Induced and natural regulatory T cells in the development of inflammatory bowel disease

Increased Interleukin-10 Expression by the Inhibition of Ca2+-Activated K+ Channel KCa3.1 in CD4+CD25+ Regulatory T Cells in the Recovery Phase in an Inflammatory Bowel Disease Mouse Model

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases of the gastrointestinal tract arising from abnormal responses of the innate and adaptative immune systems. Interleukin (IL)-10-producing CD4+CD25+ regulatory T (Treg) cells play a protective role in the recovery phase of IBD. In the present study, the effects of the administration of the selective Ca2+-activated K+ channel KCa3.1 inhibitor TRAM-34 on disease activities were examined in chemically induced IBD model mice. IBD disease severity, as assessed by diarrhea, visible fecal blood, inflammation, and crypt damage in the colon, was significantly lower in mice administered 1 mg/kg TRAM-34 than in vehicle-administered mice. Quantitative real-time polymerase chain reaction examinations showed that IL-10 expression levels in the recovery phase were markedly increased by the inhibition of KCa3.1 in mesenteric lymph node (mLN) Treg cells of IBD model mice compared with vehicle-administered mice. Among several positive and negative transcriptional regulators (TRs) for IL-10, three positive TRs-E4BP4, KLF4, and Blimp1-were upregulated by the inhibition of KCa3.1 in the mLN Treg cells of IBD model mice. In mouse peripheral CD4+CD25+ Treg cells induced by lectin stimulation, IL-10 expression and secretion were enhanced by the treatment with TRAM-34, together with the upregulation of E4BP4, KLF4, and Blimp1. Collectively, the present results demonstrated that the pharmacological inhibition of KCa3.1 decreased IBD symptoms in the IBD model by increasing IL-10 production in peripheral Treg cells and that IL-10high Treg cells produced by the treatment with KCa3.1 inhibitor may contribute to efficient Treg therapy for chronic inflammatory disorders, including IBD. SIGNIFICANCE STATEMENT: Pharmacological inhibition of Ca2+-activated K+ channel KCa3.1 increased IL-10 expression in peripheral Treg cells, together with the upregulation of the transcriptional regulators of IL-10: Krüppel-like factor 4, E4 promoter-binding protein 4, and/or B lymphocyte-induced maturation protein 1. The manipulation of IL-10high-producing Treg cells by the pharmacological inhibition of KCa3.1 may be beneficial in the treatment of chronic inflammatory diseases such as inflammatory bowel disease.

GYY4137 alleviates sepsis-induced acute lung injury in mice by inhibiting the PDGFRβ/Akt/NF-κB/NLRP3 pathway

AIMS

GYY4137 [GYY, morpholin-4-ium-4-methoxyphenyl (morpholino) phosphinodithioate] is a novel and perfect hydrogen sulfide (H₂S) donor that is stable in vivo and in vitro. H₂S, along with CO and NO, has been recognized as the third physiological gas signaling molecule that plays an active role in fighting various lung infections. However, the mechanism by which GYY4137 affects cecal ligation and puncture (CLP)-induced acute lung injury (ALI) is not understood. This study aimed to investigate whether GYY4137 inhibits the activation of the pyrin domain-containing protein 3 (NLRP3) inflammasome by inhibiting the PDGFRβ/Akt/NF-κB pathway.

MAIN METHODS

The model of CLP-induced ALI was established in vivo. The mice were subsequently treated with GYY4137 (25 μg/g and 50 μg/g) to simulate the realistic conditions of pathogenesis. Western blotting and immunohistochemical staining were used to examine protein expression, hematoxylin and eosin staining was used for the histopathological analysis, and the levels of inflammatory factors were determined using enzyme-linked immunosorbent assays (ELISAs).

KEY FINDINGS

GYY4137 significantly increased the 7-day survival of mice with septic peritonitis and protected against CLP-induced ALI, including decreasing neutrophil infiltration, improving sepsis-induced lung histopathological changes, diminishing lung tissue damage, and attenuating the severity of lung injury in mice. The protective effect of GYY4137 was undoubtedly dose-dependent. We discovered that GYY4137 reduced the levels of the p-PDGFRβ, p-NF-κB, ASC, NLRP3, caspase-1, and p-Akt proteins in septic mouse lung tissue. Akt regulates the generation of proinflammatory cytokines in endotoxemia-associated ALI by enhancing the nuclear translocation of NF-κB.

SIGNIFICANCE

These results indicate a new molecular mechanism explaining the effect of GYY4137 on the treatment of CLP-induced ALI in mice.

Monosexual Cercariae of Schistosoma japonicum Infection Protects Against DSS-Induced Colitis by Shifting the Th1/Th2 Balance and Modulating the Gut Microbiota

Inflammatory bowel disease (IBD)-related inflammation is closely associated with the initiation and progression of colorectal cancer. IBD is generally treated with 5-aminosalicylic acid and immune-modulating medication, but side effects and limitations of these therapies are emerging. Thus, the development of novel preventative or therapeutic approaches is imperative. Here, we constructed a dextran sodium sulphate (DSS)-induced IBD mouse model that was infected with monosexual Schistosoma japonicum cercariae (mSjci) at day 1 or administered dexamethasone (DXM) from days 3 to 5 as a positive control. The protective effect of mSjci on IBD mice was evaluated through their assessments of their clinical signs, histopathological lesions and intestinal permeability. To uncover the underlying mechanism, the Th1/Th2 balance and Treg cell population were also examined. Additionally, the alterations in the gut microbiota were assessed to investigate the interaction between the mSjci-modulated immune response and pathogenic microbiome. Mice treated with DSS and mSjci showed fewer IBD clinical signs and less impaired intestinal permeability than DSS-treated mice. Mechanistically, mSjci modulated the Th1/Th2 balance by repressing IFN-γ production, promoting IL-10 expression and enhancing the Treg subset population. Moreover, mSjci notably reshaped the structure, diversity and richness of the gut microbiota community and subsequently exerted immune-modulating effects. Our findings provide evidence showing that mSjci might serve as a novel and effective protective strategy and that the gut microbiota might be a new therapeutic target in IBD.

The Function and Role of the Th17/Treg Cell Balance in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, inflammatory, and autoimmune disorder. The pathogenesis of IBD is not yet clear. Studies have shown that the imbalance between T helper 17 (Th17) and regulatory T (Treg) cells, which differentiate from CD4⁺ T cells, contributes to IBD. Th17 cells promote tissue inflammation, and Treg cells suppress autoimmunity in IBD. Therefore, Th17/Treg cell balance is crucial. Some regulatory factors affecting the production and maintenance of these cells are also important for the proper regulation of the Th17/Treg balance; these factors include T cell receptor (TCR) signaling, costimulatory signals, cytokine signaling, bile acid metabolites, and the intestinal microbiota. This article focuses on our understanding of the function and role of the balance between Th17/Treg cells in IBD and these regulatory factors and their clinical significance in IBD.

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.

Mesenchymal Stromal Cell Therapy in the Management of Perianal Fistulas in Crohn's Disease: An Up-To-Date Review

Crohn's Disease (CD) is a chronic inflammatory disorder that potentially involves the entire gastrointestinal tract. Perianal fistulizing CD (pCD) is a serious and frequent complication associated with significant morbidities and a heavy negative impact on quality of life. The aim of CD treatment is to induce and maintain disease remission and to promote mucosal repair. Unfortunately, even the best therapeutic regimens in pCD do not have long-term efficacy and cause a significant number of side effects. Therefore, it is mandatory to study new therapeutical options such as the use of mesenchymal stromal cells (MSCs). These cells promote tissue repair via the induction of immunomodulation. The present review aims to analyze the existing updated scientific literature on MSCs adoption in the treatment of pCD to evaluate its efficacy and safety and to compare the use of bone marrow and adipose tissue derived MSCs, type of administration, and dose required for recovery.

