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

Reactive Oxygen Species/Reactive Nitrogen Species as Messengers in the Gut: Impact on Physiology and Metabolic Disorders

Significance: The role of reactive oxygen/nitrogen species as "friend" or "foe" messengers in the whole body is well characterized. Depending on the concentration in the tissue considered, these molecular actors exert beneficial or deleterious impacts leading to a pathological state, as observed in metabolic disorders such as type 2 diabetes and obesity. Recent Advances: Among the tissues impacted by oxidation and inflammation in this pathological state, the intestine is a site of dysfunction that can establish diabetic symptoms, such as alterations in the intestinal barrier, gut motility, microbiota composition, and gut/brain axis communication. In the intestine, reactive oxygen/nitrogen species (from the host and/or microbiota) are key factors that modulate the transition from physiological to pathological signaling. Critical Issues: Controlling the levels of intestinal reactive oxygen/nitrogen species is a complicated balance between positive and negative impacts that is in constant equilibrium. Here, we describe the synthesis and degradation of intestinal reactive oxygen/nitrogen species and their interactions with the host. The development of novel redox-based therapeutics that alter these processes could restore intestinal health in patients with metabolic disorders. Future Directions: Deciphering the mode of action of reactive oxygen/nitrogen species in the gut of obese/diabetic patients could result in a future therapeutic strategy that combines nutritional and pharmacological approaches. Consequently, preventive and curative treatments must take into account one of the first sites of oxidative and inflammatory dysfunctions in the body, that is, the intestine. Antioxid. Redox Signal. 37, 394-415.

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.

Immune activation in primary HIV: influence of duration of infection, treatment, and substance use

Background

Primary human immunodeficiency virus (HIV) is characterized by dynamic changes in viral load and innate and adaptive immune responses; it is unclear the extent to which time from acquisition to antiretroviral therapy (ART) initiation and substance use impact these immunologic changes.

Methods

We studied plasma immune activation biomarkers, viral load, and CD4⁺ and CD8⁺ cell counts in participants from the Sabes primary infection study in Peru, who had been randomized to begin ART immediately after diagnosis vs 24 weeks later. We modeled influence of substance use and duration of HIV infection on biomarkers at baseline and over 24 weeks.

Results

Compared to participants enrolled >30 days after HIV acquisition, participants enrolled during acute infection (≤30 days) had higher mean interferon (IFN)–γ and IFN-α2a (1.7-fold and 3.8-fold interquartile range [IQR] higher, respectively). Participants enrolled >30 days after HIV acquisition had higher mean baseline CD8⁺ cell count (2.7 times the IQR). Alcohol use (positive phosphatidylethanol level) was associated with elevated IFN-γ, tumor necrosis factor alpha (TNF-α), and interleukin 12p70 (IL-12p70), and smoking was associated with higher macrophage inflammatory protein 1α, TNF-α, and IL-12p70. Most biomarkers declined more quickly in participants who initiated ART immediately; however, substance use and duration of HIV infection at enrollment had little influence on rate of decline.

Conclusions

IFN-γ and other biomarkers are elevated during early primary infection, when exposure to HIV antigens is high. Immune activation decreased most quickly in those who started ART during acute/early primary infection. Higher CD8⁺ cell counts and a trend toward higher soluble CD163 levels during the 30 days after acquisition suggest the onset of compensatory responses and immune exhaustion.

Chronic Exposure to Cigarette Smoke Affects the Ileum and Colon of Guinea Pigs Differently. Relaxin (RLX-2, Serelaxin) Prevents Most Local Damage

Cigarette smoking (CS) is the cause of several organ and apparatus diseases. The effects of smoke in the gut are partially known. Accumulating evidence has shown a relationship between smoking and inflammatory bowel disease, prompting us to investigate the mechanisms of action of smoking in animal models. Despite the role played by neuropeptides in gut inflammation, there are no reports on their role in animal models of smoking exposure. The hormone relaxin has shown anti-inflammatory properties in the intestine, and it might represent a putative therapy to prevent gut damage caused by smoking. Presently, we investigate the effects of chronic smoke exposure on inflammation, mucosal secretion, and vasoactive intestinal peptide (VIP) and substance P (SP) expressions in the ileum and colon of guinea pigs. We also verify the ability of relaxin to counter the smoke-induced effects. Smoke impacted plasma carbon monoxide (CO). In the ileum, it induced inflammatory infiltrates, fibrosis, and acidic mucin production; reduced the blood vessel area; decreased c-kit-positive mast cells and VIP-positive neurons; and increased the SP-positive nerve fibers. In the colon, it reduced the blood vessel area and the goblet cell area and decreased c-kit-positive mast cells, VIP-positive neurons, and SP-positive nerve fibers. Relaxin prevented most of the smoking-induced changes in the ileum, while it was less effective in the colon. This study shows the diverse sensitivity to CS between the ileum and the colon and demonstrates that both VIP and SP are affected by smoking. The efficacy of relaxin proposes this hormone as a potential anti-inflammatory therapeutic to counteract gut damage in humans affected by inflammatory bowel diseases.

Impact of e-cigarettes on colonic mucosa and the role of recovery: involvement of oxidative and inflammatory pathway

Electronic cigarettes (e-cigarettes) (EC) are often advertised as a safer alternative to conventional cigarettes. Its widespread use has led to increased interest in its adverse health effects, thanks to few restrictions and a lack of regulatory guidelines. The study aimed to evaluate the influence of exposure to e-cigarette aerosol inhalation in rat colon model and conduct a follow-up after cessation of exposure. The experiment included 30 male adult Albino rats. The animals were divided into three groups: group I (control), non-exposed animals; group II (exposed), was exposed to electronic cigarette liquid vapor for four consecutive weeks; and group III (recovery), was followed up for another 4 weeks after exposure to an e-cigarette as exposed group and for the same duration. In the exposed group, malondialdehyde (MDA) and total nitric oxide (NO) increased significantly in colonic tissue, while superoxide dismutase (SOD) decreased. On histological examination, colonic mucosa showed distortion and loss of its epithelial lining with heavy inflammatory cell infiltration. Also, there was a significant decrease in periodic acid-Schiff-positive goblet cells and area percent of proliferating cell nuclear antigen expression. Tumor necrosis factor-alpha (TNFα) expression significantly increased in colonic mucosa. After 4 weeks of EC cessation, the colonic mucosal histological structure showed recovery with downregulated TNFα immunoexpression and restored oxidant/antioxidant balance. In conclusion, the usage of electronic cigarettes resulted in marked pathological alterations in the colonic mucosa, which could be attributed to oxidative and inflammatory stresses. In contrast, the cessation of exposure led to recovery.

Impact of 6-Month Exposure to Aerosols From Potential Modified Risk Tobacco Products Relative to Cigarette Smoke on the Rodent Gastrointestinal Tract

Cigarette smoking causes adverse health effects that might occur shortly after smoking initiation and lead to the development of inflammation and cardiorespiratory disease. Emerging studies have demonstrated the role of the intestinal microbiome in disease pathogenesis. The intestinal microbiome is susceptible to the influence of environmental factors such as smoking, and recent studies have indicated microbiome changes in smokers. Candidate modified risk tobacco products (CMRTP) are being developed to provide substitute products to lower smoking-related health risks in smokers who are unable or unwilling to quit. In this study, the ApoE^–/– mouse model was used to investigate the impact of cigarette smoke (CS) from the reference cigarette 3R4F and aerosols from two CMRTPs based on the heat-not-burn principle [carbon-heated tobacco product 1.2 (CHTP 1.2) and tobacco heating system 2.2 (THS 2.2)] on the intestinal microbiome over a 6-month period. The effect of cessation or switching to CHTP 1.2 after 3 months of CS exposure was also assessed. Next-generation sequencing was used to evaluate the impact of CMRTP aerosols in comparison to CS on microbiome composition and gene expression in the digestive tract of mice. Our analyses highlighted significant gene dysregulation in response to 3R4F exposure at 4 and 6 months. The findings showed an increase in the abundance of Akkermansiaceae upon CS exposure, which was reversed upon cessation. Cessation resulted in a significant decrease in Akkemansiaceae abundance, whereas switching to CHTP 1.2 resulted in an increase in Lactobacillaceae abundance. These microbial changes could be important for understanding the effect of CS on gut function and its relevance to disease pathogenesis via the microbiome.

Development of an Advanced Multicellular Intestinal Model for Assessing Immunomodulatory Properties of Anti-Inflammatory Compounds

Intestinal inflammation is the collective term for immune system-mediated diseases of unknown, multifactorial etiology, with often complex interactions between genetic and environmental factors. To mechanistically investigate the effect of treatment with compounds possessing immunomodulating properties in the context of intestinal inflammation, we developed an immunocompetent in vitro triculture intestinal model consisting of a differentiated intestinal epithelial layer (Caco-2/HT29-MTX) and immunocompetent cells (differentiated THP-1). The triculture mimicked a healthy intestine with stable barrier integrity. Lipopolysaccharide treatment triggered a controlled and reversible inflammatory state, resulting in significant impairment of barrier integrity and release of pro-inflammatory cytokines and chemokines, which are known hallmarks of intestinal inflammation. Treatment with known anti-inflammatory reference compounds (TPCA-1 and budenoside) prevented the induction of an inflammatory state; the decreasing triculture responses to this treatment measured by cytokine release, transepithelial electric resistance (TEER), and epithelial layer permeability proved the suitability of the intestinal model for anti-inflammatory drug screening. Finally, selected tobacco alkaloids (nicotine and anatabine (R/S and S forms)) were tested in the in vitro triculture for their potential anti-inflammatory properties. Indeed, naturally occurring alkaloids, such as tobacco-derived alkaloids, have shown substantial anti-inflammatory effects in several in vitro and in vivo models of inflammation, gaining increasing interest. Similar to the anti-inflammatory reference compounds, one of the tobacco alkaloids under investigation partially prevented the decrease in the TEER and increase in permeability and reduced the release of pro-inflammatory cytokines and chemokines. Taken together, these data confirm that our in vitro model is suitable for screening potential anti-inflammatory compounds in the context of intestinal inflammation.

