Glucose Metabolic Disorders Enhance Vascular Dysfunction Triggered by Particulate Air Pollution: a Panel Study

Fine particulate matter exposure and systemic inflammation: A potential mediating role of bioactive lipids

Inflammation is a key mechanism underlying the adverse health effects of exposure to fine particulate matter (PM2.5). Bioactive lipids in the arachidonic acid (ARA) pathway are important in the regulation of inflammation and are reportedly altered by PM2.5 exposure. Ceramide-1-phosphate (C1P), a class of sphingolipids, is required to initiate ARA metabolism. We examined the role of C1P in the alteration of ARA metabolism after PM2.5 exposure and explored whether changes in the ARA pathway promoted systemic inflammation based on a panel study involving 112 older adults in Beijing, China. Ambient PM2.5 levels were continuously monitored at a fixed station from 2013 to 2015. Serum cytokine levels were measured to assess systemic inflammation. Multiple bioactive lipids in the ARA pathway and three subtypes of C1P were quantified in blood samples. Mediation analyses were performed to test the hypotheses. We observed that PM2.5 exposure was positively associated with inflammatory cytokines and the three subtypes of C1P. Mediation analyses showed that C1P significantly mediated the associations of ARA and 5, 6-dihydroxyeicosatrienoic acid (5, 6-DHET), an ARA metabolite, with PM2.5 exposure. ARA, 5, 6-DHET, and leukotriene B4 mediated systemic inflammatory response to PM2.5 exposure. For example, C1P C16:0 (a subtype of C1P) mediated a 12.9 % (95 % confidence interval: 3.7 %, 32.5 %) increase in ARA associated with 3-day moving average PM2.5 exposure, and ARA mediated a 27.1 % (7.8 %, 61.2 %) change in interleukin-8 associated with 7-day moving average PM2.5 exposure. Our study indicates that bioactive lipids in the ARA and sphingolipid metabolic pathways may mediate systemic inflammation after PM2.5 exposure.

Particulate Air Pollution and Blood Pressure: Signaling by the Arachidonate Metabolism

BACKGROUND

Short-term exposure to ambient particulate matter (PM) can raise blood pressure, but the underlying mechanisms are unclear. We explored whether arachidonate metabolites serve as biological intermediates in PM-associated prohypertensive changes.

METHODS

This panel study recruited 110 adults aged 50 to 65 years living in Beijing, China. The participants' blood pressure, arterial stiffness, and cardiac and endothelial function were measured up to 7 times. The serum concentrations of arachidonate metabolites were quantified by targeted lipidomics. Ambient concentrations of fine PM (PM2.5), black carbon, and accumulation mode particles were continuously monitored at a station and their associations with the health indicators were evaluated.

RESULTS

Interquartile range increases in 25 to 96-hour-lag exposure to PM2.5, black carbon, and accumulation mode particles were associated with significant increases in systolic blood pressure (brachial: 0.8-3.2 mm Hg; central: 0.7-2.8 mm Hg) and diastolic blood pressure (brachial, 0.5-1.5 mm Hg; central, 0.5-1.6 mm Hg). At least 1 pollutant was associated with increases in augmentation pressure and heart rate and decreases in reactive hyperemia index and ejection time. The serum concentrations of arachidonate were significantly increased by 3.3% to 14.6% in association with PM exposure, which mediated 9% of the PM-associated increases in blood pressure. The levels of eicosanoids from the cytochrome P450, cyclooxygenase, and lipoxygenase pathways changed with PM exposure, and those from the cytochrome pathway significantly mediated the association between PM exposure and blood pressure.

CONCLUSIONS

Short-term exposure to particulate air pollution was associated with a prohypertensive change in adults, which was in part mediated by alteration of arachidonate metabolism.

Long-Term Exposure to Fine Particulate Constituents and Vascular Damage in a Population with Metabolic Abnormality in China

AIM

To date, PM2.5-associated vascular damage in metabolic abnormalities has remained controversial. We knew little about the vascular damage of PM2.5 constituents. Thus, this study aimed to investigate the relationship between long-term exposure to PM2.5 and its constituents and vascular damage in metabolic abnormalities.

