Long-term antigen exposure irreversibly modifies metabolic requirements for T cell function.
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ABSTRACT:
SUBMITTER: Bettonville M
PROVIDER: S-EPMC6025959 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Studies that examined dietary energy requirements (DERs) of patients undergoing maintenance hemodialysis (MHD) have shown mixed results. Many studies reported normal DERs, but some described increased energy needs. DERs in MHD patients have been estimated primarily from indirect calorimetry and from nitrogen balance studies. The present study measured DERs in MHD patients on the basis of their dietary energy intake and changes in body composition.This study assessed DERs in MHD patients who received a constant energy intake while changes in their body composition were measured.Seven male and 6 female sedentary, clinically stable MHD patients received a constant mean (±SD) energy intake for 92.2 ± 7.9 d while residing in a metabolic research ward. Changes in fat and fat-free mass, measured by dual-energy X-ray absorptiometry, were converted to calorie equivalents and added to energy intake to calculate energy requirements.The average DER was 31 ± 3 kcal · kg(-1) · d(-1) calculated from energy intake and change in fat and fat-free calories, which was 28 ± 197 kcal/d over the 92 d of the study. DERs of MHD patients correlated strongly with their body weight (r = 0.81, P = 0.002) and less closely with their measured resting energy expenditure expressed as kcal/d (r = 0.69, P = 0.01). Although the average observed DER in MHD patients was similar to published estimated values for normal sedentary individuals of similar age and sex, there was wide variability in DER among individual patients (range: 26-36 kcal · kg(-1) · d(-1)).Average DERs of sedentary, clinically stable patients receiving MHD are similar to those of sedentary normal individuals. Our data do not support the theory that MHD patients have increased DERs. Due to the high variability in DERs, careful monitoring of the nutritional status of individual MHD patients is essential. This trial was registered at clinicaltrials.gov as NCT02194114.
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Project description:Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants that accumulate to high levels in human populations that are subject to occupational or regional industry exposure. PBDEs have been shown to affect human neuronal, endocrine and reproductive systems, but their effect on the immune system is not well understood. In this study, experimental adult mice were intragastrically administered 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) at doses of 8, 80 or 800 mg/kg of body weight (bw) at 2-day intervals. Our results showed that continuous exposure to BDE-209 resulted in high levels of BDE-209 in the plasma that approached the levels found in people who work in professions with high risks of PDBE exposure. Reduced leukocytes, decreased cytokine (IFN-?, IL-2 and TNF-?) production and lower CD8 T-cell proliferation were observed in the mice exposed to BDE-209. Additionally, mice with long-term BDE-209 exposure had lower numbers of antigen-specific CD8 T cells after immunization with recombinant Listeria monocytogenes expressing ovalbumin (rLm-OVA) and the OVA-specific CD8 T cells had reduced functionality. Taken together, our study demonstrates that continuous BDE-209 exposure causes adverse effects on the number and functionality of immune cells in adult mice.
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Project description:Dioxins are persistent environmental toxins that are still present in the food supply despite strong efforts to minimize exposure. Dioxins ingested by humans accumulate in fat and are excreted very slowly, so their long-term effects at low concentrations are a matter of concern. It is necessary to consider long-term, low-dose continuous administration under conditions that are as close as possible to a person's diet. In this study, we orally administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most common dioxin, at low doses in mice and observed the immunological effects. We found that antigen-specific (OVA) antibody production in the serum increased dose-dependently by TCDD concentrations below 500 ng/kg after long-term (10 weeks) exposure. Similar increases were seen in fecal and vaginal samples but were not significant. Th1 and Th2 lymphocyte responses, as determined by antibody and cytokine production, also significantly increased dose-dependently up to 500 ng/kg TCDD, and the Th1/Th2 balance was shifted toward Th1. These results indicate that low-dose, long-term TCDD exposure results in immunological abnormalities, perhaps by increasing antigen permeability. Different doses of dioxins may have opposing effects, being immunostimulatory at low doses (100 ng/kg/day) and immunosuppressive at high doses (500 ng/kg/day).
