Serum laminin and collagen IV in inflammatory bowel disease

Serum Extracellular Matrix Molecules and Their Fragments as Biomarkers of Inflammation and Fibrosis in Inflammatory Bowel Diseases: A Systematic Review

BACKGROUND AND AIM

Contemporary techniques to assess disease activity or bowel damage in patients with inflammatory bowel disease [IBD], such as endoscopy and imaging, are either invasive or lack accuracy. Non-invasive biomarkers for this purpose remain an unmet medical need. Herein, we provide a comprehensive systematic review of studies evaluating blood extracellular matrix [ECM] biomarkers and their relevance in IBD.

METHODS

We conducted a systematic review of PubMed, EMBASE, Web of Science, and Scopus to identify citations pertaining to ECM biomarkers of IBD up to March 1, 2024. Studies were categorized based on marker subtype and clinical use.

RESULTS

Thirty-one ECM markers were identified, 28 of which demonstrated the ability to differentiate IBD disease activity. Collagen III emerged as the most extensively investigated [1212 IBD patients], with the degradation marker C3M and deposition marker PRO-C3 being associated with IBD and subtypes. Collagen V markers C5M and PRO-C5 emerged as the most accurate single markers for diagnosis of IBD, with an area under the curve of 0.91 and 0.93, respectively. Overall, studies were characterized by variable endpoints. None of the studies included histological grading of intestinal damage, repair, or fibrosis formation as the primary outcome in relation to the ECM blood markers.

CONCLUSIONS

Multiple ECM markers are linked with IBD and its phenotypes. However, more rigorous study designs and clearly defined endpoints are needed to ensure reproducibility and develop reliable and accurate biomarkers. ECM markers hold promise as they provide a 'window' into transmural tissue remodelling and fibrosis burden, warranting further investigation.

Gut microbiota induced abnormal amino acids and their correlation with diabetic retinopathy

AIM

To explore the correlation of gut microbiota and the metabolites with the progression of diabetic retinopathy (DR) and provide a novel strategy to elucidate the pathological mechanism of DR.

METHODS

The fecal samples from 32 type 2 diabetes patients with proliferative retinopathy (PDR), 23 with non-proliferative retinopathy (NPDR), 27 without retinopathy (DM), and 29 from the sex-, age- and BMI- matched healthy controls (29 HC) were analyzed by 16S rDNA gene sequencing. Sixty fecal samples from PDR, DM, and HC groups were assayed by untargeted metabolomics. Fecal metabolites were measured using liquid chromatography-mass spectrometry (LC-MS) analysis. Associations between gut microbiota and fecal metabolites were analyzed.

RESULTS

A cluster of 2 microbiome and 12 metabolites accompanied with the severity of DR, and the close correlation of the disease progression with PDR-related microbiome and metabolites were found. To be specific, the structure of gut microbiota differed in four groups. Diversity and richness of gut microbiota were significantly lower in PDR and NPDR groups, than those in DM and HC groups. A cluster of microbiome enriched in PDR group, including Pseudomonas, Ruminococcaceae-UCG-002, Ruminococcaceae-UCG-005, Christensenellaceae-R-7, was observed. Functional analysis showed that the glucose and nicotinate degradations were significantly higher in PDR group than those in HC group. Arginine, serine, ornithine, and arachidonic acid were significantly enriched in PDR group, while proline was enriched in HC group. Functional analysis illustrated that arginine biosynthesis, lysine degradation, histidine catabolism, central carbon catabolism in cancer, D-arginine and D-ornithine catabolism were elevated in PDR group. Correlation analysis revealed that Ruminococcaceae-UCG-002 and Christensenellaceae-R-7 were positively associated with L-arginine, ornithine levels in fecal samples.

CONCLUSION

This study elaborates the different microbiota structure in the gut from four groups. The relative abundance of Ruminococcaceae-UCG-002 and Parabacteroides are associated with the severity of DR. Amino acid and fatty acid catabolism is especially disordered in PDR group. This may help provide a novel diagnostic parameter for DR, especially PDR.

Precision medicine and drug optimization in adult inflammatory bowel disease patients

Inflammatory bowel diseases (IBD) encompass two main entities including ulcerative colitis and Crohn's disease. Although having a common global pathophysiological mechanism, IBD patients are characterized by a significant interindividual heterogeneity and may differ by their disease type, disease locations, disease behaviours, disease manifestations, disease course as well as treatment needs. Indeed, although the therapeutic armamentarium for these diseases has expanded rapidly in recent years, a proportion of patients remains with a suboptimal response to medical treatment due to primary non-response, secondary loss of response or intolerance to currently available drugs. Identifying, prior to treatment initiation, which patients are likely to respond to a specific drug would improve the disease management, avoid unnecessary side effects and reduce the healthcare expenses. Precision medicine classifies individuals into subpopulations according to clinical and molecular characteristics with the objective to tailor preventative and therapeutic interventions to the characteristics of each patient. Interventions would thus be performed only on those who will benefit, sparing side effects and expense for those who will not. This review aims to summarize clinical factors, biomarkers (genetic, transcriptomic, proteomic, metabolic, radiomic or from the microbiota) and tools that could predict disease progression to guide towards a step-up or top-down strategy. Predictive factors of response or non-response to treatment will then be reviewed, followed by a discussion about the optimal dose of drug required for patients. The time at which these treatments should be administered (or rather can be stopped in case of a deep remission or in the aftermath of a surgery) will also be addressed. IBD remain biologically complex, with multifactorial etiopathology, clinical heterogeneity as well as temporal and therapeutic variabilities, which makes precision medicine especially challenging in this area. Although applied for many years in oncology, it remains an unmet medical need in IBD.

