Chemotherapy-induced Intestinal Epithelial Damage Directly Promotes Galectin-9-driven Modulation of T Cell Behavior

The intestine is vulnerable to chemotherapy-induced damage due to the high rate of intestinal epithelial cell (IEC) proliferation. We have developed a human intestinal organoid-based 3D-model system to study the direct effect of chemotherapy-induced IEC damage on T-cell behavior. Exposure of intestinal organoids to busulfan, fludarabine, and clofarabine induced damage-related responses affecting both the capacity to regenerate and transcriptional reprogramming. In ex-vivo co-culture assays, prior intestinal organoid damage resulted in increased T-cell activation, proliferation, and migration. We identified galectin-9 (Gal-9) as a key molecule released by damaged organoids. The use of anti-Gal-9 blocking antibodies or CRISPR/Cas9-mediated Gal-9 knock-out prevented intestinal organoid damage-induced T-cell proliferation, interferon-gamma release, and migration. Increased levels of Gal-9 were found early after HSCT chemotherapeutic conditioning in the plasma of patients who later developed acute GVHD. Taken together, chemotherapy-induced intestinal damage can influence T-cell behavior in a Gal-9-dependent manner which may provide novel strategies for therapeutic intervention.