Endotoxin Exposure Levels Research Articles

Bacterial contamination of coffee and personal exposure to inhalable dust and endotoxin in primary coffee processing factories in Ethiopia.

Endotoxins from gram-negative bacteria might be released when the coffee cherries are processed and may cause respiratory health problems among workers in the coffee industry. The relationship between bacterial contamination and occupational exposure to endotoxin levels has not been thoroughly explored previously in primary coffee processing factories in Ethiopia, or elsewhere. The aim of this study was to characterize the level of personal endotoxin exposure and its relations with bacterial contamination of coffee cherries in such factories in Ethiopia. A cross-sectional study was conducted from March 2020 - February 2021 in 9 primary coffee processing factories in 3 regions in Ethiopia. A total of 180 personal air samples were collected to analyze workers' exposure to inhalable dust and endotoxin. Correlation tests were performed to assess the relationship between total bacteria and endotoxin levels and between inhalable dust and endotoxin levels. The geometric mean (GM) of personal inhalable dust exposure among machine room workers and hand pickers were 9.58mg/m3 and 2.56mg/m3, respectively. The overall GM of endotoxin exposure among machine room workers and hand pickers were 10,198 EU/m3 and 780 EU/m3, respectively. Gram-negative bacteria were found in all 54 coffee samples. The correlation between inhalable dust and endotoxin exposure was significant (r=0.80; P <0.01). About 92% of the samples from hand pickers and all samples from machine room workers exceeded the occupational exposure limit of 90 EU/m3 recommended by the Dutch Expert Committee on Occupational Standards. Prevention and control of bacterial contamination of the coffee in primary coffee processing are suggested to reduce endotoxin exposure that might cause respiratory health problems among coffee workers.

134 Occupational Exposure to Different Microbial Species and Endotoxin and Serum Levels of Markers of Inflammation – Across Working Environments

Abstract Occupational exposure to bioaerosols (fungi, bacteria, and endotoxin) may be associated with early signs of health effects of the airways measured as elevated levels of inflammatory markers in serum samples. The aim of this study is to obtain knowledge about the contribution of endotoxin, different fungal and bacterial species, and dust to the inflammatory potential of bioaerosols from different working environments. Using personal samplers, bioaerosols were sampled in the inhalation zone of workers in different occupational settings. Fungal and bacterial species were identified to species level using MALDI-TOF MS. The ability of workers’ exposure to induce production of reactive oxidative species was analysed in a human cell line. Levels of the inflammatory markers C-reactive protein and serum amyloid A were measured in blood samples of the workers. The fungal and bacterial composition as well as species richness and endotoxin exposure level differed between working environments. Among the dominating microorganisms were different Staphylococcus species (work with animals), Stenotrophomonas maltophilia (work with plants), and Aspergillus niger (work with waste). While pigeon house dust was cytotoxic, pig farm dust was highly inflammogenic. The biofilm forming capacity of the exposure correlated with bacterial concentration in high exposure samples. Serum levels of inflammatory markers were associated significantly with occupational exposure to endotoxin for work with plants and waste water. As the next step, we are analysing whether this association is also found for work in other environments and whether it is associated with exposure to different microorganisms.

Effects of early‐life exposure to dust mite allergen and endotoxin on the development of asthma and wheezing: The Japan Environment and Children's Study

BackgroundThe effects of early‐life exposure to house dust mite allergen and endotoxin on the development of asthma are unclear in the literature. We investigated the association of early‐life exposure (0–36 months old) to house dust mite allergen and endotoxin with asthma incidence.MethodsIn this novel, large‐scale, nationwide birth cohort study, 5017 participants were randomly selected from those who met the eligibility criteria. House dust was vacuum‐sampled from the children's mattresses within homes and assayed for the presence of dust mite allergen (Der 1) and endotoxin. The participants were classified into four quartiles (Q1–Q4) according to exposure levels. We defined the incidence of asthma and wheezing using questionnaires at 12, 24, and 36 months old. Odds ratios (ORs) of the incidence of asthma and wheezing by age in Der 1 and endotoxin exposure level were estimated using logistic regression.ResultsThe cumulative incidence rates of asthma and wheezing during 0–36 months were 10.4% and 38.1%, respectively. Significant ORs were observed in asthma onset during 12–24 months old, asthma onset during 24–36 months old, and wheezing onset during 0–12 months old in the Q4 Der 1 group. In the Q4 endotoxin group, significant positive associations between endotoxin exposure and asthma (OR 2.00, 95% confidence interval [CI]: 1.03–3.85) and wheezing (OR 1.78, 95% CI: 1.01–3.12) onset during 24–36 months old were found.ConclusionsOur results indicated that high levels of early‐life exposure to Der 1 and endotoxin in mattresses may be involved in the development of asthma.

