Nicotine reduces the incidence of type I diabetes in mice

Phytochemicals derived from Nicotiana tabacum L. plant contribute to pharmaceutical development

The Nicotiana tabacum L. plant, a medicinal resource, holds significant potential for benefiting human health, as evidenced by its use in Native American and ancient Chinese cultures. Modern medical and pharmaceutical studies have investigated that the abundant and distinctive function metabolites in tobacco including nicotine, solanesol, cembranoid diterpenes, essential oil, seed oil and other tobacco extracts, avoiding the toxic components of smoke, mainly have the anti-oxidation, anti-lipid production, pro-lipid oxidation, pro-insulin sensitivity, anti-inflammation, anti-apoptosis and antimicrobial activities. They showed potential pharmaceutical value mainly as supplements or substitutes for treating neurodegenerative diseases including Alzheimer's and Parkinson's disease, inflammatory diseases including colitis, arthritis, sepsis, multiple sclerosis, and myocarditis, and metabolic syndrome including Obesity and fatty liver. This review comprehensively presents the research status and the molecular mechanisms of tobacco and its metabolites basing on almost all the English and Chinese literature in recent 20 years in the field of medicine and pharmacology. This review serves as a foundation for future research on the medicinal potential of tobacco plants.

Prenatal and adult exposure to smoking and incidence of type 1 diabetes in children and adults-a nationwide cohort study with a family-based design

Background

Prenatal exposure to smoking is linked to a reduced risk of type 1 diabetes in children. We wanted to find out if the risk of adult-onset type 1 diabetes is reduced in individuals who are exposed to smoking prenatally or during adulthood.

Methods

We linked Swedish, nationwide registers and prospectively analyzed incidence of type 1 diabetes in relation to maternal smoking during pregnancy and adult smoking. Everyone was followed until age 30 or year 2019. We employed cohort and sibling design and used adjusted Cox regression and conditional logistic regression.

Findings

For analyses of maternal smoking there were 3,170,386 individuals (18,745 cases of type 1 diabetes) and for adult smoking 1,608,291 individuals (1274 cases). Prenatal exposure to smoking was associated with lower incidence of type 1 diabetes during childhood and young adulthood (age 20-24, Hazard ratio (HR) 0.76, 95% Confidence interval 0.67-0.87), but not at higher ages. The HR associated with adult smoking was estimated at 1.14 (CI 1.00-1.31) overall and 1.34 (CI 1.03-1.75) in those with family history of diabetes. In sibling analyses, the odds ratio (OR) of type 1 diabetes in relation to prenatal exposure was 0.71 (CI 0.62-0.81) in children and 1.06 (CI 0.75-1.51) in adults (age 19-30), while adult smoking conferred an OR of 1.59 (CI 1.08-2.35).

Interpretation

These findings indicate that a reduced risk conferred by tobacco exposure is limited to the prenatal period and type 1 diabetes developing during childhood. Adult smoking may be a risk factor for adult-onset type 1 diabetes, especially in people with family history of diabetes.

Funding

Swedish Research Councils, Swedish Diabetes and Novo Nordisk Foundations, China Scholarship Council.

Identification of Smoking-Associated Transcriptome Aberration in Blood with Machine Learning Methods

Long-term cigarette smoking causes various human diseases, including respiratory disease, cancer, and gastrointestinal (GI) disorders. Alterations in gene expression and variable splicing processes induced by smoking are associated with the development of diseases. This study applied advanced machine learning methods to identify the isoforms with important roles in distinguishing smokers from former smokers based on the expression profile of isoforms from current and former smokers collected in one previous study. These isoforms were deemed as features, which were first analyzed by the Boruta to select features highly correlated with the target variables. Then, the selected features were evaluated by four feature ranking algorithms, resulting in four feature lists. The incremental feature selection method was applied to each list for obtaining the optimal feature subsets and building high-performance classification models. Furthermore, a series of classification rules were accessed by decision tree with the highest performance. Eventually, the rationality of the mined isoforms (features) and classification rules was verified by reviewing previous research. Features such as isoforms ENST00000464835 (expressed by LRRN3), ENST00000622663 (expressed by SASH1), and ENST00000284311 (expressed by GPR15), and pathways (cytotoxicity mediated by natural killer cell and cytokine-cytokine receptor interaction) revealed by the enrichment analysis, were highly relevant to smoking response, suggesting the robustness of our analysis pipeline.

Effect of Nicotine on Immune System Function

As a parasympathetic alkaloid and the main substance in cigarette smoke, nicotine modulates the immune system, inhibits innate and acquired immunity and is used in treating many autoimmune diseases. It often stimulates the α7 receptor and causes an anti-inflammatory state in the body. This study is designed to evaluate the role of nicotine treatment on immune system. The results showed that nicotine affects many cells in immune system, alters the downstream intracellular mechanisms and changes lymphocytes polarization. This substance alters TLRs and STATs gene expression and thus changes in the innate immune system. All these events inhibit the secretion of pro-inflammatory cytokines and chemokines which increase angiogenesis and metastasis and exacerbates tumors due to increasing survival and cell growth. Nicotine can aggravate tumors in cancer patients, with many positive effects observed in the treating autoimmune disease, Nicotine treatment function in different conditions depends on factors such as concentration, how it is employed, treatment duration and other conditions such as body conditions affecting the immune system, hence, further studies and review of all conditions are required.

Maternal smoking during pregnancy and type 1 diabetes in the offspring: a nationwide register-based study with family-based designs

BACKGROUND

Maternal smoking during pregnancy was reported to be associated with a reduced risk of type 1 diabetes in the offspring. We investigated whether this association is consistent with a causal interpretation by accounting for familial (shared genetic and environmental) factors using family-based, quasi-experimental designs.

METHODS

We included 2,995,321 children born in Sweden between 1983 and 2014 and followed them for a diagnosis of type 1 diabetes until 2020 through the National Patient, Diabetes and Prescribed Drug Registers. Apart from conducting a traditional cohort study, we performed a nested case-control study (quasi-experiment) comparing children with type 1 diabetes to their age-matched siblings (or cousins). Information on maternal smoking during pregnancy was retrieved from the Swedish Medical Birth Register. Multivariable adjusted Cox proportional hazards regression and conditional logistic regression were used.

RESULTS

A total of 18,617 children developed type 1 diabetes, with a median age at diagnosis of 9.4 years. The sibling and cousin comparison design included 14,284 and 7988 of these children, respectively. Maternal smoking during pregnancy was associated with a 22% lower risk of offspring type 1 diabetes in the full cohort (hazard ratio 0.78, 95% confidence interval [CI] 0.75-0.82). The corresponding odds ratio was 0.78 (95% CI 0.69-0.88) in the sibling and 0.72 (95% CI 0.66-0.79) in the cousin comparison analysis.

CONCLUSIONS

This nationwide, family-based study provides support for a protective effect of maternal smoking on offspring type 1 diabetes. Mechanistic studies are needed to elucidate the underlying pathways behind this link.

Parental smoking, type 1 diabetes, and islet autoantibody positivity in the offspring: A systematic review and meta-analysis

AIMS

Our aim was to synthesize current evidence on the association between parental smoking and incidence of type 1 diabetes and islet autoantibody positivity (IA) in the offspring by conducting a systematic review and meta-analysis.

METHODS

We searched Medline, Embase, and Cochrane Library until January 21, 2021, for human studies with parental tobacco use as exposure, type 1 diabetes or IA as outcome, and hazard, risk, or odds ratios as effect estimates. Summary relative risks (RR) and 95% confidence intervals (CI) were estimated with random-effects models. Heterogeneity was quantified with the I²  statistic, bias with the ROBINS-I tool, and the certainty of evidence with the GRADE tool.

RESULTS

We identified 535 records of which 23 were eligible including 25 927 cases of type 1 diabetes. Maternal smoking during pregnancy was associated with a reduced risk of type 1 diabetes (n = 22, RR 0.78, CI 0.71-0.86, I² =69%). Including only studies with low to moderate risk of bias indicated similar results with less heterogeneity (n = 14, RR 0.73, CI 0.68-0.79, I²  = 44%). The certainty of evidence was graded as high. There was no clear association between type 1 diabetes and neither maternal (n = 6, RR 0.95, CI 0.78-1.14, I²  = 0%) nor paternal (n = 6, RR 0.90, 0.70-1.17, I²  = 68%) smoking during childhood. Furthermore, the association between maternal smoking during pregnancy and IA was weak (n = 4, RR 0.86, CI 0.44-1.65, I²  = 71%).

