Fecal Zonulin as a Noninvasive Biomarker of Intestinal Permeability in Pediatric Patients with Inflammatory Bowel Diseases-Correlation with Disease Activity and Fecal Calprotectin

Markers of enterocyte damage in celiac disease in children: is there an association with the clinical manifestations of the disease?

Actuality

The state of the intestinal barrier has crucial importance in the pathogenesis of celiac disease (CD). Fecal zonulin (FZ) and intestinal fatty acid binding protein (i-FABP) are important components in maintaining physiological processes in the intestine and potential biomarkers of enterocyte damage.

Aim of study

To evaluate FZ and i-FABP levels as markers of small intestine injury in children with CD, depending on the clinical forms and histomorphological changes in the small intestinal mucosa.

Materials and methods

In 2021-2023 yy, a single-center observational study was conducted among children with newly diagnosed CD.The level of FZ in stool and I-FABP in serum were determined using the Immundiagnostik ELISA kits (Germany).

Results

Study included 75 patients,control group was 37 healthy children. The intestinal form of the CD was established in 51 (68.0%) patients,the remaining 24 (32.0%) children have CD with extraintestinal manifestations. Among children with classical CD, the mean values of FZ were 157.9 ± 29.8 ng/ml (p < 0.02 with control), in second group the mean values of FZ were 136.7 ± 17.0 ng/ml, (p < 0.05 with the control), and a statistically significant difference between the groups was p < 0.02. The i-FABP values in the first group were 2476.9 ± 297.4 pg/ml (p < 0.05 with control),and in the second -2061.47 ± 291.5 pg/ml. In the group of children with intestinal manifestations of CD, a weak positive correlation relationship was found between FZ and stool frequency (r = 0.35). In the second group: weak inverse correlations were between FZ and weight, and height (r = -0.37 and r = -0.36 respectively). I-FABP values in the first group moderately correlated with stool frequency (r = 0.53). In the group with extraintestinal manifestations, a moderate negative relationship was found between the i-FABP2 level and BMI (r = -0.53) and a moderate positive relationship between the i-FABP level and antibodies to tissue transglutaminase IgA (r = 0.58) and a weak positive correlation with histological assessment according to Marsh criteria (r = 0.34).

Conclusions

Our study demonstrated a relationship between the clinical manifestations of CD and the levels of FZ and i-FABP. The increase in the values also can serve as marker of increased permeability and damage of the intestinal barrier, which will open up new possibilities for understanding the processes of restoration of the small intestinal mucosa.

Gastrointestinal Barrier Disruption in Post-COVID Syndrome Fatigue Patients

BACKGROUND

Post-COVID Syndrome (PCS) is the term for a condition with persistent symptoms in a proportion of COVID-19 patients after asymptomatic, mild, or severe disease courses. Numbers vary, but the current estimate is that after COVID-19 approximately 10% develop PCS. The aim of our study was to evaluate the impact of SARS-CoV-2 infection on the gastrointestinal (GI) tract and associations with the development of PCS with fatigue, post-exertional malaise (PEM), orthostatic dysregulation, autonomous dysregulation, and/or neurocognitive dysregulation.

METHODS

By combining medical record data from a prospective observational study with symptom analysis before, during, and after SARS-CoV-2 infection, we aimed to identify potential risk factors and predictive markers for PCS. Additionally, we analyzed blood, saliva, and stool samples from this well-characterized PCS patient cohort to biologically validate our findings.

RESULTS

We identified significant associations between pre-existing GI complaints and the development of PCS Fatigue. PCS patients showed higher LBP/sCD14 ratios, lower IL-33 levels, and higher IL-6 levels compared to control groups. Our results highlight the critical role of the GI tract in PCS development of post-viral Fatigue.

CONCLUSION

We propose that the viral infection disrupts pathways related to the innate immune response and GI barrier function, evidenced by intestinal low-grade inflammation and GI barrier leakage. Monitoring GI symptoms and markers before, during, and after SARS-CoV-2 infection is crucial for identifying predictive clinical phenotypes in PCS. Understanding the interaction between viral infections, immune responses, and gut integrity could lead to more effective diagnostic and treatment strategies, ultimately reducing the burden on PCS patients.

