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.

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.