Senescence-associated Secretory Phenotype Components Research Articles

A new model and precious tool to study molecular mechanisms of macrophage aging.

The accumulation of senescent cells, characterized by a senescence-associated secretory phenotype (SASP), contributes to chronic inflammation and age-related diseases (ARD). During aging, macrophages can adopt a senescent-like phenotype and an altered function, which promotes senescent cell accumulation. In the context of aging and ARD, controlling the resolution of the inflammatory response and preventing chronic inflammation, especially by targeting macrophages, must be a priority. Aging being a dynamic process, we developed a model of in vitro murine peritoneal macrophage aging. Our results show that macrophages cultured for 7 or 14 days exhibit a senescence-like phenotype: proliferation decrease, the levels of cyclin-dependent kinase inhibitors p16INK4A and p21CIP1 and of pro-inflammatory SASP components (MCP-1, IL-6, IL-1β, TNF-α, and MMP-9) increase, phagocytosis capacity decline and glycolytic activity is induced. In our model, chronic treatment with CB3, a thioredoxin-1 mimetic anti-inflammatory peptide, completely prevents p21CIP1 increase and enables day 14 macrophages to maintain proliferative activity.We describe a new model of macrophage aging with a senescence-like phenotype associated with inflammatory, metabolic and functional perturbations. This model is a valuable tool for characterizing macrophage aging mechanisms and developing innovative strategies with promising therapeutical purpose in limiting inflammaging and ARD.

Prognostic Significance and Biologic Associations of Senescence-Associated Secretory Phenotype Biomarkers in Heart Failure.

The role of cellular senescence in human heart failure (HF) remains unclear. The senescence-associated secretory phenotype (SASP) is composed of proteins released by senescent cells. We assessed the prognostic significance and biologic pathways associated with the SASP in human HF using a plasma proteomics approach. We measured 25 known SASP proteins among 2248 PHFS (Penn HF Study) participants using the SOMAScan V4 assay. We extracted the common variance in these proteins to generate SASP factor scores and assessed the relationship between these SASP factor scores and (1) all-cause death and (2) the composite of death or HF hospital admission. We also assessed the relationship of each SASP factor to 4746 other proteins, correcting for multiple comparisons, followed by pathway analyses. Two SASP factors were identified. Both factors were associated with older age, lower estimated glomerular filtration rate, and more advanced New York Heart Association class, among other clinical variables. Both SASP factors exhibited a significant positive association with the risk of death independent of the Meta-Analysis of Global-Group in Chronic HF score and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels. The 2 identified SASP factors were associated with 1201 and 1554 proteins, respectively, belonging to various pathways including the coagulation system, complement system, acute phase response signaling, and retinoid X receptor-related pathways that regulate cell metabolism. Increased SASP components are independently associated with adverse outcomes in HF. Biologic pathways associated with SASP are predominantly related to coagulation, inflammation, and cell metabolism.

Nicotine induces senescence in spermatogonia stem cells by disrupting homeostasis between circadian oscillation and rhythmic mitochondrial dynamics via the SIRT6/Bmal1 pathway

Infertility is intricately linked with alterations in circadian rhythms along with physiological decline and stem cell senescence. Yet, the direct involvement of circadian mechanisms in nicotine-induced injury to the testes, especially the senescence of spermatogonia stem cells (SSCs), is not well comprehended. This study revealed that nicotine exposure induced testis injury by triggering SSCs senescence along with the upregulation of senescence marker genes and senescence-associated secretory phenotype components. Moreover, nicotine treatment caused mitochondrial hyper-fusion, increased oxidative stress, and DNA damage. Exposure to nicotine was found to suppress the expression of sirtuin 6 (SIRT6), which accelerated the senescence of spermatogonia stem cells (SSCs). This acceleration led to increased acetylation of brain and muscle ARNT-like protein (Bmal1), consequently reducing the expression of Bmal1 protein. Conversely, the overexpression of Bmal1 alleviated mitochondrial hyper-fusion and senescence phenotypes induced by nicotine. Overall, this study unveiled a novel molecular mechanism behind nicotine-induced disorders in spermatogenesis and highlighted the SIRT6/Bmal1 regulatory pathway as a potential therapeutic target for combating nicotine-associated infertility.

