Expression of CD4+ forkhead box P3 (FOXP3)+ regulatory T cells in inflammatory bowel disease

Deficiency of Nuclear Receptor Nur77 Aggravates Mouse Experimental Colitis by Increased NFκB Activity in Macrophages

Nuclear receptor Nur77, also referred to as NR4A1 or TR3, plays an important role in innate and adaptive immunity. Nur77 is crucial in regulating the T helper 1/regulatory T-cell balance, is expressed in macrophages and drives M2 macrophage polarization. In this study we aimed to define the function of Nur77 in inflammatory bowel disease. In wild-type and Nur77-/- mice, colitis development was studied in dextran sodium sulphate (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced models. To understand the underlying mechanism, Nur77 was overexpressed in macrophages and gut epithelial cells. Nur77 protein is expressed in colon tissues from Crohn's disease and Ulcerative colitis patients and colons from colitic mice in inflammatory cells and epithelium. In both mouse colitis models inflammation was increased in Nur77-/- mice. A higher neutrophil influx and enhanced IL-6, MCP-1 and KC production was observed in Nur77-deficient colons after DSS-treatment. TNBS-induced influx of T-cells and inflammatory monocytes into the colon was higher in Nur77-/- mice, along with increased expression of MCP-1, TNFα and IL-6, and decreased Foxp3 RNA expression, compared to wild-type mice. Overexpression of Nur77 in lipopolysaccharide activated RAW macrophages resulted in up-regulated IL-10 and downregulated TNFα, MIF-1 and MCP-1 mRNA expression through NFκB repression. Nur77 also strongly decreased expression of MCP-1, CXCL1, IL-8, MIP-1α and TNFα in gut epithelial Caco-2 cells. Nur77 overexpression suppresses the inflammatory status of both macrophages and gut epithelial cells and together with the in vivo mouse data this supports that Nur77 has a protective function in experimental colitis. These findings may have implications for development of novel targeted treatment strategies regarding inflammatory bowel disease and other inflammatory diseases.

Moxibustion and Acupuncture Ameliorate Crohn's Disease by Regulating the Balance between Th17 and Treg Cells in the Intestinal Mucosa

Previous studies have demonstrated that acupuncture is beneficial to patients with Crohn's disease (CD), but the mechanism underlying its therapeutic effects remains unclear. To identify the mechanism by which acupuncture treats CD, the balance between Th17 and Treg cells was assessed in CD patients. In this study, Ninety-two CD patients were randomly and equally assigned to a treatment group that were treated with herb-partitioned moxibustion and acupuncture or a control group with wheat bran-partitioned moxibustion and superficial acupuncture. The effect of these treatments on Th17 and Treg cells and their related molecular markers in the intestinal mucosa were detected before (week 0) and after (week 12) treatment. The results suggested that the ratio of Th17 and Treg cells was significantly decreased after treatment and that the levels of IL-17 and RORγt in the intestinal mucosa were obviously reduced, while the expression of FOXP3 was increased after treatment in both groups. In the treatment group, the expression of these molecules was more markedly regulated than the control group. In conclusion, moxibustion and acupuncture have been shown to regulate the ratio of Th17 and Treg cells in the intestinal mucosa of CD patients and restore the balance between these immune cell subsets.

Changes in Foxp3-Positive Regulatory T Cell Number in the Intestine of Dogs With Idiopathic Inflammatory Bowel Disease and Intestinal Lymphoma

Although regulatory T cells (Tregs) play an integral role in immunologic tolerance and the maintenance of intestinal homeostasis, their involvement in canine gastrointestinal diseases, including idiopathic inflammatory bowel disease (IBD) and intestinal lymphoma, remains unclear. Here we show altered numbers of forkhead box P3 (Foxp3)-positive Tregs in the intestine of dogs with IBD and intestinal lymphoma. IBD was diagnosed in 48 dogs; small cell intestinal lymphoma was diagnosed in 46 dogs; large cell intestinal lymphoma was diagnosed in 30 dogs; and 25 healthy beagles were used as normal controls. Foxp3-positive Tregs in the duodenal mucosa were examined by immunohistochemistry and immunofluorescence. Duodenal expression of interleukin-10 mRNA was quantified by real-time reverse transcription polymerase chain reaction. The number of Foxp3-positive lamina propria cells and the expression of interleukin-10 mRNA were significantly lower in dogs with IBD than in healthy dogs and dogs with intestinal lymphoma. The number of Foxp3-positive intraepithelial cells was higher in dogs with small cell intestinal lymphoma. Some large cell intestinal lymphoma cases had high numbers of Foxp3-positive cells, but the increase was not statistically significant. Double-labeling immunofluorescence showed that CD3-positive granzyme B-negative helper T cells expressed Foxp3. In small cell intestinal lymphoma cases, the overall survival of dogs with a high Treg density was significantly worse than that of dogs with a normal Treg density. These results suggest that a change in the number of Foxp3-positive Tregs contributes to the pathogenesis of canine IBD and intestinal lymphoma by disrupting mucosal tolerance and suppressing antitumor immunity, respectively.

