FOXP3⁺ T regulatory cell modifications in inflammatory bowel disease patients treated with anti-TNFα agents

Circulating and intestinal regulatory T cells in inflammatory bowel disease: A systemic review and meta-analysis

Regulatory T cells (Tregs) play an important immunosuppressive role in inflammatory bowel disease (IBD). However, findings on the quantitative and functional changes of intestinal and circulating Tregs in patients with IBD are rather contradictory. We therefore conducted a meta-analysis on this issue. The pooled effect was assessed using the standardized mean difference (SMD) with a 95% confidence interval (CI), and subgroup analyses were performed to investigate heterogeneity. This analysis included 764 IBD (402 UC and 362 CD) patients and 341 healthy controls (HCs) pooled from 17 eligible studies. The percentage of circulating Tregs was significantly decreased in active IBD patients compared to HCs (SMD = -0.95, p < 0.001) and inactive IBD patients (SMD = -0.80, p < 0.001). There was no difference in the percentage of circulating Tregs between inactive IBD patients and HCs. The suppressive function of circulating Tregs was impaired in active IBD patients according to limited data (SMD = -0.75, p = 0.02). Besides, the percentage of intestinal Tregs was significantly higher in inflamed regions than in non-inflamed regions (SMD = 0.85, p < 0.001). Our study quantitatively summarized the quantitative and functional changes of Tregs and supported the therapeutic potential of Tregs in IBD. Moreover, additional research into the functions and characteristics of intestinal Tregs in IBD is needed.

Blood regulatory T cells in inflammatory bowel disease, a systematic review, and meta-analysis

INTRODUCTION

Inflammatory bowel disease (IBD) is an autoimmune disease involving various parts of the gastrointestinal (GI) tract, which includes Crohn's disease (CD) and ulcerative colitis (UC). Due to the contradictory results regarding the percentage of peripheral blood (PB) regulatory T cells (Tregs) in IBD patients, this meta-analysis aimed to determine the Tregs frequency in IBD patients.

METHOD

We searched PubMed, Web of Science, SCOPUS, and Google Scholar databases for relevant observational articles that analyzed and reported the frequency of PB Tregs in IBD patients and healthy control groups. After choosing the related articles by two reviewers, the data regarding the definition of Tregs and their frequencies in different groups were recorded.

RESULT

In 22 studies, the results showed a nonsignificant difference in the frequency of PB Tregs between IBD cases and control subjects (SMD: -0.27, 95 % CI: -0.78, 0.23). However, the frequency of CD4⁺CD25⁺CD127^- (SMD: -0.89, 95 % CI: -1.52, -0.26) and CD4⁺CD25⁺FoxP3⁺ (SMD: -1.32, 95 % CI: -2.37, -0.26) Tregs were significantly lower in IBD cases, compared to healthy subjects. Also, UC cases and active IBD cases showed a significantly lower frequency of Treg cells, compared to controls and remission IBD cases, respectively (SMD: -0.68, 95 % CI: -1.24, -0.11 and SMD: -0.60, 95 % CI: -0.93, -0.27).

CONCLUSION

Our study highlighted a probable decrease of Tregs in IBD patients, especially the patients with active states of the disease. The decrease of Treg cells might cause an imbalance in the immune system and the over-activation of auto-immune responses against the digestive tract.

Biologic Agents in Crohn's Patients Reduce CD4+ T Cells Activation and Are Inversely Related to Treg Cells

Crohn's disease (CD) is a chronic inflammatory disease with a complex interface of broad factors. There are two main treatments for Chron's disease: biological therapy and nonbiological therapy. Biological agent therapy (e.g., anti-TNF) is the most frequently prescribed treatment; however, it is not universally accessible. In fact, in Brazil, many patients are only given the option of receiving nonbiological therapy. This approach prolongs the subsequent clinical relapse; however, this procedure could be implicated in the immune response and enhance disease severity. Our purpose was to assess the effects of different treatments on CD4⁺ T cells in a cohort of patients with Crohn's disease compared with healthy individuals. To examine the immune status in a Brazilian cohort, we analyzed CD4⁺ T cells, activation status, cytokine production, and Treg cells in blood of Crohn's patients. Patients that underwent biological therapy can recover the percentage of CD4⁺CD73⁺ T cells, decrease the CD4⁺ T cell activation/effector functions, and maintain the peripheral percentage of regulatory T cells. These results show that anti-TNF agents can improve CD4⁺ T cell subsets, thereby inducing Crohn's patients to relapse and remission rates.