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Project description:BackgroundRecent studies suggest that household endotoxin and allergens can modify the impact of air pollutants on development of asthma; however, epidemiological evidence is limited and conflicting.ObjectivesTo investigate whether pet ownership modified the association between ambient air pollution and asthma in children.MethodsWe conducted a population-based cross-sectional study, the Seven Northeast Cities Study in China and recruited a total of 59,754 children from 94 schools during 2012-2013. Long-term air pollutant concentrations, including airborne particulate matter with a diameter of 1 μm or less (PM1 ), PM2.5 , PM10 , and nitrogen dioxide (NO2 ) from 2009 to 2012 were estimated using a random forest model. We collected information of respiratory health in children using the Epidemiologic Standardization Project Questionnaire of the American Thoracic Society (ATS-DLD-78-A). Regression models were used to evaluate associations between pet ownership and air pollution on asthma after adjusting for potential covariates.ResultsExposure to increasing levels of air pollutants was associated with higher prevalence of asthma, but associations were significantly attenuated in children who owned pets. For example, compared to children without pets, those who owned pets did not have an increased risk of symptoms of asthma (odds ratio, 1.01, 95% confidence interval: 0.78, 1.30), wheeze (0.96, 95% confidence interval [CI]: 0.76, 1.21), and cough (1.01, 95% CI: 0.87, 1.18) for each 10 µg/m3 increase in PM1 (P-int < 0.05). Similar trends were observed for other air pollutants. Dog and bird ownership decreased the associations of asthma and cough with air pollutant exposure. The main findings were consistent with a series of sensitivity analyses.ConclusionCurrent pet ownership may reduce the adverse impact of long-term air pollution on childhood asthma. Longitudinal studies are needed to confirm this finding which could have important implications for public health.
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Project description:BACKGROUND:Metabolic syndrome is an important risk factor for non-communicable diseases, particularly type 2 diabetes, coronary heart disease, and stroke. Long-term exposure to greenspace could be protective of metabolic syndrome, but evidence for such an association is lacking. Accordingly, we investigated the association between long-term exposure to greenspace and risk of metabolic syndrome. METHODS:The present longitudinal study was based on data from four clinical examinations between 1997 and 2013 in 6076 participants of the Whitehall II study, UK (aged 45-69?years?at baseline). Long-term exposure to greenspace was assessed by satellite-based indices of greenspace including Normalized Difference Vegetation Index (NDVI) and Vegetation Continuous Field (VCF) averaged across buffers of 500 and 1000?m surrounding the participants' residential location at each follow-up. The ascertainment of metabolic syndrome was based on the World Health Organization (WHO) definition. Hazard ratios for metabolic syndrome were estimated using Cox proportional hazards regression models, controlling for age, sex, ethnicity, lifestyle factors, and socioeconomic status. RESULTS:Higher residential surrounding greenspace was associated with lower risk of metabolic syndrome. An interquartile range increase in NDVI and VCF in the 500?m buffer was associated with 13% (95% confidence interval (CI): 1%, 23%) and 14% (95% CI: 5%, 22%) lower risk of metabolic syndrome, respectively. Greater exposure to greenspace was also associated with each individual component of metabolic syndrome, including a lower risk of high levels of fasting glucose, large waist circumference, high triglyceride levels, low HDL cholesterol, and hypertension. The association between residential surrounding greenspace and metabolic syndrome may have been mediated by physical activity and exposure to air pollution. CONCLUSIONS:The findings of the present study suggest that middle-aged and older adults living in greener neighbourhoods are at lower risk of metabolic syndrome than those living in neighbourhoods with less greenspace.
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Project description:Air pollutants (AP) play a role in subclinical inflammation, and are associated with cardiovascular morbidity and mortality. Metabolic syndrome (MetS) is inflammatory and precedes cardiovascular morbidity and type 2 diabetes. Thus, a positive association between AP and MetS may be hypothesized. We explored this association, (taking into account, pathway-specific MetS definitions), and its potential modifiers in Swiss adults. We studied 3769 participants of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults, reporting at least four-hour fasting time before venepuncture. AP exposures were 10-year mean residential PM10 (particulate matter <10?m in diameter) and NO2 (nitrogen dioxide). Outcomes included MetS defined by World Health Organization (MetS-W), International Diabetes Federation (MetS-I) and Adult Treatment Panel-III (MetS-A) using four- and eight-hour fasting time limits. We also explored associations with individual components of MetS. We applied mixed logistic regression models to explore these associations. The prevalence of MetS-W, MetS-I and MetS-A were 10%, 22% and 18% respectively. Odds of MetS-W, MetS-I and MetS-A increased by 72% (51-102%), 31% (11-54%) and 18% (4-34%) per 10?g/m3 increase in 10-year mean PM10. We observed weaker associations with NO2. Associations were stronger among physically-active, ever-smokers and non-diabetic participants especially with PM10 (p<0.05). Associations remained robust across various sensitivity analyses including ten imputations of missing observations and exclusion of diabetes cases. The observed associations between AP exposure and MetS were sensitive to MetS definitions. Regarding the MetS components, we observed strongest associations with impaired fasting glycemia, and positive but weaker associations with hypertension and waist-circumference-based obesity. Cardio-metabolic effects of AP may be majorly driven by impairment of glucose homeostasis, and to a less-strong extent, visceral adiposity. Well-designed prospective studies are needed to confirm these findings.
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