Effect of nicotine on rectal mucus and mucosal eicosanoids

Independent predictors of 90-day readmission in patients with inflammatory bowel disease: a nationwide retrospective study

BACKGROUND AND AIMS

There is a paucity of literature that comprehensively investigates risk factors for inflammatory bowel disease (IBD) readmissions on a national scale. In this study, we look to identify independent risk factors for readmission, including psychosocial factors, in patients admitted with a primary diagnosis of ulcerative colitis (UC) or Crohn's disease (CD).

METHODS

We performed a retrospective cohort study using data from the Nationwide Readmissions Database. We identified cohorts of adult patients (n = 28 473) who required inpatient admission for UC or CD in the United States in the year 2020. Multivariate logistic regression models controlling for confounding variables were used to identify independent predictors of 90-day readmission.

RESULTS

Patients were identified who required hospitalization for UC (n = 11 476) and CD (n = 16 997). In patients with UC, younger age, male sex, and transfusion requirement during index hospitalization were all independently predictive of increased 90-day readmission (all P < .05). Psychosocial factors predictive of readmission include alcohol use disorder, drug abuse, and poverty (all P < .05). In patients with CD, younger age and chronic pain were both predictive of increased readmissions (all P < .05). Psychosocial factors predictive of readmission include lower income quartile, uninsured status, depression, drug abuse, nicotine dependence, and opioid use disorder (all P < .05).

CONCLUSIONS

This study identifies several risk factors for readmission in patients with IBD, many of which are potentially modifiable psychosocial factors. Closer follow-up, possibly via virtual modalities, as well as alternative treatment strategies, should be considered in patients with IBD at higher risk of readmission.

Current Approach to Risk Factors and Biomarkers of Intestinal Fibrosis in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), especially Crohn's disease (CD), characterized by a chronic inflammatory process and progressive intestinal tissue damage, leads to the unrestrained proliferation of mesenchymal cells and the development of bowel strictures. Complications induced by fibrosis are related to high rates of morbidity and mortality and lead to a substantial number of hospitalizations and surgical procedures, generating high healthcare costs. The development of easily obtained, reliable fibrogenesis biomarkers is essential to provide an important complementary tool to existing diagnostic and prognostic methods in IBD management, guiding decisions on the intensification of pharmacotherapy, proceeding to surgical methods of treatment and monitoring the efficacy of anti-fibrotic therapy in the future. The most promising potential markers of fibrosis include cartilage oligomeric matrix protein (COMP), hepatocyte growth factor activator (HGFA), and fibronectin isoform- extra domain A (ED-A), as well as antibodies against granulocyte macrophage colony-stimulating factor (GM-CSF Ab), cathelicidin (LL-37), or circulatory miRNAs: miR-19a-3p and miR-19b-3p. This review summarizes the role of genetic predisposition, and risk factors and serological markers potentially contributing to the pathophysiology of fibrotic strictures in the course of IBD.

Long-term exposure to air pollution and risk of incident inflammatory bowel disease among middle and old aged adults

BACKGROUND

Epidemiological evidence regarding the associations between long-term exposure to air pollution and risk of incident inflammatory bowel disease (IBD) is scant.

OBJECTIVES

We examined the associations of various specific air pollutants with the risk of incident ulcerative colitis and Crohn's disease, two subtypes of IBD, among middle and old aged adults in the UK. We also explored potential susceptible subgroups.

METHODS

We used data from the UK Biobank study. Information on air pollution, including PM_2.5, PM_2.5-10, PM₁₀ as well as NO₂ and NO_x were estimated using the Land Use Regression model. Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

After a median follow-up of 11.7 years, 1872 incident ulcerative colitis and 865 incident Crohn's disease cases were identified among 455,210 IBD-free participants. HRs (95% CIs) of ulcerative colitis associated with each 1 interquartile range (IQR) increase in PM_2.5, PM_2.5-10, PM₁₀, NO₂, and NO_x were 1.06 (1.01, 1.12), 1.03 (0.99, 1.08), 1.09 (1.03, 1.16), 1.12 (1.07, 1.19), and 1.07 (1.02, 1.12), respectively. The associations between all the air pollutants and risk of Crohn's disease were null. Smoking status and sex appeared to respectively modify the associations between some air pollutants and risk of ulcerative colitis and Crohn's disease.

CONCLUSION

Long-term exposure to various air pollutants was associated with the risk of incident ulcerative colitis but not Crohn's disease, highlighting the importance of developing environmental health strategy to reduce the burden of ulcerative colitis.

Ebselen prevents cigarette smoke-induced gastrointestinal dysfunction in mice

Gastrointestinal (GI) dysfunction is a common comorbidity of chronic obstructive pulmonary disease (COPD) for which a major cause is cigarette smoking (CS). The underlying mechanisms and precise effects of CS on gut contractility, however, are not fully characterised. Therefore, the aim of the present study was to investigate whether CS impacts GI function and structure in a mouse model of CS-induced COPD. We also aimed to investigate GI function in the presence of ebselen, an antioxidant that has shown beneficial effects on lung inflammation resulting from CS exposure. Mice were exposed to CS for 2 or 6 months. GI structure was analysed by histology and immunofluorescence. After 2 months of CS exposure, ex vivo gut motility was analysed using video-imaging techniques to examine changes in colonic migrating motor complexes (CMMCs). CS decreased colon length in mice. Mice exposed to CS for 2 months had a higher frequency of CMMCs and a reduced resting colonic diameter but no change in enteric neuron numbers. Ten days cessation after 2 months CS reversed CMMC frequency changes but not the reduced colonic diameter phenotype. Ebselen treatment reversed the CS-induced reduction in colonic diameter. After 6 months CS, the number of myenteric nitric-oxide producing neurons was significantly reduced. This is the first evidence of colonic dysmotility in a mouse model of CS-induced COPD. Dysmotility after 2 months CS is not due to altered neuron numbers; however, prolonged CS-exposure significantly reduced enteric neuron numbers in mice. Further research is needed to assess potential therapeutic applications of ebselen in GI dysfunction in COPD.

