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Background: Predicting the occurrence and/or severity of oral mucositis (OM) before commencing radiotherapy (RT) remains very difficult. The aim of this prospective trial was to investigate whether the ex-vivo radiation sensitivity of oral keratinocytes from head and neck (H&N) cancer patients correlates with severe OM. Methods: Oral microbiopsies of healthy gingival mucosa were collected from 63H&N cancer patients undergoing (chemo)RT, of which 58 samples were useable. Keratinocytes from these microbiopsies underwent ex-vivo proliferation, irradiation, and subsequently the cell spreading assay. Tubes with the cell suspension were placed within the irradiation chamber of a 137Cs Gammacell 40 Exactor (Best Theratronics, Canada) and exposed to 0, 2, 4, 6, or 8 Gy at a dose rate of 0.63 Gy min−1. Cell suspension was then immediately pipetted into custom-made polydimethylsiloxane (PDMS) rings.The effect of demographic and clinical parameters on the cell spreading assay were also analyzed. Systematic clinical recording of OM was conducted twice a week by a specially trained examiner. Results: Most patients had node-positive disease and cancer of the oropharynx or oral cavity. The vast majority of patients received adjuvant RT and concurrent chemotherapy. Overall, 34 (58.6 %) participants developed grade 3 OM after a median dose of 32 Gy. No patient experienced a grade ≥ 4 event. There was a correlation between the cell spreading assay area and grade 3 OM (p 0.05 for all). Conclusions: It is necessary to establish reliable predictors of severe OM before treatment in H&N cancer to allow early management of treatment-related sequelae. This prospective trial illustrates that the intrinsic ex-vivo radiosensitivity of oral keratinocytes could be correlated with RT-induced OM in patients with H&N cancer. This novel predictor requires validation in larger prospective cohorts.

ObjectiveHead and neck cancer (HNC) accounts for almost 890,000 new cases per year. Radiotherapy (RT) is used to treat the majority of these patients. A common side-effect of RT is the onset of oral mucositis, which decreases the quality of life and represents the major dose-limiting factor in RT. To understand the origin of oral mucositis, the biological mechanisms post-ionizing radiation (IR) need to be clarified. Such knowledge is valuable to develop new treatment targets for oral mucositis and markers for the early identification of “at-risk” patients.MethodsPrimary keratinocytes from healthy volunteers were biopsied, irradiated in vitro (0 and 6 Gy), and subjected to mass spectrometry-based analyses 96 h after irradiation. Web-based tools were used to predict triggered biological pathways. The results were validated in the OKF6 cell culture model. Immunoblotting and mRNA validation was performed and cytokines present in cell culture media post-IR were quantified.ResultsMass spectrometry-based proteomics identified 5879 proteins in primary keratinocytes and 4597 proteins in OKF6 cells. Amongst them, 212 proteins in primary keratinocytes and 169 proteins in OKF6 cells were differentially abundant 96 h after 6 Gy irradiation compared to sham-irradiated controls. In silico pathway enrichment analysis predicted interferon (IFN) response and DNA strand elongation pathways as mostly affected pathways in both cell systems. Immunoblot validations showed a decrease in minichromosome maintenance (MCM) complex proteins 2-7 and an increase in IFN-associated proteins STAT1 and ISG15. In line with affected IFN signalling, mRNA levels of IFNβ and interleukin 6 (IL-6) increased significantly following irradiation and also levels of secreted IL-1β, IL-6, IP-10, and ISG15 were elevated.ConclusionThis study has investigated biological mechanisms in keratinocytes post-in vitro ionizing radiation. A common radiation signature in keratinocytes was identified. The role of IFN response in keratinocytes along with increased levels of pro-inflammatory cytokines and proteins could hint towards a possible mechanism for oral mucositis.

Abstract The application of stannous ions in combination with fluoride (F/Sn) is one of the central strategies in reducing erosive tooth wear. F/Sn efficacy can be enhanced by adding chitosan, a positively charged biopolymer. For patients with low saliva flow, this efficacy, however, is not sufficient, making further improvement desirable. This could be achieved by combining chitosan with other molecules like mucin, which together might form multilayers. This in-vitro study aimed to investigate the effect of chitosan, mucin, F/Sn and combinations thereof on enamel erosion and erosion-abrasion. Human enamel samples (n = 448, 28 groups) were cyclically eroded or eroded-abraded (10 days; 6 × 2 min erosion and 2 × 15 s/200 g abrasion per day). Samples were treated 2 × 2 min/day with solutions containing either, chitosan (50 or 500 mPas), porcine gastric mucin, F/Sn or combinations thereof after abrasive challenge. Tissue loss was measured profilometrically, interaction between hard tissue and active agents was assessed with energy dispersive spectroscopy and scanning electron microscopy. Chitosan and F/Sn showed the expected effect in reducing tissue loss under erosive and under erosive-abrasive conditions. Neither mucin alone nor the combinations with mucin showed any additional beneficial effect.