Regulatory T cells in inflammatory bowel disease

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.

Slc5a8, a Na+-coupled high-affinity transporter for short-chain fatty acids, is a conditional tumour suppressor in colon that protects against colitis and colon cancer under low-fibre dietary conditions

Mammalian colon harbours trillions of bacteria under physiological conditions; this symbiosis is made possible because of a tolerized response from the mucosal immune system. The mechanisms underlying this tolerogenic phenomenon remain poorly understood. In the present study we show that Slc5a8 (solute carrier gene family 5a, member 8), a Na(+)-coupled high-affinity transporter in colon for the bacterial fermentation product butyrate, plays a critical role in this process. Among various immune cells in colon, dendritic cells (DCs) are unique not only in their accessibility to luminal contents but also in their ability to induce tolerogenic phenotype in T-cells. We found that DCs exposed to butyrate express the immunosuppressive enzymes indoleamine 2,3-dioxygenase 1 (IDO1) and aldehyde dehydrogenase 1A2 (Aldh1A2), promote conversion of naive T-cells into immunosuppressive forkhead box P3(+) (FoxP3(+)) Tregs (regulatory T-cells) and suppress conversion of naive T-cells into pro-inflammatory interferon (IFN)-γ-producing cells. Slc5a8-null DCs do not induce IDO1 and Aldh1A2 and do not generate Tregs or suppress IFN-γ-producing T-cells in response to butyrate. We also provide in vivo evidence for an obligatory role for Slc5a8 in suppression of IFN-γ-producing T-cells. Furthermore, Slc5a8 protects against colitis and colon cancer under conditions of low-fibre intake but not when dietary fibre intake is optimal. This agrees with the high-affinity nature of the transporter to mediate butyrate entry into cells. We conclude that Slc5a8 is an obligatory link between dietary fibre and mucosal immune system via the bacterial metabolite butyrate and that this transporter is a conditional tumour suppressor in colon linked to dietary fibre content.

Genome-wide gene expression analysis for target genes to differentiate patients with intestinal tuberculosis and Crohn's disease and discriminative value of FOXP3 mRNA expression

BACKGROUND AND AIMS

Crohn's disease (CD) and intestinal tuberculosis (ITB) are both chronic granulomatous conditions with similar phenotypic presentations. Hence, there is need for a biomarker to differentiate between both these two diseases. This study aimed at genome-wide gene expression analysis of colonic biopsies from confirmed cases of ITB and CD in comparison with controls. To evaluate the role of T regulatory cells, forkhead box P3 (FOXP3) mRNA expression was quantified in serum as well as in colonic biopsies from patients with ITB and with the controls.

METHODS

Paired samples, including serum and colonic biopsies, were taken from 33 study subjects (CD, ITB and controls), and total RNA was extracted. Human whole genome gene expression microarray analysis was performed using the Illumina HumanWG-6 BeadChip Kit with six total RNA samples of the three groups in duplicates. Real-time PCR for FOXP3 mRNA expression was analyzed in serum samples and colonic biopsy samples (4-CD, 5-ITB, 4-controls).

RESULTS

In CD and ITB there was 1.5-fold upregulation of 92 and 382 genes and 1.5-fold downregulation of 91 and 256 genes, respectively. Peroxisome proliferators via the PPARγ pathway were most significantly downregulated (P < 0.005) in CD. Additionally, the IL4/5/6 signaling pathways and Toll-like receptor signaling pathway were identified as significantly differentially regulated (P < 0.005) at > 2-fold change. In ITB, the complement activation pathway, specifically the classical pathway, was the most significantly upregulated. FOXP3 mRNA expression was significantly elevated in colonic biopsies obtained from ITB patients as compared with CD cases (4.70 ± 2.21 vs 1.48 ± 0.31, P = 0.016).

CONCLUSIONS

FOXP3 mRNA expression in colonic mucosa could be a discriminatory marker between ITB and CD. Upregulation of the complement activation pathway in ITB suggests that pathogenetic mechanisms for ITB are similar to those of pulmonary tuberculosis. In CD, downregulation of PPARγ was seen in colonic tissue, suggesting that restoration of PPARγ-dependent anti-microbial barrier function may be a therapeutic target.

The magic of magic bugs in oral cavity: Probiotics

The aim of this review is to present an update about the current status of probiotics in the field of dentistry. Oral infections are the most common forms of infections. It is necessary to understand the role of the ecology and microbiology of the oral cavity in better understanding of the pathogenesis of various oral diseases. The concept of bacteriotherapy has been an emerging field in dentistry. The use of health-beneficial micro-organisms to heal diseases or support immune function was first introduced in the beginning of the 20^th century. Probiotics are dietary supplements containing potentially beneficial bacteria or yeasts and it has been found to be beneficial to the host health. In medicine, probiotics are used mainly in support therapy for gastro-intestinal diseases. In recent years, probiotics have been used as a treatment to promote oral health. This approach has shown promising results in the oral cavity with respect to control of chronic diseases such as dental caries, periodontitis, and recurring problems such as halitosis and candidal infections. Despite the immense potential of probiotics, data are still deficient on the probiotic action in the oral cavity, which further mandates randomized trials before any concrete clinical recommendations can be arrived.

Central role of gimap5 in maintaining peripheral tolerance and T cell homeostasis in the gut

Inflammatory bowel disease (IBD) including Crohn's disease and ulcerative colitis is often precipitated by an abnormal immune response to microbiota due to host genetic aberrancies. Recent studies highlight the importance of the host genome and microflora interactions in the pathogenesis of mucosal inflammation including IBD. Specifically, genome-wide (GWAS) and also next-generation sequencing (NGS)—including whole exome or genome sequencing—have uncovered a large number of susceptibility loci that predispose to autoimmune diseases and/or the two phenotypes of IBD. In addition, the generation of “IBD-prone” animal models using both reverse and forward genetic approaches has not only helped confirm the identification of susceptibility loci but also shed critical insight into the underlying molecular and cellular pathways that drive colitis development. In this review, we summarize recent findings derived from studies involving a novel early-onset model of colitis as it develops in GTPase of immunity-associated protein 5- (Gimap5-) deficient mice. In humans, GIMAP5 has been associated with autoimmune diseases although its function is poorly defined. Here, we discuss how defects in Gimap5 function impair immunological tolerance and lymphocyte survival and ultimately drive the development of CD4⁺ T cell-mediated early-onset colitis.

Retinoic acid primes human dendritic cells to induce gut-homing, IL-10-producing regulatory T cells

The vitamin A metabolite all-trans retinoic acid (RA) is an important determinant of intestinal immunity. RA primes dendritic cells (DCs) to express CD103 and produce RA themselves, which induces the gut-homing receptors α4β7 and CCR9 on T cells and amplifies transforming growth factor (TGF)-β-mediated development of Foxp3(+) regulatory T (Treg) cells. Here we investigated the effect of RA on human DCs and subsequent development of T cells. We report a novel role of RA in immune regulation by showing that RA-conditioned human DCs did not substantially enhance Foxp3 but induced α4β7(+) CCR9(+) T cells expressing high levels of interleukin (IL)-10, which were functional suppressive Treg cells. IL-10 production was dependent on DC-derived RA and was maintained when DCs were stimulated with toll-like receptor ligands. Furthermore, the presence of TGF-β during RA-DC-driven T-cell priming favored the induction of Foxp3(+) Treg cells over IL-10(+) Treg cells. Experiments with naive CD4(+) T cells stimulated by anti-CD3 and anti-CD28 antibodies in the absence of DCs emphasized that RA induces IL-10 in face of inflammatory mediators. The data thus show for the first time that RA induces IL-10-producing Treg cells and postulates a novel mechanism for IL-10 in maintaining tolerance to the intestinal microbiome.

