Gut metabolome and microbiota signatures predict response to treatment with exclusive enteral nutrition in a prospective study in children with active Crohn's disease.

BACKGROUND: Predicting response to exclusive enteral nutrition (EEN) in active Crohn's disease (CD) could lead to therapy personalization and pretreatment optimization. OBJECTIVES: This study aimed to explore the ability of pretreatment parameters to predict fecal calprotectin (FCal) levels at EEN completion in a prospective study in children with CD. METHODS: In children with active CD, clinical parameters, dietary intake, cytokines, inflammation-related blood proteomics, and diet-related metabolites, metabolomics and microbiota in feces, were measured before initiation of 8 wk of EEN. Prediction of FCal levels at EEN completion was performed using machine learning. Data are presented with medians (IQR). RESULTS: Of 37 patients recruited, 15 responded (FCal < 250 µg/g) to EEN (responders) and 22 did not (nonresponders). Clinical and immunological parameters were not associated with response to EEN. Responders had lesser (µmol/g) butyrate [responders: 13.2 (8.63-18.4) compared with nonresponders: 22.3 (12.0-32.0); P = 0.03], acetate [responders: 49.9 (46.4-68.4) compared with nonresponders: 70.4 (57.0-95.5); P = 0.027], phenylacetate [responders: 0.175 (0.013-0.611) compared with nonresponders: 0.943 (0.438-1.35); P = 0.021], and a higher microbiota richness [315 (269-347) compared with nonresponders: 243 (205-297); P = 0.015] in feces than nonresponders. Responders consumed (portions/1000 kcal/d) more confectionery products [responders: 0.55 (0.38-0.72) compared with nonresponders: 0.19 (0.01-0.38); P = 0.045]. A multicomponent model using fecal parameters, dietary data, and clinical and immunological parameters predicted response to EEN with 78% accuracy (sensitivity: 80%; specificity: 77%; positive predictive value: 71%; negative predictive value: 85%). Higher taxon abundance from Ruminococcaceae, Lachnospiraceae, and Bacteroides and phenylacetate, butyrate, and acetate were the most influential variables in predicting lack of response to EEN. CONCLUSIONS: We identify microbial signals and diet-related metabolites in feces, which could comprise targets for pretreatment optimization and personalized nutritional therapy in pediatric CD.

Preclinical cardiovascular safety assessment of pharmacology-toxicology relationship for a set of novel kinase inhibitors.

Cardiovascular toxicity is one of the more common causes of attrition in preclinical and clinical drug development. Preclinical cardiovascular safety assessment involves numerous in vitro and in vivo endpoints which are being continually reviewed and improved to lower the incidence of cardiovascular toxicity that manifests only after the initiation of clinical trials. An example of notable preclinical toxicity is necrosis in the papillary muscle of the left ventricle in dogs that is induced by exaggerated pharmacological effects of vasodilators or positive inotropic/vasodilating off-target drug effects. Two distinct, small-molecule inhibitors that target an intracellular kinase, Compound A and Compound B, were profiled in 2-week dose-range finding and 4-week toxicity studies. Serum cardiac troponin (cTnI) was evaluated after a single dose and after 2-week and 4-week repeat dose studies with each kinase inhibitor. Acute effects on hemodynamic (heart rate, blood pressures, left ventricular contractility) and electrocardiographic (QTcV, PR, QRS intervals) endpoints by each inhibitor were assessed in an anesthetized dog cardiovascular model. Cardiovascular degeneration/necrosis with and without fibrosis was observed in dogs and correlated to increases in serum cTnI in repeat-dose toxicity studies. At the same doses used in toxicologic assessments, both kinase inhibitors produced sustained increases in heart rate, left ventricular contractility, and cardiac output, and decreases in mean arterial pressure. Cardiac pathology findings associated with these 2 kinase inhibitors were accompanied not only by cardiac troponin elevations but also associated with hemodynamic changes, highlighting the importance of the link of the physiologic-toxicologic interplay in cardiovascular safety assessment.

