In-vitro analysis on the potential use of dental pulp mesenchymal stem cells on arecoline-induced oral epithelial cells.

To assess the protective role of the secretome of dental pulp mesenchymal stem cells on arecoline-induced epithelial-mesenchymal transition and senescence on epithelial cells of the oral mucosa. Effect of varying concentrations of arecoline extract and dental pulp mesenchymal stem cell condition media (DPSC-CM) were noted on oral mucosal epithelial cells. MTT assay, Annexin V-FITC/PI assay, and the quantitative gene expressions of BCL2, PUMA, BAD, BAX, CASP3, CASP9, CASP12, TGFB1, CST3, COL1A2, COL3A1, TIMP1, TIMP2, CDH1, and CDH2 were assessed. Oral mucosal epithelial cells exposed only to the arecoline were the control. 50% and 100% DPSC-CM decreased apoptosis-related gene expression in the cells exposed with 25 µM arecoline compared to the control. 50% DPSC-CM attenuated the expression of all fibrotic genes and EMT-related genes. 20% and 100% DPSC-CM showed differential effects on fibrotic and EMT-related genes. DPSC-CM inhibited apoptosis, and attenuated expression of fibrotic and EMT-related genes on arecoline treated human oral epithelial cells.

Reveals of quercetin's therapeutic effects on oral lichen planus based on network pharmacology approach and experimental validation.

Oral lichen planus (OLP) is a localized autoimmune disease of the oral mucosa, with an incidence of up to 2%. Although corticosteroids are the first-line treatment, they cause several adverse effects. Quercetin, a naturally occurring compound, has fewer side-effects and provides long-term benefits. Besides, it has powerful anti­inflammatory activities. