In utero nicotine exposure promotes M2 activation in neonatal mouse alveolar macrophages

Nicotinic regulation of microglia: potential contributions to addiction

Clinical and preclinical studies have identified immunosuppressive effects of nicotine, with potential implications for treating nicotine addiction. Here we review how nicotine can regulate microglia, the resident macrophages in the brain, and corresponding effects of nicotine on neuroimmune signaling. There is significant evidence that activation of α7 nicotinic acetylcholine receptors (nAChRs) on microglia can trigger an anti-inflammatory cascade that alters microglial polarization and activity, cytokine release, and intracellular calcium concentrations, leading to neuroprotection. These anti-inflammatory effects of nicotine-dependent α7 nAChR signaling are lost during withdrawal, suggesting that neuroimmune signaling is potentiated during abstinence, and thus, heightened microglial activity may drive circuit disruption that contributes to withdrawal symptoms and hyperkatifeia. In sum, the clinical literature has highlighted immunomodulatory effects of nicotine and the potential for anti-inflammatory compounds to treat addiction. The preclinical literature investigating the underlying mechanisms points to a role of microglial engagement in the circuit dysregulation and behavioral changes that occur during nicotine addiction and withdrawal, driven, at least in part, by activation of α7 nAChRs on microglia. Specifically targeting microglial signaling may help alleviate withdrawal symptoms in people with nicotine dependence and help to promote abstinence.

Cucurbitacin E ameliorates airway remodelling by inhibiting nerve growth factor expression in nicotine-treated bronchial epithelial cells and mice: The key role of let-7c-5p up-regulated expression

Cucurbitacin E (CuE) shows potential to handle airway remodelling. In the current study, the effects of CuE on nicotine-induced airway remodelling were explored by focussing on its interaction with let-7c-5p/NGF axis. The potential microRNA (miR) as the therapeutic target for CuE treatment was determined using a microarray assay. Changes in viability, inflammation and let-7c-5p/NGF pathway in nicotine-treated bronchial epithelial cells (BECs) were detected under CuE treatment (5 μM). The pathways were manipulated with let-7c-5p inhibitor. Mice were subjected to nicotine treatment and handled with CuE. Changes in pulmonary function and structure were detected. Based on the microarray data, let-7c-5p was selected as the therapeutic target. Viability and inflammation of BECs were induced by nicotine and then restored by CuE. At molecular level, nicotine suppressed let-7c-5p while induced NGF, FN1 and COLIA levels. The effects of CuE were counteracted by let-7c-5p inhibition. In a mouse model, nicotine impaired the function and structure of lung, which was attenuated by CuE and then re-impaired by let-7c-5p antagomir. Collectively, CuE protected against nicotine-induced airway remodelling and partially depended on the induction of let-7c-5p; our future work would pay more attention to other downstream effectors of the miR to promote the treatment of nicotine-induced pulmonary disorders.

Developmental programming of macrophages by early life adversity

Macrophages are central elements of all organs, where they have a multitude of physiological and pathological functions. The first macrophages are produced during fetal development, and most adult organs retain populations of fetal-derived macrophages that self-maintain without major input of hematopoietic stem cell-derived monocytes. Their developmental origins make macrophages highly susceptible to environmental perturbations experienced in early life, in particular the fetal period. It is now well recognized that such adverse developmental conditions contribute to a wide range of diseases later in life. This chapter explores the notion that macrophages are key targets of environmental adversities during development, and mediators of their long-term impact on health and disease. We first briefly summarize our current understanding of macrophage ontogeny and their biology in tissues and consider potential mechanisms by which environmental stressors may mediate fetal programming. We then review evidence for programming of macrophages by adversities ranging from maternal immune activation and diet to environmental pollutants and toxins, which have disease relevance for different organ systems. Throughout this chapter, we contemplate appropriate experimental strategies to study macrophage programming. We conclude by discussing how our current knowledge of macrophage programming could be conceptualized, and finally highlight open questions in the field and approaches to address them.

