Senescence In Human Dermal Fibroblasts Research Articles

Downregulated SPESP1-driven fibroblast senescence decreases wound healing in aged mice.

Human dermal fibroblasts (HDFs) are essential in the processes of skin ageing and wound healing. However, the underlying mechanism of HDFs in skin healing of the elderly has not been well defined. This study aims to elucidate the mechanisms of HDFs senescence and how senescent HDFs affect wound healing in aged skin. The expression and function of sperm equatorial segment protein 1 (SPESP1) in skin ageing were evaluated via in vivo and in vitro experiments. To delve into the potential molecular mechanisms by which SPESP1 influences skin ageing, a combination of techniques was employed, including proteomics, RNA sequencing, immunoprecipitation, chromatin immunoprecipitation and liquid chromatography-mass spectrometry analyses. Clearance of senescent cells by dasatinib plus quercetin (D+Q) was investigated to explore the role of SPESP1-induced senescent HDFs in wound healing. Here, we define the critical role of SPESP1 in ameliorating HDFs senescence and retarding the skin ageing process. Mechanistic studies demonstrate that SPESP1 directly binds to methyl-binding protein, leading to Decorin demethylation and subsequently upregulation of its expression. Moreover, SPESP1 knockdown delays wound healing in young mice and SPESP1 overexpression induces wound healing in old mice. Notably, pharmacogenetic clearance of senescent cells by D+Q improved wound healing in SPESP1 knockdown skin. Taken together, these findings reveal the critical role of SPESP1 in skin ageing and wound healing, expecting to facilitate the development of anti-ageing strategies and improve wound healing in the elderly.

Combined dasatinib and quercetin treatment contributes to skin rejuvenation through selective elimination of senescent cells in vitro and in vivo.

The skin's protective functions are compromised over time by both endogenous and exogenous aging. Senescence is well-documented in skin phenotypes, such as wrinkling and sagging, a consequence of the senescence-associated secretory phenotype (SASP) that involves the accumulation of senescent fibroblasts, chronic inflammation, and collagen remodeling. Although therapeutic approaches for eliminating senescent cells from the skin are available, their efficacy remains unclear. Accordingly, we aimed to examine the effects of dasatinib in combination with quercetin (D + Q) on senescent human skin fibroblasts and aging human skin. Senescence was induced in human dermal fibroblasts (HDFs) using approaches such as long-term passaging, ionizing radiation, and doxorubicin treatment. The generated senescent cells were treated with D + Q or vehicle. Additionally, a mouse-human chimera model was generated by subcutaneously transplanting whole-skin grafts of aged individuals onto nude mice. Mouse models were administered D + Q or vehicle by oral gavage for 30 days. Subsequently, skin samples were harvested and stained for senescence-associated beta-galactosidase. Senescence-associated markers were assessed by western blotting, reverse transcription-quantitative PCR and histological analyses. Herein, D + Q selectively eliminated senescent HDFs in all cellular models of induced senescence. Additionally, D + Q-treated aged human skin grafts exhibited increased collagen density and suppression of the SASP compared with control grafts. No adverse events were observed during the study period. Collectively, D + Q could ameliorate skin aging through selective elimination of senescent dermal fibroblasts and suppression of the SASP. Our findings suggest that D + Q could be developed as an effective therapeutic approach for combating skin aging.

Induction of Autophagy by Extract from Corydalis heterocarpa for Skin Anti-Aging.

The extracts of Corydalis heterocarpa, a salt-tolerant plant, exhibit diverse physiological properties, including anti-inflammatory, anticancer, and antiadipogenic effects. However, the anti-aging effects of C. heterocarpa extract (CHE) on human skin cells have not yet been investigated. In the present study, we determined that CHE inhibited senescence-associated β-galactosidase (SA-β-gal)-stained senescent human dermal fibroblasts (HDFs). Furthermore, CHE markedly suppressed the expression of major regulatory proteins involved in senescence, including p53, p21, and caveolin-1. Interestingly, CHE promoted autophagic flux, as confirmed by the formation of microtubule-associated protein 1 light chain 3B (LC3B) puncta and lysosomal activity. Notably, using RNA sequencing (RNA-seq), we showed that CHE selectively regulated the gene expression of leucine-rich repeat and sterile alpha motif-containing 1 (LRSAM1), an important regulator of autophagy. The adenosine-monophosphate activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway, which is essential for autophagy regulation, was also modulated by CHE. LRSAM1 depletion not only inhibited LC3B expression but also decreased the autophagy flux induced by CHE. Moreover, the knockdown of LRSAM1 suppressed the reversal of CHE-induced senescence in old HDFs. Collectively, our study has revealed the rejuvenating effects and molecular mechanisms of CHE, suggesting that CHE may be a promising anti-aging agent.

