Nicotine inhibits the production of proinflammatory cytokines of mice infected with coxsackievirus B3

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.

Heart rate variability as an indicator of COVID-19 induced myocardial injury: a retrospective cohort study

BACKGROUND

Heart rate variability (HRV) is a valuable indicator of autonomic nervous system integrity and can be a prognostic tool of COVID-19 induced myocardial affection. This study aimed to compare HRV indices between patients who developed myocardial injury and those without myocardial injury in COVID-19 patients who were admitted to intensive care unit (ICU).

METHODS

In this retrospective study, the data from 238 COVID-19 adult patients who were admitted to ICU from April 2020 to June 2021 were collected. The patients were assigned to myocardial injury and non-myocardial injury groups. The main collected data were R-R intervals, standard deviation of NN intervals (SDANN) and the root mean square of successive differences between normal heartbeats (RMSSD) that were measured daily during the first five days of ICU admission.

RESULTS

The R-R intervals, the SDANN and the RMSSD were significantly shorter in the myocardial injury group than the non-myocardial group at the first, t second, third, fourth and the fifth days of ICU admission. There were no significant differences between the myocardial injury and the non-myocardial injury groups with regard the number of patients who needed mechanical ventilation, ICU length of stay and the number of ICU deaths.

CONCLUSIONS

From the results of this retrospective study, we concluded that the indices of HRV were greatly affected in COVID-19 patients who developed myocardial injury.

Drug Repositioning for Hand, Foot, and Mouth Disease

Hand, foot, and mouth disease (HFMD) is a highly contagious disease in children caused by a group of enteroviruses. HFMD currently presents a major threat to infants and young children because of a lack of antiviral drugs in clinical practice. Drug repositioning is an attractive drug discovery strategy aimed at identifying and developing new drugs for diseases. Notably, repositioning of well-characterized therapeutics, including either approved or investigational drugs, is becoming a potential strategy to identify new treatments for virus infections. Various types of drugs, including antibacterial, cardiovascular, and anticancer agents, have been studied in relation to their therapeutic potential to treat HFMD. In this review, we summarize the major outbreaks of HFMD and the progress in drug repositioning to treat this disease. We also discuss the structural features and mode of action of these repositioned drugs and highlight the opportunities and challenges of drug repositioning for HFMD.

Advances in cell death mechanisms involved in viral myocarditis

Viral myocarditis is an acute inflammatory disease of the myocardium. Although many etiopathogenic factors exist, coxsackievirus B3 is a the leading cause of viral myocarditis. Abnormal cardiomyocyte death is the underlying problem for most cardiovascular diseases and fatalities. Various types of cell death occur and are regulated to varying degrees. In this review, we discuss the different cell death mechanisms in viral myocarditis and the potential interactions between them. We also explore the role and mechanism of cardiomyocyte death with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Exploring the mechanisms may help in the early identification and the development of effective treatments, thus improving the quality of life of patients with viral myocarditis. We believe that the inhibition of cardiomyocyte death has immense therapeutic potential in increasing the longevity and health of the heart.

Nicotine in Inflammatory Diseases: Anti-Inflammatory and Pro-Inflammatory Effects

As an anti-inflammatory alkaloid, nicotine plays dual roles in treating diseases. Here we reviewed the anti-inflammatory and pro-inflammatory effects of nicotine on inflammatory diseases, including inflammatory bowel disease, arthritis, multiple sclerosis, sepsis, endotoxemia, myocarditis, oral/skin/muscle inflammation, etc., mainly concerning the administration methods, different models, therapeutic concentration and duration, and relevant organs and tissues. According to the data analysis from recent studies in the past 20 years, nicotine exerts much more anti-inflammatory effects than pro-inflammatory ones, especially in ulcerative colitis, arthritis, sepsis, and endotoxemia. On the other hand, in oral inflammation, nicotine promotes and aggravates some diseases such as periodontitis and gingivitis, especially when there are harmful microorganisms in the oral cavity. We also carefully analyzed the nicotine dosage to determine its safe and effective range. Furthermore, we summarized the molecular mechanism of nicotine in these inflammatory diseases through regulating immune cells, immune factors, and the vagus and acetylcholinergic anti-inflammatory pathways. By balancing the “beneficial” and “harmful” effects of nicotine, it is meaningful to explore the effective medical value of nicotine and open up new horizons for remedying acute and chronic inflammation in humans.

