A pilot study on the noninvasive evaluation of intestinal damage in celiac disease using I-FABP and L-FABP

Global Approach to Follow-Up of Celiac Disease

Celiac disease, an autoimmune disorder induced by the ingestion of gluten, affects approximately 1.4% of the population. Gluten damages the villi of the small intestine, producing symptoms such as abdominal pain, bloating and a subsequent loss of nutrient absorption, causing destabilization of the nutritional status. Moreover, gluten can trigger extra intestinal symptoms, such as asthma or dermatitis, but also mental disorders such as depression or anxiety. Moreover, people suffering from celiac disease sometimes feel misunderstood by society, mainly due to the lack of knowledge about the disease and the gluten-free diet. Thus, the treatment and follow-up of patients with celiac disease should be approached from different perspectives, such as the following: (1) a clinical perspective: symptomatology and dietary adherence monitorization; (2) nutritional assessment: dietary balance achievement; (3) psychological assistance: mental disorders avoidance; and (4) social inclusion: educating society about celiac disease in order to avoid isolation of those with celiac disease. The aim of this narrative review is to gain deep insight into the different strategies that currently exist in order to work on each of these perspectives and to clarify how the complete approach of celiac disease follow-up should be undertaken so that the optimum quality of life of this collective is reached.

Intestinal immunological events of acute and resolved SARS-CoV-2 infection in non-human primates

SARS-CoV-2 infection has been associated with intestinal mucosal barrier damage, leading to microbial and endotoxin translocation, heightened inflammatory responses, and aggravated disease outcomes. This study aimed to investigate the immunological mechanisms associated with impaired intestinal barrier function. We conducted a comprehensive analysis of gut damage and inflammation markers and phenotypic characterization of myeloid and lymphoid populations in the ileum and colon of SARS-CoV-2-exposed macaques during both the acute and resolved infection phases. Our findings revealed a significant accumulation of terminally differentiated and activated CD4+ and CD8+ T cells, along with memory B cells, within the gastrointestinal tract up to 43 days after exposure to SARS-CoV-2. This robust infection-induced immune response was accompanied by a notable depletion of plasmacytoid dendritic cells, myeloid dendritic cells, and macrophages, particularly affecting the colon during the resolved infection phase. Additionally, we identified a population of CX3CR1Low inflammatory macrophages associated with intestinal damage during active viral replication. Elevated levels of immune activation and gut damage markers, and perturbation of macrophage homeostasis, persisted even after the resolution of the infection, suggesting potential long-term clinical sequelae. These findings enhance our understanding of gastrointestinal immune pathology following SARS-CoV-2 infection and provide valuable information for developing and testing medical countermeasures.

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.

Effective alternatives for dietary interventions for necrotizing enterocolitis: a systematic review of in vivo studies

Necrotizing enterocolitis (NEC) is a significant cause of morbidity and mortality among neonates and low birth weight children in the United States. Current treatment options, such as antibiotics and intestinal resections, often result in complications related to pediatric nutrition and development. This systematic review aimed to identify alternative dietary bioactive compounds that have shown promising outcomes in ameliorating NEC in vivo studies conducted within the past six years. Following PRISMA guidelines and registering in PROSPERO (CRD42023330617), we conducted a comprehensive search of PubMed, Scopus, and Web of Science. Our analysis included 19 studies, predominantly involving in vivo models of rats (Rattus norvegicus) and mice (Mus musculus). The findings revealed that various types of compounds have demonstrated successful amelioration of NEC symptoms. Specifically, six studies employed plant phenolics, seven utilized plant metabolites/cytotoxic chemicals, three explored the efficacy of vitamins, and three investigated the potential of whole food extracts. Importantly, all administered compounds exhibited positive effects in mitigating the disease. These results highlight the potential of natural cytotoxic chemicals derived from medicinal plants in identifying and implementing powerful alternative drugs and therapies for NEC. Such approaches have the capacity to impact multiple pathways involved in the development and progression of NEC symptoms.

HMGB1 is related to disease activity in children with celiac disease

INTRODUCTION

We aim to evaluate of the relationship between high mobility gene box-1 (HMGB1) levels and clinical, laboratory and histopathological findings at diagnosis and in remission in children with Celiac Disease (CD).

MATERIAL AND METHODS

The study included 36 celiac patients at diagnosis, 36 celiac patients in remission, and 36 healthy controls. Patients with intestinal pathologies other than CD, and accompanying inflammatory and/or autoimmune diseases were excluded. Relationship between HMGB1 levels and clinical, laboratory and histopathological findings were evaluated.

RESULTS

A total of 72 celiac patients [36 (18 girls, 18 boys, mean age 9.41±3.9 years) in group 1 and 36 (18 girls, 18 boys, mean age 9.91±3.36 years) in group 2] and 36 healthy controls in group 3 (19 girls, 17 boys, mean age 9.56±4 years) were included. The HMGB1 level was significantly higher in group 1 compared to group 2 and group 3 [36.63 (17.98-54.72) ng/ml vs 20.31 (16.89-29.79) ng/ml, p = 0.028 and 36.63 (17.98-54.72) ng/ml vs 20.38 (17.54-24.53) ng/ml p = 0.012, respectively]. A serum HMGB-1 level of 26.553 ng/ml was found to be a cut-off value for the CD with 61% sensitivity, 83% specificity, 78% positive predictive value, and 68% negative predictive value. Higher HMGB1 values were seen in patients with intestinal findings, anemia, anti-tissue transglutaminase IgA levels that were greater than 10 times upper limit of normal, and patients with a higher degree of atrophy as classified by Marsh-Oberhuber.

CONCLUSIONS

In conclusion, it was thought that HMGB-1 might be a marker that reflects the severity of atrophy at the time of diagnosis and could be used to control dietary compliance in the follow-up. However, there is need for larger population studies in order to evaluate its value as a serological marker for the diagnosis and follow-up of CD and to find a more reliable cut-off value.

Efficacy of short-chain polypeptide-based EEN formulas in alleviating intestinal injury in children with Crohn's disease: a single-center study in China

Short-chain polypeptides are composed of three to nine amino acids, which can be absorbed by the intestinal tract without digestive enzymes and ATP energy. Crohn's disease (CD) is a chronic non-specific disease derived from inflammation and damage of the gastrointestinal tract. In this study, we aim to investigate the effect of short-chain polypeptide-based exclusive enteral nutrition (EEN) formulas on intestinal injury in Chinese children with active CD. From January 2013 to January 2019, a total of 84 consecutive children with a diagnosis of Crohn's disease (CD) in the Department of Pediatric Gastroenterology, Children's Hospital of Nanjing Medical University, were divided into mild and moderate-to-severe active CD groups. Each group was further divided into two subgroups: drug group and short-chain polypeptide plus drug group. Tests were carried out on the levels of intestinal fatty acid binding protein (I-FABP) in the blood, fecal calprotectin (FC), and occludin protein in the intestinal mucosa 1 day before treatment and 8 weeks after treatment. Endoscopic and histopathological observations were detected to compare the changes in intestinal injury in children with active CD. After 8 weeks of treatment, the SES-CD scores and Chiu scores of the ileocecal area and terminal ileum of children with mild active CD and the ileocecal area of children with moderate-to-severe active CD in short-chain polypeptide plus drug group were significantly lower than those in the drug group. The OD value of occludin in the terminal ileum and ileocecal area of children with mild active CD and the ileocecal area of children with moderate-to-severe active CD after short-chain polypeptide-based EEN formulas and drug treatment was significantly higher than those in the drug group (p < 0.05). Meanwhile, the levels of FC and I-FABP were significantly decreased (p < 0.05). The results showed that short-chain polypeptide-based EEN formulas effectively alleviate intestinal injury in children with active CD.

Choline, DHA, and Diarrheal Disease Associated with Growth Faltering in a Case-Control Study

Background

Children with recurrent infectious diarrhea are susceptible to growth faltering. DHA and choline may play a role in this relationship due to their involvement in lipid metabolism, gut immunity, and inflammatory pathways.

Objectives

This study aimed to characterize the contributions made by DHA and choline status and enteric damage in young children in the association between diarrheal illness and child growth.