CONCLUSIONS

Maternal smoking during pregnancy may reduce the risk of type 1 diabetes in the offspring. Further studies are needed to elucidate potential mechanisms underlying this association.

REGISTRATION

Prospero CRD42021236717.

Anatabine, Nornicotine, and Anabasine Reduce Weight Gain and Body Fat through Decreases in Food Intake and Increases in Physical Activity

Obesity is a leading cause of preventable death in the United States. Currently approved pharmacotherapies for the treatment of obesity are associated with rebound weight gain, negative side effects, and the potential for abuse. There is a need for new treatments with fewer side effects. Minor tobacco alkaloids (MTAs) are potential candidates for novel obesity pharmacotherapies. These alkaloids are structurally related to nicotine, which can help reduce body weight, but without the same addictive potential. The purpose of the current study was to examine the effects of three MTAs (nornicotine, anatabine, and anabasine) and nicotine on weight gain, body composition, chow intake, and physical activity. We hypothesized that the MTAs and nicotine would reduce weight gain through reductions in chow intake and increases in physical activity. To test this, male Sprague Dawley rats were housed in metabolic phenotyping chambers. Following acclimation to these chambers and to (subcutaneous (sc)) injections of saline, animals received daily injections (sc) of nornicotine, anabasine, anatabine, or nicotine for one week. Compared to saline-injected animals that gained body weight and body fat during the treatment phase, injections of nornicotine and anatabine prevented additional weight gain, alongside reductions in body fat. Rats receiving anabasine and nicotine gained body weight at a slower rate relative to rats receiving saline injections, and body fat remained unchanged. All compounds reduced the intake of chow pellets. Nornicotine and nicotine produced consistent increases in physical activity 6 h post-injection, whereas anabasine’s and anatabine’s effects on physical activity were more transient. These results show that short-term, daily administration of nornicotine, anabasine, and anatabine has positive effects on weight loss, through reductions in body fat and food intake and increases in physical activity. Together, these findings suggest that MTAs are worthy of further investigations as anti-obesity pharmacotherapies.

Nicotine' actions on energy balance: Friend or foe?

Obesity has reached pandemic proportions and is associated with severe comorbidities, such as type 2 diabetes mellitus, hepatic and cardiovascular diseases, and certain cancer types. However, the therapeutic options to treat obesity are limited. Extensive epidemiological studies have shown a strong relationship between smoking and body weight, with non-smokers weighing more than smokers at any age. Increased body weight after smoking cessation is a major factor that interferes with their attempts to quit smoking. Numerous controlled studies in both humans and rodents have reported that nicotine, the main bioactive component of tobacco, exerts a marked anorectic action. Furthermore, nicotine is also known to modulate energy expenditure, by regulating the thermogenic activity of brown adipose tissue (BAT) and the browning of white adipose tissue (WAT), as well as glucose homeostasis. Many of these actions occur at central level, by controlling the activity of hypothalamic neuropeptide systems such as proopiomelanocortin (POMC), or energy sensors such as AMP-activated protein kinase (AMPK). However, direct impact of nicotine on metabolic tissues, such as BAT, WAT, liver and pancreas has also been described. Here, we review the actions of nicotine on energy balance. The relevance of this interaction is interesting, because considering the restricted efficiency of obesity treatments, a possible complementary approach may focus on compounds with known pharmacokinetic profile and pharmacological actions, such as nicotine or nicotinic acetylcholine receptors signaling.

Nicotinic acetylcholine receptor signaling regulates inositol-requiring enzyme 1α activation to protect β-cells against terminal unfolded protein response under irremediable endoplasmic reticulum stress

AIMS/INTRODUCTION

Under irremediable endoplasmic reticulum (ER) stress, hyperactivated inositol-requiring enzyme 1α (IRE1α) triggers the terminal unfolded protein response (T-UPR), causing crucial cell dysfunction and apoptosis. We hypothesized that nicotinic acetylcholine receptor (nAChR) signaling regulates IRE1α activation to protect β-cells from the T-UPR under ER stress.

MATERIALS AND METHODS

The effects of nicotine on IRE1α activation and key T-UPR markers, thioredoxin-interacting protein and insulin/proinsulin, were analyzed by real-time polymerase chain reaction and western blotting in rat INS-1 and human EndoC-βH1 β-cell lines. Doxycycline-inducible IRE1α overexpression or ER stress agents were used to induce IRE1α activation. An α7 subunit-specific nAChR agonist (PNU-282987) and small interfering ribonucleic acid for α7 subunit-specific nAChR were used to modulate nAChR signaling.

RESULTS

Nicotine inhibits the increase in thioredoxin-interacting protein and the decrease in insulin 1/proinsulin expression levels induced by either forced IRE1α hyperactivation or ER stress agents. Nicotine attenuated X-box-binding protein-1 messenger ribonucleic acid site-specific splicing and IRE1α autophosphorylation induced by ER stress. Furthermore, PNU-282987 attenuated T-UPR induction by either forced IRE1α activation or ER stress agents. The effects of nicotine on attenuating thioredoxin-interacting protein and preserving insulin 1 expression levels were attenuated by pharmacological and genetic inhibition of α7 nAChR. Finally, nicotine suppressed apoptosis induced by either forced IRE1α activation or ER stress agents.

CONCLUSIONS

Our findings suggest that nAChR signaling regulates IRE1α activation to protect β-cells from the T-UPR and apoptosis under ER stress partly through α7 nAChR. Targeting nAChR signaling to inhibit the T-UPR cascade may therefore hold therapeutic promise by thwarting β-cell death in diabetes.

Estrogen-progestin oral contraceptive and nicotine exposure synergistically confers cardio-renoprotection in female Wistar rats

Approximately fifty percent of premenopausal women who smoke cigarettes or on nicotine replacement therapy are also on hormonal contraceptives, especially oral estrogen-progestin. Oral estrogen-progestin therapy has been reported to promote insulin resistance (IR) which causes lipid influx into non-adipose tissue and impairs Na⁺/K⁺ -ATPase activity, especially in the heart and kidney. However, the effects of nicotine on excess lipid and altered Na⁺/K⁺ -ATPase activity associated with the use of estrogen-progestin therapy have not been fully elucidated. This study therefore aimed at investigating the effect of nicotine on cardiac and renal lipid influx and Na⁺/K⁺ -ATPase activity during estrogen-progestin therapy. Twenty-four female Wistar rats grouped into 4 (n = 6/group) received (p.o.) vehicle, nicotine (1.0 mg/kg) with or without estrogen-progestin steroids (1.0 μg ethinyl estradiol and 5.0 μg levonorgestrel) and estrogen-progestin only daily for 6 weeks. Data showed that estrogen-progestin treatment or nicotine exposure caused IR, hyperinsulinemia, increased cardiac and renal uric acid, malondialdehyde, triglyceride, glycogen synthase kinase-3, plasminogen activator inhibitor-1, reduced bilirubin and circulating estradiol. Estrogen-progestin treatment led to decreased cardiac Na⁺/K⁺-ATPase activity while nicotine did not alter Na⁺/K⁺-ATPase activity but increased plasma and tissue cotinine. Renal Na⁺/K⁺-ATPase activity was not altered by the treatments. However, all these alterations were reversed following combined administration of oral estrogen-progestin therapy and nicotine. The present study therefore demonstrates that oral estrogen-progestin therapy and nicotine exposure synergistically prevents IR-linked cardio-renotoxicity with corresponding improvement in cardiac and renal lipid accumulation, oxidative stress, inflammation and Na⁺/K⁺-ATPase activity.

Attenuation in Nicotinic Acetylcholine Receptor α9 and α10 Subunit Double Knock-Out Mice of Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor (nAChR) α9 subunit knock-out (α9 KO) mice. However, protection is incomplete, raising questions about roles for related, nAChR α10 subunits in ionotropic or recently-revealed metabotropic contributions to effects. Here, we demonstrate reduced EAE severity and delayed onset of disease signs in nAChR α9/α10 subunit double knock-out (DKO) animals relative to effects in wild-type (WT) control mice. These effects are indistinguishable from contemporaneously-observed effects in nicotine-treated WT or in α9 KO mice. Immune cell infiltration into the spinal cord and brain, reactive oxygen species levels in vivo, and demyelination, mostly in the spinal cord, are reduced in DKO mice. Disease severity is not altered relative to WT controls in mice harboring a gain-of-function mutation in α9 subunits. These findings minimize the likelihood that additional deletion of nAChR α10 subunits impacts disease differently than α9 KO alone, whether through ionotropic, metabotropic, or alternative mechanisms. Moreover, our results provide further evidence of disease-exacerbating roles for nAChR containing α9 subunits (α9*-nAChR) in EAE inflammatory and autoimmune responses. This supports our hypothesis that α9*-nAChR or their downstream mediators are attractive targets for attenuation of inflammation and autoimmunity.

