Enhanced levels of chemokines and their receptors in the colon of microscopic colitis patients indicate mixed immune cell recruitment

Lymphocytic colitis can be transcriptionally divided into channelopathic and inflammatory lymphocytic colitis

BACKGROUND

The pathobiology of the non-destructive inflammatory bowel disease (IBD) lymphocytic colitis (LC) is poorly understood. We aimed to define an LC-specific mucosal transcriptome to gain insight into LC pathology, identify unique genomic signatures, and uncover potentially druggable disease pathways.

METHODS

We performed bulk RNA-sequencing of LC and collagenous colitis (CC) colonic mucosa from patients with active disease, and healthy controls (n = 4-10 per cohort). Differential gene expression was analyzed by gene-set enrichment and deconvolution analyses to identify pathologically relevant pathways and cells, respectively, altered in LC. Key findings were validated using reverse transcription quantitative PCR and/or immunohistochemistry. Finally, we compared our data with a previous cohort of ulcerative colitis and Crohn's disease patients (n = 4 per group) to distinguish non-destructive from classic IBD.

RESULTS

LC can be subdivided into channelopathic LC, which is governed by organic acid and ion transport dysregulation, and inflammatory LC, which is driven by microbial immune responses. Inflammatory LC displays an innate and adaptive immunity that is limited compared to CC and classic IBD. Conversely, we noted a distinct induction of regulatory non-coding RNA species in inflammatory LC samples. Moreover, compared with CC, water channel and cell adhesion molecule gene expression decreased in channelopathic LC, whereas it was accentuated in inflammatory LC and associated with reduced intestinal epithelial cell proliferation.

CONCLUSIONS

We conclude that LC can be subdivided into channelopathic LC and inflammatory LC that could be pathomechanistically distinct subtypes despite their shared clinical presentation. Inflammatory LC exhibits a dampened immune response compared to CC and classic IBDs. Our results point to regulatory micro-RNAs as a potential disease-specific feature that may be amenable to therapeutic intervention.

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.

Colon cancer transcriptome

Over the last four decades, methodological innovations have continuously changed transcriptome profiling. It is now feasible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples using RNA sequencing (RNA-seq). These transcriptomes serve as a connection between cellular behaviors and their underlying molecular mechanisms, such as mutations. This relationship, in the context of cancer, provides a chance to unravel tumor complexity and heterogeneity and uncover novel biomarkers or treatment options. Since colon cancer is one of the most frequent malignancies, its prognosis and diagnosis seem to be critical. The transcriptome technology is developing for an earlier and more accurate diagnosis of cancer which can provide better protectivity and prognostic utility to medical teams and patients. A transcriptome is a whole set of expressed coding and non-coding RNAs in an individual or cell population. The cancer transcriptome includes RNA-based changes. The combined genome and transcriptome of a patient may provide a comprehensive picture of their cancer, and this information is beginning to affect treatment decision-making in real-time. A full assessment of the transcriptome of colon (colorectal) cancer has been assessed in this review paper based on risk factors such as age, obesity, gender, alcohol use, race, and also different stages of cancer, as well as non-coding RNAs like circRNAs, miRNAs, lncRNAs, and siRNAs. Similarly, they have been examined independently in the transcriptome study of colon cancer.

Campylobacter concisus from chronic inflammatory bowel diseases stimulates IL-8 production in HT-29 cells

The emerging pathogen Campylobacter concisus has been isolated from patients with gastrointestinal diseases; however, it is also present in the gut of healthy individuals. The aim of this study was to compare IL-8 production in HT-29 cells after infection with C. concisus from different gastrointestinal disease phenotypes. Additionally, to investigate whether differentiation of isolates in genomospecies (GS1 and GS2) or presence of the zot gene, encoding the Zot toxin, affects IL-8 production. A total of 37 C. concisus isolates from patients with microscopic colitis (n = 20), ulcerative colitis (n = 5), Crohn's disease (n = 5), diarrhoea (n = 2) and from healthy controls (n = 5) were used. Intestinal HT-29 cells were infected and incubated for 24 h. Supernatants were subsequently removed and analysed for IL-8 by MILLIPLEX. All isolates were able to stimulate IL-8 production and IL-8 levels were higher than in non-infected HT-29 cells. No difference was observed between disease phenotypes or GS1 and GS2, whereas presence of the zot gene showed a tendency towards higher IL-8 production. Further investigations in other inflammatory and physiological models are needed to conclude whether C. concisus strains from different gastrointestinal disease phenotypes differ in pathogenic potential and play a part in gastrointestinal disease.

