Unbiased proteomic analysis of extracellular vesicles secreted by senescent human vascular smooth muscle cells reveals their ability to modulate immune cell functions

Atherosclerosis, a common age-related disease, is characterized by intense immunological activity. Atherosclerotic plaque is composed of endothelial cells, vascular smooth muscle cells (VSMCs), lipids and immune cells infiltrating from the blood. During progression of the disease, VSMCs undergo senescence within the plaque and secrete SASP (senescence-associated secretory phenotype) factors that can actively modulate plaque microenvironment. We demonstrated that senescent VSMCs secrete increased number of extracellular vesicles (senEVs). Based on unbiased proteomic analysis of VMSC-derived EVs and of the soluble fraction of SASP (sSASP), more than 900 proteins were identified in each of SASP compartments. Comparison of the composition of VMSC-derived EVs with the SASP atlas revealed several proteins, including Serpin Family F Member 1 (SERPINF1) and Thrombospondin 1 (THBS1), as commonly upregulated components of EVs secreted by senescent VSMCs and fibroblasts. Among soluble SASP factors, only Growth Differentiation Factor 15 (GDF15) was universally increased in the secretome of senescent VSMCs, fibroblasts, and epithelial cells. Bioinformatics analysis of EV proteins distinguished functionally organized protein networks involved in immune cell function regulation. Accordingly, EVs released by senescent VSMCs induced secretion of IL-17, INFγ, and IL-10 by T cells and of TNFα produced by monocytes. Moreover senEVs influenced differentiation of monocytes favoring mix M1/M2 polarization with proinflammatory characteristics. Altogether, our studies provide a complex, unbiased analysis of VSMC SASP and prove that EVs derived from senescent VSMCs influence the cytokine milieu by modulating immune cell activity. Our results strengthen the role of senescent cells as an important inducer of inflammation in atherosclerosis.

Senolytics rejuvenate the reparative activity of human cardiomyocytes and endothelial cells

Background

Senescent cells have emerged as bona fide drivers of ageing and age-related cardiovascular disease, with senescent cells accumulating in the aged heart and following damage/injury. We have shown that removal of senescent cells using senolytics can rejuvenate the regenerative capacity of the aged heart.

Purpose

We investigate the effects of cell senescence and action of the senolytics, Dasatinib (D) and Quercetin (Q), on human cardiomyocyte and endothelial cell viability, survival, proliferation, angiogenesis and senescence in vitro.

Methods

We developed a transwell insert co-culture stress-induced premature senescence model system in vitro. Doxorubicin was used to induce premature senescence to cardiac stromal progenitor cells or HUVECs, which were seeded on the bottom chamber. In separate well plates, untreated cells (non-senescent) were seeded on the bottom chamber and acted as control. Human iPSC-cardiomyocytes (iPSC-CMs) or HUVECs were seeded on the top chamber insert. Co-cultures were left for 7 days and then iPSC-CMs or HUVECs in the top chamber were analysed for viability, proliferation and markers of senescence, and the conditioned medium analysed for SASP factors. The cultures were then treated with D+Q (0.5μM D with 20μM Q) for 3 days to clear the senescent cells in the bottom chamber. Then 7 days later the iPSC-CMs or HUVECs in the top chamber were analysed for viability, proliferation and the markers of senescence, and conditioned medium analysed for SASP factors (total of 17 days).

Results

Co-culture of iPSC-CMs with senescent cells led to decreased iPSC-CM viability (64±11% vs. 100±3% control; p<0.05) and proliferation (5±2% vs. 11±1% control; p<0.05). There was no increased senescence in co-cultured iPSC-CMs. Treatment with senolytics D+Q resulted in rescue of viability (79±23% 17d co-culture+D+Q; 64±9% 17d co-culture; 100±4% 17d control) and proliferation (7±2% 17d co-culture+D+Q; 3±0.3% 17d co-culture; 8±0.3% 17d control). Similar effects were observed with HUVECs, which showed decreased viability (83±5% vs. 100±6% control; p<0.05) and proliferation (21±7% vs. 44±7% control; p<0.05) when co-cultured with senescent HUVECs. Treatment with senolytics ameliorated HUVEC viability (61±22% 17d co-culture+D+Q; 21±12% 17d co-culture; 100±5% 17d control), proliferation (30±5% 17d co-culture+D+Q; 22±4% 17d co-culture; 48±4% 17d control) and angiogenesis (Score relative to control: 1.1±0.5 D+Q conditioned media; 0.2±0.1 senescent cell conditioned media; 1.0±0.3 control media). Luminex analysis of the senescent cell conditioned media revealed upregulation of SASP factors, but the level of SASP factors were reduced with application of D+Q.