The influence of maternal body mass index, maternal diabetes mellitus, and maternal smoking during pregnancy on the risk of childhood-onset type 1 diabetes mellitus in the offspring: Systematic review and meta-analysis of observational studies

There is emerging evidence that events occurring before and shortly after birth may be important in determining the risk of childhood-onset type 1 diabetes mellitus (T1DM). We aimed to summarize and synthesize the associations between maternal body mass index (BMI), maternal diabetes mellitus (DM), and maternal smoking during pregnancy and the risk of childhood-onset T1DM in the offspring by performing a systematic review and meta-analysis of observational studies. A random effects model was used to generate the summary risk estimates. The PubMed and Web of Science databases were searched to identify relevant observational studies. Twenty one observational studies were included in the present meta-analysis. Compared with offspring of mothers with normal weight, offspring of women with overweight or obesity were at an increased risk of developing childhood-onset T1DM (overweight: relative risk [RR] 1.09, 95% confidence interval [CI], 1.03-1.15; obesity: RR 1.25, 95% CI, 1.16-1.34; per 5 kg m^-2 increase in BMI: RR 1.10, 95% CI, 1.06-1.13). No association was found for maternal underweight (RR 0.92, 95% CI, 0.75-1.13). Maternal DM was associated with an increased risk of childhood-onset T1DM (RR 3.26, 95% CI, 2.84-3.74). Regarding the type of maternal DM, the greatest risk of T1DM in the offspring appeared to be conferred by maternal T1DM (RR 4.46, 95% CI, 2.89-6.89), followed by maternal gestational diabetes mellitus (RR 1.66, 95% CI, 1.16-2.36), and lastly by maternal type 2 diabetes mellitus (RR 1.11, 95% CI, 0.69-1.80). Additional analysis of studies comparing maternal versus paternal T1DM within the same population revealed that offspring of fathers with T1DM had a 1.5 times higher risk of developing childhood-onset T1DM than offspring of mothers with T1DM (RR 9.58, 95% CI, 6.33-14.48 vs. RR 6.24, 95% CI, 5.52-7.07). Furthermore, a reduced risk of childhood-onset T1DM was observed in infants born to mothers who smoked during pregnancy compared with infants born to mothers who did not smoke during pregnancy (RR 0.79, 95% CI, 0.71-0.87). In summary, our findings add further evidence that early-life events or environmental factors may play a role in modulating infants' risk of developing T1DM later in life.

Involvement of Acetylcholine Receptors in Cholinergic Pathway-Mediated Protection Against Autoimmune Diabetes

Type I diabetes (T1D) is a T cell-driven autoimmune disease that results in the killing of pancreatic β-cells and, consequently, loss of insulin production. Using the multiple low-dose streptozotocin (MLD-STZ) model of experimental autoimmune diabetes, we previously reported that pretreatment with a specific acetylcholinesterase inhibitor (AChEI), paraoxon, prevented the development of hyperglycemia in C57BL/6 mice. This correlated with an inhibition of T cell infiltration into the pancreatic islets and a reduction in pro-inflammatory cytokines. The cholinergic anti-inflammatory pathway utilizes nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs, respectively) expressed on a variety of cell types. In this study, we carried out a comparative analysis of the effect of specific antagonists of nAChRs or mAChRs on the development of autoimmune diabetes. Co-administration of mecamylamine, a non-selective antagonist of nAChRs maintained the protective effect of AChEI on the development of hyperglycemia. In contrast, co-administration of atropine, a non-selective antagonist of mAChRs, mitigated AChEI-mediated protection. Mice pretreated with mecamylamine had an improved response in glucose tolerance test (GTT) than mice pretreated with atropine. These differential effects of nAChR and mAChR antagonists correlated with the extent of islet cell infiltration and with the structure and functionality of the β-cells. Taken together, our data suggest that mAChRs are essential for the protective effect of cholinergic stimulation in autoimmune diabetes.

Smoking in pregnancy, cord blood cotinine and risk of celiac disease diagnosis in offspring

Ecological observations suggest an inverse relationship between smoking in pregnancy and celiac disease (CD) in offspring. While individual-level analyses have been inconsistent, they have mostly lacked statistical power or refined assessments of exposure. To examine the association between pregnancy-related smoking and CD in the offspring, as well as its consistency across data sets, we analyzed: (1) The Norwegian Mother and Child Cohort (MoBa) of 94,019 children, followed from birth (2000–2009) through 2016, with 1035 developing CD; (2) a subsample from MoBa (381 with CD and 529 controls) with biomarkers; and (3) a register-based cohort of 536,861 Norwegian children, followed from birth (2004–2012) through 2014, with 1919 developing CD. Smoking behaviors were obtained from pregnancy questionnaires and antenatal visits, or, in the MoBa-subsample, defined by measurement of cord blood cotinine. CD and potential confounders were identified through nationwide registers and comprehensive parental questionnaires. Sustained smoking during pregnancy, both self-reported and cotinine-determined, was inversely associated with CD in MoBa (multivariable-adjusted [a] OR = 0.61 [95%CI, 0.46–0.82] and aOR = 0.55 [95%CI, 0.31–0.98], respectively); an inverse association was also found with the intensity of smoking. These findings differed from those of our register-based cohort, which revealed no association with sustained smoking during pregnancy (aOR = 0.97 [95%CI, 0.80–1.18]). In MoBa, neither maternal smoking before or after pregnancy, nor maternal or paternal smoking in only early pregnancy predicted CD. In a carefully followed pregnancy cohort, a more-detailed smoking assessment than oft-used register-based data, revealed that sustained smoking during pregnancy, rather than any smoking exposure, predicts decreased likelihood of childhood-diagnosed CD.

MYMD-1, a Novel Immunometabolic Regulator, Ameliorates Autoimmune Thyroiditis via Suppression of Th1 Responses and TNF-α Release

MYMD-1 is a synthetic derivative of tobacco alkaloids, compounds that possess immunoregulatory properties and have been linked to the epidemiological observation that smoking reduces the odds of developing thyroid Abs and hypothyroidism. To assess the effect and mechanism(s) of the action of MYMD-1, we chose the NOD.H-2h4 mouse model of spontaneous thyroiditis. We began in vitro using T cells isolated from NOD.H-2h4 spleens and found that MYMD-1 suppressed TNF-α production by CD4+ T cells in a dose-dependent manner. We then treated 58 NOD.H-2h4 mice for 12 wk with either unsupplemented water that contained (10 mice) or did not contain (16 mice) MYMD-1 (185 mg/l) or water supplemented with sodium iodide (500 mg/l) that contained (16 mice) or did not contain (16 mice) MYMD-1. Mice were bled at baseline and then every 2 wk until sacrifice. MYMD-1 decreased the incidence and severity (p < 0.001) of thyroiditis, as assessed by histopathology. Similarly, the number of CD3+ T cells and CD19+ B cells infiltrating the thyroid was dampened by MYMD-1, as assessed by flow cytometry. Interestingly, the subset of thyroidal CD3+CD4+Tbet+RORγT- effector Th1 cells and the systemic levels of TNF-α were decreased by MYMD-1. Serum thyroglobulin Abs decreased in the MYMD-1 group. Thyroid hormones did not differ among the four groups, whereas thyroid-stimulating hormone increased upon iodine supplementation but remained normal in MYMD-1-treated mice. Overall, the study suggests that MYMD-1 ameliorates thyroiditis acting on specific lymphoid subsets. Further studies, including other models of autoimmunity, will confirm the potential clinical use of MYMD-1 as a novel immunometabolic regulator.

Environmental (Lifestyle) Risk Factors for LADA

BACKGROUND

In order to prevent diabetes it is important to identify common, modifiable risk factors in the population. Such knowledge is extensive for type 2 diabetes but limited for autoimmune forms of diabetes.

OBJECTIVE

This review aims at summarizing the limited literature on potential environmental (lifestyle) risk factors for LADA.

METHODS

A PubMed search identified 15 papers estimating the risk of LADA in relation to lifestyle. These were based on data from two population-based studies; one Swedish case-control study and one Norwegian cohort study.

