Detection of calprotectin in inflammatory bowel disease: Fecal and serum levels and immunohistochemical localization

The role of fecal biomarkers in individuals with inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and Ulcerative Colitis (UC), is a relapsing and remitting condition. Noninvasive biomarkers have an increasingly important role in the diagnosis of IBD and in the prediction of future disease course in individuals with IBD. Strategies for the management of IBD increasingly rely upon close monitoring of gastrointestinal inflammation.

AREAS COVERED

This review provides an update on the current understanding of established and novel stool-based biomarkers in the diagnosis and management of IBD. It also highlights key gaps, identifies limitations, and advantages of current markers, and examines aspects that require further study and analysis.

EXPERT OPINION

Current noninvasive inflammatory markers play an important role in the diagnosis and management of IBD; however, limitations exist. Future work is required to further characterize and validate current and novel markers of inflammation. In addition, it is essential to better understand the roles and characteristics of noninvasive markers to enable the appropriate selection to accurately determine the condition of the intestinal mucosa.

Treatment success in cats with chronic enteropathy is associated with a decrease in fecal calprotectin concentrations

Feline chronic enteropathies (FCE) are challenging to diagnose and monitor for progression and response to treatment. Fecal calprotectin might be a useful non-invasive marker to evaluate clinical endpoints of therapeutic monitoring in FCE. We evaluated fecal calprotectin concentrations in cats with FCE before and after initiation of treatment comprised of immunomodulation and/or dietary intervention. Included were 17 cats with FCE and 18 healthy controls. Clinical investigation of FCE cases included clinical severity grading (feline chronic enteropathy activity index, FCEAI) in all cats, abdominal ultrasonography in 15 cats, and gastrointestinal biopsies in 6 cats. Fecal calprotectin was measured in samples from 12 cats with FCE before treatment, all 17 FCE cats ≥6 weeks after treatment initiation, and all healthy controls. Fecal calprotectin concentrations in FCE cases before treatment (median: 61 μg/g) were significantly higher than after treatment initiation (median: 15 μg/g; p = 0.0098) and compared to controls (median: 6 μg/g; p = 0.0235) and correlated with the FCEAI scores (ρ = 0.54, p = 0.0316). Fecal calprotectin concentrations after treatment initiation were higher with more severe duodenal/proximal jejunal pathology (ρ = 0.83, p = 0.0427) and shorter intervals between sampling time points (ρ = -0.54, p = 0.0250). Relevant decreases in initially increased fecal calprotectin concentrations are seen in cats with FCE on varying treatment strategies that significantly improve or have remission of clinical signs. This supports the utility of fecal calprotectin as a surrogate biomarker to assess disease severity in FCE cases. Further studies need to evaluate fecal calprotectin concentrations longitudinally in relation to mucosal healing vs. clinical response.

Intestinal S100/Calgranulin Expression in Cats with Chronic Inflammatory Enteropathy and Intestinal Lymphoma

Simple Summary

Intestinal diseases in cats are complicated diseases in which intestinal inflammation is difficult to distinguish from lymphoma, which is a neoplasm. In this study, the expression of the proteins S100A8/A9 and S100A12 (also called calgranulins) in the intestine is investigated in both diseases and for potential correlations with microscopically visible changes in the intestine or the clinical severity of the disease. Only small differences were seen between healthy and diseased animals, and there were no differences between cats with intestinal inflammation and lymphoma. However, several correlations of cells staining positive for calgranulins and inflammatory changes at the microscopic level and clinical disease severity were shown. This indicates that calgranulins play a role in both gastrointestinal lymphoma and inflammation and would support the recent theory that these two diseases might not be separate disease entities but instead are related. Further insights into the role of the calgranulins in these feline diseases will lead to a better understanding of the disease pathogenesis and, thus, potentially novel diagnostics and treatment avenues.

Abstract

Diagnosing chronic inflammatory enteropathies (CIE) in cats and differentiation from intestinal lymphoma (IL) using currently available diagnostics is challenging. Intestinally expressed S100/calgranulins, measured in fecal samples, appear to be useful non-invasive biomarkers for canine CIE but have not been evaluated in cats. We hypothesized S100/calgranulins to play a role in the pathogenesis of feline chronic enteropathies (FCE) and to correlate with clinical and/or histologic disease severity. This retrospective case-control study included patient data and gastrointestinal (GI) tissues from 16 cats with CIE, 8 cats with IL, and 16 controls with no clinical signs of GI disease. GI tissue biopsies were immunohistochemically stained using polyclonal α-S100A8/A9 and α-S100A12 antibodies. S100A8/A9⁺ and S100A12⁺ cells were detected in all GI segments, with few significant differences between CIE, IL, and controls and no difference between diseased groups. Segmental inflammatory lesions were moderately to strongly correlated with increased S100/calgranulin-positive cell counts. Clinical disease severity correlated with S100A12⁺ cell counts in cats with IL (ρ = 0.69, p = 0.042) and more severe diarrhea with colonic lamina propria S100A12⁺ cells with CIE (ρ = 0.78, p = 0.021) and duodenal S100A8/A9⁺ cells with IL (ρ = 0.71, p = 0.032). These findings suggest a role of the S100/calgranulins in the pathogenesis of the spectrum of FCE, including CIE and IL.

