Cigarette smoking associates inversely with a cluster of two autoimmune diseases: ulcerative colitis and pemphigus

Autoimmune pre-disease

Approximately 5% of the world-wide population is affected by autoimmune diseases. Overall, autoimmune diseases are still difficult to treat, impose a high burden on patients, and have a significant economic impact. Like other complex diseases, e.g., cancer, autoimmune diseases develop over several years. Decisive steps in the development of autoimmune diseases are (i) the development of autoantigen-specific lymphocytes and (often) autoantibodies and (ii) potentially clinical disease manifestation at a later stage. However, not all healthy individuals with autoantibodies develop disease manifestations. Identifying autoantibody-positive healthy individuals and monitoring and inhibiting their switch to inflammatory autoimmune disease conditions are currently in their infancy. The switch from harmless to inflammatory autoantigen-specific T and B-cell and autoantibody responses seems to be the hallmark for the decisive factor in inflammatory autoimmune disease conditions. Accordingly, biomarkers allowing us to predict this progression would have a significant impact. Several factors, such as genetics and the environment, especially diet, smoking, exposure to pollutants, infections, stress, and shift work, might influence the progression from harmless to inflammatory autoimmune conditions. To inspire research directed at defining and ultimately targeting autoimmune predisease, here, we review published evidence underlying the progression from health to autoimmune predisease and ultimately to clinically manifest inflammatory autoimmune disease, addressing the following 3 questions: (i) what is the current status, (ii) what is missing, (iii) and what are the future perspectives for defining and modulating autoimmune predisease.

Nature's marvels endowed in gaseous molecules I: Carbon monoxide and its physiological and therapeutic roles

Nature has endowed gaseous molecules such as O2, CO2, CO, NO, H2S, and N2 with critical and diverse roles in sustaining life, from supplying energy needed to power life and building blocks for life's physical structure to mediating and coordinating cellular functions. In this article, we give a brief introduction of the complex functions of the various gaseous molecules in life and then focus on carbon monoxide as a specific example of an endogenously produced signaling molecule to highlight the importance of this class of molecules. The past twenty years have seen much progress in understanding CO's mechanism(s) of action and pharmacological effects as well as in developing delivery methods for easy administration. One remarkable trait of CO is its pleiotropic effects that have few parallels, except perhaps its sister gaseous signaling molecules such as nitric oxide and hydrogen sulfide. This review will delve into the sophistication of CO-mediated signaling as well as its validated pharmacological functions and possible therapeutic applications.

A brief history of carbon monoxide and its therapeutic origins

It is estimated that 10% of carbon throughout the cosmos is in the form of carbon monoxide (CO). Earth's earliest prebiotic atmosphere included the trinity of gasotransmitters CO, nitric oxide (NO), and hydrogen sulfide (H₂S), for which all of life has co-evolved with. The history of CO can be loosely traced to mythological and prehistoric origins with rudimentary understanding emerging in the middle ages. Ancient literature is focused on CO's deadly toxicity which is understandable in the context of our primitive relationship with coal and fire. Scientific inquiry into CO appears to have emerged throughout the 1700s followed by chemical and toxicological profiling throughout the 1800s. Despite CO's ghastly reputation, several of the 18th and 19th century scientists suggested a therapeutic application of CO. Since 2000, the fundamental understanding of CO as a deadly nuisance has undergone a paradigm shift such that CO is now recognized as a neurotransmitter and viable pharmaceutical candidate. This review is intended to provide a brief history on the trace origins pertaining to endogenous formation and therapeutic application of CO.

Estimating the Odds of Ulcerative Colitis-Associated Pyoderma Gangrenosum: A Population-Based Case-Control Study

BACKGROUND

Ulcerative colitis (UC) is a well-known underlying comorbidity of pyoderma gangrenosum (PG). However, the risk conferred by UC for the subsequent development of PG is yet to be elucidated. We aimed to estimate the magnitude of the association between UC and the subsequent occurrence of PG, which would enable us to assess the odds of PG developing in individuals with a history of UC.

