Nicotine inhibits cytokine synthesis by mouse colonic mucosa

Genetically Predicted Adiposity, Diabetes, and Lifestyle Factors in Relation to Diverticular Disease

BACKGROUND & AIMS

Adiposity, type 2 diabetes, alcohol and coffee consumption, and smoking have been examined in relation to diverticular disease in observational studies. We conducted a Mendelian randomization study to assess the causality of these associations.

METHODS

Independent genetic instruments associated with the studied exposures at genome-wide significance were obtained from published genome-wide association studies. Summary-level data for the exposure-associated single nucleotide polymorphisms with diverticular disease were available in the FinnGen consortium (10,978 cases and 149,001 noncases) and the UK Biobank study (12,662 cases and 348,532 noncases).

RESULTS

Higher genetically predicted body mass index and genetic liability to type 2 diabetes and smoking initiation were associated with an increased risk of diverticular disease in meta-analyses of results from the two studies. The combined odds ratio of diverticular disease was 1.23 (95% confidence interval [CI], 1.14-1.33; P < .001) for a 1-standard deviation (~4.8 kg/m²) increase in body mass index, 1.04 (95% CI, 1.01-1.07; P = .007) for a 1-unit increase in log-transformed odds ratio of type 2 diabetes, and 1.21 (95% CI, 1.12-1.30; P < .001) for a 1-standard deviation increase in prevalence of smoking initiation. Coffee consumption was not associated with diverticular disease, whereas the association for alcohol consumption largely differed between the 2 studies.

CONCLUSIONS

This study strengthens the causal associations of higher body mass index, type 2 diabetes, and smoking with an increased risk of diverticular disease. Coffee consumption is not associated with diverticular disease. Whether alcohol consumption affects the risk of diverticular disease needs further investigation.

Effects of mango and mint pod-based e-cigarette aerosol inhalation on inflammatory states of the brain, lung, heart, and colon in mice

While health effects of conventional tobacco are well defined, data on vaping devices, including one of the most popular e-cigarettes which have high nicotine levels, are less established. Prior acute e-cigarette studies have demonstrated inflammatory and cardiopulmonary physiology changes while chronic studies have demonstrated extra-pulmonary effects, including neurotransmitter alterations in reward pathways. In this study we investigated the impact of inhalation of aerosols produced from pod-based, flavored e-cigarettes (JUUL) aerosols three times daily for 3 months on inflammatory markers in the brain, lung, heart, and colon. JUUL aerosol exposure induced upregulation of cytokine and chemokine gene expression and increased HMGB1 and RAGE in the nucleus accumbens in the central nervous system. Inflammatory gene expression increased in the colon, while gene expression was more broadly altered by e-cigarette aerosol inhalation in the lung. Cardiopulmonary inflammatory responses to acute lung injury with lipopolysaccharide were exacerbated in the heart. Flavor-specific findings were detected across these studies. Our findings suggest that daily e-cigarette use may cause neuroinflammation, which may contribute to behavioral changes and mood disorders. In addition, e-cigarette use may cause gut inflammation, which has been tied to poor systemic health, and cardiac inflammation, which leads to cardiovascular disease.

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.

E-cigarettes compromise the gut barrier and trigger inflammation

E-cigarette usage continues to rise, yet the safety of e-cigarette aerosols is questioned. Using murine models of acute and chronic e-cigarette aerosol inhalation, murine colon transcriptomics, and murine and human gut-derived organoids in co-culture models, we assessed the effects of e-cigarette use on the gut barrier. Histologic and transcriptome analyses revealed that chronic, but not acute, nicotine-free e-cigarette use increased inflammation and reduced expression of tight junction (TJ) markers. Exposure of murine and human enteroid-derived monolayers (EDMs) to nicotine-free e-cigarette aerosols alone or in co-culture with bacteria also causes barrier disruption, downregulation of TJ protein, and enhanced inflammation in response to infection. These data highlight the harmful effects of "non-nicotine" component of e-cigarettes on the gut barrier. Considering the importance of an intact gut barrier for host fitness and the impact of gut mucosal inflammation on a multitude of chronic diseases, these findings are broadly relevant to both medicine and public health.

E-cigarettes compromise the gut barrier and trigger inflammation

E-cigarette usage continues to rise, yet the safety of e-cigarette aerosols is questioned. Using murine models of acute and chronic e-cigarette aerosol inhalation, murine colon transcriptomics, and murine and human gut-derived organoids in co-culture models, we assessed the effects of e-cigarette use on the gut barrier. Histologic and transcriptome analyses revealed that chronic, but not acute, nicotine-free e-cigarette use increased inflammation and reduced expression of tight junction (TJ) markers. Exposure of murine and human enteroid-derived monolayers (EDMs) to nicotine-free e-cigarette aerosols alone or in co-culture with bacteria also causes barrier disruption, downregulation of TJ protein, and enhanced inflammation in response to infection. These data highlight the harmful effects of "non-nicotine" component of e-cigarettes on the gut barrier. Considering the importance of an intact gut barrier for host fitness and the impact of gut mucosal inflammation on a multitude of chronic diseases, these findings are broadly relevant to both medicine and public health.

