Reciprocal changes of Foxp3 expression in blood and intestinal mucosa in IBD patients responding to infliximab

Diversity and function of regulatory T cells in health and autoimmune diseases

Regulatory T cell (Treg) play a pivotal role in immune regulation and maintaining host immune homeostasis. Treg heterogeneity, characterized by diverse gene expression profiles and functional states, is complex in both health and disease. Research reveals that Tregs are not a uniform population but exhibit diversity based on their origin, location, and functional status. This heterogeneity is crucial for understanding Treg roles in various pathological conditions. Dysfunctional Tregs are closely linked to the pathogenesis of autoimmune diseases, although the precise mechanisms remain unclear. The phenotypic and functional heterogeneity of Tregs is particularly significant in diseases such as systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, type 1 diabetes, psoriasis and autoimmune liver diseases. This review explores Treg origins, classifications, and heterogeneity in these conditions, aiming to provide new perspectives and strategies for diagnosis and treatment. Understanding Treg heterogeneity and plasticity promises to reveal novel therapeutic targets and advance precision immunotherapy development.

Potential of using an engineered indole lactic acid producing Escherichia coli Nissle 1917 in a murine model of colitis

The gut microbiome is a significant factor in the pathophysiology of ulcerative colitis (UC), prompting investigations into the use of probiotic therapies to counter gastrointestinal inflammation. However, while much attention has been given to the therapeutic potential of microbes at the species and strain level, the discovery and application of their metabolic products may offer more precise and controlled solutions in battling disease. In this work, we examined the therapeutic potential of indole lactic acid (ILA) to alleviate inflammation in a murine model of colitis. A previously constructed ILA-producing Escherichia coli Nissle 1917 strain (EcN aldh) and its isogenic non-ILA producing counterpart (EcN) were studied in a murine model of Dextran Sodium Sulfate (DSS) induced colitis. The colitic animals suffered from severe colitic symptoms, with no differentiation between the groups in body weight loss and disease activity index. However, three days after cessation of DSS treatment the EcN aldh-treated mice showed signs of reduced intestinal inflammation, as manifested by lower concentrations of fecal lipocalin-2. Additionally, expression analysis of the inflamed tissue revealed distinct effects of the EcN aldh strain on proteins associated with intestinal health, such as TFF3, occludin and IL-1β expression. These results show no impact of EcN or EcN aldh on acute DSS-induced colitis, but suggest that in particular EcN aldh may assist recovery from intestinal inflammation.

Identification of immune cell markers associated with ulcerative colitis histological disease activity in colonic biopsies

AIMS

Accurate determination of histological activity in ulcerative colitis (UC) is essential given its diagnostic and prognostic importance. Data on the relationship between histology and immune cell markers are limited. We aimed to evaluate the association between histological disease activity and immune cell marker concentration in colonic biopsies from patients with UC.

METHODS

Sigmoid colon biopsies from 20 patients with UC were retrospectively assessed using the Robarts Histopathology Index (RHI). Targeted mass spectrometry determined the concentration of 18 immune cell markers (cluster of differentiation (CD) 4, CD8, CD19, CD20, CD40, CD56, CD68, CD103, forkhead box p3 (FOXP3), human leucocyte antigen, DR alpha chain (HLA-DRA), interleukin 10 (IL-10), IL-23 subunit alpha (IL-23A), IL-23 receptor (IL-23R), IL-2 receptor alpha chain (IL-2RA), Ki67, lymphocyte-activation gene 3 (LAG-3), programmed cell death protein 1 (PD-1) and PD ligand 1 (PD-L1)). The association between RHI score and immune cell marker concentration was quantified using Spearman's rank correlation coefficient (ρ) and related 95% CIs.

RESULTS

Fourteen of the 18 immune cell marker proteins were detected, with tissue concentration ranging from 0.003 to 11.53 fmol/µg. The overall RHI score was positively correlated with CD19, CD20, CD40, FOXP3, LAG-3, PD-1 and PD-L1 concentration (ρ=0.596-0.799) and negatively correlated with CD56 concentration (ρ=-0.460). There was no significant association between RHI score and CD4, CD8, CD68, CD103, HLA-DRA or Ki67 concentration.

CONCLUSIONS

This study provides insight into the correlation between immune cell marker expression and histological disease activity and the possible molecular and immunological determinants underlying microscopic disease activity in UC.

Lrig1-expression confers suppressive function to CD4+ cells and is essential for averting autoimmunity via the Smad2/3/Foxp3 axis

Regulatory T cells (Treg) are CD4+ T cells with immune-suppressive function, which is defined by Foxp3 expression. However, the molecular determinants defining the suppressive population of T cells have yet to be discovered. Here we report that the cell surface protein Lrig1 is enriched in suppressive T cells and controls their suppressive behaviors. Within CD4+ T cells, Treg cells express the highest levels of Lrig1, and the expression level is further increasing with activation. The Lrig1+ subpopulation from T helper (Th) 17 cells showed higher suppressive activity than the Lrig1- subpopulation. Lrig1-deficiency impairs the suppressive function of Treg cells, while Lrig1-deficient naïve T cells normally differentiate into other T cell subsets. Adoptive transfer of CD4+Lrig1+ T cells alleviates autoimmune symptoms in colitis and lupus nephritis mouse models. A monoclonal anti-Lrig1 antibody significantly improves the symptoms of experimental autoimmune encephalomyelitis. In conclusion, Lrig1 is an important regulator of suppressive T cell function and an exploitable target for treating autoimmune conditions.

Peripheral blood T-lymphocyte subsets are potential biomarkers of disease severity and clinical outcomes in patients with ulcerative colitis: a retrospective study

BACKGROUND

Ulcerative colitis (UC) is considered an immune-mediated disease. The disorder of T-lymphocyte subsets plays an important role in the pathogenesis of UC. The aim of this study was to evaluate the significance of peripheral blood T-lymphocyte subsets in assessing disease severity and predicting clinical outcomes in UC patients.

METHODS

The retrospective case-control study was performed in 116 UC patients with active disease and 90 healthy controls (HC). The UC patients included were followed up for 180 days. Analyses of t-test, Spearman's correlation coefficient, multivariable Cox regression analysis, receiver operating characteristic (ROC) curves and cumulative survival analysis were done.

RESULTS

The UC patients had lower proportions of CD4⁺T cells (42.85%±9.77% vs 45.71%±7.94%, P=0.021) and higher proportion of CD8⁺T cells (27.88%±8.86% vs 25.00%±6.47%, P=0.008) than HC. The severely active UC patients had higher proportion of CD3⁺HLA-DR⁺ T cells (8.83%±6.55% vs 2.80%±1.55%, P<0.001; 8.83%±6.55% vs 4.06%±5.01%, P<0.001) and CD8⁺T cells (31.35%±8.49% vs 26.98%±7.98%, P=0.029; 31.35%±8.49% vs 25.46%±9.15%, P=0.003) than mild and moderate group, whereas lower proportion of CD4⁺CD25⁺T cells (2.86%±1.35% vs 3.46%±1.07%, P=0.034) than mild group and CD4⁺T cells (40.40%±9.36% vs 44.73%±10.39%, P=0.049) than moderate group. The area under the curve (AUC) of CD3⁺HLA-DR⁺ T cells for assessing severely active UC was 0.885, with the cut-off value of 5.33%. The sensitivity was 76.32% and specificity was 89.74%. The combination of CD3⁺HLA-DR⁺ T cells and CRP had stronger assessment value with AUC of 0.929. The AUC of CD8⁺T cells, CD4⁺/CD8⁺ ratio and CD4⁺CD25⁺T cells for assessing disease severity was 0.677, 0.669 and 0.631 respectively. Within the 180 days follow-up, 24 patients (20.69%) had UC-related readmission or surgery, with higher proportion of CD3⁺HLA-DR⁺ T cells (10.66%±9.52% vs 3.88%±2.56%, P=0.003) and CD8⁺T cells (31.19%±10.59% vs 27.01%±8.20%, P=0.039) than those without readmission and surgery. The proportion of CD3⁺HLA-DR⁺ T cells was the independent predictor of UC-related readmission or surgery (HR=1.109, P=0.002). The AUC of CD3⁺HLA-DR⁺ T cells for predicting readmission or surgery was 0.796 with the cut-off value of 5.38%. UC patients with CD3⁺HLA-DR⁺T cells proportion>5.38% had a shorter time to readmission or surgery (log-rank test, P<0.001).

CONCLUSIONS

The combination of CD3⁺HLA-DR⁺T cells and CRP may be potential biomarker of disease severity in UC patients. The high proportion of CD3⁺HLA-DR⁺T cells may be associated with an increased risk of readmission or surgery in UC patients.

