Mechanisms of Resorcinol Antagonism of Benzo[a]pyrene-Induced Damage to Human Keratinocytes

Anti-pollutant effect of oleic acid against urban particulate matter is mediated via regulation of AhR- and TRPV1-mediated signaling in vitro

Urban Particulate Matter (UPM) induces skin aging and inflammatory responses by regulating skin cells through the transient receptor potential vanilloid 1 (TRPV1). Although oleic acid, an unsaturated free fatty acid (FFA), has some functional activities, its effect on UPM-induced skin damage has not been elucidated. Here, we investigated signaling pathways on how oleic acid is involved in attenuating UPM induced cell damage. UPM treatment increased XRE-promoter luciferase activity and increased translocation of AhR to the nucleus, resulting in the upregulation of CYP1A1 gene. However, oleic acid treatment attenuated the UPM effects on AhR signaling. Furthermore, while UPM induced activation of TRPV1 and MAPKs signaling which activated the downstream molecules NFκB and AP-1, these effects were reduced by cotreatment with oleic acid. UPM-dependent generation of reactive oxygen species (ROS) and reduction of cellular proliferation were also attenuated by the treatment of oleic acid. These data reveal that cell damage induced by UPM treatment occurs through AhR signaling and TRPV1 activation which in turn activates ERK and JNK, ultimately inducing NFκB and AP-1 activation. These effects were reduced by the cotreatment of oleic acid on HaCaT cells. These suggest that oleic acid reduces UPM-induced cell damage through inhibiting both the AhR signaling and activation of TRPV1 and its downstream molecules, leading to a reduction of pro-inflammatory cytokine and recovery of cell proliferation.

Aquaporin-3 Downregulation in Vitiligo Keratinocytes Increases Oxidative Stress of Melanocytes

Oxidative stress-induced melanocyte apoptosis is linked to the immune system and plays a critical role in the pathogenesis of vitiligo. Aquaporin-3 (AQP3), which is downregulated in vitiligo keratinocytes, regulates intracellular H2O2 accumulation. However, the role of AQP3 in oxidative stress is uncertain in vitiligo. This study investigated the effect of downregulated AQP3 on oxidative stress in vitiligo using lesional and non-lesional skin specimen sets from vitiligo patients and primary cultured adult normal human epidermal keratinocytes, with or without downregulation and overexpression of AQP3 in the presence or absence of H2O2 treatment. The levels of nuclear factor E2-related factor 2 (NRF2) and/or its main target, NAD(P)H quinone dehydrogenase 1 (NQO-1), were lower in the lesional keratinocytes and cultured keratinocytes with AQP3 knockdown, but were increased in keratinocytes upon AQP3 overexpression. Ratios of NRF2 nuclear translocation and NQO-1 expression levels were further reduced in AQP3-knockdown keratinocytes following H2O2 treatment. The conditioned media from AQP3-knockdown keratinocytes treated with H2O2 contained higher concentrations of reactive oxygen species (ROS). Moreover, the number of viable melanocytes was reduced when the conditioned media were added to the culture media. Overall, AQP3 downregulation in the keratinocytes of patients with vitiligo can induce oxidative stress in neighboring melanocytes, leading to melanocyte death.

Dynamic changes of DNA methylation induced by benzo(a)pyrene in cancer

Benzo(a)pyrene (BaP), the earliest and most significant carcinogen among polycyclic aromatic hydrocarbons (PAHs), has been found in foods, tobacco smoke, and automobiles exhaust, etc. Exposure to BaP induced DNA damage directly, or oxidative stress-related damage, resulting in cell apoptosis and carcinogenesis in human respiratory system, digestive system, reproductive system, etc. Moreover, BaP triggered genome-wide epigenetic alterations by methylation, which might cause disturbances in regulation of gene expression, and thereby induced cancer. It has been proved that BaP reduced genome-wide DNA methylation, and activated proto-oncogene by hypomethylation in the promoter region, but silenced tumor suppressor genes by promoter hypermethylation, resulting in cancer initiation and progression. Here we summarized the changes in DNA methylation in BaP exposure, and revealed the methylation of DNA plays a role in cancer development.

Targeting the aryl hydrocarbon receptor by gut phenolic metabolites: A strategy towards gut inflammation

The Aryl Hydrocarbon Receptor (AHR) is a ligand-dependent transcription factor able to control complex transcriptional processes in several cell types, which has been correlated with various diseases, including inflammatory bowel diseases (IBD). Numerous studies have described different compounds as ligands of this receptor, like xenobiotics, natural compounds, and several host-derived metabolites. Dietary (poly)phenols have been studied regarding their pleiotropic activities (e.g., neuroprotective and anti-inflammatory), but their AHR modulatory capabilities have also been considered. However, dietary (poly)phenols are submitted to extensive metabolism in the gut (e.g., gut microbiota). Thus, the resulting gut phenolic metabolites could be key players modulating AHR since they are the ones that reach the cells and may exert effects on the AHR throughout the gut and other organs. This review aims at a comprehensive search for the most abundant gut phenolic metabolites detected and quantified in humans to understand how many have been described as AHR modulators and what could be their impact on inflammatory gut processes. Even though several phenolic compounds have been studied regarding their anti-inflammatory capacities, only 1 gut phenolic metabolite, described as AHR modulator, has been evaluated on intestinal inflammatory models. Searching for AHR ligands could be a novel strategy against IBD.