Modulation of Gut Microbiota in Korean Navy Trainees following a Healthy Lifestyle Change

Environmental factors can influence the composition of gut microbiota, but understanding the combined effect of lifestyle factors on adult gut microbiota is limited. Here, we investigated whether changes in the modifiable lifestyle factors, such as cigarette smoking, alcohol consumption, sleep duration, physical exercise, and body mass index affected the gut microbiota of Korean navy trainees. The navy trainees were instructed to stop smoking and alcohol consumption and follow a sleep schedule and physical exercise regime for eight weeks. For comparison, healthy Korean civilians, who had no significant change in lifestyles for eight weeks were included in this study. A total of 208 fecal samples were collected from navy trainees (n = 66) and civilians (n = 38) at baseline and week eight. Gut flora was assessed by sequencing the highly variable region of the 16S rRNA gene. The α-and β -diversity of gut flora of both the test and control groups were not significantly changed after eight weeks. However, there was a significant difference among individuals. Smoking had a significant impact in altering α-diversity. Our study showed that a healthy lifestyle, particularly cessation of smoking, even in short periods, can affect the gut microbiome by enhancing the abundance of beneficial taxa and reducing that of harmful taxa.

Association between Cigarette Smoking Status and Composition of Gut Microbiota: Population-Based Cross-Sectional Study

There have been few large-scale studies on the relationship between smoking and gut microbiota. We investigated the relationship between smoking status and the composition of gut microbiota. This was a population-based cross-sectional study using Healthcare Screening Center cohort data. A total of 758 men were selected and divided into three groups: never (n = 288), former (n = 267), and current smokers (n = 203). Among the three groups, there was no difference in alpha diversity, however, Jaccard-based beta diversity showed significant difference (p = 0.015). Pairwise permutational multivariate analysis of variance (PERMANOVA) tests between never and former smokers did not show a difference; however, there was significant difference between never and current smokers (p = 0.017) and between former and current smokers (p = 0.011). Weighted UniFrac-based beta diversity also showed significant difference among the three groups (p = 0.038), and pairwise PERMANOVA analysis of never and current smokers showed significant difference (p = 0.01). In the analysis of bacterial composition, current smokers had an increased proportion of the phylum Bacteroidetes with decreased Firmicutes and Proteobacteria compared with never smokers, whereas there were no differences between former and never smokers. In conclusion, gut microbiota composition of current smokers was significantly different from that of never smokers. Additionally, there was no difference in gut microbiota composition between never and former smokers.

The interaction between smoking, alcohol and the gut microbiome

The gastrointestinal microbiome is a complex echosystem that establishes a symbiotic, mutually beneficial relation with the host, being rather stable in health, but affected by age, drugs, diet, alcohol, and smoking. Alcohol and smoking contribute to changes in the stomach and affect H pylori-related disorders including the risk of gastric cancer. In the small intestine and in the colon alcohol causes depletion of bacteria with anti-inflammatory activity, eventually resulting in intestinal damage with "leaky gut". These changes contribute to hepatic damage in both alcoholic and non-alcoholic liver disease and have been associated with other disorders. Lactobacillus GG and A. muciniphila exert a protective effect in this setting. Smoking leads to modifications of the gut microbiome linked with a protective effect toward ulcerative colitis and deleterious for Crohn's disease. The exact cause-effect relation between alcohol and smoking and changes of the gastrointestinal microbiome needs further exploration with high throughput methodologies, and controlled studies are necessary to define the role of microbiome modulation on the immune response and systemic activation of pro-inflammatory pathways.

Hydrodynamics of defecation

Animals discharge feces within a range of sizes and shapes. Such variation has long been used to track animals as well as to diagnose illnesses in both humans and animals. However, the physics by which feces are discharged remain poorly understood. In this combined experimental and theoretical study, we investigate the defecation of mammals from cats to elephants using the dimensions of large intestines and feces, videography at Zoo Atlanta, cone-on-plate rheological measurements of feces and mucus, and a mathematical model of defecation. The diameter of feces is comparable to that of the rectum, but the length is double that of the rectum, indicating that not only the rectum but also the colon is a storage facility for feces. Despite the length of rectum ranging from 4 to 40 cm, mammals from cats to elephants defecate within a nearly constant duration of 12 ± 7 seconds (N = 23). We rationalize this surprising trend by our mathematical model, which shows that feces slide along the large intestine by a layer of mucus, similar to a sled sliding down a chute. Larger animals have not only more feces but also thicker mucus layers, which facilitate their ejection. Our model accounts for the shorter and longer defecation times associated with diarrhea and constipation, respectively. This study may support clinicians use of non-invasive procedures such as defecation time in the diagnoses of ailments of the digestive system.

Anti-inflammatory effects of the nicotinergic peptides SLURP-1 and SLURP-2 on human intestinal epithelial cells and immunocytes

A search for novel and more efficient therapeutic modalities of inflammatory bowel disease (IBD) is one of the most important tasks of contemporary medicine. The anti-inflammatory action of nicotine in IBD might be therapeutic, but its toxicity due to off-target and nonreceptor effects limited its use and prompted a search for nontoxic nicotinergic drugs. We tested the hypothesis that SLURP-1 and -2—the physiological nicotinergic substances produced by the human intestinal epithelial cells (IEC) and immunocytes—can mimic the anti-inflammatory effects of nicotine. We used human CCL-241 enterocytes, CCL-248 colonocytes, CCRF-CEM T-cells, and U937 macrophages. SLURP-1 diminished the TLR9-dependent secretion of IL-8 by CCL-241, and IFNγ-induced upregulation of ICAM-1 in both IEC types. rSLURP-2 inhibited IL-1β-induced secretion of IL-6 and TLR4- and TLR9-dependent induction of CXCL10 and IL-8, respectively, in CCL-241. rSLURP-1 decreased production of TNFα by T-cells, downregulated IL-1β and IL-6 secretion by macrophages, and moderately upregulated IL-10 production by both types of immunocytes. SLURP-2 downregulated TNFα and IFNγR in T-cells and reduced IL-6 production by macrophages. Combining both SLURPs amplified their anti-inflammatory effects. Learning the pharmacology of SLURP-1 and -2 actions on enterocytes, colonocytes, T cells, and macrophages may help develop novel effective treatments of IBD.

