title: Severity of doxorubicin-induced small intestinal mucositis is regulated by the TLR-2 and TLR-9 pathways.
abstract: Intestinal mucositis is a serious complication of cancer chemotherapy and radiotherapy; it frequently compromises treatment and dramatically reduces the quality of life of patients. Different approaches to limit the damage to the intestine during anti-cancer therapy have been largely ineffective due to insufficient knowledge of the mechanism of mucositis development. This study aimed to define the role of TLR-2 and TLR-9 in the modulation of small intestinal damage in a model of doxorubicin-induced mucositis. Doxorubicin-induced intestinal damage was verified by a histological score (HS), analysis of leukocyte influx into the lamina propria, and determination of the number of apoptotic cells. Additionally, the activation status of glycogen synthase kinase 3β (GSK-3β) was assessed. Wild-type (WT) mice injected with doxorubicin demonstrated severe intestinal damage (HS 8.0 ± 0.81), reduction of villus length to 43.9% ± 13.7% of original length, and increased influx of leukocytes as compared to vehicle-injected mice (HS 1.33 ± 1.15). The protective effect of TLR-2 or TLR-9 deficiency was associated with a significant decrease of the HS as compared to WT mice. In the ileum, a minor reduction of villus length and a decreased number of infiltrating leukocytes and TUNEL-positive cells was observed. We demonstrate that the TLR-9 antagonist ODN2088 reduces doxorubicin-induced intestinal damage. Furthermore, we show that GSK-3β activity is inhibited in the absence of TLR-2. The protective capacity of GSK-3β suppression was observed in WT mice by inhibiting it with the specific inhibitor SB216763. Overall, our findings demonstrate that the TLR-2/GSK-3β and TLR-9 signalling pathways play a central role in the development of intestinal mucositis and we suggest a new therapeutic strategy for limiting doxorubicin-induced intestinal inflammation.
authors.affiliation: Department for Molecular Biomedical Research, VIB, Ghent, Belgium.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kaczmarek
authors.forename: Brigitta M
authors.initials: BM
authors.lastname: Brinkman
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Heyndrickx
authors.forename: Peter
authors.initials: P
authors.lastname: Vandenabeele
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Krysko
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000009:adverse effects*; D017209:Apoptosis / Q000187:drug effects; D002634:Chemotaxis, Leukocyte; D004317:Doxorubicin / Q000009:adverse effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D007082:Ileum / Q000187:drug effects / Q000473:pathology*; D007211:Indoles / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D007962:Leukocytes / Q000187:drug effects / Q000473:pathology; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052016:Mucositis / Q000139:chemically induced / Q000473:pathology*; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000172:deficiency / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; C417521:SB 216763; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D004317:Doxorubicin; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3