Circulating Profile of ECM-Related Proteins as Diagnostic Markers in Inflammatory Bowel Diseases

The aim of our research was to find new biomarkers that could be potentially used in the diagnosis, differentiation and monitoring of inflammatory bowel diseases (IBD). Since extracellular matrix (ECM) remodeling contributes to the pathological changes occurring in IBD, the serum profile of ECM-related proteins may reflect disease activity in the intestinal mucosa. Serum laminin (LM), fibronectin (FN) and gelatinase-associated lipocalin (NGAL) concentrations were determined in 51 patients with IBD before and after a year of treatment, as well as in 48 healthy individuals. A significant difference in serum concentration of FN (130,56 ± 52.87 vs. 287.93 ± 79.69, p < 0.001) and NGAL (133.34 ± 51.51 vs. 102.37.39, p < 0.05) between patients with ulcerative colitis (UC) and healthy individuals was found. In patients with Crohn’s disease (CD), serum concentrations of LM (1329.5 ± 389.36 vs. 1012.07 ± 260.85, p < 0.005) and NGAL (138.94 ± 51.31 vs. 102.65 ± 37.39, p < 0.05) were increased, while FN (89.26 ± 43.86 vs. 287.93 ± 79.69, p < 0.001) was decreased compared to healthy subjects. Moreover, a significant correlation was found between the Mayo score in patients with UC and the levels of NGAL (r = 0.49, p < 0.01) and LM (r = 0.035, p < 0.005), respectively. Another significant correlation was noted between the Crohn’s Disease Activity Index (CDAI) and LM (r = 0.49, p < 0.05) levels in CD group. The results presented in our studies indicate that ECM-related markers might be potential additional tools helpful in diagnosing IBD, differential diagnosis of UC and CD and monitoring the disease activity.

A Serological Biomarker of Laminin Gamma 1 Chain Degradation Reflects Altered Basement Membrane Remodeling in Crohn's Disease and DSS Colitis

BACKGROUND

The laminin gamma 1 chain (LMγ1) is abundant along the crypt-villus axis in the intestinal basement membrane.

AIMS

We investigated whether a serological biomarker of laminin degradation was associated with disease activity in patients with Crohn's disease (CD) and in rats with dextran sulfate sodium (DSS)-induced colitis.

METHODS

Serum samples from CD patients (n = 43), healthy subjects (n = 19), and Sprague Dawley rats receiving 5-6% DSS water for five days and regular drinking water for 11 days were included in this study. The LG1M biomarker, a neo-epitope degradation fragment of the LMγ1 chain generated by matrix metalloproteinases-9 (MMP-9), was measured in serum to estimate the level of laminin degradation.

RESULTS

Serum LG1M was elevated in CD patients with active and inactive disease compared to healthy subjects (p < 0.0001). LG1M distinguished CD patients from healthy subjects, with an area under the curve (AUC) of 0.81 (p < 0.0001). Serum LG1M was decreased in DSS rats compared to controls 2 days after DSS withdrawal, and increased upon reversal of the disease.

CONCLUSIONS

Increased serum LG1M in active and inactive CD patients supports the evidence of altered LM expression in both inflamed and non-inflamed tissue. Moreover, lower LG1M levels in the early healing phase of DSS-induced colitis may reflect ongoing mucosal repair.

Serological biomarkers of type I, III and IV collagen turnover are associated with the presence and future progression of stricturing and penetrating Crohn's disease

BACKGROUND

Increased collagen remodelling is a key pathophysiological component underlying intestinal stricture and fistula development in Crohn's disease (CD).

AIMS

To investigate associations between serological biomarkers of collagen turnover and disease behaviour according to the Montreal classification in patients with CD.

METHODS

Serological biomarkers of type III/IV collagen formation (PRO-C3, PRO-C4) and matrix metalloproteinase (MMP) or granzyme-B (GrzB)-mediated type I, III, IV and VI collagen degradation (C1M, C3M, C4M, C4G, C6Ma3) were measured using neo-epitope protein fingerprint assays in 101 patients with CD (Montreal B1: n = 37; B2: n = 27; B3: n = 37) and 96 controls. Patients were followed up until their last outpatient visit to monitor stricturing/penetrating disease progression and recurrence and the occurrence of surgical interventions.

RESULTS

C1M, C3M and C4M were significantly reduced in patients with stricturing disease (Montreal B2) and accurately differentiated them from patients with either non-stricturing, non-penetrating (B1) or penetrating (B3) disease (all p < 0.001, multivariable analysis). Similarly, the type IV collagen formation/degradation (PRO-C4/C4M) ratio demonstrated high discriminative capacity (B1/B2: AUC = 0.90; B1/B3: AUC = 0.87, both p < 0.001, multivariable analysis). Prospectively, higher baseline levels of C1M and C4G were associated with an increased risk of penetrating disease progression (C4G: hazard ratio [HR] 1.71 [1.05-2.81], p < 0.05).

CONCLUSIONS

Elevated degradation of type I, III and IV collagen and excessive (relative) formation of type IV collagen strongly associates with stricturing CD. Type I and IV collagen fragments show predictive potential for the risk of penetrating disease progression. These biomarkers may become valuable tools for detection and prediction of stricturing and penetrating CD.

Serological Biomarkers of Tissue Turnover Identify Responders to Anti-TNF Therapy in Crohn's Disease: A Pilot Study

INTRODUCTION

Anti-tumor necrosis factor (TNF) therapy is effective in inducing remission in Crohn's disease in 60% of patients. No serological biomarkers are available, which can predict response to anti-TNF. We aimed to investigate serological markers of collagen turnover reflecting tissue inflammation as predictors of response to anti-TNF.