Vutiglabridin Alleviates Cellular Senescence with Metabolic Regulation and Circadian Clock in Human Dermal Fibroblasts.

The process of cellular senescence, which is characterized by stable cell cycle arrest, is strongly associated with dysfunctional cellular metabolism and circadian rhythmicity, both of which are reported to result from and also be causal to cellular senescence. As a result, modifying any of them-senescence, metabolism, or the circadian clock-may affect all three simultaneously. Obesity accelerates aging by disrupting the homeostasis of reactive oxygen species (ROS) via an increased mitochondrial burden of fatty acid oxidation. As a result, if senescence, metabolism, and circadian rhythm are all linked, anti-obesity treatments may improve metabolic regulation while also alleviating senescence and circadian rhythm. Vutiglabridin is a small molecule in clinical trials that improves obesity by enhancing mitochondrial function. We found that chronic treatment of senescent primary human dermal fibroblasts (HDFs) with vutiglabridin alleviates all investigated markers of cellular senescence (SA-β-gal, CDKN1A, CDKN2A) and dysfunctional cellular circadian rhythm (BMAL1) while remarkably preventing the alterations of mitochondrial function and structure that occur during the process of cellular senescence. Our results demonstrate the significant senescence-alleviating effects of vutiglabridin, specifically with the restoration of cellular circadian rhythmicity and metabolic regulation. These data support the potential development of vutiglabridin against aging-associated diseases and corroborate the intricate link between cellular senescence, metabolism, and the circadian clock.

WTAP Mediated N6-methyladenosine RNA Modification of ELF3 Drives Cellular Senescence by Upregulating IRF8.

N6-methyladenosine (m6A), the most prevalent posttranscriptional RNA modification, involved in various diseases and cellular processes. However, the underlying mechanisms of m6A regulation in skin aging are still not fully understood. In this study, proteomics analysis revealed a significant correlation between Wilms' tumor 1-associating protein (WTAP) expression and cellular senescence. Next, upregulated WTAP was detected in aging skin tissues and senescent human dermal fibroblasts (HDFs). Functionally, overexpressed WTAP induced senescence and knockdown of WTAP rescued senescence of HDFs. Mechanistically, WTAP directly targeted ELF3 and promoted its expression in an m6A-dependent manner. Exogenous-ELF3 overexpression evidently reversed shWTAP-suppressed fibroblast senescence. Furthermore, ELF3 induced IRF8-mediated senescence-associated secretory phenotype (SASP) by binding to the (-817 to -804) site of the IRF8 promoter directly. In vivo, overexpression of WTAP evidently increased senescence cells in skin and induced skin aging. In summary, these findings revealed the critical role of WTAP-mediated m6A modification in skin aging and identified ELF3 as an important target of m6A modification in HDFs senescence, providing a new idea for delaying the aging process.

Extracellular vesicles of Weizmannia coagulans lilac-01 reduced cell death of primary microglia and increased mitochondrial content in dermal fibroblasts in vitro.

We investigated the properties of extracellular vesicles from the probiotic Weizmannia coagulans lilac-01 (Lilac-01EVs). The phospholipids in the Lilac-01EV membrane were phosphatidylglycerol and mitochondria-specific cardiolipin. We found that applying Lilac-01EVs to primary rat microglia in vitro resulted in a reduction in primary microglial cell death (P<.05). Lilac-01EVs, which contain cardiolipin and phosphatidylglycerol, may have the potential to inhibit cell death in primary microglia. The addition of Lilac-01EVs to senescent human dermal fibroblasts suggested that Lilac-01 EVs increase the mitochondrial content without affecting their membrane potential in these cells.

Cistanche deserticola Polysaccharide Reduces Inflammation and Aging Phenotypes in the Dermal Fibroblasts through the Activation of the NRF2/HO-1 Pathway.

