Mucosal biomarkers in inflammatory bowel disease: Key pathogenic players or disease predictors?

The role of IL-19, IL-24, IL-21 and IL-33 in intestinal mucosa of inflammatory bowel disease: A narrative review

Interleukins are potential therapeutic targets that can alter the prognosis and progression of inflammatory bowel disease (IBD). The roles of IL-6, IL-10, IL-17, and IL-23 have been extensively studied, setting the stage for the development of novel treatments for patients with IBD. Other cytokines have been less extensively studied. Members of the IL-20 family, mainly IL-19 and IL-24, are involved in the pathogenesis of IBD, but their exact role remains unclear. Similarly, IL-33, a newly identified cytokine, has been shown to control the Th1 effector response and the action of colonic Tregs in animal models of colitis and patients with IBD. IL-21 is involved in the Th1, Th2, and Th17 responses. Data support a promising future use of these interleukins as biomarkers of severe diseases and as potential therapeutic targets for novel monoclonal antibodies. This review aims to summarize the existing studies involving animal models of colitis and patients with IBD to clarify their role in the intestinal mucosa.

Development, optimization, and validation of Inflammatory Bowel Disease rat model using isotretinoin

BACKGROUND

and Purpose: Inflammatory Bowel Disease (IBD) is a persistent bio-psychological disorder with the absence of actual pathological reason. Association between IBD and isotretinoin has been reported by many human and in vitro studies. However, in this study, our focus is on finding the causal relationship between IBD and isotretinoin for the development of a new animal model.

METHODS

Twenty-eight Sprague Dawley rats were taken for this study and divided into five groups (i.e. Group 1: Normal control, Group 2: Standard IBD Model Group (Indomethacin treated), Group 3: Isotretinoin low dose (7 mg/kg), Group 4: Isotretinoin medium dose (35 mg/kg), Group 5: Isotretinoin high dose (70 mg/kg). The rats were treated according to assigned treatment and observed on different days to evaluate the severity of IBD with the help of symptomatical (nausea, diarrhea, stool consistency, etc.) activity, biochemical parameters, macroscopy, and histological analyses.

KEY RESULTS

During the entire study period, body weight, stool consistency and frequency of the animals had been observed daily. No significant reduction in body weight was observed between the disease induced and normal control animals; however, it was observed that the stool consistency of the animals became less (mucus in stool) day by day and stool frequency increased (frequent defecation) in the different isotretinoin groups compared to the control group. There was statistically significant increase in TBARS levels of isotretinoin low (p < 0.05), medium (p < 0.001) and high dose (p < 0.01) treated group was observed, as compared to control group. Similarly, statistically significant effects of isotretinoin on GSH level (p < 0.01), CAT activity (p < 0.01), and SOD (p < 0.01) were also observed. Increase in TNF-α levels found significantly higher in isotretinoin medium dose (35 mg/kg) treated group (p < 0.001) as compared with control group as well as standard IBD model group. All the three-isotretinoin treated groups (Isotretinoin low dose: p < 0.001; Isotretinoin medium dose: p < 0.001; Isotretinoin high dose: p < 0.001) depicted significant difference in macroscopic scores as compared with control group; these results are comparable with standard IBD model group. Histological analyses revealed that, among three-dose groups of isotretinoin, there was excessive amount of crypt abscesses, infiltration of inflammatory cells, and formation of ulceration observed in isotretinoin medium dose treated group.

CONCLUSION

As standard indomethacin treated group, isotretinoin also caused significant damage to intestinal mucosa, and form ulceration in gastrointestinal tract. Compared to control group, isotretinoin significantly worsens the disease condition, which were comparable to the indomethacin-treated group; however, isotretinoin at the dose of 35 mg/kg caused maximum severe damage to the intestinal mucosa.

Could Mucosal TNF Transcript as a Biomarker Candidate Help Optimize Anti-TNF Biological Therapy in Patients With Ulcerative Colitis?

Anti-tumor necrosis factor (TNF) biological therapy has generally been accepted as a standard therapeutic option in inflammatory bowel disease (IBD) patient who are refractory to steroids or immunomodulators. However, the primary and secondary nonresponse rates to anti-TNF bioagents in patients with IBD are high. To improve the response rate, anti-TNF bioagents must be offered to the appropriate IBD patients, and the withdrawal of anti-TNF bioagents needs to be done at the right time. In this context, reliable and reproducible biomarkers can provide important supportive information for clinicians to make correct decisions based on the patient’s individual situation. In this review, we summarized the current understanding of using mucosal TNF transcript (TNF) to improve the precision of anti-TNF biological therapy strategies in patients with ulcerative colitis (UC). Analysis of published literature showed that mucosal TNF could affect the precision of the early identification of candidates who will benefit from anti-TNF therapy prior to treatment, the assessment of response and mucosal healing, and the prediction of discontinuation of anti-TNF biological therapy and relapse after drug withdrawal. Challenges and limitations of using mucosal TNF as a biomarker in applying individualized anti-TNF biological therapy in patients with UC still remain and need to be further investigated.

