Collagenous Colitis Is Associated With HLA Signature and Shares Genetic Risks With Other Immune-Mediated Diseases

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.

Celiac Disease-Related Conditions: Who to Test?

Celiac disease (CeD) is a chronic immune-mediated condition triggered by gluten consumption in genetically predisposed individuals. Approximately 1% of the general population is affected by the disorder. Disease presentation is heterogeneous and, despite growing awareness among physicians and the public, it continues to be underestimated. The most effective strategy for identifying undiagnosed CeD is proactive case finding through serologic testing in high-risk groups. We reviewed the most recent evidence on the association between CeD and more than 20 conditions. In light of this review, CeD screening is recommended in individuals with (1) autoimmune disease and accompanying symptoms suggestive of CeD; (2) diseases that may mimic CeD (eg, irritable bowel syndrome [IBS], inflammatory bowel disease [IBD], and microscopic colitis); and (3) among patients with conditions with a high CeD prevalence: first-degree relatives, idiopathic pancreatitis, unexplained liver enzyme abnormalities, autoimmune hepatitis, primary biliary cholangitis, hyposplenism or functional asplenia with severe bacterial infection, type 1 diabetes mellitus, Hashimoto's thyroiditis and Graves' disease, Sjögren's syndrome, dermatitis herpetiformis, recurrent aphthous syndrome and enamel defects, unexplained ataxia, peripheral neuropathy, delayed menarche or premature menopause, Down syndrome, Turner syndrome, Williams syndrome, chronic fatigue syndrome, IgA nephropathy, and IgA deficiency. CeD serology should be the initial step in the screening process. However, for patients with any of the aforementioned disorders who are undergoing upper endoscopy, biopsies should be performed to rule out CeD.

Human Leukocyte Antigen Signatures as Pathophysiological Discriminants of Microscopic Colitis Subtypes

BACKGROUND AND AIMS

Microscopic colitis [MC] is currently regarded as an inflammatory bowel disease that manifests as two subtypes: collagenous colitis [CC] and lymphocytic colitis [LC]. Whether these represent a clinical continuum or distinct entities is, however, an open question. Genetic investigations may contribute important insight into their respective pathophysiologies.

METHODS

We conducted a genome-wide association study [GWAS] meta-analysis in 1498 CC, 373 LC patients, and 13 487 controls from Europe and the USA, combined with publicly available MC GWAS data from UK Biobank and FinnGen [2599 MC cases and 552 343 controls in total]. Human leukocyte antigen [HLA] alleles and polymorphic residues were imputed and tested for association, including conditional analyses for the identification of key causative variants and residues. Genetic correlations with other traits and diagnoses were also studied.

RESULTS

We detected strong HLA association with CC, and conditional analyses highlighted the DRB1*03:01 allele and its residues Y26, N77, and R74 as key to this association (best p = 1.4 × 10-23, odds ratio [OR] = 1.96). Nominally significant genetic correlations were detected between CC and pneumonia [rg = 0.77; p = 0.048] and oesophageal diseases [rg = 0.45, p = 0.023]. An additional locus was identified in MC GWAS analyses near the CLEC16A and RMI2 genes on chromosome 16 [rs35099084, p = 2.0 × 10-8, OR = 1.31]. No significant association was detected for LC.

CONCLUSION

Our results suggest CC and LC have distinct pathophysiological underpinnings, characterised by an HLA predisposing role only in CC. This challenges existing classifications, eventually calling for a re-evaluation of the utility of MC umbrella definitions.

HLA inherence as a potential parameter in checkpoint inhibitor-associated autoimmune adverse event assessment

Background

The success of immunotherapy has made it a lifesaving treatment, but not without side effects. Currently, the risk factors for developing immune-related adverse events (irAEs) in patients who receive immunotherapy are poorly understood, and there is no risk-stratifying mechanism for potentially fatal irAEs. It is postulated that oncology patients with preexisting autoimmune diseases are likely to have flares on immunotherapy. However, some patients develop de novo autoimmune conditions on immunotherapy without a prior history. Literature reports have postulated that human leukocyte antigen (HLA) inherence may play a role in irAEs. However, this potential remains underexplored.

Methods

The oncology patients who developed autoimmune adverse events on immunotherapy for whom the continuation of treatment was prudent or lifesaving were selected. Of note, all nine patients received checkpoint inhibitors (CIs). Of the nine selected patients, only one had a prior history of an autoimmune condition. None of the nine selected patients had an active autoimmune condition at the time of CI initiation. Their HLA was typed, and the results were cross-referenced with the literature reports in PubMed and Google search with the corresponding autoimmune condition of each patient.

