Defective IL-10 production in severe phenotypes of Crohn's disease

Molecular and cellular factors determining the functional pleiotropy of cytokines

Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.

Macrophages-microenvironment crosstalk in fibrostenotic inflammatory bowel disease: from basic mechanisms to clinical applications

INTRODUCTION

Intestinal fibrosis is a common complication of Inflammatory Bowel Disease (IBD) with no available drugs. The current therapeutic principle is surgical intervention as the core. Intestinal macrophages contribute to both the progression of inflammation and fibrosis. Understanding the role of macrophages in the intestinal microenvironment could bring new hope for fibrosis prevention or even reversal.

AREAS COVERED

This article reviewed the most relevant reports on macrophage in the field of intestinal fibrosis. The authors discussed current opinions about how intestinal macrophages function and interact with surrounding mediators during inflammation resolution and fibrostenotic IBD. Based on biological mechanisms findings, authors summarized related clinical trial outcomes.

EXPERT OPINION

The plasticity of intestinal macrophages allows them to undergo dramatic alterations in their phenotypes or functions when exposed to gastrointestinal environmental stimuli. They exhibit distinct metabolic characteristics, secrete various cytokines, express unique surface markers, and transmit different signals. Nevertheless, the specific mechanism through which the intestinal macrophages contribute to intestinal fibrosis remains unclear. It should further elucidate a novel therapeutic approach by targeting macrophages, especially distinct mechanisms in specific subgroups of macrophages involved in the progression of fibrogenesis in IBD.

Mucosal Interleukin‐10 depletion in steroid‐refractory Crohn's disease patients

Background

Previous studies suggested that Interleukin‐10 (IL‐10) depletion in Crohn's disease (CD) could predict outcome. Aim: To determine IL‐10 in blood and at different intestinal locations in patients with active CD and to assess its potential prognostic capacity to identify aggressive CD.

Methods

Twenty‐three patients with CD were included. Ulcerative colitis (UC), infectious colitis and healthy individuals acted as controls. Serum and mucosal samples were taken at baseline and 1 month after steroid initiation in CD patients. Patients were classified according to steroid response. Control samples were obtained from different intestinal locations. IL‐10 expression was measured with real‐time polymerase chain reaction, immunofluorescence (intestine) and ELISA (serum, biopsy cultures' supernatants and tissue homogenates).

Results

CD and UC showed an increase in IL‐10 messenger RNA (mRNA) versus controls (p < .0001) in mucosa, whereas IL‐10 protein secretion was increased in all types of intestinal inflammation (p < .001). No differences in IL‐10 mRNA were found in CD at baseline regarding steroid response, but levels decreased in non‐responders versus responders (p = .027) and were restored with rescue therapy. Serum IL‐10 was increased in steroid‐refractory CD at baseline and after treatment.

Conclusions

Abnormal IL‐10 levels in refractory patients in both mucosa and blood have physiopathological relevance and may have potential clinical applications.

Immunomodulatory Effects of Lepidium meyenii Walp. Polysaccharides on an Immunosuppression Model Induced by Cyclophosphamide

Background

Lepidium meyenii Walp. (Maca) has emerged as a functional plant food and traditional herb owing to its biological activities; Maca polysaccharides as an important active component of Maca have good immunomodulatory effect; however, studies on the immunomodulatory effect of Maca polysaccharides are mainly focused on macrophages; little attention has been devoted to the mechanisms and other immune cells. This study is aimed at investigating the immunomodulatory effects and mechanisms of Maca polysaccharides.

Methods

Sixty mice were divided into five groups, and the mice were injected with cyclophosphamide to establish an immunosuppression model except for those in the common group. The body weights were measured, as well as immune-related indices, such as organ indices, haematological parameters, lymphocyte cycle, and proliferation, cytokine, and protein expression levels.

Results

The weight loss and immune organ index decline caused by cyclophosphamide could be reversed by MP. Furthermore, MP increased WBC and HGB counts and reduced the ratio of G0/G1 phase obviously, increased the proportion of S phase and G2/M phase in peripheral blood lymphocytes, increased the counts of CD4+ T cells and the ratio of CD4+/CD8+, and reduced the inhibition rate of splenic lymphocytes. MP affected the production of cytokines by increasing IFN-γ, TNF-α, and IL-2 levels and by decreasing IL-4 levels. MP increased the mRNA expression of T-bet and the protein expression of Bcl-2 in the spleen and decreased the protein expression of caspase-3 and Bax.

Conclusions

Maca polysaccharides might be the basic material for Maca's immunomodulatory effect. The mechanism was perhaps related to inhibiting lymphocyte apoptosis and promoting the balance of Th1/Th2 cell subsets.

IL-10 Receptor Blockade Delivered Simultaneously with Bacillus Calmette-Guérin Vaccination Sustains Long-Term Protection against Mycobacterium tuberculosis Infection in Mice

Mycobacterium bovis bacillus Calmette-Guérin (BCG) immunization still remains the best vaccination strategy available to control the development of active tuberculosis. Protection afforded by BCG vaccination gradually wanes over time and although booster strategies have promise, they remain under development. An alternative approach is to improve BCG efficacy through host-directed therapy. Building upon prior knowledge that blockade of IL-10R1 during early Mycobacterium tuberculosis infection improves and extends control of M. tuberculosis infection in mice, we employed a combined anti-IL-10R1/BCG vaccine strategy. An s.c. single vaccination of BCG/anti-IL10-R1 increased the numbers of CD4+ and CD8+ central memory T cells and reduced Th1 and Th17 cytokine levels in the lung for up to 7 wk postvaccination. Subsequent M. tuberculosis challenge in mice showed both an early (4 wk) and sustained long-term (47 wk) control of infection, which was associated with increased survival. In contrast, protection of BCG/saline-vaccinated mice waned 8 wk after M. tuberculosis infection. Our findings demonstrate that a single and simultaneous vaccination with BCG/anti-IL10-R1 sustains long-term protection, identifying a promising approach to enhance and extend the current BCG-mediated protection against TB.

Neuroinflammation as an etiological trigger for depression comorbid with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) suffer from depression at higher rates than the general population. An etiological trigger of depressive symptoms is theorised to be inflammation within the central nervous system. It is believed that heightened intestinal inflammation and dysfunction of the enteric nervous system (ENS) contribute to impaired intestinal permeability, which facilitates the translocation of intestinal enterotoxins into the blood circulation. Consequently, these may compromise the immunological and physiological functioning of distant non-intestinal tissues such as the brain. In vivo models of colitis provide evidence of increased blood–brain barrier permeability and enhanced central nervous system (CNS) immune activity triggered by intestinal enterotoxins and blood-borne inflammatory mediators. Understanding the immunological, physiological, and structural changes associated with IBD and neuroinflammation may aid in the development of more tailored and suitable pharmaceutical treatment for IBD-associated depression.

HG-9-91-01 Attenuates Murine Experimental Colitis by Promoting Interleukin-10 Production in Colonic Macrophages Through the SIK/CRTC3 Pathway

BACKGROUND

Interleukin-10 (IL-10) is a potent immunoregulatory cytokine that plays a pivotal role in maintaining mucosal immune homeostasis. As a novel synthetic inhibitor of salt-inducible kinases (SIKs), HG-9-91-01 can effectively enhance IL-10 secretion at the cellular level, but its in vivo immunoregulatory effects remain unclear. In this study, we investigated the effects and underlying mechanism of HG-9-91-01 in murine colitis models.

METHODS

The anti-inflammatory effects of HG-9-91-01 were evaluated on 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-, dextran sulfate sodium-induced colitis mice, and IL-10 knockout chronic colitis mice. The in vivo effector cell of HG-9-91-01 was identified by fluorescence-activated cell sorting and quantitative real-time polymerase chain reaction. The underlying mechanism of HG-9-91-01 was investigated via overexpressing SIKs in ANA-1 macrophages and TNBS colitis mice.

RESULTS

Treatment with HG-9-91-01 showed favorable anticolitis effects in both TNBS- and DSS-treated mice through significantly promoting IL-10 expression in colonic macrophages but failed to protect against IL-10 KO murine colitis. Further study indicated that HG-9-91-01 markedly enhanced the nuclear level of cAMP response element-binding protein (CREB)-regulated transcription coactivator 3 (CRTC3), whereas treatment with lentiviruses encoding SIK protein markedly decreased the nuclear CRTC3 level in HG-9-91-01-treated ANA-1 macrophages. In addition, intracolonic administration with lentiviruses encoding SIK protein significantly decreased the nuclear CRTC3 level in the lamina propria mononuclear cells and ended the anti-inflammatory activities of HG-9-91-01.

CONCLUSIONS

We found that HG-9-91-01 promoted the IL-10 expression of colonic macrophages and exhibited its anticolitis activity through the SIK/CRTC3 axis, and thus it may represent a promising strategy for inflammatory bowel disease therapy.

