T cell receptor delta repertoire in inflamed and noninflamed colon of patients with IBD analyzed by CDR3 spectratyping

Microscopic Colitis Is Associated With a Reduced Risk of Colorectal Adenoma and Cancer: A Meta-Analysis

BACKGROUND

The study sought to conduct a systematic review and meta-analysis of the risk of colorectal adenoma or cancer in patients with microscopic colitis (MC).

METHODS

A comprehensive literature search of PubMed and EMBASE databases was performed. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated to examine the effect of MC on the risk of colorectal adenoma or cancer.

RESULTS

Twelve studies reporting the outcomes of 50 795 patients with MC were eligible for this meta-analysis. MC was negatively associated with the risk of colorectal adenoma compared with participants without MC (RR, 0.44; 95% CI, 0.33-0.58; P < .001; I2 = 87.3%). Also, the rate of colorectal cancer was lower in the patients with MC compared with the general population (RR, 0.62; 95% CI, 0.43-0.89; P = .01; I2 = 91.6%). In addition, sensitivity and subgroup analyses indicated that the results were robust.

CONCLUSIONS

The present systematic review indicated that patients with MC may be associated with a lower risk of colorectal adenoma or cancer. The clinical data support the current professional society guideline. A surveillance colonoscopy program is not recommended as standard for patients with MC.

Reduced diversity of intestinal T-cell receptor repertoire in patients with Crohn’s disease

Background

The intestinal microenvironment directly determines the human T-cell receptor (TCR) repertoire. Despite its extreme diversity, TCR repertoire analysis may provide a better understanding of the immune system in patients with inflammatory bowel disease.

Methods

To investigate TCR repertoires in the intestinal mucosa, RNA sequencing was performed for inflamed and non-inflamed intestinal mucosa samples obtained from 13 patients with Crohn’s disease (CD) and healthy mucosa from nine non-IBD controls.

Results

The gene expression frequency of the TCR repertoire showed a clear separation between inflamed mucosa of patients with CD and healthy mucosa of non-IBD controls in the hierarchical clustering heatmap. The richness of TCR repertoires measured by the Chao1 index did not show a significant difference among groups, whereas diversity measured by the D50 diversity index was decreased in the inflamed mucosa of CD patients. Rare/small TCR clonotypes occupied a large proportion of TCR repertoires in healthy mucosa of controls, whereas expanded clonotypes were common in inflamed mucosa of patients with CD. Segment usages of TRAV2, TRAV22, TRAV40, TRJ14, TRAJ51, TRBV1, TRBV21.1, and TRBJ1.5 were significantly decreased in CD patients. KEGG enrichment analysis identified the enrichment of several KEGG pathways, including inflammatory bowel disease (p = 0.0012), Th1 and Th2 cell differentiation (p = 0.0011), and intestinal immune network for IgA production (p = 0.0468).

Conclusions

The diversity of the TCR repertoire is reduced in inflamed mucosa of CD patients, which might contribute to intestinal inflammation.

T cell clonal expansions in ileal Crohn's disease are associated with smoking behaviour and postoperative recurrence

T cell clonal expansions are present in the inflamed mucosa of patients with Crohn's disease (CD) and may be implicated in postoperative recurrence after ileocolonic resection.

METHODS

T cell receptor (TCR) analysis was performed in 57 patients included in a prospective multicentre cohort. Endoscopic recurrence was defined by a Rutgeerts score >i0. DNA and mRNA were extracted from biopsies collected from the surgical specimen and endoscopy, and analysed by high throughput sequencing and microarray, respectively.