Cholinergic modulation of the immune system - A novel therapeutic target for myocardial inflammation

The immune system and the nervous system depend on each other for their fine tuning and working, thus cooperating to maintain physiological homeostasis and prevent infections. The cholinergic system regulates the mobilization, differentiation, secretion, and antigen presentation of adaptive and innate immune cells mainly through α7 nicotinic acetylcholine receptors (α7nAChRs). The neuro-immune interactions are established and maintained by the following mechanisms: colocalization of immune and neuronal cells at defined anatomical sites, expression of the non-neuronal cholinergic system by immune cells, and the acetylcholine receptor-mediated activation of intracellular signaling pathways. Based on these immunological mechanisms, the protective effects of cholinergic system in animal models of diseases were summarized in this paper, such as myocardial infarction/ischemia-reperfusion, viral myocarditis, and endotoxin-induced myocardial damage. In addition to maintaining hemodynamic stability and improving the energy metabolism of the heart, both non-neuronal acetylcholine and neuronal acetylcholine in the heart can alleviate myocardial inflammation and remodeling to exert a significant cardioprotective effect. The new findings on the role of cholinergic agonists and vagus nerve stimulation in immune regulation are updated, so as to develop improved approaches to treat inflammatory heart disease.

Vagus nerve plays a pivotal role in CD4+ T cell differentiation during CVB3-induced murine acute myocarditis

Abnormalities in CD4⁺ T cell (Th cell) differentiation play an important role in the pathogenesis of viral myocarditis (VMC). Our previous studies demonstrated that activation of the cholinergic anti-inflammatory pathway (CAP) alleviated the inflammatory response. In addition, we observed that right cervical vagotomy aggravates VMC by inhibiting CAP. However, the vagus nerve’s effect on differentiation of CD4⁺ T cells has not been studied in VMC mice to date. In this study, we investigated the effects of cervical vagotomy and the α7nAChR agonist pnu282987 on CD4⁺ T cell differentiation in a murine myocarditis model (BALB/c) infected with coxsackievirus B3 (CVB3). Splenic CD4⁺ T cells from CVB3-induced mice obtained and cultured to investigate the potential mechanism of CD4⁺ T cell differentiation. Each Th cell subset was analyzed by flow cytometry. Our results showed that right cervical vagotomy increased proportions of Th1 and Th17 cells and decreased proportions of Th2 and Treg cells in the spleen. Vagotomy-induced upregulation of T-bet, Ror-γ, IFN-γ, and IL-17 expression while downregulating the expression of Gata3, Foxp3, and IL-4 in the heart. In addition, we observed upregulated levels of proinflammatory cytokines, aggravated myocardial lesions and cellular infiltration, and worsened cardiac function in VMC mice. Pnu282987 administration reversed these outcomes. Furthermore, vagotomy inhibited JAK2-STAT3 activation and enhanced NF-κB activation in splenic CD4⁺ T cells. The CD4⁺ T cell differentiation was related to JAK2-STAT3 and NF-κB signal pathways. In conclusion, vagus nerve modulates the inflammatory response by regulating CD4⁺ T cell differentiation in response to VMC.

Effect of nicotine on placental inflammation and apoptosis in preeclampsia-like model

AIMS

Placental tissues from patients with preeclampsia (PE) and in the lipopolysaccharide (LPS)-induced PE-like model were used to investigate the implication of placental inflammation and apoptosis in PE. Whether the beneficial effects of nicotine are related to inhibition of placental inflammation and apoptosis in the PE-like model were investigated.

MAIN METHODS

Placental apoptosis was detected in PE patients and the PE-like rat model by TUNEL staining. Changes in the number of CD68⁺ macrophages in placental tissues from PE patients were detected by immunofluorescent staining. The mRNA expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin (IL-1β), MCP-1, and proteins involved in extrinsic or intrinsic apoptosis signaling in the PE-like model was determined by qRT-PCR; immunofluorescent staining was used to detect the expression of TNF-α receptor (TNFR1), MCP-1 and apoptosis-related proteins.