Potent CCR3 Receptor Antagonist, SB328437, Suppresses Colonic Eosinophil Chemotaxis and Inflammation in the Winnie Murine Model of Spontaneous Chronic Colitis

Eosinophils and their regulatory molecules have been associated with chronic intestinal inflammation and gastrointestinal dysfunctions; eosinophil accumulation in the gut is prominent in inflammatory bowel disease (IBD). The chemokine receptor CCR3 plays a pivotal role in local and systemic recruitment and activation of eosinophils. In this study, we targeted CCR3-ligand interactions with a potent CCR3 receptor antagonist, SB328437, to alleviate eosinophil-associated immunological responses in the Winnie model of spontaneous chronic colitis. Winnie and C57BL/6 mice were treated with SB328437 or vehicle. Clinical and histopathological parameters of chronic colitis were assessed. Flow cytometry was performed to discern changes in colonic, splenic, circulatory, and bone marrow-derived leukocytes. Changes to the serum levels of eosinophil-associated chemokines and cytokines were measured using BioPlex. Inhibition of CCR3 receptors with SB328437 attenuated disease activity and gross morphological damage to the inflamed intestines and reduced eosinophils and their regulatory molecules in the inflamed colon and circulation. SB328437 had no effect on eosinophils and their progenitor cells in the spleen and bone marrow. This study demonstrates that targeting eosinophils via the CCR3 axis has anti-inflammatory effects in the inflamed intestine, and also contributes to understanding the role of eosinophils as potential end-point targets for IBD treatment.

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.

NF-kB pathway is involved in microscopic colitis pathogenesis

OBJECTIVE

To investigate the potential inflammatory pathways involved in the development of microscopic colitis (MC).

METHODS

This prospective study analysed human intestinal tissue that was collected and classified as healthy controls (HC), microscopic colitis (MC) and ulcerative colitis (UC). An RT² Profiler PCR Array for human inflammatory response and autoimmunity was used to evaluate the expression of 84 specific genes related to the inflammatory and autoimmunity pathways. Data were validated by means of real-time polymerase chain reaction on an independent group of MC intestinal tissue samples.

RESULTS

This study measured the expression of inflammatory genes in HC (n = 10), in patients with MC (n = 8) and in patients with active UC (n = 10). Of the 84 genes included in the array, the expression of the C-C motif chemokine ligand 19, C-C motif chemokine ligand 21, lymphotoxin beta and complement C3 genes that are involved in the non-canonical nuclear transcription factor kappa B (NF-kB) pathway was increased by 2.96, 6.05, 5.96 and 5.93 times in MC compared with HC, respectively. These results were confirmed by real-time polymerase chain reaction.

CONCLUSIONS

The findings suggest that an impairment of the non-canonical NF-kB pathway is involved in the development of MC.

Disruption of monocyte-macrophage differentiation and trafficking by a heme analog during active inflammation

Heme metabolism is a key regulator of inflammatory responses. Cobalt protoporphyrin IX (CoPP) is a heme analog and mimic that potently activates the NRF2/heme oxygenase-1 (HO-1) pathway, especially in monocytes and macrophages. We investigated the influence of CoPP on inflammatory responses using a murine model of colitis. Surprisingly, conditional deletion of myeloid HO-1 did not impact the colonic inflammatory response or the protective influence of CoPP in the setting of dextran sodium sulfate-induced colitis. Rather, we reveal that CoPP elicits a contradictory shift in blood myeloid populations relative to the colon during active intestinal inflammation. Major population changes include markedly diminished trafficking of CCR2⁺Ly6C^hi monocytes to the inflamed colon, despite significant mobilization of this population into circulation. This resulted in significantly diminished colonic expansion of monocyte-derived macrophages and inflammatory cytokine expression. These findings were linked with significant induction of systemic CCL2 leading to a disrupted CCL2 chemoattractant gradient toward the colon and concentration-dependent suppression of circulating monocyte CCR2 expression. Administration of CoPP also induced macrophage differentiation toward a Marco^hiHmox1^hi anti-inflammatory erythrophagocytic phenotype, contributing to an overall decreased inflammatory profile. Such findings redefine protective influences of heme metabolism during inflammation, and highlight previously unreported immunosuppressive mechanisms of endogenous CCL2 induction.

