Intestinal Lamina Propria Mononuclear Cells Research Articles

Interferon-Regulated Expression of Cellular Splicing Factors Modulates Multiple Levels of HIV-1 Gene Expression and Replication.

Type I interferons (IFN-Is) are pivotal in innate immunity against human immunodeficiency virus I (HIV-1) by eliciting the expression of IFN-stimulated genes (ISGs), which encompass potent host restriction factors. While ISGs restrict the viral replication within the host cell by targeting various stages of the viral life cycle, the lesser-known IFN-repressed genes (IRepGs), including RNA-binding proteins (RBPs), affect the viral replication by altering the expression of the host dependency factors that are essential for efficient HIV-1 gene expression. Both the host restriction and dependency factors determine the viral replication efficiency; however, the understanding of the IRepGs implicated in HIV-1 infection remains greatly limited at present. This review provides a comprehensive overview of the current understanding regarding the impact of the RNA-binding protein families, specifically the two families of splicing-associated proteins SRSF and hnRNP, on HIV-1 gene expression and viral replication. Since the recent findings show specifically that SRSF1 and hnRNP A0 are regulated by IFN-I in various cell lines and primary cells, including intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs), we particularly discuss their role in the context of the innate immunity affecting HIV-1 replication.

Hepatocyte growth factor ameliorates dextran sodium sulfate‑induced colitis in a mouse model by altering the phenotype of intestinal macrophages.

Hepatocyte growth factor (HGF) serves key roles in cell motility, proliferation and immunoregulatory functions. However, the effect of HGF on macrophages is unclear. The present study aimed to elucidate the effect of HGF on the phenotypic alterations of intestinal lamina propria mononuclear cells (LPMCs). Colitis was induced in a mouse model using dextran sodium sulfate (DSS). Subsequently, LPMCs were isolated from the mice with chronic colitis and the expression levels of cytokine‑encoding genes in the LPMCs were determined. CD11b‑positive macrophages isolated from LPMCs were cultured with HGF, and alterations in the levels of M1 or M2 markers were evaluated by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and flow cytometry. In addition, the cytokine levels were assessed using RT‑qPCR and ELISA. HGF shifted the phenotype of macrophages from M1 to M2‑like, as determined by increased mRNA expression levels of arginase‑1, CD206 and IL‑10, and reduced mRNA expression levels of CD86 and IL‑6 in mice with DSS‑induced colitis. Moreover, HGF could ameliorate DSS‑induced colitis owing to its immunosuppressive effect on immune cells. These findings indicated that HGF treatment may not only promote the regeneration of epithelial cells but also lead to tissue repair by phenotypic alteration of M1 macrophages to M2‑like macrophages.

SRSF1 acts as an IFN-I-regulated cellular dependency factor decisively affecting HIV-1 post-integration steps.

Efficient HIV-1 replication depends on balanced levels of host cell components including cellular splicing factors as the family of serine/arginine-rich splicing factors (SRSF, 1-10). Type I interferons (IFN-I) play a crucial role in the innate immunity against HIV-1 by inducing the expression of IFN-stimulated genes (ISGs) including potent host restriction factors. The less well known IFN-repressed genes (IRepGs) might additionally affect viral replication by downregulating host dependency factors that are essential for the viral life cycle; however, so far, the knowledge about IRepGs involved in HIV-1 infection is very limited. In this work, we could demonstrate that HIV-1 infection and the associated ISG induction correlated with low SRSF1 levels in intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs) during acute and chronic HIV-1 infection. In HIV-1-susceptible cell lines as well as primary monocyte-derived macrophages (MDMs), expression levels of SRSF1 were transiently repressed upon treatment with specific IFNα subtypes in vitro. Mechanically, 4sU labeling of newly transcribed mRNAs revealed that IFN-mediated SRSF1 repression is regulated on early RNA level. SRSF1 knockdown led to an increase in total viral RNA levels, but the relative proportion of the HIV-1 viral infectivity factor (Vif) coding transcripts, which is essential to counteract APOBEC3G-mediated host restriction, was significantly reduced. In the presence of high APOBEC3G levels, however, increased LTR activity upon SRSF1 knockdown facilitated the overall replication, despite decreased vif mRNA levels. In contrast, SRSF1 overexpression significantly impaired HIV-1 post-integration steps including LTR transcription, alternative splice site usage, and virus particle production. Since balanced SRSF1 levels are crucial for efficient viral replication, our data highlight the so far undescribed role of SRSF1 acting as an IFN-modulated cellular dependency factor decisively regulating HIV-1 post-integration steps.