Regulatory T cells as a therapeutic approach for inflammatory bowel disease

Foxp3+ T regulatory (Treg) cells suppress inflammation and are essential for maintaining tissue homeostasis. A growing appreciation of tissue-specific Treg functions has built interest in leveraging the endogenous suppressive mechanisms of these cells into cellular therapeutics in organ-specific diseases. Notably, Treg cells play a critical role in maintaining the intestinal environment. As a barrier site, the gut requires Treg cells to mediate interactions with the microbiota, support barrier integrity, and regulate the immune system. Without fully functional Treg cells, intestinal inflammation and microbial dysbiosis ensue. Thus, there is a particular interest in developing Treg cellular therapies for intestinal inflammatory disease, such as inflammatory bowel disease (IBD). This article reviews some of the critical pathways that are dysregulated in IBD, Treg cell mechanisms of suppression, and the efforts and approaches in the field to develop these cells as a cellular therapy for IBD.

Therapeutic potential of mesenchymal stem/stromal cells (MSCs)-based cell therapy for inflammatory bowel diseases (IBD) therapy

Recently, mesenchymal stem/stromal cells (MSCs) therapy has become an emerging therapeutic modality for the treatment of inflammatory bowel disease (IBD), given their immunoregulatory and pro-survival attributes. MSCs alleviate dysregulated inflammatory responses through the secretion of a myriad of anti-inflammatory mediators, such as interleukin 10 (IL-10), transforming growth factor-β (TGFβ), prostaglandin E2 (PGE2), tumor necrosis factor-stimulated gene-6 (TSG-6), etc. Indeed, MSC treatment of IBD is largely carried out through local microcirculation construction, colonization and repair, and immunomodulation, thus alleviating diseases severity. The clinical therapeutic efficacy relies on to the marked secretion of various secretory molecules from viable MSCs via paracrine mechanisms that are required for gut immuno-microbiota regulation and the proliferation and differentiation of surrounding cells like intestinal epithelial cells (IECs) and intestinal stem cells (ISCs). For example, MSCs can induce IECs proliferation and upregulate the expression of tight junction (TJs)-associated protein, ensuring intestinal barrier integrity. Concerning the encouraging results derived from animal studies, various clinical trials are conducted or ongoing to address the safety and efficacy of MSCs administration in IBD patients. Although the safety and short-term efficacy of MSCs administration have been evinced, the long-term efficacy of MSCs transplantation has not yet been verified. Herein, we have emphasized the illumination of the therapeutic capacity of MSCs therapy, including naïve MSCs, preconditioned MSCs, and also MSCs-derived exosomes, to alleviate IBD severity in experimental models. Also, a brief overview of published clinical trials in IBD patients has been delivered.

Astragaloside Ⅳ alleviates ulcerative colitis by regulating the balance of Th17/Treg cells

BACKGROUND

Restoring immune homeostasis by targeting the Th17/Treg response is a potentially valuable therapeutic strategy for ulcerative colitis (UC). Astragaloside IV (AS-Ⅳ) is a phytochemical naturally occurring in Astragalus membranaceus that has good anti-inflammatory, anti-oxidant and anti-stress properties. However, the effects of AS-IV on the homeostasis of Th17/Treg cells in colitis mice remains unknown.

PURPOSE

To investigate the protective effects and potential immunomodulatory mechanisms of AS-IV on UC.

METHODS

This study was constructed for DSS-induced acute colitis and recurrent colitis, with AS-IV administered prophylactically and therapeutically, respectively. The balance of Th17/Treg cells was analyzed by flow cytometry, their specific nuclear transcription factors were detected by RT-PCR as well as their secreted inflammatory cytokines were detected by ELISA and RT-PCR. Notch signaling-related proteins were detected by RT-PCR and Western blotting. Oxidative stress indicators were measured by biochemical technology.

RESULTS

In this study, AS-IV treatment not only effectively prevented and alleviated the clinical symptoms of DSS-induced colitis mice, including weight loss, DAI soaring, colon length shortening and colon weight gain, but also significantly improved ulcer formation, inflammatory cell infiltration and index, and regulated the expression of inflammatory cytokines in colon tissues. Importantly, the efficacy of high-dose AS-IV (100 mg/kg/day) in mice with recurrent colitis in this study was comparable to that of 5-ASA. AS-IV early administration was able to reshape the homeostasis of Th17/Treg cells in mice with acute colitis; meanwhile, AS-IV inhibited Th17 cell responses and promoted Treg cell responses in mice with recurrent colitis. Moreover, AS-IV not only inhibited the activation of Notch signaling pathway in colitis mice, but also prevented and ameliorated DSS-induced oxidative stress injury.

CONCLUSION

In conclusion, AS-IV effectively prevented and alleviated UC by reshaping Th17/Treg cell homeostasis and anti-oxidative stress.

Biomarkers for Optimization and Personalization of Anti-TNFs in Pediatric Inflammatory Bowel Disease

The use of biological drugs has improved outcomes in pediatric inflammatory bowel disease (IBD). Prediction of the response to biological drugs would be extremely useful in IBD, and even more so in children, who are still growing physically and psychologically. Specific clinical, biochemical, and genetic parameters are considered predictive of response to biological drugs, although few studies have been carried out in children with IBD. In this review, we present current evidence on biological treatments used in pediatric IBD and the available biomarkers of response. We examine demographics, clinical characteristics, biomarkers (genetic, genomic, and cellular), and microbiota.

Anti-tumour necrosis factor α antibodies and circulating lymphocyte phenotypes in inflammatory bowel disease

OBJECTIVE

Circulating lymphocyte subtypes are not fully explored parameters for monitoring chronic T cell activation during inflammatory bowel disease (IBD). Tumor necrosis factor α (TNFα), one of the main mediators of IBD related inflammation induces expression of CD70 on T cells. CD70 limits T cell expansion and controls CD27 receptor on activated B lymphocytes. Aim of this study was to assess the number and the frequency of CD70+ T cells and CD27+ B cells in IBD patients during inactive phase of the disease under or without anti-TNFα treatment.

DESIGN

We studied 91 patients with inactive IBD, 31 untreated, 29 treated with infliximab (IFX), and 31 treated with adalimumab (ADA). Lymphocyte phenotypes were assessed by flow cytometry using anti-CD45, CD19, CD27, CD3, and CD70 monoclonal antibodies. IFX and ADA actual capacity of TNFα neutralization in serum was estimated by the recoveryELISA technique.

RESULTS

Whereas CD3+ T cells were increased in treated compared to untreated patients, the percentage of the CD70+ T cells was significantly lower in treated patients indicating a 'cooling' effect of the biological therapy. This effect differs between samples according to the therapeutic range of the circulating drug. Although the CD19+ B-cell percentage tended to be lower in treated patients, CD19+27+ memory B cells did not show significant differences between groups.

CONCLUSIONS

Frequency of peripheral blood CD70+ T cells was significantly reduced by treatment with anti-TNFα antibodies. Monitoring of this parameter of T cells can give better insight to the disease progression and therapy application in IBD patients.

Biological Treatments in Inflammatory Bowel Disease: A Complex Mix of Mechanisms and Actions

Inflammatory bowel disease (IBD) is a chronic disease that requires lifelong medication and whose incidence is increasing over the world. There is currently no cure for IBD, and the current therapeutic objective is to control the inflammatory process. Approximately one third of treated patients do not respond to treatment and refractoriness to treatment is common. Therefore, pharmacological treatments, such as monoclonal antibodies, are urgently needed, and new treatment guidelines are regularly published. Due to the extremely important current role of biologics in the therapy of IBD, herein we have briefly reviewed the main biological treatments currently available. In addition, we have focused on the mechanisms of action of the most relevant groups of biological agents in IBD therapy, which are not completely clear but are undoubtfully important for understanding both their therapeutic efficacy and the adverse side effects they may have. Further studies are necessary to better understand the action mechanism of these drugs, which will in turn help us to understand how to improve their efficacy and safety. These studies will hopefully pave the path for a personalized medicine.

Insights into the biology and therapeutic implications of TNF and regulatory T cells

Treatments that block tumour necrosis factor (TNF) have major beneficial effects in several autoimmune and rheumatic diseases, including rheumatoid arthritis. However, some patients do not respond to TNF inhibitor treatment and rare occurrences of paradoxical disease exacerbation have been reported. These limitations on the clinical efficacy of TNF inhibitors can be explained by the differences between TNF receptor 1 (TNFR1) and TNFR2 signalling and by the diverse effects of TNF on multiple immune cells, including FOXP3⁺ regulatory T cells. This basic knowledge sheds light on the consequences of TNF inhibitor therapies on regulatory T cells in treated patients and on the limitations of such treatment in the control of diseases with an autoimmune component. Accordingly, the next generation of drugs targeting TNF is likely to be based on agents that selectively block the binding of TNF to TNFR1 and on TNFR2 agonists. These approaches could improve the treatment of rheumatic diseases in the future.

