Bach2 regulates autophagy to modulate UVA-induced photoaging in skin fibroblasts

miR-1246-overexpressing exosomes improve UVB-induced photoaging by activating autophagy via suppressing GSK3β

Stem cell paracrine has shown potential application in skin wound repair and photoaging treatment. Our previous study demonstrated that miR-1246-overexpressing Exosomes (OE-EXs) isolated from adipose-derived stem cells (ADSCs) showed superior photo-protecting effects on UVB-induced photoaging than that of the vector, however, the underlying mechanism was unclear. The simultaneous bioinformatics analysis indicated that miR-1246 showed potential binding sites with GSK3β which acted as a negative regulator for autophagy. This study was aimed to explore whether OE-EXs ameliorate skin photoaging by activating autophagy via targeting GSK3β. The results demonstrated that OE-EXs significantly decreased GSK3β expression, enhanced autophagy flux and autophagy-related proteins like LC3II, while suppressed p62 expression. Meanwhile, OE-EXs markedly reversed the levels of intracellular ROS, MMP-1, procollagen type I and DNA damage in human skin fibroblasts caused by UVB irradiation, but the ameliorating effects were significantly inhibited when 3-Methyladenine (3-MA) was introduced to block the autophagy pathway. Further, OE-EXs could reverse UVB-induced wrinkles, epidermal hyperplasia, and collagen fibers reduction in Kunming mice, nevertheless, the therapeutical effects of OE-EXs were attenuated when it was combinative treated with 3-MA. In conclusion, OE-EXs could cure UVB induced skin photoaging by activating autophagy via targeting GSK3β.

Full-face ALA-PDT for facial actinic keratosis: Two case reports

We reported two cases of full-face 5-aminolevulinic acid-photodynamic therapy (ALA-PDT) for facial multiple actinic keratosis (AK). After the full-face ALA-PDT, we observed that the AK lesions on the faces of the patients were completely cleared and facial rejuvenation was achieved. In our follow-up, one patient was free of recurrence for over 13 months and the other one for over 28 months. The experience of these two cases may indicate that full-face ALA-PDT has an excellent therapeutic effect while potentially preventing the recurrence of AK.

Exosomes in skin photoaging: biological functions and therapeutic opportunity

Exosomes are tiny extracellular vesicles secreted by most cell types, which are filled with proteins, lipids, and nucleic acids (non-coding RNAs, mRNA, DNA), can be released by donor cells to subsequently modulate the function of recipient cells. Skin photoaging is the premature aging of the skin structures over time due to repeated exposure to ultraviolet (UV) which is evidenced by dyspigmentation, telangiectasias, roughness, rhytides, elastosis, and precancerous changes. Exosomes are associated with aging-related processes including, oxidative stress, inflammation, and senescence. Anti-aging features of exosomes have been implicated in various in vitro and pre-clinical studies. Stem cell-derived exosomes can restore skin physiological function and regenerate or rejuvenate damaged skin tissue through various mechanisms such as decreased expression of matrix metalloproteinase (MMP), increased collagen and elastin production, and modulation of intracellular signaling pathways as well as, intercellular communication. All these evidences are promising for the therapeutic potential of exosomes in skin photoaging. This review aims to investigate the molecular mechanisms and the effects of exosomes in photoaging.

Overexpression of SIRT6 regulates NRF2/HO-1 and NF-κB signaling pathways to alleviate UVA-induced photoaging in skin fibroblasts

Skin photoaging, resulting from prolonged exposure to sunlight, especially UVA rays, has been identified as a key contributor to age-related skin degeneration. However, the mechanism by which UVA radiation induces skin cell senescence has not been fully elucidated. In this investigation, bioinformatics technology was employed to identify SIRT6 as the core hub gene involved in the progression of skin photoaging. The study evinced that prolonged exposure of cutaneous fibroblasts to UVA radiation results in a marked reduction in the expression of SIRT6, both in vivo and in vitro. Knockdown of SIRT6 in skin fibroblasts resulted in the upregulation of genes associated with cellular aging, thereby exacerbating the effects of UVA radiation-induced photoaging. Conversely, overexpression of SIRT6 decreased the expression of cell aging-related genes, indicating that SIRT6 plays a role in the regulation of senescence in skin fibroblasts induced by UVA radiation. We proffer substantiation that overexpression of SIRT6 protects skin fibroblasts from UVA-induced oxidative stress by activating the NRF2/HO-1 signaling cascade. Moreover, SIRT6 overexpression also reduced UVA-induced type I collagen degradation by inhibiting NF-κB signaling cascade. In summary, our findings showed that overexpression of SIRT6 inhibits UVA-induced senescence phenotype and type I collagen degradation in skin fibroblasts by modulating the NRF2/HO-1 and NF-κB signaling pathways. And the regulation of these signaling pathways by SIRT6 may be achieved through its deacetylase activity. Therefore, SIRT6 is a novel and promising therapeutic target for skin aging related to age and UV.