Atherosclerosis and Inflammatory Bowel Disease-Shared Pathogenesis and Implications for Treatment

Atherosclerosis and inflammatory bowel disease (IBD) are often regarded as 2 distinct entities. The commonest manifestation of atherosclerosis is ischemic heart disease (IHD), and an association between IHD and IBD has been reported. Atherosclerosis and IBD share common pathophysiological mechanisms in terms of their genetics, immunology, and contributing environmental factors. Factors associated with atherosclerosis are implicated in the development of IBD and vice versa. Therefore, treatments targeting the common pathophysiology pathways may be effective in both conditions. The current review considers the pathophysiological pathways that are shared between the 2 conditions and discusses the implications for treatment and research.

Translational research into the effects of cigarette smoke on inflammatory mediators and epithelial TRPV1 in Crohn's disease

Crohn's disease is a pathological condition of the gastro-intestinal tract, causing severe transmural inflammation in the ileum and/or colon. Cigarette smoking is one of the best known environmental risk factors for the development of Crohn's disease. Nevertheless, very little is known about the effect of prolonged cigarette smoke exposure on inflammatory modulators in the gut. We examined the effect of cigarette smoke on cytokine profiles in the healthy and inflamed gut of human subjects and in the trinitrobenzene sulphonic acid mouse model, which mimics distal Crohn-like colitis. In addition, the effect of cigarette smoke on epithelial expression of transient receptor potential channels and their concurrent increase with cigarette smoke-augmented cytokine production was investigated. Active smoking was associated with increased IL-8 transcription in ileum of controls (p < 0,001; n = 18-20/group). In the ileum, TRPV1 mRNA levels were decreased in never smoking Crohn's disease patients compared to healthy subjects (p <0,001; n = 20/group). In the colon, TRPV1 mRNA levels were decreased (p = 0,046) in smoking healthy controls (n = 20/group). Likewise, healthy mice chronically exposed to cigarette smoke (n = 10/group) showed elevated ileal Cxcl2 (p = 0,0075) and colonic Kc mRNA levels (p = 0,0186), whereas TRPV1 mRNA and protein levels were elevated in the ileum (p = 0,0315). Although cigarette smoke exposure prior to trinitrobenzene sulphonic acid administration did not alter disease activity, increased pro-inflammatory cytokine production was observed in the distal colon (Kc: p = 0,0273; Cxcl2: p = 0,104; Il1-β: p = 0,0796), in parallel with the increase of Trpv1 mRNA (p < 0,001). We infer that CS affects pro-inflammatory cytokine expression in healthy and inflamed gut, and that the simultaneous modulation of TRPV1 may point to a potential involvement of TRPV1 in cigarette smoke-induced production of inflammatory mediators.

Review article: impact of cigarette smoking on intestinal inflammation-direct and indirect mechanisms

BACKGROUND

The inflammatory bowel diseases, Crohn's disease and ulcerative colitis are related multifactorial diseases. Their pathogenesis is influenced by each individual's immune system, the environmental factors within exposome and genetic predisposition. Smoking habit is the single best-established environmental factor that influences disease phenotype, behaviour and response to therapy.

AIM

To assess current epidemiological, experimental and clinical evidence that may explain how smoking impacts on the pathogenesis of inflammatory bowel disease.

METHODS

A Medline search for 'cigarette smoking', in combination with terms including 'passive', 'second-hand', 'intestinal inflammation', 'Crohn's disease', 'ulcerative colitis', 'colitis'; 'intestinal epithelium', 'immune system', 'intestinal microbiota', 'tight junctions', 'mucus', 'goblet cells', 'Paneth cells', 'autophagy'; 'epigenetics', 'genes', 'DNA methylation', 'histones', 'short noncoding/long noncoding RNAs'; 'carbon monoxide/CO' and 'nitric oxide/NO' was performed.

RESULTS

Studies found evidence of direct and indirect effects of smoking on various parameters, including oxidative damage, impairment of intestinal barrier and immune cell function, epigenetic and microbiota composition changes, that contribute to the pathogenesis of inflammatory bowel disease.

CONCLUSIONS

Cigarette smoking promotes intestinal inflammation by affecting the function and interactions among intestinal epithelium, immune system and microbiota/microbiome.