METHODS

A population-based case-control study was conducted to compare PG patients (n = 302) and age-, sex- and ethnicity-matched control subjects (n = 1,497) regarding the presence of UC. Logistic regression models were utilized for univariate and multivariate analyses.

RESULTS

The prevalence of preexisting UC was greater in patients with PG than in controls (7.3 vs. 0.5%; p < 0.001). A 15-fold increase in the odds of PG in individuals with preexisting UC was observed (OR 14.62, 95% CI 6.45-33.18). The greatest risk of developing PG occurred in the first years following the diagnosis of UC (OR 35.50, 95% CI 4.35-289.60), and decreased thereafter to 10.03 (95% CI 1.83-55.03), 6.69 (95% CI 1.49-30.02), and 10.03 (95% CI 1.83-55.03) at 1-5, 5-10, and 10-15 years after the diagnosis of UC, respectively. This association retained its statistical significance following the adjustment for confounding factors (adjusted OR 10.78, 95% CI 4.55-25.52). Patients with both PG and UC were younger and had a lower prevalence of smoking than the remaining patients with PG.

CONCLUSIONS

UC increases the odds of developing PG by 15-fold, with the highest probability of developing PG occurring within the first year after the diagnosis of UC. Patients with UC may be advised to avoid additional precipitating factors for the development of PG.

Role of Carbon Monoxide in Host-Gut Microbiome Communication

Nature is full of examples of symbiotic relationships. The critical symbiotic relation between host and mutualistic bacteria is attracting increasing attention to the degree that the gut microbiome is proposed by some as a new organ system. The microbiome exerts its systemic effect through a diverse range of metabolites, which include gaseous molecules such as H₂, CO₂, NH₃, CH₄, NO, H₂S, and CO. In turn, the human host can influence the microbiome through these gaseous molecules as well in a reciprocal manner. Among these gaseous molecules, NO, H₂S, and CO occupy a special place because of their widely known physiological functions in the host and their overlap and similarity in both targets and functions. The roles that NO and H₂S play have been extensively examined by others. Herein, the roles of CO in host-gut microbiome communication are examined through a discussion of (1) host production and function of CO, (2) available CO donors as research tools, (3) CO production from diet and bacterial sources, (4) effect of CO on bacteria including CO sensing, and (5) gut microbiome production of CO. There is a large amount of literature suggesting the "messenger" role of CO in host-gut microbiome communication. However, much more work is needed to begin achieving a systematic understanding of this issue.

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.

Association between vitiligo and smoking: A nationwide population-based study in Korea

No study has examined the associations between vitiligo and smoking. The purpose of this study was to investigate the incidence of vitiligo according to smoking status. We used clinical data from individuals aged over 20 years who received a health examination in the National Insurance Program between 2009 and 2012 (n = 23,503,807). We excluded individuals with pre-existing vitiligo who had ever been diagnosed with vitiligo before the index year (n = 35,710) or who were diagnosed with vitiligo within a year of the index year (n = 46,476). Newly diagnosed vitiligo was identified using claims data from baseline to date of diagnosis or December 31, 2016 (n = 22,811). The development of vitiligo was compared according to self-reported smoking status by a health examination survey. The hazard ratio of vitiligo in current smokers was 0.69 (95% confidence interval; 0.65-0.72) with a reference of never-smokers after adjustment for age, sex, regular exercise, drinking status, body mass index, diabetes mellitus, hypertension, dyslipidemia, history of stroke, and history of ischemic heart diseases. The decreased risk of vitiligo in current smokers persisted after subgroup analysis of sex and age groups. The results suggested there are suppressive effects of smoking on the development of vitiligo. Further studies are needed to evaluate the mechanism of smoking on the development of vitiligo.

Alopecia Areata Is Associated with Atopic Diathesis: Results from a Population-Based Study of 51,561 Patients

BACKGROUND

Evidence of T_H1/IFN-γ overactivation as a major pathogenic driver somewhat conflicts with data supporting robust allergic background in patients with alopecia areata (AA). Previous investigations of immunological dysregulations show that both T_H1- and T_H2-related markers are overexpressed in AA. Clinical correlations in large populations may shed light on the immune pathways most likely to result in the clinical phenotype of AA.