Nicotine protects fetus against LPS-induced fetal growth restriction through ameliorating placental inflammation and vascular development in late pregnancy in rats

Our previous work has shown that nicotine suppressed lipopolysaccharide (LPS)-induced placental inflammation by inhibiting cytokine release as well as infiltration of leukocytes into the placenta through the cholinergic anti-inflammatory pathway. Nicotine also increased fetal survival and restored pup weight. In the present study, we aim to further investigate if fetal growth restriction (FGR) occurs with LPS treatment, and evaluate the protective effects of nicotine on fetuses in late gestation of rats. Pregnant Sprague–Dawley rats were divided into control group, nicotine group, LPS group and LPS + nicotine group. Rats were first pretreated with nicotine or vehicle by subcutaneous injection on gestation day (GD)14 and GD15, followed by LPS or vehicle intraperitoneal injection on GD16, and were killed on GD18. Loss of fetuses, number and weights of live fetuses and weights of placentas were recorded. Placentas were collected to evaluate placental pathology and determine inflammatory cytokines and vascular endothelial growth factor (VEGF) levels. We found that LPS treatment increased levels of placental inflammatory cytokines and placental pathological damage, decreased levels of VEGF, reduced number of live fetuses and induced FGR. Pretreatment with nicotine reversed LPS-induced high levels of placental inflammatory cytokines, low levels of placental VEGF and placental pathological damage, then rescued the number and weights of live fetuses. These data demonstrated that activation of the cholinergic anti-inflammatory pathway by nicotine protected fetus against LPS-induced FGR through ameliorating placental inflammation and vascular development in late pregnancy in rats. It may be an alternative therapeutic strategy for inflammation- induced FGR in late pregnancy.

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.

Tobacco smoking and the risk of diverticular disease - a systematic review and meta-analysis of prospective studies

AIM

This systematic review and meta-analysis aimed to clarify whether tobacco smoking is associated with an increased risk of diverticular disease.

METHOD

The PubMed and Embase databases were searched for studies of smoking and diverticular disease up to 19 February 2016. Prospective studies that reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) of diverticular disease associated with current or previous smoking were included. Summary RRs were estimated using a random effects model.

RESULTS

We identified five prospective studies which comprised 6076 cases of incident diverticular disease (diverticulosis and diverticulitis) among 385 291 participants and three studies with 1118 cases of complications related to diverticular disease (abscess or perforation) among 292 965. The summary RR for incident diverticular disease was 1.36 (95% CI 1.15-1.61, I²  = 84%, n = 4) for current smokers, 1.17 (95% CI 1.05-1.31, I²  = 49%, n = 4) for former smokers and 1.29 (95% CI 1.16-1.44, I²  = 62%, n = 5) for ever smokers. The summary RR was 1.11 (95% CI 0.99-1.25, I²  = 82%, n = 4) per 10 cigarettes per day. Although there was some indication of nonlinearity there was a dose-dependent positive association with increasing number of cigarettes smoked per day. There was some evidence that smoking also increases the risk of complications of diverticular disease, but the number of studies was small.

CONCLUSION

The current meta-analysis provides evidence that tobacco smoking is associated with an increased incidence of diverticular disease and related complications.

Nicotine Inhibits Clostridium difficile Toxin A-Induced Colitis but Not Ileitis in Rats

Nicotine is protective in ulcerative colitis but not Crohn's disease of the small intestine, but little is known about the effects of nicotine on Clostridium difficile toxin A-induced enteritis. Isolated ileal or colonic segments in anesthetized rats were pretreated with nicotine bitartrate or other pharmacological agents before intraluminal injection of toxin A. After 3 hours, the treated segments were removed and inflammation was assessed. Nicotine biphasically inhibited toxin A colitis but not ileitis. Pretreatment with the nicotinic receptor antagonist, hexamethonium, blocked the effects of nicotine. Pretreating the colonic segments with hexamethonium before toxin A administration resulted in more inflammation than seen with toxin A alone, suggesting that a tonic nicotinic anti-inflammatory condition exists in the colon. Nicotine also inhibited toxin A-induced increased colonic concentrations of the TRPV1 (transient receptor potential vanilloid subtype 1) agonist, leukotriene B4 (LTB4), and release of the proinflammatory neuropeptide, substance P. Pretreatment with nicotine did not protect against direct TRPV1-mediated colitis caused by intraluminal capsaicin. Nicotinic cholinergic receptors tonically protect the colon against inflammation and nicotine inhibits toxin A colitis but not toxin A ileitis in rats in part by inhibition of toxin A-induced activation of TRPV1 by endogenous TRPV1 agonists such as LTB4.

Nicotine, an α7 nAChR agonist, reduces lipopolysaccharide-induced inflammatory responses and protects fetuses in pregnant rats

OBJECTIVE

The objective of the study was to examine the effects of nicotine, an α7 nicotinic acetylcholine receptor agonist, on lipopolysaccharide (LPS)-induced inflammatory responses in rats during pregnancy.

STUDY DESIGN

Pregnant Sprague Dawley rats were randomly divided into groups (n = 6 rats/group): group 1 rats each received a single intraperitoneal injection of LPS (25 μg/kg) on gestation day 16; group 2 rats were first pretreated with nicotine (1 mg/kg per day, subcutaneously) on gestation days 14 and 15 and then were treated with single injections of LPS on gestational day 16; group 3 rats were treated with the vehicle (saline) used for groups 2 and 3 (controls). Maternal blood was collected at 6 hours and 24 hours after LPS and vehicle treatments and assayed for tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), and interleukin-10 (IL-10). In addition, the number of live pups and pup weights were obtained at the time of delivery.

RESULTS

LPS treatment significantly (P < .001) elevates maternal blood levels of TNF-α and IL-6 but not IL-10 (P > .05). Nicotine treatment significantly reduces LPS-induced TNF-α and IL-6 concentrations (P < .001) but does not change (P > .05) IL-10 levels. The number of live pups in the LPS group are significantly lower (P < .001) than the vehicle treated controls, and nicotine treatment significantly (P < .011) reverses this change. Similarly, fetal weights are lower following LPS (P < .016) and higher (P < .024) in the group treated with nicotine plus LPS.

