Date Published: June 18, 2018
Publisher: Public Library of Science
Author(s): Yi Sun, Yao Wang, Shu Yuan, Jialing Wen, Weiyu Li, Liu Yang, Xiaoyan Huang, Yanmei Mo, Yingqi Zhao, Yuanming Lu, Rudolf Kirchmair.
This study investigated the association of PM2.5 exposure with VEGF by conducting a systematic review of existing literature and performing a meta-analysis. We searched all the studies published in the Cochrane Library, PUBMED, Embase, China National Knowledge Infrastructure China National Knowledge Infrastructure, and WanFang Electronic Database before June 2017. Finally six studies were identified. It confirmed that the increase in VEGF (β = 1.23 pg/ml, 95% CI: 0.45, 2.01) was significantly associated with the PM2.5 mass concentration of 10 μg/m3. Studies from Canada showed that PM2.5 exposure statistically elevated the level of VEGF level that an increase of 1.20 pg/ml (95% CI: 0.88, 1.52) in VEGF was associated with per 10 μg/m3 increase in PM2.5 concentration. Other subgroup analyses indicated that the effects of PM2.5 exposure on VEGF differed per the in different exposure assessment methods, study designs, and study settings. It was concluded that elevated VEGF levels was significantly positive associated with PM2.5 exposure. Exposure assessment methods and study countries were the major sources of heterogeneity among studies.
Environmental particulate matter (PM) is defined as the microscopic solid or liquid matter suspended in atmospheric aerodynamic. PM2.5 refers to particulates less than 2.5 microns, also known as inhalable lung particles that causes negative impact on human health and atmospheric environmental quality. PM2.5 pollution in China has led to wide concern from all over the world. According to Chinese Environmental Monitoring Report, there was three large-scale regional haze pollution breaking out, including heavy pollution for 155 days and serious pollution for 31 days in 161 cities only from October 1 to October 24 in 2016. The epidemiological results have demonstrated that long-term exposure to PM2.5 promoted the increase of lung cancer incidence and played significant role in the rising of population mortality rate [1–4]. In addition, PM2.5 exposure was also proved to be a risk factor for cardiovascular disease , affecting vascular endothelial dysfunction , mediating vasodilation, accelerating the progression of atherosclerotic plaques .
We searched the following database for studies published before June 2017: Cochrane Library, PUBMED, Embase, China National Knowledge Infrastructure, and Wanfang Electronic Database. Our search strategy used a combination of the following keywords for PM2.5: ‘air pollution’, ‘particulate matter’, ‘ambient particulate matter’, ‘PM’, ‘PM2.5’, ‘PM10’, ‘airborne particulate matter’, ‘particulate air pollutants’, ‘black carbon’, ‘BC (black carbon)’, as well as the following keywords for neovascularization: ‘neovascularization’, ‘Angiogenesis, Pathologic’, ‘Vascular Endothelial Growth Factor A’, ‘Vascular development’, ‘Vascular Endothelial Growth Factor Receptor-1’, ‘Vascular Remodeling’. Only articles written in English or Chinese are included.
In the present meta-analysis, we collected six eligible studies that quantitatively evaluated the relationship between PM2.5 concentration and VEGF expression, and a total of 527 subjects were included. Our results confirmed the positive association between PM2.5 exposure and VEGF level. In studies conducted in Canada, the effects of PM2.5 exposure on VEGF were statistically significant. The level of VEGF measured both in blood and urine showed that PM2.5 exposure was positive associated with VEGF elevation. We conducted a series of subgroup analyses, and the results showed that the measurement method of the exposure and the country the study was conducted likely contributed to the heterogeneity. The number of related studies was limited. Thus, it is necessary to make further meta-analysis to explore the origin of heterogeneity, and more original studies will be included in the future.
In conclusion, this meta-analysis revealed a positive correlation between PM2.5 exposure and VEGF level. Exposure assessment methods and study countries were the major sources of heterogeneity among studies. These results extended our understanding of the adverse effects of exposure to PM2.5 that caused angiogenesis and vascular remodeling by increasing the levels of VEGF. More research are needed in the future to assess the adverse effects of PM 2.5 exposures on VEGF in countries other than Canada, particularly in developing countries.