The role of Smad7 in oral mucositis

Oral mucositis, a severe oral ulceration, is a common toxic effect of radio- or chemoradio-therapy and a limiting factor to using the maximum dose of radiation for effective cancer treatment. Among cancer patients, at least 40% and up to 70%, of individuals treated with standard chemotherapy regimens or upper-body radiation, develop oral mucositis. To date, there is no FDA approved drug to treat oral mucositis in cancer patients. The key challenges for oral mucositis treatment are to repair and protect ulcerated oral mucosa without promoting cancer cell growth. Oral mucositis is the result of complex, multifaceted pathobiology, involving a series of signaling pathways and a chain of interactions between the epithelium and submucosa. Among those pathways and interactions, the activation of nuclear factor-kappa B (NF-κB) is critical to the inflammation process of oral mucositis. We recently found that activation of TGFβ(transforming growth factor β) signaling is associated with the development of oral mucositis. Smad7, the negative regulator of TGFβ signaling, inhibits both NF-κB and TGFβ activation and thus plays a pivotal role in the prevention and treatment of oral mucositis by attenuating growth inhibition, apoptosis, and inflammation while promoting epithelial migration. The major objective of this review is to evaluate the known functions of Smad7, with a particular focus on its molecular mechanisms and its function in blocking multiple pathological processes in oral mucositis.     

Effect of Prophylactic Low Level Laser Therapy on Oral Mucositis: A Systematic Review and Meta-Analysis

Background

Objective was to determine whether prophylactic low level laser therapy (LLLT) reduces the risk of severe mucositis as compared to placebo or no therapy.

Methods

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched until February 2014 for randomized controlled trials (RCTs) comparing prophylactic LLLT with placebo or no therapy in patients with cancer or undergoing hematopoietic stem cell transplantation (HSCT). All analyses used random effects models.

Results

Eighteen RCTs (1144 patients) were included. Prophylactic LLLT reduced the overall risk of severe mucositis (risk ratio (RR) 0.37, 95% confidence interval (CI) 0.20 to 0.67; P = 0.001). LLLT also reduced the following outcomes when compared to placebo/no therapy: severe mucositis at the time of anticipated maximal mucositis (RR 0.34, 95% CI 0.20 to 0.59), overall mean grade of mucositis (standardized mean difference −1.49, 95% CI −2.02 to −0.95), duration of severe mucositis (weighted mean difference −5.32, 95% CI −9.45 to −1.19) and incidence of severe pain (RR 0.26, 95% CI 0.18 to 0.37).

Conclusion

Prophylactic LLLT reduced severe mucositis and pain in patients with cancer and HSCT recipients. Future research should identify the optimal characteristics of LLLT and determine feasibility in the clinical setting.     

A Review of Clinical Radioprotection and Chemoprotection for Oral Mucositis

The first tenet of medicine, “primum non nocere” or “first, do no harm”, is not always compatible with oncological interventions e.g., chemotherapy, targeted therapy and radiation, since they commonly result in significant toxicities. One of the more frequent and serious treatment-induced toxicities is mucositis and particularly oral mucositis (OM) described as inflammation, atrophy and breakdown of the mucosa or lining of the oral cavity. The sequelae of oral mucositis (OM), which include pain, odynodysphagia, dysgeusia, decreased oral intake and systemic infection, frequently require treatment delays, interruptions and discontinuations that not only negatively impact quality of life but also tumor control and survivorship. One potential strategy to reduce or prevent the development of mucositis, for which no effective therapies exist only best supportive empirical care measures, is the administration of agents referred to as radioprotectors and/or chemoprotectors, which are intended to differentially protect normal but not malignant tissue from cytotoxicity. This limited-scope review briefly summarizes the incidence, pathogenesis, symptoms and impact on patients of OM as well as the background and mechanisms of four clinical stage radioprotectors/chemoprotectors, amifostine, palifermin, GC4419 and RRx-001, with the proven or theoretical potential to minimize the development of mucositis particularly in the treatment of head and neck cancers.     

