Vascular smooth muscle cells (VSMCs) in human atherosclerosis manifest extensive DNA damage and activation of the DNA damage response, a pathway that coordinates cell cycle arrest and DNA repair, or ...can trigger apoptosis or cell senescence. Sirtuin 1 deacetylase (SIRT1) regulates cell ageing and energy metabolism and regulates the DNA damage response through multiple targets. However, the direct role of SIRT1 in atherosclerosis and how SIRT1 in VSMCs might regulate atherosclerosis are unknown.
SIRT1 expression was reduced in human atherosclerotic plaques and VSMCs both derived from plaques and undergoing replicative senescence. SIRT1 inhibition reduced DNA repair and induced apoptosis, in part, through reduced activation of the repair protein Nijmegen Breakage Syndrome-1 but not p53. Fat feeding reduced SIRT1 and induced DNA damage in VSMCs. VSMCs from mice expressing inactive truncated SIRT1 (Δex4) showed increased oxidized low-density lipoprotein-induced DNA damage and senescence. ApoE(-/-) mice expressing SIRT1(Δex4) only in smooth muscle cells demonstrated increased DNA damage response activation and apoptosis, increased atherosclerosis, reduced relative fibrous cap thickness, and medial degeneration.
SIRT1 is reduced in human atherosclerosis and is a critical regulator of the DNA damage response and survival in VSMCs. VSMC SIRT1 protects against DNA damage, medial degeneration, and atherosclerosis.
RATIONALE:DNA damage is present in both genomic and mitochondrial DNA in atherosclerosis. However, whether DNA damage itself promotes atherosclerosis, or is simply a byproduct of the risk factors ...that promote atherosclerosis, is unknown.
OBJECTIVE:To examine the effect of DNA damage on atherosclerosis, we studied apolipoprotein (Apo)E mice that were haploinsufficient for the protein kinase ATM (ataxia telangiectasia mutated), which coordinates DNA repair.
METHODS AND RESULTS:ATM/ApoE mice developed accelerated atherosclerosis and multiple features of the metabolic syndrome, including hypertension, hypercholesterolemia, obesity, steatohepatitis, and glucose intolerance. Transplantation with ATM bone marrow attenuated atherosclerosis but not the metabolic syndrome. ATM smooth muscle cells and macrophages showed increased nuclear DNA damage and defective DNA repair signaling, growth arrest, and apoptosis. Metabolomic screening of ATM/ApoE mouse tissues identified metabolic changes compatible with mitochondrial defects, with increased β-hydroxybutyrate but reduced lactate, reduced glucose, and alterations in multiple lipid species. ATM/ApoE mouse tissues showed an increased frequency of a mouse mitochondrial “common” deletion equivalent and reduced mitochondrial oxidative phosphorylation.
CONCLUSIONS:We propose that failure of DNA repair generates defects in cell proliferation, apoptosis, and mitochondrial dysfunction. This in turn leads to ketosis, hyperlipidemia, and increased fat storage, promoting atherosclerosis and the metabolic syndrome. Prevention of mitochondrial dysfunction may represent a novel target in cardiovascular disease.
Community Acute Bacterial Meningitis (CABM) is a rare infectious disease leading to important impairments. Our aim was to describe CABM survivors' quality of life (QOL) 12 months post-CABM and to ...assess its associations with CABM sequelae.
Patients included in the CABM COMBAT cohort were evaluated one year after the CABM episode. Data were collected by questionnaire, via phone calls with the patients. The WHOQOL-BREF was used to measure CABM survivors' QOL. Hierarchical multivariate linear regressions were performed.