The impact of the senescent microenvironment on tumorigenesis: Insights for cancer therapy.

The growing global burden of cancer, especially among people aged 60 years and over, has become a key public health issue. This trend suggests the need for a deeper understanding of the various cancer types in order to develop universally effective treatments. A prospective area of research involves elucidating the interplay between the senescent microenvironment and tumor genesis. Currently, most oncology research focuses on adulthood and tends to ignore the potential role of senescent individuals on tumor progression. Senescent cells produce a senescence-associated secretory phenotype (SASP) that has a dual role in the tumor microenvironment (TME). While SASP components can remodel the TME and thus hinder tumor cell proliferation, they can also promote tumorigenesis and progression via pro-inflammatory and pro-proliferative mechanisms. To address this gap, our review seeks to investigate the influence of senescent microenvironment changes on tumor development and their potential implications for cancer therapies.

The role of miR-222-2p in exosomes secreted by hexavalent chromium-induced premature senescent hepatocytes as a SASP component

With the development of world industrialization, the environmental pollution of hexavalent chromium [Cr(VI)] is becoming an increasingly serious problem. In particular, the mechanisms by which long-term and low-dose exposure to Cr(VI) leading the development of related cancers are not well understood. As senescent cells gradually lose their ability to proliferate and divide, they will not be malignantly transformed. However, Senescence-associated secretory phenotype (SASP) released by senescent cells into the cellular microenvironment can act on neighboring cells. Since SASP has a bidirectional regulatory role in the malignant transformation of cells. Hence, It is very necessary to identified the composition and function of SASP which secreted by Cr(VI) induced senescent L02 hepatocytes (S-L02). Exosomes, a vesicle-like substances released extracellularly after the fusion of intracellular multivesicular bodies with cell membrane, are important components of SASP and contain a large number of microRNAs (miRNAs). By establishing Cr(VI)-induced S-L02 model, we collected the exosomes from the supernatants of S-L02 and L02 culture medium respectively, and screened out the highly expressed miRNAs in the exosomes of S-L02, namely the new SASP components. Among them, the increase of miR-222-5p was the most significant. It was validated that as SASP, miR-222-5p can inhibit the proliferation of L02 and S-L02 hepatocytes and at the same time accelerate the proliferation and migration ability of HCC cells. Further mechanistic studies revealed that miR-222-5p attenuated the regulatory effect of protein phosphatase 2A subunit B isoform R2-α (PPP2R2A) on Akt via repressing its target gene PPP2R2A, causing reduced expressions of forkhead box O3 (FOXO3a), p27 and p21, and finally increasing the proliferation of HCC cells after diminishing the negative regulation of on cell cycle. This study certainly provides valuable laboratory evidence as well as potential therapeutic targets for the prevention and further personalized treatment of Cr(VI)-associated cancers.

Attenuation of pro-tumorigenic senescent secretory phenotype by StN, a novel derivative of stevioside, potentiates its inhibitory activity on hepatocellular carcinoma

Ent-13-Hydroxy-15-kaurene-19-acid N-Methylpiperazine Ethyl Ester (StN) is a novel derivative of the natural diterpene stevioside isolated from Stevia rebaudiana (Bertoni). In this study, we examined the effects of StN against hepatocellular carcinoma (HCC) in vitro and in vivo as well as its anticancer mechanisms by inhibiting proliferation and regulating the senescence-associated secretory phenotype (SASP). We showed that StN significantly inhibited HCC cell proliferation by inducing cellular senescence, as observed by increased senescence-associated β-galactosidase activity and cell cycle arrest. Mechanistically, StN impaired lysosomal stability and triggered the release of cathepsin B from the lysosomes into the nucleus where it promoted DNA damage. Cathepsin B-mediated DNA damage contributed to cellular senescence triggered by StN. Meanwhile, StN transcriptionally suppressed multiple pro-inflammatory SASP components, including IL-6, IL-1α, IL-1β, and IL-8, resulting in the reduction of pro-tumorigenic impact of SASP. Further study revealed that StN inactivated NF-κB and PI3K/Akt signaling, which significantly accounted for its inhibition on the SASP factors. In HCC xenograft mice, administration of StN significantly suppressed tumor growth, while no significant toxicity was detected. This study demonstrates a novel mechanism that suppressing the SASP by StN in senescent cells potentiates its anticancer efficacy, thus defining a potential compound for cancer treatment.