CONCLUSION

Nicotine reduces the LPS-induced inflammatory responses and rescues the fetus in rats during pregnancy. Thus, nicotine exerts dramatic antiinflammatory effects. These observations have important implications for control of inflammatory responses during pregnancy.

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.

Alcohol and smoking affect risk of uncomplicated colonic diverticulosis in Japan

Colonic diverticula are located predominantly on the right side in Asia and on the left side in Europe and the United States. Factors associated with uncomplicated colonic diverticulosis and its distribution pattern have been unknown. Our aims are to investigate the prevalence and risk factors for uncomplicated colonic diverticulosis. We conducted a prospective cross-sectional study in adults who underwent colonoscopy. Alcohol, alcohol related flushing, smoking, medications, and comorbidities were assessed by interview on the colonoscopy day. Alcohol consumption was categorized as nondrinker, light (1–180 g/week), moderate (181–360 g/week), and heavy (≥361 g/week). Smoking index was defined as the number of cigarettes per day multiplied by the number of smoking years and categorized as nonsmoker, <400, 400–799, and ≥800. A total of 2,164 consecutive patients were enrolled. Overall, 542 patients (25.1%) had uncomplicated colonic diverticulosis located on the right side (50%), bilaterally (29%), and on the left side (21%). Univariate analysis revealed age, male, smoking index, alcohol consumption, aspirin use, anticoagulants use, corticosteroid use, hypertension, and atherosclerotic disease as factors significantly associated with diverticulosis. Alcohol related flushing was not associated with the disease. Multivariate analysis showed increasing age (P<0.01), increasing alcohol consumption (P<0.01) and smoking (P<0.01), and atherosclerotic disease (P<0.01) as significantly associated factors. Alcohol and smoking were associated with right-sided and bilateral diverticula. In conclusion, one in four Japanese adults have colonic diverticulosis (50% right-sided). Age, alcohol consumption, and smoking were found to be significant risk factors for uncomplicated colonic diverticulosis, particularly right-sided and bilateral.

Genetic variants of membrane metallopeptidase genes in inflammatory bowel diseases

BACKGROUND

The substance P pathway modulates neuroimmune interactions during intestinal inflammation.

AIMS

To analyse mucosal expression and genetic variants of the genes coding for substance P, neurokinin-1 receptor and neutral endopeptidase in patients with inflammatory bowel disease.

METHODS

qRT-PCR was used to analyse mRNA levels in matched, paired samples of inflamed colonic mucosa and adjacent non-inflamed endoscopic tissue from 26 Crohn's disease and 25 ulcerative colitis patients. Allele and genotype frequencies of tag-SNPs were determined in 908 Crohn's disease, 929 ulcerative colitis, and 853 controls. Expression levels and genotype distributions were examined within patients' clinical sub-phenotypes.

RESULTS

All 3 evaluated genes were overexpressed in inflamed tissues from Crohn's disease (P=0.033, P=4×10(-5), P=0.001), while in ulcerative colitis only higher levels of the gene coding for neutral endopeptidase were statistically significant (P=2.5×10(-5)). Smoking habit and perianal disease were significantly associated with substance P (P=0.002) and neurokinin-1 receptor levels (P=0.02) in Crohn's disease. Neutral endopeptidase rs701109 variant was associated with inflammatory bowel disease (Crohn's disease: P=0.022; ulcerative colitis: P=0.045), and with the need for colectomy in ulcerative colitis (P=0.008, OR=2.46, 95% CI=1.27-4.76).

CONCLUSIONS

Genetic variants of the gene coding for neutral endopeptidase might affect the neuroimmune interaction during intestinal inflammation and influence clinical sub-phenotypes in patients with inflammatory bowel disease.

Cytokines in inflammatory bowel disease

Over the past decade, much has been learned regarding the role of various cytokines in the pathogenesis of inflammatory bowel disease. Several cytokine ‘knockout’ models in mice have been shown to develop colitis, while alterations in the production of various cytokines has been documented in human Crohn's disease and ulcerative colitis. In recent years, attempts have been made to treat these diseases through modulation of cytokine production or action. This review focuses on the cytokines that have been implicated in the pathogenesis of inflammatory bowel disease. The evidence for and against a role for particular cytokines in intestinal inflammation is reviewed, as is the experimental and clinical data suggesting that cytokines are rational targets for the development of new therapies.

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.

{alpha}7-nAChR-mediated suppression of hyperexcitability of colonic dorsal root ganglia neurons in experimental colitis

Controlled clinical trials of nicotine transdermal patch for treatment of ulcerative colitis have been shown to improve histological and global clinical scores of colitis. Here we report that nicotine (1 microM) suppresses in vitro hyperexcitability of colonic dorsal root ganglia (DRG) (L(1)-L(2)) neurons in the dextran sodium sulfate (DSS)-induced mouse model of acute colonic inflammation. Nicotine gradually reduced regenerative multiple-spike action potentials in colitis mice to a single action potential. Nicotine's effect on hyperexcitability of inflamed neurons was blocked in the presence of an alpha(7)-nicotinic acetylcholine receptor (nAChR) antagonist, methyllicaconitine, while choline, the alpha(7)-nAChR agonist, induced a similar effect to that of nicotine. Consistent with these findings, nicotine failed to suppress hyperexcitability in colonic DRG neurons from DSS-treated alpha(7) knockout mice. Furthermore, colonic DRG neurons from DSS-treated alpha(7) knockout mice were characterized by lower rheobase (10 +/- 5 vs. 77 +/- 13 pA, respectively) and current threshold (28 +/- 4 vs. 103 +/- 8 pA, respectively) levels than DSS-treated C57BL/J6 mice. An interesting observation of this study is that 8 of 12 colonic DRG (L(1)-L(2)) neurons from control alpha(7) knockout mice exhibited multiple-spike action potential firing while no wild-type neurons did. Overall, our findings suggest that nicotine at low 1 microM concentration suppresses in vitro hyperexcitability of inflamed colonic DRG neurons in a mouse model of acute colonic inflammation via activation of alpha(7)-nAChRs.