Results

Herein, we report nine patients with irAEs for whom retrospective HLA typing revealed the inherence of multiple related HLA alleles that may correspond to the autoimmune condition that they had developed on immunotherapy. It is to be mentioned that the inherence of enriched disease-related HLA alleles was shared among patients with the same irAEs. These patients developed a range of irAEs including bullous pemphigoid, pemphigus foliaceus/vulgaris, thyroiditis, vitiligo, and hepatitis on immunotherapy. Although some combinations of disease-related HLA were well reported in otherwise idiopathic autoimmune diseases, a frequently repeated HLA allele combination in our patient population was found to be rarely seen in the general population.

Conclusion

The authors suggest that an enriched inherence of disease-related HLA alleles may play a role in the genetic propensity for the development of irAEs in oncology patients, who receive immunotherapy, including CIs. Inherence of more than one or a cluster of particular autoimmune disease-related HLA alleles in patients who receive immunotherapy may unmask the corresponding autoimmune disease as the genotype inherence presents with the phenotype of the corresponding condition. It is suggested that enriched linked HLA genotypes, which are otherwise rare in the general population, may present as the corresponding phenotype of the autoimmune condition. Such clinical presentation, enhanced by immunotherapy, such as CIs, can play a role in risk stratifying patients for precision medicine and improve the outcome.

A Literature Review of Microscopic Colitis

Although the clinical importance of microscopic colitis (MC) is highly increasing, however, the disease is still mysterious due to several challenges. Recent MC data depend mainly on doubts and uncertainties leading to misclassification. This review discussed the current knowledge gaps about MC and various controversies regarding its subtypes, pathogenesis, and management. The diagnosis of MC is based mainly on histology and immunohistopathology which can discriminate two subtypes. However, transitional forms are often associated with misclassification. The site and number of the colon biopsies have been agreed upon as at least three from each side of the colon (right and left) with a total of six. There is no credible, clear explanation for the increased incidence. The etiopathogenesis is possibly multifactorial with a high impact on the immunological background. It is proposed that MC would be the initiative of irritable bowel disease, which needs further data clarification. Although budesonide is an effective treatment in most cases, budesonide-refractory MC represents a significant clinical challenge. Therefore, immunomodulators and biologics are now well-thought to be the second-line choice for treatment.

Efficacy and Safety of Vedolizumab and Tumor Necrosis Factor Inhibitors in the Treatment of Steroid-refractory Microscopic Colitis: A Systematic Review and Meta-analysis

BACKGROUND

Tumor necrosis factor (TNF-α) inhibitors and the α4β7 integrin antagonist, vedolizumab, have been investigated as treatment options for patients with steroid-refractory microscopic colitis.

AIMS

To evaluate the benefit of vedolizumab and TNF-α inhibitors in patients with steroid-refractory microscopic colitis.

METHODS

Retrospective studies and case series involving patients with steroid-refractory MC who either received vedolizumab, adalimumab, or infliximab were eligible for inclusion. Pooled proportional meta-analyses were used to calculate the rate of clinical remission at induction, clinical response, maintenance of remission, histologic remission, and overall medication related adverse effects. Statistical analysis was performed in R using the metafor and meta packages.

RESULTS

A total of 14 studies involving 164 patients were included. Pooled analysis showed a clinical remission rate of 63.5% [95% CI (0.483; 0.776), I2=43% P=0.08], 57.8% [95% CI (0.3895; 0.7571), I2=0%, P=0.7541], and 39.3% [95% CI (0.0814; 0.7492), I2=66%, P=0.02] for vedolizumab, infliximab, and adalimumab, respectively. The maintenance of remission rates were 65.9% [95% CI (0.389; 0.889), I2=67%, P=0.02], 45.3% [95% CI (0.1479; 0.7747), I2=0%, P=0.36] and 32.5% [95% CI (0.000; 0.8508), I2=53%, P=0.14] in patients who received vedolizumab, infliximab, and adalimumab, respectively. Rate of biological-related adverse events warranting discontinuation of therapy was 12.2%, 32.9%, and 23.0% for the vedolizumab, infliximab, and adalimumab groups, respectively.

CONCLUSION

Vedolizumab and anti-TNF-α agents demonstrated a clinical benefit in the treatment of steroid-refractory microscopic colitis and with a tolerable safety profile. Future randomized controlled trials are needed to compare vedolizumab with TNF-α inhibitors and examine treatment effect on patients' quality of life.