RESULTS

TCR repertoire in the mucosa of patients with CD displayed diverse clonal expansions. Active smokers at time of surgery had a significantly increased proportion of clonal expansions as compared with non-smokers (25.9%vs17.9%, p=0.02). The percentage of high frequency clones in the surgical specimen was significantly higher in patients with recurrence and correlated with postoperative endoscopic recurrence (area under the curve (AUC) 0.69, 95% CI 0.54 to 0.83). All patients with clonality above 26.8% (18/57) had an endoscopic recurrence. These patients with a high clonality were more frequently smokers than patients with a low clonality (61% vs 23%, p=0.005). The persistence of a similar TCR repertoire at postoperative endoscopy was associated with smoking and disease recurrence. Patients with high clonality showed increased expression of genes associated with CD8 T cells and reduced expression of inflammation-related genes. Expanded clones were found predominantly in the CD8 T cell compartment.

CONCLUSION

Clonal T cell expansions are implicated in postoperative endoscopic recurrence. CD patients with increased proportion of clonal T cell expansions in the ileal mucosa represent a subgroup associated with smoking and where pathogenesis appears as T cell driven.

TRIAL REGISTRATION NUMBER

NCT03458195.

Characterization of γδ T Cells in Intestinal Mucosa From Patients With Early-Onset or Long-Standing Inflammatory Bowel Disease and Their Correlation With Clinical Status

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] is a complex chronic inflammatory disease of the human gut with no clear aetiology. Traditionally, dysregulated adaptive immune responses play an important role even though accumulating evidence suggests a role also for innate immunity. Because of the well-known plasticity of γδ T cells, we investigated their percentage occurrence, phenotypic features and effector functions in the intestinal mucosa of early-onset and long-standing IBD patients, as compared to healthy subjects.

METHODS

Fresh biopsies from 30 Crohn's disease and ulcerative colitis patients were obtained and digested, and cells were analysed by flow cytometry.

RESULTS

We found a reduced frequency of Vδ1 T cells in tissue from early and late IBD patients (2.24% and 1.95%, respectively, vs 5.44% in healthy tissue) but an increased frequency of Vδ2 T cells in the gut of late IBD patients (3.19% in late patients vs 1.5% in early patients and 1.65% in healthy tissue). The infiltrating Vδ2 T cells had predominant effector memory and terminally differentiated phenotypes and produced elevated levels of tumour necrosis factor-α [TNF-α] and interleukin-17 [IL-17]. The frequency of tissue Vδ2 T cells correlated with the extent of the inflammatory response and the severity of IBD.

CONCLUSION

Our study shows that tissue Vδ1 T cells are decreased in IBD patients while Vδ2 T cells are increased in the gut of IBD patients and contribute to TNF-α production. Moreover, we identify an as yet unappreciated role of Vδ2 T cells in IL-17 production in the gut of long-standing IBD patients, suggesting that they also participate in the chronic inflammatory process.

T-cell repertoires in refractory coeliac disease

OBJECTIVE

Refractory coeliac disease (RCD) is a potentially hazardous complication of coeliac disease (CD). In contrast to RCD type I, RCD type II is a precursor entity of enteropathy-associated T-cell lymphoma (EATL), which is associated with clonally expanding T-cells that are also found in the sequentially developing EATL. Using high-throughput sequencing (HTS), we aimed to establish the small-intestinal T-cell repertoire (TCR) in CD and RCD to unravel the role of distinct T-cell clonotypes in RCD pathogenesis.

DESIGN

DNA extracted from duodenal mucosa specimens of controls (n=9), active coeliacs (n=10), coeliacs on a gluten-free diet (n=9), RCD type I (n=8), RCD type II (n=8) and unclassified Marsh I cases (n=3) collected from 2002 to 2013 was examined by TCRβ-complementarity-determining regions 3 (CDR3) multiplex PCR followed by HTS of the amplicons.

RESULTS

On average, 10⁶ sequence reads per sample were generated consisting of up to 900 individual TCRβ rearrangements. In RCD type II, the most frequent clonotypes (ie, sequence reads with identical CDR3) represent in average 42.6% of all TCRβ rearrangements, which was significantly higher than in controls (6.8%; p<0.01) or RCD type I (6.7%; p<0.01). Repeat endoscopies in individual patients revealed stability of clonotypes for up to several years without clinical symptoms of EATL. Dominant clonotypes identified in individual patients with RCD type II were unique and not related between patients. CD-associated, gliadin-dependent CDR3 motifs were only detectable at low frequencies.

