Quantitive cytokine mRNA expression profiles in the colonic mucosa of patients with steroid naïve ulcerative colitis during active and quiescent disease

Intestinal-specific TNFα overexpression induces Crohn's-like ileitis in mice

BACKGROUND AND AIM

Human and animal studies have clearly established tumor necrosis factor (TNF)α as an important mediator of Crohn's disease pathogenesis. However, whether systemic or only local TNFα overproduction is required for the development of chronic intestinal inflammation and Crohn's disease remains unclear. The aim of this study was to assess the contribution of intestinal epithelial-derived TNFα to the development of murine Crohn's-like ileitis.

METHODS

We adapted the well-established TNF(∆ARE/+) mouse model of Crohn's disease (which systemically overexpresses TNFα) to generate a homozygous mutant strain that overexpress TNFα only within the intestinal epithelium. Intestinal-specific TNF(i∆ARE/i∆ARE) mice were examined for histopathological signs of gut inflammation and extraintestinal manifestations of Crohn's disease. The mucosal immune phenotype was characterized, and the contribution of specific lymphocyte populations to the pathogenesis of TNF(i∆ARE/i∆ARE) ileitis was assessed.

RESULTS

TNF(i∆ARE/i∆ARE) mice had increased mucosal and systemic TNFα levels compared to wild-type controls (P<0.001), as well as severe chronic ileitis with increased neutrophil infiltration and villous distortion, but no extraintestinal manifestations (P<0.001 vs. wild-type controls). The gut mucosal lymphocytic compartment was also expanded in TNF(i∆ARE/i∆ARE) mice (P<0.05), consisting of activated CD69(+) and CD4(+)CD62L(-) lymphocytes (P<0.05). FasL expression was significantly elevated in the mesenteric lymph nodes of TNF(i∆ARE/i∆ARE) mice (P<0.05). Adoptive transfer of mucosal TNF(i∆ARE/i∆ARE) lymphocytes resulted in ileitis in immunologically naïve severe combined immunodeficiency recipients (P<0.05 vs. wild-type controls), indicating an effector phenotype that was associated with increased production of both Th1 (IFNγ) and Th2 (IL-5, IL-13) cytokines.

CONCLUSION

Intestinal epithelial-derived TNFα is sufficient for the induction of Crohn's-like ileitis, but not for the occurrence of extraintestinal manifestations, in TNF(i∆ARE/i∆ARE) mice. These effects were associated with generation of effector lymphocytes within the intestinal mucosa and dysregulated apoptosis. Thus, targeted intestinal blockade of TNFα may provide an effective means to neutralize gut-derived TNFα with reduced side effects.

Cytokine mucosal expression in ulcerative colitis, the relationship between cytokine release and disease activity

BACKGROUND

Ulcerative colitis (UC) is an inflammatory bowel disease with conflicting evidence from studies on the roles of TNFα, IL-8, TGFβ and other cytokines and characterised by neutrophil infiltration and tissue destruction.

AIM

To compare cytokine profiles of inflamed and non-inflamed mucosa in patients with distal UC, and matched controls.

METHODS

Patients were prospectively recruited, mucosal biopsies at flexible sigmoidoscopy (FS) were taken from UC patients within macroscopically inflamed and non-inflamed proximal mucosa, and from age-sex matched controls undergoing FS. Endoscopic and histological inflammation was graded. Quantitative cytokine analysis for IL-4, TNFα, IL-17A, IL-8, IL-10, TGFβ and IFNγ was carried out on tissue homogenates. Statistical comparison was by Wilcoxon signed rank pair analysis, Mann-Whitney U test and Spearman's correlation.

RESULTS

69 active UC patients (54 paired non-inflamed/inflamed mucosa) and 69 controls were compared. In inflamed mucosa, elevation in IL-8 and reduction in TGFβ was measured compared with non-inflamed mucosa (p<0.001; p<0.02) and control mucosa (p<0.001; p<0.001); IL-8 was positively correlated (rs=0.481, p<0.01) and TGFβ inversely correlated (rs=0.462; p<0.01) with grade of inflammation. TNFα concentration was not significantly different. Comparisons of inflamed with non-inflamed mucosa also demonstrate significant reduction in concentration of IFNγ (p<0.001), IL-4 (p<0.005) and IL-17A (p<0.002).

