Chemotherapy Induces Oral Mucositis in Mice Without Additional Noxious Stimuli

Targeting anti-apoptotic mechanisms in tumour cells: Strategies for enhancing Cancer therapy

Anti-cancer drug's cytotoxicity is determined by their ability to induce predetermined cell demise, commonly called apoptosis. The cancer-causing cells are able to evade cell death, which has been affiliated with both malignancy as well as resistance to cancer treatments. In order to avoid cell death, cancerous tumour cells often produce an abundance of anti-apoptotic proteins, becoming "dependent" on them. Consequently, protein inhibitors of cell death may prove to be beneficial as pharmacological targets for the future creation of cancer therapies. This article examines the molecular routes of apoptosis, its clinical manifestations, anti-cancer therapy options that target the intrinsic mechanism of apoptosis, proteins that prevent cell death, and members of the B-lymphoma-2 subset. In addition, novel approaches to cell death are highlighted, including how curcumin mitigates chemotherapy-induced apoptosis in healthy tissues and the various ways melatonin modifies apoptosis to improve cancer treatment efficacy, particularly through the TNF superfamily. Cancer treatment-induced increases in anti-apoptotic proteins lead to drug resistance; yet, ligands that trigger cell death by inhibiting these proteins are expected to improve chemotherapy's efficacy. The potential of frequency-modulated dietary phytochemicals as a cancer therapeutic pathway, including autophagy and apoptosis, is also explored. This approach may be more efficient than inhibition alone in overcoming drug resistance. Consequently, this method has the potential to allow for lower medication concentrations, reducing cytotoxicity and unwanted side effects.

The Protective Effects of MSC-Derived Exosomes Against Chemotherapy-Induced Parotid Gland Cytotoxicity

Background: Fluorouracil (5-FU) is one of the most popular chemotherapeutic agents used in various cancer therapy protocols. Cell-free therapy utilizing exosomes is gaining increased popularity as a safer option due to concerns over potential tumor progression following stem cell therapy. Methods: Parotid glands of albino were treated with a single bone marrow mesenchymal stem cell (BMMSC)-derived exosomes injection (100 μg/kg/dose suspended in 0.2 mL phosphate-buffered saline [PBS]), a single 5-Fu injection (20 mg/kg), and BMMSC-derived exosomes plus 5-FU and compared to control group (daily saline injections). After 30 days, the parotid glands were examined using qualitative histological evaluation, immunohistochemical evaluation using rabbit polyclonal mouse antibody to Ki-67, caspase 3, and iNOS, as well as quantitative real-time polymerase chain reaction (RT-PCR) to evaluate gene expression of TGFβ1, TNF-α, and BCL-2. Results: Histological examination of the parotid gland revealed that BMMSC-derived exosomes restored the glands' architecture and repaired most of the distortion created by 5-FU. Immunohistochemical expression of tumor proliferation and cell death markers were restored to normal levels in the exosome-treated groups that were similar to the control group. Furthermore, BMMSC-derived exosomes reversed the effects of 5-FU on quantitative gene expression levels and showed a significant decrease in TNF-α (p < 0.001) and a significant increase in TGFβ (p < 0.0001) and BCL-2 (p < 0.05) when compared to 5-FU treatment. Conclusion: Within the limitations of the current study, BMMSC-derived exosomes have the potential to counteract the cytotoxic effects of 5-FU on the parotid glands of rats in vivo. Further studies are deemed necessary to simulate clinical scenarios.

Leukopenia, weight loss and oral mucositis induced by 5-Fluorouracil in hamsters' model: A regenerative approach using electrospun poly(Lactic-co-Glycolic Acid) membrane

Clinical parameters of leukogram and weight were analyzed in animal models before and after seven days of 5-FU infusions. A comparison of leukograms before and after 5-FU administrations was analyzed. The results showed a significant difference (p = 0,004), confirming immunosuppression. There was a decrease in the weight of the animals after 7 days of 5-FU infusions (p = 0.02). After immunosuppression occurred, oral mucositis (OM) ulcerative lesions were observed. Two of the animals were selected to receive PLGA dressings. Then, electrospun PLGA membranes, with or without autologous cells, were applied to the ulcerative lesions, aiming to accelerate the regeneration process. Although this therapeutic innovation for OM lesions was still not tested in the bioengineering area, morphological analysis presented promising results. Lesions covered by cell-free PLGA, exhibited areas of inflammation persistence and angiogenesis. The cell-seeded cell-seeded PLGA membrane exhibited complete reepithelialization after 6 days, with minor inflammatory infiltrate. Interestingly, the present work showed preclinical parameters of cachexia induced by chemotherapy for cancer treatment. Moreover, it showed an innovative approach by applying dressings consisting of electrospun PLGA with the addition of autologous mesenchymal cells for OM ulcerative lesions. This promising innovation will pave the way for future applications in oral mucosa lesions.

Potentiality of Curcumin Against Radio-Chemotherapy Induced Oral Mucositis: A Review

In recent era, cancer is a major global health hazard and is mostly treated with either radio or chemotherapy. The above treatment procedure induces a secondary concern named as oral mucositis (OM). The disorder OM is specifically associated with oral mucosa and leads to bleeding, pain, difficulty in swallowing of solids, as well as fluids and speech difficulty. Curcumin is explored for prevention as well as treatment of OM. The article was organized via collection of enormous literatures by using the keywords like oral mucositis, chemotherapy, anti-inflammatory, curcumin, and clinical trials from search engines of different domains like Scopus, PubMed/MEDLINE, Science Direct, and Google Scholar with an increasing order of their year of publications. A numerous antineoplastic therapies resulted OM, as a devastating side effect. Moreover, the expanded pathogenesis of the disease permits a sound predictability over the patient's risk, thereby directing its adaptability and management protocols towards the achievement of novel therapeutics. An augmented interest towards curcumin as a potential therapeutic emerged because of its easy accessibility, antioxidant, anti-inflammatory, antiulcer, antimicrobial, and wound-healing abilities along with reduced side effects. Curcumin can potentially alter OM and OM-induced weight loss but showed a great heterogeneity.