METHODS

In 2 retrospective observational cohorts, markers for matrix metalloproteinase-degraded type III and IV collagens (C3M and C4M, respectively) and for formation of type III and IV collagens (PRO-C3 and PRO-C4, respectively) were measured in serum and compared with standard C-reactive protein in patients with active Crohn's disease who started infliximab (IFX, n = 21) or adalimumab (ADA, n = 21). Disease activity was classified by the Harvey-Bradshaw index (active disease ≥5); response was defined as clinical remission.

RESULTS

Seventeen patients (81%) treated with IFX were in remission at week 14; 15 patients (71%) treated with ADA were in remission at week 8. Serum C4M at baseline was increased in nonresponders compared with responders (IFX: 35.0 ± 2.4 vs 23.2 ± 2.6, P = 0.04, ADA: 53.0 ± 3.2 vs 34.1 ± 2.8, P = 0.006). C4M levels at baseline predicted response in both cohorts (IFX: odds ratio 39 [95% confidence interval, 2.4-523.9] P = 0.02, cutoff 35.2 nmol/L; ADA: odds ratio 26 [95% confidence interval, 1.8-332.5], P = 0.01, cutoff 46.9 nmol/L). C-reactive protein was not able to predict response to anti-TNF.

DISCUSSION

Response to anti-TNF therapy within the first 14 weeks of treatment can be predicted based on baseline levels of basement membrane marker C4M. This marker could be used as biomarker for response to anti-TNF and could aid in early therapy decision making. Validation in larger well-defined cohorts is needed.

The Role of Extracellular Matrix Components in Inflammatory Bowel Diseases

The remodeling of extracellular matrix (ECM) within the intestine tissues, which simultaneously involves an increased degradation of ECM components and excessive intestinal fibrosis, is a defining trait of the progression of inflammatory bowel diseases (IBDs), which include ulcerative colitis (UC) and Crohn's disease (CD). The increased activity of proteases, especially matrix metalloproteinases (MMPs), leads to excessive degradation of the extracellular matrix and the release of protein and glycoprotein fragments, previously joined with the extracellular matrix, into the circulation. MMPs participate in regulating the functions of the epithelial barrier, the immunological response, and the process of wound healing or intestinal fibrosis. At a later stage of fibrosis during IBD, excessive formation and deposition of the matrix is observed. To assess changes in the extracellular matrix, quantitative measurement of the concentration in the blood of markers dependent on the activity of proteases, involved in the breakdown of extracellular matrix proteins as well as markers indicating the formation of a new ECM, has recently been proposed. This paper describes attempts to use the quantification of ECM components as markers to predict intestinal fibrosis and evaluate the healing process of the gut. The markers which reflect increased ECM degradation, together with the ones which show the process of creating a new matrix during IBD, allow the attainment of important information regarding the changes in the intestinal tissue, epithelial integrity and extracellular matrix remodeling. This paper contains evidence confirming that ECM remodeling is an integral part of directional cell signaling in the progression of IBD, and not only a basis for the ongoing processes.

The Nrf2 in the pathophysiology of the intestine: Molecular mechanisms and therapeutic implications for inflammatory bowel diseases

Nrf2 (nuclear factor erythroid 2-related factor 2) is a stress-responsive transcription factor, associated with cellular homeostasis. Under normal conditions Nrf2 is kept in the cytoplasm by Kelch-like ECH-associated protein 1 (Keap1) which facilitates its degradation. Meanwhile, oxidative or electrophilic stress trigger Keap1 dissociation from the Nrf2/Keap1 complex and Nrf2 translocation to the nucleus where it induces the expression of numerous anti-oxidative and anti-inflammatory genes. The Nrf2/Keap1 axis plays a crucial role in the development of gastrointestinal (GI) tract and the maintenance of its proper functionality. This axis also seems to be a promising candidate for prevention of inflammatory bowel diseases (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), as well as their severe complications such as intestinal fibrosis and colorectal cancer. This review focuses on the role of Nrf2/Keap1 in 1) the development and proper functionality of GI tract, 2) the pathophysiology of GI diseases and their long-term complications, 3) the effectiveness of currently used drugs and non-conventional treatments which influence Nrf2/Keap1 and are potentially effective in IBD treatment, as well as 4) the effect of gut microbiota on Nrf2/Keap1 pathway in IBD.

Serum biomarkers of fibrostenotic Crohn's disease: Where are we now?

Intestinal fibrosis and subsequent stricture formation are major clinical challenges in inflammatory bowel disease, resulting in an increased rate of operation and poor prognosis compared with those without. With the changing perception that intestinal fibrosis is irreversible to the point of view that it is reversible in recent years, various candidate serum biomarkers have been studied over the past decades, which may stratify patients based on their risks of developing stenosis and enable the detection of early stages of fibrosis. However, reliable and accurate biomarkers are still unavailable due to conflicting results and the lack of high-quality evidence. In this review we summarized the serum biomarkers that have been proposed for intestinal fibrosis in recent years, which includes gene polymorphisms or variants, epigenetic markers, extracellular matrix components, growth factors, and antibodies, aiming to provide clues for future research.

Serum Biomarkers for Inflammatory Bowel Disease

Background: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic, inflammatory disorder of the gastrointestinal tract. As the novel therapeutic goal and biologicals are widely recognized, accurate assessment of disease and prediction of therapeutic response have become a crucial challenge in clinical practice. Also, because of the continuously rising incidence, convenient and economical methods of diagnosis and clinical assessment are urgently needed. Recently, serum biomarkers have made a great progress and become a focus in IBD study because they are non-invasive, convenient, and relatively inexpensive than are markers in biopsy tissue, stool, breath, and other body fluids.