Study population was composed of 284 patients. At 12 months, 53.9% (153/284) reported at least incident headache/worsening headache intensity at 12 months post-CABM, and/or incident hearing impairment, and/or unfavourable disability outcome (GOS). Unfavourable disability outcome was associated with lower physical health QOL (B = -30.35, p<0.001), lower mental health QOL (B = -15.31, p<0.001), lower environmental QOL (B = -11.08, p<0.001) and lower social relationships QOL (B = -9.62, p<0.001). Incident headache/worsening headache since meningitis onset was associated with lower psychological health (B = -5.62, p = 0.010). Incident hearing impairment was associated with lower physical QOL (B = -5.34, p = 0.030). Hierarchical regressions showed that CABM impairments significantly increase explanatory power of multivariate models (for physical health R2 change = 0.42, p<0.001, for psychological health R2 change = 0.23, p<0.001, for social relationships R2 change = 0.06, p<0.001 and for environment domain R2 change was 0.15, p<0.001).
12 month-CABM burden is heavy. Early detection and management of CABM impairments should be performed in clinical practice as early as possible to optimize patients' psychological and psychosocial functioning.
NCT01730690.
Although the hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are widely used in atherosclerosis to reduce serum cholesterol, statins have multiple other effects, including direct ...effects on cells of the vessel wall. Recently, DNA damage, including telomere shortening, has been identified in vascular smooth muscle cells (VSMCs) in human atherosclerosis. Although statins reduce DNA damage in vitro, the mechanisms by which they might protect DNA integrity in VSMCs are unknown. We show that human atherosclerotic plaque VSMCs exhibit increased levels of double-stranded DNA breaks and basal activation of DNA repair pathways involving ataxia telangiectasia–mutated (ATM) and the histone H2AX in vivo and in vitro. Oxidant stress induced DNA damage and activated DNA repair pathways in VSMCs. Statin treatment did not reduce oxidant stress or DNA damage but markedly accelerated DNA repair. Accelerated DNA repair required both the Nijmegen breakage syndrome (NBS)-1 protein and the human double minute protein Hdm2, accompanied by phosphorylation of Hdm2, dissociation of NBS-1 and Hdm2, inhibition of NBS-1 degradation, and accelerated phosphorylation of ATM. Statin treatment reduced VSMC senescence and telomere attrition in culture, accelerated DNA repair and reduced apoptosis in vivo after irradiation, and reduced ATM/ATR (ATM and Rad3-related) activity in atherosclerosis. We conclude that statins activate a novel mechanism of accelerating DNA repair, dependent on NBS-1 stabilization and Hdm2. Statin treatment may delay cell senescence and promote DNA repair in atherosclerosis.
Hydrogen sulfide (H2S) is a mediator with demonstrated protective effects for the cardiovascular system. On the other hand, prostaglandin (PG)E2 is involved in vascular wall remodeling by regulating ...matrix metalloproteinase (MMP) activities. We tested the hypothesis that endogenous H2S may modulate PGE2, MMP-1 activity and endogenous tissue inhibitors of MMPs (TIMP-1/-2). This regulatory pathway could be involved in thinning of abdominal aortic aneurysm (AAA) and thickening of saphenous vein (SV) varicosities. The expression of the enzyme responsible for H2S synthesis, cystathionine-γ-lyase (CSE) and its activity, were significantly higher in varicose vein as compared to SV. On the contrary, the endogenous H2S level and CSE expression were lower in AAA as compared to healthy aorta (HA). Endogenous H2S was responsible for inhibition of PGE2 synthesis mostly in varicose veins and HA. A similar effect was observed with exogenous H2S and consequently decreasing active MMP-1/TIMP ratios in SV and varicose veins. In contrast, in AAA, higher levels of PGE2 and active MMP-1/TIMP ratios were found versus HA. These findings suggest that differences in H2S content in AAA and varicose veins modulate endogenous PGE2 production and consequently the MMP/TIMP ratio. This mechanism may be crucial in vascular wall remodeling observed in different vascular pathologies (aneurysm, varicosities, atherosclerosis and pulmonary hypertension).