Nicotine replacement therapy and e-cigarettes in pregnancy and infant respiratory outcomes

BACKGROUND

Nicotine replacement therapy (NRT) and e-cigarettes are recommended to pregnant women who wish to stop smoking. Albeit eliminating other harmful components of cigarettes, those alternatives still expose the developing fetus to nicotine. The lungs may be particularly vulnerable to damage by nicotine as there is widespread nicotinic-acetylcholine receptor expression in the lungs. There is, however, a paucity of information about the effect of NRT and e-cigarette use in pregnancy on infant respiratory outcomes.

AIMS

To explore the effect of NRT and e-cigarettes on the developing lung.

STUDY DESIGN

A literature search was undertaken to examine the use and safety of nicotine-replacement strategies in pregnancy, with a focus on infant respiratory outcomes. This included experimental studies investigating the effect of isolated "gestational" nicotine on the developing lung.

OUTCOME MEASURES

Respiratory outcomes in animal studies and infants.

RESULTS

Animal studies investigating the effect of gestational nicotine exposure on fetal lung development demonstrated abnormal lung growth; including abnormal airway branching and alveolar development. Consequently, offspring display altered pulmonary mechanics, including both increased respiratory rate and airway resistance. These findings mirror respiratory pathology observed in infants born to smoking mothers. Human trials of NRT and e-cigarette use in pregnancy have not identified adverse perinatal outcomes regarding reduced birthweight or prematurity, but have not considered infant and childhood respiratory outcomes.

CONCLUSIONS

Nicotine can impair fetal lung development, leading to concerns regarding the safety of NRT and e-cigarettes in pregnancy. Studies have yet to explore the impact of these nicotine-containing products on infant respiratory outcomes.

Uptake of nicotinic acetylcholine receptor imaging agent is reduced in the pro-inflammatory macrophage

INTRODUCTION

Macrophages play a vital role in the development of atherosclerotic cardiovascular disease. Macrophages are functionally and phenotypically heterogeneous immune cells and commonly exist in two distinct or polarized subsets: pro-inflammatory M1 and anti-inflammatory M2 phenotypes. Previous reports suggest that stimulation of α7 or α4β2 nicotinic acetylcholine receptors (nAChRs) in macrophages leads to an anti-inflammatory response. However, the biological link between nAChR expression on macrophages and the polarization state is unknown. Therefore, we evaluated the relationship between nAChRs and polarized macrophages in peritoneal macrophages and atherosclerotic plaques of apolipoprotein E knockout (ApoE-/-) mice.

METHODS

Peritoneal macrophages isolated from mice were polarized into M1 and M2 macrophages, and the uptake of the nAChR-imaging agents, (R)-2-[11C]methylamino-benzoic acid 1-aza-bicyclo[2.2.2]oct-3-yl ester ([11C]MeQAA) or 2-[18F]fluoro-3-(2(S)-azetidinylmethoxy) pyridine ([18F]2FA), and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) was assessed. We also evaluated the accumulation of imaging agents in atherosclerotic plaques of ApoE-/- mice by autoradiography. After an autoradiogram was obtained, the same aortic tissue was used for immunohistochemical staining of CD68, inducible nitric oxide synthase (iNOS), and arginine-1.

RESULTS

In an in vitro assay, the uptake of [11C]MeQAA or [18F]2FA was lower in M1 than in M0 and M2 macrophages. In comparison, the uptake of [18F]FDG was higher in M1 macrophages. Ex vivo autoradiography showed that [11C]MeQAA was localized to the extensive plaque area. By contrast, the accumulation of [18F]2FA and [18F]FDG was heterogeneous and found only in some plaques. Moreover, the expression of CD68 and iNOS was higher in [18F]2FA non-uptake than [18F]2FA uptake plaques.

