The impact of cellular senescence in skin ageing: A notion of mosaic and therapeutic strategies.

Cellular senescence is now recognized as one of the nine hallmarks of ageing. Recent data show the involvement of senescent cells in tissue ageing and some age-related diseases. Skin represents an ideal model for the study of ageing. Indeed, skin ageing varies between individuals depending on their chronological age but also on their exposure to various exogenous factors (mainly ultraviolet rays). If senescence traits can be detected with ageing in the skin, the senescent phenotype varies among the various skin cell types. Moreover, the origin of cellular senescence in the skin is still unknown, and multiple origins are possible. This reflects the mosaic of skin ageing. Senescent cells can interfere with their microenvironment, either via the direct secretion of factors (the senescence-associated secretory phenotype) or via other methods of communication, such as extracellular vesicles. Knowledge regarding the impact of cellular senescence on skin ageing could be integrated into dermatology research, especially to limit the appearance of senescent cells after photo(chemo)therapy or in age-related skin diseases. Therapeutic approaches include the clearance of senescent cells via the use of senolytics or via the cooperation with the immune system.

Toutfaire M ，Bauwens E ，Debacq-Chainiaux F 《-》

Flavonoids in Skin Senescence Prevention and Treatment.

Domaszewska-Szostek A ，Puzianowska-Kuźnicka M ，Kuryłowicz A 《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》

Senolytics decrease senescent cells in humans: Preliminary report from a clinical trial of Dasatinib plus Quercetin in individuals with diabetic kidney disease.

Senescent cells, which can release factors that cause inflammation and dysfunction, the senescence-associated secretory phenotype (SASP), accumulate with ageing and at etiological sites in multiple chronic diseases. Senolytics, including the combination of Dasatinib and Quercetin (D + Q), selectively eliminate senescent cells by transiently disabling pro-survival networks that defend them against their own apoptotic environment. In the first clinical trial of senolytics, D + Q improved physical function in patients with idiopathic pulmonary fibrosis (IPF), a fatal senescence-associated disease, but to date, no peer-reviewed study has directly demonstrated that senolytics decrease senescent cells in humans. In an open label Phase 1 pilot study, we administered 3 days of oral D 100 mg and Q 1000 mg to subjects with diabetic kidney disease (N = 9; 68·7 ± 3·1 years old; 2 female; BMI:33·9 ± 2·3 kg/m2; eGFR:27·0 ± 2·1 mL/min/1·73m2). Adipose tissue, skin biopsies, and blood were collected before and 11 days after completing senolytic treatment. Senescent cell and macrophage/Langerhans cell markers and circulating SASP factors were assayed. D + Q reduced adipose tissue senescent cell burden within 11 days, with decreases in p16INK4A-and p21CIP1-expressing cells, cells with senescence-associated β-galactosidase activity, and adipocyte progenitors with limited replicative potential. Adipose tissue macrophages, which are attracted, anchored, and activated by senescent cells, and crown-like structures were decreased. Skin epidermal p16INK4A+ and p21CIP1+ cells were reduced, as were circulating SASP factors, including IL-1α, IL-6, and MMPs-9 and -12. "Hit-and-run" treatment with senolytics, which in the case of D + Q have elimination half-lives <11 h, significantly decreases senescent cell burden in humans. FUND: NIH and Foundations. ClinicalTrials.gov Identifier: NCT02848131. Senescence, Frailty, and Mesenchymal Stem Cell Functionality in Chronic Kidney Disease: Effect of Senolytic Agents.

Hickson LJ ，Langhi Prata LGP ，Bobart SA ，Evans TK ，Giorgadze N ，Hashmi SK ，Herrmann SM ，Jensen MD ，Jia Q ，Jordan KL ，Kellogg TA ，Khosla S ，Koerber DM ，Lagnado AB ，Lawson DK ，LeBrasseur NK ，Lerman LO ，McDonald KM ，McKenzie TJ ，Passos JF ，Pignolo RJ ，Pirtskhalava T ，Saadiq IM ，Schaefer KK ，Textor SC ，Victorelli SG ，Volkman TL ，Xue A ，Wentworth MA ，Wissler Gerdes EO ，Zhu Y ，Tchkonia T ，Kirkland JL ... -  《EBioMedicine》

Attenuation of intrinsic ageing of the skin via elimination of senescent dermal fibroblasts with senolytic drugs.

Skin ageing is caused by numerous factors that result in structural and functional changes in cutaneous components. Research has shown that senescent cells are known to accumulate in skin ageing, however, the role of senescent cells in skin ageing has not been defined. To elucidate the role of the senescent cell in skin ageing, we evaluated the effect of known senolytic drugs on senescent dermal fibroblasts. Primary human dermal fibroblasts (HDFs) were induced to senescence by long-term passaging, UV irradiation, and H2 O2 treatment. Cell viability was measured after treatment of ABT-263 and ABT-737 on HDFs. Young and aged hairless mice were intradermally injected with drugs or vehicle on the dorsal skin for 10 days. Skin specimens were obtained and reverse-transcription quantitative PCR, western blotting, and histological analysis were performed. We found that ABT-263 and ABT-737 induced selective clearance of senescent dermal fibroblasts, regardless of the method of senescence induction. Aged mouse skin treated with ABT-263 or ABT-737 showed increased collagen density, epidermal thickness, and proliferation of keratinocytes, as well as decreased senescence-associated secretory phenotypes, such as MMP-1 and IL-6. Taken together, our results indicate that selective clearance of senescent skin cells can attenuate and improve skin ageing phenotypes and that senolytic drugs may be of potential use as new therapeutic agents for treating ageing of the skin.

Kim H ，Jang J ，Song MJ ，Kim G ，Park CH ，Lee DH ，Lee SH ，Chung JH ... -  《-》

Short senolytic or senostatic interventions rescue progression of radiation-induced frailty and premature ageing in mice.

Cancer survivors suffer from progressive frailty, multimorbidity, and premature morbidity. We hypothesise that therapy-induced senescence and senescence progression via bystander effects are significant causes of this premature ageing phenotype. Accordingly, the study addresses the question whether a short anti-senescence intervention is able to block progression of radiation-induced frailty and disability in a pre-clinical setting. Male mice were sublethally irradiated at 5 months of age and treated (or not) with either a senolytic drug (Navitoclax or dasatinib + quercetin) for 10 days or with the senostatic metformin for 10 weeks. Follow-up was for 1 year. Treatments commencing within a month after irradiation effectively reduced frailty progression (p<0.05) and improved muscle (p<0.01) and liver (p<0.05) function as well as short-term memory (p<0.05) until advanced age with no need for repeated interventions. Senolytic interventions that started late, after radiation-induced premature frailty was manifest, still had beneficial effects on frailty (p<0.05) and short-term memory (p<0.05). Metformin was similarly effective as senolytics. At therapeutically achievable concentrations, metformin acted as a senostatic neither via inhibition of mitochondrial complex I, nor via improvement of mitophagy or mitochondrial function, but by reducing non-mitochondrial reactive oxygen species production via NADPH oxidase 4 inhibition in senescent cells. Our study suggests that the progression of adverse long-term health and quality-of-life effects of radiation exposure, as experienced by cancer survivors, might be rescued by short-term adjuvant anti-senescence interventions.

Fielder E ，Wan T ，Alimohammadiha G ，Ishaq A ，Low E ，Weigand BM ，Kelly G ，Parker C ，Griffin B ，Jurk D ，Korolchuk VI ，von Zglinicki T ，Miwa S ... -  《eLife》