3D printed models are an accurate, cost-effective, and reproducible tool for quantifying terrestrial thermal environments.

Predicting ecological responses to rapid environmental change has become one of the greatest challenges of modern biology. One of the major hurdles in forecasting these responses is accurately quantifying the thermal environments that organisms experience. The distribution of temperatures available within an organism's habitat is typically measured using data loggers called operative temperature models (OTMs) that are designed to mimic certain properties of heat exchange in the focal organism. The gold standard for OTM construction in studies of terrestrial ectotherms has been the use of copper electroforming which creates anatomically accurate models that equilibrate quickly to ambient thermal conditions. However, electroformed models require the use of caustic chemicals, are often brittle, and their production is expensive and time intensive. This has resulted in many researchers resorting to the use of simplified OTMs that can yield substantial measurement errors. 3D printing offers the prospect of robust, easily replicated, morphologically accurate, and cost-effective OTMs that capture the benefits but alleviate the problems associated with electroforming. Here, we validate the use of OTMs that were 3D printed using several materials across eight lizard species of different body sizes and living in habitats ranging from deserts to tropical forests. We show that 3D printed OTMs have low thermal inertia and predict the live animal's equilibration temperature with high accuracy across a wide range of body sizes and microhabitats. Finally, we developed a free online repository and database of 3D scans (https://www.3dotm.org/) to increase the accessibility of this tool to researchers around the world and facilitate ease of production of 3D printed models. 3D printing of OTMs is generalizable to taxa beyond lizards. If widely adopted, this approach promises greater accuracy and reproducibility in studies of terrestrial thermal ecology and should lead to improved forecasts of the biological impacts of climate change.

A high-quality genome for the slender anole (Anolis apletophallus): an emerging model for field studies of tropical ecology and evolution.

The slender anole, Anolis apletophallus, is a small arboreal lizard of the rainforest understory of central and eastern Panama. This species has been the subject of numerous ecological and evolutionary studies over the past 60 years as a result of attributes that make it especially amenable to field and laboratory science. Slender anoles are highly abundant, short-lived (nearly 100% annual turnover), easy to manipulate in both the lab and field, and are ubiquitous in the forests surrounding the Smithsonian Tropical Research Institute in Panama, where researchers have access to high-quality laboratory facilities. Here, we present a high-quality genome for the slender anole, which is an important new resource for studying this model species. We assembled and annotated the slender anole genome by combining 3 technologies: Oxford Nanopore, 10× Genomics Linked-Reads, and Dovetail Omni-C. We compared this genome with the recently published brown anole (Anolis sagrei) and the canonical green anole (Anolis carolinensis) genomes. Our genome is the first assembled for an Anolis lizard from mainland Central or South America, the regions that host the majority of diversity in the genus. This new reference genome is one of the most complete genomes of any anole assembled to date and should facilitate deeper studies of slender anole evolution, as well as broader scale comparative genomic studies of both mainland and island species. In turn, such studies will further our understanding of the well-known adaptive radiation of Anolis lizards.

Bovine Serum Albumin-Protected Gold Nanoclusters for Sensing of SARS-CoV-2 Antibodies and Virus.

