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Background Emerging evidence underscores the responsiveness of the mammalian intestine to dietary cues, notably through the involvement of LGR5 + intestinal stem cells in orchestrating responses to diet-driven signals. However, the effects of high-fat diet (HFD) on these cellular dynamics and their impact on gut integrity remain insufficiently understood. Our study aims to assess the multifaceted interactions between palmitic acid (PA), cell proliferation, and the intestinal epithelial barrier using a canine colonoid model. Canine models, due to their relevance in simulating human intestinal diseases, offer a unique platform to explore the molecular mechanisms underlying HFD derived intestinal dysfunction. Results Canine colonoids were subjected to PA exposure, a surrogate for the effects of HFD. This intervention revealed a remarkable augmentation of cell proliferative activity. Furthermore, we observed a parallel reduction in transepithelial electrical resistance (TEER), indicating altered epithelium barrier integrity. While E-cadherin exhibited consistency, ZO-1 displayed a noteworthy reduction in fluorescence intensity within the PA-exposed group. Conclusions By employing canine intestinal organoid systems, we provide compelling insights into the impact of PA on intestinal physiology. These findings underscore the importance of considering both cell proliferative activity and epithelial integrity in comprehending the repercussions of HFDs on intestinal health. Our study contributes to a deeper understanding of the consequences of HFD on intestinal homeostasis, utilizing valuable translational in vitro models derived from dogs.

Background Gallbladder mucocele (GBM) is a common disease in the canine gallbladder. Although the pathogenesis of GBM remains unclear, we recently reported that the excessive accumulation of mucin in the gallbladder is not a result of overproduction by gallbladder epithelial cells (GBECs). Hypothesis/Objectives Changes in the function of GBECs other than the production of mucin are associated with the pathogenesis of GBM. We performed an RNA sequencing (RNA‐seq) analysis to comprehensively search for abnormalities in gene expression profiles of GBECs in dogs with GBM. Animals Fifteen dogs with GBM and 8 dogs euthanized for reasons other than gallbladder disease were included. Methods The GBECs were isolated from gallbladder tissues to extract RNA. The RNA‐seq analysis was performed using the samples from 3 GBM cases and 3 dogs with normal gallbladders, and the gene expression profiles were compared between the 2 groups. Differences in mRNA expression levels of the extracted differentially expressed genes (DEGs) were validated by quantitative reverse transcription polymerase chain reaction (RT‐qPCR) using samples of 15 GBM cases and 8 dogs with normal gallbladders. Results Comparison of gene expression profiles by RNA‐seq extracted 367 DEGs, including ANO1, a chloride channel associated with changes in mucin morphology, and HTR4, which regulates the function of chloride channels. The ANO1 and HTR4 genes were confirmed to be downregulated in the GBM group by RT‐qPCR. Conclusions and Clinical Importance Our results suggest that GBM may be associated with decreased function of chloride channels expressed in GBECs.

The study of biliary physiology and pathophysiology has long been hindered by the lack of in vitro models that accurately reflect the complex functions of the biliary system. Recent advancements in 3D organoid technology may offer a promising solution to this issue. Bovine gallbladder models have recently gained attention in the investigation of human diseases due to their remarkable similarities in physiology and pathophysiology with the human gallbladder. In this study, we have successfully established and characterized bovine gallbladder cholangiocyte organoids (GCOs) that retain key characteristics of the gallbladder in vivo , including stem cell properties and proliferative capacity. Notably, our findings demonstrate that these organoids exhibit specific and functional CFTR activity. We believe that these bovine GCOs represent a valuable tool for studying the physiology and pathophysiology of the gallbladder with human significance.

Backgrounds The interplay between intestinal epithelial cells (IECs), the immune system, and the gut microbiome is pivotal for maintaining gastrointestinal homeostasis and mediating responses to ingested antigens. IECs, capable of expressing Major Histocompatibility Complex (MHC) class II molecules, are essential in modulating immune responses, especially CD4 + T cells, in both physiological and pathological contexts. The expression of MHC class II on IECs, regulated by the class II transactivator (CIITA) and inducible by cytokine IFN-γ, has been traditionally associated with professional antigen-presenting cells but is now recognized in the context of inflammatory conditions such as inflammatory bowel disease (IBD). In veterinary medicine, particularly among canine populations, MHC (or Dog Leukocyte Antigen, DLA) expression on IECs underlines its significance in intestinal immune pathologies, yet remains underexplored. This study aims to leverage canine intestinal organoids as a novel in vitro model to elucidate MHC class II expression dynamics and their implications in immune-mediated gastrointestinal diseases, bridging the gap between basic research and clinical application in canine health. Results Canine colonoids derived from healthy dogs showed significant expression of MHC class II and its promoter gene, CIITA , after IFN-γ treatment. This MHC class II induction was even more pronounced in differentiated colonoids cultured in Wnt-3a-depleted medium. Conclusions This study provides insights into the role of IECs as antigen-presenting cells and demonstrates the use of intestinal organoids for investigating epithelial immune responses in inflammatory conditions.