A potential role for regulatory T-cells in the amelioration of DSS induced colitis by dietary non-digestible polysaccharides

Inflammatory bowel diseases (IBD) including ulcerative colitis (UC) and Crohn's disease (CD) are chronic relapsing inflammatory disorders of the gastrointestinal tract. The interaction between a disturbed microbial composition, the intestinal mucosal barrier and the mucosal immune system plays an important role in IBD and its chronicity. It has been indicated that due to the altered microbial composition the balance between T regulatory cells (Treg) and T helper cells (Th) 17 is disturbed, leading to an inflammatory state. The present study shows that oral intake of a specific multi fibre mix (MF), designed to match the fibre content of a healthy diet, counteracts IBD-like intestinal inflammation and weight loss in dextran sodium sulphate treated mice. This reduction in inflammation might be brought about, at least in part, by the MF-induced decrease in inflammatory cytokines, increase in IL-10 and the relative increase in Treg cells in the mesenteric lymph nodes (MLN). Moreover, the Treg percentage in the MLN correlates with the percentage of tolerogenic lamina propria derived CD103+RALDH+dendritic cells in the MLN, suggesting that these play a role in the observed effects. In children with CD exclusive enteral nutrition (EEN) is a widely used safe and effective therapy. Optimizing enteral nutritional concepts with the tested fibre mix, know to modulate the gut microbiota composition, SCFA production and inflammatory status (as indicated by the present study) could possibly further improve efficacy in inducing remission.

Generation and characterization of small single domain antibodies inhibiting human tumor necrosis factor receptor 1

The cytokine TNF is a well known drug target for several inflammatory diseases such as Crohn disease. Despite the great success of TNF blockers, therapy could be improved because of high costs and side effects. Selective inhibition of TNF receptor (TNFR) 1 signaling holds the potential to greatly reduce the pro-inflammatory activity of TNF, thereby preserving the advantageous immunomodulatory signals mediated by TNFR2. We generated a selective human TNFR1 inhibitor based on Nanobody (Nb) technology. Two anti-human TNFR1 Nbs were linked with an anti-albumin Nb to generate Nb Alb-70-96 named "TNF Receptor-One Silencer" (TROS). TROS selectively binds and inhibits TNF/TNFR1 and lymphotoxin-α/TNFR1 signaling with good affinity and IC50 values, both of which are in the nanomolar range. Surface plasmon resonance analysis reveals that TROS competes with TNF for binding to human TNFR1. In HEK293T cells, TROS strongly reduces TNF-induced gene expression, like IL8 and TNF, in a dose-dependent manner; and in ex vivo cultured colon biopsies of CD patients, TROS inhibits inflammation. Finally, in liver chimeric humanized mice, TROS antagonizes inflammation in a model of acute TNF-induced liver inflammation, reflected in reduced human IL8 expression in liver and reduced IL6 levels in serum. These results demonstrate the considerable potential of TROS and justify the evaluation of TROS in relevant disease animal models of both acute and chronic inflammation and eventually in patients.

Profound loss of intestinal Tregs in acutely SIV-infected neonatal macaques

Impairment of the intestinal mucosal immune system is an early feature of HIV-infected children. Most infected children exhibit clinical gastrointestinal symptoms at some stage of infection, and persistent diarrhea is a marker for rapid disease progression. It is known that Tregs are especially important in mediating intestinal immune homeostasis and that loss of this subset may result in intestinal inflammation and associated clinical signs. Large numbers of FoxP3(+) T cells were found in all tissues in newborn macaques, which coexpressed high levels of CD25 and CD4, indicating that they were Tregs. Moreover, neonates had much greater percentages of Tregs in intestinal tissues compared with peripheral lymphoid tissues. After SIV infection, a significant loss of Tregs was detected in the intestine compared with age-matched normal infants. Finally, SIV-infected FoxP3(+) T cells were detected in tissues in neonates as early as 7 SIV dpi. These results demonstrate that Tregs constitute a significant fraction of CD4(+) T cells in neonatal intestinal tissues and that an early, profound loss of Tregs occurs in acute SIV infection, which may contribute to the intestinal disorders associated with neonatal HIV infection.

Inherited BCL10 deficiency impairs hematopoietic and nonhematopoietic immunity

Heterotrimers composed of B cell CLL/lymphoma 10 (BCL10), mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1), and caspase recruitment domain-containing (CARD) family adaptors play a role in NF-κB activation and have been shown to be involved in both the innate and the adaptive arms of immunity in murine models. Moreover, individuals with inherited defects of MALT1, CARD9, and CARD11 present with immunological and clinical phenotypes. Here, we characterized a case of autosomal-recessive, complete BCL10 deficiency in a child with a broad immunodeficiency, including defects of both hematopoietic and nonhematopoietic immunity. The patient died at 3 years of age and was homozygous for a loss-of-expression, loss-of-function BCL10 mutation. The effect of BCL10 deficiency was dependent on the signaling pathway, and, for some pathways, the cell type affected. Despite the noted similarities to BCL10 deficiency in mice, including a deficient adaptive immune response, human BCL10 deficiency in this patient resulted in a number of specific features within cell populations. Treatment of the patient's myeloid cells with a variety of pathogen-associated molecular pattern molecules (PAMPs) elicited a normal response; however, NF-κB-mediated fibroblast functions were dramatically impaired. The results of this study indicate that inherited BCL10 deficiency should be considered in patients with combined immunodeficiency with B cell, T cell, and fibroblast defects.

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.

Influence of host immunoregulatory genes, ER stress and gut microbiota on the shared pathogenesis of inflammatory bowel disease and Type 1 diabetes

Inflammatory bowel disease (IBD) with its two distinct entities, Crohn's disease and ulcerative colitis, and Type 1 diabetes mellitus (T1D) are autoimmune diseases. The prevalence of these diseases continues to rapidly rise in the industrialized world. Despite the identification of several genetic loci that are associated with both IBD and T1D, thus far, there is a paucity of epidemiological data to support a clinical overlap. In an effort to better understand the underlying pathogenic mechanisms of both IBD and T1D, this review summarizes the literature about these related autoimmune diseases, describes the most recent advances in their etiopathogenesis and emphasizes the genetic and nongenetic factors that exercise a differential influence. Genome-wide association studies have identified genetic loci with a role in immune response regulation that are linked to both IBD (particularly Crohn's disease) and T1D. Some of these genetic loci (e.g., IL-18RAP) have a divergent role, conferring risk for one disease and protection for the other. Recent evidence highlights an important role of gut microbiota and cellular responses (e.g., endoplasmic reticulum stress) in the pathogenesis of both IBD and T1D.