The effect of smoking on intestinal inflammation: what can be learned from animal models?

Epidemiological evidence demonstrates that smoking is the most important environmental risk factor in Crohn's disease while it positively interferes with the disease course of ulcerative colitis. However, the underlying mechanisms through which smoking exerts this divergent effect and affects pathogenesis of inflammatory bowel disease are largely unknown. Animal smoke models are good models to investigate the impact of cigarette smoke on intestinal physiology and inflammation. They enable one to explore the interaction of smoke components and the gut on cellular and molecular level, clarifying how smoking interferes with normal gut function and with disease course in inflammatory conditions. This review describes the currently used animal models for studying the impact of cigarette smoke on the intestinal tract. We first discuss the different methods for simulation of smoking. Furthermore, we focus on the effect of smoke exposure on normal gut physiology and immunology, on experimental (entero)colitis, and on inflammation-induced neoplasia. Based on this current knowledge, a hypothesis is formulated about the mechanisms through which cigarette smoke interferes with the gut in normal and pathological conditions.

Cigarette smoking alters epithelial apoptosis and immune composition in murine GALT

Smokers have a twofold increased risk to develop Crohn's disease (CD). However, little is known about the mechanisms through which smoking affects CD pathogenesis. Especially Crohn's ileitis is negatively influenced by smoking. Interestingly, the ileum and, more in particular, the Peyer's patches in the terminal ileum are also the sites where the first CD lesions are found. Several chemokines are implicated in the pathogenesis, among which is the CCL20-CCR6 pathway. Here, we studied the gut-associated lymphoid tissue in C57BL/6 wild-type mice and in CCR6-deficient mice after exposure to air or cigarette smoke for 24 weeks. Apoptotic index of the follicle-associated epithelium overlying the Peyer's patches was evaluated. We found that chronic smoke exposure induced apoptosis in the follicle-associated epithelium. Furthermore, immune cell numbers and differentiation along with chemokine expression were determined in Peyer's patches. Important changes in immune cell composition were observed: total dendritic cells, CD4+ T cells (including regulatory T cells) and CD8+ T cells increased significantly after smoke exposure. The CD11b+ dendritic cell subset almost doubled. Interestingly, these changes were accompanied by an upregulated mRNA expression of the chemokines CCL9 and CCL20. However, no differences in the increase of dendritic cells were observed between wild-type and CCR6-deficient mice. Our results show that cigarette smoke exposure increases apoptosis in the follicle-associated epithelium and is associated with immune cell accumulation in Peyer's patches.

Nicotine suppresses inflammatory factors in HBE16 airway epithelial cells after exposure to cigarette smoke extract and lipopolysaccharide

Cigarette smoke is a major cause of chronic inflammatory pulmonary disease, leading to inflammation, mucin (MUC) production, tissue damage, and remodeling. It is also well known that the major addictive component of cigarette smoke is nicotine. This study focused on the role of nicotine in the development of inflammatory pulmonary disease induced by cigarette smoke. HBE16 human airway epithelial cells were treated with serial dilutions of cigarette smoke chloroform extract (CE), lipopolysaccharide (LPS), and nicotine. The release of MUC5AC, tumor necrosis factor (TNF)-α, interleukin (IL)-8, and IL-6 protein were assayed by enzyme-linked immunosorbent assay. The MUC5AC protein also was observed by immunofluorescence. The expression of MUC5AC, TNF-α, IL-8, and IL-6 mRNA were detected by real-time polymerase chain reaction. We found that the mRNA of the proinflammatory mediators TNF-α, IL-8, and IL-6, as well as MUC5AC was highly expressed after CE and LPS stimulation. Nicotine did not cause an excessive expression of TNF-α, IL-8, and IL-6, nor did it affect protein production from the MUC5AC gene. Nicotine not only failed to stimulate production of TNF-α, IL-8, and IL-6, but its presence was shown to suppress the activation resulting from exposure to CE and LPS (P < 0.05). Preincubation with nicotine also would reduce the level of MUC5AC protein in culture supernatants of CE- and LPS-treated cells. However, mRNA expression of MUC5AC showed no significant change in nicotine-treated cells when compared with normal control cells. This distinctive pattern implies that nicotine may have potential to suppress airway inflammation and maintain the mucus over retention in airway secretory cells to some extent, thus forming a balance between mucus hyperproduction and hypersecretion in airways exposed to smoking and LPS.

Smoking and inflammatory bowel diseases: what in smoking alters the course?

Epidemiological studies provide strong evidence to confirm the correlation between cigarette smoking and inflammatory bowel diseases. This relationship is proved to be positive in Crohn's disease and negative in ulcerative colitis. What in smoking alters the course of inflammatory bowel diseases is still a mystery. Different smoking parts have different and may be opponent actions. Smoking has dual effects. Some of its activities are, sometimes, constructive as they are working in an antagonistic manner to the mechanism of the disease, such as reducing rectal blood flow and accordingly less recruitments of inflammatory mediators to the area of inflammation, enhancement of mucosal production, and consequently, strengthening the membranes, and inhibition of pro-inflammatory mediators' liberation and activity in subjects with ulcerative colitis. Yet the outcome of smoking actions may be affected by the existence of other cofactors. Odd factors, such as shortage of zinc in subjects with Crohn's disease, may facilitate liberation of pro-inflammatory mediators and their activities and accordingly exacerbates symptoms.

Is nicotine a key player or spectator in the induction and progression of cardiovascular disorders?

