Serpin B1 protects colonic epithelial cell via blockage of neutrophil elastase activity and its expression is enhanced in patients with ulcerative colitis

The proteolytic activity in inflammatory bowel disease: insight from gut microbiota

Inflammatory bowel disease (IBD) is a chronic, recurrent inflammatory disease caused by the destruction of the intestinal mucosal epithelium that affects a growing number of people worldwide. Although the etiology of IBD is complex and still elucidated, the role of dysbiosis and dysregulated proteolysis is well recognized. Various studies observed altered composition and diversity of gut microbiota, as well as increased proteolytic activity (PA) in serum, plasma, colonic mucosa, and fecal supernatant of IBD compared to healthy individuals. The imbalance of intestinal microecology and intestinal protein hydrolysis were gradually considered to be closely related to IBD. Notably, the pivotal role of intestinal microbiota in maintaining proteolytic balance received increasing attention. In summary, we have speculated a mesmerizing story, regarding the hidden role of PA and microbiota-derived PA hidden in IBD. Most importantly, we provided the diagnosis and therapeutic targets for IBD as well as the formulation of new treatment strategies for other digestive diseases and protease-related diseases.

Methylation-Regulated Long Non-Coding RNA Expression in Ulcerative Colitis

Long non-coding RNAs (lncRNAs) have been shown to play a role in the pathogenesis of ulcerative colitis (UC). Although epigenetic processes such as DNA methylation and lncRNA expression are well studied in UC, the importance of the interplay between the two processes has not yet been fully explored. It is, therefore, believed that interactions between environmental factors and epigenetics contribute to disease development. Mucosal biopsies from 11 treatment-naïve UC patients and 13 normal controls were used in this study. From each individual sample, both whole-genome bisulfite sequencing data (WGBS) and lncRNA expression data were analyzed. Correlation analysis between lncRNA expression and upstream differentially methylated regions (DMRs) was used to identify lncRNAs that might be regulated by DMRs. Furthermore, proximal protein-coding genes associated with DMR-regulated lncRNAs were identified by correlating their expression. The study identified UC-associated lncRNAs such as MIR4435-2HG, ZFAS1, IL6-AS1, and Pvt1, which may be regulated by DMRs. Several genes that are involved in inflammatory immune responses were found downstream of DMR-regulated lncRNAs, including SERPINB1, CCL18, and SLC15A4. The interplay between lncRNA expression regulated by DNA methylation in UC might improve our understanding of UC pathogenesis.

Mucosal addressin cell adhesion molecule 1 expression reflects mucosal inflammation and subsequent relapse in patients with ulcerative colitis

BACKGROUND AND AIMS

Mucosal addressin cell adhesion molecule 1 (MAdCAM-1) is upregulated in the vascular endothelium of the colonic mucosa in ulcerative colitis (UC). Although the association between MAdCAM-1 expression and mucosal inflammation has been discussed, the association with the clinical course of UC patients has not been reported. In this study we investigated not only the association between mucosal MAdCAM-1 expression and mucosal inflammation, but also its association with subsequent relapse in UC patients with clinical remission.

METHODS

Eighty UC patients in remission who visited Kyoto Prefectural University of Medicine for follow-up for 2 years were included. Biopsy samples were collected during colonoscopy, and transcriptional expression levels of UC-related cytokines and MAdCAM-1 were quantified using real-time polymerase chain reaction. MAdCAM-1 mRNA expression and protein expression by immunohistochemistry was compared in patients who subsequently relapsed and those who remained in remission and examined in relation to endoscopic findings, histologic activity, and cytokine expression.

RESULTS

MAdCAM-1 expression was correlated with endoscopic severity, and significantly elevated in histological active mucosa than inactive mucosa. Furthermore, MAdCAM-1 expression levels were closely correlated with those of several cytokines. MAdCAM-1 mRNA and protein expression were significantly higher in the relapse group than in the remission group, indicating that MAdCAM-1 expression in the mucosa is already elevated in UC patients in clinical remission who subsequently relapse.

CONCLUSIONS

MAdCAM-1 expression in the colonic mucosa of UC patients related to mucosal inflammation and subsequent relapse; it may serve as a marker for both relapse and therapeutic effectiveness in UC.

Investigation on the Inhibitory Effect of Wnt-5a on Colonic Mucosal Inflammation in Patients with Ulcerative Colitis

BACKGROUND

Recent progress in ulcerative colitis (UC) treatment has been remarkable, and various medications have been applied. However, some patients with UC are refractory to treatment and convert to surgery.

AIM

To investigate the role of colonic mucosal Wnt-5a expression in the pathogenesis of UC and the effect of bioactive Wnt-5a peptide on colitis in mice.

METHODS

Wnt-5a peptide was intraperitoneally administered to mice every day from the beginning of dextran sulfate sodium (DSS) treatment. The severity of colitis was evaluated based on body weight change, colonic length, and histological scores. Colonic mucosal TNF-α and KC mRNA expression levels were measured. This study included 70 patients with UC in clinical remission. Wnt-5a, TNFα, and IL-8 mRNA expression in the rectal mucosa were measured by quantitative real-time polymerase chain reaction using biopsy materials. Wnt-5a mRNA expression levels were compared between patients who relapsed and those in remission. We examined the correlation of Wnt-5a expression with TNF-α and IL-8 expression.