Antibiotic-associated dysbiosis affects the ability of the gut microbiota to control intestinal inflammation upon fecal microbiota transplantation in experimental colitis models

BackgroundThe gut microbiota plays a central role in host physiology and in several pathological mechanisms in humans. Antibiotics compromise the composition and functions of the gut microbiota inducing long-lasting detrimental effects on the host. Recent studies suggest that the efficacy of different clinical therapies depends on the action of the gut microbiota. Here, we investigated how different antibiotic treatments affect the ability of the gut microbiota to control intestinal inflammation upon fecal microbiota transplantation in an experimental colitis model and in ex vivo experiments with human intestinal biopsies.ResultsMurine fecal donors were pre-treated with different antibiotics, i.e., vancomycin, streptomycin, and metronidazole before FMT administration to colitic animals. The analysis of the gut microbiome, fecal metabolome, and the immunophenotyping of colonic lamina propria immune cells revealed that antibiotic pre-treatment significantly influences the capability of the microbiota to control intestinal inflammation. Streptomycin and vancomycin-treated microbiota failed to control intestinal inflammation and were characterized by the blooming of pathobionts previously associated with IBD as well as with metabolites related to the presence of oxidative stress and metabolism of simple sugars. On the contrary, the metronidazole-treated microbiota retained its ability to control inflammation co-occurring with the enrichment of Lactobacillus and of innate immune responses involving iNKT cells. Furthermore, ex vivo cultures of human intestinal lamina propria mononuclear cells and iNKT cell clones from IBD patients with vancomycin pre-treated sterile fecal water showed a Th1/Th17 skewing in CD4+ T-cell populations; metronidazole, on the other hand, induced the polarization of iNKT cells toward the production of IL10.ConclusionsDiverse antibiotic regimens affect the ability of the gut microbiota to control intestinal inflammation in experimental colitis by altering the microbial community structure and microbiota-derived metabolites.6E6mfZzU_A62fWsXVW3UYFVideo

Repertoire analysis of memory T-cell receptors in Japanese patients with inflammatory bowel disease.

Background and AimThe T‐cell receptor (TCR) repertoire was assessed in response to various antigens and was considered to be associated with the pathogenesis of inflammatory bowel disease (IBD). Thus, we performed TCR repertoire analysis to examine the pathology of IBD from changes in the TCR repertoire of memory T cells in the intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs) of patients with IBD.MethodsLPMCs in the surgical specimens and PBMCs were isolated from 12 patients with IBD (5 patients with ulcerative colitis [UC] and 7 patients with Crohn's disease [CD]). PBMCs were collected from 10 healthy individuals as controls. Comprehensive TCR sequence analyses of adaptor‐ligation polymerase chain reaction (PCR) products were performed using MiSeq.ResultsThe diversity of TCR‐α and TCR‐β in PBMCs was significantly lower in patients with IBD than that in controls (P = 0.00084 and 0.0013, respectively). Comparisons of TCR diversity in LPMCs and PBMCs between CD and UC showed that the diversity in LPMC was not affected by diseases, whereas that in PBMCs was significantly lower in CD than in UC (P = 0.045 and 0.049, respectively). Some TCR clones may have shown a specific increase or decrease in CD and UC, and many clones were common to both LPMCs and PBMCs in the same patients.ConclusionThe diversity of TCR clones in LPMCs and PBMCs in patients with IBD was significantly lower than that of PBMCs in controls. TCR diversity in PBMCs was particularly low in patients with CD.