CONCLUSIONS

TCRβ-HTS analysis unravels the TCR in CD and allows detailed analysis of individual TCRβ rearrangements. Dominant TCRβ sequences identified in patients with RCD type II are unique and not homologous to known gliadin-specific TCR sequences, supporting the assumption that these clonal T-cells expand independent of gluten stimulation.

Low Prevalence of Colon Polyps in Chronic Inflammatory Conditions of the Colon

OBJECTIVES

Previous studies have reported a low prevalence of colon polyps in patients with microscopic colitis. The aim of the study was to test whether such inverse associations applied to other inflammatory diseases of the colon.

METHODS

In a case-control study among 130,204 patients undergoing colonoscopy for the work-up of diarrhea, we compared the prevalence of colon polyps in a case population of patients with inflammatory bowel disease (IBD), microscopic colitis, histologic signs of active colitis, diverticulitis, or ischemic colitis, and in a control population with normal colon mucosa. Case and control subjects were compared using odds ratios and their 95% confidence intervals adjusted for age and sex.

RESULTS

In 11,176 patients with microscopic colitis, the prevalence of hyperplastic polyps, serrated adenomas, and tubular adenomas were all reduced: odds ratios=0.46 (95% confidence intervals=0.43-0.49), 0.24 (0.19-0.30), and 0.35 (0.33-0.38), respectively. In 4,435 patients with IBD, the corresponding values were: 0.18 (0.15-0.21), 0.24 (0.16-0.35), and 0.18 (0.15-0.21), respectively. In 6,501 patients with histologically active colitis, the corresponding values were: 0.58 (0.53-0.63), 0.57 (0.46-0.70), and 0.63 (0.58-0.68), respectively. No such consistent reduction in polyp prevalence was found in patients with diverticulitis or ischemic colitis.

CONCLUSIONS

Chronic inflammatory conditions of the colon are associated with a decreased prevalence of colon polyps.

Skin- and gut-homing molecules on human circulating γδ T cells and their dysregulation in inflammatory bowel disease

Changes in phenotype and function of γδ T cells have been reported in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Dysregulation of lymphocyte migration plays a key role in IBD pathogenesis; however, data on migratory properties of γδ T cells are scarce. Human circulating γδ T cells from healthy controls (n = 27), patients with active CD (n = 15), active UC (n = 14) or cutaneous manifestations of IBD (n = 2) were characterized by flow cytometry. Circulating γδ T cells in healthy controls were CD3(hi) and expressed CD45RO. They expressed gut-homing molecule β7 but not gut-homing molecule corresponding chemokine receptors (CCR)9, or skin-homing molecules cutaneous lymphocyte-associated antigen (CLA) and CCR4, despite conventional T cells containing populations expressing these molecules. CCR9 expression was increased on γδ T cells in CD and UC, while skin-homing CLA was expressed aberrantly on γδ T cells in patients with cutaneous manifestations of IBD. Lower levels of CD3 expression were found on γδ T cells in CD but not in UC, and a lower proportion of γδ T cells expressed CD45RO in CD and UC. Enhanced expression of gut-homing molecules on circulating γδ T cells in IBD and skin-homing molecules in cutaneous manifestations of IBD may be of clinical relevance.

Decreased colorectal cancer and adenoma risk in patients with microscopic colitis

INTRODUCTION

Microscopic colitis is currently considered to harbor no increased risk for colorectal cancer, based on a few small studies with limited long-term follow-up. Our aim was to identify patients with microscopic colitis, and to compare long-term rates of colorectal cancer or adenoma to a control group of patients without microscopic colitis.

METHODS

We reviewed the records of patients diagnosed with microscopic colitis, as identified by a hospital-based pathology database from January 2000 to August 2008. Clinical factors, including history of adenoma or adenocarcinoma, and all colonoscopy findings, were recorded. Age and gender-matched patients without microscopic colitis served as the control in a 1:1 fashion.