Although human atherosclerosis is associated with aging, direct evidence of cellular senescence and the mechanism of senescence in vascular smooth muscle cells (VSMCs) in atherosclerotic plaques is ...lacking. We examined normal vessels and plaques by histochemistry, Southern blotting, and fluorescence in situ hybridization for telomere signals. VSMCs in fibrous caps expressed markers of senescence (senescence-associated β-galactosidase SAβG and the cyclin-dependent kinase inhibitors cdkis p16 and p21) not seen in normal vessels. In matched samples from the same individual, plaques demonstrated markedly shorter telomeres than normal vessels. Fibrous cap VSMCs exhibited markedly shorter telomeres compared with normal medial VSMCs. Telomere shortening was closely associated with increasing severity of atherosclerosis. In vitro, plaque VSMCs demonstrated morphological features of senescence, increased SAβG expression, reduced proliferation, and premature senescence. VSMC senescence was mediated by changes in cyclins D/E, p16, p21, and pRB, and plaque VSMCs could reenter the cell cycle by hyperphosphorylating pRB. Both plaque and normal VSMCs expressed low levels of telomerase. However, telomerase expression alone rescued plaque VSMC senescence despite short telomeres, normalizing the cdki/pRB changes. In vivo, plaque VSMCs exhibited oxidative DNA damage, suggesting that telomere damage may be induced by oxidant stress. Furthermore, oxidants induced premature senescence in vitro, with accelerated telomere shortening and reduced telomerase activity. We conclude that human atherosclerosis is characterized by senescence of VSMCs, accelerated by oxidative stress-induced DNA damage, inhibition of telomerase and marked telomere shortening. Prevention of cellular senescence may be a novel therapeutic target in atherosclerosis.
Markers of cell senescence have been identified in both the blood and vessel wall of patients with atherosclerosis. In particular, vascular smooth muscle cells (VSMCs) derived from human plaques show ...numerous features of senescence both in culture and in vivo. This review summarises the evidence for VSMC senescence in atherosclerosis, and outlines the mechanisms and triggers leading to their senescence.
LPP, a LIM protein highly expressed in smooth muscle Gorenne, Isabelle; Nakamoto, Robert K; Phelps, Clayton P ...
American Journal of Physiology: Cell Physiology,
09/2003, Letnik:
285, Številka:
3
Journal Article
Recenzirano
1 Department of Molecular Physiology and
Biological Physics, University of Virginia, Charlottesville, Virginia 22908;
and 2 Huntsman Cancer Institute and Department of
Biology, University of Utah, ...Salt Lake City, Utah 84112
Submitted 31 December 2002
; accepted in final form 16 May 2003
An 80-kDa protein, prominently expressed in smooth muscle, was
microsequenced and identified as LPP, the product of the lipoma-preferred
partner gene (Petit MMR, Mols R, Schoenmakers EFPM, Mandahl N, and Van de Ven
WJM. Genomics 36: 118129, 1996). Using a specific anti-LPP
antibody, we showed, in Western blots and with immunofluorescence microscopy,
the selective expression of LPP in vascular and visceral smooth muscles
( 0.51 ng/µg total protein). In other mature (noncultured)
tissues, including heart and skeletal muscle, the protein is present only in
trace amounts and is closely correlated with the levels of the smooth muscle
marker -actin. In freshly isolated guinea pig bladder smooth muscle
cells, immunofluorescence images showed LPP as linear arrays of punctate,
longitudinally oriented staining superimposed with vinculin staining on the
plasma membrane surface. A corresponding pattern of periodic labeling at the
membrane in transverse sections of bladder smooth muscle suggested an
association of LPP with peripheral dense bodies. In cultured rat aortic smooth
muscle cells, LPP colocalized with vinculin at focal adhesions but not with
p120 catenin or -actinin. Overexpression of the protein increased
EGF-stimulated migration of vascular smooth muscle cells in Transwell assays,
suggesting the participation of LPP in cell motility. The Rho-kinase inhibitor
Y-27632 dissociated focal adhesions and LPP staining at the cell periphery and
enhanced the nuclear accumulation of LPP induced by leptomycin B, indicating
that LPP has a potential for relocating to the nucleus through a shuttling
mechanism that is sensitive to inhibition of Rho-kinase.
