The Association Between Smoking and Gut Microbiome in Bangladesh.

INTRODUCTION: Epidemiological studies that investigate alterations in the gut microbial composition associated with smoking are lacking. This study examined the composition of the gut microbiome in smokers compared with nonsmokers. AIMS AND METHODS: Stool samples were collected in a cross-sectional study of 249 participants selected from the Health Effects of Arsenic Longitudinal Study in Bangladesh. Microbial DNA was extracted from the fecal samples and sequenced by 16S rRNA gene sequencing. The associations of smoking status and intensity of smoking with the relative abundance or the absence and presence of individual bacterial taxon from phylum to genus levels were examined. RESULTS: The relative abundance of bacterial taxa along the Erysipelotrichi-to-Catenibacterium lineage was significantly higher in current smokers compared to never-smokers. The odds ratio comparing the mean relative abundance in current smokers with that in never-smokers was 1.91 (95% confidence interval = 1.36-2.69) for the genus Catenibacterium and 1.89 (95% confidence interval = 1.39-2.56) for the family Erysipelotrichaceae, the order Erysipelotrichale, and the class Erysipelotrichi (false discovery rate-adjusted p values = .0008-.01). A dose-response association was observed for each of these bacterial taxa. The presence of Alphaproteobacteria was significantly greater comparing current with never-smokers (odds ratio = 4.85, false discovery rate-adjusted p values = .04). CONCLUSIONS: Our data in a Bangladeshi population are consistent with evidence of an association between smoking status and dosage with change in the gut bacterial composition. IMPLICATIONS: This study for the first time examined the relationship between smoking and the gut microbiome composition. The data suggest that smoking status may play an important role in the composition of the gut microbiome, especially among individuals with higher levels of tobacco exposure.

The association between socioeconomic status and subclinical atherosclerosis in a rural Bangladesh population.

BACKGROUND: In Bangladesh, CVD accounts for the majority of non-communicable mortality. The purpose of this study was to determine the role of socioeconomic status (SES) on subclinical atherosclerosis measured as carotid intima-media thickness (IMT) in a rural Bangladesh population. METHODS: Carotid IMT was measured between 2010 and 2011 in 1022 participants (average age 46, 40% male) randomly selected from the Health Effects of Arsenic Longitudinal Study (HEALS), a population-based prospective cohort study based in rural Bangladesh. SES was measured as occupation type, land ownership, educational attainment, and television ownership. RESULTS: Half of the participants received formal education (53%) and under half owned land (48%) and a television (44%). Women were primarily homemakers (95%) and men worked as factory workers (24%), laborers (18%), or in business (55%). In univariate analysis, those owning greater than one acre of land (p=0.03), owning a television (p=0.02), or laborers and business owners compared to factory workers had higher levels of carotid IMT (p<0.01). In multivariate analysis after adjustment for confounders, only men employed in the business sector had elevated carotid IMT compared to factory workers. The association was strongest in older men (58.7µm, 95% CI 17.2-100.0, ≥50years old) compared to younger men (13.7µm, 95% CI -7.8-35.2, <50years old). CONCLUSION: Business sector employment was positively associated with subclinical atherosclerosis after adjustment for confounders. This finding is consistent with evidence from other developing nations suggesting that certain SES factors are independent predictors of CVD.

Periodontal diseases and carotid intima-media thickness in Bangladesh.

AIM: To evaluate the relationship between periodontal diseases and subclinical atherosclerosis in a younger and lean South Asian population. METHODS: We conducted a cross-sectional study in 917 subjects (mean age 46 years and mean body mass index 21.1 kg/m2 ) from the Health Effects of Arsenic Longitudinal Study in Bangladesh. Multivariate linear regression models were used to assess the associations between multiple clinical measures of periodontal diseases and carotid intima-media thickness (IMT). RESULTS: Mean attachment loss (AL) and percentage of sites with AL ≥ 4 mm (% AL ≥ 4) were associated with increased IMT. The IMT was 20.0-µm (95% CI: 2.2, 37.8) and 26.5-µm (95% CI: 8.9, 44.1) higher in subjects in the top quartile of mean AL (>3.72 mm) and % AL ≥ 4 (>58.4%), respectively, compared to those in the bottom quartile. In a subset of 366 subjects, mean AL was positively associated with plasma levels of matrix metalloproteinase-9 (p < 0.05) and soluble intercellular adhesion molecule-1 (p < 0.01). CONCLUSIONS: Attachment loss was associated with subclinical atherosclerosis in this young and lean Bangladeshi population. Future prospective studies are needed to confirm this association.

