Integrin heterodimers containing an Integrin alpha V subunit are essential for development and play critical roles in cell adhesion and signaling. We identified biallelic variants in the gene coding for Integrin alpha V (ITGAV) in three independent families (two patients and four fetuses) that either caused abnormal mRNA and the loss of functional protein or caused mistargeting of the integrin. This led to eye and brain abnormalities, inflammatory bowel disease, immune dysregulation, and other developmental issues. Mechanistically, the reduction of functional Integrin αV resulted in the dysregulation of several pathways including TGF-β–dependent signaling and αVβ3-regulated immune signaling. These effects were confirmed using immunostaining, RNA sequencing, and functional studies in patient-derived cells. The genetic deletion of itgav in zebrafish recapitulated patient phenotypes including retinal and brain defects and the loss of microglia in early development as well as colitis in juvenile zebrafish with reduced SMAD3 expression and transcriptional regulation. Taken together, the ITGAV variants identified in this report caused a previously unknown human disease characterized by brain and developmental defects in the case of complete loss-of-function and atopy, neurodevelopmental defects, and colitis in cases of incomplete loss-of-function.

Diarrhoeal disorders in childhood extend beyond the inflammatory bowel diseases. Persistent and severe forms of diarrhoea can occur from birth and are associated with significant morbidity and mortality. These disorders can affect not only the gastrointestinal tract but frequently have extraintestinal manifestations, immunodeficiencies and endocrinopathies. Genomic analysis has advanced our understanding of these conditions and has revealed precision-based treatment options such as potentially curative haematopoietic stem cell transplant. Although many new mutations have been discovered, there is frequently no clear genotype–phenotype correlation. The functional effects of gene mutations can be studied in model systems such as patient-derived organoids. This allows us to further characterise these disorders and advance our understanding of the pathophysiology of the intestinal mucosa. In this review, we will provide an up to date overview of genes involved in diarrhoeal disorders of early onset, particularly focussing on the more recently described gene defects associated with protein loosing enteropathy.

Background: Tumor hypoxia is theorized to contribute to the aggressive biology of pancreatic ductal adenocarcinoma (PDAC). We previously reported that hypoxia correlated with rapid tumor growth and metastasis in patient-derived xenografts. Anticipating a prognostic relevance of hypoxia in patient tumors, we developed protocols for automated semi-quantitative image analysis to provide an objective, observer-independent measure of hypoxia. We further validated this method which can reproducibly estimate pimonidazole-detectable hypoxia in a high-through put manner.Methods: We studied the performance of three automated image analysis platforms in scoring pimonidazole-detectable hypoxia in resected PDAC (n = 10) in a cohort of patients enrolled in PIMO-PANC. Multiple stained tumor sections were analyzed on three independent image-analysis platforms, Aperio Genie (AG), Definiens Tissue Studio (TS), and Definiens Developer (DD), which comprised of a customized rule set.Results: The output from Aperio Genie (AG) had good concordance with manual scoring, but the workflow was resource-intensive and not suited for high-throughput analysis. TS analysis had high levels of variability related to misclassification of cells class, while the customized rule set of DD had a high level of reliability with an intraclass coefficient of more than 85%.Discussion: This work demonstrates the feasibility of developing a robust, high-performance pipeline for an automated, quantitative scoring of pimonidazole-detectable hypoxia in patient tumors.

Lytic cell death pathways drive hepatic ischemia-reperfusion injury (IRI). The transmembrane protein ninjurin-1 (NINJ1) aggregates in the plasma membrane to permeabilize the cell during multiple cell death pathways implicated in hepatic IRI. We hypothesized that NINJ1 mediates liver IRI and that its inhibition would mitigate injury. We found that NINJ1 is highly expressed in human liver tissue and that its up-regulation and activation correlate with early allograft dysfunction in liver transplant patients. Using a segmental hepatic IRI model in mice and rats, Ninj1 genetic deletion or pharmacologic inhibition diminished acute injury. Mice with hepatocyte- or macrophage-specific Ninj1 knockout had reduced hepatocellular injury following IRI, suggesting that NINJ1 within both populations contributes to the resulting liver injury. Mechanistically, we found that hepatocytes and Kupffer cells are susceptible to hypoxia-induced NINJ1-mediated plasma membrane rupture, which can be pharmacologically prevented. We therefore position NINJ1 as a potential new therapeutic target to limit hepatic IRI, with important implications for liver transplantation.

Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare entity reported in adults, frequently mimicking inflammatory bowel disease (IBD). We report the first case of intestinal ischemia secondary to IMHMV presenting as IBD in a pediatric patient with Down syndrome. Chronic intestinal ischemia is rare in children, and this case emphasizes the need to consider this in the differential, when histopathology is suggestive. Clinical findings and colonoscopy in these patients may mimic IBD. The mucosal biopsies do not show classic features of IBD. Instead, there can be variable extent of mucosal changes such as dilated small capillaries in the lamina propria, edema, and early fibrosis. These changes may in fact represent early chronic ischemia. These findings should alert for vascular imaging and a full‐thickness biopsy to assess submucosal and subserosal larger vessels since medium‐ and large‐caliber veins in the colonic wall and mesentery are affected in IMHMV.