Inflammatory bowel disease: Therapeutic limitations and prospective of the stem cell therapy

Inflammatory bowel disease (IBD), consisting primarily of ulcerative colitis and Crohn’s disease, is a group of debilitating auto-immune disorders, which also increases the risk of colitis-associated cancer. However, due to the chronic nature of the disease and inconsistent treatment outcomes of current anti-IBD drugs (e.g., approximately 30% non-responders to anti-TNFα agents), and related serious side effects, about half of all IBD patients (in millions) turn to alternative treatment options. In this regard, mucosal healing is gaining acceptance as a measure of disease activity in IBD patients as recent studies have correlated the success of mucosal healing with improved prognosis. However, despite the increasing clinical realization of the significance of the concept of mucosal healing, its regulation and means of therapeutic targeting remain largely unclear. Here, stem-cell therapy, which uses hematopoietic stem cells or mesenchymal stem cells, remains a promising option. Stem cells are the pluripotent cells with ability to differentiate into the epithelial and/or immune-modulatory cells. The over-reaching concept is that the stem cells can migrate to the damaged areas of the intestine to provide curative help in the mucosal healing process. Moreover, by differentiating into the mature intestinal epithelial cells, the stem cells also help in restoring the barrier integrity of the intestinal lining and hence prevent the immunomodulatory induction, the root cause of the IBD. In this article, we elaborate upon the current status of the clinical management of IBD and potential role of the stem cell therapy in improving IBD therapy and patient’s quality of life.

Elemental Diet Enriched with Amino Acids Alleviates Mucosal Inflammatory Response and Prevents Colonic Epithelial Barrier Dysfunction in Mice with DSS-Induced Chronic Colitis

BACKGROUND

Clinical data suggest that enteral nutrition (EN) effectively decreases disease activity and maintains remission in patients with inflammatory bowel disease (IBD). However, the modulatory effects of EN on the intestinal mucosal immune system remain unclear.

AIMS

This study first aimed at comparing the therapeutic effects of three EN formulas on ameliorating dextran sulfate sodium- (DSS-) induced chronic colitis; with the most effective formula, we then examined its influence on the mucosal inflammatory response and epithelial barrier function.

METHODS

The effect of EN formulas on colitis in mice was assessed by body weight, disease activity index scores, colon length, and H&E staining for pathological examination. Colonic and circulating cytokine expression levels and the frequencies of immune cells were also analyzed. Intestinal epithelial barrier function was evaluated by detecting tight junction proteins.

RESULTS

We found that among the three EN formulas, an elemental diet (ED) containing enriched amino acids restored the colitis-related reduction in body weight better than the other two EN formulas. ED amino acids suppressed the release of colonic proinflammatory mediators and maintained the expression of tight junction proteins in these mice. ED amino acid treatment mitigated the colitis-induced increase in CD103+CD11b+ dendritic cells and CD4+ and CD8+ T cells and inhibited the predominant Th1/Th17 responses particularly in the colonic mucosal lamina propria of mice with colitis.

CONCLUSIONS

We showed that ED amino acids can be an effective immunomodulatory agent to reduce colitis-related inflammation by inhibiting proinflammatory mediators and Th1/Th17 cell responses and by repairing the disrupted epithelial barrier.

Maresin1 ameliorates acute lung injury induced by sepsis through regulating Th17/Treg balance

The disturbance of the immune homeostasis caused by infection is decisive for multiple organ dysfunction caused by sepsis. Both the th17 cell and the regulatory cell(Tregs) are important components of the immune system and play a crucial role in maintaining immune homeostasis. In this study, we explored the effect of Maresin1, an emerging specific pro-inflammatory mediator, on the balance of Th17/Treg in sepsis, and investigated the underlying mechanism. We used the male C57BL/6 mice to establish the model of sepsis-induced lung injury by cecal ligation and puncture to verify the protective effect of Maresin1. Our study showed that Maresin1 could significantly inhibit the excessive inflammatory response and promote the inflammation regression in the process of sepsis-induced acute lung injury, thereby reducing lung damage and improving lung function. These effects were accompanied with the regulation of Maresin1 on the Th17/Treg balance in the early stages of sepsis. We demonstrated that Maresin1 has a certain effect on increasing the number of Treg and decreasing the number of Th17 cells in the early stages of sepsis, which is consistent with its effect on STAT3/RORγt and STAT5/Foxp3 signal pathways. Our study elucidated for the first time the relationship between Maresin1 and Th17/Treg balance in sepsis-induced acute lung injury.

Tryptophan Metabolism, Regulatory T Cells, and Inflammatory Bowel Disease: A Mini Review

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract resulting from the homeostasis imbalance of intestinal microenvironment, immune dysfunction, environmental and genetic factors, and so on. This disease is associated with multiple immune cells including regulatory T cells (Tregs). Tregs are a subset of T cells regulating the function of various immune cells to induce immune tolerance and maintain intestinal immune homeostasis. Tregs are correlated with the initiation and progression of IBD; therefore, strategies that affect the differentiation and function of Tregs may be promising for the prevention of IBD-associated pathology. It is worth noting that tryptophan (Trp) metabolism is effective in inducing the differentiation of Tregs through microbiota-mediated degradation and kynurenine pathway (KP), which is important for maintaining the function of Tregs. Interestingly, patients with IBD show Trp metabolism disorder in the pathological process, including changes in the concentrations of Trp and its metabolites and alteration in the activities of related catalytic enzymes. Thus, manipulation of Treg differentiation through Trp metabolism may provide a potential target for prevention of IBD. The purpose of this review is to highlight the relationship between Trp metabolism and Treg differentiation and the role of this interaction in the pathogenesis of IBD.

Ethanol extract of Pycnoporus sanguineus relieves the dextran sulfate sodium-induced experimental colitis by suppressing helper T cell-mediated inflammation via apoptosis induction

Inflammatory bowel disease (IBD) is a chronic relapsing inflammation involving the gut system, and disequilibrium of T helper (Th) cell paradigm has been recognized as critical pathogenesis. Pycnoporus sanguineus (L.) Murrill is a species of the white-rot basidiomycetes listed as food- and cosmetic-grade microorganisms. In this study, anti-inflammatory activity of the ethanol extract from P. sanguineus (PSE) was investigated in dextran sulfate sodium (DSS)-induced experimental colitis model. PSE recovered the DSS-caused weight loss, reversed the colon shortening, and ameliorated the histopathological lesion in colon, resulting in lower disease activity index (DAI). Levels of serumal lipopolysaccharide (LPS), colonic myeloperoxidase (MPO) in the colitis-suffering mice were declined by PSE treatment. PSE also improved the mucosal integrity by enhancing the expression of tight junction and adherens junction proteins in the colon, including ZO-1, occludin, claudin-1, and E-cadherin. Besides, PSE reduced helper T cells (Th) in the colon, together with an evident decrease of several Th cell-related cytokines. Moreover, it was found that in vitro, PSE suppressed T cells and the Th subset upon Concanavalin A (ConA)-stimulation by inducing apoptosis. In summary, PSE displayed a remission on the colitis-related inflammation, which would possibly rely on the epithelial barrier restoration by suppressing Th cells via apoptosis induction, highlighting a promising potential in the treatment for IBD.

Specific T-Cell Subsets Can Predict the Efficacy of Anti-TNF Treatment in Inflammatory Bowel Diseases

The effect of TNF-blockers on T-lymphocyte subsets is largely unknown in inflammatory bowel diseases (IBDs). The aim of the present study was to analyze the prevalence of T-cell subtypes and their correlation to therapeutic response. Sixty-eight patients with Crohn’s disease (CD), 46 with ulcerative colitis (UC) were enrolled. (1) The clinical course was followed after the initiation of TNF-blockers (prospective study). (2) The immunophenotype was also compared between long-term anti-TNF treated-responders and non-responders (cross-sectional study). The results were compared with those of therapy-naïve patients with active disease and those in remission with non-biological immunosuppressive therapy, and with healthy controls. Fourteen subtypes of peripheral blood T cells were measured with flow cytometry. The prevalence of Th2 and Th17 cells, of HLA-DR- and CD69-positive CD4 and CD8 cells, was higher, whereas the percentage of CD45RA-positive CD4 and CD8 cells was lower in both IBDs than in controls. CD8CD69 cell frequency was lower in remission, and decreased during anti-TNF therapy in CD responders. CD8CD45RO memory cells had higher prevalence in UC non-responders than in those starting anti-TNF. CD4CD45RO percentage < 49.05 at the initiation of TNF-blockers was predictive of a subsequent therapeutic response in CD, and Th2 and Th17 prevalence correlated with the duration of remission on TNF-blockers in UC. This study provided a detailed description of the T-cell composition in IBDs. CD8CD69 prevalence may be an activity marker in CD, and CD4CD45RO, Th2 and Th17 levels could be predictive for a therapeutic response to anti-TNF.

