Microscopic colitis-microbiome, barrier function and associated diseases

Mechanisms and clinical management of eosinophilic oesophagitis: an overview

Since the first description of eosinophilic oesophagitis (EoE) less than three decades ago, we have observed a striking increase in the number of patients diagnosed with EoE and the understanding of its clinical and immunopathogenic background. Nonetheless, a plethora of open questions await elucidation. In this Review, we discuss the current state of knowledge regarding the underlying mechanisms, particularly environmental factors and their interaction with genetic susceptibility. Subsequently, we discuss how to translate these factors into the diagnostic and therapeutic management of this chronic, immune-mediated disorder. Finally, we dissect the still long list of unmet needs, such as reasons for and handling refractory EoE and atypical clinical presentations. These open questions can guide us through future research steps and potentially foster reconsideration of the diagnostic guidelines of EoE.

Microscopic colitis: Etiopathology, diagnosis, and rational management

Microscopic colitis is an inflammatory bowel disease divided into two subtypes: collagenous colitis and lymphocytic colitis. With an increasing incidence of microscopic colitis exceeding those of ulcerative and Crohn's disease among elderly people in some countries, microscopic colitis is a debilitating life experience. Therefore, physicians should be familiar with its clinical features and management strategies because the disease deserves the same attention as the classical inflammatory bowel diseases. Here, state-of-the-art knowledge of microscopic colitis is provided from a global perspective with reference to etiopathology and how to establish the diagnosis with the overall aim to create awareness and improve rational management in clinical practice. The immune system and a dysregulated immune response seem to play a key role combined with risk factors (e.g. cigarette smoking) in genetically predisposed individuals. The symptoms are characterized by recurrent or chronic nonbloody, watery diarrhea, urgency, weight loss, and a female preponderance. As biomarkers are absent, the diagnosis relies on colonoscopy with a histological assessment of biopsy specimens from all parts of the colon. Although the disease is not associated with a risk of colorectal cancer, a recent nationwide, population-based cohort study found an increased risk of lymphoma and lung cancer. Budesonide is the first-line therapy for management, whereas immunomodulatory drugs (including biologics) and drugs with antidiarrheal properties may be indicated in those failing, dependent, or intolerant to budesonide. In microscopic colitis induced by checkpoint inhibitors, a drug class used increasingly for a wide range of malignancies, a more aggressive therapeutic approach with biologics introduced early seems reasonable. However, particular attention needs to be drawn to the existence of incomplete forms of microscopic colitis with the risk of being overlooked in routine clinical settings.

Bacteria and bacterial derivatives as delivery carriers for immunotherapy

There is growing interest in the role of microorganisms in human health and disease, with evidence showing that new types of biotherapy using engineered bacterial therapeutics, including bacterial derivatives, can address specific mechanisms of disease. The complex interactions between microorganisms and metabolic/immunologic pathways underlie many diseases with unmet medical needs, suggesting that targeting these interactions may improve patient treatment. Using tools from synthetic biology and chemical engineering, non-pathogenic bacteria or bacterial products can be programmed and designed to sense and respond to environmental signals to deliver therapeutic effectors. This review describes current progress in biotherapy using live bacteria and their derivatives to achieve therapeutic benefits against various diseases.

Pathogenesis of Microscopic Colitis: A Systematic Review

BACKGROUND

Whereas the exact aetiology of microscopic colitis [MC] remains unknown, a dysregulated immune response to luminal factors or medications is the most accepted pathogenesis hypothesis.

METHODS

We conducted a systematic review of the pathogenesis of MC. We applied the Joanna Briggs Institute methodologies and the PRISMA statement for the reporting of systematic reviews [PROSPERO Trial Identifier: CRD42020145008]. Populations, Exposure of interest, and Outcome [PEO] questions were used to explore the following topics in MC: 1] intestinal luminal factors; 2] autoimmunity; 3] innate immunity; 4] adaptive immunity; 5] extracellular matrix; 6] genetic risk factors; and 7] mechanism of diarrhoea. A search was done in PubMed, Embase, and Web of Science up to February 2020. A narrative description was performed explaining the findings for each aspect of MC aetiopathogenesis.