RESULTS

A total of 647 patients (153 male: 494 female) were identified with microscopic colitis (MC). Any history of colorectal cancer was detected in 1.92, 1.81, and 4.17% of patients with collagenous colitis (CC), lymphocytic colitis (LC), and controls, respectively (P = 0.095, P = 0.040, P = 0.015 for CC, LC, and all MC, respectively, comparing to controls). Overall, covariate-adjusted risk (odds ratio) of any history of colorectal cancer and colorectal adenoma in MC patients was 0.34 (95% confidence interval [CI] 0.16-0.73, P = 0.006) and 0.52 (95% CI 0.50-0.76, P < 0.0001), respectively. The mean duration of follow-up was 4.63 years, with 147/647 (22.7%) of patients with clinical follow-up >7 years.

CONCLUSIONS

In this case-control study involving a large retrospective cohort, microscopic colitis is negatively associated with the risk for colorectal cancer and adenoma. Further studies are required to determine a temporal relationship between microscopic colitis and the future development of colorectal neoplasia.

Infliximab induces clonal expansion of γδ-T cells in Crohn's disease: a predictor of lymphoma risk?

Background

Concominant with the widespread use of combined immunotherapy in the management of Crohn's disease (CD), the incidence of hepato-splenic gamma-delta (γδ)-T cell lymphoma has increased sharply in CD patients. Malignant transformation of lymphocytes is believed to be a multistep process resulting in the selection of malignant γδ-T cell clones. We hypothesised that repeated infusion of anti-TNF-α agents may induce clonal selection and that concurrent treatment with immunomodulators further predisposes patients to γδ-T cell expansion.

Methodology/Principal Findings

We investigated dynamic changes in the γδ-T cells of patient with CD following treatment with infliximab (Remicade®; n = 20) or adalimumab (Humira®; n = 26) using flow cytometry. In patients with a high γδ-T cell level, the γδ-T cells were assessed for clonality. Of these 46 CD patients, 35 had a γδ-T cells level (mean 1.6%) comparable to healthy individuals (mean 2.2%), and 11 CD patients (24%) exhibited an increased level of γδ-T cells (5–15%). In the 18 patients also receiving thiopurines or methotrexate, the average baseline γδ-T cell level was 4.4%. In three male CD patients with a high baseline value, the γδ-T cell population increased dramatically following infliximab therapy. A fourth male patient also on infliximab monotherapy presented with 20% γδ-T cells, which increased to 25% shortly after treatment and was 36% between infusions. Clonality studies revealed an oligoclonal γδ-T cell pattern with dominant γδ-T cell clones. In support of our clinical findings, in vitro experiments showed a dose-dependent proliferative effect of anti-TNF-α agents on γδ-T cells.

Conclusion/Significance

CD patients treated with immunomodulators had constitutively high levels of γδ-T cells. Infliximab exacerbated clonal γδ-T cell expansion in vivo and induced γδ-T cell proliferation in vitro. Overall, young, male CD patients with high baseline γδ-T cell levels may be at an increased risk of developing malignant γδ-T cell lymphomas following treatment with anti-TNF-α agents.

Only a subset of phosphoantigen-responsive gamma9delta2 T cells mediate protective tuberculosis immunity