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.

Colon Expression of Chemokines and Their Receptors Depending on the Stage of Colitis and Oat Beta-Glucan Dietary Intervention-Crohn's Disease Model Study

Crohn’s disease (CD), a condition characterized by chronic inflammation of the gastrointestinal tract with alternating periods of exacerbation and remission, is becoming common around the world. This study aimed to analyze the molecular mechanisms underlying the anti-inflammatory properties of oat beta-glucans of varying molar masses by modulating the expression of chemokines and their receptors as well as other proteins related to both stages of TNBS (2,4,6-trinitrobenzosulfonic acid)-induced colitis, which is an animal model of CD. The experiment involved 96 Sprague–Dawley rats, which were divided into two main groups: control and TNBS-induced colitis. Both groups of rats were further divided into three dietary subgroups, which were fed with standard feed or feed supplemented with low- or high-molar-mass oat beta-glucans for 3 (reflecting acute inflammation) or 7 days (reflecting pre-remission). The gene expression of chemokines and their receptors in the colon wall was determined by RT-PCR, and the expression of selected proteins in the mucosa was determined by immunohistochemical analysis. The results showed that acute and pre-remission stages of colitis were characterized by the increased gene expression of seven chemokines and four chemokine receptors in the colon wall as well as disrupted protein expression of CXCL1, CCL5, CXCR2, CCR5, and OPN in the mucosa. The consumption of oat beta-glucans resulted in decreased expression of most of these genes and modulated the expression of all proteins, with a stronger effect observed with the use of high-molar-mass beta-glucan. To summarize, dietary oat beta-glucans, particularly those of high molar mass, can reduce colitis by modulating the expression of chemokines and their receptors and certain proteins associated with CD.

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.

CXCL13 promotes intestinal tumorigenesis through the activation of epithelial AKT signaling

The excessive release of proinflammatory chemokines promotes cell proliferation and tumor growth in colorectal cancer. However, their regulatory functions and molecular pathogenesis have not been well elucidated. Here, we observed the upregulation of chemokine (C-X-C motif) ligand 13 (CXCL13) in human colorectal cancers and mouse intestinal tumors. Both CXCL13 deficiency and blockade of CXCL13 signaling ameliorated disease progression. CXCL13 promoted intestinal tumorigenesis through the activation of the AKT signaling pathway in a C-X-C chemokine receptor type 5 (CXCR5)-dependent manner. Intestinal microbiota translocation drove CXCL13 production in dendritic cells through the activation of NF-κB signaling. Inhibition of microbiota translocation decreased CXCL13 production and ameliorated intestinal tumorigenesis. Together, the results of this study identify a role for the CXCL13-CXCR5 axis is involved in the crosstalk between chemokines and cell growth during the development of intestinal tumorigenesis, which also provides a therapeutic strategy for targeting CXCL13/CXCR5 in the future clinical treatment of intestinal tumors.

Dynamic role of macrophage CX3CR1 expression in inflammatory bowel disease

Inflammatory bowel disease (IBD), consisting of ulcerative colitis (UC) and Crohn's disease (CD), is featured by overactive immune response and enduring course of unrestrained colitis. Genetic predisposition and environmental factors are fundamental in disease progression. Notably, microbiota dysregulation and its interaction with host mucosal barrier perplex disease phenotype. Under experimental setting, distinct mouse models are established to mimic human colitis process, including infection induced dysbiosis, dextran sulfate sodium (DSS) etc. induced barrier destruction, anti-CD40 L induced innate immunity dominant colitis and T cell transfer colitis model. Thus, from a more detailed aspect, IBD is heterogeneous and can be further classified into different subtypes based on the specific etiological pathways. As a typical inflammatory disorder, various immune cell types are involved in IBD pathogenesis. Among them, macrophages are believed to play a pivotal role. CX3CR1⁺ macrophages, deriving from peripheral patrolling CD14⁺ Ly6C^hi monocytes, are specified cell population dwelling in the gut. Accumulating evidence suggests that CX3CR1⁺ macrophages are critical for mucosal homeostasis and IBD pathogenesis, while some conflicts exist in current studies with both protective and harmful effects being revealed. Herein, we reviewed published literatures and found that the observed discrepancies stem from many aspects: the expression level of CX3CR1, the confounding dendritic cell subsets and most importantly, the different colitis stages and subtypes. Overall, CX3CR1 targeting strategy could be powerful weapon in fighting against colitis, but at the same time, the precise etiological and pathological mechanisms should be cautiously examined concerning the appropriate usage of CX3CR1 targeted therapy.

