Derivation of adult canine intestinal organoids for translational research in gastroenterology

Background

Large animal models, such as the dog, are increasingly being used for studying diseases including gastrointestinal (GI) disorders. Dogs share similar environmental, genomic, anatomical, and intestinal physiologic features with humans. To bridge the gap between commonly used animal models, such as rodents, and humans, and expand the translational potential of the dog model, we developed a three-dimensional (3D) canine GI organoid (enteroid and colonoid) system. Organoids have recently gained interest in translational research as this model system better recapitulates the physiological and molecular features of the tissue environment in comparison with two-dimensional cultures.

Results

Organoids were derived from tissue of more than 40 healthy dogs and dogs with GI conditions, including inflammatory bowel disease (IBD) and intestinal carcinomas. Adult intestinal stem cells (ISC) were isolated from whole jejunal tissue as well as endoscopically obtained duodenal, ileal, and colonic biopsy samples using an optimized culture protocol. Intestinal organoids were comprehensively characterized using histology, immunohistochemistry, RNA in situ hybridization, and transmission electron microscopy, to determine the extent to which they recapitulated the in vivo tissue characteristics. Physiological relevance of the enteroid system was defined using functional assays such as optical metabolic imaging (OMI), the cystic fibrosis transmembrane conductance regulator (CFTR) function assay, and Exosome-Like Vesicles (EV) uptake assay, as a basis for wider applications of this technology in basic, preclinical and translational GI research. We have furthermore created a collection of cryopreserved organoids to facilitate future research.

Conclusions

We establish the canine GI organoid systems as a model to study naturally occurring intestinal diseases in dogs and humans, and that can be used for toxicology studies, for analysis of host-pathogen interactions, and for other translational applications.

Electronic supplementary material

The online version of this article (10.1186/s12915-019-0652-6) contains supplementary material, which is available to authorized users.

Rapid Differentiation of Host and Parasitic Exosome Vesicles Using Microfluidic Photonic Crystal Biosensor

Parasite extracellular vesicles (EVs) are potential biomarkers that could be exploited for the diagnosis of infectious disease. This paper reports a rapid bioassay to discriminate parasite and host EVs. The EV detection assay utilizes a label-free photonic crystal (PC) biosensor to detect the EVs using a host-specific transmembrane protein (CD63), which is present on EV secreted by host cells (modeled by murine macrophage cell line J774A.1) but is not expressed on EV secreted by parasitic nematodes such as the gastrointestinal nematode Ascaris suum. The surface of PC is functionalized to recognize CD63, and is sensitive to the changes in refractive index caused by the immobilization of EVs. The biosensor demonstrates a detection limit of 2.18 × 10⁹ EVs/mL and a capability to characterize the affinity constants of antibody-host EV bindings. The discrimination of murine host EVs from parasite EVs indicates the capability of the sensor to differentiate EVs from different origins. The label-free, rapid EV assay could be used to detection parasite infection and facilitate the exosome-based clinic diagnosis and exosome research.

Gene Regulatory Network Inference from Perturbed Time-Series Expression Data via Ordered Dynamical Expansion of Non-Steady State Actors

The reconstruction of gene regulatory networks from gene expression data has been the subject of intense research activity. A variety of models and methods have been developed to address different aspects of this important problem. However, these techniques are narrowly focused on particular biological and experimental platforms, and require experimental data that are typically unavailable and difficult to ascertain. The more recent availability of higher-throughput sequencing platforms, combined with more precise modes of genetic perturbation, presents an opportunity to formulate more robust and comprehensive approaches to gene network inference. Here, we propose a step-wise framework for identifying gene-gene regulatory interactions that expand from a known point of genetic or chemical perturbation using time series gene expression data. This novel approach sequentially identifies non-steady state genes post-perturbation and incorporates them into a growing series of low-complexity optimization problems. The governing ordinary differential equations of this model are rooted in the biophysics of stochastic molecular events that underlie gene regulation, delineating roles for both protein and RNA-mediated gene regulation. We show the successful application of our core algorithms for network inference using simulated and real datasets.

Themes arising in clinical consultation for therapists implementing family-based treatment for adolescents with anorexia nervosa: a qualitative study

BACKGROUND

Our study aims to explore and describe themes arising in sessions of clinical consultation with therapists implementing Family-Based Treatment (FBT) for adolescents with Anorexia Nervosa (AN). There is currently no literature describing the content of clinical consultation for FBT. Thus, this knowledge will add to the evidence-base on what therapists need from consultants in ongoing clinical consultation.

METHODS

Eight therapists at four sites participated in this study, which spanned a two-year period. Following a two-day training workshop, each therapist treated at least one adolescent patient presenting with a restrictive eating disorder with FBT, focusing on adherence to the treatment manual. Clinical consultation sessions occurred monthly and were led by an external FBT expert. Thirty-five (average per site = 9) audio recorded group clinical consultation sessions were transcribed verbatim and coded for themes. Twenty percent of the transcripts were double-coded to ensure consistency. Fundamental qualitative description guided the sampling and data collection.

RESULTS

Thematic content analysis revealed ten common themes relating to the provision of clinical consultation to therapists implementing FBT in clinical practice: encouraging parental meal time supervision,discussing the role of mothers, how to align parents, ensuring parental buy-in, when to transition to Phase 2, weighing the patient and the patients' knowledge of their weight, the role of siblings in FBT sessions, how best to manage patient co-morbidities, the role of the father in FBT and how best to manage the family meal.