Methods

A longitudinal case-control study was conducted among children aged 6-36 mo (N = 195) in Cap-Haitien, Haiti. Mother-child dyads were recruited from community health posts and outpatient clinics. Cases were defined as children experiencing acute diarrhea within the last 3 d and matched to healthy controls. Child anthropometry, dietary intake, and blood and stool samples were collected at baseline and follow-up. Plasma DHA, choline, and betaine were determined by LC-MS/MS methods (n = 49) and intestinal fatty acid-binding protein (I-FABP) by ELISA (n = 183). Multivariate regression models were applied with mediation analyses to examine associations and adjust for confounding factors.

Results

At baseline, mean plasma DHA concentrations (1.03 µg/mL; 95% CI: 0.91, 1.15) were not significantly different between cases and controls, nor was there a difference in mean plasma choline concentrations (4.5 µg/mL; 95% CI: 3.8, 5.1). Mean plasma I-FABP concentrations were significantly higher at follow-up in cases (3.34; 95% CI: 3.28, 3.40) than controls (3.20; 95% CI: 3.13, 3.27; P = 0.002). In adjusted multilinear regression models, higher plasma DHA concentrations at follow-up were associated with a negative change in weight-age z score (P = 0.016), and follow-up I-FABP was inversely associated with height-age z score (P = 0.035). No interaction or mediation effects were found.

Conclusions

I-FABP concentrations were significantly higher in cases as compared with controls at follow-up, suggesting ongoing enteric damage and increased risk for malnutrition. Plasma DHA and I-FABP may have a role in childhood growth outcomes.

Emerging Biomarkers for Screening and Management of Celiac Disease

Celiac disease (CeD) is a chronic, immune-mediated enteropathy that is precipitated by dietary gluten in genetically predisposed individuals expressing HLA-DQ2 and/or HLA-DQ8. In the current clinical practice, there are many serologic studies to aid in the diagnosis of CeD which include autoantibodies like IgA antitissue transglutaminase, antiendomysium, and antideamidated forms of gliadin peptide antibodies. Small intestinal biopsy has long been considered an essential step for the diagnosis of CeD. However, in the recent era, researchers have explored the possibility of CeD screening and diagnosis without endoscopy or biopsy. The newer emerging biomarkers of CeD appear promising in diagnostic evaluation and subsequent monitoring of disease. In this review of literature, we have explored the emerging biomarker-based diagnostic evaluation and monitoring of CeD.

Could I-FABP Be an Early Marker of Celiac Disease in Children with Type 1 Diabetes? Retrospective Study from the Tertiary Reference Centre

Patients with type 1 diabetes (T1D) are at higher risk of celiac disease (CD). Recently, intestinal fatty acid binding protein (I-FABP) has been shown to be a serological biomarker of impaired intestinal barrier in CD. Thus, the aim of this study was to verify whether I-FABP could be an early marker of CD in pediatric T1D patients. I-FABP was measured in sera of patients with T1D (n = 156), active CD (n = 38), T1D with active CD (T1D-CD, n= 51), and age-matched healthy children (n = 55). Additionally, I-FABP was determined in T1D patients with negative CD serology at least one year before CD diagnosis (T1D-CD-1, n = 22), in CD patients on a gluten-free diet (CD-GFD, n = 36), and T1D-CD patients on GFD (T1D-CD-GFD, n = 39). Sera were tested using immunoenzymatic assay. Significantly increased levels of I-FABP were found in the T1D, active CD, and T1D-CD groups (1153 ± 665, 1104 ± 916, and 1208 ± 878, respectively) in comparison to healthy with controls (485 ± 416, p < 0.05). GFD induced a significant decrease in I-FABP levels in CD and T1D-CD groups (510 ± 492 and 548 ± 439, respectively). Interestingly, in T1D-CD-1 and T1D, I-FABP levels were comparable (833 ± 369 vs. 1153 ± 665), and significantly increased in relation to healthy controls and T1D-CD values on GFD. The results indicate that the epithelial barrier is disrupted in T1D patients independently of CD development; therefore, I-FABP cannot serve as an early marker of CD in T1D patients. Although GFD can improve epithelial recovery, the question remains as to whether GFD could exert beneficial effects on the intestinal barrier in early stages of T1D.

Intestinal Fatty Acid Binding Protein Levels in Pediatric Celiac Patients in Transition From Active Disease to Clinical and Serological Remission

Celiac disease (CD) is increasingly diagnosed without endoscopy. As such, the need for accurate serological markers to aid in the diagnosis and follow-up of CD has increased. Intestinal fatty acid binding protein (I-FABP) is a cytosolic protein present in enterocytes, whose blood levels reflect mucosal damage in a reliable and quantifiable way. The aim of this study was to compare I-FABP levels in newly diagnosed patients with CD and to examine changes in levels following 6 months of gluten-free diet (GFD).

Methods

A prospective observational case control study of pediatric patients diagnosed with CD, with measurements of tissue transglutaminase IgA (TTG-IgA) and I-FABP levels at diagnosis and after 6 months of gluten free diet were compared to a control group of nonceliac patients.

Results

This study included 35 patients and 32 controls. The CD group had higher I-FABP levels at diagnosis compared with the control group (median 641.7 pg/mL versus 334 pg/mL; P < 0.05). I-FABP levels significantly differed between patients presenting with TTG-IgA level 3-10 times the upper limit of normal (ULN) compared with those presenting with values >10 times ULN (median 432.2 pg/mL versus 796.2 pg/mL; P < 0.05). Patients with CD had a significant decrease in median I-FABP levels after 6 months of GFD (median 268.2 pg/mL), paralleling a decrease in TTG-IgA and GFD adherence.

Conclusions

I-FABP levels are increased in patients with CD at diagnosis compared with controls and decrease significantly while patients adhere to GFD.

Strenuous 12-h run elevates circulating biomarkers of oxidative stress, inflammation and intestinal permeability in middle-aged amateur runners: A preliminary study

Given the solid evidence that prolonged strenuous exercise is a cause of metabolic stress, this study sought to determine whether a 12-h run would affect total oxidant status (TOS), total oxidant capacity (TOC), total antioxidant status (TAS), high-sensitivity C-reactive protein (hs-CRP) and the biomarkers of intestinal permeability (protein fatty acid-binding proteins (I-FABP) and zonulin) in middle-aged male subjects. Ten amateur long-distance runners (aged 52.0 ± 6.2 years, body height 176.9 ± 4.9 cm, body mass 73.9 ± 6.0 kg) were enrolled in the study. The venous blood samples were collected 1 hour before and right after the run and were analyzed for the levels of TAS, TOS/TOC, hs-CRP, I-FABP and zonulin. The post-run concentrations of TOS/TOC were significantly elevated (p < 0.001), but TAS changes were not significant. Pearson's correlation coefficients calculated for the post run values of TAS and TOS/TOC were statistically significant and negative (r = -0.750, p < 0.05). Significant increases in the concentrations of hs-CRP (p < 0.001), I-FABP (p < 0.05) and zonulin (p < 0.01) were noted. The results indicate that a strenuous 12-h run disturbs the prooxidant-antioxidant balance in middle-aged men, as well as promoting inflammation and impairing intestinal permeability.

Microbiota profiling in aging-associated inflammation and liver degeneration

BACKGROUND

The number of people above the age of 60 years is raising world-wide being associated with an increase in the prevalence of aging-associated impairments and even diseases. Recent studies suggest that aging is associated with alterations in bacterial endotoxin levels and that these changes may add to low-grade inflammation, the so-called 'inflammaging', and aging-associated liver degeneration. However, mechanisms involved, and especially, the interaction of intestinal microbiota and barrier in the development of aging-associated inflammation and liver degeneration have not been fully understood.

OBJECTIVE

The aim of the present study was to determine if intestinal microbiota composition changes with age and if these alterations are associated with changes of markers of intestinal barrier function and the development of inflammation and liver degeneration.

METHODS

Blood, liver, small and large intestinal tissue of male 2-, 15-, 24- and 30-months old C57BL/6 mice fed standard chow were obtained. Intestinal microbiota composition, expression levels of antimicrobial peptides in small intestine and markers of intestinal barrier function were measured. Furthermore, indices of liver damage, inflammation and expression levels of lipopolysaccharide binding protein (Lbp) as well as of toll-like receptors (Tlr) 1-9 in liver tissue were assessed.