Mast cells crosstalk with B cells in the gut and sustain IgA response in the inflamed intestine

B lymphocytes are among the cell types whose effector functions are modulated by mast cells (MCs). The B/MC crosstalk emerged in several pathological settings, notably the colon of inflammatory bowel disease (IBD) patients is a privileged site in which MCs and IgA⁺ cells physically interact. Herein, by inducing conditional depletion of MCs in red MC and basophil (RMB) mice, we show that MCs control B cell distribution in the gut and IgA serum levels. Moreover, in dextran sulfate sodium (DSS)-treated RMB mice, the presence of MCs is fundamental for the enlargement of the IgA⁺ population in the bowel and the increase of systemic IgA production. Since both conventional B-2 and peritoneal-derived B cells populate the intestine and communicate with MCs in physiological conditions and during inflammation, we further explored this interplay through the use of co-cultures. We show that MCs finely regulate different aspects of splenic B cell biology while peritoneal B cells are unresponsive to the supporting effects provided by MCs. Interestingly, peritoneal B cells induce a pro-inflammatory skewing in MCs, characterized by increased ST2 and TNF-α expression. Altogether, this study uncovers the versatility of the B/MC liaison and highlights key aspects for the resolution of intestinal inflammation.

Immunomodulatory effects of thymol and cinnamaldehyde in chicken cell lines

Thymol and cinnamaldehyde are phytogenic feed additives that have been developed to improve gut health, immunity and growth performance in poultry and swine. This study evaluated the immune modulating effects of a thymol and cinnamaldehyde blend (TCB) in the intestinal system of poultry in vitro, using two chicken cell lines, LMH (liver cell line) which has been used to mimic epithelial cell responses, and HD-11 (monocyte/macrophage-like). Cells with high viability (>95%) from established cell lines were cultured in the presence of TCB at concentrations ranging from 1 ng/ml to 100 ng/ml. The viability, transepithelial electrical resistance (TEER) and phagocytic capacity of co-cultured LMH cells, with or without stimulation with lipopolysaccharide (LPS), was subsequently evaluated. The expression of cytokines, chemokines and pattern recognition receptors by HD-11 monocytes/macrophages was measured by RT-PCR and by proteomic analysis. TCB was well tolerated by both cell lines (cell viability >90% after co-culture with TCB at 100 ng/ml for 48 h with or without LPS). Epithelial integrity of LMH cells (as assessed by TEER) was increased by TCB (10 ng/ml) after 4 h incubation, versus untreated controls, and phagocytic capacity of HD-11 cells was increased, in a dose-dependent manner (P<0.05). In HD-11 cells, TCB (10 ng/ml) downregulated the relative expression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and the transcription factor cyclooxygenase-2 and upregulated expression of anti-inflammatory IL-10, versus untreated controls (P<0.05). In summary, under the tested conditions, TCB enhanced the epithelial barrier integrity of poultry hepatocytes, increased phagocytic activity and production of anti-inflammatory cytokines by monocytes and macrophages. These results indicated how supplementing TCB in poultry diets can increase bird performance, by increasing in vivo cell membrane integrity (especially important in the gut) and assisting in immune responses, which can liberate energy for growth.

The Water Channel Aquaporin 8 is a Critical Regulator of Intestinal Fluid Homeostasis in Collagenous Colitis

BACKGROUND AND AIMS

Diarrhoea is a common, debilitating symptom of gastrointestinal disorders. Pathomechanisms probably involve defects in trans-epithelial water transport, but the role of aquaporin [AQP] family water channels in diarrhoea-predominant diseases is unknown. We investigated the involvement of AQPs in the pathobiology of collagenous colitis [CC], which features chronic, watery diarrhoea despite overtly normal intestinal epithelial cells [IECs].

