UVB-induced Apoptosis Research Articles

Butin Protects Keratinocytes From Particulate Matter 2.5 and Ultraviolet B-Mediated Damages.

Butin is a naturally occurring compound with a wide range of medicinal properties, including anti-inflammatory, anti-arthritic, and antioxidant properties. Particulate matter 2.5 (PM2.5) and ultraviolet B (UVB) radiation contribute to skin cell damage via the induction of oxidative stress. This study sought to assess the protective effects of butin against damage triggered by PM2.5 and UVB in human HaCaT keratinocytes. Assessments were performed to evaluate cell viability, apoptosis, and cellular component damage. Butin exhibited its protective ability via the inhibition of PM2.5-induced reactive oxygen species generation, lipid peroxidation, DNA damage, protein carbonylation, and mitochondrial damage. Butin reduced the PM2.5-induced c-Fos and phospho-c-Jun protein levels as well as mitogen-activated protein kinase. Furthermore, butin mitigated PM2.5- and UVB-induced apoptosis. Butin had the potential as a pharmaceutical candidate for treating skin damage caused by PM2.5 and UVB exposure.

FUNDC1-mediated mitophagy regulates photodamage independently of the PINK1/Parkin-dependent pathway

BackgroundUltraviolet B(UVB) triggers a pro-survival response through mitophagy, but the role of FUNDC1-mediated mitophagy in photodamaged skin remains unexplored. ObjectivesTo clarify the function of mitophagy in UVB-induced photodamaged skin. MethodsTo investigate the role of FUNDC1-mediated mitophagy in UVB-induced mitochondrial damage and cell apoptosis, FUNDC1 knockdown in C57BL/6 mice was performed using adeno-associated virus. Additionally, FUNDC1 overexpression and knockdown in HaCaT cells were conducted using lentivirus. A comprehensive analysis was conducted on a panel of human sun-exposed skin samples, alongside control samples, to assess the expression levels of FUNDC1. ResultsIn UVB-induced C57BL/6 mice, the dorsal skin showed photodamage including erythema, scaling, erosion, and scabs. The expression levels of PINK1, Parkin, and BNIP3 did not show significant changes, while FUNDC1 expression consistently declined along with LC3B. Cytochrome C, Bax, and cleaved-caspase3 were upregulated, while Bcl2 was downregulated. UVB-induced HaCaT cells showed mitochondrial damage, accompanied by FUNDC1 downregulation and BNIP3 upregulation, while PINK1 and Parkin showed no significant changes. FUNDC1 overexpression led to an increase in mtROS and a decrease in mitochondrial membrane potential and ATP levels, indicating complete mitochondrial clearance and exacerbated cell death. FUNDC1 knockdown protected against UVB-induced photodamage in mice and mitigated mitochondrial damage and apoptosis in HaCaT cells by activating compensatory PINK1/Parkin-dependent mitophagy, which was evidenced by upregulation of PINK1 and Bcl2 and downregulation of Bax. In human sun-exposed skin samples, there was a decrease in the number of FUNDC1+ cells compared with non-sun-exposed controls. ConclusionsFUNDC1-mediated mitophagy regulates skin photodamage and provides a novel mechanism for resisting photodamage, presenting a potential target for future therapeutic interventions.

Enhancing ocular protection against UVB: The role of irigenin in modulating oxidative stress and apoptotic pathways In Vivo

Oxidative damage contributes to age-related macular degeneration. Irigenin possesses diverse pharmacologic properties, including antioxidative and antiapoptotic effects. Our in vivo experiments indicated that irigenin mitigates UVB-induced histopathologic changes and oxidative DNA damage. Histologic analyses and TUNEL staining revealed that this compound dose-dependently ameliorated UVB-induced retinal damage and apoptosis. Furthermore, irigenin substantially reduced the level of 8-hydroxyguanosine, a biomarker of UVB-induced oxidative DNA damage. We further explored the molecular mechanisms that mediate the protective effects of irigenin. Our findings suggested that UVB-induced generation of ROS disrupts the stability of the mitochondrial membrane, activating intrinsic apoptotic pathways; the underlying mechanisms include the release of cytochrome c, activation of caspase-9 and caspase-3, and subsequent degradation of PARP-1. Notably, irigenin reversed mitochondrial disruption and apoptosis. It also modulated the Bax and Bcl-2 expression but influenced the mitochondrial apoptotic pathways. Our study highlights the role of the Nrf2 pathway in mitigating the effects of oxidative stress. We found that UVB exposure downregulated, but irigenin treatment upregulated the expression of Nrf2 and antioxidant enzymes. Therefore, irigenin activates the Nrf2 pathway to address oxidative stress. In conclusion, irigenin exhibits protective effects against UVB-induced ocular damage, evidenced by the diminution of histological alterations. It mitigates oxidative DNA damage and apoptosis in the retinal tissues by modulating the intrinsic apoptotic pathways and the AIF mechanisms. Furthermore, irigenin effectively reduces lipid peroxidation, enhancing the activity of antioxidant enzymes by stimulating the Nrf2 pathway. This protective mechanism underscores the potential benefit of irigenin in combating UVB-mediated ocular damage.

