The causal effect of air pollution on the risk of essential hypertension: a Mendelian randomization study

Causal Relationship Between Air Pollutants and Blood Pressure Phenotypes: A Mendelian Randomization Study

Objectives

Hypertension is a chronic disease widely prevalent around the world. While previous observational studies have suggested a link between air pollutants and an increased risk of hypertension, causality has not been established. Our study aimed to investigate potential causal relationships between five air pollutants and four blood pressure phenotypes through two-sample Mendelian randomization.

Methods

Two-sample Mendelian randomization (MR) analyses were performed using genome-wide association studies (GWAS) data from the IEU OpenGWAS project. The main analysis method was the inverse variance weighting (IVW) method. Heterogeneity was assessed by Cochran's Q test, while pleiotropy was assessed by MR-Egger regression. Sensitivity analysis was performed by weighted median method, MR-Egger method, simple mode method, weighted mode method, and leave-one-out analysis method.

Results

Mendelian randomization results showed positive causal associations between PM10 with hypertension (OR: 1.49; 95%CI: 1.06, 2.09; P: 2.23 × 10-2) and systolic blood pressure (β: 1.89; 95%CI: 0.32, 3.47; P: 1.85 × 10-2), positive causal associations between PM2.5 and hypertension (OR: 1.26; 95%CI: 1.01, 2.58; P: 4.30 × 10-2), and negative causal associations between NO2 and systolic blood pressure (β: -1.71; 95%CI: -3.39, -0.02; P: 4.74 × 10-2). None of the above associations were subject to pleiotropic bias, and all associations were heterogeneous except for PM10 and hypertension. The leave-one-out analysis showed that no single SNP affected the stability of the results.

Conclusion

Elevated levels of PM2.5 and PM10 have been associated with an increased risk of developing hypertension, with PM10 specifically linked to higher systolic blood pressure levels. Interestingly, NO2 has shown potential as a protective factor in lowering systolic blood pressure. This study clarifies the causal relationship between five air pollutants and elevated blood pressure. Ensuring good ambient air quality is essential in preventing hypertension and reducing the overall disease burden.

Global hotspots and trends on environmental exposure and cardiovascular disease from 1999 to 2022

BACKGROUND

The increasing risk of cardiovascular disease (CVD) associated with worsening environmental exposure is a critical health concern garnering global research attention.

AIM

To systematically assess the scope and characteristics of research on the relationship between environmental exposure and CVD.

METHODS

A thorough examination of publications on the relationship between environmental exposure and CVD from 1999 to 2022 was carried out by extensively screening the literature using the Web of Science Core Collection. The language of the selected publications was standardized to English. Afterward, different academic tools such as CiteSpace, VOSviewer, HistCite, Python, Matplotlib, and Bibliometrix were utilized to examine the research trends in this field.

RESULTS

The study's findings indicated a steady increase in scientific publications among the 1640 analyzed documents, peaking in 2022 with 197 publications. The United States emerged as the leading nation regarding high-quality publications and international collaboration. Harvard University was identified as the most prolific institution. "Environmental research" was the most frequently contributing journal, and Muenzel T was recognized as the top contributor. Current research hotspots are primarily concentrated on themes such as "cardiovascular disease", "exposure", "risk", "mortality", and "air pollution".

CONCLUSION

This study highlights increasing research on the link between environmental exposure and CVD, identifying key exposures and diseases while emphasizing the need for further investigation into underlying mechanisms.

Inhibitory neuron links the causal relationship from air pollution to psychiatric disorders: a large multi-omics analysis

Psychiatric disorders are severe health challenges that exert a heavy public burden. Air pollution has been widely reported as related to psychiatric disorder risk, but their casual association and pathological mechanism remained unclear. Herein, we systematically investigated the large genome-wide association studies (6 cohorts with 1,357,645 samples), single-cell RNA (26 samples with 157,488 cells), and bulk-RNAseq (1595 samples) datasets to reveal the genetic causality and biological link between four air pollutants and nine psychiatric disorders. As a result, we identified ten positive genetic correlations between air pollution and psychiatric disorders. Besides, PM2.5 and NO2 presented significant causal effects on schizophrenia risk which was robust with adjustment of potential confounders. Besides, transcriptome-wide association studies identified the shared genes between PM2.5/NO2 and schizophrenia. We then discovered a schizophrenia-derived inhibitory neuron subtype with highly expressed shared genes and abnormal synaptic and metabolic pathways by scRNA analyses and confirmed their abnormal level and correlations with the shared genes in schizophrenia patients in a large RNA-seq cohort. Comprehensively, we discovered robust genetic causality between PM2.5, NO2, and schizophrenia and identified an abnormal inhibitory neuron subtype that links schizophrenia pathology and PM2.5/NO2 exposure. These discoveries highlight the schizophrenia risk under air pollutants exposure and provide novel mechanical insights into schizophrenia pathology, contributing to pollutant-related schizophrenia risk control and therapeutic strategies development.

Graphical Abstract

Disease types and pathogenic mechanisms induced by PM2.5 in five human systems: An analysis using omics and human disease databases

Atmospheric fine particulate matter (PM2.5) can harm various systems in the human body. Due to limitations in the current understanding of epidemiology and toxicology, the disease types and pathogenic mechanisms induced by PM2.5 in various human systems remain unclear. In this study, the disease types induced by PM2.5 in the respiratory, circulatory, endocrine, and female and male urogenital systems have been investigated and the pathogenic mechanisms identified at molecular level. The results reveal that PM2.5 is highly likely to induce pulmonary emphysema, reperfusion injury, malignant thyroid neoplasm, ovarian endometriosis, and nephritis in each of the above systems respectively. The most important co-existing gene, cellular component, biological process, molecular function, and pathway in the five systems targeted by PM2.5 are Fos proto-oncogene (FOS), extracellular matrix, urogenital system development, extracellular matrix structural constituent conferring tensile strength, and ferroptosis respectively. Differentially expressed genes that are significantly and uniquely targeted by PM2.5 in each system are BTG2 (respiratory), BIRC5 (circulatory), NFE2L2 (endocrine), TBK1 (female urogenital) and STAT1 (male urogenital). Important disease-related cellular components, biological processes, and molecular functions are specifically induced by PM2.5. For example, response to wounding, blood vessel morphogenesis, body morphogenesis, negative regulation of response to endoplasmic reticulum stress, and response to type I interferon are the top uniquely existing biological processes in each system respectively. PM2.5 mainly acts on key disease-related pathways such as the PD-L1 expression and PD-1 checkpoint pathway in cancer (respiratory), cell cycle (circulatory), apoptosis (endocrine), antigen processing and presentation (female urogenital), and neuroactive ligand-receptor interaction (male urogenital). This study provides a novel analysis strategy for elucidating PM2.5-related disease types and is an important supplement to epidemiological investigation. It clarifies the risks of PM2.5 exposure, elucidates the pathogenic mechanisms, and provides scientific support for promoting the precise prevention and treatment of PM2.5-related diseases.