Assessment of Peripheral Blood Mononuclear Cells Senescence and Endothelial Dysfunction among Adults with High Cardiovascular Risk. / Avaliação da Senescência de Células Sanguíneas Mononucleares Periféricas e na Disfunção Endotelial entre Adultos com Alto Risco Cardiovascular.

BACKGROUND: Cardiovascular diseases (CVD) are one of the leading causes of mortality and morbidity worldwide. Biological aging has been associated with the occurrence of adverse cardiovascular outcomes; however, the underlying mechanism of this process remains unknown. OBJECTIVES: This study sought to evaluate if peripheral blood mononuclear cell (PBMC) senescence and endothelial biomarkers could influence cardiovascular (CV) risk and be suitable markers for the early detection of cardiovascular diseases in adults. METHODS: In this cross-sectional study patients free of CVD were classified as lower (n=32) and higher Interheart Risk (IHR) scores (n=28). PBMC senescence was assessed by estimating the telomerase activity (TA) and detecting the presence of senescent cells and endothelial dysfunction by estimating the concentration of nitrite and nitrate and of total antioxidant capacity (TAC). Statistical analysis was performed with SPSS version 16.0 (SPSS Inc., Chicago, IL). All p-values <0.05 were considered statistically significant. RESULTS: PBMC senescence 0.95 [p-value = 0.0001; 95% CI (0.874-1.026)] was a significant predictor of patients with higher IHR scores with a cut-off value of 21.65 with a sensitivity and specificity of 92% and 88% respectively. PBMC senescence, nitrite and nitrate and TA were found to be independently associated with high IHR scores. CONCLUSION: PBMC senescence, TA and nitrite, and nitrate status are suitable measures to predict high cardiovascular risk in adults with CV risk. Nevertheless, long-term follow-up studies are needed to confirm these findings. (Arq Bras Cardiol. 2021; 116(1):37-47).

FUNDAMENTO: Doenças cardiovasculares (DCV) são uma das principais causas de mortalidade e morbidade em todo o mundo. O envelhecimento biológico tem sido associado à ocorrência de resultados cardiovasculares. Entretanto, o mecanismo subjacente desse processo ainda é desconhecido. OBJETIVOS: Buscamos avaliar se a senescência das células sanguíneas mononucleares periféricas (CSMP) e biomarcadores endoteliais poderiam influenciar o risco cardiovascular (CV) e ser marcadores adequados para a detecção precoce de doenças cardiovasculares em adultos. MÉTODOS: Neste estudo transversal, pacientes livres de DCV foram classificados como baixo (n=32) e alto (n=28) escore de risco intracardaco (IHR) A senescência das CSMP foi avaliada estimando-se a atividade de telomerase (AT) e detectando-se a presença de células senescentes e disfunção endotelial, estimando-se a concentração de nitrito e nitrato e a capacidade antioxidante total (CAT). A análise estatística foi realizada com o software SPSS, versão 16.0 (SPSS Inc., Chicago, IL). Todos os p-valores <0,05 foram considerados estatisticamente significativos. RESULTADOS: A senescência de CSMP de 0,95 [p-valor = 0,0001; 95% IC (0,874-1,026)] foi um indicador significativo de pacientes com escore de IHR mais alto, com um valor de corte de 21,65, com sensibilidade e especificidade de 92% e 88% respectivamente. Identificou-se que a senescência de CSMP, nitrito e nitrato, e AT eram independentemente associadas a um escore de IHR alto. CONCLUSÃO: Os status de nitrito e nitrato e AT, e a senescência de CSMP são medidas adequadas para prever o alto risco cardiovascular em adultos com risco CV. Entretanto devem ser realizados estudos de acompanhamento de longo prazo para confirmar esses achados. (Arq Bras Cardiol. 2021; 116(1):37-47).

Avaliação da Senescência de Células Sanguíneas Mononucleares Periféricas e na Disfunção Endotelial entre Adultos com Alto Risco Cardiovascular / Assessment of Peripheral Blood Mononuclear Cells Senescence and Endothelial Dysfunction among Adults with High Cardiovascular Risk