CONCLUSION

Our findings suggest that IL-8 is elevated and TGFβ is reduced in distal colitis. Lower concentration of IFNγ, IL-4 and IL-17A were also noted. TNFα levels were unchanged. These findings suggest that the inflammatory response in UC may predominantly involve IL-8 mediated neutrophil infiltration and failure of TGFβ mediated tissue healing.

Pre- and posttherapy assessment of intestinal soluble mediators in IBD: where we stand and future perspectives

Inflammatory bowel disease (IBD) is a chronic inflammatory condition characterized by an abnormal immune response against food or bacterial antigens in genetically predisposed individuals. Several factors of innate and adaptive immune system take part in the inflammatory process, probably actively contributing in endoscopic and histological healing at molecular level. Although it is difficult to discriminate whether they are primary factors in determining these events or they are secondarily involved, it would be interesting to have a clear map of those factors in order to have a restricted number of potentially "good candidates" for mucosal healing. The present review will present a class of these factors and their modulation in course of therapy, starting from pathogenic studies involving several treatments associated with good clinical outcomes. This approach is meant to help in the difficult task of identifying "good candidates" for healing signatures, which could also be possible new therapeutic targets for clinical management of IBD patients.

Therapeutic landscape for ulcerative colitis: where is the Adacolumn(®) system and where should it be?

Granulocyte-monocyte apheresis is a relatively new therapy that has been proposed, sometimes with controversial results, for the treatment of inflammatory bowel disease, particularly ulcerative colitis. The aim of the present study was to perform a thorough review of the literature on the application of this type of treatment in ulcerative colitis and discuss the results, in order to provide an opinion on its use which is shared by the involved experts. The review of the literature was performed by searching PubMed with appropriate key words. The results obtained suggest that the major role for this treatment at this moment is for those patients with steroid dependency or with major contraindications to use of steroids. However, promising, albeit very preliminary, results have also been observed in steroid-naïve subjects, and this is of particular interest in consideration of the safety profile of this therapeutic method. As such, the Adacolumn may prove useful in specific subgroups of patients. Future phenotypic, genotypic, and molecular characterization of patients with inflammatory bowel disease might prove useful in defining better those subjects who might benefit most from this treatment modality.

Myosin light chain kinase inhibitor inhibits dextran sulfate sodium-induced colitis in mice

BACKGROUND AND AIMS

Myosin light chain kinase (MLCK) plays a central role in the mechanisms of barrier dysfunction, and intestinal epithelial MLCK protein expression is upregulated in active ulcerative colitis (UC). ML-7, a MLCK inhibitor, has been used in many MLCK studies. However, the effect of ML-7 has never been estimated in colitis models. The aim of this study was to determine whether ML-7 can treat UC.

METHODS

Experimental colitis was induced and ML-7 was administered by intraperitoneal injection. The disease activity index (DAI) scores were evaluated and colon tissue was collected for the assessment of histological changes, myeloperoxidase (MPO) activity, and tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-13 and interleukin (IL)-17 levels. The small intestinal mucosa was ultrastructurally examined, epithelial MLCK protein expression and enzymatic activity were determined, and intestinal permeability was assayed using FITC-dextran 4000 (FD-4) and Evans blue (EB).

RESULTS

ML-7 was found to be significantly effective in reducing the DAI scores and histological index scores, and decreasing MPO activity and TNF-α, IFN-γ, IL-13 and IL-17 levels. The small intestinal epithelial MLCK protein expression and enzymatic activity were downregulated by ML-7. The epithelial cells and intercellular tight junctions were ameliorated, and the amount of FD-4 in blood and EB permeating into the intestine were decreased by ML-7 in colitis mice.

CONCLUSIONS

ML-7 has a significant anti-colitis effect in colitis mice. It is mainly associated with the inhibition of the epithelial MLCK protein expression, resulting in ameliorated intestinal mucosal permeability.