The reduction of DSS-induced colitis severity in mice exposed to cigarette smoke is linked to immune modulation and microbial shifts

Exposure to cigarette smoke (CS) causes detrimental health effects, increasing the risk of cardiovascular, pulmonary diseases and carcinogenesis in exposed individuals. The impact of CS on Inflammatory Bowel Disease (IBD) has been established by a number of epidemiological and clinical studies. In fact, CS is associated with a higher risk of developing Crohn’s disease (CD) while inversely correlates with the development, disease risks, and relapse rate of ulcerative colitis (UC). To investigate the effect of CS exposure on experimental colitis, we performed a comprehensive and integrated comparative analysis of colon transcriptome and microbiome in mice exposed to dextran sodium sulfate (DSS) and CS. Colon transcriptome analysis revealed that CS downregulated specific pathways in a concentration-dependent manner, affecting both the inflammatory state and composition of the gut microbiome. Metagenomics analysis demonstrated that CS can modulate DSS-induced dysbiosis of specific bacterial genera, contributing to resolve the inflammation or accelerate recovery. The risks of smoking far outweigh any possible benefit, thus smoking cessation must always be encouraged because of its significant health benefits. However, the inverse association between active smoking and the development of UC cannot be ignored and the present study lays the foundation for investigating potential molecular mechanisms responsible for the attenuation of colitis by certain compounds of tobacco when decoupled from combustion.

Cannabis use disorders may protect against certain disorders of the digestive organs in people with schizophrenia but not in healthy controls

BACKGROUND

Previous studies have shown a potential for cannabis in disorders of the digestive organs. We aimed to investigate whether cannabis use disorders (CUD) would decrease the risk of incident disorders of the digestive organs, in people with schizophrenia and population controls.

METHODS

We combined nationwide Danish registers to identify 21 066 cases with schizophrenia and 176 935 sex-and-age-matched controls. Two models were analyzed for the associations between CUD and digestive disorders in time-varying Cox regressions: one adjusted for sex, year of birth, and calendar year; and one further adjusted for alcohol and other substance use disorders and parental education.

RESULTS

CUD was associated with a decreased risk of developing disorders of gut-brain interaction (e.g. irritable bowel syndrome, dyspepsia, etc.) among cases with schizophrenia (HR = 0.84, 95% CI 0.74-0.94, p = 0.003). CUD was associated with decreased risk of inflammatory bowel disease (HR = 0.70, 95% CI 0.49-0.99, p = 0.045) in the basically adjusted model, dropping just below statistical significance in the fully adjusted model (HR = 0.71, 95% CI 0.48-1.03, p = 0.07). CUD displayed a tendency toward a decreased risk of serious disorders of the digestive organs among cases with schizophrenia (HR = 0.89, 95% CI 0.77-1.02, p = 0.09) in the fully adjusted model. No associations were observed among controls.

CONCLUSIONS

In people with schizophrenia, but not in controls, CUD is associated with decreased risk of disorders of gut-brain interaction and inflammatory bowel disease, and possibly other serious disorders of the digestive organs. Our findings could lead to new targets for treatment and prevention of disorders of the digestive organs.

Roles of nAChR and Wnt signaling in intestinal stem cell function and inflammation

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that signal using endogenous acetylcholine (ACh) and the agonist, nicotine. The nAChR signaling pathway is a central regulator of physiological homeostasis in the central and peripheral nervous systems. The receptors are expressed not only in the nervous system, but also play a pivotal role in regulation of epithelial cell growth, migration, differentiation, and inflammation processes in various mammalian non-neuronal cells. In the intestine, the Wnt signaling pathway plays a central role in the epithelium and is a principal regulator of intestinal stem cell (ISC) identity and proliferation. Since Wnt signaling was first described more than 40 years ago in ISCs, large amounts of scientific evidence have demonstrated remarkable long-term self-renewal capacity of ISCs. Intestinal organoids are commonly used for studying ISC biology and intestinal pathophysiology. The contribution of non-neuronal nAChR signaling to Wnt signaling in the intestine has received less attention. Experiments using cultured intestinal organoids that lack nerve and immune cells were performed. Endogenous ACh is synthesized in the intestinal epithelium and drives organoid growth and differentiation through activation of nAChR signaling. Furthermore, nAChR signaling is coordinated with Wnt signaling for regulation of ISC function. Elucidating the mechanism of the coordinated activities of nAChR and Wnt signaling in the intestine provides new insight into epithelial homeostasis, and may be of particular relevance in inflammatory bowel diseases such as ulcerative colitis and Crohn's disease.