P027 Repertoire analysis of memory T-cell receptors in Japanese patients with inflammatory bowel disease

Abstract Background The T-cell receptor (TCR) repertoire was assessed in response to various antigens and was considered to be associated with the pathogenesis of inflammatory bowel disease (IBD). Thus, we performed TCR repertoire analysis to examine the pathology of IBD from changes in the TCR repertoire of memory T cells in the intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs) of patients with IBD. Methods LPMCs in the surgical specimens and PBMCs were isolated from 12 patients with IBD [five patients with ulcerative colitis (UC) and seven patients with Crohn’s disease (CD)]. PBMCs were collected from 10 healthy individuals as controls. Comprehensive TCR sequence analyses of adaptor-ligation PCR products were performed using MiSeq. Results The diversity of TCR-α and -β in PBMCs was significantly lower in patients with IBD than that in controls (p = 0.00084 and 0.0013, respectively). Comparisons of TCR diversity in LPMCs and PBMCs between CD and UC showed that the diversity in LPMC was not affected by diseases, whereas that in PBMCs was significantly lower in CD than in UC (p = 0.045 and 0.049, respectively). Some TCR clones may have shown a specific increase or decrease in CD and UC and many clones were common to both LPMCs and PBMCs in the same patients. Conclusion The diversity of TCR clones in LPMCs and PBMCs in patients with IBD was significantly lower than that of PBMCs in controls. TCR diversity in PBMCs was particularly low in patients with CD.

Protective Effects of Aryl Hydrocarbon Receptor Signaling in Celiac Disease Mucosa and in Poly I:C-Induced Small Intestinal Atrophy Mouse Model

Aryl hydrocarbon receptor (AhR), a transcription factor activated by a large number of natural and synthetic agents, modulates the activity of immune cells in the gut and represents an important link between the environment and immune-mediated pathologies. In this study, we investigated the role of AhR in celiac disease (CD), a gluten-driven enteropathy. AhR expression was evaluated in intestinal biopsies taken from patients with CD and controls by real-time polymerase chain reaction (PCR), immunohistochemistry and flow cytometry. AhR was also analyzed in ex vivo organ cultures of duodenal biopsies taken from inactive CD patients incubated in presence or absence of peptic-tryptic digest of gliadin. IFN-γ, TNF-α, granzyme B, and perforin expression was evaluated in anti-CD3/CD28-activated intestinal lamina propria mononuclear cells (LPMC) and intestinal intra-epithelial cells (IEL) of active CD patients cultured in the presence or absence of the AhR agonist 6-formylindolo(3, 2-b)carbazole (Ficz). Finally, the protective role of AhR was evaluated in a mouse model of poly I:C-driven small intestine damage. AhR RNA transcripts were reduced in active CD samples as compared to inactive CD and normal controls. Flow cytometry confirmed such results and showed a reduction of AhR in both IEL and LPMC of active CD patients. The addition of a peptic-tryptic digest of gliadin to ex vivo organ cultures of duodenal biopsies taken from inactive CD patients reduced AhR expression. Treatment of CD IEL and LPMC with Ficz reduced the levels of inflammatory cytokines, granzyme B and perforin. Mice injected with Ficz were protected against poly I:C-induced intestinal lesions. Our findings suggest that defective AhR-driven signals could contribute to amplify pathogenic responses in the gut of CD patients.

Thymopentin ameliorates dextran sulfate sodium-induced colitis by triggering the production of IL-22 in both innate and adaptive lymphocytes.