Smoking increases the incidence of complicated diverticular disease of the sigmoid colon

BACKGROUND AND AIMS

The aim of this study was to establish whether smoking is associated with complicated diverticular disease and adverse outcomes of operative treatment of diverticular disease. Smoking has been associated with increased rate of perforations in acute appendicitis as well as failure of colonic anastomosis in patients resected for colonic tumours. It has also been suggested that smoking is a risk factor for complicated diverticular disease of the colon.

MATERIAL AND METHODS

Retrospective investigation of records of 261 patients electively operated for diverticular disease in Helsinki University Central Hospital during a period of five years.

RESULTS

The smokers underwent sigmoidectomy at a younger age than the non-smokers (p = 0.001) and they had an increased rate of perforations (p = 0.040) and postoperative recurrent diverticulitis episodes (p = 0.019).

CONCLUSIONS

We conclude that smoking increases the likelihood of complications in diverticulosis coli. The development of complicated disease also seems to proceed more rapidly in smokers.Key words: Sigmoid resection; laparoscopy; laparoscopic sigmoidectomy; smoking and diverticular disease; complicated diverticular disease; diverticulitis.

Dysregulation of human beta-defensin-2 protein in inflammatory bowel disease

Background

Human β-defensin-2 (HBD2) is an antimicrobial peptide implicated in the pathogenesis of inflammatory bowel disease (IBD). Low copy number and concomitant low mRNA expression of the HBD2 gene have been implicated in susceptibility to colonic Crohn's Disease (CD). We investigated the colonic distribution of HBD2 mRNA expression, and the contributions of genetic and environmental factors on HBD2 protein production.

Methodology/Principal Findings

We examined HBD2 mRNA expression at three colonic locations by microarray analysis of biopsies from 151 patients (53 CD, 67 ulcerative colitis [UC], 31 controls). We investigated environmental and genetic influences on HBD2 protein production using ex vivo cultured sigmoid colon biopsies from 69 patients (22 CD, 26 UC, 21 controls) stimulated with lipopolysaccharide (LPS) and/or nicotine for 24 hours. HBD2 and cytokines were measured in culture supernatants. Using DNA samples from these patients, regions in the HBD2 gene promoter were sequenced for NF-κB binding-sites and HBD2 gene copy number was determined. HBD2 mRNA expression was highest in inflamed (vs. uninflamed p = 0.0122) ascending colon in CD and in inflamed (vs. uninflamed p<0.0001) sigmoid colon in UC. HBD2 protein production was increased in inflamed UC biopsies (p = 0.0078). There was no difference in HBD2 protein production from unstimulated biopsies of CD, UC and controls. LPS-induced HBD2 production was significantly increased in CD (p = 0.0375) but not UC (p = 0.2017); this LPS-induced response was augmented by nicotine in UC (p = 0.0308) but not CD (p = 0.6872). Nicotine alone did not affect HBD2 production. HBD2 production correlated with IL8 production in UC (p<0.001) and with IL10 in CD (p<0.05). Variations in the HBD2 promoter and HBD2 gene copy number did not affect HBD2 production.

Significance/Conclusions

Colonic HBD2 was dysregulated at mRNA and protein level in IBD. Inflammatory status and stimulus but not germline variations influenced these changes.

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.

Does nicotine influence cytokine profile and subsequent cell cycling/apoptotic responses in inflammatory bowel disease?

BACKGROUND

Smoking differentially influences susceptibility to the inflammatory bowel diseases (IBDs) Crohn's disease (CD) and ulcerative colitis (UC). We investigated the effects of nicotine on cytokine, cell cycle, and apoptotic responses in peripheral blood mononuclear cells (PBMCs) from IBD patients and healthy controls (HCs).

METHODS

PBMCs from IBD patients and HC were stimulated with lipopolysaccharide (LPS; 1 microg/mL) or phytohemagglutinin (PHA, 5 or 0.5 microg/mL), +/- nicotine (1, 10, 100 microg/mL). Cytokines (IL1beta, IL2, IL10, IL12/IL23p40, TGFbeta, TNFalpha) were measured in supernatants at 24 hours. After 72 hours cells were analyzed by flow cytometry for cell cycle and apoptosis. Statistical modeling was used to identify interactions between cytokines and cell cycle / apoptosis and minimize confounding effects.

RESULTS

Stimulation by LPS and PHA (5 microg/mL) increased IL12/IL23p40 production from CD and UC versus HC (P < 0.05); PHA (0.5 microg/mL) increased IL1beta in UC and decreased TGFbeta from CD and UC (P < 0.01). In all groups, nicotine reduced LPS- and PHA (0.5 microg/mL)-stimulated production of IL1beta, IL10, TGFbeta, and TNFalpha (P < 0.001). Cell cycle analysis showed that PHA, but not LPS, induced proliferation and decreased G(0)/G(1) resting cells in CD and UC versus HC (P < 0.001). Nicotine decreased PHA-stimulated S-phase proliferation and increased G(0)/G(1) resting cells (P < 0.01). Modeling showed independent associations between IL12/IL23p40 and apoptosis (P = 0.01), IL1beta and resting cells (P = 0.006), TNFalpha and proliferating cells (P < 0.001). Disease activity and smoking habit had no effect.

