Vulnerability to cardiovascular effects of air pollution in people with diabetes

Inflammation and acute traffic-related air pollution exposures among a cohort of youth with type 1 diabetes

BACKGROUND

Evidence remains equivocal regarding the association of inflammation, a precursor to cardiovascular disease, and acute exposures to ambient air pollution from traffic-related particulate matter. Though youth with type 1 diabetes are at higher risk for cardiovascular disease, the relationship of inflammation and ambient air pollution exposures in this population has received little attention.

OBJECTIVES

Using five geographically diverse US sites from the racially- and ethnically-diverse SEARCH for Diabetes in Youth Cohort, we examined the relationship of acute exposures to PM2.5 mass, Atmospheric Dispersion Modeling System (ADMS)-Roads traffic-related PM concentrations near roadways, and elemental carbon (EC) with biomarkers of inflammation including interleukin-6 (IL-6), c-reactive protein (hs-CRP) and fibrinogen.

METHODS

Baseline questionnaires and blood were obtained at a study visit. Using a spatio-temporal modeling approach, pollutant exposures for 7 days prior to blood draw were assigned to residential addresses. Linear mixed models for each outcome and exposure were adjusted for demographic and lifestyle factors identified a priori.

RESULTS

Among the 2566 participants with complete data, fully-adjusted models showed positive associations of EC average week exposures with IL-6 and hs-CRP, and PM2.5 mass exposures on lag day 3 with IL-6 levels. Comparing the 25th and 75th percentiles of average week EC exposures resulted in 8.3% higher IL-6 (95%CI: 2.7%,14.3%) and 9.8% higher hs-CRP (95%CI: 2.4%,17.7%). We observed some evidence of effect modification for the relationships of PM2.5 mass exposures with hs-CRP by gender and with IL-6 by race/ethnicity.

CONCLUSIONS

Indicators of inflammation were associated with estimated traffic-related air pollutant exposures in this study population of youth with type 1 diabetes. Thus youth with type 1 diabetes may be at increased risk of air pollution-related inflammation. These findings and the racial/ethnic and gender differences observed deserve further exploration.

Differential Susceptibility in Ambient Particle-Related Risk of First-Ever Stroke: Findings From a National Case-Crossover Study

Different populations may respond differently to exposure to ambient fine particulate matter, defined as particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5); however, less is known about the distribution of susceptible individuals among the entire population. We conducted a time-stratified case-crossover study to assess associations between stroke risk and exposure to PM2.5. During 2013-2015, 1,356 first-ever stroke events were derived from a large representative sample, the China National Stroke Screening Survey (CNSSS) database. Daily PM2.5 average exposures with a spatial resolution of 0.1° were estimated using a data assimilation approach combining satellite measurements, air model simulations, and monitoring values. The distribution of susceptibility was derived according to individual-specific associations with PM2.5 modified by different combinations of individual-level characteristics and their joint frequencies among all of the CNSSS participants (n = 1,292,010). We found that first-ever stroke was statistically significantly associated with PM2.5 (per 10-μg/m3 increment of exposure, odds ratio = 1.049, 95% confidence interval (CI): 1.038, 1.061). This association was modified by demographic (e.g., sex), lifestyle (e.g., overweight/obesity), and medical history (e.g., diabetes) variables. The combined association with PM2.5 varied from 0.966 (95% CI: 0.920, 1.013) to 1.145 (95% CI: 1.080, 1.215) per 10-μg/m3 increment in different subpopulations. We found that most of the CNSSS participants were at increased risk of PM2.5-related stroke, while only a small proportion were highly susceptible.

Short-Term Exposure to Air Pollution and Biomarkers of Oxidative Stress: The Framingham Heart Study

BACKGROUND

Short-term exposure to elevated air pollution has been associated with higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution hypothesized as an important underlying mechanism. However, few community-based studies have assessed this association.