Graphical Abstract

Cold Atmospheric Pressure Plasma May Prevent Oral Mucositis-Related Candidemia in Chemotherapy-Treated Rats

Oral mucositis associated with candidiasis can causes systemic candidemia, posing a risk to cancer patients administered antineoplastic therapy. Cold atmospheric pressure plasma jets (CAPPJs) have antifungal and anti-inflammatory properties. This study evaluated the effects CAPPJs in preventing systemic fungal dissemination in a murine model of oral mucositis associated with candidiasis. Forty Wistar rats were divided into groups: CAPPJs (treated) and non-treated controls (for comparison), with subgroups subject to 24 and 72 h of treatment (n = 10 each). Four cycles of chemotherapy (cisplatin and 5-fluorouracil (5-FU)) were administered, followed by oral inoculation of Candida albicans for 3 days. Mucosal damage was induced on the lateral side of tongue with 50% acetic acid. CAPPJ treatment was performed on the lesion for 5 min (2 days). Body weight was assessed daily. Fungal dissemination was conducted using organ macerates and plated on Sabouraud Agar with chloramphenicol. Blood samples were obtained for blood count tests. Chemotherapy affected the general health of the animals, as evidenced by body weight loss. Treatment with CAPPJs showed an inhibitory effect on C. albicans, with a significant reduction in fungal recovery from the tongue after 24 h (p < 0.05). Interestingly, systemic fungal dissemination was significantly reduced after 24 and 72 h of treatment when compared to control (p < 0.05). Taken together, these results suggest that CAPPJs have potential for clinical application in patients with oral mucositis at risk of candidemia.

Kinetics of neutrophil extracellular traps and cytokines in oral mucositis and Candida infection

OBJECTIVE

This study investigated the concentrations of neutrophil extracellular traps (NET) and salivary cytokines (IL-1β, IL-6, IL-8/CXCL8, TNF, and TGF-β1) in patients undergoing chemotherapy and their associations with oral mucositis (OM) and Candida infection.

MATERIALS AND METHODS

This prospective longitudinal study performed at a Brazilian service included 60 adults diagnosed with hematolymphoid diseases. Saliva samples were collected on days D0, D3, D10, and D15. Cytokines were analyzed by ELISA and NET formation by identification of the myeloperoxidase-DNA complex. Oral Candida spp. was cultured.

RESULTS

OM occurred in 43.3% of patients and oral candidiasis in 20%. However, 66% of individuals had positive cultures for C. albicans. Higher concentrations of IL-6, IL-8/CXCL8, and TNF and lower concentrations of TGF-β1 were observed in patients with OM. C. albicans infection contributed to the increase in IL-8/CXCL8, TGF-β1, and TNF. Individuals with OM or with oral candidiasis had significant reductions in NET formation. In contrast, individuals with C. albicans and with concomitant C. albicans and OM exhibited higher NET formation.

CONCLUSION

The kinetics of cytokine levels and NET formation in chemotherapy-induced OM appears to be altered by Candida infection, even in the absence of clinical signs of oral candidiasis.

Powder diet exacerbates oropharyngeal candidiasis in a mouse model

This study reports on the influence of a powder diet in a mouse model of oropharyngeal candidiasis (OPC), a significant health concern caused primarily by Candida albicans. Despite identical nutritional composition, we found that a powdered diet significantly increased Candida burdens and oral lesions, and aggravated weight loss compared to a standard pelleted diet. High fungal burdens and severe oral lesions were accomplished within 48 hours after infection with only one dose of cortisone. Moreover, mice on a powder diet recovered a week after infection. Using a powder diet, we thus modified the cortisone OPC murine model in a way that simplifies the infection process, enhances reproducibility, and facilitates studies investigating both pathogenesis and recovery processes. Our findings also underscore the pivotal role of the physical form of the diet in the progression and severity of oral Candida infection in this model. Future research should investigate this relationship further to broaden our understanding of the underlying mechanisms, potentially leading to novel prevention strategies and improved disease management.IMPORTANCEOropharyngeal candidiasis (OPC) is a multifactorial disease and a significant health concern. We found that the physical form of the diet plays a critical role in the severity and progression of OPC. We developed a modified cortisone OPC murine model that facilitates studies investigating pathogenesis and recovery processes.

Cell-penetrating peptides for transmucosal delivery of proteins

Enabling non-invasive delivery of proteins across the mucosal barriers promises improved patient compliance and therapeutic efficacies. Cell-penetrating peptides (CPPs) are emerging as a promising and versatile tool to enhance protein and peptide permeation across various mucosal barriers. This review examines the structural and physicochemical attributes of the nasal, buccal, sublingual, and oral mucosa that hamper macromolecular delivery. Recent development of CPPs for overcoming those mucosal barriers for protein delivery is summarized and analyzed. Perspectives regarding current challenges and future research directions towards improving non-invasive transmucosal delivery of macromolecules for ultimate clinical translation are discussed.

Achyrocline B (3,5 dihydroxy-6,7,8-trimethoxyflavone) synergizes with 5-fluorouracil allowing for dose reduction and reduced off-target toxicity in the treatment of colonic and pancreatic cancers

Surgically unresectable colorectal and pancreatic carcinomas have a high rate of mortality as current therapeutic options are limited. One common chemotherapeutic used to broadly treat both cancers is 5-flurouracil (5-Fu); however, treatment serves only to slow progression of the disease and comes with many side effects due to 5-Fu's intrinsic toxicity. Thus, strategies to decrease the dose of 5-Fu utilized therapeutically as well as reduce 5-Fu's off-target toxicity are paramount. Using cell models of colorectal and pancreatic cancers, we show that cotreatment with Achyrocline B (3,5 dihydroxy-6,7,8-trimethoxyflavone, AcB), a natural flavone from Achyrocline bogotensis, allows for four-fold reduction in 5-Fu dosage without loss of efficacy. We further show that the action of AcB is due to continued cell cycle progression despite 5-Fu pressure to synchronize at the G1/S threshold. In addition to AcB's effect on cancer cells, we found that AcB can directly reduce toxicity of 5-Fu in cells mimicking non-cancerous tissues. These in vitro results are then supported by xenograft modeling. AcB was shown to increase apoptosis in tumors leading to degeneration of the outer tumoral boundary. Furthermore, in 5-Fu treated animals it was found that AcB provided protection to the intestinal tract as indicated by preserved histological and immunohistochemical features. These results show promise for a new adjuvant therapy for colorectal and pancreatic carcinomas that not only reduces tumor progression, but more importantly has the potential to improve patient quality of life.

