Pathogenesis Of Oral Mucositis Research Articles

Effect of antitumor therapy on microflora and oral mucosa in patients with malignant neoplasms

The present article investigates the relationship between the microbiota of the oral cavity and oral mucositis induced by systemic antitumor therapy in patients with malignant neoplasms. This article highlights modern ideas about the composition of the normal microbiota of the oral cavity and its changes during chemotherapeutic treatment.
 It has been shown that the normal oral microbiota includes representatives of such genera as Actinomyces, Corynebacterium, Fusobacterium, Leptotrichia, Neisseria, Prevotella, Streptococcus, and Veillonella. Moreover, it is emphasized that despite the existence of modern molecular genetic techniques and development of an oral microbiota database, determining the role of individual taxonomic units in oral homeostasis remains challenging.
 Existing studies of changes in the qualitative and quantitative composition of oral microflora against the background of drug antitumor therapy have demonstrated that treatment is associated with significant changes in the microbiological landscape of the oral cavity. An increase was noted in the number of Gram-negative anaerobic opportunistic flora and a decrease in the representation of protective commensal flora. It has been demonstrated that the components of a bacterial cell can modulate the local reactions of a macroorganism through a system of Toll-like receptors while acting in different directions.
 Several unresolved fundamental issues related to the role of oral microbiota in the pathogenesis of oral mucositis are highlighted.

The place and role of oral microflora in the pathogenesis of oral mucositis in malignant neoplasms (literature review)

Background. Oral mucositis (OM) is one of the most frequent complications of systemic drug therapy of oncological diseases. Clinically, the disease manifests itself in the form of erythema and ulceration of the non-corneating mucous membrane. Although this condition is self-healing, it can affect the conduct of comprehensive antitumor treatment. Currently, the pathophysiological model of the development of OM is supplemented with new data obtained during studies of the oral microflora. Antitumor treatment can lead to changes in the composition of the resident oral microflora and it is quite possible that the changes that occur may affect the development of damage to the oral mucosa. The expansion of knowledge in this area allows researchers to look for new ways to include oral microbiota in OM management strategies.
 Aim. To summarize and update the accumulated data regarding the role of the oral microbiota in the pathogenesis of OM in patients with malignant neoplasms.
 Materials and methods. Literature search was performed in Medline, Cochrane Library, Elibrary and Pubmed, including publications demonstrating the current ability to assess the impact of the oral microbiome on OM, as well as developments in this area relating to OM management.
 Results. In the review the current views on the position of the oral microbiome in the pathogenesis of OM were highlighted and the promising directions for the use of agents influencing the state of the oral microbiota in various strategies to control this disease were emphasised.
 Conclusion. A better understanding of the pathogenesis of OM and the inclusion of new factors, such as the oral microbiome, into the picture of pathogenesis is likely to enable the formation of more effective management strategies for this disease in the future. This direction seems very promising, and developments in this area show promising results.

The Role of the Innate Immune Response in Oral Mucositis Pathogenesis.

Oral mucositis (OM) is a significant complication of cancer therapy with limited management strategies. Whilst inflammation is a central feature of destructive and ultimately ulcerative pathology, to date, attempts to mitigate damage via this mechanism have proven limited. A relatively underexamined aspect of OM development is the contribution of elements of the innate immune system. In particular, the role played by barriers, pattern recognition systems, and microbial composition in early damage signaling requires further investigation. As such, this review highlights the innate immune response as a potential focus for research to better understand OM pathogenesis and development of interventions for patients treated with radiotherapy and chemotherapy. Future areas of evaluation include manipulation of microbial-mucosal interactions to alter cytotoxic sensitivity, use of germ-free models, and translation of innate immune-targeted agents interrogated for mucosal injury in other regions of the alimentary canal into OM-based clinical trials.