β-patchoulene simultaneously ameliorated dextran sulfate sodium-induced colitis and secondary liver injury in mice via suppressing colonic leakage and flora imbalance

Ulcerative colitis (UC) often occurs accompanied by colonic leakage and flora imbalance, resulting in secondary liver injury (SLI). SLI, in turn, aggravates UC, so the treatment of UC should not ignore it. β-patchoulene (β-PAE), a tricyclic sesquiterpene isolated from Pogostemon cablin, has been reported to exert a protective effect in gastrointestinal disease in our previous studies. However, its protection against UC and SLI remains unknown. Here we explored the protective effect and underlying mechanism of β-PAE against dextran sulfate sodium-induced UC and SLI in mice. The results indicated that β-PAE significantly reduced disease activity index, splenic index and attenuated the shortening of colonic length in UC mice. It alleviated colonic pathological changes and apoptosis through protecting tight junctions, reducing neutrophil aggregation, and inhibiting the release of pro-inflammatory cytokines and adhesion molecules. These effects of β-PAE were associated with the inhibition of TLR4/MyD88/NF-κB and ROCK1/MLC2 signalling pathway. UC-induced colonic leakage caused abnormally high LPS levels to result in SLI, and β-PAE markedly inhibited it. β-PAE simultaneously ameliorated SLI with reduced biomarker levels of endotoxin exposure and hepatic inflammation. High levels of LPS were also associated with flora imbalance in UC mice. However, β-PAE restored the diversity of gut microbiota and altered the relative abundance of characteristic flora of UC mice. Escherichia-dominated gut microbiota of UC mice was changed to Oscillospira-dominated after β-PAE treatment. In conclusion, pharmacological effects of β-PAE on UC and SLI were mainly contributed by suppressing colonic leakage and flora imbalance. The findings may have implications for UC treatment that not neglect the treatment of SLI.

Endotoxin and Hydrogen Sulphide Exposure and Effects on the Airways Among Waste Water Workers in Sewage Treatment Plants and Sewer Net System.

The purpose of this study is to investigate whether airborne exposure to endotoxins, hydrogen sulphide (H2S), and inhalable particles negatively impacts the respiratory system and inflammatory blood proteins in sewage plant and sewer net system workers and, further, to determine dose-response associations between exposure and health outcomes. In total, 148 waste water workers (WWWs) from urban and rural sewage plants and the sewer net system participated. One hundred and twenty-one workers were exposed to sewage, 46 from sewage plants and 75 from the sewer net system. Twenty-seven workers were characterized as little or not exposed and served as an internal reference group. Personal inhalable samples were analysed for endotoxins (Limulus assay), particle dust (gravimetrically) and Salmonella and Yersinia spp. (polymerase chain reaction method, PCR). Levels of H2S were measured using personal electro chemical sensors. Intercellular adhesion molecule 1 (ICAM-1), interleukin 8 (IL-8), surfactant protein D (SP-D), club cell protein 16 (CC16), and macrophage inflammatory protein (MIP) were determined by enzyme-linked immunosorbent assay and C-reactive protein (CRP) by an HS-MicroCRP assay in blood samples. Workers in sewage plants were exposed to significantly higher levels of endotoxins compared to workers in the sewer net system [median 55 EU m-3 (4-262 EU m-3) and median 27 EU m-3 (1-304 EU m-3), respectively]. The estimated H2S index showed higher values when working in the sewer net system [median 3.1 (0.5-78.1)] compared to workers at the sewage plants [median 1.3 (0.5-9.3)], and the most excessive exposure was collecting sewage from cesspools (273 p.p.m.). No viable airborne Salmonella and Yersinia spp. were detected. The exposed workers had significantly higher CRP compared to the referents [1.2 µg ml-1 (0.1-19.0 µg ml-1) and 0.8 µg ml-1 (0.1-5.0 µg ml-1), respectively] and lower forced expiratory volume in 1 s (FEV1)% [92.6%, standard deviation (SD) 14.6 and 102.0%, SD 10.1, respectively], with numbers given as mean and SD. The serum concentration of CRP was significantly and negatively associated with FEV1% (β = -7.7, R2 = 0.05) and forced vital capacity % (β = -8.5, R2 = 0.08), and the serum concentration of ICAM-1 with the estimated exposure to H2S (β = -19.9, R2 = 0.07). Despite moderate levels of endotoxin and H2S exposure, the results indicate an impact of these agents on lung function and the adhesion molecule ICAM-1, and a low-grade systemic inflammation was indicated in increased levels of CRP.

