Effects of Particulate Matter in a Mouse Model of Oxazolone-Induced Atopic Dermatitis

Skin Barrier in Atopic Dermatitis

A compromised permeability barrier is a hallmark of atopic dermatitis (AD). Localized to the outermost skin layer, the stratum corneum (SC) is critically dependent on terminal differentiation of epidermal keratinocytes, which transform into protein-rich corneocytes surrounded by extracellular lamellae of unique epidermal lipids, conferring permeability barrier function. These structures are disrupted in AD. A leaky barrier is prone to environmental insult, which in AD elicits type 2-dominant inflammation, in turn resulting in a vicious cycle further impairing the SC structure. Therapies directed at enforcing SC structure and anti-inflammatory strategies administered by topical and systemic route as well as UV therapy have differential effects on the permeability barrier. The expanding armamentarium of therapeutic modalities for AD treatment warrants optimization of their effects on permeability barrier function.

Adipose tissue-derived exosomes alleviate particulate matter-induced inflammatory response and skin barrier damage in atopic dermatitis-like triple-cell model

Recently, particulate matter (PM) has been shown to exacerbate atopic dermatitis (AD) by inducing an inflammatory response. Meanwhile, several studies revealed that exosomes derived from adipose tissue-derived mesenchymal stem cells promote wound healing and alleviate inflammation via their regenerative and immunomodulatory capacities. Our study aimed to investigate the effects of human adipose tissue-derived mesenchymal stem cell-derived (ASC)-exosomes in PM-induced AD. An AD-like triple-cell model was established by treating human keratinocytes, dermal fibroblasts, and mast cells with polyinosinic:polycytidylic acid (Poly I:C) and interleukin 1 alpha (IL-1α). The effects of PM and ASC-exosomes on the expression of pro-inflammatory cytokines and skin barrier proteins were examined using quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence. PM increased pro-inflammatory cytokines (IL-6, IL-1β, and IL-1α) and decreased the anti-inflammatory cytokine IL-10, while the mRNA expression of skin barrier proteins (loricrin and filaggrin) decreased. However, when the cells were treated with ASC-exosomes, the PM-induced effects on pro-inflammatory cytokines and skin barrier proteins were reversed. Our results confirmed that PM-induced inflammation and skin barrier damage were alleviated by ASC-exosomes in our AD-like triple-cell model. These data suggest that ASC-exosomes can serve as a therapeutic agent for PM-exacerbated AD.

Anti-Inflammatory Artificial Extracellular Vesicles with Notable Inhibition of Particulate Matter-Induced Skin Inflammation and Barrier Function Impairment

Particulate matter (PM) exposure disrupts the skin barrier, causing cutaneous inflammation that may eventually contribute to the development of various skin diseases. Herein, we introduce anti-inflammatory artificial extracellular vesicles (AEVs) fabricated through cell extrusion using the biosurfactant PEGylated mannosylerythritol lipid (P-MEL), hereafter named AEVP-MEL. The P-MEL has anti-inflammatory abilities with demonstrated efficacy in inhibiting the secretion of pro-inflammatory mediators. Mechanistically, AEVP-MEL enhanced anti-inflammatory response by inhibiting the mitogen-activated protein kinase (MAPK) pathway and decreasing the release of inflammatory mediators such as reactive oxygen species (ROS), cyclooxygenase-2 (COX-2), and pro-inflammatory cytokines in human keratinocytes. Moreover, AEVP-MEL promoted increased expression levels of skin barrier proteins (e.g., involucrin, IVL) and water-proteins (e.g., aquaporin 3, AQP3). In vivo studies revealed that repeated PM exposure to intact skin resulted in cutaneous inflammatory responses, including increased skin thickness (hyperkeratosis) and mast cell infiltration. Importantly, our data showed that the AEVP-MEL treatment significantly restored immune homeostasis in the skin affected by PM-induced inflammation and enhanced the intrinsic skin barrier function. This study highlights the potential of the AEVP-MEL in promoting skin health against PM exposure and its promising implications for the prevention and treatment of PM-related skin disorders.

The Potential of Campanula takesimana Callus Extract to Enhance Skin Barrier Function

Atopic dermatitis (AD) is a prevalent inflammatory skin disease characterized by epidermal barrier dysfunction and Th2-skewed inflammation. Campanula takesimana (C. takesimana), a Korean endemic plant grown on Ulleng Island, has long been associated with a traditional alternative medicine for asthma, tonsillitis, and sore throat. In this study, we reported the effect of C. takesimana callus extract on upregulating epidermal barrier-related proteins dysregulated by Th2 cytokines. C. takesimana callus extract induced the expression of skin barrier proteins, such as filaggrin, claudin-1, and zonula occludens-1, in both human primary keratinocytes and Th2-induced AD-like skin-equivalent models. Additionally, RNA sequencing analysis demonstrated that C. takesimana callus extract partially restored Th2 cytokine-induced dysregulation of the epidermal development and lipid metabolic pathways. Considering the advantages of callus as a sustainable eco-friendly source of bioactive substances, and its effect on skin barrier proteins and lipid metabolic pathways, C. takesimana callus extracts can possibly be utilized to improve the integrity of the skin barrier.