Macrophage Depletion Protects against Cigarette Smoke-Induced Inflammatory Response in the Mouse Colon and Lung

Cigarette smoke (CS) is considered as a major risk factor for pulmonary and intestinal inflammation. CS leads to macrophage infiltration in the mucosae of the lung and colon, inducing the uncontrolled secretion of inflammatory mediators, and thus promoting inflammatory response. In this study, we investigated whether macrophage depletion modulates cigarette smoke (CS)-induced inflammatory response in both the lung and colon. The mice were exposed to CS for 30 min, after which they were rested in a fresh air environment for 30 min. The total duration of exposure to CS was 2 h per day for 4 weeks. Macrophage depletion state was made with the injection of clodronate containing liposome. Individual body weights were measured twice a week, and the mice were sacrificed on day 28. Hematoxylin and eosin (H&E) staining was performed in the lung and colon tissue to determine histological changes. Inflammatory mediators' synthesis was analyzed using ELISA and western blotting. Clodronate liposome treatment ameliorated pathological changes associated with the infiltration of immune cells in the lung and colon. Also, clodronate liposome injected mice showed significantly lower level of inflammatory mediators, including cytokines and chemokine and proteases. Our results indicated that macrophage depletion by clodronate liposome treatment attenuates CS-induced inflammatory response in both the lung and colon.

Cigarette Smoking Triggers Colitis by IFN-γ+ CD4+ T Cells

The increased incidence of Crohn’s disease in smokers has been recently reported, suggesting a strong association of cigarette smoke (CS) with colitis. However, the mechanism of the action of CS on colitis has not yet been explored. Here, we demonstrate that CS exposure is sufficient to induce colitis in mice. Interestingly, the colitis is mainly mediated by Th1, but not Th17, responses. CD4⁺ T-cell depletion or T-bet/IFN-γ deficiency protects against the development of colitis induced by CS. Additionally, IFN-γ-producing CD4⁺ T cells play a substantial role in CS-induced colitis. The adoptive transfer (AT) of effector T cells from CS-exposed WT mice into colitis-prone mice caused these mice to develop colitis, while the AT of effector T cells from IFN-γ knock-out mice did not. These findings have implications for broadening our understanding of CS-induced pathology and for the development of novel therapeutic strategies to treat Crohn’s disease.

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.

RNA-seq implicates deregulation of the immune system in the pathogenesis of diverticulitis

Individuals with diverticula or outpouchings of the colonic mucosa and submucosa through the colonic wall have diverticulosis, which is usually asymptomatic. In 10-25% of individuals, the diverticula become inflamed, resulting in diverticulitis. Very little is known about the pathophysiology or gene regulatory pathways involved in the development of diverticulitis. To identify these pathways, we deep sequenced RNAs isolated from full-thickness sections of sigmoid colon from diverticulitis patients and control individuals. Specifically for diverticulitis cases, we analyzed tissue adjacent to areas affected by chronic disease. Since the tissue was collected during elective sigmoid resection, the disease was in a quiescent state. A comparison of differentially expressed genes found that gene ontology (GO) pathways associated with the immune response were upregulated in diverticulitis patients compared with nondiverticulosis controls. Next, weighted gene coexpression network analysis was performed to identify the interaction among coexpressed genes. This analysis revealed RASAL3, SASH3, PTPRC, and INPP5D as hub genes within the brown module eigengene, which highly correlated (r = 0.67, P = 0.0004) with diverticulitis. Additionally, we identified elevated expression of downstream interacting genes. In summary, transcripts associated with the immune response were upregulated in adjacent tissue from the sigmoid colons of chronic, recurrent diverticulitis patients. Further elucidating the genetic or epigenetic mechanisms associated with these alterations can help identify those at risk for chronic disease and may assist in clinical decision management.NEW & NOTEWORTHY By using an unbiased approach to analyze transcripts expressed in unaffected colonic tissues adjacent to those affected by chronic diverticulitis, our study implicates that a defect in the immune response may be involved in the development of the disease. This finding expands on the current data that suggest the pathophysiology of diverticulitis is mediated by dietary, age, and obesity-related factors. Further characterizing the immunologic differences in diverticulitis may better inform clinical decision-making.

The intestinal barrier: a fundamental role in health and disease

The gastrointestinal mucosa constitutes a critical barrier where millions of microbes and environmental antigens come in close contact with the host immune system. Intestinal barrier defects have been associated with a broad range of diseases and therefore denote a new therapeutic target. Areas covered: This review is based on an extensive literature search in PubMed of how the intestinal barrier contributes to health and as a trigger for disease. It discusses the anatomy of the intestinal barrier and explains the available methods to evaluate its function. Also reviewed is the importance of diet and lifestyle factors on intestinal barrier function, and three prototypes of chronic diseases (inflammatory bowel disease, celiac disease and nonalcoholic fatty liver disease) that have been linked to barrier defects are discussed. Expert commentary: The intestinal barrier has been investigated by various methods, but correlation of results across studies is difficult, representing a major shortcoming in the field. New upcoming techniques and research on the effect of barrier-restoring therapeutics may improve our current understanding of the gut barrier, and provide a step forward towards personalised medicine.

