Nicotine regulates basic fibroblastic growth factor and transforming growth factor beta1 production in endothelial cells

Smoking Cessation and Incident Atrial Fibrillation in a Longitudinal Cohort

BACKGROUND

Although smoking heightens the risk of AF, it remains unknown if that risk is amenable to modification after smoking cessation.

OBJECTIVES

This study sought to evaluate the association between smoking cessation and atrial fibrillation (AF) risk in a large longitudinal cohort.

METHODS

After excluding those with prevalent AF and no history of smoking at baseline, we evaluated 146,772 UK Biobank participants with serial smoking assessments. We compared AF risk between former smokers at baseline and those who quit smoking during the study to current smokers. Incident AF was ascertained from outpatient and inpatient encounters and identified using International Classification of Diseases codes. Cox models were used to compare the risk of incident AF among current and former smokers as well as those who quit smoking during the study while controlling for age, sex, race, body mass index, education, cardiovascular comorbidities, alcohol use, and pack-years.

RESULTS

Among the 146,772 participants (48.3% female; age: 57.3 ± 7.9 years), 37,377 (25.5%) currently smoked; 105,429 (72.0%) were former smokers; and 3,966 (2.7%) quit smoking during the study. Over a mean 12.7 ± 2.0 years of follow-up, 11,214 (7.6%) participants developed AF. Compared to current smokers, the adjusted risk of AF was 13% lower in former smokers (HR: 0.87; 95% CI: 0.83-0.91) and 18% lower in those who quit smoking during the study (HR: 0.82; 95% CI: 0.70-0.95).

CONCLUSIONS

Compared to those who continue to smoke, smoking cessation was associated with a lower risk of AF.

Nicotinic acetylcholine receptors in cancer: Limitations and prospects

Nicotinic acetylcholine receptors (nAChRs) have long been considered to solely mediate neurotransmission. However, their widespread distribution in the human body suggests a more diverse physiological role. Additionally, the expression of nAChRs is increased in certain cancers, such as lung cancer, and has been associated with cell proliferation, epithelial-to-mesenchymal cell transition, angiogenesis and apoptosis prevention. Several compounds that interact with these receptors have been identified as potential therapeutic agents. They have been tested as drugs for treating nicotine addiction, alcoholism, depression, pain and Alzheimer's disease. This review focuses on nAChR-mediated signalling in cancer, presenting opportunities for the development of innovative nAChR-based anticancer drugs. It displays the differences in expression of each nAChR subunit between normal and cancer cells for selected cancer types, highlighting their possible involvement in specific cases. Antagonists of nAChRs that could complement existing cancer therapies are summarised and critically discussed. We hope that this review will stimulate further research on the role of nAChRs in cancer potentially leading to innovative cancer therapies.

Circulating Angiogenic Factors and Ischemic Diabetic Foot Syndrome Advancement-A Pilot Study

Despite clear evidence of inadequate angiogenesis in ischemic diabetic foot syndrome (DFS) pathogenesis, angiogenic factor level changes in patients with ischemic DFS remain inconsistent. This study aimed to assess circulating angiogenic factors concerning ischemic DFS advancement and describe their relationships with patients' clinical characteristics, microvascular parameters, and diabetic control. The study included 41 patients with ischemic DFS (67.3 (8.84) years; 82.9% males). Angiogenic processes were assessed by identifying circulating concentrations of five pro- and two anti-angiogenic factors. We found that penetrating ulcers were related to a significantly higher FGF-2 level (8.86 (5.29) vs. 5.23 (4.17) pg/mL, p = 0.02). Moreover, plasma FGF-2 showed a significant correlation with the SINBAD score (r = 0.32, p = 0.04), platelet count (r = 0.43, p < 0.01), white cell count (r = 0.42, p < 0.01), and age (r = -0.35, p = 0.03). We did not observe any significant linear relationship between the studied biomarkers and microcirculatory parameters, nor for glycemic control. In a univariate analysis using logistic regression, an increase in plasma FGF-2 was tied to greater odds of high-grade ulcers (OR 1.16; 95% CI 1.02-1.38, p = 0.043). This suggests that circulating FGF-2 may serve as a potential biomarker for predicting DFU advancement and progression. It is necessary to conduct further studies with follow-up observations to confirm this hypothesis.

Does the Expression of Vascular Endothelial Growth Factor (VEGF) and Bcl-2 Have a Prognostic Significance in Advanced Non-Small Cell Lung Cancer?

Lung cancer is the most common cause of mortality from malignant tumors worldwide. The five-year survival rate for people with advanced stages varies considerably, from 35.4% to 6.9%. The angiogenic potential of bcl2 is not well known, nor is the way in which tumor cells with excessive bcl2 expression affect VEGF production. Hypothetically, given that tumor growth, progression and metastasis are dependent on angiogenesis, the antiapoptotic effect is expected to form a link between these two molecules. The aim of this study was to evaluate the relationship between bcl-2 and VEGF expression, clinicopathological features and survival in 216 patients with advanced NSCLC. Archival tumor tissues were examined by immunohistochemistry for the expression of bcl-2 and VEGF. Immunoreactivity for bcl-2 was observed in 41.4% of NSCLCs, 51% of squamous and 34.8% of adenocarcinomas-expressed Bcl-2. There was an inverse correlation of mononuclear stromal reaction and bcl-2 expression in adenocarcinoma (p < 0.0005). A total of 71.8% NSCLCs were VEGF positive, 56% of squamous and 82.2% of adenocarcinomas. High level of VEGF expression was significantly associated with histology type (p = 0.043), low histology grade (p = 0.014), clinical stage IV (p = 0.018), smoking history (p = 0.008) and EGFR mutations (p = 0.026). There was an inverse correlation in the expression of Bcl-2 and VEGF in NSCLC patients (p = 0.039, r = -0.163). Two-year survival of patients with unresectable NSCLC was 39.3%, and 50% of patients were alive at 17 months. Our results demonstrated no difference in survival for patients in advanced NSCLC grouped by bcl-2 and VEGF status. Additionally, we observed an inverse correlation in the expression of Bcl-2 and VEGF in NSCLC and mononuclear reaction and bcl-2 expression in adenocarcinomas.

Harmful Impact of Tobacco Smoking and Alcohol Consumption on the Atrial Myocardium

Tobacco smoking and alcohol consumption are widespread exposures that are legal and socially accepted in many societies. Both have been widely recognized as important risk factors for diseases in all vital organ systems including cardiovascular diseases, and with clinical manifestations that are associated with atrial dysfunction, so-called atrial cardiomyopathy, especially atrial fibrillation and stroke. The pathogenesis of atrial cardiomyopathy, atrial fibrillation, and stroke in context with smoking and alcohol consumption is complex and multifactorial, involving pathophysiological mechanisms, environmental, and societal aspects. This narrative review summarizes the current literature regarding alterations in the atrial myocardium that is associated with smoking and alcohol.

Serum levels of TGF-β1, cytokines, angiogenic, and anti-angiogenic factors in pregnant women who smoke

INTRODUCTION

Women who smoke during pregnancy have a reduced risk of preeclampsia. The mechanism of this association is poorly understood. Preeclampsia is an anti-angiogenic and inflammatory state. Transforming growth factor beta 1 (TGF-β1) is a multi-functional anti-inflammatory cytokine that activates membrane bound endoglin on endothelial cells causing a myriad of vascular actions including vasorelaxation. The objective of the study was to determine serum levels of cytokines, angiogenic factors, placental growth factor (PlGF), TGF-β-1 and anti-angiogenic factors, soluble endoglin (sEng) and soluble vascular endothelial growth factor 1 (sVEGFR1) in smoking and non-smoking pregnant women.

METHODS

Using enzyme-linked immunosorbent and multiplex assays we prospectively analyzed serum levels of PIGF, TGF-β1, sEng, sVEGFR1 and cytokines in normotensive pregnant smokers and non-smokers. Exclusion criteria included maternal hypertension, autoimmune disorders, rupture of membranes, evidence of labor and drug use.

