Particulate matter induces inflammatory cytokine production via activation of NFκB by TLR5-NOX4-ROS signaling in human skin keratinocyte and mouse skin

Fine Particulate Matter-Induced Oxidative Stress Mediated by UVA-Visible Light Leads to Keratinocyte Damage

The human skin is exposed to various environmental factors including solar radiation and ambient air pollutants. Although, due to its physical and biological properties, the skin efficiently protects the body against the harm of environmental factors, their excessive levels and possible synergistic action may lead to harmful effects. Among particulate matter present in ambient air pollutants, PM2.5 is of particular importance for it can penetrate both disrupted and intact skin, causing adverse effects to skin tissue. Although certain components of PM2.5 can exhibit photochemical activity, only a limited amount of data regarding the interaction of PM2.5 with light and its effect on skin tissue are available. This study focused on light-induced toxicity in cultured human keratinocytes, which was mediated by PM2.5 obtained in different seasons. Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM) were employed to determine sizes of the particles. The ability of PM2.5 to photogenerate free radicals and singlet oxygen was studied using EPR spin-trapping and time-resolved singlet oxygen phosphorescence, respectively. Solar simulator with selected filters was used as light source for cell treatment to model environmental lightning conditions. Cytotoxicity of photoexcited PM2.5 was analyzed using MTT assay, PI staining and flow cytometry, and the apoptotic pathway was further examined using Caspase-3/7 assay and RT-PCR. Iodometric assay and JC-10 assay were used to investigate damage to cell lipids and mitochondria. Light-excited PM2.5 were found to generate free radicals and singlet oxygen in season-dependent manner. HaCaT cells containing PM2.5 and irradiated with UV-Vis exhibited oxidative stress features-increased peroxidation of intracellular lipids, decrease of mitochondrial membrane potential, enhanced expression of oxidative stress related genes and apoptotic cell death. The data indicate that sunlight can significantly increase PM2.5-mediated toxicity in skin cells.

Standardized Terminalia chebula Fruit Extract: A Natural Ingredient That Provides Long-Lasting Antioxidant Protection and Reverses Visible Signs of Pollution-Induced Skin Damage

Background

Identification of long-lasting natural antioxidants to protect against and repair skin damage induced by exposure to environmental pollution is in high demand.

Objective

To investigate a standardized Terminalia chebula (TC) fruit extract for its long-lasting antioxidant and anti-inflammatory properties and its ability to reverse the visible signs of pollution-induced skin damage in an 8-week clinical study.

Material and Methods

Chemical and cell-based in vitro studies were performed to characterize long-lasting antioxidant and anti-inflammatory properties; a clinical study with subjects with normal to dry skin living in a high-pollution city for the previous 5 years was conducted to assess if a formulation containing 1% standardized TC fruit extract affected significant improvements in skin’s visible condition and appearance compared with its placebo.

Results

The standardized TC fruit extract provided longer-lasting and more efficient neutralization of reactive oxygen species (ROS) than tocopherol; treatment of keratinocytes with the fruit extract prior to being stressed with urban dust safeguarded against increases in intracellular ROS, inhibited release of inflammatory cytokines IL-6 and IL-8 and protected membrane lipids against peroxidation. A clinical study yielded statistically significant improvements in dermatologist scores and subject self-assessments for skin texture, hydration, tone, firmness and radiance as compared to its placebo.

Conclusion

These studies validate the use of this standardized TC fruit extract not only as a restorative to diminish visible signs of existing damage but also as a preventative to help defend skin against damages caused by chronic exposure to environmental pollution.

Polycyclic aromatic hydrocarbons regulate the pigmentation pathway and induce DNA damage responses in keratinocytes, a process driven by systemic immunity

BACKGROUND

Urban pollution is correlated with an increased prevalence of skin pigmentation disorders, however the physiological processes underlying this association are unclear.

OBJECTIVES

To delineate the relationship between polycyclic aromatic hydrocarbons (PAHs), a key constituent of atmospheric pollution, and immunity/skin pigmentation pathways.

METHODS

We exposed peripheral blood mononuclear cells (PBMC) to PAHs and performed cytokines/chemokine profiling. We then examined the effect of immune activation on pigmentation by co-culturing PBMC and Benzo(a)pyrene (BaP) with reconstructed human pigmented epidermis (RHPE). To study the mechanism, we treated keratinocytes with conditioned medium from BaP-exposed PBMC and studied DNA damage responses, aryl hydrocarbon receptor (AhR) activation and pro-pigmentation factor, proopiomelanocortin (POMC) secretion.

RESULTS

PAHs induced up-regulation of inflammatory cytokines/chemokine in PBMC. Co-culturing of RHPE with PBMC+BaP resulted in increased melanin content and localization. BaP-conditioned medium significantly increased DNA damage, p53 stabilization, AhR activation and POMC secretion in keratinocytes. We found that IFNγ induced DNA damage, while TNFα and IL-8 potentiated POMC secretion in keratinocytes. Importantly, BaP-conditioned medium-induced DNA damage and POMC secretion is prevented by antioxidants vitamin E, vitamin C and sulforaphane, as well as the prototypical corticosteroid dexamethasone. Finally, vitamin C and sulforaphane enhanced the genome protective and depigmentation effects of dexamethasone, providing proof-of-concept for a combinatorial approach for the prevention and/or correction of PAH-induced pigment spots formation.

CONCLUSION

Our study reveals the importance of systemic immunity in regulating PAH-induced skin pigmentation, and provide a new keratinocyte DNA damage response mechanistic target for the prevention or reversal of pollution-associated skin pigmentation.

Enhanced Cerebral Microbleeds by Long-Term Air Pollution Exposure in Spontaneously Hypertensive Rats

BACKGROUND

Cerebral microbleeds (CMBs) are associated with a high risk for stroke . The present study determined whether long-term exposure to PM2.5 results in progressive worsening of CMBs and induction of systemic inflammation and microvascular oxidative stress.

METHODS

Sixteen male Spontaneously hypertensive rats (SHR) and eight Wistar-Kyoto (WKY) rats were exposed to either filtered air or PM2.5 for 12 months. To detect CMBs, rats were imaged using a 7-T MRI. To determine systemic inflammation and oxidative stress, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), as well as reactive oxygen species (ROS), NADPH activity and its subunits p22/47/67phox & gp91phox were measured.

RESULTS

During the exposure period, the mean daily concentration of PM2.5 was 59.2 ± 1.0 μg/m³. PM2.5 exposure significantly increased the incidence of CMBs compared to the PM2.5 (-) group (37.5% vs 12.5% incidence rate, p < 0.001). Animals exposed to PM2.5 also had significantly increased systolic blood pressures (SBPs) at 3 months (173 ± 5 vs 157 ± 5 mmHg, p < 0.05), 6 months (218 ± 6 vs 193 ± 7 mmHg, p < 0.01), 9 months (222 ± 6 vs 203 ± 8 mmHg, p < 0.05), and 12 months (231 ± 4 vs 207 ± 5 mmHg, p = 0.01). Additionally, there were significant elevations in IL-6, MCP-1, and TNF-α in the exposed group. Furthermore, PM2.5 significantly increased NOX activity and protein levels of gp91phox and p22/47/67phox.

CONCLUSION

In the SHR model, long-term exposure to PM2.5 worsened CMBs, increased SBPs, induced systemic inflammation and oxidative stress. Therefore, PM2.5 is potentially a controllable risk factor that promotes CMBs in certain patients, such as those with hypertension.

MicroRNA-30d-5p ameliorates lipopolysaccharide-induced acute lung injury via activating AMPKα

OBJECTIVES

Acute lung injury (ALI) is a devastating lung disease characterized by uncontrolled pulmonary inflammation and oxidative stress. Currently, no effective therapeutic strategies are available for ALI and its prognosis remains poor. The present study aims to investigate the role and potential mechanism of microRNA-30d-5p (miR-30d-5p) in the progression of ALI.