RESULTS

Pairwise comparisons of the microbial community in the small intestine showed differences between 2- and 24-, 15- and 24-, as well as 15- and 30-months old animals while Shannon's diversity, species richness and evenness indexes did not differ in both small and large intestine, respectively, between age groups. Concentrations of nitric oxide were significantly lower in small intestine of 15-, 24- and 30-months old mice compared to 2-months old mice while mRNA expression of the antimicrobial peptides defensin alpha 1 and lysozyme 1 was unchanged. In contrast, in liver tissue, older age of animals was associated with increasing inflammation and the development of fibrosis in 24- and 30-months old mice. Numbers of inflammatory foci and neutrophils in livers of 24- and 30-months old mice were significantly higher compared to 2-months old mice. These alterations were also associated with higher endotoxin levels in plasma as well as an increased mRNA expression of Lbp and Tlr1, Tlr2, Tlr4, Tlr6 and Tlr9 in livers in older mice.

CONCLUSION

Despite no consistent and robust changes of microbiota composition in small and/or large intestine of mice of different age were observed, our data suggest that alterations of markers of intestinal barrier function in small intestine are associated with an induction of several Tlrs and beginning hepatic inflammation in older mice and increase with age.

Serum Zonulin Measured by Commercial Kit Fails to Correlate With Physiologic Measures of Altered Gut Permeability in First Degree Relatives of Crohn's Disease Patients

Intestinal epithelial cell tight junctions (TJs) contribute to the integrity of the intestinal barrier allowing for control of the physical barrier between external antigens or bacterial products and the internal environment. Zonula occludens-1 (ZO-1) is a protein that modulates intestinal TJs, and serum levels of ZO-1 has been suggested as a biomarker of disrupted barrier function in humans. Previous studies suggested that increased intestinal permeability was associated with evidence of TJ abnormalities. However, there is limited information on the serological measurement of ZO-1 and its relation to other tests of barrier function in healthy subjects. We investigated the correlation of serum ZO-1, with physiologic measures of intestinal permeability (as the ratio of the fractional excretion of lactulose-mannitol or LMR) in a cohort of 39 healthy FDRs of Crohn's disease (CD) patients. No significant correlation was found between LMR and ZO-1 levels (r2 = 0.004, P < 0.71), or intestinal fatty acid binding proteins (I-FABP) (r2 = 0.004, P < 0.71). In conclusion, our data show that ZO-1 and I-FABP are not a marker of gut permeability as defined by LMR.

Elevated Intestinal Inflammation in Preterm Infants With Signs and Symptoms of Gastroesophageal Reflux Disease

OBJECTIVES

Reflux is common in infancy; however, persistent signs and symptoms of gastrointestinal distress are often attributed to gastroesophageal reflux disease (GERD). In this pilot study, we aimed to characterize associations between signs and symptoms of suspected GERD and noninvasive markers of intestinal inflammation in preterm infants.

METHODS

We reviewed Electronic Medical Record (EMR) data to identify clinical signs and symptoms among case patients (n = 16). Controls (n = 16) were matched on gestational age. Univariate and multivariate regression analyses were used to compare fecal calprotectin and urinary intestinal fatty acid binding protein (I-FABP) levels between cases and controls.

RESULTS

We found no differences in baseline characteristics between cases and controls. In the multivariate regression analysis controlling for the proportion of mother's milk, cases had higher fecal calprotectin levels than controls, with no differences in I-FABP levels between cases and controls.

CONCLUSION

Our findings suggest that preterm infants with signs and symptoms of GERD have higher levels of intestinal inflammation as indicated by fecal calprotectin compared to their controls. Further studies are needed to evaluate the role of intestinal inflammation in signs and symptoms of gastrointestinal distress and whether fecal calprotectin might have predictive value in diagnosing GERD.

Endothelial activation is associated with intestinal epithelial injury, systemic inflammation and treatment regimen in children living with vertically acquired HIV-1 infection

BACKGROUND

Premature development of cardiovascular disease in children living with HIV-1 (CLWH) may be associated with compromised gut barrier function, microbial translocation, immune activation, systemic inflammation and endothelial activation. Biomarkers of these pathways may provide insights into pathogenesis of atherosclerotic disease in CLWH.

METHODS

This was a cross-sectional study of CLWH enrolled in the multicentre Early Pediatric Initiation-Canadian Child Cure Cohort (EPIC⁴ ) who were on antiretroviral therapy (ART) with undetectable viral load. Plasma biomarkers of intestinal epithelial injury [intestinal fatty acid binding protein-1 (IFABP)], systemic inflammation [tumour necrosis factor (TNF) and interleukin-6 (IL-6)] and endothelial activation [angiopoietin-2 (Ang2), soluble vascular endothelial growth factor-1 (sVEGFR1) and soluble endoglin (sEng)] were quantified by enzyme-linked immunosorbent assay. Correlation and factor analysis of biomarkers were used to examine associations between innate immune pathways.

RESULTS

Among 90 CLWH, 16% of Ang2, 15% of sVEGFR1 and 23% of sEng levels were elevated relative to healthy historic controls. Pairwise rank correlations between the three markers of endothelial activation were statistically significant (ρ = 0.69, ρ = 0.61 and ρ = 0.65, P < 0.001 for all correlations). An endothelial activation index, derived by factor analysis of the three endothelial biomarkers, was correlated with TNF (ρ = 0.47, P < 0.001), IL-6 (ρ = 0.60, P < 0.001) and intestinal fatty acid binding protein-1 (ρ = 0.67, P < 0.001). Current or past treatment with ritonavir-boosted lopinavir (LPV/r) was associated with endothelial activation (odds ratio = 5.0, 95% CI: 1.7-17, P = 0.0020).

CONCLUSIONS

Endothelial activation is prevalent in CLWH despite viral suppression with combination ART and is associated with intestinal epithelial injury, systemic inflammation and treatment with LPV/r.

Robust Iterative Stimulation with Self-Antigens Overcomes CD8+ T Cell Tolerance to Self- and Tumor Antigens

The immune system adapts to constitutive antigens to preserve self-tolerance, which is a major barrier for anti-tumor immunity. Antigen-specific reversal of tolerance constitutes a major goal to spur therapeutic applications. Here, we show that robust, iterative, systemic stimulation targeting tissue-specific antigens in the context of acute infections reverses established CD8⁺ T cell tolerance to self, including in T cells that survive negative selection. This strategy results in large numbers of circulating and resident memory self-specific CD8⁺ T cells that are widely distributed and can be co-opted to control established malignancies bearing self-antigen without concomitant autoimmunity. Targeted expansion of both self- and tumor neoantigen-specific T cells acts synergistically to boost anti-tumor immunity and elicits protection against aggressive melanoma. Our findings demonstrate that T cell tolerance can be re-adapted to responsiveness through robust antigenic exposure, generating self-specific CD8⁺ T cells that can be used for cancer treatment.

HIV-associated gut dysbiosis is independent of sexual practice and correlates with noncommunicable diseases

Loss of gut mucosal integrity and an aberrant gut microbiota are proposed mechanisms contributing to chronic inflammation and increased morbidity and mortality during antiretroviral-treated HIV disease. Sexual practice has recently been uncovered as a major source of microbiota variation, potentially confounding prior observations of gut microbiota alterations among persons with HIV (PWH). To overcome this and other confounding factors, we examine a well-powered subset of AGEhIV Cohort participants comprising antiretroviral-treated PWH and seronegative controls matched for age, body-mass index, sex, and sexual practice. We report significant gut microbiota differences in PWH regardless of sex and sexual practice including Gammaproteobacteria enrichment, Lachnospiraceae and Ruminococcaceae depletion, and decreased alpha diversity. Men who have sex with men (MSM) exhibit a distinct microbiota signature characterized by Prevotella enrichment and increased alpha diversity, which is linked with receptive anal intercourse in both males and females. Finally, the HIV-associated microbiota signature correlates with inflammatory markers including suPAR, nadir CD4 count, and prevalence of age-associated noncommunicable comorbidities.