Association between IL-10 rs3024505 and susceptibility to inflammatory bowel disease: A systematic review and meta-analysis

Inflammatory bowel disease (IBD) is a chronic inflammatory disease that affects the small intestine, colon, and rectum. We evaluated associations between the interleukin 10 (IL-10) rs3024505 polymorphism and IBD, ulcerative colitis (UC), and Crohn's disease (CD) by meta-analysis. All peer-reviewed manuscripts concerning the relationship between IL-10_rs3024505 and IBD identified by searing the PubMed, Cochrane Library, EMBASE, and Chinese Medical Database were examined. The association between IL-10_rs3024505 and IBD was evaluated in allele (AG), recessive (RG), dominant (DG), homozygous (HMG), and heterozygous (HTG) genetic models. Associations were also conducted on IBD subtypes, CD and UC, and ethnicity (Non-Europeans and Europeans) subgroups. The meta-analysis included 13 studies, 8552 cases (IBD patients), and 12,830 healthy controls. Subgroup analysis of IBD (UC and CD) revealed heterogeneity in AG, DG, and HTG but no heterogeneity in RG or HMG. Moreover, AG, DG, and HTG did not show publication bias in IBD, CD, or UC, but RG and HMG exhibited publication bias. No heterogeneity and no publication bias were found among the five genetic models by a subgroup analysis of Non-Europeans and European ethnicities. The minor allele(T) of rs3024505 was significantly related to IBD: 1.37 (1.30-1.45) for AG, 2.06 (1.74-2.45) for RG, 1.39 (1.27-1.52) for DG, 2.25 (1.89-2.67) for HMG, and 1.32 (1.23-1.40) for HTG (all P < 0.00001). In the subgroup analysis of ethnicity, there was a significant effect of rs3024505 on IBD in Europeans but not non-Europeans: 1.38 (1.31-1.46) for AG, 2.07 (1.73-2.48) for RG, 1.39 (1.31-1.49) for DG, 2.26 (1.89-2.71) for HMG, and 1.33 (1.24-1.42) for HTG in Europeans (all P < 0.00001). Sensitivity analysis showed no dominant study in Europeans, but one study had a dominant impact in Non-Europeans. In conclusion, IL-10_rs3024505 polymorphism confers susceptibility to CD and UC in Europeans, but its impact should have conducted more studies in Non-Europeans.

Development of Anti-fibrotic Therapy in Stricturing Crohn's Disease: Lessons from Randomized Trials in Other Fibrotic Diseases

Intestinal fibrosis is considered an inevitable complication of Crohn's disease (CD) that results in symptoms of obstruction and stricture formation. Endoscopic or surgical treatment is required to treat the majority of patients. Progress in the management of stricturing CD is hampered by the lack of effective anti-fibrotic therapy; however, this situation is likely to change because of recent advances in other fibrotic diseases of the lung, liver and skin. In this review, we summarized data from randomized controlled trials (RCT) of anti-fibrotic therapies in these conditions. Multiple compounds have been tested for the anti-fibrotic effects in other organs. According to their mechanisms, they were categorized into growth factor modulators, inflammation modulators, 5-hydroxy-3-methylgultaryl-coenzyme A (HMG-CoA) reductase inhibitors, intracellular enzymes and kinases, renin-angiotensin system (RAS) modulators and others. From our review of the results from the clinical trials and discussion of their implications in the gastrointestinal tract, we have identified several molecular candidates that could serve as potential therapies for intestinal fibrosis in CD.

Role of Goblet Cells in Intestinal Barrier and Mucosal Immunity

Goblet cells and the mucus they secrete serve as an important barrier, preventing pathogens from invading the mucosa to cause intestinal inflammation. The perspective regarding goblet cells and mucus has changed, with current evidence suggesting that they are not passive but play a positive role in maintaining intestinal tract immunity and mucosal homeostasis. Goblet cells could obtain luminal antigens, presenting them to the underlying antigen-presenting cells (APCs) that induces adaptive immune responses. Various immunomodulatory factors can promote the differentiation and maturation of goblet cells, and the secretion of mucin. The abnormal proliferation and differentiation of goblet cells, as well as the deficiency synthesis and secretion of mucins, result in intestinal mucosal barrier dysfunction. This review provides an extensive outline of the signaling pathways that regulate goblet cell proliferation and differentiation and control mucins synthesis and secretion to elucidate how altering these pathways affects goblet functionality. Furthermore, the interaction between mucins and goblet cells in intestinal mucosal immunology is described. Therefore, the contribution of goblet cells and mucus in promoting gut defense and homeostasis is illustrated, while clarifying the regulatory mechanisms involved may allow the development of new therapeutic strategies for intestinal disorders.

Association of Serum Immunoglobulins Levels With Specific Disease Phenotypes of Crohn's Disease: A Multicenter Analysis in China

Background and Aim: Serum immunoglobulins were reported to be associated with clinical characteristics of inflammatory bowel disease. However, whether a difference exists in the serum immunoglobulins levels in patients with Crohn's disease (CD) with different disease location and behavior phenotypes remains unclear. Therefore, this study aimed to explore the associations of serum immunoglobulins levels with specific CD phenotypes. Methods: Patients with CD having recorded serum immunoglobulins levels were recruited through multicenter collaborative efforts. The associations between serum immunoglobulins levels and distinct phenotypes of CD were evaluated using multiple logistic regression models. Results: A total of 608 patients with CD were included in the study. Elevated (above the upper limit of normal) serum immunoglobulin G (IgG), IgA, IgM, and IgG4 were identified in 24.5, 17.4, 2.1, and 8.2% of patients, respectively. Elevated serum IgG4 levels negatively correlated with complicated disease behavior [odds ratio (OR) 0.49, 95% confidence interval (CI) 0.26-0.92]. Elevated serum IgG was linked to isolated ileal disease with an OR of 0.37 (95% CI 0.23-0.61). The ORs of isolated ileal disease progressively reduced across increasing quartiles of IgG (P for trend < 0.001). The adjusted ORs of isolated ileal disease for increasing quartiles of IgM were 1.82 (1.07-3.1), 1.92 (1.14-3.24), 1.17 (0.69-1.98), and 1 (P for trend = 0.008). Besides, serum IgA and IgG levels significantly correlated with several disease activity indices. Conclusions: These results suggested that certain serum immunoglobulins were associated with specific disease phenotypes of CD. Further investigations to account for the associations are warranted.

Nonclostridium difficile enteric infection and the risk of developing inflammatory bowel disease: A systematic review and meta-analysis

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory intestinal disorder. Some studies have investigated the association between non-Clostridium difficile infection (CDI) enteric infection and the risk of developing IBD with conflicting conclusions. The objective of our study was to perform a meta-analysis of available studies evaluating the possible association between non-CDI enteric infection and the risk of developing IBD.

METHODS

We performed a systematic literature search of multiple online electronic databases. Inclusion criteria entailed studies about non-CDI enteric infection and IBD; A meta-analysis was conducted to evaluate relative risk (RR) and 95% confidence intervals (CIs) of combined studies for the association between non-CDI enteric infection and the risk of developing IBD. Publication bias was assessed by funnel plot analysis.

RESULTS

Eight studies comprising 345,490 enteric infected patients, 3223 ulcerative colitis (UC) patients, and 2133 CD patients were included in the meta-analysis. Meta-analysis showed a significantly higher risk of UC in patients with enteric infection compared with noninfected patients (RR, 2.28; 95% CI, 1.85-2.8) (I2 = 91.3%, P < 0.001). It also showed a significantly higher risk of CD in patients with enteric infection compared with noninfected patients (RR, 1.88; 95% CI, 1.66-2.14) (I2 = 49%, P = 0.024).

CONCLUSION

Our meta-analysis has found that patients with non-CDI enteric infection were associated with an increased risk of IBD. Future studies are needed to determine the association between non-CDI enteric infection and the risk of developing IBD and elucidate the potential underlying mechanisms.

Engineered IL-10 variants elicit potent immunomodulatory effects at low ligand doses

Interleukin-10 (IL-10) is a dimeric cytokine with both immunosuppressive and immunostimulatory activities; however, IL-10-based therapies have shown only marginal clinical benefits. Here, we explored whether the stability of the IL-10 receptor complex contributes to the immunomodulatory potency of IL-10. We generated an IL-10 mutant with enhanced affinity for its IL-10Rβ receptor using yeast surface display. Compared to the wild-type cytokine, the affinity-enhanced IL-10 variants recruited IL-10Rβ more efficiently into active cell surface signaling complexes and triggered greater STAT1 and STAT3 activation in human monocytes and CD8⁺ T cells. These effects, in turn, led to more robust induction of IL-10-mediated gene expression programs at low ligand concentrations in both human cell subsets. IL-10-regulated genes are involved in monocyte energy homeostasis, migration, and trafficking and in CD8⁺ T cell exhaustion. At nonsaturating doses, IL-10 did not induce key components of its gene expression program, which may explain its lack of efficacy in clinical settings. Our engineered IL-10 variant showed a more robust bioactivity profile than that of wild-type IL-10 at low doses in monocytes and CD8⁺ T cells. Moreover, CAR-modified T cells expanded with the engineered IL-10 variant displayed superior cytolytic activity than those expanded with wild-type IL-10. Our study provides insights into how IL-10 receptor complex stability fine-tunes IL-10 biology and opens new opportunities to revitalize failed IL-10 therapies.