Aims: To review the available data on serological biomarkers for IBD.

Methods: We searched PubMed using predefined key words on relevant literatures of serum biomarkers regarding diagnosis, evaluation of therapeutic efficacy, surveillance of disease activity, and assessment of prognosis for IBD.

Results: We reviewed serological biomarkers that are well-established and widely used (e.g., C-reactive protein), newly discovered biomarkers (e.g., cytokines, antibodies, and non-coding RNAs), and also recently advancements in serological biomarkers (e.g., metabolomics and proteomics) that are used in different aspects of IBD management.

Conclusions: With such a wealth of researches, to date, there are still no ideal serum biomarkers for IBD. Serum profiling and non-coding RNAs are just starting to blossom but reveal great promise for future clinical practice. Combining different biomarkers can be valuable in improving performance of disease evaluation.

Extracellular Matrix Fragments of the Basement Membrane and the Interstitial Matrix Are Serological Markers of Intestinal Tissue Remodeling and Disease Activity in Dextran Sulfate Sodium Colitis

BACKGROUND

Chronic intestinal inflammation results in tissue damage partly caused by an increase in matrix metalloproteinases (MMP) activity causing degradation of extracellular matrix (ECM) proteins. We studied intestinal tissue remodeling by quantifying ECM protein fragments in serum in dextran sulfate sodium (DSS)-induced colitis, to investigate ECM protein fragments as serological biomarkers of intestinal tissue remodeling and disease activity.

METHODS

Male Sprague-Dawley rats received 5% DSS in drinking water for 5 days followed by 11 days with regular water. Disease activity index (DAI) was scored daily. Serum was collected on day 0, 6, 7, and 16. ELISAs were used to quantify MMP-derived remodeling fragments of basement membrane type IV collagen (C4M and PRO-C4) and interstitial matrix type III collagen (C3M and rPRO-C3).

RESULTS

In DSS rats, serum levels relative to baseline of C4M, PRO-C4, and C3M were elevated (P < 0.01; P < 0.001; P < 0.001) at day 7, which declined at day 16. Levels of rPRO-C3 were lower in DSS rats at day 7 and increased to normal levels at day 16. The ratio between C3M and rPRO-C3 showed an overall degradation (P < 0.0001) of collagen type III in DSS rats at day 7, which correlated to the DAI (r² = 0.5588, P < 0.0001).

CONCLUSION

Our data suggest that remodeling of the basement membrane (C4M and PRO-C4) and the interstitial matrix (C3M and rPRO-C3) increased during DSS-induced colitis and declined with reversal of the disease. Thus, serological biochemical biomarkers of the ECM reflect tissue remodeling and could be studied as markers of disease activity in IBD.

The intestinal tissue homeostasis - the role of extracellular matrix remodeling in inflammatory bowel disease

Introduction: Extracellular matrix (ECM) remodeling of the intestinal tissue is important in inflammatory bowel disease (IBD) due to the extensive mucosal remodeling. There are still gaps in our knowledge as to how ECM remodeling is related to intestinal epithelium homeostasis and healing of the intestinal mucosa.Areas covered: The aim of this review is to highlight the importance of the ECM in relation to the pathogenesis of IBD, while addressing basement membrane and interstitial matrix remodeling, and the processes of wound healing of the intestinal tissue in IBD.Expert opinion: In IBD, basement membrane remodeling may reflect the integrity of the intestinal epithelial-cell homeostasis. The interstitial matrix remodeling is associated with deep inflammation such as the transmural inflammation as seen in fistulas and intestinal fibrosis leading to fibrostenotic strictures, in patients with CD. The interplay between wound healing processes and ECM remodeling also affects the tissue homeostasis in IBD. The interstitial matrix, produced by fibroblasts, holds a very different biology as compared to the epithelial basement membrane in IBD. In combination with integration of wound healing, quantifying the interplay between damage and repair to these sub compartments may provide essential information in IBD patient profiling, mucosal healing and disease management.

Diagnostic Markers for Nonspecific Inflammatory Bowel Diseases

The nonspecific inflammatory bowel diseases (IBD) represent a heterogeneous group of chronic inflammatory disorders of the gastrointestinal tract, and Leśniowski-Crohn's disease (CD) and ulcerative colitis (UC) are among the two major clinical forms. Despite the great progress in understanding the pathogenesis of these diseases, their etiology remains unclear. Genetic, immune, and environmental factors are thought to play a key role. The correct diagnosis of nonspecific inflammatory bowel diseases as well as the determination of disease activity, risk stratification, and prediction of response to therapy still relies on a multidisciplinary approach based on clinical, laboratory, endoscopic, and histologic examination. However, considerable effort has been devoted to the development of an accurate panel of noninvasive biomarkers that have increased diagnostic sensitivity and specificity. Laboratory biomarkers useful in differentiating IBD with functional disorders and in evaluating disease activity, prognosis, and treatment selection for IBD are presented in this study.

Matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in paediatric burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors

The purpose of this study was the determination of matrix metalloproteinase-2 and its correlation with basal membrane components laminin-5 and collagen type IV in the blood plasma of burn patients measured with Surface Plasmon Resonance Imaging (SPRI) biosensors.