Modelling the Impact of Chronic Cigarette Smoke Exposure in Obese Mice: Metabolic, Pulmonary, Intestinal, and Cardiac Issues

Unhealthy lifestyle choices, such as bad eating behaviors and cigarette smoking, have major detrimental impacts on health. However, the inter-relations between obesity and smoking are still not fully understood. We thus developed an experimental model of high-fat diet-fed obese C57BL/6 male mice chronically exposed to cigarette smoke. Our study evaluated for the first time the resulting effects of the combined exposure to unhealthy diet and cigarette smoke on several metabolic, pulmonary, intestinal, and cardiac parameters. We showed that the chronic exposure to cigarette smoke modified the pattern of body fat distribution in favor of the visceral depots in obese mice, impaired the respiratory function, triggered pulmonary inflammation and emphysema, and was associated with gut microbiota dysbiosis, cardiac hypertrophy and myocardial fibrosis.

Stunting Is Preceded by Intestinal Mucosal Damage and Microbiome Changes and Is Associated with Systemic Inflammation in a Cohort of Peruvian Infants

Stunting, defined as height-for-age Z score equal to or lower than -2, is associated with increased childhood mortality, cognitive impairment, and chronic diseases. The aim of the study was to investigate the relationship between linear growth, intestinal damage, and systemic inflammation in infants at risk of stunting. We followed up 78 infants aged 5-12 months living in rural areas of Peru for 6 months. Blood samples for biomarkers of intestinal damage (intestinal fatty-acid-binding protein [I-FABP] and zonulin) and systemic inflammation (interleukin-1β, interleukin-6, tumor necrosis factor α [TNF-α], soluble CD14, and lipopolysaccharide-binding protein [LBP]) and fecal samples for microbiome analysis were collected at baseline and closure of the study. The children's growth and health status were monitored through biweekly home visits by trained staff. Twenty-one percent of the children became stunted: compared with non-stunted children, they had worse nutritional parameters and higher levels of serum I-FABP at baseline. The likelihood of becoming stunted was strongly associated with an increase in sCD14 over time; LBP and TNF-α showed a trend toward increase in stunted children but not in controls. The fecal microbiota composition of stunted children had an increased beta diversity compared with that of healthy controls throughout the study. The relative abundance of Ruminococcus 1 and 2, Clostridium sensu stricto, and Collinsella increased in children becoming stunted but not in controls, whereas Providencia abundance decreased. In conclusion, stunting in our population was preceded by an increase in markers of enterocyte turnover and differences in the fecal microbiota and was associated with increasing levels of systemic inflammation markers.

Diagnostic accuracy of urinary intestinal fatty acid binding protein in detecting colorectal anastomotic leakage

BACKGROUND

Anastomotic leakage (AL) remains a severe complication following colorectal surgery, having a negative impact on both short- and long-term outcomes. Since timely detection could enable early intervention, there is a need for the development of novel and accurate, preferably, non-invasive markers. The aim of this study was to investigate whether urinary intestinal fatty acid binding protein (I-FABP) could serve as such a marker.

METHODS

This prospective multicenter cross-sectional phase two diagnostic study was conducted at four centers in the Netherlands between March 2015 and November 2016. Urine samples of 15 patients with confirmed colorectal AL and 19 patients without colorectal AL on postoperative day 3 were included. Urinary I-FABP levels were determined using enzyme-linked immunosorbent assays and adjusted for urinary creatinine to compensate for renal dysfunction.

RESULTS

Urinary I-FABP levels were significantly elevated in patients with confirmed AL compared to patients without AL on postoperative day 3 (median: 2.570 ng/ml vs 0.809 ng/ml, p = 0.006). The area under the receiver operating characteristics curve (AUROC) was 0.775, yielding a sensitivity of 80% and specificity of 74% at the optimal cutoff point (> 1.589 ng/ml). This difference remained significant after calculation of I-FABP/creatinine ratios (median: 0.564 ng/µmol vs. 0.158 ng/µmol, p = 0.040), with an AUROC of 0.709, sensitivity of 60% and specificity of 90% at the optimal cutoff point (> 0.469 ng/µmol).

CONCLUSIONS

Levels of urinary I-FABP and urinary I-FABP/creatinine were significantly elevated in patients with confirmed AL following colorectal surgery, suggesting their potential as a non-invasive biomarker for colorectal anastomotic leakage.

The Role of Gastrointestinal-Related Fatty Acid-Binding Proteins as Biomarkers in Gastrointestinal Diseases

The fatty acid-binding proteins play a major role in intracellular transportation of long-chain fatty acids. Nine fatty acid-binding proteins have been identified, with each having individual tissue-specific functions in addition to regulation of fatty acids. This review focuses on the three fatty acid-binding proteins found in the gastrointestinal tract and discusses their role as diagnostic or disease monitoring markers in neonatal necrotizing enterocolitis, acute mesenteric ischemia, celiac disease, and inflammatory bowel disease. Of these three fatty acid-binding proteins, intestinal fatty acid-binding protein is of the most interest due to its exclusive expression in the gastrointestinal tract. The elevation of intestinal fatty acid-binding protein in blood and urine reflects enterocyte damage, regardless of the underlying cause. The short half-life of intestinal fatty acid-binding protein also means it is a relatively sensitive marker. In contrast, there is currently less evidence to support liver fatty acid-binding protein and ileal bile acid-binding protein as sensitive biomarkers in these conditions. More extensive studies with specific endpoints are required to validate the roles of these fatty acid-binding proteins in gastrointestinal diseases.

Role for diet in normal gut barrier function: developing guidance within the framework of food-labeling regulations

A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria, and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the present gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the US Food and Drug Administration can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

Bacteria-related Events and the Immunological Response of Onset and Relapse Adult Crohn's Disease Patients

BACKGROUND AND AIMS

Crohn's disease [CD] is a chronic, systemic inflammatory disease characterised by periods of remission and flare-ups. It has been associated with a disturbed gastrointestinal barrier function, an increase in the transport of luminal contents into the tissue, and lower immune tolerance.

METHODS

Peripheral blood samples were collected from healthy controls and 33 adult active flare-up CD patients. We classified patients as onset or relapse flare-up subjects, according to the days of disease evolution. Plasma levels of lipopolysaccharide-binding protein [LBP], fatty acid-binding proteins [FABP], and antibodies against bacterial lysates, interferons [IFN] and interleukin-6 [IL6] were measured by enzyme-linked immunosorbent assay [ELISA] in each group of patients.

RESULTS

Onset CD patients had higher plasma levels of LBP [57.32 ± 38.86 vs 30.22 ± 9.80 µg/ml] and IFNα [1.25 ± 0.23 vs 0.95 ± 0.36 log10pg/ml] and lower levels of immunoglobulins G and A [IgG and IgA] antibodies against bacterial lysates than relapse CD patients. We also observed a subgroup of onset patients with the highest levels of LBP. In this subgroup, LBP correlated negatively with C-reactive protein [CRP]. Onset and relapse CD patients had similar levels of FABP6 and FABP2, though LBP and FABP6 correlated positively only in relapse patients. In relapse patients, anti-E coli IgG antibodies correlated positively with systemic IL6 and IFNα levels.

CONCLUSIONS

Our findings suggest that onset and relapse flare-ups in adult CD patients are related to different systemic immune-related bacterial events. Characterising these differences may provide insights into the aetiology of Crohn's disease, and would help in the selection of appropriate therapies.

Spondyloarthritis patients with and without intestinal symptoms - searching for discriminating biomarkers

Spondyloarthritis (SpA) is often complicated with subclinical gut inflammation. This study was aimed at searching for biomarkers discriminating SpA patients with and without intestinal symptoms. A group of 29 SpA patients and 33 healthy volunteers (control) were included in the study. Based on clinical evaluation, the patient cohort was subdivided into two groups: 1) SpA accompanied by various intestinal symptoms suggesting gut inflammation (group 2, n = 14) and 2) without such complications (group 1, n = 15). Serum concentrations of interleukins (IL) (IL-10, IL-17A/F, IL-22, IL-23), tumour necrosis factor (TNF), bone-homeostasis-related factors (osteoprotegerin – OPG and Dickkopf-1 – DKK-1), and the concentrations of selected gut inflammation-associated factors (intestinal fatty acid binding protein – iFABP, claudin 3 – CLDN3 and calprotectin) in samples of sera and/or urine or stool, respectively, were measured by specific ELISA. Serum concentrations of tested factors were similar in SpA patients and control. Faecal calprotectin level was higher in patients but did not discriminate between group 1 and 2. Compared to group 1, group 2 was characterized by elevated erythrocyte sedimentation rate (ESR), higher serum CLDN3 and DKK-1 levels. In SpA patients, serum DKK-1 concentrations correlated with systemic inflammation markers (R = 0.6, p < 0.01), while serum CLDN3 was found to be an independent risk factor (OR = 4.5, p = 0.021) for the occurrence of intestinal symptoms. We conclude that in SpA patients, up-regulated circulating levels of CLDN3 seem to be related to intestinal complication, while the quantity of circulating DKK-1 reflects the intensity of systemic inflammation.

