title: Irinotecan-Induced Gastrointestinal Dysfunction and Pain Are Mediated by Common TLR4-Dependent Mechanisms.
abstract: Strong epidemiological data indicate that chemotherapy-induced gut toxicity and pain occur in parallel, indicating common underlying mechanisms. We have recently outlined evidence suggesting that TLR4 signaling may contribute to both side effects. We therefore aimed to determine if genetic deletion of TLR4 improves chemotherapy-induced gut toxicity and pain. Forty-two female wild-type (WT) and 42 Tlr4 null (-/-) BALB/c mice weighing between 18 and 25 g (10-13 weeks) received a single 270 mg/kg (i.p.) dose of irinotecan hydrochloride or vehicle control and were killed at 6, 24, 48, 72, and 96 hours. Bacterial sequencing was conducted on cecal samples of control animals to determine the gut microbiome profile. Gut toxicity was assessed using validated clinical and histopathologic markers, permeability assays, and inflammatory markers. Chemotherapy-induced pain was assessed using the validated rodent facial grimace criteria, as well as immunologic markers of glial activation in the lumbar spinal cord. TLR4 deletion attenuated irinotecan-induced gut toxicity, with improvements in weight loss (P = 0.0003) and diarrhea (P < 0.0001). Crypt apoptosis was significantly decreased in BALB/c-Tlr4(-/-billy) mice (P < 0.0001), correlating with lower mucosal injury scores (P < 0.005). Intestinal permeability to FITC-dextran (4 kDa) and LPS translocation was greater in WT mice than in BALB/c-Tlr4(-/-billy) (P = 0.01 and P < 0.0001, respectively). GFAP staining in the lumbar spinal cord, indicative of astrocytic activation, was increased at 6 and 72 hours in WT mice compared with BALB/c-Tlr4(-/-billy) mice (P = 0.008, P = 0.01). These data indicate that TLR4 is uniquely positioned to mediate irinotecan-induced gut toxicity and pain, highlighting the possibility of a targetable gut/CNS axis for improved toxicity outcomes. Mol Cancer Ther; 15(6); 1376-86. ©2016 AACR.
authors.affiliation: Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia. Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia. hannah.wardill@adelaide.edu.au.
authors.forename: Hannah R
authors.initials: HR
authors.lastname: Wardill
authors.affiliation: Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia. Division of Health Sciences, University of South Australia, Australia.
authors.forename: Rachel J
authors.initials: RJ
authors.lastname: Gibson
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Ysabella Z A
authors.initials: YZ
authors.lastname: Van Sebille
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Kate R
authors.initials: KR
authors.lastname: Secombe
authors.affiliation: Discipline of Pharmacology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Janet K
authors.initials: JK
authors.lastname: Coller
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Imogen A
authors.initials: IA
authors.lastname: White
authors.affiliation: Adelaide Centre for Neuroscience Research and Discipline of Anatomy and Pathology, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Jim
authors.initials: J
authors.lastname: Manavis
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia. Australian Research Council Centre of Excellence for Nanoscale Biophotonics, Adelaide, South Australia, Australia.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Hutchinson
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Staikopoulos
authors.affiliation: School of Dentistry, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Logan
authors.affiliation: Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Bowen
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000009:adverse effects* / Q000494:pharmacology; D017209:Apoptosis; D001419:Bacteria / Q000187:drug effects / Q000235:genetics; D002166:Camptothecin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D005243:Feces / Q000382:microbiology; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D000069196:Gastrointestinal Microbiome / Q000187:drug effects; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects; D000077146:Irinotecan; D051379:Mice; D008807:Mice, Inbred BALB C; D010146:Pain / Q000139:chemically induced* / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000235:genetics* / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D000077146:Irinotecan; D002166:Camptothecin