MATERIAL AND METHODS

31 children scalded by hot water who were managed at the Department of Paediatric Surgery between 2014-2015, after primarily presenting with burns in 4-20% TBSA were included into the study (age 9 months up to 14 years, mean age 2,5+1 years). There were 10 girls and 21 boys. Venous blood samples were drawn 2-6h, and 12-16h after the thermal injury, and on the subsequent days 3, 5 and 7. The matrix metalloproteinase-2, collagen type IV and laminin-5 concentrations were assessed using Surface Plasmon Resonance Imaging by the investigators blinded to the other data.

RESULTS

The MMP-2, laminin-5 and collagen type IV concentrations in the blood plasma of patients with burns, were highest 12-16h after thermal injury, the difference was statistically significant. The MMP-2, laminin-5 and collagen type IV concentrations measured 3 days, 5 days and 7 days after the thermal injury, slowly decreased over time, and on the 7th day reached the normal range, when compared with the concentration measured in controls.

CONCLUSION

Current work is the first follow-up study regarding MMP-2 in burns. MMP-2, laminin-5 and collagen type IV levels were elevated early after burn injury in the plasma of studied patients, and were highest 12-16h after the injury. MMP-2, laminin-5 and collagen type IV levels were not proportional to the severity of the burn. We believe in the possibility that the gradual decrease of MMP-2, collagen type IV and laminin-5 concentrations could be connected with the process of healing, but to prove it, more investigation is needed in this area. The SPR imaging biosensor is a good diagnostic tool for determination of MMP-2, laminin-5 and collagen type IV in blood plasma of patients with burns.

Protein secondary structure analysis of dried blood serum using infrared spectroscopy to identify markers for colitis screening

There remains a great need for diagnosis of inflammatory bowel disease, for which the current technique, colonoscopy, is costly and also has risks for complications. Attenuated total reflectance Fourier transform infrared spectroscopy is a new screening technique to evaluate colitis. Using second derivative spectral deconvolution of the absorbance spectra, a full set of spectral markers were identified based on statistical analysis. Using this method, Amide I group frequencies, (specifically, α-helix to β-sheet ratio of the protein secondary structure) were identified in addition to the previously reported glucose and mannose signatures in sera of chronic and acute mice models of colitis. We also used the same technique to demonstrate that these spectral markers (α-helix/β-sheet ratio, glucose and mannose) are recovering to basal levels upon anti-TNFα therapy. Hence, this technique will be able to identify changes in the sera due to diseases.

Structural and functional failure of fibrillin‑1 in human diseases (Review)

Fibrillins (FBNs) are key relay molecules that form the backbone of microfibrils in elastic and non‑elastic tissues. Interacting with other components of the extracellular matrix (ECM), these ubiquitous glycoproteins exert pivotal roles in tissue development, homeostasis and repair. In addition to mechanical support, FBN networks also exhibit regulatory activities on growth factor signalling, ECM formation, cell behaviour and the immune response. Consequently, mutations affecting the structure, assembly and stability of FBN microfibrils have been associated with impaired biomechanical tissue properties, altered cell‑matrix interactions, uncontrolled growth factor or cytokine activation, and the development of fibrillinopathies and associated severe complications in multiple organs. Beyond a panoramic overview of structural cues of the FBN network, the present review will also describe the pathological implications of FBN disorders in the development of inflammatory and fibrotic conditions.

The use of Masson's trichrome staining, second harmonic imaging and two-photon excited fluorescence of collagen in distinguishing intestinal tuberculosis from Crohn's disease

AIM

Differentiation between Crohn's disease (CD) and intestinal tuberculosis (ITB) continues to be difficult. The present study investigated the collagen fibre characteristics of CD and ITB using Masson's trichrome staining, second harmonic generation (SHG) imaging and two-photon excited fluorescence (TPEF) imaging with the aim of distinguishing between them.

METHOD

The characteristics of collagen fibres in intestinal specimens from patients with CD, ITB and healthy controls were compared using Masson's trichrome staining and SHG and TPEF imaging.

RESULTS

Masson's trichrome staining showed that the content of collagen fibre (540.92 [139.61-1681.93] vs 236.17 [72.94-1108.32], P < 0.05) and fibre deposits (888.92 [315.89-3172.9] vs 498.98 [38.82-5802.31], P < 0.05) were both higher in ITB than in CD. The content of collagen fibre (594.677 [139.61-1681.93] vs 107.425 [4.66-988.7], P < 0.05) and fibre deposits (1118.4661 [315.89-5802.31] vs 340.575 [29.62-1188.87], P < 0.05) were significantly higher in lesions with granulomata than in those without. The SHG/TPEF images demonstrated that the percentage of fibrosis in ITB was also significantly higher than in CD (P < 0.05), in both surgical (13.363% ± 5.303% vs 8.322% ± 5.078%, P = 0.044) and endoscopic specimens (mean rank 13.5 vs 7.5, P = 0.023). The SHG/TPEF imaging described different distribution patterns of collagen between CD and ITB; in the former this was irregular in clumps while in ITB the collagen was arranged around caseating granulomata.

CONCLUSION

The evaluation of fibrosis in CD and ITB by Masson's trichrome staining and SHG and TPEF imaging appears to distinguish between these two diseases.