Decreased SIRT1 protein may promote HMGB1 translocation in the keratinocytes of patients with cutaneous lupus erythematosus

Background Ultraviolet radiation causes DNA damage in keratinocytes, aggravating cutaneous lupus erythematosus (CLE). High mobility group box 1 (HMGB1) participates in nucleotide excision and may transfer from the nucleus to the cytoplasm in immune active cells and the translocation of HMGB1 may result in DNA repair defects. HMGB1 was observed to transfer from the nucleus to the cytoplasm in the keratinocytes of CLE patients. As a class III histone deacetylases (HDACs), sirtuin-1 (SIRT1) can induce HMGB1 deacetylation. Epigenetic modification of HMGB1 may lead to HMGB1 translocation. Aims We aimed to evaluate the expressions of SIRT1 and HMGB1 in the epidermis of CLE patients and whether decreased SIRT1 leads to HMGB1 translocation through HMGB1 acetylation in keratinocytes. Methods We measured the messenger RNA (mRNA) and protein expressions of SIRT1 and HMGB1 in CLE patients using real-time reverse transcription polymerase chain reaction (RT-qPCR) and western blotting. Keratinocytes were treated with SIRT1 activator resveratrol (Res) and irradiated with ultraviolet B (UVB). We detected the localization expression of HMGB1 by immunofluorescence. The apoptosis level and the cell cycle proportions were measured by flow cytometry. The acetyl-HMGB1 level was detected by immunoprecipitation. Results Compared to healthy controls, the mRNA and protein expressions of SIRT1 in the epidermis of CLE patients were significantly decreased and there was translocation of HMGB1 from the nucleus to the cytoplasm. In keratinocytes, UVB irradiation led to HMGB1 translocation from the nucleus to the cytoplasm. Res treatment inhibited HMGB1 translocation, attenuated the cell apoptosis induced by UVB and decreased the acetyl-HMGB1 level. Limitations We only treated keratinocytes with the SIRT1 activator but did not perform the relevant experiments in keratinocytes with SIRT1 knockdown or overexpression. In addition, the lysine residue site of action of SIRT1 deacetylation of HMGB1 is unclear. The specific mechanism of action of SIRT1 deacetylation of HMGB1 needs to be further investigated. Conclusion SIRT1 may inhibit HMGB1 translocation by HMGB1 deacetylation which inhibited the apoptosis of keratinocytes induced by UVB. Decreased SIRT1 may promote HMGB1 translocation in the keratinocytes of patients with CLE.

Smart nanostructures for targeted oxygen-producing photodynamic therapy of skin photoaging and potential mechanism

Background: Photodynamic therapy increases collagen and decreases solar fibrosis in photoaged skin; however, the efficacy of photodynamic therapy is limited in tissues with a hypoxic microenvironment. Methods: A novel autogenous oxygen-targeted nanoparticle, named MCZT, was synthesized based on the zeolitic imidazole framework material ZIF-8, methyl aminolevulinate, catalase and an anti-TRPV1 monoclonal antibody, and its effects on skin photoaging were investigated. Results: MCZT was successfully synthesized and showed uniform particle size, good dispersion, and excellent biocompatibility and safety. Moreover, MCZT effectively alleviated UV-induced inflammation, cellular senescence and apoptosis in HFF-1 cells. In in vivo models, MCZT ameliorated UV-evoked erythema and wrinkling, inflammation and oxidative stress, as well as the loss of collagen fibers and water, in the skin of mice. Conclusion: These findings suggest that MCZT holds promising potential for the treatment of skin photoaging.

Low-energy green light alleviates senescence-like phenotypes in a cell model of photoaging

BACKGROUND

Ultraviolet B (UVB) affects diverse pathways in skin cells, resulting in skin photoaging. Skin fibroblasts internalize and degrade elastin and collagen, playing prominent roles in photoaging. Green light is used in many fields of dermatology, but few studies have examined its role in photoaging. The present work aimed to assess low-energy green light for its effects in a previously proposed cell model of photoaging and to explore the possible anti-photoaging mechanism.

METHODS

The stress-induced premature senescence (SIPS) model was constructed via repeated treatment of MDFs with UVB. Senescence-like phenotypes were compared among normal, low-energy green light pretreatment and UVB groups, for example, cell morphological properties, senescence-associated β-galactosidase (SA-β-gal) amounts, extracellular matrix (ECM) biosynthesis and degradation, and autophagy.

RESULTS

In comparison with the UVB group, the green light pretreatment group showed significantly decreased number of senescent mast cells and markedly declined signal intensity and amounts of SA-β-gal-positive cells. Furthermore, green light pretreatment directly affected ECM by increasing type I and type III collagen production and decreasing MMP-1 amounts. Moreover, changes in autophagy levels induced by green light pretreatment provided a potential mechanism underlying its anti-aging property.

CONCLUSIONS

Low-energy green light pretreatment improves senescence-like phenotypes in vitro, indicating a possible application for anti-aging in clinic after future research has uncovered the potential mechanism.