RESULTS

Studies published to date indicate that the risk of LADA is associated with factors promoting insulin resistance and type 2 diabetes such as overweight, physical inactivity, smoking, low birth weight, sweetened beverage intake and moderate alcohol consumption (protective). Findings also indicate potential effects on autoimmunity exerted by intake of coffee (harmful) and fatty fish (protective). This supports the concept of LADA as being a hybrid form of diabetes with an etiology including factors associated with both insulin resistance and autoimmunity.

CONCLUSION

LADA may in part be preventable through the same lifestyle modifications as type 2 diabetes including weight loss, physical activity and smoking cessation. However, current knowledge is hampered by the small number of studies and the fact that they exclusively are based on Scandinavian populations. There is a great need for additional studies exploring the role of lifestyle factors in the development of LADA.

β-Cell mass restoration by α7 nicotinic acetylcholine receptor activation

Although it is well-established how nutrients, growth factors, and hormones impact functional β-cell mass (BCM), the influence of the central nervous system in this regard, and especially in the context of islet immune modulation, has been understudied. Here we investigated the expression and activity of pancreatic islet α7 nicotinic acetylcholine receptor (α7nAChR) in islet anti-inflammatory and prosurvival signaling. Systemic administration of α7nAChR agonists in mice improved glucose tolerance and curtailed streptozotocin-induced hyperglycemia by retaining BCM, in part through maintaining Pdx1 and MafA expression and reducing apoptosis. α7nAChR activation of mouse islets ex vivo led to reduced inflammatory drive through a JAK2-STAT3 pathway that couples with CREB/Irs2/Akt survival signaling. Because the vagus nerve conveys anti-inflammatory signals to immune cells of the spleen and other nonneural tissues in the viscera by activating α7nAChR agonists, our study suggests a novel role for β-cell α7nAChR that functions to maintain β-cell survival and mass homeostasis through modulating islet cytokine and phosphatidylinositol 3-kinase-dependent signaling pathways. Exploiting these pathways may have therapeutic potential for the treatment of autoimmune diabetes.

Parental Smoking and Risk of Childhood-onset Type 1 Diabetes

BACKGROUND

A few prospective studies suggest an association between maternal smoking during pregnancy and lower risk of type 1 diabetes. However, the role of unmeasured confounding and misclassification remains unclear.

METHODS

We comprehensively evaluated whether maternal smoking in pregnancy predicts lower risk of childhood-onset type 1 diabetes in two Scandinavian pregnancy cohorts (185,076 children; 689 cases) and a Norwegian register-based cohort (434,627 children; 692 cases). We measured cord blood cotinine as an objective marker of nicotine exposure during late pregnancy in 154 cases and 476 controls. We also examined paternal smoking during pregnancy, in addition to environmental tobacco smoke exposure the first 6 months of life, to clarify the role of characteristics of smokers in general.

RESULTS

In the pregnancy cohorts, maternal smoking beyond gestational week 12 was inversely associated with type 1 diabetes, pooled adjusted hazard ratio (aHR) 0.66 (95% CI = 0.51, 0.85). Similarly, in the Norwegian register-based cohort, children of mothers who still smoked at the end of pregnancy had lower risk of type 1 diabetes, aHR 0.65 (95% CI = 0.47, 0.89). Cord blood cotinine ≥30 nmol/L was also associated with reduced risk of type 1 diabetes, adjusted odds ratio 0.42 (95% CI = 0.17, 1.0). We observed no associations of paternal smoking during pregnancy, or environmental tobacco smoke exposure, with childhood-onset type 1 diabetes.

CONCLUSION

Maternal sustained smoking during pregnancy is associated with lower risk of type 1 diabetes in children. This sheds new light on the potential intrauterine environmental origins of the disease.

Nicotine and autoimmunity: The lotus' flower in tobacco

Nicotine, the major component of cigarettes, has demonstrated conflicting impact on the immune system: some authors suggest that increases pro-inflammatory cytokines and provokes cellular apoptosis of neutrophils, releasing intracellular components that act as auto-antigens; others claimed that nicotine has a protective and anti-inflammatory effects, especially by binding to α7 subunit of nicotinic acetylcholine receptors. The cholinergic pathway contributes to an anti-inflammatory environment characterized by increasing T regulatory cells response, down-regulating of pro-inflammatory cytokines and a pro-inflammatory cells apoptosis. The effects of nicotine were studied in different autoimmune disease, as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, sarcoidosis, Behçet's disease and inflammatory bowel diseases. The major problems about nicotine are the addiction and the adverse effects of related to each commercialized formulation. We sought in this review to summarize the knowledge accumulated to date concerning the relationship between nicotine and autoimmunity.

Indices of insulin resistance and glucotoxicity are not associated with bipolar disorder or major depressive disorder, but are differently associated with inflammatory, oxidative and nitrosative biomarkers

BACKGROUND

Insulin resistance (IR) is a key factor in diabetes mellitus, metabolic syndrome (MetS) and obesity and may occur in mood disorders and tobacco use disorder (TUD), where disturbances of immune-inflammatory, oxidative and nitrosative stress (IO&NS) pathways are important shared pathophysiological pathways.

METHODS

This study aimed to a) examine IR and β-cell function as measured by the homeostasis model assessment of insulin resistance (HOMA-IR) and insulin sensitivity and β cell function (HOMA-B) and glucotoxicity (conceptualized as increased glucose levels versus lowered HOMA-B values) in 74 participants with major depressive disorder (MDD) and bipolar disorder, with and or without MetS and TUD, versus 46 healthy controls, and b) whether IR is associated with IO&NS biomarkers, including nitric oxide metabolites (NOx), lipid hydroperoxides (LOOH), plasma advanced oxidation protein products (AOPP), C-reactive protein (CRP), haptoglobin (Hp) and uric acid.

RESULTS

Mood disorders are not associated with changes in IR or glucotoxicity, although the number of mood episodes may increase IR. 47.8% of the variance in HOMA-IR is explained by AOPP and body mass index (BMI, both positively) and NOx, Hp and TUD (all inversely). 43.2% of the variance in HOMA-B is explained by NOx, Hp and age (all inversely associated) and higher BMI and sex. The glucotoxic index is strongly associated with NOx, Hp and BMI (positively), male gender and lower education.

LIMITATIONS

This is a cross-sectional study and therefore we cannot draw firm conclusions on causal associations.

CONCLUSIONS

Activated IO&NS pathways (especially increased Hp and NOx) increase glucotoxicity and exert very complex effects modulating IR. Mood disorders are not associated with increased IR.

Anti-inflammatory and antithrombotic effects of nicotine exposure in oral contraceptive-induced insulin resistance are glucocorticoid-independent

BACKGROUND

Reports showed that estrogen-progestin oral contraceptive (COC) or tobacco smoking causes increased risk of cardiovascular diseases (CVD) in premenopausal women. Studies also suggest that nicotine, a major tobacco alkaloid, may worsen or improve atherothrombotic CVD. Altered hemorheology, prothrombotic and pro-inflammatory biomarkers, have been implicated in the development of atherothrombotic CVD events. However, the effect of non-smoking nicotine exposure on these biomarkers during COC treatment is not yet established. We therefore sought to determine the effects of nicotine exposure during COC treatment on these biomarkers, and also tested the hypothesis that the nicotine effects would be glucocorticoid-dependent.

METHODS

Female Sprague-Dawley rats aged 10 weeks were given (po) vehicle, low-dose nicotine (0.1mg/kg) or high-dose nicotine (1.0mg/kg) with or without COC steroids (5.0μg/kg ethinylestradiol and 25.0μg/kg levonorgestrel) daily for 6 weeks.

RESULTS

COC treatment or nicotine exposure led to increased insulin resistance (IR), hemorheological (blood viscosity, hematocrit and plasma viscosity), prothrombotic (plasminogen activator inhibitor-1), pro-inflammatory (uric acid, C-reactive protein, neutrophil/lymphocyte and platelet/lymphocyte ratios) biomarkers and corticosterone. However, these effects except that on corticosterone were abrogated by nicotine exposure during COC treatment.

CONCLUSIONS

Our study indicates that nicotine- or COC-induced IR may be mediated via inflammatory/thrombotic pathway. The results imply that nicotine exposure could impact negatively on atherothrombotic biomarkers in COC non-users, whereas the impact in COC users could be positive. The results also suggest that the anti-inflammatory, antithrombotic and blood viscosity-lowering effects of nicotine exposure during COC use is circulating glucocorticoid-independent.