Gene-arsenic interaction in longitudinal changes of blood pressure: Findings from the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide and mounting evidence indicates that toxicant exposures can profoundly impact on CVD risk. Epidemiologic studies have suggested that arsenic (As) exposure is positively related to increases in blood pressure (BP), a primary CVD risk factor. However, evidence of whether genetic susceptibility can modify the association between As and BP is lacking. In this study, we used mixed effect models adjusted for potential confounders to examine the interaction between As exposure from well water and potential genetic modifiers on longitudinal change in BP over approximately 7years of follow-up in 1137 subjects selected from the Health Effects of Arsenic Longitudinal Study (HEALS) cohort in Bangladesh. Genotyping was conducted for 235 SNPs in 18 genes related to As metabolism, oxidative stress and endothelial function. We observed interactions between 44 SNPs with well water As for one or more BP outcome measures (systolic, diastolic, or pulse pressure (PP)) over the course of follow-up. The interaction between CYBA rs3794624 and well water As on annual PP remained statistically significant after correction for multiple comparisons (FDR-adjusted p for interaction=0.05). Among individuals with the rs3794624 variant genotype, well water As was associated with a 2.23mmHg (95% CI: 1.14-3.32) greater annual increase in PP, while among those with the wild type, well water As was associated with a 0.13mmHg (95% CI: 0.02-0.23) greater annual increase in PP. Our results suggest that genetic variability may contribute to As-associated increases in BP over time.

Reduction of household air pollution through clean fuel intervention and recovery of cellular immune balance.

BACKGROUND: We conducted a clean fuel intervention trial (Bangladesh Global Environmental and Occupational Health (GEOHealth) (NCT02824237) with liquefied petroleum gas (LPG) for 26 months among rural Bangladeshi women chronically exposed to household air pollution (HAP) from biomass fuel (BMF) use. We aimed to evaluate the effect of HAP reduction following LPG intervention on immune response outcome. METHODS: We supplied LPG cook stove and refills in cylinder in 200 households for 26 months. We measured personal exposure to HAP [particulate matter 2.5 (PM2·5), black carbon (BC) and carbon monoxide (CO)] in 200 women (main cook) by personal monitors at pre- and post-intervention. Immune function was assessed before and after intervention, in blood collected within 2 weeks of HAP measurements. Primary endpoints included reduction in HAP, lymphocyte proliferation and oxidative stress response, and alterations in T and B cell proportions. FINDINGS: Exclusive LPG use for 26 months resulted in significant reduction in PM2·5 (43.5%), BC (13%) and CO (48%) exposure in the women. For one unit decrease in BC, Treg cells and memory B cells increased by 7% and 34% respectively, in the peripheral circulation. One unit decrease in CO was significantly associated with increase in early B cells and plasmablasts by 66% and 5% respectively. For one unit decrease in BC, percent-dividing cells, proliferation and expansion indices increased by 2%, 0.4%, and 1%, respectively. INTERPRETATION: Reduced personal exposure to HAP through clean fuel intervention was related to a return towards cellular immune balance.

The association between gut microbiome and anthropometric measurements in Bangladesh.

Our objective was to investigate the relationship between the gut microbiota and anthropometric measurements among 248 participants from the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh. Our cohort represents a unique population that allows for the investigation of the gut microbiota and anthropometric measurements in lean individuals. We measured height, weight, arm, thigh, hip, and waist circumferences, and collected fecal samples. Microbial DNA was extracted from the stool samples and sequenced by 16S rRNA gene sequencing. We examined associations between relative abundance of individual bacterial taxa from phylum to genus levels and anthropometric measurements. We found that higher BMI, mid-upper arm circumference, waist circumference, and waist-to-hip ratio were associated with a lower alpha diversity of fecal bacteria. Relative abundance of the genus Oscillospira and the family S24-7 were inversely related to all measurements after correction for multiple testing. Relative abundance of genus Acidaminococcus and family Ruminococcaceae were also associated with several measurements. The positive associations of the genus Acidaminococcus with BMI, as well as waist and hip circumferences, were stronger in women than in men. Our data in this lean Bangladeshi population found a correlation between Oscillospira and leanness, as measured using multiple anthropometric measures.

The role of gut microbiome and its interaction with arsenic exposure in carotid intima-media thickness in a Bangladesh population.