The protective effect of Artemisia Capillaris Thunb. Extract against UVB-induced apoptosis and inflammation through inhibiting the cGAS/STING pathway

Exposure to ultraviolet B (UVB) radiation represents a significant environmental threat to human skin. This study investigates the protective mechanism of Artemisia Capillaris Thunb. (AC) extract against UVB-induced apoptosis and inflammation in HaCaT keratinocytes. AC extract demonstrated a significant protective effect, as evidenced by reduced early apoptosis, late apoptosis, and necrosis, as well as decreased apoptotic cell status upon UVB exposure. Additionally, AC extract effectively inhibited UVB-induced DNA damage, as indicated by diminished γ-H2AX foci formation. Restoration of mitochondrial damage and normalization of mitochondrial membrane potential, along with the reduction of intracellular and mitochondrial reactive oxygen species (ROS) levels, were observed with AC extract pre-treatment. The extract also exhibited anti-inflammatory properties, evidenced by the decreased release of IL-1α, IL-6, and PGE2 from keratinocytes. Additional research on the molecular mechanisms uncovered that the AC extract alters the cGAS/STING pathway, suppressing the mRNA (cGAS, STING, IRF3, IRF7 and TBK1) and protein levels (cGAS, STING, IRF3, IRF7 and NF-κB) linked to this particular pathway. The HPLC analysis identified chlorogenic acid and its derivatives as the major components in AC, constituting up to 16.44% of the total chlorogenic acid content. The cGAS/STING signaling pathway was found to be suppressed by chlorogenic acid and its derivatives, as indicated by molecular docking studies and RT-qPCR analysis. This suppression contributes to the protective effects against cell apoptosis and inflammation induced by UVB. To summarize, AC extract, which is abundant in chlorogenic acid and its derivatives, shows potential in protecting keratinocytes from damage caused by UVB by regulating the cGAS/STING signaling pathway.

MLKL, a new actor of UVB-induced apoptosis in human diploid dermal fibroblasts

Ultraviolet radiation (UVR) is a major environmental mutagen. In skin, UVR can initiate cancer through the induction of mutagenic DNA damage and promote its progression. An important cancer prevention mechanism is the regulated cell death (RCD), which can safely dispose of damaged cells. Apoptosis, a well-known RCD, is known to be activated by UVR, but part of the mechanism and proteins involved in UVR-induced apoptosis are still to be discovered. Receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL) are two proteins involved in necroptosis, a form of RCD. Here, we have evaluated the implication of RIPK3 and MLKL in UVB-induced cell death in human diploid dermal fibroblasts. Our results show that RIPK3 and MLKL play opposite roles in UVB-induced cell death, in a necroptosis independent pathway. We showed that RIPK3 protects cells from UVB cell death, while MLKL sensitizes cells to UVB-induced apoptosis. Taken together these results are the first to show the implication of RIPK3 and MLKL in survival and apoptosis, respectively, bringing two new actors in UVB-induced cell death pathway.

Protective autophagy enhances antistress ability through AMPK/ULK1 signaling pathway in human immortalized keratinocytes.