KEY FINDINGS

Placental apoptosis was increased in both PE patients and the PE-like model, more macrophages infiltrated into placenta in PE patients. A significant upregulation in mRNA expression of TNF-α, IL-1β, MCP-1, and caspase 3, caspase 8, caspase 9 was found in the PE-like rats compared to the control animals, the immunoreactivity of placental MCP-1, TNFR1, and apoptosis-related proteins (caspase 3, caspase 8, caspase 9, Bax) was also enhanced; nicotine treatment significantly reversed those changes.

SIGNIFICANCE

Our data suggests that the protective effects of nicotine are associated with inhibiting placenta inflammation and apoptosis, and nicotine might be a potentially therapeutic candidate for preventing preeclampsia.

Melatonin: Roles in influenza, Covid-19, and other viral infections

There is a growing appreciation that the regulation of the melatonergic pathways, both pineal and systemic, may be an important aspect in how viruses drive the cellular changes that underpin their control of cellular function. We review the melatonergic pathway role in viral infections, emphasizing influenza and covid-19 infections. Viral, or preexistent, suppression of pineal melatonin disinhibits neutrophil attraction, thereby contributing to an initial "cytokine storm", as well as the regulation of other immune cells. Melatonin induces the circadian gene, Bmal1, which disinhibits the pyruvate dehydrogenase complex (PDC), countering viral inhibition of Bmal1/PDC. PDC drives mitochondrial conversion of pyruvate to acetyl-coenzyme A (acetyl-CoA), thereby increasing the tricarboxylic acid cycle, oxidative phosphorylation, and ATP production. Pineal melatonin suppression attenuates this, preventing the circadian "resetting" of mitochondrial metabolism. This is especially relevant in immune cells, where shifting metabolism from glycolytic to oxidative phosphorylation, switches cells from reactive to quiescent phenotypes. Acetyl-CoA is a necessary cosubstrate for arylalkylamine N-acetyltransferase, providing an acetyl group to serotonin, and thereby initiating the melatonergic pathway. Consequently, pineal melatonin regulates mitochondrial melatonin and immune cell phenotype. Virus- and cytokine-storm-driven control of the pineal and mitochondrial melatonergic pathway therefore regulates immune responses. Virus-and cytokine storm-driven changes also increase gut permeability and dysbiosis, thereby suppressing levels of the short-chain fatty acid, butyrate, and increasing circulating lipopolysaccharide (LPS). The alterations in butyrate and LPS can promote viral replication and host symptom severity via impacts on the melatonergic pathway. Focussing on immune regulators has treatment implications for covid-19 and other viral infections.

The cholinergic anti-inflammatory pathway ameliorates acute viral myocarditis in mice by regulating CD4+ T cell differentiation

Many studies have found that abnormalities in the proportion and differentiation of CD4⁺ T cells (Th cells) are closely related to the pathogenesis of viral myocarditis (VMC). Our previous research indicates that the cholinergic anti-inflammatory pathway (CAP) attenuates the inflammatory response of VMC and downregulates the expression of cytokines in Th1 and Th17 cells. This suggests that the cholinergic anti-inflammatory pathway likely attenuates the inflammatory response in VMC by altering Th cell differentiation. The aim of this study is to investigate the effect of CAP on CD4⁺ T cell differentiation in VMC mice. CD4⁺ T cells in the spleen of VMC mice were obtained and cultured in the presence of nicotine or methyllycaconitine (MLA). Cells were harvested and analyzed for the percentage of each Th cell subset by flow cytometry and transcription factor release by Western blot. Then, we detected the effect of CAP on the differentiation of Th cells in vivo. Nicotine or MLA was used to activate and block CAP, respectively, in acute virus-induced myocarditis. Nicotine treatment increased the proportion of Th2 and Treg cells, decreased the proportion of Th1 and Th17 cells in the spleen, reduced the level of proinflammatory cytokines, and attenuated the severity of myocardium lesions and cellular infiltration in viral myocarditis. MLA administration had the opposite effect. Our result demonstrated that CAP effectively protects the myocardium from virus infection, which may be attributable to the regulation of Th cell differentiation.