Characterization of the Small Intestinal Lesion in Celiac Disease by Label-Free Quantitative Mass Spectrometry

Global characterization of tissue proteomes from small amounts of biopsy material has become feasible because of advances in mass spectrometry and bioinformatics tools. In celiac disease (CD), dietary gluten induces an immune response that is accompanied by pronounced remodeling of the small intestine. Removal of gluten from the diet abrogates the immune response, and the tissue architecture normalizes. In this study, differences in global protein expression of small intestinal biopsy specimens from CD patients were quantified by analyzing formalin-fixed, paraffin-embedded material using liquid chromatography-mass spectrometry and label-free protein quantitation. Protein expression was compared in biopsy specimens collected from the same patients before and after 1-year treatment with gluten-free diet (n = 10) or before and after 3-day gluten provocation (n = 4). Differential expression of proteins in particular from mature enterocytes, neutrophils, and plasma cells could distinguish untreated from treated CD mucosa, and Ig variable region IGHV5-51 expression was found to serve as a CD-specific marker of ongoing immune activation. In patients who had undergone gluten challenge, coordinated up-regulation of wound response proteins, including the CD autoantigen transglutaminase 2, was observed. Our study provides a global and unbiased assessment of antigen-driven changes in protein expression in the celiac intestinal mucosa.

Serum intestinal fatty acid-binding protein in the noninvasive diagnosis of celiac disease

Current diagnostic guidelines for celiac disease (CD) in pediatric patients require a duodenal biopsy if the IgA anti-tissue transglutaminase (tTG) is below 10x the upper limit of normal (ULN). Additional markers may enable a noninvasive diagnosis in this group. Serum intestinal-fatty acid-binding protein (I-FABP), a marker for intestinal epithelial damage, could be useful in this respect. A total of 95 children with a clinical suspicion of CD and tTG 1-10x ULN were investigated. All had a duodenal biopsy and analysis of serum I-FABP. A control group of 161 children with familial short stature and normal tTG was included. I-FABP levels in the 71 patients with tTG 1-10x ULN and biopsy-proven CD (median 725 pg/mL) were not significantly different (p = 0.13) from the levels in the 24 patients with a tTG 1-10x ULN but a normal biopsy (median 497 pg/mL). However, when combining tTG and I-FABP levels, 11/24 patients could have been diagnosed noninvasively if tTG is ≥ 50 U/mL and I-FABP ≥880 pg/mL or in 12/19 patients if tTG is ≥ 60 U/mL and I-FABP ≥ 620 pg/mL. Therefore, addition of I-FABP to the diagnostic procedure of CD may provide a noninvasive diagnosis in patients with a tTG ≥ 50 U/mL.

The acute effects on duodenal gene expression in healthy men following consumption of a low-fat meal enriched with theobromine or fat

Increasing apoA-I synthesis may improve HDL functionality and lower CVD risk. As theobromine and fat increase fasting apoA-I concentrations, and the intestine is involved in apoA-I production, the acute effects of both were studied on duodenal gene transcription to better understand underlying mechanisms. In this crossover study, 8 healthy men received once a low fat (LF) meal, a LF meal plus theobromine (850 mg), or a high fat (HF) meal. Five hours after meal intake duodenal biopsies were taken for microarray analysis. Theobromine and HF consumption did not change duodenal apoA-I expression. Theobromine did not change gene expression related to lipid and cholesterol metabolism, whereas those related to glycogen/glucose breakdown were downregulated. HF consumption increased gene expression related to lipid and cholesterol uptake and transport, and to glucose storage, while it decreased those related to glucose uptake. Furthermore, genes related to inflammation were upregulated, but inflammation markers in plasma were not changed. In healthy men, acute theobromine and fat consumption did not change duodenal apoA-I mRNA, but inhibited expression of genes related to glucose metabolism. Furthermore, HF intake activated in the duodenum expression of genes related to lipid and cholesterol metabolism and to inflammation.

Intestinal Damage and Inflammatory Biomarkers in Human Immunodeficiency Virus (HIV)-Exposed and HIV-Infected Zimbabwean Infants

Background

Disease progression is rapid in human immunodeficiency virus (HIV)–infected infants. Whether intestinal damage and inflammation underlie mortality is unknown.

Methods

We measured plasma intestinal fatty acid binding protein (I-FABP), soluble CD14 (sCD14), interleukin 6 (IL-6), and C-reactive protein (CRP) at 6 weeks and 6 months of age in 272 HIV-infected infants who either died (cases) or survived (controls), and in 194 HIV-exposed uninfected (HEU) and 197 HIV-unexposed infants. We estimated multivariable odds ratios for mortality and postnatal HIV transmission for each biomarker using logistic regression.

Results

At 6 weeks, HIV-infected infants had higher sCD14 and IL-6 but lower I-FABP than HIV-exposed and HIV-unexposed infants (P < .001). CRP was higher in HIV-exposed than HIV-unexposed infants (P = .02). At 6 months, HIV-infected infants had highest sCD14, IL-6, and CRP concentrations (P < .001) and marginally higher I-FABP than other groups (P = .07). CRP remained higher in HIV-exposed vs HIV-unexposed infants (P = .04). No biomarker was associated with mortality in HIV-infected infants, or with odds of breast-milk HIV transmission in HIV-exposed infants.

Conclusions

HIV-infected infants have elevated inflammatory markers by 6 weeks of age, which increase over time. In contrast to adults and older children, inflammatory biomarkers were not associated with mortality. HEU infants have higher inflammation than HIV-unexposed infants until at least 6 months, which may contribute to poor health outcomes.

Progress towards non-invasive diagnosis and follow-up of celiac disease in children; a prospective multicentre study to the usefulness of plasma I-FABP

This prospective study investigates whether measurement of plasma intestinal-fatty acid binding protein (I-FABP), a sensitive marker for small intestinal epithelial damage, improves non-invasive diagnosing of celiac disease (CD), and whether I-FABP levels are useful to evaluate mucosal healing in patients on a gluten-free diet (GFD). Ninety children with elevated tTG-IgA titres and HLA-DQ2/DQ8 positivity were included (study group). Duodenal biopsies were taken, except in those fulfilling the ESPGHAN criteria. Plasma I-FABP levels and tTG-IgA titres were assessed sequentially during six months of follow-up. Eighty children with normal tTG-IgA titres served as control group. In 61/90 (67.8%) of the children in the study group an increased I-FABP level was found; in all these children CD diagnosis was confirmed. Interestingly, in 14/30 (46.7%) children with slightly elevated tTG-IgA titres (<10x upper limit of normal), an increased I-FABP level was found. In all these children the diagnosis of CD was confirmed histologically. After gluten elimination for six weeks I-FABP levels had decreased towards levels in the control group. Measurement of plasma I-FABP, in addition to tTG-IgA, EMA-IgA and HLAtyping, enables non-invasive diagnosing of CD in a substantial number of children, and might therefore be of value in the diagnostic approach of CD.

Intestinal barrier integrity and function in infants with cholestasis

Background/Aims

The safety of the human body is maintained by effective monitoring of the mucosal surface integrity and protection against potentially harmful compounds. This function of the gut called intestinal barrier function can be affected by cholestasis and the absence of bile in the intestinal lumen. We aimed to determine whether the gut barrier integrity is impaired in infants with cholestasis by evaluation of the intestinal fatty acid binding proteins (I-FABP) and ileal bile acid binding protein (I-BABP) as markers of intestinal epithelial cell damage and plasma D-lactate level as a marker of gut wall permeability.

Methods

This case-control study included 53 infants with cholestasis and 29 controls. Serum levels of I-FABP, I-BABP, and D-lactate were measured in all subjects.

