Cigarette tar accelerates atherosclerosis progression via RIPK3-dependent necroptosis mediated by endoplasmic reticulum stress in vascular smooth muscle cells.

BACKGROUND: Tar is the main toxic of cigarettes, and its effect on atherosclerosis progression and the underlying mechanisms remain largely unknown. Vascular smooth muscle cells (VSMCs) play a key role in atherogenesis and plaque vulnerability. The present study sought to investigate the mechanism of atherosclerosis progression through tar-induced VSMC necroptosis, a recently described form of necrosis. METHODS: The effect of tar on atherosclerosis progression and VSMC necroptosis was examined in ApoE-/- mice and cultured VSMCs. The role of necroptosis in tar-induced plaque development was evaluated in RIPK3-deletion mice (ApoE-/-RIPK3-/-). The key proteins of necroptosis in carotid plaques of smokers and non-smokers were also examined. Quantitative proteomics of mice aortas was conducted to further investigate the underlying mechanism. Pharmacological approaches were then applied to modulate the expression of targets to verify the regulatory process of tar-induced necroptosis. RESULTS: Tar administration led to increased atherosclerotic plaque area and reduced collagen and VSMCs in ApoE-/- mice. The expression of RIPK1、RIPK3、and MLKL in VSMCs of plaques were all increased in tar-exposed mice and smokers. RIPK3 deletion protected against VSMC loss and plaque progression stimulated by tar. In mechanistic studies, quantitative proteomics analysis of ApoE-/- mice aortas suggested that tar triggered endoplasmic reticulum (ER) stress. PERK-eIF2α-CHOP axis was activated in tar-treated VSMCs and atherosclerotic plaque. Inhibition of ER stress using 4PBA significantly reduced plaque progression and VSMC necroptosis. Further study revealed that ER stress resulted in calcium (Ca2+) release into mitochondria and cytoplasm. Elevated Ca2+ levels lead to mitochondrial dysfunction and excessive reactive oxygen species (ROS) production, which consequently promote RIPK3-dependent necroptosis. In addition, Ca2+/calmodulin-dependent protein kinase II (CaMKII) activated by cytosolic Ca2+ overload binds to RIPK3, accounting for necroptosis. CONCLUSION: The findings revealed that cigarette tar promoted atherosclerosis progression by inducing RIPK3-dependent VSMC necroptosis and identified novel avenues of ER stress and Ca2+ overload.

The effect of secondhand smoke exposure on dental caries and gingival health among schoolchildren in Damascus, Syria: a cross-sectional study.

OBJECTIVE: This study aimed to evaluate the effect of secondhand smoke on dental caries and gingival health among schoolchildren in Damascus, Syria. MATERIALS AND METHODS: This was a cross-sectional study. It was carried out at government schools in Damascus, Syria. This study included healthy children aged 10 to 13 years old. Schoolchildren were interviewed to answer the researcher-administered questionnaire to obtain answers regarding demographic information and family smoking behavior. A dental examination was performed by a dentist, and the number of decayed (D), missing (M), and filled (F) permanent teeth (DMFT) was scored based on the World Health Organization (WHO) 1997. A gingival examination was performed using the modified gingival index (MGI) and Silness-Leo plaque index (PI) to assess gingival inflammation and plaque accumulation, respectively. RESULTS: A total of 284 schoolchildren participated. More than half (61.26%) of them were exposed to secondhand smoke (SHS), and about half of them (52.11%) resided in a house with at least one cigarette smoked in a day. About one-third of the passive smokers (33.30%) had poor plaque control, with a statistically significant difference from non-passive smokers (p < 0.05). The multivariate regression model showed that the number of smokers at home was significantly associated with the DMFT score, dental plaque accumulation, and gingival inflammation (p < 0.1). However, the number of cigarettes smoked at home in a day was not a predictor for dental caries and gingival status (p = 1.000). CONCLUSIONS: Within the limitations of this study, the number of smokers at home appears to have more adverse effects on children's oral health compared to the quantity of smoke inhaled. In addition, SHSe was associated with more dental plaque accumulation among schoolchildren.

Cigarette tar mediates macrophage ferroptosis in atherosclerosis through the hepcidin/FPN/SLC7A11 signaling pathway.