Alteration of the Redox State with Reactive Oxygen Species for 5-Fluorouracil-Induced Oral Mucositis in Hamsters

Oral mucositis is often induced in patients receiving cancer chemotherapy treatment. It has been reported that oral mucositis can reduce quality of life, as well as increasing the incidence of mortality. The participation of reactive oxygen species (ROS) in the pathogenesis of oral mucositis is well known, but no report has actually demonstrated the presence of ROS. Thus, the purpose of this study was thus to demonstrate the involvement of ROS and the alteration of the redox state in oral mucositis using an in vivo L-band electron spin resonance (ESR) technique. An oral mucositis animal model induced by treatment of 5-fluorouracil with 10% acetic acid in hamster cheek pouch was used. Lipid peroxidation was measured as the level of malondialdehyde determined by the thiobarbituric acid reaction. The rate constants of the signal decay of nitroxyl compounds using in vivo L-band ESR were calculated from the signal decay curves. Firstly, we established the oral mucositis animal model induced by treatment of 5-fluorouracil with acetic acid in hamster cheek pouch. An increased level of lipid peroxidation in oral mucositis was found by measuring malondialdehyde using isolated hamster cheek pouch ulcer. In addition, as a result of in vivo L-band ESR measurements using our model animals, the decay rate constants of carbamoyl-PROXYL, which is a reagent for detecting the redox balance in tissue, were decreased. These results suggest that a redox imbalance might occur by excessive generation of ROS at an early stage of oral mucositis and the consumption of large quantities of antioxidants including glutathione in the locality of oral mucositis. These findings support the presence of ROS involved in the pathogenesis of oral mucositis with anti-cancer therapy, and is useful for the development of novel therapies drugs for oral mucositis.     

Dark Agouti rat model of chemotherapy-induced mucositis: Establishment and current state of the art

Mucositis is a major oncological problem. The entire gastrointestinal and genitourinary tract and also other mucosal surfaces can be affected in recipients of radiotherapy, and/or chemotherapy. Major progress has been made in recent years in understanding the mechanisms of oral and small intestinal mucositis, which appears to be more prominent than colonic damage. This progress is largely due to the development of representative laboratory animal models of mucositis. This review focuses on the development and establishment of the Dark Agouti rat mammary adenocarcinoma model by the Mucositis Research Group of the University of Adelaide over the past 20 years to characterize the mechanisms underlying methotrexate-, 5-fluorouracil-, and irinotecan-induced mucositis. It also aims to summarize the results from studies using different animal model systems to identify new molecular and cellular markers of mucositis.     

Efficacy and safety of propolis mouthwash in management of radiotherapy induced oral mucositis; A randomized,double blind clinical trial

Aim and BackgroundPropolis has been used for the management of oral mucositis in a number of studies. Due to lack of sufficient evidence especially in radiotherapy induced oral mucositis, the present study was designed to evaluate the efficacy and safety of propolis mouthwash in oral mucositis and dysphagia in patients undergoing head and neck radiotherapy.Materials and methodsThis study was a prospective, randomised, double-blind, placebo-controlled trial. The patients randomly divided into two groups receiving either the propolis or the placebo mouthwash. Patients were advised to rinse their mouth with 15 mL three times daily for four weeks. Severity of mucositis and dysphagia were evaluated by the National Cancer Institute Common Toxicity Criteria (NCI-CTC) and Common Terminology Criteria for Adverse Events (CTCAE), respectively.ResultsThirty patients completed the study. Each group consisted of 15 patients. Although, there is not any significant difference between two groups in the first week of radiotherapy, a significant difference was seen in the second, the third and the fourth week (p = 0.03, 0.02, 0.02, respectively). Dysphagia reported as a mild score in the propolis group only in the fourth week which is significant compared with the placebo group (p = 0.01). There is not any serious adverse effect related to propolis or placebo during the study.ConclusionIt seems that propolis mouthwash is an effective and safe medication for alleviation of oral mucositis and dysphagia in patients under head and neck radiotherapy.     

