Fibrogenesis and fibrolysis in collagenous colitis. Patterns of procollagen types I and IV, matrix-metalloproteinase-1 and -13, and TIMP-1 gene expression

Colonic mucosa barrier defects in collagenous and ischemic colitis

AIMS

The subepithelial myofibroblasts (SEMFs) and the subepithelial band of macrophages (SEBM) are major components of the colonic mucosa barrier. Although their role in homeostasis is widely recognized, their contribution to disease states is largely unknown. Our aim was to explore histological characteristics of SEMFs and SEBM in collagenous and ischemic colitis in order to identify specific changes in distinct mucosa backgrounds lacking significant inflammation.

METHODS

SEMFs, SEBM and lamina propria (LP) macrophages were identified immunohistochemically by alpha smooth muscle Actin and Cluster of Differentiation 68 respectively in 38 colonic biopsies [14 collagenous colitis (CC), 14 ischemic colitis (IC), 10 normal mucosa].

RESULTS

In CC, SEMFs were rarely detectable in the collagenous band while aSMA-negative pericryptal fibroblast-like cells appeared. In lower LP interconnecting SEMFs processes were formed. SEBM was preserved in areas with a collagenous layer up to 20 μm. In thicker layers, it was fragmented and gradually disappeared in parallel with engulfment of enlarged macrophages. LP macrophages were usually increased. In IC, slight SEMFs changes preceded discernible epithelial alterations. Rounding, disintegration and extinction of SEMFs constituted successive alterations coinciding with crypt shrinkage and denudation. SEBM displayed total or almost total abolishment in areas with crypt damage but also in sites with minimal changes and in adjacent normal mucosa.

CONCLUSION

Our findings provide evidence of impairment of both mucosa barrier constituents in CC and IC. In CC, histological alterations are closely related to the collagenous layer which seems to affect SEMFs differentiation and migration as well as SEBM integrity. The early extinction of SEBM in IC is indicative of its high sensitivity to hypoxia and hypoperfusion.

What do we know today about drug-induced microscopic colitis? A case of lymphocytic colitis on olmesartan

Microscopic colitis is part of the differential diagnosis of chronic watery diarrhea. Colonoscopy discloses a normal looking mucosa, therefore its diagnosis is based on histology of colonic biopsies. Two main phenotypes are distinguished: collagenous colitis and lymphocytic colitis. A third entity, incomplete microscopic colitis or unspecified microscopic colitis has been reported in the literature. It affects preferentially women over 60 years of age and its association with certain drugs is increasingly established. In case of suspected drug-induced microscopic colitis, identification of the responsible drug is a key to management. After discontinuation of the suspected drug, the gold standard of treatment is budesonide both for induction and for maintenance in case of clinical relapse, as is often the case after discontinuation. Therapy with immunomodulators, biologics, or surgery is reserved for refractory forms of microscopic colitis after multidisciplinary consultation. Through the clinical case of colitis on olmesartan, we will review the latest recommendations on drug-induced microscopic colitis.

Atypical Presentations of Collagenous Gastritis Mimicking Celiac Sprue

Collagenous gastritis has been reported as a rare cause of nausea, diarrhea, weight changes, and early satiety in female patients. Here, we describe two women aged 43 and 71 years who presented with similar symptoms. Gastric biopsies from both individuals showed thickened, irregular subepithelial collagen bands (>10 μm). The pathogenesis of collagenous gastritis is poorly understood, but it may be the presenting symptom for many underlying autoimmune conditions. In particular, there is a well-established connection between collagenous disorders of the gastrointestinal tract and celiac sprue, Sjögren syndrome, and lymphocytic colitis; however, none of these conditions had been diagnosed in our patients. The older woman had incidentally discovered hypogammaglobinemia and IgA deficiency, whereas the younger woman suffered from fibromyalgia. Although a gluten-free diet and budesonide have been effective in some cases, there is no standardized therapy for collagenous gastritis. Our patients trialed diet modification and have required no additional medical interventions.

Lack of autoantibodies against collagen and related proteins in collagenous colitis

Introduction

Collagenous colitis (CC) is a common cause of chronic diarrhea and is characterized by a subepithelial thickened collagen layer in the colonic mucosa.

It shares many of the characteristics found in autoimmune diseases, but no autoantibodies have been identified. In CC, an imbalance in collagen turnover is evident. The purpose of the present study was to investigate whether any collagen-associated autoantibodies or other antibodies such as TPO and ASCA were present, and if levels of total IgE were increased.

Methods

Sera from women with active CC were analysed with ELISA for detection of autoantibodies against collagen type III and IV (Col III and IV), matrix metalloproteinase-9 (MMP-9), tissue inhibitors of metalloproteinase-1 (TIMP-1) and tenascin-C (TNC). Sera were also analysed for TPO, ASCA and total IgE. Healthy female blood donors served as controls. The cut-off value in the control group was defined as relative units > 97.5th percentile.

Results

Sixty-six women were included (mean age 60 years; range 31–74, mean disease duration 6 years; range 1–22). No autoantibody was significantly overexpressed in the CC population compared to controls. The mean disease duration was lower (p = 0.03) in the subjects who expressed collagen-associated autoantibodies (3.7 years; range 1–14), compared to those who did not (6.4 years; range 1–22). Treatment with budesonide was not associated with any of these autoantibodies.

Conclusion

No increased presence of the investigated antibodies could be found in the present study of CC. Neither could antibodies against ASCA or TPO, or elevated levels of IgE, be found. Consequently, no association was found between CC and these proteins, even though this may not be generalizable to other compounds in the collagen layer.

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.

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

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.

Expression Profiling of Inflammatory and Immunological Genes in Collagenous Colitis

BACKGROUND

Collagenous colitis [CC] is a common idiopathic cause of chronic watery diarrhoea. We investigated its pathogenesis by means of gene expression analysis.