Biosynthetic Gene Clusters from Swine Gut Microbiome

The abuse of antibiotics has become a serious health challenge in the veterinary field. It creates environmental selection pressure on bacteria and facilitates the rapid spread of antibiotic resistance genes. The speed of discovery and application of cost-effective alternatives to antibiotics is slow in pig production. Natural products from biosynthetic gene clusters (BGCs) represent promising therapeutic agents for animal and human health and have attracted extraordinary passion from researchers due to their ability to participate in biofilm inhibition, stress resistance, and the killing of competitors. In this study, we detected the presence of diverse secondary metabolite genes in porcine intestines through sequence alignment in the antiSMASH database. After comparing variations in microbial BGCs' composition between the ileum and the colon, it was found that the abundance of the resorcinol gene cluster was elevated in the ileal microbiome, whereas the gene cluster of arylpolyene was enriched in the colonic microbiome. The investigation of BGCs' diversity and composition differences between the ileal and colonic microbiomes provided novel insights into further utilizing BGCs in livestock. The importance of BGCs in gut microbiota deserves more attention for promoting healthy swine production.

Hydrothermally Grown MoS2 as an Efficient Electrode Material for the Fabrication of a Resorcinol Sensor

Recently, the active surface modification of glassy carbon electrodes (GCE) has received much attention for the development of electrochemical sensors. Nanomaterials are widely explored as surface-modifying materials. Herein, we have reported the hydrothermal synthesis of molybdenum disulfide (MoS₂) and its electro-catalytic properties for the fabrication of a resorcinol sensor. Structural properties such as surface morphology of the prepared MoS₂ was investigated by scanning electron microscopy and phase purity was examined by employing the powder X-ray diffraction technique. The presence of Mo and S elements in the obtained MoS₂ was confirmed by energy-dispersive X-ray spectroscopy. Finally, the active surface of the glassy carbon electrode was modified with MoS₂. This MoS₂-modified glassy carbon electrode (MGC) was explored as a potential candidate for the determination of resorcinol. The fabricated MGC showed a good sensitivity of 0.79 µA/µMcm² and a detection limit of 1.13 µM for the determination of resorcinol. This fabricated MGC also demonstrated good selectivity, and stability towards the detection of resorcinol.

Anti-Pollution Activity, Antioxidant and Anti-Inflammatory Effects of Fermented Extract from Smilax china Leaf in Macrophages and Keratinocytes

Air pollution has considerable effects on the human skin, showing that every single pollutant has a different toxicological impact on it. The oxidative stress that exceeds the skin’s antioxidant capacity can lead to oxidative damage and premature skin aging by repeated air pollutant contact. In this study, according to the generalized protocol available to objectively substantiate the ‘anti-pollution’ claim, we evaluated several biomarkers after pollutants exposure in Raw 264.7 macro-phages and HaCaT keratinocytes to investigate the possibility of anti-pollution cosmetic material of fermented extract from Smilax china leaves (FESCL). FESCL decreased pollutants-induced luciferase activity in a dose-dependent manner, and FESCL significantly inhibited XRE-luciferase activity at a concentration of 1%. The IC50 value of FESCL showed the same DPPH scavenging activity at 0.0625% as ascorbic acid, and the maximum DPPH scavenging activity (92.44%) at 1%. The maximum permissible non-cytotoxic concentrations of FESCL for a Raw 264.7 cell was determined to be 2%, where PGE2 production of FESCL was inhibited by 78.20%. These results show the anti-pollution activity of FESCL against the pollutant-stimulated human living skin explants. In conclusion, we confirmed the anti-pollution potential of FESCL as one of the functional materials in cosmetic formulation.

Antioxidant Activities and Mechanisms of Tomentosin in Human Keratinocytes

Tomentosin, one of natural sesquiterpene lactones sourced from Inula viscosa L., exerts therapeutic effects in various cell types. Here, we investigated the antioxidant activities and the underlying action mechanisms of tomentosin in HaCaT cells (a human keratinocyte cell line). Specifically, we examined the involvement of tomentosin in aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways. Treatment with tomentosin for up to 60 min triggered the production of reactive oxygen species (ROS), whereas treatment for 4 h or longer decreased ROS production. Tomentosin treatment also induced the nuclear translocation of Nrf2 and upregulated the expression of Nrf2 and its target genes. These data indicate that tomentosin induces ROS production at an early stage which activates the Nrf2 pathway by disrupting the Nrf2–Keap1 complex. However, at a later stage, ROS levels were reduced by tomentosin-induced upregulation of antioxidant genes. In addition, tomentosin induced the phosphorylation of mitogen-activated protein kinases (MAPKs) including p38 MAPK and c-Jun N-terminal kinase (JNK). SB203580 (a p38 MAPK inhibitor) and SP600125 (a JNK inhibitor) attenuated the tomentosin-induced phosphorylation of Nrf2, suggesting that JNK and p38 MAPK signaling pathways can contribute to the tomentosin-induced Nrf2 activation through phosphorylation of Nrf2. Furthermore, N-acetyl-_L-cysteine (NAC) treatment blocked both tomentosin-induced production of ROS and the nuclear translocation of Nrf2. These data suggest that tomentosin-induced Nrf2 signaling is mediated both by tomentosin-induced ROS production and the activation of p38 MAPK and JNK. Moreover, tomentosin inhibited the AhR signaling pathway, as evidenced by the suppression of xenobiotic-response element (XRE) reporter activity and the translocation of AhR into nucleus induced by urban pollutants, especially benzo[a]pyrene. These findings suggest that tomentosin can ameliorate skin damage induced by environmental pollutants.