Cigarette smoking is common in societies worldwide and a growing body of evidence suggests that chronic cigarette smoking may affect the structure and function of cardiovascular system. The chronic exposure to high levels of nicotine, a major component of cigarette smoking, has been observed to play a pathogenic role in the induction and progression of cardiovascular disorders including cardiomyopathy and peripheral vascular disease. Nicotine alters the function of vascular endothelium, initiates the adhesion cascade and stimulates the vascular inflammatory events to induce atherosclerosis and hypertension. Moreover, nicotine has been noted to induce direct coronary spasm and ischemia, which develop coronary artery disease and myocardial infarction. In addition, nicotine stimulates the excessive release of impulses from sinoatrial node that may account for the induction of cardiac arrhythmia. The present review critically discussed the possible detrimental role of chronic nicotine exposure in cardiac and vascular endothelial dysfunction. Moreover, the signaling mechanisms involved in the pathogenesis of nicotine exposure-induced cardiovascular dysfunction have been discussed. In addition, the pharmacological interventions to ameliorate chronic nicotine exposure-induced cardiovascular abnormalities have been delineated.

Smoking in inflammatory bowel diseases: good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn's disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing CD and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves CD. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

Smoking in inflammatory bowel diseases: good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn's disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing CD and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves CD. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

The alpha7 nicotinic acetylcholine receptor as a pharmacological target for inflammation

The physiological regulation of the immune system encompasses comprehensive anti-inflammatory mechanisms that can be harnessed for the treatment of infectious and inflammatory disorders. Recent studies indicate that the vagal nerve, involved in control of heart rate, hormone secretion and gastrointestinal motility, is also an immunomodulator. In experimental models of inflammatory diseases, vagal nerve stimulation attenuates the production of proinflammatory cytokines and inhibits the inflammatory process. Acetylcholine, the principal neurotransmitter of the vagal nerve, controls immune cell functions via the alpha7 nicotinic acetylcholine receptor (alpha7nAChR). From a pharmacological perspective, nicotinic agonists are more efficient than acetylcholine at inhibiting the inflammatory signaling and the production of proinflammatory cytokines. This 'nicotinic anti-inflammatory pathway' may have clinical implications as treatment with nicotinic agonists can modulate the production of proinflammatory cytokines from immune cells. Nicotine has been tested in clinical trials as a treatment for inflammatory diseases such as ulcerative colitis, but the therapeutic potential of this mechanism is limited by the collateral toxicity of nicotine. Here, we review the recent advances that support the design of more specific receptor-selective nicotinic agonists that have anti-inflammatory effects while eluding its collateral toxicity.

Mechanisms of Disease: nicotine—a review of its actions in the context of gastrointestinal disease

Smoking tobacco is associated with a number of gastrointestinal disorders. In some, such as Crohn's disease and peptic ulcer disease, it increases the risk of disease and has a detrimental effect on their course. In others, such as ulcerative colitis, it decreases the risk of disease and can have a favorable effect on disease course and severity. In the eighteenth and nineteenth centuries, nicotine was used as a 'panacea' for various ailments, including abdominal symptoms--it is now under investigation to elucidate its role in gastrointestinal diseases that are associated with smoking. The actions of nicotine are complex; it is likely that its effects on the central nervous system, gastrointestinal tract and immune system interact with other risk factors, such as genetic susceptibility, to influence disease outcomes. This review focuses on the mechanisms of action of nicotine that might be relevant in gastrointestinal disease.

The vagus nerve and the nicotinic anti-inflammatory pathway

Physiological anti-inflammatory mechanisms are selected by evolution to effectively control the immune system and can be exploited for the treatment of inflammatory disorders. Recent studies indicate that the vagus nerve (which is the longest of the cranial nerves and innervates most of the peripheral organs) can modulate the immune response and control inflammation through a 'nicotinic anti-inflammatory pathway' dependent on the alpha7-nicotinic acetylcholine receptor (alpha7nAChR). Nicotine has been used in clinical trials for the treatment of ulcerative colitis, but its clinical applications are limited by its unspecific effects and subsequent toxicity. This article reviews recent advances supporting the therapeutic potential of selective nicotinic agonists in several diseases. Similar to the development of alpha- and beta-agonists for adrenoceptors, selective agonists for alpha7nAChR could represent a promising pharmacological strategy against infectious and inflammatory diseases.

The pharmacological actions of nicotine on the gastrointestinal tract

Increasing use of tobacco and its related health problems are a great concern in the world. Recent epidemiological findings have demonstrated the positive association between cigarette smoking and several gastrointestinal (GI) diseases, including peptic ulcer and cancers. Interestingly, smoking also modifies the disease course of ulcerative colitis (UC). Nicotine, a major component of cigarette smoke, seems to mediate some of the actions of cigarette smoking on the pathogenesis of GI disorders. Nicotine worsens the detrimental effects of aggressive factors and attenuates the protective actions of defensive factors in the processes of development and repair of gastric ulceration. Nicotine also takes part in the initiation and promotion of carcinogenesis in the GI tract. In this regard, nicotine and its metabolites are found to be mutagenic and have the ability to modulate cell proliferation, apoptosis, and angiogenesis during tumoriogenesis through specific receptors and signalling pathways. However, to elucidate this complex pathogenic mechanism, further study at the molecular level is warranted. In contrast, findings of clinical trials give promising results on the use of nicotine as an adjuvant therapy for UC. The beneficial effect of nicotine on UC seems to be mediated through multiple mechanisms. More clinical studies are needed to establish the therapeutic value of nicotine in this disease.

Inflammatory bowel disease and smoking: a review of epidemiology, pathophysiology, and therapeutic implications

The relationship between smoking behavior and inflammatory bowel disease (IBD) is complex. While Crohn's disease (CD) is associated with smoking and smoking has detrimental effects on the clinical course of the disease, ulcerative colitis (UC) is largely a disease of nonsmokers and former smokers. Furthermore, cigarette smoking may even result in a beneficial influence on the course of ulcerative colitis. The potential mechanisms involved in this dual relationship include changes in humoral and cellular immunity, cytokine and eicosanoid levels, gut motility, permeability, and blood flow, colonic mucus, and oxygen free radicals. Nicotine is assumed to be the active moiety. The differential therapeutic consequences comprise the cessation of smoking in CD and, so far, clinical trials using nicotine in different forms of application for UC. In this article, we review the relationship between cigarette smoking and IBD, considering epidemiological, pathogenetic, and clinical aspects.