Protective efficacy of folic acid and vitamin B12 against nicotine-induced toxicity in pancreatic islets of the rat

Although cigarette smoking is associated with insulin resistance and an increased risk for type 2 diabetes, few studies have examined the effect of nicotine on the adult endocrine pancreas. In this study, male Wister rats were treated with nicotine (3 mg/kg body weight/ day) with or without supplementation of folic acid (36 μg/kg body weight/day) or vitamin B12 (0.63 μg/kg body weight/day) alone or in combination. Fasting blood glucose, insulin and HBA1C level and different oxidative and anti-oxidative stress parameters were measured and pancreatic tissue sections were stained with eosin-haematoxylene. Data were analysed by nonparametric statistics. The results revealed that nicotine induced prediabetes condition with subsequent damage to pancreatic islets in rats. Nicotine also caused oxidative stress in pancreatic tissue as evidenced by increased nitric oxide and malondialdehyde level and decreased superoxide dismutase, catalase and reduced glutathione level. Compared to vitamin B12 supplementation, folic acid blunted the nicotine-induced toxicity in pancreatic islets with higher efficacy. Further, folic acid and vitamin B12 in combination were able to confer significant protection on pancreatic islets against nicotine induced toxicity. These results suggest that supplementation of folic acid and vitamin B12 in combination may be a possible strategy of detoxification against nicotine-induced toxicity in pancreatic islets of the rat.

Smoking and the Risk of LADA: Results From a Swedish Population-Based Case-Control Study

OBJECTIVE

Smoking is an established risk factor for type 2 diabetes. In contrast, it has been proposed that smoking may reduce the risk of latent autoimmune diabetes in adults (LADA), but studies are scarce. We aimed to study the impact of smoking on LADA and type 2 diabetes risks.

RESEARCH DESIGN AND METHODS

We used data from a Swedish case-control study including incident case patients with LADA (GAD antibody [GADA] positive, n = 377) and type 2 diabetes (GADA negative, n = 1,188) and control subjects randomly selected from the population (n = 1,472). We calculated odds ratios (ORs) with 95% CIs by logistic regression, adjusted for age, sex, BMI, family history of diabetes, and alcohol consumption.

RESULTS

There was no indication of reduced risk of LADA in smokers; instead, heavy smoking was associated with an increased risk of LADA (OR 1.37, 95% CI 1.02-1.84). Heavy smokers had higher levels of HOMA of insulin resistance (9.89 vs. 4.38, P = 0.0479) and HOMA of β-cell function (55.7 vs. 42.5, P = 0.0204), but lower levels of GADA (75 vs. 250, P = 0.0445), compared with never smokers. Smokers also displayed an increased risk of type 2 diabetes (OR in ever smokers 1.53, 95% CI 1.25-1.88).

CONCLUSIONS

In this large population of LADA patients, we did not observe a protective effect of smoking on autoimmunity and the risk of LADA. A protective effect could possibly be masked by a smoking-induced aggravation of insulin resistance, akin to the diabetogenic effect seen in individuals with type 2 diabetes.

Smoking Cessation Carries a Short-Term Rising Risk for Newly Diagnosed Diabetes Mellitus Independently of Weight Gain: A 6-Year Retrospective Cohort Study

Background. The effects of smoking on human metabolism are complex. Although smoking increases risk for diabetes mellitus, smoking cessation was also reported to be associated with weight gain and incident diabetes mellitus. We therefore conducted this study to clarify the association between smoking status and newly diagnosed diabetes mellitus. Methods. An analysis was done using the data of a mass health examination performed annually in an industrial park from 2007 to 2013. The association between smoking status and newly diagnosed diabetes mellitus was analyzed with adjustment for weight gain and other potential confounders. Results. Compared with never-smokers, not only current smokers but also ex-smokers in their first two years of abstinence had higher odds ratios (ORs) for newly diagnosed diabetes mellitus (never-smokers 3.6%, OR as 1; current smokers 5.5%, OR = 1.499, 95% CI = 1.147-1.960, and p = 0.003; ex-smokers in their first year of abstinence 7.5%, OR = 1.829, 95% CI = 0.906-3.694, and p = 0.092; and ex-smokers in their second year of abstinence 9.0%, OR = 2.020, 95% CI = 1.031-3.955, and p = 0.040). Conclusion. Smoking cessation generally decreased risk for newly diagnosed diabetes mellitus. However, increased odds were seen within the first 2 years of abstinence independently of weight gain.

Galantamine Attenuates Type 1 Diabetes and Inhibits Anti-Insulin Antibodies in Nonobese Diabetic Mice

Type 1 diabetes in mice is characterized by autoimmune destruction of insulin-producing pancreatic β-cells. Disease pathogenesis involves invasion of pancreatic islets by immune cells, including macrophages and T cells, and production of antibodies to self-antigens, including insulin. Activation of the inflammatory reflex, the neural circuit that inhibits inflammation, culminates on cholinergic receptor signals on immune cells to attenuate cytokine release and inhibit B-cell antibody production. Here, we show that galantamine, a centrally acting acetylcholinesterase inhibitor and an activator of the inflammatory reflex, attenuates murine experimental type 1 diabetes. Administration of galantamine to animals immunized with keyhole limpet hemocyanin (KLH) significantly suppressed splenocyte release of immunoglobulin G (IgG) and interleukin (IL)-4 and IL-6 during KLH challenge ex vivo. Administration of galantamine beginning at 1 month of age in nonobese diabetic (NOD) mice significantly delayed the onset of hyperglycemia, attenuated immune cell infiltration in pancreatic islets and decreased anti-insulin antibodies in serum. These observations indicate that galantamine attenuates experimental type 1 diabetes in mice and suggest that activation of the inflammatory reflex should be further studied as a potential therapeutic approach.

Perinatal risk factors for development of celiac disease in children, based on the prospective Norwegian Mother and Child Cohort Study

BACKGROUND & AIMS

There have been inconsistent reports of prenatal and perinatal factors that affect risk for development of celiac disease. We assessed the association of fetal growth, birth weight, and mode of delivery with development of celiac disease within the Norwegian Mother and Child (MoBa) Cohort Study.

METHODS

The MoBa cohort contains pregnancy information on 95,200 women and data on their 114,500 children, which were collected in Norway from 1999 through 2008; it is linked to the Medical Birth Registry. Women and children with celiac disease were identified from the National Patient Registry and from women's responses to MoBa questionnaires. We calculated odds ratios (ORs) for celiac disease by using a multivariable logistic regression model, adjusting for maternal celiac disease, sex of children, and children's age (model 1); in a second model, we adjusted for age of gluten introduction and duration of breastfeeding (model 2).

RESULTS

We identified 650 children with celiac disease and 107,828 controls in the MoBa database. We found no association between birth weight or height with celiac disease (born small for gestational age was not associated). Celiac disease was not associated with mode of delivery (cesarean section, model 1: OR, 0.84; 95% confidence interval [CI], 0.65-1.09, and model 2: OR, 0.83; 95% CI, 0.63-1.09). Maternal celiac disease, adjusted for age and sex of the children (OR, 12.45; 95% CI, 8.29-18.71) and type 1 diabetes (model 1: OR, 2.58; 95% CI, 1.19-5.53, and model 2: OR, 2.61; 95% CI, 1.14-5.98) were associated with development of celiac disease in children, whereas maternal type 2 diabetes and gestational diabetes were not.

CONCLUSIONS

On the basis of analysis of the Norwegian MoBa cohort, development of celiac disease in children is significantly associated with sex of the child, maternal celiac disease, and type 1 diabetes but not with intrauterine growth.

Endogenous ghrelin attenuates pressure overload-induced cardiac hypertrophy via a cholinergic anti-inflammatory pathway

Cardiac hypertrophy, which is commonly caused by hypertension, is a major risk factor for heart failure and sudden death. Endogenous ghrelin has been shown to exert a beneficial effect on cardiac dysfunction and postinfarction remodeling via modulation of the autonomic nervous system. However, ghrelin's ability to attenuate cardiac hypertrophy and its potential mechanism of action are unknown. In this study, cardiac hypertrophy was induced by transverse aortic constriction in ghrelin knockout mice and their wild-type littermates. After 12 weeks, the ghrelin knockout mice showed significantly increased cardiac hypertrophy compared with wild-type mice, as evidenced by their significantly greater heart weight/tibial length ratios (9.2±1.9 versus 7.9±0.8 mg/mm), left ventricular anterior wall thickness (1.3±0.2 versus 1.0±0.2 mm), and posterior wall thickness (1.1±0.3 versus 0.9±0.1 mm). Furthermore, compared with wild-type mice, ghrelin knockout mice showed suppression of the cholinergic anti-inflammatory pathway, as indicated by reduced parasympathetic nerve activity and higher plasma interleukin-1β and interleukin-6 levels. The administration of either nicotine or ghrelin activated the cholinergic anti-inflammatory pathway and attenuated cardiac hypertrophy in ghrelin knockout mice. In conclusion, our results show that endogenous ghrelin plays a crucial role in the progression of pressure overload-induced cardiac hypertrophy via a mechanism that involves the activation of the cholinergic anti-inflammatory pathway.