Keratinocytes, located in the outermost layer of human skin, are pivotal cells to resist environmental damage. Cellular autophagy plays a critical role in eliminating damaged organelles and maintaining skin cell homeostasis. Low-dose 5-Aminolevulinic acid photodynamic therapy (ALA-PDT) has been demonstrated to enhance skin's antistress ability; however, the regulatory mechanisms of autophagy in keratinocytes remain unclear. In this study, we treated immortalized human keratinocytes (HaCaT cells) with low-dose ALA-PDT (0.5 mmol/L, 3 J/cm2). Through RNA-sequencinganalysis, we identified that low-dose ALA-PDT modulated autophagy-related pathways in keratinocytes and pinpointed Unc-51-like kinase 1 (ULK1) as a key gene involved. Western blot results revealed that low-dose ALA-PDT treatment upregulated the expression of autophagy-related proteins Beclin-1 and LC3-II/LC3-I ratio. Notably, low-dose ALA-PDT regulated autophagy by inducing an appropriate level of reactive oxygen species (ROS), transiently reducing mitochondrial membrane potential,and decreasing adenosine triphosphate production; all these processes functioned on the AMP-activated protein kinase (AMPK)/ULK1 pathway to activate autophagy. Finally, we simulated external environmental damage using ultraviolet B (UVB) at a dose of 60 mJ/cm2 and observed that low-dose ALA-PDT mitigated UVB-induced cell apoptosis; however, this protective effect was reversed when using the autophagy inhibitor 3-methyladenine. Overall, these findings highlight how low-dose ALA-PDT enhances antistress ability in HaCaT cells through controlling ROS generation and activating the AMPK/ULK1 pathway to arouse cellular autophagy.

Rapamycin protects mouse skin from ultraviolet B-induced photodamage by modulating Hspb2-mediated autophagy and apoptosis.

Continuous exposure to UVB is the main extrinsic cause of skin photodamage, which is associated with oxidative stress, DNA damage, apoptosis and degradation of collagen. Rapamycin, a mechanistic target inhibitor of rapamycin complex 1 (mTORC1), has been shown to play a crucial role anti-tumor and aging retardation, but its mechanism of action in UVB-induced photodamage still remains unknown. In this study, we investigated the role of rapamycin and Hspb2 (also known as Hsp27) in UVB-induced photodamage in mice. We constructed skin acute photodamage models on the ears of WT and Hspb2 KO mice, respectively, and administered rapamycin treatment. Histological results showed that knockout of the hspb2 exacerbated the skin damage, as evidenced by thickening of the epidermis, breakage and disruption of collagen fibers and reduction in their number, which is reversed by rapamycin treatment. In addition, hspb2 knockout promoted UVB-induced apoptosis and reduced autophagy levels, with a significant increase in p53 levels and Bax/Bcl-2 ratio, a reduction in LC3II/I ratio and an increase in p62 levels in the KO mice compared to those in WT mice after the same dose of UVB irradiation. Rapamycin was also found to inhibit collagen degradation induced by hspb2 knockdown through activation of the TGF-β/Smad signaling pathway. Rapamycin can alleviate skin photodamage from Hspb2 knockout to some extent. It may be a potential therapeutic drug for skin photodamage. In this study, we investigated the role of rapamycin and Hspb2 in UVB-induced photodamage in mice. Histological results showed that knockout of the hspb2 exacerbated the skin damage, as evidenced by thickening of the epidermis, breakage and disruption of collagen fibers and reduction in their number, which is reversed by rapamycin treatment. In addition, hspb2 knockout promoted UVB-induced apoptosis and reduced autophagy levels. Rapamycin was also found to inhibit collagen degradation induced by hspb2 knockdown through activation of the TGF-β/Smad signaling pathway. We conclude that rapamycin and Hspb2 exert a synergistic protective effect in skin photodamage.

Rg3-loaded P407/CS/HA hydrogel inhibits UVB-induced oxidative stress, inflammation and apoptosis in HaCaT cells