METHODS AND RESULTS

Two thousand thirty-five Framingham Offspring Cohort participants living within 50 km of the Harvard Boston Supersite who were not current smokers were included. We assessed circulating biomarkers of oxidative stress including blood myeloperoxidase at the seventh examination (1998-2001) and urinary creatinine-indexed 8-epi-prostaglandin F2α (8-epi-PGF2α) at the seventh and eighth (2005-2008) examinations. We measured fine particulate matter (PM2.5), black carbon, sulfate, nitrogen oxides, and ozone at the Supersite and calculated 1-, 2-, 3-, 5-, and 7-day moving averages of each pollutant. Measured myeloperoxidase and 8-epi-PGF2α were loge transformed. We used linear regression models and linear mixed-effects models with random intercepts for myeloperoxidase and indexed 8-epi-PGF2α, respectively. Models were adjusted for demographic variables, individual- and area-level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of PM2.5 and black carbon with myeloperoxidase across multiple moving averages. Additionally, 2- to 7-day moving averages of PM2.5 and sulfate were consistently positively associated with 8-epi-PGF2α. Stronger positive associations of black carbon and sulfate with myeloperoxidase were observed among participants with diabetes than in those without.

CONCLUSIONS

Our community-based investigation supports an association of select markers of ambient air pollution with circulating biomarkers of oxidative stress.

AIR POLLUTION INFLUENCES ON EXHALED NITRIC OXIDE AMONG PEOPLE WITH TYPE II DIABETES

OBJECTIVE

In a population with type 2 diabetes mellitus (T2DM), we examined associations of short-term air pollutant exposures with pulmonary inflammation, measured as fraction of exhaled pulmonary nitric oxide (FeNO).

METHODS

Sixty-nine Boston Metropolitan residents with T2DM completed up to 5 bi-weekly visits with 321 offline FeNO measurements. We measured ambient concentrations of particle mass, number and components at our stationary central site. Ambient concentrations of gaseous air pollutants were obtained from state monitors. We used linear models with fixed effects for participants, adjusting for 24-hour mean temperature, 24-hour mean water vapor pressure, season, and scrubbed room NO the day of the visit, to estimate associations between FeNO and interquartile range increases in exposure.

RESULTS

Interquartile increases in the 6-hour averages of black carbon (BC) (0.5 μg/m³) and particle number (PN) (1,000 particles/cm³) were associated with increases in FeNO of 3.84% (95% CI 0.60% to 7.18%) and 9.86 % (95% CI 3.59% to 16.52%), respectively. We also found significant associations of increases in FeNO with increases in 24-hour moving averages of BC, PN and nitrogen oxides (NOx).

CONCLUSION

Recent studies have focused on FeNO as a marker for eosinophilic pulmonary inflammation in asthmatic populations. This study adds support to the relevance of FeNO as a marker for pulmonary inflammation in diabetic populations, whose underlying chronic inflammatory status is likely to be related to innate immunity and proinflammatory adipokines.

Medication type modifies inflammatory response to traffic exposure in a population with type 2 diabetes

The association between residential traffic exposure and change in C-reactive protein over 2-years was evaluated using multivariate linear regression including interaction models for traffic and diabetes medication use/type (insulin vs. oral hypoglycemic agents (OHAs)). The study population was Puerto Rican adults (n = 356) residing in greater Boston with type 2 diabetes. Traffic was characterized as proximity to roads with >20,000 weekday traffic volumes, and multi-directional traffic density. Increases in CRP concentration were significantly associated with residence ≤100 m of a roadway (p = 0.009) or near multiple roadways (p < 0.001), vs. further away, for individuals using insulin in stratified models, with consistent results in interaction models (p = 0.071 and p = 0.002). CRP was significantly lower with highest traffic density exposure in stratified (p = 0.03) and interaction models (p = 0.024) for individuals using OHAs. Individuals on insulin experienced increased CRP concentrations with traffic exposure over a 2-year study period, while those using OHAs did not experience increases.