RESULTS

There were 59 women in the smoking and 66 in the non-smoking group. Compared to non-smoking mothers. maternal age was lower in smoking mothers with no significant difference in other demographic variables. There was no difference in levels of cytokines, anti-angiogenic factors and PlGF between the two groups. Median TGF-β1 levels were significantly higher in the smoking group (8120 pg/mL vs 6040 pg/mL, p < 0.001) and remained significant after controlling for confounders. TGF-β1 levels correlated positively with cotinine levels in the smoking group.

CONCLUSIONS

We speculate that higher TGF-β1 levels may explain the reduced incidence of preeclampsia in mothers who smoke by being available for action on maternal endothelium even after inactivation by circulating maternal sEng.

Nicotine: Regulatory roles and mechanisms in atherosclerosis progression

Smoking is an independent risk factor for atherosclerosis. The smoke produced by tobacco burning contains more than 7000 chemicals, among which nicotine is closely related to the occurrence and development of atherosclerosis. Nicotine, a selective cholinergic agonist, accelerates the formation of atherosclerosis by stimulating nicotinic acetylcholine receptors (nAChRs) located in neuronal and non-neuronal tissues. This review introduces the pathogenesis of atherosclerosis and the mechanisms involving nicotine and its receptors. Herein, we focus on the various roles of nicotine in atherosclerosis, such as upregulation of growth factors, inflammation, and the dysfunction of endothelial cells, vascular smooth muscle cells (VSMC) as well as macrophages. In addition, nicotine can stimulate the generation of reactive oxygen species, cause abnormal lipid metabolism, and activate immune cells leading to the onset and progression of atherosclerosis. Exosomes, are currently a research hotspot, due to their important connections with macrophages and the VSMC, and may represent a novel application into future preventive treatment to promote the prevention of smoking-related atherosclerosis. In this review, we will elaborate on the regulatory mechanism of nicotine on atherosclerosis, as well as the effects of interference with nicotine receptors and the use of exosomes to prevent atherosclerosis development.

Endothelial to mesenchymal transition contributes to nicotine-induced atherosclerosis

Rationale: Nicotine exposure via cigarette smoking is strongly associated with atherosclerosis. However, the underlying mechanisms remain poorly understood. The current study aimed to identify whether endothelial to mesenchymal transition (EndMT) contributes to nicotine-induced atherosclerosis. Methods: ApoE-/- mice were administered nicotine in their drinking water for 12 weeks. The effects of nicotine on EndMT were determined by immunostaining on aortic root and RNA analysis in aortic intima. In vitro nicotine-treated cell model was established on human aortic endothelial cells (HAECs). The effects of nicotine on the expression of EndMT-related markers, ERK1/2 and Snail were quantified by real-time PCR, western blot and immunofluorescent staining. Results: Nicotine treatment resulted in larger atherosclerotic plaques in ApoE-/- mice. The vascular endothelial cells from nicotine-treated mice showed mesenchymal phenotype, indicating EndMT. Moreover, nicotine-induced EndMT process was accompanied by cytoskeleton reorganization and impaired barrier function. The α7 nicotine acetylcholine receptor (α7nAChR) was highly expressed in HAECs and its antagonist could effectively relieve nicotine-induced EndMT and atherosclerotic lesions in mice. Further experiments revealed that ERK1/2 signaling was activated by nicotine, which led to the upregulation of Snail. Blocking ERK1/2 with inhibitor or silencing Snail by small interfering RNA efficiently preserved endothelial phenotype upon nicotine stimulation. Conclusion: Our study provides evidence that EndMT contributes to the pro-atherosclerotic property of nicotine. Nicotine induces EndMT through α7nAChR-ERK1/2-Snail signaling in endothelial cells. EndMT may be a therapeutic target for smoking-related endothelial dysfunction and cardiovascular disease.

Elevated Plasma Transforming Growth Factor β1 Levels Predict the Development of Hypertension in Normotensives: The 14-Year Follow-Up Study

BACKGROUND

Transforming growth factor β1 (TGF-β1) is a multifunctional cytokine. There is growing evidence that TGF-β1 is involved in the pathogenesis of hypertension and the development of target organ damage in hypertensives. Although several studies have shown that TGF-β1 induced vascular hypertrophy and remodelling in various vascular diseases, there are no longitudinal data on hypertension in the epidemiological studies. The present study tested the hypothesis whether elevated TGF-β1 levels can predict the development of hypertension.

METHODS

In 2002-2004, 528 subjects received health examinations in Uku town, southwestern Japan. We examined blood pressure (BP), body mass index, and blood test. Data on fasting plasma TGF-β1 were obtained from 528 individuals. Of these, 149 normotensives (BP <140/90 mm Hg without antihypertensive medications) at baseline were followed-up for 14 years.

RESULTS

The receiver-operating characteristic curve was used and the calculated cutoff value was 8.9 ng/ml. Of 149 normotensives at baseline, 59 subjects developed hypertension. Plasma TGF-β1 levels were significantly associated with the development of hypertension after adjustment for confounding factors. To further examine the association between them, we performed logistic regression analysis. We divided the baseline plasma TGF-β1 levels into 2 groups using a cutoff value. The significant high odds ratio [3.582 (95% confidence interval, 1.025-12.525)] for the development of hypertension was found in the highest group of TGF-β1 level vs. the lowest group after adjustment for confounders.

CONCLUSIONS

This is the first report demonstrating the causal relationship between them. Elevated plasma TGF-β1 levels predicted the development of hypertension in normotensives in a population of community-dwelling Japanese.

Endothelial Cell Inflammatory Reactions Are Altered in the Presence of E-Cigarette Extracts of Variable Nicotine

Exposure to tobacco smoke has been associated with heightened endothelial cell activities associated with cardiovascular diseases (CVD). Conversely, the exposure to nicotine both activates and inhibits particular endothelial cell functions. However, which constituent(s) of tobacco smoke is responsible for these changes is unknown, since toxic gases and fine particulate matter cannot be isolated. Electronic cigarette vapor allows us to isolate these constituents, providing us the ability to evaluate individual constituents. Here, we used e-cigarettes to (1) identify which constituents of tobacco products are most responsible for altered CVD functions and (2) elucidate the underlying risk of e-cigarette exposure. To accomplish this goal, endothelial cells were exposed to extracts produced from tobacco cigarettes or e-cigarettes. Endothelial cell inflammatory processes, viability, density and metabolic activity were observed. In general, a significant increase in complement deposition, the expression of the receptors for C1q, coupled with a decrease in cell proliferation and metabolic activity was observed. These results were independent of nicotine and the exposure to e-vapor was just as harmful as tobacco smoke extracts. Thus, the exposure to fine particulate matter and not toxic combustion gases or nicotine may be the most critical for regulating CVD progression.

β-arrestin-1 mediates nicotine-induced metastasis through E2F1 target genes that modulate epithelial-mesenchymal transition

Cigarette smoking is a major risk factor in the development of non-small cell lung cancer (NSCLC), which accounts for 80% of all lung cancers. Nicotine, the major addictive component of tobacco smoke, can induce proliferation, invasion, and epithelial-to-mesenchymal transition (EMT) in NSCLC cell lines and promote metastasis of NSCLC in mice. Here, we demonstrate that the scaffolding protein β-arrestin-1 is necessary for nicotine-mediated induction of mesenchymal genes vimentin and fibronectin as well as EMT regulators ZEB1 and ZEB2. Nicotine induced changes in cell morphology and ablate tight junctions consistent with EMT; β-arrestin-1, but not β-arrestin-2, was required for these changes. β-Arrestin-1 promoted the expression of the mesenchymal genes, as well as ZEB1 and ZEB2, through the mediation of the E2F1 transcription factor; this required Src kinase activity. Stimulation of multiple NSCLC cell lines with nicotine led to enhanced recruitment of β-arrestin-1 and E2F1 on vimentin, fibronectin, and ZEB1 and ZEB2 promoters. Furthermore, there was significantly more β-arrestin-1 and E2F1 associated with these promoters in human NSCLC tumors, and β-arrestin-1 levels correlated with vimentin and fibronectin levels in human NSCLC samples. A549-luciferase cells lacking β-arrestin-1 showed a significantly reduced capacity for tumor growth and metastasis when orthotopically implanted into the lungs of SCID-beige mice. Taken together, these studies reveal a novel role for β-arrestin-1 in the growth and metastasis of NSCLC.