Dermal fibroblasts maintain the skin homeostasis by interacting with the epidermis and extracellular matrix. Their senescence contributes to functional defects in the skin related to aging. Therefore, there is an urgent need for novel therapeutic agents that could inhibit fibroblast senescence. In this study, we investigated the effects of Cistanche deserticola polysaccharide (CDP), a natural anti-inflammatory component, on the progression of senescence in human dermal fibroblasts. Normal human dermal fibroblasts (NHDFs) were cultured in passages, and highly senescent cells were selected as senescent cells. CDP treatment increased the cell proliferation in senescent NHDFs and decreased the proportion of senescence-associated-β-galactosidase-positive cells. The treatment suppressed the senescence-related secretory phenotype, and reactive oxygen species (ROS) production was reduced, alleviating H2O2-induced oxidative stress. CDP mitigated ROS formation via the nuclear factor erythroid 2-related factor/heme oxygenase-1 pathway in senescent cells and was involved in the suppression of upstream p-extracellular signal-regulated kinase. These results indicate that CDP is an antioxidant that can alleviate age-related inflammation and may be a useful compound for skin anti-aging.

Fisetin, a potential skin rejuvenation drug that eliminates senescent cells in the dermis.

Accumulation of senescent fibroblasts, chronic inflammation, and collagen remodeling due to aging-related secretory phenotypes have been hypothesized to cause age-related skin aging, which results in wrinkles and loss of skin elasticity, thus compromising appearance attractiveness. However, the rejuvenating effects of removing senescent cells from the human skin and the efficacy of related therapeutic agents remain unclear. Here, we investigated the effects of fisetin, a potential anti-aging component found in various edible fruits and vegetables, on senescent human dermal fibroblasts (HDFs) and aging human skin. Senescence was induced in primary HDFs using long-term passaging and treatment with ionizing radiation, and cell viability was assessed after treatment with fisetin and a control component. A mouse/human chimeric model was established by subcutaneously transplanting whole skin grafts from aged individuals into nude mice, which were treated intraperitoneally with fisetin or control a component for 30 d. Skin samples were obtained and subjected to senescence-associated-beta-galactosidase staining; the extent of aging was evaluated using western blotting, reverse transcription-quantitative PCR, and histological analysis. Fisetin selectively eliminated senescent dermal fibroblasts in both senescence-induced cellular models; this effect is attributable to cell death induction by caspases 3, 8, and 9-mediated endogenous and exogenous apoptosis. Fisetin-treated senescent human skin grafts showed increased collagen density and decreased senescence-associated secretory phenotypes (SASP), including matrix metalloproteinases and interleukins. No apparent adverse events were observed. Thus, fisetin could improve skin aging through selective removal of senescent dermal fibroblasts and SASP inhibition, indicating its potential as an effective novel therapeutic agent for combating skin aging.

Chemical constituents with senolytic activity from the stems of Limacia scandens

While screening senotherapeutics from natural products, seven undescribed chemicals, two syringylglycerol derivatives, two cyclopeptides, one tigliane analogue, and two chromone derivatives, as well as six known compounds were isolated from the stems of Limacia scandens. The structures of compounds were elucidated through spectroscopic data analysis, including 1D and 2D NMR, HRESIMS, and CD data. All compounds were tested in replicative senescent human dermal fibroblasts (HDFs) to determine their potential as senotherapeutic agents to specifically target senescent cells. One tigliane and two chromones derivatives showed senolytic activity, indicating that senescent cells were selectively removed. Especially, 2-{2-[(3′-O-β-d-glucopyranosyl)phenyl]ethyl}chromone is expected to be a potential senotherapeutics by inducing HDF death, inhibiting the activity of senescence-associated β-galactosidase (SA-β-gal) and expressing senescence-associated secretory phenotype (SASP) factors.