Preoperative smoking history is associated with decreased risk of early postoperative cognitive dysfunction in patients of advanced age after noncardiac surgery: a prospective observational cohort study

Objective

Prevention of postoperative cognitive dysfunction (POCD) in patients of advanced age remains unclear. Studies have shown that the cholinergic anti-inflammatory pathway contributes to a decreased risk of POCD and that nicotine stimulates the cholinergic anti-inflammatory pathway. We investigated whether patients of advanced age with a preoperative smoking history have a decreased risk of POCD.

Methods

In total, 382 patients (190 smokers, 192 nonsmokers) aged ≥60 years who underwent major noncardiac surgery were enrolled. Cognitive function was assessed, and multivariate logistic regression analyses were performed to identify risk factors.

Results

On postoperative days 5 and 7, 111 (29.05%) and 90 (23.56%) patients exhibited POCD, respectively. A preoperative smoking history was significantly correlated with a decreased risk of POCD. A high serum tumor necrosis factor-α (TNF-α) level on the operative day was significantly associated with an increased risk of POCD. Early POCD was significantly associated with the sufentanil dosage, age, and education level. The hospital stay in patients with and without POCD was 10.54 ± 2.03 and 8.33 ± 1.58 days, respectively.

Conclusion

A preoperative smoking history was associated with a decreased risk of early POCD, and a high serum TNF-α level was significantly associated with an increased risk of POCD.

Nicotine and sleep deprivation: impact on pain sensitivity and immune modulation in rats

Repeated nicotine administration has been associated with increased paradoxical sleep in rats and antinociceptive properties, whereas paradoxical sleep deprivation (PSD) elicits pronociceptive and inflammatory responses. Thus, we aimed to evaluate the effect of repeated nicotine administration and its withdrawal combined with PSD on pain sensitivity and inflammatory markers. Sixty adult male Wistar rats were subjected to repeated injections of saline (SAL) or nicotine (NIC) for 12 days or 7 days of nicotine followed by acute mecamylamine administration on day 8 to precipitate nicotine abstinence (ABST). On day 9, the animals were submitted to PSD for 72 h or remained in control condition (CTRL); on day 12, thermal pain threshold was assessed by the hot plate test. PSD significantly decreased the latency to paw withdrawal in all groups compared to their respective controls. ABST-PSD animals presented higher levels of interleukin (IL)-6 compared to all groups, except ABST-CTRL. After adjustment for weight loss, IL-6, IL-4 and tumor necrosis factor alpha, ABST-PSD was associated with the lowest pain threshold. Nicotine and IL-4 levels were predictors of higher pain threshold. Hyperalgesia induced by PSD prevailed over the antinociceptive action of nicotine, while the association between PSD and ABST synergistically increased IL-6 concentrations and decreased pain threshold.

Protective Effect of Nicotine on Sepsis-Induced Oxidative Multiorgan Damage: Role of Neutrophils

Introduction

Despite its adverse health consequences, tobacco smoking is associated with lower incidence of several neurodegenerative and inflammatory diseases. The present study is aimed to show the effects of nicotine, major tobacco constituent, on five organs targeted by sepsis.

Methods

Male Wistar albino rats received tap water with (5mg/kg) or without nicotine for 14 days. Under ketamine anesthesia, sepsis (n = 50) was induced by ligation and puncture of the cecum, while sham group (n = 8) had only laparotomy. In other rats, nicotine drink was withdrawn for 5 days before sepsis induction, while in acute nicotine group, rats were injected with nicotine (30mg/kg, i.p.) before sepsis, but had no oral intake. Rats were decapitated 24 hours after surgery to obtain lung, liver, ileum, heart, and kidney tissues to determine malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) activities. Data were analyzed by one-way analysis of variance and Tukey multiple comparison tests or Student's t test.

Results

Chronic nicotine administration or its withdrawal reduced lipid peroxidation and MPO activity and prevented GSH depletion with some varying results in different target tissues. Nicotine injection prior to sepsis depressed MPO activity in all tissues and reduced MDA levels except for the lung, while GSH levels were elevated only in the hepatic and ileal tissues. Histologically observed injury was ameliorated by all nicotine treatments at varying degrees.

