Understanding the relationship between the microbiome and the structure and function of the pig gastrointestinal tract

The gut epithelium acts as a barrier to the gut environment. The integrity of the epithelial structure and function is thus critical for microbiome-host interaction. The gut microbiome can regulate the utilization and synthesis of mucin, the expressions of the intercellular junction complex, and the functioning of specific epithelial cells, such as enterochromaffin cells and stem cells in pigs. The factors involved include microbial metabolites, especially short-chain fatty acids and host-microbe co-metabolism. Recent studies have revealed the essential role of amino acid metabolism in regulating the gut microbiome and epithelial barrier. This chapter discusses how the pig gut microbiome modulates epithelial structure and function, highlighting findings that reflect the relationship between the gut microbiome, intestinal structure and function.

CADHERIN mediated AMIS localisation

Individual cells within de novo polarising tubes and cavities must integrate their forming apical domains into a centralised apical membrane initiation site (AMIS). This is necessary to enable organised lumen formation within multi-cellular tissue. Despite the well documented importance of cell division in localising the AMIS, we have found a division-independent mechanism of AMIS localisation that relies instead on CADHERIN-mediated cell-cell adhesion. Our study of de novo polarising mouse embryonic stem cells (mESCs) cultured in 3D suggest that cell-cell adhesion directs the localisation of apical proteins such as PAR-6 to a centralised AMIS. Unexpectedly, we also found that mESC cell clusters lacking functional E-CADHERIN were still able to form a lumen-like cavity in the absence of AMIS localisation and did so at a later stage of development via a closure mechanism, instead of via hollowing. This work suggests that there are two, interrelated mechanisms of apical polarity localisation: cell adhesion and cell division. Alignment of these mechanisms in space allows for redundancy in the system and ensures the development of a coherent epithelial structure within a growing organ.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

Ankrd31 in Sperm and Epididymal Integrity

Ankyrin proteins (ANKRD) are key mediators linking membrane and sub-membranous cytoskeletal proteins. Recent findings have highlighted a new role of ANKRD31 during spermatogenesis, elucidating its involvement in meiotic recombination and male germ cell progression. Following testicular differentiation, spermatozoa (SPZ) enter into the epididymis, where they undergo several biochemical and enzymatic changes. The epididymal epithelium is characterized by cell-to-cell junctions that are able to form the blood-epididymal barrier (BEB). This intricate epithelial structure provides the optimal microenvironment needed for epididymal sperm maturation. To date, no notions have been reported regarding a putative role of ANKRD31 in correct BEB formation. In our work, we generated an Ankrd31 knockout male mouse model (Ankrd31–/–) and characterized its reproductive phenotype. Ankrd31–/– mice were infertile and exhibited oligo-astheno-teratozoospermia (a low number of immotile SPZ with abnormal morphological features). In addition, a complete deregulation of BEB was found in Ankrd31–/–, due to cell-to-cell junction anomalies. In order to suggest that BEB deregulation may depend on Ankrd31 gene deletion, we showed the physical interaction among ANKRD31 and some epithelial junction proteins in wild-type (WT) epididymides. In conclusion, the current work shows a key role of ANKRD31 in the control of germ cell progression as well as sperm and epididymal integrity.

Establishment of Intestinal Organoid from Rousettus leschenaultii and the Susceptibility to Bat-Associated Viruses, SARS-CoV-2 and Pteropine Orthoreovirus

Various pathogens, such as Ebola virus, Marburg virus, Nipah virus, Hendra virus, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2, are threatening human health worldwide. The natural hosts of these pathogens are thought to be bats. The rousette bat, a megabat, is thought to be a natural reservoir of filoviruses, including Ebola and Marburg viruses. Additionally, the rousette bat showed a transient infection in the experimental inoculation of SARS-CoV-2. In the current study, we established and characterized intestinal organoids from Leschenault’s rousette, Rousettus leschenaultii. The established organoids successfully recapitulated the characteristics of intestinal epithelial structure and morphology, and the appropriate supplements necessary for long-term stable culture were identified. The organoid showed susceptibility to Pteropine orthoreovirus (PRV) but not to SARS-CoV-2 in experimental inoculation. This is the first report of the establishment of an expandable organoid culture system of the rousette bat intestinal organoid and its sensitivity to bat-associated viruses, PRV and SARS-CoV-2. This organoid is a useful tool for the elucidation of tolerance mechanisms of the emerging rousette bat-associated viruses such as Ebola and Marburg virus.

Fermented milk modulates immune systemic response and intestinal epithelial structure in Balb/c mice sensitized to bovine whey proteins

In epidemiological studies, cow’s milk protein allergy (CMPA) is the most prevalent allergy for infants or young children.This study was conducted to compare the effect of Soummam and Saifi fermented milks on mice sensiti-zed to whey protein (β –Lactoglobulin and α –Lactalbumin). During 28 days, the animals from the first and second lot received via an oral way the fer-mented milks. In a second period of time, mice from the first, second lots were sensitized via intraperitoneal way using β-Lg, mice from third and fourth lot were sensitized by α–Lactalbumin. The antigenecity was deter-mined by enzyme-linked immunosorbent assay (ELISA). Symptom scores were determined after in vivo challenge with β-Lg or α-Lac. Intestinal da-mage was evaluated by histological analysis. Analysis of the data revealed that the titers of anti-α-lactalbumin and anti-β-lactoglbulin IgG increased significantly in the positive control groups given Soummam and Saifi fer-mented milk (p <0.001). Moreover, in fermented milk-treated mice, signifi-cant clinical symptoms were observed. Analysis of histological sections re-vealed that fermented milk doesn’t reduce the microscopic lesions induced by β-Lg or α-Lac sensitzation. This study indicated that the administration of Soummam fermented milk can modulate effectively the immune response and protect the intestinal epithelium integrity.