Background: Ulcerative colitis (UC) is a chronic inflammatory gastrointestinal disease, notoriously challenging to treat. Previous studies have found a positive correlation between thymic atrophy and colitis severity. It was, therefore, worthwhile to investigate the effect of thymopentin (TP5), a synthetic pentapeptide corresponding to the active domain of the thymopoietin, on colitis.Methods: Dextran sulfate sodium (DSS)-induced colitis mice were treated with TP5 by subcutaneous injection. Body weight, colon length, colon weight, immune organ index, disease activity index (DAI) score, and the peripheral blood profile were examined. The immune cells of the spleen and colon were analyzed by flow cytometry. Histology was performed on isolated colon tissues for cytokine analysis. Bacterial DNA was extracted from mouse colonic feces to assess the intestinal microbiota. Intestinal lamina propria mononuclear cells (LPMCs), HCT116, CT26, and splenocytes were cultured and treated with TP5.Results: TP5 treatment increased the body weight and colon length, decreased the DAI score, and restored colon architecture of colitic mice. TP5 also decreased the infiltration of immune cells and expression levels of pro-inflammatory cytokines such as IL-6. Importantly, the damaged thymus and compromised lymphocytes in peripheral blood were significantly restored by TP5. Also, the production of IL-22, both in innate and adaptive lymphoid cells, was triggered by TP5. Given the critical role of IL-22 in mucosal host defense, we tested the effect of TP5 on mucus barrier and gut microbiota and found that the number of goblet cells and the level of Mucin-2 expression were restored, and the composition of the gut microbiome was normalized after TP5 treatment. The critical role of IL-22 in the protective effect of TP5 on colitis was further confirmed by administering the anti-IL-22 antibody (αIL-22), which completely abolished the effect of TP5. Furthermore, TP5 significantly increased the expression level of retinoic acid receptor-related orphan receptor γ (RORγt), a transcription factor for IL-22. Consistent with this, RORγt inhibitor abrogated the upregulation of IL-22 induced by TP5.Conclusion: TP5 exerts a protective effect on DSS-induced colitis by triggering the production of IL-22 in both innate and adaptive lymphocytes. This study delineates TP5 as an immunomodulator that may be a potential drug for the treatment of UC.

Disturbance in the Mucosa-Associated Commensal Bacteria Is Associated with the Exacerbation of Chronic Colitis by Repeated Psychological Stress; Is That the New Target of Probiotics?

Psychological stress can exacerbate inflammatory bowel disease. However, the mechanisms underlying how psychological stress affects gut inflammation remain unclear. Here, we focused on the relationship between changes in the microbial community of mucosa-associated commensal bacteria (MACB) and mucosal immune responses induced by chronic psychological stress in a murine model of ulcerative colitis. Furthermore, we examined the effect of probiotic treatment on exacerbated colitis and MACB composition changes induced by chronic psychological stress. Repeated water avoidance stress (rWAS) in B6-Tcra-/- mice severely exacerbated colitis, which was evaluated by both colorectal tissue weight and histological score of colitis. rWAS treatment increased mRNA expression of UCN2 and IFN-γ in large intestinal lamina propria mononuclear cells (LI-LPMC). Interestingly, exacerbated colitis was associated with changes in the microbial community of MACB, specifically loss of bacterial species diversity and an increase in the component ratio of Clostridium, revealed by 16S rRNA gene amplicon analysis. Finally, the oral administration of a probiotic Lactobacillus strain was protective against the exacerbation of colitis and was associated with a change in the bacterial community of MACB in rWAS-exposed Tcra-/- mice. Taken together, these results suggested that loss of species diversity in MACB might play a key role in exacerbated colitis induced by chronic psychological stress. In addition, probiotic treatment may be used as a tool to preserve the diversity of bacterial species in MACB and alleviate gut inflammation induced by psychological stress.

Sodium chloride-enriched Diet Enhanced Inflammatory Cytokine Production and Exacerbated Experimental Colitis in Mice.

Environmental factors are supposed to play a decisive role in the pathogenesis of inflammatory bowel diseases [IBDs]. Increased dietary salt intake has been linked with the development of autoimmune diseases, but the impact of a salt-enriched diet on the course of IBD remains unknown. In this study, we examined whether high salt intake alters mucosal cytokine production and exacerbates colitis. Normal intestinal lamina propria mononuclear cells [LPMCs] were activated with anti-CD3/CD28 in the presence or absence of increasing concentrations of sodium chloride [NaCl] and/or SB202190, a specific inhibitor of p38/MAP Kinase. For in vivo experiments, a high dose of NaCl was administered to mice 15 days before induction of trinitrobenzene-sulfonic acid [TNBS]-colitis or dextran sulfate sodium [DSS]-colitis. In parallel, mice were given SB202190 before induction of TNBS-colitis. Transcription factors and effector cytokines were evaluated by flow-cytometry and real-time PCR. IL-17A, IL-23R, TNF-α, and Ror-γT were significantly increased in human LPMCs following NaCl exposure, while there was no significant change in IFN-γ, T-bet or Foxp3. Pharmacologic inhibition of p38/MAPK abrogated the NaCl-inducing effect on LPMC-derived cytokines. Mice receiving the high-salt diet developed a more severe colitis than control mice, and this effect was preventable by SB202190. Our data indicated that exposure of intestinal mononuclear cells to a high-NaCl diet enhanced effector cytokine production and contributed to the exacerbation of experimental colitis in mice.