CONCLUSIONS

Dysregulated cytokine profiles in UC and CD are associated with specific alterations in cell cycle responses; these effects may be modified by nicotine, and potentially by anticytokine therapies.

Hypothesis about mechanisms through which nicotine might exert its effect on the interdependence of inflammation and gut barrier function in ulcerative colitis

Ulcerative colitis (UC) is characterized by impairment of the epithelial barrier and the formation of ulcer-type lesions, which result in local leaks and generalized alterations of mucosal tight junctions. Ultimately, this results in increased basal permeability. Although disruption of the epithelial barrier in the gut is a hallmark of inflammatory bowel disease and intestinal infections, it remains unclear whether barrier breakdown is an initiating event of UC or rather a consequence of an underlying inflammation, evidenced by increased production of proinflammatory cytokines. UC is less common in smokers, suggesting that the nicotine in cigarettes may ameliorate disease severity. The mechanism behind this therapeutic effect is still not fully understood, and indeed it remains unclear if nicotine is the true protective agent in cigarettes. Nicotine is metabolized in the body into a variety of metabolites and can also be degraded to form various breakdown products. It is possible these metabolites or degradation products may be the true protective or curative agents. A greater understanding of the pharmacodynamics and kinetics of nicotine in relation to the immune system and enhanced knowledge of gut permeability defects in UC are required to establish the exact protective nature of nicotine and its metabolites in UC. This review suggests possible hypotheses for the protective mechanism of nicotine in UC, highlighting the relationship between gut permeability and inflammation, and indicates where in the pathogenesis of the disease nicotine may mediate its effect.

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.

Cholinergic stimulation blocks endothelial cell activation and leukocyte recruitment during inflammation

Endothelial cell activation plays a critical role in regulating leukocyte recruitment during inflammation and infection. Based on recent studies showing that acetylcholine and other cholinergic mediators suppress the production of proinflammatory cytokines via the α7 nicotinic acetylcholine receptor (α7 nAChR) expressed by macrophages and our observations that human microvascular endothelial cells express the α7 nAChR, we examined the effect of cholinergic stimulation on endothelial cell activation in vitro and in vivo. Using the Shwartzman reaction, we observed that nicotine (2 mg/kg) and the novel cholinergic agent CAP55 (12 mg/kg) inhibit endothelial cell adhesion molecule expression. Using endothelial cell cultures, we observed the direct inhibitory effects of acetylcholine and cholinergic agents on tumor necrosis factor (TNF)-induced endothelial cell activation. Mecamylamine, an nAChR antagonist, reversed the inhibition of endothelial cell activation by both cholinergic agonists, confirming the antiinflammatory role of the nAChR cholinergic pathway. In vitro mechanistic studies revealed that nicotine blocked TNF-induced nuclear factor–κB nuclear entry in an inhibitor κB (IκB)α- and IκBɛ-dependent manner. Finally, with the carrageenan air pouch model, both vagus nerve stimulation and cholinergic agonists significantly blocked leukocyte migration in vivo. These findings identify the endothelium, a key regulator of leukocyte trafficking during inflammation, as a target of anti-inflammatory cholinergic mediators.

Dextran sodium sulfate-induced colitis reveals nicotinic modulation of ion transport via iNOS-derived NO

In normal colon, ACh elicits a luminally directed Cl- efflux from enterocytes via activation of muscarinic receptors. In contrast, in the murine model of dextran sodium sulfate (DSS)-induced colitis, an inhibitory cholinergic ion transport event due to nicotinic receptor activation has been identified. The absence of nicotinic receptors on enteric epithelia and the ability of nitric oxide (NO) to modulate ion transport led us to hypothesize that NO mediated the cholinergic nicotinic receptor-induced changes in ion transport. Midportions of colon from control and DSS-treated mice were examined for inducible NO synthase (iNOS) expression by RT-PCR and immunofluorescence or mounted in Ussing chambers for assessment of cholinergic-evoked changes in ion transport (i.e., short-circuit current) with or without pretreatment with pharmacological inhibitors of NO production. iNOS mRNA and protein levels were increased throughout the tissue from DSS-treated mice and, notably, in the myenteric plexus, where the majority of iNOS immunoreactivity colocalized with the enteric glial cell marker glial fibrillary acidic protein. The drop in short-circuit current evoked by the cholinomimetic carbachol in tissue from DSS-treated mice was prevented by selective inhibitors of iNOS activity [N6-(1-iminoethyl)-lysine HCl and N-[3-(aminomethyl)benzyl]acetamidine] or an NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] or by removal of the myenteric plexus. Thus, in this model of colitis, a "switch" occurs from muscarinic to nicotinic receptor-dominated control of cholinergic ion transport. The data indicate a novel pathway involving activation of nicotinic receptors on myenteric neurons, resulting in release of NO from neurons or enteric glia and, ultimately, a dampening of stimulated epithelial Cl- secretion that would reduce secretory diarrhea.

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.