TAZ Reduces UVA-mediated Photoaging through Regulates Cell Proliferation in Skin Fibroblasts

The transcriptional co-activator with PDZ-binding motif (TAZ) is a significant transcription factor downstream of the Hippo pathway regulating organ size, tissue regeneration, cell proliferation and apoptosis. Here, we report on TAZ in response to photoaging mediated by repeated UVA irradiation in skin fibroblasts. Continuous UVA irradiation caused a decrease in TAZ and targeted CTGF mRNA and protein expression in fibroblasts, accompanied by reduced cell proliferation, DNA damage, and cell cycle arrest in G1 phase and S phase reduction. Furthermore, P16 and P21 expression levels were increased, whereas Lamin B1 and Lamin A/C expression were decreased as a result of repeated UVA exposure. We further demonstrated that TAZ reduction enables photoaging caused by continuously UVA-irradiated fibroblasts. TAZ overexpression decreases G1 phase, augments the S phase and reduces P16 and P21 protein expression levels in fibroblasts. However, TAZ overexpressing cells exposed to chronic-UVA radiation show induced G1 phase arrest, an S phase reduction, and elevated P16 and P21 protein levels in fibroblasts, compared with TAZ overexpression cells. These findings suggest a novel function of TAZ to reduce photoaging in fibroblasts. This regulation implies that TAZ might be a viable therapeutic target for photoaging or UVA-related skin disorders.

Protective effects of the phenolic compounds from mung bean hull against H2O2-induced skin aging through alleviating oxidative injury and autophagy in HaCaT cells and HSF cells

To add value to food waste and seek skin aging suppressor, petroleum ether, ethyl acetate, n-butanol and water phenolic extracts were produced from mung bean hulls subjected to ultrasound-assisted ethanolic extraction. The four extracts all contained protocatechuic acid, isovitexin, vitexin, caffeic acid, 4-coumaric acid, ferulic acid, rutin and chlorogenic acid (revealed by UHPLC-MS/MS). The effects of the four extracts and their main phenolic compounds against H₂O₂-caused cell damage and aging in HaCaT and HSF cells were examined (including cell viability, ROS, MDA, SOD, GSH-px and β-galactosidase levels). The four extracts and the eight phenolic compounds exhibited different protective effects on H₂O₂-treated HaCaT/HSF cells viability, with the ethyl acetate extract among the extracts, and isovitexin and vitexin among the eight compounds, exerting the greatest protection. Therefore, isovitexin and vitexin may be the key oxidative stress and autophagy modulators of mung bean hull, and they inhibit skin aging and damage likely through suppressing Nrf2/keap1/HO-1 related oxidative damage and LC3II/p62/GATA4 related autophagy.

Theragra chalcogramma Hydrolysate, Rich in Gly-Leu-Pro-Ser-Tyr-Thr, Alleviates Photoaging via Modulating Deposition of Collagen Fibers and Restoration of Extracellular Components Matrix in SD Rats

Excessive exposure of the skin to ultraviolet irradiation induces skin photoaging, which seriously deteriorates the barrier functions of skin tissue, and even causes skin damages and diseases. Recently, dietary supplements from marine sources have been found to be useful in modulating skin functions and can be used to alleviate photoaging. Herein, the low-molecular-weight hydrolysates with a photoaging-protection effect were prepared by enzymatic hydrolysis from Theragra chalcogramma (TCH), and the potential mechanism were subsequently explored. The results revealed that TCH desirably improved the barrier functions of photoaged skin and stimulated the deposition of ECM components Col I, Hyp, and HA in the dermal layer. Histologically, TCH reduced the epidermal hyperplasia and restored the impaired architectures in a dose-dependent manner. Meanwhile, the activity of matrix metalloproteinase-1 (MMP-1) in photoaging skin was inhibited, and the expression levels of elastin and fibrillin-1 were elevated accordingly after TCH administration, and the significant improvements were observed at high-dose level (p < 0.05). Taken together, the efficacy of TCH against skin photoaging is highly associated with the regulation on ECM metabolism and the repairing of damaged mechanical structure.

Shedding a New Light on Skin Aging, Iron- and Redox-Homeostasis and Emerging Natural Antioxidants

Reactive oxygen species (ROS) are necessary for normal cell signaling and the antimicrobial defense of the skin. However excess production of ROS can disrupt the cellular redox balance and overwhelm the cellular antioxidant (AO) capacity, leading to oxidative stress. In the skin, oxidative stress plays a key role in driving both extrinsic and intrinsic aging. Sunlight exposure has also been a major contributor to extrinsic photoaging of the skin as its oxidising components disrupt both redox- and iron-homeostasis, promoting oxidative damage to skin cells and tissue constituents. Upon oxidative insults, the interplay between excess accumulation of ROS and redox-active labile iron (LI) and its detrimental consequences to the skin are often overlooked. In this review we have revisited the oxidative mechanisms underlying skin damage and aging by focussing on the concerted action of ROS and redox-active LI in the initiation and progression of intrinsic and extrinsic skin aging processes. Based on these, we propose to redefine the selection criteria for skin antiaging and photoprotective ingredients to include natural antioxidants (AOs) exhibiting robust redox-balancing and/or iron-chelating properties. This would promote the concept of natural-based or bio-inspired bifunctional anti-aging and photoprotective ingredients for skincare and sunscreen formulations with both AO and iron-chelating properties.