Bacterial Translocation as Inflammatory Driver in Crohn's Disease

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract responsible for intestinal lesions. The multifactorial etiology attributed to CD includes a combination of environmental and host susceptibility factors, which result in an impaired host–microbe gut interaction. Bacterial overgrowth and dysbiosis, increased intestinal barrier permeability, and altered inflammatory responses in patients with CD have been described in the past. Those events explain the pathogenesis of luminal translocation of bacteria or its products into the blood, a frequent event in CD, which, in turn, favors a sustained inflammatory response in these patients. In this review, we navigate through the interaction between bacterial antigen translocation, permeability of the intestinal barrier, immunologic response of the host, and genetic predisposition as a combined effect on the inflammatory response observed in CD. Several lines of evidence support that translocation of bacterial products leads to uncontrolled inflammation in CD patients, and as a matter of fact, the presence of gut bacterial genomic fragments at a systemic level constitutes a marker for increased risk of relapse among CD patients. Also, the significant percentage of CD patients who lose response to biologic therapies may be influenced by the translocation of bacterial products, which are well-known drivers of proinflammatory cytokine production by host immune cells. Further mechanistic studies evaluating cellular and humoral immune responses, gut microbiota alterations, and genetic predisposition will help clinicians to better control and personalize the management of CD patients in the future.

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.

Decipher manifestations and Treg /Th17 imbalance in multi-staging rheumatoid arthritis and correlation with TSDR/RORC methylation

T regulatory (Treg)/T-helper (Th) 17 imbalance has been shown to integrate with epigenetics to result in the development of autoimmune diseases. We aim to investigate the influence of disease staging on Treg/Th17 cells and whether the aberrant DNA methylation is implicated in the development of rheumatoid arthritis (RA). By recruiting 65 patients with multi-staging RA and 20 healthy controls (HC), we found that patients with active RA exhibited relative lymphopenia and higher WBC, neutrophils, and PLT. Circulating Treg/Th17 in patients with early active RA was significantly decreased. The expression of IL-6 and IL-17A was significantly increased in early active RA, whereas that of IL-10 and TGF-β was on the contrary. Furthermore, the frequency of Treg cells and Treg/Th17 were negatively correlated with DAS28, and the frequency of Th17 cells was on the contrary. Levels of DNA methylation related enzymes had significant difference between early active RA and HC. Relative hypermethylation was observed at the gene level for Treg-specific demethylated region (TSDR) and hypomethylation for retinoic acid-related orphan receptor (ROR)-C in early active RA. Thus, manifestations of RA and Treg/Th17 imbalance vary with disease staging, and the aberrant DNA methylation pattern may contribute to RA disease pathogenesis. Our results highlight the importance of disease staging in clinical research.

Medical Treatment Can Unintentionally Alter the Regulatory T-Cell Compartment in Patients with Widespread Pathophysiologic Conditions

Regulatory T cells (Tregs) are non-redundant mediators of immune tolerance that are critical to prevent autoimmune disease and promote an anti-inflammatory tissue environment. Many individuals experience chronic diseases and physiologic changes associated with aging requiring long-term medication. Unfortunately, adverse effects accompany every pharmacologic intervention and may affect overall outcomes. We focus on medications typically prescribed during the treatment of prevalent chronic diseases and disorders, including cardiovascular disease, autoimmune disease, and menopausal symptoms, that affect >200 million individuals in the United States. Increasing studies continue to report that treatment of patients with estrogen, metformin, statins, vitamin D, and tumor necrosis factor blockers are unintentionally modulating the Treg compartment. Effects of these medications likely comprise direct and/or indirect interaction with Tregs via other immune and parenchymal populations. Differing and sometimes opposing effects on the Treg compartment have been observed using the same medication. The length of treatment, dosing regimen and stage of disease, patient age, ethnicity, and sex may account for such findings and determine the specific signaling pathways affected by the medication. Enhancing the Treg compartment can skew the patient's immune system toward an anti-inflammatory phenotype and therefore could provide unanticipated benefit. Currently, multiple medicines prescribed to large numbers of patients influence the Treg compartment; however, how such effects affect their disease outcome and long-term health remains unclear.