ANT2 Accelerates Cutaneous Wound Healing in Aged Skin by Regulating Energy Homeostasis and Inflammation

An effective healing response is critical to healthy aging. In particular, energy homeostasis has become increasingly recognized as a factor in effective skin regeneration. Adenine nucleotide translocase 2 (ANT2) is a mediator of ATP import into mitochondria for energy homeostasis. Although energy homeostasis and mitochondrial integrity are critical for wound healing, the role played by ANT2 in the repair process had not been elucidated to date. In our study, we found that ANT2 expression decreased in aged skin and cellular senescence. Interestingly, overexpression of ANT2 in aged mouse skin accelerated the healing of full-thickness cutaneous wounds. In addition, upregulation of ANT2 in replicative senescent human diploid dermal fibroblasts (HDFs) induced their proliferation and migration, which are critical processes in wound healing. Regarding energy homeostasis, ANT2 overexpression increased the ATP production rate by activating glycolysis and induced mitophagy. Notably, ANT2-mediated upregulation of HSPA6 in aged HDFs downregulated proinflammatory genes that mediate cellular senescence and mitochondrial damage. This study demonstrates a previously uncharacterized physiological role of ANT2 in skin wound healing via regulating cell proliferation, energy homeostasis and inflammation. Thus, our study links energy metabolism to skin homeostasis and reports to our knowledge previously unreported genetic factor that enhances wound healing in an aging model.

Reduction of senescence-associated secretory phenotype and exosome-shuttled miRNAs by Haritaki fruit extract in senescent dermal fibroblasts.

Skin ageing is linked to the accumulation of senescent cells and a "senescence-associated secretory phenotype" (SASP). SASP factors include chemokines, cytokines, and small extracellular vesicles (EVs) containing miRNAs. We characterized SASP profile markers in normal human dermal fibroblasts (HDFs) and evaluated the effect of Haritaki fruit extract on these senescence markers. Senescence was induced in HDFs by ionizing radiation (X ray), followed by 14 days of culture. Parallel incubations included fibroblasts treated for 12 days with 10 or 100 μg/mL Haritaki (a standardized extract of Terminalia chebula fruit). Senescence was assessed on Day 14 according to cell morphology, β-galactosidase activity, RT-qPCR measurement of SASP genes, as well as semi-quantitative (RT-qPCR) expression of miRNAs contained in EVs isolated from the medium. The size and distribution of EVs were measured by Nanoparticle Tracking Analysis. Human dermal fibroblasts exhibited a senescent phenotype 14 days after ionizing-radiation, demonstrated by a flattened and irregular shape, increased β-galactosidase activity and over-expression of SASP genes. CSF3, CXCL1, IL1β, IL6 and IL8 genes were increased by 1492%, 1041%, 343%, 478%, 2960% and 293%, respectively. The cell cycle inhibitor, CDKN1A, was increased by 357%, while COL1A1, was decreased by 56% and MMP1 was increased by 293%. NTA analysis of the EVs size distribution indicated a mix of exosomes (45-100 nm) and microvesicles (100-405 nm). miRNA expression in EVs was increased in senescent fibroblasts. miR 29a-3p, miR 30a-3p, miR 34a-5p, miR 24a-3p and miR 186-5p were increased in senescent HDF by 4.17-, 2.43-, 1.17-, 2.01, 12.5-fold, respectively. Incubation of senescent fibroblasts with Haritaki extract strongly decreased SASP mRNA levels and miRNA expression in EVs. Haritaki strongly reduced SASP expression and EV-shuttled miRNAs in senescent fibroblasts. These results indicate that Haritaki has strong senomorphic properties and may be a promising ingredient for the development of new anti-ageing dermo-cosmetic products by inhibiting deleterious effects of senescent cells.

LncRNA PVT1 delays skin photoaging by sequestering miR-551b-3p to release AQP3 expression via ceRNA mechanism.

Understanding human skin photoaging requires in-depth knowledge of the molecular and functional mechanisms. Human dermal fibroblasts (HDFs) gradually lose their ability to produce collagen and renew intercellular matrix with aging. Therefore, our study aims to reveal the mechanistic actions of a novel ceRNA network in the skin photoaging by regulating HDF activities. Photoaging-related genes were obtained in silico, followed by GO and KEGG enrichment analyses. Differentially expressed lncRNAs and miRNAs were screened from the GEO database to construct the ceRNA co-expression network. In skin photoaging samples, PVT1 and AQP3 were poorly expressed, while miR-551b-3p was highly expressed. The relationships among the lncRNA, miRNA and mRNA were explored through the ENCORI database and dual luciferase reporter assay. Mechanistically, PVT1 could sequester miR-551b-3p to upregulate the expression of AQP3, which further inactivated the ERK/p38 MAPK signaling pathway. HDFs were selected to construct an in vitro cell skin photoaging model, where the senescence, cell cycle distribution and viability of young and senescent HDFs were detected by SA-β-gal staining, flow cytometry and CCK-8 assay. In vitro cell experiments confirmed that overexpression of PVT1 or AQP3 enhanced viability of young and senescent HDFs and inhibited HDF senescence, while miR-551b-3p upregulation counteracted the effect of PVT1. In conclusion, PVT1-driven suppression of miR-551b-3p induces AQP3 expression to inactivate the ERK/p38 MAPK signaling pathway, thereby inhibiting HDF senescence and ultimately delaying the skin photoaging.