ИЗМЕНЕНИЯ МИКРОФЛОРЫ ПОЛОСТИ РТА И РАЗВИТИЕ ОРАЛЬНОГО МУКОЗИТА ПРИ ПРОВЕДЕНИИ СИСТЕМНОЙ ПРОТИВООПУХОЛЕВОЙ ТЕРАПИИ У БОЛЬНЫХ СО ЗЛОКАЧЕСТВЕННЫМИ НОВООБРАЗОВАНИЯМИ

This paper is devoted to the problem of the relationship between the oral microflora and oral mucositis (OM) induced by systemic anti-tumour therapy in patients with malignant neoplasms (MN). The paper covers current views on the composition of the normal oral microbiota and its changes during chemotherapeutic treatment. It is shown that normal oral microbiota includes representatives of such genera as Actinomyces, Corynebacterium, Fusobacterium, Leptotrichia, Neisseria, Prevotella, Streptococcus, Veillonella and others. It is emphasized that even despite the existence of modern molecular genetic techniques and the formation of a database of oral microbiota, it is still difficult to determine the role of individual taxonomic units in oral homeostasis. Existing studies of changes in the qualitative and quantitative composition of oral microflora against the background of anticancer therapy have demonstrated that treatment is associated with significant changes in the oral microbiological landscape, namely increasing the number of Gram-negative anaerobic opportunistic pathogenic flora and decreasing representation of protective commensal flora. It is demonstrated that bacterial cell components can modulate local macroorganism reaction through the system of Toll-like receptors, thus acting multidirectionally. A number of unresolved fundamental questions relating to the place of the oral microbiota in the pathogenesis of OM have also been highlighted.

PREVLAR: Phase 2a Randomized Trial to Assess the Safety and Efficacy of RRx-001 in the Attenuation of Oral Mucositis in Patients Receiving Head and Neck Chemoradiotherapy

No Food and Drug Administration-approved intervention exists for oral mucositis (OM) from chemoradiotherapy (CRT) used to treat head and neck cancers. RRx-001 is a hypoxia-activated, cysteine-directed molecule that affects key pathways involved in OM pathogenesis. This phase 2a, multi-institutional trial was designed to assess the safety and feasibility of 3 schedules of a fixed concentration of RRx-001; a standard-of-care arm was included to identify potential signals of efficacy for further study. This study enrolled patients with oral cavity and oropharynx squamous cell carcinoma receiving definitive or postoperative cisplatin-based CRT. Patients were randomized into 4 cohorts. In arms 1 to 3, RRx-001 was coinfused with patients' blood at differing intervals. Arm 4 was a control cohort of patients treated with CRT alone. Trained evaluators assessed OM using a standardized data collection instrument twice weekly during treatment and then until resolution. OM severity was scored centrally using World Health Organization criteria. Safety outcomes were assessed using National Cancer Institute - Common Terminology Criteriav4 benchmarks. Long-term tumor response was defined by Response evaluation criteria in solid tumors v1.1 criteria. Fifty-three patients were enrolled, with 46 and 45 individuals contributing safety and efficacy data, respectively. There were no severe adverse events attributed to the study drug. Across all 3 active arms, the study drug was infused fully per protocol in 86% of patients. All 3 RRx-001 treatment cohorts appeared to demonstrate a similar or lower OM duration relative to control; arm 1 had the lowest median duration of severe oral mucositis (SOM), 8.5 days versus 24 days in controls among patients who developed at least 1 day of SOM. There were no locoregional failures in any patient. Our results support the safety and feasibility of RRx-001 as an intervention to mitigate SOM. Additional studies are planned to confirm its efficacy.

Oxidative Stress and Chemoradiation-Induced Oral Mucositis: A Scoping Review of In Vitro, In Vivo and Clinical Studies.