Fecal metaproteomics enables functional characterization of remission in patients with inflammatory bowel disease

The gut microbiome is an important contributor to the development and the course of inflammatory bowel disease (IBD). While changes in the gut microbiome composition were observed in response to IBD therapy using biologics, studies elucidating human and microbial proteins and pathways in dependence on therapy success are sparse. Fecal samples of a cohort of IBD patients were collected before and after 14 weeks of treatment with three different biologics. Clinical disease activity scores were used to determine the clinical response and remission. Fecal metaproteomes of remitting patients (n = 12) and of non-remitting patients (n = 12) were compared before treatment and changes within both groups were assessed over sampling time to identify functional changes and potential human and microbial biomarkers. The abundance of proteins associated with neutrophilic granulocytes, and immunoglobulins significantly decreased in remitting patients. There were changes in pathways of microbial metabolism in samples from patients with remission after therapy, including an increased butyrate fermentation. Distinct changes of proteins related to gut inflammation and gut microbiome metabolism showed whether IBD remission was achieved or not. This suggests that metaproteomics could be a useful tool for monitoring remission in IBD therapies. SIGNIFICANCE: IBD is rising in incidence, especially in newly industrialized countries, and the microbiome is an important contributor to its pathogenesis. Despite manifold therapeutical options, achieving remission is often ineffective, and choosing new alternative drugs remains often empirical. Therefore, efficient tools for monitoring therapeutic response and assessing the effectiveness of drugs in specific patients are mandatory. In the present study, we show that the use of metaproteomics is a promising avenue to address these challenges. We observed the amelioration of inflammation and restoration of a healthy microbiome in remitting patients in contrast to non-remitting patients. Therefore, metaproteomics is a valuable tool for monitoring the therapy success in IBD.

Repurposing Atorvastatin, HMGCO-A Reductase Inhibitor, in Patients with Ulcerative Colitis: A Randomized Controlled Study

Background/Objective: Among the inflammatory bowel illnesses, ulcerative colitis (UC) affects 5 million people worldwide. UC manifests as weight loss, rectal bleeding, persistent diarrhea, and abdominal pain. Experimental research focused into the potential benefits of atorvastatin for colitis, although the literature only has a small amount of clinical evidence. To examine atorvastatin's protective effect in UC patients by assessing its impact on fecal myeloperoxidase, zonulin, and disease activity index (DAI). Methods: Two groups of patients with mild to moderate UC were randomly assigned. Over a six-month period, the control group (placebo group) received a placebo alongside mesalamine (1 g, three times daily [t.i.d.]). The atorvastatin group received atorvastatin (80 mg once daily) in addition to mesalamine (1 g t.i.d.). Disease severity was assessed by a gastroenterologist using the Disease Activity Index (DAI). Serum zonulin and fecal myeloperoxidase levels were measured before and after treatment to assess the biological efficacy of the interventions. Outcomes: Reduction in DAI and biomarker levels. Results: Both groups showed a significant decrease in DAI, zonulin, and fecal myeloperoxidase levels. However, the atorvastatin group (n = 23) demonstrated a significantly greater decrease in zonulin (p = 0.04), fecal myeloperoxidase (p = 0.03), and DAI (p = 0.001) compared to the placebo group (n = 24). In atorvastatin group, a significant correlation was observed between DAI and zonulin (p = 0.007, r = 0.4) and myeloperoxidase (p = 0.02, r = 0.36). Conclusions: The co-administration of atorvastatin may serve as a potential adjunct therapy for patients with UC.

Host-microbiota interactions in the infant gut revealed by daily faecal sample time series

Aim: This study aims to explore the interplay between host immune factors and gut microbiota in human infants in vivo using time-series daily stool samples and identify biomarkers of host-microbe interactions. Methods: 216 faecal samples collected from infants aged 5-6 or 11-12 months were analysed for gut microbiota composition, total bacterial load, and biomarkers of immune function. Results: We identified indications of microbial stimulation of eosinophil cationic protein (ECP), IgA, calprotectin (Cal), intestinal alkaline phosphatase (IAP), and Bactericidal/permeability-increasing protein (BPI) at 6 and 12 months, as well as stimulation of lipocalin 2 (LCN2), lactoferrin (LTF), and alpha-defensin-5 only at 6 months. The associations between biomarker concentrations and bacterial population growth were primarily positive at 6 months and mostly negative at 12 months, suggesting increasing host regulation of the microbiota with age. The exceptions were IAP, which was predictive of declining bacterial populations at both time points, and Cal, whose associations changed from negative at 6 months to positive at 12 months. Conclusion: There is an age-associated development in the correlation pattern between bacterial population growth and the biomarker concentrations, suggesting that host-microbe interactions change during early development. Albumin appeared as a potential marker of gut permeability, while LCN2 seemed to correlate with gut transit time. Mucin degradation appeared to decrease with age. Mucin2 and IAP emerged as potentially important regulators of the bacterial populations in the infant gut. The study demonstrates the utility of biomarker and bacteria profiling from daily stool samples for analysing in vivo associations between the immune system and the gut microbiota and provides evidence of host regulation of the microbiota in infants.

Looking Inside of the Intestinal Permeability Regulation by Protein-Derivatives from Bovine Milk

The prime function of the epithelium is to regulate the intestinal permeability; the latter is a quantitative parameter that refers to the measurement of the rate of passage of solutes through the epithelial monolayer. Function of epithelial monolayer depends on the expression of protein complexes known as tight junction proteins; whose function and expression can be disrupted under conditions of inflammation including irritable bowel disease (IBD), intestinal infections, and high-fat diets, among others. This manuscript is focused to outline the effects of bovine milk protein derivatives on the intestinal permeability addressed mostly in animal models in which the intestinal barrier is disrupted. At present, the properties of bovine milk protein derivatives on intestinal permeability have been scarcely documented in humans, but evidence raised from clinical trials provides promising findings of potential application of colostrum to control of the intestinal permeability in critically ill patients, users of non-steroid anti-inflammatory drugs, like athletes and militia members.