Expression of T helper type 17 (Th17)-associated cytokines and toll-like receptor 4 and their correlation with Foxp3 positive cells in rectal biopsies of horses with clinical signs of inflammatory bowel disease

Inflammatory bowel disease (IBD) in horses is an idiopathic disorder, encompassing different types of chronic intestinal inflammation. The pathogenesis of the disease remains to be established, but it has been suggested that an imbalance between regulatory T cells (Tregs) and T helper 17 (Th17)-associated cytokines and altered toll-like receptor 4 (TLR4) expression is associated with intestinal inflammation in other species. The aim of the present study was to quantify Tregs in rectal biopsies from horses affected with IBD by immunohistochemistry and to evaluate expression of genes encoding interleukin (IL)-12p40, IL-17A, IL-23p19 and TLR4 by real-time quantitative PCR. Rectal biopsies from 11 healthy horses and 11 horses with clinical signs of IBD, showing inflammation classified as chronic simple proctitis (CSP) or chronic active simple proctitis (CASP), were evaluated. Expression of IL-17A mRNA was greater in horses affected with CASP compared with horses with CSP or healthy horses. In contrast, expression of IL-12p40 was lower in horses with CSP compared with horses with CASP or healthy horses. TLR4 expression was greater in horses with CASP compared with healthy horses. A positive correlation was seen between the numbers of Tregs and expression of IL-17A and IL-23p19. An association was demonstrated between the histopathological pattern of inflammation, cytokine profile and number of infiltrating Tregs. The research findings suggest that Th17 cells are involved in active IBD, possibly through recruitment of neutrophils via IL-17A, in combination with inadequate suppression of the inflammatory response by Tregs.

In vitro assessment of the effects of vedolizumab binding on peripheral blood lymphocytes

Vedolizumab (VDZ) is a humanized monoclonal antibody in development for the treatment of inflammatory bowel disease. VDZ binds to the α4β7 integrin complex and inhibits its binding to mucosal addressin cell adhesion molecule-1 (MAdCAM-1), thus preventing lymphocyte extravasation to gut mucosal tissues. To understand whether VDZ has additional effects that may affect its overall safety as a therapeutic molecule, we examined other potential actions of VDZ. In vitro assays with human peripheral blood lymphocytes demonstrated that VDZ fails to elicit cytotoxicity, lymphocyte activation, and cytokine production from memory T lymphocytes and does not interfere with the suppressive ability of regulatory T cells. Furthermore, we demonstrated that VDZ induces internalization of α4β7 and that the integrin is rapidly re-expressed and fully functional after VDZ withdrawal. These studies provide insight into the mechanisms underlying the observed safety profile of VDZ in clinical trials.

Comprehensive intestinal T helper cell profiling reveals specific accumulation of IFN-γ+IL-17+coproducing CD4+ T cells in active inflammatory bowel disease

OBJECTIVE

Skewed T helper (TH) cell responses and specific functions of TH1, TH2, TH17, and Treg cells have been implicated in the pathogenesis of inflammatory bowel disease (IBD) that led to the establishment of the pathogenic TH1/TH2 and TH17/Treg cell imbalance paradigms. However, the relevant TH cell population driving mucosal inflammation is still unknown.

METHODS

We performed a comprehensive TH cell profiling of circulating and intestinal lymphocytes isolated from patients with Crohn's disease (CD; n = 69) and ulcerative colitis (UC; n = 41) undergoing endoscopy or surgical resection and compared them with healthy controls (n = 45). Mucosal inflammation was assessed endoscopically and histologically. TH cells were analyzed by flow cytometric evaluation of cytokine production and differentiation marker expression.