METHODS

A total of 124,387 participants with metabolic abnormalities (defined as at least one metabolic disorder, such as obesity, elevated blood pressure, elevated triglyceride level, elevated fasting glucose level, or low HDL cholesterol level) were recruited in this study from 11 representative centers in China between January 2011 and December 2017. PM2.5 and its constituents (black carbon [BC], organic matter [OM], sulfate [SO42-], nitrate [NO3-], and ammonium salts [NH4＋]) were extracted. Elevated brachial-ankle pulse wave velocity (baPWV) (≥ 1,400 cm/s) and declined ankle-brachial index (ABI) (＜0.9) indicated vascular damage. Multivariable logistic regression and Quantile g-Computation models were utilized to explore the impact on outcomes.

RESULTS

Of the 124,387 participants (median age, 49 years), 87,870 (70.64%) were men. One-year lag exposure to PM2.5 and its constituents was significantly associated with vascular damage in single pollutant models. The adjusted odds ratios (OR) for each 1-µg/m3 increase in PM2.5 was 1.013 (95% CI, 1.012-1.015) and 1.031 (95% CI, 1.025-1.037) for elevated baPWV and decreased ABI, respectively. PM2.5 constituents were also associated with vascular damage in multi-pollutant models. Among the PM2.5 constituents, BC (47.17%), SO42- (33.59%), and NH4＋ (19.23%) have the highest contribution to elevated baPWV and NO3- (47.89%) and BC (23.50%) to declined ABI.

CONCLUSION

Chronic exposure to PM2.5 and PM2.5 constituents was related to vascular damage in the abnormal metabolic population in China. The heterogeneous contribution of different PM2.5 constituents to vessel bed damage is worthy of attention when developing targeted strategies.

Air pollution exposure and vascular endothelial function: a systematic review and meta-analysis

Vascular endothelial dysfunction is an early stage to cardiovascular diseases (CVDs), but whether air pollution exposure has an effect on it remains unknown. We conducted a systematic review and meta-analysis to summarize epidemiological evidence between air pollution and endothelial dysfunction. We searched the database of PubMed, EMBASE, the Cochrane Library, and Web of Science up to November 10, 2022. Fixed and random effect models were used to pool the effect change or percent change (% change) and 95% confidence interval (95% CI) of vascular function associated with particulate matter (PM) and gaseous pollutants. I² statistics, funnel plot, and Egger's test were used to evaluate heterogeneity and publication bias. There were 34 articles included in systematic review, and 25 studies included in meta-analysis. For each 10 µg/m³ increment in short-term PM_2.5 exposure, augmentation index (AIx) and pulse wave velocity (PWV) increased by 2.73% (95% CI: 1.89%, 3.57%) and 0.56% (95% CI: 0.22%, 0.89%), and flow-mediated dilation (FMD) decreased by 0.17% (95% CI: - 0.33%, - 0.00%). For each 10 µg/m³ increment in long-term PM_2.5 exposure, FMD decreased by 0.99% (95% CI: - 1.41%, - 0.57%). The associations between remaining pollutants and outcomes were not statistically significant. The effect of short-term PM_2.5 exposure on FMD change was stronger in population with younger age, lower female proportion, higher mean body mass index and higher PM_2.5 exposure. Cardiac or vasoactive medication might attenuate this effect. Our study provides evidence that PM_2.5 exposure had adverse impact on vascular endothelial function, indicating the importance of air quality improvement for early CVD prevention.

Cumulative effects of temperature on blood pressure during pregnancy: A cohort study of differing effects in three trimesters

BACKGROUND

Little is known about the non-linear cumulative effects of temperature on blood pressure (BP) during pregnancy. We investigated the differing effects of daily ambient temperature on BP for up to 30 days in three trimesters.