Abstract 15962: Validation of the Senescence-Associated Secretome to Predict Mortality in Patients With Degenerative Aortic Valve Stenosis

Introduction: The senescence-associated secretory phenotype (SASP) is a potential driver of age-related risk reflecting advanced biological aging. Circulating SASP components include pro-inflammatory cytokines, growth modulators and matrix remodelling proteases. Aortic valve stenosis (AVS) is the prototypical inflammatory age-associated cardiovascular disease. Hypothesis: To identify circulating SASP components with an impact on prognosis in elderly pts with AVS. Methods: In a derivation cohort (n=120), circulating levels of 24 SASP components were measured using Luminex Multiplex ELISA, before undergoing TAVR. ROC curves and Youden-index derived optimal cut-off values were used to assess the predictive power of each SASP for long-term mortality. In a validation cohort (n=198), the significant predictors of mortality identified in the derivation cohort, as well as a panel of 3 independent predictors in multivariate analyses, were prospectively validated. Results: In the derivation cohort, 9 out of 24 SASP components significantly predicted mortality in univariate analyses with AUC>0.62; only 3 (GDF-15, ICAM-1, and osteoprotegerin) remained independent predictors in multivariate analyses (all p<0.03). All 3 were confirmed as significant independent predictors of mortality in the validation cohort (see AUC curves). After adjustment for clinical parameters, a score based on the cumulative number of these 3 SASP components showed a substantial increase in long-term mortality after TAVR for each additional positive marker (see KM-curves). Conclusions: This study validates high levels of 3 SASP components reflecting different pathophysiological pathways of senescence as independent predictors of long-term mortality in AVS. Their cumulative occurrence provides a deeply improved discrimination power and, may serve as a much needed risk stratification tool in elderly patients with AVS undergoing TAVR.

Combination of PARP inhibitor and CDK4/6 inhibitor modulates cGAS/STING-dependent therapy-induced senescence and provides "one-two punch" opportunity with anti-PD-L1 therapy in colorectal cancer.

Although PARP inhibitor (PARPi) has been proven to be a promising anticancer drug in cancer patients harboring BRCA1/2 mutation, it provides limited clinical benefit in colorectal cancer patients with a low prevalence of BRCA1/2 mutations. In our study, we found PARPi talazoparib significantly induced cellular senescence via inhibiting p53 ubiquitination and activating p21. Furthermore, CDK4/6i palbociclib amplified this therapy-induced senescence (TIS) in vitro and in vivo. Mechanistically, talazoparib and palbociclib combination induced senescence-associated secretory phenotype (SASP), and characterization of SASP components revealed type I interferon (IFN)-related mediators, which were amplified by cGAS/STING signaling. More importantly, RNA sequencing data indicated that combination therapy activated T cell signatures and combination treatment transformed the tumor microenvironment (TME) into a more antitumor state with increased CD8 T cells and natural killer (NK) cells and decreased macrophages and granulocytic myeloid-derived suppressor cells (G-MDSCs). Moreover, clearance of the TIS cells by αPD-L1 promoted survival in immunocompetent mouse colorectal cancer models. Collectively, we elucidated the synergistic antitumor and immunomodulatory mechanisms of the talazoparib-palbociclib combination. Further combination with PD-L1 antibody might be a promising "one-two punch" therapeutic strategy for colorectal cancer patients.

Targeting cellular senescence: A promising approach in respiratory diseases.