Cholinergic pathways modulate experimental dinitrobenzene sulfonic acid colitis in rats

Recent studies have suggested that neuroimmune interactions modulate intestinal mucosal immune responses. In the current study, we examined the role of cholinergic pathways in modulating the severity of acute dinitrobenzene sulfonic acid colitis, using pharmacological agents to suppress acetylcholinesterase in Sprague-Dawley rats, and evaluating the colitis in the cholinergic hyperresponsive Flinder's sensitive line rats and their control counterparts, the Flinder's resistant line. Colitis was induced by intrarectal dinitrobenzene sulfonic acid (80 mg x ml(-1) in 50% ethanol); controls received intrarectal saline. Sprague-Dawley rats received an acetylcholinesterase inhibitor, physostigmine (50 microg x kg(-1) s.c.) or neostigmine (50 microg x kg(-1) s.c.), 30 min prior to intrarectal dinitrobenzene sulfonic acid; controls received saline vehicle. On day 5, the macroscopic damage score, myeloperoxidase activity (an estimate of granulocyte infiltration) and smooth muscle thickness were evaluated in the inflamed colonic segment. Significant increases in macroscopic damage score and colonic smooth muscle thickness were observed in Sprague-Dawley and Flinder's Resistant Line rats on day 5 following intrarectal dinitrobenzene sulfonic acid compared to saline controls. Increased myeloperoxidase activity was also observed in dinitrobenzene sulfonic acid-treated Sprague-Dawley rats and Flinder's Resistant Line rats. In contrast, Flinder's Sensitive Line rats failed to demonstrate a significant rise in macroscopic damage, smooth muscle layer thickness, or myeloperoxidase activity on day 5 following intrarectal dinitrobenzene sulfonic acid when compared to saline-treated Flinder's Sensitive Line controls. Neostigmine and physostigmine treatment prior to intrarectal dinitrobenzene sulfonic acid significantly attenuated macroscopic damage score, myeloperoxidase activity and smooth muscle thickness on day 5 compared to colitic Sprague-Dawley controls. Significantly greater reductions in myeloperoxidase activity were observed with physostigmine vs. neostigmine pretreatment. These data suggest that cholinergic pathways modulate the acute colonic inflammatory response associated with the dinitrobenzene sulfonic acid model, with central pathways exerting a greater protective effect relative to peripheral pathways. Further studies are required to determine the contributions of sites in the nervous system and neuro-effector junctions.

In vivo influence of nicotine on human basal and NSAID-induced gut barrier function

BACKGROUND

Smoking reduces the non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal permeability increase in healthy people. It also affects inflammatory bowel disease that is associated with a disturbed gut barrier function. To assess the role of nicotine on barrier function, its influence on basal and NSAID-induced intestinal permeability was studied in healthy volunteers.

METHODS

Thirty-one healthy non-smoker subjects performed permeability tests with 51Cr-EDTA and sugar markers (sucrose, lactulose, mannitol, sucralose) before and during 2 weeks of nicotine patch application, and with and without indomethacin intake, respectively. Since smoking has been described as affecting motility, transit measurements were also done with the sodium[13C]-octanoate and lactose-[13C]-ureide breath tests before and during nicotine exposure. Correlations between permeability markers were checked and the influence of gastrointestinal transit was assessed.

RESULTS

Nicotine did not affect barrier function in vivo, nor gastric emptying, small-bowel transit time or orocaecal transit. 51Cr-EDTA and lactulose correlated in basal 0-6 h permeability testing (r = 0.529, P < 0.0001), as did 6-24 h excretion of 51Cr-EDTA and sucralose (r = 0.474, P < 0.001); 97% and 90% of the subjects had a permeability increase after indomethacin intake for 0-6 h and 6-24 h excretion of Cr-EDTA, respectively. This population proportion is 63% for lactulose/mannitol and 83% for sucralose.

CONCLUSIONS

Short-term exposure to nicotine does not alter normal basal or NSAID-induced gut barrier function or transit. 51Cr-EDTA and the respective sugar markers correlate well in in vivo permeability testing in healthy humans. The radioactive test detects more NSAID-induced permeability increase than does the lactulose/mannitol ratio permeability test.

Effect of acute cigarette smoking, alone or with alcohol, on gastric barrier function in healthy volunteers

BACKGROUND

Smoking is a risk factor for gastroduodenal ulcer and gastric adenocarcinoma. However, the pathophysiological mechanisms induced by acute cigarette smoking in the human gastric mucosa are poorly understood.

AIM

To evaluate the effect of acute cigarette smoking, alone or with alcohol, on the gastric permeability to sucrose, a specific marker of mucosal damage in the stomach.

SUBJECTS AND METHODS

Twenty healthy volunteers (8 smokers/12 non-smokers) were studied. Each fasted subject ingested 500 ml of a 20% sucrose solution and the amount of sucrose excreted in a 5-hour urine collection was measured by gas chromatography Four sucrose permeability tests were carried out: 1. basal, 2. while smoking 5 cigarettes, 3. after drinking 50 ml of a 40 degrees alcoholic beverage, 4. a combination of 2+3.

RESULTS

Sucrose excretion increased after alcohol ingestion (40.5 +/- 6.0 mg vs 143.1 +/- 28.9 mg, p = 0.002), but was not modified by acute cigarette smoking (34.4 +/- 5.9 mg). When alcohol and cigarettes were simultaneously consumed, the increase in alcohol-induced sucrose excretion was significantly reduced (73.1 +/- 16.6 mg, p = 0.03). Basal sucrose excretion was similar in smokers and non-smokers. However, in acute cigarette smoking, a decrease in sucrose excretion was observed in smokers (p = 0.02) but not in non-smokers.

CONCLUSIONS

These results indicate that acute cigarette smoking may tighten the gastric mucosa in habitual smokers and this is associated with a smaller increase of gastric permeability induced by alcohol.