Assessment of Oxidative Stress-Induced Oral Epithelial Toxicity

Reactive oxygen species (ROS) are highly reactive molecules generated in living organisms and an excessive production of ROS culminates in oxidative stress and cellular damage. Notably, oxidative stress plays a critical role in the pathogenesis of a number of oral mucosal diseases, including oral mucositis, which remains one of cancer treatments' most common side effects. We have shown previously that oral keratinocytes are remarkably sensitive to oxidative stress, and this may hinder the development and reproducibility of epithelial cell-based models of oral disease. Here, we examined the oxidative stress signatures that parallel oral toxicity by reproducing the initial events taking place during cancer treatment-induced oral mucositis. We used three oral epithelial cell lines (an immortalized normal human oral keratinocyte cell line, OKF6, and malignant oral keratinocytes, H357 and H400), as well as a mouse model of mucositis. The cells were subjected to increasing oxidative stress by incubation with hydrogen peroxide (H2O2) at concentrations of 100 μM up to 1200 μM, for up to 24 h, and ROS production and real-time kinetics of oxidative stress were investigated using fluorescent dye-based probes. Cell viability was assessed using a trypan blue exclusion assay, a fluorescence-based live-dead assay, and a fluorometric cytotoxicity assay (FCA), while morphological changes were analyzed by means of a phase-contrast inverted microscope. Static and dynamic real-time detection of the redox changes in keratinocytes showed a time-dependent increase of ROS production during oxidative stress-induced epithelial injury. The survival rates of oral epithelial cells were significantly affected after exposure to oxidative stress in a dose- and cell line-dependent manner. Values of TC50 of 800 μM, 800 μM, and 400 μM were reported for H400 cells (54.21 ± 9.04, p < 0.01), H357 cells (53.48 ± 4.01, p < 0.01), and OKF6 cells (48.64 ± 3.09, p < 0.01), respectively. Oxidative stress markers (MPO and MDA) were also significantly increased in oral tissues in our dual mouse model of chemotherapy-induced mucositis. In summary, we characterized and validated an oxidative stress model in human oral keratinocytes and identified optimal experimental conditions for the study of oxidative stress-induced oral epithelial toxicity.

High molecular weight hyaluronic acid drastically reduces chemotherapy-induced mucositis and apoptotic cell death

Oral and intestinal mucositis (OIM) are debilitating inflammatory diseases initiated by oxidative stress, resulting in epithelial cell death and are frequently observed in cancer patients undergoing chemo-radiotherapy. There are currently few preventative strategies for this debilitating condition. Therefore, the development of a safe and effective mucositis mitigating strategy is an unmet medical need. Hyaluronic acid (HA) preparations have been tentatively used in oral mucositis. However, the protective effects of HA in chemotherapy-induced mucositis and their underlying mechanisms remain to be fully elucidated. This study aimed to assess these mechanisms using multiple formulations of enriched HA (Mucosamin^®), cross-linked (xl-), and non-crosslinked high molecular weight HA (H-MW-HA) in an oxidative stress-induced model of human oral mucosal injury in vitro and an in vivo murine model of 5-flurouracil (5-FU)-induced oral/intestinal mucositis. All tested HA formulations protected against oxidative stress-induced damage in vitro without inducing cytotoxicity, with H-MW-HA also significantly reducing ROS production. Daily supplementation with H-MW-HA in vivo drastically reduced the severity of 5-FU-induced OIM, prevented apoptotic damage and reduced COX-2 enzyme activity in both the oral and intestinal epithelium. In 5-FU-injected mice, HA supplementation also significantly reduced serum levels of IL-6 and the chemokine CXCL1/KC, while the serum antioxidant activity of superoxide dismutase was elevated. Our data suggest that H-MW-HA attenuates 5-FU-induced OIM, at least partly, by impeding apoptosis, inhibiting of oxidative stress and suppressing inflammatory cytokines. This study supports the development of H-MW-HA preparations for preventing OIM in patients receiving chemotherapy.

Protective Effect of Electroacupuncture on Chemotherapy-Induced Salivary Gland Hypofunction in a Mouse Model

Radiotherapy and chemotherapy can impair salivary gland (SG) function, which causes xerostomia and exacerbate other side effects of chemotherapy and oral infection, reducing patients' quality of life. This animal study aimed to assess the efficacy of electroacupuncture (EA) as a means of preventing xerostomia induced by 5-fluorouracil (5-FU). A xerostomia mouse model was induced via four tail vein injections of 5-FU (80 mg/kg/dose). EA was performed at LI4 and LI11 for 7 days. The pilocarpine-stimulated salivary flow rate (SFR) and salivary glands weight (SGW) were recorded. Salivary immunoglobulin A (SIgA) and lysozyme were determined via enzyme-linked immunosorbent assay (ELISA). SG was collected for hematoxylin and eosin staining to measure acini number and acinar cell size. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and aquaporin 5 (AQP5) mRNA expressions in SG were quantified via RT-qPCR. 5-FU caused significant decreases in SFR, SGW, SIgA, lysozyme, AQP5 expression, and acini number, while TNF-α and IL-1β expressions and acinar cell size were significantly increased. EA treatment can prevent 5-FU damage to the salivary gland, while pilocarpine treatment can only elevate SFR and AQP5 expression. These findings provide significant evidence to support the use of EA as an alternative treatment for chemotherapy-induced salivary gland hypofunction and xerostomia.

Rodent models for anticancer toxicity studies: contributions to drug development and future perspectives

Antineoplastic treatment induces a type of gastrointestinal toxicity known as mucositis. Findings in animal models are usually easily reproducible, and standardized treatment regimens are often used, thus supporting translational science. Essential characteristics of mucositis, including intestinal permeability, inflammation, immune and oxidative responses, and tissue repair mechanisms, can be easily investigated in these models. Given the effects of mucositis on the quality of life of patients with cancer, and the importance of experimental models in the development of more effective new therapeutic alternatives, this review discusses progress and current challenges in using experimental models of mucositis in translational pharmacology research. Teaser Experimental models for studying gastrointestinal mucositis have provided a wealth of information improving the understanding of antineoplastic toxicity.

Sprayable NAHAO® hydrogel alleviates pain and accelerates rat oral mucositis wound healing

OBJECTIVE

To investigate the promote healing and analgesic effects of NAHAO® Brand Nazhen oral antibacterial care solution (NAHAO® spray) on the 5-fluorouracil-induced oral mucositis in rats.

MATERIAL AND METHOD

Sixty male SD rats were randomly divided into normal group, model group, recombinant human epidermal growth factor (rhEGF) group, NAHAO® spray group, and 1/3 concentration of NAHAO® spray group. 5-FU was injected intraperitoneally on the first and third days of the experimental model, and OM was induced using mechanical trauma on the third and fifth days. Wound healing quality was assessed by the appearance of mucosa and histological images on day6 and day10. Pain is measured by facial grooming behavior stimulated by capsaicin, the alternation of body weight and food intake was also recorded to reflect the OM pain. To examine the involvement of the cyclooxygenase pathway in the mechanism underlying oral mucositis, we detected the expression of cyclooxygenase2(COX-2) and matrix metalloproteinase 9(MMP9) via immunohistochemical staining and determined the PGE2 concentrations in rats' serum during healing of oral mucositis.