Lactose maldigestion during methotrexate-induced gastrointestinal mucositis in a rat model

Patients with chemotherapy-induced gastrointestinal mucositis suffer from anorexia, diarrhea, and stomach pain, often causing weight loss and malnutrition. When the intestinal function during mucositis would be known, a rational feeding strategy might improve the nutritional state, accelerate recuperation, and increase survival of mucositis patients. We developed a methotrexate (MTX)-induced mucositis rat model to study nutrient digestion and absorption. To determine lactose digestion and absorption of its derivative glucose during mucositis, we injected Wistar rats intravenously with MTX (60 mg/kg) or 0.9% NaCl (controls). Four days later, we orally administered trace amounts of [1-(13)C]lactose and [U-(13)C]glucose and quantified the appearance of labeled glucose in the blood for 3 h. Finally, we determined plasma citrulline level and harvested the small intestine to assess histology, myeloperoxidase level, glycohydrolase activity, immunohistochemical protein, and mRNA expression. MTX-treated rats showed profound villus atrophy and epithelial damage. During the experimental period, the absorption of lactose-derived [1-(13)C]glucose was 4.2-fold decreased in MTX-treated rats compared with controls (P < 0.01). Lactose-derived [1-(13)C]glucose absorption correlated strongly with villus length (rho = 0.86, P < 0.001) and with plasma citrulline level (rho = 0.81, P < 0.001). MTX treatment decreased jejunal lactase activity (19.5-fold, P < 0.01) and immunohistochemical protein and mRNA expression (39.7-fold, P < 0.01) compared with controls. Interestingly, MTX treatment did not affect the absorption of [U-(13)C]glucose during the experimental period. We conclude that lactose digestion is severely decreased during mucositis while glucose absorption is still intact, when supplied in trace amounts. Plasma citrulline level might be a useful objective, noninvasive marker for lactose maldigestion during mucositis in clinic.     

Radio-chemotherapy of locally advanced head and neck cancer,providing tissue and organ protection

PURPOSE: the study of the effect of Amifostine in reducing acute mucositis, xerostomia and late xerostomia emerging in the course of locally advanced head and neck cancer radio-chemotherapy. METHODS: Starting in 1999 we have conducted radio-chemotherapy treatment on 7 patients with or without Amifostine protection, each receiving 60 Gy (2 Gy a day/5 fractions a week) loco-regional irradiation. From the first to the fifth day and from the twenty-first to the twenty-fifth day prior to irradiation they were given a 70 mg/m(2) Carboplatin treatment. In the Amifostine group, on days 1-5 and 21-25 300 mg/m(2) and on days 6-20 and 26-30 200 mg/m(2) Amifostine therapy was given prior to the radio- and chemotherapy. RESULTS: In the course of the trial we did not find any haematologic side effects, or side effects directly connected to the Amifostine, which would have required suspension of the therapy. In the active phase, mucositis of Grade 1-2 was detected 1-2 weeks later than in the control group, in contrast to the mucositis of Grade 2-3 in the other arm. Global oral discomfort associated with acute xerostomia was of Grade 4-6 on a linear scale of ten, compared with Grade 7-8 on the active line. We had similar results when testing the symptoms directly connected with late xerostomia. Unstimulated and stimulated saliva production doubled following the Amifostine treatment. CONCLUSION: Despite the small pool of patients we have the impression that Amifostine can effectively reduce the severity of acute mucositis, xerostomia and late xerostomia.     

Unusual oral mucosal microbiota after hematopoietic cell transplantation with glycopeptide antibiotics: potential association with pathophysiology of oral mucositis