METHODS

Mice were intravenously treated with miR-30d-5p agomir, antagomir or their respective controls for 3 consecutive days and then were exposed to a single intratracheal injection of lipopolysaccharide (LPS) for 12 h at a dosage of 5 mg/kg to induce ALI. To inhibit adenosine monophosphate-activated protein kinase α (AMPKα) or phosphodiesterase 4 D (PDE4D), compound C (CpC) and rolipram were used.

RESULTS

miR-30d-5p expression in the lungs was significantly inhibited by LPS treatment. miR-30d-5p agomir significantly alleviated, while miR-30d-5p antagomir aggravated pulmonary inflammation, oxidative damage, and dysfunction in ALI mice. Besides, we found that miR-30d-5p agomir ameliorated LPS-induced ALI via activating AMPKα and that the inhibition of AMPKα by CpC completely abolished these beneficial effects of miR-30d-5p agomir. Further findings validated that PDE4D downregulation was required for the activation of AMPKα by miR-30d-5p agomir.

CONCLUSION

miR-30d-5p ameliorates LPS-induced ALI via activating AMPKα and it is a valuable therapeutic candidate in the treatment of ALI.

Anti-pollution skincare: Research on effective ways to protect skin from particulate matter

While there is increasing interest in anti-pollution care to particulate matter (PM), there has been no research evaluating the efficacy of skin care products in a real-world setting. Our objective was to find effective ways to protect skin from PM. In total, 64 volunteers whose skin was classified as reactive to PM concentration in the previous study were enrolled. Through split-face study, different combinations of skin care products (barrier cream, barrier cream/micellar water, antioxidant, and antioxidant/micellar water) were applied for 4 weeks during the high-PM period. The biophysical properties were measured, and a facial analysis system was used to evaluate skin condition at days 0, 14, and 28. The concentrations of PM and daily events that may affect skin conditions were also recorded. The mean concentration levels of PM₁₀ and PM_2.5 from days 0 to 14 were higher in the barrier cream group than in the antioxidant group. For each group, aside from skin tone in the antioxidant/micellar water group, there were no statistically significant differences in skin measurements before and after the application, which reflects no aggravation in skin condition during high-PM periods. Intergroup analysis showed no differences in skin measurements among the four groups from day 0 to day 14, from day 14 to day 28, and from day 0 to 28. For anti-pollution care, maintaining skin barrier function using barrier cream seems to be sufficient in individuals sensitive to PM.

Natural compounds protect the skin from airborne particulate matter by attenuating oxidative stress

Particulate matter (PM) is a common indirect indicator of air pollution and threatens public health upon prolonged exposure, leading to oxidative stress, increasing the risk of develop respiratory and cardiovascular, as well as several autoimmune diseases and cancer. Nowadays, as a first line defense against PM, skin health attracted much attention. Our review summarized the skin damage mechanism induced by PM, including damage skin barrier directly, reactive oxygen species (ROS) accumulation, autophagy, and two canonical signaling pathways. Furthermore, ROS and oxidative stress have been considered pathogenesis centers, with essential skin damage roles. Extracts from plants and natural compounds which present high antioxidant capacity could be used to treat or protect against air pollution-related skin damage. We conclude the extracts reported in recent studies with protective effects on PM-mediated skin damage. Besides, the mechanism of extracts' positive effects has been revealed partially.

Extracellular vesicles produced by primary human keratinocytes in response to TLR agonists induce stimulus-specific responses in antigen-presenting cells

Cells can communicate through the extracellular vesicles (EVs) they secrete. Pathogen associated molecular patterns (PAMPs), alter the biophysical and communicative properties of EVs released from cells, but the functional consequences of these changes are unknown. Characterization of keratinocyte-derived EVs after poly(I:C) treatment (poly(I:C)-EVs) showed slight differences in levels of EV markers TSG101 and Alix, a loss of CD63 and were positive for autophagosome marker LC3b-II and the cytokine IL36γ compared to EVs from unstimulated keratinocytes (control-EVs). Flagellin treatment (flagellin-EVs) led to an EV marker profile like control-EVs but lacked LC3b-II. Flagellin-EVs also lacked IL-36γ despite nearly identical intracellular levels. While poly(I:C) treatment led to the clear emergence of a > 200 nm diameter EV sub-population, these were not found in flagellin-EVs. EV associated IL-36γ colocalized with LC3b-II in density gradient analysis, equilibrating to 1.10 g/mL, indicating a common EV species. Poly(I:C), but not flagellin, induced intracellular vesicles positive for IL-36γ, LC3b-II, Alix and TSG101, consistent with fusion of autophagosomes and multivesicular bodies. Simultaneous rapamycin and flagellin treatment induced similar intracellular vesicles but was insufficient for the release of IL-36γ⁺/LC3b-II⁺ EVs. Finally, a qRT-PCR array screen showed eight cytokine/chemokine transcripts were altered (p < 0.05) in monocyte-derived Langerhans cells (LCs) when stimulated with poly(I:C)-EVs while three were altered when LCs were stimulated with flagellin-EVs compared to control-EVs. After independent confirmation, poly(I:C)-EVs upregulated BMP6 (p = 0.035) and flagellin-EVs upregulated CXCL8 (p = 0.005), VEGFA (p = 0.018) and PTGS2 (p = 0.020) compared to control-EVs. We conclude that exogenous signals derived from pathogens can alter keratinocyte-mediated modulation of the local immune responses by inducing changes in the types of EVs secreted and responses in antigen presenting cells.

Antioxidant and Anti-inflammatory Effect of Cannabidiol Contributes to the Decreased Lipid Peroxidation of Keratinocytes of Rat Skin Exposed to UV Radiation

There is a great need for compounds with antioxidant and anti-inflammatory properties for protection against UV radiation, which is the most prooxidative physical factor that skin cells are exposed to everyday. Therefore, the aim of the study was to evaluate the mechanism of phytocannabinoid-cannabidiol (CBD) action in vivo on lipid metabolism in keratinocytes of rat skin exposed to UVA/UVB radiation. Our results show that CBD protects keratinocytes against the effects of UVA/UVB radiation by reducing lipid peroxidation products: 4-HNE and 8-isoPGF2α. In addition, CBD significantly increases the level of endocannabinoids, such as anandamide, 2-arachidonylglycerol, and palmitoylethanolamide, and the activation of their receptors CB1/2 or TRPV1. The above changes are due to the protective effect of CBD against the UVA/UVB-induced decrease in the level/activity of superoxide dismutase and the components of the thioredoxin and glutathione systems. CBD also increases the in vivo transcriptional activity of Nrf2 and the expression of its Bach1 inhibitor as well as preventing the UVA/UVB-induced increase in the expression of Nrf2 activators p21, p62, p38, and KAP1 and proinflammatory factors such as NFκB and TNFα. By counteracting oxidative stress and changes in lipid structure in keratinocytes, CBD prevents cellular metabolic disturbances, protecting the epidermis against UV damage.

Sargassum horneri (Turner) C. Agardh containing polyphenols attenuates particulate matter-induced inflammatory response by blocking TLR-mediated MYD88-dependent MAPK signaling pathway in MLE-12 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Sargassum horneri (Turner) C. Agardh (S. horneri), an edible brown marine algae, is known to have immunomodulatory effects and has been used in oriental medicine to treat inflammatory diseases. It is well known that ambient particulate matter (PM) is closely related to increased respiratory diseases inducing lung inflammation.

AIM

Considering the use of Sargassum horneri in traditional medicine to treat inflammatory diseases, we hypothesized and investigated the use of Sargassum horneri containing polyphenols against PM-induced inflammatory responses.

MATERIALS AND METHODS

In this study, we evaluated the impact of PM (majority <2.5 μm in diameter) on deep bronchial penetration ability upon inhalation and a therapeutic approach to mitigate its harmful effects using an ethanol extract of Sargassum horneri, an edible brown algae, containing polyphenols on a type II alveolar epithelial cell line, MLE-12.