UVB radiation can damage human skin, whereas Ginsenoside Rg3, the active ingredient in red ginseng that is processed from ginseng (Panax ginseng C.A. Meyer), could inhibit UVB induced cell damage through anti-oxidation. Meanwhile, P407/CS/HA hydrogel has significant biomedical applications as carriers of drugs. However, the beneficial effects of Rg3-loaded hydrogel (Rg3-Gel) on human HaCaT keratinocytes induced by UVB have rarely been reported. In our study, Rg3 was loaded into hydrogel and the effect of Rg3-Gel against UVB‑induced Hacat cells damages was determined by measuring its ability to alleviate UVB‑induced elevation of oxidative stress, pro-inflammatory and apoptotic response. We found that the treatment with Rg3-Gel inhibited the generation of intracellular ROS and MDA and upregulated the expression of antioxidant enzymes SOD and GSH-Px which were inhibited by UVB exposure. Increased levels of pro-inflammatory cytokines TNF‑α, COX‑2, iNOS and IL‑1β following UVB irradiation were suppressed by the introduction of Rg3-Gel. Additionally, the level of Bcl-2 was decreased and the expression of Bax and Caspase3 were enhanced by Rg3-Gel treatment. In conclusion, Rg3-Gel equipped with the synergistic effect of Rg3 and hydrogel has an effective inhibitory effect on UVB-induced oxidative stress, inflammatory and apoptosis.

The Mechanism of Peach Gum Polysaccharide Preventing UVB-Induced Skin Photoaging by Regulating Matrix Metalloproteinanse and Oxidative Factors.

Exposure to ultraviolet light can cause oxidative damage and accelerate skin aging and is one of the main causes of skin aging. Peach gum polysaccharide (PG) is a natural edible plant component that has many biological activities, such as regulating blood glucose and blood lipids and improving colitis, as well as antioxidant and anticancer properties. However, there are few reports on the antiphotoaging effect of peach gum polysaccharide. Therefore, in this paper, we study the basic composition of the raw material peach gum polysaccharide and its ability to improve UVB-induced skin photoaging damage in vivo and in vitro. The results show that peach gum polysaccharide is mainly composed of mannose, glucuronic acid, galactose, xylose, and arabinose, and its molecular weight (Mw) is 4.10 × 106 g/mol. The results of the in vitro cell experiments show that PG could significantly alleviate UVB-induced apoptosis of human skin keratinocytes, promote cell growth repair, reduce the expression of intracellular oxidative factors and matrix metal collagenase, and improve the extent of oxidative stress repair. Moreover, the results from the in vivo animal experiments showed that PG could not only effectively improve the phenotype of UVB-induced photoaged skin in model mice but also significantly improve their oxidative stress status, regulate the contents of ROS and the levels of SOD and CAT, and repair the oxidative skin damage induced by UVB in vivo. In addition, PG improved UVB-induced photoaging-mediated collagen degradation in mice by inhibiting the secretion of matrix metalloproteinases. The above results indicate that peach gum polysaccharide has the ability to repair UVB-induced photoaging and may be used as a potential drug and antioxidant functional food to resist photoaging in the future.

Characterization and screening of anti-melanogenesis and anti-photoaging activity of different enzyme-assisted polysaccharide extracts from Portulaca oleracea L.

BackgroundThe flavonoids and polysaccharides in Portulaca oleracea L. (PO) have significant antibacterial and antioxidant effects, which can inhibit common bacteria and remove free radicals in the body. However, there was little research on the use of PO to alleviate hyperpigmentation and photoaging damage. PurposeThis study was to investigate the anti-photoaging and whitening activity mechanism of polysaccharide of PO (POP) in vitro and in vivo. MethodIn this study, 16 fractions obtained by four enzyme-assisted extraction from PO and their scavenging capabilities against 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals were evaluated. Among these fractions, a polysaccharide fraction (VPOP3) showed the strongest biological activity. VPOP3 was characterized by Fourier-transform infrared spectroscopy, molecular weight (MW), and monosaccharide composition analysis, and the protective effect of VPOP3 on photoaging and hyperpigmentation was researched. ResultsVPOP3 is a low-MW acidic heteropolysaccharide with MW mainly distributed around 0.71KDa, arabinose as its main monosaccharide component. VPOP3 reliably reduced the reactive oxygen species levels in cells and zebrafish and the level of lipid peroxidation in zebrafish. In addition, VPOP3 inhibited UVB-induced apoptotic body formation and apoptosis by downregulating caspase-3 and Bax and upregulating Bcl-2 in mitochondrion-mediated signaling pathways. On the other hand, VPOP3 at high concentrations significantly downregulated the expression of microphthalmia-associated transcription factor, tyrosinase (TYR), and TYR-related protein-1 and TYR-related protein-2 in the melanogenic signaling pathway to achieve a whitening effect. ConclusionThe above results showed that VPOP3 has superior activities of anti-photoaging and anti-melanogenesis and can be utilized as a safe resource in the manufacture of cosmetics.