Late radiation-induced bowel syndromes, tobacco smoking, age at treatment and time since treatment - gynecological cancer survivors

BACKGROUND

It is unknown whether smoking; age at time of radiotherapy or time since radiotherapy influence the intensity of late radiation-induced bowel syndromes.

MATERIAL AND METHODS

We have previously identified 28 symptoms decreasing bowel health among 623 gynecological-cancer survivors (three to twelve years after radiotherapy) and 344 matched population-based controls. The 28 symptoms were grouped into five separate late bowel syndromes through factor analysis. Here, we related possible predictors of bowel health to syndrome intensity, by combining factor analysis weights and symptom frequency on a person-incidence scale.

RESULTS

A strong (p < .001) association between smoking and radiation-induced urgency syndrome was found with a syndrome intensity (normalized factor score) of 0.4 (never smoker), 1.2 (former smoker) and 2.5 (current smoker). Excessive gas discharge was also related to smoking (p = .001). Younger age at treatment resulted in a higher intensity, except for the leakage syndrome. For the urgency syndrome, intensity decreased with time since treatment.

CONCLUSIONS

Smoking aggravates the radiation-induced urgency syndrome and excessive gas discharge syndrome. Smoking cessation may promote bowel health among gynecological-cancer survivors. Furthermore, by understanding the mechanism for the decline in urgency-syndrome intensity over time, we may identify new strategies for prevention and alleviation.

Recent Trends in Pharmacological Activity of Alkaloids in Animal Colitis: Potential Use for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic and disrupted inflammation of the gastrointestinal tract. IBD have two main conditions, Crohn's disease and ulcerative colitis, and have been extensively investigated in recent years. Antibiotics derived from salicylates, steroids, immunosuppressors, and anti-TNF therapy are part of the therapeutic arsenal for IBD. However, very often patients stop responding to treatments over the time. In this context, searching for alternative agents is crucial for IBD clinical management. Natural products derived from medicinal plants are an interesting therapeutic alternative, since several studies have proven effective treatments in animal models of intestinal inflammation. Several naturally occurring compounds are potent antioxidants, both as free radical scavengers and as modulators of antioxidant enzymes expression and activity. A number of natural compounds have also been proved to inhibit the release of proinflammatory cytokines, decreasing the activation of nuclear factor κB (NF-κB), which is important to the inflammatory response in IBD. The alkaloids are substances of a very diverse class of plant secondary metabolites; an extensive list of biological activities has been attributed to alkaloids, such as being anticholinergic, antitumor, diuretic, antiviral, antihypertensive, antiulcer, analgesic, and anti-inflammatory. In the present work, studies on the pharmacological activity of alkaloids in experimental models of IBD were reviewed.

pH-Sensitive metal-free carbon monoxide prodrugs with tunable and predictable release rates

Carbon monoxide prodrugs with triggered release profiles are highly desirable for targeted CO delivery to minimize their untoward side-effects.

Linking Smoking, Coffee, Urate, and Parkinson's Disease - A Role for Gut Microbiota?

While the etiology and pathogenesis of Parkinson's disease (PD) is still obscure, there is evidence for lifestyle factors influencing disease risk. Best established are the inverse associations with smoking and coffee consumption. In other contexts there is evidence that health effects of lifestyle factors may depend on gut microbiome composition. Considering the gastrointestinal involvement in PD, it was recently speculated, that the associations between smoking, coffee, and PD risk could be mediated by gut microbiota. Here we review such a possible mediatory role of gut microbiota taking into account recent findings on microbiome composition in PD and extending the scope also to urate.

Genetics and Pathogenesis of Inflammatory Bowel Disease

We are currently in an exciting time when our understanding of genetic underpinnings of inflammatory bowel disease (IBD) has undergone a revolution, based in large part on novel genotyping and sequencing technologies. With >160 susceptible loci identified for IBD, the goal is now to understand at a fundamental level the function of these susceptibility alleles. Determining the clinical relevance of how these susceptible genes shape the development of IBD is also a high priority. The main challenge is to understand how the environment and microbiome play a role in triggering disease in genetically susceptible individuals, as the interactions may be complex. To advance the field, novel in vitro and mouse models that are designed to interrogate complex genetics and functionally test hypotheses are needed. Ultimately, the goal of genetics studies will be to translate genetics to patients with IBD and improve their care.

Diarrhoea and smoking: an analysis of decades of observational data from Bangladesh

BACKGROUND

Although cigarette smoking affects all biological systems of the human body including the gastrointestinal tract, there is a lack of evidence regarding its effect on the severity of diarrhoeal disease and whether a dose-response relationship exists. We therefore tested for the presence of specific causative pathogens for infectious diarrhoea, assessed the independent effect of smoking on its severity and tested whether any dose-response relationship existed while controlling for subjects' age, sociodemographic characteristics and presence of causative pathogens in an urban setting in Bangladesh.