Inflammation and tissue remodeling contribute to fibrogenesis in stricturing Crohn’s disease: image processing and analysis study

Background

Inflammation and structural remodeling may contribute to fibrogenesis in Crohn’s disease (CD). We quantified the immunoexpression of calretinin, CD34, and calprotectin as a surrogate for mucosal innervation, telocytes (interstitial cells playing a role in networking), and inflammation, respectively, and correlated them with bowel alterations in stricturing CD.

Methods

Primary resection specimens for ileal CD (n = 44, 31 stricturing CD, 13 inflammatory CD) were identified. Left-sided ulcerative colitis and trauma cases were used as controls. Proximal and distal margin and middle (diseased) sections were stained for calretinin, CD34, and calprotectin. Microscopic images were captured from the mucosa (calretinin), submucosa (calprotectin), and myenteric plexus (CD34), and the immunostaining was quantified using image processing and analysis. Bowel thickness at the corresponding sections were measured and correlated with the amount of immunoexpression.

Results

A total of 2,037 images were analyzed. In stricturing CD, submucosal alteration/thickening at the stricture site correlated with calprotectin staining and inversely correlated with calretinin staining at the proximal margin. Muscularis propria alteration/thickening at the stricture site correlated with mucosal calretinin staining at the proximal margin. Submucosal alteration/thickening at the proximal margin correlated with calretinin and CD34 staining at the proximal margin and inversely correlated with CD34 staining at the stricture site. Calretinin immunostaining at the distal margin was significantly higher in stricturing CD than the controls.

Conclusions

Inflammation and tissue remodeling appear to contribute to fibrogenesis in stricturing CD. Increased mucosal calretinin immunostaining distal to the diseased segment could be helpful in diagnosing CD in the right clinical context.

Kitchen Diet vs. Industrial Diets-Impact on Intestinal Barrier Parameters among Stroke Patients

Background and aims: Strokes are the second highest cause of death in the world and the most common cause of permanent disability in adults. Intestinal barrier permeability thus contributes to diminished homeostasis within the body, which further affects the healing process and convalescence. Each stroke patient should be administered with ingredients that support the intestinal barrier (e.g., protein and fiber). The aim of this study was to compare the effect of various types of diet (enteral with or without fiber vs. a mixed kitchen diet) on the metabolic activity of intestinal microbiota, namely short chain fatty acids, and gut barrier integrity parameters (zonulin and calprotectin. Methods: Patients (n = 59), after suffering an ischemic stroke, were randomly allocated to three groups receiving: the kitchen diet (n = 32; 1.2 g fiber in 100 mL); Nutrison Energy^® (n = 14; 0.02 g fiber in 100 mL); and Nutrison Diason Energy HP^® (n = 13; 1.8 g fiber in 100 mL). The patients underwent anthropometric measurements and blood samples (for prealbumin measurements), and stool samples (for zonulin and calprotectin determinations) were taken twice, on admission and a week later. Results: Industrial diets enriched with fiber maintained nutritional status and had a beneficial effect on intestinal barrier permeability parameters. Patients fed with kitchen diets demonstrated a decreased number of lymphocytes, hemoglobin, erythrocytes, and increased serum concentration of C-reactive protein, but improved gut barrier markers. Proton pump inhibitors were shown to increase the inflammatory process in gut. Conclusions: Stroke patients should be administered with industrial diets enriched with fiber to improve gut barrier integrity and nutritional parameters.

IL-1 Mediates Tissue-Specific Inflammation and Severe Respiratory Failure in COVID-19