Connections of nicotine to cancer

This Opinion article discusses emerging evidence of direct contributions of nicotine to cancer onset and growth. The list of cancers reportedly connected to nicotine is expanding and presently includes small-cell and non-small-cell lung carcinomas, as well as head and neck, gastric, pancreatic, gallbladder, liver, colon, breast, cervical, urinary bladder and kidney cancers. The mutagenic and tumour-promoting activities of nicotine may result from its ability to damage the genome, disrupt cellular metabolic processes, and facilitate growth and spreading of transformed cells. The nicotinic acetylcholine receptors (nAChRs), which are activated by nicotine, can activate several signalling pathways that can have tumorigenic effects, and these receptors might be able to be targeted for cancer therapy or prevention. There is also growing evidence that the unique genetic makeup of an individual, such as polymorphisms in genes encoding nAChR subunits, might influence the susceptibility of that individual to the pathobiological effects of nicotine. The emerging knowledge about the carcinogenic mechanisms of nicotine action should be considered during the evaluation of regulations on nicotine product manufacturing, distribution and marketing.

Development of vascular smooth muscle contractility by endothelium-derived transforming growth factor β proteins

It is well established that the release of vasodilators and vasoconstrictors from vascular endothelium regulates vascular smooth muscle contraction. In this report, we investigate the role of the endothelium in the development and maintenance of constitutive vascular contractility. For that purpose, contractile activity of cultured bovine aortic smooth muscle cells (BASMCs) embedded in collagen gels was monitored by changes in gel diameter. After culturing for 5 days, ATP- and high KCl solution-induced contractions were significantly enhanced in the gels that were overlaid with bovine aortic endothelial cells (BAECs) or were cultured with conditioned medium of cultured BAECs. ATP-induced Ca(2+) transients, recorded in BASMCs cultured with conditioned medium of BAECs, were markedly augmented, but high KCl-induced Ca(2+) transients were not affected. BASMCs in control gels were spindle shaped, and those in endothelium-treated gels were more elongated and interconnected. The endothelial conditioned medium also strongly affected the intracellular distribution of actin fibers. Conditioned medium of BAECs contained TGFβ1 and TGFβ2. The TGFβ receptor antagonist SB431542 as well as simultaneous treatment with TGFβ1 and TGFβ2 neutralizing antibodies completely reversed the above effects of endothelial conditioned medium on BASMCs. BAECs medium induced phosphorylation of Smad2 and increased ATP-induced phosphorylation of myosin light chain in BASMCs. The present results indicate that the release of TGFβ1 and TGFβ2 from vascular endothelium affects the contractility of vascular smooth muscle cells by altering their morphology and agonist-induced Ca(2+) mobilization.

Nicotine signaling and progression of chronic kidney disease in smokers

The deleterious health effects of cigarette smoking are far reaching, and it remains the most important modifiable risk factor for improving overall morbidity and mortality. In addition to being a risk factor for cancer, cardiovascular disease and lung disease, there is strong evidence, both from human and animal studies, demonstrating a role for cigarette smoking in the progression of chronic kidney disease (CKD). Clinical studies have shown a strong correlation between cigarette smoking and worsening CKD in patients with diabetes, hypertension, polycystic kidney disease, and post kidney transplant. Nicotine, in addition to its role in the addictive properties of cigarette smoking, has other biological effects via activation of non-neuronal nicotinic acetylcholine receptors (nAChRs). Several nAChR subunits are expressed in the normal kidney and blockade of the α7-nAChR subunit ameliorates the effects of nicotine in animal models of CKD. Nicotine increases the severity of renal injury in animal models including acute kidney injury, diabetes, acute nephritis and subtotal nephrectomy. The renal effects of nicotine are also linked to increased generation of reactive oxygen species and activation of pro-fibrotic pathways. In humans, nicotine induces transitory increases in blood pressure accompanied by reductions in glomerular filtration rate and effective renal plasma flow. In summary, clinical and experimental evidence indicate that nicotine is at least in part responsible for the deleterious effects of cigarette smoking in the progression of CKD. The mechanisms involved are the subject of active investigation and may result in novel strategies to ameliorate the effects of cigarette smoking in CKD.

Endothelium-dependent epithelial-mesenchymal transition of tumor cells: exclusive roles of transforming growth factor β1 and β2

BACKGROUND

Induction of epithelial-mesenchymal transition (EMT) is essential for the metastasis of tumor cells and maintaining their stemness. This study aimed to examine whether endothelial cells, which are most closely located to tumor cells in vivo, play a role in inducing EMT in tumor cells or not.

METHODS

Concentrated culture medium of bovine aortic endothelial cells (BAECs) was applied to tumor cell lines (A549 and PANC-1) and epithelial cell line (NMuMg). Cadherin conversion, expressions of α-smooth muscle actin and ZO-1, actin fiber formation and cell migration were examined as hallmarks of the induction of EMT in these cell lines. Transforming growth factor β (TGFβ) antibodies were used to neutralize TGFβ1, TGFβ2 and TGFβ3. Expression and release of TGFβ proteins in BAECs as well as in porcine and human endothelial cells were assessed by Western blotting and ELISA, respectively.

RESULTS

Conditioned medium of BAEC induced EMT in the examined cell lines. All endothelial cells from various species and locations expressed TGFβ1 and TGFβ2 proteins and much lower level of TGFβ3 protein. Conditioned medium from these endothelial cells contained TGFβ1 and TGFβ2, but TGFβ3 could not be detected. Neutralizing antibody against each of TGFβ1 or TGFβ2 did not reverse endothelium-dependent EMT, but simultaneous neutralization of both TGFβ1 and TGFβ2 completely abolished it.

CONCLUSIONS

Endothelial cells may play a role in the induction and maintenance of EMT in tumor cells by constitutively releasing TGFβ1 and TGFβ2.

GENERAL SIGNIFICANCE

The present results provide a novel strategy of the inhibition of tumor metastasis by targeting vascular endothelium.

The effects of continuing and discontinuing smoking on the development of chronic kidney disease (CKD) in the healthy middle-aged working population in Japan

OBJECTIVES

The strength of the association between smoking and the development of chronic kidney disease (CKD) in the healthy middle-aged working age population has not been established.

METHODS

This was a retrospective 6-year observational study involving 4,121 male and 2,877 female workers who were free of primary kidney disease, diabetes mellitus, severe hypertension, and the signs and symptoms of CKD. Proteinuria was detected by a dipstick method, and glomerular filtration rate (GFR) was estimated by the equation of the Japan Society of Nephrology.

RESULTS

Sixty men (1.5 %) and 21 women (0.7 %) developed proteinuria over the 6 years of the study. Irrespective of sex, in comparison with non-smokers, those who continued smoking showed an odds ratio (OR) of 2.52 with a 95 % confidence interval (CI) of 1.50-4.25 for developing proteinuria while those who quit smoking showed an OR of 1.29 (95 % CI 0.48-3.42), following adjustment for confounders. Among the study population, 443 men (10.7 %) and 356 women (12.4 %) developed a GFR of <60 mL/min/1.73 m(2), corresponding to stage III CKD. Continuing smokers had a low OR (0.74, 95 % CI 0.60-0.90) for developing a low GFR, as well as a higher mean GFR than non-smokers. The reduction in GFR during the 6-year study period was not different between smokers and non-smokers, but it was larger in those who developed proteinuria than in those who did not, irrespective of smoking.

CONCLUSIONS

Continuing smokers showed a twofold or more higher risk of developing proteinuria. Discontinuation of smoking substantially reduced the risk. A longer observational period may be required to detect the smoking-induced risk of developing stage III CKD in the middle-aged working population.

Smoking in diabetic nephropathy: sparks in the fuel tank?

