposure years [adjusted hazards ratio (HR) = 0.64; 95% confidence interval (95% CI) 0.44-0.92] or endotoxin exposure (adjusted HR = 0.60; 95% CI 0.41-0.88) for the fourth quartile with significant trends for 20 year exposure lags.

CONCLUSIONS

This study suggests that chronic exposure to endotoxin or some other component of cotton dust exposure may have reduced liver cancer risk in this population.

Immunologic Response to Inhaled Endotoxin: Changes in Peripheral Cell Surface Markers in Normal Individuals

Monocyte cell surface CD14 increases following both in vitro challenge with lipopolysaccharide (LPS) and exposure to organic dusts. We investigated 9 volunteers, mean age 39 years (range, 29-53 years). Each inhaled increasing concentrations of lipopolysaccharide (0.5 microg, 5.0 microg, and 20 microg). Monocyte cell surface CD14 (expressed as mean linear fluorescence) was measured before and after using flow cytometry. Upregulation of CD14 (up to 6 hours after LPS exposure) did not differ significantly between LPS (mean, 35.8; standard deviation [SD]; 54.3), n = 7 after 20 l g LPS) in comparison to placebo (39.3 [49.0]; n = 7). Maximum mean (SD) percentage CD14 upregulation up to 6 hours after challenge differed, but not significantly between those experiencing a clinically significant event (58.4 [49.2]) in comparison to those who did not (13.8, [43.2]; P = 0.27). Two individuals with a marked clinical response developed marked CD14 upregulation after exposure to LPS.