Histone deacetylases as targets in autoimmune and autoinflammatory diseases

Reversible lysine acetylation of histones is a key epigenetic regulatory process controlling gene expression. Reversible histone acetylation is mediated by two opposing enzyme families: histone acetyltransferases (HATs) and histone deacetylases (HDACs). Moreover, many non-histone targets of HATs and HDACs are known, suggesting a crucial role for lysine acetylation as a posttranslational modification on the cellular proteome and protein function far beyond chromatin-mediated gene regulation. The HDAC family consists of 18 members and pan-HDAC inhibitors (HDACi) are clinically used for the treatment of certain types of cancer. HDACi or individual HDAC member-deficient (cell lineage-specific) mice have also been tested in a large number of preclinical mouse models for several autoimmune and autoinflammatory diseases and in most cases HDACi treatment results in an attenuation of clinical disease severity. A reduction of disease severity has also been observed in mice lacking certain HDAC members. This indicates a high therapeutic potential of isoform-selective HDACi for immune-mediated diseases. Isoform-selective HDACi and thus targeted inactivation of HDAC isoforms might also overcome the adverse effects of current clinically approved pan-HDACi. This review provides a brief overview about the fundamental function of HDACs as epigenetic regulators, highlights the roles of HDACs beyond chromatin-mediated control of gene expression and summarizes the studies showing the impact of HDAC inhibitors and genetic deficiencies of HDAC members for the outcome of autoimmune and autoinflammatory diseases with a focus on rheumatoid arthritis, inflammatory bowel disease and experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis.

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.

Solid-phase extraction of exosomes from diverse matrices via a polyester capillary-channeled polymer (C-CP) fiber stationary phase in a spin-down tip format

Exosomes, a subset of the extracellular vesicle (EV) group of organelles, hold great potential for biomarker detection, therapeutics, disease diagnosis, and personalized medicine applications. The promise and potential of these applications are hindered by the lack of an efficient means of isolation, characterization, and quantitation. Current methods for exosome and EV isolation (including ultracentrifugation, microfiltration, and affinity-based techniques) result in impure recoveries with regard to remnant matrix species (e.g., proteins, genetic material) and are performed on clinically irrelevant time and volume scales. To address these issues, a polyethylene terephthalate (PET) capillary-channeled polymer (C-CP) fiber stationary phase is employed for the solid-phase extraction (SPE) of EVs from various matrices using a micropipette tip-based format. The hydrophobic interaction chromatography (HIC) processing and a spin-down workflow are carried out using a table-top centrifuge. Capture and subsequent elution of intact, biologically active exosomes are verified via electron microscopy and bioassays. The performance of this method was evaluated by capture and elution of exosome standards from buffer solution and three biologically relevant matrices: mock urine, reconstituted non-fat milk, and exosome-depleted fetal bovine serum (FBS). Recoveries were evaluated using UV-Vis absorbance spectrophotometry and ELISA assay. The dynamic binding capacity (50%) for the 1-cm-long (~ 5 μL bed volume) tips was determined using a commercial exosome product, yielding a value of ~ 7 × 10¹¹ particles. The novel C-CP fiber spin-down tip approach holds promise for the isolation of exosomes and other EVs from various matrices with high throughput, low cost, and high efficiency. Graphical abstract.

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.