Immunohistochemical Study of Adhesion Molecules in Irritable Bowel Syndrome: A Comparison to Inflammatory Bowel Diseases

Background:

The surface of endothelial cells is covered with cell adhesion molecules including E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1) that mediate the adhesion and extravasation of leukocytes and play a pivotal role in inflammatory response. The aim of this study was to investigate the role of expression of adhesion molecules in inflammatory bowel disease (IBD) patients, irritable bowel syndrome (IBS) patients, and normal colonic mucosa.

Materials and Methods:

IBS and IBD patients along with normal colonic mucosa were recruited in the study. In all groups, two biopsies were taken from each of the three anatomical sites (terminal ileum, cecum, and rectum). Three monoclonal antibodies, E-selectin mAb, VCAM-1 mAb, and ICAM-1 mAb, were applied for immunohistochemical analysis.

Results:

In IBD patients, the expression of intensity of E-selectin, VCAM-1, and ICAM-1 was found decreased, at least in cecum and rectum, in comparison with IBS patients and controls (P < 0.001, P < 0.005, and P < 0.007, respectively). Comparison of the expression of intensity of the aforementioned molecules in IBS patients and controls revealed significant augmentation at the cecum and rectum of IBS patients.

Conclusions:

The expression of adhesion molecules appeared lower in IBD patients compared to IBS patients and controls. In addition, the expression of adhesion molecules appeared higher in IBS compared to the control group. Therefore, it could be hypothesized that the expression of adhesion molecules could be considered as an early event in the process of proinflammatory IBS group and may be other factors play a crucial role in the process of intestinal inflammation in IBD patients.

Proinflammatory cytokines in irritable bowel syndrome: a comparison with inflammatory bowel disease

Background/Aims

Irritable bowel syndrome (IBS) is a common disease often considered as a functional intestinal disorder. Inflammation in IBS is a quite intriguing theory. The aim of this study was to investigate tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 expression in inflammatory bowel disease (IBD) patients, IBS patients and normal controls.

Methods

IBS and IBD patients along with normal controls were recruited in the study. In all groups, 2 pinch biopsies were taken at each of 3 anatomical sites (terminal ileum, cecum, and rectum). IBS patients were also subcategorized according to the syndrome clinical manifestations. Two monoclonal antibodies (mAb), TNF-α mAb and IL-6 mAb, and one polyclonal antibody IL-1β mAb were applied for immunohistochemical analysis.

Results

In IBD patients intensity of TNF-α and IL-1β were lower than in IBS patients or controls, while IL-6 was significantly increased comparing to the aforementioned groups. In IBS patients TNF-α was increased comparing to IBD patients or controls, while IL-6 and IL-1β were similar to controls. In IBS subgroups, TNF-α was lower in diarrhea predominant IBS patients and higher constipation predominant IBS patients. Differences among IBS subgroups regarding IL-6 and IL-1β were nonsignificant.

Conclusions

IL-6 seems to be the most important proinflammatory cytokine in IBD patients, while TNF-α could play a more significant role in IBS pathogenesis.

The Algal Meroterpene 11-Hydroxy-1'-O-Methylamentadione Ameloriates Dextran Sulfate Sodium-Induced Colitis in Mice

Inflammatory bowel disease (IBD) is a complex class of immune disorders. Unfortunately, a treatment for total remission has not yet been found, while the use of natural product-based therapies has emerged as a promising intervention. The present study was aimed to investigate the anti-inflammatory effects of the algal meroterpene 11-hydroxy-1'-O-methylamentadione (AMT-E) in a murine model of dextran sodium sulphate (DSS)-induced colitis. AMT-E was orally administered daily (1, 10, and 20 mg/kg animal) to DSS treated mice (3% w/v) for 7 days. AMT-E prevented body weight loss and colon shortening and effectively attenuated the extent of the colonic damage. Similarly, AMT-E increased mucus production and reduced myeloperoxidase activity (marker for anti-inflammatory activity). Moreover, the algal meroterpene decreased the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-10 levels, and caused a significant reduction of the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Our results demonstrate the protective effects of AMT-E on experimental colitis, provide an insight of the underlying mechanisms of this compound, and suggest that this class of marine natural products might be an interesting candidate for further studies on the prevention/treatment of IBD.