Ulcerative colitis

Ulcerative colitis is an idiopathic, chronic inflammatory disorder of the colonic mucosa, which starts in the rectum and generally extends proximally in a continuous manner through part of, or the entire, colon; however, some patients with proctitis or left-sided colitis might have a caecal patch of inflammation. Bloody diarrhoea is the characteristic symptom of the disease. The clinical course is unpredictable, marked by alternating periods of exacerbation and remission. In this Seminar we discuss the epidemiology, pathophysiology, diagnostic approach, natural history, medical and surgical management, and main disease-related complications of ulcerative colitis, and briefly outline novel treatment options. Enhanced understanding of how the interaction between environmental factors, genetics, and the immune system results in mucosal inflammation has increased knowledge of disease pathophysiology. We provide practical therapeutic algorithms that are easily applicable in daily clinical practice, emphasising present controversies in treatment management and novel therapies.

Role of serum cytokine profile in ulcerative colitis assessment

BACKGROUND

Several cytokines are overexpressed in the colonic mucosa of patients with ulcerative colitis (UC). The measurement of these parameters in plasma could be useful in diagnosis and disease assessment.

METHODS

In all, 67 UC patients and 21 healthy controls were enrolled. At inclusion, clinical, endoscopic, and histological disease activity were assessed using the Ulcerative Colitis Activity Index (UCAI) and the Baron and Geboes scales, respectively. Serum cytokine concentrations were analyzed with a multiplex system (Bio-Plex pro, Bio-Rad) measuring interleukin (IL)-1-β, IL-2, IL-6, IL-8, IL-10, IL-13, IL-17, interferon-gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α). Multiple logistic regression was used to design a serum cytokines profile.

RESULTS

In the UC group the disease activity was moderate to severe based on clinical evaluation in 35 patients (52.2%), by endoscopic appearance in 45 (67.2%), and in 53 patients (81.6%) using histology. With respect to controls, the multivariate analysis identified that UC patients had higher IL-8 (odds ratio [OR] = 1.37; P = 0.002) and IL-10 concentrations (OR = 3.88; P = 0.012) with lower levels of IFN-γ (OR = 0.95; P = 0.002). The model had an accuracy of 77.3%, which increased to 94.6% when only newly diagnosed patients were considered. Patients with moderate to severe disease according to their clinical score showed a higher concentration of IL-8 (OR = 1.16; P = 0.012) and IL-10 (OR = 1.76; P = 0.039) with lower levels of IL-17 (OR = 0.97; P = 0.021). The IL-8 serum concentration was also related to endoscopic and histological severity (OR = 1.10; P = 0.026 and OR = 1.33, P = 0.017, respectively).

CONCLUSIONS

A serum cytokine profile may be an auxiliary tool for the diagnosis and severity assessment of UC. IL-8 seems to be a reliable biomarker, closely related to disease activity.

Colonic inflammation in Parkinson's disease

Lewy pathology affects the gastrointestinal tract in Parkinson's disease (PD) and data from recent genetic studies suggest a link between PD and gut inflammation. We therefore undertook the present survey to investigate whether gastrointestinal inflammation occurs in PD patients. Nineteen PD patients and 14 age-matched healthy controls were included. For each PD patients, neurological and gastrointestinal symptoms were assessed using the Unified Parkinson's Disease Rating Scale part III and the Rome III questionnaire, respectively and cumulative lifetime dose of L-dopa was calculated. Four biopsies were taken from the ascending colon during the course of a total colonoscopy in controls and PD patients. The mRNA expression levels of pro-inflammatory cytokines (tumor necrosis factor alpha, interferon gamma, interleukin-6 and interleukin-1 beta) and glial marker (Glial fibrillary acidic protein, Sox-10 and S100-beta) were analyzed using real-time PCR in two-pooled biopsies. Immunohistochemical analysis was performed on the two remaining biopsies using antibodies against phosphorylated alpha-synuclein to detect Lewy pathology. The mRNA expression levels of pro-inflammatory cytokines as well as of two glial markers (Glial fibrillary acidic protein and Sox-10) were significantly elevated in the ascending colon of PD patients with respect to controls. The levels of tumor necrosis factor alpha, interferon gamma, interleukin-6, interleukin-1 beta and Sox-10 were negatively correlated with disease duration. By contrast, no correlations were found between the levels of pro-inflammatory cytokines or glial markers and disease severity, gastrointestinal symptoms or cumulative lifetime dose of L-dopa. There was no significant difference in the expression of pro-inflammatory cytokines or glial marker between patients with and without enteric Lewy pathology. Our findings provide evidence that enteric inflammation occurs in PD and further reinforce the role of peripheral inflammation in the initiation and/or the progression of the disease.