Microscopic Colitis: Pathogenesis and Diagnosis

Microscopic colitis is a type of inflammatory bowel disease and is classified as either collagenous colitis or lymphocytic colitis. The typical presentation is chronic watery diarrhea. The disease occurs more frequently in women aged 60-65 years and is increasing in incidence. The pathophysiology of microscopic colitis remains poorly understood and has not been well-described with possible several pathogeneses. To date, the diagnosis of microscopic colitis depends on histological tissue obtained during colonoscopy. Other non-invasive biomarkers, such as inflammatory markers and fecal biomarkers, have been studied in microscopic colitis, but the results remains inconclusive. The approach to chronic diarrhea is important and being able to differentiate chronic diarrhea in patients with microscopic colitis from other diseases, such as inflammatory bowel disease, functional diarrhea, and malignancy, by using non-invasive biomarkers would facilitate patient management. The management of microscopic colitis should be based on each individual's underlying pathogenesis and involves budesonide, bile acid sequestrants, or immunosuppressive drugs in refractory cases. Cigarette smoking and certain medications, especially proton pump inhibitors, should be eliminated, when possible, after the diagnosis is made.

Predominant Antibody Deficiency and Risk of Microscopic Colitis: a Nationwide Case-Control Study in Sweden

PURPOSE : Predominant antibody deficiency (PAD) disorders, including common variable immunodeficiency (CVID), have been linked to increased risk of gastrointestinal infections and inflammatory bowel diseases. However, there are limited data on the relationship between PAD, specifically CVID, and risk of microscopic colitis (MC).

METHODS

We performed a nationwide case-control study of Swedish adults with MC diagnosed between 1997 and 2017 (n = 13,651). Data on biopsy-verified MC were retrieved from all of Sweden's pathology departments through the Epidemiology Strengthened by histoPathology Reports in Sweden (ESPRESSO) study. We defined predominant antibody deficiency using International Union of Immunologic Societies (IUIS) phenotypic classification. Individuals with MC were matched to population controls by age, sex, calendar year, and county. We used logistic regression to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

The prevalence of PAD in MC was 0.4% as compared to 0.05% in controls. After adjustment for potential confounders, this corresponded to an aOR of 7.29 (95%CI 4.64-11.63). The magnitude of the association was higher for CVID (aOR 21.01, 95% 5.48-137.44) compared to other antibody deficiencies (aOR 6.16, 95% CI 3.79-10.14). In exploratory analyses, the association between PAD and MC was particularly strong among males (aOR 31.73, 95% CI 10.82-135.04).

CONCLUSION

In this population-based study, predominant antibody deficiency was associated with increased risk of MC, particularly among males. Clinicians who encounter these patients should consider a detailed infectious history and screening for antibody deficiency.

Type 1 diabetes and microscopic colitis: A nationwide matched case-control study in Sweden

BACKGROUND AND AIMS

Microscopic colitis (MC) is a colonic inflammatory condition associated with autoimmune dysfunction. Type 1 diabetes (T1D) is a chronic disease induced by autoimmune destruction of pancreatic β-cells. We aimed to examine the association between T1D and MC.

METHODS

A matched case-control study was conducted using the nationwide ESPRESSO cohort as study base. All biopsy-confirmed MC patients born after 1940 were identified and compared to biopsy-free individuals matched from the general population for T1D diagnosis using the Swedish National Patient Register. The T1D-MC association was estimated as odds ratios (ORs) and 95% confidence intervals (CIs) by conditional logistic models, considering differences by sex and MC subtype. Full sibling comparison and adjustment for MC-associated medications were also performed.

RESULTS

We identified 352 (3.7%) and 945 (2.0%) T1D diagnoses from 9,600 MC cases and 47,870 matched population controls, respectively, which corresponded to an overall OR of 1.79 (95% CI: 1.56-2.05). The association was stronger for collagenous colitis (OR, 2.15; 95% CI: 1.70-2.71) than lymphocytic colitis (OR, 1.62; 95% CI: 1.37-1.92) and remained statistically significant in full sibling comparison (OR, 1.46; 95%: 1.18-1.81). Medication adjustment attenuated the association to null among females (OR: 1.02; 95% CI: 0.82-1.27) but not among males (OR: 1.45; 95% CI: 1.11-1.90).

CONCLUSION

T1D diagnosis was almost 80% more prevalent in MC patients compared to general population. This positive association did not seem to be spurious due to residual confounding shared by full siblings but may relate to consumption of medications associated with MC onset.

Celiac disease and risk of microscopic colitis: A nationwide population-based matched cohort study

BACKGROUND

An association has been reported between celiac disease (CD) and microscopic colitis (MC). However, large, population-based cohort studies are rare.

OBJECTIVE

To systematically examine the association between CD and MC in a large, nationwide cohort.