Novel biomarkers of fibrosis in Crohn’s disease

Fibrosis represents a major challenge in Crohn’s disease (CD), and many CD patients will develop fibrotic strictures requiring treatment throughout their lifetime. There is no drug that can reverse intestinal fibrosis, and so endoscopic balloon dilatation and surgery are the only effective treatments. Since patients may need repeated treatments, it is important to obtain the diagnosis at an early stage before strictures become symptomatic with extensive fibrosis. Several markers of fibrosis have been proposed, but most need further validation. Biomarkers can be measured either in biological samples obtained from the serum or bowel of CD patients, or using imaging tools and tests. The ideal tool should be easily obtained, cost-effective, and reliable. Even more challenging is fibrosis occurring in ulcerative colitis. Despite the important burden of intestinal fibrosis, including its detrimental effect on outcomes and quality of life in CD patients, it has received less attention than fibrosis occurring in other organs. A common mechanism that acts via a specific signaling pathway could underlie both intestinal fibrosis and cancer. A comprehensive overview of recently introduced biomarkers of fibrosis in CD is presented, along with a discussion of the controversial areas remaining in this field.

Biomarkers of intestinal fibrosis - one step towards clinical trials for stricturing inflammatory bowel disease

Intestinal fibrosis, caused by an excessive deposition of extracellular matrix components, and subsequent stricture development are a common complication of inflammatory bowel disease. However, currently there are no biomarkers which reliably predict the risk of developing intestinal strictures or identify early stages of fibrosis prior to clinical symptoms. Candidate biomarkers of intestinal fibrosis, including gene variants (i.e. nucleotide-binding oligomerization domain-2 gene), serum microRNAs (miR-19, miR-29), serum extracellular matrix proteins (i.e. collagen, fibronectin) or enzymes (i.e. tissue inhibitor of matrix metalloproteinase-1), serum growth factors (i.e. basic fibroblast growth factor, YKL-40), serum anti-microbial antibodies (i.e. anti-Saccharomyces cerevisiae) and circulating cells (i.e. fibrocytes) have shown conflicting results on relatively heterogeneous patients' cohorts, and none of them was proven to be strictly specific for fibrostenosis, but rather predictive of a disease disabling course. In this review we critically reassess the diagnostic and prognostic value of serum biomarkers of intestinal fibrosis in inflammatory bowel disease.

Fragments of Citrullinated and MMP-degraded Vimentin and MMP-degraded Type III Collagen Are Novel Serological Biomarkers to Differentiate Crohn's Disease from Ulcerative Colitis

BACKGROUND AND AIMS

A hallmark of inflammatory bowel disease [IBD] is chronic inflammation, which leads to excessive extracellular matrix [ECM] remodelling and release of specific protein fragments, called neoepitopes. We speculated that the biomarker profile panel for ulcerative colitis [UC] and Crohn's disease [CD] represent a heterogeneous expression pattern, and may be applied as a tool to aid in the differentiation between UC and CD.

METHODS

Serum biomarkers of degraded collagens I, III-IV [C1M, C3M, and C4M], collagen type 1 and IV formation [P1NP, P4NP], and citrullinated and MMP-degraded vimentin [VICM] were studied with a competitive ELISA assay system in a cohort including 164 subjects [CD n = 72, UC n = 60, and non-IBD controls n = 32] and a validation cohort of 61 subjects [CD n = 46, and UC n = 15]. Receiver operating characteristic curve analysis and logistic regression modelling were carried out to evaluate the discriminative power of the biomarkers.

RESULTS

All biomarkers were corrected for confounding factors. VICM and C3M demonstrated the highest diagnostic power, alone, to differentiate CD from UC with an area under the curve [AUC] of 0.77 and 0.69, respectively. Furthermore, the biomarkers C1M [AUC = 0.81], C3M [AUC = 0.83], VICM [AUC = 0.83], and P1NP [AUC = 0.77] were best to differentiate UC from non-IBD. The best combinations of biomarkers to differentiate CD from UC and UC from non-IBD were VICM, C3M, C4M [AUC = 0.90] and VICM, C3M [AUC = 0.98] respectively.

CONCLUSIONS

Specific extracellular matrix degradation markers are elevated in IBD and can discriminate CD from UC and UC from non-IBD controls with a high diagnostic accuracy.

Results of the 4th scientific workshop of the ECCO (Group II): markers of intestinal fibrosis in inflammatory bowel disease

The fourth scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on intestinal fibrosis in inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms and markers of intestinal fibrosis as well as to suggest new therapeutic targets to prevent or treat fibrosis. The results of this workshop are presented in three separate manuscripts. This section describes markers of fibrosis in IBD, identifies unanswered questions in the field and provides a framework for future studies addressing the unmet needs in the field of intestinal fibrosis.

IBD candidate genes and intestinal barrier regulation

Technological advances in the large scale analysis of human genetics have generated profound insights into possible genetic contributions to chronic diseases including the inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis. To date, 163 distinct genetic risk loci have been associated with either Crohn's disease or ulcerative colitis, with a substantial degree of genetic overlap between these 2 conditions. Although many risk variants show a reproducible correlation with disease, individual gene associations only affect a subset of patients, and the functional contribution(s) of these risk variants to the onset of IBD is largely undetermined. Although studies in twins have demonstrated that the development of IBD is not mediated solely by genetic risk, it is nevertheless important to elucidate the functional consequences of risk variants for gene function in relevant cell types known to regulate key physiological processes that are compromised in IBD. This article will discuss IBD candidate genes that are known to be, or are suspected of being, involved in regulating the intestinal epithelial barrier and several of the physiological processes presided over by this dynamic and versatile layer of cells. This will include assembly and regulation of tight junctions, cell adhesion and polarity, mucus and glycoprotein regulation, bacterial sensing, membrane transport, epithelial differentiation, and restitution.