CD4+CD25+CD127low FoxP3+ regulatory T cells in Crohn's disease

BACKGROUND

Regulatory T (Treg) cell plays a key role in autoimmune diseases. We evaluated the regulatory function and frequency of Treg cells and secreted IL-10, IL-35 concentration in Crohn's disease (CD).

METHODS

Twenty-three patients with CD and 25 healthy controls (HC) were included in this study. We analysed the alteration of Tregs frequency using flow cytometry for CD4, CD25, CD127 and FoxP3 markers. Surface expression of CD4, CD25 and CD127 markers were used for isolation of relatively pure Treg cells. Suppressive activity of Tregs was determined by measuring their ability to inhibit the proliferation of T responder (Tres) cells. In addition, the amounts of IL-10 and IL-35 cytokines in co-culture supernatants were measured by ELISA assay after stimulation with anti-CD2/CD3/CD28.

RESULTS

CD patients had significantly lower frequency of CD4+ CD25+ CD127low FoxP3+ Treg cells in comparison with controls (2.17 ± 1.04 vs. 2.83 ± 1.07, p = 0.0352). Additionally, Treg cells mediated suppression was not significantly different in CD patients compared to controls. There was a significant difference in IL-10 secretion in response to anti-CD2/CD3/CD28 stimulation compared with HC (p = 0.0074).

CONCLUSION

The frequency of CD4+ CD25+ CD127low FoxP3+ Tregs decreased in active stage of CD but there was no impaired suppressive function of CD4+ CD25+ CD127low FoxP3+ Treg cells. We suggest that an alteration in the balance of Tregs and T effectors may contribute to pathogenesis of CD.

Frequencies of circulating regulatory TIGIT+CD38+ effector T cells correlate with the course of inflammatory bowel disease

Disease heterogeneity hampers achieving long-term disease remission in inflammatory bowel disease (IBD). Monitoring ongoing tissue-localized regulatory and inflammatory T-cell responses in peripheral blood would empower disease classification. We determined whether regulatory and inflammatory phenotypes of circulating CD38⁺ effector (CD62L^negCD4⁺) T cells, a population enriched for cells with mucosal antigen specificity, classify disease course in pediatric IBD patients. In healthy individuals, circulating CD38⁺ effector T cells had a predominant regulatory component with lower frequencies of IFNγ-secreting T cells, higher frequencies of IL-10-secreting T cells and higher frequencies of inhibitory molecule T-cell immunoglobulin and ITIM domain⁺ (TIGIT) cells than CD38^neg effector T cells. TIGIT expression was stable upon stimulation and marked CD38⁺ T cells with inhibitory properties. In IBD patients with active intestinal inflammation this predominant regulatory component was lost: circulating CD38⁺ effector T cells had increased activated CD25⁺CD45RA^neg and decreased TIGIT⁺ cell frequencies. TIGIT percentages below 25% before treatment associated with shorter duration of clinical remission. In conclusion, phenotypic changes in circulating CD38⁺ effector T cells, in particular the frequency of TIGIT⁺ cells, classify pediatric IBD patients and predict severity of disease course. These findings have relevance for IBD and can be exploited in graft-versus-host-disease and checkpoint inhibitor-induced inflammation in cancer.

Mucosal Immunity Related to FOXP3+ Regulatory T Cells, Th17 Cells and Cytokines in Pediatric Inflammatory Bowel Disease

BACKGROUND

We aimed to investigate mucosal immunity related to forkhead box P3 (FOXP3+) regulatory T (Treg) cells, T helper 17 (Th17) cells and cytokines in pediatric inflammatory bowel disease (IBD).

METHODS

Mucosal tissues from terminal ileum and colon and serum samples were collected from twelve children with IBD and seven control children. Immunohistochemical staining was done using anti-human FOXP3 and anti-RORγt antibodies. Serum levels of cytokines were analyzed using a multiplex assay covering interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-17A/F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, interferon (IFN)-γ, soluble CD40L, and tumor necrosis factor-α.