Results

Both groups of patients with neonatal hepatitis and biliary atresia showed significantly higher levels of I-FABP and I-BABP than the controls. There were no differences in the serum D-lactate level between the cases and controls. There was no difference between the two groups of patients (I and II) regarding any of the parameters studied. No significant correlations between serum levels of I-FABP, I-BABP, or D-lactate and total or direct bilirubin levels were found in the cholestatic infants.

Conclusions

The intestinal epithelial barrier integrity is breached nearly in all parts of the intestine in infants with cholestasis. Further research is recommended to determine the impact of this finding on the management of these infants. The relationship between physical intestinal barrier damage and its functional failure remains subject for further research.

Intestinal cell damage and systemic immune activation in individuals reporting sensitivity to wheat in the absence of coeliac disease

OBJECTIVE

Wheat gluten and related proteins can trigger an autoimmune enteropathy, known as coeliac disease, in people with genetic susceptibility. However, some individuals experience a range of symptoms in response to wheat ingestion, without the characteristic serological or histological evidence of coeliac disease. The aetiology and mechanism of these symptoms are unknown, and no biomarkers have been identified. We aimed to determine if sensitivity to wheat in the absence of coeliac disease is associated with systemic immune activation that may be linked to an enteropathy.

DESIGN

Study participants included individuals who reported symptoms in response to wheat intake and in whom coeliac disease and wheat allergy were ruled out, patients with coeliac disease and healthy controls. Sera were analysed for markers of intestinal cell damage and systemic immune response to microbial components.

RESULTS

Individuals with wheat sensitivity had significantly increased serum levels of soluble CD14 and lipopolysaccharide (LPS)-binding protein, as well as antibody reactivity to bacterial LPS and flagellin. Circulating levels of fatty acid-binding protein 2 (FABP2), a marker of intestinal epithelial cell damage, were significantly elevated in the affected individuals and correlated with the immune responses to microbial products. There was a significant change towards normalisation of the levels of FABP2 and immune activation markers in a subgroup of individuals with wheat sensitivity who observed a diet excluding wheat and related cereals.

CONCLUSIONS

These findings reveal a state of systemic immune activation in conjunction with a compromised intestinal epithelium affecting a subset of individuals who experience sensitivity to wheat in the absence of coeliac disease.

Transition of intestinal fatty acid-binding protein on hypothermic circulatory arrest with cardiopulmonary bypass

Introduction:

Intestinal fatty acid-binding protein (I-FABP) is increasingly employed as a highly specific marker of intestinal necrosis. However, the value of this marker associated with cardiovascular surgery with hypothermic circulatory arrest is unclear. The aim of this study was to measure serum I-FABP levels and provide the transition of I-FABP levels with hypothermic circulatory arrest to help in the management of intestinal perfusion.

Methods:

From August 2011 to September 2013, 33 consecutive patients who had aortic arch surgery with hypothermic circulatory arrest or heart valve surgery performed were enrolled in the study. Twenty patients had aortic surgery with hypothermic (23-29°C) circulatory arrest and 13 patients had heart valve surgery with cardiopulmonary bypass (33°C).

Results:

I-FABP levels increased, both in patients undergoing aortic surgery with hypothermic circulatory arrest and heart valve surgery with cardiopulmonary bypass, reaching peak levels shortly after the administration of protamine. I-FABP levels in patients with aortic surgery were significantly higher with circulatory arrest. They reached peak levels immediately after recirculation and there was a significant drop at the end of surgery (p<0.001). I-FABP levels in heart valve surgery were gradually increased, with the highest at the administration of protamine; they gradually decreased. Peak I-FABP levels were significantly higher in patients undergoing aortic surgery with hypothermic circulatory arrest than in patients with heart valve surgery. However, no postoperative reperfusion injury occurred in the intestinal tract due to the use of hypothermic organ protection.

Conclusion:

Plasma I-FABP monitoring could be a valuable method for finding an intestinal ischemia in patients with cardiovascular surgery.

Gut epithelial barrier markers in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is now being recognized as an additional contributing factor to the pathogenesis of obesity-related comorbidities. At the same time, there is now increasing evidence to suggest that intestinal wall permeability plays a role in the development of metabolic syndrome. In the present study, circulating zonulin and fatty acid binding protein (I-FABP) were measured in association with metabolic, hepatic, and inflammatory parameters.

RESULTS

Compared with controls, plasma I-FABP levels were significantly higher in patients with OSA (571 pg/mL [IQR 290-950] vs 396 pg/mL [IQR 234-559], p = 0.04). Zonulin levels were similar between groups. Significant relationships were observed between zonulin levels and waist circumference (p < 0.05), glucose (p < 0.05), and insulin (p < 0.05). In addition, in the OSA group, zonulin levels correlated negatively with the mean nocturnal oxygenation saturation (p < 0.05) and positively with total cholesterol (p < 0.05), alanine aminotransferase (ALT) (p < 0.005), aminotransferase (AST) (p < 0.01), gamma glutamyltransferase (GGT) (p < 0.005), and high-sensitivity C-reactive protein (hs-CRP) (p < 0.05). Multivariate analysis showed that associations between zonulin and ALT, AST, and hs-CRP were attenuated, but not eliminated, after adjustment for other variables.

CONCLUSIONS

The results of this study suggest that OSA is a risk factor for intestinal damage, regardless of metabolic profile, and that intestinal permeability might be a possible contributor to nonalcoholic fatty liver disease in patients with OSA.

Assessment of Environmental Enteric Dysfunction in the SHINE Trial: Methods and Challenges

Environmental enteric dysfunction (EED) is a virtually ubiquitous, but poorly defined, disorder of the small intestine among people living in conditions of poverty, which begins early in infancy and persists. EED is characterized by altered gut structure and function, leading to reduced absorptive surface area and impaired intestinal barrier function. It is hypothesized that recurrent exposure to fecal pathogens and changes in the composition of the intestinal microbiota initiate this process, which leads to a self-perpetuating cycle of pathology. We view EED as a primary gut disorder that drives chronic systemic inflammation, leading to growth hormone resistance and impaired linear growth. There is currently no accepted case definition or gold-standard biomarker of EED, making field studies challenging. The Sanitation Hygiene Infant Nutrition Efficacy (SHINE) trial in Zimbabwe is evaluating the independent and combined effects of a package of infant feeding and/or water, sanitation, and hygiene interventions on stunting and anemia. SHINE therefore provides an opportunity to longitudinally evaluate EED in a well-characterized cohort of infants, using a panel of biomarkers along the hypothesized causal pathway. Our aims are to describe the evolution of EED during infancy, ascertain its contribution to stunting, and investigate the impact of the randomized interventions on the EED pathway. In this article, we describe current concepts of EED, challenges in defining the condition, and our approach to evaluating EED in the SHINE trial.

Intestinal barrier analysis by assessment of mucins, tight junctions, and α-defensins in healthy C57BL/6J and BALB/cJ mice

The intestinal barrier is gaining increasing attention because it is related to intestinal homeostasis and disease. Different parameters have been used in the past to assess intestinal barrier functions in experimental studies; however most of them are poorly defined in healthy mice. Here, we compared a number of barrier markers in healthy mice, established normal values and correlations. In 48 mice (24 C57BL/6J, 24 BALB/cJ background), we measured mucus thickness, and expression of mucin-2, α-defensin-1 and -4, zonula occludens-1, occludin, junctional adhesion molecule-A, claudin-1, 2 and -5. We also analyzed claudin-3 and fatty acid binding protein-2 in urine and plasma, respectively. A higher expression of mucin-2 protein was found in the colon compared to the ileum. In contrast, the α-defensins-1 and -4 were expressed almost exclusively in the ileum. The protein expression of the tight junction molecules claudin-1, occludin and zonula occludens-1 did not differ between colon and ileum, although some differences occurred at the mRNA level. No age- or gender-related differences were found. Differences between C57BL/6J and BALB/cJ mice were found for α-defensin-1 and -4 mRNA expression, and for urine and plasma marker concentrations. The α-defensin-1 mRNA correlated with claudin-5 mRNA, whereas α-defensin-4 mRNA correlated with claudin-3 concentrations in urine. In conclusion, we identified a number of murine intestinal barrier markers requiring tissue analyses or measurable in urine or plasma. We provide normal values for these markers in mice of different genetic background. Such data might be helpful for future animal studies in which the intestinal barrier is of interest.