An approach to assess severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (and past infection) was developed. For virus detection, the SARS-CoV-2 virus nucleocapsid protein (NP) was targeted. To detect the NP, antibodies were immobilized on magnetic beads to capture the NPs, which were subsequently detected using rabbit anti-SARS-CoV-2 nucleocapsid antibodies and alkaline phosphatase (AP)-conjugated anti-rabbit antibodies. A similar approach was used to assess SARS-CoV-2-neutralizing antibody levels by capturing spike receptor-binding domain (RBD)-specific antibodies utilizing RBD protein-modified magnetic beads and detecting them using AP-conjugated anti-human IgG antibodies. The sensing mechanism for both assays is based on cysteamine etching-induced fluorescence quenching of bovine serum albumin-protected gold nanoclusters where cysteamine is generated in proportion to the amount of either SARS-CoV-2 virus or anti-SARS-CoV-2 receptor-binding domain-specific immunoglobulin antibodies (anti-RBD IgG antibodies). High sensitivity can be achieved in 5 h 15 min for the anti-RBD IgG antibody detection and 6 h 15 min for virus detection, although the assay can be run in "rapid" mode, which takes 1 h 45 min for the anti-RBD IgG antibody detection and 3 h 15 min for the virus. By spiking the anti-RBD IgG antibodies and virus in serum and saliva, we demonstrate that the assay can detect the anti-RBD IgG antibodies with a limit of detection (LOD) of 4.0 and 2.0 ng/mL in serum and saliva, respectively. For the virus, we can achieve an LOD of 8.5 × 105 RNA copies/mL and 8.8 × 105 RNA copies/mL in serum and saliva, respectively. Interestingly, this assay can be easily modified to detect myriad analytes of interest.

Mismatches between phenotype and environment shape fitness at hyperlocal scales.

In the era of human-driven climate change, understanding whether behavioural buffering of temperature change is linked with organismal fitness is essential. According to the 'cost-benefit' model of thermoregulation, animals that live in environments with high frequencies of favourable thermal microclimates should incur lower thermoregulatory costs, thermoregulate more efficiently and shunt the associated savings in time and energy towards other vital tasks such as feeding, territory defence and mate acquisition, increasing fitness. Here, we explore how thermal landscapes at the scale of individual territories, physiological performance and behaviour interact and shape fitness in the southern rock agama lizard (Agama atra). We integrated laboratory assays of whole organism performance with behavioural observations in the field, fine-scale estimates of environmental temperature, and paternity assignment of offspring to test whether fitness is predicted by territory thermal quality (i.e. the number of hours that operative temperatures in a territory fall within an individual's performance breadth). Male lizards that occupied territories of low thermal quality spent more time behaviourally compensating for sub-optimal temperatures and displayed less. Further, display rate was positively associated with lizard fitness, suggesting that there is an opportunity cost to engaging in thermoregulatory behaviour that will change as climate change progresses.

Utilization of a Glucometer Test Strip and Enzymatic Reactions to Quantify Anti-SARS-CoV-2 Spike RBD IgG Antibody and SARS-CoV-2 Virus in Saliva and Serum.

A sensor capable of quantifying both anti-SARS-CoV-2 spike receptor-binding domain (RBD) antibody levels and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in saliva and serum was developed. This was accomplished by exploiting the enzymatic reaction of maltose and orthophosphate (PO43-) in the presence of maltose phosphorylase to generate an equivalent amount of glucose that was detected using a commercial glucometer test strip and a potentiostat. Important for this approach is the ability to generate PO43- in an amount that is directly related to the concentration of the analytes. RBD-modified magnetic microparticles were used to capture anti-SARS-CoV-2 spike RBD antibodies, while particles modified with anti-SARS-CoV-2 nucleocapsid antibodies were used to capture SARS-CoV-2 nucleocapsid protein from inactivated virus samples. A magnet was used to isolate and purify the magnetic microparticles (with analyte attached), and alkaline phosphatase-conjugated secondary antibodies were bound to the analytes attached to the respective magnetic microparticles. Finally, through enzymatic reactions, specific amounts of PO43- (and subsequently glucose) were generated in proportion to the analyte concentration, which was then quantified using a commercial glucometer test strip. Utilizing glucose test strips makes the sensor relatively inexpensive, with a cost per test of ∼US $7 and ∼US $12 for quantifying anti-SARS-CoV-2 spike RBD antibody and SARS-CoV-2, respectively. Our sensor exhibited a limit of detection of 0.42 ng/mL for anti-SARS-CoV-2 spike RBD antibody, which is sensitive enough to quantify typical concentrations of antibodies in COVID-19-infected or vaccinated individuals (>1 µg/mL). The limit of detection for the SARS-CoV-2 virus is 300 pfu/mL (5.4 × 106 RNA copies/mL), which exceeds the performance recommended by the WHO (500 pfu/mL). In addition, the sensor exhibited good selectivity when challenged with competing analytes and could be used to quantify analytes in saliva and serum matrices with an accuracy of >94% compared to RT-qPCR.