METHODS

A total of 20,757 patients aged 15 years and above with diarrhoea were enrolled into the Diarrhoeal Disease Surveillance System, managed by the International Centre for Diarrhoeal Disease Research, Bangladesh, from 1993 to 2012. We collected data on individuals' current daily consumption of cigarettes and bidis (traditional hand-rolled cigarettes) and conducted an ordered logistic regression to determine the effect of smoking on diarrhoeal disease severity and whether a dose-response relationship exists.

RESULTS

We identified 19 % of patients with diarrhoea as smokers, of whom 52 % smoked 1-9 cigarettes per day. While 97 % of smokers were male, 41 % were aged 15-30 years of age. Smokers were found to have a significantly lower severity of diarrhoeal disease (OR: 0.92, 95 % CI: 0.85-0.99, p = 0.025) after adjusting for age, wealth quintile, illiteracy and the presence of specific causative pathogens (Vibrio cholerae and Shigella). We observed no dose-response relationship between the number of cigarettes smoked per day and disease severity when adjusting for the same covariates. Smokers were more frequently infected with Shigella (7 vs. 6 %, p < 0.001) and less often with Vibrio cholerae (22 vs. 26 %, p < 0.001) than their non-smoking counterparts.

CONCLUSIONS

The aetiology and severity of diarrhoeal disease differed between smokers and non-smokers in our sample. However, we found no dose-response relationship between disease severity and the number of cigarettes smoked per day.

Inflammatory bowel disease in an underdeveloped region of Northeastern Brazil

AIM: To evaluate the demographic characteristics and clinical phenotypes of inflammatory bowel disease (IBD) in a geographic area in Northeastern Brazil.

METHODS: This retrospective study was conducted at the Hospital of the Federal University of Piauí in Northeastern Brazil. Demographic characteristics and clinical phenotypes of IBD were analyzed in relation to the time of diagnostic confirmation, which was defined as the date of disease onset. Data were collected between January 2011 and December 2012 and included all census patients 18 years of age or older during that period for whom there was diagnostic confirmation of Crohn’s disease (CD), ulcerative colitis (UC), or unclassified colitis according to the Montreal criteria. We also analyzed the period of time between the onset of clinical manifestations and the diagnosis of IBD (delay in the diagnosis). Statistical analyses included means and standard deviations for numeric variables and the Pearson χ² adherence test for nominal variables. The annual index occurrence and overall prevalence of IBD at our institution were also calculated, with P values < 0.05 indicating statistical significance. This study was approved by the Institutional Ethics and Research Committee.

RESULTS: A total of 252 patients with IBD were included, including 152 (60.3%) UC patients and 100 (39.7%) CD patients. The clinical and demographic characteristics of all patients with IBD showed a female to male ratio of 1.3:1.0 and a mean age of 35.2 (SD = 14.5) years. In addition, the majority of patients were miscegenated (171, 67.9%), had received higher education (157, 62.4%), lived in urban areas (217, 86.1%), and were under the age of 40 years (97, 62.5%). For patients with CD, according to the Montreal classification, the predominant features present from the onset of disease were an age between 17 and 40 years (A2); colonic disease location (L2); and nonstricturing, nonfistulizing disease behavior (B1). However, approximately one-quarter of all CD patients demonstrated perineal involvement. We also observed considerable delay in the diagnosis of IBD throughout the entire study period (mean = 35.5 mo). In addition, the annual index occurrence rose from 0.08 to 1.53 cases/10⁵ inhabitants/year during the study period, and the prevalence rate was 12.8 cases/10⁵ inhabitants in 2012. Over the last two decades, there was a noted increase in the frequency of IBD in the study area.

CONCLUSION: In this study, there was a predominance of patients with UC, young people under 40 years of age, individuals with racial miscegenation, and low annual incomes.

Cigarette smoking is associated with intestinal barrier dysfunction in the small intestine but not in the large intestine of mice

AIMS

To observe the effect of cigarette smoke (CS) on the small bowel and colon in mice and to attempt to explain the potential mechanisms that account for these effects.

METHODS

Male BALB/c mice age 6-8 weeks were randomly divided into a CS group and a control group (n=10 per group). CS mice were exposed to CS (five cigarettes each time, four times a day for 5 days a week using Hamburg II smoking machine and CS was diluted with air at a ratio of 1:6) for 10 weeks, and control mice were exposed to room air. After 10 weeks, mice were sacrificed for analysis (colon and small bowel).

