Protective effects of valsartan against cigarette smoke-induced left ventricular systolic dysfunction in rats

Influence of cigarette smoking on biventricular systolic function independent of respiratory function: a cross-sectional study

Background

Cigarette smoking harms nearly every organ, including the heart and lungs. A comprehensive assessment of both cardiac and respiratory function is necessary for evaluating the direct effects of tobacco on the heart. However, few previous studies examining the effects of cigarette smoking on cardiac function included an assessment of lung function. This cross-sectional study investigated the influence of cigarette smoking on cardiac function, independent of respiratory function.

Methods

We retrospectively reviewed the medical records of 184 consecutive cases that underwent both spirometry and transthoracic echocardiography around the same time (within 1 month) in one hospital from April 2019 to March 2020. Participants were classified into three groups based on lifetime smoking exposure (pack-years): non-smoker (n = 49), low exposure (1–20 pack-years, n = 40), and high exposure (≥ 20 pack years, n = 95). Multiple linear regression analysis was used to assess the relationship among cigarette smoking, and cardiac and respiratory functions. The relationship between selected dependent variables and lifetime pack-years was assessed in two models with multiple linear regression analysis. Model 1 was adjusted for age and male sex; and Model 2 was adjusted for Model 1 plus forced expiratory volume percentage in 1 s and forced vital capacity percentage.

Results

Compared with the non-smokers, the participants with high smoking exposure had lower left ventricular (LV) systolic function and larger LV size. Multiple linear regression analysis revealed a negative association of cumulative lifetime pack-years with LV and right ventricular (RV) systolic functions, even after adjustment for age, sex, and spirometric parameters (forced expiratory volume percentage in 1 s and forced vital capacity percentage). Meanwhile, there was no significant association of smoking exposure with LV diastolic function (E/e′ and E/A) and RV diastolic function (e′t and e′t/a′t).

Conclusions

Cumulative smoking exposure was associated with a negative effect on biventricular systolic function in patients with relatively preserved cardiac function, independent of respiratory function.

Hydrogen Sulfide Regulating Myocardial Structure and Function by Targeting Cardiomyocyte Autophagy

Objective:

Hydrogen sulfide (H₂S), a gaseous signal molecule, plays a crucial role in many pathophysiologic processes in the cardiovascular system. Autophagy has been shown to participate in the occurrence of many cardiac diseases. Increasing evidences indicated that H₂S regulates myocardial structure and function in association with the altered autophagy and plays a “switcher” role in the autophagy of myocardial diseases. The aim of this review was to summarize these insights and provide the experimental evidence that H₂S targets cardiomyocyte autophagy to regulate cardiovascular function.

Data Sources:

This review was based on data in articles published in the PubMed databases up to October 30, 2017, with the following keywords: “hydrogen sulfide,” “autophagy,” and “cardiovascular diseases.”

Study Selection:

Original articles and critical reviews on H₂S and autophagy were selected for this review.

Results:

When autophagy plays an adaptive role in the pathogenesis of diseases, H₂S restores autophagy; otherwise, when autophagy plays a detrimental role, H₂S downregulates autophagy to exert a cardioprotective function. For example, H₂S has beneficial effects by regulating autophagy in myocardial ischemia/reperfusion and plays a protective role by inhibiting autophagy during the operation of cardioplegia and cardiopulmonary bypass. H₂S postpones cardiac aging associated with the upregulation of autophagy but improves the left ventricular function of smoking rats by lowering autophagy.

Conclusions:

H₂S exerts cardiovascular protection by regulating autophagy. Cardiovascular autophagy would likely become a potential target of H₂S therapy for cardiovascular diseases.

Immune-regulating effects of exercise on cigarette smoke-induced inflammation

Long-term cigarette smoking (LTCS) represents an important risk factor for cardiac infarction and stroke and the central risk factor for the development of a bronchial carcinoma, smoking-associated interstitial lung fibrosis, and chronic obstructive pulmonary disease. The pathophysiologic development of these diseases is suggested to be promoted by chronic and progressive inflammation. Cigarette smoking induces repetitive inflammatory insults followed by a chronic and progressive activation of the immune system. In the pulmonary system of cigarette smokers, oxidative stress, cellular damage, and a chronic activation of pattern recognition receptors are described which are followed by the translocation of the NF-kB, the release of pro-inflammatory cytokines, chemokines, matrix metalloproteases, and damage-associated molecular patterns. In parallel, smoke pollutants cross directly through the alveolus-capillary interface and spread through the systemic bloodstream targeting different organs. Consequently, LTCS induces a systemic low-grade inflammation and increased oxidative stress in the vascular system. In blood, these processes promote an increased coagulation and endothelial dysfunction. In muscle tissue, inflammatory processes activate catabolic signaling pathways followed by muscle wasting and sarcopenia. In brain, several characteristics of neuroinflammation were described. Regular exercise training has been shown to be an effective nonpharmacological treatment strategy in smoke-induced pulmonary diseases. It is well established that exercise training exerts immune-regulating effects by activating anti-inflammatory signaling pathways. In this regard, the release of myokines from contracting skeletal muscle, the elevations of cortisol and adrenalin, the reduced expression of Toll-like receptors, and the increased mobilization of immune-regulating leukocyte subtypes might be of vital importance. Exercise training also increases the local and systemic antioxidative capacity and several compensatory mechanisms in tissues such as an increased anabolic signaling in muscle or an increased compliance of the vascular system. Accordingly, regular exercise training seems to protect long-term smokers against some important negative local and systemic consequences of smoking. Data suggest that it seems to be important to start exercise training as early as possible.