Cellular senescence serves as a significant tumor suppression mechanism in mammals. Cellular senescence is induced in response to various stressors and acts as a safeguard against the uncontrolled proliferation of damaged cells that could lead to malignant transformation. Senescent cells also exhibit a distinctive feature known as the senescence-associated secretory phenotype (SASP), wherein they secrete a range of bioactive molecules, including pro-inflammatory cytokines, growth factors, and proteases. These SASP components have both local and systemic effects, influencing the surrounding microenvironment and distant tissues, and have been implicated in the processes of tissue aging and the development of chronic diseases. Recent studies utilizing senolysis models have shed light on the potential therapeutic implications of targeting senescent cells. The targeting of senescent cell may alleviate the detrimental effects associated with cellular senescence and its SASP components. Senolytics have shown promise in preclinical studies for treating age-related pathologies and chronic diseases, including cancer, cardiovascular disorders, and neurodegenerative conditions. Respiratory diseases have emerged as a significant global health concern, responsible for a considerable number of deaths worldwide. Extensive research conducted in both human subjects and animal models has demonstrated the involvement of cellular senescence in the pathogenesis of respiratory diseases. Chronic pulmonary conditions such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis have been linked to the accumulation of senescent cells. This review aims to present the findings from research on respiratory diseases that have utilized systems targeting senescent cells and to identify potential therapeutic strategies for the clinical management of these conditions. Geriatr Gerontol Int 2024; 24: 60-66.

#5865 BET INHIBITION DIMINISHES CELLULAR SENESCENCE IN CULTURED TUBULAR EPITHELIAL CELLS

Abstract Background and Aims Chronic kidney disease (CKD) can be considered an age-related disorder. Recent studies have shown the involvement of the activation of cellular senescence mechanisms in the kidney and aging. Intensive research to develop pharmacological approaches targeting cellular senescence is under investigation. Among novel therapeutic options, epigenetic drugs, such as bromodomain and extra terminal BET inhibitors, are being widely explored in proliferative, immune and chronic inflammatory diseases, including CKD. These drugs regulate transcription activation of cell cycle control and proinflammatory factors. There are not studies about the potential effect of BET inhibitors on cellular senescence in the kidney despite the fact that tubular epithelial cells are frequently implicated in kidney senescence. Method To study this, we evaluate the effect of JQ1, a BET inhibitor, on cellular senescence in primary cell culture of murine tubular epithelial cells (TECs) using Adriamycin as a senescence inducer verified by B-galactosidase assay. Next, we evaluated the effect of JQ1 on gene expression levels of cell cycle markers, components of senescence-associated secretory phenotype (SASP) as well as anti-apoptotic and antioxidant markers, all of them related to senescence program. Results Our results indicated that JQ1 significantly decreased Adriamycin-induced p21 gene upregulation, a primordial cell cycle arrest factor. This BET inhibitor also downregulated SAPS genes, such as Tgfb1, Il1b, Ctgf, Ccl2 and Il6 overexpression in Adriamycin-treated tubular cells. Likewise, anti-apoptotic Bcl-xl and antioxidant factors Cat, Hmox-1, Nox-4 and Nrf2 mRNA levels were significantly restored by JQ1. Conclusion In conclusion, the present study highlights the use of JQ1 as a therapeutic option to ameliorate tubular cellular senescence-associated markers. These data support the potential use of BET inhibitors in chronic kidney diseases.