METHODS

We assessed the expression of all AQP family members in mucosal samples of CC patients before and during treatment with the corticosteroid drug budesonide, steroid-refractory CC patients and healthy controls. Samples were analysed by genome-wide mRNA sequencing [RNA-seq] and quantitative real-time PCR [qPCR]. In some patients, we performed tissue microdissection followed by RNA-seq to explore the IEC-specific CC transcriptome. We determined changes in the protein levels of the lead candidates in IEC by confocal microscopy. Finally, we investigated the regulation of AQP expression by corticosteroids in model cell lines.

RESULTS

Using qPCR and RNA-seq, we identified loss of AQP8 expression as a hallmark of active CC, which was reverted by budesonide treatment in steroid-responsive but not refractory patients. Consistently, decreased AQP8 mRNA and protein levels were observed in IECs of patients with active CC, and steroid drugs increased AQP8 expression in model IECs. Moreover, low APQ8 expression was strongly associated with higher stool frequency in CC patients.

CONCLUSION

Down-regulation of epithelial AQP8 may impair water resorption in active CC, resulting in watery diarrhoea. Our results suggest that AQP8 is a potential drug target for the treatment of diarrhoeal disorders.

Impact of smoking cigarette on the mRNA expression of cytokines in mucosa of inflammatory bowel disease

It is well known that smoking is the risk factor in the development and clinical course of Crohn s disease (CD), but on the other hand, smoking is a protective factor against ulcerative colitis (UC). The pathways that are influenced by smoking in CD and UC are poorly understood. The aim of our study was to analyse the influence of smoking on the mRNA expression of cytokines in mucosa in patients with CD and UC. We performed a cross-sectional study. The cohort consisted of 86 IBD patients (48 CD patients and 38 UC patients) and took place at the IBD Centre at the University Hospital Bratislava-Ružinov. We took the demographic and clinical data of each patient, including information about their smoking habits. We performed a colonoscopy on each patient and took biopsies from both inflamed and non-inflamed sigma (CD, UC) and terminal ileum (CD). mRNA was extracted from mucosal biopsy samples for each cytokine and was normalized to a housekeeping gene (GAPDH). Finally, we compared the mRNA expression of target cytokines in the mucosa of smokers and non-smokers in IBD patients. Smokers with Crohn s disease have a significantly higher mRNA expression of pro-inflammatory cytokine TNF ? (p=0.003) in inflamed mucosa in sigma compared with non-smokers. In smokers with ulcerative colitis, we observed significantly higher mRNA expression of anti-inflammatory cytokine IL 10 (p=0.022) in non-inflamed mucosa of sigma. Similarly, smokers with UC have a significantly decreased mRNA expression of cytokine TLR 2 (p=0.024) and CCR1 (p=0.049) in non-inflamed mucosa of sigma. Based on our results, smoking has a positive influence on cessation and the clinical course of UC due to the stimulation of anti-inflammatory cytokine IL 10 in mucosa. On the other hand, smokers with CD have a higher expression of pro-inflammatory cytokine TNF ?, which could be associated with a worsening of the disease and response to therapy.

Transcriptome analysis identifies a robust gene expression program in the mouse intestinal epithelium on aging

The intestinal epithelium undergoes constant regeneration driven by intestinal stem cells. How old age affects the transcriptome in this highly dynamic tissue is an important, but poorly explored question. Using transcriptomics on sorted intestinal stem cells and adult enterocytes, we identified candidate genes, which change expression on aging. Further validation of these on intestinal epithelium of multiple middle-aged versus old-aged mice highlighted the consistent up-regulation of the expression of the gene encoding chemokine receptor Ccr2, a mediator of inflammation and several disease processes. We observed also increased expression of Strc, coding for stereocilin, and dramatically decreased expression of Rps4l, coding for a ribosome subunit. Ccr2 and Rps4l are located close to the telomeric regions of chromosome 9 and 6, respectively. As only few genes were differentially expressed and we did not observe significant protein level changes of identified ageing markers, our analysis highlights the overall robustness of murine intestinal epithelium gene expression to old age.

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.