Functional, Cellular, and Molecular Remodeling of the Heart under Influence of Oxidative Cigarette Tobacco Smoke

Passive and active chronic cigarette smoking (CS) remains an international epidemic and a key risk factor for cardiovascular disease (CVD) development. CS-induced cardiac damage is divided into two major and interchangeable mechanisms: (1) direct adverse effects on the myocardium causing smoking cardiomyopathy and (2) indirect effects on the myocardium by fueling comorbidities such as atherosclerotic syndromes and hypertension that eventually damage and remodel the heart. To date, our understanding of cardiac remodeling following acute and chronic smoking exposure is not well elucidated. This manuscript presents for the first time the RIMD (oxidative stress (R), inflammation (I), metabolic impairment (M), and cell death (D)) detrimental cycle concept as a major player in CS-induced CVD risks and direct cardiac injury. Breakthroughs and latest findings in the field with respect to structural, functional, cellular, and molecular cardiac remodeling following chronic smoking exposure are summarized. This review also touches the genetics/epigenetics of smoking as well as the smoker's paradox and highlights the most currently prominent pharmacological venues to mitigate CS-induced adverse cardiac remodeling.

Antioxidant effects of hydrogen sulfide on left ventricular remodeling in smoking rats are mediated via PI3K/Akt-dependent activation of Nrf2

There is growing evidence that oxidative stress plays critical roles in the pathogenesis of cardiac remodeling. In the present study, we established a rat model of passive smoking and investigated the antioxidant effects of hydrogen sulfide (H2S) on smoking-induced left ventricular remodeling. Cardiac structure and function were evaluated using 2-dimensional echocardiography. Myocardial fibrosis was detected by Masson's trichrome staining and immunohistochemistry. Oxidative stress was assessed by measuring malondialdehyde levels, superoxide dismutase and glutathione peroxidase activities, and reactive oxygen species generation in the myocardium. Neonatal rat cardiomyocytes transfected with specific siRNA and exposed to cigarette smoke condensate and H2S donor sodium hydrosulfide were used to confirm the involvement of Nrf2 and PI3K/Akt signaling in the antioxidant effects of H2S. Our results indicated that H2S could protect against left ventricular remodeling in smoking rats via attenuation of oxidative stress. Moreover, H2S was also found to increase the phosphorylation of Akt and GSK3β and decrease the nuclear expression of Fyn, which consequently leads to nuclear translocation of Nrf2 and elevated expression of HO-1 and NQO1. In conclusion, H2S may exert antioxidant effects on left ventricular remodeling in smoking rats via PI3K/Akt-dependent activation of Nrf2 signaling.

Hydrogen sulfide improves left ventricular function in smoking rats via regulation of apoptosis and autophagy

The present study was designed to investigate the protective effects of hydrogen sulfide (H2S) against cigarette smoking-induced left ventricular dysfunction in rats. Left ventricular structure and function were assessed using two-dimensional echocardiography. Cardiomyocyte apoptosis was determined by Annexin V/PI and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. Cardiac autophagy was evaluated by detection of autophagy-related protein expression and observation of autophagosomes. Our results indicated that administration of NaHS (a donor of H2S) could protect against smoking-induced left ventricular systolic dysfunction. H2S was found to exert anti-apoptotic effects in the myocardium of smoking rats by inhibiting JNK and P38 mitogen-activated protein kinases pathways and activating PI3K/Akt signaling. Moreover, H2S could also reduce smoking-induced autophagic cell death via regulation of AMPK/mTOR signaling pathway. In conclusion, our study demonstrates that H2S can improve left ventricular systolic function in smoking rats via regulation of apoptosis and autophagy.

Prevalence and clinical correlation of left ventricular systolic dysfunction in african americans with ischemic stroke

BACKGROUND

The goal of the present study was to determine the prevalence of left ventricular systolic dysfunction (LVSD) and associated clinical correlates in African Americans (AA) diagnosed with ischemic stroke (IS).