RESULTS

NAHAO® spray attenuated pathological damage and reduced pain sensitivity effectively. COX-2 expression levels were inhibited in the NAHAO® spray-treated group. The concentration of PGE2 and the expression of MMP9 were inhibited in NAHAO®-treated rats. Compared with normal rats, the elevated rubbing time following capsaicin stimulation in the model was completely inhibited after being treated with NAHAO® spray.

CONCLUSION

NAHAO® spray alleviated OM-induced pain and promoted wound healing partly by inhibiting the cyclooxygenase-related pathway.

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.

A Rat Model for Oral Mucositis Induced by a Single Administration of 5-Fluorouracil

BACKGROUND/AIM

This study aimed to develop a reliable chemotherapy-induced oral mucositis (CIOM) rat model by intraperitoneally administering a single dosage of 5-fluorouracil (5-FU) combined with a chemical stimulus.

MATERIALS AND METHODS

The 5-FU dosage for CIOM development was determined by the survival rate of rats administrated 160 mg/kg, 200 mg/kg, and 240 mg/kg of 5-FU. Thirty rats were assigned to normal control (NC) and three experimental groups: i) ulcer formation without 5-FU administration (PBS/U+), ii) 5-FU administration without ulcer formation (5-FU/U-), and iii) ulcer formation after 5-FU administration (5-FU/U+). White blood cell count and weight were measured at the day of 5-FU administration (D0), ulcer formation (D2), and two days after ulcer formation (D4). The oral mucosa for histologic evaluations was obtained two (D4) and five days (D7) after ulcer formation.

RESULTS

The 5-FU dosage for CIOM development was 200 mg/kg. White blood cell count (WBC) counts and weight of rats were significantly lower in 5-FU/U- (WBC, p<0.001; weight, p=0.002) and 5-FU/U+ (WBC, p<0.001; weight, p<0.001) groups compared to those in the NC group at D4. The number of Ki-67 positive cells in the oral epithelium was lower in 5-FU/U+ group compared to that in NC (p<0.001) and PBS/U+ (p=0.047) groups at D7.

CONCLUSION

Single administration of 200 mg/kg of 5-FU combined with a chemical stimulus can lead to an immune-suppressive status, failure of weight gain, and impairment of epithelium regeneration as observed in a CIOM rat model.

MKI67 an potential oncogene of oral squamous cell carcinoma via the high throughput technology

Oral squamous cell carcinoma is a malignant tumor that occurs in the oral cavity, with poor prognosis and easy recurrence. However, the relationship between MKI67 and oral squamous cell carcinoma remains unclear. The oral squamous cell carcinoma datasets GSE138206, GSE146483 and GSE184616 were downloaded from the gene expression omnibus database, and the differentially expressed genes (DEGs) were screened. The protein-protein interaction network was constructed and analyzed by search tool for the retrieval of interacting genes database and Cytoscape software. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) were used for functional enrichment analysis. GO and KEGG analyses were performed on the whole genome, as formulated by gene set enrichment analysis. comparative toxicogenomics database was used to identify the diseases most associated with the core genes. TargetScan was used to screen miRNA regulating central DEGs. A total of 1472 DEGs were identified. GO analysis showed that the differentially expressed genes were mainly enriched in the tissues of extracellular matrix, type i interferon signaling pathway, human papillomavirus infection, adhesion spot, hepatitis C and ECM-receptor interaction. Enrichment items were similar to GO and KEGG enrichment items of differentially expressed genes. 10 core genes were obtained, and their expression was different between oral squamous cell carcinoma and normal tissue samples. MKI67 is highly expressed in oral squamous cell carcinoma and may be an oncogene in oral squamous cell carcinoma.

Experimental Chemotherapy-Induced Mucositis: A Scoping Review Guiding the Design of Suitable Preclinical Models

Mucositis is a common and most debilitating complication associated with the cytotoxicity of chemotherapy. The condition affects the entire alimentary canal from the mouth to the anus and has a significant clinical and economic impact. Although oral and intestinal mucositis can occur concurrently in the same individual, these conditions are often studied independently using organ-specific models that do not mimic human disease. Hence, the purpose of this scoping review was to provide a comprehensive yet systematic overview of the animal models that are utilised in the study of chemotherapy-induced mucositis. A search of PubMed/MEDLINE and Scopus databases was conducted to identify all relevant studies. Multiple phases of filtering were conducted, including deduplication, title/abstract screening, full-text screening, and data extraction. Studies were reported according to the updated Preferred Reporting Items for Systematic reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. An inter-rater reliability test was conducted using Cohen's Kappa score. After title, abstract, and full-text screening, 251 articles met the inclusion criteria. Seven articles investigated both chemotherapy-induced intestinal and oral mucositis, 198 articles investigated chemotherapy-induced intestinal mucositis, and 46 studies investigated chemotherapy-induced oral mucositis. Among a total of 205 articles on chemotherapy-induced intestinal mucositis, 103 utilised 5-fluorouracil, 34 irinotecan, 16 platinum-based drugs, 33 methotrexate, and 32 other chemotherapeutic agents. Thirteen articles reported the use of a combination of 5-fluorouracil, irinotecan, platinum-based drugs, or methotrexate to induce intestinal mucositis. Among a total of 53 articles on chemotherapy-induced oral mucositis, 50 utilised 5-fluorouracil, 2 irinotecan, 2 methotrexate, 1 topotecan and 1 with other chemotherapeutic drugs. Three articles used a combination of these drugs to induce oral mucositis. Various animal models such as mice, rats, hamsters, piglets, rabbits, and zebrafish were used. The chemotherapeutic agents were introduced at various dosages via three routes of administration. Animals were mainly mice and rats. Unlike intestinal mucositis, most oral mucositis models combined mechanical or chemical irritation with chemotherapy. In conclusion, this extensive assessment of the literature revealed that there was a large variation among studies that reproduce oral and intestinal mucositis in animals. To assist with the design of a suitable preclinical model of chemotherapy-induced alimentary tract mucositis, animal types, routes of administration, dosages, and types of drugs were reported in this study. Further research is required to define an optimal protocol that improves the translatability of findings to humans.

Natural Products for the Prevention and Treatment of Oral Mucositis-A Review

Cancer, a major world public health problem, is associated with chemotherapy treatments whose administration leads to secondary concerns, such as oral mucositis (OM). The OM disorder is characterized by the presence of ulcers in the oral mucosa that cause pain, bleeding, and difficulty in ingesting fluids and solids, or speaking. Bioactive compounds from natural sources have arisen as an effective approach for OM. This review aims to summarize the new potential application of different natural products in the prevention and treatment of OM in comparison to conventional ones, also providing a deep insight into the most recent clinical studies. Natural products, such as Aloe vera, Glycyrrhiza glabra, Camellia sinensis, Calendula officinalis, or honeybee crops, constitute examples of sources of bioactive compounds with pharmacological interest due to their well-reported activities (e.g., antimicrobial, antiviral, anti-inflammatory, analgesic, or wound healing). These activities are associated with the bioactive compounds present in their matrix (such as flavonoids), which are associated with in vivo biological activities and minimal or absent toxicity. Finally, encapsulation has arisen as a future opportunity to preserve the chemical stability and the drug bioa vailability of bioactive compounds and, most importantly, to improve the buccal retention period and the therapeutic effects.