RESULTS

Wnt-5a peptide significantly attenuated the severity of DSS-induced colitis. Moreover, mucosal TNF-α and KC mRNA expression were significantly suppressed by Wnt-5a peptide treatment. Wnt-5a mRNA levels were significantly lower in patients with subsequent relapse than in those who remained in remission. Mucosal Wnt-5a was inversely correlated with TNF α and IL-8 expression.

CONCLUSION

Wnt-5a peptide suppressed colitis in mice, and decreased Wnt-5a expression was strongly associated with relapse in patients with UC. Wnt-5a may have an inhibitory effect on mucosal inflammation in UC, and Wnt-5a peptide could be a new therapeutic strategy.

Proteomics Profiling of Stool Samples from Preterm Neonates with SWATH/DIA Mass Spectrometry for Predicting Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a life-threatening condition for premature infants in neonatal intensive care units. Finding indicators that can predict NEC development before symptoms appear would provide more time to apply targeted interventions. In this study, stools from 132 very-low-birth-weight (VLBW) infants were collected daily in the context of a multi-center prospective study aimed at investigating the potential of fecal biomarkers for NEC prediction using proteomics technology. Eight of the VLBW infants received a stage-3 NEC diagnosis. Stools collected from the NEC infants up to 10 days before their diagnosis were available for seven of them. Their samples were matched with those from seven pairs of non-NEC controls. The samples were processed for liquid chromatography-tandem mass spectrometry analysis using SWATH/DIA acquisition and cross-compatible proteomic software to perform label-free quantification. ROC curve and principal component analyses were used to explore discriminating information and to evaluate candidate protein markers. A series of 36 proteins showed the most efficient capacity with a signature that predicted all seven NEC infants at least a week in advance. Overall, our study demonstrates that multiplexed proteomic signature detection constitutes a promising approach for the early detection of NEC development in premature infants.

Dietary Inclusion of Dried Chicory Root Affects Cecal Mucosa Proteome of Nursery Pigs

Simple Summary

A well-balanced diet seems to play a key role in disease prevention and health promotion in young animals. Therefore, many attempts have been made to supplement feeds with novel nutritional components, with potential prebiotic capacity. It seems that chicory root fulfils those criteria as it contains high amounts of inulin-type fructans. Hence, the aim of the study was to determine the effect of dietary supplementation with 4% dried chicory root on the cecal mucosa proteome of piglets. It is shown that this feed additive may affect cellular metabolism in the cecal epithelium and may be beneficial for gut health.

Abstract

Prebiotics are known to have many beneficial effects on intestinal health by modulating the gut microbiota composition, thereby affecting epithelial cell proliferation and metabolism. This study had two aims: (1) to identify the protein constituents in the cecal mucosa of 50-day-old healthy (PIC × Penarlan P76) barrows, and (2) to assess the effects of 4% inclusion of dried chicory root in a cereal-based diet on the cecal mucosa proteome changes. Pigs (eight per group) were randomly allotted to the groups and were fed a control diet from the tenth day of life (C) or a diet supplemented with 4% of died chicory root (CR), for 40 days. At the age of 50 days, animals were sacrificed and cecal tissue samples were collected. It was found that feeding a CR diet significantly decreased the expression of 16 cecal mucosa proteins. Among them, fifteen proteins were down-regulated, while only one (KRT20) was shown to be up-regulated when compared to the C group. Dietary supplementation with CR caused down-expression of metabolism-associated proteins including enzymes involved in the process of glycolysis (G6PD, TPI1, ALDH9A1, CKMT1 and AKR1A1) as well as those engaged in transcriptional and translational activity (PRPF19, EEF1G) and several structural proteins (ACTR3, KRT77, CAP1 and actin). From our findings, it is possible to conclude that dietary chicory root at 4% had beneficial effects on the gut health of pigs as indicated by a changed abundance of certain cecal proteins such as KRT20, SERPINB1, HSP27, ANAXA2 and ANAXA4.

Mucosal interleukin-8 expression as a predictor of subsequent relapse in ulcerative colitis patients with Mayo endoscopic subscore 0

BACKGROUND AND AIM

Complete endoscopic mucosal healing is defined as a Mayo endoscopic subscore of 0. Some patients diagnosed with a Mayo endoscopic subscore 0 may present with subsequent clinical relapse. Here, we aimed to demonstrate mucosal cytokine profile as a predictor of clinical relapse in ulcerative colitis patients with a Mayo endoscopic subscore of 0 as a marker of mucosal healing.

METHODS

We conducted prospective observational pilot study to examine the relationship between mucosal cytokine expression and subsequent relapse of UC patients diagnosed with a Mayo endoscopic subscore of 0. We enrolled 55 patients, and expression of cytokines tumor necrosis factor-α, interferon γ, interleukin-1β, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-7, interleukin-8, interleukin-9, interleukin-10, interleukin-12, interleukin-13, interleukin-15, interleukin-17A, interleukin-17F, interleukin-18, interleukin-21, interleukin-22, interleukin-23, interleukin-27, and interleukin-33 was measured by quantitative real-time PCR using rectal mucosa biopsy materials. Cytokine expression levels were compared between patients who relapsed between March 1, 2016, and March 30, 2020, of the study period and those who remained in remission.