Bacterial β-(1,3)-glucan prevents DSS-induced IBD by restoring the reduced population of regulatory T cells

Bacterial β-(1,3)-glucan has more advantages in terms of cost, yield and efficiency than that derived from mushrooms, plants, yeasts and fungi. We have previously developed a novel and high-yield β-(1,3)-glucan produced by Agrobacterium sp. R259. This study aimed to elucidate the functional mechanism and therapeutic efficacy of bacterial β-(1,3)-glucan in dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD).Mice were orally pretreated with bacterial β-(1,3)-glucan at daily doses of 2.5 or 5mg/kg for 2 weeks. After 6 days of DSS treatment, clinical assessment of IBD severity and expression of pro-inflammatory cytokines were evaluated. In vivo cell proliferation was examined by immunohistochemistry using Ki-67 and ER-TR7 antibodies. The frequency of regulatory T cells (Tregs) was analyzed by flow cytometry. Natural killer (NK) activity and IgA level were evaluated using NK cytotoxicity assay and ELISA.The deterioration of body weight gain, colonic architecture, disease score and histological score was recovered in DSS-induced IBD mice when pretreated with bacterial β-(1,3)-glucan. The recruitment of macrophages and the gene expression of proinflammatory cytokines, such as IL-1β, IL-6 and IL-17A/F, were markedly decreased in the colon of β-(1,3)-glucan-pretreated mice. β-(1,3)-Glucan induced the recovery of Tregs in terms of their frequency in DSS-induced IBD mice. Intriguingly, β-(1,3)-glucan reversed the functional defects of NK cells and excessive IgA production in DSS-induced IBD mice.We conclude that bacterial β-(1,3)-glucan prevented the progression of DSS-induced IBD by recovering the reduction of Tregs, functional defect of NK cells and excessive IgA production.

Oral administration of bovine milk from cows hyperimmunized with intestinal bacterin stimulates lamina propria T lymphocytes to produce Th1-biased cytokines in mice

The goal of this study was to examine the effects of oral administration of bovine milk from cows hyperimmunized with a proprietary bacterin (immune milk “Sustaina”) on mucosal immunity in the intestine of adult mice. C57BL/6 mice were orally given immune or control milk for two weeks, and then lymphocyte population and the cytokine production in lamina propria of colon in normal mice and mice induced colitis by dextran sulphate sodium (DSS) were detected. We found that the levels of IFN-γ and IL-10 increased, but the levels of IL-17A and IL-4, decreased in lamina propria of colon in immune milk-fed mice as compared with those in control milk-fed mice. Interestingly, oral administration of immune milk partially improved the acute colitis induced by DSS. The levels of TNF-α and IFN-γ increased, but IL-6, IL-17A and IL-4 decreased in lamina propria (LP) of colon in immune milk-fed mice with DSS-induced colitis. Our results suggest that immune milk may stimulate CD4⁺ T cells to polarize towards a Th1 type response, but contrarily suppress Th17 and Th2 cells responses in large intestinal LP of mice. The results indicate that this kind of immune milk has is able to promote the maintainance of intestinal homeostasis and enhance protection against infection, and could alleviate the symptoms of acute colitis in mice.

Effects of dietary glutamine on the homeostasis of CD4+ T cells in mice with dextran sulfate sodium-induced acute colitis

This study investigated the effects of dietary glutamine (Gln) on T-helper (Th) and T regulatory (Treg) cell homeostasis and colonic inflammatory mediator expression in mice with dextran sulfate sodium (DSS)-induced colitis. Mice were randomly assigned to 4 groups with 2 normal control (C and G) and 2 DSS-treated groups (DC and DG). The C and DC groups were fed a common semipurified diet, while the G and DG groups received an identical diet except that part of the casein was replaced by Gln, which provided 25% of the total amino acid nitrogen. Mice were fed the diets for 10 days. On day 6, mice in the normal control groups were given distilled water, while those in the DSS groups were given distilled water containing 1.5% DSS for 5 d. At the end of the experiment, the mice were sacrificed for further examination. Results showed that DC group had higher plasma haptoglobin, colonic weight, immunoglobulin G, inflammatory cytokine and nuclear factor (NF)-κB protein levels. Gln administration lowered inflammatory mediators and NF-κB/IκBα ratio in colitis. Compared with the DC group, the percentages of interleukin-17F and interferon-γ in blood and transcription factors, T-bet and RAR-related orphan receptor-γt, gene expressions in mesenteric lymph nodes were lower, whereas blood Foxp3 was higher in the DG group. Also, DG group had lower colon injury score. These results suggest that Gln administration suppressed Th1/Th17 and Th-associated cytokine expressions and upregulated the expression of Tregs, which may modulate the balance of Th/Treg and reduce inflammatory reactions in DSS-induced colitis.

FoxP3⁺ regulatory T cells attenuate experimental necrotizing enterocolitis

Necrotizing enterocolitis (NEC) results from severe intestinal inflammation in premature infants. FoxP3(+) regulatory T cells (Tregs) are central to gut homeostasis. While Treg proportions are significantly reduced in the ileums of premature infants with NEC, it is unknown whether they play a critical function in preventing NEC. This study investigated Treg development in newborn rat pups and their role in experimental NEC induction. Utilizing an established rat model of experimental NEC, the ontogeny of T cells and Tregs in newborn pups was characterized by flow cytometry. To investigate the functions of Tregs, newborn pups were given Tregs harvested from adult rats prior to NEC induction to assess clinical improvement and mechanisms of immune regulation. The results revealed that there were few Treg numbers in the terminal ileums of newborn rats and 8-fold reduction after NEC. Adoptive transfer of Tregs significantly improved weight loss, survival from 53% to 88%, and NEC incidence from 87% to 35%. The Tregs modulated the immune response as manifested in reduced CD80 expression on antigen presenting cells and decreased T cell activation within the mesenteric lymph nodes. These findings suggest that while Tregs are present in the intestines, their numbers might be insufficient to dampen the excessive inflammatory state in NEC. Adoptive transfer of Tregs attenuates the severity of NEC by limiting the immune response. Strategies to enhance Tregs have a therapeutic potential in controlling the development of NEC.

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.

Heligmosomoides polygyrus bakeri infection activates colonic Foxp3+ T cells enhancing their capacity to prevent colitis

Helminthic infections protect mice from colitis in murine models of inflammatory bowel disease and also may protect people. Helminths like Heligmosomoides polygyrus bakeri can induce regulatory T cells (Treg). Experiments explored whether H. polygyrus bakeri infection could protect mice from colitis through activation of colonic Treg and examined mechanisms of action. We showed that H. polygyrus bakeri infection increased the number of T cells expressing Foxp3 in the colon. More importantly, Foxp3(+)/IL-10(-) and Foxp3(+)/IL-10(+) T cell subsets isolated from the colon of H. polygyrus bakeri-infected mice prevented colitis when adoptively transferred into a murine model of inflammatory bowel disease, whereas Treg from uninfected mice could not provide protection. Only the transferred colonic Foxp3(+)/IL-10(-) T cells from H. polygyrus bakeri-infected mice readily accumulated in the colon and mesenteric lymph nodes of recipient mice, and they reconstituted the Foxp3(+)/IL-10(-) and Foxp3(+)/IL-10(+) T cell subsets. However, transferred Foxp3(+)/IL-10(+) T cells disappeared. IL-10 expression by Foxp3(+) T cells was necessary for colitis prevention. Thus, H. polygyrus bakeri infection activates colonic Foxp3(+) T cells, making them highly regulatory. The Foxp3(+) T cells that fail to express IL-10 may be critical for populating the colon with the Foxp3(+)/IL-10(+) T cells, which are required to control colitis.

Modulation of immune function by polyphenols: possible contribution of epigenetic factors

Several biological activities have been described for polyphenolic compounds, including a modulator effect on the immune system. The effects of these biologically active compounds on the immune system are associated to processes as differentiation and activation of immune cells. Among the mechanisms associated to immune regulation are epigenetic modifications as DNA methylation of regulatory sequences, histone modifications and posttranscriptional repression by microRNAs that influences the gene expression of key players involved in the immune response. Considering that polyphenols are able to regulate the immune function and has been also demonstrated an effect on epigenetic mechanisms, it is possible to hypothesize that there exists a mediator role of epigenetic mechanisms in the modulation of the immune response by polyphenols.