Faecal intestinal permeability and intestinal inflammatory markers in older adults with age-related disorders: A systematic review and meta-analysis

This systematic review and meta-analysis appraised previous findings to uncover potential faecal intestinal permeability and intestinal inflammatory markers in older adults. A comprehensive literature search led to the identification of ten eligible studies with findings of potential faecal intestinal permeability (zonulin and alpha-1-antitrypsin) and intestinal inflammatory markers [calprotectin, lactoferrin and neutrophil gelatinase-associated lipocalin (NGAL)]. Most of the cases (n > 2) [Parkinson's disease (PD) and Alzheimer's disease (AD)] exhibited higher faecal alpha-1-antitrypsin, zonulin and calprotectin levels. The present meta-analysis confirmed significantly higher faecal alpha-1-antitrypsin in older persons with PD compared to non-PD [MD = 22.92 mg/dL; 95 % CI = 14.02-31.81, p < 0.00001; I2 = 0 % (p = 0.73)]. There was, however, no significant difference in faecal zonulin between PD and non-PD individuals [MD = 26.88 ng/mL; 95 % CI = -29.26-83.01, p = 0.35; I2 = 94 % (p < 0.0001)]. Meanwhile, faecal calprotectin was higher in older adults with GI symptoms, multiple system atrophy (MSA) or PD than the healthy controls [MD = 9.51 μg/g; 95 % CI = 0.07-18.95, p = 0.05; I2 = 84 % (p < 0.00001)]. Altogether, faecal calprotectin appears to be a potential intestinal inflammatory marker whereas previous findings on faecal alpha-1-antitrypsin as an intestinal permeability marker remain limited and require further validation.

A Novel Microbial Dysbiosis Index and Intestinal Microbiota-Associated Markers as Tools of Precision Medicine in Inflammatory Bowel Disease Paediatric Patients

Recent evidence indicates that the gut microbiota (GM) has a significant impact on the inflammatory bowel disease (IBD) progression. Our aim was to investigate the GM profiles, the Microbial Dysbiosis Index (MDI) and the intestinal microbiota-associated markers in relation to IBD clinical characteristics and disease state. We performed 16S rRNA metataxonomy on both stools and ileal biopsies, metabolic dysbiosis tests on urine and intestinal permeability and mucosal immunity activation tests on the stools of 35 IBD paediatric patients. On the GM profile, we assigned the MDI to each patient. In the statistical analyses, the MDI was correlated with clinical parameters and intestinal microbial-associated markers. In IBD patients with high MDI, Gemellaceae and Enterobacteriaceae were increased in stools, and Fusobacterium, Haemophilus and Veillonella were increased in ileal biopsies. Ruminococcaceae and WAL_1855D were enriched in active disease condition; the last one was also positively correlated to MDI. Furthermore, the MDI results correlated with PUCAI and Matts scores in ulcerative colitis patients (UC). Finally, in our patients, we detected metabolic dysbiosis, intestinal permeability and mucosal immunity activation. In conclusion, the MDI showed a strong association with both severity and activity of IBD and a positive correlation with clinical scores, especially in UC. Thus, this evidence could be a useful tool for the diagnosis and prognosis of IBD.

Can Faecal Zonulin and Calprotectin Levels Be Used in the Diagnosis and Follow-Up in Infants with Milk Protein-Induced Allergic Proctocolitis?

OBJECTIVE

The aim of our study was to investigate whether a 1-month-long milk-free diet results in a reduction in faecal calprotectin (FC) and faecal-zonulin-related proteins (FZRP) in children with milk-protein-induced allergic proctocolitis (MPIAP).

MATERIALS AND METHODS

This is a single-centre, prospective, observational cohort study involving 86 infants with MPIAP, aged 1-3 months, and 30 healthy controls of the same age. The FC and FZRP were marked using the ELISA method (IDK® Calprotectin or Zonulin ELISA Kit, Immunodiagnostik AG, Bensheim, Germany). The diagnosis of MPIAP was confirmed with an open milk challenge test.

RESULTS

FFC and FZRP proved useful in evaluating MPIAP treatment with a milk-free diet, and the resolution of allergic symptoms and a significant (p = 0.0000) decrease in the concentrations of both biomarkers were observed after 4 weeks on the diet. The FC and FZRP concentrations were still higher than in the control group. A high variability of FC concentrations was found in all the study groups. An important limitation is the phenomenon of FZRP not being produced in all individuals, affecting one in five infants.