P2Y6 receptor contributes to neutrophil recruitment to inflamed intestinal mucosa by increasing CXC chemokine ligand 8 expression in an AP-1-dependent manner in epithelial cells

BACKGROUND

Inflammatory bowel diseases are characterized by the presence of CXCL8 at the site of lesions resulting in neutrophil recruitment and loss of tissue functions. We report that P2Y(6) receptor activation stimulates CXCL8 expression and release by intestinal epithelial cells (IECs). In this context, we investigated if uridine 5'-diphosphate (UDP) enemas stimulate neutrophil recruitment to the mucosa of mice suffering from colitis-like disease and we characterized the signaling events linking P2Y(6) to CXCL8 expression in IEC.

METHODS

Neutrophil recruitment was monitored by immunofluorescence and FACS analysis. Expression of Cxcl1, a mouse functional homolog of CXCL8, was determined by quantitative real-time polymerase chain reaction (qPCR). Pharmacological inhibitors and interfering RNAs were used to characterize the signaling pathway. The outcomes of these treatments on protein phosphorylation and on CXCL8 expression were characterized by western blots, qPCR, luciferase, and chromatin immunoprecipitation (ChIP) assays.

RESULTS

Mutation of the AP-1 site in the CXCL8 core promoter abolished the UDP-stimulating effect. The c-fos/c-jun dimer was identified as the AP-1 complex regulating CXCL8 in response to UDP stimulation. Regulation of CXCL8 expression by P2Y(6) required PKCδ activation upstream of the signaling pathway composed of MEK1/2-ERK1/2 and c-fos. UDP administration to mice suffering from colitis-like disease increased the number of neutrophil infiltrating the mucosa, correlating with Cxcl1 increased expression in IEC and the severity of inflammation.

CONCLUSIONS

This study not only describes the P2Y(6) signaling mechanism regulating CXCL8 expression in IEC, but it also illustrates the potential of targeting P2Y(6) to reduce intestinal inflammation.

Milk fat globule-epidermal growth factor 8 is decreased in intestinal epithelium of ulcerative colitis patients and thereby causes increased apoptosis and impaired wound healing

Milk fat globule-epidermal growth factor 8 (MFG-E8) plays an important role in maintaining intestinal barrier homeostasis and accelerating intestinal restitution. However, studies of MFG-E8 expression in humans with ulcerative colitis are lacking. We examined MFG-E8 expression in colonic mucosal biopsies from ulcerative colitis patients and healthy controls (n = 26 each) by real-time quantitative polymerase chain reaction (PCR), Western blot analysis and immunohistochemistry. MFG-E8 mRNA and protein expression was lower in ulcerative colitis patients than in controls. MFG-E8 expression was inversely correlated with mucosal inflammatory activity and clinical disease activity in patients. MFG-E8 was present in human intestinal epithelial cells both in vivo and in vitro. Apoptosis induction was also detected in the intestinal epithelium of ulcerative colitis patients by terminal-deoxynucleoitidyl transferase mediated nick-end labeling assay. We used lentiviral vectors encoding human MFG-E8 targeting short hairpin RNA to obtain MFG-E8 knockdown intestinal epithelia cell clones. MFG-E8 knockdown could promote apoptosis in intestinal epithelial cell lines, accompanied by a decrease in level of the antiapoptotic protein B-cell lymphoma 2 (BCL-2) and induction of the proapoptotic protein BCL2-associated protein X (BAX). The addition of recombinant human MFG-E8 led to decreased BAX and cleaved caspase-3 levels and induction of BCL-2 level in intestinal epithelia cells. MFG-E8 knockdown also attenuated wound healing on scratch assay of intestinal epithelial cells. The mRNA level of intestinal trefoid factor 3, a pivotal factor in intestinal epithelial cell migration and restitution, was downregulated with MFG-E8 knockdown. In conclusion, we demonstrated that decreased colonic MFG-E8 expression in patients with ulcerative colitis may be associated with mucosal inflammatory activity and clinical disease activity through basal cell apoptosis and preventing tissue healing in the pathogenesis of ulcerative colitis.