Chemoradiation-induced mucositis is a debilitating condition of the gastrointestinal tract eventuating from antineoplastic treatment. It is believed to occur primarily due to oxidative stress mechanisms, which generate Reactive Oxygen Species (ROS). The aim of this scoping review was to assess the role of oxidative stress in the development of Oral Mucositis (OM). Studies from the literature, published in MEDLINE and SCOPUS, that evaluated the oxidative stress pathways or antioxidant interventions for OM, were retrieved to elucidate the current understanding of their relationship. Studies failing inclusion criteria were excluded, and those suitable underwent data extraction, using a predefined data extraction table. Eighty-nine articles fulfilled criteria, and these were sub-stratified into models of study (in vitro, in vivo, or clinical) for evaluation. Thirty-five clinical studies evaluated antioxidant interventions on OM’s severity, duration, and pain, amongst other attributes. A number of clinical studies sought to elucidate the protective or therapeutic effects of compounds that had been pre-determined to have antioxidant properties, without directly assessing oxidative stress parameters (these were deemed “indirect evidence”). Forty-seven in vivo studies assessed the capacity of various compounds to prevent OM. Findings were mostly consistent, reporting reduced OM severity associated with a reduction in ROS, malondialdehyde (MDA), myeloperoxidase (MPO), but higher glutathione (GSH) and superoxide dismutase (SOD) activity or expression. Twenty-one in vitro studies assessed potential OM therapeutic interventions. The majority demonstrated successful a reduction in ROS, and in select studies, secondary molecules were assessed to identify the mechanism. In summary, this review highlighted numerous oxidative stress pathways involved in OM pathogenesis, which may inform the development of novel therapeutic targets.

Antibiotic-Induced Gut Microbiota Depletion Accelerates the Recovery of Radiation-Induced Oral Mucositis in Rats

Due to its pivotal role in the modulation of immune and inflammatory responses, the gut microbiota has emerged as a key modulator of cancer treatment-induced gastrointestinal mucositis. However, it is not clear yet how it affects radiation therapy-induced oral mucositis (OM). As such, this study aimed to explore the gut microbiota's role in the pathogenesis of radiation-induced OM in rats. Male Sprague Dawley rats were treated with 20 Gy x-ray radiation (Rx) delivered to the snout, with or without antibiotic-induced microbiota depletion (AIMD). OM severity was assessed, and tongue tissues were collected on day 9 and 15 postradiation for tissue injury and inflammatory markers assessment. AIMD+Rx had a significantly shorter duration of severe OM compared with Rx alone group. Macroscopically, the tongue ulcer-like area was smaller in AIMD+Rx compared with the Rx group. Microscopically, a smaller percentage of the mucosal ulcer was observed in the dorsal tongue of AIMD+Rx compared with the Rx group. AIMD+Rx also had significantly lower levels of interleukin 6, interleukin 1 beta, and toll like receptor 4 in the tongue tissues than the Rx group. The gut microbiota plays a role in OM pathogenesis, mainly in the recovery phase, through the modulation of proinflammatory pathways. Future microbiota-targeted interventions may improve OM in clinical settings.

Oral Microbiota during Childhood and Its Role in Chemotherapy-Induced Oral Mucositis in Children with Cancer

The human oral cavity harbors the second most abundant microbiota after the gastrointestinal tract, with over 700 species currently identified in the oral microflora. The oral microbiota develops from intrauterine life and after birth is continuously shaped by several influencing factors. The perturbation of the diversity and proportions of species within the oral microbiota leads to dysbiosis and associated increased risk of local and systemic diseases. In children who receive chemotherapy for cancer, oral mucositis is a common and painful side effect that decreases quality of life (QoL) and treatment adherence. The oral microbiota undergoes a substantial dysbiosis as an effect of cancer and its treatment, characterized by lower richness and less diversity. Furthermore, this dysbiosis seems to promote pro-inflammatory cytokine release and pro-apoptotic mediators, enhancing the oral tissue damage. Further studies on the role of the oral microbiota in the pathogenesis of oral mucositis should be performed among children with cancer who receive chemotherapy, to find preventive and protective factors against the pathogenesis of oral mucositis.

Oral-Gut Microbiome Axis in the Pathogenesis of Cancer Treatment-Induced Oral Mucositis.