CONCLUSIONS

FC and FZRP can be used to monitor the resolution of colitis in infants with MPIAP treated with a milk-free diet, indicating a slower resolution of allergic inflammation than of allergic symptoms. The diagnosis of MPIAP on the basis of FC concentrations is subject to considerable error, due to the high individual variability of this indicator. FZRP is a better parameter, but this needs further research, as these are the first determinations in infants with MPIAP.

Bovine Colostrum in Increased Intestinal Permeability in Healthy Athletes and Patients: A Meta-Analysis of Randomized Clinical Trials

BACKGROUND

Increasing intestinal permeability causes chronic inflammation, which is one of the etiological factors of many diseases that presently constitute global challenges.

AIMS

Considering the importance of developing therapies to eliminate the increased intestinal permeability, in this systematic review and meta-analysis, we analyze the impact of bovine colostrum (BC) on the gut barrier and its permeability.

METHODS

Online databases, including PubMed, ISI Web of Science, and Scopus, were searched to find pertinent articles up to March 2022. Weighted mean difference (WMD) and 95% confidence intervals (CI) were considered as effect sizes. The random-effects model was used to pool the study results.

RESULTS

A total of ten articles were included in the meta-analysis. The pooled effect revealed a significant reduction in the 5-h urinary lactulose/rhamnose ratio after BC consumption [mean difference (MD): -0.24; 95% CI -0.43 to -0.04; I2 = 99%] and urinary lactulose/mannitol ratio (MD: -0.01; 95% CI -0.02 to -0.001; I2 = 29.8%). No differences were observed in the plasma intestinal fatty acid-binding protein (I-FABP) between BC and control groups (MD: 2.30; 95% CI -293.9 to 298.5; I2 = 92%).

CONCLUSIONS

BC supplementation significantly reduced intestinal permeability; however, to confirm the results, more randomized clinical trials considering different quality, dose, and duration are needed.

Trends in Faecal Zonulin Concentrations in Paediatric Patients with Celiac Disease at Baseline and on a Gluten-Free Diet: Exploring Correlations with Other Faecal Biomarkers

Celiac disease (CeD) is an autoimmune condition triggered by gluten in genetically predisposed individuals, affecting all ages. Intestinal permeability (IP) is crucial in the pathogenesis of CeD and it is primarily governed by tight junctions (TJs) that uphold the intestinal barrier's integrity. The protein zonulin plays a critical role in modulating the permeability of TJs having emerged as a potential non-invasive biomarker to study IP. The importance of this study lies in providing evidence for the usefulness of a non-invasive tool in the study of IP both at baseline and in the follow-up of paediatric patients with CeD. In this single-centre prospective observational study, we explored the correlation between faecal zonulin levels and others faecal and serum biomarkers for monitoring IP in CeD within the paediatric population. We also aimed to establish reference values for faecal zonulin in the paediatric population. We found that faecal zonulin and calprotectin values are higher at the onset of CeD compared with the control population. Specifically, the zonulin levels were 347.5 ng/mL as opposed to 177.7 ng/mL in the control population (p = 0.001), while calprotectin levels were 29.8 μg/g stool compared to 13.9 μg/g stool (p = 0.029). As the duration without gluten consumption increased, a significant reduction in faecal zonulin levels was observed in patients with CeD (348.5 ng/mL vs. 157.1 ng/mL; p = 0.002), along with a decrease in the prevalence of patients with vitamin D insufficiency (88.9% vs. 77.8%). We conclude that faecal zonulin concentrations were higher in the patients with active CeD compared with healthy individuals or those following a gluten-free diet (GFD). The significant decrease in their values over the duration of the GFD suggests the potential use of zonulin as an additional tool in monitoring adherence to a GFD.

New noninvasive biomarkers of intestinal inflammation and increased intestinal permeability in pediatric inflammatory bowel diseases and their correlation with fecal calprotectin: a pilot study

BACKGROUND

Increased intestinal permeability is considered to play a crucial role in the pathogenesis of inflammatory bowel diseases (IBD). Therefore, recently, the use of non-invasive biomarkers in both diagnosis and monitoring IBD is emphasized. The aim of this study was to investigate fecal and serum zonulin and serum I-FABP in pediatric IBD patients and their correlation with fecal calprotectin (FCP).

METHODS

Seventy-one individuals: 32 Crohn's disease (CD) patients, 33 ulcerative colitis (UC) patients and 6 controls were examined for fecal and serum zonulin and plasma I-FABP. Values were correlated to FCP and to each other for all children included in the study. A stool specimen and blood samples were collected during check-up visits at hospital. Then fecal and serum zonulin, I-FABP and FCP were tested by ELISA Test. Non-parametric statistical tests were used for data analysis.