Transcript levels of Toll-Like Receptors 5, 8 and 9 correlate with inflammatory activity in Ulcerative Colitis

Background

Dysregulation of innate immune response by Toll-Like Receptors (TLRs) is a key feature in Ulcerative Colitis (UC). Most studies have focused on TLR2, TLR3, and TLR4 participation in UC. However, few studies have explored other TLRs. Therefore, the aim of this study was to evaluate the mRNA profiles of TLR1 to 9 in colonic mucosa of UC patients, according to disease activity.

Methods

Colonic biopsies were taken from colon during colonoscopy in 51 patients with Ulcerative Colitis and 36 healthy controls. mRNA levels of TLR1 to 9, Tollip, inflammatory cytokines IL6 and TNF were assessed by RT-qPCR with hydrolysis probes. Characterization of TLR9 protein expression was performed by Immunohistochemistry.

Results

Toll-like receptors TLR8, TLR9, and IL6 mRNA levels were significantly higher in the colonic mucosa from UC patients (both quiescent and active) as compared to healthy individuals (p < 0.04). In the UC patients group the TLR2, TLR4, TLR8 and TLR9 mRNA levels were found to be significantly lower in patients with quiescent disease, as compared to those with active disease (p < 0.05), whereas TLR5 showed a trend (p = 0.06). IL6 and TNF mRNA levels were significantly higher in the presence of active disease and help to discriminate between quiescent and active disease (p < 0.05). Also, IL6 and TNF mRNA positively correlate with TLRs mRNA with the exception for TLR3, with stronger correlations for TLR5, TLR8, and TLR9 (p < 0.0001). TLR9 protein expression was mainly in the lamina propria infiltrate.

Conclusions

This study demonstrates that TLR2, TLR4, TLR8, and TLR9 expression increases in active UC patients, and that the mRNA levels positively correlate with the severity of intestinal inflammation as well as with inflammatory cytokines.

Cells, cytokines and inflammatory bowel disease: a clinical perspective

Ulcerative colitis and Crohn's disease are chronic inflammatory disorders of the GI tract. Although the disorders can usually be distinguished on clinical and pathological criteria, there are similarities in natural history and response to therapy. The purpose of this article is to examine the inflammatory infiltrate in both disorders and the cytokine profiles in intestinal mucosa and peripheral blood. For both disorders, the predominant cells in inflamed mucosa are neutrophils and lymphocytes positive for CD4. There are also increases in the number of B cells, macrophages, dendritic cells, plasma cells, eosinophils and perhaps mast cells. Cytokine levels and cytokine expression are also similar for both disorders, with increases in TNF-α and IFN-γ consistent with a Th1 response. As inflammation occurs in a microbial environment, one possibility is that the nature of the inflammatory response is largely independent of initiating factors. One concept that might be useful is that of initiating cells and cytokines and effector cells and cytokines. Persuasive evidence exists for a defect in phagocytic cells in Crohn's disease, perhaps with the expansion of a subset of activated macrophages. There are also possible links to natural killer cells and changes in the regulation of IL-8 and perhaps IL-22. For ulcerative colitis, the cellular events are less clear, but natural killer T cells may be important as initiating cells, and there is some evidence for upregulation of cytokines involved in Th2 responses, including IL-4 and IL-13. For both disorders, proinflammatory cytokines include TNF-α, IL-12, IL-23, and perhaps IL-17 and IFN-γ. Research challenges include the identification, activation and function of subsets of inflammatory cells, as well as new ways to terminate the inflammatory response.