METHODS

Retrospective chart analysis was done on all diagnosed AA IS patients between January 2010 and March 2012. Patients with atrial fibrillation were excluded. A total of 147 patients were included in the study. Transthoracic 2-dimensional echocardiography was used to assess left ventricular systolic function, and study groups were categorized as normal, mild, moderate, and severely abnormal, based on the ejection fraction (EF). Available imaging studies were analyzed for data collection. Logistic regression and Pearson chi-square tests were performed.

RESULTS

Normal EF was present in 114 of 147 patients (78%). Mild abnormality was present in 9 of 147 (6%), moderate in 8 of 147 (5%), and severe in 16 of 147 (11%) patients. In patients with mildly reduced EF, smoking was the most common (RF). In patients with moderately and severely reduced EFs, hypertension was the most common RF. History of smoking was commonly found in systolic dysfunction group compared with normal group (P = .001). Logistic regression analysis revealed that smoking and advanced age were the significant predictors for LVSD. Large-vessel IS were more common in systolic dysfunction group than normal EF group (P = .017).

CONCLUSIONS

Prevalence of LVSD in AA with IS was 22% in our study. Smoking was a significant modifiable RF associated with systolic dysfunction. A history of smoking and higher age could predict the occurrence of LVSD. There were more large-vessel IS in patients with LVSD.

Inhibitory effects of hydrogen sulphide on pulmonary fibrosis in smoking rats via attenuation of oxidative stress and inflammation

Accumulating evidence has demonstrated that hydrogen sulphide (H2 S) is involved in the pathogenesis of various respiratory diseases. In the present study, we established a rat model of passive smoking and investigated whether or not H2 S has protective effects against pulmonary fibrosis induced by chronic cigarette smoke exposure. Rat lung tissues were stained with haematoxylin-eosin and Masson's trichrome. The expression of type I collagen was detected by immunohistochemistry. Oxidative stress was evaluated by detecting serum levels of malondialdehyde, superoxide dismutase and glutathione peroxidase and measuring reactive oxygen species generation in lung tissue. Inflammation was assessed by measuring serum levels of inflammatory cytokines, including high-sensitivity C-reactive protein, tumour necrosis factor-α, interleukin (IL)-1β and IL-6. The protein expression of Nrf2, NF-κB and phosphorylated mitogen-activated protein kinases (MAPKs) in the pulmonary tissue was determined by Western blotting. Our findings indicated that administration of NaHS (a donor of H2 S) could protect against pulmonary fibrosis in the smoking rats. H2 S was found to induce the nuclear accumulation of Nrf2 in lung tissue and consequently up-regulate the expression of antioxidant genes HO-1 and Trx-1 in the smoking rats. Moreover, H2 S could also reduce cigarette smoking-induced inflammation by inhibiting the phosphorylation of ERK 1/2, JNK and p38 MAPKs and negatively regulating NF-κB activation. In conclusion, our study suggests that H2 S has protective effects against pulmonary fibrosis in the smoking rats by attenuating oxidative stress and inflammation.

Cardiovascular effects of nose-only water-pipe smoking exposure in mice

Water-pipe smoking (WPS) is a major type of smoking in Middle Eastern countries and is increasing in popularity in Western countries and is perceived as relatively safe. However, data on the adverse cardiovascular effects of WPS are scarce. Here, we assessed the cardiovascular effects of nose-only exposure to mainstream WPS generated by commercially available honey-flavored "moasel" tobacco in BALB/c mice. The duration of the session was 30 min/day for 1 mo. Control mice were exposed to air. WPS caused a significant increase of systolic blood pressure (SBP) in vivo (+13 mmHg) and plasma concentrations of IL-6 (+30%) but not that of TNF-α. Heart concentrations of IL-6 (+184%) and TNF-α (+54%) were significantly increased by WPS. Concentrations of ROS (+95%) and lipid peroxidation (+27%) were significantly increased, whereas those of GSH were decreased (-21%). WPS significantly shortened the thrombotic occlusion time in pial arterioles (-46%) and venules (40%). Plasma von Willebrand factor concentrations were significantly increased (+14%) by WPS. Erythrocyte numbers (+15%) and hematocrit (+17%) were significantly increased. Blood samples taken from mice exposed to WPS and exposed to ADP showed significant platelet aggregation compared with air-exposed mice. WPS caused a significant shortening of activated partial thromboplastin time (-45%) and prothrombin time (-13%). We conclude that 1-mo nose-only exposure to WPS increased SBP and caused cardiac inflammation, oxidative stress, and prothrombotic events. Our findings provide plausible elucidation that WPS is injurious to the cardiovascular system.