Severe oral mucositis occurs frequently in patients receiving hematopoietic stem cell transplantation (HCT). Oral mucosal bacteria can be associated with progression of oral mucositis, and systemic infection may occur via ulcerative oral mucositis. However, little information is available regarding the oral microbiota after HCT. Here, PCR-denaturing gradient gel electrophoresis (DGGE) was performed to characterize the oral mucosal microbiota, which can be affected by antibiotics, before and after HCT. Sixty reduced-intensity HCT patients were enrolled. Three patients with the least antibiotic use (quinolone prophylaxis and/or β-lactam monotherapy group) and three patients with the most antibiotic use (β-lactam-glycopeptide combination therapy group) were selected. Bacterial DNA samples obtained from the oral mucosa before and after HCT were subjected to PCR-DGGE. The trajectory of oral mucositis was evaluated. The oral mucosal microbiota in the β-lactam-glycopeptide combination therapy group was different from that in the quinolone prophylaxis and/or β-lactam monotherapy group, and Staphylococcus spp. and Enterococcus spp. were identified. Lautropia mirabilis was dominant in one patient. Ulcerative oral mucositis was observed only in the β-lactam-glycopeptide combination therapy group. In conclusion, especially with the use of strong antibiotics, such as glycopeptides, the oral mucosal microbiota differed completely from that under normal conditions and consisted of Staphylococcus spp., Enterococcus spp., and unexpectedly L. mirabilis. The normal oral microbiota consists not only of bacteria, but these unexpected bacteria could be involved in the pathophysiology as well as systemic infection via oral mucositis. Our results can be used as the basis for future studies in larger patient populations.     

Tumor blood vessel "normalization" improves the therapeutic efficacy of boron neutron capture therapy (BNCT) in experimental oral cancer

We previously demonstrated the efficacy of BNCT mediated by boronophenylalanine (BPA) to treat tumors in a hamster cheek pouch model of oral cancer with no normal tissue radiotoxicity and moderate, albeit reversible, mucositis in precancerous tissue around treated tumors. It is known that boron targeting of the largest possible proportion of tumor cells contributes to the success of BNCT and that tumor blood vessel normalization improves drug delivery to the tumor. Within this context, the aim of the present study was to evaluate the effect of blood vessel normalization on the therapeutic efficacy and potential radiotoxicity of BNCT in the hamster cheek pouch model of oral cancer. Blood vessel normalization was induced by two doses of thalidomide in tumor-bearing hamsters on 2 consecutive days. All studies in thalidomide-treated animals were performed 48 h after the first dose of thalidomide, previously established as the window of normalization. Biodistribution studies were performed with BPA at a dose of 15.5 mg (10)B/kg in thalidomide-treated (Th+) and untreated (Th-) tumor-bearing hamsters. The effect of blood vessel normalization prior to BPA administration on the efficacy of BNCT was assessed in in vivo BNCT studies at the RA-3 Nuclear Reactor in tumor-bearing hamsters. Group I was treated with BPA-BNCT after treatment with thalidomide (Th+ BPA-BNCT). Group II was treated with BPA-BNCT alone (Th- BPA-BNCT). Group III was treated with the beam only after treatment with thalidomide (Th+ BO), and Group IV was treated with the beam only (Th- BO). Groups I and II were given the same dose of BPA (15.5 mg (10)B/kg), and all groups (I-IV) were exposed to the same neutron fluence. Two additional groups were treated with the beam only at a higher dose to exacerbate mucositis in precancerous tissue and to explore the potential direct protective effect of thalidomide on radiation-induced mucositis in a scenario of more severe toxicity, i.e. Group V (Th+ hdBO) and Group VI (Th- hdBO). The animals were followed for 28 days. Biodistribution studies revealed no statistically significant differences in gross boron content between Th+ and Th- animals. Overall tumor control (complete response + partial response) at 28 days post-treatment was significantly higher for Group I (Th+ BPA-BNCT) than for Group II (Th- BPA-BNCT): 84 ± 3% compared to 67 ± 5%. Pretreatment with thalidomide did not induce statistically significant changes in overall tumor control induced by the beam only, i.e. 15 ± 5% in Group III (Th+ BO) and 18 ± 5% in Group IV (Th- BO), or in overall tumor control induced by the high-dose beam only, i.e. 60 ± 7% in Group V (Th+ hdBO) and 47 ± 10% in Group VI (Th- hdBO). BPA-BNCT alone (Group II) induced mucositis in precancerous tissue that reached Grades 3-4 in 80% of the animals, whereas pretreatment with thalidomide (Group I) prevented mucositis Grades 3 and 4 completely. Beam-only Group III (Th+ BO) exhibited only Grade 1 mucositis in precancerous tissue, whereas 17% of the animals in beam-only Group IV (Th- BO) reached Grade 2 mucositis. High-dose beam-only group V (Th+ hdBO) exhibited only Grade 2 mucositis, whereas high-dose beam-only group VI (Th- hdBO) reached Grade 3 mucositis in 83% of the animals. In all cases mucositis in precancerous tissue was reversible. No normal tissue radiotoxicity was observed with any of the protocols. Pretreatment with thalidomide enhanced the therapeutic efficacy of BNCT and reduced precancerous tissue toxicity.     

