PM2.5 induces apoptosis, oxidative stress injury and melanin metabolic disorder in human melanocytes

PM2.5 Exposure Aggravates Inflammatory Response and Mucus Production in 16HBE Cells through Inducing Oxidative Stress and RAGE Expression

Particulate matter 2.5 (PM2.5)-induced oxidative stress has been extensively proposed as a pivotal event in lung diseases. Receptor for advanced glycation end-products (RAGE) is a receptor of pro-inflammatory ligands that has been supported to be implied in the progression of multiple lung diseases. This study attempts to delineate the specific effects of PM2.5 on human bronchial epithelial 16HBE cells in vitro and figure out whether PM2.5 functions via mediating oxidative stress and RAGE. In PM2.5-challenged 16HBE cells, MTT assay detected cell viability. ELISA estimated inflammatory levels. Flow cytometry analysis measured ROS activity and related assay kits examined oxidative stress levels. Western blot tested nuclear factor E2-related factor 2 (Nrf2), RAGE, β-catenin, and mucin 5AC (MUC5AC) expression. Immunofluorescence staining evaluated nuclear translocation of β-catenin. It was noticed that PM2.5 exposure exacerbated inflammatory response, oxidative stress, and mucus production. Additionally, PM2.5 elevated RAGE expression while declined Nrf2 expression as well as stimulated the nuclear translocation of β-catenin. Furthermore, RAGE inhibition or nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor VAS2870 mitigated inflammatory response, oxidative stress, and mucus generation in PM2.5-exposed 16HBE cells. In addition, RAGE inhibition or VAS2870 raised Nrf2 expression, reduced RAGE expression, and hampered β-catenin nuclear translocation. Briefly, PM2.5 might act as a leading driver of inflammatory response and mucus production in lung injury, the mechanism of which might be related to the activation of oxidative stress and the up-regulation of RAGE.

The inhibitory effect of chlorogenic acid on oxidative stress and apoptosis induced by PM2.5 in HaCaT keratinocytes

Exposure to fine particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5) can cause oxidative damage and apoptosis in the human skin. Chlorogenic acid (CGA) is a bioactive polyphenolic compound with antioxidant, antifungal, and antiviral properties. The objective of this study was to identify the ameliorating impact of CGA that might protect human HaCaT cells against PM2.5. CGA significantly scavenged the reactive oxygen species (ROS) generated by PM2.5, attenuated oxidative cellular/organelle damage, mitochondrial membrane depolarization, and suppressed cytochrome c release into the cytosol. The application of CGA led to a reduction in the expression levels of Bcl-2-associated X protein, caspase-9, and caspase-3, while simultaneously increasing the expression of B-cell lymphoma 2. In addition, CGA was able to reverse the decrease in cell viability caused by PM2.5 via the inhibition of extracellular signal-regulated kinase (ERK). This effect was further confirmed by the use of the mitogen-activated protein kinase kinase inhibitor, which acted upstream of ERK. In conclusion, CGA protected keratinocytes from mitochondrial damage and apoptosis via ameliorating PM2.5-induced oxidative stress and ERK activation.

Causal association between air pollution and autoimmune diseases: a two-sample Mendelian randomization study

Background

In recent years, an increasing number of observational studies have reported the impact of air pollution on autoimmune diseases (ADs). However, no Mendelian randomization (MR) studies have been conducted to investigate the causal relationships. To enhance our understanding of causality, we examined the causal relationships between particulate matter (PM) and nitrogen oxides (NOx) and ADs.

Methods

We utilized genome-wide association study (GWAS) data on PM and NOx from the UK Biobank in European and East Asian populations. We also extracted integrated GWAS data from the Finnish consortium and the Japanese Biobank for two-sample MR analysis. We employed inverse variance weighted (IVW) analysis to assess the causal relationship between PM and NOx exposure and ADs. Additionally, we conducted supplementary analyses using four methods, including IVW (fixed effects), weighted median, weighted mode, and simple mode, to further investigate this relationship.

Results

In the European population, the results of MR analysis suggested a statistically significant association between PM2.5 and psoriasis only (OR = 3.86; 95% CI: 1.89-7.88; PIVW < 0.00625), while a potential association exists between PM2.5-10 and vitiligo (OR = 7.42; 95% CI: 1.02-53.94; PIVW < 0.05), as well as between PM2.5 and systemic lupus erythematosus (OR = 68.17; 95% CI: 2.17-2.1e+03; PIVW < 0.05). In East Asian populations, no causal relationship was found between air pollutants and the risk of systemic lupus erythematosus and rheumatoid arthritis (PIVW > 0.025). There was no pleiotropy in the results.

