DOP075 Tissue fibrosis modulates interleukin (IL)-13 signaling in intestinal epithelial cells
Authors: Saha S , Clark A 
Published: January 2025

Abstract

Background
Inflammatory Bowel Diseases (IBDs) are characterized by chronic inflammation of the intestinal tissue and persistent disruption of the intestinal epithelial barrier. A common and dangerous complication of chronic inflammation during IBD is fibrosis, a mechanical stiffening of the intestinal tissue [1,2]. Previous work suggests that immune cell activity, for example Interleukin (IL)-13-mediated macrophage activation, can be mechanosensitive [3,4]. However, it is not currently well understood how fibrosis affects the inflammatory response in intestinal epithelial cells.

Methods
To address how tissue stiffness impacts intestinal inflammation, we studied the effects of inflammatory cytokine signaling in intestinal epithelial cells using a recently developed intestinal organoid monolayer model. We cultured intestinal organoid monolayers on soft (0.5kPa), intermediate (5kPa) or stiff (15kPa) hydrogels to mimic physiological or fibrotic conditions and studied the cellular response to IL-13, an inflammatory cytokine implicated in IBD and loss of barrier integrity. To investigate the impacts of substrate stiffness and IL-13 signaling on epithelial cell function, we combined high-resolution live microscopy, quantitative image analysis using AI-based models and biophysical measurements.

Results
We found that substrate mechanosensing and IL-13 signaling interact synergistically to modulate intestinal epithelial stem cell differentiation, leading to a dramatic increase in the frequency of secretory cells. Furthermore, organoids cultured on stiff substrates no longer respond to IL-13 treatment, suggesting that fibrotic conditions may promote an inflamed-like state even in the absence of inflammatory cytokines. To further investigate cross-talk between substrate mechanics and IL-13 signalling, we inhibited downstream IL-13 signalling and cell contractility. We found that both the stiffness- and IL-13-induced phenotypes could be rescued by either inhibiting myosin-2 activity or blocking downstream IL-13 signalling, further indicating a co-dependence and synergy of substrate stiffness and IL-13. Further experiments implicate the relocalization of myosin-2 to the cell cortex and increased nuclear accumulation of the mechanosensitive protein YAP in mediating this response. Experiments using mouse models of colitis further support a role for YAP in this process.

Conclusion
Taken together, this work reveals how tissue mechanics modulate the inflammatory response in the intestinal epithelium. Future translational work based on these findings will inspire new approaches to mitigate the effects of fibrosis during IBD.

References
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[2]Stewart DC, Berrie D, Li J, et al. Quantitative assessment of intestinal stiffness and associations with fibrosis in human inflammatory bowel disease. PLoS One. 2018;13(7):e0200377. doi:10.1371/journal.pone.0200377
[3]Kim JK, Han SB, Park SI, Kim IS, Kim DH. Nuclear transport of STAT6 determines the matrix rigidity dependent M2 activation of macrophages. Biomaterials. 2022;290:121859. doi:10.1016/j.biomaterials.2022.121859
[4]Saha S, Müller D, Clark AG. Mechanosensory feedback loops during chronic inflammation. Front Cell Dev Biol. 2023;11:1225677. doi:10.3389/fcell.2023.1225677