Conclusion

We show that D+Q senolytics have therapeutic potential in rejuvenating the reparative activity of cardiomyocytes and endothelial cells. These results open the path to further studies on using senolytic therapy in age-related cardiac deterioration and rejuvenation.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Heart Research UK

Evaluation of the effect of adding a high-fidelity simulation to an existing didactic lecture to teach pharmacy undergraduates the management of sepsis in secondary care

Introduction

Sepsis is potentially life-threatening, requiring rapid identification and treatment. ‘Sepsis Six’ (1) has become the recognised treatment pathway and has traditionally been taught to our undergraduate pharmacy students in didactic fashion. Interactive teaching methods, such as simulation, are the most effective forms of education to improve patient safety (2). Such approaches might be beneficial in the teaching of sepsis management.

Aim

To evaluate the effect of adding simulation-based teaching to an existing didactic lecture on the management of sepsis.

Methods

Year 4 students at the University of Bath (n=92) attended a sepsis lecture given by a teacher practitioner with experience in managing sepsis in March 2020. Students completed an online survey that used Likert scales to evaluate understanding of sepsis and confidence in managing it (see table).

One week later, small groups of students completed a 30-minute simulation using a SimMan ALS ‘patient’ programmed to show physiological signs of sepsis. Simulations were facilitated by a teacher practitioner with experience of operating SimMan ALS. Each group had a brief outlining the required tasks: reviewing the patient; assessing sepsis risk; summarising a treatment plan and priority actions. After the simulation, students underwent de-brief and completed the same online survey a second time. Changes in students’ responses between surveys were analysed using Wilcoxon signed-rank tests in SPSS, therefore data from students who completed only one survey were not included.

Results

26 students completed both surveys (response rate: 28%). Likert scores for questions 1, 2, 4 and 5 were significantly higher following the simulation, indicating improved confidence and knowledge (see table).

Conclusion

Adding a high-fidelity simulation to an existing didactic lecture increased student confidence in identifying and managing sepsis. Self-reported knowledge of sepsis red flags also increased (indicated by the responses to Statement 1). This study should encourage future sepsis teaching to include a blend of didactic and simulated learning. Limitations include the low response rate, evaluation at only one university and reliance on student self-assessment of knowledge.

References

(1) Daniels, R, Nutbeam, T. et al (2019) The Sepsis Manual 5th Edition. UK Sepsis Trust. www.sepsistrust.org

(2) Yu A, Fontana G, Darzi A (2016). Evaluation of Education and Training Interventions for Patient Safety. A report by the Centre for Health Policy at Imperial College London, an academic partner to Health Education England and the Commission on Education and Training for Patient Safety. London.

ATM-deficient neural precursors develop senescence phenotype with disturbances in autophagy

ATM is a kinase involved in DNA damage response (DDR), regulation of response to oxidative stress, autophagy and mitophagy. Mutations in the ATM gene in humans result in ataxi A-Telangiectasia disease (A-T) characterized by a variety of symptoms with neurodegeneration and premature ageing among them. Since brain is one of the most affected organs in A-T, we have focused on senescence of neural progenitor cells (NPCs) derived from A-T reprogrammed fibroblasts. Accordingly, A-T NPCs obtained through neural differentiation of iPSCs in 5% oxygen possessed some features of senescence including increased activity of SA-β-gal and secretion of IL6 and IL8 in comparison to control NPCs. This phenotype of A-T NPC was accompanied by elevated oxidative stress. A-T NPCs exhibited symptoms of impaired autophagy and mitophagy with lack of response to chloroquine treatment. Additional sources of oxidative stress like increased oxygen concentration (20 %) and H₂O₂ respectively aggravated the phenotype of senescence and additionally disturbed the process of mitophagy. In both cases only A-T NPCs reacted to the treatment. We conclude that oxidative stress may be responsible for the phenotype of senescence and impairment of autophagy in A-T NPCs. Our results point to senescent A-T cells as a potential therapeutic target in this disease.