Effects of AVX-470, an Oral, Locally Acting Anti-Tumour Necrosis Factor Antibody, on Tissue Biomarkers in Patients with Active Ulcerative Colitis

BACKGROUND AND AIMS

AVX-470 is an orally administered, bovine-derived, anti-tumour necrosis factor (TNF) antibody with local activity in the gastrointestinal tract. In the first-in-human clinical trial of AVX-470 in active ulcerative colitis, we evaluated inflammatory biomarkers in colon tissue as measures of disease activity and early response to treatment.

METHODS

Thirty-six patients received active drug (AVX-470 at 0.2, 1.6 or 3.5g/day) or placebo over 4 weeks. Colon biopsy samples were collected from 5 regions of colon at baseline and week 4. Tissue inflammatory biomarkers were evaluated by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), epithelial cell apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) and bovine immunoglobulin by immunohistochemistry and mass spectrometry. Endoscopic activity (Ulcerative Colitis Endoscopic Index of Severity [UCEIS]) at colonoscopy was assessed in each colonic region by a central reader.

RESULTS

Bovine immunoglobulin was observed in mucosal tissue before and after dosing in lamina propria and submucosal layers of biopsy tissue. Baseline levels of TNF, myeloperoxidase (MPO), CD68 and interleukin (IL)-1β and, to a lesser extent, IL-6 mRNA were 2- to 3-fold higher in distal vs proximal colon tissue, corresponding to the 2- to 3-fold differences in baseline severities of endoscopic scores. Reductions of >10-fold in TNF and, to lesser extents, in MPO and epithelial cell apoptosis were observed in proximal and distal colon biopsies after 4 weeks of AVX-470 3.5g/day treatment. Reductions in TNF scores were correlated with changes in MPO and CD3 immunohistochemistry scores.

CONCLUSIONS

These results are consistent with anti-TNF activity of orally administered AVX-470 in colon mucosal tissue in ulcerative colitis patients and demonstrate the utility of tissue biomarkers in assessing disease and treatment response in early clinical studies.

CLINICAL TRIAL REGISTRATION NUMBER

This trial was registered with Clinicaltrials.gov as study NCT01759056 and with EudraCT as study 2012-004859-27.

Cape Gooseberry [Physalis peruviana L.] Calyces Ameliorate TNBS Acid-induced Colitis in Rats

BACKGROUND AND AIMS

Physalis peruviana [cape gooseberry] is highly appreciated for its commercial value. The Colombian ecotype is in great demand in the international market, particularly for the unique morphological characteristics of the calyx, which has extended use as a traditional herbal remedy in Colombia because of its anti-inflammatory properties. In this work, the anti-inflammatory activity of the total ethereal extract of Physalis peruviana calyces was evaluated in preventive and therapeutic protocols in a TNBS acid-induced colitis rat model.

METHODS

Colitis was induced by intrarectal administration of TNBS. An evaluation of macroscopic and histopathological parameters in colonic tissue was performed, along with the determination of myeloperoxidase enzyme activity, cytokine levels and gene expression. Additionally, effects on nitric oxide release by lipopolysaccharide [LPS]-stimulated RAW264.7 macrophages and the scavenging activity of DPPH and ABTS free radicals were determined.

RESULTS

The treatment with the Physalis peruviana extract produced a significant improvement in the colonic tissue at both macroscopic and histological levels. IL-1β and TNF-α production was reduced by the extract in both experimental approaches. The groups treated with Physalis peruviana showed a tendency to MUC2 up-regulation and down-regulation of COX-2, iNOS, NLRP3, IL-1β, IL-6 and IL-10 expression. Nitric oxide release in RAW264.7 macrophages was significantly inhibited.

CONCLUSIONS

The Physalis peruviana extract showed intestinal anti-inflammatory activity in the TNBS-induced colitis model, placing this species' calyx, a natural derivative, as a promising source of metabolites that could be used in treatment for inflammatory bowel disease.