Evaluation of anti-TNF therapeutic response in patients with inflammatory bowel disease: Current and novel biomarkers

Neutralizing tumour necrosis factor (TNF) antibodies have been widely used to treat inflammatory bowel disease (IBD) in the clinical practice. In this review, the principal biomarker analysis revealed that faecal calprotectin, C-reactive protein, serum or mucosal concentrations of anti-TNF monoclonal antibodies (mAbs) and antibodies to anti-TNF mAbs are commonly used as current biomarkers in the evaluation of anti-TNF therapeutic efficacy. However, mucosal cytokine transcripts. microRNAs, proteomics and faecal and mucosal gut microbiota profile and mucosal histological features are reported to be novel candidates of biomarkers with high clinical utility in the evaluation of anti-TNF therapeutic efficacy in patients with IBD. Therefore, a robust validation of novel promising biomarkers and comparison studies between current used and novel biomarkers are urgently required to improve their value in the evaluation of therapeutic efficacy and optimization of personalized medicine and identification of IBD candidates for anti-TNF therapy in future clinical practice.

Distinct integrin activation pathways for effector and regulatory T cell trafficking and function

Integrin activation mediates lymphocyte trafficking and immune functions. Conventional T cell (Tconv cell) integrin activation requires Rap1-interacting adaptor molecule (RIAM). Here, we report that Apbb1ip-/- (RIAM-null) mice are protected from spontaneous colitis due to IL-10 deficiency, a model of inflammatory bowel disease (IBD). Protection is ascribable to reduced accumulation and homing of Tconv cells in gut-associated lymphoid tissue (GALT). Surprisingly, there are abundant RIAM-null regulatory T cells (T reg cells) in the GALT. RIAM-null T reg cells exhibit normal homing to GALT and lymph nodes due to preserved activation of integrins αLβ2, α4β1, and α4β7. Similar to Tconv cells, T reg cell integrin activation and immune function require Rap1; however, lamellipodin (Raph1), a RIAM paralogue, compensates for RIAM deficiency. Thus, in contrast to Tconv cells, RIAM is dispensable for T reg cell integrin activation and suppressive function. In consequence, inhibition of RIAM can inhibit spontaneous Tconv cell-mediated autoimmune colitis while preserving T reg cell trafficking and function.

CELL THERAPY IN INFLAMMATORY BOWEL DISEASE

In recent years, cell-based therapies have been explored in various immune-mediated inflammatory diseases, including inflammatory bowel disease (IBD). Cell therapy is the process of introducing new cells into an organism or tissue in order to treat a disease. The most studied cellular treatment in IBD was "stem cells-based therapy", which was explored according to different protocols in terms of type of donors, stem cells sources, study design and clinical endpoints. More recently, preliminary studies have also described the clinical use of "regulatory cells", which include T-reg and Tr1 cells, and "tolerogenic" dendritic cells. Finally, induced pluripotent stem cells are the subject of an intensive preclinical research program on animal models, including those related to colitis.

Enhancement of Circulating and Intestinal T Regulatory Cells and Their Expression of Helios and Neuropilin-1 in Children with Inflammatory Bowel Disease

Background/Aims

The proportions of intestinal and peripheral regulatory T cells (Tregs) in pediatric inflammatory bowel disease (IBD) were poorly investigated, as well as different subsets of these cells. Helios and Neuropilin-1 were proposed as markers differentiating between thymic and peripheral Tregs. Therefore, the aim of current work was to investigate the proportions of Tregs and expression of Helios and Neuropilin-1 in Tregs in peripheral blood and intestinal mucosa of children with inflammatory bowel disease.

Materials and methods

Fifteen patients newly diagnosed with inflammatory bowel disease: ulcerative colitis (n=7) and Crohn's disease (n=8) were included in the study. Nine children who presented with no abnormalities in colonoscopy served as a control group. Quantification of regulatory T cells of the CD4⁺CD25^highFOXP3⁺ phenotype, as well as Helios⁺ and Neuropilin-1⁺ in peripheral blood and bowel mucosa was based on multicolor flow cytometry.

Results

The rates of circulating and intestinal Tregs were significantly higher in the studied group than in the control group. The rate of intestinal T regulatory lymphocytes was significantly higher than circulating Tregs in patients with IBD, but not in the control group. The median proportion of circulating FOXP3⁺Helios⁺ cells amounted to 24.83% in IBD patients and 15.93% in the controls. The median proportion of circulating FOXP3⁺Nrp-1⁺ cells was 34.23% in IBD and 21.01% in the control group. No statistically significant differences were noted for the circulating FOXP3⁺Helios⁺ cells and FOXP3⁺Nrp-1⁺ cells between the studied and the control group.

Conclusion

The rates of circulating and intestinal T regulatory cells are increased in naïve pediatric patients with IBD. The rate of Tregs is higher in intestinal mucosa than in peripheral blood in patients with IBD. Flow cytometry is a valuable method assessing the composition of infiltrates in inflamed tissue. Helios and Neuropilin-1 likely cannot serve as markers to differentiate between natural and adaptive Tregs.

Qingchang Huashi granule ameliorates experimental colitis via restoring the dendritic cell-mediated Th17/Treg balance

BACKGROUND

The balance between T helper 17 (Th17) cells and regulatory T cells (Tregs) is involved in immunological tolerance. Destruction of immunological tolerance by dendritic cell (DC)-mediated T cells is involved in the pathogenesis of ulcerative colitis (UC). Qingchang Huashi granule (QCHS) has been confirmed in the treatment of UC involved by inhibiting the activation of DCs. The aim of this study was to investigate the mechanism through which QCHS restores the Th17/Treg balance by modulating DCs in the treatment of UC.

METHODS

The effects of QCHS on Th17 cells, Tregs and DCs were detected in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis model. Furthermore, we injected QCHS-treated DCs into colitis model to test whether QCHS modulates the Th17/Treg balance via DCs. Tregs and Th17 cells were analyzed by FACS. IL-10, IL-17, and Foxp3 were measured by ELISA, Western blot and qRT-PCR.

RESULTS

Both QCHS and QCHS-treated DCs improved colonic histopathology, diminished Th17 cell differentiation and inhibited IL-17 production while promoting CD4+CD25+Foxp3+ Treg differentiation and augmenting IL-10 and Foxp3 expression in colitis mice. Additionally, QCHS reduced CD86 and MHC-II expression on DCs, decreased IL-12 production ex vivo and restored the Th17/Treg ratio in the colitis model.

CONCLUSION

The findings of this study indicate that QCHS ameliorates TNBS-induced colitis by restoring the DC-mediated Th17/Treg balance.

Regulatory T cells in Crohn's disease following anti-TNF-α therapy

BACKGROUND AND AIM

Anti-tumor necrosis factor alpha (TNF-α) therapy is an effective therapy for Crohn's disease (CD). We investigated FoxP3+ and CD127- regulatory T cells (Tregs) before and after administration of anti-TNF-α therapy in CD.

METHODS

Eight patients with active CD who had received anti-TNF-α antibodies were enrolled. Treatment responses were followed by physical examination and Crohn's disease activity index (CDAI) scoring before and 2 weeks after the initial administration of anti-TNF-α antibodies. Peripheral blood samples were collected before and 2 weeks after treatment. White blood cell count and serum levels of C-reactive protein (CRP) and albumin were measured. FoxP3+ expression and CD127- Tregs were measured by fluorescence activated cell sorting (FACS) analysis of whole blood samples.

RESULTS

Median values of CDAI decreased significantly after treatment. The proportion of FoxP3+ Tregs increased significantly after treatment. There was a significant negative correlation between ΔCD127- Tregs and Δlymphocyte.

CONCLUSIONS

Anti-TNF-α therapy would enhance Tregs, which may account for the mechanism underlying the positive effect of the anti-TNF-α treatment in CD patients.

Dissecting the Heterogeneity in T-Cell Mediated Inflammation in IBD

Infiltration of the lamina propria by inflammatory CD4+ T-cell populations is a key characteristic of chronic intestinal inflammation. Memory-phenotype CD4+ T-cell frequencies are increased in inflamed intestinal tissue of IBD patients compared to tissue of healthy controls and are associated with disease flares and a more complicated disease course. Therefore, a tightly controlled balance between regulatory and inflammatory CD4+ T-cell populations is crucial to prevent uncontrolled CD4+ T-cell responses and subsequent intestinal tissue damage. While at steady state, T-cells display mainly a regulatory phenotype, increased in Th1, Th2, Th9, Th17, and Th17.1 responses, and reduced Treg and Tr1 responses have all been suggested to play a role in IBD pathophysiology. However, it is highly unlikely that all these responses are altered in each individual patient. With the rapidly expanding plethora of therapeutic options to inhibit inflammatory T-cell responses and stimulate regulatory T-cell responses, a crucial need is emerging for a robust set of immunological assays to predict and monitor therapeutic success at an individual level. Consequently, it is crucial to differentiate dominant inflammatory and regulatory CD4+ T helper responses in patients and relate these to disease course and therapy response. In this review, we provide an overview of how intestinal CD4+ T-cell responses arise, discuss the main phenotypes of CD4+ T helper responses, and review how they are implicated in IBD.