Mycobacterium tuberculosis and Mycobacterium bovis bacillus Calmette-Guérin (BCG) induce potent expansions of human memory Vgamma(9)(+)Vdelta(2)(+) T cells capable of IFN-gamma production, cytolytic activity, and mycobacterial growth inhibition. Certain phosphoantigens expressed by mycobacteria can stimulate gamma(9)delta(2) T cell expansions, suggesting that purified or synthetic forms of these phosphoantigens may be useful alone or as components of new vaccines or immunotherapeutics. However, we show that while mycobacteria-activated gamma(9)delta(2) T cells potently inhibit intracellular mycobacterial growth, phosphoantigen-activated gamma(9)delta(2) T cells fail to inhibit mycobacteria, although both develop similar effector cytokine and cytolytic functional capacities. gamma(9)delta(2) T cells receiving TLR-mediated costimulation during phosphoantigen activation also failed to inhibit mycobacterial growth. We hypothesized that mycobacteria express Ags, other than the previously identified phosphoantigens, that induce protective subsets of gamma(9)delta(2) T cells. Testing this hypothesis, we compared the TCR sequence diversity of gamma(9)delta(2) T cells expanded with BCG-infected vs phosphoantigen-treated dendritic cells. BCG-stimulated gamma(9)delta(2) T cells displayed a more restricted TCR diversity than phosphoantigen-activated gamma(9)delta(2) T cells. In addition, only a subset of phosphoantigen-activated gamma(9)delta(2) T cells functionally responded to mycobacteria-infected dendritic cells. Furthermore, differential inhibitory functions of BCG- and phosphoantigen-activated gamma(9)delta(2) T cells were confirmed at the clonal level and were not due to differences in TCR avidity. Our results demonstrate that BCG infection can activate and expand protective subsets of phosphoantigen-responsive gamma(9)delta(2) T cells, and provide the first indication that gamma(9)delta(2) T cells can develop pathogen specificity similar to alphabeta T cells. Specific targeting of protective gamma(9)delta(2) T cell subsets will be important for future tuberculosis vaccines.

Antigen receptor V-segment usage in mucosal T cells

In the accepted model of lymphocyte intestinal homing, naïve T cells recirculate via organized lymphoid tissues, whilst induced effector/memory cells home to the intestinal mucosa. In order to assess the T-cell-receptor repertoire in the intestine and gut-associated lymphoid tissue (GALT), spectratyping was performed on the proximal and the distal intestine, spleen and mesenteric lymph node tissue from six PVG rats. The products were analysed with an automated sequencer and statistical analyses were performed with hierarchical cluster analysis. This demonstrated the presence of a restricted T-cell repertoire in the small intestine compared with that in the mesenteric lymph nodes and the spleen. It also demonstrated marked differences in repertoire between individual, fully inbred rats maintained under apparently identical conditions in the same cage and fed identical diets. In addition, this work demonstrated marked differences between repertoires in the proximal and the distal intestine. Such marked differences are likely to reflect the end result of increasing divergence over time produced by relatively subtle effects of environment and antigenic load. Equally, marked differences in repertoire between small intestinal segments within individual rats indicate selective recruitment or retention of specific clones, presumably antigen-driven.

gammadelta T cells: firefighters or fire boosters in the front lines of inflammatory responses

Intradermal inoculation of cloned self-reactive alphabeta T cells into the footpads of mice induced cutaneous graft-versus-host disease (GVHD), and after recovery from GVHD, the epidermis became resistant to subsequent attempts to induce GVHD. Resistance to GVHD was not induced in the epidermis of T-cell receptor delta-deficient (TCRdelta(-/-)) mice that lacked gammadelta T cells bearing canonical Vgamma5/Vdelta1(+)gammadeltaTCRs, known as dendritic epidermal T cells (DETCs), and resistance was restored by reconstitution of these mutant mice with precursors of Vgamma5(+) DETCs. Pulmonary infection by Cryptococcus neoformans induced an increase of gammadelta T cells in the lung, and in comparison with wildtype mice, TCRdelta(-/-) mice eliminated C. neoformans more rapidly and synthesized more interferon-gamma in the lung. In the mouse small intestine, the absence of gammadelta T cells is associated with a reduction in epithelial cell turnover and downregulation of the expression of major histocompatibility complex class II molecules. The protective role of gammadelta T cells was verified in a dextran sodium sulfate-induced inflammatory bowel disease (IBD) model, whereas in a spontaneous model of IBD, gammadelta T cells were involved in the exacerbation of colitis in TCRalpha(-/-) mice. Taken together, in addition to the homeostatic regulation of epithelial tissues, gammadelta T cells appear to play a pivotal role in the modification of inflammatory responses induced in many organs containing epithelia.