Diabetic nephropathy is associated with high morbidity and mortality and the prevalence of this disease is continuously increasing worldwide. Long-term diabetes increases the likelihood of developing secondary complications like nephropathy, the most common cause of end stage renal disease. Usually, other factors like hypertension, alcoholism and smoking also partly contribute to the progression of diabetic nephropathy. Among this, cigarette smoking in diabetes has been repeatedly confirmed as an independent risk factor for the onset and progression of diabetic nephropathy. Various studies suggest that smoking is a major fuel in the development of high oxidative stress and subsequently hyperlipidemia, accumulation of advanced glycation end products, activation of the renin angiotensin system and Rho-kinase, which are observed to play a pathogenic role in the progression of diabetic nephropathy. Furthermore, cigarette smoking in diabetic patients with vascular complications produces a variety of pathological changes in the kidney, such as thickening of the glomerular basement membrane and mesangial expansion with progression in glomerulosclerosis and interstitial fibrosis, which ultimately results in end stage renal failure. Strong associations are consistently found between chronic cigarette smoking and diabetic microvascular complications. A diverse group of studies unveil potential mechanisms that may explain the role of cigarette smoking in the progression of diabetic nephropathy. Tremendous efforts are being made to control smoking mediated progression of diabetic nephropathy, but no promising therapy is yet available. The present review critically discusses the possible detrimental role of chronic cigarette smoking in the progression of diabetic nephropathy and various possible pharmacological interventions to attenuate the exacerbation of diabetic nephropathy.

Treating a collagen scaffold with a low concentration of nicotine promoted angiogenesis and wound healing

BACKGROUND

Nicotine, one of the major pharmacologically active agents of cigarette smoke, has various effects on cell proliferation, and it has recently been reported to have angiogenic effects. In our previous study, we showed that the topical administration of nicotine at a low concentration accelerated wound healing. This study aimed to evaluate the efficacy of nicotine and synergistic effects of combination treatment with nicotine and basic fibroblast growth factor (bFGF) in a murine excisional wound model treated with artificial dermis.

METHODS

Full-thickness defects (8 mm in diameter) were created on the backs of mice, and artificial dermis was sutured to the defects. Phosphate-buffered saline (10 μL), nicotine (10(-3), 10(-4), or 10(-5) M), bFGF (0.5 μg), and both bFGF and 10(-4) M nicotine were topically administered to the artificial dermal tissue for 7 d. The mice were killed on day 14, and the wound area, neoepithelium length, and area of newly formed capillaries in the artificial dermis were evaluated.

RESULTS

The wound areas treated with 10(-4) M nicotine, bFGF, or bFGF plus 10(-4) M nicotine were significantly smaller than those in the control group. In these three groups, the neoepithelium in the bFGF plus 10(-4) M nicotine group was significantly longer than that in the other groups. There was no significant difference between the neoepithelium lengths of the control and 10(-5) M nicotine groups. The 10(-3) M nicotine group displayed the least re-epithelization among the groups.

CONCLUSIONS

In this study, 10(-4) M nicotine induced angiogenesis in, and accelerated the healing of, wounds treated with artificial dermis. bFGF and nicotine had synergistic effects, and the combined use of nicotine and bFGF is an effective wound healing method.

Nicotine, cigarette smoking and cardiac arrhythmia: an overview

Tobacco smoke is the single most important modifiable risk factor for coronary diseases and the leading preventable cause of death in the US. While the effect of cigarette smoking on the progression of atherosclerotic diseases is established and well studied, the role of cigarette smoking on cardiac arrhythmia is less clearly defined. In fact the pathophysiological mechanism of cigarette smoking-induced cardiac arrhythmia is very likely a complex one where the pro-fibrotic effect of nicotine on myocardial tissue with consequent increased susceptibility to catecholamine might play a role. Moreover, other constituents of cigarette smoking, such as carbon monoxide and oxidative stress, are likely to contribute to the generation of arrhythmias. Finally, cigarette smoking may induce coronary artery disease and chronic obstructive pulmonary disease, which also might cause arrhythmia independently. The objective of this paper is to summarize the published studies relating to cardiac arrhythmia induced by cigarette smoking, and to identify a pathophysiological mechanism by which cigarette smoking might induce cardiac arrhythmia.

Very low nicotine content cigarettes and potential consequences on cardiovascular disease

Cigarette smoking remains highly prevalent in the U.S. and contributes significantly to cardiovascular disease (CVD). Tobacco control policies, including product regulation, can reduce smoking-related harm. One approach being considered in the U.S. is for the FDA to set a low nicotine standard for cigarettes. Such a standard could result in multiple beneficial outcomes including reduced cardiovascular toxicity related to nicotine, reduced smoking intensity in current smokers, increased cessation rates, decreased development of smoking dependence in youth, and decreased passive smoke exposure. Consequently, CVD risk in the U.S. could be dramatically improved by nicotine reduction in cigarettes. Possible pathways linking nicotine reduction in cigarettes to decreased CVD risk are discussed, while potential unintended consequences that could offset expected gains are also presented. Gaps in the literature, including limited data on CVD biomarkers and long-term CVD outcomes following the use of very low nicotine cigarettes, are discussed to highlight areas for new research.

MG624, an α7-nAChR antagonist, inhibits angiogenesis via the Egr-1/FGF2 pathway

Small cell lung cancer (SCLC) demonstrates a strong etiological association with smoking. Although cigarette smoke is a mixture of about 4,000 compounds, nicotine is the addictive component of cigarette smoke. Several convergent studies have shown that nicotine promotes angiogenesis in lung cancers via the α7-nicotinic acetylcholine receptor (α7-nAChR) on endothelial cells. Therefore, we conjectured that α7-nAChR antagonists may attenuate nicotine-induced angiogenesis and be useful for the treatment of human SCLC. For the first time, our study explores the anti-angiogenic activity of MG624, a small-molecule α7-nAChR antagonist, in several experimental models of angiogenesis. We observed that MG624 potently suppressed the proliferation of primary human microvascular endothelial cells of the lung (HMEC-Ls). Furthermore, MG624 displayed robust anti-angiogenic activity in the Matrigel, rat aortic ring and rat retinal explant assays. The anti-angiogenic activity of MG624 was assessed by two in vivo models, namely the chicken chorioallantoic membrane model and the nude mice model. In both of these experimental models, MG624 inhibited angiogenesis of human SCLC tumors. Most importantly, the administration of MG624 was not associated with any toxic side effects, lethargy or discomfort in the mice. The anti-angiogenic activity of MG624 was mediated via the suppression of nicotine-induced FGF2 levels in HMEC-Ls. MG624 decreased nicotine-induced early growth response gene 1 (Egr-1) levels in HMEC-Ls, and reduced the levels of Egr-1 on the FGF2 promoter. Consequently, this process decreased FGF2 levels and angiogenesis. Our findings suggest that the anti-angiogenic effects of MG624 could be useful in anti-angiogenic therapy of human SCLCs.

Pharmacological effects of Radix Angelica Sinensis (Danggui) on cerebral infarction

Radix Angelica Sinensis, the dried root of Angelica sinensis (Danggui), is a herb used in Chinese medicine to enrich blood, promote blood circulation and modulate the immune system. It is also used to treat chronic constipation of the elderly and debilitated as well as menstrual disorders. Research has demonstrated that Danggui and its active ingredients, as anti-arthrosclerotic, anti-hypertensive, antioxidant anti-inflammatory agents which would limit platelet aggregation, are effective in reducing the size of cerebral infarction and improving neurological deficit scores.

Genome-wide expression analysis reveals diverse effects of acute nicotine exposure on neuronal function-related genes and pathways

Previous human and animal studies demonstrate that acute nicotine exposure has complicated influences on the function of the nervous system, which may lead to long-lasting effects on the behavior and physiology of the subject. To determine the genes and pathways that might account for long-term changes after acute nicotine exposure, a pathway-focused oligoarray specifically designed for drug addiction research was used to assess acute nicotine effect on gene expression in the neuron-like SH-SY5Y cells. Our results showed that 295 genes involved in various biological functions were differentially regulated by 1 h of nicotine treatment. Among these genes, the expression changes of 221 were blocked by mecamylamine, indicating that the majority of nicotine-modulated genes were altered through the nicotinic acetylcholine receptors (nAChRs)-mediated signaling process. We further identified 14 biochemical pathways enriched among the nicotine-modulated genes, among which were those involved in neural development/synaptic plasticity, neuronal survival/death, immune response, or cellular metabolism. In the genes significantly regulated by nicotine but blocked by mecamylamine, 13 enriched pathways were detected. Nine of these pathways were shared with those enriched in the genes regulated by nicotine, including neuronal function-related pathways such as glucocorticoid receptor signaling, p38 MAPK signaling, PI3K/AKT signaling, and PTEN signaling, implying that nAChRs play important roles in the regulation of these biological processes. Together, our results not only provide insights into the mechanism underlying the acute response of neuronal cells to nicotine but also provide clues to how acute nicotine exposure exerts long-term effects on the nervous system.