Oral mucositis (OM) is one of the most common and debilitating oral complications of cancer treatments including chemotherapy, radiotherapy, and hematopoietic stem cell transplantation. It is associated with severe pain and difficulties in chewing, swallowing, and speech. This leads to impairment of basic oral functions and could result in unplanned treatment interruption or modification. As such, OM negatively impacts both patients' quality of life as well as tumor prognostic outcomes. Understanding pathways underlying OM pathogenesis help identify new targets for intervention or prevention. The pathophysiology of OM has been widely studied over past decades with several pathways related to oxidative stress, inflammation, and molecular and cellular signaling being implicated. In this mini-review, we will discuss the emerging role of the oral-gut microbiome axis in the development of OM. Particularly, we will elaborate on how the alterations in the oral and gut microbiota as well as intestinal dysfunction caused by cancer treatments could contribute to the pathogenesis of OM. Further, we will briefly discuss the potential methods for targeting the oral-gut microbiome axis to improve OM outcomes.

Growth Factors and Effects of Palifermin in Management of Cancer Therapy Induced Oral Mucositis

Amongst the various hazards of chemotherapeutic drugs and radiation in cancer patients, oral mucositis is the most commonly encountered and troublesome complication so far. It can be a cause for discontinuation of therapy and may add to the cost of treatment. In this article, pathogenesis of oral mucositis and role of recombinant human growth factors in management of it have been discussed, as we need to achieve a guideline for proper treatment of this painful side effect of cancer treatment. Palifermin, a keratinocyte growth factor has been shown to give promising results in cases of severe mucositis in hematopoetic stem cell transplant patients undergoing combined chemoradiotherapy. Other exogenous growth factors are also effective in the management of mucositis when administered topically or subcutaneously, but there is need for more number of studies with a large sample size for establishing a proper treatment plan which is cost effective as well as helpful in reducing patient’s discomfort.

A Dose-Escalation Phase Ib International Study to Evaluate the Safety, Pharmacokinetics and Efficacy of ST-617 for the Attenuation of Oral Mucositis in Patients Receiving Chemoradiation for H&N Cancer

Oral Mucositis (OM) is a common, painful, and costly toxicity associated with cytotoxic chemoradiation regimens used to treat H&N cancer, which may interfere with planned treatment and negatively impact tumor control. There are currently no approved interventions to mitigate the incidence, severity or duration of OM. Oxidative stress is a critical event in OM's pathogenesis. Through its effect on Nrf2, ST-617 has marked anti-oxidative activity/properties. Supportive Therapeutics is developing ST-617, a dithioethione, for the attenuation of OM. The objective of this trial was to assess the safety, tolerability, pharmacokinetics, pharmacodynamics and efficacy of ST-617 in patients at high risk of severe OM (SOM).A dose escalation trial was performed in which ST-617, administered as an oral suspension, 1-2 hours before the administration of daily RT fractions at 9 study sites in South Africa and Australia. Eighteen patients with diagnoses of oral or oropharyngeal CA were enrolled (up to 6 pts/dose). Patients received concomitant cisplatin either weekly or tri-weekly. ST-617 was administered 3 days prior to CRT, and then continuing daily concomitant with BSC (Best Supportive Care) until the end of treatment. Safety outcomes, using CTCAE criteria (v 4.03) were used. Dose escalation occurred in the absence of toxicity. OM occurrence and severity were assessed by trained and validated evaluators using WHO, NCI-CTC and RTOG criteria; scores were centrally assigned. The primary efficacy endpoints included the incidence and duration of SOM (WHO grades 3 or 4) vs historical controls. PD tracking measured total ROS/RNS, GSH/GSSG, regulation in plasma and buccal epithelial cells.17 pts completed the 50, 100 and 150mg/day with no safety issues. No early dose limiting toxicity (DLT) or serious Adverse Event linked to ST-617 were observed. AEs observed were mainly nausea which is usually associated with CRT as expected. As overall SOM incidence (baseline to the last day of radiation) of 50% was less than expected and was related to ST-617 dose: 50 mg/day 83% (n = 6); 100 mg/day 33% (n = 9); 200 mg/day 33% (n = 3). The 100 mg/day dose was well tolerated with no grade 4 OM. No CRT dose interruptions or delays due to OM were noted Total ROS/RNS levels in plasma and buccal samples show significant decrease with increased ST-617 dosing from 50 to 100 mg/day. ST-617 did not alter tumor response at 1 year post-CRT (n = 17).ST-617 administration was safe at all doses tested. The course and severity of patients treated with ST-617 compared favorably with historical controls. A dose-response effect on SOM incidence was noted. Mechanistic correlation between ROS/RNS levels was seen. A randomized, controlled, double blind trial is planned with the recommended dose of 100mg/day.