BACKGROUND: Emerging data suggest that inorganic arsenic exposure and gut microbiome are associated with the risk of cardiovascular disease. The gut microbiome may modify disease risk associated with arsenic exposure. Our aim was to examine the inter-relationships between arsenic exposure, the gut microbiome, and carotid intima-media thickness (IMT)-a surrogate marker for atherosclerosis. METHODS: We recruited 250 participants from the Health Effects of Arsenic Longitudinal Study in Bangladesh, measured IMT and collected fecal samples in year 2015-2016. 16S rRNA gene sequencing was conducted on microbial DNA extracted from the fecal samples. Arsenic exposure was measured using data on arsenic concentration in drinking water wells over time to derive a time-weighted water arsenic index. Multivariable linear regression models were used to test the inter-relationships between arsenic exposure, relative abundance of selected bacterial taxa from phylum to genus levels, and IMT. RESULTS: We identified nominally significant associations between arsenic exposure, measured using either time-weighted water arsenic or urinary arsenic, and the relative abundances of several bacterial taxa from the phylum Tenericutes, Proteobacteria, and Firmicutes. However, none of the associations retained significance after correction for multiple testing. The relative abundances of the family Aeromonadaceae and genus Citrobacter were significantly associated with IMT after correction for multiple testing (P-value = 0.02 and 0.03, respectively). Every 1% increase in the relative abundance of Aeromonadaceae and Citrobacter was related to an 18.2-µm (95% CI: 7.8, 28.5) and 97.3-µm (95% CI: 42.3, 152.3) difference in IMT, respectively. These two taxa were also the only selected family and genus using the LASSO variable selection method. There was a significant interaction between Citrobacter and time-weighted water arsenic in IMT (P for interaction = 0.04). CONCLUSIONS: Our findings suggest a role of Citrobacter in the development of atherosclerosis, especially among individuals with higher levels of arsenic exposure.

Association between number of children and carotid intima-media thickness in Bangladesh.

Previous studies on the association between number of children and carotid intima-media thickness (cIMT) were limited to Western populations. Pregnancy in women is associated with physiologic changes that may influence the risk of cardiovascular disease. Comparing the association between number of children and cIMT in men and women can provide insights on whether the association may be due to pregnancy. We investigated the association between number of children and cIMT among 718 female (mean age 37.5 years) and 417 male participants (mean age 41.3 years), randomly selected from the Health Effect of Arsenic Longitudinal Study (HEALS), a population-based cohort study in Bangladesh. Multivariate linear regression was used to assess the association and to control for education attainment, history of diabetes, age, smoking, betel use, BMI, systolic blood pressure, and diastolic blood pressure. The average number of children was 4.43 for women and 3.74 for men. There were no nulliparous women. We observed a positive association between number of children and cIMT in women. Mean cIMT increased by 4.5 µm (95% CI, 0.8-8.1) per increment of one birth (P = 0.02). Compared to women with two children, cIMT in women with 4 children and ≥5 children was 23.6µm (95%CI, 2.6-44.7; P = 0.03) and 25.1 µm (95%CI, 3.5-46.6; P = 0.02) greater, respectively. The association was not modified by BMI, SBP, betel use or age. Data in men showed no evidence of association (P = 0.4). The finding suggests a role of high parity in atherosclerosis in women of a low-income, high parity population.

Arsenic Exposure from Drinking Water and Urinary Metabolomics: Associations and Long-Term Reproducibility in Bangladesh Adults.

BACKGROUND: Chronic exposure to inorganic arsenic from drinking water has been associated with a host of cancer and noncancer diseases. The application of metabolomics in epidemiologic studies may allow researchers to identify biomarkers associated with arsenic exposure and its health effects. OBJECTIVE: Our goal was to evaluate the long-term reproducibility of urinary metabolites and associations between reproducible metabolites and arsenic exposure. METHODS: We studied samples and data from 112 nonsmoking participants (58 men and 54 women) who were free of any major chronic diseases and who were enrolled in the Health Effects of Arsenic Longitudinal Study (HEALS), a large prospective cohort study in Bangladesh. Using a global gas chromatography-mass spectrometry platform, we measured metabolites in their urine samples, which were collected at baseline and again 2 y apart, and estimated intraclass correlation coefficients (ICCs). Linear regression was used to assess the association between arsenic exposure at baseline and metabolite levels in baseline urine samples. RESULTS: We identified 2,519 molecular features that were present in all 224 urine samples from the 112 participants, of which 301 had an ICC of ≥0.60. Of the 301 molecular features, water arsenic was significantly related to 31 molecular features and urinary arsenic was significantly related to 74 molecular features after adjusting for multiple comparisons. Six metabolites with a confirmed identity were identified from the 82 molecular features that were significantly associated with either water arsenic or urinary arsenic after adjustment for multiple comparisons. CONCLUSIONS: Our study identified urinary metabolites with long-term reproducibility that were associated with arsenic exposure. The data established the feasibility of using metabolomics in future larger studies. https://doi.org/10.1289/EHP1992.

