Local Immune Changes in Early Stages of Inflammation and Carcinogenesis Correlate with the Collagen Scaffold Changes of the Colon Mucosa

Abstract

Continuous activation of the immune system inside a tissue can lead to remodelling of the tissue structure and creation of a specific microenvironment, such as during the tumour development. Chronic inflammation is a central player in stimulating changes that alter the tissue stroma and can lead to fibrotic evolution. In the colon mucosa, regulatory mechanisms, including TGF-β1, avoid damaging inflammation in front of the continuous challenge by the intestinal microbiome. Inducing either DSS colitis or AOM colorectal carcinogenesis in AVN-Wistar rats, we evaluated at one month after the end of each treatment whether immunological changes and remodelling of the collagen scaffold were already in development. At this time point, we found in both models a general downregulation of pro-inflammatory cytokines and even of TGF-β1, but not of IL-6. Moreover, we demonstrated by multi-photon microscopy the simultaneously presence of pro-fibrotic remodelling of the collagen scaffold, with measurable changes in comparison to the control mucosa. The scaffold was significantly modified depending on the type of induced stimulation. These results suggest that at one month after the end of the DSS or AOM inductions, a smouldering inflammation is present in both induced conditions, since the pro-inflammatory cytokines still exceed, in proportion, the local homeostatic regulation of which TGF-β1 is a part (inflammatory threshold). Such an inflammation appears sufficient to sustain remodelling of the collagen scaffold that may be taken as a possible pathological marker for revealing pre-neoplastic inflammation.

Novel PD-L1- and collagen-expressing patient-derived cell line of undifferentiated pleomorphic sarcoma (JBT19) as a model for cancer immunotherapy

“…5 d, comprehensive of all observed mice until the 24 th day of the experiment. These tumors were found to contain the collagen tissue structures as determined by two-photon confocal microscopy in the second harmonic generation mode (SHG) 36 (Fig. 5 e).…”

“…The single-photon confocal microscopy used 405 nm (blue), 473 nm (green), and 635 nm (red) laser, and the acquired images were processed using the Olympus FLUOVIEW Ver.4.2 viewer software. For two-photon confocal microscopy, the Bruker Ultima IntraVital device in second harmonic generation mode (SHG) was used to visualize the collagen tissue structure in unstained fresh tissue sections using the 810 nm wavelength as described 36 . The acquired images were analyzed using the ImageJ software (NIH, MA, USA) and LAS X Leica (Wetzlar, Germany).…”