RESULTS

Specialized TH cell populations were enriched in the intestinal mucosa compared with peripheral blood. Specifically, we observed a concomitant upregulation of TH17 cells and Tregs in active inflammatory lesions in patients with both CD and UC compared with quiescent/mildly inflamed lesions and healthy tissue. Of note, interferon γ+ interleukin (IL)-17+coproducing CD4+ T cells with high expression of T-bet, CD26, and IL-22 resembling recently described pathogenic TH17 cells were specifically enriched in the inflamed mucosal tissue.

CONCLUSIONS

Our results argue against the controversial TH1/TH2 or TH17/Treg paradigms. In contrast, they suggest that a subpopulation of TH17 cells sharing a TH1 signature may be specifically involved in intestinal inflammation in CD and UC. These findings provide a better understanding of IBD pathogenesis and may help explain the efficacy of anti-IL-12p40/IL-23 and failure of anti-IL-17A therapies despite the enrichment of TH17 cells.

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.

Adipose-tissue and intestinal inflammation - visceral obesity and creeping fat

Obesity has become one of the main threats to health worldwide and therefore gained increasing clinical and economic significance as well as scientific attention. General adipose-tissue accumulation in obesity is associated with systemically increased pro-inflammatory mediators and humoral and cellular changes within this compartment. These adipose-tissue changes and their systemic consequences led to the concept of obesity as a chronic inflammatory state. A pathognomonic feature of Crohn’s disease (CD) is creeping fat (CF), a locally restricted hyperplasia of the mesenteric fat adjacent to the inflamed segments of the intestine. The precise role of this adipose-tissue and its mediators remains controversial, and ongoing work will have to define whether this compartment is protecting from or contributing to disease activity. This review aims to outline specific cellular changes within the adipose-tissue, occurring in either obesity or CF. Hence the potential impact of adipocytes and resident immune cells from the innate and adaptive immune system will be discussed for both diseases. The second part focuses on the impact of generalized adipose-tissue accumulation in obesity, respectively on the locally restricted form in CD, on intestinal inflammation and on the closely related integrity of the mucosal barrier.

Targeting sirtuin-1 alleviates experimental autoimmune colitis by induction of Foxp3+ T-regulatory cells

Induced Forkhead box P3-positive (Foxp3(+)) T-regulatory cells (iTregs) are essential to gastrointestinal immune homeostasis, and loss of the ability to develop iTregs may lead to autoimmune colitis. We previously showed a role for sirtuin-1 (Sirt1) in control of Treg function and hypothesized that targeting of Sirt1 might enhance iTreg development and thereby represent a potential therapy for inflammatory bowel disease (IBD). We adoptively transferred CD4(+)CD25(-)Foxp3(-) T effector (TE) cells from wild-type (WT) (C57BL/6) or fl-Sirt1/CD4cre mice into B6/Rag1(-/-) mice and monitored the mice until they lost 10-15% of their weight. Adoptive transfer of TE cells lacking Sirt1 to B6/Rag1(-/-) mice resulted in a 2.8-fold increase in iTreg formation compared with mice receiving WT TE cells and correlated with attenuated colitis and reduced weight loss (1.04±1.4% vs. 13.97±2.2%, respectively, P<0.001). In a second model of IBD, we used pharmacologic Sirt1 targeting of mice receiving multiple cycles of dextran sodium sulfate (DSS) in their drinking water, alternated with fresh water. Likewise, WT mice receiving cyclic DSS and a Sirt1 inhibitor, EX-527, had reduced weight loss (5.8±5.9% vs. 13.2±6.9%, respectively, P=0.03) and increased iTreg formation compared with controls. Sirt1 appears a promising target for pharmacologic therapy of IBD as a result of promoting iTreg development.