Inhibition of allergen-induced basophil activation by ASM-024, a nicotinic receptor ligand

BACKGROUND

Nicotinic acetylcholine receptors (nAChRs) were identified on eosinophils and shown to regulate inflammatory responses, but nAChR expression on basophils has not been explored yet.

OBJECTIVE

We investigated surface receptor expression of nAChR α4, α7 and α1/α3/α5 subunits on basophils. Furthermore, we examined the effects of ASM-024, a synthetic nicotinic ligand, on in vitro anti-IgE and in vivo allergen-induced basophil activation.

METHODS

Basophils were enriched from the peripheral blood of allergic donors and the expression of nAChR subunits and muscarinic receptors was determined. Purified basophils were stimulated with anti-IgE in the presence of ASM-024 with or without muscarinic or nicotinic antagonists for the measurement of CD203c expression and histamine release. The effect of 9 days of treatment with 50 and 200 mg ASM-024 on basophil CD203c expression was examined in the blood of mild allergic asthmatics before and after allergen inhalation challenge.

RESULTS

nAChR α4, α7 and α1/α3/α5 receptor subunit expression was detected on basophils. Stimulation of basophils with anti-IgE increased CD203c expression and histamine release, which was inhibited by ASM-024 (10(-5) to 10(-)(3) M, p < 0.05). The effect of ASM-024 was reversed in the presence of muscarinic and nicotinic antagonists. In subjects with mild asthma, ASM-024 inhalation significantly inhibited basophil CD203c expression measured 24 h after allergen challenge (p = 0.03).

CONCLUSION

This study shows that ASM-024 inhibits IgE- and allergen-induced basophil activation through both nicotinic and muscarinic receptors, and suggests that ASM-024 may be an efficacious agent for modulating allergic asthma responses.

Nicotinic acetylcholine receptors in glucose homeostasis: the acute hyperglycemic and chronic insulin-sensitive effects of nicotine suggest dual opposing roles of the receptors in male mice

Cigarette smoking causes insulin resistance. However, nicotine induces anti-inflammation and improves glucose tolerance in insulin-resistant animal models. Here, we determined the effects of nicotine on glucose metabolism in insulin-sensitive C57BL/J6 mice. Acute nicotine administration (30 min) caused fasting hyperglycemia and lowered insulin sensitivity acutely, which depended on the activation of nicotinic-acetylcholine receptors (nAChRs) and correlated with increased catecholamine secretion, nitric oxide (NO) production, and glycogenolysis. Chlorisondamine, an inhibitor of nAChRs, reduced acute nicotine-induced hyperglycemia. qRT-PCR analysis revealed that the liver and muscle express predominantly β4 > α10 > α3 > α7 and β4 > α10 > β1 > α1 mRNA for nAChR subunits respectively, whereas the adrenal gland expresses β4 > α3 > α7 > α10 mRNA. Chronic nicotine treatment significantly suppressed expression of α3-nAChR (predominant peripheral α-subunit) in liver. Whereas acute nicotine treatment raised plasma norepinephrine (NE) and epinephrine (Epi) levels, chronic nicotine exposure raised only Epi. Acute nicotine treatment raised both basal and glucose-stimulated insulin secretion (GSIS). After chronic nicotine treatment, basal insulin level was elevated, but GSIS after acute saline or nicotine treatment was blunted. Chronic nicotine exposure caused an increased buildup of NO in plasma and liver, leading to decreased glycogen storage, along with a concomitant suppression of Pepck and G6Pase mRNA, thus preventing hyperglycemia. The insulin-sensitizing effect of chronic nicotine was independent of weight loss. Chronic nicotine treatment enhanced PI-3-kinase activities and increased Akt and glycogen synthase kinase (GSK)-3β phosphorylation in an nAChR-dependent manner coupled with decreased cAMP response element-binding protein (CREB) phosphorylation. The latter effects caused suppression of Pepck and G6Pase gene expression. Thus, nicotine causes both insulin resistance and insulin sensitivity depending on the duration of the treatment.

Smoking is associated with reduced risk of autoimmune diabetes in adults contrasting with increased risk in overweight men with type 2 diabetes: a 22-year follow-up of the HUNT study

OBJECTIVE

To investigate the association between smoking habits and risk of autoimmune diabetes in adults and of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We used data from the three surveys of the Nord-Trøndelag Health Study, spanning 1984-2008 and including a cohort of 90,819 Norwegian men (48%) and women (52%) aged ≥20 years. Incident cases of diabetes were identified by questionnaire and classified as type 2 diabetes (n = 1,860) and autoimmune diabetes (n = 140) based on antibodies to glutamic decarboxylase (GADA) and age at onset of diabetes. Hazard ratios (HRs) adjusted for confounders were estimated by Cox proportional hazards regression models.

RESULTS

The risk of autoimmune diabetes was reduced by 48% (HR 0.52 [95% CI 0.30-0.89]) in current smokers and 58% in heavy smokers (0.42 [0.18-0.98]). The reduced risk was positively associated with number of pack-years. Heavy smoking was associated with lower levels of GADA (P = 0.001) and higher levels of C-peptide (964 vs. 886 pmol/L; P = 0.03). In contrast, smoking was associated with an increased risk of type 2 diabetes, restricted to overweight men (1.33 [1.10-1.61]). Attributable proportion due to an interaction between overweight and heavy smoking was estimated to 0.40 (95% CI 0.23-0.57).

CONCLUSIONS

In this epidemiological study, smoking is associated with a reduced risk of autoimmune diabetes, possibly linked to an inhibitory effect on the autoimmune process. An increased risk of type 2 diabetes was restricted to overweight men.

Nicotine exposure exacerbates development of cataracts in a type 1 diabetic rat model

Diabetes and smoking are known risk factors for cataract development. In this study, we evaluated the effect of nicotine on the progression of cataracts in a type 1 diabetic rat model. Diabetes was induced in Sprague-Dawley rats by a single injection of 65 mg/kg streptozotocin. Daily nicotine injections were administered subcutaneously. Forty-five rats were divided into groups of diabetics with and without nicotine treatment and controls with and without nicotine treatment. Progression of lens opacity was monitored using a slit lamp biomicroscope and scores were assigned. To assess whether systemic inflammation played a role in mediating cataractogenesis, we studied serum levels of eotaxin, IL-6, and IL-4. The levels of the measured cytokines increased significantly in nicotine-treated and untreated diabetic animals versus controls and demonstrated a positive trend in the nicotine-treated diabetic rats. Our data suggest the presence of a synergistic relationship between nicotine and diabetes that accelerated cataract formation via inflammatory mediators.

Renoprotective effects of long-term oral nicotine in a rat model of spontaneous proteinuria

Many proteinuric renal conditions are accompanied by renal inflammation. Nicotine is known to have anti-inflammatory properties and is used in oral form to help subjects quit smoking. A potential anti-inflammatory role of nicotine in proteinuric renal diseases has not been investigated to date. We therefore evaluated the effects of oral nicotine in a rat model of proteinuria-induced renal inflammation. We used a well-established model of adult (24 wk of age) male Munich-Wistar-Frömter rats. Animals were given three different physiological doses of nicotine in drinking water for 28 wk until 52 wk of age (long term). A group without nicotine served as a parallel control. At 52 wk of age, the control group had a 2.1 times reduction in creatinine clearance, 3.2 times increase in urinary protein excretion, an increased focal glomerulosclerosis (FGS) score, increased glomerular desmin deposition, decreased glomerular podocin, and a higher accumulation of macrophages and myofibroblasts compared with 24-wk-old animals. Oral treatment with nicotine dose dependently preserved renal function and halted proteinuria progression, which were independent of blood pressure reduction. It also reduced FGS, desmin deposition, podocin loss, and density of renal macrophages and myofibroblasts. Nicotine also reduced the level of gene expression of the renal inflammatory markers monocyte chemoattractant protein and vascular cell adhesion molecule-1. In conclusion, long-term oral nicotine preserved kidney function, reduced proteinuria, reduced renal inflammation, and protected progression of renal structural damage in a rat model of proteinuria. We further suggest evaluating nicotine as a potential additional therapeutic option for treating proteinuric kidney diseases.