β7 Integrin Inhibition Can Increase Intestinal Inflammation by Impairing Homing of CD25hiFoxP3+ Regulatory T Cells

BACKGROUND & AIMS

Integrin α4β7 mediates lymphocyte trafficking to the gut and gut-associated lymphoid tissues, a process critical for recruitment of effector lymphocytes from the circulation to the gut mucosa in inflammatory bowel disease (IBD) and murine models of intestinal inflammation. Antibody blockade of β7 integrins generally is efficacious in IBD; however, some patients fail to respond, and a few patients can experience exacerbations. This study examined the effects of loss of β7 integrin function in murine models of IBD.

METHODS

In a mouse IBD model caused by lack of interleukin 10, a cytokine important in CD25hiFoxP3+ regulatory T cell (Treg) function, genetic deletion of β7 integrin or antibody blockade of α4β7-mucosal addressin cell adhesion molecule-1 interaction paradoxically exacerbated colitis.

RESULTS

Loss of β7 impaired the capacity of Tregs homing to the gut and therefore suppress intestinal inflammation in an adoptive T-cell transfer model; however, the intrinsic suppressive function of β7-deficient Tregs remained intact, indicating that the β7 deficiency selectively impacts gut homing. Deletion of β7 integrin did not worsen colitis in an acute dextran sodium sulfate model in which Treg number and function were normal.

CONCLUSIONS

In Integrin subunit beta (Itgb)7-/-Il10-/- mice, loss of β7-dependent Treg homing to gut-associated lymphoid tissues combined with loss of intrinsic Treg function exacerbated intestinal inflammation. These results suggest that IBD patients with reduced CD25hiFoxP3+ Treg numbers or function or lack of interleukin 10 could be at risk for failure of α4β7 blocking therapy.

Redefining the IBDs using genome-scale molecular phenotyping

The IBDs, Crohn's disease and ulcerative colitis, are chronic inflammatory conditions of the gastrointestinal tract resulting from an aberrant immune response to enteric microbiota in genetically susceptible individuals. Disease presentation and progression within and across IBDs, especially Crohn's disease, are highly heterogeneous in location, severity of inflammation and other phenotypes. Current clinical classifications fail to accurately predict disease course and response to therapies. Genome-wide association studies have identified >240 loci that confer risk of IBD, but the clinical utility of these findings remains unclear, and mechanisms by which the genetic variants contribute to disease are largely unknown. In the past 5 years, the profiling of genome-wide gene expression, epigenomic features and gut microbiota composition in intestinal tissue and faecal samples has uncovered distinct molecular signatures that define IBD subtypes, including within Crohn's disease and ulcerative colitis. In this Review, we summarize studies in both adult and paediatric patients that have identified different IBD subtypes, which in some cases have been associated with distinct clinical phenotypes. We posit that genome-scale molecular phenotyping in large cohorts holds great promise not only to further our understanding of the diverse molecular causes of IBD but also for improving clinical trial design to develop more personalized disease management and treatment.

Mechanisms of molecular resistance and predictors of response to biological therapy in inflammatory bowel disease

Biological therapy has led to marked improvements in treatment of patients with inflammatory bowel disease, and an increasing number of drugs has been approved for treatment. However, only a subgroup of patients responds to therapy, highlighting the need to identify biomarkers for therapeutic response to allow personalised medicine in inflammatory bowel disease. Potential markers of response to biological therapy have been identified; however, studies also suggest that changes in the composition of immune cell infiltrates in response to therapeutic pressure lead to molecular resistance to these drugs. For instance, the cytokine interleukin 23 has been identified as a driver of evasion of apoptosis in response to anti-tumour necrosis factor drugs in patients with Crohn's disease, leading to expansion of apoptosis-resistant T cells and drug resistance. In this Review, we examine the concept of molecular resistance to biological therapy and discuss implications for future therapy.

Reappraisal of antibodies against Saccharomyces cerevisiae (ASCA) as persistent biomarkers in quiescent Crohn's disease

A clear correlation exists between microbiota and the dysregulation of the immune response in Inflammatory Bowel Diseases (IBD), which comprise Crohn's disease (CD) and ulcerative colitis (UC). These unbalanced reactions also involve humoral responses, with antibodies against Saccharomyces cerevisiae. Thus, here we aimed to quantify IgA and IgG specific to S. cerevisiae (ASCA) in quiescent CD and UC, to correlate the production of these antibodies with patient's inflammatory response and disease clinical presentation. Twenty-nine subjects (16 CD and 13 UC) and 45 healthy controls were enrolled in this study and had plasma samples tested for ASCA and cytokines (IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α), besides clinical evaluation. IBD patients had increase IgA and IgG ASCA, especially those with colonic (L2) and fistulizing (B3) CD. Similarly, patients who dropped out the treatment had augmented ASCA, while IgG was reduced in those receiving sulfasalazine treatment. Furthermore, the quiescent CD patients had elevated IL-6 on plasma, especially in the absence of treatment, together with increased counter regulatory response of IL-10. There was a positive correlation between IgA and IgG on CD but not UC, as well as between IgA and TNF in total IBD patients. In addition, the levels of IgG x TNF, IgA x IL-10 and IgG x IL-10 were also correlated in CD, indicating that ASCA production may be influenced by the inflammatory response. Finally, we concluded that ASCA could be pointed as relevant biomarker of CD presentation and residual inflammation, even in clinical remission patients.

Association of Ulcerative Colitis with FOXP3 Gene Polymorphisms and Its Colonic Expression in Chinese Patients

Abnormalities of forkhead box P3 (FOXP3) are implicated in various autoimmune diseases. This study is aimed at investigating the association of ulcerative colitis (UC) with FOXP3 polymorphisms and its colonic expression in Chinese patients. Polymorphisms of rs3761548, rs2232365, rs2294021, and rs3761547 were examined in 472 UC patients and 525 healthy controls using the SNaPshot method. The colonic expression of FOXP3 mRNA and protein was assayed in inflammatory mucosa of 34 UC patients and normal mucosa of 36 patients with benign sigmoid polyps (normal controls) using real-time quantitative polymerase chain reaction and immunohistochemical analysis. All data were handled separately for females and males. As a result, the carrier frequencies with at least one variant allele of rs3761548, rs2232365, and rs229402 increased in female and male UC patients compared with healthy controls. Significant differences in these carrier frequencies were also observed between patients with mild and moderate UC and patients with severe UC. The expression of FOXP3 was higher in UC patients (both males and females), especially those with severe UC, than in normal controls. The expression of FOXP3 was downregulated in UC patients having at least one variant allele compared with UC patients having no variant allele of rs3761548, rs2232365, and rs2294021. Male gender (β = −0.341), rs2294021 variation (β = −0.503), and severe UC (β = 0.361) were independently related to the mRNA expression of FOXP3 in UC patients. Together, our findings indicated that FOXP3 (rs3761548, rs2232365, and rs2294021) variations increased the risk of UC and were associated with the lower colonic expression of FOXP3 in UC patients.

miR-106a deficiency attenuates inflammation in murine IBD models

Pro-inflammatory cytokine TNFα antagonizes regulatory T cell (Treg) suppressive function with a measurable reduction of IL-10 protein secretion. Tregs are critical to suppress excessive immune activation, particularly within the intestine where high antigenic loads elicit chronic subclinical immune activation. Employing a TNFα-driven murine inflammatory bowel disease (IBD) model (TNF^ΔARE/+), which mirrors the Treg expansion and transmural ileitis seen in Crohn's disease, we demonstrate that the TNFα-mediated loss of Treg suppressive function coincides with induction of a specific miRNA, miR-106a in both humans and mice, via NFκB promoter binding to suppress post-transcriptional regulation of IL-10 release. Elevation of miR-106a and impaired Treg function in this model recapitulate clinical data from IBD patients. MiR-106a deficiency promotes Treg induction, suppressive function and IL-10 production in vitro. MiR-106a knockout attenuated chronic murine ileitis, whereas T cell restricted deficiency of miR-106a attenuated adoptive transfer colitis. In both models, attenuated inflammation coincided with suppression of both Th1 and Th17 cell subset expansion within the intestinal lamina propria. Collectively, our data demonstrate impaired Treg suppressive function in a murine IBD model consistent with human disease and support the potential for inhibition of miR-106a as a future therapeutic approach to treat chronic inflammatory conditions including IBD.