Increased frequency of regulatory T cells in pediatric inflammatory bowel disease at diagnosis: a compensative role?

BACKGROUND

Regulatory T cells (Tregs) play a critical role in maintaining immune homeostasis. We investigated two main types of Tregs, the CD4+FOXP3+ and IL-10+ Tr1, in pediatric subjects with inflammatory bowel disease (IBD) both at diagnosis and after the clinical remission.

METHODS

Peripheral blood Tregs were analyzed in 16 children with Crohn's disease (CD), 19 with ulcerative colitis (UC), and 14 healthy controls (HC). Two cocktails of fluoresceinated antibodies were used to discriminate between CD4+FOXP3+ and Tr1.

RESULTS

We observed in both CD and UC groups a higher frequency of Tr1 at diagnosis compared to controls, which decreased at follow-up compared to diagnosis, in particular in UC. Similarly, in UC patients the percentage of CD4+FOXP3+ Tregs markedly decreased at follow-up compared to the same patients at diagnosis and compared to HC. The expression of CTLA-4 in CD4+FOXP3+ Tregs increased in both groups at clinical remission.

CONCLUSION

This study shows that IBD children present at diagnosis an increased frequency of circulating Tregs, probably as a compensative reaction to tissue inflammation. During the clinical remission, the Treg frequency diminishes, and concomitantly, their activation status increases. Notwithstanding, the high Treg density at diagnosis is not sufficient to counteract the inflammation in the childhood IBD.

Emerging treatments for inflammatory bowel disease

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is characterized by chronic inflammation, a relapsing and remitting clinical course, requirement for lifelong medication and often, significant morbidity. While multiple effective therapeutic options exist for the treatment of IBD, a proportion of patients will either fail to respond or lose response to therapy. Advances in therapeutics, such as the gut-specific anti-integrins, now offer patients an alternative option to systemic immunosuppression. Anti-interleukin 12 (anti-IL-12)/IL-23 agents offer new and effective treatment options for CD, while the oral small molecules now offer an oral alternative for the treatment of moderate-to-severe disease, previously requiring subcutaneous injection or intravenous infusion. Alternatives to pharmacological treatment such as stem-cell transplant and faecal microbiota transplant are also showing some promise in the treatment of both CD and UC.

Degeneration of the intestinal microbial community in PI3Kγ-knockout mice

BACKGROUND AND AIM

PI3Kγ is closely related to inflammation and cardiovascular diseases and thus, PI3Kγ inhibitors are candidate drugs for the treatment of these disorders. Considering the potential effect of the intestinal microbiome on inflammation and cardiovascular diseases, this study aimed to identify characteristics of the intestinal microbial community under PI3Kγ deficiency, to help reveal the potential influence of PI3Kγ inhibitors mediated by the microbial community.

METHODS

Exon 2 of the PI3Kγ gene was knocked out in a Balb/c mouse by using single-guide RNAs. Homozygous PI3Kγ-knockout (PI3Kγ-/-) mice were obtained by embryo transfer and hybridization. PI3Kγ-/- and wild-type (WT) mice were raised in the same specific pathogen-free conditions until 8 weeks of age. Then, colonic tissues and feces from the middle segment of the colon were collected and analyzed by Illumina MiSeq sequencing. Differences in intestinal microbial community between the PI3Kγ-/- and WT mice were detected by bioinformatics analysis.

RESULTS

The richness and alpha diversity of the colonic microbial community were decreased in PI3Kγ-/- mice. The alpha diversity of the microbial community in feces did not differ between PI3Kγ-/- and WT mice. The beta diversity of the microbial community in feces of PI3Kγ-/- mice was obviously different from that in WT mice, whereas the within-group variation in Bray-Curtis distances of the mucosal microbial community was significantly decreased in PI3Kγ-/- mice. The topological structure of the species-related network of the colonic microbial community in PI3Kγ-/- mice was more polarized. Finally, we predicted that PI3Kγ deficiency might affect the synthesis of some antibiotics, bile acid, and thiamine through effects on the microbial community.

CONCLUSIONS

PI3Kγ dysfunction led to degeneration of the intestinal microbial community and might alter the synthesis of some antibiotics, bile acids, and thiamine. The usage of PI3Kγ inhibitors for inflammation and cardiovascular diseases might lead to knock-on effect on our organism through intestinal microbiota.

ECM1 is an essential factor for the determination of M1 macrophage polarization in IBD in response to LPS stimulation

Inflammatory bowel disease (IBD) comprises chronic relapsing disorders of the gastrointestinal tract characterized pathologically by intestinal inflammation and epithelial injury. Here, we uncover a function of extracellular matrix protein 1 (ECM1) in promoting the pathogenesis of human and mouse IBD. ECM1 was highly expressed in macrophages, particularly tissue-infiltrated macrophages under inflammatory conditions, and ECM1 expression was significantly induced during IBD progression. The macrophage-specific knockout of ECM1 resulted in increased arginase 1 (ARG1) expression and impaired polarization into the M1 macrophage phenotype after lipopolysaccharide (LPS) treatment. A mechanistic study showed that ECM1 can regulate M1 macrophage polarization through the granulocyte-macrophage colony-stimulating factor/STAT5 signaling pathway. Pathological changes in mice with dextran sodium sulfate-induced IBD were alleviated by the specific knockout of the ECM1 gene in macrophages. Taken together, our findings show that ECM1 has an important function in promoting M1 macrophage polarization, which is critical for controlling inflammation and tissue repair in the intestine.

Lineage Tracking the Generation of T Regulatory Cells From Microbial Activated T Effector Cells in Naïve Mice

Regulatory T cells (Tregs) are essential for the maintenance of gut homeostasis by suppressing conventional CD4⁺ helper T cells (Tconvs) that are activated by microbial antigens. Although thymus is the major source of the peripheral Tregs, peripheral conversion from Tconvs to Tregs have also been shown to occur under various experimental conditions. It remains less clear about the frequency of lineage conversion from Tconvs to Tregs in naïve animals. Here we used a newly established reporter system to track a group of post expansion Tregs (eTregs), which exhibited a stronger suppressive ability than the non-lineage marked Tregs. Notably, microbial antigens are the primary driver for the formation of eTregs. TCR repertoire analysis of Peyer's patch T cells revealed that eTregs are clonally related to Tconvs, but not to the non-lineage tracked Tregs. Adoptive transfer of Tconvs into lymphopenic hosts demonstrated a conversion from Tconvs to eTregs. Thus, our lineage tracking method was able to capture the lineage conversion from microbial activated effector T cells to Tregs in naïve animals. This study suggests that a fraction of clonally activated T cells from the natural T cell repertoire exhibits lineage conversion to Tregs in response to commensal microbes under homeostatic conditions.

Lactobacillus plantarum CBT LP3 ameliorates colitis via modulating T cells in mice

Lactobacillus plantarum has been identified as a probiotic bacterium owing to its role in immune regulation and maintenance of intestinal permeability. Here, we investigated the anti-colitic effects and mechanism of L. plantarum CBT LP3 (LP3). This in vivo study was performed using dextran sodium sulfate (DSS) to induce colitis in mice. Mice were randomly divided into three groups: a control supplied with normal drinking water, a DSS-treated group followed by oral administration of vehicle, and a DSS-treated group gavaged with LP3 daily for 7 days following DSS administration. An analysis of macrophages and T cell subsets harvesting from peritonium cavity cells and splenocytes was performed using a flow cytometric assay. Gene expression and cytokine profiles were measured using quantitative reverse transcriptase polymerase chain reaction. The administration of LP3 significantly attenuated disease activity and histolopathology compared to control. LP3 had anti-inflammatory effects, with increased induction of regulatory T cells and type 2 helper T cells in splenocytes and restoration of goblet cells accompanied by suppression of proinflammatory cytokine expressions. These findings suggest that L. plantarum CBT LP3 can be used as a potent immunomodulator, which has significant implications for IBD treatment.