Correlation of Biomarker Expression in Colonic Mucosa with Disease Phenotype in Crohn's Disease and Ulcerative Colitis

BACKGROUND

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are characterized by chronic intestinal inflammation due to immunological, microbial, and environmental factors in genetically predisposed individuals. Advances in the diagnosis, prognosis, and treatment of IBD require the identification of robust biomarkers that can be used for molecular classification of diverse disease presentations. We previously identified five genes, RELA, TNFAIP3 (A20), PIGR, TNF, and IL8, whose mRNA levels in colonic mucosal biopsies could be used in a multivariate analysis to classify patients with CD based on disease behavior and responses to therapy.

AIM

We compared expression of these five biomarkers in IBD patients classified as having CD or UC, and in healthy controls.

RESULTS

Patients with CD were characterized as having decreased median expression of TNFAIP3, PIGR, and TNF in non-inflamed colonic mucosa as compared to healthy controls. By contrast, UC patients exhibited decreased expression of PIGR and elevated expression of IL8 in colonic mucosa compared to healthy controls. A multivariate analysis combining mRNA levels for all five genes resulted in segregation of individuals based on disease presentation (CD vs. UC) as well as severity, i.e., patients in remission versus those with acute colitis at the time of biopsy.

CONCLUSION

We propose that this approach could be used as a model for molecular classification of IBD patients, which could further be enhanced by the inclusion of additional genes that are identified by functional studies, global gene expression analyses, and genome-wide association studies.

Contribution of the IL-17/IL-23 axis to the pathogenesis of inflammatory bowel disease

Inflammatory bowel diseases (IBDs) are chronic disorders of modern society, requiring management strategies aimed at prolonging an active life and establishing the exact etiology and pathogenesis. These idiopathic diseases have environmental, genetic, immunologic, inflammatory, and oxidative stress components. On the one hand, recent advances have shown that abnormal immune reactions against the microorganisms of the intestinal flora are responsible for the inflammation in genetically susceptible individuals. On the other hand, in addition to T helper cell-type (Th) 1 and Th2 immune responses, other subsets of T cells, namely regulatory T cells and Th17 maintained by IL-23 are likely to develop IBD. IL-23 acts on innate immune system members and also facilitates the expansion and maintenance of Th17 cells. The IL-17/IL-23 axis is relevant in IBD pathogenesis both in human and experimental studies. Novel biomarkers of IBD could be calprotectin, microRNAs, and serum proinflammatory cytokines. An efficient strategy for IBD therapy is represented by the combination of IL-17A and IL-17F in acute IL-17A knockout TNBS-induced colitis, and also definite decrease of the inflammatory process in IL-17F knockout, DSS-induced colitis have been observed. Studying the correlation between innate and adaptive immune systems, we hope to obtain a focused review in order to facilitate future approaches aimed at elucidating the immunological mechanisms that control gut inflammation.

Influence of receptor activator of nuclear factor kappa B ligand, osteoprotegerin and interleukin-33 on bone metabolism in patients with long-standing ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic disease with periods of remission and recurrences. Dysfunction of the local immune response leads to chronic inflammation within the large intestine which triggers morphological changes in the intestinal wall as well as induces the synthesis of numerous factors that have an adverse impact on the bone metabolism. The aim of the study was to determine the expression of RANKL, OPG and IL-33 in mucosal biopsies of UC patients with long disease duration as well as serum level of these cytokines in the context of bone density and bone metabolism.

MATERIALS AND METHODS

The UC group consisted of 56 patients with average disease duration of 16y. The control group comprised 37 healthy individuals. Local expression of cytokines was assessed in the biopsies of colonic mucosa by the real-time PCR and immunohistochemistry (IHC), and their serum concentration was measured by ELISA.

RESULTS

The increased bone resorption observed in patients with UC was reflected by low bone density and high serum level of C-terminal telopeptide (CTX). Mucosal RANKL expression and serum concentration were similar in UC group and healthy subjects, however, UC patients had higher local expression of OPG and serum OPG concentration. Increased IL-33 gene expression was observed only in UC at the mRNA level. We propose that bone resorption in UC patients despite OPG up-regulation could be caused by IL-33-induced mucosal synthesis of a potent proinflammatory cytokine, such as TNF-α, known as a possible inducer of osteoclastogenesis in the way independent of RANKL.

Biomarkers of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disease mostly involved with intestine with unknown etiology. Diagnosis, evaluation of severity, and prognosis are still present as challenges for physicians. An ideal biomarker with the characters such as simple, easy to perform, noninvasive or microinvasive, cheap, rapid, and reproducible is helpful for patients and clinicians. Currently biomarkers applied in clinic include CRP, ESR, pANCA, ASCA, and fecal calprotectin. However, they are far from ideal. Lots of studies are focused on seeking for ideal biomarker for IBD. Herein, the paper reviewed recent researches on biomarkers of IBD to get advances of biomarkers in inflammatory bowel disease.

