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* = Presenting author

P037 Remodelling events preceding clinical onset of intestinal inflammation reveal the predictive power of the extracellular matrix

E. Shimshoni*1, R. Afik1, L. Puricelli2, A. Shenoy3, T. Geiger3, A. Podestà2, I. Sagi1

1Weizmann Institute of Science, Biological Regulation, Rehovot, Israel, 2University of Milan, Physics, Milan, Italy, 3Tel Aviv University, Human Genetics, Tel Aviv, Israel

Background

The extracellular matrix (ECM), which is a substantial tissue component, is not a static entity, but rather it constantly undergoes remodelling in homeostasis, as well as in pathology, such as intestinal inflammation, thus contributing to tissue architecture and function. Previous studies show that dysregulation of ECM remodelling enzymes in human inflammatory bowel disease (IBD), as well as in several murine models of the disease, is taking place. By obtaining a detailed molecular characterisation of changes in biochemical and biophysical properties of the ECM, we unexpectedly revealed that significant changes in ECM molecular composition, morphology, and stiffness appear before detection of intestinal inflammation by endoscopy, and form a unique ECM signature.

Methods

We examined gut ECM architecture, composition, and mechanical dynamics during acute and chronic inflammation, by utilising the dextran sodium sulphate (DSS)-induced colitis and interleukin (IL)-10-deficient mouse models, respectively. First, we assessed changes in ECM structure by second-harmonic imaging of native collagen and scanning electron microscopy. Next, we assessed ECM mechanical properties using meso-scale atomic-force microscopy with a colloidal probe. Finally, we compared ECM proteomic composition amongst all colonic tissue states using mass spectrometry.

Results

We demonstrate the structural transition the ECM undergoes during colitis by utilising high-resolution second-harmonic imaging and scanning electron microscopy. Using meso-scale atomic-force microscopy, we show that there is a reduction in ECM stiffness as acute colitis progresses. ECM composition is altered during colitis, as demonstrated by mass spectrometry analysis, showing significantly altered abundance of many ECM related proteins in acute and chronic colitis. Remarkably, pre-symptomatic colonic ECMs of 2 different colitis models, the early stage of the DSS model and the healthy non-symptomatic IL-10-deficient mouse, display very high structural and compositional similarity, which is distinct from that of the healthy wild-type mouse.

Figure 1. (A) Second-harmonic images of mouse colon on the indicated time points over the course of DSS-induced colitis. (B) Comparisons of differentially abundant ECM proteins between the 5 different states.

Conclusion

The colonic ECM we observed in early stages of inflammation, before onset of symptoms, holds the potential to be used as predictor of flares in IBD patients. The generation of such ECM, shared between acute and chronic inflammation, indicates the generation of a pro-inflammatory matrix, potentially providing the appropriate microenvironmental signals for development of intestinal inflammation.