Diagnosis and management of microscopic colitis: current perspectives

Collagenous colitis and lymphocytic colitis, together constituting microscopic colitis, are common causes of chronic diarrhea. They are characterized clinically by chronic nonbloody diarrhea and a macroscopically normal colonic mucosa where characteristic histopathological findings are seen. Previously considered rare, they now have emerged as common disorders that need to be considered in the investigation of the patient with chronic diarrhea. The annual incidence of each disorder is five to ten per 100,000 inhabitants, with a peak incidence in 60- to 70-year-old individuals and a predominance of female patients in collagenous colitis. The etiology and pathophysiology are not well understood, and the current view suggests an uncontrolled mucosal immune reaction to various luminal agents in predisposed individuals. Clinical symptoms comprise chronic diarrhea, abdominal pain, fatigue, weight loss, and fecal incontinence that may impair the patient's health-related quality of life. An association is reported with other autoimmune disorders, such as celiac disease, thyroid disorders, diabetes mellitus, and arthritis. The best-documented treatment, both short-term and long-term, is budesonide, which induces clinical remission in up to 80% of patients after 8 weeks' treatment. However, after successful budesonide therapy is ended, recurrence of clinical symptoms is common, and the best possible long-term management deserves further study. The long-term prognosis is good, and the risk of complications, including colonic cancer, is low. We present an update of the epidemiology, pathogenesis, diagnosis, and management of microscopic colitis.

Bifidobacterium breve attenuates murine dextran sodium sulfate-induced colitis and increases regulatory T cell responses

While some probiotics have shown beneficial effects on preventing or treating colitis development, others have shown no effects. In this study, we have assessed the immunomodulating effects of two probiotic strains, Lactobacillus rhamnosus (L. rhamnosus) and Bifidobacterium breve (B. breve) on T cell polarization in vitro, using human peripheral blood mononuclear cells (PBMC), and in vivo, using murine dextran sodium sulfate (DSS) colitis model. With respect to the latter, the mRNA expression of T cell subset-associated transcription factors and cytokines in the colon was measured and the T helper type (Th) 17 and regulatory T cell (Treg) subsets were determined in the Peyer's patches. Both L. rhamnosus and B. breve incubations in vitro reduced Th17 and increased Th2 cell subsets in human PBMCs. In addition, B. breve incubation was also able to reduce Th1 and increase Treg cell subsets in contrast to L. rhamnosus. In vivo intervention with B. breve, but not L. rhamnosus, significantly attenuated the severity of DSS-induced colitis. In DSS-treated C57BL/6 mice, intervention with B. breve increased the expression of mRNA encoding for Th2- and Treg-associated cytokines in the distal colon. In addition, intervention with B. breve led to increases of Treg and decreases of Th17 cell subsets in Peyer's patches of DSS-treated mice. B. breve modulates T cell polarization towards Th2 and Treg cell-associated responses in vitro and in vivo. In vivo B. breve intervention ameliorates DSS-induced colitis symptoms and this protective effect may mediated by its effects on the T-cell composition.

Fallen angels or risen apes? A tale of the intricate complexities of imbalanced immune responses in the pathogenesis and progression of immune-mediated and viral cancers

Excessive immune responses directed against foreign pathogens, self-antigens, or commensal microflora can cause cancer establishment and progression if the execution of tight immuno-regulatory mechanisms fails. On the other hand, induction of potent tumor antigen-specific immune responses together with stimulation of the innate immune system is a pre-requisite for effective anti-tumor immunity, and if suppressed by the strong immuno-regulatory mechanisms can lead to cancer progression. Therefore, it is crucial that the inevitable co-existence of these fundamental, yet conflicting roles of immune-regulatory cells is carefully streamlined as imbalances can be detrimental to the host. Infection with chronic persistent viruses is characterized by severe immune dysfunction resulting in T cell exhaustion and sometimes deletion of antigen-specific T cells. More often, this is due to increased immuno-regulatory processes, which are triggered to down-regulate immune responses and limit immunopathology. However, such heightened levels of immune disruption cause a concomitant loss of tumor immune-surveillance and create a permissive microenvironment for cancer establishment and progression, as demonstrated by increased incidences of cancer in immunosuppressed hosts. Paradoxically, while some cancers arise as a consequence of increased immuno-regulatory mechanisms that inhibit protective immune responses and impinge on tumor surveillance, other cancers arise due to impaired immuno-regulatory mechanisms and failure to limit pathogenic inflammatory responses. This intricate complexity, where immuno-regulatory cells can be beneficial in certain immune settings but detrimental in other settings underscores the need for carefully formulated interventions to equilibrate the balance between immuno-stimulatory and immuno-regulatory processes.