Differential Diagnosis of Appendiceal Serrated Lesions and Polyps and Low-Grade Appendiceal Mucinous Neoplasm: Analysis Of 88 Cases

Purpose: To identify clinicopathological features for the differential diagnosis of appendiceal serrated lesions and polyps (SPs) and low-grade appendiceal mucinous neoplasm (LAMN) for the purpose of avoiding over‐diagnosis.Methods: Clinical data and pathological features of 66 patients with SPs diagnosed at the Aerospace Center Hospital between January 2013 and January 2021 were collected and compared to 22 cases of LAMN.Results: SPs, compared with LAMN, are likely to be associated with acute inflammation (SPs 53.0% vs. LAMN 18.2%), and may be located in the appendix partly, although with smaller diameter (average 9.6 vs. 27.2 mm); epithelial structures of serrated (100% vs. 22.7%) and filiform villous (47.0% vs. 18.2%) were often found in SPs. SPs occasionally show attenuated or flattened morphology (16.7% vs. 100%) and undulating or scalloped (7.6% vs. 40.9%) structures, and can also be accompanied by diverticulum (18.2% vs. 18.2%) and acellular mucin in the appendiceal wall (16.7% vs. 54.5%), which causes confusion with LAMN. The key point of the differential diagnosis is to observe whether the muscularis mucosa exists (loss, 0% vs. 100%) and fibrosis of the appendiceal wall (0% vs. 100%). SMA immunohistochemistry can assist in the diagnosis. Calcification is also indicative of LAMN.Conclusions: The epithelial structure of SPs can appear flattened and focally scalloped, and can be accompanied by mucin in the appendiceal wall, which may appear as complex lesions, easily over-diagnosed as LAMN. Key differential diagnostic features are identifying the structure of lamina propria, determining whether the muscularis mucosa exists, and whether the appendiceal wall is fibrotic.

Dietary Purple Potato Supplementation Ameliorates Gut Inflammation and Associated Colitis

Objectives The incidence of inflammatory bowel disease (IBD) is rapidly increasing worldwide. Patients with IBD experience increased susceptibility to colorectal cancer and are associated with morbidity and mortality. Diets are known factors associated with IBD. This study examined the beneficial effects of dietary purple potato against spontaneous colitis and improving gut microbiota in interleukin (IL)-10-deficient mice, a commonly used IBD mice model. Methods IL-10-deficient mice at 7-week-old were assigned to a standard rodent diet (CON) or a control diet supplemented with 10% purple potato (dry feed weight) for 11 weeks, when colonic tissues were collected for histological and biochemical analyses. Results Purple potato supplementation had no effect on feed intake and body weight in IL-10-deficient mice during the 11-week feeding trial. Purple potato supplementation improved the colitis symptom and the integrity of the colonic epithelial structure with reduced inflammation and pathological scores. Furthermore, the density of goblet cells and differentiation markers for goblet cells was enhanced due to PP supplementation. Conclusions Data collectively showed that dietary purple potato supplementation had protective effects against colitis onset in IL-10-deficient mice and improved gut epithelial structure, providing a promising dietary approach for the management and prevention of colitis. Funding Sources USDA-NIFA and Northwest Potato Research Consortium.

EFFECTOFTAIL-SUSPENSIONONLEVELSOFPRO- ANDANTI-INFLAMMATORY CYTOKINS AND MORPHOLOGICAL CHANGES IN RAT'S PULMONARY TISSUES

Cytokin regulation of local immune reactions in pulmonary tissues (IL-10, IL-4, TGFb1, TNFα), and morphology of the vascular bed and alveolar epithelium of the lung air compartments were studied in a 15-day tail-suspended Wistar male rats with a body mass of 180–200 grams. Cytokin regulation of the local immunity after suspension was characterized by activation of cell proliferation and differentiation regulator TGFβ1 aimed to forestall the inflammatory and auto immune processes and to promote remodeling of the lung epithelial structure and extracellular matrix.

Abl and Canoe/Afadin mediate mechanotransduction at tricellular junctions

Epithelial structure is generated by the dynamic reorganization of cells in response to mechanical forces. Adherens junctions transmit forces between cells, but how cells sense and respond to these forces in vivo is not well understood. We identify a mechanotransduction pathway involving the Abl tyrosine kinase and Canoe/Afadin that stabilizes cell adhesion under tension at tricellular junctions in the Drosophila embryo. Canoe is recruited to tricellular junctions in response to actomyosin contractility, and this mechanosensitivity requires Abl-dependent phosphorylation of a conserved tyrosine in the Canoe actin-binding domain. Preventing Canoe tyrosine phosphorylation destabilizes tricellular adhesion, and anchoring Canoe at tricellular junctions independently of mechanical inputs aberrantly stabilizes adhesion, arresting cell rearrangement. These results identify a force-responsive mechanism that stabilizes tricellular adhesion under tension during epithelial remodeling.