The Role of the Anti-Inflammatory Cytokine Interleukin-10 in Tissue Fibrosis

Significance: Fibrosis is the endpoint of chronic disease in multiple organs, including the skin, heart, lungs, intestine, liver, and kidneys. Pathologic accumulation of fibrotic tissue results in a loss of structural integrity and function, with resultant increases in morbidity and mortality. Understanding the pathways governing fibrosis and identifying therapeutic targets within those pathways is necessary to develop novel antifibrotic therapies for fibrotic disease. Recent Advances: Given the connection between inflammation and fibrogenesis, Interleukin-10 (IL-10) has been a focus of potential antifibrotic therapies because of its well-known role as an anti-inflammatory mediator. Despite the apparent dissimilarity of diseases associated with fibrotic progression, pathways involving IL-10 appear to be a conserved molecular theme. More recently, many groups have worked to develop novel delivery tools for recombinant IL-10, such as hydrogels, and cell-based therapies, such as ex vivo activated macrophages, to directly or indirectly modulate IL-10 signaling. Critical Issues: Some efforts in this area, however, have been stymied by IL-10's pleiotropic and sometimes conflicting effects. A deeper, contextual understanding of IL-10 signaling and its interaction with effector cells, particularly immune cells, will be critical to future studies in the field. Future Directions: IL-10 is clearly a gatekeeper of fibrotic/antifibrotic signaling. The development of novel therapeutics and cell-based therapies that capitalize on targets within the IL-10 signaling pathway could have far-reaching implications for patients suffering from the consequences of organ fibrosis.

IL-10 Impairs Local Immune Response in Lung Granulomas and Lymph Nodes during Early Mycobacterium tuberculosis Infection

Tuberculosis (TB), caused by Mycobacterium tuberculosis, continues to be a major global health problem. Lung granulomas are organized structures of host immune cells that function to contain the bacteria. Cytokine expression is a critical component of the protective immune response, but inappropriate cytokine expression can exacerbate TB. Although the importance of proinflammatory cytokines in controlling M. tuberculosis infection has been established, the effects of anti-inflammatory cytokines, such as IL-10, in TB are less well understood. To investigate the role of IL-10, we used an Ab to neutralize IL-10 in cynomolgus macaques during M. tuberculosis infection. Anti-IL-10-treated nonhuman primates had similar overall disease outcomes compared with untreated control nonhuman primates, but there were immunological changes in granulomas and lymph nodes from anti-IL-10-treated animals. There was less thoracic inflammation and increased cytokine production in lung granulomas and lymph nodes from IL-10-neutralized animals at 3-4 wk postinfection compared with control animals. At 8 wk postinfection, lung granulomas from IL-10-neutralized animals had reduced cytokine production but increased fibrosis relative to control animals. Although these immunological changes did not affect the overall disease burden during the first 8 wk of infection, we paired computational modeling to explore late infection dynamics. Our findings support that early changes occurring in the absence of IL-10 may lead to better bacterial control later during infection. These unique datasets provide insight into the contribution of IL-10 to the immunological balance necessary for granulomas to control bacterial burden and disease pathology in M. tuberculosis infection.

Viewpoint: Toward the Genetic Architecture of Disease Severity in Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) is characterized by uneven disease courses with various clinical outcomes. A few prognostic markers of disease severity may help stratify patients and identify those who will benefit the most from early aggressive treatment. The concept of disease severity remains too broad and vague, mainly because the definition must embrace several disease mechanisms, mainly inflammation and fibrosis, with various rates of disease progression. The magnitude of inflammation is an obvious key driver of disease severity in IBD that ultimately influence disease behavior. Advances in the genetics underlying disease severity are currently emerging, but attempts to overlap the genetics of disease susceptibility and severity have until now been unsatisfactory, suggesting that the genetic architecture of disease severity may be distinct from the genetics of disease susceptibility. In this review, we report on the current knowledge on disease severity and on the main research venues to decipher the genetic architecture of disease severity.

Absence of specific alternatively spliced exon of CD44 in macrophages prevents colitis

CD44 is a transmembrane molecule appearing in numerous isoforms generated by insertions of alternatively spliced variant exons (CD44v) and having various binding partners. CD44v7 on T cells was proposed to promote colitis by preventing T-cell apoptosis. Here we demonstrate that Cd44v7-deficient T cells - like Cd44 wild-type (Cd44^WT) T cells - provoked disease in two different colitis models: the model induced by CD4⁺CD45RB^high T-cell transfer into Rag2-deficient mice and a new model based on ovalbumin (OVA)-specific T-cell transfer into Rag-sufficient, OVA-challenged mice. In contrast, CD44v7 absence on macrophages in recipient mice prevented colitis. Prevention was associated with the downregulation of signal transducer and activator of transcription 3 (STAT3)-activating and Foxp3-counteracting interleukin-6 (IL-6), lower numbers of phospho-STAT3-containing lymphocytes, and higher Foxp3⁺ T-cell counts in the colon. Consequently, the protected colons showed lower IL-12, IL-1β expression, and decreased interferon-γ levels. Importantly, stimulation of T cells by Cd44v7-deficient macrophages induced upregulation of Foxp3 in vitro, while cotransfer of Cd44^WT macrophages into Cd44v7-deficient mice reduced Foxp3⁺ T-cell counts and caused colitis. Accordingly, the CD44v7 ligand osteopontin, whose levels were elevated in Crohn's disease, specifically induced IL-6 in human monocytes, a cytokine also increased in these patients. We suggest macrophage-specific targeting of the CD44v7 pathway as a novel therapeutic option for Crohn's disease.

Adeno-associated virus-mediated colonic secretory expression of HMGB1 A box attenuates experimental colitis in mice

BACKGROUND

Extracellular high mobility group box 1 (HMGB1) is crucially implicated in the pathogenesis of inflammatory bowel diseases (IBDs). A box domain of HMGB1 has been identified as a specific antagonist of HMGB1. In the present study, we tested the effects of adeno-associated virus (AAV)-mediated colonic secretory expression of HMGB1 A box on murine experimental colitis.

METHODS

Self-complementary AAV-2 carrying mouse immunoglobin Gκ leader-human HMGB1 A box (AAV-HMGB1 A box) was constructed. The effects of intracolonically administered AAV-HMGB1 A box on dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis were assessed by the disease activity index (DAI), colon length, macroscopic and histological scoring, myeloperoxidase (MPO) activity, and epithelial apoptosis and complementary proliferation. Colonic immune cell infiltrates, mucosal malondialdehyde content and superoxide dismutase activity, colonic tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-10 levels, serum HMGB1 concentration, and colonic HMGB1 release were determined to investigate the underlying mechanisms.

RESULTS

Intracolonically administered AAV-HMGB1 A box efficiently mediated secretory expression of HMGB1 A box and led to significant decreases in DAI, macroscopic and histological scores and colonic epithelial apoptosis in both DSS- and TNBS-treated mice. Modulating inflammation-associated cytokines, such as inhibiting colonic TNF-α and IL-1β expression, decreasing HMGB1 release, and restoring colonic IL-10 levels, and thereby inhibiting inflammatory cell infiltration and alleviating oxidant damage, might be the underlying mechanism.

CONCLUSIONS

Intracolonic application of AAV-HMGB1 A box is effective in alleviating murine colitis and has therapeutic potential in human IBDs.

Recombinant adeno-associated virus carrying thymosin β4 suppresses experimental colitis in mice

AIM

To investigate the protective effect of a recombinant adeno-associated virus carrying thymosin β₄ (AAV-Tβ₄) on murine colitis via intracolonic administration.

METHODS

AAV-Tβ₄ was prepared and intracolonically used to mediate the secretory expression of Tβ₄ in mouse colons. Dextran sulfate sodium (DSS) was applied to induce the murine ulcerative colitis, and 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to establish a mouse colitis model resembling Crohn’s disease. The disease severity and colon injuries were observed and graded to reveal the effects of AAV-Tβ₄ on colitis. The activities of myeloperoxidase (MPO) and superoxide dismutase (SOD) and the content of malondialdehyde (MDA) were determined using biochemical assays. Colonic levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-10 were measured using ELISA, and mucosal epithelial cell apoptosis and proliferation were detected by TUNEL assay and immunochemistry, respectively.

RESULTS

Recombinant AAVs efficiently delivered LacZ and Tβ₄ into the colonic tissues of the mice, and AAV-Tβ₄ led to a strong expression of Tβ₄ in mouse colons. In both the DSS and TNBS colitis models, AAV-Tβ₄-treated mice displayed distinctly attenuated colon injuries and reduced apoptosis rate of colonic mucosal epithelia. AAV-Tβ₄ significantly reduced inflammatory cell infiltrations and relieved oxidative stress in the inflamed colons of the mice, as evidenced by decreases in MPO activity and MDA content and increases in SOD activity. AAV-Tβ₄ also modulated colonic TNF-α, IL-1β and IL-10 levels and suppressed the compensatory proliferation of colonic epithelial cells in DSS- and TNBS-treated mice.