RESULTS

FOXP3+ Treg cells in the lamina propria (LP) of terminal ileum of patients with Crohn's disease were significantly (P < 0.05) higher than those in the healthy controls. RORγt+ T cells of terminal ileum tended to be higher in Crohn's disease than those in the control. In the multiplex assay, serum concentrations (pg/mL) of IL-4 (9.6 ± 1.5 vs. 12.7 ± 3.0), IL-21 (14.9 ± 1.5 vs. 26.4 ± 9.1), IL-33 (14.3 ± 0.9 vs. 19.1 ± 5.3), and IFN-γ (15.2 ± 5.9 vs. 50.2 ± 42.4) were significantly lower in Crohn's disease than those in the control group. However, serum concentration of IL-6 (119.1 ± 79.6 vs. 52.9 ± 39.1) was higher in Crohn's disease than that in the control. Serum concentrations of IL-17A (64.2 ± 17.2 vs. 28.3 ± 10.0) and IL-22 (37.5 ± 8.8 vs. 27.2 ± 3.7) were significantly higher in ulcerative colitis than those in Crohn's disease.

CONCLUSION

Mucosal immunity analysis showed increased FOXP3+ T reg cells in the LP with Crohn's disease while Th17 cell polarizing and signature cytokines were decreased in the serum samples of Crohn's disease but increased in ulcerative colitis.

The Innate and Adaptive Immune System as Targets for Biologic Therapies in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an immune-mediated inflammatory condition causing inflammation of gastrointestinal and systemic cells, with an increasing prevalence worldwide. Many factors are known to trigger and maintain inflammation in IBD including the innate and adaptive immune systems, genetics, the gastrointestinal microbiome and several environmental factors. Our knowledge of the involvement of the immune system in the pathophysiology of IBD has advanced rapidly over the last two decades, leading to the development of several immune-targeted treatments with a biological source, known as biologic agents. The initial focus of these agents was directed against the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) leading to dramatic changes in the disease course for a proportion of patients with IBD. However, more recently, it has been shown that a significant proportion of patients do not respond to anti-TNF-α directed therapies, leading a shift to other inflammatory pathways and targets, including those of both the innate and adaptive immune systems, and targets linking both systems including anti-leukocyte trafficking agents-integrins and adhesion molecules. This review briefly describes the molecular basis of immune based gastrointestinal inflammation in IBD, and then describes how several current and future biologic agents work to manipulate these pathways, and their clinical success to date.

Mechanisms behind efficacy of tumor necrosis factor inhibitors in inflammatory bowel diseases

Biological treatment with tumor necrosis factor (TNF) inhibitors is successful in the management of inflammatory bowel disease (IBD). All TNF inhibitors antagonize the pro-inflammatory cytokine TNF-α but with varying efficacies in IBD. The variations in efficacy probably are caused by structural differences between the agents that affect their mechanisms of action and pharmacokinetic properties. Several mechanisms have been proposed, such as modulation of the expression of pro-inflammatory mediators and a reduction in the number of activated immune cells. However, it seems that clinical efficacy is the result of a number of different mechanisms and that binding of transmembrane TNF by TNF inhibitors. Knowledge of the mechanisms of action has been obtained mainly through the use of in vitro assays that may differ significantly from the situation in vivo. This review discusses the available data on TNF inhibitors in order to identify mechanisms of importance for their efficacy in IBD. Thus, a better understanding of the mechanistic basis for clinical efficacy can lead to a more rational use of TNF inhibitors in the management of IBD.

Decrease of CD4(+) CD25(+) CD127(low) FoxP3(+) regulatory T cells with impaired suppressive function in untreated ulcerative colitis patients

