Effects of Particulate Matter on Healthy Skin: A Comparative Study between High- and Low-Particulate Matter Periods

Systematic establishment of the relationship between skin absorption and toxicity of furanoids via in silico, in vitro, and in vivo assessments

Furanoids are a class of contaminants prevalent in both airborne and occupational environments, with potential health implications through inhalation, oral ingestion, and skin penetration. Given their diminutive molecular size, there is a presumption that furanoids can readily permeate the skin. To systematically explore this presumption, we investigated the skin absorption and toxicity of a series of furans (furfuryl alcohol, furfuryl acetate, furfural, methyl 2-furoate, and 5-methylfurfural) using in silico, in vitro, and in vivo models. The in vitro permeation test (IVPT) from neat and aqueous suspension (5 mM) of furans demonstrated a facile absorption through pig and nude mouse skins. The lipophilicity of furans significantly influenced skin deposition, with higher lipophilicity displaying greater deposition. However, an opposing trend emerged in the receptor compartment accumulation. In barrier-defective skin simulating atopic dermatitis (AD) and psoriasis, enhanced deposition occurred with more hydrophilic furans but not with the more lipophilic ones. In the cell-based study, furanoids induced the proliferation of keratinocytes and skin fibroblasts except for the compounds with the aldehyde group (furfural and 5-methylfurfural). Both furfuryl acetate and 5-methylfurfural activated keratinocytes via the overexpression of COX-2 and PGE2 by 1.5‒2-fold. This stimulation involved the mitogen-activated protein kinase (MAPK) signaling pathway. For the in vivo mouse skin treatment, we selected furfuryl acetate (hydrophilic) and 5-methylfurfural (lipophilic). Both furans showed different patterns of skin lesions, where repeated application of furfuryl acetate caused epidermal hyperplasia and scaling, while 5-methylfurfural predominantly evoked skin inflammation and barrier disintegration. Toxicokinetics analysis revealed a higher plasma concentration of topically applied furfuryl acetate than that of the 5-methylfurfural (5.04 versus 2.34 nmol/ml), resulting in the mild injury of furfuryl acetate-treated peripheral organs. Conversely, no notable adverse effects on organs were observed for the 5-methylfurfural. This study established the relationship between cutaneous absorption and the toxicity of furans following skin exposure.

The influence of air pollution on skin microbiome: a link to skin barrier dysfunction

An equilibrium of skin microbiome is crucial for maintaining skin barrier function. However, external factors such as air pollution have the potential to disrupt this equilibrium. Hence, further investigation into the influence of air pollution on the skin microbiome emerges as a critical imperative. Healthy women matched for age from two different ambient air cities in Thailand: Bangkok, characterized by highly polluted air (HPA) (n = 33), and Songkhla, characterized by less polluted air (LPA) (n = 33) were recruited. Skin barrier physiological parameters were measured on the forehead skin. Microbiome samples were collected via the scraping and swabbing technique from the forehead skin and analyzed for microbiome profiles using amplicon sequencing. We found that the abundant microbiome at the phylum level was comparable between HPA- and LPA-exposed skin. However, microbiome diversity was decreased at genus level of fungus and species level of bacteria on HPA-exposed skin. Interestingly, some relatively higher enriched microbiome correlated with skin barrier physiological parameters. Specifically, a higher enrichment of Streptococcus parasanguinis on LPA-exposed skin correlated with both lower skin pH and higher stratum corneum (SC) hydration. Conversely, a higher enrichment of Malassezia spp. and Aureobasidum spp. on HPA-exposed skin was correlated with increased transepidermal water loss and decreased SC hydration, respectively. In conclusion, air pollution potentially affects the skin microbiome by reducing its diversity, disrupting its beneficial correlations with barrier physiology, and promoting the overgrowth of pathogenic microbiome, resulting in decreased hydration and increased pH levels. These factors could ultimately lead to skin barrier dysfunction.

Non-linear association between air pollutants and secondary sensitive skin in acne patients

BACKGROUND

There is a growing number of patients suffering from sensitive skin secondary to acne, but its prevalence and influencing factors are not yet well-understood.