Global warming and implications for epithelial barrier disruption and respiratory and dermatologic allergic diseases

Global warming has direct and indirect effects, as well as short- and long-term impacts on the respiratory and skin barriers. Extreme temperature directly affects the airway epithelial barrier by disrupting the structural proteins and by triggering airway inflammation and hyperreactivity. It enhances tidal volume and respiratory rate by affecting the thermoregulatory system, causing specific airway resistance and reflex bronchoconstriction via activation of bronchopulmonary vagal C fibers and upregulation of transient receptor potential vanilloid (TRPV) 1 and TRPV4. Heat shock proteins are activated under heat stress and contribute to both epithelial barrier dysfunction and airway inflammation. Accordingly, the frequency and severity of allergic rhinitis and asthma have been increasing. Heat activates TRPV3 in keratinocytes, causing the secretion of inflammatory mediators and eventually pruritus. Exposure to air pollutants alters the expression of genes that control skin barrier integrity and triggers an immune response, increasing the incidence and prevalence of atopic dermatitis. There is evidence that extreme temperature, heavy rains and floods, air pollution, and wildfires increase atopic dermatitis flares. In this narrative review, focused on the last 3 years of literature, we explore the effects of global warming on respiratory and skin barrier and their clinical consequences.

Preventive Effect of Pharmaceutical Phytochemicals Targeting the Src Family of Protein Tyrosine Kinases and Aryl Hydrocarbon Receptor on Environmental Stress-Induced Skin Disease

The skin protects our body; however, it is directly exposed to the environment and is stimulated by various external factors. Among the various environmental factors that can threaten skin health, the effects of ultraviolet (UV) and particulate matter (PM) are considered the most notable. Repetitive exposure to ultraviolet and particulate matter can cause chronic skin diseases such as skin inflammation, photoaging, and skin cancer. The abnormal activation of the Src family of protein tyrosine kinases (SFKs) and the aryl hydrocarbon receptor (AhR) in response to UV and/or PM exposure are involved in the development and aggravation of skin diseases. Phytochemicals, chemical compounds of natural plants, exert preventive effects on skin diseases through the regulation of various signaling pathways. Therefore, this review aims to highlight the efficacy of phytochemicals as potential nutraceuticals and pharmaceutical materials for the treatment of skin diseases, primarily by targeting SFK and AhR, and to explore the underlying mechanisms of action. Future studies are essential to validate the clinical potential for the prevention and treatment of skin diseases.

Particulate matter increases Cutibacterium acnes-induced inflammation in human epidermal keratinocytes via the TLR4/NF-κB pathway

Recent studies have demonstrated that particulate matter (PM) can induce oxidative stress and inflammatory responses that are related to the development or exacerbation of several inflammatory dermatoses. However, the effect of PM on acne vulgaris has yet to be determined. In this study, we induced acne-like inflammation in HEKn cells with several concentrations of Cutibacterium acnes (C. acnes) and Staphylococcus aureus peptidoglycan (PGN) to investigate whether PM exposure exacerbates acne-like inflammation and elucidate the underlying mechanisms. To confirm whether PM increases the messenger ribonucleic acid (mRNA) and protein levels of proinflammatory cytokines (IL-1α, IL-1β, IL-6, IL-8, and TNF-α) and cyclooxygenase (COX)-2 expression in C. acnes- or PGN-treated HEKn cells, we used quantitative real-time polymerase chain reactions, enzyme-linked immunosorbent assays, and western blot assays. The results demonstrated that C. acnes, PGN, and PM induced the expression of proinflammatory cytokines in a time- and dose-dependent manner at the mRNA and protein levels, respectively. Moreover, PM further increased the expression of proinflammatory cytokines, COX2, TLR4, and the phosphorylation of NF-κB in C. acnes- and PGN-treated HEKn cells. In conclusion, our results suggest that PM may exacerbate acne symptoms by increasing the inflammatory response.

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.

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.

Development of In Vitro Co-Culture Model to Mimic the Cell to Cell Communication in Response to Urban PM2.5

Background

Airborne particulate matter (PM), a widespread air contaminant, is a complex mixture of solids and aerosols composed of particles suspended in the air. PM is associated with inflammatory responses and may worsen inflammatory skin diseases. However, the mechanisms through which PM affects atopic dermatitis (AD) remain unclear.

Objective

To establish an in vitro model that more accurately mimics AD using human keratinocyte (HaCaT), dermal fibroblast (HDF), and mast cell (HMC-1) and using this model to investigate the mechanism through which PMs affect AD.

Methods

An AD-like in vitro model was established by seeding HaCaT, HDF, and HMC-1 cells with recombinant human interleukin (IL)-1α and polyinosinic:polycytidylic acid. We confirmed the effect of PM on the inflammatory cytokine expression of a triple-cell culture model. SRM 1649b Urban Dust, which is mainly composed of polycyclic aromatic hydrocarbons, was used as the reference PM. The effects of PM on the expression levels of proinflammatory cytokines and skin barrier markers were assessed using quantitative real-time polymerase chain reaction and western blotting. Inflammatory cytokine levels were measured using an enzyme-linked immunosorbent assay.

Results

Interactions between various skin cell types were evaluated using a co-culture system. PM treatment increased mRNA and protein levels of the inflammatory cytokines IL-6, IL-1α, tumor necrosis factor-α, IL-4, and IL-1β and decreased the expression of the skin barrier markers filaggrin and loricrin.

Conclusion

Our results suggest that an in vitro triple-cell culture model using HaCaT, HDF, and HMC-1 cells may be reliable for obtaining more physiological, functional, and reproducible data on AD and skin barriers.