Resumo Fundamento Doenças cardiovasculares (DCV) são uma das principais causas de mortalidade e morbidade em todo o mundo. O envelhecimento biológico tem sido associado à ocorrência de resultados cardiovasculares. Entretanto, o mecanismo subjacente desse processo ainda é desconhecido. Objetivos Buscamos avaliar se a senescência das células sanguíneas mononucleares periféricas (CSMP) e biomarcadores endoteliais poderiam influenciar o risco cardiovascular (CV) e ser marcadores adequados para a detecção precoce de doenças cardiovasculares em adultos. Métodos Neste estudo transversal, pacientes livres de DCV foram classificados como baixo (n=32) e alto (n=28) escore de risco intracardaco (IHR) A senescência das CSMP foi avaliada estimando-se a atividade de telomerase (AT) e detectando-se a presença de células senescentes e disfunção endotelial, estimando-se a concentração de nitrito e nitrato e a capacidade antioxidante total (CAT). A análise estatística foi realizada com o software SPSS, versão 16.0 (SPSS Inc., Chicago, IL). Todos os p-valores <0,05 foram considerados estatisticamente significativos. Resultados A senescência de CSMP de 0,95 [p-valor = 0,0001; 95% IC (0,874-1,026)] foi um indicador significativo de pacientes com escore de IHR mais alto, com um valor de corte de 21,65, com sensibilidade e especificidade de 92% e 88% respectivamente. Identificou-se que a senescência de CSMP, nitrito e nitrato, e AT eram independentemente associadas a um escore de IHR alto. Conclusão Os status de nitrito e nitrato e AT, e a senescência de CSMP são medidas adequadas para prever o alto risco cardiovascular em adultos com risco CV. Entretanto devem ser realizados estudos de acompanhamento de longo prazo para confirmar esses achados. (Arq Bras Cardiol. 2021; 116(1):37-47)

Abstract Background Cardiovascular diseases (CVD) are one of the leading causes of mortality and morbidity worldwide. Biological aging has been associated with the occurrence of adverse cardiovascular outcomes; however, the underlying mechanism of this process remains unknown. Objectives This study sought to evaluate if peripheral blood mononuclear cell (PBMC) senescence and endothelial biomarkers could influence cardiovascular (CV) risk and be suitable markers for the early detection of cardiovascular diseases in adults. Methods In this cross-sectional study patients free of CVD were classified as lower (n=32) and higher Interheart Risk (IHR) scores (n=28). PBMC senescence was assessed by estimating the telomerase activity (TA) and detecting the presence of senescent cells and endothelial dysfunction by estimating the concentration of nitrite and nitrate and of total antioxidant capacity (TAC). Statistical analysis was performed with SPSS version 16.0 (SPSS Inc., Chicago, IL). All p-values <0.05 were considered statistically significant. Results PBMC senescence 0.95 [p-value = 0.0001; 95% CI (0.874-1.026)] was a significant predictor of patients with higher IHR scores with a cut-off value of 21.65 with a sensitivity and specificity of 92% and 88% respectively. PBMC senescence, nitrite and nitrate and TA were found to be independently associated with high IHR scores. Conclusion PBMC senescence, TA and nitrite, and nitrate status are suitable measures to predict high cardiovascular risk in adults with CV risk. Nevertheless, long-term follow-up studies are needed to confirm these findings. (Arq Bras Cardiol. 2021; 116(1):37-47)

Pharmacologic downregulation of protein arginine methyltransferase1 expression by adenosine dialdehyde increases cell senescence in breast cancer.

We investigated the role of protein arginine methylation (PAM) in estrogen receptor (ER)-positive breast cancer cells through pharmacological intervention. Tamoxifen (TAM) or adenosine dialdehyde (ADOX), independently, triggered cell cycle arrest and down-regulated PAM, as reduced protein arginine methyltransferase1 (PRMT1) mRNA and asymmetric dimethylarginine (ADMA) levels. Synergistic effect of these compounds elicited potent anti-cancer effect. However, reduction in ADMA was not proportionate with the compound-induced down-regulation of PRMT1 mRNA. We hypothesized that the disproportionate effect is due to the influence of the compounds on other methyltransferases, which catalyze the arginine dimethylation reaction and the diversity in the degree of drug-protein interaction among these methyltransferases. In silico analyses revealed that independently, ADOX or TAM, binds with phosphatidylethanolamine-methyltransferase (PEMT) or betaine homocysteine-methyl transferase (BHMT); and that the binding affinity of ADOX with PEMT or BHMT is prominent than TAM. These observations suggest that in breast cancer, synergistic effect of ADOX + TAM elicits impressive protective function by regulating PAM; and plausibly, restoration of normal enzyme activities of methyltransferases catalyzing arginine dimethylation could have clinical benefits.

Pharmacological inhibition of guanosine triphosphate cyclohydrolase1 elevates tyrosine phosphorylation of caveolin1 and cellular senescence.