Therapeutic Intervention Using a Smad7-Based Tat Protein to Treat Radiation-Induced Oral Mucositis

Recent studies reported therapeutic effects of Smad7 on oral mucositis in mice without compromising radiation therapy-induced cancer cell killing in neighboring oral cancer. This study aims to assess whether a Smad7-based biologic can treat oral mucositis in a clinically relevant setting by establishing an oral mucositis model in dogs and analyzing molecular targets. We created a truncated human Smad7 protein fused with the cell-penetrating Tat tag (Tat-PYC-Smad7). We used intensity modulated radiation therapy to induce oral mucositis in dogs and applied Tat-PYC-Smad7 to the oral mucosa in dose-finding studies after intensity modulated radiation therapy. Clinical outcomes were evaluated. Molecular targets were analyzed in biopsies and serum samples. Tat-PYC-Smad7 treatment significantly shortened the duration of grade 3 oral mucositis based on double-blinded Veterinary Radiation Therapy Oncology Group scores and histopathology evaluations. Topically applied Tat-PYC-Smad7 primarily penetrated epithelial cells and was undetectable in serum. NanoString nCounter Canine IO Panel identified that, compared to the vehicle samples, top molecular changes in Tat-PYC-Smad7 treated samples include reductions in inflammation and cell death and increases in cell growth and DNA repair. Consistently, immunostaining shows that Tat-PYC-Smad7 reduced DNA damage and neutrophil infiltration with attenuated TGF-β and NFκB signaling. Furthermore, IL-1β and TNF-α were lower in Tat-PYC-Smad7 treated mucosa and serum samples compared to those in vehicle controls. Topical Tat-PYC-Smad7 application demonstrated therapeutic effects on oral mucositis induced by intensity modulated radiation therapy in dogs. The local effects of Tat-PYC-Smad7 targeted molecules involved in oral mucositis pathogenesis as well as reduced systemic inflammatory cytokines.

The role of benzydamine in prevention and treatment of chemoradiotherapy-induced mucositis

PurposeTo discuss the role of benzydamine in the prevention and treatment of radiation-induced oral mucositis (OM) in head and neck (H&N) cancer patients. This document represents an expert opinion paper on indications and key-role aspects in OM pathogenesis, prevention and treatment.Oral mucositisOM represents a common side effect of chemotherapy (CHT) and radiotherapy (RT). It consists in a painful erythema involving the oral cavity mucosa, which may progress to ulceration. Five biologically dynamic phases are considered crucial in mucositis: “initiation, signalling, amplification, ulceration and healing”. Oral environment and microbiota are fundamental in mucositis development being involved in susceptibility to infections and in ulceration consequences. Different agents against mucositis have been studied and the use of benzydamine is strongly supported in literature. The Multinational Association of Supportive Care in Cancer and International Society for Oral Oncology (MASCC/ISOO) guidelines recommend its use for the prevention of OM in H&N patients undergoing RT and RT/CHT.BenzydamineBenzydamine is a local anti-inflammatory drug with analgesic properties. It can decrease TNF-α, IL-1β and prostaglandin synthesis, also inhibiting leukocyte-endothelial interactions, neutrophil degranulation, vasodilation and vascular permeability. Literature agrees on the beneficial effects of benzydamine in preventing and reducing oral mucositis severity in H&N cancer patients undergoing RT/CHT.ConclusionsMucositis represents a major concern in H&N cancer patients and a clinical and economical issue. A multimodal and multidisciplinary approach is needed for its management. International guidelines recommend benzydamine for OM prevention and treatment in H&N cancer patients, but further “real world” trials should be designed.