CONCLUSION

Macrophage polarization was related to nAChR expression, and α4β2 nAChR expression was suppressed in the M1 macrophage. These findings suggest that nAChR imaging has the potential to identify the inflammatory status of atherosclerotic plaque.

Novel Pathways and Mechanism of Nicotine-Induced Oral Carcinogenesis

BACKGROUND

Smokeless Tobacco (SLT) contains 9 times more nicotine than Smoked Tobacco (SMT). The carcinogenic effect of nicotine is intensified by converting nicotine-to-nicotine-derived Nitrosamines (NDNs).

METHODS

A review of the literature was conducted with a tailored search strategy to unravel the novel pathways and mechanisms of nicotine-induced oral carcinogenesis.

RESULTS

Nicotine and NDNs act on nicotinic Acetylcholine Receptors (nAChRs) as agonists. Nicotine facilitates cravings through α4β2nAChR and α7nAChR, via enhanced brain dopamine release. Nicotine binding to nAChR promotes proliferation, migration, invasion, chemoresistance, radioresistance, and metastasis of oral cancer cells. Nicotine binding to α7nAChR on keratinocytes triggers Ras/Raf-1/MEK1/ERK cascade promoting anti-apoptosis and pro-proliferative effects. Furthermore, the nicotine-enhanced metastasis is subdued on nAChR blockade through reduced nuclear localization of p-EGFR.

CONCLUSION

Protracted exposure to nicotine/NDN augments cancer-stimulatory α7nAChR and desensitizes cancer inhibitory α4β2nAChR. Since nAChRs dictate both addictive and carcinogenic effects of nicotine, it seems counterintuitive to designate nicotine just as an addictive agent devoid of any carcinogenicity.

Factors and mechanisms contributing to the development of preschool wheezing disorders

INTRODUCTION

Half of all children will experience an episode of wheezing by their sixth birthday and acute episodes of wheezing in preschool children account for the majority of all childhood hospital admissions for wheeze. Recurrent preschool wheezing associates with early loss of lung function and a life-long impact on lung health.

AREAS COVERED

We reviewed the literature on PubMed from August 2010-2020 focussing on factors associated with wheeze inception and persistence, paying specific attention to mechanistic studies that have investigated the impact of early life exposures in shaping immune responses in children with underlying susceptibility to wheezing. In particular, the role of early allergen sensitization, respiratory infections, and the impact of the environment on shaping the airway microbiome and resulting immune responses are discussed.

EXPERT OPINION

There is an abundance of associative data showing the role of in utero and postnatal factors influencing wheeze onset and persistence. However, mechanistic and stratified, biomarker-based interventional studies that confirm these associations are now needed if we are to impact the significant healthcare burden resulting from preschool wheezing disorders.

MicroRNA-98 reduces nerve growth factor expression in nicotine-induced airway remodeling

Evolving evidence suggests that nicotine may contribute to impaired asthma control by stimulating expression of nerve growth factor (NGF), a neurotrophin associated with airway remodeling and airway hyperresponsiveness. We explored the hypothesis that nicotine increases NGF by reducing lung fibroblast (LF) microRNA-98 (miR-98) and PPARγ levels, thus promoting airway remodeling. Levels of NGF, miR-98, PPARγ, fibronectin 1 (FN1), endothelin-1 (EDN1, herein referred to as ET-1), and collagen (COL1A1 and COL3A1) were measured in human LFs isolated from smoking donors, in mouse primary LFs exposed to nicotine (50 μg/ml), and in whole lung homogenates from mice chronically exposed to nicotine (100 μg/ml) in the drinking water. In selected studies, these pathways were manipulated in LFs with miR-98 inhibitor (anti-miR-98), miR-98 overexpression (miR-98 mimic), or the PPARγ agonist rosiglitazone. Compared with unexposed controls, nicotine increased NGF, FN1, ET-1, COL1A1, and COL3A1 expression in human and mouse LFs and mouse lung homogenates. In contrast, nicotine reduced miR-98 levels in LFs in vitro and in lung homogenates in vivo Treatment with anti-miR-98 alone was sufficient to recapitulate increases in NGF, FN1, and ET-1, whereas treatment with a miR-98 mimic significantly suppressed luciferase expression in cells transfected with a luciferase reporter linked to the putative seed sequence in the NGF 3'UTR and also abrogated nicotine-induced increases in NGF, FN1, and ET-1 in LFs. Similarly, rosiglitazone increased miR-98 and reversed nicotine-induced increases in NGF, FN1, and ET-1. Taken together, these findings demonstrate that nicotine-induced increases in NGF and other markers of airway remodeling are negatively regulated by miR-98.