OBJECTIVE

The aim of this study is to investigate the nonlinear relationship between air pollutants and secondary sensitive skin in acne patients.

METHODS

A cross-sectional study comprising 4325 acne outpatients in China was carried out between September 2021 and December 2022, employing a simple random sampling approach. Air pollutants data was derived from the nearest air quality monitoring station corresponding to the subjects' residential locations. Furthermore, socio-economic characteristics, biological attributes, and lifestyle data of patients were acquired via questionnaire surveys. The data were subsequently analyzed utilizing the XGBoost machine learning model.

RESULTS

A nonlinear relationship has been observed between secondary sensitive skin in acne patients and various factors, including particulate matter (PM2.5), inhalable particulate matter (PM10), ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), the severity of depression, different levels of exercise intensity, acne grading, frequency of sunscreen application, gender, and age.

CONCLUSION

The occurrence of secondary sensitive skin in acne patients be mitigated through the implementation of measures such as the control of air pollutant emissions, regulation of negative emotions, and improvement of personal lifestyle.

Particulate matter and inflammatory skin diseases: From epidemiological and mechanistic studies

Epidemiological and toxicological studies have confirmed that exposure to atmospheric particulate matter (PM) could affect our cardiovascular and respiratory systems. Recent studies have shown that PM can penetrate the skin and cause skin inflammation, but the evidence is limited and contradictory. As the largest outermost surface of the human body, the skin is constantly exposed to the environment. The aim of this study was to assess the relationship between PM and inflammatory skin diseases. Most epidemiological studies have provided positive evidence for outdoor, indoor, and wildfire PM and inflammatory skin diseases. The effects of PM exposure during pregnancy and inflammatory skin diseases in offspring are heterogeneous. Skin barrier dysfunction, Oxidative stress, and inflammation may play a critical role in the underlying mechanisms. Finally, we summarize some interventions to alleviate PM-induced inflammatory skin diseases, which may contribute to public health welfare. Overall, PM is related to inflammatory skin diseases via skin barrier dysfunction, oxidative stress, and inflammation. Appropriate government interventions are beneficial.

Modulation of the Cardiovascular Effects of Polycyclic Aromatic Hydrocarbons: Physical Exercise as a Protective Strategy

Exposure to polycyclic aromatic hydrocarbons (PAHs) present in air pollution increases cardiovascular risk. On the contrary, physical exercise is a widely used therapeutic approach to mitigate cardiovascular risk, but its efficacy in an environment of air pollution, particularly with PAHs, remains unclear. This study investigates the effects of exercise on inflammation, endothelial dysfunction, and REDOX imbalance due to PAH exposure using a mouse model. Twenty male BALB/c mice were subjected to a mixture of PAHs (phenanthrene, fluoranthene, pyrene) in conjunction with aerobic exercise. The investigation evaluated serum levels of inflammatory cytokines, gene expression linked to inflammatory markers, endothelial dysfunction, and REDOX imbalance in aortic tissues. Furthermore, the study evaluated the expression of the ICAM-1 and VCAM-1 proteins. Exercise led to notable changes in serum inflammatory cytokines, as well as the modulation of genes associated with endothelial dysfunction and REDOX imbalance in aortic tissue. In turn, exercise produced a modulation in the protein expression of ICAM-1 and VCAM-1. The findings implicate the potential of exercise to counter PAH-induced damage, as demonstrated by changes in markers. In conclusion, exercise could mitigate the adverse effects related to exposure to PAHs present in air pollution, as evidenced by changes in inflammatory markers, endothelial dysfunction, and REDOX imbalance.