Plasma intestinal fatty acid-binding protein fails to predict endoscopic disease activity in inflammatory bowel disease patients

BACKGROUND

Monitoring disease activity in inflammatory bowel disease (IBD) is of major importance to prevent long-term complications. Intestinal fatty acid-binding protein (I-FABP) has been identified as a marker for intestinal damage and correlates with the degree of inflammation. The aim of the present study was to evaluate whether I-FABP can predict active disease or remission in Crohn's disease (CD) and ulcerative colitis (UC) in a real-life IBD cohort.

METHODS

In total, 70 patients with endoscopic disease activity available and 194 patients with disease activity on the basis of a stringent combi-score of clinical activity index, C-reactive protein, and fecal calprotectin were included. Plasma I-FABP was compared between patients with active disease and remission. In a small subgroup of CD patients, follow-up samples were analyzed.

RESULTS

In CD (139.2 vs. 119.2 pg/ml; P=0.37) and UC (107.8 vs. 151.8 pg/ml; P=0.33), the median I-FABP did not differ in endoscopic active disease versus remission. In UC patients with active disease on the basis of the combi-score, the median I-FABP (106.8 vs. 172.0 pg/ml; P=0.03) was significantly lower than in patients in remission, but not in CD (145.5 vs. 157.5 pg/ml; P=0.29). Neither disease location in CD nor extent of disease in UC influenced I-FABP significantly. I-FABP was not different (P=0.78) in CD patients with a change in disease activity over time.

CONCLUSION

Plasma I-FABP did not differ between endoscopic active disease and remission in both CD and UC. I-FABP was lower in active UC but not CD on the basis of the combi-score. On the basis of these findings, I-FABP has no potential as a novel noninvasive biomarker for disease activity in IBD.

Serum I-FABP Detects Gluten Responsiveness in Adult Celiac Disease Patients on a Short-Term Gluten Challenge

OBJECTIVES

Response to gluten challenge (GC) is a key feature in diagnostic algorithms and research trials in celiac disease (CD). Currently, autoantibody titers, late responders to GC, and invasive duodenal biopsies are used to evaluate gluten responsiveness. This study investigated the accuracy of serum intestinal-fatty acid binding protein (I-FABP), a marker for intestinal epithelial damage, to predict intestinal damage during GC in patients with CD.

METHODS

Twenty adult CD patients in remission underwent a two-week GC with 3 or 7.5 g of gluten daily. Study visits occurred at day -14, 0, 3, 7, 14, and 28. Serum I-FABP, antibodies to tissue transglutaminase (tTG-IgA), deamidated gliadin peptides (IgA-DGP), and anti-actin (AAA-IgA) were assessed at each visit. Villous-height to crypt-depth ratio (Vh:Cd) and intraepithelial lymphocyte (IEL) count were evaluated at day -14, 3, and 14. Forty-three CD-serology negative individuals were included to compare serum I-FABP levels in CD patients on a gluten-free diet (GFD) with those in healthy subjects.

RESULTS

Serum I-FABP levels increased significantly during a two-week GC. In contrast, the most pronounced autoantibody increase was found at day 28, when patients had already returned to a GFD for two weeks. IgA-AAA titers were only significantly elevated at day 28. I-FABP levels and IEL count correlated at baseline (r=0.458, P=0.042) and at day 14 (r=0.654, P=0.002) of GC. Neither gluten dose nor time on a GFD influenced I-FABP change during GC.

CONCLUSIONS

Serum I-FABP levels increased significantly during a two-week GC in adult CD patients and correlated with IEL count. The data suggest that serum I-FABP is an early marker of gluten-induced enteropathy in celiac patients and may be of use in both clinical and research settings.

Novel diagnostic techniques for celiac disease

The diagnosis of celiac disease has long been based on the demonstration of gluten-induced small-bowel mucosal damage. However, due to the constantly increasing disease prevalence and limitations in the histology-based criteria there is a pressure towards more serology-based diagnostics. The serological tools are being improved and new non-invasive methods are being developed, but the constantly refined endoscopic and histologic techniques may still prove helpful. Moreover, growing understanding of the disease pathogenesis has led researchers to suggest completely novel approaches to celiac disease diagnostics regardless of disease activity. In this review, we will elucidate the most recent development and possible future innovations in the diagnostic techniques for celiac disease.

Systemic inflammation and liver damage in HIV/hepatitis C virus coinfection

OBJECTIVES

Chronic hepatitis C virus (HCV) and HIV viral infections are characterized by systemic inflammation. Yet the relative levels, drivers and correlates of inflammation in these settings are not well defined.

METHODS

Seventy-nine HIV-infected patients who had been receiving antiretroviral therapy (ART) for more than 2 years and who had suppressed plasma HIV levels (< 50 HIV-1 RNA copies/mL) were included in the study. Two patient groups, HCV-positive/HIV-positive and HCV-negative/HIV-positive, and a control group comprised of healthy volunteers (n = 20) were examined. Markers of systemic inflammation [interleukin (IL)-6, interferon gamma-induced protein (IP)-10, soluble tumour necrosis factor receptor-I (sTNF-RI) and sTNF-RII], monocyte/macrophage activation [soluble CD163 (sCD163), soluble CD14 and neopterin], intestinal epithelial barrier loss [intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide (LPS)] and coagulation (d-dimers) were analysed. CD4 naïve T cells and CD4 recent thymic emigrants (RTEs) were enumerated.

RESULTS

Plasma levels of IP-10, neopterin and sCD163 were higher in HCV/HIV coinfection than in HIV monoinfection and were positively correlated with indices of hepatic damage [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and the AST to platelet ratio index (APRI)]. Levels of I-FABP were comparably increased in HIV monoinfection and HIV/HCV coinfection but LPS concentrations were highest in HCV/HIV coinfection, suggesting impaired hepatic clearance of LPS. Plasma HCV levels were not related to any inflammatory indices except sCD163. In coinfected subjects, a previously recognized relationship of CD4 naïve T-cell and RTE counts to hepatocellular injury was defined more mechanistically by an inverse relationship to sCD163.

CONCLUSIONS

Hepatocellular injury in HCV/HIV coinfection is linked to elevated levels of certain inflammatory cytokines and an apparent failure to clear systemically translocated microbial products. A related decrease in CD4 naïve T cells and RTEs also merits further exploration.

Clinical significance of FABP2 expression in newborns with necrotizing enterocolitis

BACKGROUND

This meta-analysis aimed to determine the role of human fatty acid binding protein 2 (FABP2) expression in the diagnosis of necrotizing enterocolitis (NEC) of newborns.

DATA SOURCES

Eligible studies for further statistical analysis were identified from various databases including PubMed, Expert Medica Database, Web of Science, Cochrane Library, Google Scholar, China BioMedicine and China National Knowledge Infrastructure. Random effects model was used, and summary standardized mean difference (SMD) with its 95% confidence interval (CI) was calculated to assess the association of FABP2 expression and NEC.

RESULTS

Ten articles which included 572 infants (262 infants with NEC and 310 healthy controls) were included in the current meta-analysis. FABP2 showed a positive relationship with NEC of newborns (SMD=2.88, 95% CI=2.09-3.67, P<0.001). And FABP2 expression was higher in patients with advanced stage of NEC (stage III or stage II+III) than in those with early stage of NEC (stage I) (SMD=-0.48, 95% CI=-0.87 to -0.09, P=0.015). Ethnicity-stratified analysis yielded significantly different estimates with a high FABP2 expression in NEC in both Caucasians (SMD=3.16, 95% CI=1.90-4.43, P<0.001) and Asians (SMD=2.57, 95% CI=1.50-3.64, P<0.001). Sample-based subgroup analysis showed that FABP2 expression was positively correlated with neonatal NEC in both urinary- and blood-sample subgroups (all P<0.05).

CONCLUSION

The results prove that the high FABP2 expression is related to the damage to intestinal cells, which may be a possible early detection marker identifying neonatal NEC.