Size-fractioned ultrafine particles and black carbon associated with autonomic dysfunction in subjects with diabetes or impaired glucose tolerance in Shanghai, China

BACKGROUND

Particles in smaller size fractions, such as ultrafine particles (UFPs) (with diameter less than 100 nm), has become of significant cardiovascular health concerns. However, the biological plausibility underlying potential relationship between UFPs and cardiovascular outcomes is less studied.

METHODS

Fifty-three subjects living in Shanghai with type-2 diabetes (T2D) or impaired glucose tolerance (IGT) were followed for autonomic dysfunctions with three repeated measurements in 2010. Minute-to-minute concentrations of ambient particles in small size-fractions (5-560 nm), black carbon (BC), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) were monitored using a central monitoring laboratory equipped with real-time air monitors close to residential area of the subjects. Generalized linear mixed models, with adjustment for individual risk factors, were applied to assess the effects of air pollution on autonomic dysfunctions in subjects.

RESULTS

Our study showed that significant reduction in the standard deviation of all NN intervals (SDNN) ranging from 3.4% to 8.1% were associated with interquartile range (IQR) increase of number concentration of particles (PNC) in size fractions<100 nm, and reduction from 1.3% to 4.6% with particles of diameter 100-200 nm, in subjects with diabetes or glucose tolerance. Increased exposure to traffic-related pollutants BC, NO2 and CO, and combustion pollutant SO2, were also significantly associated with HRV reductions. However, no effect was observed for particles in size fraction of 200-560 nm and O3. Diabetic risk factor and gender appeared to have significant interactions on autonomic dysfunction associated with UFPs and traffic pollution exposures in certain time-window.

CONCLUSIONS

Our results suggest that underlying diabetes or impaired glucose tolerance may confer reduced autonomic function of heart due to traffic pollution exposure.

Air pollution exposure and abnormal glucose tolerance during pregnancy: the project Viva cohort

BACKGROUND

Exposure to fine particulate matter (PM with diameter ≤ 2.5 μm; PM2.5) has been linked to type 2 diabetes mellitus, but associations with hyperglycemia in pregnancy have not been well studied.

METHODS

We studied Boston, Massachusetts-area pregnant women without known diabetes. We identified impaired glucose tolerance (IGT) and gestational diabetes mellitus (GDM) during pregnancy from clinical glucose tolerance tests at median 28.1 weeks gestation. We used residential addresses to estimate second-trimester PM2.5 and black carbon exposure via a central monitoring site and spatiotemporal models. We estimated residential traffic density and roadway proximity as surrogates for exposure to traffic-related air pollution. We performed multinomial logistic regression analyses adjusted for sociodemographic covariates, and used multiple imputation to account for missing data.

RESULTS

Of 2,093 women, 65 (3%) had IGT and 118 (6%) had GDM. Second-trimester spatiotemporal exposures ranged from 8.5 to 15.9 μg/m3 for PM2.5 and from 0.1 to 1.7 μg/m3 for black carbon. Traffic density was 0-30,860 vehicles/day × length of road (kilometers) within 100 m; 281 (13%) women lived ≤ 200 m from a major road. The prevalence of IGT was elevated in the highest (vs. lowest) quartile of exposure to spatiotemporal PM2.5 [odds ratio (OR) = 2.63; 95% CI: 1.15, 6.01] and traffic density (OR = 2.66; 95% CI: 1.24, 5.71). IGT also was positively associated with other exposure measures, although associations were not statistically significant. No pollutant exposures were positively associated with GDM.

CONCLUSIONS

Greater exposure to PM2.5 and other traffic-related pollutants during pregnancy was associated with IGT but not GDM. Air pollution may contribute to abnormal glycemia in pregnancy.

Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study

BACKGROUND

Extreme weather and air pollution are associated with increased cardiovascular risk in people with diabetes.