Conclusions

The findings of the present study indicate that long-term nicotine administration reduces sepsis-induced oxidative damage in several tissues, which appears to involve inhibition of neutrophil activity in the inflamed tissues.

Implications

Nicotine administration or its withdrawal reduced lipid peroxidation and neutrophil content and prevented GSH depletion with some varying results in different target tissues. A single injection prior to sepsis induction depressed MPO activity in all the tissues and reduced all tissue MDA levels except for the lung. When nicotine was withdrawn for 5 days, its inhibitory effect on MPO activity was still present in all the tissues except for the liver. Microscopically an improved inflammatory response was observed in all the tissues of rats that have received different nicotine pretreatment regimens.

Right Cervical Vagotomy Aggravates Viral Myocarditis in Mice Via the Cholinergic Anti-inflammatory Pathway

The autonomic nervous system dysfunction with increased sympathetic activity and withdrawal of vagal activity may play an important role in the pathogenesis of viral myocarditis. The vagus nerve can modulate the immune response and control inflammation through a ‘cholinergic anti-inflammatory pathway’ dependent on the α7-nicotinic acetylcholine receptor (α7nAChR). Although the role of β-adrenergic stimulation on viral myocarditis has been investigated in our pervious studies, the direct effect of vagal tone in this setting has not been yet studied. Therefore, in the present study, we investigated the effects of cervical vagotomy in a murine model of viral myocarditis. In a coxsackievirus B3 murine myocarditis model (Balb/c), effects of right cervical vagotomy and nAChR agonist nicotine on echocardiography, myocardial histopathology, viral RNA, and proinflammatory cytokine levels were studied. We found that right cervical vagotomy inhibited the cholinergic anti-inflammatory pathway, aggravated myocardial lesions, up-regulated the expression of TNF-α, IL-1β, and IL-6, and worsened the impaired left ventricular function in murine viral myocarditis, and these changes were reversed by co-treatment with nicotine by activating the cholinergic anti-inflammatory pathway. These results indicate that vagal nerve plays an important role in mediating the anti-inflammatory effect in viral myocarditis, and that cholinergic stimulation with nicotine also plays its peripheral anti-inflammatory role relying on α7nAChR, without requirement for the integrity of vagal nerve in the model. The findings suggest that vagus nerve stimulation mediated inhibition of the inflammatory processes likely provide important benefits in myocarditis treatment.

The Protective Effects of Ivabradine in Preventing Progression from Viral Myocarditis to Dilated Cardiomyopathy

To study the beneficial effects of ivabradine in dilated cardiomyopathy (DCM) mice, which evolved from coxsackievirus B3-induced chronic viral myocarditis. Four-to-five-week-old male balb/c mice were inoculated intraperitoneally with coxsackievirus B3 (Strain Nancy) on days 1, 14, and 28. The day of the first virus inoculation was defined as day 1. Thirty-five days later, the surviving chronic viral myocarditis mice were divided randomly into two groups, a treatment group and an untreated group. Ivabradine was administered by gavage for 30 consecutive days in the treatment group, and the untreated group was administered normal saline. Masson’s trichrome stain was used to evaluate the fibrosis degree in myocardial tissue. The expression levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), collagen I, collagen III and p38-MAPK signaling pathway proteins were detected by Western blot. Electrocardiogram was used to investigate the heart rate and rhythm. The thickness of the ventricular septum and left ventricular posterior wall, left ventricular end diastolic dimension, left ventricular end systolic dimension, left ventricular ejection fractions and fractional shortening were studied by echocardiography. Compared with the untreated chronic viral myocarditis mice, ivabradine significantly increased the survival rate, attenuated the myocardial lesions and fibrosis, improved the impairment of the left ventricular function, diminished the heart dimension, decreased the production of collagen I and collagen III, reduced the expression of the proinflammatory cytokines TNF-α, IL-1β, and IL-6, and lowered the production of phospho-p38 MAPK. The findings indicate the therapeutic effect of ivabradine in preventing the progression from viral myocarditis to DCM in mice with chronic viral myocarditis induced by coxsackievirus B3, is associated with inhibition of the p38 MAPK pathway, downregulated inflammatory responses and decreased collagen expression. Ivabradine appears a promising approach for the treatment of patients with viral myocarditis.