The relationship between the severity of radiation-induced oral mucositis and the myeloperoxidase levels in rats

Characterization of a novel dual murine model of chemotherapy-induced oral and intestinal mucositis

Oral and intestinal mucositis are debilitating inflammatory diseases observed in cancer patients undergoing chemo-radiotherapy. These are devastating clinical conditions which often lead to treatment disruption affecting underlying malignancy management. Although alimentary tract mucositis involves the entire gastrointestinal tract, oral and intestinal mucositis are often studied independently utilizing distinct organ-specific pre-clinical models. This approach has however hindered the development of potentially effective whole-patient treatment strategies. We now characterize a murine model of alimentary tract mucositis using 5-Fluorouracil (5-FU). Mice were given 5-FU intravenously (50 mg/kg) or saline every 48 h for 2 weeks. Post initial injection, mice were monitored clinically for weight loss and diarrhea. The incidence and extent of oral mucositis was assessed macroscopically. Microscopical and histomorphometric analyses of the tongue and intestinal tissues were conducted at 3 interim time points during the experimental period. Repeated 5-FU treatment caused severe oral and intestinal atrophy, including morphological damage, accompanied by body weight loss and mild to moderate diarrhea in up to 77.8% of mice. Oral mucositis was clinically evident throughout the observation period in 88.98% of mice. Toluidine blue staining of the tongue revealed that the ulcer size peaked at day-14. In summary, we have developed a model reproducing the clinical and histologic features of both oral and intestinal mucositis, which may represent a useful in vivo pre-clinical model for the study of chemotherapy-induced alimentary tract mucositis and the development of preventative therapies.

The effect of systemic application of propolis on tongue damage and oral mucositis in rats exposed to radiation

PURPOSE

In this experimental study, the effect of dose-dense systemic application of propolis on oral mucosity, histological changes in papilla, and inflammatory and hypoxic markers in rats exposed to radiation was investigated.

METHODS

Seven rats were in the control and 30 rats in the experimental group. Three experimental groups were formed. In Group 1 RT (15 Gy) was delivered only to the head and neck region. In Group 2, RT (15 Gy) and systemic administration of 100 mg/kg/ml propolis, in Group 3, RT (15 Gy) and systemic administration of 200 mg/kg/ml propolis were applied. Oral mucositis index (OMI) was scored in control and experimental groups. Proinflammatory markers [interleukin-6 (IL-6), myeloperoxidase (MPO), tumor-necrosis factor-α (TNF-α)] hypoxia markers [glucose transporter-1 (GLUT-1), hypoxia-inducible factor 1α (HIF-1α)] were studied histomorphologically.

RESULTS

The significantly highest OMI score was observed in the G1. OMI score was statistically significantly decreased in experimental groups receiving systemic propolis, especially in G3. Proinflammatory markers increased significantly only in the experimental RT group, G1. Serum levels of MPO and TNF-α significantly decreased in the dose-dense systemic propolis arm. The highest levels of hypoxia markers (HIF-1α and GLUT-1) were detected in the RT group, then in G2, G3, and control groups in order of decreasing frequency. However, the difference between the groups did not reach the level of statistical significance.

CONCLUSION

Systemic propolis can be reduced acute mucositis with its anti-inflammatory effect without developing resistance to RT (tumor protection). However, greater number of clinical studies should be designed to arrive at definitive conclusions.

Tissue Damage in Radiation-Induced Oral Mucositis Is Mitigated by IL-17 Receptor Signaling

Oral mucositis (OM) is a treatment-limiting adverse side effect of radiation and chemotherapy. Approximately 80% of patients undergoing radiotherapy (RT) for head and neck cancers (HNC) develop OM, representing a major unmet medical condition. Our understanding of the immunopathogenesis of OM is limited, due in part to the surprising paucity of information regarding healing mechanisms in the oral mucosa. RNAseq of oral tissue in a murine model that closely mimics human OM, showed elevated expression of IL-17 and related immune pathways in response to head and neck irradiation (HNI). Strikingly, mice lacking the IL-17 receptor (IL-17RA) exhibited markedly more severe OM. Restoration of the oral mucosa was compromised in Il17ra-/- mice and components associated with healing, including matrix metalloproteinase 3, 10 and IL-24 were diminished. IL-17 is typically associated with recruitment of neutrophils to mucosal sites following oral infections. Unexpectedly, in OM the absence of IL-17RA resulted in excessive neutrophil recruitment and immunopathology. Instead, neutrophil activation was IL-1R-driven in Il17ra-/- mice. Blockade of IL-1R and depletion of neutrophils lessened the severity of damage in these mice. Overall, we show IL-17 is protective in OM through multiple mechanisms including restoration of the damaged epithelia and control of the neutrophil response. We also present a clinically relevant murine model of human OM to improve mechanistic understanding and develop rational translational therapeutics.