RESULTS

The level of fecal zonulin and FCP were higher in IBD patients compared to control group (CG): median for CD - 46.0 (7.0-3854) ng/mL, 252.0 (77.0-1054.2) ug/g; UC - 115.3 (50.7-418.3) ng/mL, 40 (16.0-1883.0) ug/g; CG - 60.8 (31.8-123.0) ng/mL, 41.5 (31.0-323.0) ug/g, respectively, (P<0.05). No statistically significant difference in concentrations of serum zonulin and I-FABP was reported between patients and CG (P=0.55). The only correlation that has been reported was between fecal zonulin and FCP and the strongest one was in CD: CD-R =0.73, UC-R =0.67, All-R =0.67, CG-R =0.65.

CONCLUSIONS

According to our results it seems that only fecal zonulin may serve as another, next to FCP, biomarker of intestinal damage in IBD. However, both fecal and serum zonulin as well as I-FABP need further studies to assess their usefulness in diagnostics and monitoring in IBD.

Wolfberry, Yam, and Chrysanthemum polysaccharides increased intestinal Akkermansia muciniphila abundance and hepatic YAP1 expression to alleviate DILI

Drug-induced liver injury (DILI) is frequently induced by high dose of acetaminophen (APAP) and is concomitant with disturbances of gut flora. Akkermansia muciniphila is beneficial for the repair of liver injury. Lycium barbarum polysaccharide, yam polysaccharide, and chrysanthemum polysaccharide all have anti-inflammatory and antioxidation effects. The objective of this study is to investigate the potential of lycium barbarum polysaccharide, yam polysaccharide, and chrysanthemum polysaccharide (LYC) in improving DILI by increasing the abundance of A. muciniphila. Initially, screening for the optimal concentrations of wolfberry, yam, and chrysanthemum (WYC) or LYC to promote A. muciniphila proliferation in vitro and validated in antibiotic (ATB)-treated KM mice. Subsequently, APAP-induced DILI model in BALB/c mice were constructed to examine the treatment effects of LYC. Our findings indicate that the optimal concentration ratio of WYC was 2:3:2, and LYC was 1:1:1. WYC increased A. muciniphila proliferation in vitro and in ATB-treated mice under this ratio. Meanwhile, LYC increased A. muciniphila abundance in vitro and the combination LYC with A. muciniphila promoted the proliferation of A. muciniphila in ATB-treated mice. The overdose of APAP resulted in the impairment of the intestinal barrier function and subsequent leakage of lipopolysaccharide (LPS). Moreover, LYC increased A. muciniphila abundance, reduced intestinal inflammation and permeability, and upregulated the expression of the tight junction protein zonula occludens protein 1 (ZO-1) and occludin contents in the gut. Lastly, LYC inhibited LPS leakage and upregulated hepatic YAP1 expression, ultimately leading to the repair of DILI.

Systematic review and meta-analysis of human health-related protein markers for realizing real-time wastewater-based epidemiology

For effective implementation of the wastewater-based epidemiology (WBE) approach, real-time quantification of markers in wastewater is critical for data acquisition before data interpretation, dissemination, and decision-making. This can be achieved by using biosensor technology, but whether the quantification/detection limits of different types of biosensors comply with the concentration of WBE markers in wastewater is unclear. In the present study, we identified promising protein markers with relatively high concentrations in wastewater samples and analyzed biosensor technologies that are potentially available for real-time WBE. The concentrations of potential protein markers in stool and urine samples were obtained through systematic review and meta-analysis. We examined 231 peer-review papers to collect information regarding potential protein markers that can enable us to achieve real-time monitoring using biosensor technology. Fourteen markers in stool samples were identified at the ng/g level, presumably equivalent to ng/L of wastewater after dilution. Moreover, relatively high average concentrations of fecal inflammatory proteins were observed, e.g., fecal calprotectin, clusterin, and lactoferrin. Fecal calprotectin exhibited the highest average log concentration among the markers identified in stool samples with its mean value being 5.24 [95 % CI: 5.05, 5.42] ng/g. We identified 50 protein markers in urine samples at the ng/mL level. Uromodulin (4.48 [95 % CI: 4.20, 4.76] ng/mL) and plasmin (4.18 [95 % CI: 3.15, 5.21] ng/mL) had the top two highest log concentrations in urine samples. Furthermore, the quantification limit of some electrochemical- and optical-based biosensors was found to be around the femtogram/mL level, which is sufficiently low to detect protein markers in wastewater even after dilution in sewer pipes.

Celiac Disease in Uzbek Children: Insights into Disease Prevalence and Clinical Characteristics in Symptomatic Pediatric Patients

BACKGROUND

A few studies on pediatric Celiac Disease (CD) are available from Central Asia. Recent immunogenetic research has highlighted that the HLA-DQ2/8 genetic predisposition to CD as well as the dietary intake of gluten in this geographical area, are comparable to other regions of the world where CD prevalence is known to be 1% or higher.