The integrin αvβ8 promotes activation of TGFβ by human peripheral monocyte and intestinal macrophage populations

Abstract Transforming growth factor beta (TGFβ) plays a key role in maintaining immune homeostasis, both preventing inflammation and promoting tissue repair. The cytokine is secreted as an inactive complex, with the function of TGFβ tightly regulated at the level of its activation. Our previous work in mice has demonstrated a crucial role for an integrin, αvβ8, in activation of TGFβ in the immune system. This pathway appears especially important in the intestine, with important functions in regulating T-cell response via integrin αvβ8 expression in dendritic cells and regulatory T-cells. However, how TGFβ is activated to regulate the human immune system is poorly understood. Here, we show that, in humans, integrin αvβ8 is highly expressed on blood monocytes, which promotes activation of TGFβ by these cells. When monocytes are differentiated to macrophages, high integrin β8 expression and TGFβ-activating function is observed on the more tolerogenic (M2-like) macrophages versus inflammatory (M1-like) macrophages. In both monocytes and macrophages, expression of β8 is upregulated by specific bacterial TLR ligands, suggesting that stimulation of the cells may promote their ability to activate TGFβ. In addition to peripheral immune cells, intestinal lamina propria mononuclear cells express high levels of integrin αvβ8, with increased levels seen in patients with inflammatory bowel disease. Highest levels of integrin αvβ8 are seen on a population of CD14+CD33+CD64+ cells, corresponding to intestinal macrophages. Thus, our data suggest that expression of integrin αvβ8 on monocytes may play an important role in the induction and function of anti-inflammatory macrophages in the intestine via TGFβ activation.

Therapeutic potential of recombinant cystatin from Schistosoma japonicum in TNBS-induced experimental colitis of mice.

BackgroundHelminth infections and their components have been shown to have a protective effect on autoimmune diseases. The isolated purified protein from Schisotosoma japonicum and its potential therapeutic effect on trinitrobenzene sulfonic acid (TNBS)-induced colitis could provide an alternative way to treat inflammatory bowel disease (IBDs).MethodsColitis was induced in Balb/c mice by rectal administration of 2.5 % TNBS, followed by intraperitoneal injection of rSjcystatin 50 μg at 6 h and 24 h afterwards. The inflammation was monitored by recording weight change, stool character and bleeding, colon length, macroscopic score (MAO), microscopic score (MIO), myeloperoxidase activity (MPO) and disease activity index (DAI). The potential underlying mechanism was investigated by examining cytokine profiles including Th1 (IFNγ), Th2 (IL-4), Th17 (IL-17A) and Treg subsets from lymphocytes of spleen, mesenteric lymph nodes (MLN) and intestinal lamina propria mononuclear cells (LPMCs) by flow cytometry. The mRNA relative expressions of the cytokines in splenocytes and MLN were analysed by quantitative real time reverse-transcriptase polymerase chain reaction (qRT-PCR). Simultaneously, the concentrations of the cytokines in the colon homogenate supernatants were tested by enzyme-linked immunosorbent assay (ELISA) and key transcription factors were detected by Western blotting.ResultsAdministration of rSjcystatin significantly reduced inflammatory parameters and ameliorated the severity of the TNBS-induced colitis through decreasing IFNγ in three organs and lifting the level of IL-4, IL-13, IL-10, and TGF-β in the colon tissues, with uptrending Tregs in the MLN and LPMC.ConclusionThe findings provide evidence that rSjcystatin has a therapeutic potential for diminishing colitis inflammation in Balb/c mice. The immunological mechanism may involve the down-regulation of Th1 response and up-regulation of Th2 and Tregs in the MLN and colon.