Conclusion

Our results suggest a causal association between PM2.5 and psoriasis in European populations. With the help of air pollution prevention and control, the harmful progression of psoriasis may be slowed.

Promoting New Approach Methodologies (NAMs) for research on skin color changes in response to environmental stress factors: tobacco and air pollution

Aging is one of the most dynamic biological processes in the human body and is known to carry significant impacts on individuals' self-esteem. Skin pigmentation is a highly heritable trait made possible by complex, strictly controlled cellular and molecular mechanisms. Genetic, environmental and endocrine factors contribute to the modulation of melanin's amount, type and distribution in the skin layers. One of the hallmarks of extrinsic skin aging induced by environmental stress factors is the alteration of the constitutive pigmentation pattern clinically defined as senile lentigines and/or melasma or other pigmentary dyschromias. The complexity of pollutants and tobacco smoke as environmental stress factors warrants a thorough understanding of the mechanisms by which they impact skin pigmentation through repeated and long-term exposure. Pre-clinical and clinical studies demonstrated that pollutants are known to induce reactive oxygen species (ROS) or inflammatory events that lead directly or indirectly to skin hyperpigmentation. Another mechanistic direction is provided by Aryl hydrocarbon Receptors (AhR) which were shown to mediate processes leading to skin hyperpigmentation in response to pollutants by regulation of melanogenic enzymes and transcription factors involved in melanin biosynthesis pathway. In this context, we will discuss a diverse range of New Approach Methodologies (NAMs) capable to provide mechanistic insights of the cellular and molecular pathways involved in the action of environmental stress factors on skin pigmentation and to support the design of raw ingredients and formulations intended to counter their impact and of any subsequently needed clinical studies.

A cross-sectional study of Chinese women facial skin status with environmental factors and individual lifestyles

Geographical, environmental and pollution conditions affect facial skin health, but their effects on skin appearance have not been elucidated. This study aimed to describe the skin barrier and skin tone characteristics of Chinese subjects according to lifestyle and environmental conditions using in vitro measurements. In total, 1092 women aged 22-42 years were recruited from 7 representative Chinese cities. Eight skin parameters (hydration, sebum, pH, transdermal water loss, individual type angle, melanin index, erythema index, yellowness) were measured using noninvasive instruments; individual lifestyle data were also collected. Data on four meteorological factors (air temperature, relative humidity, sunshine duration, wind speed) and seven air pollution indicators (air quality index, fine particulate matter, breathable particulate matter, sulfur dioxide, nitrogen dioxide, carbon monoxide and ozone) were collected in each city from the China Meteorological Administration. Facial skin characteristics differed significantly between cities. Facial skin barrier characteristics and skin tones showed regional differences, with a better skin barrier associated with the western region, as indicated by high skin hydration and sebum secretion and a low pH value. According to the value of transdermal water loss, lighter and darker skin tones were found in the western and southern regions, respectively. Environmental conditions affected facial skin status. Air pollution induced facial skin issues, with fine particulate matter and nitrogen dioxide contributing the most. Individual lifestyles affected the facial skin barrier and skin tone.

Sesamin Ameliorates Fine Particulate Matter (PM2.5)-Induced Lung Injury via Suppression of Apoptosis and Autophagy in Rats

Lung damage can be caused by fine particulate matter (PM_2.5). Thus, effective prevention strategies for PM_2.5-induced lung injury are urgently required. Sesamin (Ses) is a natural polyphenolic compound that has attracted considerable attention of researchers because of its wide range of pharmacological activities. The present study aims to elucidate whether Ses pretreatment could alleviate PM_2.5-induced lung damage and identify its possible mechanisms. Sprague-Dawley rats were orally dosed with 0.5% carboxymethylcellulose (CMC) and different concentrations of Ses once a day for 21 days. Then, the rats of the PM_2.5 exposure group and Ses-treated group were exposed to PM_2.5 by intratracheal instillation every 2 days for 1 week. Biomarkers associated with lung injury were detected in bronchoalveolar lavage fluid (BALF). Lung tissue was collected for histology, inflammation, oxidative stress, immunohistochemistry, and Western blot. Our results showed that PM_2.5 exposure could cause pathological changes in lung tissue and increase levels of TP, AKP, and ALB in BALF. Meanwhile, exposure to PM_2.5 can cause oxidative stress and inflammation in the lungs. In addition, Ses pretreatment could ameliorate histopathological injury, oxidative stress, and inflammation caused by PM_2.5 exposure. It could also inhibit PM_2.5-induced apoptosis and upregulation of autophagy-associated proteins. Collectively, our study indicated that Ses pretreatment could ameliorate PM_2.5-induced lung damage via inhibiting apoptosis and autophagy in rats.