Inflammatory gene expression profiles in Crohn's disease and ulcerative colitis: a comparative analysis using a reverse transcriptase multiplex ligation-dependent probe amplification protocol

BACKGROUND AND AIMS

Cytokines and their receptors play a critical role in the pathogenesis of the inflammatory bowel disease (IBD). The aim of this study was to investigate the expression profiles of inflammatory genes in inflamed and non-inflamed colonic tissue samples in patients with Crohn's disease (CD) and ulcerative colitis (UC), and to identify molecular signatures for different IBD phenotypes.

METHODS

Seventy-one patients diagnosed with IBD (38 CD, 33 UC) and 15 non-IBD controls have been included in the study. For each patient, biopsy samples were obtained during colonoscopy from inflamed (L) and healthy (N) mucosa. We investigated by commercially available reverse-transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) kit the mRNA expression of a set of 40 genes involved in inflammation: cytokines, chemokines, receptors, signal transduction molecules and transcription factors.

RESULTS

In L biopsies from patients with CD, higher expression levels were found for IL-4 (p=0.009) and IL-12p35 (p=0.0005), whereas in L biopsy samples from patients with UC higher expression levels were found for IL-8 (p=0.03), chemokines SCYA3 (p=0.05), SCYA4 (p=0.01) and glutathione S-transferase P1 (p=0.01). In N biopsies of patients with CD higher expression levels were found for IL-1R (p=0.01) and IL-12p35 (p=0.007), whereas in N biopsies of patients with UC higher expression levels were found for IL-15 (p=0.009) and SCYA8 (p=0.001). The logistic regression analysis has indicated that low expression levels of IL-2 and IL-10, together with higher ASCA IgG titers were independently associated with penetrating/stricturing CD.

CONCLUSIONS

RT-MLPA is a sensitive and effective method for the evaluation of the profiles of inflammatory genes in IBD, with potential future applications for diagnosis, phenotypic stratification and targeted therapy.

ATG4B/autophagin-1 regulates intestinal homeostasis and protects mice from experimental colitis

The identification of inflammatory bowel disease (IBD) susceptibility genes by genome-wide association has linked this pathology to autophagy, a lysosomal degradation pathway that is crucial for cell and tissue homeostasis. Here, we describe autophagy-related 4B, cysteine peptidase/autophagin-1 (ATG4B) as an essential protein in the control of inflammatory response during experimental colitis. In this pathological condition, ATG4B protein levels increase in parallel with the induction of autophagy. Moreover, ATG4B expression is significantly reduced in affected areas of the colon from IBD patients. Consistently, atg4b (-/-) mice present Paneth cell abnormalities, as well as an increased susceptibility to DSS-induced colitis. atg4b-deficient mice exhibit significant alterations in proinflammatory cytokines and mediators of the immune response to bacterial infections, which are reminiscent of those found in patients with Crohn disease or ulcerative colitis. Additionally, antibiotic treatments and bone marrow transplantation from wild-type mice reduced colitis in atg4b (-/-) mice. Taken together, these results provided additional evidence for the importance of autophagy in intestinal pathologies and describe ATG4B as a novel protective protein in inflammatory colitis. Finally, we propose that atg4b-null mice are a suitable model for in vivo studies aimed at testing new therapeutic strategies for intestinal diseases associated with autophagy deficiency.

Label-free quantification for discovering novel biomarkers in the diagnosis and assessment of disease activity in inflammatory bowel disease

OBJECTIVE

No distinctive biomarkers capable of discriminating between ulcerative colitis (UC) and Crohn's disease (CD) have yet been found. In this study, we aimed to discover these biomarkers by using advanced label-free quantification technology for proteomes.

METHODS

Biomarker protein expressions of colonic tissues of Korean IBD patients and controls were determined using label-free quantification to compare the protein profiles of colonic mucosa in three individuals with normal colonic tissue, four patients with UC, three with CD and two with inflammatory polyps related to UC. A computational framework and tools for discovery-based liquid chromatography-tandem mass spectrometry proteomics was applied to draw the biomarkers.

RESULTS

In total, 339 proteins were identified in normal sample group, 217 and 283 proteins in active and inactive UC, 345 and 366 proteins in active and inactive CD and 392 proteins in inflammatory polyps related to UC, respectively. The findings were reproducible. A Corra analysis led to the discovery of 27 potential biomarkers in UC, 37 biomarkers relevant to CD and 11 proteins commonly associated with IBD. Three novel proteins, PRG2, LCP1 and PSME1 were identified as biomarkers signifying active CD.