RESULTS

PM triggered mRNA expression of toll-like receptors (TLRs) TLR2/4/7, and those TLRs were significantly attenuated by Sargassum horneri extract (SHE). SHE further attenuated the phosphorylation of mitogen-activated protein kinase (MAPK) p38, extracellular signal-regulated kinase 1/2 (Erk1/2), and c-Jun NH (2)-terminal kinase (JNK), which were also activated in PM-exposed cells. Altogether, SHE subdued the PM-induced mRNA expression of pro-inflammatory cytokines (interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6) and lung epithelial cell derived-chemokines (IL-8, monocyte chemoattractant protein-1 (MCP-1), and chemokine (C-C motif) ligand 5 (CCL5)). SHE also suppressed the mRNA expression of PM-induced pro-allergic cytokines thymic stromal lymphopoietin (TSLP) and interleukin (IL)-33. Furthermore, we showed that SHE suppressed the MAPK-dependent signaling pathway by attenuating receptor-associated factor (TRAF) 6 activation of proteins MyD88 and TNF.

CONCLUSION

Taking all the data together, we suggest that the anti-inflammatory potential of SHE on PM-exposed MLE-12 cells is mediated by the inhibition of PM-triggered downstream signaling along the TLR2/4/7-MyD88-TRAF6 axis of MAPK signaling.

Reactive Oxygen Species-Mediated Inflammation and Apoptosis in Hand-Foot Syndrome Induced by PEGylated Liposomal Doxorubicin

BACKGROUND

Doxil® (PEGylated liposomal doxorubicin, PLD) has been widely used in cancer treatment due to its excellent therapeutic efficacy, but it can simultaneously cause severe adverse effects such as hand-foot syndrome (HFS). To date, the pathophysiologic mechanism of HFS development induced by PLD administration has not been well understood.

MATERIALS AND METHODS

The histological features of skin lesion in PLD-induced HFS model were characterized by hematoxylin and eosin (H&E) staining and picrosirius red staining, and the induction of inflammation and apoptosis in the epidermal layer was detected by immunohistochemical and TUNEL staining. Moreover, the generation of reactive oxygen species (ROS) was determined to elucidate the potential mechanism of skin lesion in the development of HFS.

RESULTS

The administration of PLD has been demonstrated to induce the histological damage of skin tissues including the destruction of collagen fibers and the induction of severe inflammation and apoptosis of epidermal cells. The mechanism was probably attributed to the accumulation of PLD in the skin tissues during the long-term circulation and further the induction of ROS to cause the oxidative damage of keratinocytes owing to the sustained release of doxorubicin from PLD.

CONCLUSION

The ROS generation induced by the administration of PLD has been identified to be a crucial factor in the development of HFS, which could be used as a potential therapeutic target to alleviate the HFS symptom of PLD administration.

Role of Epigenetics in the Regulation of Immune Functions of the Skin

This review is intended to illuminate the emerging understanding of epigenetic modifications that regulate both adaptive and innate immunity in the skin. Host defense of the epidermis and dermis involves the interplay of many cell types to enable homeostasis; tolerance to the external environment; and appropriate response to transient microbial, chemical, and physical insults. To understand this process, the study of cutaneous immunology has focused on immune responses that reflect both adaptive learned and genetically programmed innate defense systems. However, recent advances have begun to reveal that epigenetic modifications of chromatin structure also have a major influence on the skin immune system. This deeper understanding of how enzymatic changes in chromatin structure can modify the skin immune system and may explain how environmental exposures during life, and the microbiome, lead to both short-term and long-term changes in cutaneous allergic and other inflammatory processes. Understanding the mechanisms responsible for alterations in gene and chromatin structure within skin immunocytes could provide key insights into the pathogenesis of inflammatory skin diseases that have thus far evaded understanding by dermatologists.

Sulforaphane controls the release of paracrine factors by keratinocytes and thus mitigates particulate matter-induced premature skin aging by suppressing melanogenesis and maintaining collagen homeostasis

BACKGROUND

Skin aging, potentially caused by exposure to particulate matter (PM)_2.5, is characterized by wrinkling, abnormal pigmentation, and skin dryness triggered by several keratinocyte-derived paracrine factors. Sulforaphane (4-methylsulfinylbutyl isothiocyanate, SFN), commonly found in cruciferous vegetables, has diverse biological effects on skin tissue.

PURPOSE

In the present study, we have investigated whether SFN may alleviate PM_2.5-induced premature skin aging.

METHODS

We used keratinocyte/melanocyte or keratinocyte/fibroblast coculture models of skin cells and measured the parameters of melanogenesis, collagen homeostasis and inflammation.

RESULTS

SFN inhibited the development of reactive oxygen species in keratinocytes exposed to PM_2.5. In keratinocyte/melanocyte cocultures, it significantly inhibited the upregulation of melanogenic paracrine mediators (including endothelin-1 and prostaglandin E2) in keratinocytes exposed to PM_2.5; the synthesis of melanogenic proteins including microphthalmia-associated transcription factor, tyrosinase-related protein 1, and tyrosinase; and the levels of melanin in melanocytes. SFN treatment of keratinocyte/fibroblast cocultures significantly reduced the PM_2.5-induced expression of NF-κB-mediated cytokines including interleukin-1β, interleukin-6, tumor necrosis factor α, and cyclooxygenase-2. In fibroblasts of the keratinocyte/fibroblast coculture system, the expression levels of phospho-NF-κB, cysteine-rich protein 61, and matrix metalloproteinase-1 were significantly decreased whereas procollagen type I synthesis was significantly increased.

CONCLUSION

Collectively, our results suggest that SFN mitigates PM_2.5-induced premature skin aging by suppressing melanogenesis and maintaining collagen homeostasis. It acts by regulating the release of paracrine factors from keratinocytes.

ROS production and mitochondrial dysfunction driven by PU.1-regulated NOX4-p22phox activation in Aβ-induced retinal pigment epithelial cell injury

Rationale: Amyloid β (Aβ) deposition, an essential pathological process in age-related macular degeneration (AMD), causes retinal pigment epithelium (RPE) degeneration driven mostly by oxidative stress. However, despite intense investigations, the extent to which overoxidation contributes to Aβ-mediated RPE damage and its potential mechanism has not been fully elucidated.

Methods: We performed tandem mass-tagged (TMT) mass spectrometry (MS) and bioinformatic analysis of the RPE-choroid complex in an Aβ_1-40-induced mouse model of retinal degeneration to obtain a comprehensive proteomic profile. Key regulators in this model were confirmed by reactive oxygen species (ROS) detection, mitochondrial ROS assay, oxygen consumption rate (OCR) measurement, gene knockout experiment, chromatin immunoprecipitation (ChIP), and luciferase assay.

Results: A total of 4243 proteins were identified, 1069 of which were significantly affected by Aβ_1-40 and found to be enriched in oxidation-related pathways by bioinformatic analysis. Moreover, NADPH oxidases were identified as hub proteins in Aβ_1-40-mediated oxidative stress, as evidenced by mitochondrial dysfunction and reactive oxygen species overproduction. By motif and binding site analyses, we found that the transcription factor PU.1/Spi1 acted as a master regulator of the activation of NADPH oxidases, especially the NOX4-p22^phox complex. Also, PU.1 silencing impeded RPE oxidative stress and mitochondrial dysfunction and rescued the retinal structure and function.

Conclusion: Our study suggests that PU.1 is a novel therapeutic target for AMD, and the regulation of PU.1 expression represents a potentially novel approach against excessive oxidative stress in Aβ-driven RPE injury.

