The effect of Yang Yan Qing E Wan on senescent phenotypes and the expression of β-catenin and p16INK4a in human skin fibroblasts

Cutaneous Redox Senescence

Our current understanding of skin cell senescence involves the role of environmental stressors (UV, O3, cigarette smoke, particulate matter, etc.), lifestyle (diet, exercise, etc.) as well as genetic factors (metabolic changes, hormonal, etc.). The common mechanism of action of these stressors is the disturbance of cellular redox balance characterized by increased free radicals and reactive oxygen species (ROS), and when these overload the intrinsic antioxidant defense system, it can lead to an oxidative stress cellular condition. The main redox mechanisms that activate cellular senescence in the skin involve (1) the oxidative damage of telomeres causing their shortening; (2) the oxidation of proteomes and DNA damage; (3) an a in lysosomal mass through the increased activity of resident enzymes such as senescence-associated β-galactosidase (SA-β-gal) as well as other proteins that are products of lysosomal activity; (4) and the increased expression of SASP, in particular pro-inflammatory cytokines transcriptionally regulated by NF-κB. However, the main targets of ROS on the skin are the proteome (oxi-proteome), followed by telomeres, nucleic acids (DNAs), lipids, proteins, and cytoplasmic organelles. As a result, cell cycle arrest pathways, lipid peroxidation, increased lysosomal content and dysfunctional mitochondria, and SASP synthesis occur. Furthermore, oxidative stress in skin cells increases the activity of p16INK4A and p53 as inhibitors of Rb and CDks, which are important for maintaining the cell cycle. p53 also promotes the inactivation of mTOR-mediated autophagic and apoptotic pathways, leading to senescence. However, these markers alone cannot establish the state of cellular senescence, and multiple analyses are encouraged for confirmation. An updated and more comprehensive approach to investigating skin senescence should include further assays of ox-inflammatory molecular pathways that can consolidate the understanding of cutaneous redox senescence.

Bazi Bushen alleviates skin senescence by orchestrating skin homeostasis in SAMP6 mice

Bazi Bushen, a Chinese-patented drug with the function of relieving fatigue and delaying ageing, has been proven effective for extenuating skin senescence. To investigate the potential mechanism, senescence-accelerated mouse prone 6 (SAMP6) was intragastrically administered with Bazi Bushen for 9 weeks to induce skin homeostasis. Skin homeostasis is important in mitigating skin senescence, and it is related to many factors such as oxidative stress, SASP, apoptosis, autophagy and stem cell. In our study, skin damage in SAMP6 mice was observed using HE, Masson and SA-β-gal staining. The content of hydroxyproline and the activities of SOD, MDA, GSH-PX and T-AOC in the skin were measured using commercial assay kits. The level of SASP factors (IL-6, IL-1β, TNF-α, MMP2 and MMP9) in skin were measured using ELISA kits. The protein expressions of p16, p21, p53, Bax, Bcl-2, Cleaved caspase-3, LC3, p62, Beclin1, OCT4, SOX2 and NANOG were measured by western blotting. The expression of ITGA6 and COL17A1 was measured by immunofluorescence staining and western blotting. Our findings demonstrated that Bazi Bushen alleviated skin senescence by orchestrating skin homeostasis, reducing the level of oxidative stress and the expression of SASP, regulating the balance of apoptosis and autophagy and enhancing the protein expressions of ITGA6 and COL17A1 to improve skin structure in SAMP6 mice. This study indicated that Bazi Bushen could serve as a potential therapy for alleviating skin senescence.

Cellular senescence in liver diseases: From mechanisms to therapies

Cellular senescence is an irreversible state of cell cycle arrest, characterized by a gradual decline in cell proliferation, differentiation, and biological functions. Cellular senescence is double-edged for that it can provoke organ repair and regeneration in physiological conditions but contribute to organ and tissue dysfunction and prime multiple chronic diseases in pathological conditions. The liver has a strong regenerative capacity, where cellular senescence and regeneration are closely involved. Herein, this review firstly introduces the morphological manifestations of senescent cells, the major regulators (p53, p21, and p16), and the core pathophysiologic mechanisms underlying senescence process, and then specifically generalizes the role and interventions of cellular senescence in multiple liver diseases, including alcoholic liver disease, nonalcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. In conclusion, this review focuses on interpreting the importance of cellular senescence in liver diseases and summarizes potential senescence-related regulatory targets, aiming to provide new insights for further researches on cellular senescence regulation and therapeutic developments for liver diseases.