OBJECTIVES

In a population with diabetes, we conducted a novel assessment of vascular brachial artery responses both to ambient pollution and to weather (temperature and water vapor pressure, a measure of humidity).

METHODS

Sixty-four 49- to 85-year-old Boston residents with type 2 diabetes completed up to five study visits (279 repeated measures). Brachial artery diameter (BAD) was measured by ultrasound before and after brachial artery occlusion [i.e., flow-mediated dilation (FMD)] and before and after nitroglycerin-mediated dilation (NMD). Ambient concentrations of fine particulate mass (PM2.5), black carbon (BC), organic carbon (OC), elemental carbon, particle number, and sulfate were measured at our monitoring site; ambient concentrations of carbon monoxide, nitrogen dioxide, and ozone were obtained from state monitors. Particle exposure in the home and during each trip to the clinic (home/trip exposure) was measured continuously and as a 5-day integrated sample. We used linear models with fixed effects for participants, adjusting for date, season, temperature, and water vapor pressure on the day of each visit, to estimate associations between our outcomes and interquartile range increases in exposure.

RESULTS

Baseline BAD was negatively associated with particle pollution, including home/trip-integrated BC (-0.02 mm; 95% CI: -0.04, -0.003, for a 0.28 μg/m3 increase in BC), OC (-0.08 mm; 95% CI: -0.14, -0.03, for a 1.61 μg/m3 increase) as well as PM2.5, 5-day average ambient PM2.5, and BC. BAD was positively associated with ambient temperature and water vapor pressure. However, exposures were not consistently associated with FMD or NMD.

CONCLUSION

Brachial artery diameter, a predictor of cardiovascular risk, decreased in association with particle pollution and increased in association with ambient temperature in our study population of adults with type 2 diabetes.

CITATION

Zanobetti A, Luttmann-Gibson H, Horton ES, Cohen A, Coull BA, Hoffmann B, Schwartz JD, Mittleman MA, Li Y, Stone PH, de Souza C, Lamparello B, Koutrakis P, Gold DR. 2014. Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study. Environ Health Perspect 122:242-248; http://dx.doi.org/10.1289/ehp.1206136.

Systemic inflammation (C-reactive protein) in type 2 diabetic patients is associated with ambient air pollution in Pune City, India

OBJECTIVE

To study the association between ambient air pollutants and serum C-reactive protein (CRP) concentration in 1,392 type 2 diabetic patients in Pune, India.

RESEARCH DESIGN AND METHODS

A cross-sectional study was conducted that linked daily time series of ambient air pollution data (obtained from central monitoring sites) and plasma CRP concentration in type 2 diabetic patients from the Wellcome Trust Genetic (WellGen) Study, recruited between March 2005 and May 2007. Air pollution effects on CRP concentration were investigated with delays (lags) of 0-7 days and multiday averaging spans of 7, 14, and 30 days before blood collection adjusted for age, sex, BMI, hemoglobin, fasting plasma glucose, treatment with agents with anti-inflammatory action, season, air temperature, and relative humidity.

RESULTS

Median CRP concentration was 3.49 mg/L. For 1 SD increase in SO(2) and oxides of nitrogen (NO(x)) concentrations in ambient air, a day before blood collection (lag(1)), we observed a significant increase in CRP (9.34 and 7.77%, respectively). The effect was higher with lag(2) (12.42% for SO(2) and 11.60% for NO(x)) and wore off progressively thereafter. We also found a significant association with multiday averaging times of up to 30 and 7 days for SO(2) and NO(x), respectively. No significant associations were found between particulate matter with an aerodynamic profile ≤10 µm (PM(10)) and CRP concentration except in summer. The association was significantly higher among patients with a shorter duration of diabetes, and in those not on statin and thiazolidinedione treatment.

CONCLUSIONS

We demonstrate, for the first time, a possible contribution of ambient air pollution to systemic inflammation in Indian type 2 diabetic patients. This may have implications for vascular complications of diabetes.