Is senescence-associated β-galactosidase a marker of neuronal senescence?

One of the features of cellular senescence is the activity of senescence-associated- β-galactosidase (SA-β-gal). The main purpose of this study was to evaluate this marker of senescence in aging neurons. We found that cortical neurons exhibited noticeable SA-β-gal activity quite early in culture. Many SA-β-gal-positive neurons were negative for another canonical marker of senescence, namely, double-strand DNA breaks (DSBs). Moreover, DDR signalling triggered by low doses of doxorubicin did not accelerate the appearance of neuronal SA-β-gal. In vivo, we observed pronounced induction of SA-β-gal activity in the hippocampus of 24-month-old mice, which is consistent with previous findings and supports the view that at this advanced age neurons developed a senescence-like phenotype. Surprisingly however, relatively high SA-β-gal activity, probably unrelated to the senescence process, was also observed in much younger, 3-month-old mice. In conclusion, we propose that SA-β-gal activity in neurons cannot be attributed uniquely to cell senescence either in vitro or in vivo. Additionally, we showed induction of REST protein in aging neurons in long-term culture and we propose that REST could be a marker of neuronal senescence in vitro.

NOX4 downregulation leads to senescence of human vascular smooth muscle cells

Senescence is a stress response characterized by an irreversible growth arrest and alterations in certain cell functions. It is believed that both double-strand DNA breaks (DSB) and increased ROS level are the main culprit of senescence. Excessive ROS production is also particularly important in the development of a number of cardiovascular disorders. In this context the involvement of professional ROS-producing enzymes, NADPH oxidases (NOX), was postulated. In contrary to the common knowledge, we have shown that not only increased ROS production but also diminished ROS level could be involved in the induction of senescence.

Accordingly, our studies revealed that stress-induced premature senescence (SIPS) of vascular smooth muscle cells (VSMCs) induced by doxorubicin or H₂O₂, correlates with increased level of DSB and ROS. On the other hand, both SIPS and replicative senescence were accompanied by diminished expression of NOX4. Moreover, inhibition of NOX activity or decrease of NOX4 expression led to permanent growth arrest of VSMCs and secretion of interleukins and VEGF. Interestingly, cells undergoing senescence due to NOX4 depletion neither acquired DSB nor activated DNA damage response. Instead, transient induction of the p27, upregulation of HIF-1alpha, decreased expression of cyclin D1 and hypophosphorylated Rb was observed. Our results showed that lowering the level of ROS-producing enzyme - NOX4 oxidase below physiological level leads to cellular senescence of VSMCs which is correlated with secretion of pro-inflammatory cytokines. Thus the use of specific NOX4 inhibitors for pharmacotherapy of vascular diseases should be carefully considered.

Polyploidy Formation in Doxorubicin-Treated Cancer Cells Can Favor Escape from Senescence

Cancer cells can undergo stress-induced premature senescence, which is considered to be a desirable outcome of anticancer treatment. However, the escape from senescence and cancer cell repopulation give rise to some doubts concerning the effectiveness of the senescence-induced anticancer therapy. Similarly, it is postulated that polyploidization of cancer cells is connected with disease relapse. We postulate that cancer cell polyploidization associated with senescence is the culprit of atypical cell divisions leading to cancer cell regrowth. Accordingly, we aimed to dissociate between these two phenomena. We induced senescence in HCT 116 cells by pulse treatment with doxorubicin and observed transiently increased ploidy, abnormal nuclear morphology, and various distributions of some proteins (e.g., p21, Ki-67, SA-β-galactosidase) in the subnuclei. Doxorubicin-treated HCT 116 cells displayed an increased production of reactive oxygen species (ROS) possibly caused by an increased amount of mitochondria, which are characterized by low membrane potential. A decrease in the level of ROS by Trolox partially protected the cells from polyploidization but not from senescence. Interestingly, a decreased level of ROS prevented the cells from escaping senescence. We also show that MCF7 cells senesce, but this is not accompanied by the increase of ploidy upon doxorubicin treatment. Moreover, they were stably growth arrested, thus proving that polyploidy but not senescence per se enables to regain the ability to proliferate. Our preliminary results indicate that the different propensity of the HCT 116 and MCF7 cells to increase ploidy upon cell senescence could be caused by a different level of the mTOR and/or Pim-1 kinases.