Nicotine exerts an anti-inflammatory effect in a murine model of acute lung injury

Activation of the cholinergic anti-inflammatory pathway through direct activation of nicotinic acetylcholine receptors on immune cells can inhibit pro-inflammatory chemokine and cytokine release and thereby protect in a variety of inflammatory diseases. The aim of this study was to investigate whether nicotine treatment protected against acute lung inflammation. Mice challenged with intratracheal lipopolysaccharide (LPS, 50 μg) were treated with nicotine (0.2 or 0.4 mg/kg, sc). After 24 h, bronchoalveolar lavage fluid (BALF) was obtained to measure leukocyte infiltration, lung edema, and pro-inflammatory chemokine (MIP-1α, MIP-2, and eotaxin) and cytokine (IL-1, IL-6, and TNF-α) levels. Nicotine treatment reduced the LPS-mediated infiltration of leukocytes and edema as evidenced by decreased BALF inflammatory cells, myeloperoxidase, and protein. Nicotine also downregulated lung production of pro-inflammatory chemokines and cytokines. These data support the proposal that activation of the cholinergic anti-inflammatory pathway may represent a useful addition to the therapy of acute respiratory distress syndrome.

A mixture of Salacia oblonga extract and IP-PA1 reduces fasting plasma glucose (FPG) and low-density lipoprotein (LDL) cholesterol levels

At present, lifestyle-related diseases are one of the most critical health issues worldwide. It has been reported that lipopolysaccharide derived from a Gram-negative bacteria (IP-PA1) symbiotic with wheat exhibited several advantageous biological effects, such as the reduction of plasma glucose levels in NOD mice and low-density lipoprotein (LDL) levels in WHHL rabbits. In this study, the beneficial effects on plasma glucose and lipids of a tea (SI tea) consisting of IP-PA1 and Salacia (which contains an inhibitor of α-glucosidase) were investigated in the KK-Ay/TaJcl type 2 diabetic model mice and in human subjects with premetabolic syndrome in a double-blind, randomized study. SI tea significantly decreased plasma glucose levels in KK-Ay/TaJcl mice. A clinical trial of SI tea was performed with 41 subjects between the ages of 40 and 69, who belonged either to a high plasma glucose group (HG: FPG 100-125 mg/dl) or to a hyperlipidemia group (HL: TG ≥ 150 mg/dl, or LDL ≥ 120 mg/dl, or HDL < 40 mg/dl). These subjects ingested either Salacia without IP-PA1 (the control) or SI tea. Blood samples were collected at 0, 30, and 60 days after initiating SI tea treatment, and were measured for FPG, HbA1c, TG, LDL, and HDL. These results showed that SI tea reduced FPG and HbA1c more rapidly than the control in the HL group, and also significantly improved LDL and HDL levels in the HG group. Thus, SI tea may be helpful in preventing lifestyle-related diseases.

Activation of the cholinergic antiinflammatory pathway ameliorates obesity-induced inflammation and insulin resistance

Obesity is associated with a chronic inflammatory state characterized by adipose tissue macrophage infiltration and inflammation, which contributes to insulin resistance. The cholinergic antiinflammatory pathway, which acts through the macrophage α7-nicotinic acetylcholine receptor (α7nAChR), is important in innate immunity. Here we show that adipose tissue possesses a functional cholinergic signaling pathway. Activating this pathway by nicotine in genetically obese (db/db) and diet-induced obese mice significantly improves glucose homeostasis and insulin sensitivity without changes of body weight. This is associated with suppressed adipose tissue inflammation. In addition, macrophages from α7nAChR-/- [α7 knockout (α7KO)] mice have elevated proinflammatory cytokine production in response to free fatty acids and TNFα, known agents causing inflammation and insulin resistance. Nicotine significantly suppressed free fatty acid- and TNFα-induced cytokine production in wild type (WT), but not α7KO macrophages. These data suggest that α7nAChR is important in mediating the antiinflammatory effect of nicotine. Indeed, inactivating this pathway in α7KO mice results in significantly increased adipose tissue infiltration of classically activated M1 macrophages and inflammation in α7KO mice than their WT littermates. As a result, α7KO mice exhibit more severely impaired insulin sensitivity than WT mice without changes of body weight. These data suggest that the cholinergic antiinflammatory pathway plays an important role in obesity-induced inflammation and insulin resistance. Targeting this pathway may provide novel therapeutic benefits in the prevention and treatment of obesity-induced inflammation and insulin resistance.

An alpha7 nicotinic acetylcholine receptor-selective agonist reduces weight gain and metabolic changes in a mouse model of diabetes

Type 2 diabetes has become a pervasive public health problem. The etiology of the disease has not been fully defined but appears to involve abnormalities in peripheral and central nervous system pathways, as well as prominent inflammatory components. Because nicotinic acetylcholine receptors (nAChRs) are known to interact with anti-inflammatory pathways and have been implicated in control of appetite and body weight, as well as lipid and energy metabolism, we examined their role in modulating biological parameters associated with the disease. In a model of type 2 diabetes, the homozygous leptin-resistant db/db obese mouse, we measured the effects of a novel alpha7 nAChR-selective agonist [5-methyl-N-[2-(pyridin-3-ylmethyl)-1-azabicyclo[2.2.2]oct-3-yl]thiophene-2-carboxamide (TC-7020)] on body mass, glucose and lipid metabolism, and proinflammatory cytokines. Oral administration of TC-7020 reduced weight gain and food intake, reduced elevated glucose and glycated hemoglobin levels, and lowered elevated plasma levels of triglycerides and the proinflammatory cytokine tumor necrosis factor-alpha. These changes were reversed by the alpha7-selective antagonist methyllycaconitine, confirming the involvement of alpha7 nAChRs. Prevention of weight gain, decreased food intake, and normalization of glucose levels were also blocked by the Janus kinase 2 (JAK2) inhibitor alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG-490), suggesting that these effects involve linkage of alpha7 nAChRs to the JAK2-signal transducer and activator of transcription 3 signaling pathway. The results show that alpha7 nAChRs play a central role in regulating biological parameters associated with diabetes and support the potential of targeting these receptors as a new therapeutic strategy for treatment.

Nicotine and inflammatory neurological disorders

Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. However, there is increasing evidence that smokers have a lower incidence of some inflammatory and neurodegenerative diseases. Nicotine is the main immunosuppressive constituent of cigarette smoke, which inhibits both the innate and adaptive immune responses. Unlike cigarette smoke, nicotine is not yet considered to be a carcinogen and may, in fact, have therapeutic potential as a neuroprotective and anti-inflammatory agent. This review provides a synopsis summarizing the effects of nicotine on the immune system and its (nicotine) influences on various neurological diseases.

Cholinergic stimulation attenuates the IL-4 induced expression of E-selectin and vascular endothelial growth factor by equine pulmonary artery endothelial cells

The endothelium plays a critical role in regulating leukocyte recruitment and migration during inflammation. Recent studies provide evidence that acetylcholine (ACh) and other cholinergic mediators block endothelial cells activation and leukocyte recruitment during inflammation. We thus postulated that the non-neuronal cholinergic system might modulate the recruitment of neutrophils during allergic pulmonary inflammation. In the present study, we examined the effects of cholinergic stimulation on the expression of neutrophil chemokines and adhesion molecules by endothelial cells stimulated by recombinant equine (re) IL-4. Using primary equine pulmonary artery endothelial cells culture and real-time RT-PCR method, we observed that ACh, nicotine, and muscarine inhibit the expression of E-selectin and vascular endothelial growth factor by endothelial cells stimulated by reIL-4. The expression of CXCL-8, a potent neutrophil chemotactic cytokine, remained unaffected however. These findings suggest that the cholinergic anti-inflammatory pathway may modulate pulmonary allergic inflammation and remodeling by the inhibition of selected adhesion molecules and growth factors.

Nicotinic attenuation of central nervous system inflammation and autoimmunity

The expression of nicotinic acetylcholine receptors by neurons, microglia, and astrocytes suggests possibly diverse mechanisms by which natural nicotinic cholinergic signaling and exposure to nicotine could modulate immune responses within the CNS. In this study, we show that nicotine exposure significantly delays and attenuates inflammatory and autoimmune responses to myelin Ags in the mouse experimental autoimmune encephalomyelitis model. In the periphery, nicotine exposure inhibits the proliferation of autoreactive T cells and alters the cytokine profile of helper T cells. In the CNS, nicotine exposure selectively reduces numbers of CD11c(+) dendritic and CD11b(+) infiltrating monocytes and resident microglial cells and down-regulates the expression of MHC class II, CD80, and CD86 molecules on these cells. The results underscore roles of nicotinic acetylcholine receptors and nicotinic cholinergic signaling in inflammatory and immune responses and suggest novel therapeutic options for the treatment of inflammatory and autoimmune disorders, including those that affect the CNS.