Mechanism of PM2.5-induced human bronchial epithelial cell toxicity in central China

Exposure to PM_2.5 has been linked to respiratory disorders, yet knowledge of the molecular mechanism is limited. Here, PM_2.5 was monitored and collected in central China, and its cytotoxicity mechanism on human bronchial epithelial cells (BEAS-2B) was investigated. With the average concentration of 109 ± 69 μg/m³, PM_2.5 was rich in heavy metals and organic pollutants. After exposure to PM_2.5, the viability of BEAS-2B cells decreased, where 510 dysregulated genes were predicted to induce necroptosis via inhibiting ATP synthesis through the oxidative phosphorylation signaling pathway. Cellular experiments demonstrated that the content of ATP was downregulated, while the expression of RIP3, a necroptosis indicator, was upregulated. Besides, four enzymes in charge of ATP synthesis were downregulated, including ATP5F, NDUF, COX7A, and UQCR, while two genes of RELA and CAPN1 responsible for necroptosis were upregulated. Furthermore, N-acetylcysteine was applied as an enhancer for ATP synthesis, which reversed the downregulation of ATP5F, NDUF, and COX7A, and consequently alleviated the elevation of RELA, CAPN1, and RIP3. In conclusion, PM_2.5 exposure downregulates ATP5F, NDUF, COX7A, and UQCR, and that inhibits ATP synthesis via the oxidative phosphorylation signaling pathway, which subsequently upregulates RELA and CAPN1 and ultimately leads to necroptosis of BEAS-2B cells.

Toll-like receptor 5 deficiency diminishes doxorubicin-induced acute cardiotoxicity in mice

Rationale: Clinical application of doxorubicin (DOX) is limited by its toxic cardiovascular side effects. Our previous study found that toll-like receptor (TLR) 5 deficiency attenuated cardiac fibrosis in mice. However, the role of TLR5 in DOX-induced cardiotoxicity remains unclear.

Methods: To further investigate this, TLR5-deficient mice were subjected to a single intraperitoneal injection of DOX to mimic an acute model.

Results: Here, we reported that TLR5 expression was markedly increased in response to DOX injection. Moreover, TLR5 deficiency exerted potent protective effects against DOX-related cardiac injury, whereas activation of TLR5 by flagellin exacerbated DOX injection-induced cardiotoxicity. Mechanistically, the effects of TLR5 were largely attributed to direct interaction with spleen tyrosine kinase to activate NADPH oxidase (NOX) 2, increasing the production of superoxide and subsequent activation of p38. The toxic effects of TLR5 activation in DOX-related acute cardiac injury were abolished by NOX2 deficiency in mice. Our further study showed that neutralizing antibody-mediated TLR5 depletion also attenuated DOX-induced acute cardiotoxicity.

Conclusion: These findings suggest that TLR5 deficiency attenuates DOX-induced cardiotoxicity in mice, and targeting TLR5 may provide feasible therapies for DOX-induced acute cardiotoxicity.

In ovo very early-in-life exposure to diesel exhaust induced cardiopulmonary toxicity in a hatchling chick model

Diesel exhaust (DE) had been associated with cardiopulmonary toxicity and developmental toxicity. However, neonatal very early-in-life exposure had not been extensively studied previously. To investigate the potential effects of neonatal very early-in-life exposure to DE, a brand-new chicken embryo in ovo exposure model had been established, with which the cardiopulmonary effects of DE exposure via air cell infusion at embryonic day 18/19 (ED18/19) were assessed in hatchling chicks post-hatch 0-, 1-, or 2-weeks. Heart rates were assessed with electrocardiography. Cardiac and pulmonary morphologies were investigated with histopathological methods. Cardiopulmonary effects were explored with immunohistochemistry for alpha smooth muscle actin (alpha-SMA). In further investigations, the expression levels of phosphorylated AhR, serum levels of TGF-β1, phosphorylated SMAD2/3 and phosphorylated p38MAPK were assessed in the lung tissues. Significantly elevated heart rates, increased right ventricular wall thickness and cardiac collagen deposition were observed in the hearts of exposed hatchling chicks. Significantly increased collagen deposition as well as increased vascular alpha-SMA layer thickness/decreased cavity area were observed in exposed animal lungs. These effects persisted up to two weeks post-hatch. Mechanistic studies revealed elevated phosphorylated AhR expression levels in 0-week and 1-week chicken lungs, while phosphorylated SMAD2/3 levels significantly increased in 0-week chicken lungs but decreased in 2-week chicken lungs following DE exposure. Phosphorylation of p38MAPK did not remarkably increase until 2-week post-hatch. In summary, the novel chicken neonatal very early-in-life exposure model effectively exposed the chicken embryos during the neonatal initial breathing, resulting in cardiopulmonary toxicity, which is associated with AHR, TGF-β1 and MAPK signaling.

Caffeine Targets SIRT3 to Enhance SOD2 Activity in Mitochondria

Caffeine is chemically stable and not readily oxidized under normal physiological conditions but also has antioxidant effects, although the underlying molecular mechanism is not well understood. Superoxide dismutase (SOD) 2 is a manganese-containing enzyme located in mitochondria that protects cells against oxidative stress by scavenging reactive oxygen species (ROS). SOD2 activity is inhibited through acetylation under conditions of stress such as exposure to ultraviolet (UV) radiation. Sirtuin 3 (SIRT3) is the major mitochondrial nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase, which deacetylates two critical lysine residues (lysine 68 and lysine 122) on SOD2 and promotes its antioxidative activity. In this study, we investigated whether the antioxidant effect of caffeine involves modulation of SOD2 by SIRT3 using in vitro and in vivo models. The results show that caffeine interacts with SIRT3 and promotes direct binding of SIRT3 with its substrate, thereby enhancing its enzymatic activity. Mechanistically, caffeine bound to SIRT3 with high affinity (K_D = 6.858 × 10^–7 M); the binding affinity between SIRT3 and its substrate acetylated p53 was also 9.03 (without NAD⁺) or 6.87 (with NAD⁺) times higher in the presence of caffeine. Caffeine effectively protected skin cells from UV irradiation-induced oxidative stress. More importantly, caffeine enhanced SIRT3 activity and reduced SOD2 acetylation, thereby leading to increased SOD2 activity, which could be reversed by treatment with the SIRT3 inhibitor 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP) in vitro and in vivo. Taken together, our results show that caffeine targets SIRT3 to enhance SOD2 activity and protect skin cells from UV irradiation-induced oxidative stress. Thus, caffeine, as a small-molecule SIRT3 activator, could be a potential agent to protect human skin against UV radiation.

CD248 as a novel therapeutic target in pulmonary arterial hypertension

Pulmonary vascular remodeling is the most important pathological characteristic of pulmonary arterial hypertension (PAH). No effective treatment for PAH is currently available because the mechanism underlying vascular remodeling is not completely clear. CD248, also known as endosialin, is a transmembrane protein that is highly expressed in pericytes and fibroblasts. Here, we evaluated the role of CD248 in pulmonary vascular remodeling and the processes of PAH pathogenesis. Activation of CD248 in pulmonary artery smooth muscle cells (PASMCs) was found to be proportional to the severity of PAH. CD248 contributed to platelet-derived growth factor-BB (PDGF-BB)-induced PASMC proliferation and migration along with the shift to more synthetic phenotypes. In contrast, treatment with Cd248 siRNA or the anti-CD248 therapeutic antibody (ontuxizumab) significantly inhibited the PDGF signaling pathway, obstructed NF-κB p65-mediated transcription of Nox4, and decreased reactive oxygen species production induced by PDGF-BB in PAMSCs. In addition, knockdown of CD248 alleviated pulmonary vascular remodeling in rat PAH models. This study provides novel insights into the dysfunction of PASMCs leading to pulmonary vascular remodeling, and provides evidence for anti-remodeling treatment for PAH via the immediate targeting of CD248.