CONCLUSIONS

In conclusion, clinical consultation themes aligned with many of the central tenets of FBT, including how to help parents align their supportive approach during the refeeding process, and how to help parents assume control of eating disordered behaviours. This knowledge helps to guide consultants to anticipate common issues brought forward by therapists attempting to implement FBT.

Involvement of a putative intercellular signal-recognizing G protein-coupled receptor in the engulfment of Salmonella by the protozoan Tetrahymena

In an effort to investigate the molecular basis of protozoa engulfment-mediated hypervirulence of Salmonella in cattle, we evaluated protozoan G protein-coupled receptors (GPCRs) as transducers of Salmonella engulfment by the model protozoan Tetrahymena. Our laboratory previously demonstrated that non-pathogenic protozoa (including Tetrahymena) engulf Salmonella and then exacerbate its virulence in cattle, but the mechanistic details of the phenomenon are not fully understood. GPCRs were investigated since these receptors facilitate phagocytosis of particulates by Tetrahymena, and a GPCR apparently modulates bacterial engulfment for the pathogenic protozoan Entamoeba histolytica. A database search identified three putative Tetrahymena GPCRs, based on sequence homologies and predicted transmembrane domains, that were the focus of this study. Salmonella engulfment by Tetrahymena was assessed in the presence of suramin, a non-specific GPCR inhibitor. Salmonella engulfment was also assessed in Tetrahymena in which expression of putative GPCRs was knocked-down using RNAi. A candidate GPCR was then expressed in a heterologous yeast expression system for further characterization. Our results revealed that Tetrahymena were less efficient at engulfing Salmonella in the presence of suramin. Engulfment was reduced concordantly with a reduction in the density of protozoa. RNAi-based studies revealed that knock-down of one the Tetrahymena GPCRs caused diminished engulfment of Salmonella. Tetrahymena lysates activated this receptor in the heterologous expression system. These data demonstrate that the Tetrahymena receptor is a putative GPCR that facilitates bacterial engulfment by Tetrahymena. Activation of the putative GPCR seemed to be related to protozoan cell density, suggesting that its cognate ligand is an intercellular signaling molecule.

Getting to the root of neuronal signalling in plant-parasitic nematodes using RNA interference

Abstract

A variety of genes expressed in preparasitic second-stage juveniles (J2) of plant-parasitic nematodes appear to be vulnerable to RNA interference (RNAi) in vitro by coupling double-stranded (ds)RNA soaking with the artificial stimulation of pharyngeal pumping. Also, there is mounting evidence that the in planta generation of nematode-specific double-stranded RNAs (dsRNAs) has real utility in the control of these pests. Although neuronally-expressed genes in Caenorhabditis elegans are commonly refractory to RNAi, we have discovered that neuronally-expressed genes in plant-parasitic nematodes are highly susceptible to RNAi and that silencing can be induced by simple soaking procedures without the need for pharyngeal stimulation. Since most front-line anthelmintics that are used for the control of nematode parasites of animals and humans act to disrupt neuromuscular coordination, we argue that intercellular signalling processes associated with neurons have much appeal as targets for transgenic plant-based control strategies for plant-parasitic nematodes. FMRFamide-like peptides (FLPs) are a large family of neuropeptides which are intimately associated with neuromuscular regulation, and our studies on flp gene function in plant-parasitic nematodes have revealed that their expression is central to coordinated locomotory activities. We propose that the high level of conservation in nervous systems across nematodes coupled with the RNAi-susceptibility of neuronally-expressed genes in plant-parasitic nematodes provides a valuable research tool which could be used to interrogate neuronal signalling processes in nematodes.

Population-specific patterns of linkage disequilibrium in the human 5q31 region

Linkage disequilibrium across the human genome is generally lower in West Africans than Europeans. However in the 5q31 region, which is rich in immune genes, we find significantly more examples of apparent nonrecombination between distant marker pairs in West Africans. Much of this effect is due to SNPs that are absent in Europeans, possibly reflecting recent positive selection in the West African population.

Mullerian inhibiting substance acts as a motor neuron survival factor in vitro

The survival of motor neurons is controlled by multiple factors that regulate different aspects of their physiology. The identification of these factors is important because of their relationship to motor neuron disease. We investigate here whether Mullerian Inhibiting Substance (MIS) is a motor neuron survival factor. We find that motor neurons from adult mice synthesize MIS and express its receptors, suggesting that mature motor neurons use MIS in an autocrine fashion or as a way to communicate with each other. MIS was observed to support the survival and differentiation of embryonic motor neurons in vitro. During development, male-specific MIS may have a hormone effect because the blood-brain barrier has yet to form, raising the possibility that MIS participates in generating sex-specific differences in motor neurons.

Functional ryanodine receptor channels in flatworm muscle fibres

Caffeine, which stimulates intracellular Ca2+ release channels known as ryanodine receptor (RyR) channels, induces contraction of individual muscle fibres dissociated from the trematode Schistosoma mansoni, and the turbellarians Dugesia tigrina and Procerodes littoralis. Caffeine is much more potent on S. mansoni fibres (EC50 0.7 mM) than those from D. tigrina or P. littoralis (3.2 mM and 4.6 mM, respectively). These caffeine-induced contractions are blocked by ryanodine, confirming the presence of functional RyR channels in these flatworm muscles. However, the contractions are not blocked by typical RyR channel blockers ruthenium red or neomycin, indicating that there may be important pharmacological differences between the RyR channels in this early-diverging phylum and those of later animals. These studies demonstrate that RyR channels are present in the muscle of these flatworms, and that the sarcoplasmic reticulum stores sufficient Ca2+ to support contraction.