LIM protein; dense plaque; Rho-kinase; nuclear transport; cell migration
Address for reprint requests and other correspondence: A. P. Somlyo, PO Box
800736, Charlottesville, VA 22908 (E-mail:
aps2n{at}virginia.edu ).
Abstract
Background
Humoral response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurs within the first weeks after coronavirus disease 2019 (COVID-19). Those antibodies exert a ...neutralizing activity against SARS-CoV-2, whose evolution over time after COVID-19 as well as efficiency against novel variants are poorly characterized.
Methods
In this prospective study, sera of 107 patients hospitalized with COVID-19 were collected at 3 and 6 months postinfection. We performed quantitative neutralization experiments on top of high-throughput serological assays evaluating anti-spike (S) and anti-nucleocapsid (NP) immunoglobulin G (IgG).
Results
Levels of seroneutralization and IgG rates against the ancestral strain decreased significantly over time. After 6 months, 2.8% of the patients had a negative serological status for both anti-S and anti-NP IgG. However, all sera had a persistent and effective neutralizing effect against SARS-CoV-2. IgG levels correlated with seroneutralization, and this correlation was stronger for anti-S than for anti-NP antibodies. The level of seroneutralization quantified at 6 months correlated with markers of initial severity, notably admission to intensive care units and the need for mechanical invasive ventilation. In addition, sera collected at 6 months were tested against multiple SARS-CoV-2 variants and showed efficient neutralizing effects against the D614G, B.1.1.7, and P.1 variants but significantly weaker activity against the B.1.351 variant.
Conclusions
Decrease in IgG rates and serological assays becoming negative did not imply loss of neutralizing capacity. Our results indicate a sustained humoral response against the ancestral strain and the D614G, B.1.1.7, and P.1 variants for at least 6 months in patients previously hospitalized for COVID-19. A weaker protection was, however, observed for the B.1.351 variant.
Little is known on the association between clinical factors and coronavirus disease 2019 (COVID‐19) more than 15 days after diagnosis. We conducted a multicentric prospective cohort of COVID‐19 ...hospitalized patients to describe clinical, biological, and virological characteristics at hospital admission and over time, according to mortality up to Day 60 after admission. For the analysis of risk factors of survival, analyses assessing associations between mortality and demographic characteristics or comorbidities were performed using a Cox regression model. Between January 24 and March 15, 2020, 246 patients with reverse‐transcriptase polymerase chain reactions virologically confirmed COVID‐19 were enrolled. In multivariate analysis, mortality at Day 60 (n = 42 patients, 17.1% 95% confidence interval, 12.6–22.4) was associated with older age (adjusted hazard ratio aHR for age ≥ 65 years: 5.22 2.56–10.63, p < .001), gender (aHR for male: 2.97 1.47–5.99, p = .002), chronic pulmonary disease (aHR: 4.84 2.32–10.07, p < .001), obesity (aHR: 3.32 1.70–6.52, p < .001), and diabetes (aHR: 1.98 1.01–3.89, p = .048). The median nasopharyngeal viral load at admission was 6.4 log10 copies/ml and was associated with mortality regardless of clinical risk factors. Viral load decreased with time elapsed since symptoms onset. Our study confirmed that mortality was associated with clinical characteristics at admission. The viral load at admission was significantly lower in patients admitted late after the onset of symptoms in both dead and alive patients. Our results could improve earlier identification of patients with increased risk of mortality and adapted management.
Highlights
Older age, male gender, chronic pulmonary disease (not asthma), obesity, and diabetes were associated with mortality in COVID‐19 hospitalized patients.
Viral load at admission decreased with the time since symptom onset, with an association with mortality adjusted on clinical risk factors.
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