Tobacco and IBD: relevance in the understanding of disease mechanisms and clinical practice

Current smoking protects against ulcerative colitis and, after onset of the disease, improves its course, decreasing the need for colectomy. However, smoking increases the risk of developing Crohn's disease and worsens its course, increasing the need for steroids, immunosuppressants and reoperations. Smoking cessation aggravates ulcerative colitis and improves Crohn's disease. The effects of smoking are the sum of contradictory effects of various substances, including nicotine and carbon monoxide, and are modulated by gender, genetic background, disease location and activity, cigarette dose and nicotine concentration. Smokers with ulcerative colitis should not be discouraged from stopping smoking but encouraged to stop, to reduce their risk of cardiopulmonary tobacco-related diseases. In Crohn's disease, smoking cessation has become a major therapeutic goal, particularly in young women and in patients with ileal involvement. A large amount of supportive information, use of nicotine-replacement therapies and antidepressants, and individual counselling might aid the patient in quitting.

Anti-inflammatory actions of acupuncture

Acupuncture has a beneficial effect when treating many diseases and painful conditions, and therefore is thought to be useful as a complementary therapy or to replace generally accepted pharmacological intervention. The attributive effect of acupuncture has been investigated in inflammatory diseases, including asthma, rhinitis, inflammatory bowel disease, rheumatoid arthritis, epicondylitis, complex regional pain syndrome type 1 and vasculitis. Large randomised trials demonstrating the immediate and sustained effect of acupuncture are missing. Mechanisms underlying the ascribed immunosuppressive actions of acupuncture are reviewed in this communication. The acupuncture-controlled release of neuropeptides from nerve endings and subsequent vasodilative and anti-inflammatory effects through calcitonine gene-related peptide is hypothesised. The complex interactions with substance P, the analgesic contribution of beta-endorphin and the balance between cell-specific pro-inflammatory and anti-inflammatory cytokines tumour necrosis factor-alpha and interleukin-10 are discussed.

Effects of appendicectomy on the course of ulcerative colitis

BACKGROUND

Appendicectomy reduces the risk of having ulcerative colitis. However, its effect on the natural history of ulcerative colitis remains uncertain.

AIM

To determine whether appendicectomy reduces the overall severity of ulcerative colitis.

PATIENTS AND METHODS

Appendicectomy status and smoking habits were specified by direct interview in 638 patients seen consecutively between 1997 and 2000. Severity of ulcerative colitis was assessed by reviewing therapeutic needs from the onset of colitis. Additionally, the annual incidence of flare up was assessed prospectively between 1997 and 2000 in patients who had not been colectomised.

RESULTS

The 10 year risk of colectomy was 16 (7)% in previously appendicectomised patients (n=49) compared with 33 (2)% in non-appendicectomised patients (n=589, p=0.05). Cox regression showed that previous appendicectomy and current smoking were independent factors protecting against colectomy (adjusted hazard ratio and 95% confidence intervals: 0.40 (0.20-0.78) and 0.60 (0.40-0.95), respectively). The respective proportions of appendicectomised and non-appendicectomised patients who required oral steroids and immunosuppressive therapy were not significantly different (67% v 70% and 27% v 19%, respectively). Between 1997 and 2000, ulcerative colitis was active for 48% of the time in appendicectomised patients (47 of 98 patient years) and for 62% of the time in non-appendicectomised patients (631 of 1024 patient years; p<0.01).

CONCLUSION

Previous appendicectomy is associated with a less severe course of ulcerative colitis. The beneficial effect of appendicectomy on the risk of colectomy is additive to that of current smoking.

Cigarette smoking, appendectomy, and tonsillectomy as risk factors for the development of primary sclerosing cholangitis: a case control study

BACKGROUND AND AIMS

The strong clinical association between primary sclerosing cholangitis (PSC) and ulcerative colitis (UC) suggests common factors in their pathogenesis. Smoking, previous appendectomy, and tonsillectomy have been associated with a decreased risk of developing UC. In this study, our aim was to examine these risk factors in patients with PSC with and without underlying inflammatory bowel disease (IBD).

METHODS

The smoking habits and history of previous appendectomy and/or tonsillectomy of 170 patients with PSC, 41 without underlying IBD, 170 patients with UC but normal liver function tests, and 170 age and sex matched community controls were obtained by questionnaire.

RESULTS

A total of 112 PSC patients (66%) had never smoked compared with 66 controls (39%). Only 12 PSC patients (7%) were current smokers versus 43 controls (25%). The resultant odds ratio of having PSC was 0.17 (95% confidence interval (CI) 0.08-0.35) among current smokers and 0.33 (95% CI 0.21-0.52) among ever (former+current) smokers. Among former smokers, the odds of having PSC were also significantly decreased (odds ratio 0.45, 95% CI 0.26-0.73; p<0.05). In the subgroup of PSC patients without IBD, only 5% were current smokers versus 26% of matched controls, and never smokers were overrepresented (68% v 37%). The rate of previous appendectomy was similar in all three study groups (14%, 12%, and 13%) but the frequency of tonsillectomy was reduced in the PSC group (21% v 31%; p=0.05).

CONCLUSION

PSC, like UC, is a disease of non-smokers as the odds of having PSC was significantly decreased among current and former smokers. The association between non-smoking and PSC was independent of whether the PSC patient had underlying IBD. Previous tonsillectomy but not appendectomy may also be associated with a decreased risk of PSC but this warrants further study.

Transport mechanisms of nicotine across the human intestinal epithelial cell line Caco-2

Ulcerative colitis is a disease more commonly seen in nonsmokers. Because nicotine was postulated to be a beneficial component of tobacco smoke for ulcerative colitis, various formulations of nicotine have been developed to improve the local bioavailability within the gastrointestinal tissue. In the present study, to characterize the disposition of nicotine in the intestines, we investigated intestinal nicotine transport using Caco-2 cells. Nicotine was predominantly transported across Caco-2 cell monolayers in a unidirectional mode, corresponding to intestinal secretion, by pH-dependent specific transport systems. The specific uptake systems appear to be distinct from organic cation transporters and the transport system for tertiary amines, in terms of its substrate specificity and the pattern of the interaction. These transport systems could play a role in the intestinal accumulation of nicotine from plasma and could also be responsible for the topical delivery of nicotine for ulcerative colitis therapy. These findings could provide useful information for the design of effective nicotine delivery.