Human-specific gene CHRFAM7A mediates M2 macrophage polarization via the Notch pathway to ameliorate hypertrophic scar formation

Hypertrophic scars often cause great pain to patients. It is generally believed that anti-inflammatory scar therapies are the best strategies for treatment because excessive inflammation is observed in hypertrophic scar tissue. However, the results of such treatment are unsatisfactory. In recent studies, immune stimulatory therapies have been suggested to be a preferable method for ameliorating hypertrophic scars. In this study, the expression of the human-specific gene CHRFAM7A, which has been reported to be a promoter of inflammation, was found to be lower in human hypertrophic scars than in normotrophic scars. The CHRFAM7A gene was overexpressed in a hypertrophic scar mouse model using a lentivirus system. Scar fibrosis decreased in the CHRFAM7A transfection group compared to the control group, and the proportion of M2 macrophages decreased at 4 and 8 weeks after establishing the model. We also found that CHRFAM7A increased the activation of the Notch pathway, which eventually attenuated M2 polarization. In the CHRFAM7A-transfected hypertrophic scar mouse group, the number of M1 macrophages increased dramatically in the initial period. Moreover, the expression of the inflammatory gene TNFα was also increased in transfected mice. Our results demonstrate that CHRFAM7A can effectively ameliorate hypertrophic scar formation via regulation of macrophage phenotypic transition. CHRFAM7A might be a therapeutic target for hypertrophic scars.

New therapeutic targets for the prevention of infectious acute exacerbations of COPD: role of epithelial adhesion molecules and inflammatory pathways

Chronic respiratory diseases are among the leading causes of mortality worldwide, with the major contributor, chronic obstructive pulmonary disease (COPD) accounting for approximately 3 million deaths annually. Frequent acute exacerbations (AEs) of COPD (AECOPD) drive clinical and functional decline in COPD and are associated with accelerated loss of lung function, increased mortality, decreased health-related quality of life and significant economic costs. Infections with a small subgroup of pathogens precipitate the majority of AEs and consequently constitute a significant comorbidity in COPD. However, current pharmacological interventions are ineffective in preventing infectious exacerbations and their treatment is compromised by the rapid development of antibiotic resistance. Thus, alternative preventative therapies need to be considered. Pathogen adherence to the pulmonary epithelium through host receptors is the prerequisite step for invasion and subsequent infection of surrounding structures. Thus, disruption of bacterial-host cell interactions with receptor antagonists or modulation of the ensuing inflammatory profile present attractive avenues for therapeutic development. This review explores key mediators of pathogen-host interactions that may offer new therapeutic targets with the potential to prevent viral/bacterial-mediated AECOPD. There are several conceptual and methodological hurdles hampering the development of new therapies that require further research and resolution.