Topical Iron Chelator Therapy: Current Status and Future Prospects

Systemic iron chelation therapy has long been used for iron overload, providing a role in returning iron levels to proper homeostatic concentrations. Recently, topical iron chelation therapy has emerged as a potential strategy for treating skin damage. This narrative review explores the current status and future prospects of topical iron chelation therapy for treating ultraviolet (UV) and non-UV skin damage, as well as its potential application in wound healing. The review was conducted through a literature search across PubMed, Web of Science, and EMBASE databases, spanning publications from 1990 to 2023. The selection of articles was focused on primary research studies, either experimental or clinical, that explored the implications and formulations of topical iron chelators used alone or in conjunction with another therapeutic agent. The search strategy employed a combination of terms, including "topical iron chelation", "topical deferoxamine", "UV", "wound healing", "skin inflammation", "radiation-induced fibrosis", and "skin cancer". Relevant studies, including methods, intervention strategies, measured outcomes, and findings, are summarized. The review also considered the potential challenges in translating research findings into clinical practice. Results indicate that topical iron chelators, such as deferoxamine, are effective in mitigating UV-induced skin damage, reducing tumorigenesis, and decreasing oxidative damage. In addition, the use of these agents in radiation-induced fibrosis has been shown to significantly increase skin elasticity and reduce dermal fibrosis. Several studies also highlight the use of topical iron chelators in difficult-to-treat chronic wounds, such as diabetic neuropathic ulcers and sickle cell ulcers. In conclusion, topical iron chelation therapy represents a novel and promising approach for skin protection and wound healing. Its potential makes it a promising area of future research.

Impact of Air Pollution on Atopic Dermatitis: A Comprehensive Review

Air pollution is associated with multiple health problems worldwide, contributing to increased morbidity and mortality. Atopic dermatitis (AD) is a common allergic disease, and increasing evidence has revealed a role of air pollution in the development of atopic dermatitis. Air pollutants are derived from several sources, including harmful gases such as nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO), as well as particulate matter (PM) of various sizes, and bioaerosols. Possible mechanisms linking air pollution to atopic dermatitis include damage to the skin barrier through oxidative stress, increased water loss, physicochemical injury, and an effect on skin microflora. Furthermore, oxidative stress triggers immune dysregulation, leading to enhanced sensitization to allergens. There have been multiple studies focusing on the association between various types of air pollutants and atopic dermatitis. Since there are many confounders in the current research, such as climate, synergistic effects of mixed pollutants, and diversity of study population, it is not surprising that inconsistencies exist between different studies regarding AD and air pollution. Still, it is generally accepted that air pollution is a risk factor for AD. Future studies should focus on how air pollution leads to AD as well as effective intervention measures.

Air Pollution and Atopic Dermatitis, from Molecular Mechanisms to Population-Level Evidence: A Review

Atopic dermatitis (AD) has increased in prevalence to become the most common inflammatory skin condition globally, and geographic variation and migration studies suggest an important role for environmental triggers. Air pollution, especially due to industrialization and wildfires, may contribute to the development and exacerbation of AD. We provide a comprehensive, multidisciplinary review of existing molecular and epidemiologic studies on the associations of air pollutants and AD symptoms, prevalence, incidence, severity, and clinic visits. Cell and animal studies demonstrated that air pollutants contribute to AD symptoms and disease by activating the aryl hydrocarbon receptor pathway, promoting oxidative stress, initiating a proinflammatory response, and disrupting the skin barrier function. Epidemiologic studies overall report that air pollution is associated with AD among both children and adults, though the results are not consistent among cross-sectional studies. Studies on healthcare use for AD found positive correlations between medical visits for AD and air pollutants. As the air quality worsens in many areas globally, it is important to recognize how this can increase the risk for AD, to be aware of the increased demand for AD-related medical care, and to understand how to counsel patients regarding their skin health. Further research is needed to develop treatments that prevent or mitigate air pollution-related AD symptoms.

Preventative Effects of Antioxidants against PM10 on Serum IgE Concentration, Mast Cell Counts, Inflammatory Cytokines, and Keratinocyte Differentiation Markers in DNCB-Induced Atopic Dermatitis Mouse Model