Chronic nicotine administration differentially alters jejunal and colonic inflammation in interleukin-10 deficient mice

BACKGROUND

Cigarette smoking alters the course of inflammatory bowel disease, is associated with protection against ulcerative colitis, but aggravates or has no effect on Crohn's disease. While the aetiology of this discrepancy remains unclear, differences between location of involvement in ulcerative colitis and Crohn's disease have not been examined in these studies.

AIM

To examine the effects of nicotine administration on the course of jejunitis and colitis in interleukin-10 deficient mice.

METHODS

Male C57/BL10 IL-10 -/- and wild type mice were given nicotine (12.5 microg/ml) in their drinking water at age 12-14 weeks when they had developed clinical signs of inflammatory bowel disease. Gender and age matched control mice received tap water alone. All mice were killed after 2 weeks of treatment. Whole tissue sections of jejunum, proximal and distal colon were separated and examined by macroscopic and histological score. Northern blots were examined for somatostatin, intestinal trefoil factor and mucin-2.

RESULTS

At 14-16 weeks, when the mice were killed, IL-10 -/- untreated control mice developed jejunitis (macroscopic score 1.4 +/- 0.5, microscopic score 2.0 +/- 0.2) and colitis (2.0 +/- 0.2 and 5.9 +/- 0.9, respectively). IL-10 -/- mice treated for 2 weeks with nicotine had significantly reduced colonic scores (1.4 +/- 0.6 and 2.2 +/- 0.15, respectively). In contrast, the jejunum was more severely damaged (2.6 +/- 0.4 and 4.0 +/- 0.3; P = 0.01, respectively). Nicotine significantly increased both somatostatin and intestinal trefoil factor mRNA expression in the colon but not in the jejunum; no effect was noted on mucin-2 or beta-actin mRNA expression.

CONCLUSIONS

(1) Two weeks of nicotine administration leads to contrasting effects on jejunal and colonic inflammation in IL-10 -/- mice. (2) Nicotine ameliorated inflammation in the colon, which was associated with enhanced expression of two protective peptides.

Medical therapy for ulcerative colitis

Although newer therapeutic agents are being developed for the treatment of inflammatory bowel disease, aminosalicylates and corticosteroids remain the mainstay of treatment for UC (Tables 2-5). Patients who do not respond to these agents or become steroid dependent require immunomodulatory therapy or curative surgery. Cyclosporine represents the greatest treatment advance for UC in 10 years. The role of nicotine, heparin, antibiotics, probiotics, and SCFA in the treatment of UC is less clear, but these agents may offer an alternative therapeutic approach for patients intolerant or nonresponsive to standard therapy.

Ridogrel enemas in distal ulcerative colitis

OBJECTIVE

To evaluate the effect of Ridogrel enemas (Janssen Research Foundation, Beerse, Belgium) on disease activity and mucosal inflammatory mediators in patients with active left-sided ulcerative colitis.

DESIGN AND METHODS

Eleven patients with active left-sided ulcerative colitis were evaluated in an open non-placebo-controlled pilot study. All patients were treated with Ridogrel enemas (300 mg/40 ml once daily) over four weeks. A disease activity score based on clinical, endoscopic and histological criteria was obtained before and after treatment with Ridogrel. The concentrations of thromboxane B2 (TxB2), prostaglandin E2 (PGE2), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-alpha) were measured in mucosal biopsies before and after treatment.

RESULTS

One patient discontinued treatment because of progression of disease, the other ten patients tolerated the Ridogrel enemas well. Mucosal TxB2 concentration decreased significantly in all patients. The mucosal concentrations of the other inflammatory mediators (PGE2, IL-6 and TNF-alpha) were unaltered. The disease score decreased in five patients. However, clinical improvement was not always associated with a decrease in endoscopic and/or histological scores.

CONCLUSIONS

This pilot study shows that Ridogrel enemas selectively reduce mucosal TxB2 concentration.

Risk factors for hospitalized gastrointestinal bleeding among older persons. Cardiovascular Health Study Investigators

OBJECTIVES

We sought to estimate the incidence of hospitalization for upper and lower gastrointestinal bleeding among older persons and to identify independent risk factors.

DESIGN

Prospective cohort study.

SETTING

The Cardiovascular Health Study (CHS).

PARTICIPANTS

5,888 noninstitutionalized men and women age 65 years or older in four U.S. communities enrolled in the CHS.

MEASUREMENTS

Gastrointestinal bleeding events during the period 1989 through 1998 were identified using hospital discharge diagnosis codes and confirmed by medical records review. Risk-factor information was collected in a standardized fashion at study baseline and annually during follow-up.

RESULTS

Among CHS participants (mean baseline age 73.3 years, 42% male), the incidence of hospitalized gastrointestinal bleeding was 6.8/1,000 person-years. In multivariate analyses, advanced age, male sex, unmarried status, cardiovascular disease, difficulty with daily activities, use of multiple medications, and use of oral anticoagulants were independent risk factors. Compared with nonsmokers, subjects who smoked more than half a pack per day had a multivariate-adjusted hazard ratio (HR) of 2.14 (95% confidence interval [CI] = 1.22-3.75) for upper gastrointestinal bleeding and a multivariate-adjusted HR of 0.21 (95% CI = 0.03-1.54) for lower gastrointestinal bleeding. Aspirin users did not have an elevated risk of upper gastrointestinal bleeding (HR = 0.76, 95% CI = 0.52-1.11), and users of other nonsteroidal anti-inflammatory drugs had a HR of 1.54 (95 % CI = 0.99-2.36). Low ankle-arm systolic blood pressure index was associated with higher risk of gastrointestinal bleeding among subjects with clinical cardiovascular disease but not among those without clinical cardiovascular disease.