Nicotine Impairs Macrophage Control of Mycobacterium tuberculosis

Pure nicotine impairs macrophage killing of Mycobacterium tuberculosis (MTB), but it is not known whether the nicotine component in cigarette smoke (CS) plays a role. Moreover, the mechanisms by which nicotine impairs macrophage immunity against MTB have not been explored. To neutralize the effects of nicotine in CS extract, we used a competitive inhibitor to the nicotinic acetylcholine receptor (nAChR)-mecamylamine-as well as macrophages derived from mice with genetic disruption of specific subunits of nAChR. We also determined whether nicotine impaired macrophage autophagy and whether nicotine-exposed T regulatory cells (Tregs) could subvert macrophage anti-MTB immunity. Mecamylamine reduced the CS extract increase in MTB burden by 43%. CS extract increase in MTB was also significantly attenuated in macrophages from mice with genetic disruption of either the α7, β2, or β4 subunit of nAChR. Nicotine inhibited autophagosome formation in MTB-infected THP-1 cells and primary murine alveolar macrophages, as well as increased the intracellular MTB burden. Nicotine increased migration of THP-1 cells, consistent with the increased number of macrophages found in the lungs of smokers. Nicotine induced Tregs to produce transforming growth factor-β. Naive mouse macrophages co-cultured with nicotine-exposed Tregs had significantly greater numbers of viable MTB recovered with increased IL-10 production and urea production, but no difference in secreted nitric oxide as compared with macrophages cocultured with unexposed Tregs. We conclude that nicotine in CS plays an important role in subverting macrophage control of MTB infection.

Electronic cigarettes: what are they and what do they do?

Electronic cigarettes (ECIGs) use electricity to power a heating element that aerosolizes a liquid containing solvents, flavorants, and the dependence-producing drug nicotine for user inhalation. ECIGs have evolved rapidly in the past 8 years, and the changes in product design and liquid constituents affect the resulting toxicant yield in the aerosol and delivery to the user. This rapid evolution has been accompanied by dramatic increases in ECIG use prevalence in many countries among adults and, especially, adolescents in the United States. The increased prevalence of ECIGs that deliver nicotine and other toxicants to users' lungs drives a rapidly growing research effort. This review highlights the most recent information regarding the design of ECIGs and their liquid and aerosol constituents, the epidemiology of ECIG use among adolescents and adults (including correlates of ECIG use), and preclinical and clinical research regarding ECIG effects. The current literature suggests a strong rationale for an empirical regulatory approach toward ECIGs that balances any potential ECIG-mediated decreases in health risks for smokers who use them as substitutes for tobacco cigarettes against any increased risks for nonsmokers who may be attracted to them.

Impaired defenses of neonatal mouse alveolar macrophage with cftr deletion are modulated by glutathione and TGFβ1

Our understanding of the intrinsic effects of cystic fibrosis (CF) transmembrane conductance regulator (cftr) deletion on resident neonatal alveolar macrophage (AM) remains limited. We previously demonstrated that diminished glutathione (GSH) or excessive AM transforming growth factor beta one (TGFβ1) contributes to AM dysfunction in a variety of disease states. In this study, using a gut-corrected cftr neonatal knockout (KO) mouse model and a siRNA-manipulated macrophage-like cell line (THP-1 cell), we hypothesized (1) that cftr mutation alone increases neonatal AM oxidant stress and cellular TGFβ1 signaling via altered GSH, thereby impairing cellular function, and (2) that exogenous GSH attenuates AM alterations and dysfunction in the KO AM In neonatal KO mice, the baseline bronchoalveolar lavage fluid demonstrated a near doubling in mixed disulfides (P ≤ 0.05) and oxidized GSSG (P ≤ 0.05) without concurrent inflammation compared to WT littermates. KO AM demonstrated diminished AM thiols (P ≤ 0.05), increased AM mitochondrial ROS (P ≤ 0.05), increased AM TGFβ1 (P ≤ 0.05) with increased TGFβ1 signaling (P ≤ 0.05), and impaired phagocytosis (P ≤ 0.05). KO AM mitochondrial ROS was modulated by exogenous GSH (P ≤ 0.05). Conversely, TGFβ1 was reduced (P ≤ 0.05) and impaired phagocytosis was rescued (P ≤ 0.05) by exogenous GSH in the KO AM These results suggest that an altered neonatal AM phenotype may contribute to the initiation of lung inflammation/infection in the CF lung. Modulation of the AM in the neonatal CF lung may potentially alter progression of disease.

