Microscopic colitis in patients with mild duodenal damage: A new clinical and pathological entity (“lymphocytic enterocolitis”)?

Microscopic Colitis and Celiac Disease: Sharing More than a Diagnostic Overlap

Microscopic colitis (MC) is an emergent group of chronic inflammatory diseases of the colon, and celiac disease (CD) is a chronic gluten-induced immune-mediated enteropathy affecting the small bowel. We performed a narrative review to provide an overview regarding the relationship between both disorders, analyzing the most recent studies published at the epidemiological, clinical and pathophysiological levels. In fact, MC and CD are concomitantly prevalent in approximately 6% of the cases, mainly in the subset of refractory patients. Thus, physicians should screen refractory patients with CD against MC and vice versa. Both disorders share more than a simple epidemiological association, being multifactorial diseases involving innate and adaptive immune responses to known or unknown luminal factors based on a rather common genetic ground. Moreover, autoimmunity is a shared characteristic between the patients with MC and those with CD, with autoimmunity in the latter being quite well-established. Furthermore, CD and MC share some common clinical symptoms and risk factors and overlap with other gastrointestinal diseases, but some differences exist between both disorders. More studies are therefore needed to better understand the complex mechanisms involving the common pathogenetic ground contributing to the CD and MC epidemiological association.

Epidemiology of Nonesophageal Eosinophilic Gastrointestinal Diseases in Symptomatic Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Primary eosinophilic gastrointestinal diseases (EGIDs) are increasingly described disorders that include eosinophilic esophagitis (EoE), eosinophilic gastritis, gastroenteritis, and colitis. The exact epidemiology of nonesophageal EGIDs (non-EoE EGIDs) is still unclear.

OBJECTIVE

To evaluate the epidemiology of non-EoE EGIDs in adults and children referred to outpatient clinics for gastrointestinal symptoms.

METHODS

We conducted a systematic review and meta-analysis using a protocol registered and published with the international prospective register of systematic reviews (PROSPERO CRD42018111437). We searched PubMed, EMBASE, Web of Science, Scopus, and CINAHL for cohort or cross-sectional studies published since 1990, evaluating the incidence and prevalence of non-EoE EGIDs. We assessed study quality and risk of bias using items derived from the Strengthening the Reporting of Observational Studies in Epidemiology statement.

RESULTS

A total of 576 articles were identified. Ten studies with 13,377 participants were included in the analysis, with the results showing high heterogeneity. No significant publication bias was found. The overall prevalence of non-EoE EGIDs in patients with gastrointestinal symptoms was 1.9% (95% confidence interval: 0.575-3.894; I2 = 92.72%; P < .001). Because none of the examined studies were prospectively designed, incidence rates could not be determined.

CONCLUSIONS

More prospective, large-scale, multicenter studies are needed to evaluate reported data and to further investigate the epidemiology of non-EoE EGIDs and their possible risk factors and comorbidities.

Microscopic colitis: a narrative review with clinical approach

Microscopic colitis (MC) is diagnosed in presence of microscopic alterations of colonic mucosa, in patients without macroscopic lesions who referred for chronic diarrhea. The two types of MC are lymphocytic colitis (LC) and collagenous colitis (CC), but it is unclear whether these are the different expression of one unique disease or if they are distinct conditions. Today, although MC represents a consistent health problem, being responsible for a large part of gastroenterological consultations for diarrhea, it remains often underestimated. The detailed pathogenesis of MC has not been determined yet. Probably, it is the result of an interaction between individual, environmental and genetic factors. The most relevant risk factor for the development of MC is the use of certain drugs (such as non-steroidal anti-inflammatory drugs [NSAIDs], proton pump inhibitors [PPIs], selective serotonin reuptake inhibitors, beta-blockers, statins). Smoking is another relevant factor reported as associated with the development of MC. Diagnosis needs the execution of a colonoscopy in patients complaining about chronic diarrhea and abdominal pain. The crucial role is played by histology: MC is characterized by the presence of colonic mucosal lymphocytic infiltrate, with intraepithelial lymphocytes ≥20 per 100 enteric surface cells, in CC there is a typical subepithelial collagen layer, whose thickness is ≥10 μm. We carried out a review of the current literature to rule out what is new on epidemiology, diagnosis and therapy of MC.

Microscopic colitis-microbiome, barrier function and associated diseases

Microscopic colitis (MC) is a chronic inflammatory bowel disease (IBD) with little in terms of endoscopic abnormalities and is frequently associated with other autoimmune diseases. The peak incidence of the disease is in middle aged or older populations, mostly females. The pathogenesis of MC is complex, multifactorial and poorly understood. Current concepts revolve around innate immunity or microbiome alterations as well as gut barrier dysfunction, all of which lead to the development of subtle inflammatory lesions in gut mucosa. The results of numerous basic and clinical studies involving molecular techniques as well as advanced endoscopic imaging revealed the important role of both intrinsic (e.g., hormonal) as well as extrinsic (e.g., NSAIDs and PPIs) factors in the modulation of gastrointestinal microbiome and MC pathogenesis. Capsule endoscopy as well confocal endomicroscopy imaging, alongside standard endoscopic techniques offer new tools in the evaluation of MC patients and allow their better stratification for novel treatment protocols based on modulation of gut microbiome and barrier function.