Plasma citrulline as surrogate marker of intestinal inflammation in pediatric and adolescent with Crohn's disease: preliminary report

Circulating Apolipoprotein B-48 as a Biomarker of Parenteral Nutrition Dependence in Adult Patients with Short Bowel Syndrome

Short bowel syndrome (SBS) is a rare but serious condition that may lead to chronic intestinal failure. Citrulline concentrations are currently used to reflect the residual intestinal mass in patients with SBS, although this method has several limitations. In a cohort of patients with SBS, we quantified apolipoprotein B-48 (ApoB-48), which is exclusively synthesized by enterocytes and secreted associated with dietary lipids and investigated the relationship between ApoB-48 and clinical and biological data as well as PN dependence. A total of 51 adult patients were included, 36 of whom were PN-dependent. We found a robust positive correlation between circulating ApoB-48 and residual small bowel length, which was also found in the subgroup of patients with jejunocolic anastomosis. Fasting ApoB-48 levels were significantly lower in PN-dependent patients than in PN-weaned patients and negatively correlated with parenteral nutrition dependence. Our results suggest that ApoB-48 could be proposed as a marker of intestinal absorptive function and could be an interesting follow-up marker in patients with SBS.

Relevance of biomarkers indicating gut damage and microbial translocation in people living with HIV

The intestinal barrier has the daunting task of allowing nutrient absorption while limiting the entry of microbial products into the systemic circulation. HIV infection disrupts the intestinal barrier and increases intestinal permeability, leading to microbial product translocation. Convergent evidence has shown that gut damage and an enhanced level of microbial translocation contribute to the enhanced immune activation, the risk of non-AIDS comorbidity, and mortality in people living with HIV (PLWH). Gut biopsy procedures are invasive, and are not appropriate or feasible in large populations, even though they are the gold standard for intestinal barrier investigation. Thus, validated biomarkers that measure the degree of intestinal barrier damage and microbial translocation are needed in PLWH. Hematological biomarkers represent an objective indication of specific medical conditions and/or their severity, and should be able to be measured accurately and reproducibly via easily available and standardized blood tests. Several plasma biomarkers of intestinal damage, i.e., intestinal fatty acid-binding protein (I-FABP), zonulin, and regenerating islet-derived protein-3α (REG3α), and biomarkers of microbial translocation, such as lipopolysaccharide (LPS) and (1,3)-β-D-Glucan (BDG) have been used as markers of risk for developing non-AIDS comorbidities in cross sectional analyses and clinical trials, including those aiming at repair of gut damage. In this review, we critically discuss the value of different biomarkers for the estimation of gut permeability levels, paving the way towards developing validated diagnostic and therapeutic strategies to repair gut epithelial damage and to improve overall disease outcomes in PLWH.

The Association of Plasma-Free Branched-Chain Amino Acids with Disease Related Parameters in Ulcerative Colitis

Branched-chain amino acids (BCAAs) are involved in immune system's metabolic pathways and play fundamental role in gut health. Our aim was to assess BCAA plasma levels in patients with ulcerative colitis (UC) and associations of plasma BCAAs with disease-related parameters. This was a case-control study in adult patients with UC and BMI-matched controls. A total of 150 volunteers were screened between May 2016 and June 2017; 43 patients and 34 healthy controls were enrolled. Medical and dietary history (3 × 24 h recalls, MedDiet score), anthropometric measurements, blood and fecal samples were collected. We measured BCAAs in plasma with gas chromatography-mass spectrometry. In patients, fecal calprotectin, lactoferrin, lysozyme and defensin were quantified. Dietary pattern was similar in patients and controls. Plasma-free BCAA profiles did not differ between groups. Regression analysis showed that i) valine was inversely associated with calprotectin (p = 0.007) and ii) isoleucine with age (p = 0.031), after adjusting for age, sex, PMS and smoking. Leucine was negatively associated with age (p = 0.015) after adjusting for age, sex and PMS, but this association vanished when smoking was introduced. No correlation was observed between total BCAAs with any of the parameters. Plasma-free valine is negatively associated with calprotectin in patients with UC.

A Citrulline-Based Translational Population System Toxicology Model for Gastrointestinal-Related Adverse Events Associated With Anticancer Treatments

Gastrointestinal (GI)-related adverse events (AEs) are commonly observed in the clinic during cancer treatments. Citrulline is a potentially translatable biomarker of GI AEs. In this study, irinotecan-induced citrulline changes were studied for a range of doses and schedules in rats. A translational system toxicology model for GI AEs using citrulline was then developed based on new experimental data and parameters from a literature intestinal cell dynamic model. With the addition of feedback-development and tolerance-development mechanisms, the model well captured the plasma citrulline profiles after irinotecan treatment in rats. Subsequently, the model was translated to humans and predicted the observed GI AE dynamics in humans including dose-scheduling effect using the cytotoxic and feedback parameters estimated in rats with slight calibrations. This translational toxicology model could be used for other antineoplastic drugs to simulate various clinical dosing scenarios before human studies and mitigate potential GI AEs.

Citrulline as a marker of intestinal function and absorption in clinical settings: A systematic review and meta-analysis

Background

Citrulline has been described as a marker of intestinal function or absorption but evidence varies according to clinical settings.

Objective

The objective of this article is to examine the evidence of plasma citrulline as a marker of intestinal function and absorption in various clinical settings.

Methods

Studies were examined for p values, means and standard deviations, correlation coefficients or other metrics depicting the association of citrulline with intestinal function. A random effects model was used to produce a pooled estimate. A hierarchical summary receiver operating curve model was fitted for diagnostic accuracy measures.