Curcumin-treated cancer cells show mitotic disturbances leading to growth arrest and induction of senescence phenotype

Cellular senescence is recognized as a potent anticancer mechanism that inhibits carcinogenesis. Cancer cells can also undergo senescence upon chemo- or radiotherapy. Curcumin, a natural polyphenol derived from the rhizome of Curcuma longa, shows anticancer properties both in vitro and in vivo. Previously, we have shown that treatment with curcumin leads to senescence of human cancer cells. Now we identified the molecular mechanism underlying this phenomenon. We observed a time-dependent accumulation of mitotic cells upon curcumin treatment. The time-lapse analysis proved that those cells progressed through mitosis for a significantly longer period of time. A fraction of cells managed to divide or undergo mitotic slippage and then enter the next phase of the cell cycle. Cells arrested in mitosis had an improperly formed mitotic spindle and were positive for γH2AX, which shows that they acquired DNA damage during prolonged mitosis. Moreover, the DNA damage response pathway was activated upon curcumin treatment and the components of this pathway remained upregulated while cells were undergoing senescence. Inhibition of the DNA damage response decreased the number of senescent cells. Thus, our studies revealed that the induction of cell senescence upon curcumin treatment resulted from aberrant progression through the cell cycle. Moreover, the DNA damage acquired by cancer cells, due to mitotic disturbances, activates an important molecular mechanism that determines the potential anticancer activity of curcumin.

[Neuronal ageing]

Ageing leads to irreversible alterations in the nervous system, which to various extent impair its functions such as capacity to learn and memory. In old neurons and brain, similarly to what may take place in other cells, there is increased oxidative stress, disturbed energetic homeostasis and metabolism, accumulation of damage in proteins and nucleic acids. Characteristic of old neurons are alterations in plasticity, synaptic transmission, sensitivity to neurotrophic factors and cytoskeletal changes. Some markers of senescence, whose one of them is SA-beta-galactosidase were used to show the process of neuronal ageing both in vitro, and in vivo. Some research suggest that, despite the fact that neurons are postmitotic cells, it is cell cycle proteins which play a certain role in their biology, e.g. differentiation. However, their role in neuronal ageing is not known or explained. Ageing is the serious factor of development of neurodegenerative diseases among others Alzheimer disease.

Primary prevention program clearinghouse : Prevention issue: Journal of pediatric psychology

The Clearinghouse has been redesigned so that whenever possible abstracts are focused on one theme rather than on an assortment of topics. In this Clearinghouse we are pleased to provide the authors' abstracts of articles published in theJournal of Pediatric Psychology special issue on Health Promotion and Problem Prevention in Pediatric Psychology (Vol. 11, No. 2). The articles demonstrate general and specific approaches to health promotion and prevention of injury, death, and disease in children. In addition, we have included a list of the books reviewed in the special issue.Addresses for requesting individual reprints are provided with each abstract. Alternatively you can order the entire special issue from Plenum Press, 233 Spring Street, New York, NY 10013.

Survey of Hawaii physicians' attitudes on health care reform

Hawaii is more important in health care that its size suggests. It is the first state in the U.S. to have mandated employer-funded health insurance for all workers, and to realize near universal coverage for residents. Because of that, the U.S. can benefit from the experience of those who deliver health services to the people of Hawaii. To determine some of the problems in the current system and what physicians see as solutions, a study of the attitudes and experiences of local physicians was conducted.

Normal ventricles in young schizophrenics

The CT scans of 11 schizophrenics and 26 controls were evaluated for both linear (Evan's and cella media ratios) and volume (planimetry and grid ratios) measurements of ventricular size. There were no differences between the two groups on any of the measures obtained. These results are discussed in relation to previous reports showing ventricular enlargement in schizophrenics. The relatively younger age and briefer period of hospitalization in this present sample are suggested as variables possibly associated with these findings.