Activation of the cholinergic antiinflammatory pathway reduces ricin-induced mortality and organ failure in mice

Exposure to ricin, either by accident through ingestion of castor oil plant seeds or intentionally through its use as a bioweapon, invariably leads to multiple organ damage and death. Currently there is only a vaccine in advanced development to ricin, but no other antidote. Ricin causes systemic inflammation with increased proinflammatory cytokine release and subsequent multiple organ failure, particularly kidney and liver dysfunction. Activation of the cholinergic antiinflammatory pathway, specifically through the alpha7 nicotinic acetylcholine receptor (either indirectly through vagus nerve stimulation or directly through nicotine treatment) reduces proinflammatory gene expression. This activation also increases release of proinflammatory chemokines and cytokines, and has proven effective in a variety of inflammatory diseases. The aim of this study was to investigate whether nicotine treatment protected against ricin toxicity in mice. Male Balb/c mice exposed to ricin had increased serum levels of the inflammatory cytokine tumor necrosis factor-alpha and markers of both kidney (blood urea nitrogen, creatine) and liver (alanine tranaminase) dysfunction, with a subsequent increase in mortality. Nicotine administration 2 h after ricin injection significantly delayed and reduced ricin-induced mortality, an effect coupled with reduced serum levels of tumor necrosis factor-alpha and markers of kidney and liver dysfunction. Both the kidney and liver had markedly increased cellular oxidative stress following ricin exposure, an effect attenuated by nicotine administration. In conclusion, these data demonstrate that in cases of ricin poisoning, activation of the cholinergic antiinflammatory pathway may prove beneficial by reducing organ damage, delaying mortality, and allowing for a greater chance of survival.

Methadone ameliorates multiple-low-dose streptozotocin-induced type 1 diabetes in mice

Type 1 diabetes is an autoimmune disease characterized by inflammation of pancreatic islets and destruction of beta cells by the immune system. Opioids have been shown to modulate a number of immune functions, including T helper 1 (Th1) and T helper 2 (Th2) cytokines. The immunosuppressive effect of long-term administration of opioids has been demonstrated both in animal models and humans. The aim of this study was to determine the effect of methadone, a mu-opioid receptor agonist, on type 1 diabetes. Administration of multiple low doses of streptozotocin (STZ) (MLDS) (40 mg/kg intraperitoneally for 5 consecutive days) to mice resulted in autoimmune diabetes. Mice were treated with methadone (10 mg/kg/day subcutaneously) for 24 days. Blood glucose, insulin and pancreatic cytokine levels were measured. Chronic methadone treatment significantly reduced hyperglycemia and incidence of diabetes, and restored pancreatic insulin secretion in the MLDS model. The protective effect of methadone can be overcome by pretreatment with naltrexone, an opioid receptor antagonist. Also, methadone treatment decreased the proinflammatory Th1 cytokines [interleukin (IL)-1beta, tumor necrosis factor-alpha and interferon-gamma] and increased anti-inflammatory Th2 cytokines (IL-4 and IL-10). Histopathological observations indicated that STZ-mediated destruction of beta cells was attenuated by methadone treatment. It seems that methadone as an opioid agonist may have a protective effect against destruction of beta cells and insulitis in the MLDS model of type 1 diabetes.

Beneficial effect of Corni Fructus, a constituent of Hachimi-jio-gan, on advanced glycation end-product-mediated renal injury in Streptozotocin-treated diabetic rats

Previous investigations have demonstrated that Hachimi-jio-gan, a Chinese prescription consisting of eight crude drugs, has a therapeutic potential in diabetes and diabetic nephropathy, using these model rats. To add to these findings, we performed this study to assess whether one of the crude drugs, Corni Fructus (Cornus officinalis SIEB. et ZUCC.), had an effect on streptozotocin-induced diabetic rats as a major active constituent, compared with an inhibitor of advanced glycation end-product (AGE) formation, aminoguanidine. Diabetic rats were orally administrated Corni Fructus extract (50, 100, 200 mg/kg body weight/d) or aminoguanidine (100 mg/kg body weight/d). Treatment with Corni Fructus for 10 d suppressed hyperglycemia, proteinuria, renal AGE formation, and related protein expressions, i.e., receptor for AGEs, nuclear factor-kappaB, transforming growth factor-beta1, and Nepsilon-(carboxymethyl)lysine, in the same way as with aminoguanidine. However, improvement of renal function, shown via serum creatinine (Cr) and Cr clearance, was superior to aminoguanidine treatment. In conclusion, the present study supported the hypothesis that Corni Fructus plays an important role against diabetic pathogenesis, i.e., reducing glucose toxicities, up-regulating renal function, and consequently ameliorating glycation-associated renal damage; thus, this study may provide a new recognition of crude drugs to clarify the mechanisms of Chinese prescriptions.

Modulation of eosinophil activation in vitro by a nicotinic receptor agonist

Nicotinic receptor agonists decreased the infiltration of eosinophils into the lung and airways in a mouse model of asthma. To better understand the mechanisms implicated in this anti-inflammatory phenomenon, the expression of nicotinic acetylcholine receptors (nAChRs) and the effect of dimethylphenylpiperazinium (DMPP), a nonselective nAChR agonist, on human blood eosinophils were studied. The expression of alpha-3, -4, and -7 nAChR subunits on human blood eosinophils was measured by cell ELISA and immunocytochemistry. mRNA expression for all three subunits was evaluated by quantitative RT-PCR. The effect of DMPP on leukotriene C4 (LTC4) and matrix metalloproteinase-9 (MMP-9) production, eosinophil migration, and intracellular calcium mobilization was measured. The results show that the alpha-3, -4, and -7 nAChR subunits and mRNAs are expressed by blood eosinophils. In vitro treatment of these cells with various concentrations of DMPP reduced platelet-activating factor (PAF)-induced LTC4 production significantly. DMPP (160 microM) decreased eotaxin, and 5-oxo-6,8,11,14-eicosatetranoic acid induced eosinophil migration through Matrigel by 40.9% and 55.5%, respectively. This effect was reversed by the nAChR antagonist mecamylamine. In addition, DMPP reduced MMP-9 release and the inositol 1,4,5-triphosphate-dependent intracellular calcium increase provoked by PAF. Taken together, these results indicate that functional nAChRs are expressed on eosinophils and that nAChR agonists down-regulate eosinophil function in vitro. These anti-inflammatory effects could be of interest in the treatment of allergic asthma.

Dimethyphenylpiperazinium, a nicotinic receptor agonist, downregulates inflammation in monocytes/macrophages through PI3K and PLC chronic activation

Activation of nicotinic acetylcholine receptors (nAChRs) on inflammatory cells induces anti-inflammatory effects. The intracellular mechanisms that regulate this effect are still poorly understood. In neuronal cells, nAChRs are associated with phosphatidylinositol 3-kinase (PI3K). This enzyme, which can activate phospholipase C (PLC), is also present in monocytes. The aim of this study was to assess the role of these proteins in the signaling pathways involved in the anti-inflammatory effect of dimethylphenylpiperazinium (DMPP), a synthetic nAChR agonist, on monocytes and macrophages. The results indicate that PI3K is associated with alpha3, -4, and -5 nAChR subunits in monocytes. The PI3K inhibitors wortmannin and LY294002 abrogated the inhibitory effect of DMPP on LPS-induced TNF release by monocytes. Treatment with DMPP for 24 and 48 h provoked a mild PLC phosphorylation, which was blocked by the nAChR antagonist mecamylamine and reversed by PI3K inhibitors. Treatment of monocytes and alveolar macrophages with DMPP reduced the inositol 1,4,5-trisphosphate (IP3)-dependent intracellular calcium mobilization induced by platelet-activating factor (PAF), an effect that was reversed by mecamylamine in alveolar macrophages. DMPP did not have any effect on PAF receptor expression. DMPP also inhibited the thapsigargin-provoked calcium release, indicating that the endoplasmic reticulum calcium stores might be depleted by treatment with the nAChR agonist. Taken together, these results suggest that PI3K and PLC activation is involved in the anti-inflammatory effect of DMPP. PLC limited, but constant activation could induce, the depletion of intracellular calcium stores, leading to the anti-inflammatory effect of DMPP.