P036 Identification and functional analysis of stromal subsets in experimental IBD mouse models
Zhou, Z.(1);Plug, L.G.(1);de Jonge-Muller, E.S.M.(1);van de Beek, L.M.(1);Brands, L.(1);van der Meulen-de Jong, A.E.(1);Hawinkels, L.J.A.C.(1);Barnhoorn, M.C.(1);
(1)Leiden University Medical Center, Department of Gastroenterology and Hepatology, Leiden, The Netherlands;
Single cell RNA sequencing data from the inflamed colon of inflammatory bowel disease (IBD) patients revealed the presence of different stromal cell/fibroblast subsets and showed their importance in IBD pathology. Up to now, it is unknown if and how the stroma cells affect disease progression. In this study we compared the stromal cell subsets in three IBD mouse models and explored the interaction between these stromal subsets and epithelial cells.
Stromal cell subset markers, including CD55, C-X-C motif chemokine 12 (CXCL12), podoplanin (PDPN), CD90 and CD73, were analyzed in the inflamed murine colon by flow cytometry in interleukin (IL)-10 knockout (KO) mice, dextran sulfate sodium(DSS)-induced colitis and the T cell transfer model. In order to explore the changes in stromal subsets upon colitis induction in vitro, short hairpin RNAs were used to silence target gene expression of these cellular markers in murine fibroblasts. Fibroblast proliferation and migration was studied in addition to the effects on immune cell trafficking and tissue regeneration.
In all three colitis models, an increase in the total amount of stromal cells was observed. The percentages of PDPN+ and CD73+ stromal cells significantly increased during colitis in the IL-10 KO mice, while the percentage of CD55+, CD90+ and CXCL12+ stromal cells decreased. For the T cell transfer model, the abundance of CD73+, CD90+ and CD55+ stromal cells was enriched, while the percentage of CXCL12+ stromal cells was reduced. Interestingly, in contrast to the two other, in the DSS-mice the percentage of CXCL12+ stromal cells was significantly increased. In vitro experiments showed the importance of CD55 and CXCL12 for fibroblast proliferation and CD55 for their migration. Furthermore, the fibroblast supernatant obtained after the knockdown of CXCL12 decreased epithelial cell wound healing. On the contrary, knock-down of CD90 in the fibroblasts improved epithelial migration. Current experiments explore the immune regulatory properties of the fibroblast subsets.
The composition of stromal cell subsets is significantly changed in experimental colitis and differs between three established colitis mouse models. Therefore they may possibly reflect different human IBD subtypes observed in the clinic. Finally the defined subsets influence fibroblast behavior and epithelial regeneration.