RESULTS

Ten cytokines, including interleukin-2, interleukin-4, interleukin-8, interleukin-10, interleukin-12, interleukin-15, interleukin-17A, interleukin-21, interleukin-23, and interleukin-33, were significantly elevated in patients with subsequent relapse compared with those who remained in remission. Interleukin-8 expression was the most useful predictor.

CONCLUSIONS

In the rectal mucosa of ulcerative colitis patients with Mayo endoscopic subscore 0, levels of several cytokines were elevated in cases of subsequent relapse. Among these, interleukin-8 expression was the most useful for predicting relapse.

Complement factor D as a predictor of Achilles tendon healing and long-term patient outcomes

Dense connective tissue healing, such as tendon, is protracted leading to highly variable and unsatisfactory patient outcomes. Biomarkers prognostic of long-term clinical outcomes is, however, unknown. The present study was designed to investigate the proteomic profile of healing, identify potential biomarkers, and assess their association with the patient's long-term outcomes after ATR. Quantitative mass spectrometry analysis demonstrated 1423 proteins in healing and contralateral healthy Achilles tendons of 28 ATR patients. Comparing healing at 2 weeks and healthy protein profiles, we identified 821 overlapping, 390 upregulated, and 17 downregulated proteins. Upregulated proteins are related mainly to extracellular matrix organization and metabolism, while downregulated pathways were associated with exocytosis in immune modulation and thrombosis formation. Further proteomic profiling in relation to validated patient outcomes revealed the downregulated pro-inflammatory complement factor D (CFD) as the most reliable predictive biomarker of successful tendon healing. Our finding showed a comprehensive proteomic landscape and bioinformatics on human connective tissue, indicating subtype-specific and shared biological processes and proteins in healing and healthy Achilles tendons, as well as in tendons related to good and poor patient outcomes. Inflammatory protein CFD and serpin family B member 1 were finally identified as potential predictive biomarkers of effective healing outcomes when combined the proteomic profiles with a validated clinical database. Following the future elucidation of the mechanisms associated with the identified biomarkers as predictors of good outcomes, our findings could lead to improved prognostic accuracy and development of targeted treatments, thus improving the long-term healing outcomes for all patients.

Quantitative metaproteomics and activity-based protein profiling of patient fecal microbiome identifies host and microbial serine-type endopeptidase activity associated with ulcerative colitis

The gut microbiota plays an important yet incompletely understood role in the induction and propagation of ulcerative colitis (UC). Organism-level efforts to identify UC-associated microbes have revealed the importance of community structure, but less is known about the molecular effectors of disease. We performed 16S rRNA gene sequencing in parallel with label-free data-dependent LC-MS/MS proteomics to characterize the stool microbiomes of healthy (n = 8) and UC (n = 10) patients. Comparisons of taxonomic composition between techniques revealed major differences in community structure partially attributable to the additional detection of host, fungal, viral, and food peptides by metaproteomics. Differential expression analysis of metaproteomic data identified 176 significantly enriched protein groups between healthy and UC patients. Gene ontology analysis revealed several enriched functions with serine-type endopeptidase activity overrepresented in UC patients. Using a biotinylated fluorophosphonate probe and streptavidin-based enrichment, we show that serine endopeptidases are active in patient fecal samples and that additional putative serine hydrolases are detectable by this approach compared with unenriched profiling. Finally, as metaproteomic databases expand, they are expected to asymptotically approach completeness. Using ComPIL and de novo peptide sequencing, we estimate the size of the probable peptide space unidentified (“dark peptidome”) by our large database approach to establish a rough benchmark for database sufficiency. Despite high variability inherent in patient samples, our analysis yielded a catalog of differentially enriched proteins between healthy and UC fecal proteomes. This catalog provides a clinically relevant jumping-off point for further molecular-level studies aimed at identifying the microbial underpinnings of UC.

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Identified 176 significantly altered protein groups between healthy and UC patients.

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Serine-type endopeptidase activity is overrepresented in UC patients.

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Fluorophosphonate ABPP shows that endopeptidases are active in fecal samples.

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ABPP enrichment helps identify additional putative serine hydrolases in samples.

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De novo sequencing used to estimate number of MS2 spectra unidentified by ComPIL.

Colitis Linked to Endoplasmic Reticulum Stress Induces Trypsin Activity Affecting Epithelial Functions

BACKGROUND AND AIMS

Intestinal epithelial cells [IECs] from inflammatory bowel disease [IBD] patients exhibit an excessive induction of endoplasmic reticulum stress [ER stress] linked to altered intestinal barrier function and inflammation. Colonic tissues and the luminal content of IBD patients are also characterized by increased serine protease activity. The possible link between ER stress and serine protease activity in colitis-associated epithelial dysfunctions is unknown. We aimed to study the association between ER stress and serine protease activity in enterocytes and its impact on intestinal functions.