Acute respiratory distress syndrome (ARDS) in COVID-19 has been associated with catastrophic inflammation. We present measurements in humans and a new animal model implicating a role in danger-associated molecular patterns. Calprotectin (S100A8/A9) and high-mobility group box 1 (HMGB1) were measured in patients without/with ARDS, and admission calprotectin was associated with soluble urokinase plasminogen activator receptor (suPAR). An animal model was developed by intravenous injection of plasma from healthy or patients with COVID-19 ARDS into C57/BL6 mice once daily for 3 consecutive days. Mice were treated with one anti-S100A8/A9 antibody, the IL-1 receptor antagonist anakinra or vehicle, and Flo1-2a anti-murine anti-IL-1α monoclonal antibody or the specific antihuman IL-1α antibody XB2001 or isotype controls. Cytokines and myeloperoxidase (MPO) were measured in tissues. Calprotectin, but not HMGB1, was elevated in ARDS. Higher suPAR indicated higher calprotectin. Animal challenge with COVID-19 plasma led to inflammatory reactions in murine lung and intestines as evidenced by increased levels of TNFα, IL-6, IFNγ, and MPO. Lung inflammation was attenuated with anti-S100A8/A9 pre-treatment. Anakinra treatment restored these levels. Similar decrease was found in mice treated with Flo1-2a but not with XB2001. Circulating alarmins, specifically calprotectin, of critically ill COVID-19 patients induces tissue-specific inflammatory responses through an IL-1-mediated mechanism. This could be attenuated through inhibition of IL-1 receptor or of IL-1α.

Intramucosal Calprotectin Expression in Inflammatory Bowel Disease (IBD) and Non-IBD Colorectal Inflammation

BACKGROUND: Inflammatory bowel disease (IBD) diagnosis remains a challenge accompanied with high numbers of misdiagnosis causing suboptimal management. Tons of trials have been conducted to improve the diagnostic accuracy, one of which is the use of biomarker such as calprotectin. Calprotectin can be detected in tissue (intramucosal) and is becoming a potential marker of IBD. AIM: This study aims to determine intramucosal calprotectin expression in IBD, non-IBD colitis, and control. METHODS: This analytic retrospective study included consecutively sampled IBD and non-IBD colitis colorectal biopsy specimens, and control group obtained from Cipto Mangunkusumo Hospital registered from 2017 to 2019. Cases were included in the study if specimens were indicative of IBD and non-IBD clinically and histopathologically and no abnormality were found histopathologically in the control group. Specimens with non-adequate data from the hospital medical records or with missing tissue slides were excluded from the study. Calprotectin immunostaining was conducted to evaluate mean intramucosal calprotectin expression (cell/HPF) in each group. RESULTS: Most of the samples from IBD and non-IBD group (45 samples each) showed mild active inflammation. Mucosal calprotectin expression in aforementioned groups was higher than that of control group (p < 0.001). Subjects with active inflammation showed higher calprotectin expression compared to those with inactive inflammation (p < 0.001). Calprotectin expression was also related to activity grade. CONCLUSION: Higher calprotectin expression showed significant association with the presence of inflammation and disease activity. However, the application of intramucosal calprotectin immunohistochemistry test to determine inflammatory etiology (IBD vs. non-IBD) still needs to be further evaluated.

Evaluation of Serum Calprotectin Levels in Patients with Inflammatory Bowel Disease

BACKGROUND

Fecal calprotectin has been proposed as a useful biomarker of disease activity in inflammatory bowel disease (IBD). However, the role of calprotectin in systemic circulation is not well established. Thus, this study aimed to quantify serum calprotectin levels to identify a potential inflammatory marker for IBD.

METHODS

Ninety-eight patients with ulcerative colitis (UC) and 105 patients with Crohn's disease (CD) were prospectively enrolled and clinically scored. Ninety-two healthy, age-matched subjects served as controls. Blood samples from UC and CD patients and controls were analyzed for serum calprotectin levels and routine laboratory parameters. Disease activity was assessed by partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum calprotectin levels were higher in CD and UC patients than in controls and were higher during active disease than during inactive disease in CD but not in UC. In UC, serum calprotectin levels were correlated with C-reactive protein (CRP) but not with other laboratory parameters or disease activity. In CD, serum calprotectin levels were positively correlated with disease activity, serum CRP, and platelet count. In UC and CD, serum calprotectin and CRP levels increased during the acute phase and decreased towards remission.

CONCLUSIONS

Serum calprotectin is an inflammatory marker in IBD but might be more effective in evaluating patients with CD than those with UC. Further studies are needed to confirm these findings and to better determine the specific uses of serum calprotectin in routine practice.

Neutrophil Extracellular Traps in Digestive Cancers: Warrior or Accomplice

Characterized as a complex of extracellular DNA fibers and granule proteins, neutrophil extracellular traps (NETs) are generated specifically by neutrophils which play a critical role in host defense and immune regulation. NETs have been initially found crucial for neutrophil anti-microbial function. Recent studies suggest that NETs are involved in tumorigenesis and cancer progression. However, the function of NETs in cancer remains unclear, which might be due to the variation of research models and the heterogeneity of cancers. Although most of malignant tumors have similar biological behaviors, significant differences indeed exist in various systems. Malignant tumors of the digestive system cause the most incidence and mortality of cancer worldwide. In this review, we would focus on research developments on NETs in digestive cancers to provide insights on their role in digestive cancer progression and future research directions.