METHODS

This is a prospective and cross-sectional study investigating the prevalence and clinical characteristics of CD in symptomatic children referred to the pediatric gastroenterology department of a tertiary hospital in Uzbekistan from 1 September 2021, until 31 July 2022. In addition to collecting the relevant information related to clinical manifestations and laboratory analyses from the clinical files, a specific survey was also administered to patients' guardians. Serological, histopathological, and immunogenetic parameters specific to CD, fecal zonulin, and pancreatic elastases were assessed in CD patients.

RESULTS

The study population consisted of 206 children. Overall, almost all of them (n = 192; 93.2%) were referred because of gastrointestinal manifestations, which were associated with extra-gastrointestinal manifestations in most cases (n = 153; 74.3%); a minority (n = 14; 6.8%) was mainly referred due short stature and/or growth failure only. Among all of these study participants, CD was diagnosed in 11 children (5.3%). Notably, although diarrhea was similarly reported in CD and non-CD patients, watery diarrhea (type 7 according to the Bristol stool scale) was much more frequently and significantly observed in the former group. All of these CD patients showed anti-tTG IgA 10 times higher than the upper normal limit, except one child with lower serum levels of total IgA; however, all of them received a diagnostic confirmation by histopathological analysis due to the lack of EMA testing in the country. Notably, most CD children (82%) showed a Marsh III histological grading. Around half patients (54.5%) showed zonulin values above the reference range, whereas none showed insufficient levels of pancreatic elastase. However, no correlation or association between zonulin and clinical, laboratory, histopathological, and immunogenetic parameters was found.

CONCLUSIONS

This study may further suggest a relevant prevalence of CD in Uzbek children, based on this partial picture emerging from symptomatic patients only. Additionally, we highlighted the prevalence of typical CD forms with watery diarrhea, which should strongly support a full diagnostic work-up for CD in the local clinical setting. The high levels of anti-tTG IgA and high Marsh grade might also lead us to speculate a significant diagnostic delay despite the classical clinical expression of CD.

Early life exposure to low-dose perfluorooctane sulfonate disturbs gut barrier homeostasis and increases the risk of intestinal inflammation in offspring

Perfluorooctane sulfonate (PFOS), one of the legacy per- and poly-fluoroalkyl substances (PFAS), is associated with multiple adverse health effects on children. However, much remains to be known about its potential impacts on intestinal immune homeostasis during early life. Our study found that PFOS exposure during pregnancy in rats significantly increased the maternal serum levels of interleukin-6 (IL-6) and zonulin, a gut permeability biomarker, and decreased gene expressions of Tight junction protein 1 (Tjp1) and Claudin-4 (Cldn4), the tight junction proteins, in maternal colons on gestation day 20 (GD20). Being exposed to PFOS during pregnancy and lactation in rats significantly decreased the body weight of pups and increased the offspring's serum levels of IL-6 and tumor necrosis factor-α (TNF-α) on postnatal day 14 (PND14), and induced a disrupted gut tight junction, manifested by decreased expressions of Tjp1 in pup's colons on PND14 and increased pup's serum concentrations of zonulin on PND28. By integrating high-throughput 16S rRNA sequencing and metabolomics, we demonstrated that early-life PFOS exposure altered the diversity and composition of gut microbiota that were correlated with the changed metabolites in serum. The altered blood metabolome was associated with increased proinflammatory cytokines in offspring. These changes and correlations were divergent at each developmental stage, and pathways underlying immune homeostasis imbalance were significantly enriched in the PFOS-exposed gut. Our findings provide new evidence for the developmental toxicity of PFOS and its underlying mechanism and explain in part the epidemiological observation of its immunotoxicity.

A spotlight on intestinal permeability and inflammatory bowel diseases

INTRODUCTION

The intestinal barrier is a multi-faced structure lining the surface of the intestinal mucosa of the GI tract. To exert its main functions as a physical and immunological defense barrier, several components of the intestinal barrier act in a concerted and cooperative manner.

AREAS COVERED

Herein, we first introduce to the basic organization of the intestinal barrier and then summarize different methods to assess barrier function in and ex vivo. Finally, we provide an in-depth overview of the relevance of intestinal barrier dysfunction in inflammatory bowel diseases.

EXPERT OPINION

In parallel to a more fundamental understanding of the intestinal barrier as a key component for intestinal integrity is the notion that intestinal barrier defects are associated with a variety of diseases such as inflammatory bowel diseases. Recent research has fueled and perpetuated the concept that barrier defects are critical components of disease development, disease behavior, and potentially also an area of therapeutic intervention in IBD patients. Although being far away from standard, new technologies can be used to easily assess barrier healing in IBD and to derive clinical consequences from these findings such as more accurate forecasting of future disease behavior or the identification of novel therapeutic targets.

Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis

Increased intestinal permeability and inflammation, both fueled by dysbiosis, appear to contribute to rheumatoid arthritis (RA) pathogenesis. This single-center pilot study aimed to investigate zonulin, a marker of intestinal permeability, and calprotectin, a marker of intestinal inflammation, measured in serum and fecal samples of RA patients using commercially available kits. We also analyzed plasma lipopolysaccharide (LPS) levels, a marker of intestinal permeability and inflammation. Furthermore, univariate, and multivariate regression analyses were carried out to determine whether or not there were associations of zonulin and calprotectin with LPS, BMI, gender, age, RA-specific parameters, fiber intake, and short-chain fatty acids in the gut. Serum zonulin levels were more likely to be abnormal with a longer disease duration and fecal zonulin levels were inversely associated with age. A strong association between fecal and serum calprotectin and between fecal calprotectin and LPS were found in males, but not in females, independent of other biomarkers, suggesting that fecal calprotectin may be a more specific biomarker than serum calprotectin is of intestinal inflammation in RA. Since this was a proof-of-principle study without a healthy control group, further research is needed to validate fecal and serum zonulin as valid biomarkers of RA in comparison with other promising biomarkers.

Development of an Inflammation-Triggered In Vitro "Leaky Gut" Model Using Caco-2/HT29-MTX-E12 Combined with Macrophage-like THP-1 Cells or Primary Human-Derived Macrophages

The "leaky gut" syndrome describes a damaged (leaky) intestinal mucosa and is considered a serious contributor to numerous chronic diseases. Chronic inflammatory bowel diseases (IBD) are particularly associated with the "leaky gut" syndrome, but also allergies, autoimmune diseases or neurological disorders. We developed a complex in vitro inflammation-triggered triple-culture model using 21-day-differentiated human intestinal Caco-2 epithelial cells and HT29-MTX-E12 mucus-producing goblet cells (90:10 ratio) in close contact with differentiated human macrophage-like THP-1 cells or primary monocyte-derived macrophages from human peripheral blood. Upon an inflammatory stimulus, the characteristics of a "leaky gut" became evident: a significant loss of intestinal cell integrity in terms of decreased transepithelial/transendothelial electrical resistance (TEER), as well as a loss of tight junction proteins. The cell permeability for FITC-dextran 4 kDa was then increased, and key pro-inflammatory cytokines, including TNF-alpha and IL-6, were substantially released. Whereas in the M1 macrophage-like THP-1 co-culture model, we could not detect the release of IL-23, which plays a crucial regulatory role in IBD, this cytokine was clearly detected when using primary human M1 macrophages instead. In conclusion, we provide an advanced human in vitro model that could be useful for screening and evaluating therapeutic drugs for IBD treatment, including potential IL-23 inhibitors.

Programming Factors of Neonatal Intestinal Dysbiosis as a Cause of Disease

The intestinal microbiota consists of trillions of bacteria, viruses, and fungi that achieve a perfect symbiosis with the host. They perform immunological, metabolic, and endocrine functions in the body. The microbiota is formed intrauterine. Dysbiosis is a microbiome disorder characterized by an imbalance in the composition of the microbiota, as well as changes in their functional and metabolic activities. The causes of dysbiosis include improper nutrition in pregnant women, hormone therapy, the use of drugs, especially antibiotics, and a lack of exposure to the mother's vaginal microbiota during natural birth. Changes in the intestinal microbiota are increasingly being identified in various diseases, starting in the early neonatal period into the adult period. Conclusions: In recent years, it has become more and more obvious that the components of the intestinal microbiota are crucial for the proper development of the immune system, and its disruption leads to disease.

The use of calgranulin-C (S100A12) and fecal zonulin as possible non-invasive markers in children with inflammatory bowel disease: a clinical study

Calgranulin-C (S100A12) and zonulin are considered markers of intestinal inflammation. Our aim was to evaluate fecal S100A12 (f-S100A12) and fecal zonulin (f-zonulin) in children with inflammatory bowel disease (IBD), compared to fecal calprotectin (FC) and serum inflammatory markers. We enrolled children with a previous diagnosis of Crohn's disease (CD) and ulcerative colitis (UC). F-S100A12, f-zonulin, and FC were determined by enzyme-linked immunosorbent assay (ELISA). Endoscopic examination was considered in the patients who underwent ileocolonoscopy within 2 weeks from the enrollment. One hundred seventeen children, 39.3% with CD and 60.7% with UC were enrolled. In both CD and UC, there was a significant direct correlation between FC and f-S100A12 levels. In children with CD and UC, both FC and f-S100A12 correlated with markers of serum inflammation. We found difference in FC and f-S100A12 levels between patients in clinical relapse and remission (FC: mean 1027 ± 818 mcg/ml vs 580 ± 695 mcg/ml respectively, p = 0.028; f-S100A12: mean 66.4 ± 48.2 mcg/ml vs 42.7 ± 40 mcg/ml, respectively p = 0.02). Moreover, we found difference in FC between children with endoscopic inflammation and remission (mean 825 ± 779 mcg/ml vs 473.3 ± 492 mcg/ml, respectively p = 0.048), as well as for f-S100A12 (53 ± 43 mcg/ml vs mean 31 ± 33 mcg/ml vs, respectively p = 0.019). No significant results were found for f-zonulin.

