Irinotecan-induced mucositis encompasses changes in intestinal and colonic cell kinetics and this is associated with altered extracellular matrix component expression

Abstract

OBJECTIVES: Chemotherapy-induced mucositis is characterised by damage of mucous membranes throughout the AT. Extracellular matrix (ECM) components play a vital role in maintaining mucosal barrier integrity by regulating cellular apoptosis, proliferation and differentiation of overlying epithelial cells. The aims of this study is to characterise the changes in epithelial cell kinetics and to investigate the expression of the ECM components in the gastrointestinal tract following irinotecan. METHODS: Dark agouti rats were treated with irinotecan and killed at various timepoints after treatment. Ki67 proliferation marker immunostaining and TUNEL were used to assess proliferation and apoptosis, respectively, in the jejunum and colon. Masson’s Trichrome and Picosirius red staining were used to illustrate the level of collagen and ECM components, and immu nohistochemistry was used to further assess collagen IV, fibronectin and Laminin 1 & 2 expression in these tissues. RESULTS: Irinotecan halved cellular proliferation in the jejunum and colon at 48 and 24 h, respectively, while apoptosis peaked at 6h. Masson’s trichrome and picosirius red staining indicated a substantial increase in collagen and other basement membrane components around crypts from 24h in both regions and this diminished at the later timepoints of 96 and 144h. Collagen IV expression decreased significantly in the crypt region in a delayed fashion while laminin 1 & 2 show a biphasic decrease at 6 and 96h. Fibronectin expression decreased significantly in jejunal villi and the basal colon from 6h following treatment. An increase in fibronectin was observed in the basal region of the colon at 24h onwards. CONCLUSIONS: Irinotecan induced a significant alteration in epithelial cell kinetics in both the jejunum and colon which was correlated with changes in ECM component expression. Changes in ECM expression may have a direct impact on the loss of mucosal layer integrity seen in mucositis.