Predictive value of tissue calprotectin for disease recurrence after ileocecal resection in pediatric Crohn's disease

AIM

Detection of possible predictive factors of endoscopic recurrence after ileocecal resection in Crohn's disease could be very beneficial for the individual adjustment of postoperative therapy. The aim of this study was to verify, whether immunohistochemical detection of calprotectin in resection margins is useful in diagnostics of endoscopic recurrence.

METHODS

In this study we included pediatric patients with Crohn's disease who underwent ileocecal resection, regardless of pre-operative or post-operative therapy (n=48). We collected laboratory, clinical, surgical, endoscopic and histopathological data at the time of surgery and at 6 months after surgery. The immunohistochemical staining of calprotectin antigen was performed on all paraffin blocks from the resection margins.

RESULTS

Out of 48 patients 52% had endoscopic recurrence in the anastomosis (defined by Rutgeerts score) within 6 months after surgery. The number of cells positive for calprotectin in the proximal resection margin was negatively associated with recurrence (P=0.008), as was the elevated level of total calprotectin (from both resection margins). There was no correlation of calprotectin in distal resection margin and endoscopic recurrence. Fecal calprotectin over 100 ug/g (P=0.0005) and high CRP (P<0.001) at 6 months after ileocecal resection and peritonitis (P=0.048) were associated with endoscopic recurrence.

CONCLUSION

Approximately half of the patients developed endoscopic recurrence within 6 months after ileocecal resection. The predictive value of tissue calprotectin is questionable, as it is negatively associated with endoscopic recurrence. There are other potentially useful predictors, such as CRP and fecal calprotectin at 6 months after resection and the presence of peritonitis.

The Role of Biomarkers in Surgery for Ulcerative Colitis: A Review

Ulcerative colitis (UC) is an inflammatory condition that generally affects the rectum and extends proximally into the colon in a continuous, distal-to-proximal pattern. Surgical resection (total proctocolectomy) is the only cure for UC and is often necessary in managing complicated or refractory disease. However, recent advances in biologically targeted therapies have resulted in improved disease control, and surgery is required in only a fraction of cases. This ever-increasing array of options for medical management has added complexity to surgical decision-making. In some circumstances, the added time required to ensure failure of medical therapy can delay colectomy in patients who will ultimately need it. Indeed, many patients with severe disease undergo trials of multiple medical therapies prior to considering surgery. In severe cases of UC, continued medical management has been associated with a delay to surgical intervention and higher rates of morbidity and mortality. Biomarkers represent a burgeoning field of research, particularly in inflammatory bowel disease and cancer. This review seeks to highlight the different possible settings for surgery in UC and the role various biomarkers might play in each.

Distinct Human Gut Microbial Taxonomic Signatures Uncovered With Different Sample Processing and Microbial Cell Disruption Methods for Metaproteomic Analysis

The use of metaproteomics for studying the human gut microbiota can shed light on the taxonomic profile and the functional role of the microbial community. Nevertheless, methods for extracting proteins from stool samples continue to evolve, in the pursuit of optimal protocols for moistening and dispersing the stool sample and for disrupting microbial cells, which are two critical steps for ensuring good protein recovery. Here, we evaluated different stool sample processing (SSP) and microbial cell disruption methods (CDMs). The combination of a longer disintegration period of the stool sample in a tube rotator with sonication increased the overall number of identified peptides and proteins. Proteobacteria, Bacteroidetes, Planctomycetes, and Euryarchaeota identification was favored by mechanical cell disruption with glass beads. In contrast, the relative abundance of Firmicutes, Actinobacteria, and Fusobacteria was improved when sonication was performed before bead beating. Tenericutes and Apicomplexa identification was enhanced by moistening the stool samples during processing and by disrupting cells with medium-sized glass beads combined with or without sonication. Human protein identifications were affected by sonication. To test the reproducibility of these gut metaproteomic analyses, we examined samples from six healthy individuals using a protocol that had shown a good taxonomic diversity and identification of proteins from Proteobacteria and humans. We also detected proteins involved in microbial functions relevant to the host and related mostly to specific taxa, such as B12 biosynthesis and short chain fatty acid (SCFA) production carried out mainly by members in the Prevotella genus and the Firmicutes phylum, respectively. The taxonomic and functional profiles obtained with the different protocols described in this work provides the researcher with valuable information when choosing the most adequate protocol for the study of certain pathologies under suspicion of being related to a specific taxon from the gut microbiota.

Effect of disease duration on the association between serum albumin and mucosal healing in patients with ulcerative colitis

Objective

Serum albumin is used as a marker of acute inflammation. Several studies have addressed the association between serum albumin and clinical outcome in patients with ulcerative colitis (UC). While mucosal healing (MH) has been indicated as the therapeutic goal for UC, the association between serum albumin and MH remains unclear. We evaluated this issue in patients with UC overall and explored whether duration of UC affected this association.