CONCLUSION

Tβ₄ exerts a protective effect on murine colitis, indicating that AAV-Tβ₄ could potentially be developed into a promising agent for the therapy of inflammatory bowel diseases.

Metformin Improves Ileal Epithelial Barrier Function in Interleukin-10 Deficient Mice

Background and aims

The impairment of intestinal epithelial barrier is the main etiologic factor of inflammatory bowel disease. The proper intestinal epithelial proliferation and differentiation is crucial for maintaining intestinal integrity. Metformin is a common anti-diabetic drug. The objective is to evaluate the protective effects of metformin on ileal epithelial barrier integrity using interleukin-10 deficient (IL10KO) mice.

Methods

Wild-type and IL10KO mice were fed with/without metformin for 6 weeks and then ileum was collected for analyses. The mediatory role of AMP-activated protein kinase (AMPK) was further examined by gain and loss of function study in vitro.

Results

Compared to wild-type mice, IL10KO mice had increased proliferation, reduced goblet cell and Paneth cell lineage differentiation in the ileum tissue, which was accompanied with increased crypt expansion. Metformin supplementation mitigated intestinal cell proliferation, restored villus/crypt ratio, increased goblet cell and Paneth cell differentiation and improved barrier function. In addition, metformin supplementation in IL10KO mice suppressed macrophage pro-inflammatory activity as indicated by reduced M1 macrophage abundance and decreased pro-inflammatory cytokine IL-1β, TNF-α and IFN-γ expressions. As a target of metformin, AMPK phosphorylation was enhanced in mice treated with metformin, regardless of mouse genotypes. In correlation, the mRNA level of differentiation regulator including bmp4, bmpr2 and math1 were also increased in IL10KO mice supplemented with metformin, which likely explains the enhanced epithelial differentiation in IL10KO mice with metformin. Consistently, in Caco-2 cells, metformin promoted claudin-3 and E-cadherin assembly and mitigated TNF-α-induced fragmentation of tight junction proteins. Gain and loss of function assay also demonstrated AMPK was correlated with epithelial differentiation and proliferation.

Conclusions

Metformin supplementation promotes secretory cell lineage differentiation, suppresses inflammation and improves epithelial barrier function in IL10KO mice likely through activation of AMPK, showing its beneficial effects on gut epithelial.

Transglutaminase 2 is dispensable but required for the survival of mice in dextran sulfate sodium-induced colitis

Transglutaminase 2 (TG2) is a ubiquitously expressed enzyme that catalyzes crosslinking, polyamination or deamidation of glutamine residues in proteins. It has been reported that TG2 is involved in the pathogenesis of various inflammatory diseases including celiac disease, pulmonary fibrosis, cystic fibrosis, multiple sclerosis and sepsis. Recently, using a mouse model of bleomycin-induced lung fibrosis, we showed that TG2 is required to trigger inflammation via the induction of T helper type 17 (Th17) cell differentiation in response to tissue damage. However, the role of TG2 in inflammatory bowel disease (IBD), which is thought to be a Th17 cell-associated disease, has remained elusive. In this study, we investigated the role of TG2 in dextran sulfate sodium (DSS)-induced colitis, the most widely used mouse model for IBD. Age- and sex-matched wild-type and TG2^-/- mice were fed 2% DSS for 7 days or 3.5% DSS for 5 days in drinking water. An in situ TG activity assay revealed that DSS treatment activates TG2 in various colon cell types, including columnar absorptive cells and goblet cells. DSS-treated TG2^-/- mice showed lower interleukin (IL)-6, but higher IL-17A and RORγt (retinoic acid receptor-related orphan receptor-γt) expression levels in the colon tissues than that in the wild-type mice. Moreover, TG2^-/- mice showed higher mortality than the wild-type mice because of DSS treatment. Nevertheless, we found no significant differences in changes of body weight, colon length, morphology, immune cell infiltration and in vivo intestinal permeability between DSS-treated wild-type and TG2^-/- mice. These results indicate that TG2-mediated Th17 cell differentiation is not required for the pathogenesis of DSS-induced acute colitis.

IL-10/microRNA-155/SHIP-1 signaling pathway is crucial for commensal bacteria induced spontaneous colitis

Interleukin 10 (IL-10) microRNA-155 (miR-155)/Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP-1) signaling pathway plays an important role in maintaining immune homeostasis. We aimed to determine and characterize the changes induced by commensal bacteria on the IL-10/miR-155/SHIP-1 signaling pathway, as well as the potential therapeutic effects of anti-miR-155 on colitis in IL-10 deficient (IL-10(-)/(-)) mice. Age- and sex-matched C57BL/6 IL-10(-)/(-) and wild type mice were transferred from a germ-free environment to a specific pathogen free condition. Part of IL-10(-)/(-) mice were then treated with anti-miR-155. IL-10/miR-155/SHIP-1 signaling pathway was evaluated and the therapeutic effects of anti-miR-155 treatment on colitis in IL-10(-)/(-) mice was assessed. The expression and the relationship of IL-10, miR-155, and SHIP-1 were also measured in patients with active Crohn's colitis. IL-10/miR-155/SHIP-1 signaling pathway was activated in IL-10(-)/(-) mice transferring from a germ-free environment to a specific pathogen free condition. Anti-miR-155 treatment significantly ameliorated the severity of colitis in IL-10(-)/(-) mice. Additionally, administration of anti-miR-155 was associated with a restoration of SHIP-1 signaling pathway. The relationship of IL-10, miR-155, and SHIP-1 was confirmed in human study using samples from patients with active Crohn's colitis. IL-10/miR-155/SHIP-1 pathways play a critical role in commensal bacteria induced colitis and miR-155 may be a potential therapeutic target for human inflammatory bowel disease.

Dysregulated Lysine Acetyltransferase 2B Promotes Inflammatory Bowel Disease Pathogenesis Through Transcriptional Repression of Interleukin-10

BACKGROUND AND AIMS

Accumulating evidence supports epigenetic modifications in mediating intestinal immunity in inflammatory bowel disease [IBD] pathogenesis. This study aimed to identify key dysregulated epigenetic modulators and the molecular downstream pathways in IBD.

METHODS

Expression of 116 well-defined epigenetic modulators was profiled and validated in 96 intestinal tissues from patients with Crohn's disease [CD], ulcerative colitis [UC], and healthy controls using quantitative reverse transcriptase polymerase chain reaction [QRT-PCR], western blot, and immunohistochemistry. Dysregulation of histone modifications and IBD-related cytokines were examined by chromatin immunoprecipitation, luciferase activity, and gene expression analyses in normal colonic epithelial cell line, NCM460, upon small-molecule inhibition or RNA interference, followed by validation in primary colonic tissues.

RESULTS

Targeted expression profiling uncovered seven differentially expressed epigenetic modulators, of which the down-regulation of lysine acetyltransferase 2B [KAT2B] mRNA and protein was the most significant and was consequently validated in inflamed CD and UC compared with healthy colonic tissues. KAT2B protein localised abundantly in nuclei of normal colonic epithelium but diminished in paired inflamed CD and UC tissues. Pharmacological inhibition of KAT2B by anacardic acid in NCM460 cells reduced the levels of histone H4 lysine 5 acetylation [H4K5ac] and interleukin-10 [IL-10] in a dose-dependent manner. Knockdown of KAT2B reduced the IL-10 promoter occupancy of KAT2B and H4K5ac, resulting in transcriptional silencing. IL-10 level was also diminished in inflamed IBD tissues.

CONCLUSIONS

Our findings demonstrated a novel epigenetic mechanism of IL-10 dysregulation in IBD. Down-regulation of KAT2B may disrupt the innate and adaptive inflammatory responses due to the suppression of this crucial anti-inflammatory cytokine.

Heterogeneity of subordination of the IL-18/IFN-γ axis to caspase-1 among patients with Crohn's disease

In Crohn's disease (CD), hierarchical architecture of the inflammatory network, including subordination of IL-18, an IFN-γ-inducing cytokine, to the inflammasome, have remained undeciphered. Heterogeneity among patients of such a subordination cannot be evaluated by animal models, monofactorial in their etiology and homogenous in disease progression. To address these issues, we set up an ex vivo model of inflamed mucosa explant cultures from patients with active long-standing CD. Th1 cytokine production, especially IFN-γ and IL-18, was assessed in relation with inflammation intensity. Subordination of the Th1 response to caspase-1, effector of the inflammasome, was determined in explant cultures subjected to pharmacological inhibition of caspase-1 by YVAD. We showed a correlation between secreted IFN-γ/IL-18 levels, and caspase-1 activation, with inflammation intensity of intestinal CD mucosa explants. Inhibition of caspase-1 activation using the specific inhibitor YVAD identified a homogenous non responder group featuring a caspase-1-independent IL-18/IFN-γ response, and a heterogenous responder group, in which both IL-18 and IFN-γ responses were caspase-1-dependent, with a 40-70% range of inhibition by YVAD. These findings bring out the concept of heterogeneity of subordination of the Th1 response to inflammasome activation among CD patients. This ex vivo model should have therapeutic relevance in allowing to determine eligibility of CD patients for new targeted therapies.