Therapeutic potential of regulatory T cells in autoimmune disorders

Regulatory T cells (Tregs) play a dominant role in the regulation of immune responses. Quantitative and/or qualitative abnormalities of Tregs were observed in patients with autoimmune diseases and therapeutic interventions focusing Tregs are an attractive new target with the potential to cure these disorders. Biological agents approved for treatment of inflammatory rheumatic diseases transiently influence Treg prevalences and function and experimental therapies including novel biological agents, gene therapy, activation and ex vivo expansion of purified Tregs as well as substances influencing tolerogenic dendritic cells will be developed for selective Treg therapy. Although many of these interventions are effective in vitro, in animal models as well as in early clinical trials, significant concerns exist regarding the stability of Treg modifications as well as the long-term safety of Treg-based therapies.

Inhibiting cardiac allograft rejection with interleukin-35 therapy combined with decitabine treatment in mice

BACKGROUND

Regulatory T (Treg) cells play a pivotal role in the maintenance of transplantation tolerance. It is of great interest to induce allograft tolerance mediated by regulatory CD4(+)CD25(+) T cells.

METHODS

Here we investigated the effect of hydrodynamic IL-35-expressing plasmid injection in combination with a methyltransferase inhibitor (decitabine) on immune function and transplantation tolerance in mice.

RESULTS

We showed that IL-35 and decitabine stimulated the proliferation of CD4(+)CD25(+) Tregs and suppressed CD8(+) T cell proliferation in an allogenic mixed lymphocyte culture in vitro. IL-35 gene therapy and decitabine administration prolonged the survival of the transplanted heart in the heterotopic abdominal heart transplantation model in mice.

CONCLUSIONS

The possible mechanism through which IL-35 and decitabine treatment increased the survival of graft tissues is to enhance the proliferation of CD4(+)CD25(+) Treg cells and suppress the generation and function of effector T cells. Thus, IL-35 gene therapy combined with decitabine provides a novel approach to induce transplantation tolerance.

Faecalibacterium prausnitzii upregulates regulatory T cells and anti-inflammatory cytokines in treating TNBS-induced colitis

BACKGROUND AND AIMS

Faecalibacterium prausnitzii (F. prausnitzii) is a common anaerobic bacteria colonized in the human gut and inflammatory bowel disease (IBD) patients are usually lack of F. prausnitzii. The aims of this study were to evaluate the anti-inflammatory and immunomodulatory capacity of F. prausnitzii by comparing it with Bifidobacterium longum (B. longum) in both cellular and animal experiments.

METHODS

Human peripheral blood mononuclear cells (PBMCs) and 2, 4, 6-trinitrobenzenesulphonic acid (TNBS)-induced colitis rat models were treated with F. prausnitzii, B. longum, F. prausnitzii supernatant or F. prausnitzii medium, respectively. Interleukin (IL)-10, TGF-β1 and IL-12p70 in human PBMCs culture supernatant and rat blood serum were detected. The frequency of CD25(+)Foxp3(+)Treg in human PBMCs, rat PBMCs and rat splenocytes were investigated. Besides, the T-bet, GATA-3, ROR-γt and Foxp3 mRNA in human PBMCs, histopathologic characteristics of the intestinal mucosal and weight loss in the rat models were examined.

RESULTS

F. prausnitzii, B. longum and F. prausnitzii supernatant clearly facilitated the induction of IL-10 and TGF-β1, while induced relatively mild production of IL-12p70 in both cellular and animal models. The F. prausnitzii, B. longum and supernatant differed in their capacity to induce T-bet, GATA-3 and ROR-γt mRNA expression in human PBMCs (both bacterial strains inhibited the expression of ROR-γt while supernatant inhibited the T-bet and GATA-3). However, all of them induced the Foxp3 and Treg production and ameliorated the TNBS-induced colitis. In addition, F. prausnitzii supernatant exhibited the supreme anti-inflammatory capacity.

CONCLUSIONS

F. prausnitzii and its unidentified metabolites in the supernatant are promising candidates in treating IBD, and further research remains necessary to elucidate the safety, efficacy, optimum and mechanism of this bacterium in the clinical practice.

LncRNA DQ786243 affects Treg related CREB and Foxp3 expression in Crohn's disease

BACKGROUND

Long non-coding RNAs (lncRNAs) have different functions in cells. They work as signals, decoys, guides, and scaffolds. Altered lncRNA levels can affect the expression of gene products. There are seldom studies on the role of lncRNAs in inflammatory bowel disease (IBD).