Regulation of Photosensitivity by the Hippo Pathway in Lupus Skin.

Photosensitivity is one of the most common manifestations of systemic lupus erythematosus (SLE), yet its pathogenesis is not well understood. The normal-appearing epidermis of patients with SLE exhibits increased ultraviolet B (UVB)-driven cell death that persists in cell culture. Here, we investigated the role of epigenetic modification and Hippo signaling in enhanced UVB-induced apoptosis seen in SLE keratinocytes. We analyzed DNA methylation in cultured keratinocytes from SLE patients compared to keratinocytes from healthy controls (n=6/group). Protein expression was validated in cultured keratinocytes using immunoblotting and immunofluorescence. An immortalized keratinocyte line overexpressing WWC1 was generated via lentiviral vector. WWC1-driven changes were inhibited using a large tumor suppressor kinase 1/2 (LATS1/2) inhibitor (TRULI) and small interfering RNA (siRNA). The interaction between the Yes-associated protein (YAP) and the transcriptional enhancer associate domain (TEAD) was inhibited by overexpression of an N/TERT cell line expressing a tetracycline-inducible green fluorescent protein-tagged protein that inhibits YAP-TEAD binding (TEADi). Apoptosis was assessed using cleaved caspase 3/7 and TUNEL staining. Hippo signaling was the top differentially methylated pathway in SLE versus control keratinocytes. SLE keratinocytes (n=6) showed significant hypomethylation (Δβ = -0.153) and thus overexpression of the Hippo regulator WWC1 (P = 0.002). WWC1 overexpression increased LATS1/2 kinase activation, leading to YAP cytoplasmic retention and altered proapoptotic transcription in SLE keratinocytes. Accordingly, UVB-mediated apoptosis in keratinocytes could be enhanced by WWC1 overexpression or YAP-TEAD inhibition, mimicking SLE keratinocytes. Importantly, inhibition of LATS1/2 with either the chemical inhibitor TRULI or siRNA effectively eliminated enhanced UVB-apoptosis in SLE keratinocytes. Our work unravels a novel driver of photosensitivity in SLE: overactive Hippo signaling in SLE keratinocytes restricts YAP transcriptional activity, leading to shifts that promote UVB apoptosis.

Abstract 2558: Loss of TC-PTP in keratinocytes leads to increased UVB-induced autophagy

Abstract Amongst the deteriorating effects of the sun’s ultraviolet B (UVB) radiation on cellular homeostasis is the formation of photoproducts in the DNA, such as cyclobutene pyrimidine dimers. Photoproducts cause conformational alterations in the DNA structure which may evade cellular repair machinery and persist through DNA replication processes, leading to potential gene mutations and ultimately leading to skin cancer. Photoproducts are typically repaired by nucleotide excision repair. Notwithstanding, when the repair mechanism fails, apoptosis ensues to prevent the accumulation of mutations and to restore cellular homeostasis. T-cell protein tyrosine phosphatase (TC-PTP) is one of the members of PTP family that has been shown to increase UVB-induced apoptosis in keratinocytes via the downregulation of Flk-1/JNK signaling. This implies that loss of TC-PTP causes resistance to apoptosis in UVB-damaged keratinocytes. In the present work, we report that this resistance is accompanied by an increase in UVB-induced autophagy in the absence of TC-PTP. We generated human TC-PTP-deficient (TC-PTP/KO) HaCaT keratinocytes using CRISPR/Cas9 system. The expression of microtubule-associated protein light chain 3 (LC3) was significantly increased in TC-PTP/KO HaCaT keratinocytes compared to engineered controls (TC-PTP/Mock) following treatment with UVB irradiation. Increased expression of LC3 in TC-PTP/KO keratinocytes was accompanied by a significant decrease in the expression of the p62. We also observed that treatment of TC-PTP KO keratinocytes with chloroquine (CQ), a late-phase autophagy inhibitor, caused a remarkable increase in LC3 expression following UVB exposure in comparison with untreated TC-PTP/KO keratinocytes, implying that loss of TC-PTP increases autophagy in response to UVB. With this regard, TC-PTP deficiency in human keratinocytes significantly increased cell proliferation following UVB exposure compared to similarly treated control keratinocytes. Pretreatment of CQ before UVB irradiation in TC-PTP KO keratinocytes significantly reduced cell viability compared to untreated TC-PTP KO keratinocytes. These results suggest that TC-PTP protects keratinocytes from UVB-induced damage by negatively regulating autophagy signaling. Citation Format: Obed Asare, Klarissa Zavala, Lindsey Shim, Bilal Hafeez, Dae Kim. Loss of TC-PTP in keratinocytes leads to increased UVB-induced autophagy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2558.