Cigarette smoking decreases TGF-b1 serum concentrations after long bone fracture

TGF-b1 serum concentrations are considered to be one of the most promising markers of fracture healing. Previously, we demonstrated significant differences in the post-traumatic time courses of patients with timely and delayed fracture healing. The aim of this study was to evaluate possible differences in the serum concentrations of TGF-b1 in cigarette-smoking vs. non-smoking patients with timely and delayed fracture healing in order to understand pathophysiological pathways through which smoking impairs fracture healing.Serum samples were collected from 248 patients undergoing surgical treatment for long bone fractures within 1 year of surgery. Samples from 14 patients with atrophic-type delayed fracture healing were compared with 14 matched patients with normal bone healing. Each group included seven smokers and seven non-smokers. Post-operative serum concentrations were analysed at 1, 2, 4, 8, and 12 weeks as well as 1 year after surgery. The patients were monitored both clinically and radiologically for the entire duration of the study.All patients increased TGF-b1 serum concentrations after surgery. In patients with normal fracture healing, significantly higher TGF-b1 levels were observed in non-smokers (70 ng/ml) than in smokers(50 ng/ml) at the 4th week after surgery (p = 0.007). Also at the 4th week, in patients with delayed healing, significantly lower TGF-b1 levels were observed in smokers than in non-smokers (38 ng/ml vs.47 ng/ml, p = 0.021). However, no significant differences between non-smokers with delayed healing and smokers with normal healing (p = 0.151) were observed at the 4th week after surgery. TGF-b1 serum concentrations reached a plateau in all groups from the 6th to the 12th week after surgery, with a slight decrease observed in the final measurement taken 1 year after surgery.This study demonstrates that, after fracture, TGF-b1 serum concentrations are reduced by smoking,and this reduction is statistically significant during the 4th week after surgery. Our findings may help reveal the mechanism by which smoking impairs fracture healing. Furthermore, these results may help to establish a serological marker that predicts impaired fracture healing soon after the injury. Surgeons will not only be able to monitor the bone healing, but they will also be able to monitor the success of additional treatments such as ultrasound and bone morphologic proteins (BMPs).

Nicotine worsens the severity of nephropathy in diabetic mice: implications for the progression of kidney disease in smokers

Epidemiological studies have established the role of cigarette smoking as a risk factor in the progression of chronic kidney disease, including diabetic nephropathy. We have previously reported that nicotine promotes mesangial cell proliferation and hypertrophy via activation of nonneuronal nicotinic acetylcholine receptors and that nicotine worsens renal injury in a model of acute glomerulonephritis (Jaimes E, Tian RX, Raij L. Am J Physiol Heart Circ Physiol 292: H76-H82, 2007; Jaimes EA, Tian RX, Joshi M, Raij L. Am J Nephrol 29: 319-326, 2009). These studies were designed to test the hypothesis that nicotine worsens renal injury in db/db mice, a well-established model of diabetic nephropathy, and that reactive oxygen species play an important as mediators of these effects. For these studies, nicotine (100 μg/ml) was administered in the drinking water to control and db/db mice for 10 wk. Blood pressure was measured by the tail-cuff method, and urine was collected for proteinuria. At death, kidneys were collected for histology and molecular biology. The administration of nicotine did not result in significant changes in blood pressure or blood glucose and resulted in cotinine levels similar to those found in the plasma of smokers. In diabetic mice, the administration of nicotine significantly increased urinary protein excretion (1-fold), glomerular hypertrophy, and mesangial area (∼20%). These changes were accompanied by significant increases in NADPH oxidase 4 (∼30%) and increased nitrotyrosine and Akt expression. In vitro, we determined that nicotine has additive effects to high glucose on reactive oxygen species generation and Akt phosphorylation in human mesangial cells. These findings unveil novel mechanisms that may result in the development of novel strategies in the treatment and prevention of diabetic nephropathy in smokers.

Smoking and atherosclerotic cardiovascular disease: part II: role of cigarette smoking in cardiovascular disease development

Potential mechanisms and biomarkers of atherosclerosis related to cigarette smoking - a modifiable risk factor for that disease - are discussed in this article. These include smoking-associated inflammatory markers, such as leukocytes, high-sensitivity C-reactive protein, serum amyloid A, ICAM-1 and IL-6. Other reviewed markers are indicative for smoking-related impairment of arterial endothelial function (transcapillary leakage of albumin, inhibition of endogenous nitric oxide synthase activity and reduced endothelium-dependent vasodilation) or point to oxidative stress caused by various chemicals (cholesterol oxidation, autoantibodies to oxidized low-density lipoprotein, plasma levels of malondialdehyde and F(2)-isoprostanes and reduced antioxidant capacity). Smoking enhances platelet aggregability, increases blood viscosity and shifts the pro- and antithrombotic balance towards increased coagulability (e.g., fibrinogen, von Willebrand factor, ICAM-1 and P-selectin). Insulin resistance is higher in smokers compared with nonsmokers, and hemoglobin A1c is dose-dependently elevated, as is homocysteine. Smoke exposure may influence the kinetics of markers with different response to transient or chronic changes in cigarette smoking behavior.

Effect of nicotine on gene expression of angiogenic and osteogenic factors in a rabbit model of bone regeneration

PURPOSE

This study aims to evaluate the influence of nicotine on the gene expression of osteogenic and angiogenic factors in bone regeneration by use of a nicotine-compromised rabbit model of mandibular lengthening.

MATERIALS AND METHODS

Thirty adult New Zealand white rabbits were randomly assigned to the nicotine group or the control group. The total nicotine or placebo exposure time for all animals was 7 weeks. Unilateral mandibular distraction osteogenesis was performed. Five animals in each group were sacrificed at day 5, day 11, and day 18, respectively, after commencement of active distraction. The distraction regenerate samples were harvested, and the messenger ribonucleic acid expression of bone transforming growth factor beta(1), platelet-derived growth factor A, and basic fibroblast growth factor was assayed by real-time polymerase chain reaction analysis.

RESULTS

The messenger ribonucleic acid expression of transforming growth factor beta(1), platelet-derived growth factor A, and basic fibroblast growth factor was significantly inhibited by nicotine exposure at a variety of time points.

CONCLUSIONS

The presence of nicotine inhibited the gene expression of angiogenic and osteogenic factors resulting in compromised bone regeneration.

Human cleft lip and palate fibroblasts and normal nicotine-treated fibroblasts show altered in vitro expressions of genes related to molecular signaling pathways and extracellular matrix metabolism

Nonsyndromic cleft lip with or without cleft palate (CLP) is a frequent craniofacial malformation caused by both genetic and environmental factors. Maternal smoking during pregnancy is a known risk factor, due to the teratogenic role of nicotine. To assess and compare the impact of CLP and nicotine, we studied the quantitative expression of genes involved in signaling pathways and extracellular matrix (ECM) metabolism in human normal nicotine-treated (NicN) and CLP fibroblasts compared to normal control (CTRL) cells. Palatal fibroblast cultures from seven CLP children and seven age-matched CTRL subjects were established and subconfluent cells incubated for 24 h without (CTRL and CLP fibroblasts) or with (NicN fibroblasts) 0.6 mM nicotine. Gene expressions were analyzed by real-time quantitative PCR. For the first time, a regulated cholinergic signaling in our human fibroblasts in vitro was demonstrated. Members of TGF-beta, retinoic acid (RA), and GABA-ergic signaling systems were also differently regulated. Among the ECM genes, fibronectin, syndecan, integrin alpha2, and MMP13 genes were concordantly modulated, while integrin beta5, and decorin genes were discordantly modulated. Interestingly, nicotine treatment regulated gene expressions of CD44 and CLPTM1, two candidate genes for CLP. Our findings show a positive association between nicotine treatment and CLP phenotype. Results suggest that nicotine deranges normal palate development, which might contribute to the development of a CLP malformative phenotype, through the impairment of some important signaling systems and ECM composition.