METHODS

We analysed the expression of genes implicated in immunological and inflammatory pathways in paired colonic biopsies of histologically involved and uninvolved mucosa from five patients with histologically patchy CC, in pooled colonic biopsies of eight other patients with diffuse CC, and in pooled biopsies of eight normal controls. Analyses were performed with the Nanostring nCounter system. Expression ratios were generated and confirmed by quantitative reverse transcription PCR.

RESULTS

CC mucosa was characterized by enhanced expression of nitric oxide synthase 2; of matrix metalloproteinases 3 and 9 and tissue inhibitor of metalloproteinase 1, but not transforming growth factor β1; of mediators of T-helper 1 immunity including interleukins 12A [IL12A], 12B, IL12 receptor B1 and interferon γ; of immune mediators of the leukocyte immunoglobulin-like receptor subfamily B; and of multiple T cell cytokines and their receptors. The mitogen-activated protein kinase signalling pathway was unchanged. There were no increases in IL22, IL22RA2 or tumour necrosis factor α, which are reportedly elevated in chronic inflammatory bowel disease. In four of five patients with patchy CC, similar gene expression profiles were observed in histologically involved and uninvolved mucosa.

CONCLUSIONS

CC is characterized by altered expression of a limited repertoire of genes involved in nitric oxide synthesis, extracellular matrix remodelling, T-helper 1 immunity and immune modulation. The abnormal gene expression in patchy CC may be expressed in mucosa with and without histological disease manifestations.

Smoking is Associated with an Increased Risk of Microscopic Colitis: Results From Two Large Prospective Cohort Studies of US Women

BACKGROUND

Long-term data on the influence of smoking on risk of microscopic colitis are limited. We therefore sought to examine and characterize the association between smoking and risk of incident microscopic colitis in two large prospective cohorts of women.

METHODS

We conducted a prospective study of 231015 women enrolled in the Nurses' Health Study [NHS] and NHSII. Information regarding smoking, other lifestyle factors and medications were collected biennially from 1976 to 2012 in NHS and from 1989 to 2013 in NHSII. Incident cases of microscopic colitis were confirmed through physician medical record review. We used Cox proportional hazards modelling to examine the association between smoking and risk of microscopic colitis.

RESULTS

We documented 166 incident cases of microscopic colitis over 6122779 person-years of follow up. Compared to non-smokers, the multivariable-adjusted hazard ratio [HR] for microscopic colitis was 2.52 (95% confidence interval [CI] 1.59-4.00) amongst current smokers and 1.54 [95% CI 1.09-2.17] amongst past smokers. The risk increased with higher pack-years of smoking [p trend = 0.001] and diminished following smoking cessation [p trend = 0.017]. Current smoking appeared to be more strongly associated with risk of collagenous colitis [HR 3.68; 95% CI 1.94-6.97] than lymphocytic colitis [HR 1.71; 95% CI 0.83-3.53].

CONCLUSION

In two large prospective cohort studies, we observed an association between current smoking and risk of microscopic colitis. Risk of microscopic colitis appeared to increase with higher pack-years and diminish following smoking cessation. Future studies focused on characterizing the biological mechanisms underlying these associations are warranted.

Microscopic Colitis: A Review of Collagenous and Lymphocytic Colitis

Microscopic colitis (MC) is a chronic inflammatory bowel disease characterized by chronic watery diarrhea and diagnosed with the histologic hallmarks of disease despite a macroscopically normal large bowel. Although 2 distinct disease phenotypes exist, their clinical presentations and epidemiologic characteristics have overlapping features. This article summarizes evidence regarding the pathogenesis of MC, mechanisms of diarrhea in this cohort, and associations with medications. In addition, currently recommended and novel therapeutic approaches to achieving remission in this patient population are reviewed.

显微镜结肠炎的诊疗进展

显微镜结肠炎(microscopic colitis, MC)是一种以反复发作的、非出血性、分泌性水样腹泻为主要临床表现, 结肠镜下结肠黏膜正常, 病理显微镜下见特异性病理、组织学改变的一组临床、病理综合征, 其主要包括淋巴细胞性结肠炎和胶原性结肠炎两种类型. 近十余年来MC的发病率有所增高, 相关研究愈来愈多, 但临床医师对其认识有限. 本文就收集到的国内、外的相关研究文献, 对该病的流行病学、病因、临床症状、结肠镜诊断、病理学诊断及治疗方面的研究进展作一概述.

Diagnosis and Management of Microscopic Colitis

Microscopic colitis (MC) is a relatively common cause of chronic watery diarrhea, especially in older persons. Associated symptoms, including abdominal pain and arthralgias, are common. The diagnosis is based upon characteristic histological findings in the presence of diarrhea. The two types of MC, collagenous and lymphocytic colitis, share similar clinical features, with the main difference being the presence or absence of a thickened subepithelial collagen band. There are several treatment options for patients with MC, although only budesonide has been well studied in multiple controlled clinical trials. This review will describe the clinical features, epidemiology, pathophysiology, diagnostic criteria, and treatment of patients with MC.

Biomarkers and Microscopic Colitis: An Unmet Need in Clinical Practice

One of the most common causes of chronic diarrhea is ascribed to microscopic colitis (MC). MC is classified in subtypes: collagenous colitis (CC) and lymphocytic colitis (LC). Patients with MC report watery, non-bloody diarrhea of chronic course, abdominal pain, weight loss, and fatigue that may impair patient's health-related quality of life. A greater awareness, and concomitantly an increasing number of diagnoses over the last years, has demonstrated that the incidence and prevalence of MC are on the rise. To date, colonoscopy with histological analysis on multiple biopsies collected along the colon represents the unique accepted procedure used to assess the diagnosis of active MC and to evaluate the response to medical therapy. Therefore, the emerging need for less-invasive procedures that are also rapid, convenient, standardized, and reproducible, has encouraged scientists to turn their attention to the identification of inflammatory markers and other molecules in blood or feces and within the colonic tissue that can confirm a MC diagnosis. This review gives an update on the biomarkers that are potentially available for the identification of inflammatory activity, related to CC and LC.