Circulating fibrocytes and Crohn's disease

Background

Despite advances in medical therapy, there remains no effective preventive or non-surgical therapeutic option for fibrostenotic Crohn's disease (CD). Symptomatic recurrences are common, necessitating reintervention. Intestinal fibroblasts mediate stricture formation, but their exact source is unclear. Recent evidence indicates that circulating fibrocytes drive fibrosis through differentiation into fibroblasts and the production of extracellular matrix proteins. The aim of this review is to describe current understanding of the pathophysiology underlying fibrosis in CD, the cellular and molecular biology of fibrocytes and their role in CD.

Methods

The electronic literature (January 1972 to December 2012) on ‘circulating fibrocytes’ and ‘Crohn's fibrosis’ was reviewed.

Results

Circulating fibrocytes appear universally involved in organ fibrosis. A complex array of cytokines, chemokines and growth factors regulate fibrocyte biology, and these are associated with fibrogenesis in CD. The cytokines transforming growth factor β1, connective tissue growth factor and interleukin 13, overexpressed in the strictured Crohn's intestine, promote fibrocyte generation and/or differentiation.

Conclusion

Levels of circulating fibrocytes are raised in conditions marked by exaggerated fibrosis. These and other observations prompt a characterization of fibrocyte activity in CD with a view to investigating a pathogenic role.

Moxibustion Inhibits the ERK Signaling Pathway and Intestinal Fibrosis in Rats with Crohn's Disease

Intestinal fibrosis is the main pathological process in Crohn's disease (CD); acupuncture and moxibustion can inhibit the process of fibrosis in CD rats, but the regulatory mechanism remains unknown. The present study observed the effect of moxibustion on the extracellular signal-regulated kinase (ERK) signaling pathway in the CD rat. The result shows that the phosphorylation of the Ras, Raf-1, MEK-1, and ERK-1/2 proteins and the expression of the corresponding mRNAs in the colon tissue of CD rat were significantly higher than the normal control group. Both treatments with mild moxibustion and with herb-separated moxibustion significantly reduced the expression of the Ras, Raf-1, MEK-1, and ERK-1/2 proteins and Ras and Raf-1 mRNA. MEK-1 and ERK-1/2 mRNA expression in each treatment group showed a downward trend, and the ERK-1/2 mRNA levels were significantly lower in the mild moxibustion group. It indicates that Ras, Raf-1, MEK-1, and ERK-1/2 are involved in the process of intestinal fibrosis in CD rats. Moxibustion can downregulate the abnormal expression of colonic Ras, Raf-1, MEK-1, and ERK-1/2 protein and mRNA levels in CD intestinal fibrosis in rats. Moxibustion may play a role in the treatment of CD intestinal fibrosis by regulating ERK signaling pathway.

Nitric oxide pathway-related gene alterations in inflammatory bowel disease

OBJECTIVE

To reveal specific gene activation in nitric oxide (NO)-related inflammation we studied differential gene expression in inflammatory bowel disease (IBD).

METHODS

Total RNA was isolated from 20 biopsies of inflamed mucosa from Crohn's disease (CD) and ulcerative colitis (UC) patients each as well as from six controls, labeled with (32)P-dCTP and hybridized to a human NO gene array. Significant genes were analyzed for functional gene interactions and heatmaps generated by hierarchical clustering. A selection of differentially expressed genes was further evaluated with immunohistochemical staining.

RESULTS

Significant gene expression differences were found for 19 genes in CD and 23 genes in UC compared to controls, both diseases with high expression of ICAM1 and IL-8. Correlation between microarray expression and corresponding protein expression was significant (r = 0.47, p = 0.002). Clustering analysis together with functional gene interaction analysis revealed clusters of coregulation and coexpression in CD and UC: transcripts involved in angiogenesis, inflammatory response mediated by the transcription factor hypoxia-inducible factor 1, and tissue fibrosis. Also, a fourth cluster with transcripts regulated by the transcription factor Sp1 was found in UC.

CONCLUSIONS

Expression analysis in CD and UC revealed disease-specific regulation of NO-related genes, which might be involved in perpetuating inflammatory disease activity in IBD.

Progress in research of biological activity markers for inflammatory bowel disease

The incidence of inflammatory bowel disease (IBD) has been increasing in recent years. The clinical manifestations of IBD are complicated, and both intestinal and extraintestinal symptoms may develop. Due to the lack of specific index, IBD is easy to be misdiagnosed, and evaluating disease activity is more difficult. Radiology, endoscopic and histological biopsy for diagnosis are expensive. Currently, there is an urgent need of a simple, noninvasive, sensitive, economic, and highly specific method for diagnosis of IBD. Biological activity markers may meet this demand. In this paper, the clinical applicability of biological activity markers, which come from both ulcerative colitis (UC) and Crohn's disease (CD), in identifying the presence or extent of inflammatory response, is reviewed.

Predictors of fibrostenotic Crohn's disease

Intestinal fibrosis is a common and serious complication of Crohn's disease (CD) and as it can occur at any time during the disease course, it is crucial to identify patients at risk. The aim is not only to understand the pathophysiology of fibrogenesis but to be able to accurately inform subjects about their disease course, design future trials of potentially useful antifibrotic therapies, and, most important, identify those CD patients at risk, with the view to early, more aggressive medical therapy. This review summarizes the current status of our understanding and ability to predict fibrostenosing CD. The review encompasses three distinct areas: genetic variants, clinical phenotypes, and serologic markers in order to develop a conceptual framework for an understanding of fibrostenotic CD. It also aims to highlight where our knowledge is insufficient in order to identify areas that require future research.

