Inflammatory response after inhalation of bacterial endotoxin assessed by the induced sputum technique

Healthy subjects express differences in clinical responses to inhaled lipopolysaccharide that are related with inflammation and with atopy

BACKGROUND

Endotoxin and its purified derivative LPS are important contaminants of both domestic and occupational environments that have been related to airway diseases. A body of data suggests that there is considerable interindividual variability in LPS sensitivity.

OBJECTIVE

The aim of the study was to relate the individual clinical responses to inhaled LPS with the inflammatory process and the atopic status.

METHODS

Fifteen healthy subjects were challenged each week by inhalation with saline solution or LPS (0.5, 5, or 50 microg). The systemic response was defined by the increase in body temperature, blood neutrophilia, acute-phase proteins (C-reactive protein and LPS-binding protein [LBP]), and E-selectin. The LPS-induced airway response was defined as the increase in airway responsiveness and related to the cell count and concentration of TNF-alpha, myeloperoxidase, and eosinophil cationic protein in induced sputum. The atopic status was defined as an increase in IgE or a positive skin prick test result.

RESULTS

Subjects (n = 7) with a significant increase in body temperature had a larger increase in the systemic inflammatory response (blood neutrophilia; P <.01) and in blood concentrations of C-reactive protein (P <.02) and LBP (P <.01). Subjects with a significant increase in airway responsiveness (n = 8) had an increase in the sputum concentration of eosinophil cationic protein (P <.01). The amplitude of the systemic response (increase in body temperature [P <.001], blood neutrophilia [P <.02], and rise in LBP [P <.05] and decrease in FEV(1) [P <.01]) were inversely associated with the atopic status, suggesting a link between atopy and LPS responsiveness.

CONCLUSIONS

The clinical response to LPS occurs systemically or locally and is associated with inflammation. The atopic status was inversely related to the systemic inflammation.

Systemic and local airways inflammatory response to endotoxin

Endotoxin can be detected in house dust. Numerous studies have revealed that endotoxin exposure is a risk factor in increasing airway obstructive manifestations, both in occupational and domestic environments. In humans, inhalation of pure endotoxin induces systemic symptoms and a change in bronchial non-specific responsiveness, related with changes in blood and sputum inflammatory markers. However, some recent work suggests that, prior to airway disease development, endotoxin may have an atopy-protective effect. In particular, indoor endotoxin exposure in early life may protect against allergen sensitisation by enhancing type-1 immunity. Finally, since large variations between human immune responses to endotoxin have been reported, genetic mutations could alter the mechanisms of endotoxin recognition and contribute to the risk of atopy.

Sputum phagocytes from healthy individuals are functional and activated: a flow cytometric comparison with cells in bronchoalveolar lavage and peripheral blood

Cells in the bronchial airways of healthy individuals are continuously exposed to inhaled particulates in the size range 2-5 microm, which preferentially deposit in the bronchial rather than the alveolar lung. Induced sputum obtains cells primarily from the surfaces of bronchial airways. Using flow cytometry, we investigated whether sputum phagocytes demonstrate phenotypes indicative of increased functional activation and inflammation compared to phagocytes from the alveolar airways and peripheral blood (PB) in healthy subjects (N = 17). Sputum macrophages demonstrated increased levels of CD11b, increased oxidative burst, and greater phagocytosis than autologous alveolar macrophages. Expression of CD11b, CD64, and HLA-DR in sputum monocytes was upregulated compared to that in PB monocytes. Sputum neutrophils showed increased expression of CD11b, CD64, CD14, and HLA-DR and were more phagocytic than PB neutrophils. In conclusion sputum/bronchial phagocytes from healthy individuals express an inflammatory phenotype and are functionally more active than phagocytes from the alveolar airways and peripheral blood.

Concentrated swine feeding operations and public health: a review of occupational and community health effects

Recent industry changes in swine-management practices have resulted in a growing controversy surrounding the environmental and public health effects of modern swine production. The numerous wastes produced by intensive swine production not only pose a significant challenge to effective environmental management but also are associated with decreased air quality in confinement houses, potentially transferable antimicrobial resistance patterns, and several infectious agents that can be pathogenic to humans. Published studies have documented a variety of contaminants, microbial agents, and health effects in those occupationally exposed to swine, and these have provided the groundwork for an increasing body of research to evaluate possible community health effects. Nonetheless, several factors limit our ability to define and quantify the potential role of intensive swine-rearing facilities in occupational and community health. Our incomplete understanding and ability to detect specific exposures; the complicated nature of disease etiology; pathogenesis; and surveillance; and the inherent difficulties associated with study design all contribute to the inadequate level of knowledge that currently prevails. However; an evaluation of the published literature; and a recognition of the elements that may be compromising these studies; provides the foundation from which future studies may develop.

Health effects among workers in sewage treatment plants

OBJECTIVES

To further assess the presence of fatigue, symptoms of diarrhoea, and inflammation of airways among people working in sewage plants and the relation to airborne bacterial endotoxin at the workplace.

METHODS

34 Employees in sewage treatment plants and 35 controls were selected. They underwent a questionnaire investigation, and spirometry and airway responsiveness were measured. Measurements were made of airborne endotoxin at different workplaces.

RESULTS

The amount of airborne endotoxin varied between 3.8 and 32,170 ng/m3. Workers reported significantly higher nose irritation, tiredness, and diarrhoea. Airway responsiveness was increased among sewage workers, but no differences between the groups were found for spirometry.

CONCLUSIONS

The results confirm previous studies on the presence of airways and intestinal inflammation among workers in sewage treatment plants. The most likely causative agent is endotoxin, and at 14 of 23 workplaces, concentrations exceeded recommended guidelines.