Life and death at the mucosal-luminal interface: New perspectives on human intestinal ischemia-reperfusion

Intestinal ischemia is a frequently observed phenomenon. Morbidity and mortality rates are extraordinarily high and did not improve over the past decades. This is in part attributable to limited knowledge on the pathophysiology of intestinal ischemia-reperfusion (IR) in man, the paucity in preventive and/or therapeutic options and the lack of early diagnostic markers for intestinal ischemia. To improve our knowledge and solve clinically important questions regarding intestinal IR, we developed a human experimental intestinal IR model. With this model, we were able to gain insight into the mechanisms that allow the human gut to withstand short periods of IR without the development of severe inflammatory responses. The purpose of this review is to overview the most relevant recent advances in our understanding of the pathophysiology of human intestinal IR, as well as the (potential) future clinical implications.

I-FABP and L-FABP are early markers for abdominal injury with limited prognostic value for secondary organ failures in the post-traumatic course

BACKGROUND

Trauma patients sustaining abdominal trauma exhibit high risk of organ failure and/or sepsis aggravating morbidity and mortality during the post-traumatic course. The present study re-evaluates L- and I-FABPs (small fatty acid binding proteins) as early biomarkers for abdominal injury (AI) in a large cohort of patients and analyzes their potential as indicators of specific organ failure and their association with sepsis and/or mortality in the post-traumatic course.

METHODS

This prospective study included 134 multiply traumatized patients (ISS≥16). Fifty-nine had AI (abbreviated AI Scale, AISAbd≥3) and 75 had no AI (noAI). Twenty healthy volunteers served as controls. Plasma I- and L-FABP levels were measured at the admittance to the emergency room (d0) and up to 10 days daily (d1-d10) using ELISA. Sepsis, organ failure, multiple organ failure (MOF) and mortality were assessed.

RESULTS

Median L- and I-FABP in the AI-group [258 (IQR=71-500) ng/mL and 328 (IQR=148-640) pg/mL, respectively] were higher compared to noAI-group [30 (IQR=18-50) ng/mL and 60 (IQR=40-202) pg/mL, p>0.05] on d0. Sensitivity and specificity to detect AI were 80% and 75% for L-FABP, 78% and 62% for I-FABP. Both FABPs decline with the post-traumatic course to control levels. On d0 and d1, FABPs correlate with the Sepsis-related Organ Failure Assessment (SOFA) score of the following day (d0: ρ:0.33, ρ:0.46, d1: ρ:0.48, ρ:0.35). No other correlations were found. Eight percent of all patients developed sepsis, 18% pneumonia, 4% urinary tract infection, 3% acute kidney failure and one MOF. FABPs correlated neither with Simplifed Acute Physiology Score (SAPS)-II nor to sepsis. All patients with acute kidney failure demonstrated enhanced L-FAPB levels before the increase of serum creatinine levels.

CONCLUSIONS

Our results confirm the potential of L- and I-FABP to indicate abdominal injuries initially after trauma. Except L-FABP as indicator of acute kidney failure both FABPs have to be further evaluated as predictors for other organ failures, sepsis and/or mortality.

Evidence for a Cystic Fibrosis Enteropathy

Background

Previous studies have suggested the existence of enteropathy in cystic fibrosis (CF), which may contribute to intestinal function impairment, a poor nutritional status and decline in lung function. This study evaluated enterocyte damage and intestinal inflammation in CF and studied its associations with nutritional status, CF-related morbidities such as impaired lung function and diabetes, and medication use.

Methods

Sixty-eight CF patients and 107 controls were studied. Levels of serum intestinal-fatty acid binding protein (I-FABP), a specific marker for enterocyte damage, were retrospectively determined. The faecal intestinal inflammation marker calprotectin was prospectively studied. Nutritional status, lung function (FEV1), exocrine pancreatic insufficiency (EPI), CF-related diabetes (CFRD) and use of proton pump inhibitors (PPI) were obtained from the medical charts.

Results

Serum I-FABP levels were elevated in CF patients as compared with controls (p<0.001), and correlated negatively with FEV1 predicted value in children (r-.734, p<0.05). Faecal calprotectin level was elevated in 93% of CF patients, and correlated negatively with FEV1 predicted value in adults (r-.484, p<0.05). No correlation was found between calprotectin levels in faeces and sputum. Faecal calprotectin level was significantly associated with the presence of CFRD, EPI, and PPI use.

Conclusion

This study demonstrated enterocyte damage and intestinal inflammation in CF patients, and provides evidence for an inverse correlation between enteropathy and lung function. The presented associations of enteropathy with important CF-related morbidities further emphasize the clinical relevance.

Expression Pattern of Fatty Acid Binding Proteins in Celiac Disease Enteropathy

Celiac disease (CD) is an immune-mediated enteropathy that develops in genetically susceptible individuals following exposure to dietary gluten. Severe changes at the intestinal mucosa observed in untreated CD patients are linked to changes in the level and in the pattern of expression of different genes. Fully differentiated epithelial cells express two isoforms of fatty acid binding proteins (FABPs): intestinal and liver, IFABP and LFABP, respectively. These proteins bind and transport long chain fatty acids and also have other important biological roles in signaling pathways, particularly those related to PPARγ and inflammatory processes. Herein, we analyze the serum levels of IFABP and characterize the expression of both FABPs at protein and mRNA level in small intestinal mucosa in severe enteropathy and normal tissue. As a result, we observed higher levels of circulating IFABP in untreated CD patients compared with controls and patients on gluten-free diet. In duodenal mucosa a differential FABPs expression pattern was observed with a reduction in mRNA levels compared to controls explained by the epithelium loss in severe enteropathy. In conclusion, we report changes in FABPs' expression pattern in severe enteropathy. Consequently, there might be alterations in lipid metabolism and the inflammatory process in the small intestinal mucosa.

Prediction of Gut Wall Integrity Loss in Viral Gastroenteritis by Non-Invasive Marker

BACKGROUND:

Intestinal fatty acid binding proteins (I-FABPs) are mainly expressed in the intestinal villi, which are the initial site of destruction in viral gastroenteritis.

AIM:

This study was designed to assess serum I-FABPs as a predictor of gut wall integrity loss in viral gastroenteritis.

PATIENTS AND METHODS:

This case-control cross-sectional study was conducted on 93 cases of acute viral gastroenteritis. Twenty-eight healthy children matching in age were recruited as control group. Serum I-FABPs were measured using ELISA technique. Viral detection and typing were done by PCR for adenovirus, and by Reverse transcriptase PCR for rotavirus, astrovirus and norovirus.

RESULTS:

Serum I-FABPs level was significantly higher in the cases compared to the controls and was also higher in the 46 rotavirus gastroenteritis cases compared to other viral gastroenteritis cases. Serum I- FABPs level was significantly higher in severely dehydrated cases as compared to mildly dehydrated ones (P=0.037).

CONCLUSION:

Serum I-FABPs could be used as an early and sensitive predictor marker of gut wall integrity loss in children with viral gastroenteritis and its level can indicate case severity.

Serum markers in the clinical management of celiac disease

The advent of highly reliable noninvasive celiac diagnostic tests has transformed the field of celiac disease, from diagnosis, to evaluation of epidemiology, to clinical and translational research. Serologic tests in their modern forms are highly sensitive and specific for diagnosis, allowing for consideration of avoidance of diagnostic intestinal biopsy in some settings. On the other hand, as predictors of intestinal damage and for use in monitoring disease activity, currently available noninvasive tests have been disappointing. Serologic tests, while a measure of disease activity, do not correlate well with histology or symptomatology, and it is unclear if they predict long-term risk. Additionally, while the many clinically available tests have improved accessibility, they can have widely different cutoff levels and overall performance, making the comparison of levels in individual patients over time and across populations quite difficult. In the future, we can expect to see improvement in the currently available serologic tests including tissue transglutaminase and deamidated gliadin peptide with expansion of the dynamic range of the tests, and the celiac care community should push for a standardization of assays that would simplify research and patient care. Additionally, current serologic tests are measures of the adaptive immune response in celiac disease but do not directly measure intestinal inflammation. Promising work on intestinal fatty acid-binding protein and other assays which directly measure intestinal damage may complement traditional serologic tests and further improve our ability to noninvasively diagnose and monitor celiac disease. The coming years hold promise for the continuing evolution of serum-based tests in celiac disease with the possibility of substantial improvement of patient care and clinical research.