High exposure to endotoxin in farming is associated with less new-onset pollen sensitisation

ObjectivesLittle is known about risk factors for new onset and loss of atopic sensitisation in adulthood. The aim is to examine the longitudinal effect of quantitatively assessed endotoxin exposures on...

Occupational exposure to endotoxins and lung cancer risk: results of the ICARE Study

ObjectivesTo investigate the role of occupational exposure to endotoxins in lung cancer in a French population-based case–control study (ICARE (Investigation of occupational and environmental causes of respiratory cancers)).MethodsDetailed information was...

Evaluation of the use of the Endotoxin Activity Assay (EAA™) to Quantify Non-septic Exposure of Metabolic Endotoxemia

Objective: Endotoxin, also known as lipopolysaccharide (LPS), is a potent immune stimulant. Low levels of endotoxin exposure (metabolic endotoxemia) play a pivotal role in metabolic disorders. However, there is no robust clinical assay to directly quantify metabolic endotoxemia. We aimed to validate the whole blood Endotoxin Activity Assay (EAA™) as a novel, rapid method to quantify low grade metabolic endotoxemia against the well-established lipopolysaccharide binging protein assay (LBP), a robust surrogate marker of endotoxaemia. Methods: 67 women and 47 men aged 21 to 47 years (35.4 ± 5.5 years, 34.5 ± 7.2 years respectively) were assessed for adiposity (BMI, waist circumference and % body fat using bio-impedance), endotoxin levels (LBP, EAA™) and inflammatory status (serum CRP, IL-6, IL-8). Results: There was no direct relationship between EAA™ and LBP measures for quantitating metabolic endotoxemia for either women or men (R=0.146, p=0.284; R=0.283 p=0.09 respectively). In women, the traditional indirect marker of endotoxemia LBP correlated significantly with CRP and IL-6, measures of generalised immune activation and inflammation (R=0.664, p<0.001, R=0.296, p=0.028 respectively), but not with EAA™ assed endotoxemia. Supporting this relationship, LBP correlated with BMI and body fat percentage (R=0.306, p=0.022; R=0.301, p=0.024 respectively). However, the EAA™ only correlated with body fat percentage (R=0.382, p=0.014). In men, LBP was significantly related to CRP and IL-6 (R=0.345, p=0.046; R=0.421, p=0.009 respectively), but no relationship was observed between these inflammatory markers and EAA™ assed metabolic endotoxemia (R=0.206, p=0.243; R=0.280, p=0.093 respectively). There was no relationship between EAA™ or LBP and any of the three measures of adiposity. Conclusion: In conclusion, the existing rapid whole blood EAA™ method of analysis was not suitable to detect low levels of endotoxemia known to be present in the obese state, while the results suggest LBP indirect analysis remains the superior tool for measuring low grade endotoxemia in this population.

Development of Land Use Regression (LUR) models for assessment of annual average PM10 and endotoxin exposure levels in ambient air in a livestock dense area