The Role of Nicotine in the Effects of Maternal Smoking during Pregnancy on Lung Development and Childhood Respiratory Disease. Implications for Dangers of E-Cigarettes

Use of e-cigarettes, especially among the young, is increasing at near-exponential rates. This is coupled with a perception that e-cigarettes are safe and with unlimited advertising geared toward vulnerable populations, the groups most likely to smoke or vape during pregnancy. There is now wide appreciation of the dangers of maternal smoking during pregnancy and the lifelong consequences this has on offspring lung function, including the increased risk of childhood wheezing and subsequent asthma. Recent evidence strongly supports that much of the effect of smoking during pregnancy on offspring lung function is mediated by nicotine, making it highly likely that e-cigarette use during pregnancy will have the same harmful effects on offspring lung function and health as do conventional cigarettes. In fact, the evidence for nicotine being the mediator of harm of conventional cigarettes may be most compelling for its effects on lung development. This raises concerns about both the combined use of e-cigarettes plus conventional cigarettes by smokers during pregnancy as well as the use of e-cigarettes by e-cigarette-only users who think them safe or by those sufficiently addicted to nicotine to not be able to quit e-cigarette usage during pregnancy. Thus, it is important for health professionals to be aware of the risks of e-cigarette usage during pregnancy, particularly as it pertains to offspring respiratory health.

Impact of Tobacco Smoke and Nicotine Exposure on Lung Development

Tobacco smoke and nicotine exposure during prenatal and postnatal life can impair lung development, alter the immune response to viral infections, and increase the prevalence of wheezing during childhood. The following review examines recent discoveries in the fields of lung development and tobacco and nicotine exposure, emphasizing studies published within the last 5 years. In utero tobacco and nicotine exposure remains common, occurring in approximately 10% of pregnancies within the United States. Exposed neonates are at increased risk for diminished lung function, altered central and peripheral respiratory chemoreception, and increased asthma symptoms throughout childhood. Recently, genomic and epigenetic risk factors, such as alterations in DNA methylation, have been identified that may influence the risk for long-term disease. This review examines the impact of prenatal tobacco and nicotine exposure on lung development with a particular focus on nicotinic acetylcholine receptors. In addition, this review examines the role of prenatal and postnatal tobacco smoke and nicotine exposure and its association with augmenting infection risk, skewing the immune response toward a T-helper type 2 bias and increasing risk for developing an allergic phenotype and asthmalike symptoms during childhood. Finally, this review outlines the respiratory morbidities associated with childhood secondhand smoke and nicotine exposure and examines genetic and epigenetic modifiers that may influence respiratory health in infants and children exposed to in utero or postnatal tobacco smoke.

Inter- and transgenerational epigenetic inheritance: evidence in asthma and COPD?

Evidence is now emerging that early life environment can have lifelong effects on metabolic, cardiovascular, and pulmonary function in offspring, a concept also known as fetal or developmental programming. In mammals, developmental programming is thought to occur mainly via epigenetic mechanisms, which include DNA methylation, histone modifications, and expression of non-coding RNAs. The effects of developmental programming can be induced by the intrauterine environment, leading to intergenerational epigenetic effects from one generation to the next. Transgenerational epigenetic inheritance may be considered when developmental programming is transmitted across generations that were not exposed to the initial environment which triggered the change. So far, inter- and transgenerational programming has been mainly described for cardiovascular and metabolic disease risk. In this review, we discuss available evidence that epigenetic inheritance also occurs in respiratory diseases, using asthma and chronic obstructive pulmonary disease (COPD) as examples. While multiple epidemiological as well as animal studies demonstrate effects of 'toxic' intrauterine exposure on various asthma-related phenotypes in the offspring, only few studies link epigenetic marks to the observed phenotypes. As epigenetic marks may distinguish individuals most at risk of later disease at early age, it will enable early intervention strategies to reduce such risks. To achieve this goal further, well designed experimental and human studies are needed.