Regulatory T (Treg) cells take part in immune homeostasis and play a pivotal role in maintaining peripheral tolerance. The aim of this study was to evaluate the frequency and function of Treg cells in active and untreated ulcerative colitis (UC) patients. Thirty-two subjects with newly diagnosed UC and 31 age-matched healthy controls were included in this survey. The frequency of Tregs was analyzed with flow cytometry using CD4, CD25, CD127 and FoxP3 markers. We used surface expression of CD4(+), CD25(+) and CD127(low) markers for isolation of a relatively pure Treg population. Suppressive activity of Tregs was determined by measuring their ability to inhibit the proliferation of T responder cells. UC patients had a lower frequency of CD4(+) CD25(+) CD127(low) FoxP3(+) Treg cells. Additionally, Treg cell-mediated suppression was lower in UC patients compared to controls. The frequency and suppressive capacity of Tregs and MFI of FoxP3 were inversely correlated with disease activity. These results suggest that CD4(+) CD25(+) CD127(low) FoxP3(+) Treg cells may contribute to immunopathogenesis of UC, and assessment of Treg cell frequency and function may have clinical value.

TNF-α: a treatment target or cause of sarcoidosis?

Sarcoidosis is a systemic granulomatous disease that affects numerous organs, commonly manifesting at the lungs and skin. While corticosteroids remain the first line of treatment, tumour necrosis factor alpha (TNF-α) inhibitors have been investigated as one potential steroid sparing treatment for sarcoidosis. TNF-α is one of many components involved in the formation of granulomas in sarcoidosis. While there have been larger scale studies of biologic TNF-α inhibition in systemic sarcoidosis, studies in cutaneous disease are limited. Paradoxically, in some patients treated with biologic TNF-α inhibitors for other diseases, treatment can induce the development of sarcoidosis. In the light of this complexity, we discuss the role of TNF-α in granuloma formation, the therapeutic role of TNF-α inhibition and immunologic abnormalities following treatment with these TNF-α inhibitors including drug-specific alterations involving interferon-γ, lymphotoxin-α, TNF receptor 2 (TNFR2) and T-regulatory cells.

The involvement of gut microbiota in inflammatory bowel disease pathogenesis: potential for therapy

Over the past recent years, a great number of studies have been directed toward the evaluation of the human host-gut microbiota interaction, with the goal to progress the understanding of the etiology of several complex diseases. Alterations in the intestinal microbiota associated with inflammatory bowel disease are well supported by literature data and have been widely accepted by the research community. The concomitant implementation of high-throughput sequencing techniques to analyze and characterize the composition of the intestinal microbiota has reinforced the view that inflammatory bowel disease results from altered interactions between gut microbes and the mucosal immune system and has raised the possibility that some form of modulation of the intestinal microbiota may constitute a potential therapeutic basis for the disease. The aim of this review is to describe the changes of gut microbiota in inflammatory bowel disease, focusing the attention on its involvement in the pathogenesis of the disease, and to review and discuss the therapeutic potential to modify the intestinal microbial population with antibiotics, probiotics, prebiotics, synbiotics and fecal microbiota transplantation.

Review article: selective histone deacetylase isoforms as potential therapeutic targets in inflammatory bowel diseases

BACKGROUND

A link between histone deacetylases (HDACs) and intestinal inflammation has been established. HDAC inhibitors that target gut-selective inflammatory pathways represent a potential new therapeutic strategy in patients with refractory inflammatory bowel diseases (IBD).

AIMS

To review the use of selective HDAC inhibitors to treat gut inflammation and to highlight potential improvements in selectivity/sensitivity by additional targeting of HDAC-regulating microRNAs (miRNAs).

METHODS

Original articles and reviews have been identified using PubMed search terms: 'histone deacetylase', 'HDAC inhibitor', 'inflammatory bowel disease', 'gut inflammation,' and 'microRNA and HDAC'.

RESULTS

The use of butyrate in distal colitis provided the first evidence that inhibition of HDACs decreases intestinal inflammation in IBD. HDAC inhibitors, such as valproic acid, vorinostat and givinostat, reduce inflammation and tissue damage in experimental murine colitis. Potential mechanisms of action for HDAC inhibitors include increased apoptosis, reduction of pro-inflammatory cytokine release, regulation of transcription factors and modulation of HDAC-regulatory miRNAs. HDAC2, HDAC3, HDAC6, HDAC9 and HDAC10 isoforms seem to be specifically involved in chronic intestinal inflammation, justifying the use of selective inhibitors as new therapeutic strategies in IBD. Controlling miRNAs for these isoforms can be identified.