PP 3.20 - Peripheral blood CD4 + T cells and intestinal lamina propria mononuclear cells contribute to viremia following an analytical treatment interruption: a follow-up analysis of the panobinostat trial

PP 3.20 - Peripheral blood CD4 + T cells and intestinal lamina propria mononuclear cells contribute to viremia following an analytical treatment interruption: a follow-up analysis of the panobinostat trial

Interleukin-6 (IL-6) Regulates Claudin-2 Expression and Tight Junction Permeability in Intestinal Epithelium

In inflammatory bowel diseases (IBD), intestinal barrier function is impaired as a result of deteriorations in epithelial tight junction (TJ) structure. IL-6, a pleiotropic cytokine, is elevated in IBD patients, although the role of IL-6 in barrier function remains unknown. We present evidence that IL-6 increases TJ permeability by stimulating the expression of channel-forming claudin-2, which is required for increased caudal-related homeobox (Cdx) 2 through the MEK/ERK and PI3K pathways in intestinal epithelial cells. IL-6 increases the cation-selective TJ permeability without any changes to uncharged dextran flux or cell viability in Caco-2 cells. IL-6 markedly induces claudin-2 expression, which is associated with increased TJ permeability. The colonic mucosa of mice injected with IL-6 also exhibits an increase in claudin-2 expression. The claudin-2 expression and TJ permeability induced by IL-6 are sensitive to the inhibition of gp130, MEK, and PI3K. Furthermore, expression of WT-MEK1 induces claudin-2 expression in Caco-2 cells. Claudin-2 promoter activity is increased by IL-6 in a MEK/ERK and PI3K-dependent manner, and deletion of Cdx binding sites in the promoter sequence results in a loss of IL-6-induced promoter activity. IL-6 increases Cdx2 protein expression, which is suppressed by the inhibition of MEK and PI3K. These observations may reveal an important mechanism by which IL-6 can undermine the integrity of the intestinal barrier.

Increase in Dendritic Cell Migration Markers CCR7 and CCR9 in the Neo-Terminal Ileum of Postoperative Crohn's Disease: An Adaptive Response to Bacterial Exposure?

Introduction Gut dendritic cells (DCs) are crucial in bacterial recognition, T cell signalling and inflammatory regulation. DC TLR expression is altered in CD: increased on myeloid DC (MDC) in colonic CD and reduced on plasmacytoid DCs (PDC) in postoperative CD (POCD) ileum. In active CD, peripheral CD4 and CD8 T cells showed increased intestinal homing with high CCR9 levels. In Crohn9s colonic tissues, CCR7, a homing marker crucial for DC trafficking to mesenteric lymph nodes, was elevated compared with controls. Additionally CCR7 expression on MDC is higher in ileal compared with colonic tissue in CD. CCR7 and CCR9 expression on DC in POCD is unknown. After ileo-caecal resection the neo-terminal ileum is exposed to the bacteria rich contents of the colon. The authors hypothesise that alteration in gut microflora after surgery may modulate expression of homing markers on DC from POCD patients. The authors aimed to examine homing marker expression on MDC and PDC from the ileum and the colon in healthy controls (HC) and POCD patients. Methods HC and POCD patients were identified at colonoscopy. Intestinal lamina propria mononuclear cells were collected using collagenase digestion and labelled with directly conjugated monoclonal antibodies to CCR7 and 9. PDC and MDC were characterised as CD11c+ve and –ve respectively and expression of CCR7 and 9 by multicolour flow cytometry measured. Statistical analysis was via unpaired t tests. In experiments with paired colonic and ileal samples paired t tests were performed. Results In paired samples, HC ileal CCR9+ve PDC concentrations were lower than colonic PDC (26.46±10.43/ml SEM vs 53.76±20.16/ml SEM, p There were significantly higher concentrations of CCR9+ve and CCR7+ve PDCs within ileal POCD compared with ileum normal controls (103.8±22.64/ml vs 37.68±7.434/ml, p=0.039 and 117.4±26.97/ml SEM vs 40.47±3.97/ml SEM, p=0.03). No differences in MDC concentrations of both homing markers in all types of tissue existed. Conclusion POCD neo-terminal ileum showed higher CCR7+ve and CCR9+ve PDC than normal ileum. This novel finding indicates a potential role for PDC in CD pathogenesis. The loss of the ileocaecal valve in POCD may alter microbiota flora exposure in the ileum with an adaptive response of CCR9+ve DC to a level seen in normal colonic tissue. Additionally, this may induce migration of PDC by upregulation of CCR7 expression. Further studies to examine the changes with disease progression may unravel the function of PDC in ileal POCD tissues.