Particulate matter (PM) can cause oxidative stress, inflammation, and skin aging. We investigated the effects of antioxidants such as dieckol, punicalagin, epigallocatechin gallate (EGCG), resveratrol, and Siegesbeckiae Herba extract (SHE) against PM < 10 μm (PM10) on serum IgE concentration, mast cell counts, inflammatory cytokines, and keratinocyte differentiation markers in a 2,4-Dinitrochlorobenzene (DNCB)-induced atopic dermatitis mouse model. Seven-week-old BALB/c mice were sensitized with 2% DNCB. Atopic dermatitis-like lesions were induced on the mice with 0.2% DNCB. Antioxidants and PM10 were applied to the mice for 4 weeks. PM10 increased the serum IgE concentration and spleen weight in mice, and all antioxidants downregulated these parameters. Histological examination showed an increase in epidermal thickness and mast cell counts in response to PM10, and all antioxidants showed a decrease. PM10 upregulates the expression of inflammatory cytokines, including interleukin (IL)-1β, IL-4, IL-6, IL-17α, IL-25, IL-31 and thymic stromal lymphopoietin (TSLP) in mice, and all antioxidants inhibited the upregulation of inflammatory cytokines. ELISA showed the same results as real-time PCR. PM10 downregulates the expression of keratinocyte differentiation markers, including loricrin and filaggrin, in mouse keratinocytes and antioxidants prevented the downregulation of the keratinocyte differentiation markers. Conclusively, PM10 aggravated the DNCB-induced mouse model in serum IgE concentration, mast cell counts, inflammatory cytokine, and keratinocyte differentiation markers. In addition, antioxidants modulated changes in the DNCB-induced mouse model caused by PM10.

Effects of <10-µm Particulate Matter on Cultured Human Sebocytes and Outer Root Sheath Cells and Usefulness of Siegesbeckia Herba Extract

Background

Particulate matter (PM) is one of the air pollutants that can damage human skin; the recent increase in the amount of PM may be detrimental to skin health.

Objective

We aimed to investigate the effects of PM on cultured human sebocytes and outer root sheath (ORS) cells and the effects of Siegesbeckia Herba extract (SHE) on PM-treated cultured cells.

Methods

Sebocytes and ORS cells were cultured. The cultured cells were treated with various concentrations of PM of <10 µm in size (PM10) (10 µg/ml, 25 µg/ml, 50 µg/ml, and 100 µg/ml) for 24 h. Real-time polymerase chain reaction, measurement of reactive oxygen species (ROS), small interfering (si) RNA transfection, Oil Red O and Nile red staining, and immunofluorescence staining were performed to analyze the presence of inflammatory cytokines, matrix metalloproteinases (MMPs), aryl hydrocarbon receptor (AhR), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), ROS, and lipid production. In addition, PM10 (100 µg/ml)-treated cultured cells were treated with 10 mg/ml of SHE.

Results

PM10 upregulates the expression of inflammatory cytokines, MMPs, AhR, NF-κB, and ROS in cultured human sebocytes and ORS cells. The production of ROS was dramatically reduced in AhR siRNA-transfected cells. In addition, PM10 upregulates sebum production in cultured sebocytes. SHE inhibited the upregulation of inflammatory cytokines, MMPs, AhR, NF-κB, ROS, and sebum production in cultured human sebocytes and/or ORS cells by PM10.

Conclusion

Effects of PM10 on cultured human sebocytes and ORS cells can be regulated by SH.

Transepidermal water loss (TEWL): Environment and pollution-A systematic review

Introduction

Transepidermal water loss (TEWL) is an objective measurement of skin integrity measured as the amount of water lost across the stratum corneum. TEWL varies greatly across variables such as age and anatomic location, and disruptions in the skin barrier have been linked to inflammatory dermatoses such as psoriasis and atopic dermatitis. Impact of environmental conditions and pollution on TEWL has yet to be determined. Accordingly, this review summarizes effects of environmental conditions and pollution on TEWL.

Methods

A comprehensive literature search was performed using Embase, PubMed, and Web of Science to find human studies that provided data on environmental conditions and/or pollution and TEWL.

Results

In total, 15 studies were included, with 11 studies examining environmental and seasonal conditions on TEWL and four examining pollution. All studies examining pollution showed increased TEWL in people exposed to particulate matter or NO2. Contradictory results were found on the effects of season and climate across the 11 studies, with no consensus reached.

Conclusion

Exposure to pollution is reported to cause increases in TEWL, likely through free radical damage. Significant discrepancies exist among current literature as to the effects of season and climate on TEWL. There is a need to continue examining environmental variables other than temperature and relative humidity, such as atmospheric and steam pressure, that may impact TEWL.