Photoprotective Effects of Dendrobium nobile Lindl. Polysaccharides against UVB-Induced Oxidative Stress and Apoptosis in HaCaT Cells

Acute ultraviolet (UV)-B radiation is the major external factor causing photodamage. In this study, we aimed to determine the effects of Dendrobium nobile Lindl. polysaccharides (DNPs) on photodamage in HaCaT keratinocytes after UVB irradiation and the underlying mechanisms. We found that DNPs significantly attenuated the decline in the viability and proliferation of HaCaT cells after UVB irradiation. Moreover, DNPs scavenged reactive oxygen species (ROS), improved the activities of endogenous antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, and reduced the levels of malondialdehyde, while partially attenuating cell cycle arrest, suggesting their antioxidant and anti-apoptotic properties. The mitogen-activated protein kinase (MAPK) pathway was found to be important for the attenuation of UVB-induced photodamage in the HaCaT cells. Furthermore, DNPs exerted cytoprotective effects by downregulating UVB-induced ROS-mediated phosphorylation of MAPKs, including p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase, and by inhibiting p53 expression as well as the apoptotic cascade response. Therefore, DNPs ameliorated UVB-induced oxidative damage and apoptosis in HaCaT cells via the regulation of MAPKs. Our findings thus highlight the Dendrobium nobile Lindl polysaccharides as promising therapeutic candidates for UVB-induced photodamage.

Safe-Shields: Basal and Anti-UV Protection of Human Keratinocytes by Redox-Active Cerium Oxide Nanoparticles Prevents UVB-Induced Mutagenesis

Cerium oxide nanoparticles (nanoceria), biocompatible multifunctional nanozymes exerting unique biomimetic activities, mimic superoxide-dismutase and catalase through a self-regenerating, energy-free redox cycle driven by Ce3+/4+ valence switch. Additional redox-independent UV-filter properties render nanoceria ideal multitask solar screens, shielding from UV exposure, simultaneously protecting tissues from UV-oxidative damage. Here, we report that nanoceria favour basal proliferation of primary normal keratinocytes, and protects them from UVB-induced DNA damage, mutagenesis, and apoptosis, minimizing cell loss and accelerating recovery with flawless cells. Similar cell-protective effects were found on irradiated noncancerous, but immortalized, p53-null HaCaT keratinocytes, with the notable exception that here, nanoceria do not accelerate basal HaCaT proliferation. Notably, nanoceria protect HaCaT from oxidative stress induced by irradiated titanium dioxide nanoparticles, a major active principle of commercial UV-shielding lotions, thus neutralizing their most critical side effects. The intriguing combination of nanoceria multiple beneficial properties opens the way for smart and safer containment measures of UV-induced skin damage and carcinogenesis.

Hemin protects UVB-induced skin damage through inhibiting keratinocytes apoptosis and reducing neutrophil infiltration.

Ultraviolet-B (UVB) exposure on the skin triggers apoptosis, oxidative stress and acute inflammatory responses, which eventually increases the risk of various skin disorders. Hemin, an iron-binding porphyrin, has been clinically used for porphyria treatment. However, whether hemin contributes to the skin protection against UVB injury remains to be elucidated. Here, we found that hemin treatment (10 and 20mg/kg) by intraperitoneal administration could dramatically relieve UVB irradiation-induced skin damage featured by erythema, edema, epidermal hyperplasia and collagen loss in C57BL/6J mice. Importantly, hemin treatment attenuated UVB irradiation-triggered cell apoptosis in skin epidermis. Consistently, hemin (10, 20μM) treatment decreased Caspase-3 activation and protected against UVB-induced apoptosis in HaCaT cells. Besides, hemin treatment reduced the infiltration of neutrophils in skin under UVB irradiation, thus restrained neutrophil extracellular traps (NET) formation and myeloperoxidase (MPO) release. We further revealed that hemin inhibited the expression of inflammation associated cytokines and chemokines in UVB-induced HaCaT cells and blocked the chemotaxis of dHL-60 cells to preconditioned media from HaCaT culture upon UVB irradiation. Furthermore, hemin inhibited the excessive maturation and mobilization of bone marrow neutrophils and rectified the proportion of abnormally elevated neutrophils in the blood under UVB irradiation. In conclusion, our study showed that hemin treatment protects against UVB-induced skin damage through inhibiting keratinocytes apoptosis, and suppressing neutrophils infiltration in the skin via externally restraining the keratinocyte attraction and internally regulating bone marrow neutrophil maturation and mobilization, suggesting that hemin is an effective drug candidate for the therapy of UVB damage.