METHODS

We conducted a nationwide population-based matched cohort study in Sweden of 45,138 patients with biopsy-verified CD (diagnosed in 1990-2016), 223,149 reference individuals, and 51,449 siblings of CD patients. Data on CD and MC were obtained from all (n = 28) pathology departments in Sweden. Adjusted hazard ratios (aHRs) were calculated using Cox regression.

RESULTS

During follow-up, 452 CD patients and 197 reference individuals received an MC diagnosis (86.1 vs. 7.5 per 100,000 person-years). This difference corresponded to an aHR of 11.6 (95% confidence interval [CI] = 9.8-13.8) or eight extra MC cases in 1000 CD patients followed up for 10 years. Although the risk of MC was highest during the first year of follow-up (aHR 35.2; 95% CI = 20.1-61.6), it remained elevated even after 10 years (aHR 8.1; 95% CI = 6.0-10.9). Examining MC subtypes lymphocytic colitis (LC) and collagenous colitis (CC) separately, the aHR was 12.4 (95% CI = 10.0-15.3) for LC and 10.2 (95% CI = 7.7-13.6) for CC. MC was also more common before CD (adjusted odds ratio [aOR] = 52.7; 95% CI = 31.4-88.4). Compared to siblings, risk estimates decreased but remained elevated (CD and later MC: HR = 6.2; CD and earlier MC: aOR = 7.9).

CONCLUSION

Our study demonstrated a very strong association of MC with CD with an increased risk of future and previous MC in CD patients. The magnitude of the associations underscores the need to consider the concomitance of these diagnoses in cases in which gastrointestinal symptoms persist or recur despite a gluten-free diet or conventional MC treatment. The comparatively lower risk estimates in sibling comparisons suggest that shared genetic and early environmental factors may contribute to the association between CD and MC.

Collagenous colitis associated with novel sprue-like intestinal diseases

Almost a half-century ago, an unusual and distinct form of colitis was first recognized, collagenous colitis, characterized by sub-epithelial trichrome-positive deposits having the ultrastructural features of collagen. Later, other reports documented more extensive collagenous dis-ease in these patients, sometimes in the stomach and small bowel, a close linkage with other forms of microscopic colitis and its association with celiac and other immune-mediated diseases. Moreover, emerging genetic methods permitted large studies of collagenous colitis to complement these intriguing clinical and pathological studies. Finally, recent and related studies have further demonstrated these immune-based forms of colitis, with new sprue-like intestinal diseases caused by novel medications, recently detected viral infections and vaccinations.

Mucosa associated invariant T and natural killer cells in active and budesonide treated collagenous colitis patients

Introduction

Collagenous colitis (CC) is an inflammatory bowel disease, which usually responds to budesonide treatment. Our aim was to study the immunological background of the disease.

Methods

Analyses of peripheral and mucosal MAIT (mucosa associated invariant T cells) and NK (natural killer) cells were performed with flow cytometry. Numbers of mucosal cells were calculated using immunohistochemistry. We studied the same patients with active untreated CC (au-CC) and again while in remission on budesonide treatment. Budesonide refractory patients and healthy controls were also included. The memory marker CD45R0 and activation marker CD154 and CD69 were used to further study the cells. Finally B cells, CD4⁺ and CD8⁺ T cells were also analysed.

Results

The percentages of circulating CD56^dimCD16⁺ NK cells as well as MAIT cells (CD3⁺TCRVa7.2⁺CD161⁺) were decreased in au-CC compared to healthy controls. This difference was not seen in the mucosa; where we instead found increased numbers of mucosal CD4⁺ T cells and CD8⁺ T cells in au-CC. Mucosal immune cell numbers were not affected by budesonide treatment. In refractory CC we found increased mucosal numbers of MAIT cells, CD4⁺ and CD8⁺ T cells compared to au-CC.

Discussion

Patients with active collagenous colitis have lower percentages of circulating MAIT and NK cells. However, there was no change of these cells in the colonic mucosa. Most mucosal cell populations were increased in budesonide refractory as compared to au-CC patients, particularly the number of MAIT cells. This may indicate that T cell targeting therapy could be an alternative in budesonide refractory CC.

Microscopic colitis: an update

Microscopic colitis (MC) is an inflammatory pathology of the bowel diagnosed predominantly in older patients. MC is a cause of chronic watery, non-bloody diarrhea, that affects the older patients, mostly women, and leads to impaired health-related quality of life. The diagnosis and treatment can be often difficult. There are three main histological subtypes: collagenous colitis, lymphocytic colitis and incomplete microscopic colitis. Because of the variable nature of this pathology, the therapeutic options should be individualized for every patient. MC has a variable course, varying from occasional symptoms to recurrent or progressive symptoms. A literature search was performed on the main databases. Data on microscopic colitis was collected and presented. This comprehensive review aims to raise awareness of this pathology while providing the latest data regarding current recommendations. General practitioners and gastroenterologists should always take microscopic colitis into consideration when diagnosing a patient with chronic diarrhea.