Functional response difference between diabetic/normal cancerous patients to inflammatory cytokines and oxidative stresses after radiotherapy

Diabetes, which is considered as a chronic metabolic disorder leads to an increase in inflammatory cytokines and oxidative stresses. Studies have shown several functional differences in the oxidative stress and inflammatory cytokines responses in diabetic/normal cancerous patients candidate for radiotherapy. Also, radiotherapy as a cancer treatment modality is known as a carcinogen due to oxidative damage via generation of reactive oxygen metabolites and also causing inflammation of the tissue by increasing the inflammatory cytokines. Therefore, the consequence of diabetes on oxidative stress and increased inflammatory factors and synergistic effects of radiotherapy on these factors cause complications in diabetics undergoing radiotherapy. It is considered as one of the most interesting objectives to control inflammation and oxidative stress in these patients. This review aims to concentrate on the influence of factors such as MPO, MDA, IL-1β, and TNF-α in diabetic patients by emphasizing the effects related to radiation-induced toxicity and inflammation by proposing therapeutic approaches which could be helpful in reduction of the complications.

Effects of commercially produced almond by-products on chemotherapy-induced mucositis in rats

AIM

To determine if almond extracts reduce the severity of chemotherapy-induced mucositis as determined through biochemical, histological and behavioural markers.

METHODS

Intestinal mucositis is a debilitating condition characterized by inflammation and ulceration of the gastrointestinal mucosa experienced by cancer patients undergoing chemotherapy. Certain bioactive plant products have shown promise in accelerating mucosal repair and alleviating clinical symptoms. This study evaluated almond extracts for their potential to reduce the severity of chemotherapy-induced mucositis in Dark Agouti rats. Female Dark Agouti rats were gavaged (days 3-11) with either PBS, almond hull or almond blanched water extract at two doses, and were injected intraperitoneally with 5-fluorouracil (5-FU-150 mg/kg) or saline on day 9 to induce mucositis. Burrowing behavior, histological parameters and myeloperoxidase activity were assessed.

RESULTS

Bodyweight was significantly reduced in rats that received 5-FU compared to saline-treated controls (P < 0.05). Rats administered 5-FU significantly increased jejunal and ileal MPO levels (1048%; P < 0.001 and 409%; P < 0.001), compared to healthy controls. Almond hull extract caused a pro-inflammatory response in rats with mucositis as evidenced by increased myeloperoxidase activity in the jejunum when compared to 5-FU alone (rise 50%, 1088 ± 96 U/g vs 723 ± 135 U/g, P = 0.02). Other extract-related effects on inflammatory activity were minimal. 5-FU significantly increased histological severity score compared to healthy controls confirming the presence of mucositis (median of 9.75 vs 0; P < 0.001). The extracts had no ameliorating effect on histological severity score in the jejunum or ileum. Burrowing behavior was significantly reduced in all chemotherapy-treated groups (P = 0.001). The extracts failed to normalize burrowing activity to baseline levels.

CONCLUSION

Almond extracts at these dosages offer little beneficial effect on mucositis severity. Burrowing provides a novel measure of affective state in studies of chemotherapy-induced mucositis.

Cannabidiol: an alternative therapeutic agent for oral mucositis?

WHAT IS KNOWN AND OBJECTIVE

Chemo- and radiotherapy are therapeutic modalities often used in patients with malignant neoplasms. They kill tumour cells but act on healthy tissues as well, resulting in adverse effects. Oral mucositis is especially of concern, due to the morbidity that it causes. We reviewed the literature on the etiopathogenesis of oral mucositis and the activity of cannabidiol, to consider the possibility of its use for the prevention and treatment of oral mucositis.

METHODS

We searched the PubMed database and selected complete articles published in English that met the inclusion criteria for the period 1998-2016. The search terms 'cannabinoids', 'cannabidiol', 'oxidative stress', 'antioxidants' and 'oral mucositis' were used.

RESULTS AND DISCUSSION

The control of oxidative stress may prevent and alleviate oral mucositis. Studies have demonstrated that cannabidiol is safe to use and possesses antioxidant, anti-inflammatory and analgesic properties.

WHAT IS NEW AND CONCLUSIONS

The literature on the use of cannabidiol in dentistry is still scarce. Studies investigating the use of cannabidiol in oral mucositis and other oxidative stress-mediated side effects of chemotherapy and radiotherapy on the oral mucosa should be encouraged.