Potential Vaccines for Treating Crohn's Disease

CD is an inflammatory disease of the GIT and can affect several parts of the digestive system. There is a relationship between impaired mucosal barrier in the GIT of IBD patients and the role of bacteria such as MAP in CD. Apart from different therapeutic approaches for treating CD, development of a vaccine is a novel modality. In the present article, most available therapeutic opportunities in the last decade, especially the possibility of vaccines against CD, are reviewed. According to the search, availability of a new generation of vaccines against CD is expected specially tolerogenic ex vivo -derived DC-based vaccines. Regarding different locations of the challenge and the variety of clinical manifests of CD and also the type of resident antigen-presenting cells and their traffic in different parts of GIT, the results of immunotherapy with DC-based vaccines may vary case by case.

Altered microbial community structure in PI3Kγ knockout mice with colitis impeding relief of inflammation: Establishment of new indices for intestinal microbial disorder

Lipopolysaccharide stimulates the intestinal microbiome to activate phosphoinositide 3 kinase (PI3K) signaling via several pathways; however, the direct effect that PI3K has on the intestinal bacterial community remains unclear. Herein, we investigate changes in the colonic microbiome of colitis PI3Kγ-knockout (PI3Kγ-/-) mice. Additionally, the effect of anal administration of colonic irrigation fluid from control mice to those with colitis was examined. Microbial 16S rRNA genes from the colonic mucosa of PI3Kγ-/- and WT mice were sequenced using Illumina MiSeq platform, and colonic IgA, IL-2, IL-10, and IL-17A production was quantified by western blot analysis. Myeloperoxidase (MPO) activity was detected by absorbance via colorimetric analysis. From the results, two new indices were derived by dividing the bacterial community into invading taxa, common taxa, and vanishing taxa. These indices were used to estimate the degree of microbiome disorder in chronic experimental colitis models. PI3Kγ-/- mice showed slower remission of inflammation as assessed by the disease activity index，pathological score, IL-2, IL-17, IL-10, IgA expression and MPO activity. The unique and common taxa of wild-type and PI3Kγ-/- mice increased as colitis symptoms regressed. Continuous loss of commensal bacteria happened with the continuous invasion of exogenous bacteria in the intestinal mucosa of PI3Kγ--/- mice after colitis begin to aggravate. However, transplantation of normal intestinal microbiota to PI3Kγ-/- mice promoted remission of inflammation; while the microbial dysbiosis observed during PI3Kγ dysfunction aggravated the intestinal microbiome disorder and impeded colitis recovery. Thus, the PI3Kγ signaling pathway may regulate microbial community composition in the colon.

Estrogen receptor β activation ameliorates DSS-induced chronic colitis by inhibiting inflammation and promoting Treg differentiation

Estrogen receptor (ER) β activation has anti-inflammatory activity. However, its effect on the development of inflammatory bowel disease (IBD) and the underlying mechanism have not been clarified. This study aimed to assess the clinical value of ERβ+CD4+ T cells in IBD patients and examine the anti-inflammatory role of ERβ activation in dextran sulfate sodium (DSS)-induced chronic colitis in mice. We investigated the effects of ERB041 (an ERβ-specific agonist) on inflammatory cytokines and pro-inflammatory T-cell and regulatory T-cell (Treg) responses in murine colitis. We tested the role of ERβ activation on Treg differentiation and its activity to suppress T-cell proliferation in vitro. We found that reduced frequency of circulating ERβ+CD4+ T cells in IBD patients was negatively correlated with inflammation and disease severity. ERβ and FoxP3 expression co-localized in the intestinal tissues of IBD patients. Treatment with ERB041 significantly mitigated colitis-induced weight loss, inflammation, and disease severity. It also restored the ERβ+CD4+ T cell population in the spleen and colon lamina propria of these mice. ERB041 treatment inhibited CD4+CD25- and CD8+ T cell infiltration and restored Tregs and activated T-cell immunoreceptor with Ig and ITIM domains (TIGIT)+ Tregs in the colon lamina propria. In vitro, we found that ERβ activation enhanced Treg differentiation, immunosuppression, and TGF-β1/Smad signaling in CD4+ T cells. Our data suggest that ERβ+CD4+ T cells represent a potential biomarker for evaluating IBD disease severity, and ERβ activation may be valuable for the treatment of IBD by enhancing the Treg response.

Immunomodulating Activity and Therapeutic Effects of Short Chain Fatty Acids and Tryptophan Post-biotics in Inflammatory Bowel Disease

Crohn's disease (CD) and Ulcerative colitis (UC) are grouped as Inflammatory Bowel Diseases (IBD). The IBD is associated to a multifaceted interplay between immunologic, microbial, genetic, and environmental factors. Nowadays, the gut microbiota (GM) dysbiosis has been indicated as a cause in the IBD development, affecting the impaired cross-talk between GM and immune cells. Moreover, recent studies have uncovered a crucial role for bacterial post-biotics (metabolites) in the orchestration of the host immune response, as they could be messengers between the GM and the immune system. In addition, transgenic mouse models showed that SCFAs (Short Chain Fatty Acids) and Tryptophan (Trp) post-biotics play important immunomodulatory effects, regulating both innate and adaptive immune cell generation, their function and trafficking. Here, we present an overview on the main microbial post-biotics and their effects on the gut mucosa with specific emphasis on their relevance for IBD. Finally, we discuss the therapeutic potential of SCFA and Trp post-biotics on IBD through approaches based on the "immunonutrition," defined as a modulation of the immune system provided by specific interventions that modify dietary nutrients.

Exosomes Derived From M2b Macrophages Attenuate DSS-Induced Colitis

Macrophages are commonly classified as M1 macrophages or M2 macrophages. The M2 macrophages are further sub-categorized into M2a, M2b, M2c, and M2d subtypes. The M2a, M2b, and M2c subtypes play roles in anti-inflammatory activity, tissue remodeling, type 2 T helper cell (Th2) activation, and immunoregulation. Previous studies have shown that macrophage exosomes can affect some disease processes. Exosomes are 30-150-nm lipid bilayer membrane vesicles derived from most living cells, with important biological functions. The role of exosomes in preventing the development of autoimmune diseases, including inflammatory bowel disease (IBD), has evoked increasing interest. Here, we analyze the roles of exosomes derived from M2a, M2b, and M2c macrophage phenotypes in dextran sulfate sodium (DSS)-induced colitis. Exosomes were isolated from the supernatant of different types of macrophages and identified via transmission electron microscopy (TEM), western blotting, and NanoSight. The results showed that M2b macrophage exosomes significantly attenuated the severity of DSS-induced colitis in mice. The number of regulatory T (Treg) cells in the spleens of mice with colitis and levels of IL-4 both increased following treatment with M2b macrophage exosomes. In addition, key cytokines associated with colitis (IL-1β, IL-6, and IL-17A) were significantly suppressed, following treatment with M2b macrophage exosomes. The M2b macrophage exosomes exerted protective effects on DSS-induced colitis, mainly mediated by the CC chemokine 1 (CCL1)/CCR8 axis. These findings provide a novel approach for the treatment of IBD.

Kuijieling-Containing Serum Regulates Th17 and Treg Cell Differentiation by Inhibiting STAT3 Signaling In Vitro

Object

To investigate the effect of Kuijieling (KJL) on the balance between T helper 17 (Th17) and regulatory T (Treg) cells in peripheral blood mononuclear cells (PBMC) in vitro and explore the underlying mechanism.

Materials and Methods

PBMCs isolated from rats were stimulated with transforming growth factor-β, interleukin (IL)-6, and IL-23 to induce the imbalance of Th17 and Treg cells and were treated with 10, 5, or 2.5% KJL-containing serum. The proportion of Th17 or Treg cells in CD4⁺ T cells was analyzed by flow cytometry, the concentrations of IL-17, IL-21, and IL-10 were assayed by ELISA, mRNA expressions of retinoic acid-related orphan receptor γt (RORγt), forkhead box protein 3 (Foxp3), and signal transducer and activator of transcription 3 (STAT3) were quantified by PCR, and phosphorylated STAT3 (p-STAT3) was analyzed by flow cytometry.