Design

This cross-sectional study recruited consecutive patients with UC. Study subjects consisted of 273 Japanese patients with UC. Serum albumin was divided into tertiles based on its distribution in all study subjects. One endoscopy specialist was responsible for measuring partial MH and MH, which were defined as a Mayo endoscopic subscore of 0–1 and 0, respectively. The association between serum albumin and clinical outcomes was assessed by multivariate logistic regression.

Results

Rates of clinical remission, partial MH and MH were 57.9%, 63% and 26%, respectively. Only high serum albumin (>4.4 mg/dL) was significantly positively associated with MH (OR 2.29 (95% CI: 1.03 to 5.29), p for trend=0.043). In patients with short UC duration (<7 years) only, high serum albumin was significantly positively associated with MH and clinical remission. In patients with long UC duration (≥7 years), in contrast, no association between serum albumin and clinical outcomes was found.

Conclusion

In Japanese patients with UC, serum albumin was significantly positively associated with MH. In patients with short UC duration, serum albumin might be a useful complementary marker for MH.

Molecular and Histological Profiling Reveals an Innate-Shaped Immune Microenvironment in Solitary Juvenile Polyps

INTRODUCTION

Solitary juvenile polyps (JP) are characterized by a benign disease course with low recurrence rate but present with signs of intestinal inflammation. To better understand the underlying pathogenesis, we performed histological and molecular evaluation targeting distinct immune mechanisms.

METHODS

Pediatric patients with JP (n = 12), with treatment-naïve inflammatory bowel disease (IBD; [n = 41]) as inflammatory control, and non-IBD controls (n = 14) were investigated. For a comparative analysis of infiltrating immune cells, a next-generation tissue microarray of biopsies was assembled, immunostained, and scored. Targeted transcriptional profiling was performed using a customized immunology panel.

RESULTS

In JP, a predominant accumulation of neutrophils and eosinophils was observed. RNA expression profiles revealed increased levels of CXCL8, CXCL5, and CCL11 transcripts in JP, indicating an enhanced recruitment of neutrophils and eosinophils. Moreover, messenger RNA levels of the proinflammatory cytokine IL1b and the inflammation-amplifying receptor TREM1 were higher in JP, whereas we could not find signs of a functionally polarized Tcell response in JP when compared with IBD.

DISCUSSION

Patients with JP and patients with treatment-naïve IBD have distinct cell infiltrates during active disease. The ample presence of eosinophils in JP supports neutrophil accumulation, which is responsible for the elevated release of calprotectin. Intriguingly, however, we were not able to identify a functionally polarized T-cell response in JP, which indicates that during the acute onset of inflammation in JP, a potent adaptive immune memory is not established. This may explain the low reoccurrence rate of JP.

International consensus on methodological issues in standardization of fecal calprotectin measurement in inflammatory bowel diseases

BACKGROUND

Fecal calprotectin (FC) is a non-invasive marker of gut inflammation which is frequently used to guide therapeutic decisions in patients with inflammatory bowel diseases (IBD). Each step of FC measurement can influence the results, leading to misinterpretations and potentially impacting the management of IBD patients. To date, there is high heterogeneity between FC measurements and no current method is universally accepted as a standard.

AIMS

Our aim was to provide clear position statementsabout the pre-analytical and the analytical phases of FC measurement to homogenize FC levels and to minimize variability and risk of misinterpretation through aninternational consensus.

MATERIALS & METHODS

Fourteen physicians with expertise in the field of IBD and FC from 11 countries attended a virtual international consensus meeting on July 17th, 2020. A systematic literature was conducted and the literature evidence was shared and discussedamong the participants. Statements were formulated, discussed, and voted. Statements were considered approved if all participants agreed.

RESULTS

Nine statements were formulated and approved. Based on the available evidence, quantitative tests should be preferred for measuring FC. Furthermore, FC measurement, if possible, should always be performed with the same method and factors influencing FC levels should be taken into account when interpreting the results.

DISCUSSION

FC has an increasingly important role in the management of patients with IBD. However, large multicenter studies should be conducted to define the reproducibility and to confirm the diagnostic accuracy of the available FC tests.

CONCLUSION

FC concentrations guide clinicians' treatment decisions. Our statements have a relevant impact in daily practice and could be applied in clinical trials to standardize FC measurement.