Modified Qing’e Formula protects against UV-induced skin oxidative damage via the activation of Nrf2/ARE defensive pathway

Exposure to ultraviolet (UV) light triggers the rapid generation and accumulation of reactive oxygen species (ROS) in skin cells, which increases oxidative stress damage and leads to photoaging. Nuclear factor E2-related factor 2 (Nrf2) modulates the antioxidant defense of skin cells against environmental factors, especially ultraviolet radiation. Natural products that target Nrf2-regulated antioxidant reactions are promising candidates for anti-photoaging. The aim of this study was to investigate the protective effect of Modified Qing’e Formula (MQEF) on UV-induced skin oxidative damage and its molecular mechanisms. In this study, the photoaging models of human keratinocytes (HaCaT) and ICR mice were established by UV irradiation. In vitro models showed that MQEF displayed potent antioxidant activity, significantly increased cell viability and reduced apoptosis and excess ROS levels. Meanwhile, the knockdown of Nrf2 reversed the antioxidant and anti-apoptotic effects of MQEF. In vivo experiments indicated that MQEF could protect the skin against UV-exposed injury which manifested by water loss, sensitivity, tanning, wrinkling, and breakage of collagen and elastic fibers. The application of MQEF effectively increased the activity of antioxidant enzymes and reduced the content of malondialdehyde (MDA) in mice. In addition, MQEF was able to activate Nrf2 nuclear translocation in mouse skin tissue. In summary, MQEF may attenuate UV-induced photoaging by upregulating Nrf2 expression and enhancing antioxidant damage capacity. MQEF may be a potential candidate to prevent UV-induced photoaging by restoring redox homeostasis.

Artesunate treatment ameliorates ultraviolet irradiation-driven skin photoaging via increasing β-catenin expression

OBJECTIVE

Artesunate, a semi-synthetic derivative of artemisinin, exerts various pharmacological activities. Nevertheless, the effects of Art on skin photoaging remain unclear. Herein, we investigated whether Art ameliorated ultraviolet-irradiated skin photoaging in HaCaT cells and mice.

METHODS

To construct skin photoaging cellular models, HaCaT cells were irradiated by UV (UVB, 20mJ/cm²) for 5 days. HaCaT cells were pretreated with three concentrations of Art (1, 5 and 20 μg/ml) for 2 h each day. After 5 days, cell senescence, ROS production, SOD levels, p16^INK4a and β-catenin expression, proliferation and apoptosis were detected in HaCaT cells. Effects of Art on normal cells were investigated. After sh-β-catenin transfection or XAV-939 treatment, HaCaT cells were pretreated with 20 μg/ml Art and irradiated by UVB. After 5 days, skin photoaging was then observed. Furthermore, skin photoaging mouse models were established and the effects of Art and β-catenin silencing on skin photoaging were investigated.

RESULTS

Art treatment suppressed cell senescence, intracellular ROS production, p16^INK4a expression and apoptosis and promoted proliferation and SOD and β-catenin expression in UVB irradiated HaCaT cells. But Art had no toxic effects on normal cells. Silencing β-catenin by sh-β-catenin or XAV-939 exacerbated UVB irradiation-mediated cell senescence, apoptosis, and ROS production in HaCaT cells, which was ameliorated by Art treatment. The therapeutic effects of Art on skin photoaging were also confirmed in mouse models.

CONCLUSIONS

These findings suggested that Art treatment alleviated UVB irradiation-driven skin photoaging through enhancing β-catenin expression, which offered novel clues for pharmacological activity of Art.