Rheumatologic Associations of Microscopic Colitis: A Narrative Review

Extra-intestinal manifestations are frequent complications of the classical inflammatory bowel diseases, Crohn's disease and ulcerative colitis. However, in addition to the classical diseases, there is a spectrum of conditions, often termed "microscopic colitis", in which extra-intestinal manifestations are less well described. Our objective was to review the literature regarding the extra-intestinal manifestations complicating microscopic colitis and describe the association with systemic autoimmune rheumatic diseases. A comprehensive search and review of peer-reviewed English-language and international journals and reports was completed based on key terms, including "microscopic colitis", "lymphocytic colitis", "collagenous colitis", "inflammatory bowel disease", "extraintestinal manifestations", and the specific disease associations utilizing the PubMed Central database and MEDLINE. A broad spectrum of rheumatologic manifestations has been reported in patients with microscopic colitis. The identification of rheumatoid arthritis and limited scleroderma as co-morbidities with microscopic colitis was noteworthy. Inflammatory arthropathy was frequently seen in microscopic colitis, usually preceding or occurring in conjunction with the onset of gastrointestinal symptoms. A variety of presentations of associated arthritis were reported: migratory, symmetric or asymmetric, peripheral or axial, oligoarticular or polyarticular, erosive or non-erosive. There was a high incidence of autoantibodies in these patients, supporting a potential autoimmune association. On the basis of these anecdotal reports, we would suggest development of a clinical registry to help define the incidence of extra-intestinal manifestations and systemic autoimmune rheumatic diseases among microscopic colitis patients to help elucidate shared predispositions, pathogenic mechanisms and therapeutic opportunities.

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.

Microscopic colitis in older adults: impact, diagnosis, and management

Microscopic colitis (comprising lymphocytic and collagenous colitis, albeit an incomplete variant is gaining recognition as well) is a chronic, immune-mediated inflammatory state of the lower gastrointestinal tract (colon). The diagnosis requires diagnostic colonoscopy with characteristic histopathological findings. They have a propensity to present in senior populations (above 60 years of age), particularly women – who are approximately 2.5–3 times more likely to develop microscopic colitis. Preexisting other immune-inflammatory diseases are also shown to predispose patients for the development of microscopic colitis. The classic presentation is profuse watery diarrhea, often during the night or early morning hours. Fecal incontinence and abdominal pain are frequent as well. Thus, the disease impacts patients’ quality of life and well-being. The first described cases date back to the seventies and eighties of the twentieth century, thereby they can be considered fairly recently discovered disease states. Our understanding of the disease and its pathophysiology is still incomplete. Although there is a lack of unified recommendation for treatment, most clinicians prefer the use of budesonide, and most published guidelines regard this locally acting glucocorticoid as the therapy of choice. In our article, we aimed for a brief, noncomprehensive overview of the clinical significance, diagnosis, and management of microscopic colitis.

Diagnosis and Management of Microscopic Colitis in Pediatric Patients

Microscopic colitis (MC) is an inflammatory disease of the colon, characterized by chronic watery diarrhea with distinguishing histologic findings despite normal endoscopic appearance of the colonic mucosa. MC is a common cause of diarrhea in older adults, though it has been infrequently reported in children and adolescents. As MC is rare in the pediatric population, and the clinical presentation is non-specific, increased awareness of this disease amongst pediatric clinicians and pathologists is essential for timely diagnosis, which requires performing colonoscopy with biopsy. The etiology of MC is incompletely understood, but current theories in pathogenesis inform management strategies. The goals of management in pediatric MC should be to achieve symptomatic improvement while minimizing adverse effects of treatment. Many patients who achieve clinical response have symptomatic recurrence after discontinuation of initial therapy, and may require maintenance medication therapy to sustain remission. This review aims to summarize the epidemiology and risk factors, clinical features, diagnosis, theories regarding pathogenesis, and suggested management approaches for MC in the pediatric population.

Endoscopic and histopathologic features of Anti‐PD‐1‐related collagenous colitis

Objectives

Cancer patients treated with immune checkpoint inhibitors occasionally show persistent diarrhea accompanied by endoscopic features of ulcerative colitis. The endoscopic mucosal inflammation may appear mild in some patients compared to the clinical severity, which can make choosing a treatment challenging. In this study, we evaluated the factors that support the continuation of chemotherapy by assessing the endoscopic and histopathological characteristics of patients who experienced diarrhea after immune checkpoint inhibitor administration.