#3612 STING IS INVOLVED IN THE CELLULAR SENESCENCE PROCESS ASSOCIATED WITH RENAL AGING

Abstract Background and Aims Cellular senescence is an adaptative process in response to damage or stress. It consists of a cell-cycle-arrest (CCA) alternatively to the programmed cell death process, which is necessary for the regeneration of damaged tissues. However, permanent senescence promotes an aberrant inflammatory response associated to chronic diseases, fibrosis and aging. One of the mechanisms which triggers cellular senescence is the DNA damage response (DDR) activation, that leads to the emergence of a cellular senescence-associated secretory phenotype (SASP), inflammation and fibrosis. Sting is a detection protein of pathogenic DNA derived from cellular damage and genotoxic and environmental stresses, starting an innate immune response and inflammation. A deregulated DDR response and thus the process of senescence itself, are also able to activate Sting. Nevertheless, the role of Sting in senescence associated to renal aging is an unknown fact. The aim of this study is to evaluate the role of STING in aging-associated pathophysiological changes in the kidney. Method Studies were carried out in C57BL76 mice (wild type mice) and in mice with a phenotype deficient in the Sting gene (KO-Sting), of different ages: 3 (young) and 18 (aged) months. Renal function parameters, histology and markers of kidney damage, and activation of cellular senescence in presence or absence of Sting were studied. Results C57BL76 mice of 18 month presented renal dysfunction and fibrosis that was not observed in KO-Sting mice of the same age. Interestingly, 18 months wild-type mice showed an activation of the Sting pathway, characterized by increased transcriptional levels of Ifit1, Oasl2, Usp19 and Mx2. Moreover, the activation of STING pathway was associated to activation of cellular senescence mechanisms, including elevated renal gene expression of SASP components, such as Ccl2, Ccn2, Il1β, Il6, Pai1 or Tgf-β. Importantly, in Sting KO mice of 18 months, DNA damage response was not activated (no increase in ɣH2AX) and cell cycle arrest was not induced, as determined by the p21 and p16 markers. In addition, SAPS gene expression remained at basal levels in aged KO-Sting mice. However, Klotho gene expression levels are downregulated in all 18-month-old mice, wild type and KO mice. Conclusion In conclusion, these findings suggest that the absence of STING prevents age-related renal cellular senescence in a Klotho independent manner in a murine experimental model.

Palbociclib-Induced Cellular Senescence Is Modulated by the mTOR Complex 1 and Autophagy.

Despite not dividing, senescent cells acquire the ability to synthesize and secrete a plethora of bioactive molecules, a feature known as the senescence-associated secretory phenotype (SASP). In addition, senescent cells often upregulate autophagy, a catalytic process that improves cell viability in stress-challenged cells. Notably, this "senescence-related autophagy" can provide free amino acids for the activation of mTORC1 and the synthesis of SASP components. However, little is known about the functional status of mTORC1 in models of senescence induced by CDK4/6 inhibitors (e.g., Palbociclib), or the effects that the inhibition of mTORC1 or the combined inhibition of mTORC1 and autophagy have on senescence and the SASP. Herein, we examined the effects of mTORC1 inhibition, with or without concomitant autophagy inhibition, on Palbociclib-driven senescent AGS and MCF-7 cells. We also assessed the pro-tumorigenic effects of conditioned media from Palbociclib-driven senescent cells with the inhibition of mTORC1, or with the combined inhibition of mTORC1 and autophagy. We found that Palbociclib-driven senescent cells display a partially reduced activity of mTORC1 accompanied by increased levels of autophagy. Interestingly, further mTORC1 inhibition exacerbated the senescent phenotype, a phenomenon that was reversed upon autophagy inhibition. Finally, the SASP varied upon inhibiting mTORC1, or upon the combined inhibition of mTORC1 and autophagy, generating diverse responses in cell proliferation, invasion, and migration of non-senescent tumorigenic cells. Overall, variations in the SASP of Palbociclib-driven senescent cells with the concomitant inhibition of mTORC1 seem to depend on autophagy.

Abstract 425: Characterization of TKI-induced drug-tolerant persister cells from a patient-derived cell line