Reishi Protein LZ-8 Induces FOXP3(+) Treg Expansion via a CD45-Dependent Signaling Pathway and Alleviates Acute Intestinal Inflammation in Mice

LZ-8, an immunomodulatory protein isolated from Ganoderma lucidum (also known as Ling-Zhi or Reishi), has been shown to promote cell proliferation and IL-2 production in T cells. In this study, we show that LZ-8 induces the expansion of both murine and human CD4⁺ T cells into FOXP3⁺ regulatory T (Treg) cells. LZ-8 treatment was found to stimulate a 4-fold and a 10-fold expansion in the Treg populations of murine and human primary CD4⁺ T cells, respectively. In addition, the expression of CTLA-4 and IL-10 was induced in LZ-8-treated CD4⁺ T cells. Using neutralizing antibodies and gene-deficient T-cell lines, we also found that LZ-8 promotes Treg expansion through a CD45-mediated signaling pathway and that the CD18-dependent induction of IL-2 was involved in Treg formation and IL-10 production. The suppressive activity of LZ-8 was confirmed using a murine model of DSS-induced colitis; the disease was alleviated by the adoptive transfer of LZ-8-treated CD4⁺ T cells. In conclusion, a new regulatory function for LZ-8 was identified, and the molecular mechanisms underlying this function were elucidated.

High beta-palmitate fat controls the intestinal inflammatory response and limits intestinal damage in mucin Muc2 deficient mice

BACKGROUND

Palmitic-acid esterified to the sn-1,3 positions of the glycerol backbone (alpha, alpha'-palmitate), the predominant palmitate conformation in regular infant formula fat, is poorly absorbed and might cause abdominal discomfort. In contrast, palmitic-acid esterified to the sn-2 position (beta-palmitate), the main palmitate conformation in human milk fat, is well absorbed. The aim of the present study was to examine the influence of high alpha, alpha'-palmitate fat (HAPF) diet and high beta-palmitate fat (HBPF) diet on colitis development in Muc2 deficient (Muc2(-/-)) mice, a well-described animal model for spontaneous enterocolitis due to the lack of a protective mucus layer.

METHODS

Muc2(-/-) mice received AIN-93G reference diet, HAPF diet or HBPF diet for 5 weeks after weaning. Clinical symptoms, intestinal morphology and inflammation in the distal colon were analyzed.

RESULTS

Both HBPF diet and AIN-93G diet limited the extent of intestinal erosions and morphological damage in Muc2(-/-) mice compared with HAPF diet. In addition, the immunosuppressive regulatory T (Treg) cell response as demonstrated by the up-regulation of Foxp3, Tgfb1 and Ebi3 gene expression levels was enhanced by HBPF diet compared with AIN-93G and HAPF diets. HBPF diet also increased the gene expression of Pparg and enzymatic antioxidants (Sod1, Sod3 and Gpx1), genes all reported to be involved in promoting an immunosuppressive Treg cell response and to protect against colitis.

CONCLUSIONS

This study shows for the first time that HBPF diet limits the intestinal mucosal damage and controls the inflammatory response in Muc2(-/-) mice by inducing an immunosuppressive Treg cell response.

Multifactorial patterns of gene expression in colonic epithelial cells predict disease phenotypes in experimental colitis

BACKGROUND

The pathogenesis of inflammatory bowel disease (IBD) is complex and the need to identify molecular biomarkers is critical. Epithelial cells play a central role in maintaining intestinal homeostasis. We previously identified five "signature" biomarkers in colonic epithelial cells (CEC) that are predictive of disease phenotype in Crohn's disease. Here we investigate the ability of CEC biomarkers to define the mechanism and severity of intestinal inflammation.

METHODS

We analyzed the expression of RelA, A20, pIgR, tumor necrosis factor (TNF), and macrophage inflammatory protein (MIP)-2 in CEC of mice with dextran sodium sulfate (DSS) acute colitis or T-cell-mediated chronic colitis. Factor analysis was used to combine the five biomarkers into two multifactorial principal components (PCs). PC scores for individual mice were correlated with disease severity.

RESULTS

For both colitis models, PC1 was strongly weighted toward RelA, A20, and pIgR, and PC2 was strongly weighted toward TNF and MIP-2, while the contributions of other biomarkers varied depending on the etiology of inflammation. Disease severity was correlated with elevated PC2 scores in DSS colitis and reduced PC1 scores in T-cell transfer colitis. Downregulation of pIgR was a common feature observed in both colitis models and was associated with altered cellular localization of pIgR and failure to transport IgA.

CONCLUSIONS

A multifactorial analysis of epithelial gene expression may be more informative than examining single gene responses in IBD. These results provide insight into the homeostatic and proinflammatory functions of CEC in IBD pathogenesis and suggest that biomarker analysis could be useful for evaluating therapeutic options for IBD patients.

Deletion of Foxp3+ regulatory T cells in genetically targeted mice supports development of intestinal inflammation

BACKGROUND

Mice lacking Foxp3+ regulatory T (Treg) cells develop severe tissue inflammation in lung, skin, and liver with premature death, whereas the intestine remains uninflamed. This study aims to demonstrate the importance of Foxp3+ Treg for the activation of T cells and the development of intestinal inflammation.

METHODS

Foxp3-GFP-DTR (human diphtheria toxin receptor) C57BL/6 mice allow elimination of Foxp3+ Treg by treatment with Dx (diphtheria toxin). The influence of Foxp3+ Treg on intestinal inflammation was tested using the CD4+ T-cell transfer colitis model in Rag-/- C57BL/6 mice and the acute DSS-colitis model.

RESULTS

Continuous depletion of Foxp3+ Treg in Foxp3-GFP-DTR mice led to dramatic weight loss and death of mice by day 28. After 10 days of depletion of Foxp3+ Treg, isolated CD4+ T-cells were activated and produced extensive amounts of IFN-γ, IL-13, and IL-17A. Transfer of total CD4+ T-cells isolated from Foxp3-GFP-DTR mice did not result in any changes of intestinal homeostasis in Rag-/- C57BL/6 mice. However, administration of DTx between days 14 and 18 after T-cell reconstitution, lead to elimination of Foxp3+ Treg and to immediate weight loss due to intestinal inflammation. This pro-inflammatory effect of Foxp3+ Treg depletion consecutively increased inflammatory cytokine production. Further, the depletion of Foxp3+ Treg from Foxp3-GFP-DTR mice increased the severity of acute dSS-colitis accompanied by 80% lethality of Treg-depleted mice. CD4+ effector T-cells from Foxp3+ Treg-depleted mice produced significantly more pro-inflammatory cytokines.

CONCLUSION

Intermittent depletion of Foxp3+ Treg aggravates intestinal inflammatory responses demonstrating the importance of Foxp3+ Treg for the balance at the mucosal surface of the intestine.

Inhibition of Pim-1 kinase ameliorates dextran sodium sulfate-induced colitis in mice

BACKGROUND

Pim-1 kinase is involved in the control of cell growth, differentiation and apoptosis. Recent evidence suggests that Pim kinases play a role in immune regulation and inflammation. However, the role of Pim-1 kinase in inflammatory bowel diseases (IBD) remains unclear.

AIMS

The aims of this study were to explore the role of Pim-1 kinase in the pathology of IBD and to assess whether inhibiting Pim-1 kinase may be of therapeutic benefit as a treatment regimen for IBD.