Association of major dietary patterns and blood pressure longitudinal change in Bangladesh.

BACKGROUND: Observational studies and clinical trials have shown associations of diet and high blood pressure (BP). However, prospective studies on the association between dietary patterns and longitudinal BP change are lacking, especially in low-income populations. METHOD: We evaluated the association of dietary patterns and food groups with longitudinal change of BP in 10 389 participants in the Health Effects of Arsenic Longitudinal Study, with a median of 6.7 years of follow-up. Dietary information was obtained through a previously validated food-frequency questionnaire. BP was measured at baseline and at each biennial follow-up using the same method. RESULT: Each standard deviation (SD) increase for the 'gourd vegetable' dietary pattern score was related to a slower annual change of 0.08, 0.04, and 0.05 mmHg in SBP, DBP, or pulse pressure, respectively. Each SD increase in the 'balanced' dietary pattern score was related to a decreasing annual change of 0.06 mmHg (P = 0.012) and 0.08 mmHg in SBP and pulse pressure (P < 0.001). On the contrary, one SD increase in 'western' dietary pattern score was related to a greater annual increase of 0.07 (P = 0.005) and 0.05 mmHg in SBP and pulse pressure (P = 0.013). Higher intake of fruits and vegetables was associated with a slower rate of change in annual SBP and pulse pressure, whereas higher meat intake was related to a more rapid increase in annual pulse pressure. CONCLUSION: The findings suggest that dietary patterns play a significant role in the rate of BP change over time in a low-income population.

Association between Arsenic Exposure from Drinking Water and Longitudinal Change in Blood Pressure among HEALS Cohort Participants.

BACKGROUND: Cross-sectional studies have shown associations between arsenic exposure and prevalence of high blood pressure; however, studies examining the relationship of arsenic exposure with longitudinal changes in blood pressure are lacking. METHOD: We evaluated associations of arsenic exposure in relation to longitudinal change in blood pressure in 10,853 participants in the Health Effects of Arsenic Longitudinal Study (HEALS). Arsenic was measured in well water and in urine samples at baseline and in urine samples every 2 years after baseline. Mixed-effect models were used to estimate the association of baseline well and urinary creatinine-adjusted arsenic with annual change in blood pressure during follow-up (median, 6.7 years). RESULT: In the HEALS population, the median water arsenic concentration at baseline was 62 µg/L. Individuals in the highest quartile of baseline water arsenic or urinary creatinine-adjusted arsenic had a greater annual increase in systolic blood pressure compared with those in the reference group (ß = 0.48 mmHg/year; 95% CI: 0.35, 0.61, and ß = 0.43 mmHg/year; 95% CI: 0.29, 0.56 for water arsenic and urinary creatinine-adjusted arsenic, respectively) in fully adjusted models. Likewise, individuals in the highest quartile of baseline arsenic exposure had a greater annual increase in diastolic blood pressure for water arsenic and urinary creatinine-adjusted arsenic, (ß = 0.39 mmHg/year; 95% CI: 0.30, 0.49, and ß = 0.45 mmHg/year; 95% CI: 0.36, 0.55, respectively) compared with those in the lowest quartile. CONCLUSION: Our findings suggest that long-term arsenic exposure may accelerate age-related increases in blood pressure. These findings may help explain associations between arsenic exposure and cardiovascular disease.

A prospective study of arm circumference and risk of death in Bangladesh.

BACKGROUND: Epidemiological studies have observed protective effects of mid-upper arm circumference (MUAC) against all-cause mortality mostly in Western populations. However, evidence on cause-specific mortality is limited. METHODS: The sample included 19 575 adults from a population-based cohort study in rural Bangladesh, who were followed up for an average of 7.9 years for mortality. Cox proportional hazards regression was used to evaluate the effect of MUAC, as well as the joint effect of body mass index (BMI) and MUAC, on the risk of death from any cause, cancer and cardiovascular disease (CVD). RESULTS: During 154 664 person-years of follow-up, 744 deaths including 312 deaths due to CVD and 125 deaths due to cancer were observed. There was a linear inverse relationship of MUAC with total and CVD mortality. Each 1-cm increase in MUAC was associated a reduced risk of death from any cause [hazard ratio (HR) = 0.85; 95% confidence interval (C), 0.81-0.89) and CVD (HR = 0.87; 95% CI, 0.80-0.94), after controlling for potential confounders. No apparent relationship between MUAC and the risk of death from cancer was observed. Among individuals with a low BMI (<18.5 kg/m(2)), a MUAC less than 24 cm was associated with increased risk for all-cause (HR = 1.81; 95% CI, 1.52-2.17) and CVD mortality (HR = 1.45; 95% CI, 1.11-1.91). CONCLUSIONS: MUAC may play a critical role on all-cause and CVD mortality in lean Asians.