Assessment of Inflammatory Markers in Children with Cow's Milk Allergy Treated with a Milk-Free Diet

Background: The aim of the study was to establish whether the use of a strict milk-free diet in children with cow’s milk allergy, resulting in the resolution of clinical symptoms of the disease, also extinguishes the inflammatory reaction induced by the allergy. Methods: We examined 64 children (aged 3–6 years) with a diagnosed cow’s milk allergy who had been treated with an elimination diet for at least six months and showed remission of the disease’s clinical symptoms as a result of the treatment. The control group consisted of 30 healthy children of the same age following an unrestricted age-appropriate diet. Concentrations of cytokines, calprotectin, and adipokines (leptin, resistin, chemerin, neutrophilic lipocalin associated with gelatinase—NGAL) were determined in the serum samples obtained from the studied children by immunoenzymatic assays. Results: Patients with CMA had significantly higher median values of serum IL-6, TNF-α, resistin, chemerin and NGAL in comparison to the healthy children (p < 0.05, p < 0.001, p < 0.05, p < 0.01, p < 0.001, respectively). Serum concentrations of IL-10, leptin, calprotectin and CRP as well as in WBC count were in the same range in both studied groups. We observed direct statistically significant correlations between levels of IL-10 and CRP (p = 0.005), IL-10 and WBC (p = 0.045), TNF-α and WBC (p = 0.038), calprotectin and WBC (p < 0.001), chemerin and CRP (p < 0.001) as well as between NGAL and WBC (p = 0.002) in children with CMA. Conclusion: The use of a strict milk-free diet by children with CMA, resulting in the resolution of clinical symptoms of the disease, does not seem to extinguish the inflammation induced by the allergy. The findings of this study—elevated IL-6, TNF-α, resistin, chemerin and NGAL levels in patients with CMA—suggest that these parameters seem to be involved in the generation of a low-grade proinflammatory environment observed in cow‘s milk allergy and could be used to monitor the effectiveness of treatment.

Neutrophil Extracellular Traps in Inflammatory Bowel Disease: Pathogenic Mechanisms and Clinical Translation

The Inflammatory Bowel Diseases (IBD), Ulcerative Colitis (UC) and Crohn's Disease (CD) are characterised by chronic non-resolving gut mucosal inflammation involving innate and adaptive immune responses. Neutrophils, usually regarded as first responders in inflammation, are a key presence in the gut mucosal inflammatory milieu in IBD. Here, we review the role of neutrophil extracellular trap (NET) formation as a potential effector disease mechanism. NETs are extracellular webs of chromatin, microbicidal proteins and oxidative enzymes that are released by neutrophils to contain pathogens. NETs contribute to the pathogenesis of several immune-mediated diseases such as systemic lupus erythematosus and rheumatoid arthritis; and recently, as a major tissue damaging process involved in the host response to severe acute respiratory syndrome coronavirus 2 infection. NETs are pertinent as a defence mechanism at the gut mucosal interphase exposed to high levels of bacteria, viruses and fungi. On the other hand, NETs can also potentiate and perpetuate gut inflammation. In this review, we discuss the broad protective vs. pathogenic roles of NETs, explanatory factors that could lead to an increase in NET formation in IBD and how NETs may contribute to gut inflammation and IBD-related complications. Finally, we summarise therapeutic opportunities to target NETs in IBD.

Power calculations for detecting differences in efficacy of fecal microbiota donors

Fecal microbiota transplantation (FMT) is a recommended therapy for recurrent Clostridioides difficile infection and is being investigated as a potential therapy for dozens of other indications, notably inflammatory bowel disease. The immense variability in human stool, combined with anecdotal reports from FMT studies, have suggested the existence of “donor effects”, in which stool from some FMT donors is more efficacious than stool from other donors. In this study, simulated clinical trials were used to estimate the number of patients that would be required to detect donor effects under a variety of study designs. In most cases, reliable detection of donor effects required more than 100 patients treated with FMT. These results suggest that previous reports of donor effects need to be verified with results from large clinical trials and that patient biomarkers may be the most promising route to robustly identifying donor effects.

Calprotectin in inflammatory bowel disease

The term IBD is usually used for referring to a group of inflammatory gastro-intestinal diseases (mainly Crohn's disease and ulcerative colitis). Accordingly, IBD arises as a result of inappropriate immune response to intestinal commensal organisms among genetically susceptible individuals. Performing colonoscopy and histopathologic evaluation on an inflamed bowel biopsy specimen are currently considered as gold standards for diagnosis and management of IBD. Correspondingly, these techniques are known to be invasive and costly. In recent decades, fecal calprotectin, as a biomarker, has received much attention for the diagnosis and non-invasive management of IBD. Up to now, many studies have investigated the efficacy of fecal calprotectin in the areas of IBD differentiation from IBS, prediction of endoscopic and histologic activities of IBD and prediction of disease recurrence. Although some of these studies have reported promising results, some others have shown significant limitations. Therefore, in this paper, we reviewed the most interesting ones of these studies after a brief discussion of the laboratory measurement of fecal calprotectin. Moreover, we attempted to provide an answer for the question of whether fecal-calprotectin could be considered as a potential surrogate marker for colonoscopy.