METHODS

Colitic mouse model was established by the induction of dextran sodium sulfate. The expression of Pim-1 in the colonic samples of control and colitic mice was examined. Furthermore, the mice were treated with Pim-1inhibitor (PIM-Inh), then the body weight and colon inflammation were evaluated, and the production of cytokines including IFN-γ, IL-4, TGF-β and IL-17 in colon tissues was determined by ELISA. The expression of T cell master transcription factors T-bet, ROR-γt, GATA-3 and Foxp3 and Nuclear factor κB (NF-κB) and inducible nitric oxide synthase in colon tissues was detected by real-time PCR and western blot. Finally, the effect of LPS on Pim-1 expression and the effects of PIM-Inh on LPS-induced upregualtion of p65 and TNF-α in RAW264.7 cells were examined by real-time PCR and western blot.

RESULTS

Pim-1 expression was correlated with the degree of mucosal inflammation in vivo, and it was significantly induced by LPS in vitro. PIM-Inh had protective effects on acute colitis in vivo. Mechanistically, PIM-Inh reduced the proinflammatory immune response through the inhibition of the overactivation of macrophages and the down-regulation of excessive Th1- and Th17-type immune responses. Furthermore, PIM-Inh could skew T cell differentiation towards a Treg phenotype.

CONCLUSIONS

Pim-1 kinase is involved in mucosal injury/inflammation and Pim-1 kinase inhibitor may provide a novel therapeutic approach for IBD.

Oral lichen planus as a preneoplastic inflammatory model

Oral lichen planus (OLP) is a chronic oral inflammatory disease of unknown etiology. According to reports, 1-2% of OLP patients develop oral squamous cell carcinoma (OSCC) in the long run. While World Health Organization (WHO) classifies OLP as “a potentially malignant disorder,” it is still a matter of debate which mechanisms drive OLP to such a condition. The current hypothesis connecting OLP and OSCC is that chronic inflammation results in crucial DNA damage which over time results in cancer development. Initial studies investigating the OLP and OSCC link were mainly retrospective clinical studies. Over the past years, several amount of information has accumulated, mainly from molecular studies on the OLP malignant potential. This article is a critical review of whether OLP has a malignant potential and, therefore, represents a model of preneoplastic inflammation.

Prophylactic effects of Lonicera japonica extract on dextran sulphate sodium-induced colitis in a mouse model by the inhibition of the Th1/Th17 response

Inflammatory bowel diseases (IBD) are chronically relapsing inflammatory disorders of the intestine. Although some therapeutic agents, including steroids, are available for the treatment of IBD, these agents have limited use. Therefore, dietary supplements have emerged as possible interventions for IBD. Japanese honeysuckle flower, the flower of Lonicera japonica, is a well-known dietary supplement and has been used to prevent or treat various inflammatory diseases. In the present study, we investigated the effects of L. japonica on experimental murine colitis. Colitis was induced by 5 % dextran sulphate sodium (DSS) in Balb/c mice. The water extract of L. japonica (LJE) at doses of 20, 100 or 500 mg/kg was orally administered to mice twice per day for 7 d. Body weight, colon length and a histological damage score were assessed to determine the effects on colitis. Cytokine profiles were assessed to examine the effects on helper T (Th) cell-related immunological responses. In addition, CD4+CD25+Foxp3+T cells were analysed in vivo and in vitro for investigating the effects on regulatory T (Treg) cells. LJE showed dose-dependent inhibitory effects against colon shortening, weight loss and histological damage. LJE down-regulated IL-1β, TNF-α, interferon-γ, IL-6, IL-12 and IL-17. However, LJE did not show any significant effects on IL-10, IL-23, transforming growth factor-β1 and Treg cell populations. In conclusion, LJE showed protective effects against DSS-induced colitis via the Th1/Th17 pathway and not via Treg cell-related mechanisms.

Computational modeling-based discovery of novel classes of anti-inflammatory drugs that target lanthionine synthetase C-like protein 2

Background

Lanthionine synthetase component C-like protein 2 (LANCL2) is a member of the eukaryotic lanthionine synthetase component C-Like protein family involved in signal transduction and insulin sensitization. Recently, LANCL2 is a target for the binding and signaling of abscisic acid (ABA), a plant hormone with anti-diabetic and anti-inflammatory effects.

Methodology/Principal Findings

The goal of this study was to determine the role of LANCL2 as a potential therapeutic target for developing novel drugs and nutraceuticals against inflammatory diseases. Previously, we performed homology modeling to construct a three-dimensional structure of LANCL2 using the crystal structure of lanthionine synthetase component C-like protein 1 (LANCL1) as a template. Using this model, structure-based virtual screening was performed using compounds from NCI (National Cancer Institute) Diversity Set II, ChemBridge, ZINC natural products, and FDA-approved drugs databases. Several potential ligands were identified using molecular docking. In order to validate the anti-inflammatory efficacy of the top ranked compound (NSC61610) in the NCI Diversity Set II, a series of in vitro and pre-clinical efficacy studies were performed using a mouse model of dextran sodium sulfate (DSS)-induced colitis. Our findings showed that the lead compound, NSC61610, activated peroxisome proliferator-activated receptor gamma in a LANCL2- and adenylate cyclase/cAMP dependent manner in vitro and ameliorated experimental colitis by down-modulating colonic inflammatory gene expression and favoring regulatory T cell responses.

Conclusions/Significance

LANCL2 is a novel therapeutic target for inflammatory diseases. High-throughput, structure-based virtual screening is an effective computational-based drug design method for discovering anti-inflammatory LANCL2-based drug candidates.

HIF-1 in T cells ameliorated dextran sodium sulfate-induced murine colitis

HIF-1 is active in hypoxia, such as inflamed mucosa, and HIF-1 in epithelium has been reported to control inflamed mucosa in IBD models. Although T cells play an important role for pathogenesis of IBD, the function of HIF-1 in T cells remains to be elucidated. We aimed to clarify the function of HIF-1 in T cells in IBD with focus on the balance between Treg and Teff. Double immunohistochemistry of colonic mucosa in IBD patients showed that HIF-1 was expressed in T cells infiltrating the inflamed mucosa, suggesting that HIF-1 in T cells is involved in the pathogenesis. DSS administration to T cell-specific HIF-1α KO mice showed more severe colonic inflammation than control mice with the up-regulation of Th1 and Th17. Hypoxic stimulation in vitro increased Treg activation in WT T cells but not in HIF-1-deleted T cells. In contrast, hypoxic stimulation increased Th17 activation, and the degree was higher in HIF-1-deleted cells than in control cells. These results show that hypoxia controls intestinal inflammation by regulating cytokine balance in a HIF-1-dependent manner, suggesting that strengthening HIF-1 induction in T cells at the sites of inflammation might be a therapeutic strategy for IBD regulation.

Immune responses triggering colitis and colitis-associated carcinoma

Inflammatory bowel diseases compromise of two forms of chronic intestinal inflammatory disorders: Crohn's disease and ulcerative colitis. Both forms of inflammatory bowel disease result from inappropriate inflammatory responses to the intestinal microbiota, but have different underlying immune responses. The connection between inflammation and cancer has long been established and longstanding inflammatory bowel diseases are an important risk factor for developing colorectal cancer. Colitis-associated colorectal cancer pathogenesis is highly influenced by specific inflammatory processes during inflammatory bowel disease. This article reviews the immunological responses affecting Crohn's disease and ulcerative colitis as well as the linkage of inflammatory bowel disease to the development of colitis-associated cancer. Finally, we discuss the prospects of using new research efforts to devise new immunotherapeutic approaches.