Protective effect of kava constituents in an in vitro model of oral mucositis.

Oral mucositis is a debilitating inflammatory disorder observed in patients undergoing active cancer treatment, particularly cancer of the head and neck region. A key pathway believed to be involved in the pathogenesis of oral mucositis is the formation of reactive oxygen species (ROS). The identification of compounds that can inhibit this pathway may therefore be of benefit in treating this disorder. The kava plant (Piper methysticum) contains various constituents, including flavokawain A (FKA), flavokawain B (FKB), yangonin, methysticin and kavain. These constituents are known to be biologically active and possess anti-oxidative properties. This study therefore focused on examining these constituents for their effect on ROS formation in an in vitro oral mucositis model. Cell proliferation was assessed in normal oral keratinocytes (OKF6) treated with and without kava constituents, namely FKA, FKB, yangonin, methysticin and kavain using an MTS in vitro assay. Oxidative stress was assessed by co-treating and pre-treating OKF6 cells with H2O2. The effects were quantified by analysis of ROS production, using a CM-H2DCFDA assay. Pre-treatment of cells for 24h with 2.5μg/ml kavain and 5μg/ml FKA demonstrated a significant protective anti-oxidative effect. Similarly, FKB at a concentration of 2.5μg/ml, demonstrated a trend of ROS reduction but was observed to be cytotoxic at concentrations greater than 5μg/ml. Reduction in ROS production by methysticin and yangonin was compromised by their cell cytotoxicity. This was the first study to identify the anti-oxidative effects and safety of FKA and kavain with regard to oral keratinocytes, highlighting their potential use in the development of a preventative treatment for oral mucositis.

Herpesviruses in the oral cavity of patients subjected to allogeneic hematopoietic stem cell transplantation and its relationship with oral mucositis.

This study was performed to characterise oral shedding of herpesviruses in patients who underwent allogeneic hematopoietic stem cell transplantation (alloHSCT) and to investigate its relationship with oral mucositis (OM). PCR and enzymatic digestion were conducted to identify oral shedding of herpesviruses and its correlation with OM development in 31 patients. The samples were collected at three sites in the oral cavity and at 5 times during follow-up; two additional collections were made from patients who developed ulcerative OM. HSV-1, EBV, CMV, HHV-6A, HHV-6B, and HHV-7 were detected in 4.97%, 16.02%, 4.41%, 2.20%, 3.31%, and 68% of the oral mucosal samples, respectively; 4.41%, 16.57%, 5.52%, 2.20%, 5.52%, and 63.53% of supragingival samples, respectively, and 4.41%, 18.23%, 2.76%, 1.65%, 2.75%, and 35.91% of subgingival samples, respectively. OM was diagnosed in 13 patients. The presence of HHV-7 in C1 (oral mucosa: p = 0.032) and C2 (supragingival: p = 0.009; subgingival: p = 0.002) was significantly increased in patients who developed OM, and patients exhibiting HHV-7 shedding in the oral cavity were 3.32-fold more likely to develop OM. Patients who developed OM showed higher HHV-7 shedding in the oral cavity at nadir (immediately prior to OM development), suggesting modifications to the inflammatory microenvironment. HHV-7 may be involved in oral dysbiosis in HSCT-related OM; enhanced understanding of its role in the pathogenesis of OM may lead to the development of strategies for managing and preventing this common side effect of alloHSCT.