RESULTS

Quantitative RT-PCR showed that DQ786243 was significantly overexpressed in clinical active CD patients compared with clinical inactive CD patients (P = 0.0118) or healthy controls (P = 0.002). CREB was also more highly expressed in active CD than in inactive CD (P = 0.0034) or controls (P = 0.0241). Foxp3 was interestingly lower in inactive CD than in active CD (P = 0.0317) or controls (P = 0.0103), but there were no apparent differences between active CD and controls. CRP was well correlated with DQ786243 (r = 0.489, P = 0.034), CREB (r = 0.500, P = 0.029) and Foxp3 (r = 0.546, P = 0.016). At 48 hours after DQ786243 transfection, qRT-PCR showed both CREB (P = 0.017) and Foxp3 (P = 0.046) had an increased mRNA expression in Jurkat cells. Western blot showed the same pattern. After DQ786243 transfection, CREB phosphorylation ratio (p-CREB/t-CREB) was increased (P = 0.0043).

CONCLUSION

DQ786243 can be related with severity of CD. It can affect the expression of CREB and Foxp3 through which regulates the function of Treg. CREB itself seems not the mediator of DQ786243 to up-regulate Foxp3. The phosphorylation of CREB might play a more important role in the process.

Distribution of CD4(pos) -, CD8(pos) - and regulatory T cells in the upper and lower gastrointestinal tract in healthy young subjects

The gastrointestinal immune system is involved in the development of several autoimmune-mediated diseases, including inflammatory bowel disease, multiple sclerosis, and type 1 diabetes mellitus. Alterations in T-cell populations, especially regulatory T cells (Tregs), are often evident in patients suffering from these diseases. To be able to detect changes in T-cell populations in diseased tissue, it is crucial to investigate T-cell populations in healthy individuals, and to characterize their variation among different regions of the gastrointestinal (GI) tract. While limited data exist, quantitative data on biopsies systematically drawn from various regions of the GI tract are lacking, particularly in healthy young humans. In this report, we present the first systematic assessment of how T cells--including Tregs--are distributed in the gastrointestinal mucosa throughout the GI tract of healthy young humans by means of multi-parameter FACS analysis. Gastroduodenoscopy and colonoscopy were performed on 16 healthy volunteers aged between 18 and 32. Biopsies were drawn from seven GI regions, and were used to determine the frequencies of CD8(+)-, CD4(+)- and Tregs in the gastrointestinal mucosa by means of multi-parameter FACS analysis. Our data show that there is significant variation in the baseline T-cell landscape along the healthy human gastrointestinal tract, and that mucosal T-cell analyses from a single region should not be taken as representative of the entire gastrointestinal tract. We show that certain T-cell subsets in the gastrointestinal mucosa vary significantly among regions; most notably, that Tregs are enriched in the appendiceal orifice region and the ascending colon, and that CD8(pos) T cells are enriched in the gastric mucosa.

TGF-β1 secreted by hepatocellular carcinoma induces the expression of the Foxp3 gene and suppresses antitumor immunity in the tumor microenvironment

AIM

The purpose of this study was to explore the mechanisms of TGF-β1 mediated immunosuppression in tumor stroma.

METHODS

The expression of TGF-β1 was investigated in Huh7, Hep 3B, SGC-7901, Eca-109 and Hepa1-6 cell lines using immunofluorescence. Knocked-down TGF-β1 of the Hepa1-6 cell line was established through lentivirus-based RNA interference. The interference efficiency of the TGF-β1 gene was tested by real-time PCR and ELISA; the expression of Foxp3, IFN-γ and CD83 in CD4(+), CD8(+) or dendritic cells was examined via flow cytometry; and the tumorigenic ability of the cancer cells was investigated in the animal experiments.

RESULTS

The diverse digestive cancer cells were found to secrete TGF-β1, mRNA of which was knocked down by 78 % thanks to lentivirus-based interference in Hepa1-6 cells. Flow cytometry showed that CD4(+)CD25(+)Foxp3(+) regulatory T cells significantly increased in hepatocellular carcinoma patients when compared with those in the healthy controls. The supernatant from Hepa1-6 cells and recombinant TGF-β1 significantly induced the expression of Foxp3 gene in vitro, while that from sh TGF-β1 Hepa1-6 cells restored it. Hepa1-6 cells inhibited IFN-γ and CD83 expression in CD8(+) or dendritic cells by secreting TGF-β1. The animal experiments indicated that the knockdown TGF-β1 gene impaired the tumorigenic ability of Hepa1-6 cells.