METHODS

The impact of ER stress induced by Thapsigargin on serine protease secretion was studied using either human intestinal cell lines or organoids. Moreover, treating human intestinal cells with protease-activated receptor antagonists allowed us to investigate ER stress-resulting molecular mechanisms that induce proteolytic activity and alter intestinal epithelial cell biology.

RESULTS

Colonic biopsies from IBD patients exhibited increased epithelial trypsin-like activity associated with elevated ER stress. Induction of ER stress in human intestinal epithelial cells displayed enhanced apical trypsin-like activity. ER stress-induced increased trypsin activity destabilized intestinal barrier function by increasing permeability and by controlling inflammatory mediators such as C-X-C chemokine ligand 8 [CXCL8]. The deleterious impact of ER stress-associated trypsin activity was specifically dependent on the activation of protease-activated receptors 2 and 4.

CONCLUSIONS

Excessive ER stress in IECs caused an increased release of trypsin activity that, in turn, altered intestinal barrier function, promoting the development of inflammatory process.

Protease inhibitory activity of secretory leukocyte protease inhibitor ameliorates murine experimental colitis by protecting the intestinal epithelial barrier

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder in the intestine, and the dysfunction of intestinal epithelial barrier (IEB) may trigger the onset of IBD. Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that has been implicated in the tissue-protective effect in the skin and lung. We found that SLPI was induced in lipopolysaccharides-treated colon carcinoma cell line and in the colon of dextran sulfate sodium (DSS)-treated mice. SLPI-deficient mice were administered DSS to induce colitis and sustained severe inflammation compared with wild-type mice. The colonic mucosa of SLPI-deficient mice showed more severe inflammation with neutrophil infiltration and higher levels of proinflammatory cytokines compared with control mice. Moreover, neutrophil elastase (NE) activity in SLPI-deficient mice was increased and IEB function was severely impaired in the colon, accompanied with the increased number of apoptotic cells. Importantly, we demonstrated that DSS-induced colitis was ameliorated by administration of protease inhibitor SSR69071 and recombinant SLPI. These results suggest that the protease inhibitory activity of SLPI protects from colitis by preventing IEB dysfunction caused by excessive NE activity, which provides insight into the novel function of SLPI in the regulation of gut homeostasis and therapeutic approaches for IBD.

Increased mucosal IL-12 expression is associated with relapse of ulcerative colitis

Background

The role of IL-12/23 in the pathogenesis of ulcerative colitis (UC) is unclear. We analyzed mucosal IL-12/23 expression and its relationship with endoscopic severity, histological activity, and UC relapse.

Methods

Rectal biopsies were collected from 70 UC patients with clinical remission. IL-12, IL-23, IFN-γ, IL-17A, and IL-17F mRNA expression was measured by real-time PCR. Endoscopic severity and histological activity were evaluated using the Mayo endoscopic subscore (MES) and the Geboes score, respectively.

Results

The longest follow-up period was 51 months. Thirty-four patients relapsed during the study period. Samples from these subsequently relapsed patients formed the “relapse” group, while those from patients that did not relapse formed the “remission” group. IL-12 (P = 0.0003) and IL-23 (P = 0.014) mRNA expression was significantly higher in the relapse than the remission group. Expression of IL-23 (P = 0.015) but not IL-12 (P = 0.374) was correlated with MES. However, in patients with an MES of 0 and 1, IL-12 expression was statistically higher in the relapse than the remission group (P = 0.0015, P = 0.0342). IL-12 and IL-23 expression did not vary significantly between histologically active and inactive mucosa; both were higher in histologically inactive patients in the remission group (IL-12: P = 0.0002, IL-23: P = 0.046).

Conclusions

Rectal IL-12 and IL-23 expression was elevated in the relapse group, but IL-12 was more strongly associated with UC relapse, irrespective of endoscopic severity and histological activity. Mucosal IL-12 was elevated in patients with deep mucosal healing. Our results suggest an important role of IL-12 in UC pathogenesis and the molecular mechanism of UC relapse.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12876-021-01709-5)

Inflammation-Induced Abnormal Expression of Self-molecules on Epithelial Cells: Targets for Tumor Immunoprevention

Tumor-associated antigens (TAA) are self-molecules abnormally expressed on tumor cells, which elicit humoral and cellular immunity and are targets of immunosurveillance. Immunity to TAAs is found in some healthy individuals with no history of cancer and correlates positively with a history of acute inflammatory and infectious events and cancer risk reduction. This suggests a potential role in cancer immunosurveillance for the immune memory elicited against disease-associated antigens (DAA) expressed on infected and inflamed tissues that are later recognized on tumors as TAAs. To understand probable sources for DAA generation, we investigated in vitro the role of inflammation that accompanies both infection and carcinogenesis. After exposure of normal primary breast epithelial cells to proinflammatory cytokines IL1β, IL6, and TNFα, or macrophages producing these cytokines, we saw transient overexpression of well-known TAAs, carcinoembryonic antigen and Her-2/neu, and overexpression and hypoglycosylation of MUC1. We documented inflammation-induced changes in the global cellular proteome by 2D difference gel electrophoresis combined with mass spectrometry and identified seven new DAAs. Through gene profiling, we showed that the cytokine treatment activated NF-κB and transcription of the identified DAAs. We tested three in vitro-identified DAAs, Serpin B1, S100A9, and SOD2, and found them overexpressed in premalignant and malignant breast tissues as well as in inflammatory conditions of the colon, stomach, and liver. This new category of TAAs, which are also DAAs, represent a potentially large number of predictable, shared, immunogenic, and safe antigens to use in preventative cancer vaccines and as targets for cancer therapies.