Salivary proteins as markers of radiation-related oral mucositis

Objectives The aim of this study was to characterize the salivary proteomic profile of patients treated for head and neck cancers (HNCs) and correlate it with the risk of developing severe radiation-related oral mucositis (OM). Study Design Forty-one patients with oral squamous cell carcinoma (OSCC) who underwent adjuvant radiotherapy (RT) or chemoradiotherapy (CRT) were included. All patients were submitted to dental conditioning protocols prior to RT. OM and OM-related pain were evaluated daily during RT and graded according to the Common Toxicity Criteria for Adverse Events (National Cancer Institute, version 4.0, 2010) and the visual analogue scale (VAS). For the molecular analysis, whole saliva was collected immediately before RT and subjected to proteomic analysis by means of liquid chromatography–mass spectrometry (LTQ Orbitrap Velos MS; Thermo Fisher Scientific, Bremen, Germany) and label-free protein quantification. The results obtained from the targeted proteomic analysis were compared with OM clinical outcomes. Statistical analysis was performed by using Wilcoxon's test. Results Of the study patients, 73% presented with stage III/IV OSCC; 58% were submitted to CRT protocols, with a mean RT dose of 66 Gy. Most of the patients (66%) had visible tumor areas at the time of saliva collection; 43.9% had grade 2 and 31.7% had grade 3 as the highest OM grade during RT, with a mean highest reported VAS score of 3.53. For the target proteomics analysis, a total of 65 proteins were observed to be mostly related to biologic processes, such as immune responses, peptidase inhibitor activity, and the inflammatory system. The macrophage migration inhibitory factor (MIF HUMAN) was statistically significant when correlated with OM grade. MIF was observed in patients with grades 1 to 4 OM and showed higher abundance for OM grades 3 and 4 compared with grades 1 and 2 (P = .04). Conclusions The correlation of MIF with the severity of OM is compatible with the role of MIF as a proinflammatory protein. This seems to be the first study to describe this association; therefore, future prospective studies would be ideal to observe pre- and post-RT alterations in salivary MIF levels to validate this result and better understand the role of MIF in the pathogenesis of OM.

Oral microbial influences on oral mucositis during radiotherapy treatment of head and neck cancer.

Oral mucositis (OM) remains a significant complication developed by many patients undergoing radiotherapy (RT) to the head and neck region. Emerging data suggest oral microbes may contribute to the onset and severity of this acute side effect. In this study, saliva and oral swabs from head and neck cancer patients undergoing RT were collected. We employed molecular microbiological techniques to study the bacterial communities present in saliva, and both the bacterial and fungal communities present on the buccal mucosa and lateral tongue. Changes in microbiota composition with increasing radiation dose and the presence of mucositis were examined. The data suggest that the salivary microbiota remain stable during RT and are consistently dominated by Streptococcus, Prevotella, Fusobacterium and Granulicatella. Obligate and facultative anaerobic Gram-negative bacilli (GNB) Bacteroidales G2, Capnocytophaga, Eikenella, Mycoplasma and Sneathia, as well as anaerobic GNB in the periopathogenic genera Porphyromonas and Tannerella, were all positively correlated with ≥ grade 2 OM. Significant increases in the relative abundances of Bacteroidales G2, Fusobacterium and Sneathia were identified in buccal mucosa swabs at sites of ≥ grade 2 OM (p < 0.05). Furthermore, the abundance of several GNB (Fusobacterium, Haemophilus, Tannerella, Porphyromonas and Eikenella) on the buccal mucosa may influence patient susceptibility to developing OM. Candida was widely detected in buccal mucosa swabs, regardless of mucositis status. Our findings support previously hypothesized associations between oral health and the pathogenesis of OM, highlighting the importance of oral health interventions for head and neck cancer patients.

Methotrexate in saliva and risk in the development of chemotherapeutic mucositis in children