Histopathological Features of Inflammatory Bowel Disease are Associated With Different CD4+ T Cell Subsets in Colonic Mucosal Lamina Propria

BACKGROUND

Inflammatory bowel disease [IBD] results particularly from an aberrance of CD4+ helper and regulatory T cells and comprises histopathologically chronic active enterocolitis with features reflecting both activity and chronicity of mucosal inflammation. The exact immunological-histological correlation in IBD is not understood.

METHODS

We studied the correlation between colonic mucosal CD4+ T cell subsets [Th1, Th2, Th17, Th22 and Treg] and mucosal histological changes in ulcerative colitis [UC] and Crohn's disease [CD]. CD4+ T cell subtyping and enumeration were achieved by flow cytometry. Histological features were categorized and assessed semi-quantitatively using three validated histological scoring schemes [ECAP, RHI and D'Haens]. Correlations between prevalence [%] of CD4+ T cell subsets and histological scores were analysed.

RESULTS

Treg cells were correlated with ECAP category A [activity] as well as RHI scores. Treg cell were increased particularly in mucosa with severe neutrophilic infiltration in the cryptal/surface epithelium and in lamina propria, and with basal plasmacytosis. Th17 cells were also increased in cases with extensive neutrophil infiltrate in lamina propria, whereas RORc+ cells were increased in cases with severe lymphoplasmacytic infiltration in lamina propria. In both UC and CD, mucosa with marked crypt architectural alteration had increased IL-22+ and Th22 cells. UC with Paneth cell metaplasia had higher Th17 cells. CD with granuloma had increased IL-22+ and IL-22+IFN-γ+ cells.

CONCLUSIONS

The Treg subset appears to be associated with the overall severity of IBD histopathology, particularly with active inflammation. Th17 is also associated with activity. By contrast, IL-22+ cells are associated with chronicity and granuloma formation in CD.

Activation of LANCL2 by BT-11 Ameliorates IBD by Supporting Regulatory T Cell Stability Through Immunometabolic Mechanisms

BACKGROUND

Inflammatory bowel disease (IBD) afflicts 5 million people and is increasing in prevalence. There is an unmet clinical need for safer and effective treatments for IBD. The BT-11 is a small molecule oral therapeutic that ameliorates IBD by targeting lanthionine synthetase C-like 2 (LANCL2) and has a benign safety profile in rats.

METHODS

Mdr1a-/-, dextran sodium sulphate , and adoptive transfer mouse models of colitis were employed to validate therapeutic efficacy and characterize the mechanisms of therapeutic efficacy of BT-11. In vitro cultures of CD4+ T cell differentiation and human peripheral blood mononuclear cells from Crohn's disease patients were used to determine its potential for human translation.

RESULTS

BT-11 reduces inflammation in multiple mouse models of IBD. Oral treatment with BT-11 increases the numbers of lamina propria regulatory T cells (Tregs) in a LANCL2-dependent manner. In vitro, BT-11 increases the differentiation in Treg phenotypes, the upregulation of genes implicated in Treg cell stability, and conditions Treg cells to elicit greater suppressive actions. These immunoregulatory effects are intertwined with the ability of BT-11 to regulate late stage glycolysis and tricarboxylic acid cycle. Immunometabolic mechanistic findings translate into human peripheral blood mononuclear cells from healthy individuals and Crohn's disease patients.

CONCLUSIONS

BT-11 is a safe, efficacious oral therapeutic for IBD with a human translatable mechanism of action that involves activation of LANCL2, immunometabolic modulation of CD4+ T cell subsets leading to stable regulatory phenotypes in the colonic LP.

Infliximab restores colonic barrier to adherent-invasive E. coli in Crohn's disease via effects on epithelial lipid rafts

OBJECTIVE

Infliximab is important in the therapeutic arsenal of Crohn's disease (CD). However, its effect on mucosal barrier function is not fully understood. Adherent-invasive Escherichia coli (AIEC) are important in CD pathophysiology, but the transmucosal uptake routes are partly unknown. We investigated effects of infliximab on uptake of colon-specific AIEC HM427 across CD colonic mucosa.

MATERIALS AND METHODS

Endoscopic biopsies from non-inflamed colon of seven patients with CD, before and after two infliximab infusions, and eight non-inflammation controls, were mounted in Ussing chambers. Paracellular permeability (⁵¹Cr-EDTA) and transmucosal passage of GFP-expressing HM427 were studied. Mechanisms of HM427 transepithelial transport were investigated in Caco-2 monolayers treated with TNF, in the presence of infliximab and/or endocytosis inhibitors.

RESULTS

Before infliximab treatment, colonic passage of HM427 [CD: 2475 CFU (450-3000); controls 1163(225-1950)] and ⁵¹Cr-EDTA permeability were increased in CD (p < .05), but were restored to control levels by infliximab (CD: 150 (18.8-1069)). In TNF-exposed Caco-2 monolayers HM427 transport and lipid rafts/HM427 co-localization was decreased by infliximab. The lipid raft inhibitor methyl-β-cyclodextrin decreased HM427 transport.

CONCLUSION

Infliximab restored the colonic barrier to AIEC in CD; an effect partially mediated by blocking lipid rafts in epithelial cells. This ability likely contributes to infliximab's clinical efficacy in colonic CD.

Current, experimental, and future treatments in inflammatory bowel disease: a clinical review

Inflammatory bowel diseases (IBDs) may result from dysregulated mucosal immune responses directed toward the resident intestinal microbiota. This review describes the hallmark immunobiology of Crohn's disease and ulcerative colitis as well as therapeutic targets and mechanisms of action for current, experimental, and future treatments in IBD. Conventional therapies include 5-aminosalicylic acid, glucocorticosteroids, thiopurines, and methotrexate. Since 1997, monoclonal antibodies have gained widespread use. These consist of antibodies directed against pro-inflammatory cytokines such as tumor necrosis factor α, interleukin (IL)-12, and IL-23, or anti-homing antibodies directed against α4β7 integrin. Emerging oral therapies include modulators of intracellular signal transduction such as Janus kinase inhibitors. Vitamin D may help to regulate innate and adaptive immune responses. Modulation of the intestinal microbiota, using live microorganisms (probiotics), substrates for the colonic microbiota (prebiotics), or fecal microbiota transplantation (FMT), is in development. Dietary supplements are in widespread use, but providing evidence for their benefit is challenging. Stem cell treatment and nervous stimulation are promising future treatments.

Clinical Applications of Regulatory T cells in Adoptive Cell Therapies

Interest in adoptive T-cell therapies has been ignited by the recent clinical success of genetically-modified T cells in the cancer immunotherapy space. In addition to immune targeting for malignancies, this approach is now being explored for the establishment of immune tolerance with regulatory T cells (Tregs). Herein, we will summarize the basic science and clinical results emanating from trials directed at inducing durable immune regulation through administration of Tregs. We will discuss some of the current challenges facing the field in terms of maximizing cell purity, stability and expansion capacity, while also achieving feasibility and GMP production. Indeed, recent advances in methodologies for Treg isolation, expansion, and optimal source materials represent important strides toward these considerations. Finally, we will review the emerging genetic and biomaterial-based approaches on the horizon for directing Treg specificity to augment tissue-targeting and regenerative medicine.

Immunomodulatory effects of M2000 (β-D-Mannuronic acid) on TNF-α, IL-17 and FOXP3 gene expression in patients with inflammatory bowel disease

INTRODUCTION

Inflammatory bowel diseases (IBD) are immune-mediated disorders that result from an aberrant immunological response to the gut luminal antigen in genetically susceptible patients. IBD is categorized into two serotype, Crohn's diseases (CD) and ulcerative colitis (UC), both subtype are important cause of gastrointestinal diseases. The increasing rate of hospitalization, with the high economic burden experienced by the IBD patients, calls for more concerted research efforts to design a potent and affordable treatment option for the treatment of IBD.

AIMS/OBJECTIVE

This research was designed to test the efficacy and potency of β-D Mannuronic acid (M2000) and assess if it could serve as a better therapeutic option in the treatment of IBD.

METHODOLOGY

Ten (10)ml of blood was aseptically collected into an EDTA container, from 24 IBD patients and 24 normal healthy controls. PBMC was isolated and stimulated with 1μg/ml of LPS in cell culture plate and incubated for 4h. The cells were later treated with 10μg/ml and 50μg/ml of β-D Mannuronic acid (M2000) and incubated for 24h at 37°C under 5% CO2 and 100% humidity. The RNA extractions, cDNA synthesis, and QRT-PCR were performed.

RESULTS

Our findings showed a significant down-regulation of TNF-α and IL-17 gene expression, while the expression of FOXP3 gene was significantly up-regulated.

CONCLUSION

This result has indicated that β-D Mannuronic acid (M2000) have immunoregulatory and anti-inflammatory effects on these cytokines that are pivotal in the pathogenesis of IBD.

Can We Predict the Efficacy of Anti-TNF-α Agents?