CONCLUSION

This is the first study to apply label-free quantification for discovering biomarkers in patients with different types and stages of IBD, providing additional insights for revealing the molecular pathogenesis of IBD as well as protein biomarkers of IBD predicting responses to treatment.

Influence of triterpenoids present in apple peel on inflammatory gene expression associated with inflammatory bowel disease (IBD)

Various ursanic, oleanic and lupanic pentacyclic triterpenoids found in apple peel were studied for anti-inflammatory effects in vitro using T84 colon carcinoma cells. After pretreatment with single triterpenoids, cells were stimulated with pro-inflammatory cytokines (TNF-α, INF-γ, IL-1β). Regulation of mRNA expression was analysed for three specific inflammation-associated marker genes (TNF-α, IL-8, IP-10) using qRT-PCR. Furthermore, the effects of ursolic acid (UA) and oleanolic acid (OA) on the synthesis of certain pro-inflammatory proteins were examined. IP-10 expression was inhibited in a dose-dependent manner by all the tested compounds at concentrations ≥25 μM. The mRNA expression of TNF-α was slightly affected and the IL-8 level was increased. At the protein level, UA and OA (25 μM) reduced the synthesis of IP-10; sICAM-1, IL-23 and GROα were slightly repressed. The TNF-α level was not modulated, whereas induction of IL-8 was increased. UA also enhanced the synthesis of IL-1ra, while OA suppressed the level of I-TAC. The present study confirms that triterpenoids present in apple peel and β-damascone may be implicated in the anti-inflammatory properties of apple constituents, suggesting that these substances might be helpful in the treatment of IBD as nutrient supplements.

Immune markers and differential signaling networks in ulcerative colitis and Crohn's disease

BACKGROUND

Cytokine signaling pathways play a central role in the pathogenesis of inflammatory bowel disease (IBD). Ulcerative colitis (UC) and Crohn's disease (CD) have unique as well as overlapping phenotypes, susceptibility genes, and gene expression profiles. This study aimed to delineate patterns within cytokine signaling pathways in colonic mucosa of UC and CD patients, explore molecular diagnostic markers, and identify novel immune mediators in IBD pathogenesis.

METHODS

We quantified 70 selected immune genes that are important in IBD signaling from formalin-fixed, paraffin-embedded (FFPE) colon biopsy samples from normal control subjects and UC and CD patients having either severe colitis or quiescent disease (n = 98 subjects). We utilized and validated a new modified real-time reverse-transcription polymerase chain reaction (RT-PCR) technique for gene quantification.

RESULTS

Expression levels of signaling molecules including IL-6/10/12/13/17/23/33, STAT1/3/6, T-bet, GATA3, Foxp3, SOCS1/3, and downstream inflammatory mediators such as chemokines CCL-2/11/17/20, oxidative stress inducers, proteases, and mucosal genes were differentially regulated between UC and CD and between active and quiescent disease. We also document the possible role of novel genes in IBD, including SHP-1, IRF-1,TARC, Eotaxin, NOX2, arginase I, and ADAM 8.

CONCLUSIONS

This comprehensive approach to quantifying gene expression provides insights into the pathogenesis of IBD by elucidating distinct immune signaling networks in CD and UC. Furthermore, this is the first study demonstrating that gene expression profiling in FFPE colon biopsies might be a practical and effective tool in the diagnosis and prognosis of IBD and may help identify molecular markers that can predict and monitor response to individualized therapeutic treatments.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Quantitative proteomic approaches in biomarker discovery of inflammatory bowel disease

Proteomics offers considerable opportunities for either enhancing our biological understanding or discovering biomarkers, blood and biopsied specimen-based proteomic approaches, provide reproducible and quantitative tools that can complement clinical assessments and aid clinicians in the diagnosis and treatment of inflammatory bowel disease (IBD). Sometimes a differential diagnosis of Crohn's disease (CD) and ulcerative colitis (UC) and the prediction of treatment response can be deduced by finding meaningful biomarkers, for which the central platform for proteomics is tandem mass spectrometry (MS/MS). A range of workflows are available for protein (or peptide) separation prior to MS/MS as well as bioinformatics analysis to achieve protein identification, for which two-dimensional electrophoresis (2-DE) and subsequent mass spectrometry (MS), liquid chromatography-MS, difference gel electrophoresis following 2-DE, isobaric tags for relative and absolute quantification (iTRAQ), stable isotope labeling by amino acids and label-free quantification are under development. In this article, the current status and perspective of these advanced proteomic technologies are introduced, with examples of recent biomarkers focused on the diagnosis, treatment response, prognosis of IBD, and even colitis-associated carcinogenesis in both animal models and human patients.