A diminutive snake species can maintain regional heterothermy in both homogeneous and heterogeneous thermal environments.

Regional heterothermy is a pattern whereby different body regions are maintained at different temperatures, often to prioritize the function of certain body parts over others, or to maximize the function of organs and tissues that vary in thermal sensitivity. Regional heterothermy is relatively well understood in endotherms, where physiological mechanisms maintain heterogeneity. However, less is known about regional heterothermy in ectotherms, where behavioral mechanisms are more important for generating thermal variation. In particular, whether small and elongate ectotherms with high surface area to volume ratios such as diminutive snakes can maintain regional heterothermy, despite rapid thermal equilibration, is not yet known. We measured regional variation in body temperature and tested whether environmental heterogeneity is used to generate regional heterothermy in the ring-necked snake (Diadophis punctatus) using both field and laboratory studies. We found that ring-necked snakes have robust regional heterothermy in a variety of contexts, despite their small body size and elongate body shape. Temperature variation along the length of their bodies was not detectable when measured externally. However, snakes had higher mouth than cloacal temperatures both in the field and in laboratory thermal gradients. Further, this regional heterothermy was maintained even in ambient laboratory conditions, where the thermal environment was relatively homogeneous. Our results indicate that regional heterothermy in ring-necked snakes is not solely driven by environmental variation but is instead linked to physiological or morphological mechanisms that maintain regional variation in body temperature irrespective of environmental context.

Climate change is not just global warming: Multidimensional impacts on animal gut microbiota.

Climate change has rapidly altered many ecosystems, with detrimental effects for biodiversity across the globe. In recent years, it has become increasingly apparent that the microorganisms that live in and on animals can substantially affect host health and physiology, and the structure and function of these microbial communities can be highly sensitive to environmental variables. To date, most studies have focused on the effects of increasing mean temperature on gut microbiota, yet other aspects of climate are also shifting, including temperature variation, seasonal dynamics, precipitation and the frequency of severe weather events. This array of environmental pressures might interact in complex and non-intuitive ways to impact gut microbiota and consequently alter animal fitness. Therefore, understanding the impacts of climate change on animals requires a consideration of multiple types of environmental stressors and their interactive effects on gut microbiota. Here, we present an overview of some of the major findings in research on climatic effects on microbial communities in the animal gut. Although ample evidence has now accumulated that shifts in mean temperature can have important effects on gut microbiota and their hosts, much less work has been conducted on the effects of other climatic variables and their interactions. We provide recommendations for additional research needed to mechanistically link climate change with shifts in animal gut microbiota and host fitness.

Evolutionary constraints mediate extinction risk under climate change.

Mounting evidence suggests that rapid evolutionary adaptation may rescue some organisms from the impacts of climate change. However, evolutionary constraints might hinder this process, especially when different aspects of environmental change generate antagonistic selection on genetically correlated traits. Here, we use individual-based simulations to explore how genetic correlations underlying the thermal physiology of ectotherms might influence their responses to the two major components of climate change-increases in mean temperature and thermal variability. We found that genetic correlations can influence population dynamics under climate change, with declines in population size varying three-fold depending on the type of correlation present. Surprisingly, populations whose thermal performance curves were constrained by genetic correlations often declined less rapidly than unconstrained populations. Our results suggest that accurate forecasts of the impact of climate change on ectotherms will require an understanding of the genetic architecture of the traits under selection.

Three-Dimensional Reconstruction of the Hepatitis C Virus Envelope Glycoprotein E1E2 Heterodimer by Electron Microscopic Analysis.