Differential chemokine expression patterns in tonsillar disease

Expression profiles of CXC- and CC-chemokines in various forms of tonsillar disease were studied to evaluate whether certain chemokines play a predominant role in a specific subset of tonsillar disease. Total RNA was isolated from 89 biopsies (21 hyperplastic palatine tonsils, 25 adenoids, 16 chronic inflammatory palatine tonsils and 27 chronic inflammatory palatine tonsils with histological prove of acute inflammation), reverse transcribed and subjected to PCR amplifying IL-8, Gro-alpha, eotaxin-1, eotaxin-2, MCP-3, MCP-4 and RANTES. 2% agarose gel electrophoresis revealed a predominance of IL-8 in the chronic inflammatory palatine tonsil group compared to tonsillar hyperplasia. Furthermore, eotaxin-2 was strongly overexpressed in adenoid samples compared to chronic inflammatory specimens. Our data suggest that the majority of diseases related to adenoid formation are mediated via an eotaxin-2 expression, whereas chronic inflammatory tonsillitis is associated with IL-8 upregulation. These data imply that adenoids are related to a Th-2, and chronic inflammatory tonsillitis to a Th-1 based immune response.

Temporal clinical, proteomic, histological and cellular immune responses of dextran sulfate sodium-induced acute colitis

AIM

To investigate the temporal clinical, proteomic, histological and cellular immune profiles of dextran sulfate sodium (DSS)-induced acute colitis.

METHODS

Acute colitis was induced in C57Bl/6 female mice by administration of 1%, 2% or 3% DSS in drinking water for 7 d. Animals were monitored daily for weight loss, stool consistency and blood in the stool, while spleens and colons were harvested on day 8. A time course analysis was performed in mice ingesting 3% DSS, which included colon proteomics through multiplex assay, colon histological scoring by a blinded investigator, and immune response through flow cytometry or immunohistochemistry of the spleen, mesenteric lymph node and colon.

RESULTS

Progressive worsening of clinical colitis was observed with increasing DSS from 1% to 3%. In mice ingesting 3% DSS, colon shortening and increase in pro-inflammatory factors starting at day 3 was observed, with increased spleen weights at day 6 and day 8. This coincided with cellular infiltration in the colon from day 2 to day 8, with progressive accumulation of macrophages F4/80⁺, T helper CD4⁺ (Th), T cytotoxic CD8⁺ (Tcyt) and T regulatory CD25⁺ (Treg) cells, and progressive changes in colonic pathology including destruction of crypts, loss of goblet cells and depletion of the epithelial barrier. Starting on day 4, mesenteric lymph node and/or spleen presented with lower levels of Treg, Th and Tcyt cells, suggesting an immune cell tropism to the gut.

CONCLUSION

These results demonstrate that the severity of experimental colitis is dependent on DSS concentration, correlated with clinical, proteomic, histological and cellular immune response on 3% DSS.

Herpes Simplex Virus Type 1 Infects Enteric Neurons and Triggers Gut Dysfunction via Macrophage Recruitment

Herpes Simplex Virus type 1 (HSV-1), a neurotropic pathogen widespread in human population, infects the enteric nervous system (ENS) in humans and rodents and causes intestinal neuromuscular dysfunction in rats. Although infiltration of inflammatory cells in the myenteric plexus and neurodegeneration of enteric nerves are common features of patients suffering from functional intestinal disorders, the proof of a pathogenic link with HSV-1 is still unsettled mainly because the underlying mechanisms are largely unknown. In this study we demonstrated that following intragastrical administration HSV-1 infects neurons within the myenteric plexus resulting in functional and structural alterations of the ENS. By infecting mice with HSV-1 replication-defective strain we revealed that gastrointestinal neuromuscular anomalies were however independent of viral replication. Indeed, enteric neurons exposed to UV-inactivated HSV-1 produced monocyte chemoattractant protein-1 (MCP-1/CCL2) to recruit activated macrophages in the longitudinal muscle myenteric plexus. Infiltrating macrophages produced reactive oxygen and nitrogen species and directly harmed enteric neurons resulting in gastrointestinal dysmotility. In HSV-1 infected mice intestinal neuromuscular dysfunctions were ameliorated by in vivo administration of (i) liposomes containing dichloromethylene bisphosphonic acid (clodronate) to deplete tissue macrophages, (ii) CCR2 chemokine receptor antagonist RS504393 to block the CCL2/CCR2 pathway, (iii) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) and AR-C 102222 to quench production of nitrogen reactive species produced via iNOS. Overall these data demonstrate that HSV-1 infection makes enteric neurons recruit macrophages via production of a specific chemoattractant factor. The resulting inflammatory reaction is mandatory for intestinal dysmotility. These findings provide insights into the neuro-immune communication that occurs in the ENS following HSV-1 infection and allow recognition of an original pathophysiologic mechanism underlying gastrointestinal diseases as well as identification of novel therapeutic targets.