Genetic Deletion of Tissue Inhibitor of Metalloproteinase-1/TIMP-1 Alters Inflammation and Attenuates Fibrosis in Dextran Sodium Sulphate-induced Murine Models of Colitis

BACKGROUND AND AIMS

Increased levels of tissue inhibitor of metalloproteinase-1 [TIMP-1] have been detected in both inflammatory and fibrotic lesions in Crohn's disease. In a murine model of chronic inflammation, fibrosis was associated with an increase in TIMP-1 and inhibition of matrix metalloproteinase [MMP]-mediated degradation. We investigated the effect of TIMP-1 deficiency in acute and chronic murine models of colitis.

METHODS

Colitis was induced via oral administration of dextran sodium sulphate [DSS] to B6.129S4-Timp1^tm1Pds/J knock-out [KO] and C57BL/6J wild-type [WT] mice. Levels of inflammation and fibrosis were assessed and gelatin zymographies and gene expression microarrays were performed.

RESULTS

Compared with WT mice, TIMP-1 KO mice had higher inflammatory parameters after acute DSS administration and developed less fibrosis after chronic DSS administration. MMP-2 levels were increased in WT versus TIMP-1 KO mice with acute colitis, whereas a trend for higher proMMP-9 levels was observed in WT versus TIMP-1 KO mice with chronic colitis. In control conditions, several immune-related genes [e.g Ido1, Cldn8] were differentially expressed between young TIMP-1 KO and WT mice, but to a lesser extent between older TIMP-1 KO and WT mice. In response to DSS, the gene expression pattern was significantly different between young TIMP-1 KO and WT mice, whereas it was similar in older TIMP-1 KO and WT mice.

CONCLUSIONS

TIMP-1 deficiency leads to differential expression of immune-related genes and to attenuated development of fibrosis. Unravelling the role of TIMP-1 in intestinal remodelling is necessary to develop more effective and more targeted therapeutic strategies for intestinal fibrosis.

Modeling of the mechano-chemical behaviour of the nuclear pore complex: current research and perspectives

Recent evidence suggests that mechanical deformation of the cell nucleus regulates the nuclear import of the transcriptional activators of genes involved in primary physiological cell responses such as stem cell differentiation. In addition, this nuclear mechanosensing response is de-regulated in pathological states, such as cancer and neurodegeneration. One hypothesis that could greatly advance the field is that the deformation of the nuclear envelope activates nuclear pore complexes through a direct mechanical link. The understanding of this possible mechanism for nuclear pore complex stretch-activation entails studying the mechanical connection of this complex to the nuclear envelope at the nanoscale. The nanomechanics of the nuclear pore complex is thus emerging as a novel research field, bridging nanoscience with nanotechnology. This review examines the frontier of research methodologies that are potentially useful for building a computational model of this interaction. This includes, for example, electron tomography to assess the geometrical features of the nuclear pore complex and nanoindentation to estimate its mechanical properties and that of the nuclear envelope. In order to summarize the state-of-the-art and perspectives in the field of NPC nanomechanics, this review covers highly interdisciplinary experimental and theoretical research methodologies pertaining to the fields of physics, chemistry, biology, materials and mechanics.

The Role of Butylidenephthalide in Targeting the Microenvironment Which Contributes to Liver Fibrosis Amelioration

The treatment of liver fibrosis has clinical limitations because of its multiple etiologies, such as epithelial–mesenchymal transition (EMT) promotion, cell regeneration and remodeling dysfunction, inflammatory cell activation, and scar tissue deposition. These factors might be considered as a new target for the fibrotic microenvironment, leading to increased fibrogenesis and liver fibrosis. Here, we investigate a small molecule named butylidenephthalide (BP) and its multiple effects on liver fibrosis treatment. Thioacetamide was used in vivo to induce chronic liver fibrosis. BP was administered orally in rats for a period of 2 and 4 weeks, which resulted in a significantly reduced fibrosis score (p < 0.05) and (p < 0.001), respectively. The inflammatory reaction of macrophage infiltration were reduced in the administration of BP, which led to the decrease in the transaminase levels. Moreover, we also found liver functions recovering (due to the increased serum albumin and reduced prothrombin time) where liver cells regenerated, which can be seen in the increase of Ki-67 on Oval cell. In addition, the fibrotic scar was also reduced, along with the expression of matrix metalloprotease by hepatic stellate cell. Furthermore, regarding the mechanism/study of EMT reduced by BP, the knockdown of BMP-7, which could reduce α-SMA expression, was mediated by the regulation of TGF-β, which implies its major role on EMT. Finally, in the in vivo study, BP treatment of liver fibrosis was reduced by Bmp7 knockdown in zebrafish, suggesting that BP leads to the reduction of liver fibrosis, which also depends on BMP-7 induction. These results suggest that BP had multiple targets for treating liver fibrosis in the following ways: reduction of EMT, decreasing inflammatory reaction, and liver cell proliferation. This multiple targets approach provided a new mechanism to treat liver injury and fibrosis.