Despite the development of highly effective hepatitis C virus (HCV) treatments, an effective prophylactic vaccine is still lacking. HCV infection is mediated by its envelope glycoproteins, E1 and E2, during the entry process, with E2 binding to cell receptors and E1 mediating endosomal fusion. The structure of E1E2 has only been partially resolved by X-ray crystallography of the core domain of E2 protein (E2c) and its complex with various neutralizing antibodies. Structural understanding of the E1E2 heterodimer in its native form can advance the design of candidates for HCV vaccine development. Here, we analyze the structure of the recombinant HCV E1E2 heterodimer with the aid of well-defined monoclonal anti-E1 and E2 antibodies, as well as a small-molecule chlorcyclizine-diazirine-biotin that can target and cross-link the putative E1 fusion domain. Three-dimensional (3D) models were generated after extensive 2D classification analysis with negative-stain single-particle data sets. We modeled the available crystal structures of the E2c and Fabs into 3D volumes of E1E2-Fab complexes based on the shape and dimension of the domain density. The E1E2 heterodimer exists in monomeric form and consists of a main globular body, presumably depicting the E1 and E2 stem/transmembrane domain, and a protruding structure representing the E2c region, based on anti-E2 Fab binding. At low resolution, a model generated from negative-stain analysis revealed the unique binding and orientation of individual or double Fabs onto the E1 and E2 components of the complex. Cryo-electron microscopy (cryo-EM) of the double Fab complexes resulted in a refined structural model of the E1E2 heterodimer, presented here. IMPORTANCE Recombinant HCV E1E2 heterodimer is being developed as a vaccine candidate. Using electron microscopy, we demonstrated unique features of E1E2 in complex with various neutralizing antibodies and small molecule inhibitors that are important to understanding its antigenicity and induction of immune response.

Climate anomalies and competition reduce establishment success during island colonization.

Understanding the factors that facilitate or constrain establishment of populations in novel environments is crucial for conservation biology and the study of adaptive radiation. Important questions include: (1) Does the timing of colonization relative to stochastic events, such as climatic perturbations, impact the probability of successful establishment? (2) To what extent does community context (e.g., the presence of competitors) change the probability of establishment? (3) How do sources of intrapopulation variance, such as sex differences, affect success at an individual level during the process of establishment? Answers to these questions are rarely pursued in a field-experimental context or on the same time scales (months to years) as the processes of colonization and establishment. We introduced slender anole lizards (Anolis apletophallus) to eight islands in the Panama Canal and tracked them over multiple generations to investigate the factors that mediate establishment success. All islands were warmer than the mainland (ancestral) environment, and some islands had a native competitor. We transplanted half of these populations only 4 months before the onset of a severe regional drought and the other half 2 years (two generations) before the drought. We found that successful establishment depended on both the intensity of interspecific competition and the timing of colonization relative to the drought. The islands that were colonized shortly before the drought went functionally extinct by the second generation, and regardless of time before the drought, the populations on islands with interspecific competition declined continuously over the study period. Furthermore, the effect of the competitor interacted with sex, with males suffering, and females benefitting, from the presence of a native competitor. Our results reveal that community context and the timing of colonization relative to climactic events can combine to determine establishment success and that these factors can generate opposite effects on males and females.

Sustained Drought, but Not Short-Term Warming, Alters the Gut Microbiomes of Wild Anolis Lizards.