The use of biologic agents, particularly anti-tumor necrosis factor (TNF)-α, has revolutionized the treatment of inflammatory bowel diseases (IBD), modifying their natural history. Several data on the efficacy of these agents in inducing and maintaining clinical remission have been accumulated over the past two decades: their use avoid the need for steroids therapy, promote mucosal healing, reduce hospitalizations and surgeries and therefore dramatically improve the quality of life of IBD patients. However, primary non-response to these agents or loss of response over time mainly due to immunogenicity or treatment-related side-effects are a frequent concern in IBD patients. Thus, the identification of predicting factors of efficacy is crucial to allow clinicians to efficiently use these therapies, avoiding them when they are ineffective and eventually shifting towards alternative biological therapies with the end goal of optimizing the cost-effectiveness ratio. In this review, we aim to identify the predictive factors of short- and long-term benefits of anti-TNF-α therapy in IBD patients. In particular, multiple patient-, disease- and treatment-related factors have been evaluated.

Extracts from Hericium erinaceus relieve inflammatory bowel disease by regulating immunity and gut microbiota

Hericium erinaceus (HE), a traditional edible mushroom, is known as a medicine food homology to ameliorate gastrointestinal diseases. To investigate whether HE is clinically effective in alleviating inflammatory bowel disease (IBD), HE extracts (polysaccharide, alcoholic extracts and whole extracts were prepared using solvent extraction methods) were administrated for 2 weeks in rats with IBD induced by trinitro-benzene-sulfonic acid (TNBS) enema (150 mg/kg). Significant clinical and histological changes in IBD rats were identified, including damage activity, common morphous and tissue damage index scores in colonic mucosa and myeloperoxidase (MPO) activity. The damage activity, common morphous and tissue damage index scores in colonic mucosa (P <0.05) were improved, MPO activities were decreased. Inflammatory factors were also differentially expressed in colonic mucosa in IBD rats, including serum cytokines, Foxp3 and interleukin (IL)-10 were increased while NF-κB p65 and tumor necrosis factor (TNF)-α were decreased (P <0.05), and T cells were activated (P <0.05), especially in the alcohol extracts-treated group. We also found that the structure of gut microbiota of the H. erinaceus extracts-treated groups changed significantly by compared with the model group. Further studies revealed that the polysaccharides in HE extracts may play a prebiotic role, whereas the alcoholic extracts show bactericidin-like and immunomodulatory effects. Taken together, we demonstrated that H. erinaceus extracts could promote the growth of beneficial gut bacteria and improve the host immunity in vivo IBD model, which shows clinical potential in relieving IBD by regulating gut microbiota and immune system.

Rapamycin is highly effective in murine models of immune-mediated bone marrow failure

Acquired aplastic anemia, the prototypical bone marrow failure disease, is characterized by pancytopenia and marrow hypoplasia. Most aplastic anemia patients respond to immunosuppressive therapy, usually with anti-thymocyte globulin and cyclosporine, but some relapse on cyclosporine withdrawal or require long-term administration of cyclosporine to maintain blood counts. In this study, we tested efficacy of rapamycin as a new or alternative treatment in mouse models of immune-mediated bone marrow failure. Rapamycin ameliorated pancytopenia, improved bone marrow cellularity, and extended animal survival in a manner comparable to the standard dose of cyclosporine. Rapamycin effectively reduced Th1 inflammatory cytokines interferon-γ and tumor necrosis factor-α, increased the Th2 cytokine interleukin-10, stimulated expansion of functional regulatory T cells, eliminated effector CD8⁺ T cells (notably T cells specific to target cells bearing minor histocompatibility antigen H60), and preserved hematopoietic stem and progenitor cells. Rapamycin, but not cyclosporine, reduced the proportion of memory and effector T cells and maintained a pool of naïve T cells. Cyclosporine increased cytoplasmic nuclear factor of activated T-cells-1 following T-cell receptor stimulation, whereas rapamycin suppressed phosphorylation of two key signaling molecules in the mammalian target of rapamycin pathway, S6 kinase and protein kinase B. In summary, rapamycin was an effective therapy in mouse models of immune-mediated bone marrow failure, acting through different mechanisms to cyclosporine. Its specific expansion of regulatory T cells and elimination of clonogenic CD8⁺ effectors support its potential clinical utility in the treatment of aplastic anemia.

Clinical Response to Vedolizumab in Ulcerative Colitis Patients Is Associated with Changes in Integrin Expression Profiles

Background

Despite large clinical success, deeper insights into the immunological effects of vedolizumab therapy for inflammatory bowel diseases are scarce. In particular, the reasons for differential clinical response in individual patients, the precise impact on the equilibrium of integrin-expressing T cell subsets, and possible associations between these issues are not clear.

Methods

Blood samples from patients receiving clinical vedolizumab therapy were sequentially collected and analyzed for expression of integrins and chemokine receptors on T cells. Moreover, clinical and laboratory data from the patients were collected, and changes between homing marker expression and clinical parameters were analyzed for possible correlations.

Results

While no significant correlation of changes in integrin expression and changes in outcome parameters were identified in Crohn’s disease (CD), increasing α4β7 levels in ulcerative colitis (UC) seemed to be associated with favorable clinical development, whereas increasing α4β1 and αEβ7 correlated with negative changes in outcome parameters. Changes in α4β1 integrin expression after 6 weeks were significantly different in responders and non-responders to vedolizumab therapy as assessed after 16 weeks with a cutoff of +4.2% yielding 100% sensitivity and 100% specificity in receiver-operator-characteristic analysis.

Discussion

Our data show that clinical response to vedolizumab therapy in UC but not in CD is associated with specific changes in integrin expression profiles opening novel avenues for mechanistic research and possibly prediction of response to therapy.

Chromatin Remodeling Protein SMAR1 Is a Critical Regulator of T Helper Cell Differentiation and Inflammatory Diseases

T cell differentiation from naïve T cells to specialized effector subsets of mature cells is determined by the iterative action of transcription factors. At each stage of specific T cell lineage differentiation, transcription factor interacts not only with nuclear proteins such as histone and histone modifiers but also with other factors that are bound to the chromatin and play a critical role in gene expression. In this review, we focus on one of such nuclear protein known as tumor suppressor and scaffold matrix attachment region-binding protein 1 (SMAR1) in CD4⁺ T cell differentiation. SMAR1 facilitates Th1 differentiation by negatively regulating T-bet expression via recruiting HDAC1–SMRT complex to its gene promoter. In contrast, regulatory T (T_reg) cell functions are dependent on inhibition of Th17-specific genes mainly IL-17 and STAT3 by SMAR1. Here, we discussed a critical role of chromatin remodeling protein SMAR1 in maintaining a fine-tuned balance between effector CD4⁺ T cells and T_reg cells by influencing the transcription factors during allergic and autoimmune inflammatory diseases.

Gut Inflammation in Mice Triggers Proliferation and Function of Mucosal Foxp3+ Regulatory T Cells but Impairs Their Conversion from CD4+ T Cells

BACKGROUND AND AIMS

Regulatory Foxp3⁺CD4⁺ T cells [Tregs] have been implicated in the control of colitis in T-cell transfer models, yet their ability to regulate colitis induced by innate immunity and the impact of gut inflammation on their fate and function have been poorly documented.

METHODS

Colitis was induced by dextran sodium sulphate in DEREG transgenic mice. Tregs ablation and transfer experiments showd that Tregs could limit the severity of colitis in B6 mice.

RESULTS

Gut inflammation resulted in increased number of Tregs in mesenteric lymph nodes [MLN] and colon lamina propria [LP], although their frequency decreased due to massive concomitant leukocyte infiltration. This coincided at both sites with a dramatic increase in Ki67⁺ Tregs which retained proliferative capacity. Gut inflammation resulted in enhanced suppressive function of Tregs in colon lamina propria and neuropillin-1^- [NRP1^-] Treg in MLN. Real-time polymerase chain reaction analysis and flow cytometry [using IL10-egfp-reporter mice] showed that compared with NRP1⁺ Treg, NRP1^- Treg express higher levels of IL-10 transcripts and were enriched in IL10-expressing cells both in the steady state and during colitis. Moreover, Treg conversion in vivo from from naïve CD4⁺ T cells or Treg precursors was impaired in colitic mice. Finally, gut inflammation caused a decrease in intestinal dendritic cells, affecting both CD103⁺CD11b⁺ and CD103⁺CD11b^- subsets and affected their Treg conversion capacity.

CONCLUSIONS

Together, our data indicate that non-specific colon inflammation triggers proliferation and suppressive function of Tregs in the lamina propria and MLN, but impairs their de novo conversion from CD4⁺ T cells by intestinal dendritic cells.