RESULTS

CS exposure impaired the intestinal barrier of the small bowel, based on evidence that CS mice exhibited increased intestinal permeability, bacterial translocation, intestinal villi atrophy, damaged tight junctions and abnormal tight junction proteins. These changes were partly mediated through the activated NF-κB (p65) signalling pathway. However, no obvious changes associated with the intestinal barrier were identified in the small bowel of control mice or the colons of control or CS mice.

CONCLUSIONS

CS is associated with intestinal barrier dysfunction in the small intestine but not in the large intestine of mice.

Colonic inflammation in mice is improved by cigarette smoke through iNKT cells recruitment

Cigarette smoke (CS) protects against intestinal inflammation during ulcerative colitis. Immunoregulatory mechanisms sustaining this effect remain unknown. The aim of this study was to assess the effects of CS on experimental colitis and to characterize the intestinal inflammatory response at the cellular and molecular levels. Using the InExpose® System, a smoking device accurately reproducing human smoking habit, we pre-exposed C57BL/6 mice for 2 weeks to CS, and then we induced colitis by administration of dextran sodium sulfate (DSS). This system allowed us to demonstrate that CS exposure improved colonic inflammation (significant decrease in clinical score, body weight loss and weight/length colonic ratio). This improvement was associated with a significant decrease in colonic proinflammatory Th1/Th17 cytokine expression, as compared to unexposed mice (TNF (p=0.0169), IFNγ (p<0.0001), and IL-17 (p=0.0008)). Smoke exposure also induced an increased expression of IL-10 mRNA (p=0.0035) and a marked recruitment of iNKT (invariant Natural Killer T; CD45+ TCRβ+ CD1d tetramer+) cells in the colon of DSS-untreated mice. Demonstration of the role of iNKT cells in CS-dependent colitis improvement was performed using two different strains of NKT cells deficient mice. Indeed, in Jα18KO and CD1dKO animals, CS exposure failed to induce significant regulation of DSS-induced colitis both at the clinical and molecular levels. Thus, our study demonstrates that iNKT cells are pivotal actors in the CS-dependent protection of the colon. These results highlight the role of intestinal iNKT lymphocytes and their responsiveness to environmental stimuli. Targeting iNKT cells would represent a new therapeutic way for inflammatory bowel diseases.

Smoking is a risk factor for recurrence of intestinal stricture after endoscopic dilation in Crohn's disease

BACKGROUND

Endoscopic balloon dilation is an efficacious and safe alternative to surgery as treatment of short intestinal strictures in Crohn's disease (CD). Factors predicting outcome of the procedure are not well described.

AIM

To evaluate whether smoking at diagnosis, treatment with azathioprine, or other clinical variables may affect clinical outcome after endoscopic dilation. The endpoint was requirement of a new intervention such as dilation or surgery with intestinal resection or strictureplasty.

METHODS

Retrospective study of 83 patients with CD who underwent endoscopic balloon dilation of an intestinal stricture between 1987 and 2009.

RESULTS

After index dilation 55/83 patients underwent a new intervention. Among current smokers, 31/32 (97%) underwent another intervention compared to 18/33 (55%) among never smokers (adjusted HR: 2.50, 95% CI: 1.14-5.50, P = 0.022). After 5 years, cumulative probability of new intervention was 0.81 in smokers compared to 0.52 in never smokers; difference 0.29 (95% CI: 0.07-0.52, P = 0.01). In 16 patients, therapy with azathioprine was initiated before or shortly after the index dilation; 7/16 underwent a new intervention compared to 48/67 of those without azathioprine (HR: 0.46, 95% CI: 0.21-1.03, P = 0.06). After adjustment for other variables, the association was even weaker (HR: 0.80, 95% CI: 0.29-2.18, P = 0.668). Sex, age at diagnosis, age at first dilation, balloon size, location of stricture, and treatment period did not influence outcome.

CONCLUSIONS

Smoking doubles the risk of recurrent stricture formation requiring a new intervention after index dilation. Maintenance therapy with azathioprine did not influence the subsequent course and need for a new intervention.

[Psoriasis and inflammatory bowel diseases]

Psoriasis and inflammatory bowel diseases (Crohn's disease and ulcerative colitis) are among the immune-mediated inflammatory diseases. This group includes approximately 80 disorders, some of which can at times be associated in a single patient. In psoriasis, Crohn's disease may be observed slightly more frequently, but ulcerative colitis and celiac disease are also an issue. The underlying relations between these disorders comprise: i) genetic data obtained by genome-wide association studies that show the involvement of shared predisposing loci and/or genes, for example, in innate immunity; ii) immunological data: these disorders share inflammation effector mechanisms, particularly the activation pathway of Th17 lymphocytes, which explains the efficacy of anti-TNF antibodies and anti-IL-12/23; and iii) environmental co-factors such as smoking, possibly certain food proteins (gliadin, etc.), and bacterial infections that are probably decisive elements in the genesis of these diseases.