CONCLUSIONS

The pro-inflammatory influence of HDACs in the gut has been confirmed, but mostly in murine studies. Considerably more human data are required to permit development of selective HDAC inhibitors for IBD treatment. Inhibition of key HDAC isoforms in combination with modulation of HDAC-regulatory miRNAs has potential as a novel therapeutic approach.

Control of tissue-localized immune responses by human regulatory T cells

Treg cells control immune responses to self and nonharmful foreign antigens. Emerging data from animal models indicate that Treg cells function in both secondary lymphoid organs and tissues, and that these different microenvironments may contain specialized subsets of Treg cells with distinct mechanisms of action. The design of therapies for the restoration of tissue-localized immune homeostasis is dependent upon understanding how local immune responses are influenced by Treg cells in health versus disease. Here we review the current state of knowledge about human Treg cells in four locations: the skin, lung, intestine, and joint. Despite the distinct biology of these tissues, there are commonalities in the biology of their resident Treg cells, including phenotypic and functional differences from circulating Treg cells, and the presence of cytokine-producing (e.g. IL-17(+)) FOXP3(+) cells. We also highlight the challenges to studying tissue Treg cells in humans, and opportunities to use new technologies for the detailed analysis of Treg cells at the single-cell level. As emerging biological therapies are increasingly targeted toward tissue-specific effects, it is critical to understand their potential impact on local immune regulation.

Regulatory T-cells in autoimmune diseases: challenges, controversies and--yet--unanswered questions

Regulatory T cells (Tregs) are central to the maintenance of self-tolerance and tissue homeostasis. Markers commonly used to define human Tregs in the research setting include high expression of CD25, FOXP3 positivity and low expression/negativity for CD127. Many other markers have been proposed, but none unequivocally identifies bona fide Tregs. Tregs are equipped with an array of mechanisms of suppression, including the modulation of antigen presenting cell maturation and function, the killing of target cells, the disruption of metabolic pathways and the production of anti-inflammatory cytokines. Treg impairment has been reported in a number of human autoimmune conditions and includes Treg numerical and functional defects and conversion into effector cells in response to inflammation. In addition to intrinsic Treg impairment, resistance of effector T cells to Treg control has been described. Discrepancies in the literature are common, reflecting differences in the choice of study participants and the technical challenges associated with investigating this cell population. Studies differ in terms of the methodology used to define and isolate putative regulatory cells and to assess their suppressive function. In this review we outline studies describing Treg frequency and suppressive function in systemic and organ specific autoimmune diseases, with a specific focus on the challenges faced when investigating Tregs in these conditions.

GITR+ regulatory T cells in the treatment of autoimmune diseases

Autoimmune diseases decrease life expectancy and quality of life for millions of women and men. Although treatments can slow disease progression and improve quality of life, all currently available drugs have adverse effects and none of them are curative; therefore, requiring patients to take immunosuppressive drugs for the remainder of their lives. A curative therapy that is safe and effective is urgently needed. We believe that therapies promoting the in vivo expansion of regulatory T cells (Tregs) or injection of in vitro expanded autologous/heterologous Tregs (cellular therapy) can alter the natural history of autoimmune diseases. In this review, we present data from murine and human studies suggesting that 1) glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) plays a crucial role in thymic Treg (tTreg) differentiation and expansion; 2) GITR plays a crucial role in peripheral Treg (pTreg) expansion; 3) in patients with Sjögren syndrome and systemic lupus erythematosus, CD4(+)GITR(+) pTregs are expanded in patients with milder forms of the disease; and 4) GITR is superior to other cell surface markers to differentiate Tregs from other CD4(+) T cells. In this context, we consider two potential new approaches for treating autoimmune diseases consisting of the in vivo expansion of GITR(+) Tregs by GITR-triggering drugs and in vitro expansion of autologous or heterologous GITR(+) Tregs to be infused in patients. Advantages of such an approach, technical problems, and safety issues are discussed.