The role of autoantibodies in inflammatory bowel disease

The search for the underlying trigger of an inappropriate inflammatory reaction characteristic of inflammatory bowel diseases (IBD) has led to the discovery of several antibodies. The panel of serologic markers for IBD is rapidly expanding. Serologic markers hold the promise of helping researchers and clinicians to better understand IBD heterogeneity and natural history. The real importance of the antibodies produced against various microbial and autoantigens is still uncertain. Whether these antibodies play a primary role in the pathogenesis of IBD, or their presence is only a consequence of the inflamed mucosa is a fundamental question that remains to be clarified. The impact of the routine evaluation of these serologic markers in the everyday clinical IBD diagnostic algorithm is questionable due to their limited sensitivity. Despite their great potential, the routine use of serologic markers for diagnosis and follow-up is currently not justified. However, their correlation with disease phenotype and behavior is more established. A combination of serum markers has been shown to be of more value compared to using single markers alone. The ongoing challenge is how to best utilize these serologic markers to provide clinically relevant information in a cost-effective manner. Further prospective clinical trials are needed to determine their exact role in pathogenesis and practical clinical importance. We review the current standpoint of the clinical impact of various established and newly suggested markers in Crohn's disease and ulcerative colitis.

Soy-derived di- and tripeptides alleviate colon and ileum inflammation in pigs with dextran sodium sulfate-induced colitis

We evaluated the antiinflammatory activity of soy-derived di- and tripeptides in a dextran sodium sulfate (DSS)-induced pig model of intestinal inflammation. In the DSS-positive control (POS) and DSS-positive with soy peptide treatment (SOY) groups (n = 6/group), DSS was administered to piglets via i.g. catheter for 5 d, followed by a 5-d administration of saline or soy-derived peptides, respectively. A negative control (NEG) group received saline in lieu of the DSS and soy peptides. The severity of inflammation was assessed by clinical signs, morphological and histological measurements, gut permeability, and neutrophil infiltration. Local production of TNF and IL6 were measured by ELISA, colonic and ileal inflammatory gene expression were assessed by real-time RT-PCR, and CD4+CD25+ lymphocyte populations were analyzed by flow cytometry. Crypt elongation and muscle thickness, d-mannitol gut permeation, colonic expression of the inflammatory mediators IFNG, IL1B, TNF, RORC, and IL17A as well as the FOXP3 T-regulatory transcription factor, and myeloperoxidase activity were lower (P < 0.05) in the SOY pigs than in POS pigs. Messenger RNA levels of ileal IFNG, TNF, IL12B, and IL17A were lower (P < 0.05) and FOXP3 expression was greater (P < 0.05) in SOY piglets than in the POS group. In the mesenteric lymph nodes, CD4+CD25+ T cells were higher (P < 0.05) in both the POS and SOY groups than in NEG controls. Soy-derived peptides exert antiinflammatory activity in vivo, suggesting their usefulness for the treatment of inflammatory disorders.

Candidate mucosal and surrogate biomarkers of inflammatory bowel disease in the era of new technology

OBJECTIVE

There is increasing knowledge of the pathophysiology behind inflammatory bowel disease (IBD) although the exact mechanism is far from fully understood. In the era of new technology, over the last years molecular approaches have shed light on the inflammatory mechanisms and their metabolic end products. This opens for a molecular fingerprinting that can be used in the biomarker field of IBD. There is a great need of biomarkers for prediction of clinical outcome and prognostic biomarker for prediction of therapeutic effects in IBD. Although the biomarker concept is old, so far very few really useful biomarkers exist in IBD.

MATERIAL AND METHODS

Here, we review the predictive and prognostic biomarkers in IBD in the era of new technologies with emphasis on the potential of molecular fingerprinting.

RESULTS

Very few candidate biomarkers have been documented. The most promising candidate predictor is tumor necrosis factor-α, but there is a lack of validation.

CONCLUSION

So far, there are few biomarkers documented in IBD, but we are at the start of a new scientific field that will be of great value for the handling of the disease.