Correlation of MKI67 with prognosis, immune infiltration, and T cell exhaustion in hepatocellular carcinoma

BACKGROUND

MKI67 plays a vital role in the tumour microenvironment (TME) and congenital immunity. The present work focuses on exploring the prognosis prediction performance of MKI67 and its associations with T cell activity and immune infiltration within numerous cancers, especially hepatocellular liver carcinoma (LIHC).

METHODS

Oncomine, GEPIA2, and HPA were adopted to analyse MKI67 levels in different types of cancers. The prognostic prediction performance of MKI67 was evaluated through the TCGA portal, GEPIA2, LOGpc, and Kaplan-Meier Plotter databases. The associations of MKI67 with related gene marker sets and immune infiltration were inspected through TISIDB, GEPIA2, and TIMER. We chose MKI67 to analyse biological processes (BPs) and KEGG pathways related to the coexpressed genes. Furthermore, the gene-miRNA interaction network for MKI67 in liver cancer was also examined based on the miRWalk database.

RESULTS

MKI67 expression decreased in many cancers related to the dismal prognostic outcome of LIHC. We found that MKI67 significantly affected the prognosis of LIHC in terms of histology and grade. Increased MKI67 levels were directly proportional to the increased immune infiltration degrees of numerous immune cells and functional T cells, such as exhausted T cells. In addition, several critical genes related to exhausted T cells, including TIM-3, TIGIT, PD-1, LAG3, and CXCL13, were strongly related to MKI67. Further analyses showed that MKI67 was associated with adaptive immunity, cell adhesion molecules (CAMs), and chemokine/immune response signal transduction pathways.

CONCLUSION

MKI67 acts as a prognostic prediction biomarker in several cancers, particularly LIHC. Upregulation of MKI67 elevates the degree of immune infiltration of many immune cell subtypes, including functional T cells, CD4+ T cells, and CD8+ T cells. Furthermore, MKI67 shows a close correlation with T cell exhaustion, which plays a vital role in promoting T cell exhaustion within LIHC. Detection of the MKI67 level contributes to prognosis prediction and MKI67 modulation within exhausted T cells, thus providing a new method to optimize the efficacy of anti-LIHC immunotherapy.

Oral Administration of Melatonin or Succinyl Melatonin Niosome Gel Benefits 5-FU-Induced Small Intestinal Mucositis Treatment in Mice

Mucositis is one of the most adverse effects of 5-fluorouracil (5-FU) and had no standard drug for treatment. Melatonin is a neurohormone, and can ameliorate radiotherapy-induced small intestinal mucositis. Melatonin encapsulated in niosomes improved its poor bioavailability. Succinyl melatonin, a melatonin derivative, showed prolonged release compared with melatonin. This study investigated the efficacy of melatonin niosome gel (MNG) and succinyl melatonin niosome gel (SNG) in 5-FU-induced small intestinal mucositis treatment in mice. MNG and SNG with particle sizes of 293 and 270 nm were shown to have mucoadhesive potentials. The effect of a daily oral application of MNG, SNG, or fluocinolone acetonide gel (FAG, positive control) was compared to that of the normal group. The body weight, food consumption, histology, Fourier transform infrared (FTIR) spectroscopy, inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-1β), and malondialdehyde (MDA) in the small intestine were monitored. The results showed decreased %body weight and food consumption in all 5-FU-injected groups compared with the normal group. The MNG and SNG treatments maintained the food consumption and the normal integrity of the small intestines, as evidenced by villus length and crypt depth, similar to the observations in the normal groups. The FTIR spectra showed no change in lipids of the MNG and SNG groups compared with the normal group. Moreover, SNG could reduce IL-1β content to a level that was not different from the level in the normal groups. Therefore, the oral application of MNG and SNG could protect against 5-FU-induced small intestinal mucositis in mice.

Sublingual protein delivery by a mucoadhesive patch made of natural polymers

The sublingual mucosa is an appealing route for drug administration. However, in the context of increased use of therapeutic proteins, development of protein delivery systems that will protect the protein bioactivity is needed. As proteins are fragile and complex molecules, current sublingual formulations of proteins are in liquid dosage. Yet, protein dilution and short residence time at the sublingual mucosa are the main barriers for the control of the dose that is delivered. In this work, a simple delivery scaffold based on the assembly of two polysaccharides, chitosan and hyaluronic acid, is presented. The natural polymers were assembled by the Layer-by-Layer methodology to produce a mucoadhesive and oro-dispersible freestanding membrane, shown to be innocuous for epithelial human cells. The functionalization of the membrane with proteins led to the production of a bioactive patch with efficient loading and release of proteins, and suitable mechanical properties for manipulation. Sublingual administration of the patch in mouse evidenced the absence of inflammation and an extended time of contact between the model protein ovalbumin and the mucosa compared to liquid formulation. The delivery of fluorescent ovalbumin in mouse sublingual mucosa demonstrated the penetration of the protein in the epithelium 10 min after the patch administration. Moreover, a migration assay with a chemokine incorporated into the patch showed no decrease in bioactivity of the loaded protein after enzymatic release. This study therefore provides a promising strategy to develop a sublingual protein delivery system. STATEMENT OF SIGNIFICANCE: Although the oral route is largely used for drug delivery, it has limitations for the delivery of proteins that can be degraded by pH or gastric enzymes. The sublingual route therefore appears as an interesting approach for protein administration. In this work, a simple delivery scaffold is presented based on the assembly of two polysaccharides by the Layer-by-Layer methodology to produce a mucoadhesive patch. The produced patch allowed efficient loading and release of proteins, as well as protection of their bioactivity. An extended time of contact between the protein and the mucosa compared to liquid formulation was highlighted in mouse model. This study provides a promising strategy to develop a sublingual protein delivery system.