Reduction of miR-133a-3p contributes to apoptosis and gasdermin E-mediated pyroptosis of keratinocytes in skin exposed to ultraviolet B radiation.

Engagement of regulated cell death in keratinocytes plays a crucial role in the pathogenesis and development of skin disorders associated with UV radiation. However, it remains unclear how microRNAs (miRNAs) participate in the regulation of UV-caused keratinocyte death. In this study, we found that miR-133a-3p was decreased in the epidermis of UVB-challenged mice and UVB-irradiated keratinocyte cell line HaCaT cells. The intradermal injection of agomir miR-133a-3p ameliorated skin damage of UVB-challenged mice, especially epidermal necrosis. Meanwhile, the injection inhibited apoptosis indicator PARP cleavage and pyroptosis indicator GSDME cleavage in the epidermis. In UVB-challenged HaCaT cells, transfection of miR-133a-3p mimic or inhibitor alleviated or aggravated UVB-induced apoptosis and GSDME-mediated pyroptosis respectively. miR-133a-3p was also involved in the effects of metformin treatment on alleviating skin damage in UVB-challenged mice and on inhibiting apoptosis and GSDME-mediated pyroptosis in UVB-irradiated HaCaT cells. We confirmed that CYLD is a target gene of miR-133a-3p and participates in the protective effects of miR-133a-3p on inhibiting UVB-caused apoptosis and GSDME-mediated pyroptosis in keratinocytes. This study indicates a pivotal role for miR-133a-3p of keratinocytes in UVB-caused skin damage. Alleviating skin photodamage by restoring the decrease of miR-133a-3p can be considered a potential therapeutic approach.

Platelet-rich plasma protects human keratinocytes from UVB-induced apoptosis by attenuating inflammatory responses and endoplasmic reticulum stress.

Although the role of platelet-rich plasma (PRP) in ultraviolet light B (UVB)-induced photoaging has been confirmed in many studies, the specific mechanism is still not clear. Therefore, we attempted to investigate the effect and mechanism of PRP on UVB-induced human keratinocyte (HaCaT cells) apoptosis. HaCaT cells were collected to construct UVB-induced photoaging models. Then, the cells were divided into Sham group, 5% PRP group, UVB group, and UVB + 5% PRP group. Next, MTT assay was used to detect the level of cell proliferation; flow cytometry to check the level of apoptosis; ELISA to determine the TNF-α, IL-18, IL-6, and IL-1β levels in the supernatant; and Western blot to test Bax, Bcl-2, cytochrome c (Cyt.c), GRP78, CHOP, and ATF4 protein expression levels. Briefly, 5% PRP intervention could relieve the inhibition of UVB on HaCaT cell proliferation, inhibit the promotion of UVB to cell apoptosis, up-regulate UVB-induced Bcl-2 protein expression, and decrease Bax and Cyt.c protein level. In addition, 5% PRP significantly down-regulated the inflammatory factor levels of TNF-α, IL-18, IL-6, and IL-1βin UVB-induced cells and reduced the inflammatory response. Moreover, 5% PRP also greatly reduced the protein expression levels of GRP78, CHOP, and ATF4 in UVB-induced cells and alleviated endoplasmic reticulum (ER) stress. PRP may protect HaCaT cells from UVB-induced apoptosis by alleviating inflammatory response and ER stress.

Anthocyanin from Lycium ruthenicum Murr. in the Qaidam Basin Alleviates Ultraviolet-Induced Apoptosis of Human Skin Fibroblasts by Regulating the Death Receptor Pathway.