CONCLUSION

Our data suggest that f-S100A12 and FC are both useful non-invasive biomarkers in the management of pediatric IBD in follow up and in monitoring endoscopic and clinical relapse.

WHAT IS KNOWN

• Fecal calprotectin (FC), fecal S100A12 (f- S100A12), and fecal zonulin represent potential noninvasive markers of gut inflammation. • Since S100A12 is predominantly expressed by granulocytes, high levels of f-S100A12 should be more specific for inflammation than FC.

WHAT IS NEW

• FC and f-S100A12 were correlated to each other and despite the lack of correlation with disease location, they were associated with endoscopic inflammation and clinical relapse in children with IBD. • No significant correlations were found between f-zonulin and the inflammatory parameters.

Morphological Assessment and Biomarkers of Low-Grade, Chronic Intestinal Inflammation in Production Animals

Simple Summary

Production animals are continuously exposed to environmental and dietary factors that might induce a state of low-grade, chronic intestinal inflammation. This condition compromises the productive performance and well-fare of these animals, requiring studies to understand what causes it and to develop control strategies. An intestinal inflammatory process is generally associated with alterations in the structure and functionality of its wall, resulting in the release of cellular components into the blood and/or feces. These components can act as biomarkers, i.e., they are measured to identify and quantify an inflammatory process without requiring invasive methods. In this review we discuss the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the identification of biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

Abstract

The complex interaction between the intestinal mucosa, the gut microbiota, and the diet balances the host physiological homeostasis and is fundamental for the maximal genetic potential of production animals. However, factors such as chemical and physical characteristics of the diet and/or environmental stressors can continuously affect this balance, potentially inducing a state of chronic low-grade inflammation in the gut, where inflammatory parameters are present and demanding energy, but not in enough intensity to provoke clinical manifestations. It’s vital to expand the understanding of inflammation dynamics and of how they compromise the function activity and microscopic morphology of the intestinal mucosa. These morphometric alterations are associated with the release of structural and functional cellular components into the feces and the blood stream creating measurable biomarkers to track this condition. Moreover, the identification of novel, immunometabolic biomarkers can provide dynamic and predictors of low-grade chronic inflammation, but also provide indicators of successful nutritional or feed additive intervention strategies. The objective of this paper is to review the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

The association of zonulin-related proteins with prevalent and incident inflammatory bowel disease

Background

Current evidence regarding the association of serum zonulin-related proteins (ZRP) levels with prevalent inflammatory bowel disease (IBD) is contradictory. Moreover, the association with the subsequent risk of incident IBD is still unexplored. This study aimed to investigate the association of serum ZRP levels with both prevalent and incident IBD.

Method

The study included a total of 130 women (51–61 years) from the Women’s Health in Lund Area (WHILA) study, which included 18 prevalent IBD (diagnosed before baseline) and 47 incident IBD diagnosed during the 17 years (median) follow-up and age- and sampling time-matched controls. Serum ZRP was tested in all participants by ELISA.

Results

The serum ZRP levels were significantly higher in prevalent IBD compared to their matched controls (63.2 ng/ml vs 57.0 ng/ml, p = 0.02), however, no evidence of a difference in ZRP levels was found between the women who developed IBD during the follow-up period and their matched controls (61.2 ng/ml vs 59.7 ng/ml, p = 0.34). Using linear mixed models, we found that the association between serum ZRP levels and prevalent IBD (β = 6.2, p = 0.01), remained after adjusting for potential confounders. Conditional logistic regression models showed no evidence of an association between ZRP level and incident IBD (OR 1.03, p = 0.34).

Conclusion

Higher serum ZRP levels were associated with prevalent IBD, but not with incident IBD in our study samples.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-02075-y.

Gut Microbial Metabolite-Mediated Regulation of the Intestinal Barrier in the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease. The disease has a multifactorial aetiology, involving genetic, microbial as well as environmental factors. The disease pathogenesis operates at the host-microbe interface in the gut. The intestinal epithelium plays a central role in IBD disease pathogenesis. Apart from being a physical barrier, the epithelium acts as a node that integrates environmental, dietary, and microbial cues to calibrate host immune response and maintain homeostasis in the gut. IBD patients display microbial dysbiosis in the gut, combined with an increased barrier permeability that contributes to disease pathogenesis. Metabolites produced by microbes in the gut are dynamic indicators of diet, host, and microbial interplay in the gut. Microbial metabolites are actively absorbed or diffused across the intestinal lining to affect the host response in the intestine as well as at systemic sites via the engagement of cognate receptors. In this review, we summarize insights from metabolomics studies, uncovering the dynamic changes in gut metabolite profiles in IBD and their importance as potential diagnostic and prognostic biomarkers of disease. We focus on gut microbial metabolites as key regulators of the intestinal barrier and their role in the pathogenesis of IBD.