Cigarette smoke exposure impairs lipid metabolism by decreasing low-density lipoprotein receptor expression in hepatocytes

Association between lipid profiles and cigarette smoke among adults in the Persian cohort (Shahedieh) study

OBJECTIVES

Exposure to cigarette smoke introduces a large amount of nicotine into the bloodstream through the lungs. So, smoking can be a risk factor for many diseases. The present study was conducted to investigate the effect of active and passive cigarette smoke on the blood lipid profile and dyslipidemia.

METHODS

This cross-sectional study was performed on 5052 individuals who participated in the recruitment phase of the Shahedieh cohort study. A logistic regression model was used to investigate the relationship between smoking exposure status and lipid profiles.

RESULTS

The prevalence of abnormal low-density lipoprotein-cholesterol (LDL-C), abnormal HDL-C, abnormal total cholesterol (TC), abnormal triglyceride (TG), and dyslipidemia were 254 (5.00%), 562 (11.10%), 470 (9.30%), 1008 (20.00%), and 1527 (30.20%), respectively. Adjusting for confounders, it was observed that current smokers had higher odds of having abnormal HDL-C [OR (95% CI), 2.90 (2.28-3.69)], abnormal TG [OR (95% CI), 1.71 (1.38-2.13)] and dyslipidemia [OR (95% CI), 1.86 (1.53-2.25)]. Ex-smokers also had greater odds of abnormal HDL-C [OR (95% CI), 1.51 (1.06-2.16)] compared to non-smokers who were not exposed to cigarette smoke.

CONCLUSIONS

The findings indicated that current smokers had higher TG and lower HDL. So, necessary measures should be taken to reduce smoking. The findings also showed that the prevalence of abnormal TG and HDL in ex-smokers was lower than in current smokers. Therefore, the existence of incentive policies to quit smoking seems necessary.

In Association with Other Risk Factors, Smoking Is the Main Predictor for Lower Transcutaneous Oxygen Pressure in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) significantly increases the risk of peripheral artery disease (PAD), and diabetes is the leading cause of nontraumatic amputations. This study investigated the risk factors for transcutaneous oxygen pressure (TcPO2) in T2DM, a noninvasive method to quantify skin oxygenation and the underlying microvascular circulation. The study included 119 T2DM patients (91 male/28 female). TcPO2 measurements were conducted with the Tina TCM4 Series transcutaneous monitor (Radiometer, Copenhagen, Sweden) and skin electrodes. Patients with TcPO2 < 40 mmHg were younger (p = 0.001), had significantly higher systolic blood pressure (SBP) (p = 0.023), glycated hemoglobin (HbA1c) (p = 0.013), fasting plasma glucose (fPG) (p = 0.038), total cholesterol (p = 0.006), LDL cholesterol (p = 0.004), and had more frequent smoking habits (p = 0.001) than those with TcPO2 ≥ 40 mmHg. The main predictors for the TcPO2 value (R2 = 0.211) obtained via stepwise regression analysis were age, smoking, SBP, HbA1c, fPG, and total and LDL cholesterol. Among all the listed predictors, smoking, HbA1c, and LDL cholesterol were found to be the most significant, with negative parameter estimates of -3.051310 (p = 0.0007), -2.032018 (p = 0.0003), and -2.560353 (p = 0.0046). The results of our study suggest that in association with other risk factors, smoking is the main predictor for lower TcPO2 in T2DM.

Improving Genetic Association Studies with a Novel Methodology that Unveils the Hidden Complexity of All-Cause Heart Failure

Motivation

Genome-Wide Association Studies (GWAS) commonly assume phenotypic and genetic homogeneity that is not present in complex conditions. We designed Transformative Regression Analysis of Combined Effects (TRACE), a GWAS methodology that better accounts for clinical phenotype heterogeneity and identifies gene-by-environment (GxE) interactions. We demonstrated with UK Biobank (UKB) data that TRACE increased the variance explained in All-Cause Heart Failure (AHF) via the discovery of novel single nucleotide polymorphism (SNP) and SNP-by-environment (i.e. GxE) interaction associations. First, we transformed 312 AHF-related ICD10 codes (including AHF) into continuous low-dimensional features (i.e., latent phenotypes) for a more nuanced disease representation. Then, we ran a standard GWAS on our latent phenotypes to discover main effects and identified GxE interactions with target encoding. Genes near associated SNPs subsequently underwent enrichment analysis to explore potential functional mechanisms underlying associations. Latent phenotypes were regressed against their SNP hits and the estimated latent phenotype values were used to measure the amount of AHF variance explained.