Feasibility of a Novel Mobile C-Reactive Protein-Testing Device Using Gold-Linked Electrochemical Immunoassay: Clinical Performance Study

Background

Home-based care is one of the most promising solutions to provide sufficient medical care for several older patients in Japan. However, because of insufficient diagnostic devices, it is sometimes difficult to detect early signs of the occurrence or worsening of diseases, such as infections under home-based care settings. C-reactive protein (CRP) is highly sensitive to diagnosing infections, and its elevation can help diagnose acute infection in older patients. Therefore, a CRP-measuring device that can be used in such a specific occasion is needed for home-based care. However, aspects such as its size, weight, and procedure are still challenging with respect to the practical use of mobile devices that quantitatively measure CRP levels easily and quickly under home-based care settings.

Objective

We developed a new mobile, rapid CRP measurement device using a gold-linked electrochemical immunoassay (GLEIA) system. The aim of this study was to evaluate the feasibility of this mobile CRP-testing device.

Methods

First, we assessed the performance of bare GLEIA-based electrode chips as the foundation of the device. After embedding the bare GLEIA-based electrode chips in a special plastic case and developing the mobile CRP-testing device, we further tested the device prototype using clinical blood samples. Finally, we evaluated the intra-assay variability for precision in the same condition and inter-assay variability for reproducibility in different conditions.

Results

Blood samples for analysis were obtained by direct vein puncture from outpatients (N=85; females: 57/85; males: 28/85; age: 19-88 years) at Kanazawa University Hospital in Japan. For performance evaluation of bare GLEIA-based electrode chips, we used 85 clinical blood samples. There was a significant positive correlation between the electrode-predicted CRP levels and the reference CRP concentrations (R²=0.947; P<.001). The assembled device was mobile (size 45×90×2.4 mm; weight 10 g) and disposable. The minimum volume of the sample needed for measuring CRP was 1.4 µL. The estimated preanalytical time was approximately 7 minutes and 40 seconds, and analysis time was approximately 1 minute and 10 seconds. Subsequently, for performance evaluation of the mobile CRP-testing device using GLEIA-based electrode chips, we used 26 clinical blood samples and found a significant positive correlation between the mobile device-predicted CRP levels and the reference CRP concentrations (R²=0.866, P<.001). The intra-assay variabilities were 34.2%, 40.8%, and 24.5% for low, medium, and high CRP concentrations, respectively. The inter-assay variabilities were 46.5%, 38.3%, and 64.1% for low, medium, and high CRP concentrations, respectively.

Conclusions

Our findings suggest that this new mobile CRP-testing device might be suitable for use in home-based care settings.

Intestinal Barrier Integrity in Heat-Stressed Modern Broilers and Their Ancestor Wild Jungle Fowl

High environmental temperature has strong adverse effects on poultry production, welfare, and sustainability and, thereby, constitutes one of the most challenging stressors. Although colossal information has been published on the effects of heat stress on poultry productivity and gut health, the fundamemntal mechanisms associated with heat stress responses and intestinal barrier function are still not well defined. The aim of the present study was, therefore, to determine the effects of acute (2 h) heat stress on growth performance, gut integrity, and intestinal expression of heat shock and tight junction proteins in slow- (broilers of the 1950's, ACRB), moderate- (broilers of 1990's, 95RAN), rapid-(modern broilers, MRB) growing birds, and their ancestor wild jungle fowl (JF). Heat stress exposure significantly increased the core body temperature of 95RAN and MRB chickens by ~0.5–1°C, but not that of JF and ACRB compared to their counterparts maintained at thermoneutral conditions. Heat stress also depressed feed intake and increased serum fluorescein isothiocyanate-dextran (FITC-D) levels (P < 0.05) in modern broilers (95RAN and MRB) but not in JF and ACRB, indicating potential leaky gut syndrome. Molecular analyses showed that heat stress exposure significantly up regulated the duodenal expression of occludin (OCLN) and lipocalin (LCN2) in ACRB, zonula occludens (ZO-2), villin1 (VIL1), and calprotectin (CALPR) in 95 RAN, and only CALPR in MRB compared to their TN counterparts. In the jejunum however, heat stress down regulated the expression of PALS1-associated tight junction protein (PATJ) in ACRB, 95RAN, and MRB, and that of cadherin1 (CDH1) in MRB. In the ileum, heat stress significantly down regulated the expression of OCLN in 95 RAN, ZO-1 in MRB, gap junction protein alpha1 (GJA1) in JF, and VIL1 in ACRB compared to their TN counterparts. In summary, this is the first report, to our knowledge, showing that tight junction protein expression is environmental-, genotype-, and intestinal segment-dependent and identifying molecular signatures, such as CDH1, CALPR, and ZO-1, potentially involved in leaky gut syndrome-induced by heat stress in MRB.