Progress in understanding the role of interleukins in the pathogenesis of ulcerative colitis

Ulcerative colitis (UC) is a chronic, nonspecific inflammatory bowel disease. The assessment of UC reactiveness can be used to guide clinical treatment. Therefore, it is of important significance to find markers which have sufficient specificity and sensitivity for ease of monitoring UC. In recent years, a intensive study of the relation between interleukins (ILs) and the pathogenesis of UC has revealed changes in the secretion levels of ILs in the progression of UC, which suggests that ILs can be used as markers for monitoring the activity of UC to guide diagnosis and treatment. This paper is a review on the mechanism of action of ILs in the pathogenesis of UC.

N-nitroso compound exposure-associated transcriptomic profiles are indicative of an increased risk for colorectal cancer

Endogenous formation of N-nitroso compounds (NOCs), which are known animal carcinogens, could contribute to human carcinogenesis but definitive evidence is still lacking. To investigate the relevance of NOCs in human colorectal cancer (CRC) development, we analyzed whole genome gene expression modifications in human colon biopsies in relation to fecal NOC exposure. We had a particular interest in patients suffering from intestinal inflammation as this may stimulate endogenous NOC formation, and consequently predispose to CRC risk. Inflammatory bowel disease (IBD) patients diagnosed with ulcerative colitis and irritable bowel syndrome patients without inflammation, serving as controls, were therefore recruited. Fecal NOC were demonstrated in the majority of subjects. By associating gene expression levels of all subjects to fecal NOC levels, we identified a NOC exposure-associated transcriptomic response that suggests that physiological NOC concentrations may potentially induce genotoxic responses and chromatin modifications in human colon tissue, both of which are linked to carcinogenicity. In a network analysis, chromatin modifications were linked to 11 significantly modulated histone genes, pointing towards a possible epigenetic mechanism that may be relevant in comprehending NOC-induced carcinogenesis. In addition, pro-inflammatory transcriptomic modifications were identified in visually non-inflamed regions of the IBD colon. However, fecal NOC levels were slightly but not significantly increased in IBD patients, suggesting that inflammation did not strongly stimulate NOC formation. We conclude that NOC exposure is associated with gene expression modifications in the human colon that may suggest a potential role of these compounds in CRC development.

Chemokine CXCL11 links microbial stimuli to intestinal inflammation

Interleukin (IL)-17 plays an important role in the pathogenesis in a number of immune inflammatory disorders. This study aims to investigate the mechanism by which microbial product flagellin is involved in the development of T helper type (Th)17 cells. Serum levels of IL-17 and CXCL9-11 in patients with ulcerative colitis (UC) were evaluated. The source and mechanism of CXC11 release in intestinal mucosa were examined with colonic biopsies from UC patients and a colitis mouse model. The role of flagellin in the development of Th17 cells was studied with a cell co-culture system. High serum levels of CXCL11 and IL-17 were observed in UC. Flagellin could induce the production of CXCL11 in CD14(+) cells that facilitated the development of Th17 cells. In a skewed Th1 response environment flagellin induces intestinal inflammation, with IL-17 expression predominant. CXCR3/CXCL11 pathway is involved in microbial product flagellin-induced intestinal inflammation in which the Th17 response plays an important role.

Gene expression changes associated with resistance to intravenous corticosteroid therapy in children with severe ulcerative colitis

BACKGROUND AND AIMS

Microarray analysis of RNA expression allows gross examination of pathways operative in inflammation. We aimed to determine whether genes expressed in whole blood early following initiation of intravenous corticosteroid treatment can be associated with response.

METHODS

From a prospectively accrued cohort of 128 pediatric patients hospitalized for intravenous corticosteroid treatment of severe UC, we selected for analysis 20 corticosteroid responsive (hospital discharge or PUCAI ≤45 by day 5) and 20 corticosteroid resistant patients (need for second line medical therapy or colectomy, or PUCAI >45 by day 5). Total RNA was extracted from blood samples collected on day 3 of intravenous corticosteroid therapy. The eluted transcriptomes were quantified on Affymetrix Human Gene 1.0 ST arrays. The data was analysed by the local-pooled error method for discovery of differential gene expression and false discovery rate correction was applied to adjust for multiple comparisons.