The expression of fibrosis-related genes is elevated in doxorubicin-induced senescent human dermal fibroblasts, but their secretome does not trigger a paracrine fibrotic response in non-senescent cells

Tissue fibrosis is associated with the aging process of most of our organs, and organ aging correlates with the chronic accumulation of senescent cells. Fibrosis occurs when fibroblasts proliferate and deposit pathological amounts of extracellular matrix (ECM), leading to progressive tissue scarring and organ dysfunction. Fibroblasts play a key role in fibrosis, especially in the skin where fibroblasts are the most abundant cell type in the dermis and are mainly responsible for the synthesis of ECM. This study aims to investigate how senescent fibroblasts and their secretome influence dermal fibrosis. Here we used human dermal fibroblasts (HDFs) treated with doxorubicin (doxo) to induce senescence. The senescent phenotype of these stress-induced premature senescent (SIPS) cells was confirmed with several markers. The expression of pro-fibrotic genes was quantified and finally, the impact of their secretome on the fibrotic response of non-senescent fibroblasts was assessed. Doxorubicin treatment, induced senescence in fibroblasts which has been confirmed with elevated senescence-associated β- galactosidase (SA-β-gal) activity, absence of BrdU incorporation, upregulation of p21, and loss of Lamin b1. Expression levels of the pro-fibrotic genes ACTA2 and FN1 increased in SIPS cells, but in contrast to studies using lung fibroblasts the secretome of these cells failed to induce a paracrine fibrotic response in non-senescent cells. In general, these results suggest that these senescent cells are potentially profibrotic, and their accumulation can trigger fibrosis in organs.

P-MSC-derived extracellular vesicles facilitate diabetic wound healing via miR-145-5p/ CDKN1A-mediated functional improvements of high glucose-induced senescent fibroblasts.

Persistent hyperglycaemia in diabetes causes functional abnormalities of human dermal fibroblasts (HDFs), partially leading to delayed skin wound healing. Extracellular vesicles (EVs) containing multiple pro-healing microRNAs (miRNAs) have been shown to exert therapeutic effects on diabetic wound healing. The present study aimed to observe the effects of EVs derived from placental mesenchymal stem cells (P-MSC-EVs) on diabetic wound healing and high glucose (HG)-induced senescent fibroblasts and to explore the underlying mechanisms. P-MSC-EVs were isolated by differential ultracentrifugation and locally injected into the full-thickness skin wounds of diabetic mice, to observe the beneficial effects on wound healing in vivo by measuring wound closure rates and histological analysis. Next, a series of assays were conducted to evaluate the effects of low (2.28 x 1010 particles/ml) and high (4.56 x 1010 particles/ml) concentrations of P-MSC-EVs on the senescence, proliferation, migration, and apoptosis of HG-induced senescent HDFs in vitro. Then, miRNA microarrays and real-time quantitative PCR (RT-qPCR) were carried out to detect the differentially expressed miRNAs in HDFs after EVs treatment. Specific RNA inhibitors, miRNA mimics, and small interfering RNA (siRNA) were used to evaluate the role of a candidate miRNA and its target genes in P-MSC-EV-induced improvements in the function of HG-induced senescent HDFs. Local injection of P-MSC-EVs into diabetic wounds accelerated wound closure and reduced scar widths, with better-organized collagen deposition and decreased p16INK4a expression. In vitro, P-MSC-EVs enhanced the antisenescence, proliferation, migration, and antiapoptotic abilities of HG-induced senescent fibroblasts in a dose-dependent manner. MiR-145-5p was found to be highly enriched in P-MSC-EVs. MiR-145-5p inhibitors effectively attenuated the P-MSC-EV-induced functional improvements of senescent fibroblasts. MiR-145-5p mimics simulated the effects of P-MSC-EVs on functional improvements of fibroblasts by suppressing the expression of cyclin-dependent kinase inhibitor 1A and activating the extracellular signal regulated kinase (Erk)/protein kinase B (Akt) signaling pathway. Furthermore, local application of miR-145-5p agomir mimicked the effects of P-MSC-EVs on wound healing. These results suggest that P-MSC-EVs accelerate diabetic wound healing by improving the function of senescent fibroblasts through the transfer of miR-145-5p, which targets cyclin-dependent kinase inhibitor 1A to activate the Erk/Akt signaling pathway. P-MSC-EVs are promising therapeutic candidates for diabetic wound treatment.