Methods

This study included eight patients who were diagnosed with collagenous colitis based on pathological assessments. We retrospectively investigated these patients’ backgrounds, laboratory data, and computed tomography images that were extracted from their medical records. We also summarized their endoscopic and pathologic findings.

Results

All eight patients were being treated with anti‐programmed cell death‐1/programmed cell death‐ligand 1 therapeutic agents and had a recent history of oral proton pump inhibitor therapy. The anti‐programmed cell death‐1‐related collagenous colitis in these cases was characterized by endoscopically mild mucosal inflammation, high fecal calprotectin levels, and a lower frequency of intestinal wall thickening on computed tomography. Histological assessments showed CD8⁺ lymphocytes predominantly infiltrating the lamina propria and crypts of the colonic mucosa. Suspending the proton pump inhibitor therapy relieved the patients’ symptoms and allowed the continuation of the anti‐programmed cell death‐1/programmed cell death‐ligand 1 therapy.

Conclusions

Anti‐programmed cell death‐1‐related collagenous colitis is reversible; appropriate diagnosis of adverse events is crucial for the continuation of immune checkpoint inhibitor therapy.

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.

Microscopic Colitis in Denmark: Regional Variations in Risk Factors and Frequency of Endoscopic Procedures

OBJECTIVE

Microscopic colitis [MC], encompassing collagenous colitis [CC] and lymphocytic colitis [LC], is an increasingly prevalent gastrointestinal disease with an unknown aetiology. Previous research has reported significant differences in the incidence of MC within Denmark, with the lowest incidence found in the most populated region [Capital Region of Denmark]. Our aim was to elucidate the causes of these regional differences.

DESIGN

All incident MC patients [n = 14 302] with a recorded diagnosis of CC [n = 8437] or LC [n = 5865] entered in The Danish Pathology Register between 2001 and 2016 were matched to 10 reference individuals [n = 142 481]. Information regarding drug exposure, including proton pump inhibitors [PPIs], selective serotonin reuptake inhibitors [SSRIs], statins, and nonsteroidal anti-inflammatory drugs [NSAIDs], were retrieved from The Danish National Prescription Registry. Information regarding endoscopy rate, smoking-related diseases, and immune-mediated inflammatory diseases were acquired from The Danish National Patient Registry.

RESULTS

Smoking, immune-mediated inflammatory diseases, exposure to PPIs, SSRIs, statins, and NSAIDs were significantly associated with MC in all Danish regions. The association between drug exposure and MC was weakest in the Capital Region of Denmark with an odds ratio of 1.8 (95% confidence interval [CI]: 1.61-2.01). The relative risk of undergoing a colonoscopy with biopsy was significantly increased in sex- and age-matched controls in all regions compared with controls from the Capital Region of Denmark, with the greatest risk found in the Region of Southern Denmark, 1.37 [95% CI: 1.26-1.50].

CONCLUSIONS

The cause of the regional differences in MC incidence in Denmark seems to be multifactorial, including variations in disease awareness and distribution of risk factors.

OUP accepted manuscript

Microscopic colitis (MC) is a chronic inflammatory disease of the large intestine and as a relatively late recognized condition, its relationship with other disorders of the gastrointestinal tract is gradually being understood and investigated. As a multifactorial disease, MC interacts with inflammatory bowel disease, celiac disease, and irritable bowel syndrome through genetic overlap, immunological factors, and gut microflora. The risk of colorectal cancer was significantly lower in MC, gastrointestinal infections increased the risk of developing MC, and there was an inverse association between Helicobacter pylori infection and MC. A variety of associations are found between MC and other gastrointestinal disorders, where aspects such as genetic effects, resemblance of immunological profiles, and intestinal microecology are potential mechanisms behind the relationships. Clinicians should be aware of these connections to achieve a better understanding and management of MC.

Microscopic colitis: controversies in clinical symptoms and autoimmune comorbidities

BACKGROUND

Microscopic colitides are chronic immune-inflammatory bowel diseases. The typical presentation is chronic, watery diarrhoea. Inflammation mostly cannot be visualized via macroscopic inspection. The diagnosis thus requires histologic sampling. The clinical picture can vary. New investigations can prove valuable in setting up recommendations.