Clinical applications of palifermin: amelioration of oral mucositis and other potential indications

Mucositis is one of the most significant toxicities in cancer patients undergoing cytotoxic treatment. It can have a negative impact on both quality of life and health economics. Severe oral mucositis can contribute to hospitalization, need for narcotic analgesics, total parentral nutrition, suboptimal delivery of anti‐neoplastic treatment, and morbidity and mortality. Palifermin, a recombinant derivative of human keratinocyte growth factor, is the first active agent approved by the FDA for the prevention of severe oral mucositis in patients undergoing haematopoietic stem cell transplantation (HSCT). Several studies have also shown significant reduction in the incidence, severity and/or duration of oral mucositis in other high‐risk settings such as concurrent chemoradiotherapy (CT/RT) for patients with head and neck cancer, and use of mucotoxic chemotherapeutic agents such as doxorubicin in sarcoma and fluorouracil for the treatment of colorectal cancer. The reduction in mucositis has translated into amelioration of symptoms and improvement in daily functioning as measured by patient‐reported outcome in multiple studies. The clinical response to palifermin appears to be related in part to epithelial proliferation and mucosal thickening. Palifermin also has other potential clinical applications including the acceleration of immune reconstitution and inhibition of graft‐versus‐host disease in patients undergoing HSCT, and mitigation of dysphagia in lung cancer patients treated with concurrent CT/RT. Palifermin is generally well tolerated with mild‐to‐moderate skin and oral adverse events. Future studies may expand the use of palifermin into other areas that would benefit from its cytoprotective and regenerative effects.     

Smoking during radiotherapy for head and neck cancer and acute mucosal reaction

AimWe compared the incidence of RTOG/EORTC grade III and higher acute mucositis in patients with head and neck cancer who continued to smoke during radiotherapy with those who quit smoking.BackgroundThere are conflicting data on the relationship between smoking during radiotherapy and the severity of acute mucosal reaction. More studies dealing with this issue are needed.Materials and methodsAmong 136 patients receiving curative radio(chemo)therapy, 37 (27%) declared that they had not quit smoking during radiotherapy. The intensity of mucositis was scored daily by a nurse and weekly by a physician using the RTOG/EORTC scale. The main end-point of the study was the highest observed RTOG/EORTC grade of mucositis.ResultsPatients who smoked during radiotherapy (smokers) were younger than their counterparts who quit smoking (non-smokers), p = 0.06. There were no other differences in the baseline characteristics between smokers and non-smokers. Grade III/IV acute mucositis was observed in 43.5% of all patients. The percentage of patients with grade III/IV acute mucositis was similar in smokers and non-smokers (46% vs. 42%, p = 0.71). Nine patients (smokers [13.5%]; non-smokers [4%], p = 0.05) required prolonged hospitalization to heal mucositis.ConclusionsIn the whole group, smoking during radiotherapy was not related to acute mucosal toxicity evaluated as the rate of the highest observed grade of mucositis.     