Particulate Matter Induces Tissue OxInflammation: From Mechanism to Damage

Significance: Oxidative stress and oxidative damage are central hypothetical mechanisms for the adverse effects of airborne particulate matter (PM). Activation of inflammatory cells capable of generating reactive oxygen and nitrogen species is another proposed damage pathway. Understanding the interplay between these responses can help us understand the adverse health effects attributed to breathing polluted air. Recent Advances: The consequences of PM exposure on different organs are oxidative damage, decreased function, and inflammation, which can lead to the development/exacerbation of proinflammatory disorders. Mitochondrial damage is also an important event in PM-induced cytotoxicity. Critical Issues: Reactive oxygen species (ROS) are generated during phagocytosis of the particles, leading to enhancement of oxidative stress and triggering the inflammatory response. The activation of inflammatory signaling pathways results in the release of cytokines and other mediators, which can further induce ROS production by activating endogenous enzymes, leading to a positive feedback loop, which can aggravate the effects triggered by PM exposure. Future Directions: Further research is required to elucidate the exact mechanisms by which PM exposure results in adverse health effects, in terms of the relationship between the redox responses triggered by the presence of the particles and the inflammation observed in the different organs, so the development/exacerbation of PM-associated health problems can be prevented.

Impact of airborne particulate matter on skin: a systematic review from epidemiology to in vitro studies

BACKGROUND

Air pollution is killing close to 5 million people a year, and harming billions more. Air pollution levels remain extremely high in many parts of the world, and air pollution-associated premature deaths have been reported for urbanized areas, particularly linked to the presence of airborne nano-sized and ultrafine particles.

MAIN TEXT

To date, most of the research studies did focus on the adverse effects of air pollution on the human cardiovascular and respiratory systems. Although the skin is in direct contact with air pollutants, their damaging effects on the skin are still under investigation. Epidemiological data suggested a correlation between exposure to air pollutants and aggravation of symptoms of chronic immunological skin diseases. In this study, a systematic literature review was conducted to understand the current knowledge on the effects of airborne particulate matter on human skin. It aims at providing a deeper understanding of the interactions between air pollutants and skin to further assess their potential risks for human health.

CONCLUSION

Particulate matter was shown to induce a skin barrier dysfunction and provoke the formation of reactive oxygen species through direct and indirect mechanisms, leading to oxidative stress and induced activation of the inflammatory cascade in human skin. Moreover, a positive correlation was reported between extrinsic aging and atopic eczema relative risk with increasing particulate matter exposure.

Ambient particulate matter triggers dysfunction of subcellular structures and endothelial cell apoptosis through disruption of redox equilibrium and calcium homeostasis

Ambient particulate matter (APM) is becoming a global environmental problem that seriously jeopardizes public health. Previous evidence hinted that APM correlates to cardiovascular diseases. As a potential target, equilibrium of endothelial cell is a prerequisite for vascular health which could be vulnerably attacked by particles, but the specific mechanisms whereby APM damages endothelial cells have not been fully elucidated. In the current study, based on two classical mechanisms of oxidative stress and intracellular calcium overload, we aimed to explore their roles in APM-induced endothelial cell apoptosis from the perspective of subcellular levels, including endoplasmic reticulum (ER) stress and mitochondrial dysfunction. As a result, PM SRM1648a results in oxidative stress and calcium overload in EA.hy926 cells. Additionally, ERs and mitochondria could be severely disturbed by particles in morphology and function, characterized by swelling ERs, mitochondrial fission and disappearance of cristae, coupled with ER damage, mtROS overproduction and significant reduction in mitochondrial membrane potential (MMP). Adverse effects on these organelles are the prime culprits of following apoptosis in endothelial cells. Fortunately, additional antioxidants and calcium inhibitors could mitigate cellular lesion through improvement of subcellular function. Intriguingly, antioxidants relieve cell stress via both mitochondrial and ER stress-mediated pathways, whereas the role of calcium modulators in cell apoptosis is independent of the mitochondrial pathway but could be explained by amelioration of ER stress. In conclusion, our data basically revealed that internalized PM SRM1648a triggers oxidative stress and calcium influx in EA.hy926 endothelial cells, followed by multiple subcellular damage and eventually contributes to cell death, during which antioxidants and calcium inhibitors confer protective effects.

Enzymatically synthesized glycogen protects inflammation induced by urban particulate matter in normal human epidermal keratinocytes

Urban particulate matters (PM) exposure is significantly correlated with extrinsic skin aging signs and skin cancer incidence. PM contains polycyclic aromatic hydrocarbons, and they act as the agonists of aryl hydrocarbon receptor (AhR). Activation of AhR promotes generation of intracellular reactive oxygen species (ROS) and inflammation. Enzymatically synthesized glycogen (ESG), which is synthesized from starch, possesses various functions, such as anti-tumor, anti-obesity and antioxidant. However, the effects of ESG on PM-induced skin inflammation remain unclear. In this study, we investigated whether ESG has a protective effect on PM-induced oxidative stress and inflammation in human epidermal keratinocytes. ESG inhibited PM-induced expression of inflammatory cytokines IL6, TNFA and PTGS2. ESG also inhibited PM-induced phosphorylation of MAPKs and ROS accumulation. However, ESG had no effect on PM-induced expression of CYP1A1, one of the target proteins of AhR. On the other hand, ESG increased nuclear translocation of Nrf2 and expression of antioxidant proteins, HO-1 and NQO1. These results suggest that ESG suppressed PM-induced inflammation by decreasing ROS accumulation through the Nrf2 pathway.

Subacute exposure of PM2.5 induces airway inflammation through inflammatory cell infiltration and cytokine expression in rats

Accumulating evidences support that exposure to fine particulate matter (PM_2.5) could cause inflammation of the airway, but its underlying mechanisms are less known. Our study aimed to explore the potential effect of non-canonical NF-κB signaling pathway in airway inflammation, which caused by PM_2.5, and the possible regulatory relationship between miR-6747-5p and NF-κB2. The histological analysis from in vivo study manifested that PM_2.5 could induce the exudation and infiltration of polymorphonuclear leukocytes (PMNs). Immunohistochemistry results of lung tissues showed that PM_2.5 increased ICAM-1, 6Ckine, SDF-1 and BAFF positive staining with a dose-dependent manner. In addition, PM_2.5 could induce the p52 nuclear translocation to trigger non-canonical NF-κB signaling pathway in lung tissues and BEAS-2B cells. Targetscan reporter gene assay showed that there was a target regulatory relationship between miR-6747-5p and NF-κB2. Besides, the chemical mimics of miR-6747-5p weakened the activation of non-canonical NF-κB signaling pathway induced by PM_2.5. In summary, exposure to PM_2.5 could trigger airway inflammation by activating the non-canonical NF-κB signaling pathway, which may be related to the negative feedback regulation mechanism of miR-6747-5p. Our findings will give new ideas into the toxic effects of airway inflammation triggered by PM_2.5.

Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

Particulate matter poses health risk to developing organisms. To investigate particulate matters with a diameter smaller than 2.5 um (PM2.5)-induced developmental cardiotoxicity, fertile chicken eggs were exposed to PM2.5 via air cell injection at doses of 0.05, 0.2, 0.5, 2, and 5 mg/egg kg. Morphological changes in the embryonic day four (ED4) and hatchling hearts were assessed with histological techniques. Heart rates of hatchling chickens were measured with electrocardiography. The protein expression levels of nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-kb p65), inducible nitric oxide synthase (iNOS), and matrix metallopeptidase 9 (MMP9) were assessed with immunohistochemistry or western blotting in hatchling hearts. PM2.5 exposure elevated areas of heart in ED4 embryo, increased heart rate, and thickened right ventricular wall thickness in hatchling chickens. Immunohistochemistry revealed enhanced NF-kb p65 expression in hatchling hearts. Western blotting results indicated that both iNOS and MMP9 expression were enhanced by lower doses of PM2.5 exposure (0.2 and 0.5 mg/kg) but not 2 mg/kg. In summary, developmental exposure to PM2.5 induced developmental cardiotoxicity in chicken embryo and hatchling chickens, which is associated with NF-kb p65, iNOS, and MMP9.