RESULTS

A total of 41 genes differentially expressed between responders and non-responders were detected with statistical significance. Two of these genes, CEACAM1 and MMP8, possibly inhibited by methylprednisolone through IL8, were both found to be over-expressed in non-responsive patients. ABCC4 (MRP4) as a member of the multi-drug resistance superfamily was a novel candidate gene for corticosteroid resistance. The expression pattern of a cluster of 10 genes selected from the 41 significant hits were able to classify the patients with 80% sensitivity and 80% specificity.

CONCLUSIONS

Elevated expression of several genes involved in inflammatory pathways was associated with resistance to intravenous corticosteroid therapy early in the course of treatment. Gene expression profiles may be useful to classify resistance to intravenous corticosteroids in children with severe UC and assist with clinical management decisions.

Inflammatory tendencies and overproduction of IL-17 in the colon of young NOD mice are counteracted with diet change

OBJECTIVE

Dietary factors influence diabetes development in the NOD mouse. Diet affects the composition of microbiota in the distal intestine, which may subsequently influence intestinal immune homeostasis. However, the specific effects of antidiabetogenic diets on gut immunity and the explicit associations between intestinal immune disruption and type 1 diabetes onset remain unclear.

RESEARCH DESIGN AND METHODS

Gut microbiota of NOD mice fed a conventional diet or ProSobee formula were compared using gas chromatography. Colonic lamina propria immune cells were characterized in terms of activation markers, cytokine mRNA and Th17 and Foxp3(+) T-cell numbers, using real-time PCR and flow cytometry. Activation of diabetogenic CD4 T-cells by purified B-cells was assessed in both groups. Immune tolerance to autologous commensal bacteria was evaluated in vitro using thymidine-incorporation tests.

RESULTS

Young NOD mice showed a disturbed tolerance to autologous commensal bacteria. Increased numbers of activated CD4 T-cells and (CD11b(+)CD11c(+)) dendritic cells and elevated levels of Th17 cells and IL23 mRNA were moreover observed in colon lamina propria. These phenomena were abolished when mice were fed an antidiabetogenic diet. The antidiabetogenic diet also altered the expression levels of costimulatory molecules and the capacity of peritoneal B-cells to induce insulin-specific CD4 T-cell proliferation.

CONCLUSIONS

Young NOD mice show signs of subclinical colitis, but the symptoms are alleviated by a diet change to an antidiabetogenic diet. Disrupted immune tolerance in the distal intestine may influence peritoneal cell pools and B-cell-mediated activation of diabetogenic T-cells.

IL-6 may modulate the skeletal response to glucocorticoids during exacerbations of inflammatory bowel disease

Whether inflammatory cytokines affect the skeletal response to glucocorticoid (GC) treatment is unclear. Our objectives were to (1) identify the cytokine(s) elevated during exacerbations of inflammatory bowel disease (IBD); (2) determine whether the cytokine(s) identified in this way is related to systemic GC sensitivity; and (3) examine whether cytokines and/or measures of GC sensitivity are related to changes in bone formation or resorption following GC therapy. We designed a combined cross-sectional and prospective study, including patients with active (n = 31) and inactive (n = 34) IBD as well as controls (n = 29). We assessed circulating concentrations of cytokines, PINP and betaCTX, as well as GC sensitivity in peripheral blood mononuclear cells. IL-6 was the only cytokine increased in active IBD, 2.35 (2.63) versus 1.64 (1.21) versus 1.31 (2.79) pg/microl active IBD, inactive IBD, and controls, respectively (median [interquartile range]) (P = 0.03, ANOVA). IL-6 was positively related to magnitude of GC sensitivity (beta = 0.02, 95% CI 0.008-0.04, P = 0.005). Following treatment with GC in active IBD, PINP decreased (P < 0.001), whereas betaCTX showed no significant change (P = 0.2). Subsequently, multiple regression analyses revealed that plasma IL-6 concentrations were inversely related to the extent of PINP suppression following GC (beta = 3.3, 95% CI 0.2-6.4, P = 0.04, adjusted for baseline PINP and duration of GC treatment), while no association was observed with GC sensitivity. In conclusion, IL-6 is elevated in active IBD and may protect against GC-induced suppression of bone formation via a mechanism which appears to be independent of systemic GC sensitivity.