PATIENTS

A total of 103 patients with microscopic colitis (MC) [28 lymphocytic colitis (LC) 27.2%, 75 collagenous colitis (CC) 72.8%] in the Clinical Centre of the University of Debrecen (tertiary care centre) were included, diagnosed between 1993 and 2020. We aimed for a retrospective analysis characterizing Hungarian MC patients. We sought to compare two subgroups of patients (with either LC or CC). Our investigation focussed on dominant alteration of stool habits, autoimmune and allergic comorbidities. Autoimmune diseases were diagnosed in 39% (40) of the patients, allergic diseases in 26.2% (27) of patients and 22.2% of tested patients had alimentary hypersensitivity to certain foods (18 cases out of 81 tested).

RESULTS

Age of diagnosis was younger in LC (44.5 years, SD: 5.3 vs. 51.9 years, SD: 12.8, difference= 7.4 years p = .0151). Autoimmune diseases were equally frequent in the two groups (LC: 10 patients 36%, CC: 30 patients, 40%, difference: 4%, p = .7124). Food-linked hypersensitivities were more common in CC (LC: 1 patient, CC: 17 patients). Difference in allergic diseases (asthma, rhinitis, urticaria) did not differ between groups (LC: 6 patients, 21%; CC: 21 patients, 28%, difference: 7% p = .4739). One-third of the patients did not complain about chronic diarrhoea. These patients had chronic constipation as the main symptom (34 patients, 33%).

CONCLUSION

Pre-existing autoimmune and allergic diseases were common in patients with MC. Chronic watery diarrhoea is not experienced in many cases. The absence of certain symptoms should not be used to rule out the condition.

Autoimmune diseases in microscopic colitis: A Danish nationwide case-control study

BACKGROUND

The association between autoimmune diseases and microscopic colitis remains uncertain.

AIMS

To describe the association between autoimmune diseases and microscopic colitis by using a matched case-control design based on nationwide registry data.

METHODS

All adult Danish patients with a diagnosis of microscopic colitis from 2001 to 2018 were identified from nationwide registries. Odds of autoimmune diseases were compared between cases with microscopic colitis and sex- and age-matched controls from the background population in a 1:10 ratio and evaluated by logistic regression calculating odds ratios (OR) with 95% confidence intervals (CI) adjusted for comorbidity. Analyses were stratified according to sex, age and the subtypes of lymphocytic and collagenous colitis.

RESULTS

We identified 15 597 cases with microscopic colitis and matched to 155 910 controls. In total, 3491 (22%) of patients with microscopic colitis had concomitant autoimmune disease compared to 16 521 (11%) of controls (OR, 2.46; 95% CI, 2.36-2.56). Adjusting for comorbidities reduced the OR to 2.09 (95% CI, 2.01-2.19). Analyses showed increased ORs with 16 different autoimmune diseases, particularly of gastrointestinal and endocrine origin, and connective tissue disorders. The highest ORs were for coeliac disease (OR = 10.15; 95% CI, 8.20-12.6), Crohn's disease (OR = 2.47; 95% CI, 2.10-2.91) and ulcerative colitis (OR = 6.73; 95% CI, 6.20-7.30). In stratified analyses younger age at diagnosis and collagenous colitis were associated with higher odds.

CONCLUSION

Using nationwide registry data, microscopic colitis was associated with a wide range of autoimmune diseases, especially of gastrointestinal origin. The results suggest an autoimmune predisposition to microscopic colitis.

Celiac disease: clinical update

PURPOSE OF REVIEW

This review highlights literature from the past year and explores the impact on current understanding of celiac disease pathogenesis, diagnosis, and management.

RECENT FINDINGS

In contrast to earlier clinical trials, recent data suggests that early gluten introduction may protect against the development of celiac disease. Celiac disease is underdiagnosed, associated with high burden of disease and linked to excess mortality risk, yet, there remains considerable uncertainty regarding the utility of mass screening in asymptomatic individuals. The gut microbiome is increasingly implicated in celiac disease pathogenesis, although the exact mechanism is undefined. Probiotics have been proposed as a disease-modifying option for celiac disease but most studies assessing efficacy are of low-quality. Patients with celiac disease do not appear to be at increased risk of contracting or developing adverse outcomes from COVID-19. Little is known about the pathogenesis of nonceliac gluten sensitivity; however, recent findings suggest an autoimmune basis for the condition.

SUMMARY

Current understanding of celiac disease continues to advance, though significant knowledge gaps remain. Large, rigorous, prospectively designed studies are needed to further characterize celiac disease pathogenesis, management and therapeutic options.