Veterinary medicine has made tremendous progress for domestic dogs, which are irreplaceable family members enriching human life. Nevertheless, no adequate supply system exists for their blood products. This study examined the synthesis, structure, safety, and efficacy of poly(2-ethyl-2-oxazoline)-conjugated porcine serum albumin (POx-PSA) as an artificial plasma expander for dogs. The aqueous POx-PSA solution showed moderately high colloid osmotic pressure and good blood cell compatibility. Actually, lyophilized powder stored for 1 year can regenerate into a homogeneous solution. The circulation half-life of POx-PSA in rats was 2.1-fold longer than that of naked PSA. Rats produced neither anti-PSA IgG antibody nor anti-POx IgG antibody, which suggests excellent immunological stealth properties of POx-PSA. Complete resuscitation of hemorrhagic shock in rats was achieved soon after injection of POx-PSA solution. Serum biochemistry tests and histopathological observations indicated no abnormality in the related organs. When POx-PSA was administered to dogs intravenously, (i) no serum biochemical or hematological alteration was observed, also (ii) no overt deterioration of animal health was observed. These results indicate that POx-PSA has potential as an artificial plasma expander for dogs.

An 11-year-old, 12.3-kg, female Miniature Dachshund was presented to our institution with ascites of unknown etiology. The dog had been administered moxidectin for 3 years to treat a heartworm infection. Thoracic radiographs showed enlargement of the right heart. Echocardiography revealed right atrial and ventricular dilatation as well as flattening of the interventricular septum. Heartworm was identified in the main pulmonary artery, which was dilated. Tricuspid regurgitation (TR) was observed using color Doppler ultrasonography, and 2.5 L of ascites were removed. The dog was diagnosed with pulmonary hypertension, severe TR, and right-sided congestive heart failure. Except at the initial site, heartworm was not detected using echocardiography, and the antigen test was negative. However, pharmacological treatment did not improve the right-sided congestive heart failure. Instead, De Vega tricuspid annuloplasty (TAP) was performed on the beating heart under cardiopulmonary bypass with the owner's consent. Sutures terminated between the two commissures in the middle of the annulus and were secured using another pledget. Annular reduction was performed by tying down the plication suture while the cylindrical sizer was inserted into the tricuspid valve orifice. The size of the cylindrical sizer was 16 mm, which was set based on the height and width of the septal leaflet. A 6-month follow-up showed a reduction of TR and right-sided volume overload with no evidence of ascites retention/recurrence or any other complication. Our findings indicate that TAP may be a valid treatment option for dogs with right-sided congestive heart failure caused by secondary TR.

Large cell gastrointestinal lymphoma (LCGIL) is the most common extranodal lymphoma in dogs, but its molecular biological backgrounds have not been clarified. In this study, we comprehensively investigated the gene mutations in LCGIL. Whole exome sequencing analysis using four dogs with LCGIL showed mutations in NACC1 gene in two dogs. Further, the six genes known to be mutated in human intestinal T-cell lymphoma, ASXL3, SOCS3, PRDM1, FYN, TET2, and ZDBF2, were found to be mutated in one dog. Then, targeted next-generation sequencing analysis was performed to validate these results using additional 31 dogs with LCGIL. As a result, the mutation in ZDBF2 genes were identified in all samples, but the same mutation was ubiquitously observed in all peripheral blood samples. As for the remaining genes, the mutations were not observed in any dogs. The targeted next-generation analysis of whole exon regions of ZDBF2 revealed the other mutations in additional three dogs. In the present study, some mutations in genes related to human intestinal T-cell lymphoma were identified, but common gene mutations were not found among most cases. These results implied the heterogeneity of molecular pathophysiology of canine LCGIL. Further studies are needed to comprehensively analyze genomic and non-genomic molecular aberrations in each canine LCGIL case.