Effects of unsaturated fatty acids (Arachidonic/Oleic Acids) on stability and structural properties of Calprotectin using molecular docking and molecular dynamics simulation approach

Calprotectin is a heterodimeric protein complex with two subunits called S100A8/A9. The protein has an essential role in inflammation process and various human diseases. It has the ability to bind to unsaturated fatty acids including Arachidonic acid, Oleic acid and etc., which could be considered as a major carrier for fatty acids. In this study we aimed to appraise the thermodynamics and structural changes of Calprotectin in presence of Arachidonic acid/Oleic acid) using docking and molecular dynami simulation method. To create the best conformation of Calprotectin-Oleic acid/Arachidonic acid complexes, the docking process was performed. The complexes with the best binding energy were selected as the models for molecular dynamics simulation process. Furthermore, the structural and thermodynamics properties of the complexes were evaluated too. The Root Mean Square Deviation and Root Mean Square Fluctuation results showed that the binding of Arachidonic acid/Oleic acid to Calprotectin can cause the protein structural changes which was confirmed by Define Secondary Structure of Proteins results. Accordingly, the binding free energy results verified that binding of Oleic acid to Calprotectin leads to instability of S100A8/A9 subunits in the protein. Moreover, the electrostatic energy contribution of the complexes (Calprotectin-Oleic acid/Arachidonic acid) was remarkably higher than van der Waals energy. Thus, the outcome of this study confirm that Oleic acid has a stronger interaction with Calprotectin in comparison with Arachidonic acid. Our findings indicated that binding of unsaturated fatty acids to Calprotectin leads to structural changes of the S100A8/A9 subunits which could be beneficial to play a biological role in inflammation process.

The role of serum calprotectin as a novel biomarker in inflammatory bowel diseases: a review study

As the incidence of inflammatory bowel diseases (IBD) increases in the newly industrialized countries, the health and financial burden of disease also increase. These changes make the role of IBD biomarkers further crucial. Serum calprotectin, as a novel blood-based biomarker of IBD, has been investigated in several investigations. Yet, there is no consensus regarding its clinical utility. We searched the electronic database, including PubMed, EMBASE, Scopus, and Web of Science up to the end of 2018 to find how serum calprotectin associates with the disease characteristics in IBD. The search terms included: inflammatory bowel diseases, IBD, Crohn Diseases (CD), Ulcerative Colitis (UC), calprotectin, serum, and blood. Based on our review, a biomarker role has been suggested for serum calprotectin in IBD, as significant associations were found between serum calprotectin and disease burden, prognosis, and relapse. A complementary role to fecal calprotectin has also been suggested for serum calprotectin. On the other hand, considering a significant correlation between serum calprotectin and serum CRP, but not fecal calprotectin, serum calprotectin could be more representative of systemic inflammation than an intestinal inflammation. Consequently, further researches are needed to unwrap the potential of serum calprotectin as a blood-based biomarker in IBD.

Usefulness of fecal calprotectin by monoclonal antibody testing in adult Japanese with inflammatory bowel diseases: a prospective multicenter study

Background/Aims

Noninvasive objective monitoring is advantageous for optimizing treatment strategies in patients inflammatory bowel disease (IBD). Fecal calprotectin (FCP) is superior to traditional biomarkers in terms of assessing the activity in patients with IBD. However, there are the differences among several FCP assays in the dynamics of FCP. In this prospective multicenter trial, we investigated the usefulness of FCP measurements in adult Japanese patients with IBD by reliable enzyme immunoassay using a monoclonal antibody.

Methods

We assessed the relationship between FCP levels and disease or endoscopic activity in patients with ulcerative colitis (UC, n=64) or Crohn’s disease (CD, n=46) compared with healthy controls (HCs, n=64).

Results

FCP levels in UC patients strongly correlated with the Disease Activity Index (r_s=0.676, P<0.0001) and Mayo endoscopic subscore (MES; r_s=0.677, P<0.0001). FCP levels were significantly higher even in patients with inactive UC or CD compared with HCs (P=0.0068, P<0.0001). The optimal cutoff value between MES 1 and 2 exhibited higher sensitivity (94.1%). FCP levels were significantly higher in active UC patients than in inactive patients (P<0.001), except those with proctitis. The Crohn’s Disease Activity Index tended to correlate with the FCP level (r_s=0.283, P=0.0565).

Conclusions

Our testing method using a monoclonal antibody for FCP was well-validated and differentiated IBD patients from HCs. FCP may be a useful biomarker for objective assessment of disease activity in adult Japanese IBD patients, especially those with UC.