Repertoire of the alpha beta T-cell receptor in the intestine

The majority of T cells in the human and mouse intestine express the T-cell receptor (TCR) as an alphabeta heterodimer on their cell surface. As the major recognition element of antigens in the context of major histocompatibility complex-derived proteins, an examination of the structure of the alpha beta TCR in intestines has provided significant insights into the potential function of these cells and the major determinants that drive their selection. Studies in the human intestine have shown that the repertoires of intraepithelial lymphocytes (IELs), and likely lamina propria lymphocytes, are polyclonal before and shortly after birth, with the repertoire becoming oligoclonal in adults. Similarly, in adult mice the repertoire is oligoclonal, while in the newborn it is polyclonal. Investigations in mice have shown that some T cells may evade thymic selection. The population size and oligoclonality of IELs is influenced by the microbial content of the luminal microenvironment. This microenvironment probably directly determines the TCR repertoire. Studies in human inflammatory bowel disease (IBD) indicate that inflammation further skews the TCR repertoire. We speculate that dominant antigens associated with the pathogenesis of IBD are responsible for such skewing and that identifying the antigenic drivers may shed light on the environmental factors that trigger or potentiate human IBD.

Epithelial Defence by γδ T Cells

Gamma delta T cells constitute a separate lineage of T lymphocytes which differ from conventional alpha beta T cells with regard to T cell receptor (TCR) repertoire and tissue localization. In murine skin, gamma delta T cells expressing a canonical V gamma5 TCR are abundant and contribute as so-called dendritic epidermal T cells to local immune surveillance. In humans, major subsets of gammadelta T cells are recognized on the basis of their TCR V delta usage. While V delta2 cells dominate in the peripheral blood, V delta1 cells are preferentially localized in mucosal tissue including the intestinal epithelia. In this article we summarize basic features of intraepithelial gamma delta T cells and discuss their possible role in epithelial defence.

A primary dysregulation in the immunoregulatory role of the intestinal mucosal epithelial cell in inflammatory bowel disease pathogenesis? Biology of inflammatory response as tissue pattern entities in Crohn's versus ulcerative colitis

Within a framework of dual involvement of mucosa and submucosa on the one hand, and of the muscularis propria of the bowel wall on the other, it might be valid to consider involvement of the vascular supply as the essential means in itself of not only causing the morphologic lesions in inflammatory bowel disease, but also especially in accounting for persisting patterns of inflammatory response both in ulcerative colitis and in Crohn's disease. Inflammatory bowel disease as a group constitutes a spectrum of biologic and pathobiologic manifestations in terms not only of inflammatory involvement of the bowel wall but also in terms of how the bowel in its turn deals with inflammation as a pathologic lesion in its own right. Parameters of inflammatory bowel activity transcend simple concepts of etiology and pathogenesis as applicable to category disorders such as infections or bowel ischemia. Indeed, the strictly characterized initiation of the inflammatory bowel response as a function of defective regulation of the antigenicity of the luminal contents on the one hand, and on interactions between nitric oxide and free oxygen radicals on the other, might help determine a persistence of tissue damage in inflammatory bowel disease that is either relapsing/remitting or chronic in progression. In a final analysis, perhaps, there might be involved a single central form of pathway induction of dysregulated immune reactivity arising from an early disturbance in activation patterns as induced by the onset of luminal antigenicity at an early or specific-stage, further characterized perhaps by specific forms of intestinal epithelial defects of the bowel mucosa in patients subsequently developing inflammatory bowel disease. Specific genetic markers for disease susceptibility and for therapeutic responsiveness are particularly of interest. The Nucleotide binding oligomerization Domain 2 (NOD2) would recognize microbial lipopolysaccharide or else mark systemic responses to pathogens that are pathogenic to evolving inflammatory bowel disease.