LPS-Stimulated Whole Blood Cytokine Production Is Not Related to Disease Behavior in Patients with Quiescent Crohn's Disease

Introduction

Crohn’s disease (CD) is a chronic inflammatory disease in which cytokines play a pivotal role in the induction and maintenance of inflammation. Innate cytokine production is genetically determined and varies largely between individuals; this might impact the severity of inflammation. We aimed to assess whether ex-vivo endotoxin-stimulated levels of cytokines could be associated with disease phenotype.

Methods

Patients with quiescent CD (Harvey-Bradshaw Index ≤ 4 and negative inflammation markers) who were not using immunomodulating drugs or biologicals were eligible. Historical disease characteristics (localization, behavior, number of bowel resections, drug history, extra-intestinal symptoms) were extracted from medical records. We measured cytokine levels (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10) in supernatants of lipopolysaccharide (LPS) -stimulated whole blood cultures and correlated these with disease characteristics and age- and sex-matched healthy controls. In addition, we analyzed whether single nucleotide polymorphisms (SNPs) in the promoter region of the TNF-α gene were related to TNF-α levels.

Results

We included 75 patients with CD and 24 healthy controls. Six patients were excluded because of increased inflammation markers resulting in a total of 69 patients. The mean age (SD) of patients with CD was 51.2 (12.3) years with a mean (SD) disease duration of 24.1 (11.5) years. Disease localization, peri-anal involvement and behavior were not related to LPS-stimulated TNF-α, IL-1β, IL-6 or IL-10 levels. In addition, combination of localization with behavior to differentiate mild from severe disease type showed no significant differences. TNF-α levels were higher in patients with CD (428 pg/ml IQR [267-468]) compared to healthy controls (459 pg/ml IQR [364-570], p=0.02). We found no associations between SNPs in the promoter region and TNF-α levels.

Conclusion

In this study, innate cytokine production of TNF-α, IL-1β, IL-6 and IL-10 was not related to historical disease characteristics or disease severity in patients with quiescent CD. These findings suggest that genetically determined levels of these cytokines obtained from LPS-stimulated whole blood cultures are not linked with disease behavior or severity.

Interleukin-10 paradox: A potent immunoregulatory cytokine that has been difficult to harness for immunotherapy

Interleukin-10 (IL-10) is arguably the most potent anti-inflammatory cytokine. It is produced by almost all the innate and adaptive immune cells. These cells also serve as its targets, indicating that IL-10 secretion and action is highly regulated and perhaps compartmentalized. Consistent with this notion, various efforts directed at systemic administration of IL-10 to modulate autoimmune diseases (type 1 diabetes, multiple sclerosis, rheumatoid arthritis, psoriasis) have produced conflicting and largely inconsequential effects. On the other hand, IL-10 can promote humoral immune responses, enhancing class II expression on B cells and inducing immunoglobulin (Ig) production. Consequently, the high IL-10 level in systemic lupus erythematosus (SLE) patients is considered pathogenic and its blockade ameliorates the disease. In this perspective, we review preclinical findings and results of recent clinical studies using exogenous IL-10 to treat the aforementioned autoimmune diseases. In addition, given the limited success of IL-10 supplementation, we suggest that future studies should be expanded beyond modulating the delivery modes to include developing new strategies to protect and replenish the endogenous sources of IL-10. As an example, we provide evidence that aberrant Fas-mediated deletion of IL-10-producing B cells subverts the immunoregulatory role of IL-10 in autoimmune diabetes and that modulation of the Fas pathway preserves the IL-10-producing B cells and completely protects NOD mice from developing the disease.

Fibrosis Related Inflammatory Mediators: Role of the IL-10 Cytokine Family

Importance of chronic fibroproliferative diseases (FDs) including pulmonary fibrosis, chronic kidney diseases, inflammatory bowel disease, and cardiovascular or liver fibrosis is rapidly increasing and they have become a major public health problem. According to some estimates about 45% of all deaths are attributed to FDs in the developed world. Independently of their etiology the common hallmark of FDs is chronic inflammation. Infiltrating immune cells, endothelial, epithelial, and other resident cells of the injured organ release an orchestra of inflammatory mediators, which stimulate the proliferation and excessive extracellular matrix (ECM) production of myofibroblasts, the effector cells of organ fibrosis. Abnormal amount of ECM disturbs the original organ architecture leading to the decline of function. Although our knowledge is rapidly expanding, we still have neither a diagnostic tool to detect nor a drug to specifically target fibrosis. Therefore, there is an urgent need for the more comprehensive understanding of the pathomechanism of fibrosis and development of novel diagnostic and therapeutic strategies. In the present review we provide an overview of the common key mediators of organ fibrosis highlighting the role of interleukin-10 (IL-10) cytokine family members (IL-10, IL-19, IL-20, IL-22, IL-24, and IL-26), which recently came into focus as tissue remodeling-related inflammatory cytokines.

IL-10 promoter polymorphisms influence susceptibility to aGvHD and are associated with proportions of CD4+FoxP3+ lymphocytes in blood after hematopoietic stem cell transplantation

Four hundred and ninety-five patients (390 and 105 grafted from unrelated and sibling (SIB) donors, respectively) and their donors were analyzed for the impact of interleukin-10 (IL-10) promoter genotype [rs18000896 (-1082 G/A), rs18000871 (-819 C/T) and rs18000872 (-592 C/A)] on the outcome of hematopoietic stem cell transplantation (HSCT). Patients having ACC haplotype were at a lower risk of acute graft versus host disease (aGvHD, grade > I) if transplanted from human leukocyte antigen (HLA) well-matched (10/10) unrelated donors (20/135 vs 39/117, P < 0.001, Pcorr = 0.002), which was not seen if patients were transplanted from either sibling (SIB) or poorly matched (<10/10) unrelated donors (MUD). In addition, GCC haplotype positive recipients of unrelated donor transplants tended to be more susceptible to aGvHD (68/199 vs 39/169, P = 0.019, Pcorr = 0.057). Multivariate logistic regression analysis in the MUD transplanted group showed that donor-recipient human leukocyte antigen (HLA) mismatch [odds ratio (OR) = 3.937, P = 0.001] and a lack of ACC haplotype in recipients (OR = 0.417, P = 0.013) played a significant role as independent risk factors of aGvHD grade > I. ACC carriers had higher proportions of FoxP3+ lymphocytes gated in CD4+ lymphocytes as compared with patients with other IL-10 haplotypes. It was seen at the time of hematological recovery (mean ± SEM: 3.80 ± 0.91% vs 2.06 ± 0.98%, P = 0.012) and 2 weeks later (5.32 ± 0.87% vs 2.50 ± 0.83%, P = 0.013); -592 C/A polymorphism was separately analyzed and it was found that AA homozygotes tended to have a higher incidence of aGvHD (8/15 vs 116/456, P = 0.034) and low proportions of FoxP3 CD4+ lymphocytes in blood (0.43 ± 0.22% vs 4.32 ± 0.71%, P = 0.051) measured 2 weeks after hematological recovery. Functional IL-10 polymorphism associated features influenced the risk of aGvHD with a positive effect of ACC on the pool of Treg in blood.

Timing, frequency and type of physician-diagnosed infections in childhood and risk for Crohn's disease in children and young adults

BACKGROUND

Recent experimental data show that exposure to microbes during early childhood can confer immunological tolerance and protect against Crohn's disease (CD). Epidemiological evidence for this link, however, remains controversial. Using prospective data, we examined the link between this hypothesis and risk for CD in children and young adults.

METHODS

A case-control study design was used. CD cases (diagnosed before age 20 years) were recruited from a tertiary-care pediatric hospital in Montreal, and population-based controls matched for age, gender and, geographical location were selected. Infection data were ascertained from physician-billing records. These records, which use International Classification of Diseases, Ninth Revision diagnostic codes, were consulted retrospectively but provide prospectively collected diagnostic information. Conditional logistic regression analysis was used to study potential associations. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated.

RESULTS

Four hundred nine cases and 1621 controls were included. Regression analysis adjusting for potential confounding variables suggested that any recorded infection before the diagnosis of CD was associated with reduced risk of CD (OR, 0.67; 95% CI, 0.48-0.93). The protective effect was restricted to infections occurring mainly before 5 years of age, with increasing number of infections resulting in greater protection (1-5 infections: OR, 0.74; ≥6 infections: OR, 0.61; P value for trend = 0.039). Infections affecting the oral and upper respiratory tracts, cellulitis, and, enteric infections seemed most protective.

CONCLUSIONS

Our study provides support for the hygiene hypothesis, whereby exposure to infections in early childhood could potentially reduce risks of CD.