RESULTS

Thirty-eight documents provided evidence for PEO1, 100 for PEO2, 72 for PEO3 and 4, 38 for PEO5, 20 for PEO6, and 23 for PEO7. The majority of documents were cohorts, case reports, and case series, with a few case-control and some experimental studies. Consistency among data provided by different studies was considered to support pathogenetic hypotheses. MC is a multifactorial disease believed to involve innate and adaptive immune responses to luminal factors, genetic risk, autoimmunity, and extracellular matrix alterations, all contributing by varied mechanisms to watery diarrhoea.

CONCLUSIONS

This is the first systematic review on the aetiology of MC supporting the notion that MC is a multifactorial disease. However, high-profile studies are lacking, and most evidence derives from small heterogeneous studies.

Mucosal and faecal neutrophil gelatinase-associated lipocalin as potential biomarkers for collagenous colitis

BACKGROUND

Collagenous colitis (CC) is an inflammatory bowel disease where chronic diarrhoea is the main symptom. Diagnostic markers distinguishing between CC and other causes of chronic diarrhoea remain elusive. This study explores neutrophil gelatinase-associated lipocalin (NGAL) and its mRNA lipocalin2 (LCN2) as histological and faecal disease markers in CC.

METHODS

NGAL/LCN2 were studied in colonic biopsies from CC patients before and during budesonide treatment using RNA sequencing (n = 9/group), in situ hybridization (ISH) (n = 13-22/group) and immunohistochemistry (IHC) (n = 14-25/group). Faecal samples from CC (n = 3-28/group), irritable bowel syndrome diarrhoea (IBS-D) (n = 14) and healthy controls (HC) (n = 15) were assayed for NGAL and calprotectin.

RESULTS

NGAL/LCN2 protein and mRNA expression were upregulated in active CC vs HC, and vs paired samples of treated CC in clinical remission. IHC and ISH localized increased NGAL/LCN2 mainly to epithelium of active CC, compared to almost absence in HC and treated CC. In contrast, calprotectin was solely expressed in immune cells. Despite great individual differences, faecal NGAL was significantly increased in active CC compared to HC, IBS-D and treated CC and had high test sensitivity. Faecal calprotectin levels were variably increased in active CC, but the values remained below usual clinical cut-offs.

CONCLUSION

NGAL/LCN2 is upregulated in the epithelium of active CC and reduced during budesonide-induced clinical remission to the level of HC and IBD-S. This was reflected in NGAL faecal concentrations. We propose NGAL as an IHC marker for disease activity in CC and a potential faecal biomarker discriminating CC from HC and IBS-D.

Short chain fatty acids and its producing organisms: An overlooked therapy for IBD?

The gut microbiome and the intestinal immune system are driving contributors to inflammatory bowel diseases (IBD). Both have an important signalling factor in common: short-chain fatty acids (SCFAs). SCFAs (acetate, propionate and butyrate) are produced by bacterial fermentation in the gut and exert several effects on host metabolism and immune system. This review provides an overview of the current knowledge of these effects, with specific focus on energy metabolism, intestinal barrier, immune system, and disease activity in IBD. To conclude, more research is needed on the cross-feeding mechanisms in the gut microbiome, as well as on the therapeutic potential of SCFAs on different disease models. Also randomized controlled trials and prospective cohort studies should investigate the clinical impact of SCFA administration.

Association Between Microscopic Colitis and Parkinson's Disease in a Swedish Population

BACKGROUND

Gastrointestinal inflammation has been linked with Parkinson's disease (PD). Microscopic colitis (MC) is an intestinal inflammatory disease with unknown relationship with PD.

OBJECTIVE

This study aimed to examine the association of MC with PD risk.

METHODS

In this nationwide matched cohort study in Sweden, PD incidence was compared between 12,609 patients with histologically confirmed MC and a matched population cohort of 58,879 MC-free individuals and a sibling cohort comprising all unaffected siblings of the MC patients (N_MC /N_Sibling  = 6281/12,351). Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression models.

RESULTS

During a mean follow-up of ~7 years, we identified 449 incident PD diagnoses among the MC patients and the population cohort. Overall, MC was associated with an adjusted HR of 1.76 for PD, but the association attenuated substantially during follow-up. In the time-varying effects model, PD hazard was 3.45-fold (95% CI: 2.42, 4.93) higher during the first 2 years after biopsy and 1.80-fold (95% CI: 1.23, 2.64) higher during the following 3 years among MC versus MC-free individuals but was not different beyond 5 years after biopsy (HR: 1.03; 95% CI: 0.68, 1.54). This temporal pattern of MC-PD associations persisted when comparing MC patients to their siblings. In a post hoc case-control analysis, we also detected a strong association between MC and preexisting PD (odds ratio: 3.46; 95% CI: 2.91, 4.12).