Histology of microscopic colitis-review with a practical approach for pathologists

Microscopic colitis has emerged as a major cause of chronic watery non-bloody diarrhoea, particularly in elderly females. The term is used as an umbrella term to categorize a subgroup of colitides with distinct clinicopathological phenotypes and no significant endoscopic abnormalities. Lymphocytic colitis is defined by an increased number of surface intraepithelial lymphocytes, and collagenous colitis by a thickened collagen band underneath the surface epithelium. There is increased inflammation in the lamina propria, but only little or no crypt architectural distortion. Incomplete and variant forms showing less characteristic features have been reported under different names. The differential diagnosis mainly includes resolving infectious colitis and changes related to the intake of drugs such as non-steroidal anti-inflammatory drugs. Substantial clinical and histological overlap between lymphocytic and collagenous colitis has been described, raising the suspicion that the conditions are two histological manifestations of the same entity, possibly representing different manifestations during the disease course or different stages of disease development. In this review, we provide a practical approach for pathologists, with a focus on diagnostic criteria and differential diagnosis, and discuss recent insights into the pathogenesis of disease and the relationship with classic chronic inflammatory bowel disease, i.e. Crohn's disease and ulcerative colitis.

Diagnosis and management of microscopic colitis: current perspectives

Collagenous colitis and lymphocytic colitis, together constituting microscopic colitis, are common causes of chronic diarrhea. They are characterized clinically by chronic nonbloody diarrhea and a macroscopically normal colonic mucosa where characteristic histopathological findings are seen. Previously considered rare, they now have emerged as common disorders that need to be considered in the investigation of the patient with chronic diarrhea. The annual incidence of each disorder is five to ten per 100,000 inhabitants, with a peak incidence in 60- to 70-year-old individuals and a predominance of female patients in collagenous colitis. The etiology and pathophysiology are not well understood, and the current view suggests an uncontrolled mucosal immune reaction to various luminal agents in predisposed individuals. Clinical symptoms comprise chronic diarrhea, abdominal pain, fatigue, weight loss, and fecal incontinence that may impair the patient's health-related quality of life. An association is reported with other autoimmune disorders, such as celiac disease, thyroid disorders, diabetes mellitus, and arthritis. The best-documented treatment, both short-term and long-term, is budesonide, which induces clinical remission in up to 80% of patients after 8 weeks' treatment. However, after successful budesonide therapy is ended, recurrence of clinical symptoms is common, and the best possible long-term management deserves further study. The long-term prognosis is good, and the risk of complications, including colonic cancer, is low. We present an update of the epidemiology, pathogenesis, diagnosis, and management of microscopic colitis.

The role of interleukin 17 in Crohn's disease-associated intestinal fibrosis

Background

Interleukin (IL)-17A and IL-17E (also known as IL-25) have been implicated in fibrosis in various tissues. However, the role of these cytokines in the development of intestinal strictures in Crohn’s disease (CD) has not been explored. We investigated the levels of IL-17A and IL-17E and their receptors in CD strictured and non-strictured gut, and the effects of IL-17A and IL-17E on CD myofibroblasts.

Results

IL-17A was significantly overexpressed in strictured compared with non-strictured CD tissues, whereas no significant difference was found in the expression of IL-17E or IL-17A and IL-17E receptors (IL-17RC and IL-17RB, respectively) in strictured and non-strictured CD areas. Strictured CD explants released significantly higher amounts of IL-17A than non-strictured explants, whereas no difference was found as for IL-17E, IL-6, or tumor necrosis factor-α production. IL-17A, but not IL-17E, significantly inhibited myofibroblast migration, and also significantly upregulated matrix metalloproteinase (MMP)-3, MMP-12, tissue inhibitor of metalloproteinase-1 and collagen production by myofibroblasts from strictured CD tissues.

Conclusions

Our results suggest that IL-17A, but not IL-17E, is pro-fibrotic in CD. Further studies are needed to clarify whether the therapeutic blockade of IL-17A through the anti-IL-17A monoclonal antibody secukinumab is able to counteract the fibrogenic process in CD.

Microscopic colitis. A review

Microscopic colitis (MC) is characterized by a triad of watery diarrhea, usually normal colonoscopic findings and typical microscopic findings. Two distinct histological forms of MC have been defined: lymphocytic colitis and collagenous colitis, but overlapping features may be present. The incidence of MC appears to be rising and in some countries it may account for as many as 10-20% of patients with non-bloody watery diarrhea. The cause of MC remains unknown and is likely to be multifactorial. The pathogenesis is poorly defined, and numerous immunological abnormalities have been reported. MC is commonly associated with autoimmune diseases including celiac disease. Use of various medications, most notably non-steroidal anti-inflammatory agents and proton pump inhibitors, have been etiologically implicated but not firmly established as causative. In imperfect trials several agents have been reported to be effective in the treatment of MC; budesonide is the best studied and evidence supporting its effectiveness is the most persuasive. In cases of otherwise unexplained watery, non-bloody diarrhea, MC should be considered and colonic biopsied specimens should be taken of normal-appearing mucosa.

Microscopic colitis

Microscopic colitis may be defined as a clinical syndrome, of unknown etiology, consisting of chronic watery diarrhea, with no alterations in the large bowel at the endoscopic and radiologic evaluation. Therefore, a definitive diagnosis is only possible by histological analysis. The epidemiological impact of this disease has become increasingly clear in the last years, with most data coming from Western countries. Microscopic colitis includes two histological subtypes [collagenous colitis (CC) and lymphocytic colitis (LC)] with no differences in clinical presentation and management. Collagenous colitis is characterized by a thickening of the subepithelial collagen layer that is absent in LC. The main feature of LC is an increase of the density of intra-epithelial lymphocytes in the surface epithelium. A number of pathogenetic theories have been proposed over the years, involving the role of luminal agents, autoimmunity, eosinophils, genetics (human leukocyte antigen), biliary acids, infections, alterations of pericryptal fibroblasts, and drug intake; drugs like ticlopidine, carbamazepine or ranitidine are especially associated with the development of LC, while CC is more frequently linked to cimetidine, non-steroidal antiinflammatory drugs and lansoprazole. Microscopic colitis typically presents as chronic or intermittent watery diarrhea, that may be accompanied by symptoms such as abdominal pain, weight loss and incontinence. Recent evidence has added new pharmacological options for the treatment of microscopic colitis: the role of steroidal therapy, especially oral budesonide, has gained relevance, as well as immunosuppressive agents such as azathioprine and 6-mercaptopurine. The use of anti-tumor necrosis factor-α agents, infliximab and adalimumab, constitutes a new, interesting tool for the treatment of microscopic colitis, but larger, adequately designed studies are needed to confirm existing data.