Phototherapy with artificial light suppresses dextran sulfate sodium-induced colitis in a mouse model

BACKGROUND AND AIM

Medical treatment for inflammatory bowel disease (IBD) requires chronic administration and causes side effects. Recently, anti-inflammatory effects of phototherapy were reported in animal models. The present study evaluated whether phototherapy improves dextran sulfate sodium (DSS)-induced colitis in a mouse model of IBD.

METHODS

Mice were divided into four equal groups: Control, DSS, DSS + light low (LL), and DSS + light high (LH) groups. Normal fluorescent light intensity in the Control and DSS groups was 200 lux. Artificial light intensities were as follows: DSS + LL group, 1000 lux; DSS + LH group, 2500 lux. After administering phototherapy for 7 days, we evaluated disease activity index (DAI), histological score, colon length/weight, serum 1,25-dihydroxyvitamin D(3) level, and serum and colonic cytokines in the mice.

RESULTS

DAI and histological scores were significantly lower in the DSS + LL group than in the DSS group (both, P < 0.05). Colon length and weight were significantly higher in the DSS + LL group than in the DSS group (both, P < 0.05). Serum interleukin (IL)-6, TNF-α, and IL-17 in the DSS + LL group were significantly lower, and serum and colonic IL-10 were significantly higher in the DSS + LL group than in the DSS group (all, P < 0.05). Serum 1,25-dihydroxyvitamin D(3) levels in the DSS + LH group were significantly increased compared with those in the DSS + LL and DSS groups.

CONCLUSION

Artificial light phototherapy suppressed DSS-induced colitis in mice by suppression of pro-inflammatory cytokines and promotion of anti-inflammatory cytokines.

Polymorphisms of the cytokine genes TGFB1 and IL10 in a mixed-race population with Crohn's disease

Background

Most Crohn’s disease (CD) genes discovered in recent years are associated with biological systems critical to the development of this disease. TGFB1 and IL10 are cytokines with important roles in CD. The aim of this study was to evaluate the association between CD, its clinical features and TGFB1 and IL10 gene polymorphisms.

Methods

This case–control study enrolled 91 patients and 91 controls from the state of Bahia, Brazil. Five single nucleotide polymorphisms (SNPs) were studied in the TGFB1 gene (codon 10 T > C - rs1800470; codon 25 G > C - rs1800471) and IL10 gene (−1082 A > G - rs1800896; -819 T > C - rs1800871; -592 A > C - rs1800872). An analysis of the genetic polymorphisms was performed using a commercial kit. A comparison of allele frequencies and genotypes was estimated by calculating the odds ratio (OR) with a confidence interval adjusted via the Bonferroni test for a local alpha of 1%. A stratified analysis was applied for gender, race and smoking history. Patients with CD were characterized according to the Montreal classification.

Results

The C allele and CC genotype of the TGFB1 gene rs1800470 were both significantly associated with CD. The stratified analysis showed no confounding factors for the co-variables of gender, race and smoking history. The IL10 gene rs1800896 G allele was significantly associated with age at diagnosis of CD, while the T allele of the IL10 gene rs1800871 was significantly associated with perianal disease. The SNPs rs1800871 and rs1800872 were in 100% linkage disequilibrium.

Conclusions

TGFB1 gene polymorphisms may be associated with susceptibility to the development of CD, and IL10 gene polymorphisms appear to influence the CD phenotype in this admixed population.

S100A expression and interleukin-10 polymorphisms are associated with ulcerative colitis and diarrhea predominant irritable bowel syndrome

BACKGROUND

Both ulcerative colitis (UC) and diarrhea-predominant irritable bowel syndrome (IBS-D) are associated with alterations in enteric serotonin (5-HT) signaling.

AIMS

The purpose of this study was to compare the rectal and sigmoid colonic mucosal expression of S100A proteins and functional polymorphisms of the 5-HT transporter (5HTT) and interleukin-10 genes in patients with IBS-D or UC with healthy controls.

METHODS

mRNA expression of S100 proteins was measured in sigmoid and rectal biopsies and in rectal epithelium isolated by laser-captured microdissection. Leucocyte DNA was analyzed by PCR-based reaction fragment length polymorphisms and direct sequencing. Clinical symptoms were assessed by the self-rating depression scale and by the gastrointestinal symptom rating scale.

RESULTS

Fifty patients with IBS-D, 56 with UC and 50 healthy controls were studied. Colonic mucosal expression of S100A8 and S100A9 in UC was significantly higher than in IBS or controls and correlated with the UC disease activity index (r = 0.65, p < 0.001). S100A10 expression in the rectal epithelium of the IBS patients was significantly higher (0.643 vs. 0.402, p = 0.01) than in controls and correlated with the SDS scores (r = 0.41, p = 0.002). The frequency of IL10-819 CC genotype was significantly higher in IBS-D (10.7 vs. 0 %, p = 0.047) and UC (16 vs. 0 %, p = 0.007) than that in controls.

CONCLUSION

Overexpression of S100A10 in the rectum may play a role in IBS as it is involved in modulating 5-HT1B receptors. The IL10-819 CC is a candidate genotype for both IBS and UC in Japanese.

Why interleukin-10 supplementation does not work in Crohn’s disease patients

Inflammatory bowel diseases (IBD) such as Crohn’s disease (CD) or ulcerative colitis are chronic intestinal disorders, which are on the increase in “Westernised” countries. IBD can be caused by both genetic and environmental factors. Interleukin-10 (IL-10) is an immunoregulatory cytokine that has been identified as being involved in several diseases including IBD. Studies have shown that polymorphisms in the promoter region reduce serum levels of IL-10 and this reduction has been associated with some forms of IBD. Mouse models have shown promising results with IL-10 supplementation, as such IL-10 supplementation has been touted as being a possible alternative treatment for CD in humans. Clinical trials have shown that recombinant human IL-10 is safe and well tolerated up to a dose of 8 μg/kg. However, to date, the results of the clinical trials have been disappointing. Although CD activity was reduced as measured by the CD activity index, IL-10 supplementation did not result in significantly reduced remission rates or clinical improvements when compared to placebo. This review discusses why IL-10 supplementation is not effective in CD patients currently and what can be addressed to potentially make IL-10 supplementation a more viable treatment option in the future. Based on the current research we conclude that IL-10 supplementation is not a one size fits all treatment and if the correct population of patients is chosen then IL-10 supplementation could be of benefit.

Nucleotide-binding oligomerization domain 2 signaling promotes hyperresponsive macrophages and colitis in IL-10-deficient mice

IL-10 contributes to the maintenance of intestinal homeostasis via the regulation of inflammatory responses to enteric bacteria. Loss of IL-10 signaling results in spontaneous colitis in mice and early onset enterocolitis in humans. Nucleotide-binding oligomerization domain (NOD) 2 is an intracellular receptor of bacterial peptidoglycan products, and, although NOD2 mutations are associated with Crohn's disease, the precise role of NOD2 in the development of intestinal inflammation remains undefined. To determine the role of NOD2 in the development of colitis on the clinically relevant genetic background of IL-10-deficient signaling, we generated mice lacking IL-10 and NOD2 (IL-10(-/-)NOD2(-/-)). Loss of NOD2 in IL-10(-/-) mice resulted in significant amelioration of chronic colitis, indicating that NOD2 signaling promotes the development of intestinal inflammation in IL-10(-/-) mice. Contrary to previous reports investigating immune function in NOD2(-/-) mice, T cell proliferative capacity and IL-2 production were not impaired, and immune polarization toward type 1 immunity was not affected. However, loss of NOD2 in IL-10-deficient macrophages reduced IL-6, TNF-α, and IL-12p40 production in response to bacterial stimulation. Further analysis of the intrinsic macrophage response before the onset of inflammation revealed that, in the absence of IL-10, synergistic signaling between various TLRs and NOD2 resulted in hyperresponsive, proinflammatory macrophages, thus providing the appropriate immune environment for the development of colitis. Data presented in this study demonstrate that NOD2 signaling contributes to intestinal inflammation that arises through loss of IL-10 and provides mechanistic insight into the development of colitis in inflammatory bowel disease patients with impaired IL-10 signaling.

Interleukin-10-1082A/G polymorphism and inflammatory bowel disease susceptibility: a meta-analysis based on 17,585 subjects

A large number of studies have shown that the interleukin-10 (IL-10)-1082A/G polymorphism is implicated in susceptibility to inflammatory bowel disease (IBD). However, the results are inconsistent. We performed this meta-analysis to estimate the association between -1082A/G polymorphism in the IL-10 gene and IBD susceptibility. A total number of 18 case-control studies including 17,585 subjects were identified. No association was found between -1082A/G polymorphism and ulcerative colitis (UC) susceptibility. However, increased risk of Crohn's disease (CD) was associated with -1082A/G polymorphism in the dominant genetic model (GG+GA vs. AA: OR=1.22, 95% CI: 1.02-1.46, P=0.028) and the heterozygote comparison (GA vs. AA: OR=1.28, 95% CI: 1.05-1.55, P=0.015). The results of this meta-analysis provide evidence for the association between IL-10-1082A/G polymorphism and susceptibility of CD. Due to several limitations in the present study, well-designed epidemiological studies with large sample size among different ethnicities should be performed in the future.

