RESUMEN
Patients with long-standing inflammatory bowel disease (IBD) face an increased risk of developing colitis-associated cancer (CAC). Although IBD-induced prolonged inflammation seems to be involved in CAC pathogenesis, the specific molecular changes that contribute remain unknown. Here, we applied digital spatial RNA profiling, RNAscope, and imaging mass cytometry to examine paired uninflamed, inflamed, and early dysplastic mucosa of patients with IBD. We observed robust type 3 (IL-17) responses during inflammation, accompanied by elevated JAK-STAT signaling and phosphorylated STAT3 (P-STAT3) levels, with both inflamed and dysplastic mucosa displaying immune cell activation. Higher stromal P-STAT3 was detected in uninflamed and inflamed mucosa of patients who eventually developed dysplasia. CD8a+ T cells did not infiltrate inflamed or dysplastic epithelial regions in these patients, while control patients showed elevated CD8a in inflamed mucosa. Our study reveals distinct inflammatory patterns throughout CAC development, marked by an activated IL-17 pathway, engaged STAT3, and diminished cytotoxic T cell infiltration.
RESUMEN
BACKGROUND: The determinants of metastasis in mismatch repair deficiency with high levels of microsatellite instability (MSI-H) in colorectal cancer (CRC) are poorly understood. Here, we hypothesized that distinct immune and stromal microenvironments in primary tumors may discriminate between non-metastatic MSI-H CRC and metastatic MSI-H CRC. METHODS: We profiled 46,727 single cells using high-plex imaging mass cytometry and analyzed both differential cell type abundance, and spatial distribution of fibroblasts and immune cells in primary CRC tumors with or without metastatic capacity. We validated our findings in a second independent cohort using immunohistochemistry. RESULTS: High-plex imaging mass cytometry and hierarchical clustering based on microenvironmental markers separated primary MSI-H CRC tumors with and without metastatic capacity. Primary tumors with metastatic capacity displayed a high stromal content and low influx of CD8+ T cells, which expressed significantly lower levels of markers reflecting proliferation (Ki67) and antigen-experience (CD45RO) compared to CD8+ T cells in non-metastatic tumors. CD8+ T cells showed intra-epithelial localization in non-metastatic tumors, but stromal localization in metastatic tumors, which was validated in a second cohort. CONCLUSION: We conclude that localization of phenotypically distinct CD8+ T cells within stroma may predict metastasis formation in MSI-H CRC.