Exposure to electronic cigarettes impairs pulmonary anti-bacterial and anti-viral defenses in a mouse model

Electronic cigarettes (E-cigs) have experienced sharp increases in popularity over the past five years due to many factors, including aggressive marketing, increased restrictions on conventional cigarettes, and a perception that E-cigs are healthy alternatives to cigarettes. Despite this perception, studies on health effects in humans are extremely limited and in vivo animal models have not been generated. Presently, we determined that E-cig vapor contains 7x10¹¹ free radicals per puff. To determine whether E-cig exposure impacts pulmonary responses in mice, we developed an inhalation chamber for E-cig exposure. Mice that were exposed to E-cig vapor contained serum cotinine concentrations that are comparable to human E-cig users. E-cig exposure for 2 weeks produced a significant increase in oxidative stress and moderate macrophage-mediated inflammation. Since, COPD patients are susceptible to bacterial and viral infections, we tested effects of E-cigs on immune response. Mice that were exposed to E-cig vapor showed significantly impaired pulmonary bacterial clearance, compared to air-exposed mice, following an intranasal infection with Streptococcus pneumonia. This defective bacterial clearance was partially due to reduced phagocytosis by alveolar macrophages from E-cig exposed mice. In response to Influenza A virus infection, E-cig exposed mice displayed increased lung viral titers and enhanced virus-induced illness and mortality. In summary, this study reports a murine model of E-cig exposure and demonstrates that E-cig exposure elicits impaired pulmonary anti-microbial defenses. Hence, E-cig exposure as an alternative to cigarette smoking must be rigorously tested in users for their effects on immune response and susceptibility to bacterial and viral infections.

Is it safe to use smoking cessation therapeutics during pregnancy?

INTRODUCTION

Worldwide, 10 to 35% of pregnant women smoke. It is clear that smoking cessation has positive impacts for both the mother and child, yet many women are still unable to quit due to the addictive properties of nicotine. There are limited data surrounding their safety and efficacy in pregnancy.

AREAS COVERED

This review highlights evidence from clinical studies and animal experiments regarding the effects of smoking cessation therapeutics on pregnancy, neonatal and long-term postnatal outcomes.

EXPERT OPINION

There are insufficient data at this time to recommend the use of varenicline and/or bupropion for smoking cessation during pregnancy. In addition, the efficacy and safety of nicotine replacement therapy use for smoking cessation in pregnant women has not been clearly demonstrated. Until further studies are completed, there will continue to be considerable uncertainty regarding the use of these drugs in pregnancy despite the well-documented benefits of smoking cessation.

Fibronectin regulation by vitamin C treatment in kidneys of nicotinic mice offspring

Background:

Maternal cigarette smoking causes health risks and developmental defects in the offspring. So far, many studies have been conducted to suppress the effects of nicotine. However, the effects of coadministration of vitamin C and nicotine on extracellular matrix have not gained enough attention.

Objectives:

This study decided to investigate the effects of vitamin C on fibronectin expression in kidneys of mice offspring, treated with nicotine.

Materials and Methods:

Eighteen female pregnant BALB/c mice were selected; six mice in the experimental group 1 (exp 1) received nicotine (3 mg/kg/day), six mice in the experimental group 2 (exp 2) received 3 mg/kg/day nicotine and 9 mg/kg/day vitamin C simultaneously, and six were used as the control group and received 3 mL/kg/day normal saline via intraperitoneal (IP) injection parallel to other groups, since the 6th day of gestation to the end of prenatal period. In the first days of delivery, fibronectin content of neonatal kidneys was studied by immunohistochemistry (IHC) assay and gene expression was studied by the real-time PCR.

Results:

IHC results showed that fibronectin reaction significantly increased in proximal convoluted tubules of exp 1 compared with the control offspring; on the other hand, fibronectin reaction decreased in the mice offspring of exp 2. Gene expression results showed that fibronectin expression in the exp 1 offspring significantly increased compared with the control ones and fibronectin expression decreased in the mice offspring of exp 2.

