Chicken-derived RSPO1 and WNT3 contribute to maintaining longevity of chicken intestinal organoid cultures

Intestinal organoids are advanced cellular models, which are widely used in mammalian studies to mimic and study in vivo intestinal function and host–pathogen interactions. Growth factors WNT3 and RSPO1 are crucial for the growth of intestinal organoids. Chicken intestinal organoids are currently cultured with mammalian Wnt3a and Rspo1, however, maintaining their longevity has shown to be challenging. Based on the limited homology between mammalian and avian RSPO1, we expect that chicken-derived factors are required for the organoid cultures. Isolated crypts from embryonic tissue of laying hens were growing in the presence of chicken WNT3 and RSPO1, whereas growth in the presence of mammalian Wnt3a and Rspo1 was limited. Moreover, the growth was increased by using Prostaglandin E2 (PGE₂) and a Forkhead box O1-inhibitor (FOXO1-inhibitor), allowing to culture these organoids for 15 passages. Furthermore, stem cells maintained their ability to differentiate into goblets, enterocytes and enteroendocrine cells in 2D structures. Overall, we show that chicken intestinal organoids can be cultured for multiple passages using chicken-derived WNT3 and RSPO1, PGE₂, and FOXO1-inhibitor.

Flood Control: How Milk-Derived Extracellular Vesicles Can Help to Improve the Intestinal Barrier Function and Break the Gut-Joint Axis in Rheumatoid Arthritis

Many studies provided compelling evidence that extracellular vesicles (EVs) are involved in the regulation of the immune response, acting as both enhancers and dampeners of the immune system, depending on the source and type of vesicle. Research, including ours, has shown anti-inflammatory effects of milk-derived EVs, using human breast milk as well as bovine colostrum and store-bought pasteurized cow milk, in in vitro systems as well as therapeutically in animal models. Although it is not completely elucidated which proteins and miRNAs within the milk-derived EVs contribute to these immunosuppressive capacities, one proposed mechanism of action of the EVs is via the modulation of the crosstalk between the (intestinal) microbiome and their host health. There is increasing awareness that the gut plays an important role in many inflammatory diseases. Enhanced intestinal leakiness, dysbiosis of the gut microbiome, and bowel inflammation are not only associated with intestinal diseases like colitis and Crohn's disease, but also characteristic for systemic inflammatory diseases such as lupus, multiple sclerosis, and rheumatoid arthritis (RA). Strategies to target the gut, and especially its microbiome, are under investigation and hold a promise as a therapeutic intervention for these diseases. The use of milk-derived EVs, either as stand-alone drug or as a drug carrier, is often suggested in recent years. Several research groups have studied the tolerance and safety of using milk-derived EVs in animal models. Due to its composition, milk-derived EVs are highly biocompatible and have limited immunogenicity even cross species. Furthermore, it has been demonstrated that milk-derived EVs, when taken up in the gastro-intestinal tract, stay intact after absorption, indicating excellent stability. These characteristics make milk-derived EVs very suitable as drug carriers, but also by themselves, these EVs already have a substantial immunoregulatory function, and even without loading, these vesicles can act as therapeutics. In this review, we will address the immunomodulating capacity of milk-derived EVs and discuss their potential as therapy for RA patients.

Review criteria

The search terms "extracellular vesicles", "exosomes", "microvesicles", "rheumatoid arthritis", "gut-joint axis", "milk", and "experimental arthritis" were used. English-language full text papers (published between 1980 and 2021) were identified from PubMed and Google Scholar databases. The reference list for each paper was further searched to identify additional relevant articles.

Enterocytes, fibroblasts and myeloid cells synergize in anti-bacterial and anti-viral pathways with IL22 as the central cytokine

IL22 is an important cytokine involved in the intestinal defense mechanisms against microbiome. By using ileum-derived organoids, we show that the expression of anti-microbial peptides (AMPs) and anti-viral peptides (AVPs) can be induced by IL22. In addition, we identified a bacterial and a viral route, both leading to IL22 production by T cells, but via different pathways. Bacterial products, such as LPS, induce enterocyte-secreted SAA1, which triggers the secretion of IL6 in fibroblasts, and subsequently IL22 in T cells. This IL22 induction can then be enhanced by macrophage-derived TNFα in two ways: by enhancing the responsiveness of T cells to IL6 and by increasing the expression of IL6 by fibroblasts. Viral infections of intestinal cells induce IFNβ1 and subsequently IL7. IFNβ1 can induce the expression of IL6 in fibroblasts and the combined activity of IL6 and IL7 can then induce IL22 expression in T cells. We also show that IL22 reduces the expression of viral entry receptors (e.g. ACE2, TMPRSS2, DPP4, CD46 and TNFRSF14), increases the expression of anti-viral proteins (e.g. RSAD2, AOS, ISG20 and Mx1) and, consequently, reduces the viral infection of neighboring cells. Overall, our data indicates that IL22 contributes to the innate responses against both bacteria and viruses.