Despite the known promotional effects of cigarette smoking on progression of atherosclerosis (AS), tar as the most dominant toxic component in cigarette smoking has been little studied. Understanding the potential role and mechanisms of tar in AS may be a prerequisite for future reductions in cardiovascular morbidity and mortality. Male ApoE-/- mice were fed with high-fat diet and injected intraperitoneally with cigarette tar (40 mg/kg/day) for 16 weeks. The results showed that cigarette tar significantly promoted the formation of lipid-rich plaques with larger necrotic cores and less fibrous, and caused severe iron overload and lipid peroxidation in AS lesions. Moreover, tar significantly upregulated the expression of hepcidin and downregulated FPN and SLC7A11 of macrophages in AS plaques. Ferroptosis inhibitor (FER-1 and DFO) treatment, hepcidin-knockdown or SLC7A11-overexpression reversed above changes, thereby delaying the progression of atherosclerosis. In vitro, the use of FER-1, DFO, si-hepcidin, and ov-SLC7A11 increased cell viability and inhibited iron accumulation, lipid peroxidation and GSH depletion in tar treated macrophages. These interventions also inhibited the tar induced upregulation of hepcidin, and increased the expression of FPN, SLC7A11, and GPX4. Furthermore, NF-κB inhibitor reversed the regulatory effect of tar on hepcidin/FPN/SLC7A11 axis, and then inhibiting macrophage ferroptosis. These findings indicated that cigarette tar promotes atherosclerosis progression by inducing macrophage ferroptosis via NF-κB-activated hepcidin/FPN/SLC7A11 pathway.

A Novel Chemiluminescent Method for Efficient Evaluation of Heterogeneous Fenton Catalysts Using Cigarette Tar.

The evaluation of the catalytic capacity of catalysts is indispensable research, as catalytic capacity is a crucial factor to dictate the efficiency of heterogeneous Fenton catalysis. Herein, we obtained cigarette tar-methanol extracts (CTME) by applying methanol to cigarette tar and found that CTME could cause CL reactions with Fe2+/H2O2 systems in acidic, neutral, and alkaline media. The CL spectrum experiment indicated that the emission wavelengths of the CTME CL reaction with Fe2+/H2O2 systems were about 490 nm, 535 nm, and 590 nm. Quenching experiments confirmed that hydroxyl radicals (•OH) were responsible for the CL reaction for CTME. Then the CL property of CTME was applied in-situ to rapidly determine the amounts of •OH in tetrachloro-1,4-benzoquinone (TCBQ)/H2O2 system in acidic, neutral and alkaline media, and the CL intensities correlated the best (R2 = 0.99) with TCBQ concentrations. To demonstrate the utility of the CTME CL method, the catalytic capacity of different types and concentrations of catalysts in heterogeneous Fenton catalysis were examined. It was found that the order of CL intensities was consistent with the order of degradation efficiencies of Rhodamine B, indicating that this method could distinguish the catalytic capacity of catalysts. The CTME CL method could provide a convenient tool for the efficient evaluation of the catalytic capacity of catalysts in heterogeneous Fenton catalysis.

Aqueous cigarette tar extracts disrupt corticogenesis from human embryonic stem cells in vitro.

BACKGROUND: Cigarette butts are the most common form of litter in the world, and approximately 4.5 trillion smoked cigarettes are discarded every year worldwide. Cigarette butts contain over 4000 chemicals, many of which are known to have neurotoxic effects. Stem cell neuronal differentiation provides an excellent cellular model with which to examine the impact of aqueous cigarette tar extracts (ACTEs) on neurodevelopment. METHODS: We have developed a neurosphere-based stem cell neuronal differentiation protocol that can recapitulate corticogenesis and produce cell types that are similar to upper and lower layer cortical projection neurons found in the germinal zone of the developing human cortex. In this study, ACTEs were generated from smoked cigarette butts and then applied at different concentrations to neuronal progenitors and cortical neurons derived from human embryonic stem cells. RESULTS: ACTEs reduced the expression of the cortical neuronal progenitor markers pax6, tbr2, and neuroD and decreased the number of cortical layer neurons (tbr1, satb2, foxp2, and brn2) after exposure to as low as 1.87% of the extract from one smoked cigarette butt. Furthermore, our results showed that ACTEs increased reactive oxygen species (ROS) production in cortical neurons, which caused a substantial loss of the synaptic proteins PSD95, synaptophysin, vesicular glutamate transporter1 (vGlut1), and the extracellular matrix molecule reelin; all of those molecules are important for the maintenance of cortical neuron identity and activity. CONCLUSION: ACTEs from smoked cigarettes have significant effects on cortical neuron development and neurodegeneration. The stem cell neuronal differentiation model holds great promise as a potentially powerful tool for the assessment of ACTEs on neurotoxicity.