Air pollution and autonomic and vascular dysfunction in patients with cardiovascular disease: interactions of systemic inflammation, overweight, and gender

The authors conducted a 2-year follow-up of 40 cardiovascular disease patients (mean age = 65.6 years (standard deviation, 5.8)) who underwent repeated measurements of cardiovascular response before and during the 2008 Beijing Olympics (Beijing, China), when air pollution was strictly controlled. Ambient levels of particulate matter with an aerodynamic diameter less than 2.5 µm (PM(2.5)), black carbon, nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide were measured continuously, with validation of concurrent real-time measurements of personal exposure to PM(2.5) and carbon monoxide. Linear mixed-effects models were used with adjustment for individual risk factors, time-varying factors, and meteorologic effects. Significant heart rate variability reduction and blood pressure elevation were observed in association with exposure to air pollution. Specifically, interquartile-range increases of 51.8 µg/m(3), 2.02 µg/m(3), and 13.7 ppb in prior 4-hour exposure to PM(2.5), black carbon, and nitrogen dioxide were associated with significant reductions in the standard deviation of the normal-to-normal intervals of 4.2% (95% confidence interval (CI): 1.9, 6.4), 4.2% (95% CI: 1.8, 6.6), and 3.9% (95% CI: 2.2, 5.7), respectively. Greater heart rate variability declines were observed among subjects with C-reactive protein values above the 90th percentile, subjects with a body mass index greater than 25, and females. The authors conclude that autonomic and vascular dysfunction may be one of the mechanisms through which air pollution exposure can increase cardiovascular disease risk, especially among persons with systemic inflammation and overweight.

Traffic exposure in a population with high prevalence type 2 diabetes--do medications influence concentrations of C-reactive protein?

Type 2 Diabetes (T2D) and particulate air pollution are associated with inflammatory dysregulation. We assessed the modifying effects of diabetes medications on the association of C-reactive protein (CRP), a marker of inflammation, and traffic exposure in adults with T2D (n = 379). CRP concentrations were significantly positively associated with residence ≤100 m of a roadway, >100 m and ≤200 m of a roadway and increased traffic density for individuals using insulin. For individuals using oral hypoglycemic medications (OHAs), CRP was significantly negatively associated with residence >100 m - ≤200 m of a roadway and multiple roadway exposure in an interaction model. Among people with diabetes, individuals on insulin appear to be most vulnerable to the effects of traffic exposure. Disease severity among insulin users may promote the pro-inflammatory response to traffic exposure, though diabetes medications may also modify the response. Possible anti-inflammatory effects of OHAs with traffic exposure merit further evaluation.

Geoenvironmental diabetology

Many reports have documented the negative health consequences that environmental stressors can have on patients with diabetes. Studies examining the interaction between the environment and a patient with diabetes can be unified under a single discipline termed "geoenvironmental diabetology." Geoenvironmental diabetology is defined more specifically as the study of how geophysical phenomena impact a patient with diabetes, to include effects on metabolic control, ancillary equipment (e.g., glucometers and insulin pumps), medications, supplies, access to care, and influences on the adaptive strategies employed by patients to care for their diabetes under extreme circumstances. Geological events such as natural disasters (e.g., earthquakes) or extreme weather (e.g., heat waves) are examples of stressors that can affect patients with diabetes and that can be included under the heading of geoenvironmental diabetology. As proposed here, geoenvironmental diabetology refers to how events in the physical world affect those with diagnosed diabetes, rather than how environmental factors might trigger development of disease. As the global prevalence of diabetes continues to increase, including in parts of the world that are especially vulnerable to disasters and climate change, further discussion is warranted on how to best prepare for management of diabetes under conditions of extreme geological and weather events and a changing climate. An overview is presented of various studies that have detailed how geoenvironmental phenomena can adversely affect patients with diabetes and concludes with a discussion of requirements for developing strategies for geoenvironmental diabetes management.