The PSMP-CCR2 interactions trigger monocyte/macrophage-dependent colitis

Monocytes/macrophages have been found to be an important component of colitis. However, the key chemokine that initiates the CCR2⁺ monocytes migration from circulation to colitis tissue remains to be undiscovered. PC3-secreted microprotein (PSMP) is a novel chemokine whose receptor is CCR2. The physiological and pathological functions of PSMP have not yet been reported. In this study, PSMP was found to be expressed in colitis and colonic tumor tissues from patients and significantly up-regulated in mouse DSS-induced colitis tissues. PSMP overexpression in the colon aggravated the DSS-induced colitis and the anti-PSMP neutralizing antibody mollified the colitis by reducing macrophage infiltration and inhibiting the expression of IL-6, TNF-α and CCL2. Furthermore, we demonstrated that lipopolysaccharide and muramyl dipeptide induced PSMP expression in the colonic epithelial cells. PSMP was up-regulated in the initial stage prior to IL-6, TNF-α and CCL2 up-regulated expression in DSS colitis and promoted the M1 macrophages to produce CCL2. PSMP chemo-attracted Ly6C^hi monocytes in a CCR2 dependent manner via in situ chemotaxis and adoptive transfer assays. Our data identify PSMP as a key molecule in ulcerative colitis, which provides a novel mechanism of monocyte/macrophage migration that affects gut innate immunity and makes PSMP a potential target for controlling colitis.

Oligoclonal T-cell Receptor Repertoire in Colonic Biopsies of Patients with Microscopic Colitis and Ulcerative Colitis

BACKGROUND

Microscopic colitis (MC), comprising collagenous colitis (CC) and lymphocytic colitis (LC), is a type of variation of inflammatory bowel diseases. Local T-cell infiltration in the mucosa plays a major role in MC immunopathology.

METHODS

To understand diversity and clonality of infiltrating T cells, we analyzed the T-cell receptor beta (TCRβ) chains in colonic biopsies of MC, ulcerative colitis (UC), and their remission counterparts (CC/LC-HR [histological remission] or UC-R [remission]) compared with patients with noninflamed colons using next-generation sequencing.

RESULTS

Compared with controls and patients with CC, patients with LC had significantly lower diversity with significantly lower evenness and richness in TCRVβ-Jβ gene segments. Similarly, patients with LC-HR had lower diversity because of significantly lower TCRVβ-Jβ clone richness. Patients with UC and UC-R showed significantly higher diversity and richness. Univariate and multivariate analyses were performed to identify TCRVβ-Jβ gene segments differentiating disease types from controls or their remission counterparts. Patients with LC were discriminated from controls by 12 clones and from patients with CC by 8 clones. Neither univariate nor multivariate analyses showed significance for patients with CC or CC-HR compared with controls. Patients with UC and UC-R had 16 and 14 discriminating clones, respectively, compared with controls.

CONCLUSIONS

Altogether, patients with MC and UC showed an oligoclonal TCRβ distribution. TCRVβ-Jβ clone types and their diversity were distinctive between patients with CC and LC, as well as for patients with UC, suggesting different pathophysiological mechanisms according to disease type and stage. This study suggests that CC and LC are different entities because of differences in immunoregulatory responses, as mirrored by their T-cell repertoire.

Proton pump inhibitor induced collagen expression in colonocytes is associated with collagenous colitis

AIM

To elucidate the role of proton pump inhibitors (PPIs) in collagenous disease, direct effect of PPI on colonocytes was examined.

METHODS

Collagenous colitis is a common cause of non-bloody, watery diarrhea. Recently, there has been increasing focus on the use of proton PPIs as a risk factor for developing collagenous colitis. Mouse CT26 colonic cells were treated with PPI and/or PPI-induced alkaline media. Expression of fibrosis-associated genes was examined by RT-PCR. In human materials, collagen expression was examined by immunohistochemistry.