Angiogenic activity of nicotinic acetylcholine receptors: implications in tobacco-related vascular diseases

Cigarette smoking bears a strong etiological association with many neovascularization-related diseases like cancer, cardiovascular disease and macular degeneration. Although cigarette smoke is a complex mixture of many compounds, nicotine is the major active and addictive component of tobacco. Recent studies have shown that nicotine can enhance angiogenesis and arteriogenesis in several experimental systems and animal models. The pro-angiogenic activity of nicotine is mediated by nicotinic acetylcholine receptors, which have been found to be expressed on several types of cells in the vasculature like endothelial cells, smooth muscle cells and immune cells. The present review summarizes the pro-angiogenic activity of nicotine in neoplastic and non-neoplastic disease. The present article focuses on the role of nAChRs, particularly alpha7-nAChR in mediating the pro-angiogenic effects of nicotine. The expression patterns of nAChRs on various components of the vasculature are discussed. The complex signaling pathways underlying the angiogenic effect of nAChRs are described. The review also takes a look at the therapeutic potential of nAChR agonists and antagonists in angiogenesis-related diseases. More basic research as well as patient-oriented clinical studies is needed to firmly establish the clinical potential of nAChR ligands in angiogenesis-based therapies. Also the side effects of targeting nAChRs remain to be established in patients. The development of selective nAChR agonists and antagonists with improved specificity may represent novel therapeutic regimens in the treatment of angiogenesis-related diseases.

Effect of nicotine on human umbilical vein endothelial cells (HUVECs) migration and angiogenesis

The effects of nicotine on vascular endothelial cells have not been completely elucidated. We performed this study to assess the changes in cellular behaviors of human umbilical vein endothelial cells (HUVECs) treated with nicotine. We examined changes in cell count and morphology and assayed cellular migration with Boyden chamber and microcapillary tube formation in a Matrigel matrix following treatment with various concentrations of nicotine. Compared to the control, nicotine stimulated cell proliferation, migration, and tube formation at concentrations similar to those found in smokers. Although there were no specific morphological changes in HUVECs treated with nicotine at the concentration similar to that in smokers, at high concentration (10(-4) M), morphological changes such as cytoplasmic vacuolization and irregular cell shape were observed, which were assumed to be the result of direct cytotoxicity of nicotine. In HUVECs, nicotine enhanced cellular proliferation, migration and angiogenesis in vitro, and thus caused a functional change, not a morphological change at a concentration similar to that in habitual smokers.

Smoking: a risk factor for progression of chronic kidney disease and for cardiovascular morbidity and mortality in renal patients--absence of evidence or evidence of absence?

Although it is beyond any doubt that smoking is the number one preventable cause of death in most countries, smoking as an independent progression factor in renal disease has been questioned against the background of evidence-based criteria. This is because information from large, randomized, prospective studies that investigate the effects of smoking on renal function in healthy individuals as well as in patients with primary or secondary renal disease are lacking. Since 2003, a substantial number of clinical and experimental data concerning the adverse renal effects of smoking have been published, including large, prospective, population-based, observational studies. These more recent data together with evidence from experimental studies clearly indicate that smoking is a relevant risk factor, conferring a substantial increase in risk for renal function deterioration. This review summarizes the present knowledge about the renal risks of smoking as well as the increased cardiovascular risk caused by smoking in patients with chronic kidney disease. The conclusion is that smoking is an important renal risk factor, and nephrologists have to invest more efforts to motivate patients to stop smoking.

Serum transforming growth factor-beta1 levels and pancreatic cancer risk: a nested case-control study (Japan)

OBJECTIVE

To examine the relationship of baseline levels of serum TGF-beta1 to the subsequent risk of death from pancreatic cancer in a nested case-control study.

METHODS

The cases were 85 persons who had provided a blood sample at baseline and subsequently died of pancreatic cancer during the study period. For each case, three controls were randomly selected from among the cohort participants, and were matched for each case by sex, age (+/-1 year), and study area. Serum TGF-beta1 levels were measured with enzyme-linked immunosorbent assay (ELISA). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from conditional logistic models.

RESULTS

The mean of serum TGF-beta1 levels was significantly higher among cases than among controls (p = 0.01). Individuals with serum TGF-beta1 levels in the highest quartile had a 2.5-fold increase in risk as compared with those in the lowest quartile (OR, 2.5; 95% CI, 0.9-6.9), after adjustment for month of blood draw, cigarette smoking, body mass index and history of diabetes. Excluding 12 pancreatic cancer deaths that occurred within three years of follow-up did not alter the positive association.

CONCLUSION

Our prospective data indicate that high serum TGF-beta1 levels may be associated with an increased risk of death from pancreatic cancer.

Nicotine inhibits myofibroblast differentiation in human gingival fibroblasts

Cigarette smoking has been suggested as a risk factor for several periodontal diseases. It has also been found that smokers respond less favorably than non-smokers to periodontal therapy. Previous work in our lab has shown that nicotine inhibits human gingival cell migration. Since myofibroblasts play an important role in wound closure, we asked if nicotine affects gingival wound healing process by regulating myofibroblast differentiation. Human gingival fibroblasts (HGFs) from two patients were cultured in 10% fetal bovine serum cell culture medium. Cells were pretreated with different doses of nicotine (0, 0.01, 0.1, and 1 mM) for 2 h, and then incubated with transforming growth factor beta (TGF-beta1) (0, 0.25, 0.5, and 1 ng/ml) with or without nicotine for 30 h. The expression level of alpha-smooth muscle actin (alpha-SMA), a specific marker for myofibroblasts, was analyzed by Western blots, immunocytochemistry, and real-time polymerase chain reaction (real-time PCR). Phosphorylated p38 mitogen-activated protein kinase (Phospho-p38 MAPK) activity was analyzed by Western blots. TGF-beta1 induced an increase of alpha-SMA protein and mRNA expression, while nicotine (1 mM) inhibited the TGF-beta1-induced expression of alpha-SMA but not beta-actin. Nicotine treatment down-regulated TGF-beta1-induced p38 MAPK phosphorylation. Our results demonstrated for the first time that nicotine inhibits myofibroblast differentiation in human gingival fibroblasts in vitro; supporting the hypothesis that delayed wound healing in smokers may be due to decreased wound contraction by myofibroblasts.

Nicotine does not affect vascularization but inhibits growth of freely transplanted ovarian follicles by inducing granulosa cell apoptosis

BACKGROUND

There is clear support for an association between smoking and decreased female fecundity and fertility. Cigarette smoke appears to have adverse effects along a continuum of reproductive processes. We therefore studied the effect of nicotine on follicular growth and vascularization of freely transplanted ovarian follicles.

METHODS

We used the skinfold chamber model in Syrian golden hamsters, which allows the in vivo microscopy of follicular grafts. Animals were treated daily with nicotine at doses mimicking low-rate and high-rate smokers (0.2 and 1.0 mg/kg body weight subcutaneously). Saline-treated animals served as controls. To further evaluate the effect of nicotine on angiogenesis, an in vitro aortic ring assay was used.

RESULTS

The re-vascularisation rate of follicles was similar in nicotine-treated animals and controls. During the 7 days after transplantation, nicotine further caused a dose-dependent inhibition of follicular growth. In contrast, the vascularized area and microvessel density were not affected by the nicotine exposure. In vitro aortic ring assays confirmed that nicotine does not influence sprouting and microvessel formation. However, immunohistochemistry for cleaved caspase-3 revealed a large extent of granulosa cell apoptosis within transplanted follicles of high-dose nicotine-treated animals.

CONCLUSIONS

Nicotine as one toxic component of cigarette smoke does not affect vascularization, but adversely influences follicular growth by an increase in apoptotic cell death. As follicular growth is a crucial step in normal ovulation and fertilization, nicotine-induced cell apoptosis may represent one of the mechanisms underlying the well-established link between smoking and fertility disorders.