Introduction There is concern about the influence of livestock farms on the health of Dutch inhabitants. Results from studies on health effects of livestock farming based on exposure proxies are inconsistent. Dust exposure measurements may enable more refined exposure-response analyses. We aimed to develop LUR models for particulate matter 10 (PM10) and endotoxin, known to be emitted from livestock farms and associated with adverse health effects. Methods Ambient PM10 was collected with Harvard Impactors at 61 sites (residential gardens) representing a variety of nearby livestock related characteristics. Three to four 2-week averaged PM10 samples were collected at each site over the course of 1.5 year. In addition a local reference site was set up and measured continuously to take into account temporal variation. Samples were analyzed for PM10 mass by weighing and endotoxin using the LAL assay. LUR models were developed using temporally adjusted annual PM10 and endotoxin exposure averages and livestock-related GIS variables (distances to and number of farms /animals by animal species). Results More spatial variation was observed for endotoxin compared to PM10. The model explained variance was higher for endotoxin than for PM10 (Adj. R2 0.56 and 0.12 respectively; number of predictor variables 7 and 2 respectively). Predictor variables included number of farms and type of animal species kept in the surroundings, and distance to the farms. Conclusions In conclusion, the effect of livestock-related sources on annual average exposure levels seems considerable for endotoxin and more limited for PM10. The LUR approach used, similar to air measurement studies focusing on other air pollutants, was found to be suitable to predict spatial variation in a livestock dense area. Thus far only livestock related predictor variables were explored. The developed LUR models should be further enriched and validated, before they can be applied to predict air pollution concentrations.

Occupational exposure levels of bioaerosol components are associated with serum levels of the acute phase protein Serum Amyloid A in greenhouse workers.

BackgroundOccupational exposure to particles may be associated with increased inflammation of the airways. Animal experiments suggest that inhaled particles also induce a pulmonary acute phase response, leading to systemic circulation of acute phase proteins. Greenhouse workers are exposed to elevated levels of bioaerosols. The objective of this study is to assess whether greenhouse workers personal exposure to bioaerosol components was associated with serum levels of the acute phase proteins Serum Amyloid A (SAA) and C-reactive protein (CRP).MethodsSAA and CRP levels were determined in serum sampled repeatedly from 33 greenhouse workers. Blood was drawn repeatedly on Mondays and Thursdays during work weeks. Acute phase protein levels were compared to levels in a comparison group of 42 people and related to individual exposure levels to endotoxin, dust, bacteria, fungi and β-glucan.ResultsSerum levels of SAA and CRP were not significantly different in greenhouse workers and a reference group, or on the two work days. In a mixed model, SAA levels were positively associated with endotoxin exposure levels (p = 0.0007). Results for fungi were not clear. CRP levels were positively associated with endotoxin exposures (p = 0.022). Furthermore, when workers were categorized into three groups based on SAA and CRP serum levels endotoxin exposure was highest in the group with the highest SAA levels and in the group with middle and highest CRP levels. SAA and CRP levels were elevated in workers with asthma.ConclusionGreenhouse workers did not have elevated serum levels of SAA and CRP compared to a reference group. However, occupational exposure to endotoxin was positively associated with serum levels of the acute phase proteins SAA and CRP. Preventive measures to reduce endotoxin exposure may be beneficial.

266 Endotoxin and glucan exposure protects against atopy and hay fever: a longitudinal study

ObjectivesWe previously showed that occupational endotoxin exposure in agricultural workers was associated with wheeze and negatively associated with atopy. We recently completed a 5“year follow” up of the initial study...

Leukocytes from wheezing infants release lower amounts of IL-12 and IFN-γ compared to non-wheezing infants

This study investigated environmental endotoxin exposure during early life, sensitization to aeroallergens, the production of cytokines by LPS-stimulated leukocytes, and the development of a wheezing phenotype in a prospective cohort of infants with high risk of developing allergic diseases. Eighty-four infants were followed from birth until 30 months of age. We assessed endotoxin concentration in house dust of their homes during the first 6 months of life. At age 30 months they were clinically evaluated to determine the development of wheezing and other clinical events, were skin prick tested, and had blood samples collected for the evaluation of cytokine release by LPS-stimulated peripheral blood mononuclear cells (PBMC). The level of endotoxin exposure during early life was not associated with development of a wheezing phenotype. On the other hand a higher incidence of respiratory infections occurred among recurrent wheezing (RW) infants. PBMC from RW children exposed to higher levels of environmental endotoxin (above 50 EU/mg) released less Interleukin (IL)-12p70 and IFN-γ compared to the non-RW group. TNF-α, IL-10, IL-4, IL-5, and IL17 production by LPS-stimulated PBMC from RW and non-RW children was equivalent in both groups of environmental endotoxin exposure. In this prospective cohort of infants with high risk of developing allergic diseases we observed that RW and non-RW children were exposed to similar levels of endotoxin early in life. LPS-stimulated PBMC from RW infants exposed to higher levels of endotoxin released significantly less IL-12 and IFN-γ compared to non-RW infants.