Predictors of response to infliximab in patients with Crohn's disease

BACKGROUND & AIMS

Identifying predictors of response to infliximab in Crohn's disease may lead to better selection of patients for this therapy.

METHODS

One hundred patients with either inflammatory or fistulous Crohn's disease and at least 3 months of follow-up after infliximab infusion were evaluated. Clinical response and duration of response were the primary outcome measures.

RESULTS

For inflammatory disease, 73% of nonsmokers, compared with 22% of smokers, responded to infliximab (P < 0.001). Among patients taking concurrent immunosuppressives, 74% responded to infliximab compared with 39% not taking any immunosuppressives (P = 0.007). Prolonged response (duration >2 months) was achieved in 59% of nonsmokers compared with 6% of smokers (P < 0.001) and in 65% of patients on immunosuppressives compared with 18% not on immunosuppressives (P < 0.001). For fistulous disease, overall response rates were not different between nonsmokers and smokers, but nonsmokers had a longer duration of response (P = 0.046). Concurrent use of immunosuppressive medications had no effect on rate or duration of response. Multivariable logistic regression analysis confirmed the harmful effect of smoking and the beneficial effect of immunosuppressive use on response in patients with inflammatory disease. The same analysis for fistulous disease did not show an association between smoking or concurrent immunosuppressive use and response to infliximab.

CONCLUSIONS

In patients with inflammatory disease, nonsmoking and concurrent immunosuppressive use are associated with higher rates of response and longer duration of response to infliximab. In patients with fistulous Crohn's disease, nonsmoking is associated with longer duration of response to infliximab.

Immunomodulatory effects of high-dose alpha-tocopherol acetate on mice subjected to sidestream cigarette smoke

Several recent epidemiological investigations raise serious questions about the health effects of high-dose supplements of Vitamin E (VE) in cigarette smokers. To examine these findings, a total of 96 C57BL/6 mice were randomly assigned to eight groups in a 2 x 4 factorial design (smoke vs. sham smoke and normal diet vs. 3 VE supplements). The mice were exposed to sidestream cigarette smoke (SSCS), at 0.4 mg total particulate matter/m(3) air, from standard research cigarettes (1R4)/day or filtered room air at 30 min/day, 5 days/week, for 9 weeks through a nose-only exposure chamber. The American Institute of Nutrition 93G purified rodent diet was modulated with 75 (regular diet, 1-fold), 1050 (15-fold), 5550 (75-fold), and 11175 (150-fold) IU dl-alpha-tocopherol acetate (alpha-TA)/kg as VE supplementation and provided ad libitum at an average intake rate of 4.11 g diet/mouse/day. This result demonstrated that SSCS exposure results in lung dysfunction, as indicated by a decrease of pulmonary dynamic compliance (C(dyn)) and increase of lung resistance (R(L)), and body weight loss in mice fed with regular diet. These changes accompanied with increases of bronchoalveolar lavage (BAL) concentrations of cytokines interleukin (IL)-1 beta, IL-4 and IFN-gamma, as well as hepatic lipid peroxidation. However, supplemental alpha-TA at the doses of > or = 1050 IU/kg diet prevented the SSCS-induced body weight loss and lung dysfunction. alpha-TA at > or = 5550 IU/kg significantly increased BAL levels of IL-2 and IL-4 in both the sham SSCS and the SSCS groups. Given at 5550 IU alpha-TA/kg, but not higher, mice elevated BAL IL-1 beta level if they were exposed to SSCS. Hepatic lipid peroxidation was decreased in a dose-dependent fashion with different alpha-TA supplements in both the sham SSCS and SSCS groups. Neither SSCS nor alpha-TA had an effect on lung permeability, BAL IL-6, splenic T and B lymphocyte proliferation and their T helper (Th)1 and Th2 cytokines measured among all groups. Data suggest that supplemental alpha-TA may be needed to counteract SSCS-induced oxidative stress, but that potential side effects introduced by high dosage of this synthetic compound should be considered.

Inflammatory bowel disease and environmental influences

Some environmental factors have been established firmly as influences on the development of IBD, such as smoking and appendectomy. Other behaviors, such as oral contraceptive use and sugar intake, have been suggested as risk factors, but he data conflict sharply. The importance of other behaviors, such as breast-feeding, is even murkier with sharply divergent data. Some issues studied may not be factors in themselves but rather markers for other unidentified influences. The conflicting evidence in many of these studies may be clarified as specific genes are identified and the interplay between these environmental factors and genetic subtypes is investigated.

Differential impact of nicotine on cellular proliferation and cytokine production by LPS-stimulated murine splenocytes

The immunoregulatory effects of nicotine have not been fully clarified and the reported data are often conflicting. The present study investigated the role of nicotine as an immunomodulator of murine splenocytes stimulated by lipopolysaccharide (LPS), the endotoxin component of gram-negative bacteria. BALB/c female mice of two different ages, young (2-3 months) and old (18-22 months), were used. The cells were incubated with nicotine at two different time points, 3 h pre-incubation and concurrent incubation relevant to LPS stimulation, before further incubation for 48 or 72 h. Treatment of murine splenocytes with nicotine showed an impact on cellular proliferation as well as on the production of the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The results indicated that nicotine significantly inhibited cellular proliferation of murine splenocytes in a concentration-related manner (32, 64 and 128 microg/ml). Timing of nicotine exposure prior to LPS stimulation was critical in terms of immunological impact on cytokine production. TNF-alpha and IL-6 production were significantly enhanced by 1 microg/ml of nicotine when cells were pre-incubated with nicotine for 3 h compared to concurrent incubation relative to LPS stimulation. The alteration in cytokine production varied with the age of the mouse. TNF-alpha production was significantly inhibited by nicotine in young mice, while IL-6 production was significantly inhibited by nicotine in old mice. Since any immunomodulation that alters the profile of these cytokines may cause an imbalance in the immune system impinging on health status, these findings may be important when dealing with the concept of nicotine as a therapeutic agent.