Conclusions:

This study revealed that vitamin C could reduce the fibronectin accumulation effects of nicotine on kidney.

Lung remodeling mechanisms in chronic lung diseases

PURPOSE OF REVIEW

To summarize the new knowledge on tissue remodeling in the context of lung diseases. Tissue remodeling includes changes in cells: differentiation; response to growths factors, hormones, or environmental factors; and composition of the extracellular matrix. So, can one trigger cause them all or are they independently regulated?

RECENT FINDINGS

New evidence from clinical and experimental studies strengthened the view that a susceptibility to remodeling can be initiated in early life and be re-activated by environmental triggers later in life. Many studies further support the idea that TGF-β plays the central role in the pathogenesis of remodeling and fibrosis. However, the activation pathways and the end-effect of TGF-β activation seems to be distinctive of disease and effecter cell specific patterns. The existing animal models do not properly reflect the human disease and thus have to be further improved.

SUMMARY

The central role of TGF-β on pathological mechanisms leading to remodeling and fibrosis has been further confirmed. However, the questions of why TGF-β is activated as well as its disease and cell type specific mode of action remain to be answered. Based on clinical data redefining the term 'tissue remodeling' in a disease and cell type specific way should be considered.

Perinatal factors in neonatal and pediatric lung diseases

Wheezing and asthma are significant clinical problems for infants and young children, particularly following premature birth. Recurrent wheezing in infants can progress to persistent asthma. As in adults, altered airway structure (remodeling) and function (increased bronchoconstriction) are also important in neonatal and pediatric airway diseases. Accumulating evidence suggests that airway disease in children is influenced by perinatal factors including perturbations in normal fetal lung development, postnatal interventions in the intensive care unit (ICU) and environmental and other insults in the neonatal period. Here, in addition to genetics, maternal health, environmental processes, innate immunity and impaired lung development/function can all influence pathogenesis of airway disease in children. We summarize current understanding of how prenatal and postnatal factors can contribute to development of airway diseases in neonates and children. Understanding these mechanisms will help identify and develop novel therapies for childhood airway diseases.

Novel mechanism of aortic aneurysm development in mice associated with smoking and leukocytes

OBJECTIVE

The purpose of this study was to evaluate potential mechanisms promoting abdominal aortic aneurysm development with tobacco smoke (TS) exposure.

METHODS AND RESULTS

Experiments used the elastase perfusion model of abdominal aortic aneurysms with smoke-free controls. The effect of TS exposure was evaluated in C57/Bl6 mice, after broad-spectrum matrix metalloproteinase inhibition with doxycycline and in mice deficient in matrix metalloproteinase-9, matrix metalloproteinase-12, Cathepsin-S, and Neutrophil Elastase. Preparations of washed marrow, spleen, and peripheral blood leukocytes were transferred to smoke-free mice from 6-week TS-exposed mice or smoke-free mice. All mice were euthanized 14 days after elastase perfusion, and the percentage of change in aortic diameter (%Δ aortic diameter) was calculated. Electron microscopy of aortic tissue from animals exposed to TS without elastase exposure did not demonstrate any ultrastructural changes. Neither doxycycline nor any specific elastase deficiency was effective at preventing an increase in %Δ aortic diameter in TS-exposed animals. Smoke exposure for 6 weeks increased the %Δ aortic diameter after a smoke-free interval of up to 6 weeks before elastase perfusion. Leukocyte preparations from TS-exposed mice localized to abdominal aortic aneurysms and increased the %Δ aortic diameter in smoke-free mice.

CONCLUSIONS

The effect of TS on the development of abdominal aortic aneurysms is not dependent on the activity of elastolytic enzymes and persists for long periods despite cessation of TS. Alterations in leukocyte response to aortic injury appear to mediate this effect.