RESULTS

CT26 cells expressed a Na⁺-H⁺ exchanger gene (solute carrier family 9, member A2). Treatment with PPI and/or PPI-induced alkaline media caused growth inhibition and oxidative stress in CT26 cells. The treatment increased expression of fibrosis inducing factors, transforming growth factor β and fibroblast growth factor 2. The treatment also decreased expression of a negative regulator of collagen production, replication factor C1, resulting in increased expression of collagen types III and IV in association with lipid peroxide. In biopsy specimens from patients with collagenous colitis, type III and IV collagen were increased. Increase of type III collagen was more pronounced in PPI-associated collagenous colitis than in non-PPI-associated disease.

CONCLUSION

From these findings, the reaction of colonocytes to PPI might participate in pathogenesis of collagenous colitis.

Reduced IL-37 Production Increases Spontaneous Chemokine Expressions in Colon Epithelial Cells

BACKGROUND AND AIM

Microscopic colitis, comprising collagenous colitis and lymphocytic colitis, is a common cause of chronic diarrhea. Previously, we showed enhanced chemokine productions in microscopic colitis patients, indicating dysregulated immune cell chemotaxis in the immunopathogenesis. We also showed decreased mRNA of IL-37, mainly regarded as an anti-inflammatory cytokine, in the colonic mucosa of these patients, potentially an important factor for the chronicity of the colitis. Our aim in this study was to understand the possible role of IL-37 in chemokine production using a cell line model.

METHODS

A colon epithelial cell line, T84, was stimulated with the TLR5 ligand flagellin. IL-37 protein production was reduced 20% using the CRISPR/Cas9 system, and the changes in chemokine mRNA and protein expressions were compared to cells transfected with empty plasmid.

RESULTS

The 20% reduction in IL-37 protein levels spontaneously increased CCL5, CXCL8, CXCL10, and CXCL11 mRNA and protein expressions. CCL2 mRNA and protein levels were enhanced upon TLR5 stimulation. CCL3, CCL20, and CX₃CL1 mRNA expressions were increased either spontaneously or following TLR5 stimulation, whereas CCL4 and CCL22 mRNA expressions were significantly decreased.

CONCLUSIONS

Even a minor decrease in the ability of colon epithelial cells to produce IL-37 results in altered chemokine expression, mainly an increase in the production of several chemokines. Our results indicate that a decreased IL-37 expression by colon epithelial cells may be an important factor for increasing the recruitment of immune cells and subsequently developing microscopic colitis.

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.

The Role of T-Cell Subsets in Chronic Inflammation in Celiac Disease and Inflammatory Bowel Disease Patients: More Common Mechanisms or More Differences?

Background

Chronic intestinal inflammation due to noninfectious causes represents a growing health issue all over the world. Celiac disease as well as inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative and microscopic colitis involve uncontrolled T-cell activation and T-cell-mediated damage as common denominators. Therefore, diagnosis and treatment decisions clearly benefit from the knowledge of the intricacies of the systemic and the local T-cell activity.

Summary

Depending on the cytokine milieu, CD4⁺ T cells can differentiate into proinflammatory T helper 1 (Th1), anti-inflammatory Th2, antimicrobial Th17, pleiotropic Th9, tissue-instructing Th22 cells, and in the regulatory compartment forkhead box protein 3⁺ Treg, suppressive Tr1 or Th3 cells. Additionally, follicular Th cells provide B-cell help in antibody class switching; cytotoxic CD8⁺ T cells target virus-infected or tumor cells. This review discusses our current knowledge on the contribution of defined T-cell subpopulations to establishing and maintaining chronic intestinal inflammation in either of the above entities. It also puts emphasis on the differences in the prevalence of these diseases between Eastern and Western countries.

Key Messages

In celiac disease, the driving role of T cells in the lamina propria and in the epithelium mainly specific for two defined antigens is well established. Differences in genetics and lifestyle between Western and Eastern countries were instrumental in understanding underlying mechanisms. In IBD, the vast amount of potential antigens and the corresponding antigen-specific T cells makes it unlikely to find universal triggers. Increased mucosal CD4⁺ regulatory T cells in all four entities fail to control or abrogate local inflammatory processes. Thus, prevailing differences in the functional T-cell subtypes driving chronic intestinal inflammation in celiac disease and IBD at best allow some overlap in the treatment options for either disease.