As rising temperatures threaten biodiversity across the globe, tropical ectotherms are thought to be particularly vulnerable due to their narrow thermal tolerance ranges. Nevertheless, physiology-based models highlighting the vulnerability of tropical organisms rarely consider the contributions of their gut microbiota, even though microbiomes influence numerous host traits, including thermal tolerance. We combined field and lab experiments to understand the response of the slender anole lizard (Anolis apletophallus) gut microbiome to climatic shifts of various magnitude and duration. First, to examine the effects of long-term climate warming in the wild, we transplanted lizards from the mainland Panama to a series of warmer islands in the Panama Canal and compared their gut microbiome compositions after three generations of divergence. Next, we mimicked the effects of a short-term "heat-wave" by using a greenhouse experiment and explored the link between gut microbiome composition and lizard thermal physiology. Finally, we examined variation in gut microbiomes in our mainland population in the years both before and after a naturally occurring drought. Our results suggest that slender anole microbiomes are surprisingly resilient to short-term warming. However, both the taxonomic and predicted functional compositions of the gut microbiome varied by sampling year across all sites, suggesting that the drought may have had a regional effect. We provide evidence that short-term heat waves may not substantially affect the gut microbiota, while more sustained climate anomalies may have effects at broad geographic scales. IMPORTANCE As climate change progresses, it is crucial to understand how animals will respond to shifts in their local environments. One component of this response involves changes in the microbial communities living in and on host organisms. These "microbiomes" can affect many processes that contribute to host health and survival, yet few studies have measured changes in the microbiomes of wild organisms experiencing novel climatic conditions. We examined the effects of shifting climates on the gut microbiome of the slender anole lizard (Anolis apletophallus) by using a combination of field and laboratory studies, including transplants to warm islands in the Panama Canal. We found that slender anole microbiomes remain stable in response to short-term warming but may be sensitive to sustained climate anomalies, such as droughts. We discuss the significance of these findings for a species that is considered highly vulnerable to climate change.

Scientific and Regulatory Policy Committee Points to Consider: Integration of Clinical Pathology Data With Anatomic Pathology Data in Nonclinical Toxicology Studies.

Integrating clinical pathology data with anatomic pathology data is a common practice when reporting findings in the context of nonclinical toxicity studies and aids in understanding and communicating the nonclinical safety profile of test articles in development. Appropriate pathology data integration requires knowledge of analyte and tissue biology, species differences, methods of specimen acquisition and analysis, study procedures, and an understanding of the potential causes and effects of a variety of pathophysiologic processes. Neglecting these factors can lead to inappropriate data integration or a missed opportunity to enhance understanding and communication of observed changes. In such cases, nonclinical safety information relevant to human safety risk assessment may be misrepresented or misunderstood. This "Points to Consider" manuscript presents general concepts regarding pathology data integration in nonclinical studies, considerations for avoiding potential oversights and errors in data integration, and focused discussion on topics relevant to data integration for several key organ systems, including liver, kidney, and cardiovascular systems.

Species-Specific Expression of Growth-Regulatory Genes in 2 Anoles with Divergent Patterns of Sexual Size Dimorphism.

Sexual size dimorphism is widespread in nature and often develops through sexual divergence in growth trajectories. In vertebrates, the growth hormone/insulin-like growth factor (GH/IGF) network is an important regulator of growth, and components of this network are often regulated in sex-specific fashion during the development of sexual size dimorphism. However, expression of the GH/IGF network is not well characterized outside of mammalian model systems, and the extent to which species differences in sexual size dimorphism are related to differences in GH/IGF network expression is unclear. To begin bridging this gap, we compared GH/IGF network expression in liver and muscle from 2 lizard congeners, one with extreme male-biased sexual size dimorphism (brown anole, Anolis sagrei), and one that is sexually monomorphic in size (slender anole, A. apletophallus). Specifically, we tested whether GH/IGF network expression in adult slender anoles resembles the highly sex-biased expression observed in adult brown anoles or the relatively unbiased expression observed in juvenile brown anoles. We found that adults of the 2 species differed significantly in the strength of sex-biased expression for several key upstream genes in the GH/IGF network, including insulin-like growth factors 1 and 2. However, species differences in sex-biased expression were minor when comparing adult slender anoles to juvenile brown anoles. Moreover, the multivariate expression of the entire GH/IGF network (as represented by the first two principal components describing network expression) was sex-biased for the liver and muscle of adult brown anoles, but not for either tissue in juvenile brown anoles or adult slender anoles. Our work suggests that species differences in sex-biased expression of genes in the GH/IGF network (particularly in the liver) may contribute to the evolution of species differences in sexual size dimorphism.