Effects of Air Pollution on Cellular Senescence and Skin Aging

The human skin is exposed daily to different environmental factors such as air pollutants and ultraviolet (UV) light. Air pollution is considered a harmful environmental risk to human skin and is known to promote aging and inflammation of this tissue, leading to the onset of skin disorders and to the appearance of wrinkles and pigmentation issues. Besides this, components of air pollution can interact synergistically with ultraviolet light and increase the impact of damage to the skin. However, little is known about the modulation of air pollution on cellular senescence in skin cells and how this can contribute to skin aging. In this review, we are summarizing the current state of knowledge about air pollution components, their involvement in the processes of cellular senescence and skin aging, as well as the current therapeutic and cosmetic interventions proposed to prevent or mitigate the effects of air pollution in the skin.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

The Role of Oxidative Stress in the Pathogenesis of Vitiligo: A Culprit for Melanocyte Death

Vitiligo is a common chronic acquired pigmentation disorder characterized by loss of pigmentation. Among various hypotheses proposed for the pathogenesis of vitiligo, oxidative stress-induced immune response that ultimately leads to melanocyte death remains most widely accepted. Oxidative stress which causes elevated levels of reactive oxygen species (ROS) can lead to dysfunction of molecules and organelles, triggering further immune response, and ultimately melanocyte death. In recent years, a variety of cell death modes have been studied, including apoptosis, autophagy and autophagic cell death, ferroptosis, and other novel modes of death, which will be discussed in this review in detail. Oxidative stress is also strongly linked to these modes of death. Under oxidative stress, ROS could induce autophagy by activating the Nrf2 antioxidant pathway of melanocytes. However, persistent stimulation of ROS might eventually lead to excessive activation of Nrf2 antioxidant pathway, which in turn will inactivate autophagy. Moreover, ferroptosis may be triggered by oxidative-related transcriptional production, including ARE, the positive feedback loop related to p62, and the reduced activity and expression of GPX4. Therefore, it is reasonable to infer that these modes of death are involved in the oxidative stress response, and that oxidative stress also acts as an initiator for various modes of death through some complex mechanisms. In this study, we aim to summarize the role of oxidative stress in vitiligo and discuss the corresponding mechanisms of interaction between various modes of cell death and oxidative stress. These findings may provide new ideas for exploring the pathogenesis and potential therapeutic targets of vitiligo.

Bioprocess of Microbial Melanin Production and Isolation

Melanin is one of the most abundant pigments found in the biosphere. Owing to its high biocompatibility and diverse biological activities, it has been widely applied as a functional biomaterial in the cosmetic, pharmaceutical, biopolymer, and environmental fields. In this study, the production of melanin was comprehensively reviewed concerning bioconversion and isolation processes. First, several melanogenic microbes, including fungi and bacteria, were summarized. Melanin production was classified by host and melanin type and was analyzed by titers in g/L in addition to reaction conditions, including pH and temperature. The production was further interpreted using a space-time yields chart, which showed two distinct classifications in productivity, and reaction conditions were analyzed using a pH-temperature-titer chart. Next, the extraction process was summarized by crude and pure melanin preparation procedures, and the extraction yields were highlighted. Finally, the recent applications of melanin were briefly summarized, and prospects for further application and development in industrial applications were suggested.

Arbutin as a Skin Depigmenting Agent with Antimelanogenic and Antioxidant Properties

Arbutin is a compound of hydroquinone and D-glucose, and it has been over 30 years since there have been serious studies on the skin lightening action of this substance. In the meantime, there have been debates and validation studies about the mechanism of action of this substance as well as its skin lightening efficacy and safety. Several analogs or derivatives of arbutin have been developed and studied for their melanin synthesis inhibitory action. Formulations have been developed to improve the stability, transdermal delivery, and release of arbutin, and device usage to promote skin absorption has been developed. Substances that inhibit melanin synthesis synergistically with arbutin have been explored. The skin lightening efficacy of arbutin alone or in combination with other active ingredients has been clinically evaluated. Combined therapy with arbutin and laser could give enhanced depigmenting efficacy. The use of arbutin causes dermatitis rarely, and caution is recommended for the use of arbutin-containing products, especially from the viewpoint that hydroquinone may be generated during product use. Studies on the antioxidant properties of arbutin are emerging, and these antioxidant properties are proposed to contribute to the skin depigmenting action of arbutin. It is hoped that this review will help to understand the pros and cons of arbutin as a cosmetic ingredient, and will lead to future research directions for developing advanced skin lightening and protecting cosmetic products.