Results

Our method identified over 100 main GWAS effects that were consistent with prior studies and hundreds of novel gene-by-smoking interactions, which collectively accounted for approximately 10% of AHF variance. This represents an improvement over traditional GWAS whose results account for a negligible proportion of AHF variance. Enrichment analyses suggested that hundreds of miRNAs mediated the SNP effect on various AHF-related biological pathways. The TRACE framework can be applied to decode the genetics of other complex diseases.

Availability

All code is available at https://github.com/EpistasisLab/latent_phenotype_project.

Meta-analysis of the effects of smoking and smoking cessation on triglyceride levels

Smoking increases lipid levels, including triglycerides, leading to increased cardiovascular disease risk. We performed a meta-analysis to quantify the effects of smoking and smoking cessation on triglyceride levels. The PubMed and Scopus databases were searched to identify studies reporting either triglyceride levels in smokers and non-smokers or the effects of smoking cessation on triglyceride levels. Fixed- and random-effects models were used to perform the analyses when three or more studies/comparisons were available. We identified 169 and 21 studies evaluating the effects of smoking and smoking cessation, respectively, on triglyceride levels. Triglyceride levels were 0.50 mmol/L (95% confidence interval: 0.49-0.50 mmol/L) higher in smokers than non-smokers, but the effect differed widely across studies. No statistically significant effect was observed on triglyceride levels between baseline and 6 weeks (mean difference [MD] = 0.02 [-0.09, 0.12] mmol/L), 2 months (MD = 0.03 [-0.21, 0.27] mmol/L), 3 months (MD = 0.08 [-0.03, 0.21] mmol/L), or 1 year (MD = 0.04 [-0.06, 0.14] mmol/L) after quitting. However, a slightly significant decrease in triglyceride levels was observed at 1 month after cessation (MD = -0.15 [-0.15, -0.01] mmol/L). The results of this meta-analysis provide a basis for understanding the effects of smoking and smoking cessation on triglyceride levels, which could have important implications for public health.

Metabolomics-based safety evaluation of acute exposure to electronic cigarettes in mice

INTRODUCTION

A growing number of epidemiological evidence reveals that electronic cigarettes (E-cigs) were associated with pneumonia, hypertension and atherosclerosis, but the toxicological evaluation and mechanism of E-cigs were largely unknown.

OBJECTIVE

Our study was aimed to explore the adverse effects on organs and metabolomics changes in C57BL/6J mice after acute exposure to E-cigs.

METHODS AND RESULTS

Hematoxylin and eosin (H&E) staining found pathological changes in tissues after acute exposure to E-cigs, such as inflammatory cell infiltration, nuclear pyknosis, and intercellular interstitial enlargement. E-cigs could increase apoptosis-positive cells in a time-dependent way using Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. Oxidative damage indicators of reactive oxygen species (ROS), malondialdehyde (MDA) and 4-hydroxynonena (4-HNE) were also elevated after E-cigs exposure. There was an increasing trend of total glycerol and cholesterol in serum, while the glucose and liver enzymes including alanine aminotransferase (ALT), aspartate transaminase (AST), gamma-glutamyltranspeptidase (γ-GT) had no significant change compared to that of control. Further, Q Exactive high field (HF) mass spectrometer was used to conduct metabolomics, which revealed that differential metabolites including l-carnitine, Capryloyl glycine, etc. Trend analysis showed the type of compounds that change over time. Pathway enrichment analysis indicated that E-cigs affected 24 metabolic pathways, which were mainly regulated amino acid metabolism, further affected the tricarboxylic acid (TCA) cycle. Additionally, metabolites-diseases network analysis found that the type 2 diabetes mellitus, propionic acidemia, defect in long-chain fatty acids transport and lung cancer may be related to E-cigs exposure.