Scientific and Regulatory Policy Committee Points to Consider: Integration of Clinical Pathology Data With Anatomic Pathology Data in Nonclinical Toxicology Studies.

Integrating clinical pathology data with anatomic pathology data is a common practice when reporting findings in the context of nonclinical toxicity studies and aids in understanding and communicating the nonclinical safety profile of test articles in development. Appropriate pathology data integration requires knowledge of analyte and tissue biology, species differences, methods of specimen acquisition and analysis, study procedures, and an understanding of the potential causes and effects of a variety of pathophysiologic processes. Neglecting these factors can lead to inappropriate data integration or a missed opportunity to enhance understanding and communication of observed changes. In such cases, nonclinical safety information relevant to human safety risk assessment may be misrepresented or misunderstood. This "Points to Consider" manuscript presents general concepts regarding pathology data integration in nonclinical studies, considerations for avoiding potential oversights and errors in data integration, and focused discussion on topics relevant to data integration for several key organ systems including liver, kidney, and cardiovascular system.

Intestinal fatty acid binding protein is a disease biomarker in paediatric coeliac disease and Crohn's disease.

BACKGROUND: There is a clinical need to develop biomarkers of small bowel damage in coeliac disease and Crohn's disease. This study evaluated intestinal fatty acid binding protein (iFABP), a potential biomarker of small bowel damage, in children with coeliac disease and Crohn's disease. METHODS: The concentration iFABP was measured in plasma and urine of children with ulcerative colitis, coeliac disease, and Crohn's disease at diagnosis and from the latter two groups after treatment with gluten free diet (GFD) or exclusive enteral nutrition (EEN), respectively. Healthy children (Controls) were also recruited. RESULTS: 138 children were recruited. Plasma but not urinary iFABP was higher in patients with newly diagnosed coeliac disease than Controls (median [Q1, Q3] coeliac disease: 2104 pg/mL 1493, 2457] vs Controls: 938 pg/mL [616, 1140], p = 0.001). Plasma or urinary iFABP did not differ between patients with coeliac on GFD and Controls. Baseline iFABP in plasma decreased by 6 months on GFD (6mo GFD: 1238 pg/mL [952, 1618], p = 0.045). By 12 months this effect was lost, at which point 25% of patients with coeliac disease had detectable gluten in faeces, whilst tissue transglutaminase IgA antibodies (TGA) continued to decrease. At diagnosis, patients with Crohn's disease had higher plasma iFABP levels than Controls (EEN Start: 1339 pg/mL [895, 1969] vs Controls: 938 pg/mL [616, 1140], p = 0.008). iFABP did not differ according to Crohn's disease phenotype. Induction treatment with EEN tended to decrease (p = 0.072) iFABP in plasma which was no longer different to Controls (EEN End: 1114 pg/mL [689, 1400] vs Controls: 938 pg/mL [616, 1140], p = 0.164). Plasma or urinary iFABP did not differ in patients with ulcerative colitis from Controls (plasma iFABP, ulcerative colitis: 1309 pg/mL [1005, 1458] vs Controls: 938 pg/mL [616, 1140], p = 0.301; urinary iFABP ulcerative colitis: 38 pg/mg [29, 81] vs Controls: 53 pg/mg [27, 109], p = 0.605). CONCLUSIONS: Plasma, but not urinary iFABP is a candidate biomarker with better fidelity in monitoring compliance during GFD than TGA. The role of plasma iFABP in Crohn's disease is promising but warrants further investigation. TRIAL REGISTRATION: Clinical Trials.gov, NCT02341248. Registered on 19/01/2015.

The Impact of Compliance During Exclusive Enteral Nutrition on Faecal Calprotectin in Children With Crohn Disease.