Serine proteases at the cutting edge of IBD: Focus on gastrointestinal inflammation

Serine proteases have been long recognized to coordinate many physiological processes and play key roles in regulating the inflammatory response. Accordingly, their dysregulation has been regularly associated with several inflammatory disorders and suggested as a central mechanism in the pathophysiology of digestive inflammation. So far, studies addressing the proteolytic homeostasis in the gut have mainly focused on host serine proteases as candidates of interest, while largely ignoring the potential contribution of their bacterial counterparts. The human gut microbiota comprises a complex ecosystem that contributes to host health and disease. Yet, our understanding of microbially produced serine proteases and investigation of whether they are causally linked to IBD is still in its infancy. In this review, we highlight recent advances in the emerging roles of host and bacterial serine proteases in digestive inflammation. We also discuss the application of available tools in the gut to monitor disease-related serine proteases. An exhaustive representation and understanding of such functional potential would help in closing existing gaps in mechanistic knowledge.

Neutrophil Elastase and Neutrophil Extracellular Traps in the Tumor Microenvironment

Tumor-associated neutrophils (TANs) play a major role during cancer development and progression in the tumor microenvironment. Neutrophil elastase (NE) is a serine protease normally expressed in neutrophil primary granules. Formation of neutrophil extracellular traps (NETs), a mechanism used by neutrophils, has been traditionally associated with the capture and killing of bacteria. However, there are recent discoveries suggesting that NE secretion and NETs formation are also involved in the tumor microenvironment. Here, we focus on how NE and NETs play a key regulatory function in the tumor microenvironment, such as tumor proliferation, distant metastasis, tumor-associated thrombosis, and antitumor activity. Additionally, the potential use of NETs, NE, or associated molecules as potential disease activity biomarkers or therapeutic targets will be introduced.

WNT gene polymorphisms and predisposition to apical periodontitis

Single nucleotide polymorphisms (SNPs) in WNT genes may impact gene/protein function and contribute to individual predisposition to apical periodontitis (AP). Here, we investigated the association of SNPs in/nearby WNT3, WNT3A, WNT5A, WNT8A, WNT9B and WNT11 genes with AP using a case-control dataset. Cases were defined as individuals with deep caries and AP (n = 188); controls had deep caries and no AP (n = 230). Genotyping was performed using Taqman chemistry in real time PCR. Data analyses was performed using Fisher Exact tests assuming a Bonferroni correction threshold value of 0.005. Single-SNP association analysis revealed a trend for association with WNT3 rs9890413 genotypes (P = 0.009) under a dominant model and allelic association for WNT3A rs1745420 (P = 0.009). Haplotypes involving WNT3-WNT9B-WNT3A alleles were also significantly associated with AP (P ≤ 0.003). Luciferase reporter assays showed higher transcriptional activity (1.4-fold) with the alternate G allele in rs1745420. Expression of WNT3, WNT3A and WNT5A in AP tissues was significantly higher than in control tissues, and inversely correlated with the expression of SERPINB1, COL1A1 and TIMP1 (P < 0.05). Our results suggest that WNT genes have a role in modulating AP and polymorphisms in these genes may increase susceptibility to AP.

Application of a chemical probe to detect neutrophil elastase activation during inflammatory bowel disease

Neutrophil elastase is a serine protease that has been implicated in the pathogenesis of inflammatory bowel disease. Due to post-translational control of its activation and high expression of its inhibitors in the gut, measurements of total expression poorly reflect the pool of active, functional neutrophil elastase. Fluorogenic substrate probes have been used to measure neutrophil elastase activity, though these tools lack specificity and traceability. PK105 is a recently described fluorescent activity-based probe, which binds to neutrophil elastase in an activity-dependent manner. The irreversible nature of this probe allows for accurate identification of its targets in complex protein mixtures. We describe the reactivity profile of PK105b, a new analogue of PK105, against recombinant serine proteases and in tissue extracts from healthy mice and from models of inflammation induced by oral cancer and Legionella pneumophila infection. We apply PK105b to measure neutrophil elastase activation in an acute model of experimental colitis. Neutrophil elastase activity is detected in inflamed, but not healthy, colons. We corroborate this finding in mucosal biopsies from patients with ulcerative colitis. Thus, PK105b facilitates detection of neutrophil elastase activity in tissue lysates, and we have applied it to demonstrate that this protease is unequivocally activated during colitis.