Microscopic colitis

Microscopic colitis (MC) is an inflammatory disease of the large intestine associated with urgent watery diarrhoea. MC may occur in people of all ages, although the disease primarily affects older women. Once believed to be rare, MC is now known to be a common cause of chronic watery diarrhoea in high-income countries, affecting 1 in 115 women and 1 in 286 men during their lifetime in Swedish population-based estimates. An inappropriate immune response to disturbances in the gut microenvironment is implicated in the pathogenesis of MC. Evidence also supports an underlying genetic basis for disease. The diagnosis of MC relies on clinical symptoms and microscopic assessment of colonic biopsy samples. MC is categorized histologically into collagenous colitis, lymphocytic colitis and their incomplete forms. The mainstay of treatment includes the use of budesonide, with or without adjunctive therapies, and withdrawal of offending drugs. Emerging studies suggest a role for biologicals and immunosuppressive therapies for the management of budesonide-refractory or budesonide-dependent disease. MC can have a substantial negative effect on patient quality of life. The outlook for MC includes a better understanding of the immune response, genetics and the microbiome in disease pathogenesis along with progress in disease management through robust clinical trials.

Transcriptomic Profiling of Collagenous Colitis Identifies Hallmarks of Nondestructive Inflammatory Bowel Disease

BACKGROUND AND AIMS

The pathophysiology of the inflammatory bowel disease collagenous colitis (CC) is poorly described. Our aim was to use RNA sequencing of mucosal samples from patients with active CC, CC in remission, refractory CC, ulcerative colitis (UC), and control subjects to gain insight into CC pathophysiology, identify genetic signatures linked to CC, and uncover potentially druggable disease pathways.

METHODS

We performed whole transcriptome sequencing of CC samples from patients before and during treatment with the corticosteroid drug budesonide, CC steroid-refractory patients, UC patients, and healthy control subjects (n = 9-13). Bulk mucosa and laser-captured microdissected intestinal epithelial cell (IEC) gene expression were analyzed by gene set enrichment and gene set variation analyses to identify significant pathways and cells, respectively, altered in CC. Leading genes and cells were validated using reverse-transcription quantitative polymerase chain reaction or immunohistochemistry.

RESULTS

We identified an activation of the adaptive immune response to bacteria and viruses in active CC that could be mediated by dendritic cells. Moreover, IECs display hyperproliferation and increased antigen presentation in active CC. Further analysis revealed that genes related to the immune response (DUOX2, PLA2G2A, CXCL9), DNA transcription (CTR9), protein processing (JOSD1, URI1), and ion transport (SLC9A3) remained dysregulated even after budesonide-induced remission. Budesonide-refractory CC patients fail to restore normal gene expression, and displayed a transcriptomic profile close to UC.

CONCLUSIONS

Our study confirmed the implication of innate and adaptive immune responses in CC, governed by IECs and dendritic cells, respectively, and identified ongoing epithelial damage. Refractory CC could share pathomechanisms with UC.

Gastrointestinal Infection and Risk of Microscopic Colitis: A Nationwide Case-Control Study in Sweden

BACKGROUND AND AIMS

Gastrointestinal infections have been linked to changes in the composition and function of gut microbiome and development of inflammatory bowel diseases. We therefore sought to examine the relationship between gastroenteritis and risk of microscopic colitis (MC).

METHODS

We conducted a case-control study of all adult patients with MC diagnosed between 1990 and 2016 in Sweden matched to up to 5 general population controls according to age, sex, calendar year, and county. Cases of MC were identified using Systematized Nomenclature of Medicine codes from the ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) study, a cohort of gastrointestinal pathology reports from all 28 pathology centers in Sweden. We used logistic regression modeling to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

Through December of 2016, we matched 13,468 MC cases to 64,479 controls. The prevalence of previous diagnosed gastrointestinal infection was 7.5% among patients with MC, which was significantly higher than in controls (3.0%, P_comparison < .001). After adjustment, gastroenteritis was associated with an increased risk of MC (aOR 2.63; 95% CI 2.42-2.85). Among specific pathogens, Clostridioides difficile (aOR 4.39; 95% CI 3.42-5.63), Norovirus (aOR 2.87; 95% CI 1.66-4.87), and Escherichia species (aOR 3.82; 95% CI 1.22-11.58), but not Salmonella species, were associated with an increased risk of MC. The association between gastrointestinal infections and risk of MC was stronger for collagenous subtype (aOR 3.23; 95% CI 2.81-3.70) as compared with lymphocytic colitis (aOR 2.51; 95% CI 2.28-2.76; P_{heterogeneity} = .005). The associations remained significant after adjustment for immune-mediated conditions and polypharmacy and when compared with unaffected siblings.

CONCLUSION

In a nationwide study, we found that gastrointestinal infection, particularly Clostridioides difficile, is associated with an increased risk of subsequent MC. This study was approved by the Regional Ethics Committee, Stockholm, Sweden (Protocol no. 2014/1287-31/4).