Understanding chemotherapy-induced intestinal mucositis and strategies to improve gut resilience

Intestinal mucositis remains one of the most debilitating side effects related to chemotherapy. The onset and persistence of mucositis is an intricate physiological process involving cross-communication between the specific chemotherapeutic drug, the immune system, and gut microbes that results in a loss of mucosal integrity leading to gut-barrier dysfunction. Intestinal mucositis has a severe impact on a patient's quality of life and negatively influences the outcome of treatment. Most importantly, intestinal mucositis is a major contributor to the decreased survival rates and early onset of death associated with certain chemotherapy treatments. Understanding the pathophysiology and symptomology of intestinal mucositis is important in reducing the negative consequences of this condition. Prophylaxis, early diagnosis, and proper symptom management are essential to improved survival outcomes in patients with cancer. This review focuses on the pathobiology of intestinal mucositis that accompanies chemotherapy treatments. In addition, we will discuss the therapeutic potential of select strategies that have shown promise in mitigating chemotherapies' off-target effects without hampering their anticancer efficacy.NEW & NOTEWORTHY Intestinal mucositis, or damage to the intestinal mucosa, is a common side effect of chemotherapy. In this review, we describe the pathobiology of intestinal mucositis that is associated with chemotherapy treatments. In addition, we discuss the efficacy of several potential therapeutic strategies that have shown some potential in alleviating chemotherapies' off-target effects.

Anticancer Activity of Fucoidan via Apoptosis and Cell Cycle Arrest on Cholangiocarcinoma Cell

OBJECTIVE

Many previous studies reported that fucoidan has antitumor activities. The objective of the present study was to determine the cytotoxic effects and related mechanisms of cell death induced by fucoidan extracted from Fucus vesiculosus on CL-6 cholangiocarcinoma cell.

METHODS

CL-6 and OUMS cells were treated with 0, 100, 200, and 300 μg/mL of fucoidan. MTT assay was used to determine cytotoxicity. Flow cytometry-based assay was used to examine the distribution of apoptosis and cell cycle. The changes in nuclear morphology were determined using Hoechst 33,342 staining. Mitochondrial membrane potential (ΔΨm) was evaluated using the JC-1 kit. The apoptotic, anti-apoptotic, and cell cycle-related proteins study were examined by Western blot analysis.

RESULTS

The relative viable cell number of treated CL-6 cells was decreased but no effect was observed in OUMS normal cells. Furthermore, treated cells were arrested in the G0/G1 phase with down-regulation of cyclin D1 and CDK4. Annexin V/PI staining with flow cytometry analysis suggested that fucoidan could induce apoptosis in CL-6 cells. Western blot study revealed the up-regulation of apoptotic markers including Bax, cleaved PARP, cleaved caspase-3, but down-regulation of anti-apoptotic markers,  cl-2. Moreover, fucoidan could induce nuclear fragmentation and chromatin condensation with alteration of ΔΨm.  Conclusion: Fucoidan exerts antitumor properties against CL-6 cholangiocarcinoma cells illustrated by the induction of apoptosis and cell cycle arrest.
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Lactobacillus reuteri DSM 17938 and ATCC PTA 5289 ameliorates chemotherapy-induced oral mucositis

Oral mucositis (OM) is a common complication of cancer therapy, however OM management remains unsatisfactory. There is a growing interest in the therapeutic potential of probiotics in OM due to positive findings of its use in intestinal mucositis. This study aimed to determine the efficacy and safety of the probiotic combination Lactobacillus reuteri DSM 17938 and ATCC PTA 5289 strains in chemotherapy-induced OM. Mice were divided into 4 groups. PBS/water and PBS/LR groups comprised of mice injected with PBS intraperitoneally (i.p.), and were given water or the mixture of L. reuteri (LR) DSM 17938 and ATCC PTA 5289 in water respectively. The 5-FU/water and 5-FU/LR groups comprised of mice injected with 5-FU i.p., and were given water or L. reuteri DSM 17938 and ATCC PTA 5289 in water respectively. Histopathological analysis revealed that the oral epithelia of the 5-FU/water and 5-FU/LR groups were thinner compared to PBS/water and PBS/LR groups. However, epithelial damage was significantly reduced in the 5-FU/LR compared to 5-FU/water group. Additionally, the 5-FU/LR group showed reduced oxidative stress and inflammation in the oral mucosa. We further showed that L. reuteri reduced oxidative stress through the nuclear factor E2-related factor-2 (Nrf-2) signalling. There was no evidence of translocation of L. reuteri systemically. This study demonstrated for the first time that L. reuteri protected oral mucosa against damage induced by chemotherapy.

The Dysbiosis and Inter-Kingdom Synergy Model in Oropharyngeal Candidiasis, a New Perspective in Pathogenesis

As more information emerges on oral microbiota using advanced sequencing methodologies, it is imperative to examine how organisms modulate the capacity of each other to colonize or trigger infection. Most mouse models of oral C. albicans infection have focused on interactions with single bacterial species. Thus, little is known about the microbiome-mediated interactions that control the switch of C. albicans from commensalism to infection. Evidence is accumulating that in immunosuppression where mucosal candidiasis is more prevalent, there is an altered oral bacterial microbiome with reduced diversity, but not an altered mycobiome. Oropharyngeal candidiasis in immunosuppressed humans and mice is associated with a further reduction in oral bacterial diversity and a dysbiotic shift with significant enrichment of streptococcal and enterococcal species. Our recent studies in a cancer chemotherapy mouse model supported the combined profound effect of immunosuppression and C. albicans in reducing oral bacterial diversity and provided the first direct evidence that these changes contribute to pathogenesis, representing dysbiosis. There is still a gap in understanding the relationship between Candida and the oral bacterial microbiome. We propose that certain oral commensal bacteria contribute to fungal pathogenesis and we identify gaps in our understanding of the mechanisms involved in this cooperative virulence.

In vitro evaluation of Eugenia dysenterica in primary culture of human gingival fibroblast cells

Eugenia dysenterica is a Brazilian tree investigated for its properties and bioactive compounds, which are believed to have both pharmacological and phytochemical therapeutic effects. The leaves of this tree contain tannins, flavonoids, terpenes, and saponins, with reportedly beneficial effects to the human body. Despite these therapeutic applications, its effects have never been tested on oral tissues. Therefore, the aim of the present study was to evaluate the cytotoxic and antioxidant effects and the anti-inflammatory and repair properties of the acetone fraction of E. dysenterica on primary culture of human gingival fibroblasts and on the immortalized murine macrophage cell line (RAW 264.7). For this purpose, a metabolic activity assay, a wound healing assay, a nitric oxide assay, and RT-qPCR were performed. The assays revealed a cytoprotective effect of this plant, suggested by the increase in the expression of SOD1 and NRF2. An antioxidant potential effect was observed in the DPPH• assay. However, the fraction of E. dysenterica did not show anti-inflammatory activity. In conclusion, Eugenia dysenterica may promote cytoprotection when associated with chlorhexidine digluconate because of its antioxidant effect. However, additional studies are necessary on other human dental tissues using other parts of the plant in order to develop a possible mouthwash to assist patients with oral disorders.

Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis

BACKGROUND

Gastrointestinal mucosal injury (mucositis), commonly affecting the oral cavity, is a clinically significant yet incompletely understood complication of cancer chemotherapy. Although antineoplastic cytotoxicity constitutes the primary injury trigger, the interaction of oral microbial commensals with mucosal tissues could modify the response. It is not clear, however, whether chemotherapy and its associated treatments affect oral microbial communities disrupting the homeostatic balance between resident microorganisms and the adjacent mucosa and if such alterations are associated with mucositis. To gain knowledge on the pathophysiology of oral mucositis, 49 subjects receiving 5-fluorouracil (5-FU) or doxorubicin-based chemotherapy were evaluated longitudinally during one cycle, assessing clinical outcomes, bacterial and fungal oral microbiome changes, and epithelial transcriptome responses. As a control for microbiome stability, 30 non-cancer subjects were longitudinally assessed. Through complementary in vitro assays, we also evaluated the antibacterial potential of 5-FU on oral microorganisms and the interaction of commensals with oral epithelial tissues.

RESULTS

Oral mucositis severity was associated with 5-FU, increased salivary flow, and higher oral granulocyte counts. The oral bacteriome was disrupted during chemotherapy and while antibiotic and acid inhibitor intake contributed to these changes, bacteriome disruptions were also correlated with antineoplastics and independently and strongly associated with oral mucositis severity. Mucositis-associated bacteriome shifts included depletion of common health-associated commensals from the genera Streptococcus, Actinomyces, Gemella, Granulicatella, and Veillonella and enrichment of Gram-negative bacteria such as Fusobacterium nucleatum and Prevotella oris. Shifts could not be explained by a direct antibacterial effect of 5-FU, but rather resembled the inflammation-associated dysbiotic shifts seen in other oral conditions. Epithelial transcriptional responses during chemotherapy included upregulation of genes involved in innate immunity and apoptosis. Using a multilayer epithelial construct, we show mucositis-associated dysbiotic shifts may contribute to aggravate mucosal damage since the mucositis-depleted Streptococcus salivarius was tolerated as a commensal, while the mucositis-enriched F. nucleatum displayed pro-inflammatory and pro-apoptotic capacity.

CONCLUSIONS

Altogether, our work reveals that chemotherapy-induced oral mucositis is associated with bacterial dysbiosis and demonstrates the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury. These findings suggest that control of oral bacterial dysbiosis could represent a novel preventive approach to ameliorate oral mucositis.

Candida albicans induces mucosal bacterial dysbiosis that promotes invasive infection

Infectious complications are a common cause of morbidity and mortality in cancer patients undergoing chemotherapy due to increased risk of oral and gastrointestinal candidiasis, candidemia and septicemia. Interactions between C. albicans and endogenous mucosal bacteria are important in understanding the mechanisms of invasive infection. We published a mouse intravenous chemotherapy model that recapitulates oral and intestinal mucositis, and myelosuppression in patients receiving 5-fluorouracil. We used this model to study the influence of C. albicans on the mucosal bacterial microbiome and compared global community changes in the oral and intestinal mucosa of the same mice. We validated 16S rRNA gene sequencing data by qPCR, in situ hybridization and culture approaches. Mice receiving both 5Fu and C. albicans had an endogenous bacterial overgrowth on the oral but not the small intestinal mucosa. C. albicans infection was associated with loss of mucosal bacterial diversity in both sites with indigenous Stenotrophomonas, Alphaproteobacteria and Enterococcus species dominating the small intestinal, and Enterococcus species dominating the oral mucosa. Both immunosuppression and Candida infection contributed to changes in the oral microbiota. Enterococci isolated from mice with oropharyngeal candidiasis were implicated in degrading the epithelial junction protein E-cadherin and increasing the permeability of the oral epithelial barrier in vitro. Importantly, depletion of these organisms with antibiotics in vivo attenuated oral mucosal E-cadherin degradation and C. albicans invasion without affecting fungal burdens, indicating that bacterial community changes represent overt dysbiosis. Our studies demonstrate a complex interaction between C. albicans, the resident mucosal bacterial microbiota and the host environment in pathogenesis. We shed significant new light on the role of C. albicans in shaping resident bacterial communities and driving mucosal dysbiosis.

Role of oral flora in chemotherapy-induced oral mucositis in vivo

OBJECTIVE

To determine if commensal oral microflora impacts the severity of chemotherapy-induced oral mucositis (OM).

DESIGN

Specific-pathogen-free (SPF) and germ-free Swiss Webster mice in the experimental groups were dosed with 5-fluorouracil (5-FU) to induce OM. Mice in the control group received phosphate buffered saline. Comparative analyses of the epithelial thickness and cell proliferation/turnover rates, as well as the expression levels of metalloproteinases and pro-inflammatory mediators in the oral mucosa between the control and experimental groups were determined by histopathological and immunohistochemical analyses.

RESULTS

5-FU-treated SPF and germ-free mice showed characteristic features of OM with reduced oral epithelial thickness, presence of inflammatory cells in the connective tissues, and increased levels of expression of metalloproteinases and pro-inflammatory cytokines compared to the respective control groups. When 5-FU-treated SPF and germ-free mice were compared, 5-FU-treated germ-free mice exhibited less severe epithelial destruction with higher expression of the cell proliferation marker Ki67, coupled with lower expression levels of metalloproteinases and pro-inflammatory cytokine in the oral mucosa.

CONCLUSION

This study provides the first histopathological evidence that oral flora has a detrimental effect on chemotherapy-induced OM in vivo.

Management of oral mucositis in pediatric patients receiving cancer therapy: A systematic review and meta-analysis

BACKGROUND

One of the most common complications of cancer chemotherapy is oral mucositis (OM). OM affects more than 75% of patients undergoing chemotherapy and represents a significant burden to patients and caregivers. We performed a systematic review and meta-analysis of published studies to investigate the effects of agents and techniques in reducing OM.

PROCEDURE

This systematic review investigated, critically appraised, and rated the evidence on agents used to manage OM in children undergoing cancer therapy. A comprehensive search of the relevant literature was performed from January 2006 to December 2017. MEDLINE, Scopus, the Cochrane Database of Systematic Reviews, EMBASE, and the Web of Science were searched. Nine eligible studies were identified. Using random-effects models, standardized mean difference was estimated between treated and control groups across all studies. The Cochran test and the I2 index were performed for heterogeneity between studies. The significance level was set at P = 0.05.