Human "orchestrator" CD11b(+) B1 cells spontaneously secrete interleukin-10 and regulate T-cell activity

Immune regulation produced by B cells has been attributed to production and secretion of interleukin (IL)-10, which is a characteristic of mouse B1 cells. In view of the widespread clinical use of B-cell depletion therapies in autoimmune and malignant diseases, it is important to monitor the function and fate of regulatory B cells. However, there is no consensus regarding the phenotypic identity of human IL-10(+) B cells. Here we show that human CD11b(+) B1 cells, one of two recently described subpopulations of B1 cells, spontaneously produce IL-10 and suppress T-cell activation. In view of the capacity of these B cells to either stimulate T-cell proliferation or suppress T-cell activation, CD11b(+) B1 cells are considered to be capable of orchestrating elements of immune responsiveness and thus are termed "orchestrator B1 cells," or "B1orc," whereas CD11b(-) B1 cells that primarily secrete antibody are termed "secretor B1 cells," or "B1sec."

Potential prospects of nanomedicine for targeted therapeutics in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) such as Crohn’s disease are highly debilitating. There are inconsistencies in response to and side effects in the current conventional medications, failures in adequate drug delivery, and the lack of therapeutics to offer complete remission in the presently available treatments of IBD. This suggests the need to explore beyond the horizons of conventional approaches in IBD therapeutics. This review examines the arena of the evolving IBD nanomedicine, studied so far in animal and in vitro models, before comprehensive clinical testing in humans. The investigations carried out so far in IBD models have provided substantial evidence of the nanotherapeutic approach as having the potential to overcome some of the current drawbacks to conventional IBD therapy. We analyze the pros and cons of nanotechnology in IBD therapies studied in different models, aimed at different targets and mechanisms of IBD pathogenesis, in an attempt to predict its possible impact in humans.

Loss of interleukin-10 or transforming growth factor β signaling in the human colon initiates a T-helper 1 response via distinct pathways

BACKGROUND & AIMS

Signaling via interleukin (IL)-10 or transforming growth factor (TGF)-β is disrupted in subpopulations of patients with inflammatory bowel disease, but it is not clear how a T-helper (Th) 1 cell response is induced. We studied conversion of human mucosal innate immune cells into inflammatory cells and the initiation of a Th1 cell response following loss of IL-10 or TGF-β signaling.

METHODS

We depleted IL-10 or TGF-β from explant cultures of human normal colonic mucosa using immunoneutralization. Pharmacologic inhibitors and antibodies were used to determine the factors involved in the initiation of an interferon (IFN)-γ response following loss of TGF-β or IL-10 signaling. Cytokines produced by mucosal cells were assessed by enzyme-linked immunosorbent assay and quantitative reverse-transcriptase polymerase chain reaction. The subsets of cells involved in cytokine production were determined by in situ immunofluorescence analysis and flow cytometry after digestion of the explants with collagenase.

RESULTS

Depletion of IL-10 from human normal colonic mucosa resulted in an IFN-γ response, characterized by early-stage secretion of mature IL-18 and production of the active form of caspase-1 by macrophages and some epithelial cells. A caspase-1 inhibitor or the IL-18 antagonist IL-18-binding protein blocked this response. By contrast, depletion of TGF-β resulted in an IFN-γ response that was preceded by and required secretion of IL-12 from macrophages, dendritic cells, and epithelial cells.

CONCLUSIONS

Innate immune cells (macrophages and epithelial cells) activate a Th1 cell response in explant cultures of human normal colonic mucosa depleted in IL-10 or TGF-β via distinct, nonredundant pathways. These pathways might contribute to the pathogenesis of inflammatory bowel disease.

Apoptosis resistance of mucosal lymphocytes and IL-10 deficiency in patients with steroid-refractory Crohn's disease

BACKGROUND

Apoptosis resistance of T-cells is considered an abnormality of immune pathways in Crohn's disease (CD). It has been previously shown that corticosteroids induce apoptosis of cells involved in inflammation. Thus, our aim was to assess the apoptosis of mononuclear cells and pro/antiinflammatory cytokines in the intestinal mucosa of patients with active CD, related to steroid response, and identify cellular and molecular factors that may predict this response to therapy.

METHODS

Patients with CD (n = 26), ulcerative colitis (UC) (n = 32), and controls (n = 10) were prospectively studied with mucosal biopsies before and 7-10 days after corticosteroid treatment. Immunophenotype and apoptosis of T and B lymphocytes, plasma cells, and macrophages were assessed by flow cytometry, immunohistochemistry, and immunofluorescence. The cytokine expression pattern was evaluated by quantitative polymerase chain reaction (PCR).

RESULTS

Apoptosis resistance of T and B lymphocytes was observed only in steroid-refractory and -dependent CD patients as compared to responsive patients (P = 0.032; P = 0.004, respectively), being evident after steroid treatment. Interleukin (IL)-10 was markedly increased at baseline in steroid-responsive patients compared to the nonresponders (P = 0.006; sensitivity: 88.8%; specificity: 66.6% to predict steroid response).

CONCLUSIONS

Apoptosis resistance of mucosal T and B cells in steroid-refractory and -dependent CD patients appears during the evolution of the acute phase, limiting its clinical application as a predictor marker. In contrast, increased expression of IL-10 at an early stage of active steroid-sensitive CD patients supports its usefulness at predicting a good steroid response. Steroid-dependent and -refractory CD patients share similar molecular and cellular pathophysiological mechanisms.

Apple polyphenols require T cells to ameliorate dextran sulfate sodium-induced colitis and dampen proinflammatory cytokine expression

Human IBD, including UC and Crohn's disease, is characterized by a chronic, relapsing, and remitting condition that exhibits various features of immunological inflammation and affects at least one/1000 people in Western countries. Polyphenol extracts from a variety of plants have been shown to have immunomodulatory and anti-inflammatory effects. In this study, treatment with APP was investigated to ameliorate chemically induced colitis. Oral but not peritoneal administration of APP during colitis induction significantly protected C57BL/6 mice against disease, as evidenced by the lack of weight loss, colonic inflammation, and shortening of the colon. APP administration dampened the mRNA expression of IL-1β, TNF-α, IL-6, IL-17, IL-22, CXCL9, CXCL10, CXCL11, and IFN-γ in the colons of mice with colitis. APP-mediated protection requires T cells, as protection was abated in Rag-1(-/-) or TCRα(-/-) mice but not in IL-10(-/-), IRF-1(-/-), μMT, or TCRδ(-/-) mice. Administration of APP during colitis to TCRα(-/-) mice actually enhanced proinflammatory cytokine expression, further demonstrating a requirement for TCRαβ cells in APP-mediated protection. APP treatment also inhibited CXCR3 expression by TCRαβ cells, but not B or NK cells, in the colons of mice with colitis; however, depletion of CD4(+) or CD8(+) T cells alone did not abolish APP-mediated protection. Collectively, these results show that oral administration of APP protects against experimental colitis and diminishes proinflammatory cytokine expression via T cells.

Macrophages from IBD patients exhibit defective tumour necrosis factor-α secretion but otherwise normal or augmented pro-inflammatory responses to infection

Defects in macrophage function have been implicated in the establishment of Crohn's disease (CD). However, the response of macrophages from CD patients to live bacteria, particularly Mycobacterium avium subsp. paratuberculosis (MAP), has not been addressed. Considering MAP has long been associated to CD, our objective was to assess whether macrophages from CD patients showed impaired inflammatory response to infection by MAP comparing to M. avium subsp. avium (MA) and other live intestinal commensal bacteria. Human peripheral blood monocyte-derived macrophages were obtained from CD patients, ulcerative colitis (UC) patients and controls. Following in vitro infection with MAP, MA, Escherichia coli or Enterococcus faecalis, cytokine levels and cell surface receptor expression were evaluated at different time points. Macrophages from CD patients showed impaired TNF-α secretion in response to bacterial challenge, but augmented IL-23 secretion and preserved IL-12 secretion and CD-40 expression. In addition, CD macrophages showed low IL-10 secretion. Macrophages from IBD patients showed increased expression of TLR-2 and -4, unaffected by infection. Differences in cytokine secretion observed after bacterial challenge were not MAP-specific, as other bacteria (E. coli and MA) showed similar effects. Macrophages from UC patients showed a less compromised TNF-α synthesis in response to mycobacterial infection than CD macrophages, with increased constitutive IL-12 secretion, and preserved IL-10 secretion. The increased IL-23 levels in response to infection and decreased IL-10 production observed in macrophages from CD patients may contribute to the inflammatory exacerbation observed in those patients.

Interleukin-10 and inflammatory bowel disease

The etiology of inflammatory bowel disease (IBD) has not been fully elucidated. Evidence indicates that dysregulation of intestinal mucosal immunity plays a critical role in the pathogenesis of IBD since it can cause overproduction of inflammatory cytokines and lead to uncontrolled intestinal inflammation. Cytokines play a pivotal role in modulating inflammation and may therefore be a good target for IBD therapy. Interleukin-10 (IL-10) is a regulatory cytokine which inhibits both antigen presentation and subsequent pro-inflammatory cytokine release and has been proposed as a potent anti-inflammatory biological therapy for chronic IBD. Many IL-10-based strategies have been developed for treatment of IBD, including recombinant IL-10, genetically modified bacteria expressing IL-10, adenoviral vectors encoding IL-10, and combination therapy with IL-10 and Treg cells. The use of IL-10-based strategies will provide new insights into cell- and gene-based treatment for IBD.