Cigarette smoke aggravates experimental colitis in rats

BACKGROUND & AIMS

Tobacco smoking has a complex effect on intestinal inflammation, being protective in ulcerative colitis, whereas it aggravates Crohn's disease. The beneficial effect of smoking has been attributed to nicotine, but the mechanisms underlying the adverse effect are still under investigation. The aim of this study was to examine the effect of cigarette smoking on experimental colitis in rats and to investigate the underlying mechanism.

METHODS

Rats were exposed daily to cigarette smoke by means of a specialized smoking chamber. Control rats were placed in the same chamber without introducing smoke. In parallel experiments, rats received the ganglionic blocker hexamethonium before smoke exposure. After 2 weeks, colitis was induced by dinitrobenzenesulfonic acid (DNBS), and inflammation was assessed 3 days later.

RESULTS

Exposure to cigarette smoke significantly increased macroscopic and histological damages as well as myeloperoxidase activity compared with sham-treated controls. Treatment with hexamethonium before smoking reversed the effect of the smoke on the colitis, improving all parameters.

CONCLUSIONS

Exposure to cigarette smoke aggravates DNBS-induced colitis in the rat. This effect is reversed by hexamethonium, suggesting that a neural pathway is involved.

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.

Smoking may be associated with complications in diverticular disease

BACKGROUND

The vast majority of people with diverticula remain asymptomatic or develop minor symptoms while a small group develop serious complications that are associated with significant morbidity and mortality rates. The aim was to identify any risk factors predisposing to complications.

METHODS

Eighty patients with diverticular disease were studied. Patients in group 1 (n = 45) with complications requiring hospitalization or surgery were compared with those in group 2 (n = 35) with asymptomatic diverticula or minor symptoms. Logistic regression analysis was performed.

RESULTS

No differences in epidemiological factors, concurrent and past medical and surgical conditions or chronic medication were detected between the two groups. Generalized disease was not associated with more complications than sigmoid disease. However, smoking seemed to be an independent factor predisposing to complications; the proportion of smokers in group 1 was significantly greater (24 of 45) than that in group 2 (ten of 35) (odds ratio 2.9, P = 0.028).

CONCLUSION

In patients with diverticular disease, smoking is associated with an increased risk of complications.

Novel therapies for inflammatory bowel disease

Looking back at successes and failures in newer approaches to treating IBD, it is tempting--although still difficult--to draw conclusions about pathogenesis. When a therapy proves effective, do clinicians truly know how it works? Even with a therapy as specific as anti-TNF antibody, it is not clear if the benefit is attributable to simple binding and clearance of TNF-alpha or to binding on the cell surface and subsequent deletion of the activated macrophage. When a drug appears to be less effective than preclinical models suggest, can failures in effectiveness from delivery or dosing be differentiated? The disappointing results of clinical trials with IL-10--so at odds with the prediction of benefit from animal models--bring into question the validity of those models as well as the soundness of design of the clinical trials on which efficacy of IL-10 is judged. The variability of response even to the most narrowly targeted agents suggests that these diseases are far more heterogeneous in humans than in their murine counterparts. Clinicians are only just beginning to recognize subclinical markers of response, and it may soon be possible to predict response on the basis of genetic composition. For the moment, however, the field of pharmacogenetics is embryonic. Challenges in developing new therapeutic strategies include not only identifying novel agents, but also improving the definitions of clinical endpoints and defining efficacy at the biologic level. Only through considered evaluation of clinical evidence may clinicians determine which therapies should remain novelties and which should become an accepted part of the armamentarium.

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.

Immunomodulatory effects of cigarette smoke

Cigarette smoke is a major health risk factor which significantly increases the incidence of diseases including lung cancer and respiratory infections. This increased susceptibility may result from cigarette smoke-induced impairment of the immune system. While the acute effects of cigarette smoke on the immune system are less clear, chronic exposure to cigarette smoke or nicotine causes T cell unresponsiveness. This apparent T cell anergy may account for or contribute to the immunosuppressive and anti-inflammatory properties of cigarette smoke/nicotine. Nicotine-induced immunosuppression may result from its direct effects on lymphocytes, indirectly through its effects on the neuroendocrine system, or both.

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.

Nicotine inhibits the in vitro production of interleukin 2 and tumour necrosis factor-alpha by human mononuclear cells

Smoking protects against ulcerative colitis (UC), and treatment with nicotine patches has a beneficial symptomatic effect in patients with UC. To find an explanation for this response to nicotine in UC, we assessed the effects of nicotine on cytokine production by mononuclear cells (MNC). MNC were isolated from peripheral blood from healthy volunteers. Non-adherent MNC were preincubated with varying concentrations of nicotine or prednisolone for 24 h followed by addition of phytohemagglutinin (10 micrograms/ml). The concentrations of interleukin 2 (IL-2) and tumour necrosis factor-alpha (TNF alpha) in the supernatants were determined by ELISA. Nicotine as well as prednisolone caused a significant inhibition of IL-2 and TNF alpha production. The maximum inhibition caused by nicotine was about 50% of that caused by prednisolone and was reached at concentrations equivalent to nicotine levels measured in plasma of smokers. These results indicate that nicotine exerts its immunoregulatory role through modulation of the cytokine production by non-adherent mononuclear cells.