Neutrophils and neutrophil extracellular traps in the liver and gastrointestinal system

Neutrophil extracellular traps (NETs) have an important role during infection by helping neutrophils to capture and kill pathogens. However, evidence is accumulating that uncontrolled or excessive production of NETs is related to the exacerbation of inflammation and the development of autoimmunity, cancer metastasis and inappropriate thrombosis. In this Review, we focus on the role of NETs in the liver and gastrointestinal system, outlining their protective and pathological effects. The latest mechanistic insights in NET formation, interactions between microorganisms and NETs and the relationship between neutrophil subtypes and their functions are also discussed. Additionally, we describe the potential importance of NET-related molecules, including cell-free DNA and hypercitrullinated histones, as biomarkers and targets for therapeutic intervention in gastrointestinal diseases.

A Commensal Bifidobacterium longum Strain Prevents Gluten-Related Immunopathology in Mice through Expression of a Serine Protease Inhibitor

Microbiota-modulating strategies, including probiotic administration, have been tested for the treatment of chronic gastrointestinal diseases despite limited information regarding their mechanisms of action. We previously demonstrated that patients with active celiac disease have decreased duodenal expression of elafin, a human serine protease inhibitor, and supplementation of elafin by a recombinant Lactococcus lactis strain prevents gliadin-induced immunopathology in the NOD/DQ8 mouse model of gluten sensitivity. The commensal probiotic strain Bifidobacterium longum NCC2705 produces a serine protease inhibitor (Srp) that exhibits immune-modulating properties. Here, we demonstrate that B. longum NCC2705, but not a srp knockout mutant, attenuates gliadin-induced immunopathology and impacts intestinal microbial composition in NOD/DQ8 mice. Our results highlight the beneficial effects of a serine protease inhibitor produced by commensal B. longum strains.IMPORTANCE Probiotic therapies have been widely used to treat gastrointestinal disorders with variable success and poor mechanistic insight. Delivery of specific anti-inflammatory molecules has been limited to the use of genetically modified organisms, which has raised some public and regulatory concerns. By examining a specific microbial product naturally expressed by a commensal bacterial strain, we provide insight into a mechanistic basis for the use of B. longum NCC2705 to help treat gluten-related disorders.

Fluorescent diphenylphosphonate-based probes for detection of serine protease activity during inflammation

Activity-based probes are small molecules that covalently bind to the active site of a protease in an activity-dependent manner. We synthesized and characterized two fluorescent activity-based probes that target serine proteases with trypsin-like or elastase-like activity. We assessed the selectivity and potency of these probes against recombinant enzymes and demonstrated that while they are efficacious at labeling active proteases in complex protein mixtures in vitro, they are less valuable for in vivo studies. We used these probes to evaluate serine protease activity in two mouse models of acute inflammation, including pancreatitis and colitis. As anticipated, the activity of trypsin-like proteases was increased during pancreatitis. Levels of elastase-like proteases were low in pancreatic lysates and colonic luminal fluids, whether healthy or inflamed. Exogenously added recombinant neutrophil elastase was inhibited upon incubation with these samples, an effect that was augmented in inflamed samples compared to controls. These data suggest that endogenous inhibitors and elastase-degrading proteases are upregulated during inflammation.

The hidden side of SERPINB1/Leukocyte Elastase Inhibitor

SERPINB1, also called Leukocyte Elastase Inhibitor (LEI) is a member of the clade B of SERPINS. It is an intracellular protein and acts primarily to protect the cell from proteases released into the cytoplasm during stress. Its role in inflammation is clear due to its involvement in the resolution of chronic inflammatory lung and bowel diseases. LEI/SERPINB1 intrinsically possesses two enzymatic activities: an antiprotease activity dependent on its reactive site loop, which is analogous to the other proteins of the family and an endonuclease activity which is unveiled by the cleavage of the reactive site loop. The conformational change induced by this cleavage also unveils a bipartite nuclear localization signal allowing the protein to translocate to the nucleus. Recent data indicate that it has also a role in cell migration suggesting that it could be involved in diverse processes like wound healing and malignant metastases.

Pathophysiological roles of proteases in gastrointestinal disease

Gastrointestinal diseases, such as irritable bowel syndrome, inflammatory bowel disease, and colorectal cancer, affect a large proportion of the population and are associated with many unpleasant symptoms. Although the causes of these diseases remain largely unknown, there is increasing evidence to suggest that dysregulated protease activity may be a contributing factor. Proteases are enzymes that cleave other proteins, and their activity is normally very tightly regulated. During disease, however, the balance between proteases and their inhibitors is often shifted, leading to altered spatial and temporal control of substrate cleavage. Evaluating protease levels in normal physiology and disease has relied heavily on the use of chemical tools. Although these tools have greatly advanced the field, they are not without caveats. This review provides an introduction to these tools, their application in the gut, and a summary of the current knowledge on the contribution of protease activity to gastrointestinal disease.