Colorectal normal histology and histopathologic findings in patients with chronic diarrhea

Collagenous and lymphocytic colitis are common causes of chronic watery diarrhea that are characterized by distinct histopathologic abnormalities without endoscopically visible lesions and are summarized as microscopic colitis. Several variants of microscopic colitis have been described, although their clinical significance still has to be defined. Preserved mucosal architecture is a histologic hallmark of microscopic colitis and distinguishes the disease from inflammatory bowel disease (IBD). In addition to architectural abnormalities, the diagnosis of IBD rests on characteristic inflammatory changes. Differential diagnosis of IBD mainly includes prolonged infection and diverticular disease-associated colitis, also known as segmental colitis associated with diverticulosis.

Lymphocytic and collagenous colitis: an overview of so-called microscopic colitis

The entity of 'microscopic colitis' is being diagnosed with increasing frequency and is a well-established clinicopathological diagnosis that is underpinned by a triad of watery diarrhea, normal results on endoscopy and characteristic microscopic findings. Careful histopathological evaluation and awareness of its numerous associations (especially with drugs and celiac disease) and mimics will lead to the correct diagnosis of microscopic colitis. The etiology of microscopic colitis remains enigmatic and is multifactorial with different elements being more influential in different individuals. Treatment includes antidiarrheal agents and anti-inflammatory drugs (including steroids). The purpose of this article is to provide some clarity on nomenclature, discuss the multitude of conditions that can occur synchronously or metachronously with microscopic colitis and their role in the etiopathogenesis of this condition, provide a detailed review of the pathological aspects of the disease and to briefly discuss treatment trends.

Central role of IL-6 and MMP-1 for cross talk between human intestinal mast cells and human intestinal fibroblasts

Mast cells (MC) are key effector cells in allergic reactions but also involved in host defence, tissue remodeling, angiogenesis, and fibrogenesis. Here, we show that human intestinal fibroblasts (FB) suppress apoptosis in human intestinal MC dependent on IL-6. Intestinal FB produced IL-6 upon direct stimulation by intestinal MC in co-culture or by MC mediators such as TNF-α, IL-1β, tryptase or histamine. MC incubated with IL-6 survived for up to 3 weeks similar to MC co-cultured with FB and MC survival could be blocked by neutralizing anti-IL-6 Abs. Moreover, FB stimulated by MC mediators upregulated their expression of matrix metalloproteinase-1 (MMP-1), a key fibrolytic enzyme. Noteworthy, FB co-cultured with MC or treated with MMP-1 lost confluence and showed increased numbers of apoptotic cells. Our data indicate an intimate cross talk between mucosal MC and FB resulting in MC survival and induction of a fibrolytic rather than a profibrotic state in FB.

Allelic variation of the matrix metalloproteinase-9 gene is associated with collagenous colitis

BACKGROUND

Collagenous colitis is a chronic inflammatory bowel disease of unknown origin characterized by a thickened subepithelial collagen layer. Differential expression of matrix-metalloproteinases (MMPs) have been implicated in the pathogenesis of collagenous colitis. The aim was to assess genetic polymorphisms of MMP-1, -7, and -9 in a case-control setting for susceptibility to collagenous colitis.

METHODS

Seventy-five patients with symptomatic collagenous colitis and 334 healthy blood donors were genotyped for single nucleotide polymorphisms (SNPs) in MMP-1-1607, MMP-7-153, MMP-7-181, and MMP-9 exon 6 using TaqMan technology. Susceptibility to collagenous colitis was tested by comparison of the carrier status of the rare allele.

RESULTS

The carrier frequency of the allele GG of the coding SNP MMP-9 in exon 6 was 24% in patients with collagenous colitis and 14.3% in healthy blood donors (P = 0.039). The carriage of the allele GG significantly increased the risk for collagenous colitis with an odds ratio of 1.9 (95% confidence interval: 1.0-3.5). None of the other SNPs of MMP-1, MMP-7-153, and MMP-7-181 were associated with collagenous colitis.

CONCLUSIONS

Allelic variation in the MMP-9 gene may be part of a complex genetic risk profile for collagenous colitis. Further studies are needed to confirm this observation and to explore the functional role of this gene polymorphism in collagenous colitis.

Microscopic colitis

Microscopic colitis is a common cause of chronic watery diarrhea, especially among older persons. Diagnosis requires histologic analysis of colon biopsy samples in the appropriate clinical setting. Recent studies have shown an increase in the incidence of microscopic colitis, and several have addressed potential mechanisms. We review recent findings about the clinical features, diagnosis, epidemiology, pathophysiology, and treatment of microscopic colitis.