A prospective study of arsenic exposure, arsenic methylation capacity, and risk of cardiovascular disease in Bangladesh.

BACKGROUND: Few prospective studies have evaluated the influence of arsenic methylation capacity on cardiovascular disease (CVD) risk. OBJECTIVE: We evaluated the association of arsenic exposure from drinking water and arsenic methylation capacity with CVD risk. METHOD: We conducted a case-cohort study of 369 incident fatal and nonfatal cases of CVD, including 211 cases of heart disease and 148 cases of stroke, and a subcohort of 1,109 subjects randomly selected from the 11,224 participants in the Health Effects of Arsenic Longitudinal Study (HEALS). RESULTS: The adjusted hazard ratios (aHRs) for all CVD, heart disease, and stroke in association with a 1-SD increase in baseline well-water arsenic (112 µg/L) were 1.15 (95% CI: 1.01, 1.30), 1.20 (95% CI: 1.04, 1.38), and 1.08 (95% CI: 0.90, 1.30), respectively. aHRs for the second and third tertiles of percentage urinary monomethylarsonic acid (MMA%) relative to the lowest tertile, respectively, were 1.27 (95% CI: 0.85, 1.90) and 1.55 (95% CI: 1.08, 2.23) for all CVD, and 1.65 (95% CI: 1.05, 2.60) and 1.61 (95% CI: 1.04, 2.49) for heart disease specifically. The highest versus lowest ratio of urinary dimethylarsinic acid (DMA) to MMA was associated with a significantly decreased risk of CVD (aHR = 0.54; 95% CI: 0.34, 0.85) and heart disease (aHR = 0.54; 95% CI: 0.33, 0.88). There was no significant association between arsenic metabolite indices and stroke risk. The effects of incomplete arsenic methylation capacity--indicated by higher urinary MMA% or lower urinary DMA%--with higher levels of well-water arsenic on heart disease risk were additive. There was some evidence of a synergy of incomplete methylation capacity with older age and cigarette smoking. CONCLUSIONS: Arsenic exposure from drinking water and the incomplete methylation capacity of arsenic were adversely associated with heart disease risk.

Arsenic exposure from drinking water and QT-interval prolongation: results from the Health Effects of Arsenic Longitudinal Study.

BACKGROUND: Arsenic exposure from drinking water has been associated with heart disease; however, underlying mechanisms are uncertain. OBJECTIVE: We evaluated the association between a history of arsenic exposure from drinking water and the prolongation of heart rate-corrected QT (QTc), PR, and QRS intervals. METHOD: We conducted a study of 1,715 participants enrolled at baseline from the Health Effects of Arsenic Longitudinal Study. We assessed the relationship of arsenic exposure in well water and urine samples at baseline with parameters of electrocardiogram (ECG) performed during 2005-2010, 5.9 years on average since baseline. RESULTS: The adjusted odds ratio (OR) for QTc prolongation, defined as a QTc ≥ 450 msec in men and ≥ 460 msec in women, was 1.17 (95% CI: 1.01, 1.35) for a 1-SD increase in well-water arsenic (108.7 µg/L). The positive association appeared to be limited to women, with adjusted ORs of 1.24 (95% CI: 1.05, 1.47) and 1.24 (95% CI: 1.01, 1.53) for a 1-SD increase in baseline well-water and urinary arsenic, respectively, compared with 0.99 (95% CI: 0.73, 1.33) and 0.86 (95% CI: 0.49, 1.51) in men. There were no apparent associations of baseline well-water arsenic or urinary arsenic with PR or QRS prolongation in women or men. CONCLUSIONS: Long-term arsenic exposure from drinking water (average 95 µg/L; range, 0.1-790 µg/L) was associated with subsequent QT-interval prolongation in women. Future longitudinal studies with repeated ECG measurements would be valuable in assessing the influence of changes in exposure.