Molecular mechanism of action of anti-tumor necrosis factor antibodies in inflammatory bowel diseases

Anti-tumor necrosis factor (TNF) antibodies are successfully used in the therapy of inflammatory bowel diseases (IBD). However, the molecular mechanism of action of these agents is still a matter of debate. Apart from neutralization of TNF, influence on the intestinal barrier function, induction of apoptosis in mucosal immune cells, formation of regulatory macrophages as well as other immune modulating properties have been discussed as central features. Nevertheless, clinically effective anti-TNF antibodies were shown to differ in their mode-of-action in vivo and in vitro. Furthermore, the anti-TNF agent etanercept is effective in the treatment of rheumatoid arthritis but failed to induce clinical response in Crohn’s disease patients, suggesting different contributions of TNF in the pathogenesis of these inflammatory diseases. In the following, we will review different aspects regarding the mechanism of action of anti-TNF agents in general and analyze comparatively different effects of each anti-TNF agent such as TNF neutralization, modulation of the immune system, reverse signaling and induction of apoptosis. We discuss the relevance of the membrane-bound form of TNF compared to the soluble form for the immunopathogenesis of IBD. Furthermore, we review reports that could lead to personalized medicine approaches regarding treatment with anti-TNF antibodies in chronic intestinal inflammation, by predicting response to therapy.

Peripheral and Intestinal T-regulatory Cells are Upregulated in Children with Inflammatory Bowel Disease at Onset of Disease

BACKGROUND/AIMS

To determine the proportion of T-regulatory cells (CD4⁺CD25^highFOXP3⁺ cells) in peripheral blood and the number of FOXP3⁺ cells in intestinal mucosa of children with inflammatory bowel disease (IBD), and to verify whether these parameters correlate with the activity of the disease.

MATERIAL AND METHODS

24 patients newly diagnosed for IBD were included in the study: ulcerative colitis (UC; n = 13) and Crohn's disease (CD; n = 11). Seventeen healthy controls (HC) and 16 patients with irritable bowel syndrome (IBS) served as a control group for peripheral and intestinal Tregs assessment, respectively. The disease activity was assessed by Pediatric Ulcerative Colitis Activity Index (PUCAI) and Pediatric Crohn's Disease Activity Index (PCDAI). Quantification of regulatory T cells of CD4⁺CD25^highFOXP3⁺ phenotype in peripheral blood was based on three-color flow cytometry. Mucosal Tregs represented by FOXP3⁺ cells were evaluated using immunohistochemistry.

RESULTS

Median proportion of CD4⁺CD25^highFOXP3⁺ cells among CD4⁺ T cells in peripheral blood (5.1%, range 1.7-84% vs. 4.3%, range 2-8.1%, p = 0.023) and median number of intestinal FOXP3+ cells (115.33 per high-power field, hpf, range 39.33-375.67 vs. 10.16 per hpf, range 5-30, p = 0.0001) were significantly higher in children with IBD than in the controls. The proportion of circulating Tregs and the number of intestinal FOXP3+ cells did not correlate with clinical activity of the disease, as well as with endoscopic and histopathologic scoring. No significant correlation was found between the percentage of peripheral CD4+CD25^highFOXP3+ cells and the number of intestinal FOXP3+cells.

CONCLUSIONS

Children with IBD likely do not present with a quantitative deficiency of circulating and intestinal Tregs at the moment of diagnosis.

Differential effects of α4β7 and GPR15 on homing of effector and regulatory T cells from patients with UC to the inflamed gut in vivo

OBJECTIVE

Gut homing of lymphocytes via adhesion molecules has recently emerged as new target for therapy in IBDs. We aimed to analyse the in vivo homing of effector (Teff) and regulatory (Treg) T cells to the inflamed gut via α4β7 and G protein receptor GPR15.

DESIGN

We assessed the expression of homing receptors on T cells in peripheral blood and inflamed mucosa. We studied the migration pattern and homing of Teff and Treg cells to the inflamed gut using intravital confocal microscopy and FACS in a humanised mouse model in dextran sodium sulfate-treated NSG (NOD.Cg-Prkdcscid-Il2rgtm1Wjl/SzJ) mice.

RESULTS

Expression of GPR15 and α4β7 was significantly increased on Treg rather than Teff cells in peripheral blood of patients with UC as compared with Crohn's disease and controls. In vivo analysis in a humanised mouse model showed augmented gut homing of UC Treg cells as compared with controls. Moreover, suppression of UC (but not control) Teff and Treg cell homing was noted upon treatment with the α4β7 antibody vedolizumab. In contrast, siRNA blockade of GPR15 had only effects on homing of Teff cells but did not affect Treg homing in UC. Clinical vedolizumab treatment was associated with marked expansion of UC Treg cells in peripheral blood.

CONCLUSIONS

α4β7 rather than GPR15 is crucial for increased colonic homing of UC Treg cells in vivo, while both receptors control UC Teff cell homing. Vedolizumab treatment impairs homing of UC Treg cells leading to their accumulation in peripheral blood with subsequent suppression of systemic Teff cell expansion.

Ulcerative Colitis Is Characterized by a Decrease in Regulatory B Cells

BACKGROUND AND AIMS

Ulcerative colitis (UC) is characterized by Th2-polarized, B cell responses. However, neither size, composition, nor activity of the Breg compartment in active UC has been evaluated.

METHODS

Peripheral blood of 25 patients with UC, 5 patients with Crohn's disease (CD) and 15 control subjects was examined for Bregs subsets by flow cytometry. Intestinal tissue of 5 patients with UC, 3 patients with CD and 5 control subjects was also examined for Bregs. The levels of serum interleukin (IL)-10, immunoglobulin (Ig), and C-reactive protein (CRP), and the erythrocyte sedimentation rate (ESR) in individual subjects were measured. Interleukin-10 production in B cells isolated from patients with UC was examined. Potential associations between the values of the different measures were analysed by the Spearman correlation test.

RESULTS

Compared with controls, the UC patients had significantly reduced frequencies of CD24(high)CD38(high) and CD5(+) Bregs in peripheral blood as well as in intestinal tissues, accompanied by lower serum IL-10 levels. Interleukin-10 production was significantly decreased in stimulated B cells from patients with UC, whereas patient IL-10(+) B cells were found to be enriched in CD24(high)CD38(high) and CD5(+) B cells. However, increased percentages of CD95(+)-exhausted Bregs were encountered in subsets. Furthermore, Mayo clinic scores, CRP, and ESR in UC patients was negatively correlated with the frequency of Bregs and the IL-10 concentration, whereas these parameters were positively correlated with the frequency of CD95(+)-exhausted Bregs and the IgG levels.

CONCLUSIONS

Active UC is characterized by exhaustion of regulatory control in the B cell compartment.

Regional Specialisation of T Cell Subsets and Apoptosis in the Human Gut Mucosa: Differences Between Ileum and Colon in Healthy Intestine and Inflammatory Bowel Diseases

BACKGROUND AND AIMS

There is very limited information regarding region-specific immunological response in human intestine. We aimed to determine differences in immune compartmentalisation between ileum and colon in healthy and inflamed mucosa.

METHODS

T cell profile and its apoptosis were measured by flow cytometry, Th1, Th17, Treg [CD4(+)CD25(+)FOXP3(+)], double positive [DP, CD3(+)CD4(+)CD8(+)] and double negative T cells [DN, CD3(+)CD4(-)CD8(-)], immunohistochemistry [FOXP3, caspase-3], and real-time polymerase chain reaction [PCR] [IFN-γ, IL-17-A, and FOXP3] on biopsies from different regions of healthy intestine and of intestine in inflammatory bowel diseases.

RESULTS

Healthy colon showed higher percentages of Treg, Th17, and DN, and lower numbers of DP T cells compared with ileum [p < 0.05]. Some but not all region-specific differences were lost in inflammatory conditions. Disease-specific patterns were found: a Th1/Th17 pattern and a Th17 pattern in Crohn's disease and ulcerative colitis respectively, whereas a reduction in Th1/Th17 was found in microscopic colitis. In colonic Crohn's disease and microscopic colitis, DN T cells had a pattern inverse to that of Th1/Th17 (increase in microscopic colitis [p < 0.05] and decrease in Crohn's disease [p < 0.005]). Higher levels of lymphocyte apoptosis were found in healthy colon compared with the ileal counterparts [p = 0.001]. All forms of colonic inflammation presented a dramatic decrease in apoptosis compared with healthy colon. By contrast ileal Crohn's disease showed higher levels of cleaved-Caspase(+) CD3(+) cells.

CONCLUSIONS

Immunological differences exist in healthy gastrointestinal tract. Inflammatory processes overwhelm some location-specific differences, whereas others are maintained. Care has to be taken when analysing immune response in intestinal inflammation, as location-specific differences may be relevant.