Circulating SerpinB1 levels and clinical features in patients with type 2 diabetes

OBJECTIVE

The main purpose of this study was to investigate the association of serum SerpinB1 levels and various parameters in patients with type 2 diabetes. The effect of canagliflozin (a sodium glucose cotransporter 2 (SGLT2) inhibitor), which can decrease circulating insulin levels, on serum SerpinB1 levels was also investigated. A recent study suggests that the serum levels of SerpinB1, also known as monocyte neutrophil elastase inhibitor, increase with insulin resistance, may have a protective effect for pancreatic β cells, and may decrease insulin resistance.

RESEARCH DESIGN AND METHODS

The study included 30 patients with type 2 diabetes hospitalized for glycemic control and 10 control subjects.

RESULTS

SerpinB1 levels were significantly higher in patients with type 2 diabetes, compared with that in heathy control subjects (10.01±3.59 vs 5.69±1.64 ng/mL, p<0.0001). Serum SerpinB1 levels had a significant negative correlation with low-density lipoprotein cholesterol (LDL-C) (p=0.0123). Serum SerpinB1 levels had a significant positive association or trend toward a positive association with age and with hemoglobin A1c (HbA1c), and significant negative association with LDL-C levels in some multiple regression analysis models. Patients treated with statins had a tendency toward higher serum SerpinB1 levels, compared with those patients not treated with statins. During a 3-day observation period both with and without canagliflozin treatment, the serum SerpinB1 levels did not change.

CONCLUSIONS

Serum SerpinB1 levels are elevated in patients with type 2 diabetes compared with that in healthy subjects and are negatively correlated with serum LDL-C.

Faecal proteomics: A tool to investigate dysbiosis and inflammation in patients with cystic fibrosis

BACKGROUND

Several microbial studies reported gut microbiota dysbiosis in patients with cystic fibrosis (CF). The functional consequences of this phenomenon are poorly understood. Faecal metaproteomics allows the quantitative analysis of host and microbial proteins to address functional changes resulting from this dysbiosis.

METHODS

We analysed faecal protein extracts from fifteen patients with CF that have pancreatic insufficiency and from their unaffected siblings by shotgun proteomics. Novel computational and statistical tools were introduced to evaluate changes in taxonomic composition and protein abundance.

RESULTS

Faecal protein extracts from patients with CF were dominated by host proteins involved in inflammation and mucus formation. Taxonomic analysis of the microbial proteins confirmed the strong reduction of butyrate reducers such as Faecalibacterium prausnitzii and increase of Enterobacteriaceae, Ruminococcus gnavus and Clostridia species.

CONCLUSION

Faecal metaproteomics provides insights in intestinal dysbiosis, inflammation in patients with CF and can be used to monitor different disease markers in parallel.

Review article: the role of oxidative stress in pathogenesis and treatment of inflammatory bowel diseases

In this review, we focus on the role of oxidative stress in the aetiology of inflammatory bowel diseases (IBD) and colitis-associated colorectal cancer and discuss free radicals and free radical-stimulated pathways as pharmacological targets for anti-IBD drugs. We also suggest novel anti-oxidative agents, which may become effective and less-toxic alternatives in IBD and colitis-associated colorectal cancer treatment. A Medline search was performed to identify relevant bibliography using search terms including: ‘free radicals,’ ‘antioxidants,’ ‘oxidative stress,’ ‘colon cancer,’ ‘ulcerative colitis,’ ‘Crohn’s disease,’ ‘inflammatory bowel disease.’ Several therapeutics commonly used in IBD treatment, among which are immunosuppressants, corticosteroids and anti-TNF-α antibodies, could also affect the IBD progression by interfering with cellular oxidative stress and cytokine production. Experimental data shows that these drugs may effectively scavenge free radicals, increase anti-oxidative capacity of cells, influence multiple signalling pathways, e.g. MAPK and NF-kB, and inhibit pro-oxidative enzyme and cytokine concentration. However, their anti-oxidative and anti-inflammatory effectiveness still needs further investigation. A highly specific antioxidative activity may be important for the clinical treatment and relapse of IBD. In the future, a combination of currently used pharmaceutics, together with natural and synthetic anti-oxidative compounds, like lipoic acid or curcumine, could be taken into account in the design of novel anti-IBD therapies.

Calcitriol inhibits keratinocyte proliferation by upregulating leukocyte elastase inhibitor (serpin B1)

Calcitriol had been proved to be effective for treatment of psoriasis vulgaris. However, the molecular events leading to the normalization of keratinocyte differentiation had not been fully explored. The aim of the study was to evaluate the role of calcitriol and serpin B1 in human keratinocyte cell line (HaCaT) proliferation. Proteins extracted from calcitriol-treated and untreated HaCaT were separated by 2-D differential gel electrophoresis (2DE). Then, the 2DE profiles were analyzed to screen for differentially expressed proteins, which were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry. The upregulation of serpin B1 was confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analysis. The effect of serpin B1 on HaCaT proliferation was analyzed by RNA interference experiments, methylthiazoletetrazolium assay and flow cytometry. Reproducible 2-DE profiles of HaCaT were established. The result that serpin B1 was upregulated in the calcitriol-treated group was confirmed by qRT-PCR and western blot analysis. Calcitriol could inhibit proliferation of HaCaT at the concentration of 10(-9) -10(-6 ) mol/L. HaCaT proliferation was promoted when serpin B1 was interfered. The inhibition effect of calcitriol was stopped after serpin B1 was interfered. Serpin B1 was overexpressed in calcitriol-treated HaCaT cells and may play an important role in inhibiting HaCaT proliferation by calcitriol.