Urban Particulate Matter Enhances ROS/IL-6/COX-II Production by Inhibiting MicroRNA-137 in Synovial Fibroblast of Rheumatoid Arthritis

BACKGROUND

Rheumatoid arthritis (RA) has been associated with air pollution, possibly due to the augmentation of inflammatory effects. In this study, we aimed to determine the roles of inflammatory pathways and microRNA involved in the pathogenesis of RA fibroblast-like synoviocytes (FLS) inflammation induced by particulate matter.

METHODS

The inflammatory mediators, messenger RNAs, microRNAs and their interrelationships were investigated using western blotting, QPCR, ELISA and immunohistochemistry.

RESULTS

Particulate matter (PMs) induced an increase in the expression of interleukin-6 (IL-6) and cyclooxygenase-II (COX-II) in RA-FLS and microRNA-137 was found definitely to mediate the inflammatory pathways. PMs-induced generation of reactive oxygen species (ROS) in RA-FLS was attenuated by pretreatment with antioxidants. Nox-dependent ROS generation led to phosphorylation of ERK1/2, p38 and JNK, followed by downregulation of microRNA-137. In vivo studies, the joints of rats exposed to PMs revealed synovial fibroblast inflammation under pathologic examination and the expressions of IL-6 and COX-II were obviously increased. PMs exposure results in activated ROS-mediated mitogen-activated protein kinase (MAPK) signaling pathways and cause increased IL-6 and COX-II through downregulation of hsa-miRNA-137, which lead to inflammation and RA exacerbation.

CONCLUSIONS

microRNA-137 plays an important role in PMs-induced RA acute exacerbation through MAPK signaling pathways and IL-6/COX-II activation. Targeting these mechanisms can potentially be used to develop new therapeutic strategies and prevention of RA inflammation in the future.

Organ-on-a-Chip: Opportunities for Assessing the Toxicity of Particulate Matter

Recent developments in epidemiology have confirmed that airborne particulates are directly associated with respiratory pathology and mortality. Although clinical studies have yielded evidence of the effects of many types of fine particulates on human health, it still does not have a complete understanding of how physiological reactions are caused nor to the changes and damages associated with cellular and molecular mechanisms. Currently, most health assessment studies of particulate matter (PM) are conducted through cell culture or animal experiments. The results of such experiments often do not correlate with clinical findings or actual human reactions, and they also cause difficulty when investigating the causes of air pollution and associated human health hazards, the analysis of biomarkers, and the development of future pollution control strategies. Microfluidic-based cell culture technology has considerable potential to expand the capabilities of conventional cell culture by providing high-precision measurement, considerably increasing the potential for the parallelization of cellular assays, ensuring inexpensive automation, and improving the response of the overall cell culture in a more physiologically relevant context. This review paper focuses on integrating the important respiratory health problems caused by air pollution today, as well as the development and application of biomimetic organ-on-a-chip technology. This more precise experimental model is expected to accelerate studies elucidating the effect of PM on the human body and to reveal new opportunities for breakthroughs in disease research and drug development.

The aryl hydrocarbon receptor as a target of environmental stressors - Implications for pollution mediated stress and inflammatory responses

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor regulating the expression of genes, for instance encoding the monooxygenases cytochrome P450 (CYP) 1A1 and CYP1A2, which are important enzymes in metabolism of xenobiotics. The AHR is activated upon binding of polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (POPs), and related ubiquitous environmental chemicals, to mediate their biological and toxic effects. In addition, several endogenous and natural compounds can bind to AHR, thereby modulating a variety of physiological processes. In recent years, ambient particulate matter (PM) associated with traffic related air pollution (TRAP) has been found to contain significant amounts of PAHs. PM containing PAHs are of increasing concern as a class of agonists, which can activate the AHR. Several reports show that PM and AHR-mediated induction of CYP1A1 results in excessive generation of reactive oxygen species (ROS), causing oxidative stress. Furthermore, exposure to PM and PAHs induce inflammatory responses and may lead to chronic inflammatory diseases, including asthma, cardiovascular diseases, and increased cancer risk. In this review, we summarize findings showing the critical role that the AHR plays in mediating effects of environmental pollutants and stressors, which pose a risk of impacting the environment and human health.

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PAHs present on ambient air pollution particles are ligands of the cellular AHR.

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AHR-dependent induction of CYP1, AKR, NOX and COX-2 genes can be a source of ROS generation.

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AHR signaling and NRF2 signaling interact to regulate the expression of antioxidant genes.

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Air pollution and ROS can affect inflammation, which is partially triggered by AHR and associated immune responses.

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Skin, lung, and the cardiovascular system are major target sites for air pollution-induced inflammation.

Protective Effect of Diphlorethohydroxycarmalol Isolated from Ishige okamurae Against Particulate Matter-Induced Skin Damage by Regulation of NF-κB, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts

Particulate matters (PM), the main contributor to air pollution, have become a serious issue that threatens human's health. Skin is the largest organ in humans, as well as the primary organ exposed to PM. Overexposure of PM induces skin damage. Diphlorethohydroxycarmalol (DPHC), an algal polyphenol with the potential of skin protection, has been isolated from the edible brown seaweed Ishige okamurae. The purpose of the present study is to investigate the protective effect of DPHC against PM (ERM-CZ100)-induced skin damage in human dermal fibroblasts (HDF) cells. The results indicated that DPHC significantly and dose-dependently reduced intracellular reactive oxygen species generation in HDF cells. In addition, DPHC significantly induced collagen synthesis and inhibited collagenase activity in ERM-CZ100-stimulated HDF cells. Further study demonstrated that DPHC remarkably reduced the expression of human matrix metalloproteinases through regulation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases signaling pathways in ERM-CZ100-stimulated HDF cells. This study suggested that DPHC is a potential candidate to protect skins against PM-induced damage, and it could be used as an ingredient in pharmaceutical and cosmeceutical industries.

The role of reactive oxygen species in the biological activity of antimicrobial agents: An updated mini review

Antimicrobial resistance remains a serious problem that results in high mortality and increased healthcare costs globally. One of the major issues is that resistant pathogens decrease the efficacy of conventional antimicrobials. Accordingly, development of novel antimicrobial agents and therapeutic strategies is urgently needed to overcome the challenge of antimicrobial resistance. A potential strategy is to kill pathogenic microorganisms via the formation of reactive oxygen species (ROS). ROS are defined as a number of highly reactive molecules that comprise molecular oxygen (O₂), superoxide anion (O₂^•-), hydrogen peroxide (H₂O₂) and hydroxyl radicals (^•OH). ROS exhibit antimicrobial actions against a broad range of pathogens through the induction of oxidative stress, which is an imbalance between ROS and the ability of the antioxidant defence system to detoxify ROS. ROS-dependent oxidative stress can damage cellular macromolecules, including DNA, lipids and proteins. This article reviews the antimicrobial action of ROS, challenges to ROS hypothesis, work to solidify ROS-mediated antimicrobial lethality hypothesis, recent developments in antimicrobial agents using ROS as an antimicrobial strategy, safety concerns related to ROS, and future directions in ROS research.