Results

KJL-containing serum decreased the proportion of Th17 cells and increased the proportion of Treg cells in CD4⁺ T cells, decreased the concentration of IL-17 and IL-21, enhanced the level of IL-10 in the cell culture supernatant, promoted the expression of Foxp3, and inhibited the levels of RORγt, STAT3, and p-STAT3.

Conclusion

KJL suppresses the STAT3 pathway to remedy the imbalance between Th17 and Treg cells.

Mesenchymal Stem Cells for Perianal Crohn's Disease

Perianal fistulizing Crohn’s disease (PFCD) is associated with significant morbidity and might negatively impact the quality of life of CD patients. In the last two decades, the management of PFCD has evolved in terms of the multidisciplinary approach involving gastroenterologists and colorectal surgeons. However, the highest fistula healing rates, even combining surgical and anti-TNF agents, reaches 50% of treated patients. More recently, the administration of mesenchymal stem cells (MSCs) have shown notable promising results in the treatment of PFCD. The aim of this review is to describe the rationale and the possible mechanism of action of MSC application for PFCD and the most recent results of randomized clinical trials. Furthermore, the unmet needs of the current administration process and the expected next steps to improve the outcomes will be addressed.

Protective effects of oxymatrine against DSS-induced acute intestinal inflammation in mice via blocking the RhoA/ROCK signaling pathway

Oxymatrine (OMT) is an important quinoxaline alkaloid that has a wide range of pharmacological effects and has been shown to alleviate ulcerative colitis due to its profound anti-inflammatory effects. The RhoA/ROCK (Rho kinase) signaling pathway has been shown to be related to the pathogenesis of several autoimmune diseases; however, the specific mechanisms of RhoA/ROCK signaling in inflammatory bowel disease (IBD) remain elusive. Therefore, we sought to determine whether OMT could ameliorate acute intestinal inflammation by targeting the RhoA/ROCK signaling pathway. The potential therapeutic effect of OMT on acute intestinal inflammation and its impact on the RhoA/ROCK signaling pathway were assessed in six groups of mice treated with low, medium and high doses of OMT (25, 50 and 100 mg/kg, respectively), and an inhibitor of ROCK, Y-27632, as a positive control, after initiating dextran sodium sulfate (DSS)-induced acute intestinal inflammation. The model group and normal group were injected intraperitoneally with equal doses of PBS. Our results showed that OMT treatment could protect the integrity of the epithelial barrier, relieve oxidative stress, inhibit the expression of inflammatory mediators and pro-inflammatory cytokines, restrain the differentiation of Th17 cells and promote the differentiation of Treg cells via inhibition of the RhoA/ROCK pathway, thus providing therapeutic benefits for ulcerative colitis (UC). Therefore, inhibiting the RhoA/ROCK pathway might be a new approach that can be used in UC therapy, which deserves to be investigated further.

Human gingiva-derived mesenchymal stem cells alleviate inflammatory bowel disease via IL-10 signalling-dependent modulation of immune cells

Current evidence indicates that inflammatory bowel disease (IBD) is caused primarily by impaired mucosal immunity, resulting in an imbalance between epithelial barrier function and tissue inflammation. Human gingiva-derived mesenchymal stem cells (GMSCs) exhibit immunomodulatory and anti-inflammatory effects in a variety of immunity- and inflammation-associated diseases. However, the role of GMSCs in treating IBD has not been elucidated. Our study, therefore, examined the therapeutic effect and mechanism of GMSCs in a murine colitis model of IBD. Our results indicate that the infusion of GMSCs significantly prolonged survival and relieved symptoms. Phenotype analyses showed that the frequencies of NK1.1⁺ and CD11b⁺ cells, as well as CD4 T cells in the spleen, were suppressed in GMSC-treated mice compared with the PBS- or fibroblast-treated control groups. Additionally, GMSC treatment markedly increased the numbers of interleukin (IL)-10⁺ regulatory T cells, reduced the secretion of pro-inflammatory cytokines, and increased production of anti-inflammatory cytokines. A mechanistic study revealed that anti-IL-10R antibody abolished the protective effect of GMSCs compared with mice treated with anti-IgG antibody. Thus, our results indicate that GMSCs play a critical role in alleviating colitis by modulating inflammatory immune cells via IL-10 signalling.

Stem cell therapy for perianal Crohn's

PURPOSE OF REVIEW

Perianal Crohn's disease is a morbid and disabling condition, notoriously difficult to successfully treat with conventional medical and surgical therapies. Mesenchymal stem cells (MSCs) are an emerging novel therapy for perianal Crohn's disease.

RECENT FINDINGS

Over 300 patients with perianal Crohn's disease have now been treated with MSCs in the context of clinical trials. All trials have demonstrated safety, and efficacy superior to conventional therapy with biologics and surgical intervention. This was consistent despite the heterogeneity in study protocols including variability in cell dosing, mode of delivery, repeat dosing, and allogeneic versus autologous donors. Sustained healing to 1 year has also been demonstrated in a recent extension of the largest phase III study confirming superior efficacy of MSCs to placebo at 1-year follow-up. However, several outstanding questions regarding the use of MSCs for perianal Crohn's disease remain, which, if answered, could enhance MSCs' treatment efficacy. These include defining the optimal MSC donor, optimal MSC source (e.g., bone marrow versus adipose tissue), investigating a potential alloimmune response following allogeneic cellular delivery, and determining the optimal mode for MSC delivery. In addition to these unanswered questions, significant challenges in the required infrastructure and cost required for cell-based therapies may drive future research toward identifying novel acellular therapies.

SUMMARY

Novel regenerative therapies offer promising new treatment options for perianal Crohn's disease, without the risk of opportunistic infection seen with biologics and incontinence with surgical techniques. Future research will help define the optimal MSC product and treatment protocol, and may even expand our horizon of regenerative medicine into acellular therapy as well as cell-based therapies.

Bioresponsive drug delivery systems in intestinal inflammation: State-of-the-art and future perspectives

Oral colon-specific delivery systems emerged as the main therapeutic cargos by making a significant impact in the field of modern medicine for local drug delivery in intestinal inflammation. The site-specific delivery of therapeutics (aminosalicylates, glucocorticoids, biologics) to the ulcerative mucus tissue can provide prominent advantages in mucosal healing (MH). Attaining gut mucosal healing and anti-fibrosis are main treatment outcomes in inflammatory bowel disease (IBD). The pharmaceutical strategies that are commonly used to achieve a colon-specific drug delivery system include time, pH-dependent polymer coating, prodrug, colonic microbiota-activated delivery systems and a combination of these approaches. Amongst the different approaches reported, the use of biodegradable polysaccharide coated systems holds great promise in delivering drugs to the ulcerative regions. The present review focuses on major physiological gastro-intestinal tract challenges involved in altering the pharmacokinetics of delivery systems, pathophysiology of MH and fibrosis, reported drug-polysaccharide cargos and focusing on conventional to advanced disease responsive delivery strategies, highlighting their limitations and future perspectives in intestinal inflammation therapy.

Research progress of P2X7 receptor in inflammatory bowel disease

Inflammatory bowel disease is a chronic nonspecific inflammatory disease of the intestine. Its pathogenesis is not yet fully understood. It may be related to heredity, environmental triggers, infection, immune dysfunction and other factors. Purinergic receptor (P2X7R) ligand-gated ion channel is closely related to inflammation and widely expressed in intestinal cells. Previous studies have shown that ATP/P2X7R signal is involved in the pathogenesis of intestinal inflammation, but its specific mechanism needs further study. This article reviews the research progress of P2X7 receptor in inflammatory bowel disease.

Correction of Defective T-Regulatory Cells From Patients With Crohn's Disease by Ex Vivo Ligation of Retinoic Acid Receptor-α

BACKGROUND & AIMS

Crohn's disease (CD) is characterized by an imbalance of effector and regulatory T cells in the intestinal mucosa. The efficacy of anti-adhesion therapies led us to investigate whether impaired trafficking of T-regulatory (Treg) cells contributes to the pathogenesis of CD. We also investigated whether proper function could be restored to Treg cells by ex vivo expansion in the presence of factors that activate their regulatory activities.