ABSTRACT: It remains unclear whether suboptimal response to exclusive enteral nutrition (EEN) in some children with Crohn disease (CD) is explained by poor compliance. The present study measured faecal gluten immunogenic peptides (GIP), a biomarker of gluten intake, in 45 children (3- 17 years) with CD, and explored associations with faecal calprotectin (FC) levels at 33 and 54 days of EEN. FC decreased in patients with undetectable GIP at both 33 and 54 days of EEN (mean decrease, 33 days: -743 mg/kg, 54 days: -1043 mg/kg, P  < 0.001) but not in patients who had detectable levels. At EEN completion, patients with undetectable GIP had a lower FC by 717 mg/kg compared with patients with a positive GIP result (P = 0.042) and demonstrated a greater decline from baseline FC (-69% vs +5%, P = 0.011). Poorer response to EEN is explained in part by diminished compliance. Faecal GIP might be useful as proxy biomarker of EEN compliance.

Symmetric Dimethylarginine Is a Sensitive Biomarker of Glomerular Injury in Rats.

Glomerular filtration rate is the gold-standard method for assessment of renal function but is rarely performed in routine toxicity studies. Standard serum biomarkers of renal function are insensitive and become elevated only with significant loss of organ function. Symmetric dimethylarginine (SDMA) is a ubiquitous analyte that is freely filtered by the glomerulus and can be detected in serum. It has shown utility for the detection of renal injury in dogs and cats in clinical veterinary practice, but the potential utility of SDMA to detect renal injury in preclinical species or toxicity studies has not been thoroughly investigated. We utilized a well-characterized glomerular toxicant, puromycin aminonucleoside, to induce podocyte injury and subsequent proteinuria in young male Sprague-Dawley rats. At the end of 1 or 2 weeks, blood, urine, and kidney tissue were collected for analysis. One week following a single 50 mg/kg dose, urea nitrogen, creatinine, and albumin mean values were within historical control ranges, while SDMA was increased. Glomerular changes in these animals included periodic acid-Schiff positive globules within podocytes, podocyte hypertrophy by light microscopy, and podocyte degeneration with effacement of foot processes by electron microscopy (EM). Taken together, our data indicate that SDMA may be a useful biomarker for early detection of glomerular toxicities in rats.

Dietary triggers of gut inflammation following exclusive enteral nutrition in children with Crohn's disease: a pilot study.

BACKGROUND: The anti-inflammatory effect of exclusive enteral nutrition on the gut of children with Crohn's disease is rapidly lost after food reintroduction. This study assessed disease dietary triggers following successful treatment with exclusive enteral nutrition. METHODS: Nutrient intake, dietary patterns and dietary biomarkers in faeces (gluten immunogenic peptides, undigestible starch, short chain fatty acids) were assessed in 14 children with Crohn's disease during early food reintroduction, following exclusive enteral nutrition. Groups above (Group A) and below (Group B) the median levels of faecal calprotectin after food reintroduction were assigned for comparative analysis. RESULTS: Intakes of fibre, gluten-containing cereals and red and processed meat were significantly higher in Group A than Group B; (median [Q1, Q3], g/day; Fibre: 12.1 [11.2, 19.9] vs. 9.9 [7.6, 12.1], p = 0.03; Red and processed meat: 151 [66.7, 190] vs. 63.3 [21.7, 67], p = 0.02; gluten-containing cereals: 289 [207, 402] vs. 203 [61, 232], p = 0.035). A diet consisting of cereals and meat products was predictive (92% accuracy) of higher faecal calprotectin levels after food reintroduction. In faeces, butyrate levels, expressed as absolute concentration and relative abundance, were higher in Group A than Group B by 28.4 µmol/g (p = 0.015) and 6.4% (p = 0.008), respectively. Levels of gluten immunogenic peptide and starch in faeces did not differ between the two groups. CONCLUSIONS: This pilot study identified potential dietary triggers of gut inflammation in children with Crohn's disease after food reintroduction following treatment with exclusive enteral nutrition. TRIAL REGISTRATION: Clinical trials.gov registration number: NCT02341248; Clinical trials.gov URL: https://clinicaltrials.gov/ct2/show/NCT02341248 (retrospectively registered).