Target Inhibition of IL-1 Receptor Prevents Ifosfamide Induced Hemorrhagic Cystitis in Mice.

PURPOSE: Hemorrhagic cystitis is an important dose limiting side effect of ifosfamide based cancer chemotherapy. Despite chemoprophylaxis inflammation can still be found in cystoscopy guided biopsies. Previous studies confirmed the role of TNF-α and IL-1ß. We evaluated the protective effect of the IL-1R antagonist anakinra and the anti-TNF-α antibody infliximab in experimental ifosfamide induced hemorrhagic cystitis. MATERIALS AND METHODS: Hemorrhagic cystitis was induced by an injection of ifosfamide (400 mg/kg intraperitoneally) in Swiss wild-type C57Bl/6, IL-1R-/-, TNFR1-/- or TNFR1/R2-/- mice. Mice were treated 30 minutes before ifosfamide with anakinra (100 mg/kg intraperitoneally), infliximab (5 mg/kg intraperitoneally) or vehicle. Visceral nociception was evaluated after hemorrhagic cystitis induction. At 12 hours the animals were sacrificed. Bladders were harvested to assess bladder wet weight, vascular permeability, macroscopic and microscopic findings, muscle contractility, and for cystometrography. Inflammatory cell infiltration was assessed by myeloperoxidase assay and flow cytometry. RESULTS: Anakinra attenuated hemorrhage, edema, neutrophil infiltration, visceral hyperalgesia and bladder dysfunction. IL-1R-/- mice also showed milder hemorrhagic cystitis. Infliximab inhibited bladder edema and visceral hyperalgesia without preventing hemorrhage, bladder dysfunction, neutrophils or accumulation. Additionally, the lack of TNFR1 decreased bladder edema but not cell infiltration whereas concomitant deficiency of TNFR1 and TNFR2 resulted in worse hemorrhagic cystitis. CONCLUSIONS: Anakinra is effective for preventing experimentally ifosfamide induced hemorrhagic cystitis. It seems that neutrophil and macrophage infiltration in this circumstance depends on IL-1 signaling through IL1R. Possibly TNFR2 has a protective role in hemorrhagic cystitis.

Irinotecan- and 5-fluorouracil-induced intestinal mucositis: insights into pathogenesis and therapeutic perspectives.

PURPOSE: Intestinal mucositis and diarrhea are common manifestations of anticancer regimens that include irinotecan, 5-fluorouracil (5-FU), and other cytotoxic drugs. These side effects negatively impact therapeutic outcomes and delay subsequent cycles of chemotherapy, resulting in dose reductions and treatment discontinuation. Here, we aimed to review the experimental evidence regarding possible new targets for the management of irinotecan- and 5-FU-related intestinal mucositis. METHODS: A literature search was performed using the PubMed and MEDLINE databases. No publication time limit was set for article inclusion. RESULTS: Here, we found that clinical management of intestinal mucositis and diarrhea is somewhat ineffective at reducing symptoms, possibly due to a lack of specific targets for modulation. We observed that IL-1ß contributes to the apoptosis of enterocytes in mucositis induced by 5-FU. However, 5-FU-related mucositis is far less thoroughly investigated with regard to specific molecular targets when compared to irinotecan-related disease. Several studies have proposed that a correlation exists between the intestinal microbiota, the enterohepatic recirculation of active metabolites of irinotecan, and the establishment of mucositis. However, as reviewed here, this association seems to be controversial. In addition, the pathogenesis of irinotecan-induced mucositis appears to be orchestrated by interleukin-1/Toll-like receptor family members, leading to epithelial cell apoptosis. CONCLUSIONS: IL-1ß, IL-18, and IL-33 and the receptors IL-1R, IL-18R, ST2, and TLR-2 are potential therapeutic targets that can be modulated to minimize anticancer agent-associated toxicity, optimize cancer treatment dosing, and improve clinical outcomes. In this context, the pathogenesis of mucositis caused by other anticancer agents should be further investigated.

The Adaptor Protein Myd88 Is a Key Signaling Molecule in the Pathogenesis of Irinotecan-Induced Intestinal Mucositis.

Intestinal mucositis is a common side effect of irinotecan-based anticancer regimens. Mucositis causes cell damage, bacterial/endotoxin translocation and production of cytokines including IL-1 and IL-18. These molecules and toll-like receptors (TLRs) activate a common signaling pathway that involves the Myeloid Differentiation adaptor protein, MyD88, whose role in intestinal mucositis is unknown. Then, we evaluated the involvement of TLRs and MyD88 in the pathogenesis of irinotecan-induced intestinal mucositis. MyD88-, TLR2- or TLR9-knockout mice and C57BL/6 (WT) mice were given either saline or irinotecan (75 mg/kg, i.p. for 4 days). On day 7, animal survival, diarrhea and bacteremia were assessed, and following euthanasia, samples of the ileum were obtained for morphometric analysis, myeloperoxidase (MPO) assay and measurement of pro-inflammatory markers. Irinotecan reduced the animal survival (50%) and induced a pronounced diarrhea, increased bacteremia, neutrophil accumulation in the intestinal tissue, intestinal damage and more than twofold increased expression of MyD88 (200%), TLR9 (400%), TRAF6 (236%), IL-1ß (405%), IL-18 (365%), COX-2 (2,777%) and NF-κB (245%) in the WT animals when compared with saline-injected group (P<0.05). Genetic deletion of MyD88, TLR2 or TLR9 effectively controlled the signs of intestinal injury when compared with irinotecan-administered WT controls (P<0.05). In contrast to the MyD88-/- and TLR2-/- mice, the irinotecan-injected TLR9-/- mice showed a reduced survival, a marked diarrhea and an enhanced expression of IL-18 versus irinotecan-injected WT controls. Additionally, the expression of MyD88 was reduced in the TLR2-/- or TLR9-/- mice. This study shows a critical role of the MyD88-mediated TLR2 and TLR9 signaling in the pathogenesis of irinotecan-induced intestinal mucositis.