Methotrexate-induced mucositis in mucin 2-deficient mice

The mucin Muc2 or Mycin2 (Muc2), which is the main structural component of the protective mucus layer, has shown to be upregulated during chemotherapy-induced mucositis. As Muc2 has shown to have protective capacities, upregulation of Muc2 may be a counter reaction of the intestine protecting against mucositis. Therefore, increasing Muc2 protein levels could be a therapeutic target in mucositis prevention or reduction. Our aim was to determine the role of Muc2 in chemotherapy-induced mucositis. Mucositis was induced in Muc2 knockout (Muc2(-/-)) and wild type (Muc2(+/+)) mice by injecting methotrexate (MTX). Animals were weighed and sacrificed on Days 2-6 after MTX treatment and jejunal segments were analyzed. Before MTX treatment, the small intestine of Muc2(+/+) and Muc2(-/-) mice were similar with respect to epithelial morphology and proliferation. Moreover, sucrase-isomaltase and trefoil factor-3 protein expression levels were comparable between Muc2(+/+) and Muc2(-/-) mice. Up to Day 3 after MTX treatment, percentages of weight-loss did not differ. Thereafter, Muc2(+/+) mice showed a trend towards regaining weight, whereas Muc2(-/-) mice continued to lose weight. Surprisingly, MTX-induced intestinal damage of Muc2(-/-) and Muc2(+/+) mice was comparable. Prior to MTX-injection, tumor necrosis factor-alpha and interleukin-10 mRNAs were upregulated in Muc2(-/-) mice, probably due to continuous exposure of the intestine to luminal antigens. Muc2 deficiency does not lead to an increase in chemotherapy-induced mucositis. A possible explanation is the mechanism by which Muc2 deficiency may trigger the immune system to release interleukin-10, an anti-inflammatory cytokine before MTX-treatment.     

Potential role of the NADPH oxidase NOX1 in the pathogenesis of 5-fluorouracil-induced intestinal mucositis in mice

Although NADPH oxidase 1 (NOX1) has been shown to be highly expressed in the gastrointestinal tract, the physiological and pathophysiological roles of this enzyme are not yet fully understood. In the present study, we investigated the role of NOX1 in the pathogenesis of intestinal mucositis induced by the cancer chemotherapeutic agent 5-fluorouracil (5-FU) in mice. Intestinal mucositis was induced in Nox1 knockout (Nox1KO) and littermate wild-type (WT) mice via single, daily administration of 5-FU for 5 days. In WT mice, 5-FU caused severe intestinal mucositis characterized by a shortening of villus height, a disruption of crypts, a loss of body weight, and diarrhea. In Nox1KO mice, however, the severity of mucositis was significantly reduced, particularly with respect to crypt disruption. The numbers of apoptotic caspase-3- and caspase-8-activated cells in the intestinal crypt increased 24 h after the first 5-FU administration but were overall significantly lower in Nox1KO than in WT mice. Furthermore, the 5-FU-mediated upregulation of TNF-α, IL-1β, and NOX1 and the production of reactive oxygen species were significantly attenuated in Nox1KO mice compared with that in WT mice. These findings suggest that NOX1 plays an important role in the pathogenesis of 5-FU-induced intestinal mucositis. NOX1-derived ROS production following administration of 5-FU may promote the apoptotic response through upregulation of inflammatory cytokines.     

A Novel Peptide for Simultaneously Enhanced Treatment of Head and Neck Cancer and Mitigation of Oral Mucositis

We have characterized a novel 21 amino acid-peptide derived from Antrum Mucosal Protein (AMP)-18 that mediates growth promotion of cultured normal epithelial cells and mitigates radiation-induced oral mucositis in animal models, while suppressing in vitro function of cancer cells. The objective of this study was to evaluate these dual potential therapeutic effects of AMP peptide in a clinically relevant animal model of head and neck cancer (HNC) by simultaneously assessing its effect on tumor growth and radiation-induced oral mucositis in an orthotopic model of HNC. Bioluminescent SCC-25 HNC cells were injected into the anterior tongue and tumors that formed were then subjected to focal radiation treatment. Tumor size was assessed using an in vivo imaging system, and the extent of oral mucositis was compared between animals treated with AMP peptide or vehicle (controls). Synergism between AMP peptide and radiation therapy was suggested by the finding that tumors in the AMP peptide/radiation therapy cohort demonstrated inhibited growth vs. radiation therapy-only treated tumors, while AMP peptide-treatment delayed the onset and reduced the severity of radiation therapy-induced oral mucositis. A differential effect on apoptosis appears to be one mechanism by which AMP-18 can stimulate growth and repair of injured mucosal epithelial cells while inhibiting proliferation of HNC cells. RNA microarray analysis identified pathways that are differentially targeted by AMP-18 in HNC vs. nontransformed cells. These observations confirm the notion that normal cells and tumor cells may respond differently to common biological stimuli, and that leveraging this finding in the case of AMP-18 may provide a clinically relevant opportunity.     