Abstract Introduction: Targeted therapies provide clinical benefits in patients harboring oncogene-driven cancers, but relapses invariably occur. Studies on resistance mechanisms are essential to guide the development of next-generation inhibitors. An increasing number of studies focus on an earlier stage of disease evolution. Resistance may develop from the selection of preexisting resistant cells or by adaptation of drug-tolerant persister (DTP) cells. In this context, our study depicts DTP cells able to survive the initial tyrosine kinase inhibitor (TKI) exposure without harboring genetic changes, in order to identify the vulnerabilities existing in this cell state. Materials and Methods: This project focuses on a patient-derived cell line from the prospective MATCH-R clinical trial (NCT0251782). The model is a non-small cell lung cancer harboring EML4-ALK fusion and ALK C1156Y/G1269A mutation, sensitive to the 3rd generation ALK TKI lorlatinib. In vitro, fully resistant cells were generated by long-term lorlatinib exposure and the acquired resistance mechanism resulted from an epithelial-mesenchymal transition (EMT). DTP cells were generated under shorter drug exposures that eradicate sensitive carcinoma cells. Results and Discussion: Carcinoma cell plasticity drives cell transformation towards a phenotypic state, rendering them more tolerant to drugs. To better characterize this phenotype, we first focused on EMT and observed that DTP cells co-harbored epithelial and mesenchymal markers. We noticed that DTP cells exhibited an intracellular reactive oxygen species (ROS) rate making them dependent on protective oxidation-reduction mechanisms against oxidative stress-related damage. We revealed the overexpression of p21 and p27, known to bind to cyclin-CDK complexes and induce cell-cycle arrest. This dormant phenotype of DTP cells was underlined by a global repressive chromatin state evidenced by enrichment in H3K27me3, H3K36me3 and H3K9me3 marks; the latter mark also being a component of senescence-associated heterochromatin foci. In agreement, a high level of SA-β-gal and senescence-associated secretory phenotype components (CXCL10, PAI-1), evidenced that our DTP model displayed a senescence-like phenotype. We quantified an increase in γH2AX DNA damage foci in DTP cells compared to sensitive cells, in line with the concept that TKI treatment may have a role in DNA repair modulation that ultimately promotes new mutations. Together, our data depicted DTP features that might be relevant to identify drug candidates overcoming resistance (HDAC inhibitors, senolytic drugs and DNA repair inhibitors). Conclusion: We demonstrated potential targetable features of DTP cells. A combination of targeted therapies with DTP drug candidates could represent a therapeutic opportunity to improve the depth of response and delay the emergence of resistance in patients. Citation Format: Floriane Brayé, Francesco Facchinetti, Helena Gerber, Juliette Juigné, Giorgia Guaitoli, Jean-Paul Thiery, Santiago Ponce, Benjamin Besse, Ken A. Olaussen, Luc Friboulet. Characterization of TKI-induced drug-tolerant persister cells from a patient-derived cell line [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 425.

Characteristics of circulating small noncoding RNAs in plasma and serum during human aging.

Aging is a complicated process that triggers age-related disease susceptibility through intercellular communication in the microenvironment. While the classic secretome of senescence-associated secretory phenotype (SASP) including soluble factors, growth factors, and extracellular matrix remodeling enzymes are known to impact tissue homeostasis during the aging process, the effects of novel SASP components, extracellular small noncoding RNAs (sncRNAs), on human aging are not well established. Here, by utilizing 446 small RNA-seq samples from plasma and serum of healthy donors found in the Extracellular RNA (exRNA) Atlas data repository, we correlated linear and nonlinear features between circulating sncRNAs expression and age by the maximal information coefficient (MIC) relationship determination. Age predictors were generated by ensemble machine learning methods (Adaptive Boosting, Gradient Boosting, and Random Forest) and core age-related sncRNAs were determined through weighted coefficients in machine learning models. Functional investigation was performed via target prediction of age-related miRNAs. We observed the number of highly expressed transfer RNAs (tRNAs) and microRNAs (miRNAs) showed positive and negative associations with age respectively. Two-variable (sncRNA expression and individual age) relationships were detected by MIC and sncRNAs-based age predictors were established, resulting in a forecast performance where all R 2 values were greater than 0.96 and root-mean-square errors (RMSE) were less than 3.7 years in three ensemble machine learning methods. Furthermore, important age-related sncRNAs were identified based on modeling and the biological pathways of age-related miRNAs were characterized by their predicted targets, including multiple pathways in intercellular communication, cancer and immune regulation. In summary, this study provides valuable insights into circulating sncRNAs expression dynamics during human aging and may lead to advanced understanding of age-related sncRNAs functions with further elucidation.