Depletion of growth differentiation factor 15 (GDF15) leads to mitochondrial dysfunction and premature senescence in human dermal fibroblasts.

Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine also known as a mitokine; however, its role in mitochondrial homeostasis and cellular senescence remained elusive. We show here that knocking down GDF15 expression in human dermal fibroblasts induced mitochondrial dysfunction and premature senescence, associated with a distinct senescence-associated secretory phenotype. Fibroblast-specific loss of GDF15 expression in a model of 3D reconstructed human skin induced epidermal thinning, a hallmark of skin aging. Our results suggest GDF15 to play a so far undisclosed role in mitochondrial homeostasis to delay both the onset of cellular senescence and the appearance of age-related changes in a 3D human skin model.

Phytocannabinoids Stimulate Rejuvenation and Prevent Cellular Senescence in Human Dermal Fibroblasts

In light of the increased popularity of phytocannabinoids (pCBs) and their appearance in beauty products without rigorous research on their rejuvenation efficacy, we decided to investigate the potential role of pCBs in skin rejuvenation. Utilizing healthy and stress-induced premature senescent (SIPS) CCD-1064Sk skin fibroblasts, the effects of pCBs on cellular viability, functional activity, metabolic function, and nuclear architecture were tested. Both delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) within the range of 0.5 µM to 2.0 µM increased cell growth in a dose-dependent manner while significantly decreasing senescence as measured by beta-galactosidase activity. Utilizing a scratch assay, both THC and CBD (2.0 µM) significantly improved wound healing in both healthy and SIPS fibroblasts. THC and CBD altered nuclear architecture and mRNA levels of cell cycle regulators and genes involved in ECM production. Subsequently, we found ELN, Cyclin D1, PCNA, and BID protein levels altered by SIPS but ameliorated after pCBs exposure in human dermal fibroblasts. Lastly, we compared the efficacy of THC and CBD with common anti-aging nutrient signaling regulators in replicative senescent adult human dermal fibroblasts, CCD-1135Sk. Both THC and CBD were found to improve wound healing better than metformin, rapamycin, and triacetylresveratrol in replicative senescent CCD-1135Sk fibroblasts. Therefore, pCBs can be a valuable source of biologically active substances used in cosmetics, and more studies using clinical trials should be performed to confirm the efficacy of phytocannabinoids.

Promitotic Action of Oenothera biennis on Senescent Human Dermal Fibroblasts

Accumulation of senescent dermal fibroblasts drives skin aging. The reactivation of proliferation is one strategy to modulate cell senescence. Recently, we reported the exact chemical composition of the hydrophilic extract of Oenothera biennis cell cultures (ObHEx) and we showed its skin anti-aging properties. The aim of this work is to assess its biological effect specifically on cell senescence. ObHEx action has been evaluated on normal human dermal fibroblasts subjected to stress-induced premature senescence (SIPS) through an ultra-deep proteomic analysis, leading to the most global senescence-associated proteome so far. Mass spectrometry data show that the treatment with ObHEx re-establishes levels of crucial mitotic proteins, strongly downregulated in senescent cells. To validate our proteomics findings, we proved that ObHEx can, in part, restore the activity of 'senescence-associated-ß-galactosidase', the most common hallmark of senescent cells. Furthermore, to assess if the upregulation of mitotic protein levels translates into a cell cycle re-entry, FACS experiments have been carried out, demonstrating a small but significative reactivation of senescent cell proliferation by ObHEx. In conclusion, the deep senescence-associated global proteome profiling published here provides a panel of hundreds of proteins deregulated by SIPS that can be used by the community to further understand senescence and the effect of new potential modulators. Moreover, proteomics analysis pointed to a specific promitotic effect of ObHEx on senescent cells. Thus, we suggest ObHEx as a powerful adjuvant against senescence associated with skin aging.