Results

Citrulline levels are correlated strongly with small bowel length in short bowel syndrome patients (r = 0.67). Citrulline is strongly negatively correlated (r = -0.56) with intestinal disease severity with regards to enteropathies (coeliac disease, tropical enteropathy, Crohn's disease, mucositis, acute rejection in intestinal transplantation). Citrulline cut-off levels have an overall sensitivity and specificity of 80% and 84% respectively. Citrulline levels in untreated coeliac patients compared to controls were reduced by 10 µmol/l. Citrulline levels increase with gluten-free diet and with improvement of enteropathy. Citrulline is decreased in critical illness and sepsis.

Conclusion

These findings allow us to advocate quite reasonably that citrulline is a marker of acute and chronic intestinal insufficiency.

Diagnostics for Statistical Variable Selection Methods for Prediction of Peptic Ulcer Disease in Helicobacter pylori Infection

BACKGROUND

The development of accurate classification models depends upon the methods used to identify the most relevant variables. The aim of this article is to evaluate variable selection methods to identify important variables in predicting a binary response using nonlinear statistical models. Our goals in model selection include producing non-overfitting stable models that are interpretable, that generate accurate predictions and have minimum bias. This work was motivated by data on clinical and laboratory features of Helicobacter pylori infections obtained from 60 individuals enrolled in a prospective observational study.

RESULTS

We carried out a comprehensive performance comparison of several nonlinear classification models over the H. pylori data set. We compared variable selection results by Multivariate Adaptive Regression Splines (MARS), Logistic Regression with regularization, Generalized Additive Models (GAMs) and Bayesian Variable Selection in GAMs. We found that the MARS model approach has the highest predictive power because the nonlinearity assumptions of candidate predictors are strongly satisfied, a finding demonstrated via deviance chi-square testing procedures in GAMs.

CONCLUSIONS

Our results suggest that the physiological free amino acids citrulline, histidine, lysine and arginine are the major features for predicting H. pylori peptic ulcer disease on the basis of amino acid profiling.

Correlations of plasma citrulline levels with clinical and endoscopic score and blood markers according to small bowel involvement in pediatric Crohn disease

OBJECTIVE

Several studies have indicated that plasma citrulline levels reflect the extent of mucosal injury of the small intestine. This study was performed to determine whether plasma citrulline levels correlate with the disease activity in pediatric patients with Crohn disease (CD).

METHODS

A total of 63 CD and 23 ulcerative colitis (UC) patients were included in this study. Disease severity was assessed by pediatric CD activity index (PCDAI), pediatric UC activity index, simplified endoscopic activity score for CD, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). The correlations among these variables and plasma citrulline levels were evaluated. We performed subgroup analysis whether correlations between plasma citrulline levels and disease activity depend on small bowel involvement in patients with CD.

RESULTS

The plasma citrulline levels correlated negatively with CRP (r = -0.332, P = 0.008), ESR (r = -0.290, P = 0.022), and PCDAI (r = -0.424, P = 0.001) in patients with CD. The plasma citrulline levels were significantly lower in patients with jejunal involvement than in those without (P = 0.027). In subgroup analysis, patients with CD with jejunal involvement showed significantly negative correlations of plasma citrulline levels with CRP (r = -0.628, P = 0.016) and PCDAI (r = -0.632, P = 0.015); however, patients with CD without jejunal involvement revealed no correlations of plasma citrulline levels with CRP and PCDAI. There were no significant correlations between plasma citrulline levels and simplified endoscopic activity score for CD. There were no significant correlations of plasma citrulline levels with CRP, ESR, and pediatric UC activity index in patients with UC.

CONCLUSIONS

Plasma citrulline levels correlated with disease severity as measured by PCDAI, CRP, and ESR in pediatric patients with CD with jejunal involvement.

Fecal calprotectin in pediatric inflammatory bowel disease: a systematic review

BACKGROUND

Inflammatory bowel disease frequently begins during childhood or adolescence. Current tests and procedures for diagnosing and monitoring inflammatory bowel disease are invasive, uncomfortable and costly. Fecal calprotectin is an inflammatory marker tested in several studies including pediatric patients with inflammatory bowel disease.

METHODS

A search for articles published up to October 2011 was conducted using MEDLINE and EMBASE databases. We included original English-written articles referred to pediatric patients with inflammatory bowel disease and measured fecal calprotectin levels. We extracted data concerning fecal calprotectin levels in patients with inflammatory bowel disease and in the controls groups, sensitivity, specificity, positive and negative likelihood ratio.

RESULTS

Thirty-four studies were included. Fecal calprotectin levels of patients with inflammatory bowel disease are much higher than those of healthy controls or patients with functional disorders or other gastrointestinal diseases. The results vary greatly when taking all studies into consideration. Nevertheless, in cases of newly diagnosed and/or active inflammatory bowel disease, the results are more homogeneous, with high sensitivity and positive likelihood ratio, low negative likelihood ratio, but moderate specificity. Moreover, 50 μg/g seems to be the most proper cut-off point for the fecal calprotectin test.

CONCLUSIONS

The fecal calprotectin test could be used for supporting diagnosis or confirming relapse of inflammatory bowel disease in pediatric patients. A positive result could confirm the suspicion of either inflammatory bowel disease diagnosis or inflammatory bowel disease relapse, due to the high sensitivity of the test, but a negative result should not exclude these conditions, due to its moderate specificity.