CONCLUSIONS

Our findings provided important clues for metabolites biomarkers of E-cigs acute exposure and are beneficial for disease prevention.

Long-term PM0.1 exposure and human blood lipid metabolism: New insight from the 33-community study in China

Ambient particles with aerodynamic diameter <0.1 μm (PM_0.1) have been suggested to have significant health impact. However, studies on the association between long-term PM_0.1 exposure and human blood lipid metabolism are still limited. This study was aimed to evaluate such association based on multiple lipid biomarkers and dyslipidemia indicators. We matched the 2006-2009 average PM_0.1 concentration simulated using the neural-network model following the WRF-Chem model with the clinical and questionnaire data of 15,477 adults randomly recruited from 33 communities in Northeast China in 2009. After controlling for social demographic and behavior confounders, we assessed the association of PM_0.1 concentration with multiple lipid biomarkers and dyslipidemia indicators using generalized linear mixed-effect models. Effect modification by various social demographic and behavior factors was examined. We found that each interquartile range increase in PM_0.1 concentration was associated with a 5.75 (95% Confidence interval, 3.24-8.25) mg/dl and a 6.05 (2.85-9.25) mg/dl increase in the serum level of total cholesterol and LDL-C, respectively. This increment was also associated with an odds ratio of 1.25 (1.10-1.42) for overall dyslipidemias, 1.41 (1.16, 1.73) for hypercholesterolemia, and 1.90 (1.39, 2.61) for hyperbetalipoproteinemia. Additionally, we found generally greater effect estimates among the younger participants and those with lower income or with certain behaviors such as high-fat diet. The deleterious effect of long-term PM_0.1 exposure on lipid metabolism may make it an important toxic chemical to be targeted by future preventive strategies.

Electronic and Conventional Cigarette Exposure Aggravate Metabolic Parameters in High-Fat Diet-Induced Rats

BACKGROUND: The health implications of the perceived use of electronic cigarettes (e-cigarettes) are safer than conventional cigarettes on metabolic parameters are not clearly understood. The current study evaluates the metabolic parameters as the impact of cigarette and e-cigarette exposure in high-fat-diet (HFD)-induced rats. METHODS: Twenty-four male Wistar rats were divided into four groups: i) NC: normal control group; ii) HFD Alone; iii) HFD + Cig and iv) HFD + E-Cig, administered HFD followed by cigarette or e-cigarette exposure, respectively. Six cigarettes stick with nicotine 2 mg/stick and 2 ml of e-cigarette liquid with nicotine 6 mg/ml were used for 25 cycles of exposure. In the end, the rats were sacrificed and obtained blood for metabolic parameter analysis, consisting of lipid profile, glucose, uric acid, urea, creatinine, aspartate transaminase (AST), and alanine transaminase (ALT). Statistical analysis with One-Way ANOVA with post hoc was used for high-density lipoprotein (HDL), triglyceride, total cholesterol, glucose, uric acid, urea, and creatinine. Furthermore, Kruskal-Wallis with Mann-Whitney U was used for nonparametric data such as low-density lipoprotein (LDL), AST, and ALT. RESULTS: Data of all metabolic parameters were shown a significant increase in the group of HFD Alone, HFD + Cig, and HFD + E-Cig, otherwise HDL levels. Furthermore, HFD + Cig followed by HFD + E-Cig groups were significantly higher compared to HFD Alone group. CONCLUSION: E-cigarettes were shown to be less harmful than conventional cigarettes but did not guarantee it was safe. Both cigarettes and e-cigarettes aggravated metabolic parameters in HFD-induced rats.