METHODS

We measured levels of the integrin α4β7 on Treg cells isolated from peripheral blood or lamina propria of patients with CD and healthy individuals (controls). Treg cells were expanded ex vivo and incubated with rapamycin with or without agonists of the retinoic acid receptor-α (RARA), and their gene expression profiles were analyzed. We also studied the cells in cytokine challenge, suppression, and flow chamber assays and in SCID mice with human intestinal xenografts.

RESULTS

We found that Treg cells from patients with CD express lower levels of the integrin α4β7 than Treg cells from control patients. The pathway that regulates the expression of integrin subunit α is induced by retinoic acid (RA). Treg cells from patients with CD incubated with rapamycin and an agonist of RARA (RAR568) expressed high levels of integrin α4β7, as well as CD62L and FOXP3, compared with cells incubated with rapamycin or rapamycin and all-trans retinoic acid. These Treg cells had increased suppressive activities in assays and migrated under conditions of shear flow; they did not produce inflammatory cytokines, and RAR568 had no effect on cell stability or lineage commitment. Fluorescently labeled Treg cells incubated with RAR568 were significantly more likely to traffic to intestinal xenografts than Treg cells expanded in control medium.

CONCLUSIONS

Treg cells from patients with CD express lower levels of the integrin α4β7 than Treg cells from control patients. Incubation of patients' ex vivo expanded Treg cells with rapamycin and an RARA agonist induced expression of α4β7 and had suppressive and migratory activities in culture and in intestinal xenografts in mice. These cells might be developed for treatment of CD. ClinicalTrials.gov, Number: NCT03185000.

Mevalonate promotes differentiation of regulatory T cells

Mevalonate is a precursor in a biosynthetic pathway that is important for the coordination of regulatory T cell (Treg) proliferation and upregulation of the suppressive function that establishes the functional competency of Tregs. The extensive role of mevalonate and its underlying effect on Treg differentiation are still unclear. We found that mevalonate increases in vitro differentiation of induced Tregs (iTregs) without broadly affecting Th1 and Th17 cell differentiation. Furthermore, an adoptive transfer study showed that mevalonate enhanced peripherally induced Treg cells (pTregs) in mesenteric lymphocytes in vivo. Mevalonate-treated iTregs exhibited greater suppressive activity against effector cells than untreated Tregs. Mechanistically, mevalonate enhanced transforming growth factor (TGF)-β signaling by increasing the phosphorylation of Smad3, but not Smad2, and by promoting Foxp3 expression. Furthermore, we demonstrated that mevalonate treatment ameliorated dextran sulfate sodium (DSS)-induced colitis and resulted in an increased percentage of Tregs in vivo. Our results suggest that mevalonate enhanced Treg differentiation and ameliorated DSS colitis, indicating its potential for treatment of inflammatory diseases.

Curcumin and Intestinal Inflammatory Diseases: Molecular Mechanisms of Protection

Intestinal inflammatory diseases, such as Crohn’s disease, ulcerative colitis, and necrotizing enterocolitis, are becoming increasingly prevalent. While knowledge of the pathogenesis of these related diseases is currently incomplete, each of these conditions is thought to involve a dysfunctional, or overstated, host immunological response to both bacteria and dietary antigens, resulting in unchecked intestinal inflammation and, often, alterations in the intestinal microbiome. This inflammation can result in an impaired intestinal barrier allowing for bacterial translocation, potentially resulting in systemic inflammation and, in severe cases, sepsis. Chronic inflammation of this nature, in the case of inflammatory bowel disease, can even spur cancer growth in the longer-term. Recent research has indicated certain natural products with anti-inflammatory properties, such as curcumin, can help tame the inflammation involved in intestinal inflammatory diseases, thus improving intestinal barrier function, and potentially, clinical outcomes. In this review, we explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its antimicrobial and immunomodulatory properties, as well as its potential to alter the intestinal microbiome. Curcumin may play a significant role in intestinal inflammatory disease treatment in the future, particularly as an adjuvant therapy.

Human LAP+GARP+FOXP3+ regulatory T cells attenuate xenogeneic graft versus host disease

Adoptive transfer of regulatory T cells (FOXP3⁺ Tregs) has been developed as a potential curative immune therapy to prevent and treat autoimmune and graft-versus-host diseases (GVHD). A major limitation that has hindered the use of Treg immunotherapy in humans is the difficulty of consistently isolating and obtaining highly purified Tregs after ex vivo expansion. Methods: We isolated bona fide Tregs from expansion cultures based on their selective surface expression of latency-associated peptide (LAP). The TCR Vβ diversity and intracellular cytokine production of Tregs were determined by flow cytometer. The TSDR methylation was determined by epigenetic human FOXP3 qPCR Assay. Their in vitro and in vivo potency was confirmed with suppression assay and humanized xenogeneic GVHD (xGVHD) murine model, respectively. Results: LAP⁺ repurification results in >90% LAP⁺FOXP3⁺ Tregs, leaving behind FOXP3^- and FOXP3⁺ nonTregs within the LAP^- population. After 4-week expansion, the LAP⁺ Tregs were >1 billion cells, highly suppressive and anergic in vitro, >90% demethylated in the TSDR and able to maintain TCR Vβ diversity. In the xGVHD model, exogenous CD25^-PBMC administered alone results in a median survival of 32 days. The co-transfer of LAP⁺ Tregs increased median survival to 47 days, while the LAP parent (CD25⁺) and LAP^- nonTregs had median survival of 39 and 31 days, respectively. Conclusions: These preclinical data together provide evidence that LAP⁺ Tregs are highly purified with fully suppressive function for cell therapy. This population results in a more effective and safer product for immunotherapy to treat GVHD and provides the necessary preclinical data for transition into a clinical trial with LAP⁺ Tregs to prevent or treat GVHD and other autoimmune diseases.

Stem Cell Therapies for Inflammatory Bowel Disease

PURPOSE OF REVIEW

Stem cell therapies have demonstrated safety and efficacy in the treatment of perianal Crohn's disease as compared to conventional therapy. Thus, an understanding of their place in the treatment algorithm for inflammatory bowel disease has become imperative as we move into an era of regenerative medicine.

RECENT FINDINGS

There have now been over a dozen clinical trials highlighting stem cells as a useful therapeutic in Crohn's disease. Due to the success in the local treatment for perianal Crohn's disease, investigation is continuing in the space of targeted systemic delivery for the treatment of luminal disease. As we increase the number of patients treated in clinical trials, it is imperative to define the optimal cell donor, optimize treatment dosing and retreatment protocols, and understand methods for safely targeting and treating intraluminal disease.

Soybean Meal-Induced Intestinal Inflammation in Zebrafish Is T Cell-Dependent and Has a Th17 Cytokine Profile

Currently, inflammatory bowel disease (IBD) is a serious public health problem on the rise worldwide. In this work, we utilized the zebrafish to introduce a new model of intestinal inflammation triggered by food intake. Taking advantage of the translucency of the larvae and the availability of transgenic zebrafish lines with fluorescently labeled macrophages, neutrophils, or lymphocytes, we studied the behavior of these cell types in vivo during the course of inflammation. We established two feeding strategies, the first using fish that were not previously exposed to food (naïve strategy) and the second in which fish were initially exposed to normal food (developed strategy). In both strategies, we analyzed the effect of subsequent intake of a control or a soybean meal diet. Our results showed increased numbers of innate immune cells in the gut in both the naïve or developed protocols. Likewise, macrophages underwent drastic morphological changes after feeding, switching from a small and rounded contour to a larger and dendritic shape. Lymphocytes colonized the intestine as early as 5 days post fertilization and increased in numbers during the inflammatory process. Gene expression analysis indicated that lymphocytes present in the intestine correspond to T helper cells. Interestingly, control diet only induced a regulatory T cell profile in the developed model. On the contrary, soybean meal diet induced a Th17 response both in naïve and developed model. In addition, when feeding was performed in rag1-deficient fish, intestinal inflammation was not induced indicating that inflammation induced by soybean meal is T cell-dependent.