The role of 2,4-diamino-6-hydroxypyrimidine (DAHP), on cellular-senescence remains unclear as differential effects of DAHP have been reported in cardiovascular and cerebrovascular systems. We investigated the effect of pharmacologically-induced guanosine-triphosphate-cyclohydrolase1 (GTPCH1)-inhibition, through DAHP, on cellular-senescence in experimentally-induced diabetic and non-diabetic Wistar rats. Cellular-senescence was evaluated through senescence-associated events, namely, cell-cycle-arrest of peripheral blood mononuclear cells (PBMNCs); myocardial DNA fragmentation, total antioxidant capacity (TAC), telomerase-activity, nicotinamide adenine dinucleotide (NAD+)-content and tyrosine14-phosphorylation of caveolin1 (pY14) in similarly-aged, pubertal Wistar rats with streptozotocin (STZ) and/or DAHP. Oxidative stress (OS) indices such as myocardial biopterin concentrations (tetrahydrobiopterin-BH4 and dihydrobiopterin-BH2) and plasma total nitrite and nitrate (NOx) were determined. DAHP, per se, exhibited distinct senescence; in addition, in STZ+DAHP (the cardiomyopathy model), there was a marked accumulation of cells in G0G1 phase, as evidenced through flow-cytometry analysis, as-well-as fragmented DNA, than the respective controls suggesting the DAHP-mediated onset of senescence in circulating cells and the myocardium, with or without STZ. Concentrations of BH4 and BH2, and NOx were impaired in STZ and/or DAHP, indicating elevated OS in the treatment groups. In the independent treatment groups or the combination treatment, typical senescence indicators including myocardial telomerase-activity, NAD+-content and TAC were significantly reduced, while there was a marked elevation in the concentrations of pY14 as compared to the respective controls, reinforcing the occurrence of senescence in PBMNCs and the myocardium. We postulate that DAHP promotes early onset of cellular-senescence, potentially through OS-mediated cellular events in diabetic or non-diabetic models.

Forskolin attenuates doxorubicin-induced accumulation of asymmetric dimethylarginine and s-adenosylhomocysteine via methyltransferase activity in leukemic monocytes.

Doxorubicin (DOX) is an antitumor drug, associated with cardiomyopathy. Strategies to address DOX-cardiomyopathy are scarce. Here, we identify the effect of forskolin (FSK) on DOX-induced-asymmetric-dimethylarginine (ADMA) accumulation in monocytoid cells. DOX-challenge led to i) augmented cytotoxicity, reactive-oxygen-species (ROS) production and methyltransferase-enzyme-activity identified as ADMA and s-adenosylhomocysteine (SAH) accumulation (SAH-A). However, except cytotoxicity, other DOX effects were decreased by metformin and FSK. FSK, did not alter the DOX-induced cytotoxic effect, but, decreased SAH-A by >50% and a combination of three drugs restored physiological methyltransferase-enzyme-activity. Together, protective effect of FSK against DOX-induced SAH-A is associated with mitigated methyltransferase-activity, a one-of-a-kind report.

Caveolin1/protein arginine methyltransferase1/sirtuin1 axis as a potential target against endothelial dysfunction.

Endothelial dysfunction (ED), an established response to cardiovascular risk factors, is characterized by increased levels of soluble molecules secreted by endothelial cells (EC). Evidence suggest that ED is an independent predictor of cardiac events and that it is associated with a deficiency in production or bioavailability of nitric oxide (NO) and/or an imbalance in the relative contribution of endothelium-derived relaxing and contracting factors. ED can be reversed by treating cardiovascular risk factors, hence, beyond ambiguity, ED contributes to initiation and progression of atherosclerotic disease. Majority of cardiovascular risk factors act by a common pathway, oxidative stress (OS), characterized by an imbalance in bioavailability of NO and reactive oxygen species (ROS). Enhanced ROS, through several mechanisms, alters competence of EC that leads to ED, reducing its potential to maintain homeostasis and resulting in development of cardiovascular disease (CVD). Influential mechanisms that have been implicated in the development of ED include (i) presence of elevated levels of NOS inhibitor, asymmetric dimethylarginine (ADMA) due to augmented enzyme activity of protein arginine methyl transferase-1 (PRMT1); (ii) decrease in NO generation by endothelial nitric oxide synthase (eNOS) uncoupling, or by reaction of NO with free radicals and (iii) impaired post translational modification of protein (PTM) such as eNOS, caveolin-1 (cav1) and sirtuin-1 (SIRT1). However, the inter-related mechanisms that concur to developing ED is yet to be understood. The events that possibly overlay include OS-induced sequestration of SIRT1 to caveolae facilitating cav1-SIRT1 association; potential increase in lysine acetylation of enzymes such as eNOS and PRMT1 leading to enhanced ADMA formation; imbalance in acetylation-methylation ratio (AMR); diminished NO generation and ED. Here we review current literature from research showing interdependent association between cav1-PRMT1-SIRT1 to the outcomes of experimental and clinical research aiming to preserve endothelial function with gene- or pharmaco-therapy.