Saireito (TJ-114), a Japanese Traditional Herbal Medicine,Reduces 5-Fluorouracil-Induced Intestinal Mucositis in Mice by Inhibiting Cytokine-Mediated Apoptosis in Intestinal Crypt Cells

Clinical chemotherapy frequently causes intestinal mucositis as a side effect, which is accompanied by severe diarrhea. We recently showed that the cytokine-mediated apoptotic pathway might be important for the development of intestinal mucositis induced by 5-fluorouracil (5-FU). Saireito, the traditional Japanese herbal (Kampo) medicine, is widely used to treat diarrhea and various inflammatory diseases in Japan. In the present study, we investigated the effect of saireito on 5-FU-induced intestinal mucositis in mice, especially in relation to apoptosis in the intestinal crypt. Male C57BL/6 mice were given 5-FU (50 mg/kg), i.p. once daily for 6 days. Intestinal mucositis was evaluated histochemically. Saireito (100–1000 mg/kg) was administered p.o. twice daily for 6 days. Repeated 5-FU treatment caused severe intestinal mucositis including morphological damage, which was accompanied by body weight loss and diarrhea. Daily administration of saireito reduced the severity of intestinal mucositis in a dose-dependent manner. Body weight loss and diarrhea during 5-FU treatment were also significantly attenuated by saireito administration. The number of apoptotic and caspase-3-activated cells in the intestinal crypt was increased, and was accompanied by up-regulated tumor necrosis factor (TNF)-α and interleukin (IL)-1β mRNA within 24 h of the first 5-FU injection. However, all of these measures were significantly lower after saireito administration. These results suggest that saireito attenuates 5-FU-induced intestinal mucositis. This action may come from the reduction of apoptosis in the intestinal crypt via suppression of the up-regulation of inflammatory cytokines. Therefore, saireito may be clinically useful for the prevention of intestinal mucositis during cancer chemotherapy.     

Chemotherapy-induced mucositis is associated with changes in proteolytic pathways

Mucositis, a common toxic side effect of chemotherapy, is characterized by an arrest of cell proliferation and a loss of gut barrier function, which may cause treatment reduction or withdrawal. Gut integrity depends on nutritional and metabolic factors, including the balance between protein synthesis and proteolysis. The effects of methotrexate (MTX; a frequently used chemotherapeutic agent) on intestinal proteolysis and gut barrier function were investigated in rats. Male Sprague-Dawley rats received 2.5 mg/kg of MTX subcutaneously during 3 days and were euthanized at Day 4 (D4) or Day 7 (D7). We observed at D4 that MTX induced mucosal damage and increased intestinal permeability (7-fold) and the mucosal concentration of interleukin (IL)-1beta and IL-6 (4- to 6-fold). In addition, villus height and glutathione content significantly decreased. Intestinal proteolysis was also affected by MTX as cathepsin D activity increased at D4, whereas chymotrypsin-like proteasome activity decreased and calpain activities remained unaffected. At D7, cathepsin D activity was restored to control levels, but proteasome activity remained reduced. This disruption of proteolysis pathways strongly contributed to mucositis and requires further study. Lysosomal proteolytic activity may be considered the main proteolytic pathway responsible for alteration of mucosal integrity and intestinal permeability during mucositis, as cathepsin D activity was found to be correlated with mucosal atrophy and intestinal permeability. Proteasome regulation could possibly be an adaptive process for survival. Future investigation is warranted to target proteolytic pathways with protective nutritional or pharmacological therapies during mucositis.