Colitis and intestinal inflammation in IL10-/- mice results from IL-13Rα2-mediated attenuation of IL-13 activity

BACKGROUND & AIMS

The cytokine interleukin (IL)-10 is required to maintain immune homeostasis in the gastrointestinal tract. IL-10 null mice spontaneously develop colitis or are more susceptible to induction of colitis by infections, drugs, and autoimmune reactions. IL-13 regulates inflammatory conditions; its activity might be compromised by the IL-13 decoy receptor (IL-13Rα2).

METHODS

We examined the roles of IL-13 and IL-13Rα2 in intestinal inflammation in mice. To study the function of IL-13Rα2, il10(-/-) mice were crossed with il13rα2(-/-) to generate il10(-/-)il13rα2(-/-) double knockout (dKO) mice. Colitis was induced with the gastrointestinal toxin piroxicam or Trichuris muris infection.

RESULTS

Induction of colitis by interferon (IFN)-γ or IL-17 in IL-10 null mice requires IL-13Rα2. Following exposure of il10(-/-) mice to piroxicam or infection with T muris, production of IL-13Rα2 increased, resulting in decreased IL-13 bioactivity and increased inflammation in response to IFN-γ or IL-17A. In contrast to il10(-/-) mice, dKO mice were resistant to piroxicam-induced colitis; they also developed less severe colitis during chronic infection with T muris infection. In both models, resistance to IFN-γ and IL-17-mediated intestinal inflammation was associated with increased IL-13 activity. Susceptibility to colitis was restored when the dKO mice were injected with monoclonal antibodies against IL-13, confirming its protective role.

CONCLUSIONS

Colitis and intestinal inflammation in IL10(-/-) mice results from IL-13Rα2-mediated attenuation of IL-13 activity. In the absence of IL-13Rα2, IL-13 suppresses proinflammatory Th1 and Th17 responses. Reagents that block the IL-13 decoy receptor IL-13Rα2 might be developed for inflammatory bowel disease associated with increased levels of IFN-γ and IL-17.

Post-transcriptional control during chronic inflammation and cancer: a focus on AU-rich elements

A considerable number of genes that code for AU-rich mRNAs including cytokines, growth factors, transcriptional factors, and certain receptors are involved in both chronic inflammation and cancer. Overexpression of these genes is affected by aberrations or by prolonged activation of several signaling pathways. AU-rich elements (ARE) are important cis-acting short sequences in the 3'UTR that mediate recognition of an array of RNA-binding proteins and affect mRNA stability and translation. This review addresses the cellular and molecular mechanisms that are common between inflammation and cancer and that also govern ARE-mediated post-transcriptional control. The first part examines the role of the ARE-genes in inflammation and cancer and sequence characteristics of AU-rich elements. The second part addresses the common signaling pathways in inflammation and cancer that regulate the ARE-mediated pathways and how their deregulations affect ARE-gene regulation and disease outcome.

Metabolomic analysis identifies inflammatory and noninflammatory metabolic effects of genetic modification in a mouse model of Crohn's disease

Interleukin-10 is an immunosuppressive cytokine involved in the regulation of gastrointestinal mucosal immunity toward intestinal microbiota. Interleukin-10-deficient (IL10(-/-)) mice develop Crohn's disease-like colitis unless raised in germ-free conditions. Previous gas chromatography-mass spectrometry (GC-MS) metabolomic analysis revealed urinary metabolite differences between IL10(-/-) and wildtype C57BL/6 mice. To determine which of these differences were specifically associated with intestinal inflammation arising from IL10-deficiency, urine samples from IL10(-/-) and wildtype mice, housed in either conventional or specific pathogen-free conditions, were subjected to GC-MS metabolomic analysis. Fifteen metabolite differences, including fucose, xanthurenic acid, and 5-aminovaleric acid, were associated with intestinal inflammation. Elevated urinary levels of xanthurenic acid in IL10(-/-) mice were attributed to increased production of kynurenine metabolites that may induce T-cell tolerance toward intestinal microbiota. Liquid chromatography-mass spectrometry analysis confirmed that plasma levels of kynurenine and 3-hydroxykynurenine were elevated in IL10(-/-) mice. Eleven metabolite differences, including glutaric acid, 2-hydroxyglutaric acid, and 2-hydroxyadipic acid, were unaffected by the severity of inflammation. These metabolite differences may be associated with residual genes from the embryonic stem cells of the 129P2 mouse strain that were used to create the IL10(-/-) mouse, or may indicate novel functions of IL10 unrelated to inflammation.

Novel anti-inflammatory functions for endothelial and myeloid cyclooxygenase-2 in a new mouse model of Crohn's disease

Cyclooxygenase-2 (COX-2) is an important regulator of inflammation implicated in the development of a variety of diseases, including inflammatory bowel disease (IBD). However, the regulation of intestinal inflammation by COX-2 is poorly understood. We previously reported that COX-2(-/-) mice fed a cholate-containing high-fat (CCHF) diet had high mortality of unknown mechanisms attributable to severe intestinal inflammation in the ileo-ceco-colic junction that presented characteristics similar to Crohn's disease (CD). To further characterize the role of COX-2 in intestinal inflammation, we established cell-specific conditional COX-2(-/-) mice. Endothelial cell-specific (COX-2(-E/-E)) and myeloid cell-specific (COX-2(-M/-M)) COX-2(-/-) mice, but not wild-type mice, on the CCHF diet developed localized CD-like pathology at the ileo-ceco-colic junction that was associated with cellular infiltration, increased expression of myeloperoxidase and IL-5, and decreased IL-10 expression. The CD-like pathology in COX-2(-E/-E) mice was also accompanied by increased expression of cytokines (IL-6, TNF-alpha, and INF-gamma), compared with wild-type mice and COX-2(-M/-M) mice. In contrast, the ileo-ceco-colic inflammation in COX-2(-M/-M) mice was associated with more pronounced infiltration of granulocytes and macrophages than COX-2(-E/-E) mice. COX-2(-ME/-ME) (COX-2(-M/-M) x COX-2(-E/-E)) mice on the CCHF diet developed CD-like pathology in the ileo-ceco-colic junction reminiscent of total COX-2(-/-) mice on CCHF diet and wild-type mice on CCHF diet treated with COX-2 inhibitor, celecoxib. The pathology of diet-mediated ileo-ceco-colic inflammation in COX-2(-/-) mice offers an excellent model system to elucidate the protective roles of endothelial and myeloid COX-2 and the molecular pathogenesis of CD.

The polymorphism rs3024505 proximal to IL-10 is associated with risk of ulcerative colitis and Crohns disease in a Danish case-control study

Background

Crohns disease (CD) and ulcerative colitis (UC) are characterized by a dysregulated inflammatory response to normal constituents of the intestinal flora in the genetically predisposed host. Heme oxygenase-1 (HO-1/HMOX1) is a powerful anti-inflammatory and anti-oxidant enzyme, whereas the pro-inflammatory interleukin 1β (IL-1β/IL1B) and anti-inflammatory interleukin 10 (IL-10/IL10) are key modulators for the initiation and maintenance of inflammation. We investigated whether single nucleotide polymorphisms (SNPs) in the IL-1β, IL-10, and HO-1 genes, together with smoking, were associated with risk of CD and UC.

Methods

Allele frequencies of the IL-1β T-31C (rs1143627), and IL-10 rs3024505, G-1082A (rs1800896), C-819T (rs1800871), and C-592A (rs1800872) and HO-1 A-413T (rs2071746) SNPs were assessed using a case-control design in a Danish cohort of 336 CD and 498 UC patients and 779 healthy controls. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by logistic regression models.

Results

Carriers of rs3024505, a marker polymorphism flanking the IL-10 gene, were at increased risk of CD (OR = 1.40, 95% CI: 1.06-1.85, P = 0.02) and UC (OR = 1.43, 95% CI: 1.12-1.82, P = 0.004) and, furthermore, with risk of a diagnosis of CD and UC at young age (OR = 1.47, 95% CI: 1.10-1.96) and OR = 1.35, 95% CI: 1.04-1.76), respectively). No association was found between the IL-1β, IL-10 G-1082A, C-819T, C-592A, and HO-1 gene polymorphisms and CD or UC. No consistent interactions between smoking status and CD or UC genotypes were demonstrated.

Conclusions

The rs3024505 marker polymorphism flanking the IL-10 gene was significantly associated with risk of UC and CD, whereas no association was found between IL-1β or HO-1 gene polymorphisms and risk of CD and UC in this Danish study, suggesting that IL-10, but not IL-1β or HO-1, has a role in IBD etiology in this population.