The Risk Factors for Progression to Chronic Pancreatitis in Patients with Past-History of Acute Pancreatitis: A Retrospective Analysis Based on Mechanistic Definition

Background: According to the mechanistic definition, the history of acute pancreatitis (AP) is a risk factor for chronic pancreatitis (CP). However, the etiology and severity of previous AP involved in the progression to CP have not been clarified. Here, we investigated risk factors for the progression to CP in patients with past-history of AP. Methods: Sixty-four patients with AP who were followed-up for at least two years at our institution between April 2009 and March 2017 were enrolled. The multivariate analysis was performed based on the risk factors extracted by univariate analysis. Results: Among the 64 patients, 13 patients (20.3%) progressed to CP (PCP group), while 48 did not (non-PCP group). Regarding the etiology of AP, rate of alcohol AP was significantly higher in the PCP group (76.9% vs. 33.3%, p = 0.003). In univariate analysis, smoking, number of previous AP, and alcohol consumption and drinking habits (Alcohol Use Disorders Identification Test-Concise; AUDIT-C) were identified as factors associated with progression to CP. Furthermore, multivariate analysis showed that AUDIT-C ≥ 6 points (male) and 4 points (female) after AP was a significant risk factor for CP (p = 0.003). Conclusions: Our results indicated that AUDIT-C ≥ 6 points (male) and 4 points (female) after AP was a risk factor in the process of progression to CP in patients with past-history of AP.

Risk Factors for Recurrent Pancreatitis After First Episode of Acute Pancreatitis

Background

Methods

Results

Conclusion

Cigarette smoke extract stimulates PCSK9 production in HepG2 cells via ROS/NF‑κB signaling

Cigarette smoke (CS) exposure is a risk factor for dyslipidemia and atherosclerosis. Reduced expression of low-density lipoprotein receptor (LDLR) in hepatocytes may be one of the underlying mechanisms for these disorders. The aim of the present study was to investigate the molecular mechanism underlying the regulatory effect of CS extract (CSE) on proprotein convertase subtilisin/kexin type 9 (PCSK9) and low LDLR expression in HepG2 cells. PCSK9 and LDLR mRNA and protein expression levels in HepG2 cells were evaluated after CSE treatment via reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. In addition, total intracellular reactive oxygen species (ROS) production was determined via 2,7-dichlorofluorescein diacetate fluorescence. CSE significantly increased PCSK9 expression and inhibited LDLR expression in a time- and concentration-dependent manner. Furthermore, CSE significantly induced ROS production and nuclear factor κB (NF-κB) activation. However, pretreatment with a ROS scavenger or an NF-κB inhibitor significantly attenuated the CSE-induced changes in PCSK9 and LDLR expression. In addition, pretreatment with melatonin markedly reduced ROS production, NF-κB activation and PCSK9 expression, and increased LDLR expression in the CSE-treated cells. These data suggest that melatonin inhibits CSE-regulated PCSK9 and LDLR production in HepG2 cells via ROS/NF-κB signaling.

Potential Role of Melatonin as an Adjuvant for Atherosclerotic Carotid Arterial Stenosis

Carotid artery stenosis (CAS) is an atherosclerotic disease characterized by a narrowing of the artery lumen and a high risk of ischemic stroke. Risk factors of atherosclerosis, including smoking, hypertension, hyperglycemia, hyperlipidemia, aging, and disrupted circadian rhythm, may potentiate atherosclerosis in the carotid artery and further reduce the arterial lumen. Ischemic stroke due to severe CAS and cerebral ischemic/reperfusion (I/R) injury after the revascularization of CAS also adversely affect clinical outcomes. Melatonin is a pluripotent agent with potent anti-inflammatory, anti-oxidative, and neuroprotective properties. Although there is a shortage of direct clinical evidence demonstrating the benefits of melatonin in CAS patients, previous studies have shown that melatonin may be beneficial for patients with CAS in terms of reducing endothelial damage, stabilizing arterial plaque, mitigating the harm from CAS-related ischemic stroke and cerebral I/R injury, and alleviating the adverse effects of the related risk factors. Additional pre-clinical and clinical are required to confirm this speculation.