RESULTS

Palifermin reduced the incidence (OR = 4.131, P = 0.000), duration (St diff mean = 0.803, P = 0.000), and severity (St diff mean = 0.637, P = 0.000) of OM in pediatric cancer patients significantly. However, the laser did not show significant efficacy in decreasing the incidence rate of OM (OR = 2.870, P = 0.364).

CONCLUSION

This review provided a comprehensive examination of available options for children who have OM. The results support the possibility of a positive effect of palifermin on reducing OM in children receiving cancer therapy.

Mechanisms of apoptosis modulation by curcumin: Implications for cancer therapy

Cancer incidences are growing and cause millions of deaths worldwide. Cancer therapy is one of the most important challenges in medicine. Improving therapeutic outcomes from cancer therapy is necessary for increasing patients' survival and quality of life. Adjuvant therapy using various types of antibodies or immunomodulatory agents has suggested modulating tumor response. Resistance to apoptosis is the main reason for radioresistance and chemoresistance of most of the cancers, and also one of the pivotal targets for improving cancer therapy is the modulation of apoptosis signaling pathways. Apoptosis can be induced by intrinsic or extrinsic pathways via stimulation of several targets, such as membrane receptors of tumor necrosis factor-α and transforming growth factor-β, and also mitochondria. Curcumin is a naturally derived agent that induces apoptosis in a variety of different tumor cell lines. Curcumin also activates redox reactions within cells inducing reactive oxygen species (ROS) production that leads to the upregulation of apoptosis receptors on the tumor cell membrane. Curcumin can also upregulate the expression and activity of p53 that inhibits tumor cell proliferation and increases apoptosis. Furthermore, curcumin has a potent inhibitory effect on the activity of NF-κB and COX-2, which are involved in the overexpression of antiapoptosis genes such as Bcl-2. It can also attenuate the regulation of antiapoptosis PI3K signaling and increase the expression of MAPKs to induce endogenous production of ROS. In this paper, we aimed to review the molecular mechanisms of curcumin-induced apoptosis in cancer cells. This action of curcumin could be applicable for use as an adjuvant in combination with other modalities of cancer therapy including radiotherapy and chemotherapy.

The Relationship of Candida albicans with the Oral Bacterial Microbiome in Health and Disease

Candida albicans is an opportunistic pathogen colonizing the oropharyngeal, esophageal, and gastrointestinal mucosa in most healthy humans. In immunocompromised hosts, this fungal organism can cause mucosal candidiasis in these sites. C. albicans also causes fungemia, a serious consequence of cancer cytotoxic chemotherapy, which is thought to develop from fungal translocation through compromised mucosal barriers. Changes in endogenous bacterial population size or composition as well as changes in the host environment can transform fungal commensals into opportunistic pathogens in the upper and lower GI tract. Pioneering studies from our group have shown that a ubiquitous oral commensal of the mitis streptococcal group (Streptococcus oralis) has a mutualistic relationship with C. albicans, with C. albicans enabling streptococcal biofilm growth at mucosal sites, and S. oralis facilitating invasion of the oral and esophageal mucosa by C. albicans. In these studies, we used a cortisone-induced immunosuppression mouse model. More recently, the development of a novel mouse chemotherapy model has allowed us to examine the interactions of C. albicans with the endogenous bacterial microbiota in the oral and small intestinal mucosa, two sites adversely affected by cytotoxic chemotherapy. In this model, oral inoculation with C. albicans causes severe dysbiosis in the mucosal bacterial composition in both sites. We also found that antibiotic treatment ameliorates invasion of the oral mucosa but aggravates dissemination through the intestinal mucosa. In this chapter, we discuss work from our laboratory and others examining the relationships of C. albicans with oral bacteria and their role in mucosal homeostasis or disease.

Candida Interactions with the Oral Bacterial Microbiota

The human oral cavity is normally colonized by a wide range of microorganisms, including bacteria, fungi, Archaea, viruses, and protozoa. Within the different oral microenvironments these organisms are often found as part of highly organized microbial communities termed biofilms, which display consortial behavior. Formation and maintenance of these biofilms are highly dependent on the direct interactions between the different members of the microbiota, as well as on the released factors that influence the surrounding microbial populations. These complex biofilm dynamics influence oral health and disease. In the latest years there has been an increased recognition of the important role that interkingdom interactions, in particular those between fungi and bacteria, play within the oral cavity. Candida spp., and in particular C. albicans, are among the most important fungi colonizing the oral cavity of humans and have been found to participate in these complex microbial oral biofilms. C. albicans has been reported to interact with individual members of the oral bacterial microbiota, leading to either synergistic or antagonistic relationships. In this review we describe some of the better characterized interactions between Candida spp. and oral bacteria.

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.

Challenges in the local delivery of peptides and proteins for oral mucositis management

Oral mucositis, a common inflammatory side effect of oncological treatments, is a disorder of the oral mucosa that can cause painful ulcerations, local motor disabilities, and an increased risk of infections. Due to the discomfort it produces and the associated health risks, it can lead to cancer treatment restrains, such as the need for dose reduction, cycle delays or abandonment. Current mucositis management has low efficiency in prevention and treatment. A topical drug application for a local action can be a more effective approach than systemic routes when addressing oral cavity pathologies. Local delivery of growth factors, antibodies, and anti-inflammatory cytokines have shown promising results. However, due to the peptide and protein nature of these novel agents, and the several anatomic, physiological and environmental challenges of the oral cavity, their local action might be limited when using traditional delivering systems. This review is an awareness of the issues and strategies in the local delivery of macromolecules for the management of oral mucositis.

Phase II investigational oral drugs for the treatment of radio/chemotherapy induced oral mucositis

INTRODUCTION

Oral mucositis is a significant unmet clinical need for many cancer patients. The biological complexity of mucositis' pathogenesis provides a number of mechanistic targets suitable as pharmacologic targets. The diversity of targets has stimulated drug development in search of an effective intervention. In this paper, we review a range of agents that are currently being evaluated.

AREAS COVERED

Drugs for management of oral mucositis vary in formulation, route of administration and biological target. Most propose to interrupt the initiation of injury by suppressing activation of the innate immune response or countering oxidative stress, or minimizing downstream inflammatory responses. Overwhelmingly, the population most studied is patients being treated with concomitant chemoradiation for cancers of the head and neck as this is the cohort that most consistently suffers severe mucositis for long periods of time. The Phase 2 pipeline is robust. Preliminary data reported for a number of agents is optimistic. Genomics may be important in interpreting and comparing responses to agents across widely demographically diverse populations.

EXPERT OPINION

Oral mucositis remains a significant toxicity for patients undergoing cancer treatment. Incremental reports of successes have been noted for a number of targeted agents.