METHODS

The first, second, and third trimester analyses included 2547, 2299, and 2011 pregnant women, respectively, from a prospective cohort in Nanjing from January 2017 to January 2020. BP was measured at each follow-up visit. The individual daily temperature exposures were calculated for 30 days prior to the follow-up date. The Distributed Lag Non-linear Model was used to investigate the relationship between temperature and BP in each trimester.

RESULTS

Temperatures under 15 °C elevate systolic, diastolic BP, and mean arterial pressure (SBP, DBP, and MAP) in the first trimester, while temperatures above 15 °C reduce SBP in the second and third trimesters. By using Distributed Lag Linear Models, we estimated that with a 1 °C decrease in daily temperature, the SBP and DBP increased by 0.32 (95 % CI: 0.12, 0.52) and 0.23 (95 % CI: 0.07, 0.39) mmHg, respectively, in the first trimester with a 20-day cumulative lag, while with a 1 °C increase in daily temperature, the SBP decreased by 0.23 (0.35, 0.10) mmHg in the third trimester with a 30-day cumulative lag. The significant effects of temperature mainly manifested between 2 and 4 weeks of exposure.

CONCLUSIONS

Temperature has different effects on BP over three trimesters. Protective measures to reduce cold-related BP rise will help reduce the risk of hypertensive disorders of pregnancy.

Subendocardial Viability Ratio Predictive Value for Cardiovascular Risk in Hypertensive Patients

Background: The subendocardial viability ratio (SEVR), also known as the Buckberg index, is a parameter of arterial stiffness with indirect prognostic value in assessing long-term cardiovascular risk. Materials and Methods: We conducted a prospective cohort study on 70 patients with uncomplicated hypertension admitted to a county medical reference hospital. We analyzed demographics, laboratory data, arterial stiffness parameters and cardiovascular risk scores (SCORE and Framingham risk scores) and aimed to identify paraclinical parameters associated with increased cardiovascular risk. Results: Of the arterial stiffness parameters, SEVR correlates statistically significantly with age, central and peripheral systolic blood pressure, as well as with heart rate. SEVR seems to have prognostic value among hypertensive patients by increasing the risk of major cardiovascular events assessed by SCORE and Framingham risk scores. SEVR correlates statistically significantly with serum fibrinogen (p = 0.02) and hemoglobin (p = 0.046). Between pulse wave velocity and lipid parameters (p = 0.021 for low-density lipoprotein cholesterol <LDL> and p = 0.030 for triglycerides) a statistically significant relationship was found for the study group. The augmentation index of the aorta also correlated with serum LDL-cholesterol (p = 0.032) and the hemoglobin levels (p = 0.040) of hypertensive patients. Conclusions: Age, abdominal circumference and Framingham score are independent predictors for SEVR in our study group, further highlighting the need for early therapeutic measures to control risk factors in this category of patients.

The underlying mechanism of PM2.5-induced ischemic stroke

Under the background of global industrialization, PM_2.5 has become the fourth-leading risk factor for ischemic stroke worldwide, according to the 2019 GBD estimates. This highlights the hazards of PM_2.5 for ischemic stroke, but unfortunately, PM_2.5 has not received the attention that matches its harmfulness. This article is the first to systematically describe the molecular biological mechanism of PM_2.5-induced ischemic stroke, and also propose potential therapeutic and intervention strategies. We highlight the effect of PM_2.5 on traditional cerebrovascular risk factors (hypertension, hyperglycemia, dyslipidemia, atrial fibrillation), which were easily overlooked in previous studies. Additionally, the effects of PM_2.5 on platelet parameters, megakaryocytes activation, platelet methylation, and PM_2.5-induced oxidative stress, local RAS activation, and miRNA alterations in endothelial cells have also been described. Finally, PM_2.5-induced ischemic brain pathological injury and microglia-dominated neuroinflammation are discussed. Our ultimate goal is to raise the public awareness of the harm of PM_2.5 to ischemic stroke, and to provide a certain level of health guidance for stroke-susceptible populations, as well as point out some interesting ideas and directions for future clinical and basic research.