Helminth-host immunological interactions: prevention and control of immune-mediated diseases

Exposure to commensal and pathogenic organisms strongly influences our immune system. Exposure to helminths was frequent before humans constructed their current highly hygienic environment. Today, in highly industrialized countries, contact between humans and helminths is rare. Congruent with the decline in helminth infections is an increase in the prevalence of autoimmune and inflammatory disease. It is possible that exclusion of helminths from the environment has permitted the emergence of immune-mediated disease. We review the protective effects of helminths on expression of inflammatory bowel disease, multiple sclerosis, and animal models of these and other inflammatory diseases. We also review the immune pathways altered by helminths that may afford protection from these illnesses. Helminth exposure tends to inhibit IFN-γ and IL-17 production, promote IL-4, IL-10, and TGF-β release, induce CD4(+) T cell Foxp3 expression, and generate regulatory macrophages, dendritic cells, and B cells. Helminths enable protective pathways that may vary by specific species and disease model. Helminths or their products likely have therapeutic potential to control or prevent immune-mediated illness.

Inflammatory bowel disease: is it a primary immunodeficiency?

Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease are chronic and relapsing conditions, characterized by abdominal pain, diarrhea, bleeding and malabsorption. IBD has been considered a hyperinflammatory state due to disturbed interactions between the immune system and the commensal bacterial flora of the gut. However, there is evidence that Crohn's disease might be the consequence of a reduced release of pro-inflammatory cytokines and an impaired acute inflammatory response, thereby suggesting that IBD might be an immunodeficiency rather than an excessive inflammatory reaction. This theory has been supported by observations in patients with primary immunodeficiencies such as the Wiskott-Aldrich syndrome and IPEX (immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome). In contrary, defects in the anti-inflammatory down-regulation of the immune response as they are seen in patients with Mendelian defects in the IL10 signaling pathway support the hyper-inflammatory theory. In this review, we describe and discuss primary immunodeficiencies associated with IBD and show that the bowel is a highly sensitive indicator of dysregulations, making IBD a model disease to study and identify key regulators required to balance the human mucosal immune system.

IL-10 and IL-10 receptor defects in humans

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is chronic in nature and is characterized by abdominal pain, diarrhea, bleeding, and malabsorption. It is considered a complex multigenic and multifactorial disorder that results from disturbed interactions between the immune system and commensal bacteria of the gut. Recent work has demonstrated that IBD with an early-onset within the first months of life can be monogenic: mutations in IL-10 or its receptor lead to a loss of IL-10 function and cause severe intractable enterocolitis in infants and small children. Both IL-10 and IL-10 receptor deficiency can be successfully treated by hematopoietic stem cell transplantation.

Mediation of Host Immune Responses after Immunization of Neonatal Calves with a Heat-Killed Mycobacterium avium subsp. paratuberculosis Vaccine

A major drawback of current whole-cell vaccines for Mycobacterium avium subsp. paratuberculosis is the interference with diagnostic tests for bovine tuberculosis (TB) and paratuberculosis. The current study was designed to explore the effects of immunization with a heat-killed whole-cell vaccine (Mycopar) on diagnostic test performance and to characterize host immune responses to vaccination over a 12-month period. Neonatal dairy calves were assigned to treatment groups consisting of (i) controls, not vaccinated ( n = 5), and (ii) vaccinates, vaccinated with Mycopar vaccine ( n = 5). The results from this study demonstrated a rapid initiation of M. avium subsp. paratuberculosis -specific gamma interferon (IFN-γ) in vaccinated calves by 7 days, with robust responses throughout the study. Vaccinated calves also had responses to M. bovis purified protein derivative tuberculin (BoPPD) but minimal reactivity to ESAT-6/CFP-10, an M. bovis recombinant fusion protein. The levels of antigen-specific interleukin-4 (IL-4) and IL-10 were markedly decreased in vaccinated calves between days 7 and 90 of the study but thereafter were similar to the levels in controls. Vaccinated calves began to seroconvert at 4 months, with 4/5 calves having detectable M. avium subsp. paratuberculosis antibody by 6 months. The responses in test platforms for bovine TB were negligible in the vaccinate group, as only one calf had a response, which was in the suspect range of the comparative cervical skin test. Serum antibody responses to M. bovis antigens ESAT-6, CFP-10, and MPB83 were negative on the Vet TB STAT-PAK, DPP VetTB, and DPP BovidTB tests. These results suggest that the Mycopar vaccine will interfere with diagnostic tools for paratuberculosis but result in low interference with the comparative cervical skin test and emerging serologic tests for M. bovis .

Inhibitor of PI3Kγ ameliorates TNBS-induced colitis in mice by affecting the functional activity of CD4+CD25+FoxP3+ regulatory T cells

BACKGROUND AND PURPOSE

Phosphoinositide 3-kinase-γ (PI3Kγ) is implicated in many pathophysiological conditions, and recent evidence has suggested its involvement in colitis. In the present study, we investigated the effects of AS605240, a relatively selective PI3Kγ inhibitor, in experimental colitis and its underlying mechanisms.

EXPERIMENTAL APPROACH

Acute colitis was induced in mice by treatment with trinitrobenzene sulphonic acid (TNBS), and the effect of AS605240 on colonic injury was assessed. Pro-inflammatory mediators and cytokines were measured by immunohistochemistry, elisa, real time-polymerase chain reaction and flow cytometry.

KEY RESULTS

Oral administration of AS605240 significantly attenuated TNBS-induced acute colitis and diminished the expression of matrix metalloproteinase-9 and vascular endothelial growth factor. The colonic levels and expression of IL-1β, CXCL-1/KC, MIP-2 and TNF-α were also reduced following therapeutic treatment with AS605240. Moreover, AS605240 reduced MIP-2 levels in a culture of neutrophils stimulated with lipopolysaccharide. The mechanisms underlying these actions of AS605240 are related to nuclear factor-κ (NF-κB) inhibition. Importantly, the PI3Kγ inhibitor also up-regulated IL-10, CD25 and FoxP3 expression. In addition, a significant increase in CD25 and FoxP3 expression was found in isolated lamina propria CD4+ T cells of AS605240-treated mice. The effect of AS605240 on Treg induction was further confirmed by showing that concomitant in vivo blockade of IL-10R significantly attenuated its therapeutic activity.

CONCLUSIONS AND IMPLICATIONS

These results suggest that AS605240 protects mice against TNBS-induced colitis by inhibiting multiple inflammatory components through the NF-κB pathway while simultaneously inducing an increase in the functional activity of CD4+CD25+ Treg. Thus, AS605240 may offer a promising new therapeutic strategy for the treatment of inflammatory bowel diseases.

Identification of Treg-like cells in Tetraodon: insight into the origin of regulatory T subsets during early vertebrate evolution

CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg cells) are critical for the maintenance of peripheral tolerance, and the suppression of autoimmune diseases and even tumors. Although Treg cells are well characterized in humans, little is known regarding their existence or occurrence in ancient vertebrates. In the present study, we report on the molecular and functional characterization of a Treg-like subset with the phenotype CD4-2(+)CD25-like(+)Foxp3-like(+) from a pufferfish (Tetraodon nigroviridis) model. Functional studies showed that depletion of this subset produced an enhanced mixed lymphocyte reaction (MLR) and nonspecific cytotoxic cell (NCC) activity in vitro, as well as inflammation of the intestine in vivo. The data presented here will not only enrich the knowledge of fish immunology but will also be beneficial for a better cross-species understanding of the evolutionary history of the Treg family and Treg-mediated regulatory networks in cellular immunity.