Regulation of angiotensin-converting enzyme production by nicotine in human endothelial cells

Nicotine, a component of cigarette smoke, has been implicated in the pathogenesis of cardiovascular disease. We examined whether nicotine regulates angiotensin-converting enzyme (ACE), an enzyme that plays an important role in the pathophysiology of atherosclerosis and hypertension. Human umbilical cord vein endothelial cells were treated with nicotine (0.1-1 microM) alone or in combination with vascular endothelial growth factor (VEGF; 0.5 nM) or GF-109203X (GFX; 2.5 microM). The amount of ACE in intact endothelial cells was measured by an inhibitor-binding assay method, and ACE mRNA levels were quantified using LightCycler technology. Phosphorylated PKC levels were measured by Western immunoblotting. Nicotine did not modulate basal ACE production but significantly potentiated VEGF-induced ACE upregulation. Treatment of endothelial cells with the PKC inhibitor GFX totally blocked VEGF- and nicotine-induced ACE upregulation. VEGF induced PKC phosphorylation, which was potentiated by cotreatment with nicotine. We conclude that nicotine significantly potentiated VEGF-induced ACE upregulation. This effect was probably mediated by PKC phosphorylation. The interaction of nicotine with VEGF in ACE induction may contribute to the pathogenesis of smoking-related cardiovascular disease.

Chronic nicotine in hearts with healed ventricular myocardial infarction promotes atrial flutter that resembles typical human atrial flutter

The potential of chronic nicotine exposure for atrial fibrillation (AF) and atrial flutter (AFL) in hearts with and without chronic myocardial infarction (MI) remains poorly explored. MI was created in dogs by permanent occlusion of the left anterior descending coronary artery, and dogs were administered nicotine (5 mg·kg−1·day−1 sc) for 1 mo using osmotic minipumps. High-resolution epicardial (1,792 bipolar electrodes) and endocardial Halo catheters were used to map activation during induced atrial rhythms. Nicotine promoted inducible sustained AFL at a mean cycle length of 134 ± 10 ms in all MI dogs ( n = 6) requiring pacing and electrical shocks for termination. No AFL could be induced in MI dogs ( n = 6), control (non-MI) dogs ( n = 3) not exposed to nicotine, and dogs with no MI and exposed to nicotine ( n = 3). Activation maps during AFL showed a single reentrant wavefront in the right atrium that rotated either clockwise (60%) or counterclockwise (40%) around the crista terminalis and through the isthmus. Ablation of the isthmus prevented the induction of AFL. Nicotine caused a significant ( P < 0.01) but highly heterogeneous increase in atrial interstitial fibrosis (2- to 10-fold increase in left and right atria, respectively) in the MI group but only a 2-fold increase in the right atrium in the non-MI group. Nicotine also flattened ( P < 0.05) the slope of the epicardial monophasic action potential duration (electrical restitution) curve of both atria in the MI but not in non-MI dogs. Two-dimensional simulation in an excitable matrix containing an isthmus and nicotine's restitutional and reduced gap junctional coupling (fibrosis) parameters replicated the experiments. Chronic nicotine in hearts with MI promotes AFL that closely resembles typical human AFL. Increased atrial interstitial fibrosis and flattened electrical restitution are important substrates for the AFL.

Metalloproteinases and their inhibitors are markers of plaque instability

BACKGROUND

Our aim was to investigate the release, activity, and expression of matrix metalloproteinases (MMPs)-1, -2, -3 and -9, and tissue inhibitors of metalloproteinases (TIMPs)-1 and -2 in patients undergoing carotid endarterectomy and to determine whether altered plasma levels of MMPs and TIMPs may be correlated with carotid instability.

METHODS

The carotid plaques of 53 consecutive patients who underwent carotid endarterectomy were classified histologically as stable or unstable. The release of MMPs and TIMPs was analyzed in the serum of patients with stable and unstable carotid plaques, and in 15 age-matched healthy volunteers. The production, activity, and expression of MMPs and TIMPs were determined by Western blotting, zymography, and reverse transcriptase polymerase chain reaction in the carotid specimens.

RESULTS

Twenty-nine (55%) patients had an unstable carotid plaque and 24 (45%) a stable plaque. Plasma levels of MMPs were higher in patients with unstable plaques compared to patients with stable plaques and healthy volunteers ( P < .001), whereas plasma levels of TIMPs were lower in patients with unstable plaques compared to patients with stable plaques and healthy volunteers ( P < .001). In the carotid specimens, we found increased activity, production, and expression of MMPs, and decreased activity, production and expression of TIMPs in unstable plaques compared to stable plaques ( P < .001). After endarterectomy, plasma levels of MMPs and TIMPs in patients with unstable and stable plaques returned to the values found in healthy volunteers.

CONCLUSIONS

Our study demonstrated that an imbalance exists between MMPs and TIMPs in unstable carotid plaques, which is reflected in the plasma levels of these markers. These data may help in selecting patients at high risk for cerebral events.

Nicotinic acetylcholine receptor-mediated stimulation of endothelial cells results in the arrest of haematopoietic progenitor cells on endothelium

The function of endothelial cells that contribute to the regulation of haematopoietic stem/progenitor cells (HSPC) migration from peripheral blood into bone marrow can be influenced by extrinsic factors including nicotine. Therefore, the effect of nicotine on HSPC extravasation was studied. Using a parallel laminar flow chamber, we demonstrated an increase in the number of HSPC adhering to the nicotine-exposed endothelium under conditions of physiological shear stress in vitro. Nicotine-induced adhesion of HSPC was inhibited by mecamylamine, a non-selective nicotinic acetylcholine receptor (nAchR) antagonist. The enhanced adhesive interactions of HSPC with nicotine-exposed endothelial monolayers coincided with the nicotine-induced activation of endothelial cells. Nicotine induced fast cytoskeletal reorganization and formation of filopodia in endothelial cells through interaction with the non-neuronal nAchR expressed by these cells. In addition, nicotine treatment stimulated rapid phosphorylation of Erk1/2 and p-38 in endothelial cells. Finally, nicotine inhibited the stroma derived factor-1-mediated transendothelial migration of HSPC. Decreased migration of HSPC correlated with diminished matrix metalloproteinase-9 activity secreted by bone marrow cells and decreased expression of CD44 on the surface of endothelial cells. Overall, our data suggest that exposure to nicotine causes endothelial cell dysfunction and leads to the pathological arrest of HSPC on endothelium, interfering with their proper migration process.

Augmented transforming growth factor-beta1 in gingival crevicular fluid of smokers with chronic periodontitis

BACKGROUND

Patients who smoke are at increased risk for chronic periodontitis (CP). Also, CP patients who smoke exhibit significantly less reduction of probing depths and gains in clinical attachment compared to non-smokers following periodontal therapy. Several studies suggest that the effects of smoking on the host response may be paramount in regulating the basal systemic inflammatory status and therapeutic outcomes in this cohort. Growth factors, specifically transforming growth factor beta1 (TGF-beta1), are critical in regulating the wound healing response by controlling cell division, differentiation, and motility. The hypothesis to be tested was that gingival crevicular fluid (GCF) TGF-beta1 production was altered in smokers compared to non-smokers with CP.

METHODS

GCF was collected from smokers and non-smokers with CP, both at baseline and 1 to 2 weeks after initial therapy. GCF volume was determined using an electronic device and TGF-beta1 concentration was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Smokers exhibited a higher mean concentration of GCF TGF-beta1 at baseline compared to non-smokers (P = 0.03). After initial therapy, smokers exhibited significantly less reduction in mean GCF volume compared to non-smokers (P = 0.04).

CONCLUSIONS

Augmented constitutive production of GCF TGF-beta1 in smokers may explain the clinical appearance of fibrotic gingival tissue exhibited by this patient cohort. A diminished reduction in GCF volume in smokers following root instrumentation suggests a chronic inflammatory status in conjunction with an ineffective host response. These findings support the concept that smokers with CP display an altered local inflammatory response after initial therapy, perhaps symptomatic of colonization by residual periodontal pathogens.