Identification of binding partners interacting with the α1-N-propeptide of type V collagen

The predominant form of type V collagen is the [α1(V)]₂α2(V) heterotrimer. Mutations in COL5A1 or COL5A2, encoding respectively the α1(V)- and α2(V)-collagen chain, cause classic EDS (Ehlers-Danlos syndrome), a heritable connective tissue disorder, characterized by fragile hyperextensible skin and joint hypermobility. Approximately half of the classic EDS cases remain unexplained. Type V collagen controls collagen fibrillogenesis through its conserved α1(V)-N-propeptide domain. To gain an insight into the role of this domain, a yeast two-hybrid screen among proteins expressed in human dermal fibroblasts was performed utilizing the N-propeptide as a bait. We identified 12 interacting proteins, including extracellular matrix proteins and proteins involved in collagen biosynthesis. Eleven interactions were confirmed by surface plasmon resonance and/or co-immunoprecipitation: α1(I)- and α2(I)-collagen chains, α1(VI)-, α2(VI)- and α3(VI)-collagen chains, tenascin-C, fibronectin, PCPE-1 (procollagen C-proteinase enhancer-1), TIMP-1 (tissue inhibitor of metalloproteinases-1), MMP-2 (matrix metalloproteinase 2) and TGF-β1 (transforming growth factor β1). Solid-phase binding assays confirmed the involvement of the α1(V)-N-propeptide in the interaction between native type V collagen and type VI collagen, suggesting a bridging function of this protein complex in the cell-matrix environment. Enzymatic studies showed that processing of the α1(V)-N-propeptide by BMP-1 (bone morphogenetic protein 1)/procollagen C-proteinase is enhanced by PCPE-1. These interactions are likely to be involved in extracellular matrix homoeostasis and their disruption could explain the pathogenetic mechanism in unresolved classic EDS cases.

Recent advances in diagnosis and treatment of microscopic colitis

Microscopic colitis, comprising collagenous colitis and lymphocytic colitis, is a common cause of chronic diarrhea. It is characterized clinically by chronic watery diarrhea and a macroscopically normal colonic mucosa where diagnostic histopathological features are seen on microscopic examination. The annual incidence of each disorder is 4-6/100,000 inhabitants, with a peak incidence in individuals 60-70 years old and a noticeable female predominance in collagenous colitis. The etiology is unknown. Chronic diarrhea, abdominal pain, weight loss, fatigue, and fecal incontinence are common symptoms that impair the health-related quality of life of the patient. There is an association with other autoimmune disorders, such as celiac disease, thyroid disorders, diabetes mellitus, and arthritis. Budesonide is the best-documented treatment, both short-term and long-term. Recurrence of symptoms is common after withdrawal of successful budesonide therapy, and the optimal long-term treatment strategy needs further study. The long-term prognosis is good, and the risk of complications including colon cancer is low. We review the epidemiology, clinical features, diagnosis and treatment of microscopic colitis.

The collagenous gastroenteritides: similarities and differences

Collagenous gastritis, collagenous sprue, and collagenous colitis share striking histologic similarities and occur together in some patients. They also share some drug and disease associations. Pediatric cases of collagenous gastritis, however, lack most of these associations. The etiologies of the collagenous gastroenteritides are not known, so it is not clear whether they are similar because they share pathogeneses, or because they indicate a common histologic response to varying injuries. The features, disease and drug associations, and the inquiries into the pathogenesis of these disorders are reviewed.

Connective tissue growth factor expression is increased in collagenous colitis and coeliac disease

AIMS

Subepithelial collagen deposition is a classical feature of collagenous colitis (CC), but is also seen in untreated coeliac disease. The end-stage mediator of excess cellular collagen production is connective tissue growth factor (CTGF). The aim of this study was to investigate CTGF expression by in situ hybridization (ISH) and polymerase chain reaction (PCR) in CC and coeliac disease as well as lymphocytic colitis (LC), Crohn's colitis and ulcerative colitis (UC).

METHODS AND RESULTS

For coeliac disease we analysed fresh frozen material by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and archival material for ISH. PCR transcripts in coeliac disease were moderately elevated and labelled cells were significantly increased in the subepithelial zone. For CC, LC and UC we investigated archival material because of the rarity of the first two conditions. There was a marked increase in CTGF expression in the subepithelial zone in CC, localizing to cells with the morphology of smooth muscle cells, which was not seen in LC.

CONCLUSIONS

The colocalization of CTGF transcripts with areas of excessive collagen deposition in coeliac disease and CC suggest that it might be the end-stage mediator of local fibrosis in these conditions.

Matrix elasticity, cytoskeletal forces and physics of the nucleus: how deeply do cells 'feel' outside and in?

Cellular organization within a multicellular organism requires that a cell assess its relative location, taking in multiple cues from its microenvironment. Given that the extracellular matrix (ECM) consists of the most abundant proteins in animals and contributes both structure and elasticity to tissues, ECM probably provides key physical cues to cells. In vivo, in the vicinity of many tissue cell types, fibrous characteristics of the ECM are less discernible than the measurably distinct elasticity that characterizes different tissue microenvironments. As a cell engages matrix and actively probes, it senses the local elastic resistance of the ECM and nearby cells via their deformation, and--similar to the proverbial princess who feels a pea placed many mattresses below--the cell seems to possess feedback and recognition mechanisms that establish how far it can feel. Recent experimental findings and computational modeling of cell and matrix mechanics lend insight into the subcellular range of sensitivity. Continuity of deformation from the matrix into the cell and further into the cytoskeleton-caged and -linked nucleus also supports the existence of mechanisms that direct processes such as gene expression in the differentiation of stem cells. Ultimately, cells feel the difference between stiff or soft and thick or thin surroundings, regardless of whether or not they are of royal descent.