Dysregulated lipid metabolism in lymphangioleiomyomatosis pathogenesis as a paradigm of chronic lung diseases.

A chronic inflammatory condition characterizes various lung diseases. Interestingly, a great contribution to inflammation is made by altered lipids metabolism, that can be caused by the deregulation of the mammalian target of rapamycin complex-1 (mTORC1) activity. There is evidence that one of mTOR downstream effectors, the sterol regulatory element-binding protein (SREBP), regulates the transcription of enzymes involved in the de novo fatty acid synthesis. Given its central role in cell metabolism, mTOR is involved in several biological processes. Among those, mTOR is a driver of senescence, a process that might contribute to the establishment of chronic lung disease because the characteristic irreversible inhibition of cell proliferation, associated to the acquisition of a pro-inflammatory senescence-associated secretory phenotype (SASP) supports the loss of lung parenchyma. The deregulation of mTORC1 is a hallmark of lymphangioleiomyomatosis (LAM), a rare pulmonary disease predominantly affecting women which causes cystic remodeling of the lung and progressive loss of lung function. LAM cells have senescent features and secrete SASP components, such as growth factors and pro-inflammatory molecules, like cancer cells. Using LAM as a paradigm of chronic and metastatic lung disease, here we review the published data that point out the role of dysregulated lipid metabolism in LAM pathogenesis. We will discuss lipids' role in the development and progression of the disease, to hypothesize novel LAM biomarkers and to propose the pharmacological regulation of lipids metabolism as an innovative approach for the treatment of the disease.

Eliminating Senescent Cells Can Promote Pulmonary Hypertension Development and Progression.

Senescent cells (SCs) are involved in proliferative disorders, but their role in pulmonary hypertension remains undefined. We investigated SCs in patients with pulmonary arterial hypertension and the role of SCs in animal pulmonary hypertension models. We investigated senescence (p16, p21) and DNA damage (γ-H2AX, 53BP1) markers in patients with pulmonary arterial hypertension and murine models. We monitored p16 activation by luminescence imaging in p16-luciferase (p16LUC/+) knock-in mice. SC clearance was obtained by a suicide gene (p16 promoter-driven killer gene construct in p16-ATTAC mice), senolytic drugs (ABT263 and cell-permeable FOXO4-p53 interfering peptide [FOXO4-DRI]), and p16 inactivation in p16LUC/LUC mice. We investigated pulmonary hypertension in mice exposed to normoxia, chronic hypoxia, or hypoxia+Sugen, mice overexpressing the serotonin transporter (SM22-5-HTT+), and rats given monocrotaline. Patients with pulmonary arterial hypertension compared with controls exhibited high lung p16, p21, and γ-H2AX protein levels, with abundant vascular cells costained for p16, γ-H2AX, and 53BP1. Hypoxia increased thoracic bioluminescence in p16LUC/+ mice. In wild-type mice, hypoxia increased lung levels of senescence and DNA-damage markers, senescence-associated secretory phenotype components, and p16 staining of pulmonary endothelial cells (P-ECs, 30% of lung SCs in normoxia), and pulmonary artery smooth muscle cells. SC elimination by suicide gene or ABT263 increased the right ventricular systolic pressure and hypertrophy index, increased vessel remodeling (higher dividing proliferating cell nuclear antigen-stained vascular cell counts during both normoxia and hypoxia), and markedly decreased lung P-ECs. Pulmonary hemodynamic alterations and lung P-EC loss occurred in older p16LUC/LUC mice, wild-type mice exposed to Sugen or hypoxia+Sugen, and SM22-5-HTT+ mice given either ABT263 or FOXO4-DRI, compared with relevant controls. The severity of monocrotaline-induced pulmonary hypertension in rats was decreased slightly by ABT263 for 1 week but was aggravated at 3 weeks, with loss of P-ECs. Elimination of senescent P-ECs by senolytic interventions may worsen pulmonary hemodynamics. These results invite consideration of the potential impact on pulmonary vessels of strategies aimed at controlling cell senescence in various contexts.

What's New in Musculoskeletal Basic Science.