Survival and cellular heterogeneity of epithelium in cultured mouse and rat precision-cut intestinal slices

Precision-cut intestinal slices (PCIS) are used to study intestinal (patho)physiology, drug efficacy, toxicity, transport and metabolism ex vivo. One of the factors that limit the use of PCIS is a relatively short life-span. Moreover, culture-induced changes in cellular composition of PCIS remain largely uncharacterized. In this study, we demonstrated the epithelial cell heterogeneity in mouse and rat PCIS and its alterations during culture. In addition, we evaluated whether the presence of niche growth factors impacts the survival of PCIS epithelial cells. We showed that freshly prepared PCIS retained the main epithelial cell types, namely absorptive enterocytes, goblet cells, enteroendocrine cells, stem cells, transit-amplifying cells and Paneth cells. Once placed in culture, PCIS displayed progressive epithelial damage, and loss of these epithelial cell types. Cells comprising the intestinal stem cell niche were especially sensitive to the damage, and the addition of niche growth factors beneficially affected the survival of stem cells and transit-amplifying cells in PCIS during culture. In conclusion, this study provides new insights into the dynamic changes in cellular composition of epithelium in cultured PCIS, paving the way to future toxicological and pharmacological studies in an informed and reliable ex vivo setting.

Docosahexaenoyl serotonin, an endogenously formed n-3 fatty acid-serotonin conjugate has anti-inflammatory properties by attenuating IL-23-IL-17 signaling in macrophages

Conjugates of fatty acids and amines, including endocannabinoids, are known to play important roles as endogenous signaling molecules. Among these, the ethanolamine conjugate of the n-3 poly unsaturated long chain fatty acid (PUFA) docosahexaenoic acid (22:6n-3) (DHA) was shown to possess strong anti-inflammatory properties. Previously, we identified the serotonin conjugate of DHA, docosahexaenoyl serotonin (DHA-5-HT), in intestinal tissues and showed that its levels are markedly influenced by intake of n-3 PUFAs. However, its biological roles remain to be elucidated. Here, we show that DHA-5-HT possesses potent anti-inflammatory properties by attenuating the IL-23-IL-17 signaling cascade in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Transcriptome analysis revealed that DHA-5-HT down-regulates LPS-induced genes, particularly those involved in generating a CD4+ Th17 response. Hence, levels of PGE2, IL-6, IL-1β, and IL-23, all pivotal macrophage-produced mediators driving the activation of pathogenic Th17 cells in a concerted way, were found to be significantly suppressed by concentrations as low as 100-500nM DHA-5-HT. Furthermore, DHA-5-HT inhibited the ability of RAW264.7 cells to migrate and downregulated chemokines like MCP-1, CCL-20, and gene-expression of CCL-22 and of several metalloproteinases. Gene set enrichment analysis (GSEA) suggested negative overlap with gene sets linked to inflammatory bowel disease (IBD) and positive overlap with gene sets related to the Nrf2 pathway. The specific formation of DHA-5-HT in the gut, combined with increasing data underlining the importance of the IL-23-IL-17 signaling pathway in the etiology of many chronic inflammatory diseases merits further investigation into its potential as therapeutic compound in e.g. IBD or intestinal tumorigenesis.

LKB1 and AMPK family signaling: the intimate link between cell polarity and energy metabolism

Research on the LKB1 tumor suppressor protein mutated in cancer-prone Peutz-Jeghers patients has continued at a feverish pace following exciting developments linking energy metabolism and cancer development. This review summarizes the current state of research on the LKB1 tumor suppressor. The weight of the evidence currently indicates an evolutionary conserved role for the protein in the regulation of various aspects of cellular polarity and energy metabolism. We focus on studies examining the concept that both cellular polarity and energy metabolism are regulated through the conserved LKB1-AMPK signal transduction pathway. Recent studies from a variety of model organisms have given new insight into the mechanism of polyp development and cancer formation in Peutz-Jeghers patients and the role of LKB1 mutation in sporadic tumorigenesis. Conditional LKB1 mouse models have outlined a tissue-dependent context for pathway activation and suggest that LKB1 may affect different AMPK isoforms independently. Elucidation of the molecular mechanism responsible for Peutz-Jeghers syndrome will undoubtedly reveal important insight into cancer development in the larger population.