CONCLUSION

This study identifies risk factors for gastrointestinal bleeding, such as disability, that may be amenable to modification. The findings will help clinicians to identify older persons who are at high risk for gastrointestinal bleeding.

Protective role of cyclooxygenase inhibitors in the adverse action of passive cigarette smoking on the initiation of experimental colitis in rats

Clinical and experimental findings had indicated that cigarette smoke exposure, and cyclooxygenase-2, are strongly associated with inflammatory bowel disease. The present study aimed to evaluate the role of cyclooxygenase-2 in the pathogenesis of experimental inflammatory bowel disease as well as in the adverse action of cigarette-smoke exposure. Rats were pretreated with different cyclooxygenase-2 inhibitors (indomethacin, nimesulide, or SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide)) along with cigarette-smoke exposure before 2,4,6-trinitrobenzenesulfonic acid-enema. Results indicated that pretreatment with cyclooxygenase-2 inhibitors not only protected against 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also attenuated the potentiating effect of cigarette-smoke exposure on colonic damage. Furthermore, the colonic cyclooxygenase-2 protein and mRNA expression was markedly induced by 2,4,6-trinitrobenzenesulfonic acid-enema, and it was potentiated further by cigarette-smoke exposure, while the cyclooxygenase-1 expression was not changed. The present study suggests that the highly induced cyclooxygenase-2 expression not only plays a pathogenic role in 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also contributes to the adverse action of cigarette-smoke exposure on this disorder.

The relationship between heritability and smoking habits in Crohn's disease. Italian Cooperative Study Group

OBJECTIVE

In Crohn's disease (CD), the relationship between genetic predisposition and smoking has not been well defined. The aim of this study was to compare the smoking habits at the time of the diagnosis of CD patients having familial occurrence of inflammatory bowel disease (IBD) with those of some control groups.

METHODS

In a multicenter study, 136 CD patients with a relative with IBD, 272 healthy controls matched for sex and age, 500 CD patients without familial occurrence of IBD, and 84 ulcerative colitis patients (UC) with familial occurrence of IBD were personally interviewed about their smoking habits. In addition, data for 35 healthy siblings of patients with familial CD were collected by interviewing the patients' relatives.

RESULTS

The prevalence of smokers was found significantly higher in CD patients with a family history for IBD than in healthy controls and in familial UC patients (OR 2.28 CI 1.5-3.48 and OR 5.81 CI 3.15-10.75, respectively). No significant difference was found either in the percentage of smokers or in the number of cigarettes smoked per day between familial and sporadic CD patients. Among all siblings of CD patients, 72% of affected siblings and 34% of healthy siblings were smokers, concordant with their relatives.

CONCLUSIONS

In CD patients with familial occurrence of IBD, the percentage of smokers is elevated. It is possible that in a genetically predisposed population, smoking could be an important environmental factor in determining CD or expressing this disease instead of UC.

Role of smoking in inflammatory bowel disease: implications for therapy

The relationship between smoking and inflammatory bowel disease is now firmly established but remains a source of confusion among both patients and doctors. It is negatively associated with ulcerative colitis but positively associated with Crohn's disease. In addition, it has opposite influences on the clinical course of the two conditions with benefit in ulcerative colitis but a detrimental effect in Crohn's disease. These differences have been the subject of much interest and scrutiny with the hope that they may offer some insight into the pathogenesis of the two conditions and possibly lead to alternative therapeutic options. Nicotine is probably the principal active ingredient in smoking responsible for the association; trials have shown it to be of some benefit in ulcerative colitis, but further research is required to establish its therapeutic role, and the relevant mechanisms responsible for its action. In this article, we review the role of smoking in inflammatory bowel disease and its implication for therapy.

Smoking and disease recurrence after operation for Crohn's disease

BACKGROUND

There is increasing speculation about the role of smoking in the pathogenesis of inflammatory bowel diseases. The purpose of this study is to review the impact of smoking on disease recurrence after operation for Crohn's disease.

METHODS

A Medline-based literature review (1966-1999) was carried out; ten studies examined the relationship between smoking and disease recurrence after operation.

RESULTS

Approximately half of the patients were smokers at the time of operation. In most studies smoking significantly increased the risk of postoperative disease recurrence. Smokers had an approximately twofold increased risk of recurrence compared with non-smokers and the effect of smoking was dose dependent. The increased risk of recurrence among smokers was more prominent in women than in men, and a longer duration of smoking increased the risk of recurrence. Ex-smokers had a similar recurrence rate to non-smokers and giving up smoking soon after operation was associated with a lower probability of recurrence.

CONCLUSION

Smoking significantly increases the risk of recurrence of disease after operation for Crohn's disease, especially in women and heavy smokers. Encouraging patients to stop smoking is an important part of the management of Crohn's disease.

Transdermal nicotine decreases mucosal IL-8 expression but has no effect on mucin gene expression in ulcerative colitis

Our goal was to determine the effect of transdermal nicotine on cytokine and mucin gene transcription in ulcerative colitis (UC). Sixty-four nonsmoking patients with active UC were randomly assigned to transdermal nicotine (maximum dose 22 mg/day) or placebo for 4 weeks. Clinical assessment and colonic mucosal biopsies were obtained at entry and after 4 weeks. Inflammatory and immunoregulatory cytokines were assessed by qualitative reverse transcriptase-polymerase chain reaction (RT-PCR). Based on this initial screen. IL-8 mRNA levels were measured by RT-competitive PCR. MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, and MUC6 mRNA concentrations were measured by quantitative dot blot analysis. Cytokine mRNA expression, except for IL-8, was similar in all patients. IL-8 mRNA levels were significantly decreased in the colonic mucosa of nicotine-treated patients who improved (p = 0.04). IL-8 mRNA values were similar before and after treatment in nonresponding nicotine-treated patients and in all placebo-treated patients. Mucin gene expression was similar in all patient groups. Beneficial effects of transdermal nicotine in active UC may result from decrease of IL-8 expression at the transcriptional level. Transdermal nicotine has no effect on mucin gene transcription.