OBJECTIVE

To investigate the atopic comorbidities among patients with AA in a large population-based study.

METHODS

This is a cross-sectional retrospective study of patients with AA and a matched comparison group, analyzing the associations between AA and 4 atopic comorbidities: asthma, atopic dermatitis (AD), allergic rhinitis, and allergic conjunctivitis. χ² and t tests were used for univariate analysis, and logistic regression model was used for multivariate analysis. The study was performed using the computerized database of the Clalit Health Services, encompassing more than 4.4 million subjects.

RESULTS

The study population included 51,561 patients with AA and 51,410 matched control subjects. The prevalence of asthma (7.8% vs 6.5%; odds ratio [OR], 1.22; 95% CI, 1.17-1.28; P < .001), AD (3.9% vs 2.6%; OR, 1.55; 95% CI, 1.44-1.66; P < .001), allergic rhinitis (16.0% vs 12.8%; OR, 1.29; 95% CI, 1.25-1.34; P < .001), and allergic conjunctivitis (23.5% vs 19.6%; OR, 1.27; 95% CI, 1.23-1.30; P < .001) was significantly higher among patients with AA as compared with matched control subjects. Patients with AA also had a significantly higher probability of having more than 1 atopic comorbidity, with increasing OR as the number of concomitant atopic conditions increased.

CONCLUSIONS

Our analysis supports the previous literature and provides strong generalizability of significant atopy in patients with AA, suggesting T_H2 pathogenicity in AA, and challenging the traditional view of AA as a single-axis, T_H1-centered disease.

Gut Inflammation in Association With Pathogenesis of Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disease that is generally thought to be caused by multiple factors, including environmental and genetic factors. Emerging evidence suggests that intestinal disturbances, such as constipation, are common non-motor symptoms of PD. Gut inflammation may be closely associated with pathogenesis in PD. This review aims to discuss the cross-talk between gut inflammation and PD pathology initiation and progression. Firstly, we will highlight the studies demonstrating how gut inflammation is related to PD. Secondly, we will analyze how gut inflammation spreads from the gastro-intestine to the brain. Here, we will mainly discuss the neural pathway of pathologic α-syn and the systemic inflammatory routes. Thereafter, we will address how alterations in the brain subsequently lead to dopaminergic neuron degeneration, in which oxidative stress, glutamate excitotoxicity, T cell driven inflammation and cyclooxygenase-2 (COX-2) are involved. We conclude a model of PD triggered by gut inflammation, which provides a new angle to understand the mechanisms of the disease.

Clustering of immune-mediated diseases in sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is an immune-mediated disease of unknown cause. Immune-mediated diseases appear to cluster in patients and in families. We review what is known on this topic for sarcoidosis, and what factors may underlie disease clustering.

RECENT FINDINGS

In populations of patients with sarcoidosis, relative risk estimates of Sjögren's syndrome, systemic lupus erythematosus, autoimmune hepatitis, ankylosing spondylitis, multiple sclerosis (MS), celiac disease, autoimmune thyroid disease, and ulcerative colitis, varied between 2.1 and 11.6. In relatives of patients with sarcoidosis, relative risk estimates varied between 1.3 and 5.8 for sarcoidosis, MS, celiac disease, type 1 diabetes, Graves' disease, rheumatoid arthritis, Crohn's disease, and ulcerative colitis. Shared risk loci in key immunological pathways provide evidence for a contribution to development of multiple diseases. Identical changes in the immune status, epigenetic alterations, and environmental triggers have been detected in several diseases, and drug-induced disease is likely responsible for a small portion of co-occurring disease.

SUMMARY

Clustering of sarcoidosis and other immune-mediated diseases in patients and in their relatives occurs for sarcoidosis, MS, celiac disease, Graves' disease, and ulcerative colitis. Further research is needed to substantiate causal links and risk estimates in patients and their relatives.