Antigen presentation and MHC class II expression by human esophageal epithelial cells: role in eosinophilic esophagitis

Professional antigen-presenting cells (APCs) play a crucial role in initiating immune responses. Under pathological conditions, epithelial cells at mucosal surfaces act as nonprofessional APCs, thereby regulating immune responses at the site of exposure. Epithelial cells in the esophagus may contribute to the pathogenesis of eosinophilic esophagitis (EoE) by presenting antigens on the major histocompatibility complex (MHC) class II. Our goal was to demonstrate the ability of esophageal epithelial cells to process and present antigens on the MHC class II system and to investigate the contribution of epithelial cell antigen presentation to EoE. Immunohistochemistry detected HLA-DR, CD80, and CD86 expression and enzyme-linked immunosorbent assay detected interferon-γ (IFNγ) in esophageal biopsies. Antigen presentation was studied using the human esophageal epithelial cell line HET-1A by reverse transcriptase-PCR, flow cytometry, and confocal microscopy. T helper cell lymphocyte proliferation was assessed by flow cytometry and IL-2 secretion. IFNγ and MHC class II were increased in mucosa of patients with EoE. IFNγ increased mRNA of HLA-DP, HLA-DQ, HLA-DR, and CIITA in HET-1A cells. HET-1A engulfed cell debris and processed ovalbumin. HET-1A cells expressed HLA-DR after IFNγ treatment. HET-1A stimulated T helper cell activation. In this study, we demonstrated the ability of esophageal epithelial cells to act as nonprofessional APCs in the presence of IFNγ. Esophageal epithelial cell antigen presentation may contribute to the pathophysiology of eosinophilic esophagitis.

Increase of regulatory T cells in ileal mucosa of untreated pediatric Crohn's disease patients

BACKGROUND

Inflammatory bowel disease (IBD) of pediatric and adult onset differs in several aspects although little knowledge exists about pathogenic disparity. Regulatory T cells (Tregs) characterized as CD4+CD25+Foxp3+ are modulators of gut homeostasis, but their role in human IBD remains unclear.

OBJECTIVE

To evaluate the mucosal distribution of Foxp3+ and CD25+ cells in untreated pediatric IBD patients at the time of diagnosis.

MATERIAL AND METHODS

Untreated pediatric (n = 14) and adult (n = 12) Crohn's disease (CD) patients were prospectively included together with age-matched symptomatic controls. Colonic and ileal mucosal biopsies collected at diagnosis were studied by immunohistochemistry for enumeration of T cells and for mucosal expression of Foxp3 and CD25. Multicolor immunofluorescence staining was performed in situ to phenotype Foxp3+ cells as Tregs and characterize the CD25+ cells.

RESULTS

The density of mucosal T cells displayed only small variations, while that of Foxp3+ cells and CD25+ cells was increased in CD patients. Multicolor immunofluorescence showed that most CD25+ cells were macrophages. Interestingly, in the ileum of pediatric CD patients the density of Foxp3+ cells was significantly higher than in adult CD patients. Co-expression of Foxp3 and CD25, as well as Foxp3 and CTLA-4, indicated that the Foxp3+ cells were Tregs.

CONCLUSION

Mucosal numbers of Foxp3(+) Tregs and activated (CD25+) macrophages are elevated in both pediatric and adult ileal CD. The greater increase of ileal Foxp3+ Tregs in pediatric CD than in adult CD might contribute to the relatively less frequent phenotype of isolated ileal enteritis in CD children.

Function of the intestinal epithelium and its dysregulation in inflammatory bowel disease

The intestinal epithelium not only acts as a physical barrier to commensal bacteria and foreign antigens but is also actively involved in antigen processing and immune cell regulation. The inflammatory bowel diseases (IBDs) are characterized by inflammation at this mucosal surface with well-recognized defects in barrier and secretory function. In addition to this, defects in intraepithelial lymphocytes, chemokine receptors, and pattern recognition receptors promote an abnormal immune response, with increased differentiation of proinflammatory cells and a dysregulated relationship with professional antigen-presenting cells. This review focuses on recent developments in the structure of the epithelium, including a detailed account of the apical junctional complex in addition to the role of the enterocyte in antigen recognition, uptake, processing, and presentation. Recently described cytokines such as interleukin-22 and interleukin-31 are highlighted as is the dysregulation of chemokines and secretory IgA in IBD. Finally, the effect of the intestinal epithelial cell on T effector cell proliferation and differentiation are examined in the context of IBD with particular focus on T regulatory cells and the two-way interaction between the intestinal epithelial cell and certain immune cell populations.

Ectonucleotidases as regulators of purinergic signaling in thrombosis, inflammation, and immunity

Evolving studies in models of transplant rejection, inflammatory bowel disease, and cancer, among others, have implicated purinergic signaling in clinical manifestations of vascular injury and thrombophilia, inflammation, and immune disturbance. Within the vasculature, spatial and temporal expression of CD39 nucleoside triphosphate diphosphohydrolase (NTPDase) family members together with CD73 ecto-5'-nucleotidase control platelet activation, thrombus size, and stability. This is achieved by closely regulated phosphohydrolytic activities to scavenge extracellular nucleotides, maintain P2-receptor integrity, and coordinate adenosinergic signaling responses. The CD38/CD157 family of extracellular NADases degrades NAD(+) and generates Ca(2+)-active metabolites, including cyclic ADP ribose and ADP ribose. These mediators regulate leukocyte adhesion and chemotaxis. These mechanisms are crucial in vascular homeostasis, hemostasis, thrombogenesis, and during inflammation. There has been recent interest in ectonucleotidase expression by immune cells. CD39 expression identifies Langerhans-type dendritic cells and efficiently distinguishes T regulatory cells from other resting or activated T cells. CD39, together with CD73 in mice, serves as an integral component of the suppressive machinery of T cells. Purinergic responses also impact generation of T helper-type 17 cells. Further, CD38 and changes in NAD(+) availability modulate ADP ribosylation of the cytolytic P2X7 receptor that deletes T regulatory cells. Expression of CD39, CD73, and CD38 ectonucleotidases on either endothelial or immune cells allows for homeostatic integration and control of vascular inflammatory and immune cell reactions at sites of injury. Ongoing development of therapeutic strategies targeting these and other ectonucleotidases offers promise for the management of vascular thrombosis, disordered inflammation, and aberrant immune reactivity.

The effects of Foxp3-expressing regulatory T cells expanded with CD28 superagonist antibody in DSS-induced mice colitis

Regulatory T (Treg) cells play an important role in the pathogenesis of inflammatory bowel disease (IBD). In the present study, we found that a superagonistic CD28-specific monoclonal antibody (supCD28mAb, D665) could preferentially stimulate expansion of CD4+Foxp3+ Treg cells. Foxp3(EGFP) mice were orally administrated with 3.5% DSS for 5days, and intraperitoneally injected supCD28mAb 1mg/mice in treated group. All of the mice were sacrificed on day 8, and both clinical and histological parameters showed that the severity of colitis was significantly reduced in treated group compared to controls. In treated group, the proportion of CD103, CD152 and CD62L expression on Foxp3+Treg cells in the spleen and mesenteric lymph node were higher than controls. Furthermore, qRT-PCR analysis showed that expression of anti-inflammatory cytokines such as IL-10, TGF-β was significantly increased in treated group. Taken together, our data demonstrated that supCD28mAb targets CD4+Foxp3+Treg cells expansion in vivo, maintains and enhances their regulatory functions, to reduce the damage of colon in dextran sulfate sodium (DSS)-induced mouse colitis by secreting a large amount of IL-10. It represents a major advance towards the therapeutic use of polyclonally activated Treg cells as cellular therapy for treatment of IBD.