Inhalable dust and endotoxin exposure among Danish pig, dairy, poultry and mink farmers: results from the SUS cohort study

ObjectivesTo provide information on variability and levels of personal dust and endotoxin exposure in different sectors of the primary animal production based on the same methodology.Methods507 personal inhalable dust samples...

Risk of lung cancer in relation to contiguous windows of endotoxin exposure among female textile workers in Shanghai

Exposure to endotoxin has been consistently associated with a reduced risk of lung cancer. However, there is a paucity of information regarding temporal aspects of this relationship. The objective of this study was to investigate the associations between contiguous windows of endotoxin exposure and risk of lung cancer. Data were reanalyzed from a case-cohort study (602 cases, 3,038 subcohort) of female textile workers in Shanghai, China. Cumulative endotoxin exposure was partitioned into two windows: ≥20 and <20years before risk. Exposure-response relations were examined using categorical and non-linear (semi-parametric) models, accounting for confounding by previous exposure windows. There was an inverse trend of decreasing risk of lung cancer associated with increasing levels of endotoxin exposure ≥20years before risk (p trend=0.02). Women in the highest two categories of cumulative exposures had hazard ratios of 0.78 (95% CI 0.60-1.03) and 0.77 (95% CI 0.58-1.02) for lung cancer, respectively, in comparison with unexposed textile workers. There was, however, a weaker association and not statistically significant between lung cancer and endotoxin exposure accumulated in the more recent window (<20years before risk). Results provide further evidence that endotoxin exposure that occurred 20years or more before risk confers the strongest protection against lung cancer, indicating a possible early anti-carcinogenic effect. Further studies are needed to better understand the underlying biological mechanisms for this effect.

Endotoxin exposure, CD14 and wheeze among farmers: a gene–environment interaction

ObjectivesEndotoxin-exposed workers are at an increased risk of non-atopic asthma and lung-function decline. Genetic variants may influence susceptibility to these effects. The objective of the present study was to assess...

Low level bacterial endotoxin activates two distinct signaling pathways in human peripheral blood mononuclear cells

BackgroundBacterial endotoxin, long recognized as a potent pro-inflammatory mediator in acute infectious processes, has more recently been identified as a risk factor for atherosclerosis and other cardiovascular diseases. When endotoxin enters the bloodstream, one of the first cells activated is the circulating monocyte, which exhibits a wide range of pro-inflammatory responses.MethodsWe studied the effect of low doses of E. coli LPS on IL-8 release and superoxide formation by freshly isolated human peripheral blood mononuclear cells (PBMC).ResultsIL-8 release was consistently detectable at 10 pg/ml of endotoxin, reaching a maximum at 1 ng/ml, and was exclusively produced by monocytes; the lymphocytes neither produced IL-8, nor affected monocyte IL-8 release. Superoxide production was detectable at 30 pg/ml of endotoxin, reaching a maximum at 3 ng/ml. Peak respiratory burst activity was seen at 15-20 min, and superoxide levels returned to baseline by 1 h. IL-8 release was dependent on both membrane-associated CD14 (mCD14) and Toll-like receptor 4 (TLR4. Superoxide production was dependent on the presence of LBP, but was not significantly affected by a blocking antibody to TLR4. Moreover, treatment with lovastatin inhibited LPS-dependent IL-8 release and superoxide production.ConclusionsThese findings suggest that IL-8 release and the respiratory burst are regulated by distinct endotoxin-dependent signaling pathways in PBMC in low level of endotoxin exposure. Selectively modulating these pathways could lead to new approaches to treat chronic inflammatory diseases, such as atherosclerosis, while preserving the capacity of monocytes to respond to acute bacterial infections.