Metabolic phenotyping of the Crohn's disease-like IBD etiopathology in the TNF(ΔARE/WT) mouse model

The underlying biochemical consequences of inflammatory bowel disease (IBD) on the systemic and gastrointestinal metabolism have not yet been fully elucidated but could help to better understand the disease pathogenesis and to identify tissue-specific markers associated with the different disease stages. Here, we applied a metabonomic approach to monitor metabolic events associated with the gradual development of Crohn's disease (CD)-like ileitis in the TNF(ΔARE/WT) mouse model. Metabolic profiles of different intestinal compartments from the age of 4 up to 24 weeks were generated by combining proton nuclear magnetic resonance ((1)H NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS). From 8 weeks onward, mice developed CD similar to the immune and tissue-related phenotype of human CD with ileal involvement, including ileal histological abnormalities, reduced fat mass and body weight, as well as hallmarks of malabsorption with higher energy wasting. The metabonomic approach highlighted shifts in the intestinal lipid metabolism concomitant to the histological onset of inflammation. Moreover, the advanced disease status was characterized by a significantly altered metabolism of cholesterol, triglycerides, phospholipids, plasmalogens, and sphingomyelins in the inflamed tissue (ileum) and the adjacent intestinal parts (proximal colon). These results describe different biological processes associated with the disease onset, including modifications of the general cell membrane composition, alteration of energy homeostasis, and finally the generation of inflammatory lipid mediators. Taken together, this provides novel insights into IBD-related alterations of specific lipid-dependant processes during inflammatory states.

Innate immunity in allergic disease

The innate immune system consists of multiple cell types that express germline-encoded pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). Allergens are frequently found in forms and mixtures that contain PAMPs and DAMPs. The innate immune system is interposed between the external environment and the internal acquired immune system. It is also an integral part of the airways, gut, and skin. These tissues face continuous exposure to allergens, PAMPs, and DAMPs. Interaction of allergens with the innate immune system normally results in immune tolerance but, in the case of allergic disease, this interaction induces recurring and/or chronic inflammation as well as the loss of immunologic tolerance. Upon activation by allergens, the innate immune response commits the acquired immune response to a variety of outcomes mediated by distinct T-cell subsets, such as T-helper 2, regulatory T, or T-helper 17 cells. New studies highlighted in this review underscore the close relationship between allergens, the innate immune system, and the acquired immune system that promotes homeostasis versus allergic disease.

Horizontal gene transfers with or without cell fusions in all categories of the living matter

This article reviews the history of widespread exchanges of genetic segments initiated over 3 billion years ago, to be part of their life style, by sphero-protoplastic cells, the ancestors of archaea, prokaryota, and eukaryota. These primordial cells shared a hostile anaerobic and overheated environment and competed for survival. "Coexist with, or subdue and conquer, expropriate its most useful possessions, or symbiose with it, your competitor" remain cellular life's basic rules. This author emphasizes the role of viruses, both in mediating cell fusions, such as the formation of the first eukaryotic cell(s) from a united crenarchaeon and prokaryota, and the transfer of host cell genes integrated into viral (phages) genomes. After rising above the Darwinian threshold, rigid rules of speciation and vertical inheritance in the three domains of life were established, but horizontal gene transfers with or without cell fusions were never abolished. The author proves with extensive, yet highly selective documentation, that not only unicellular microorganisms, but the most complex multicellular entities of the highest ranks resort to, and practice, cell fusions, and donate and accept horizontally (laterally) transferred genes. Cell fusions and horizontally exchanged genetic materials remain the fundamental attributes and inherent characteristics of the living matter, whether occurring accidentally or sought after intentionally. These events occur to cells stagnating for some 3 milliard years at a lower yet amazingly sophisticated level of evolution, and to cells achieving the highest degree of differentiation, and thus functioning in dependence on the support of a most advanced multicellular host, like those of the human brain. No living cell is completely exempt from gene drains or gene insertions.

Prediction of disease course in inflammatory bowel diseases

Clinical presentation at diagnosis and disease course of both Crohn’s disease (CD) and ulcerative colitis are heterogeneous and variable over time. Since most patients have a relapsing course and most CD patients develop complications (e.g. stricture and/or perforation), much emphasis has been placed in the recent years on the determination of important predictive factors. The identification of these factors may eventually lead to a more personalized, tailored therapy. In this TOPIC HIGHLIGHT series, we provide an update on the available literature regarding important clinical, endoscopic, fecal, serological/routine laboratory and genetic factors. Our aim is to assist clinicians in the everyday practical decision-making when choosing the treatment strategy for their patients suffering from inflammatory bowel diseases.