Collagenous gastritis: reports and systematic review

Collagenous gastritis is a rare disorder first described in 1989. After encountering two cases, we decided to review the literature and evaluate the collagen band. A systematic review of PubMed and EMBASE databases was performed. Twenty-eight cases have been previously described and two patterns of presentations are identifiable: children or young adults (median age 12 years, range 2-22 years) presenting with symptoms attributable to the gastritis (anaemia and pain); and older adults (median age 52 years, range 35-77 years) presenting with loose stools, often associated with collagenous colitis or coeliac disease. Our two cases (one child and one adult) matched this pattern. Immunostaining of the collagen band for collagens II, III, IV and VI, and tenascin showed that the band in our cases was predominantly tenascin. In conclusion, collagenous gastritis is a rare entity whose presentation depends on the age of the patient. An autoimmune aetiology seems possible given its associations. Treatment is empirical. The 30 cases now reported show that the disorder can relapse or persist for years.

Diagnosis and management of microscopic colitis

Microscopic colitis, comprising collagenous and lymphocytic colitis, is characterized clinically by chronic watery diarrhea, and a macroscopically normal colonic mucosa where diagnostic histopathological features are seen on microscopic examination. The annual incidence of each disorder is 4-6/100,000 inhabitants, with a peak incidence in 60-70-year-old individuals and a noticeable female predominance for collagenous colitis. The etiology is unknown. Chronic diarrhea, abdominal pain, weight loss, fatigue and fecal incontinence are common symptoms, which impair the health-related quality of life of the patient. There is an association with other autoimmune disorders such as celiac disease, diabetes mellitus, thyroid disorders and arthritis. Budesonide is the best-documented short-term treatment, but the optimal long-term strategy needs further study. The long-term prognosis is good and the risk of complications including colonic cancer is low.

Investigational treatment options in microscopic colitis

Collagenous and lymphocytic colitis are the two recognized major presentations of microscopic colitis. Both diseases present with chronic watery diarrhea and a chronic inflammatory infiltrate in the colonic mucosa without specific endoscopic abnormalities, and hence diagnosis is established by histology. Recent epidemiological studies suggest that microscopic colitis may affect as many patients as Crohn's disease or ulcerative colitis. The cause of these diseases is unknown; however, several lines of evidence support the hypothesis of mucosal injury from an unknown agent in the fecal stream. Due to the lack of disease causality, therapeutic management of microscopic colitis is now directed primarily at symptoms' resolution or improvement. Based on current evidence, oral budesonide represents an effective treatment option for patients with microscopic colitis to achieve and maintain remission. Other anti-inflammatory drugs such as mesalazine or bismuth subsalicylate are now under evaluation. The optimal long-term management strategy of microscopic colitis, however, remains an unsolved issue.

Matrix metalloproteases: underutilized targets for drug delivery

Pathophysiological molecules in the extracellular environment offer excellent targets that can be exploited for designing drug targeting systems. Matrix metalloproteases (MMPs) are a family of extracellular proteolytic enzymes that are characterized by their overexpression or overactivity in several pathologies. Over the last two decades, the MMP literature reveals heightened interest in the research involving MMP biology, pathology and targeting. This review describes various strategies that have been designed to utilize MMPs for targeting therapeutic entities. Key factors that need to be considered in the successful design of such systems have been identified based on the analyses of these strategies. Development of targeted drug delivery using MMPs has been steadily pursued; however, drug delivery efforts using these targets need to be intensified and focused to realize the clinical application of the fast developing fundamental MMP research.

NOD2/CARD15 gene polymorphisms are not associated with collagenous colitis

BACKGROUND

Collagenous colitis is a chronic inflammatory bowel disease of unknown origin. In some cases of collagenous colitis, histomorphological features are comparable to other inflammatory bowel diseases.

AIM

To assess functional NOD2/CARD15 polymorphisms for the susceptibility to collagenous colitis in a case-control study.

MATERIALS AND METHODS

Seventy-five patients with symptomatic collagenous colitis and 534 healthy blood donors were genotyped for SNP 8, 12, and 13 of the NOD2/CARD15 gene using TaqMan technology. Susceptibility to collagenous colitis was tested using Chi(2)-test comparing the carrier status of the rare allele.

RESULTS

The carrier frequency of the rare allele in SNP 8, 12, and 13 was 9.5, 1.3, and 8.1% in patients with collagenous colitis and 8.9, 1.1, and 8.4% in healthy blood donors, respectively. There were no significant differences in allele-, genotype, and carrier frequency (p>0.05).

CONCLUSION

Our data suggest that functional polymorphisms in the NOD2/CARD15 gene might not be involved in the susceptibility to collagenous colitis.

Synthesis of collagen I in collagenous sprue

BACKGROUND & AIMS

Collagenous sprue (CS) is a rare severe malabsorption syndrome of unknown etiology, characterized by villus atrophy and a broad subepithelial collagen band. We studied the expression patterns of genes involved in fibrogenesis and fibrolysis and analyzed the composition of the subepithelial collagen band in CS compared with untreated celiac diseases (CDs).

METHODS

Duodenal biopsies from 2 patients with CS were hybridized with (35)S-labeled RNA probes for procollagen alpha1(I), matrix metalloproteinases (MMPs)-1 and -3, and tissue inhibitor of MMP-1 (TIMP-1). Numbers of positive subepithelial and lamina propria cells and grain density per cell were determined microscopically. Immunohistochemistry for collagens I, III, IV, XIV, and tenascin was performed by the immunoalkaline phosphatase method. Findings were compared with earlier data from patients with untreated CD.

RESULTS

Numbers of cells expressing procollagen I, MMP-1, and MMP-3 mRNA were similar, but subepithelial procollagen I transcripts per cell were significantly increased (42 and 38 vs 18 [13-23]; P < .05) in CS compared with CD, whereas cellular transcript densities for MMP-1 and MMP-3 mRNA were similar. In addition, the number of TIMP-1 mRNA-positive cells was higher in CS compared with CD (32 and 25 vs 16.5 [4-25]; P < .05). The subepithelial collagenous bands stained for collagen I, collagen III, and tenascin.