Cellular and Molecular Therapeutic Targets in Inflammatory Bowel Disease-Focusing on Intestinal Barrier Function

The human gut relies on several cellular and molecular mechanisms to allow for an intact and dynamical intestinal barrier. Normally, only small amounts of luminal content pass the mucosa, however, if the control is broken it can lead to enhanced passage, which might damage the mucosa, leading to pathological conditions, such as inflammatory bowel disease (IBD). It is well established that genetic, environmental, and immunological factors all contribute in the pathogenesis of IBD, and a disturbed intestinal barrier function has become a hallmark of the disease. Genetical studies support the involvement of intestinal barrier as several susceptibility genes for IBD encode proteins with key functions in gut barrier and homeostasis. IBD patients are associated with loss in bacterial diversity and shifts in the microbiota, with a possible link to local inflammation. Furthermore, alterations of immune cells and several neuro-immune signaling pathways in the lamina propria have been demonstrated. An inappropriate immune activation might lead to mucosal inflammation, with elevated secretion of pro-inflammatory cytokines that can affect the epithelium and promote a leakier barrier. This review will focus on the main cells and molecular mechanisms in IBD and how these can be targeted in order to improve intestinal barrier function and reduce inflammation.

The Differential Roles of T Cells in Non-alcoholic Fatty Liver Disease and Obesity

Non-alcoholic fatty liver disease (NAFLD) constitutes a spectrum of disease states characterized by hepatic steatosis and is closely associated to obesity and the metabolic syndrome. In non-alcoholic steatohepatitis (NASH), additionally, inflammatory changes and hepatocellular damage are present, representing a more severe condition, for which the treatment is an unmet medical need. Pathophysiologically, the immune system is one of the main drivers of NAFLD progression and other obesity-related comorbidities, and both the innate and adaptive immune system are involved. T cells form the cellular component of the adaptive immune system and consist of multiple differentially active subsets, i.e., T helper (Th) cells, regulatory T (Treg) cells, and cytotoxic T (Tc) cells, as well as several innate T-cell subsets. This review focuses on the role of these T-cell subsets in the pathogenesis of NAFLD, as well as the association with obesity and type 2 diabetes mellitus, reviewing the available evidence from both animal and human studies. Briefly, Th1, Th2, Th17, and Th22 cells seem to have an attenuating effect on adiposity. Th2, Th22, and Treg cells seem to decrease insulin resistance, whereas Th1, Th17, and Tc cells have an aggravating effect. Concerning NAFLD, both Th22 and Treg cells appear to have an overall tempering effect, whereas Th17 and Tc cells seem to induce more liver damage and fibrosis progression. The evidence regarding the role of the innate T-cell subsets is more controversial and warrants further exploration.

Unique Phenotypes and Functions of Follicular Helper T Cells and Regulatory T Cells in Sjögren's Syndrome

Sjogren’s syndrome (SS) is a T cell-mediated autoimmune disease of the systemic exocrine glands, such as salivary and lacrimal glands. A variety of T-cell subpopulations maintain immune tolerance in the thymus and periphery through complex immune responses including cellular and humoral immunity. The T-cell subpopulations exhibiting abnormal or unique phenotypes and impaired functionality have been reported to play important roles in the cellular mechanisms of autoimmunity in SS patients and animal models of SS. In this review, we focused on follicular helper T cells related to antibody production and regulatory T cells to control immune tolerance in the pathogenesis of SS. The unique roles of these T-cell subpopulations in the process of the onset or development of SS have been demonstrated in this review of recent publications. The clinical application of these T-cell subpopulations will be helpful for the development of new techniques for diagnosis or treatment of SS in the future.

Intestinal CD4 Depletion in HIV / SIV Infection

Among the most significant findings in the pathogenesis of HIV infection was the discovery that almost total depletion of intestinal CD4+ T cells occurs rapidly after SIV or HIV infection, regardless of the route of exposure, and long before CD4+ T cell losses occur in blood or lymph nodes. Since these seminal discoveries, we have learned much about mucosal and systemic CD4+ T cells, and found several key differences between the circulating and intestinal CD4+ T cell subsets, both in phenotype, relative proportions, and functional capabilities. Further, specific subsets of CD4+ T cells are selectively targeted and eliminated first, especially cells critically important for initiating primary immune responses, and for maintenance of mucosal integrity (Th1, Th17, and Th22 cells). This simultaneously results in loss of innate immune responses, and loss of mucosal integrity, resulting in mucosal, and systemic immune activation that drives proliferation and activation of new target cells throughout the course of infection. The propensity for the SIV/HIV to infect and efficiently replicate in specific cells also permits viral persistence, as the mucosal and systemic activation that ensues continues to damage mucosal barriers, resulting in continued influx of target cells to maintain viral replication. Finally, infection and elimination of recently activated and proliferating CD4+ T cells, and infection and dysregulation of Tfh and other key CD4+ T cell results in hyperactive, yet non-protective immune responses that support active viral replication and evolution, and thus persistence in host tissue reservoirs, all of which continue to challenge our efforts to design effective vaccine or cure strategies.

Anti-Inflammatory Effect of IL-37-Producing T-Cell Population in DSS-Induced Chronic Inflammatory Bowel Disease in Mice

Inflammatory bowel disease (IBD) is a chronic inflammatory disease that is thought to arise in part from abnormal adaptive immune responses against intestinal microbiota. T lymphocytes play significant roles in triggering mucosal inflammation and/or maintaining gut immune homeostasis. It has been demonstrated that IL-37 expresses in a variety of cells and exerts a protective function involved in both innate immunity and adaptive immunity. In the present study, a population of IL-37-producing T-cells was detected in the spleen and mesenteric lymph nodes (MLNs) in IL-37+/+ mice after dextran sodium sulfate (DSS) induction. Adoptive transfer of the T-cells from the spleen of IL-37+/+ mice following DSS treatment partly recovered the body weight, improved the disease activity index (DAI) and macroscopic damage score, and attenuated the intestinal inflammation. In addition, colon shortening, an indirect marker of inflammation, was decreased, consistent with the decreased IFN-γ level and the increased IL-10 level in the colonic tissue. Collectively, our data uncovered a subset of T-lymphocytes expressing IL-37, which represents a potent regulation of immunity and serves as the protective role in chronic IBD.

IL-33 Protects Mice against DSS-Induced Chronic Colitis by Increasing Both Regulatory B Cell and Regulatory T Cell Responses as Well as Decreasing Th17 Cell Response

BACKGROUND

Previously, we have reported that IL-33 functioned as a protective modulator in dextran sulfate sodium- (DSS-) induced chronic colitis by suppressing Th17 cell response in colon lamina propria and IL-33 induced both regulatory B cells (Bregs) and regulatory T cells (Tregs) in mesenteric lymph nodes (MLNs) of mice with DSS-induced acute colitis. Moreover, we speculated that IL-33 would promote the Treg or Breg responses leading to the attenuation of DSS-induced chronic colitis. So, we investigated the role of IL-33 on Bregs and Tregs in the MLN of DSS-induced chronic colitis mice.

METHODS

IL-33 was administered by intraperitoneal injection to mice with DSS-induced chronic colitis. Clinical symptoms, colon length, and histological changes were determined. The production of cytokines was measured by ELISA. The T and B cell subsets were measured by flow cytometry. The expression of mRNA of transcription factors was measured by quantitative real-time PCR.

RESULTS

We show that IL-33 treatment increases both Breg and Treg responses in the MLN of mice with DSS-induced chronic colitis. Moreover, IL-33 treatment also decreases Th17 cell response in the MLN of mice with DSS-induced chronic colitis.

CONCLUSION

Our data provide clear evidence that IL-33 plays a protective role in DSS-induced chronic colitis, which is closely related to increasing Breg and Treg responses in the MLN of mice as well as suppressing Th17 cell responses.

Role of Regulatory T Cells in Tumor-Bearing Mice Treated with Allo-Hematopoietic Stem Cell Transplantation Plus Thymus Transplantation

We recently developed a new allogeneic hematopoietic stem cell transplantation method (allo-HSCT) combined with thymus transplantation (TT) from the same donor (allo-HSCT + TT). This method induces elevated T cell function with mild graft-versus-host disease (GVHD) in comparison to conventional HSCT alone and HSCT + donor lymphocyte infusion (DLI). This new method is effective against several intractable diseases, including malignant tumors, for which conventional treatments are ineffective. Regulatory T (T_reg) cells play an important role in the enhanced graft-versus-tumor (GVT) effect and reduction of GVHD, thus leading to longer survival. Replacement and reduction of elevated T_reg cells by donor-derived allo-T_reg cells from the transplanted thymus may play one of crucial roles in the effect. This review discusses the role of T_reg cells in a tumor-bearing mouse model treated with allo-HSCT + TT.