Evaluation of immune infiltration in the colonic mucosa of patients with ipilimumab-related colitis

Approximately 30% of patients treated with ipilimumab will develop gastrointestinal toxicity. The immunological drivers that underpin the clinical observations in human tissues are poorly understood. We report here on the immune consequences of ipilimumab treatment in the colorectal mucosa of patients with treatment-related colitis. Using immunohistochemistry, we evaluated the immune infiltrate by CD8+, FoxP3, and granzyme B (GzmB) in colonic biopsies from 20 patients with ipilimumab-related colitis. We assessed 10 cases with normal colon biopsies for comparison. In eight cases (four on steroids only, four on steroids and infliximab), we evaluated two sequential biopsies. We observed that CD8+, FoxP3+, and GzmB T cell counts were significantly higher in patients with ipilimumab-related colitis compared to normal colon (p < 0.0001). Patients who required infliximab for the resolution of their colitis had a significantly higher CD8+/FoxP3 ratio than those treated only with steroids and this correlated with clinical severity. The analysis of repeat samples revealed that resolution of the colitis was associated with a decrease in CD8+ and FoxP3+ cells both in patients treated with steroids and infliximab. Our data suggest that counts of cytotoxic T cells and Tregs in the colonic mucosa from patients with ipilimumab-related colitis correlate with clinical findings and may predict severity and guide management.

Global mucosal and serum cytokine profile in patients with ulcerative colitis undergoing anti-TNF therapy

BACKGROUND AND OBJECTIVE

The knowledge of the effects of anti-tumour necrosis factor (TNF) treatment on the global cytokine profile in patients with ulcerative colitis (UC) is limited. A better understanding of these mechanisms could improve the ability to select patients that should undergo the therapy. Therefore, the aim was to determine the global mucosal and serum cytokine profile before and during induction therapy with anti-TNF in UC patients.

MATERIALS AND METHODS

In total, mucosal biopsies (n = 28) and serum samples (n = 42) were collected from UC patients (total n = 48) before anti-TNF therapy. At week 14 response to the therapy was evaluated and again mucosal biopsies (n = 14) and serum samples (n = 42) were collected. Quantitative real-time PCR was used to determine mucosal cytokine mRNA expression and the MSD MULTI-ARRAY assay system platform was used for analysis of cytokines in serum. The global cytokine profile was evaluated by multivariate factor analysis.

RESULTS

At baseline, the global profile of mucosal cytokine mRNA expression and serum cytokines discriminated therapy responders from non-responders. Responders had lower mucosal mRNA expression of interleukin 1β (IL-1β), IL-17A, IL-6 and interferon γ (IFN-γ) than non-responders. Fourteen weeks after therapy start mucosal IL-1β and IL-6 were down-regulated in therapy responders but not in non-responders. At week 14, serum levels of IL-6 were decreased in therapy responders whereas IFN-γ and IL-12p70 were increased in non-responders.

CONCLUSIONS

Our data suggest that patients with a therapy failure have a more severe pro-inflammatory cytokine profile before start of anti-TNF treatment, which is less well suppressed by the treatment as compared to therapy responders.

Role of regulatory T cell in the pathogenesis of inflammatory bowel disease

Regulatory T (Treg) cells play key roles in various immune responses. For example, Treg cells contribute to the complex pathogenesis of inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis during onset or development of that disease. Many animal models of IBD have been used to investigate factors such as pathogenic cytokines, pathogenic bacteria, and T-cell functions, including those of Treg cells. In addition, analyses of patients with IBD facilitate our understanding of the precise mechanism of IBD. This review article focuses on the role of Treg cells and outlines the pathogenesis and therapeutic strategies of IBD based on previous reports.

Disrupted regulatory T cell homeostasis in inflammatory bowel diseases

In the gut, where billions of non-self-antigens from the food and the microbiota are present, the immune response must be tightly regulated to ensure both host protection against pathogenic microorganisms and the absence of immune-related pathologies. It has been well documented that regulatory T cells (Tregs) play a pivotal role in this context. Indeed, Tregs are able to prevent excessive inflammation, which can lead to the rupture of intestinal homeostasis observed in inflammatory bowel diseases (IBDs). Both the worldwide incidence and prevalence of such diseases have increased throughout the latter part of the 20^th century. Therefore, it is crucial to understand how Tregs suppress the colitogenic immune cells to establish new treatments for patients suffering from IBDs. In this review, we will first summarize the results obtained in animal model studies that highlight the importance of Tregs in maintaining intestinal homeostasis and describe the specific suppressive mechanisms involved. Next, our current knowledge about Tregs contribution to human IBDs will be reviewed, as well as the current therapeutic perspective on using Tregs for clinical IBD treatment and the challenges that remain to be resolved to ensure both the safety and effectiveness of these therapies in targeting this critical immune-regulatory cell population.

New Insights into the Mechanisms of Action of Anti-Tumor Necrosis Factor-α Monoclonal Antibodies in Inflammatory Bowel Disease

Tumor necrosis factor alpha (TNF-α) has been widely accepted as a therapeutic target for inflammatory disorders including inflammatory bowel disease. Anti-TNF-α monoclonal antibodies (mAbs) including infliximab, adalimumab, golimumab, and certolizumab pegol have revolutionized therapy for these chronic inflammatory disorders. These agents are potent inhibitors of TNF-α, but significant evidence points to the fact that their actions extend beyond simple neutralization of the cytokine. Recent advances in understanding the mechanism of action of anti-TNF-α mAbs has discovered a number of previously unrecognized actions that are likely to be relevant in mediating their anti-inflammatory effects. Many of those actions are mediated by the binding of the antibodies to transmembrane TNF-α (tmTNF-α) and involve complex interactions with other molecular factors and cells. In this review, we have highlighted new information on the mechanism of actions of anti-TNF-α mAbs, from in vitro and in vivo studies. Despite obvious benefits in many patients, the clinical use of these antibodies are hampered by the fact that some patients do not respond to them, and among patients who do respond, many will develop recurrent disease despite continued dosing. Although pharmacokinetic factors explain some of the observed cases of partial or complete resistance to the effects of anti-TNF-α mAbs, other nonresponder patients may be resistant to those agents mechanism of action. A more thorough understanding of the mechanism of action of anti-TNF-α mAbs may allow the development of strategies to individualize therapy and to overcome resistance.

Anti-Tumor Necrosis Factor Therapy Restores Peripheral Blood B-cell Subsets and CD40 Expression in Inflammatory Bowel Diseases

BACKGROUND

Anti-tumor necrosis factor (TNF) therapy has become a standard therapy for severe inflammatory bowel diseases (IBD), but its effect on B lymphocytes is largely unexplored. In this study we investigated peripheral blood B cells, B-cell subsets, and CD40 expression in patients with IBD before and during anti-TNF therapy with infliximab (IFX).

METHODS

Blood was taken from healthy controls (n = 52) and patients with active IBD before (n = 46) and/or during anti-TNF therapy (n = 55). B-cell markers were detected by immunofluorescent staining and FACS analysis. Patients were classified as responders or nonresponders to anti-TNF therapy.

RESULTS

We found a numerical deficiency of circulating CD19 B cells, a lower activation state (CD40 expression) and lower proportions of CD5 B cells and IgMIgDCD27 preswitched memory cells among B cells in active patients with IBD before IFX therapy compared with healthy controls. IFX treatment increased CD19 B-cell numbers as well as the proportions of named B-cell subsets in responders but not in nonresponders. IFX more effectively upregulated CD40 expression in responders than in nonresponders. Restoration of B cells correlated with the biological response to therapy (C-reactive protein). Trough serum levels of IFX correlated with the number of B cells during therapy.

CONCLUSIONS

A lower number of circulating B cells, a low CD40 expression, and a decrease in the proportion of CD5 and in the preswitched memory subset characterize active IBD. Restoration of these abnormalities correlates with the clinical response to anti-TNF therapy. The mechanism for this effect on B cells should be further explored.

Promises and paradoxes of regulatory T cells in inflammatory bowel disease

Since their discovery two decades ago, CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) have become the subject of intense investigation by immunologists. Unlike other T cells, which promote an immune response, Tregs actively inhibit inflammation when activated by their cognate antigen, thus raising hope that these cells could be engineered into a highly targeted, antigen-specific, immunosuppressant therapy. Although Tregs represent less than 10% of circulating CD4(+)T cells, they have been shown to play an essential role in preventing or limiting inflammation in a variety of animal models and human diseases. In particular, spontaneous intestinal inflammation has been shown to occur in the absence of Tregs, suggesting that there may be a Treg defect central to the pathogenesis of human inflammatory bowel disease (IBD). However, over the past decade, multiple groups have reported no qualitative or quantitative deficits in Tregs from the intestines and blood of IBD patients to explain why these cells fail to regulate inflammation in Crohn's disease and ulcerative colitis. In this review, we will discuss the history of Tregs, what is known about them in IBD, and what progress and obstacles have been seen with efforts to employ them for therapeutic benefit.