Aryl Hydrocarbon Receptor-Induced Signals Up-regulate IL-22 Production and Inhibit Inflammation in the Gastrointestinal Tract

The pathogenesis of inflammatory bowel disease (IBD) is believed to involve an altered balance between effector and regulatory T cells. Aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor that mediates the toxicity of dioxins, controls T-cell responses. We investigated the role of AhR in inflammation and pathogenesis of IBD in humans and mouse models. AhR expression was evaluated in intestinal tissue samples from patients with IBD and controls by real-time polymerase chain reaction (PCR) and flow cytometry. Intestinal lamina propria mononuclear cells (LPMCs) were activated in the presence or absence of the AhR agonist 6-formylindolo(3, 2-b)carbazole (Ficz). Colitis was induced in mice using trinitrobenzene sulfonic acid (TNBS), dextran sulfate sodium (DSS), or T-cell transfer. Mice were given injections of Ficz or the AhR antagonist 2-metyl-2H-pyrazole-3-carboxylic acid; some mice first received injections of a blocking antibody against interleukin (IL)-22. Cytokines were quantified by real-time PCR and flow cytometry. Intestine tissue from patients with IBD expressed significantly less AhR than controls. In LPMCs from patients with IBD, incubation with Ficz reduced levels of interferon gamma (IFN)-γ and up-regulated IL-22. Mice injected with Ficz were protected against TNBS-, DSS-, and T-cell transfer-induced colitis; they had marked down-regulation of inflammatory cytokines and induction of IL-22. Mice given AhR antagonist produced more inflammatory cytokines and less IL-22 and developed a severe colitis. Neutralization of endogenous IL-22 disrupted the protective effect of Ficz on TNBS-induced colitis. AhR is down-regulated in intestinal tissue of patients with IBD; AhR signaling, via IL-22, inhibits inflammation and colitis in the gastrointestinal tract of mice. AhR-related compounds might be developed to treat patients with IBDs.

Increase in dendritic cell migration markers CCR7 and CCR9 in the neo-terminal ileum of postoperative crohn's disease: an adaptive response to bacterial exposure?

IntroductionGut dendritic cells (DCs) are crucial in bacterial recognition, T cell signalling and inflammatory regulation. DC TLR expression is altered in CD: increased on myeloid DC (MDC) in colonic CD...

Expression of co-stimulators in ulcerative colitis and its pathologic significance

To study the expression and localization of co-stimulators in the mucosa of patients with ulcerative colitis (UC), and to explore its role in the pathogenesis of UC. Expression of co-stimulators CD86 and inducible co-stimulator (ICOS) was studied by immunohistochemistry on paraffin-embedded mucosal tissue from patients with active UC (64 cases), inactive UC (51 cases) and normal controls (20 cases). Immunostaining for CD28 was also carried out on frozen fresh mucosal tissue sampled from patients with active UC (7 cases), inactive UC (2 cases) and normal controls (5 cases). In addition, expression of CD4, CD8 and CD20 were also examined. In active UC, increased expression of CD86 was not only observed in lamina propria mononuclear cells but also in the intestinal epithelial cells, as compared with inactive UC and the normal controls (P < 0.01). Increased ICOS expression in lamina propria mononuclear cells was detected in active UC, as compared with inactive UC and the normal controls (P < 0.01). Increased ICOS expression in intestinal epithelial cells was also seen in active UC, as compared with that of inactive UC (P < 0.01). The expression of CD86 was higher in inactive UC than in the normal controls (P < 0.05 or P < 0.01). However, the expression of ICOS showed no statistically significant difference between inactive UC and normal controls. Increased expression of CD28 in active UC, compared with that in inactive UC and normal controls, was also noticed (P < 0.05 or P < 0.01). The number of CD4 or CD8-positive intraepithelial lymphocytes and lymphocytes infiltrating in the lamina propria and small vessel walls was much higher in active UC than in inactive UC and normal controls (P < 0.01). Moreover, the ratio of CD4/CD8 was highest in active UC (P < 0.01). The number of CD20-positive B lymphocytes in lamina propria was also higher in active UC than in inactive UC and normal controls (P < 0.01). In active UC, CD86 and ICOS were over-expressed in the intestinal epithelial cells and lamina propria mononuclear cells. The phenomenon suggests that abnormal expression of co-stimulators may contribute to the deregulation of acquired immune responses in UC.