CONCLUSIONS

Our findings suggest that MC may not be a risk factor for PD; instead, it may co-occur with PD as a comorbidity or develop after a diagnosis of PD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Gut Inflammation Induced by Dextran Sulfate Sodium Exacerbates Amyloid-β Plaque Deposition in the AppNL-G-F Mouse Model of Alzheimer's Disease

BACKGROUND

Although it is known that the brain communicates with the gastrointestinal (GI) tract via the well-established gut-brain axis, the influence exerted by chronic intestinal inflammation on brain changes in Alzheimer's disease (AD) is not fully understood. We hypothesized that increased gut inflammation would alter brain pathology of a mouse model of AD.

OBJECTIVE

Determine whether colitis exacerbates AD-related brain changes.

METHODS

To test this idea, 2% dextran sulfate sodium (DSS) was dissolved in the drinking water and fed ad libitum to male C57BL/6 wild type and AppNL-G-F mice at 6-10 months of age for two cycles of three days each. DSS is a negatively charged sulfated polysaccharide which results in bloody diarrhea and weight loss, changes similar to human inflammatory bowel disease (IBD).

RESULTS

Both wild type and AppNL-G-F mice developed an IBD-like condition. Brain histologic and biochemical assessments demonstrated increased insoluble Aβ1-40/42 levels along with the decreased microglial CD68 immunoreactivity in DSS treated AppNL-G-F mice compared to vehicle treated AppNL-G-F mice.

CONCLUSION

These data demonstrate that intestinal dysfunction is capable of altering plaque deposition and glial immunoreactivity in the brain. This study increases our knowledge of the impact of peripheral inflammation on Aβ deposition via an IBD-like model system.

Faecal microbiota transplantation in Clostridioides difficile infection: real-life experience from an academic Italian hospital

BACKGROUND

Faecal microbiota transplantation (FMT) is a reasonable therapeutic option for the treatment of Clostridioides difficile infection (CDI) recurrent and refractory (RCDI) to therapy, but little evidence on the long-term impact of this therapy is currently available in the literature. The aim of this study was to evaluate the efficacy and safety of FMT in recurrent and refractory CDI and the modifications of the recipient's gut microbiota in the medium-long term.

METHODS

This prospective study collects the clinical and laboratory data of RCDI patients treated with FMT by colonoscopy from February 2016 to October 2019. Stool samples for metagenomic analysis were collected pre-FMT at 1 week and at 6 and 12-24 months post-FMT.

RESULTS

In the study period, 20 FMT procedures were performed on 19 patients. Overall, FMT was effective in 85% of treated patients. No serious adverse event was recorded. In the medium- to long-term follow up, a newly diagnosed case of collagenous colitis was observed. Post-FMT, significant changes in microbiota were observed, characterised by the transition from a low- to a greater-diversity profile. Therefore, FMT restores eubiosis and maintains it over time.

CONCLUSION

FMT is a safe and effective treatment option in RCDI patients. This procedure induces profound microbiota changes that explain its high clinical efficacy.

Microscopic colitis: pathophysiology and clinical management

Microscopic colitis is a chronic inflammatory disease of the colon that frequently causes chronic watery diarrhoea that might be accompanied by abdominal pain, nocturnal diarrhoea, urgency, and faecal incontinence. These symptoms lead to poor quality of life and increased health-care costs. Diagnosis relies on histological examination of multiple biopsy samples from the colonic mucosa, which often show no or only few abnormalities on endoscopy. Two major histological subtypes can be distinguished-collagenous colitis and lymphocytic colitis-but incomplete and variant forms with fewer characteristic features have been reported. Here we summarise the latest evidence on epidemiology, pathogenesis, and risk factors, and discuss established and novel therapeutic options for clinical remission. Finally, we propose an updated treatment algorithm. Further prospective studies are needed to clarify the natural history of microscopic colitis, supported by validated criteria for the assessment of disease activity.