CONCLUSIONS

The prominent subepithelial matrix deposition in CS is due to increased expression of the main fibrogenic genes (procollagen I and TIMP-1) by myofibroblastic cells, whereas expression of fibrolytic MMPs remains unaltered.

Review article: uncomplicated diverticular disease of the colon

Diverticular disease of the colon is the fifth most important gastrointestinal disease in terms of direct and indirect health care costs in western countries. Uncomplicated diverticular disease is defined as the presence of diverticula in the absence of complications such as perforation, fistula, obstruction and/or bleeding. The distribution of diverticula along the colon varies worldwide being almost always left-sided and directly related to age in western countries and right-sided where diet is rich in fibre. The pathophysiology of diverticular disease is complex and relates to abnormal colonic motility, changes in the colonic wall, chronic mucosal low-grade inflammation, imbalance in colonic microflora and visceral hypersensitivity. Moreover, there can be genetic factors involved in the development of colonic diverticula. The use of non-absorbable antibiotics is the mainstay of therapy in patients with mild to moderate symptoms, and the effect of fibre-supplementation alone does not appear to be significantly different from placebo, although no definite data are available. More recently, alternative treatments have been reported. Mesalazine acts as a local mucosal immunomodulator and has been shown to improve symptoms and prevent recurrence of diverticulitis. In addition, probiotics have also been shown to be beneficial by re-establishing a normal gut microflora. In this study, the current literature on uncomplicated diverticular disease of the colon is reviewed.

Role of matrix metalloproteinases in intestinal inflammation

Matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitors of MMPs (TIMPs), are produced in the gastrointestinal tract by several structural cells. The balance between MMPs and TIMPs is essential for many physiological processes in the gut. However, imbalance between MMPs and TIMPs plays an important role in the pathophysiology of diverse intestinal inflammatory conditions. We reviewed the role of the MMP/TIMP system in the pathogenesis of intestinal inflammatory diseases and pharmacologic perspectives for the use of compounds that restore the MMP/TIMP balance.

Overview of role of the immune system in the pathogenesis of inflammatory bowel disease

Crohn's disease (CD) and ulcerative colitis (UC) are caused by the over-activity of the immune system. Current and novel therapies are designed to dampen these over-active responses. Analysis of the types of immune responses ongoing in diseased mucosa of inflammatory bowel disease patients has revealed that CD and UC are fundamentally different diseases. The former has the molecular imprints of a Th1 dominant cell-mediated hypersensitivity response whereas the latter appears to involve antibody-mediated hypersensitivity.

Collagenous mucosal inflammatory diseases of the gastrointestinal tract

Collagenous mucosal inflammatory diseases involve the columnar-lined gastric and intestinal mucosa and have become recognized increasingly as a significant cause of symptomatic morbidity, particularly in middle-aged and elderly women, especially with watery diarrhea. Still, mechanisms involved in the pathogenesis of this diarrhea remain poorly understood and require further elucidation. The prognosis and long-term outcome of these disorders has been documented only to a limited extent. Recent clinical and pathologic studies have indicated that collagenous mucosal inflammatory disease is a more extensive pathologic process that concomitantly may involve several sites in the gastric and intestinal mucosa. The dominant pathologic lesion is a distinct subepithelial hyaline-like deposit that has histochemical and ultrastructural features of collagen overlying a microscopically defined inflammatory process. An intimate relationship with other autoimmune connective tissue disorders is evident, particularly celiac disease. This is intriguing because these collagenous disorders have not been shown to be gluten dependent. Collagenous mucosal inflammatory disorders may represent a relatively unique but generalized inflammatory response to a multitude of causes, including celiac disease, along with a diverse group of pharmacologic agents. Some recent reports have documented treatment success but histopathologic reversal has been more difficult to substantiate owing to the focal, sometimes extensive nature, of this pathologic process.

A proteomics approach to identify changes in protein profiles in pre-cancerous colon

The development of colon cancer is characterised by alterations in multiple genetic and epigenetic pathways in colon tissue leading ultimately to deregulation of colon epithelial cells. Early detection is an important factor in decreasing colon cancer deaths. Proteomic techniques were used to identify potential early markers in colon tissue exhibiting pre-cancerous activity that may characterise pathological changes in a chemically induced colon cancer rat model. Protein profiles were assessed in soluble and insoluble fractions prepared from distal colon of rats treated with the colonotropic carcinogen, dimethylhydrazine. Alterations in protein profiles were associated with the presence of aberrant crypt foci, hyperplasia and dysplasia, microanatomical changes, and metabolic changes in rat colon. These changes may have a potential role in the identification of pre-pathological features preceding colon tumorigenesis.

Increased mRNA expression of tissue inhibitors of metalloproteinase-1 and -2 in Duchenne muscular dystrophy

In dystrophinopathies, disease severity is generally related to the extent of muscle fibrosis. To determine whether a decrease in matrix degradation contributes to the severe fibrosis seen in Duchenne muscular dystrophy (DMD), we quantified RNA transcript numbers for the fibrolytic matrix metalloproteinases (MMP)-1 and -2 and their natural tissue inhibitors (TIMP)-1 and -2 in DMD muscle as well as in pathological and normal controls. In addition, we investigated gelatinase (MMP-2) enzyme activity by zymography. We found an up-regulation of TIMP-1, TIMP-2 and MMP-2 RNA in DMD muscle. Zymography revealed an increase in MMP-2 activity in DMD muscle homogenates, which was absent in pathological and normal controls. Therefore, besides enhanced fibrogenesis, a disturbance of matrix degradation may play a significant role in muscle fibrosis in DMD. TIMP-1 should be investigated further as a promising target for pharmacological intervention to prevent muscle fibrosis in DMD.