Curcumin protects BEAS‑2B cells from PM2.5‑induced oxidative stress and inflammation by activating NRF2/antioxidant response element pathways

Fine particulate matter (PM_2.5) with an average aerodynamic diameter of &lt;2.5 µm can cause severe lung injury. Oxidative stress and inflammation are considered the main outcomes of PM_2.5 exposure. Curcumin is a well‑known antioxidant; however, its effect on PM_2.5‑induced oxidative injury in airway epithelial cells remains unclear. In the present study, it was demonstrated that pre‑treatment with curcumin significantly reduced the PM_2.5‑induced apoptosis of BEAS‑2B human bronchial epithelial cells by decreasing the level of intercellular reactive oxygen species. Western blot analysis revealed that curcumin increased the expression of nuclear factor erythroid 2‑related factor 2 (NRF2) and regulated the transcription of downstream genes, particularly those encoding antioxidant enzymes. Moreover, curcumin reduced the PM_2.5‑induced expression and production of inflammatory factors, and induced the expression of the anti‑inflammatory factors, interleukin (IL)‑5 and IL‑13. Taken together, the present study demonstrates that curcumin protects BEAS‑2B cells against PM_2.5‑induced oxidative damage and inflammation, and prevents cell apoptosis by increasing the activation of NRF2‑related pathways. It is thus suggested that curcumin may be a potential compound for use in the prevention of PM_2.5‑induced tissue injury.

Autophagy attenuates particulate matter 2.5-induced damage in HaCaT cells

Background

Keratinocyte is a key component of the skin barrier and maintains skin homeostasis. As an environmental pathogenic factor, PM2.5 can cause epidermal cell damage, but the mechanism remains to be elucidated. The present study aimed to evaluate the effect caused by PM2.5 in HaCaT cells and investigate the underlying mechanisms.

Methods

HaCaT cells were treated with PM2.5 for 12 h or 24 h, either alone or combined with UVB irradiation. A Cell Counting Kit (CCK-8) assay was carried out to detect the effect of PM2.5 on HaCaT cell viability. Flow cytometry, Western Blot, and AO staining were employed to detect the changes of apoptosis and autophagy. The changes of cytotoxicity and apoptosis in HaCaT cells were analyzed by CCK-8 and flow cytometry after pretreatment with autophagy inhibitor 3-MA.

Results

The results showed that PM2.5 induced cytotoxicity by increasing cell apoptosis and activating autophagy. Apoptosis was determined to be increased significantly after autophagy inhibition. Moreover, solar radiation intensified PM2.5-induced damage in HaCaT cells, which further enhanced the autophagy. However, there was no significant difference in apoptosis after inhibition of autophagy in combined treatment.

Conclusions

Our data reveals that PM2.5 induces damage in HaCaT cells, and autophagy plays a protective role to promote cell survival.

Effects of DNA Damage and Oxidative Stress in Human Bronchial Epithelial Cells Exposed to PM2.5 from Beijing, China, in Winter

Epidemiological studies have corroborated that respiratory diseases, including lung cancer, are related to fine particulate matter (<2.5 μm) (PM_2.5) exposure. The toxic responses of PM_2.5 are greatly influenced by the source of PM_2.5. However, the effects of PM_2.5 from Beijing on bronchial genotoxicity are scarce. In the present study, PM_2.5 from Beijing was sampled and applied in vitro to investigate its genotoxicity and the mechanisms behind it. Human bronchial epithelial cells 16HBE were used as a model for exposure. Low (67.5 μg/mL), medium (116.9 μg/mL), and high (202.5 μg/mL) doses of PM_2.5 were used for cell exposure. After PM_2.5 exposure, cell viability, oxidative stress markers, DNA (deoxyribonucleic acid) strand breaks, 8-OH-dG levels, micronuclei formation, and DNA repair gene expression were measured. The results showed that PM_2.5 significantly induced cytotoxicity in 16HBE. Moreover, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and cellular heme oxygenase (HO-1) were increased, and the level of glutathione (GSH) was decreased, which represented the occurrence of severe oxidative stress in 16HBE. The micronucleus rate was elevated, and DNA damage occurred as indicators of the comet assay, γ-H2AX and 8-OH-dG, were markedly enhanced by PM_2.5, accompanied by the influence of 8-oxoguanine DNA glycosylase (OGG1), X-ray repair cross-complementing gene 1 (XRCC1), and poly (ADP-ribose) polymerase-1 (PARP1) expression. These results support the significant role of PM_2.5 genotoxicity in 16HBE cells, which may occur through the combined effect on oxidative stress and the influence of DNA repair genes.