The Antitumor Efficacy of β-Elemene by Changing Tumor Inflammatory Environment and Tumor Microenvironment

Inflammatory mediators and inflammatory cells in the inflammatory microenvironment promote the transformation of normal cells to cancer cells in the early stage of cancer, promote the growth and development of cancer cells, and induce tumor immune escape. The monomeric active ingredient β-elemene is extracted from the traditional Chinese medicine Curcuma wenyujin and has been proven to have good anti-inflammatory and antitumor activities in clinical applications for more than 20 years in China. Recent studies have found that this traditional Chinese medicine plays a vital role in macrophage infiltration and M2 polarization, as well as in regulating immune disorders, and it even regulates the transcription factors NF-κB and STAT3 to alter inflammation, tumorigenesis, and development. In addition, β-elemene regulates not only different inflammatory factors (such as TNF-α, IFN, TGF-β, and IL-6/10) but also oxidative stress in vivo and in vitro. The excellent anti-inflammatory and antitumor effects of β-elemene and its ability to alter the inflammatory microenvironment of tumors have been gradually elaborated. Although the study of monomeric active ingredients in traditional Chinese medicines is insufficient in terms of quality and quantity, the pharmacological effects of more active ingredients of traditional Chinese medicines will be revealed after β-elemene.

miR-590-3p Inhibits Pyroptosis in Diabetic Retinopathy by Targeting NLRP1 and Inactivating the NOX4 Signaling Pathway

Purpose

To elucidate the mechanism whereby miR-590-3p regulates pyroptosis in diabetic retinopathy (DR).

Methods

Human retinal microvascular endothelial cells (HRMECs) incubated with high glucose (HG) were used to establish cell models, and the expression levels of miR-590-3p, caspase-1, IL-1β, NLRP1, NOX4, TXNIP, NLRP3, and ROS were determined. Additionally, miR-590-3p was altered using a mimic or an inhibitor, and siRNAs targeting NLRP1 and NOX4 were applied to explore the regulatory mechanism of miR-590-3p in DR. The relationships between miR-590-3p and NLRP1/NOX4 also were investigated using a luciferase reporter assay. Furthermore, vitreous tissue samples were collected to confirm pyroptosis in clinical DR.

Results

Downregulated miR-590-3p and upregulated NLRP1/NOX4 levels were observed in a cell culture model of DR. Inhibiting miR-590-3p upregulated NLRP1, the NOX4/ROS/TXNIP/NLRP3 pathway, and caspase-1. NLRP1 and NOX4 were confirmed as direct target genes of miR-590-3p. The overexpression of miR-590-3p or knockdown of NLRP1 and NOX4 increased cell activity and suppressed pyroptosis. Intriguingly, the upregulation of IL-1β induced the downregulation of miR-590-3p by lowering the DNA promoter activity of pri-miR-590.

Conclusions

HG induced pyroptosis in a cell culture model of DR, and the downregulation of miR-590-3p promoted pyroptotic death by targeting NLRP1 and activating the NOX4/ROS/TXNIP/NLRP3 pathway via an IL-1β-mediated positive feedback loop.

Particulate matter-induced senescence of skin keratinocytes involves oxidative stress-dependent epigenetic modifications

Ambient air particulate matter (PM) induces senescence in human skin cells. However, the underlying mechanisms remain largely unknown. We investigated how epigenetic regulatory mechanisms participate in cellular senescence induced by PM with a diameter <2.5 (PM2.5) in human keratinocytes and mouse skin tissues. PM2.5-treated cells exhibited characteristics of cellular senescence. PM2.5 induced a decrease in DNA methyltransferase (DNMT) expression and an increase in DNA demethylase (ten-eleven translocation; TET) expression, leading to hypomethylation of the p16INK4A promoter region. In addition, PM2.5 led to a decrease in polycomb EZH2 histone methyltransferase expression, whereas the expression of the epigenetic transcriptional activator MLL1 increased. Furthermore, binding of DNMT1, DNMT3B, and EZH2 to the promoter region of p16INK4A decreased in PM2.5-treated keratinocytes, whereas TET1 and MLL1 binding increased, leading to decreased histone H3 lysine 27 trimethylation (H3K27Me3) and increased H3K4Me3 in the promoter of p16INK4A. PM2.5-induced senescence involved aryl hydrocarbon receptor (AhR)-induced reactive oxygen species (ROS) production. ROS scavenging dampened PM2.5-induced cellular senescence through regulation of DNA and histone methylation. Altogether, our work shows that skin senescence induced by environmental PM2.5 occurs through ROS-dependent the epigenetic modification of senescence-associated gene expression. Our findings provide information for the design of preventive and therapeutic strategies against skin senescence, particularly in light of the increasing problem of PM2.5 exposure due to air pollution.

Particulate Matter 2.5 Mediates Cutaneous Cellular Injury by Inducing Mitochondria-Associated Endoplasmic Reticulum Stress: Protective Effects of Ginsenoside Rb1

The prevalence of fine particulate matter-induced harm to the human body is increasing daily. The aim of this study was to elucidate the mechanism by which particulate matter 2.5 (PM_2.5) induces damage in human HaCaT keratinocytes and normal human dermal fibroblasts, and to evaluate the preventive capacity of the ginsenoside Rb1. PM_2.5 induced oxidative stress by increasing the production of reactive oxygen species, leading to DNA damage, lipid peroxidation, and protein carbonylation; this effect was inhibited by ginsenoside Rb1. Through gene silencing of endoplasmic reticulum (ER) stress-related genes such as PERK, IRE1, ATF, and CHOP, and through the use of the ER stress inhibitor tauroursodeoxycholic acid (TUDCA), it was demonstrated that PM_2.5-induced ER stress also causes apoptosis and ultimately leads to cell death; however, this phenomenon was reversed by ginsenoside Rb1. We also found that TUDCA partially restored the production of ATP that was inhibited by PM_2.5, and its recovery ability was significantly higher than that of ginsenoside Rb1, indicating that the process of ER stress leading to cell damage may also occur via the mitochondrial pathway. We concluded that ER stress acts alone or via the mitochondrial pathway in the induction of cell damage by PM_2.5, and that ginsenoside Rb1 blocks this process. Ginsenoside Rb1 shows potential for use in skin care products to protect the skin against damage by fine particles.

Can Plant Phenolic Compounds Protect the Skin from Airborne Particulate Matter?

The skin is directly exposed to the polluted atmospheric environment, and skin diseases, such as atopic dermatitis and acne vulgaris, can be induced or exacerbated by airborne particulate matter (PM). PM can also promote premature skin aging with its accompanying functional and morphological changes. PM-induced skin diseases and premature skin aging are largely mediated by reactive oxygen species (ROS), and the harmful effects of PM may be ameliorated by safe and effective natural antioxidants. Experimental studies have shown that the extracts and phenolic compounds derived from many plants, such as cocoa, green tea, grape, pomegranate, and some marine algae, have antioxidant and anti-inflammatory effects on PM-exposed cells. The phenolic compounds can decrease the levels of ROS in cells and/or enhance cellular antioxidant capacity and, thereby, can attenuate PM-induced oxidative damage to nucleic acids, proteins, and lipids. They also lower the levels of cytokines, chemokines, cell adhesion molecules, prostaglandins, and matrix metalloproteinases implicated in cellular inflammatory responses to PM. Although there is still much research to be done, current studies in this field suggest that plant-derived phenolic compounds may have a protective effect on skin exposed to high levels of air pollution.

Environmental Stressors on Skin Aging. Mechanistic Insights

The skin is the main barrier that protects us against environmental stressors (physical, chemical, and biological). These stressors, combined with internal factors, are responsible for cutaneous aging. Furthermore, they negatively affect the skin and increase the risk of cutaneous diseases, particularly skin cancer. This review addresses the impact of environmental stressors on skin aging, especially those related to general and specific external factors (lifestyle, occupation, pollutants, and light exposure). More specifically, we have evaluated ambient air pollution, household air pollutants from non-combustion sources, and exposure to light (ultraviolet radiation and blue and red light). We approach the molecular pathways involved in skin aging and pathology as a result of exposure to these external environmental stressors. Finally, we reflect on how components of environmental stress can interact with ultraviolet radiation to cause cell damage and the critical importance of knowing the mechanisms to develop new therapies to maintain the skin without damage in old age and to repair its diseases.