Genetics of ulcerative colitis

Ulcerative colitis (UC) and Crohn's disease (CD) are related polygenic inflammatory bowel diseases (IBDs), with distinct and overlapping susceptibility loci. Recently, hypothesis-free genome-wide association (GWA) studies have revolutionized the field of complex disease genetics. Substantial advances have been achieved in defining the genetic architecture of IBD. To date, over 60 published IBD susceptibility loci have been discovered and replicated, of which approximately a third are associated with both UC and CD, although 21 are specific to UC and 23 to CD. In CD, the breakthrough identification of NOD2 as a susceptibility gene was followed by a rapid phase of gene discovery from GWA studies between 2006 and 2008. Progress in UC was slower; however, by initially testing hits for CD in UC, and later scanning larger UC cohorts, significant new loci for UC have been discovered, with exciting novel insights into disease pathogenesis. Notably, genes implicated in mucosal barrier function (ECM1, CDH1, HNF4α, and laminin B1) confer risk of UC; furthermore, E-cadherin is the first genetic correlation between colorectal cancer and UC. Impaired IL10 signaling has reemerged as a key pathway in intestinal inflammation, and is perhaps the most amenable to therapeutic intervention in UC. Collaborative international efforts with large meta-analyses of GWA studies and replication will yield many new UC genes. Furthermore, a large effort is required to characterize the loci found. Fine-mapping, deep resequencing, and functional studies will be critical to translating these gene discoveries into pathogenic insights, and ultimately into clinical insights and novel therapeutics.

[Fibrogenesis and inflammatory bowel disease]

A substantial proportion of patients with Crohn's disease develops intestinal stenosis due to anomalous fiber deposits. These patients frequently require resection of the affected segment. Despite its evident clinical significance, intestinal fibrogenesis has received little attention in comparison with research into hepatic, pulmonary, renal or cutaneous fibrosis. There seems to be a certain genetic predisposition to developing intestinal fibrosis. A meta-analysis has demonstrated that the three main variants of the NOD2/CARD15 gene are associated with this complication. In Crohn's disease, a series of alterations in collagen synthesis, expression of various pro- and anti-fibrogenic factors and intestinal fibroblast function have been described in the last few years. More recently, the development of intestinal fibrosis has been attenuated in several experimental models. Nevertheless, further studies are required to improve our understanding of intestinal fibrogenesis and to develop effective strategies for its prevention and treatment.

Unique dietary-related mouse model of colitis

BACKGROUND

A high-fat diet is a risk factor for the development of inflammatory bowel disease (IBD) in humans. Deoxycholate (DOC) is increased in the colonic contents in response to a high-fat diet. Thus, an elevated level of DOC in the colonic lumen may play a role in the natural course of development of IBD.

METHODS

Wild-type B6.129 mice were fed an AIN-93G diet, either supplemented with 0.2% DOC or unsupplemented and sacrificed at 1 week, 1 month, 3 months, 4 months, and 8 months. Colon samples were assessed by histopathological, immunohistochemical, and cDNA microarray analyses.

RESULTS

Mice fed the DOC-supplemented diet developed focal areas of colonic inflammation associated with increases in angiogenesis, nitrosative stress, DNA/RNA damage, and proliferation. Genes that play a central role in inflammation and angiogenesis and other related processes such as epithelial barrier function, oxidative stress, apoptosis, cell proliferation/cell cycle/DNA repair, membrane transport, and the ubiquitin-proteasome pathway showed altered expression in the DOC-fed mice compared with the control mice. Changes in expression of individual genes (increases or reductions) correlated over time. These changes were greatest 1 month after the start of DOC feeding.

CONCLUSIONS

The results suggest that exposure of the colonic mucosa to DOC may be a key etiologic factor in IBD. The DOC-fed mouse model may reflect the natural course of development of colitis/IBD in humans, and thus may be useful for determining new preventive strategies and lifestyle changes in affected individuals.

A chemotactic peptide from laminin alpha 5 functions as a regulator of inflammatory immune responses via TNF alpha-mediated signaling

Tissue injury triggers inflammatory responses that may result in release of degradation products or exposure of cryptic domains of extracellular matrix components. Previously, we have shown that a cryptic peptide (AQARSAASKVKVSMKF) in the alpha-chain of laminin-10 (alpha5beta1gamma1), a prominent basement membrane component, is chemotactic for both neutrophils (PMNs) and macrophages (Mphis) and induces matrix metalloproteinase-9 (MMP-9) production. To determine whether AQARSAASKVKVSMKF has additional effects on inflammatory cells, we performed microarray analysis of RNA from RAW264.7 Mphis stimulated with AQARSAASKVKVSMKF. Several cytokines and cytokine receptors were increased >3-fold in response to the laminin alpha5 peptide. Among these were TNF-alpha and one of its receptors, the p75 TNFR (TNFR-II), increasing 3.5- and 5.7-fold, respectively. However, the peptide had no effect on p55 TNFR (TNFR-I) expression. Corroborating the microarray data, the protein levels of TNF-alpha and TNFR-II were increased following stimulation of RAW264.7 cells with AQARSAASKVKVSMKF. In addition, we determined that the production of TNF-alpha and TNFR-II in response to AQARSAASKVKVSMKF preceded the production of MMP-9. Furthermore, using primary Mphis from mice deficient in TNFR-I, TNFR-II, or both TNF-alpha receptors (TNFRs), we determined that AQARSAASKVKVSMKF induces MMP-9 expression by Mphis through a pathway triggered by TNFR-II. However, TNF-alpha signaling is not required for AQARSAASKVKVSMKF-induced PMN release of MMP-9 or PMN emigration. These data suggest that interactions of inflammatory cells with basement membrane components may orchestrate immune responses by inducing expression of cytokines, recruitment of inflammatory cells, and release of proteinases.