CONCLUSION

TGF-β1, expressed in cancer cells, might be a potential therapeutic target for cancer treatment.

Regulatory T cells in inflammatory bowel diseases and colorectal cancer

Regulatory T cells (T(regs)) are key elements in immunological self-tolerance. The number of T(regs) may alter in both peripheral blood and in colonic mucosa during pathological circumstances. The local cellular, microbiological and cytokine milieu affect immunophenotype and function of T(regs). Forkhead box P3+ T(regs) function shows altered properties in inflammatory bowel diseases (IBDs). This alteration of T(regs) function can furthermore be observed between Crohn's disease and ulcerative colitis, which may have both clinical and therapeutical consequences. Chronic mucosal inflammation may also influence T(regs) function, which together with the intestinal bacterial flora seem to have a supporting role in colitis-associated colorectal carcinogenesis. T(regs) have a crucial role in the immunoevasion of cancer cells in sporadic colorectal cancer. Furthermore, their number and phenotype correlate closely with the clinical outcome of the disease, even if their contribution to carcinogenesis has previously been controversial. Despite knowledge of the clinical relationship between IBD and colitis-associated colon cancer, and the growing number of immunological aspects encompassing sporadic colorectal carcinogenesis, the molecular and cellular links amongst T(regs), regulation of the inflammation, and cancer development are still not well understood. In this paper, we aimed to review the current data surrounding the role of T(regs) in the pathogenesis of IBD, colitis-associated colon cancer and sporadic colorectal cancer.

Regulatory T cells in HIV infection: can immunotherapy regulate the regulator?

Regulatory T cells (Tregs) have a dominant role in self-tolerance and control of autoimmune diseases. These cells also play a pivotal role in chronic viral infections and cancer by limiting immune activation and specific immune response. The role of Tregs in HIV pathogenesis remains poorly understood as their function, changes according to the phases of infection. Tregs can suppress anti-HIV specific responses and conversely can have a beneficial role by reducing the deleterious impact of immune activation. We review the frequency, function and homing potential of Tregs in the blood and lymphoid tissues as well as their interaction with dendritic cells in the context of HIV infection. We also examine the new insights generated by recombinant IL-2 and IL-7 clinical trials in HIV-infected adults, including the immunomodulatory effects of Tregs. Based on their detrimental role in limiting anti-HIV responses, we propose Tregs as potential targets for immunotherapeutic strategies aimed at decreasing Tregs frequency and/or immunosuppressive function. However, such approaches require a better understanding of the time upon infection when interfering with Treg function may not cause a deleterious state of hyperimmune activation.

Interleukin (IL)-23 suppresses IL-10 in inflammatory bowel disease

Interleukin (IL)-10 plays an important role in immune regulation in the intestine. Immune deregulation is suggested in the pathogenesis of inflammatory bowel disease (IBD). This study aims to elucidate the role of IL-23 in the suppression of IL-10 in the IBD intestinal mucosa. Surgically removed colon specimens were obtained from 16 IBD patients. The expressions of IL-10, IL-23, and IgA in the specimens were examined at the protein and gene transcriptional levels. The gene transcription of IL-10 was assessed by chromatin immunoprecipitation assay and promoter accessibility assay. The levels of IgA and IL-10 were significantly lower, whereas the levels of IL-23 were higher, in IBD specimens than in normal controls. The levels of IgA and IL-10 were negatively correlated with the infiltration of inflammatory cells in the IBD mucosa. The production of IL-10 by lamina propria mononuclear cells was lower in the IBD group than in the control group, and these levels could be enhanced by blocking IL-23. The gene transcription of IL-10 was significantly suppressed in CD4(+) T cells of IBD mucosa; this phenomenon could be replicated in vitro by adding IL-23 in the culture of polarized Th2 cells. Overexpression of IL-23 in the intestinal mucosa suppresses the production of IL-10, which weakens the defensive barrier by reducing the production of IgA in the gut.