The aim of the study was to assess the possible direct effect of anticancer therapy with methotrexate (MTX) in bio liquids on the oral mucosa in the development of oral mucositis (OM). Twenty one children and adolescents participated in this study. Chemotherapy with MTX was administered in the following concentrations of 1; 2; 5 g/m2 of body surface area during 24 hours (including four episodes with OM). Twenty seven episodes of chemotherapy with high dose MTX were assessed in the samples of saliva on the 6th; 12; 24; 42; 48; 54 hour from the start of infusion and in the samples of blood on the 42; 48; 54 hour from the start of infusion. Сoncentration of methotrexate was measured by standard fluorescent polarization immunoassay using MTX reagent pac kit according to the manufacturer's instructions. Analysis of dynamics of methotrexate concentration in samples was performed using a linear model of mixed effects, on the basis of which the average values ​​(M) and confidence intervals for them were calculated (95 % CI). The analysis of the correlation of the levels of methotrexate in the blood and oral liquid was performed at individual time points (42; 48 and 54 hours) using the Spearman method (r). It was determined that excretion of MTX in the oral cavity repeated its clearance in blood. MTX concentration in saliva was less than 1/10 from its concentration in blood. During the first day, MTX concentration had decimicromol level and then until 54 hour it had santimicromol level. MTX concentration in saliva on the 6; 12; 24 hour in children with OM was lower by 2 times than in children without OM (P &lt; 0,001). There was no significant difference in those parameters between two groups (with or without OM) in the following observed hours. This data does not support hypothesis concerning involvement of salivary MTX in OM pathogenesis.

Regulation of HMGB1 release protects chemoradiotherapy-associated mucositis

Oral mucositis (OM) is a common complication in cancer patients undergoing anticancer treatment. Despite the clinical and economic consequences of OM, there are no drugs available for its fundamental control. Here we show that high-mobility group box 1 (HMGB1), a “danger signal” that acts as a potent innate immune mediator, plays a critical role in the pathogenesis of OM. In addition, we investigated treatment of OM through HMGB1 blockade using NecroX-7 (tetrahydropyran-4-yl)-[2-phenyl-5-(1,1-dioxo-thiomorpholin-4-yl)methyl-1Hindole-7-yl]amine). NecroX-7 ameliorated basal layer epithelial cell death and ulcer size in OM induced by chemotherapy or radiotherapy. This protective effect of NecroX-7 was mediated by inhibition of HMGB1 release and downregulation of mitochondrial oxidative stress. Additionally, NecroX-7 inhibited the HMGB1-induced release of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and macrophage inflammatory protein (MIP)-1β, as well as the expression of p53-upregulated modulator of apoptosis (PUMA) and the excessive inflammatory microenvironment, including nuclear factor-kB (NF-kB) pathways. In conclusion, our findings suggest that HMGB1 plays a key role in the pathogenesis of OM; therefore, blockade of HMGB1 by NecroX-7 may be a novel therapeutic strategy for OM.

Chemotherapy-induced oral mucositis and associated infections in a novel organotypic model.

Oral mucositis is a common side effect of cancer chemotherapy, with significant adverse impact on the delivery of anti-neoplastic treatment. There is a lack of consensus regarding the role of oral commensal microorganisms in the initiation or progression of mucositis because relevant experimental models are non-existent. The goal of this study was to develop an in vitro mucosal injury model that mimics chemotherapy-induced mucositis, where the effect of oral commensals can be studied. A novel organotypic model of chemotherapy-induced mucositis was developed based on a human oral epithelial cell line and a fibroblast-embedded collagen matrix. Treatment of organotypic constructs with 5-fluorouracil (5-FU) reproduced major histopathologic characteristics of oral mucositis, such as DNA synthesis inhibition, apoptosis and cytoplasmic vacuolation, without compromising the three-dimensional structure of the multilayer organotypic mucosa. Although structural integrity of the model was preserved, 5-FU treatment resulted in a widening of epithelial intercellular spaces, characterized by E-cadherin dissolution from adherens junctions. In a neutrophil transmigration assay we discovered that this treatment facilitated transport of neutrophils through epithelial layers. Moreover, 5-FU treatment stimulated key proinflammatory cytokines that are associated with the pathogenesis of oral mucositis. 5-FU treatment of mucosal constructs did not significantly affect fungal or bacterial biofilm growth under the conditions tested in this study; however, it exacerbated the inflammatory response to certain bacterial and fungal commensals. These findings suggest that commensals may play a role in the pathogenesis of oral mucositis by amplifying the proinflammatory signals to mucosa that is injured by cytotoxic chemotherapy.