Interleukin-25 Inhibits Interleukin-12 Production and Th1 Cell-Driven Inflammation in the Gut

During the pathogenesis of Crohn's disease (CD), interleukin (IL)-12, a cytokine produced by mucosal CD14+ monocyte-like cells, promotes tissue-damaging T helper cell (Th) 1-mediated inflammation through mechanisms that are not fully understood. IL-25 promotes Th2 cell responses by activating major histocompatibility complex class II-positive non-T and non-B cells. Because Th1 and Th2 cells, and the cytokines they release, are often mutually antagonistic, we examined whether IL-25 affects IL-12 production or Th1 cell-mediated inflammation in the gut. Studies were performed using colonic samples from patients and mice with peptidoglycan (PGN)-, 2,4,6-trinitrobenzenesulphonic acid (TNBS)-, or oxazolone-induced colitis. IL-25 receptor (IL-25R) levels were evaluated in intestinal lamina propria mononuclear cells by flow cytometry, and IL-25 levels were measured by real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. Mucosal CD14+ cells from patients with CD were incubated with IL-25 and/or lipopolysaccharide or PGN. Mice were injected with IL-25, and some mice first received injections of an IL-13 blocking antibody. Cytokines were quantified by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. CD14+ cells from the mucosa of CD patients expressed IL-25R and responded to IL-25 by decreasing the synthesis of IL-12 and IL-23. IL-25 prevented PGN-induced colitis in mice. IL-25 induced IL-13 production in the colon, but IL-13 was not required for suppression of PGN colitis. IL-25 ameliorated TNBS- and oxazolone-colitis. Patients with CD or ulcerative colitis produced significantly less IL-25 compared with controls. IL-25 inhibits CD14+ cell-derived cytokines and experimental colitis. IL-25 could be a useful treatment of CD and ulcerative colitis.

Reduced expression of basal and probiotic-inducible G-CSF in intestinal mononuclear cells is associated with inflammatory bowel disease

Granulocyte-colony stimulating factor (G-CSF) is a pleiotropic cytokine involved in the hematopoiesis of granulocytes, neuroprotection, and immunomodulation. Previously, we have shown that probiotic Lactobacillus rhamnosus GR-1 induces G-CSF production from bone marrow-derived macrophages. Whether this probiotic also induces G-CSF in intestinal mononuclear cells is unknown. G-CSF release in response to L. rhamnosus GR-1 was analyzed in isolated intestinal lamina propria mononuclear cells from inflammatory bowel disease (IBD) and non-IBD patients. The effects of G-CSF on proinflammatory cytokine production in human peripheral blood mononuclear cells and intestinal tissue from C57BL/6 wildtype and G-CSF receptor knockout mice was examined. Normal mouse or human intestinal lamina propria cells constitutively express high levels of G-CSF, of which production was further enhanced by exogenous L. rhamnosus GR-1. However, cells obtained from IBD patients showed reduced G-CSF production under basal conditions and also lower production after exogenous GR-1 treatments. Intestinal tissue samples isolated from G-CSF receptor-deficient mice constitutively expressed higher levels of TNFalpha, IL-23, and IL-12 than those from wildtype mice, and pretreatment of G-CSF suppressed lipopolysaccharide (LPS)-induced IL-23 in human peripheral blood mononuclear cells. These results suggest that high G-CSF production induced by commensals such as L. rhamnosus is important in maintaining normal immunological homeostasis in the intestine and defects in the production of G-CSF are associated with IBD.