A Novel Approach to Estimating Average Long-term Endotoxin Exposure for Children: The Endotoxin Exposure Matrix

PP-30-121 Background/Aims: A major limitation to quantitative endotoxin exposure assessment is that it only effectively captures endotoxin exposure level at 1 time-point. Thus far, no feasible or economical method has been proposed to estimate average long-term endotoxin exposure. A potential solution to this difficulty is to borrow from occupational epidemiology and adapt the concepts of job exposure matrices to estimate cumulative endotoxin exposure, which acts as a proxy for average exposure over time, in a new exposure matrix—the Endotoxin Exposure Matrix (EEM). Methods: The EEM is designed to estimate the environmental (background) levels of endotoxin and incorporate intensifying factors (factors affecting background levels). These environmental factors (location of residence, degree of parental interaction, and household dust) are assigned an endotoxin exposure score in an a priori fashion (with the exception of household dust). Household levels of endotoxin will be measured from collected dust samples using the LAL Assay and converted into endotoxin exposure scores, which is assessed along a 3-point ordinal scale. This quantitative measure will also allow internal validation of the EEM. Exposure status for various intensifying endotoxin factors will act as multipliers for their corresponding environmental factors (eg, infrequent house cleaning increases the endotoxin exposure from household dust). To capture the long-term nature of exposure, duration of exposure (years lived) will be taken into account. Endotoxin exposure scores associated with the environmental factors will be multiplied by the duration of exposure and corresponding intensifying factors and summed to give an endotoxin exposure index (EEI). Results: As the EEI is semiquantitative, its interpretation is on an ordinal scale, such that a higher EEI value corresponds to a higher level of endotoxin exposure and the absolute value of the index is not meaningful. Conclusion: Therefore, the EEM allows average long-term endotoxin exposure to be estimated in a feasible and economical fashion.

Inverse association between endotoxin exposure and canine atopic dermatitis

The development of canine atopic dermatitis (CAD) may be related to exposure to mite allergens, bacterial endotoxin and/or fungal glucans. In this study, indoor exposure levels of house dust mite allergens, endotoxins and fungal glucans were measured to determine their possible association with CAD. A case-control study including adult Labrador retrievers with (n=28) and without (controls; n=65) CAD was conducted. Dust samples were collected from the living room floor and the bedding and coat of the dog and these were analyzed for house dust mite allergens Der p1 and Der f1, endotoxin and (1→3)-β-d-glucan levels. Dog owners were also required to return a questionnaire regarding their home characteristics. The endotoxin exposure level in the coats of dogs was significantly inversely associated with CAD (odds ratio 0.38; 95% confidence interval 0.15-0.97; P<0.05). No significant difference was found in exposure levels to house dust mite allergens and fungal glucans. The results indicated that endotoxin exposure is inversely associated with CAD, suggesting a protective effect of high indoor endotoxin exposure towards the development of the condition.

Allergen and endotoxin exposure in a companion animal hospital

BackgroundExposure to allergens, both in general and occupational environments, is known to result in sensitisation and exacerbation of allergic diseases, while endotoxin exposure might protect against allergic diseases. This may...

Occupational Endotoxin Exposure Reduces the Risk of Atopic Sensitization but Increases the Risk of Bronchial Hyperresponsiveness

Background: Microbial exposures in both childhood and adult life are protective against atopy, allergic rhinitis and atopic asthma. In adults, this protective effect is paralleled by an increased prevalence of non-atopic asthma. This study was undertaken to investigate associations between occupational endotoxin exposure and atopic sensitization and bronchial hyperresponsiveness to methacholine (BHR) in agricultural workers. In addition, the role of atopy in endotoxin-related respiratory effects was studied. Methods: Data were available for 427 farmers and agricultural industry workers, for whom airborne endotoxin exposure levels were estimated by 249 personal exposure measurements. Atopy was assessed as specific serum IgE to common inhalant allergens, and respiratory symptoms and personal characteristics by standardized questionnaires. BHR was determined in a subset of 113 subjects. Associations were adjusted for age, sex, smoking and living on a farm during childhood. Results: Endotoxin exposure was positively associated with BHR and wheeze (p < 0.05). In contrast, endotoxin exposure was inversely associated with atopy and IgE to grass pollen (p < 0.001). The proportions of wheeze and BHR that were attributable to atopy were only 16.6 and 32.8%, respectively. Conclusions: High endotoxin exposure is a risk factor for BHR and wheeze, which were characterized by a predominantly non-atopic phenotype. At the same time, endotoxin exposure is related to a reduced risk of atopy and IgE to grass pollen in adults. It is unlikely that this is entirely a result of healthy worker selection, as significant inverse associations between endotoxin and IgE to grass pollen were found regardless of reported allergic symptoms.