Air Pollution, Autophagy, and Skin Aging: Impact of Particulate Matter (PM10) on Human Dermal Fibroblasts

Abstract

A World Health Organization (WHO) report from 2016 states that over 3 million people die annually from air pollution, which places air pollution as the world’s largest single environmental health risk factor. Particulate matter (PM) is one of the main components of air pollution, and there is increasing evidence that PM exposure exerts negative effects on the human skin. To see the impact of air pollution on skin aging, we analyzed the effect of PM exposure on human dermal fibroblasts (HDFs) with Western blot, enzyme-linked immunosorbent assay (ELISA), and gene analysis. Cultured HDFs were exposed to PM10 at a concentration of 30 µg/cm2 for 24 h, and their gene/protein expression of inflammatory cytokines, fibroblast chemical mediators, and autophagy were assessed. A total of 1977 genes were found to be differentially expressed following PM exposure. We observed a significantly increased expression of pro-inflammatory genes interleukin (IL)-1β, IL-6, IL-8 and IL-33 in dermal fibroblasts exposed to PM10. Protein expression of IL-6 and IL-8 also significantly increased, which complemented our gene analysis results. In addition, there was a significant increase in cytochrome P450 (CYP1A1, CYP1B1), matrix metalloproteinase (MMP-1, MMP-3) mRNA expression, and significant decrease in transforming growth factor (TGF)-β, collagen type I alpha chain (COL1A1, COL1A2), and elastin (ELN) mRNA expression in PM-exposed dermal fibroblasts. Protein expression of MMP-1 was significantly increased and that of TGF-β and procollagen profoundly decreased, similar to the gene analysis results. Autophagy, an integrated cellular stress response, was also increased while transmission electron microscopy (TEM) analysis provided evidence of PM internalization in the autolysosomes. Taken together, our results demonstrate that PM10 contributes to skin inflammation and skin aging via impaired collagen synthesis. Increased autophagy in our study suggests a reparative role of autophagy in HDFs stressed with PM, but its biological significance requires further research.

Skin Aging Estimation Scheme Based on Lifestyle and Dermoscopy Image Analysis

“…Skin aging is a gradual process represented by the characteristic change in skin and one of the most obvious symptoms of human aging [12][13][14][15][16][17][18][19]. There have been many studies to clarify the relationship between progression of skin aging and skin texture change.…”

“…Park et al analyzed the effect of particulate matter (PM) on skin aging. They demonstrated that PM contributes to skin inflammation and skin aging [19].…”

Urbanization, Environmental Pollution and Skin Aging

“…Fuks et al, 2019 says shortterm exposure to ozone (O3) elicits an oxidative stress response in human, which leads to aberrant transcriptional expression of genes consistent with increased skin aging [17]. Park et al, 2018 demonstrated that PM10 contributes to skin inflammation and skin aging via impaired collagen synthesis [18]. Also, PM negatively affect the human skin and exacerbates preexisting skin disease [19,20].…”

“…Also, PM negatively affect the human skin and exacerbates preexisting skin disease [19,20]. PM penetrates skin through hair follicles or sweat ducts, and across the stratum corneum (intracellularly or transcellularly) [18]. Also, Mohiuddin, 2019 reviewed that increased levels of 4 -hydroxy -2-nonenal (HNE) in the skin, in response to pollutants, likely accelerates skin aging and exacerbates existing skin inflammatory conditions [21].…”

“…Smoker's face typically has lines or wrinkles radiating at the right angles from the upper and lower lips or corners of the eyes, deep lines on the cheeks, or numerous shallow lines on the cheeks and lower jaw [40]. An indirect link between indoor air pollution and skin aging was established by a study showing that the use of fossil fuels for cooking was associated with skin aging [18,51,52]. At the end, some of these environmental exposures are preventable by protecting the skin against sun exposure or by quitting smoking, but there are other environmental exposures like air pollution where up to now no protection is available.…”