The study aimed to investigate the potential protective role of anthocyanin from Lycium ruthenicum Murr. in the Qaidam Basin against ultraviolet B (UVB)-induced apoptosis of human skin fibroblasts (HSFs). HSFs cultured in vitro were randomly divided into a control group, UVB group, and anthocyanin groups (0.1, 0.5, and 1.0 mg/mL). HSFs in the UVB and anthocyanin groups were exposed to 30 mJ/cm2 UVB to establish a photoaging model. Then, apoptosis rate, tumor necrosis factor-α (TNF-α), cysteinyl aspartate specific proteinase-3 (caspase-3), cysteinyl aspartate specific proteinase-7 (caspase-7), and survivin expression were evaluated. UVB irradiation can increase the apoptosis rate of HSFs and expression of TNF-α, caspase-7, and survivin. Anthocyanin pretreatment (0.1, 0.5, and 1.0 mg/mL) decreased UVB-induced apoptosis rate and TNF-α and caspase-7 expression and increased survivin expression. Compared with the control group, the apoptosis rate and expression of TNF-α, caspase-7, and survivin of anthocyanin groups in UVB-irradiated HSFs were high. Among the three doses of anthocyanin (0.1, 0.5, and 1.0 mg/mL) groups, the apoptosis rate and TNF-α expression of anthocyanin at 1.0 mg/mL were the lowest. There was no significant change in caspase-3 expression in each group. Anthocyanin from Lycium ruthenicum Murr. in the Qaidam Basin could alleviate UVB-induced apoptosis by regulating the death receptor pathway.

Recombinant Photolyase-Thymine Alleviated UVB-Induced Photodamage in Mice by Repairing CPD Photoproducts and Ameliorating Oxidative Stress.

Cyclobutane pyrimidine dimers (CPDs) are the main mutagenic DNA photoproducts caused by ultraviolet B (UVB) radiation and represent the major cause of photoaging and skin carcinogenesis. CPD photolyase can efficiently and rapidly repair CPD products. Therefore, they are candidates for the prevention of photodamage. However, these photolyases are not present in placental mammals. In this study, we produced a recombinant photolyase-thymine (rPHO) from Thermus thermophilus (T. thermophilus). The rPHO displayed CPD photorepair activity. It prevented UVB-induced DNA damage by repairing CPD photoproducts to pyrimidine monomers. Furthermore, it inhibited UVB-induced ROS production, lipid peroxidation, inflammatory responses, and apoptosis. UVB-induced wrinkle formation, epidermal hyperplasia, and collagen degradation in mice skin was significantly inhibited when the photolyase was applied topically to the skin. These results demonstrated that rPHO has promising protective effects against UVB-induced photodamage and may contribute to the development of anti-UVB skin photodamage drugs and cosmetic products.

RhFGF21 Protects Epidermal Cells against UVB-Induced Apoptosis through Activating AMPK-Mediated Autophagy.

Ultraviolet irradiation, especially ultraviolet B (UVB) irradiation, increases the risks of various skin diseases, such as sunburn, photo-aging and cancer. However, few drugs are available to treat skin lesions. Therefore, the discovery of drugs to improve the health of irradiated skin is urgently needed. Fibroblast growth factor 21 (FGF21) is a metabolic factor that plays an important role in the protection and repair of various types of pathological damage. The effects of FGF21 on skin injury caused by UVB-irradiation were the focus of this study. We found that UVB irradiation promoted the expression of FGF21 protein in mouse epidermal cells, and exogenous recombinant human FGF21 (rhFGF21) protected mouse skin tissue against UVB-induced injury. RhFGF21 inhibited the inflammatory responses and epidermal cell apoptosis as well as promotion of autophagy in UVB-irradiated mice. Moreover, we found that rhFGF21 protected HaCaT cells against UVB-induced apoptosis, and the protective effect was enhanced by treatment with an autophagy activator (rapamycin) but was inhibited by treatment with an autophagy inhibitor (3-methyladenine, 3MA). AMP-activated protein kinase (AMPK), as a cellular energy sensor, regulates autophagy. RhFGF21 increased the expression of p-AMPK protein in epidermal cells irradiated with UVB in vivo and in vitro. Moreover, rhFGF21 increased autophagy levels and the viability were diminished by treatment with an AMPK inhibitor (compound C). RhFGF21 protects epidermal cells against UVB-induced apoptosis by inducing AMPK-mediated autophagy.