Decreased production of interleukin-10 and transforming growth factor-β in Toll-like receptor-activated intestinal B cells in SAMP1/Yit mice

A unique subset of B cells expressing interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) plays an essential role in preventing inflammation and autoimmunity. We investigated the presence of this cell subset in intestines and its role in the pathogenesis of ileitis using SAMP1/Yit and age-matched control AKR/J mice. Mononuclear cells were isolated from mesenteric lymph nodes (MLNs) and the expressions of B220, CD1d, CD5, Toll-like receptor 4 (TLR4) and TLR9 in isolated cells were analysed. Purified B cells were stimulated with lipopolysaccharide (LPS) or CpG-DNA, then IL-10 and TGF-β(1) expressions were examined by enzyme immunoassay and flow cytometry. Production of IL-1β by TLR-mediated macrophages co-cultured with or without purified MLN B cells from SAMP1/Yit and AKR/J mice was evaluated. In addition, interferon-γ (IFN-γ) production in intestinal T cells co-cultured with MLN B cells were also assessed in SAMP1/Yit and AKR/J strains. The production levels of IL-10 and TGF-β(1) stimulated by LPS and CpG-DNA were significantly lower in B cells separated from MLNs from the SAMP1/Yit strain. B cells expressing IL-10 and TGF-β(1) were mainly located in a population characterized by the cell surface marker CD1d(+) . Interleukin-1β production by TLR-activated macrophages co-cultured with MLN B cells from SAMP1/Yit mice was significantly higher than that of those from AKR/J mice. Interestingly, IFN-γ production by T cells was noted only when they were co-cultured with SAMP1/Yit but not the AKR/J B cells. These results are the first to show that disorders of regulatory B-cell function under innate immune activation may cause disease pathogenesis in a murine model of Crohn's disease.

Epinephrine-primed murine bone marrow-derived dendritic cells facilitate production of IL-17A and IL-4 but not IFN-γ by CD4+ T cells

Sympathetic activation leading to the release of epinephrine and norepinephrine, is known as an important regulatory circuit related to immune-mediated diseases. However, questions still remain on the behavior of antigen presenting cells (APC) dictated by stress-induced sympathetic neurotransmitters. The purpose of this study was to examine the fate of bone marrow-derived dendritic cell (BMDC)-associated influences on resting CD4(+) T cell activation. We hypothesize that pre-exposure of dendritic cells (DCs) can modify the intensity of cytokine production, leading to preference in resting CD4(+) T cell activation. BMDCs were pre-treated with epinephrine for 2h followed by subsequent treatment of lipopolysaccharide (LPS). Subsequently, BMDCs were cocultured with purified CD4(+) T cells from mouse spleen in the absence or presence of anti-CD3 stimulation in epinephrine-free media. Epinephrine pre-treatment enhanced surface expression of MHCII, CD80 and CD86. Quantitative RT-PCR showed that epinephrine pre-treatment induced a significant transcriptional decrease of IL-12p40 and a significant increase of IL-12p35 and IL-23p19. In addition, β2-adrenergic-blockade was shown to reverse these effects. Epinephrine pre-treatment also induced a significant decrease of IL-12p70 and a significant increase of IL-23 and IL-10 cytokine production. Importantly, these changes corresponded with increased IL-4 and IL-17A, but not IFN-g cytokine production by CD4(+) T cells in a b2-adrenergic receptor-dependent manner. These results suggest that exposure to stress-derived epinephrine dictates dendritic cells to generate a dominant Th2/Th17 phenotype in the context of subsequent exposure to a pathogenic stimulus.

New insights into the immunological effects of food bioactive peptides in animal models of intestinal inflammation

Bioactive peptides have proven to be active in several conditions, including inflammatory bowel disease (IBD). This is a chronic and relapsing condition of unknown aetiology that comprises chiefly ulcerative colitis and Crohn's disease. Although there are treatments for IBD, they have frequent side effects and they are not always effective; therefore there is a need for new therapies that could alleviate this condition. Two bioactive peptides present in milk (transforming growth factor-beta (TGF-beta) and casein macropeptide, also named glycomacropeptide) have been shown to have intestinal anti-inflammatory activities. In fact, TGF-beta is currently added to formulas intended for patients with IBD, and several studies indicate that these formulas could induce clinical remission. In this paper, evidence supporting the anti-inflammatory effect of TGF-beta and bovine glycomacropeptide, as well as their mechanisms of action, is reviewed, focusing on the evidence obtained in animal models.

Crohn's disease as an immunodeficiency

The pathogenesis of Crohn's disease (CD) has widely been regarded as the consequence of a dysregulated T-cell-mediated response to intestinal microbes, and the majority of the worldwide research effort has focused on characterizing and treating the chronic inflammatory phase of the disease. However, recent molecular biological and clinical investigations indicate that CD is actually a primary immunodeficiency. At first counter-intuitive, the apparent paradox of a pathogenic innate immune defect can be linked mechanistically to the granulomatous chronic inflammation characteristic of the disease. Genome-wide association studies have corroborated the involvement of innate immune dysfunction in the pathogenesis of CD, but less than 20% of the heritable risk is accounted for. By contrast, in vitro and in vivo stimulation of the immune system has highlighted novel areas of interest that may lead to the development of targeted therapeutic and diagnostic tools.

Role of gut-resident dendritic cells in inflammatory bowel disease

The gastrointestinal immune system, innate and adaptive, is continuously exposed to challenges provided by the enteric flora. In most cases, the result of mucosal immune responses is the development of tolerance. Mucosal dendritic cells initiate and regulate local immune responses. Uncontrolled local immune responses are thought to be a major factor in the development of inflammatory bowel disease, such as Crohn's disease and ulcerative colitis. This review will discuss the function of dendritic cells in the recognition of the enteric flora and their role in the development of intestinal inflammation.

Stem cells as potential therapeutic targets for inflammatory bowel disease

The incidence and prevalence of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), are rising. According to some estimates >1 million new cases of IBD arise in the United States annually. The conventional therapies available for IBD range from anti-inflammatory drugs to immunosuppressive agents, but these therapies generally fail to achieve satisfactory results due to their side effects. Interest in a new therapeutic option, that is, biological therapy, has gained much momentum recently due to its focus on different stages of the inflammatory process. Stem cell (SC) research has become a new direction for IBD therapy due to our recent understanding of cell populations involved in the pathogenic process. To this end, hematopoietic and mesenchymal stem cells are receiving more attention from IBD investigators. The intestinal environment, with its crypts and niches, supports incoming embryonic and hematopoietic stem cells and allows them to engraft and differentiate. The above findings suggest that, in the future, SC-based therapy will be a promising alternative to conventional therapy for IBD. In this review, we discuss SCs as potential therapeutic targets for future treatment of IBD.

Cellular mediators of inflammation: tregs and TH17 cells in gastrointestinal diseases

Human lymphocyte subpopulations were originally classified as T- and B-cells in the 70s. Later, with the development of monoclonal antibodies, it became possible to recognize, within the T-cells, functional populations: CD4⁺ and CD8⁺. These populations were usually referred to as “helper” and “suppressor” cells, respectively. However several investigations within the CD8 cells failed to detect a true suppressor activity. Therefore the term suppressor was neglected because it generated confusion. Much later, true suppressor activity was recognized in a subpopulation of CD4 cells characterized by high levels of CD25. The novel population is usually referred to as T regulatory cells (Tregs) and it is characterized by the expression of FoxP3. The heterogeneity of CD4 cells was further expanded by the recent description of a novel subpopulation characterized by production of IL-17. These cells are generally referred to as T_H17. They contribute to regulate the overall immune response together with other cytokine-producing populations. Treg and T_H17 cells are related because they could derive from a common progenitor, depending on the presence of certain cytokines. The purpose of this review is to summarize recent findings of the role of these novel populations in the field of human gastroenterological disease.