Morin Protects Human Respiratory Cells from PM2.5 Induced Genotoxicity by Mitigating ROS and Reverting Altered miRNA Expression

Chronic fine particulate matter (PM2.5) exposure causes oxidative stress and leads to many diseases in human like respiratory and cardiovascular disorders, and lung cancer. It is known that toxic responses elicited by PM2.5 particles depend on its physical and chemical characteristics that are greatly influenced by the source. Dietary polyphenolic compounds that possess antioxidant and free radical scavenging properties could be used for therapeutic or preventive approaches against air pollution related health hazards. This study evaluates characteristics and toxicity of PM2.5 collected from rural, urban, industrial, and traffic regions in and around Coimbatore City, Tamilnadu, India. Traffic PM2.5 particles contained higher amounts of metals and polycyclic aromatic hydrocarbons (PAHs). It also possessed higher levels of oxidative potential, induced more intracellular reactive oxygen species (ROS), and caused more levels of cell death and DNA damage in human respiratory cells. Its exposure up regulated DNA damage response related miR222, miR210, miR101, miR34a, and miR93 and MycN and suppressed Rad52. Pre-treatment with morin significantly decreased the PM2.5 induced toxicity and conferred protection against PM2.5 induced altered miRNA expression. Results of this study showed that cytoprotective effect of morin is due to its antioxidative and free radical scavenging activity.

Niacinamide Protects Skin Cells from Oxidative Stress Induced by Particulate Matter

Niacinamide (NIA) is a water-soluble vitamin that is widely used in the treatment of skin diseases. Moreover, NIA displays antioxidant effects and helps repair damaged DNA. Recent studies showed that particulate matter 2.5 (PM_2.5) induced reactive oxygen species (ROS), causing disruption of DNA, lipids, and protein, mitochondrial depolarization, and apoptosis of skin keratinocytes. Here, we investigated the protective effects of NIA on PM_2.5-induced oxidative stress in human HaCaT keratinocytes. We found that NIA could inhibit the ROS generation induced by PM_2.5, as well block the PM_2.5-induced oxidation of molecules, such as lipids, proteins, and DNA. Furthermore, NIA alleviated PM_2.5-induced accumulation of cellular Ca²⁺, which caused cell membrane depolarization and apoptosis, and reduced the number of apoptotic cells. Collectively, the findings show that NIA can protect keratinocytes from PM_2.5-induced oxidative stress and cell damage.

Establishing of mouse oral carcinoma cell lines derived from transgenic mice and their use as syngeneic tumorigenesis models

Background

The survival of OSCC patient needs to be further improved. miR-211 is oncogenic in OSCC and its upregulation is associated with tumor progression and poor patient survival. K14-EGFP-miR-211 transgenic mice also exhibit augmented potential for OSCC induction.

Methods

Four murine OSCC cell lines, designated MOC-L1 to MOC-L4, are established from tongue tumors induced by 4-nitroquinoline 1-oxide using the K14-EGFP-miR-211 transgenic mouse model. The genetic disruption, in vitro oncogenicity, and the eligibilities of tumorigenesis and metastasis of the cell lines are analyzed.

Results

All cell lines show green fluorescence and express a range of epithelial markers. The MOC-L1, MOC-L2 and MOC-L3 cells carry missense mutations in the DNA binding domain of the p53 gene. MOC-L1 exhibits a high level of epithelial-mesenchymal transition and has the aggressive characteristics associated with this. MOC-L1 and MOC-L2 are clonogenic in vitro as well as being tumorigenic when implanted into the dermis or tongue of syngeneic recipients. Nonetheless, only MOC-L1 exhibits immense potential for local regional and distal metastasis. Since the expression of miR-196b in MOC-L1 xenografts is drastically decreased on cisplatin treatment, it would seem that targeting of miR-196b might facilitate tumor abrogation.

Conclusions

As cell lines established in this study originated from the C57BL/6 mouse, the strain most suitable for transgenic engineering, exploring the interplay of these OSCC cells with other genetically modified cells in immune-competent mice would provide important insights into OSCC pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5486-7) contains supplementary material, which is available to authorized users.

Autism genes and the leukocyte transcriptome in autistic toddlers relate to pathogen interactomes, infection and the immune system. A role for excess neurotrophic sAPPα and reduced antimicrobial Aβ

Prenatal and early childhood infections have been implicated in autism. Many autism susceptibility genes (206 Autworks genes) are localised in the immune system and are related to immune/infection pathways. They are enriched in the host/pathogen interactomes of 18 separate microbes (bacteria/viruses and fungi) and to the genes regulated by bacterial toxins, mycotoxins and Toll-like receptor ligands. This enrichment was also observed for misregulated genes from a microarray study of leukocytes from autistic toddlers. The upregulated genes from this leukocyte study also matched the expression profiles in response to numerous infectious agents from the Broad Institute molecular signatures database. They also matched genes related to sudden infant death syndrome and autism comorbid conditions (autoimmune disease, systemic lupus erythematosus, diabetes, epilepsy and cardiomyopathy) as well as to estrogen and thyrotropin responses and to those upregulated by different types of stressors including oxidative stress, hypoxia, endoplasmic reticulum stress, ultraviolet radiation or 2,4-dinitrofluorobenzene, a hapten used to develop allergic skin reactions in animal models. The oxidative/integrated stress response is also upregulated in the autism brain and may contribute to myelination problems. There was also a marked similarity between the expression signatures of autism and Alzheimer's disease, and 44 shared autism/Alzheimer's disease genes are almost exclusively expressed in the blood-brain barrier. However, in contrast to Alzheimer's disease, levels of the antimicrobial peptide beta-amyloid are decreased and the levels of the neurotrophic/myelinotrophic soluble APP alpha are increased in autism, together with an increased activity of α-secretase. sAPPα induces an increase in glutamatergic and a decrease in GABA-ergic synapses creating and excitatory/inhibitory imbalance that has also been observed in autism. A literature survey showed that multiple autism genes converge on APP processing and that many are able to increase sAPPalpha at the expense of beta-amyloid production. A genetically programmed tilt of this axis towards an overproduction of neurotrophic/gliotrophic sAPPalpha and underproduction of antimicrobial beta-amyloid may explain the brain overgrowth and myelination dysfunction, as well as the involvement of pathogens in autism.

Participation of NADPH Oxidase-Related Reactive Oxygen Species in Leptin-Promoted Pulmonary Inflammation: Regulation of cPLA2α and COX-2 Expression

Obesity is a worldwide epidemic problem and correlates to varieties of acute or chronic lung diseases such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis. An increase of leptin, a kind of adipokine, in lean mice plasma has been found to impair immune responses and facilitate the infection of Klebsiella pneumoniae, resulting in increased pneumonia severity. Also, a higher leptin level is found in exhaled breath condensates of obese or asthmatic subjects, compared to healthy ones, suggesting that leptin is involved in the occurrence or exacerbation of lung injury. In previous studies, we showed that leptin stimulated cytosolic phospholipase A2-α (cPLA2α) gene expression in lung alveolar type II cells via mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB)-activated coactivator p300. Herein, we show that the in vivo application of leptin in the respiratory system upregulated the expression of inflammatory proteins cPLA2α and cyclooxygenase-2 (COX-2) together with leukocyte infiltration. Treatment with an ROS scavenger (N-acetylcysteine, NAC), an NADPH oxidase inhibitor (apocynin), or an activating protein (AP)-1 inhibitor (tanshinone IIA) attenuated leptin-mediated cPLA2α/COX-2 expression and leukocyte recruitment in the lung. Leptin increased intracellular oxidative stress in a leptin receptor (OB-R) and NADPH oxidase-dependent manner, leading to the phosphorylation of the AP-1 subunit c-Jun. In summation, leptin increased lung cPLA2α/COX-2 expression and leukocyte recruitment via the NADPH oxidase/ROS/AP-1 pathway. Understanding the inflammatory effects of leptin on the pulmonary system provides opportunities to develop strategies against lung injury related to metabolic syndrome or obesity.