What's New in Musculoskeletal Basic Science.

Cellular Senescence and Periodontitis: Mechanisms and Therapeutics.

Simple SummaryOral health is increasingly recognized as an important part of overall health. Tooth loss is a contributor to overall musculoskeletal frailty and is closely associated with increased morbidity in the elderly population. Limited intervention exists to alleviate tooth loss associated with periodontitis, other than antibiotics. Mounting evidence suggests that targeting cellular senescence could slow down the fundamental aging process, and thus alleviate a wide range of age-related tissue dysfunctions, likely including tooth loss. Therefore, we feel it might be valuable to review the current understanding of the role and potential mechanisms of senescent cells in oral health with aging.Periodontitis is a chronic inflammatory disease which increases in prevalence and severity in the older population. Aging is a leading risk factor for periodontitis, which exacerbates alveolar bone loss and results in tooth loss in the elderly. However, the mechanism by which aging affects periodontitis is not well understood. There is considerable evidence to suggest that targeting cellular senescence could slow down the fundamental aging process, and thus alleviate a series of age-related pathological conditions, likely including alveolar bone loss. Recently, it has been discovered that the senescent cells accumulate in the alveolar bone and promote a senescence-associated secretory phenotype (SASP). Senescent cells interacting with bacteria, together with secreted SASP components altering the local microenvironment and inducing paracrine effects in neighboring cells, exacerbate the chronic inflammation in periodontal tissue and lead to more alveolar bone loss. This review will probe into mechanisms underlying excessive alveolar bone loss in periodontitis with aging and discuss potential therapeutics for the treatment of alveolar bone loss targeting cellular senescence and the SASP. Inspecting the relationship between cellular senescence and periodontitis will lead to new avenues of research in this field and contribute to developing potential translatable clinical interventions to mitigate or even reverse the harmful effects of aging on oral health.

Cellular senescence is increased in airway smooth muscle cells of elderly persons with asthma.

Senescent cells can drive age-related tissue dysfunction partially via a senescence-associated secretory phenotype (SASP) involving proinflammatory and profibrotic factors. Cellular senescence has been associated with a structural and functional decline during normal lung aging and age-related diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Asthma in the elderly (AIE) represents a major healthcare burden. AIE is associated with bronchial airway hyperresponsiveness and remodeling, which involves increased cell proliferation and higher rates of fibrosis, and resistant to standard therapy. Airway smooth muscle (ASM) cells play a major role in asthma such as remodeling via modulation of inflammation and the extracellular matrix (ECM) environment. Whether senescent ASM cells accumulate in AIE and contribute to airway structural or functional changes is unknown. Lung tissues from elderly persons with asthma showed greater airway fibrosis compared with age-matched elderly persons with nonasthma and young age controls. Lung tissue or isolated ASM cells from elderly persons with asthma showed increased expression of multiple senescent markers including phospho-p53, p21, telomere-associated foci (TAF), as well as multiple SASP components. Senescence and SASP components were also increased with aging per se. These data highlight the presence of cellular senescence in AIE that may contribute to airway remodeling.

Osteoarthritis: Mechanistic Insights, Senescence, and Novel Therapeutic Opportunities.

Osteoarthritis (OA) is the most common joint disease. In the last years, the research community has focused on understanding the molecular mechanisms that led to the pathogenesis of the disease, trying to identify different molecular and clinical phenotypes along with the discovery of new therapeutic opportunities. Different types of cell-to-cell communication mechanisms have been proposed to contribute to OA progression, including mechanisms mediated by connexin43 (Cx43) channels or by small extracellular vesicles. Furthermore, changes in the chondrocyte phenotype such as cellular senescence have been proposed as new contributors of the OA progression, changing the paradigm of the disease. The use of different drugs able to restore chondrocyte phenotype, to reduce cellular senescence and senescence-associated secretory phenotype components, and to modulate ion channel activity or Cx43 appears to be promising therapeutic strategies for the different types of OA. In this review, we aim to summarize the current knowledge in OA phenotypes related with aging and tissue damage and the new therapeutic opportunities currently available.