Nicotine therapy for ulcerative colitis: a review of rationale, mechanisms, pharmacology, and clinical results

Smoking is protective against developing ulcerative colitis. Nicotine may be the cause of this protective effect. Controlled trials have demonstrated efficacy of transdermal nicotine for active ulcerative colitis. Side effects observed with transdermal nicotine include contact dermatitis, nausea, and lightheadedness. Topical administration of nicotine to the colon reduces nicotine blood concentrations and side effects, and may be of clinical benefit.

The influence of cigarette smoking on cytokine levels in patients with inflammatory bowel disease

Anecdotal reports suggest that smoking may be beneficial for patients with inflammatory bowel disease (IBD) as nicotine may act through inflammatory mediators within the colonic mucosa. Furthermore, there is increasing evidence that cytokines play a pathologic role in IBD. Our aim was to determine the effects of cigarette smoking on cytokine levels in the colonic mucosa of patients with and without IBD. Mucosal biopsies were obtained from 10 patients with Crohn's disease (CD), 10 with ulcerative colitis (UC), and 10 healthy controls. Five of 10 patients in each of the three groups were smokers and five were nonsmokers. Concentrations of interleukin (IL)-1beta, IL-2, IL-6, and IL-8 were determined using enzyme-linked immunosorbent assay (ELISA). Cytokine levels of smokers were compared with nonsmokers in each group and with controls. Results were analyzed using the Mann-Whitney test; significance was set at p<0.05. The concentration of IL-8 was significantly higher in healthy controls who smoke compared with nonsmokers and significantly reduced in smokers with CD compared with nonsmokers with CD. Moreover, concentrations of IL-1beta and IL-8 were significantly reduced in smokers with UC compared with nonsmokers with UC. Smokers had significantly elevated levels of IL-8 in the colonic mucosa. Smokers with IBD had a significant reduction in cytokine levels; specifically, IL-1beta and IL-8 for patients with UC and IL-8 for patients with CD. Further studies are warranted to determine if this reduction in cytokine levels is histologically and clinically significant.

Transdermal nicotine inhibits interleukin 2 synthesis by mononuclear cells derived from healthy volunteers

BACKGROUND

Smoking has either a beneficial or harmful effect on the course and recurrence of ulcerative colitis (UC) and Crohn's disease respectively. Transdermal application of nicotine had similar effects in UC and therefore was considered to be an effective basic drug that could be further developed in the search for new compounds in the treatment of acute exacerbations of corticosteroid-resistant UC. To clarify the hypothesis that nicotine exerts its anti-inflammatory effect in UC through selective inhibition of T-cell-derived cytokine synthesis, we studied in vivo effects of nicotine on cytokine production by human non-adherent mononuclear cells isolated from peripheral blood in a randomized, double-blind, placebo-controlled trial.

METHODS

Healthy non-smoking volunteers applied for 2 weeks of nicotine patches (n = 12) with incremental doses of nicotine during the first week to achieve a maintenance dose of 15 mg per day, or placebo (n = 12). Blood was obtained before treatment and 1, 2, 3 and 6 weeks after the start of treatment. Cells were cultured in the absence or presence of phytohaemagglutinin for 48 h, and total amounts of interleukin 2 (IL-2), IL-4, IL-10, IL-13, interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) were measured.

RESULTS

Transdermal nicotine caused a significant inhibition of IL-2 after 2 weeks' treatment compared with the placebo group. In addition, a diminished production of IL-10 and TNF-alpha in comparison with day 0 was observed.

CONCLUSION

The beneficial effect of transdermal nicotine in ulcerative colitis may be mediated by a selective inhibition of the IL-2 production by mucosal mononuclear cells, which could result in diminished cell proliferation and consequently a reduction in the inflammatory process.

Inflammatory bowel disease and smoking--a review

The relationship between smoking and inflammatory bowel disease is a curious but well-established one. It is negatively associated with ulcerative colitis but positively associated with Crohn's disease. It also has opposite influences on the clinical course of the two conditions with possible beneficial effect in ulcerative colitis and detrimental effect in Crohn's disease. The diametrically "opposite" relationship of smoking status with the two conditions has been the subject of much interest in the hope that it may reveal pathogenic mechanisms responsible for the two conditions and possibly offer the key to alternative therapeutic options. Nicotine may be the principal agent in smoking responsible for the association; trials have shown it to be of some benefit in ulcerative colitis, but further research is required to establish its therapeutic role and possible mechanisms of action. In this article, we review the historical, clinical, and therapeutic aspects of the association between smoking and inflammatory bowel disease.

Smoking and nicotine in inflammatory bowel disease: good or bad for cytokines?

Smoking has either a beneficial or harmful effect on the course and recurrence of ulcerative colitis and Crohn's disease respectively. Transdermal application of nicotine had similar effects in ulcerative colitis and therefore was considered to be an effective basic drug which could be further developed in the search for new compounds in the treatment of acute exacerbations of corticosteroid resistant ulcerative colitis. In this communication the short-term use of nicotine in ulcerative colitis is reviewed.

The role of cigarettes and nicotine in the onset and treatment of ulcerative colitis

Epidemiological evidence suggests that ulcerative colitis is a disease of nonsmokers, while Crohn's disease is a disease of smokers. The relative risk of developing ulcerative colitis is not only greater in nonsmokers, in addition there appears to be a rebound effect in smokers who quit, with the heaviest (ex-)smokers increasing their relative risk of the disease the most. This factor poses an ethical dilemma for health professionals giving advice on stopping smoking, which may thus have a serious detrimental effect on the health of some patients. Nicotine is believed to be the pharmacological ingredient of tobacco that is responsible for this beneficial effect and several clinical trials using nicotine have demonstrated it to be an effective therapeutic agent in the treatment of ulcerative colitis. Although the aetiology of ulcerative colitis is unclear, current research using nicotine-based products has produced some interesting clues, together with the possibility of some form of therapeutic treatment based on nicotine administration.