UV-induced senescence of human dermal fibroblasts restrained by low-stiffness matrix by inhibiting NF-κB activation

• PDMS substrates with tunable stiffness coated by fibronectin are rational designed and fabricated. • HDFs were more sensitive to UV induced ROS accumulation and cell senescence on stiff substrates. • Soft substrates significantly reduced UV induced ROS production and cell senescence. • ECM stiffness plays a significant regulatory role on HDFs senescence. As a hallmark of skin ageing, senescent human dermal fibroblasts (HDFs) are known to lose the ability to divide. However, they can still interact with their cellular environment and the surrounding matrix. As the skin ages, the progressive slowing down of HDFs function decreases the skin's structural integrity, which is more serious than if there is the dermal collagen matrix eroded. This leads to matte r s of the unbalanced barrier under the skin, skin fragility, inadequate wound healing, as well as other cosmetic issues. It is also well documented that skin ageing comes with significant stiffness increases. Therefore, understanding the interactions between HDFs and the surrounding microenvironments during senescence may provide insights into skin ageing. Here we aim to investigate matrix stiffness' effect on HDF senescence and elucidate possible mechanisms that make HDFs senescent. In our experiments, HDFs were cultivated on Polydimethylsiloxane (PDMS) with various stiffnesses and exposed to UV light to trigger senescence. Results show that HDFs are significantly affected by senescence when cultured on a matrix with stiffness. However, the cells are not significantly affected when cultured on a low stiffness matrix. The following characterization revealed cells cultured on stiff substrates under UV exposure had stimulated the nucleus factor kappa-B (NF-κB) activation. In contrast, cells on a matrix of softness only displayed low activation of NF-κB. NF-κB activity suppression with ammonium pyrrolidine dithiocarbamate (PDTC) decreases UV-induced HDFs senescence on stiff substrates. Taken together, we demonstrated that soft matrix defends HDFs against ultraviolet-induced senescence by inhibiting the activation of NF-κB.

Replicative Senescence-Associated LINE1 Methylation and LINE1-Alu Expression Levels in Human Endothelial Cells

One of the main challenges of current research on aging is to identify the complex epigenetic mechanisms involved in the acquisition of the cellular senescent phenotype. Despite some evidence suggested that epigenetic changes of DNA repetitive elements, including transposable elements (TE) sequences, are associated with replicative senescence of fibroblasts, data on different types of cells are scarce. We previously analysed genome-wide DNA methylation of young and replicative senescent human endothelial cells (HUVECs), highlighting increased levels of demethylated sequences in senescent cells. Here, we aligned the most significantly demethylated single CpG sites to the reference genome and annotated their localization inside TE sequences and found a significant hypomethylation of sequences belonging to the Long-Interspersed Element-1 (LINE-1 or L1) subfamilies L1M, L1P, and L1HS. To verify the hypothesis that L1 demethylation could be associated with increased transcription/activation of L1s and/or Alu elements (non-autonomous retroelements that usually depend on L1 sequences for reverse transcription and retrotransposition), we quantified the RNA expression levels of both L1 (generic L1 elements or site-specific L1PA2 on chromosome 14) and Alu elements in young and senescent HUVECs and human dermal fibroblasts (NHDFs). The RNA expression of Alu and L1 sequences was significantly increased in both senescent HUVECs and NHDFs, whereas the RNA transcript of L1PA2 on chromosome 14 was not significantly modulated in senescent cells. Moreover, we found an increased amount of TE DNA copies in the cytoplasm of senescent HUVECs and NHDFs. Our results support the hypothesis that TE, which are significantly increased in senescent cells, could be retrotranscribed to DNA sequences.

517 Regulation of the lipidome and lipid metabolism in prematurely senescent human dermal fibroblasts

A wide range of environmental factors (e.g. UV radiation, pollution) challenge skin homeostasis and it’s prolonged imbalance accelerates skin aging. Aged skin is associated with accumulation of senescent cells which harbor damaged biomolecules and expose danger signals and inflammatory mediators. Prolonged tissue presence of senescent cells negatively affects their microenvironment and contributes to age related tissue decline. Global lipidomics with an UHPLC triple quadrupole MS/MS method confirmed previously reported increase of lysophospholipids in stress-induced premature senescent (SIPS) fibroblasts in vitro and additionally revealed that phospholipids are not the only senescence regulated lipids.