Down-regulating effect of nicotine on connexin43 gap junctions in human umbilical vein endothelial cells is attenuated by statins

We investigated the effect of nicotine on connexin43 (Cx43) expression and gap-junctional communication in human umbilical vein endothelial cells (HUVEC). We also evaluated whether the effect requires activation of acetyl choline receptors sensitive to nicotine (nAChRs) and is altered by statins. The results showed that expression of Cx43 protein is reduced by nicotine in a dose-dependent manner (6 x 10(-4) M nicotine vs control, 33% reduction, p < 0.01), though Cx43 mRNA is up-regulated (6 x 10(-4) M nicotine vs control, 36% increase, p < 0.01). Concomitantly, the communication function, determined by fluorescence recovery after photobleaching, is decreased (6 x 10(-4) M nicotine vs control, 38% reduction, p < 0.05). Such a down-regulation of Cx43 gap junctions by nicotine disappears in the presence of the nAChRs antagonist, dihydro-beta-erythroidine, and protease inhibitors leupeptin plus N-acetyl-Leu-Leu-Norleu-al (ALLN). Similarly, the effect of nicotine is attenuated by statins, including fluvastatin, lovastatin, pravastatin, and simvastatin, even at the presence of mevalonate. We concluded that i) nicotine down-regulates Cx43 expression and gap-junctional communication in HUVEC via post-transcriptional modification, which involves enhancement of Cx43 proteolysis; ii) the effect of nicotine is mediated via activation of nAChRs; and iii) the effect of nicotine is attenuated by statins through mechanisms outside the hypolipidemic pathway.

Aspects of human fetoplacental vasculogenesis and angiogenesis. III. Changes in complicated pregnancies

Patterns of fetoplacental angiogenesis vary not only during the course of a normal pregnancy but also in certain pregnancy pathologies. Here, we review some of the molecular and morphological events which occur in complicated pregnancies. The pregnancy complications are chosen in an attempt to represent the possible different origins (preplacental, uteroplacental, postplacental) of fetal hypoxia. Molecular events focus on reported changes in hypoxia-inducible factors, angiopoietins and the vascular endothelial, basic fibroblast and placenta growth factors and their receptors. Morphological changes focus on patterns of angiogenesis (branching and non-branching) and a consistent set of morphometric descriptors (covering measures of total capillary growth, villous capillarization and capillary size and shape in transverse section). Apart from some uncertainties due to lack of information, or failure to resolve fully the effects of intrauterine growth restriction and pre-eclampsia, alterations in the angiogenic growth factors and morphologies of capillaries and villi in different complicated pregnancies seem to conform reasonably well to those predicted by the fetal hypoxia paradigm. However, it is clear that future studies on the effects of different origins of fetal hypoxia should exercise more care in the choice and interpretation of relevant descriptors and take more account of the parallel effects of possible confounders. In addition, rather than comparing uncomplicated and complicated pregnancies only at term, more information about molecular and morphological events that occur throughout gestation would be extremely valuable. This includes further studies on changes in growth factor receptors, the less-well-documented angiogenic factors (e.g. angiogenin, angiostatin, endostatin) and the associations between endothelial cells and pericytes. A more integrated approach involving also parallel analysis of the effects of erythropoietin and other potential vasoactive factors on the behaviour and morphology of fetal vessels would be beneficial.

Nicotine inhibits palatal fusion and modulates nicotinic receptors and the PI-3 kinase pathway in medial edge epithelia

OBJECTIVES

To analyze the effects of nicotine on palatal fusion inhibition in vitro and determine if nicotine modulated transforming growth factor beta3 or phosphatidylinositol-3 kinase signaling. A second objective was to determine the localization and regulation of nicotinic receptors in the medial edge epithelia (MEE) during palatal fusion.

DESIGN

Palatal shelves from embryonic day (E) 13.5 mice were cultured in serum free media and treated with 0, 0.06, 0.6, or 6 mM nicotine, nicotinic receptor antagonist alpha-bungarotoxin, or the combination of nicotine and alpha-bungarotoxin. Tissues harvested at 72 h were analyzed for epithelial-mesenchymal transformation (EMT) and fusion. MEE samples collected at 20 h were analyzed for phosphorylated Akt-Ser473, phosphorylated Smad2, and nicotinic receptors.

RESULTS

Nicotine inhibited palatal fusion in vitro in a dose dependent manner. Activated Akt-Ser473 was greater in control MEE than in nicotine treated tissues; while there was no difference in activated Smad2 between groups. The alpha7 subunit of nicotinic receptor was expressed in MEE during palate fusion and increased in nicotine treated tissues. Alpha-bungarotoxin did not rescue the nicotine treated palates.

CONCLUSION

Nicotine treatment had no effect on Smad2, but caused a down regulation of the PI-3 kinase pathway that may have contributed to inhibiting palatal fusion in vitro.

Circulating transforming growth factor-beta1, lipoprotein(a) and cellular adhesion molecules in angiographically assessed coronary artery disease

Transforming growth factor-beta1 (TGF-beta1) is involved in different physiological and pathological processes, including atherogenesis. High plasma lipoprotein(a) (Lp(a)) concentration is an established independent risk factor that may interfere with the plasmin-mediated TGF-beta1 activation. Both Lp(a) and TGF-beta1 are thought to influence the expression of cellular adhesion molecules (CAMs), also involved in the process of atherogenesis. Whereas many studies confirmed the association between high plasma Lp(a) levels and coronary artery disease (CAD), conflicting results were obtained in different studies in which the changes of TGF-beta1 and CAM concentrations in CAD patients were investigated. The aim of this case-control study was to explore the association of circulating TGF-beta1, Lp(a) and CAMs (intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin) levels with the occurrence and severity of angiographically assessed coronary artery disease. Plasma TGF-beta1, Lp(a), ICAM-1, VCAM-1 and E-selectin concentrations were measured in 100 patients with angiographically assessed CAD and 100 healthy blood donors matched according to age and gender. Lp(a) and TGF-beta1 were significantly higher in patients than in healthy controls (p < 0.001 and p < 0.01, respectively), but no significant correlation between the TGF-beta1 and Lp(a) values was found. The CAM concentrations obtained in CAD patients did not differ significantly as compared with the corresponding values in the controls. None of the measured parameters were influenced by the severity of CAD.

Vascular endothelial growth factor increases the migration and proliferation of smooth muscle cells through the mediation of growth factors released by endothelial cells

BACKGROUND

Vascular endothelial growth factor (VEGF), a highly specific chemotactic and mitogenic factor for vascular endothelial cells (EC), appears to be involved in the development of atherosclerosis. The purpose of our study was to assess if VEGF might indirectly stimulate SMC migration and proliferation in a EC-SMC coculture system, through the mediation of growth factors released by EC.

METHODS

Bovine aortic SMC were cocultured with bovine aortic EC treated with hrVEGF, to assess SMC proliferation and migration. The release and mRNA expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta(1) (TGFbeta(1)) were assessed by ELISA and PCR analysis.

RESULTS

hrVEGF (10 ng/ml), added to EC cocultured with SMC, induced a significant increase in tritiated thymidine uptake by SMC as compared to controls (P < 0.01) and a significant increase in SMC migration in respect to control (27%; P < 0.01). EC stimulated with hrVEGF increased the release and the expression of bFGF and decreased the release and the expression of TGFbeta(1) with a statistically significant difference in respect to controls (P < 0.001).

CONCLUSIONS

VEGF indirectly stimulates SMC proliferation and migration through the modulation of bFGF and TGFbeta(1) released by EC.

Nicotinic receptors in aging and dementia

Activation of neuronal nicotinic acetylcholine receptors (nAChRs) has been shown to maintain cognitive function following aging or the development of dementia. Nicotine and nicotinic agonists have been shown to improve cognitive function in aged or impaired subjects. Smoking has also been shown in some epidemiological studies to be protective against the development of neurodegenerative diseases. This is supported by animal studies that have shown nicotine to be neuroprotective both in vivo and in vitro. Treatment with nicotinic agonists may therefore be useful in both slowing the progression of neurodegenerative illnesses, and improving function in patients with the disease. While increased nicotinic function has been shown to be beneficial, loss of cholinergic markers is often seen in patients with dementia, suggesting that decreased cholinergic function could contribute to both the cognitive deficits, and perhaps the neuronal degeneration, associated with dementia. In this article we will review the literature on each of these areas. We will also present hypotheses that might address the mechanisms underlying the ability of nAChR function to protect against neurodegeneration or improve cognition, two potentially distinct actions of nicotine.