Kuijieling regulates the differentiation of Treg and Th17 cells to ameliorate experimental colitis in rats

BACKGROUND

Regulatory T (Treg) cells and T helper 17 (Th17) cells play crucial roles in ulcerative colitis (UC). Kuijieling (KJL) is an effective Chinese medicine formula for treating UC in clinic. Kuijieling has shown remedy effect on the imbalance between Treg and Th17 cells. This study aimed to further reveal the exact underlying mechanism of how Kuijieling regulates the differentiation of Treg and Th17 cells in the treatment of UC.

METHODS

Colitis was induced by trinitrobenzene sulfonic acid in rats and treated by KJL. Pathological injury was evaluated by HE staining and pathological score. Transforming growth factor-β1 (TGF-β1), interleukin(IL)-2, IL-6, IL-10, IL-17, IL-23 and IL-21 in plasma were assayed by ELISA. Forkhead box P3 (Foxp3), signal transducer and activator of transcription (STAT) 5 expressed in colon mucosa were measured by western blot. Immunohistochemistry was employed for quantifying retinoic acid-related orphan receptor γt (RORγt) and STAT3 in colon. RT-PCR was used to analyze the expression of IL-2, IL-17, IL-23, IL-21 mRNA in colon.

RESULTS

After the administration of KJL, pathological injury in colon mucosa was reduced and histological score was decreased, transforming growth factor-β1 (TGF-β1), interleukin(IL)-2, IL-10 in blood and Foxp3, STAT5, IL-2 in colon increased significantly, IL-6, IL-23, IL-17, IL-21 in blood and RORγt, STAT3, IL-23, IL-17, IL-21 in colon decreased. Our result showed that KJL regulates the related cytokines and transcription factors to promote Treg cells and suppress Th17 cells.

CONCLUSION

KJL restores the balance between Treg and Th17 cells through regulating the differentiation of them, therefore contributes to the treatment of UC.

Immunotherapy in inflammatory bowel disease: Novel and emerging treatments

Inflammatory bowel disease (IBD) is a chronic disabling inflammatory process that affects young individuals, with growing incidence. The etiopathogenesis of IBD remains poorly understood. A combination of genetic and environmental factors triggers an inadequate immune response against the commensal intestinal flora in IBD patients. Thus, a better understanding of the immunological mechanisms involved in IBD pathogenesis is central to the development of new therapeutic options.

Current pharmacological treatments used in clinical practice like thiopurines or anti-TNF are effective but can produce significant side effects and their efficacy may diminish over time. In fact, up to one third of the patients do not have a satisfactory response to these therapies. Consequently, the search for new therapeutic strategies targeting alternative immunological pathways has intensified. Several new oral and parenteral substances are in the pipeline for IBD.

In this review we discuss novel therapies targeting alternative pro-inflammatory pathways like IL-12/23 axis, IL-6 pathway or Janus Kinase inhibitors; as well as others modulating anti-inflammatory signalling pathways like transforming growth factor-β1 (TGF-β1). We also highlight new emerging therapies targeting the adhesion and migration of leukocytes into the inflamed intestinal mucosa by blocking selectively different subunits of α₄β₇ integrins or binding alternative adhesion molecules like MAdCAM-1. Drugs reducing the circulating lymphocytes by sequestering them in secondary lymphoid organs (sphingosine-1-phosphate (S1P) receptor modulators) are also discussed. Finally, the latest advances in cell therapies using mesenchymal stem cells or engineered T regs are reviewed. In addition, we provide an update on the current status in clinical trials of these new immune-regulating therapies that open a new era in the treatment of IBD.

Autologous Haematopoietic Stem Cell Transplantation (AHSCT) in Severe Crohn's Disease: A Review on Behalf of ECCO and EBMT

Despite the major recent progress in the treatment of Crohn's disease [CD], there is a subset of patients in whom the disease runs an aggressive course with progressive tissue damage requiring early and repeated surgical management. Increasing evidence supports sustained and profound improvement in gastrointestinal parameters and quality of life following high-dose immunosuppressive therapy and autologous haematopoietic stem cell transplantation [AHSCT] compared to standard therapy in this context. In addition, international transplant registry data reflect the use of AHSCT in CD outside of trials in selected patients. However, AHSCT may be associated with significant treatment-related complications with risk of transplant-related mortality. In a joint initiative, the European Crohn's and Colitis Organisation [ECCO] and the European Society for Blood and Marrow Transplantation [EBMT] have produced a state-of-the-art review of the rationale, evaluation, patient selection, stem cell mobilization and transplant procedures and long-term follow up. Given the unique spectrum of issues, we recommend that AHSCT should only be performed in experienced centres with expertise in both haematological and gastroenterological aspects of the procedure. Where possible, patients should be enrolled on clinical trials and data registered centrally. Future development should be coordinated at both national and international levels.

The role of salt for immune cell function and disease

The immune system evolved to protect organisms from invading pathogens. A network of pro- and anti-inflammatory cell types equipped with special effector molecules guarantees efficient elimination of intruders like viruses and bacteria. However, imbalances can lead to an excessive response of effector cells incurring autoimmune or allergic diseases. An interplay of genetic and environmental factors contributes to autoimmune diseases and recent studies provided evidence for an impact of dietary habits on the immune status and related disorders. Western societies underwent a change in lifestyle associated with changes in food consumption. Salt (sodium chloride) is one component prevalent in processed food frequently consumed in western countries. Here we summarize recent advances in understanding the mechanisms behind the effects of sodium chloride on immune cells like regulatory T cells (Tregs) and T helper (T_H ) 17 cells and its implication as a risk factor for several diseases.

Antigen-specific Treg cells in immunological tolerance: implications for allergic diseases

Allergic diseases are chronic inflammatory disorders in which there is failure to mount effective tolerogenic immune responses to inciting allergens. The alarming rise in the prevalence of allergic diseases in recent decades has spurred investigations to elucidate the mechanisms of breakdown in tolerance in these disorders and means of restoring it. Tolerance to allergens is critically dependent on the generation of allergen-specific regulatory T (Treg) cells, which mediate a state of sustained non-responsiveness to the offending allergen. In this review, we summarize recent advances in our understanding of mechanisms governing the generation and function of allergen-specific Treg cells and their subversion in allergic diseases. We will also outline approaches to harness allergen-specific Treg cell responses to restore tolerance in these disorders.

The shifted balance between circulating follicular regulatory T cells and follicular helper T cells in patients with ulcerative colitis

B-cell immunity participates in the pathogenesis of ulcerative colitis (UC). The immune balance between follicular regulatory T (TFR) cells and follicular helper T (TFH) cells is important in regulating B-cell responses. However, the alteration of TFR/TFH balance in UC remains unclear. Peripheral blood from 25 UC patients and 15 healthy controls was examined for the frequencies of circulating TFR, TFH, and regulatory T (Treg) cells by flow cytometry. Levels of serum cytokines were measured using cytometric bead array (CBA). Disease activity was evaluated by the Mayo Clinic Score. Compared with controls, UC patients exhibited significant reductions in circulating Foxp3⁺CXCR5⁺ TFR cells, the subset interleukin (IL)-10⁺Foxp3⁺CXCR5⁺ cells, and Treg cells, but significant expansions in Foxp3^-CXCR5⁺ TFH cells and IL-21⁺Foxp3^-CXCR5⁺ cells. UC patients also had reduced levels of serum IL-10 and elevated levels of serum IL-21. The values of Mayo Clinic Score, C-reactive protein (CRP), or erythrocyte sedimentation rate (ESR) in UC patients were negatively correlated with circulating TFR cells, serum IL-10 level, and TFR/TFH ratio, while positively correlated with circulating TFH cells and serum IL-21 level. Alterations in circulating TFR and TFH cells shift the balance from immune tolerance to immune responsive state, contributing to dysregulated B-cell immunity and the pathogenesis of UC.