Microbiota modulation-based therapy for luminal GI disorders: current applications of probiotics and fecal microbiota transplantation

Introduction: Alteration in the intestinal microbiota also termed as intestinal dysbiosis has been demonstrated in numerous gastrointestinal disorders linked to aberrant immune processes, acquisition of pathogenic organisms and often administration of antibiotics. Restoration of microbiota through probiotics and fecal microbiota transplantation (FMT) has gained tremendous popularity among researchers in the prevention and treatment of gastrointestinal diseases.Areas covered: In this review, studies testing the safety and efficacy of probiotics and FMT for the treatment of various infectious and inflammatory luminal gastrointestinal diseases are reviewed. Randomized control studies are given priority while important uncontrolled studies are also highlighted.Expert opinion: Probiotics have demonstrated efficacy in the prevention of antibiotic-associated diarrhea and in the eradication of Helicobacter pylori infection. Their utility in the primary and secondary prevention of Clostridioides difficile infection is debatable. The future of medicine should bring forth a personalized approach to probiotic use. FMT has revolutionized the treatment of recurrent CDI as well as severe and fulminant CDI. At the same time, it has galvanized gut microbiota research in the last decade. While FMT in ulcerative colitis appears promising, further studies on the durability and long-term safety are needed before it can be recommended in clinical practice.

Upper Gastrointestinal Crohn's Disease: Literature Review and Case Presentation

Upper gastrointestinal tract predominant Crohn's Disease (CD) remains an elusive clinical entity, manifesting limited or vague symptomatology, eluding clinical suspicion, and delaying subsequent diagnostic evaluation. As a result, it has not been widely described and there is a lack of clear recommendations for diagnosis or management. Standard IBD evaluation including serologic testing, imaging, and endoscopy may initially not be fruitful. Furthermore, endoscopic evaluation may be grossly normal in patients without long standing-disease. We describe an 18-year-old male who presented with only unexplained, persistent iron-deficiency anemia. Extensive outpatient testing including multiple endoscopic evaluations with standard biopsies was unfruitful. Ultimately, a positive fecal calprotectin prompted enteroscopy with endoscopic mucosal resection (EMR) in an effort to obtain a larger, deeper tissue specimen. Grossly cobblestoned mucosa along with histopathology revealing focal crypt abscesses, chronic inflammation in the lamina propria, and superficial foveolar epithelial regenerative changes were consistent with CD. This patient's case illustrates the need for a high degree of suspicion for CD in patients with unexplained or persistent iron deficiency anemias. Persistent investigation yielded an elevation in fecal calprotectin suggesting underlying gastrointestinal inflammation and prompted advanced endoscopic evaluation with EMR. Waxing and waning tissue findings are characteristic of CD and pose a unique challenge in patients with upper gastrointestinal predominant pathology. As such, diligent workup including laboratory evaluation, imaging, and serial endoscopy is critical to establish pathology and dictate subsequent management in IBD, especially upper gastrointestinal tract predominant CD.

Smoking and Risk of Microscopic Colitis: A Systematic Review and Meta-analysis

BACKGROUND

The association between smoking and inflammatory bowel disease has long been recognized, but its role in the development of microscopic colitis is less well defined. This systematic review and meta-analysis was conducted with the aims to identify all available studies on the association between smoking and risk of microscopic colitis and to synthesize their results.

METHODS

The MEDLINE and EMBASE databases were searched from inception to May 2018 for cohort studies and case-control studies that compared the risk of microscopic colitis among current/former smokers vs individuals who have never smoked. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were extracted from the included studies and pooled together using a random-effects model, generic inverse variance method of DerSimonian and Laird. Between-study heterogeneity was quantified using the Q statistic and I2. Publication bias was assessed using funnel plots.

RESULTS

Seven studies (2 cohort studies and 5 case-control studies) with 262,312 participants met the eligibility criteria and were included in the meta-analysis. Relative to never-smokers, current smokers had significantly increased odds of microscopic colitis, with a pooled OR of 2.99 (95% CI, 2.15-4.15; I2, 64%). Former smokers also had significantly higher odds of microscopic colitis compared with never-smokers, with a pooled OR of 1.63 (95% CI, 1.37-1.94; I2, 0%). Funnel plots were symmetric and did not provide suggestive evidence of publication bias for both analyses.

CONCLUSIONS

The current systematic review and meta-analysis found a significantly higher risk of microscopic colitis among current smokers compared with never-smokers. The risk attenuated among former smokers but remained significantly higher among never-smokers.