Oncostatin M mediates STAT3-dependent intestinal epithelial restitution via increased cell proliferation, decreased apoptosis and upregulation of SERPIN family members

Objective

Oncostatin M (OSM) is produced by activated T cells, monocytes, and dendritic cells and signals through two distinct receptor complexes consisting of gp130 and LIFR (I) or OSMR-β and gp130 (II), respectively. Aim of this study was to analyze the role of OSM in intestinal epithelial cells (IEC) and intestinal inflammation.

Methods

OSM expression and OSM receptor distribution was analyzed by PCR and immunohistochemistry experiments, signal transduction by immunoblotting. Gene expression studies were performed by microarray analysis and RT-PCR. Apoptosis was measured by caspases-3/7 activity. IEC migration and proliferation was studied in wounding and water soluble tetrazolium assays.

Results

The IEC lines Caco-2, DLD-1, SW480, HCT116 and HT-29 express mRNA for the OSM receptor subunits gp130 and OSMR-β, while only HCT116, HT-29 and DLD-1 cells express LIFR mRNA. OSM binding to its receptor complex activates STAT1, STAT3, ERK-1/2, SAPK/JNK-1/2, and Akt. Microarray analysis revealed 79 genes that were significantly up-regulated (adj.-p≤0.05) by OSM in IEC. Most up-regulated genes belong to the functional categories “immunity and defense” (p = 2.1×10⁻⁷), “apoptosis” (p = 3.7×10⁻⁴) and “JAK/STAT cascade” (p = 3.4×10⁻⁶). Members of the SERPIN gene family were among the most strongly up-regulated genes. OSM significantly increased STAT3- and MEK1-dependent IEC cell proliferation (p<0.05) and wound healing (p = 3.9×10⁻⁵). OSM protein expression was increased in colonic biopsies of patients with active inflammatory bowel disease (IBD).

Conclusions

OSM promotes STAT3-dependent intestinal epithelial cell proliferation and wound healing in vitro. Considering the increased OSM expression in colonic biopsy specimens of patients with active IBD, OSM upregulation may modulate a barrier-protective host response in intestinal inflammation. Further in vivo studies are warranted to elucidate the exact role of OSM in intestinal inflammation and the potential of OSM as a drug target in IBD.

Proteases and small intestinal barrier function in health and disease

PURPOSE OF REVIEW

To summarize the recent knowledge regarding intestinal proteases and the gut barrier.

RECENT FINDINGS

It is now well established that intestinal proteases, such as matrix metalloproteinase (MMP)-1, MMP-3, MMP-10 and MMP-12, are key players in the development of ulcers in inflammatory bowel disease, have direct effects on epithelial barrier function and are involved in epithelial restitution. However, more recent work has suggested that the membrane-anchored epithelial cell serine protease matriptase is critical in maintaining the gut barrier, and roles have also been described for elastase, MMP-13, gelatinases, mast cell proteases and proteases derived from parasites and gut bacteria. Interestingly, epithelial proteases often co-localize with epithelial adherens junctions, and nonepithelial-derived proteases have junctional proteins as targets.

SUMMARY

The role of proteases in controlling normal barrier function in the gut is now becoming very clear, to go alongside their role in intestinal inflammation.

Evaluation of ubiquitinated proteins by proteomics reveals the role of the ubiquitin proteasome system in the regulation of Grp75 and Grp78 chaperone proteins during intestinal inflammation

The ubiquitin proteasome system (UPS) is the major pathway of intracellular protein degradation and may be involved in the pathophysiology of inflammatory bowel diseases or irritable bowel syndrome. UPS specifically degrades proteins tagged with an ubiquitin chain. We aimed to identify polyubiquitinated proteins during inflammatory response in intestinal epithelial HCT-8 cells by a proteomic approach. HCT-8 cells were incubated with interleukin 1β, tumor necrosis factor-α, and interferon-γ for 2 h. Total cellular protein extracts were separated by 2D gel electrophoresis and analyzed by an immunodetection using antiubiquitin antibody. Differential ubiquitinated proteins were then identified by LC-ESI MS/MS. Seven proteins were differentially ubiquitinated between control and inflammatory conditions. Three of them were chaperones: Grp75 and Hsc70 were more ubiquitinated (p < 0.05) and Grp78 was less ubiquitinated (p < 0.05) under inflammatory conditions. The results for Grp75 and Grp78 were then confirmed in HCT-8 cells and in 2-4-6-trinitrobenzen sulfonic acid induced colitis in rats mimicking inflammatory bowel disease by immunoprecipitation. No difference was observed in irritable bowel syndrome like model. In conclusion, we showed that a proteomic approach is suitable to identify ubiquitinated proteins and that UPS-regulated expression of Grp75 and Grp78 may be involved in inflammatory response. Further studies should lead to the identification of ubiquitin ligases responsible for Grp75 and Grp78 ubiquitination.