Abstract The understanding of the role of intestinal bacteria in various intestinal diseases has been limited due to the lack of suitable in vitro models. However, recent advancements in Gut-on-a-Chip culture technology provide a promising avenue for exploring complex interactions between intestinal epithelium and bacteria. In this study, we aimed to create a microfluidic Gut-on-a-Chip co-culture system using dogs as a model. Dogs share similarities with humans in terms of intestinal disease pathophysiology, clinical presentations, and intestinal microbiome, making them a relevant model for various intestinal diseases, including inflammatory bowel disease (IBD). We cultured colonoids from both healthy dogs and dogs with IBD on the Gut-on-a-Chip platform to create villus-like structures under dynamic conditions. Co-cultures with non-pathogenic Escherichia coli (NPE) were established in the Gut-on-a-Chip with healthy colonoids, and we conducted a static Transwell (TW) co-culture for comparison. To assess epithelial barrier integrity, we measured transepithelial electrical resistance (TEER), and we evaluated the expression of ZO-1, a tight junction protein, through immunofluorescence staining (IF). Following 6-9 days of uninterrupted medium flow in the Gut-on-a-Chip models, we observed sporadic clusters of villus-like structures (i.e., 3D morphogenesis) in canine intestinal epithelial cells in both the models derived from healthy dogs and those with IBD. The IF confirmed the presence of ZO-1, indicating the establishment of tight junctions. Infection with NPE in the TW system resulted in a significant reduction in TEER (48.2±4.4% at 12 hours and 7.3±5.3% at 24 hours). In contrast, the Gut-on-a-Chip maintained TEER levels at 100.3±12.8% at 12 hours, 94.9±2.2% at 24 hours, and 88.8±15.0% at 48 hours, preserving the 3D structure. The innovative canine Gut-on-a-Chip model, capable of reproducing villus-like structures and preserving a 3D configuration using both healthy and diseased organoids (specifically, IBD), presents a valuable platform for investigating bacterial-epithelium interactions in both human and veterinary medicine. This dynamic microfluidic culture system enables the co-cultivation of living bacteria while maintaining epithelial integrity, facilitating the study of intricate interactions between intestinal bacteria and epithelial crosstalk.

Recent advancements in canine intestinal organoid research have paved the way for the development of enhanced in vitro models, crucial for exploring intestinal physiology and diseases. Despite these strides, there is a notable gap in creating specific in vitro models that focus on intestinal inflammation. Our study aims to bridge this gap by investigating the impact of proinflammatory cytokines on canine intestinal epithelial cells (IECs) within the context of organoid models. Canine intestinal organoids were treated with proinflammatory cytokines TNF-α, IFN-γ, and IL-1β. The expression of stem cell markers Lgr5 , Sox9 , Hopx , and Olfm4 was evaluated through RT-qPCR, while membrane integrity was assessed using immunofluorescence staining for tight junction proteins and transport assays for permeability. IFN-γ significantly decreased Lgr5 expression, a key intestinal stem cell marker, at both 24 and 48 h post-treatment ( p =0.030 and p =0.002, respectively). Conversely, TNF-α increased Olfm4 expression during the same intervals ( p =0.018 and p =0.011, respectively). A reduction in EdU-positive cells, indicative of decreased cell proliferation, was observed following IFN-γ treatment. Additionally, a decrease in tight junction proteins E-cadherin and ZO-1 ( p <0.001 and p =0.003, respectively) and increased permeability in IECs ( p =0.012) were noted, particularly following treatment with IFN-γ. The study highlights the profound impact of proinflammatory cytokines on canine IECs, influencing both stem cell dynamics and membrane integrity. These insights shed light on the intricate cellular processes underlying inflammation in the gut and open avenues for more in-depth research into the long-term effects of inflammation on intestinal health.

This study addresses the gap in translatable in vitro models for investigating Enterohemorrhagic E. coli (EHEC) infections, particularly relevant to both canine and human health. EHEC is known to induce acute colitis in dogs, leading to symptoms like hemorrhagic diarrhea and hemolytic uremic syndrome, similar to those observed in humans. However, understanding the pathophysiology and developing treatment strategies have been challenging due to the lack of effective models that replicate the clinical disease caused by EHEC in both species. Our approach involved the development of colonoid-derived monolayers using intestinal tissues from healthy, client-owned dogs. These monolayers were exposed to EHEC and the impact of EHEC was assessed through several techniques, including trans-epithelial electrical resistance (TEER) measurement, immunofluorescence staining for junction proteins and mucus, and scanning electron microscopy for morphological analysis. Modified culture with saline, which was intended to prevent bacterial overgrowth, maintained barrier integrity and cell differentiation. EHEC infection led to significant decreases in TEER and ZO-1 expression, but not in E-cadherin levels or mucus production. Additionally, EHEC elicited a notable increase in TNF-α production, highlighting its distinct impact on canine intestinal epithelial cells compared to non-pathogenic E. coli. These findings closely replicate in vivo observations in dogs and humans with EHEC enteropathy, validating the canine colonoid-derived monolayer system as a translational model to study host-pathogen interactions in EHEC and potentially other clinically significant enteric pathogens.