Decreased sigmoidal ABCB1 (P-glycoprotein) expression in ulcerative colitis is associated with disease activity

Aims: The modulation of the intestinal expression of detoxifying proteins by relevant transcription factors, intracellular receptors and cytokines in ulcerative colitis (UC) is poorly understood. Here, we compared the intestinal expression of drug transporters, metabolizing enzymes and putative regulatory genes between inflamed and noninflamed tissue and studied their modulation by disease activity. Materials & methods: Sigmoidal biopsies of 18 UC patients and 18 healthy volunteers matched for age, gender and ABCB1 3435C>T genotype were investigated for mRNA expression levels of 43 systematically selected candidate genes by low-density array real-time PCR. Additionally, the ABCB1 gene product P-glycoprotein was visualized by immunohistochemistry and quantified by western blotting. Disease phenotype was categorized by clinical, endoscopic and histopathological examination. Disease activity was quantified by clinical activity index. Results: In inflamed sigmoidal tissue from UC patients, 11 genes (NAT1, NR2B1, CEBPB, IFG, IL8, IL10, S100A12, SPP1, DEFA5, DEFA6 and HAMP) were overexpressed. By contrast, only the major human efflux transporter ABCB1 showed significantly lower expression levels, that were inversely correlated with those of certain antimicrobial peptides (DEFA5/6) and cytokines (IL1β and IL8). Cell culture experiments revealed a time-dependent decrease of ABCB1 expression upon IL8 exposure. Disease activity profoundly modified ABCB1 expression, indicated by an inverse correlation of clinical activity index values with ABCB1 mRNA expression (r = -0.603; p = 0.017) and markedly reduced protein expression in UC patients with moderate and severe symptomology (p = 0.011). Conclusion: Cytokine-mediated downregulation of the major human efflux transporter ABCB1 in inflamed intestine of UC patients is presumably dependent on disease activity, with a possible contribution from IL8.

Effect of 5-ASA on serum level of IL-8 and PMN apoptosis in TNBS-induced rat colitis

AIM: To investigate the therapeutic mechanism of 5-ASA in inflammatory bowel disease (IBD) through observation of its effects on serum level of IL-8 and PMN apoptosis in trinitrobenzene sulphonic acid (TNBS)-induced rat colitis.

METHODS: Thirty female Sprague-Dawley (SD) rats were randomly divided into three groups, namely, normal control group (group A) and colitis groups (group B and C). Then group B was given 1 mL normal saline while group C was given 5-ASA (200 mg/kg) for 7 d. All of the animals in three groups were anesthetized, and the macroscopic and histological changes of the colon were evaluated and scored. Expression of serum IL-8 was detected using ELISA, and the apoptosis of PMN was examined by flow cytometry.

RESULTS: Compared with group A, macroscopic and histological scores and the serum level of IL-8 were significantly higher in group B (2.74 ± 0.437 vs 0.27 ± 0.346, 5.10 ± 1.101 vs 0.50 ± 0.527, 4.70 ± 0.949 vs 0.44 ± 0.458, 720.97 ± 71.718 ng/L vs 129.88 ± 18.399 ng/L, all P < 0.01), but they were markedly decreased in group C than in group B (1.34 ± 0.385 vs 2.74 ± 0.437, 1.70 ± 0.483 vs 5.10 ± 1.101, 1.50 ± 0.850 vs 4.70 ± 0.949, 392.84 ± 43.628 ng/L vs 720.97 ± 71.718 ng/L, all P < 0.01). Compared with group A, PMN apoptosis rate was notably lower in group B (30.54% ± 4.036% vs 56.13% ± 5.188%, P < 0.01), but it was markedly increased in group C (48.89% ± 4.522%) than in group B (P < 0.01).

CONCLUSION: There is notably therapeutic effect in topical enema with 5-ASA for IBD, which may be related to reduced serum level of IL-8 and induced PMN apoptosis.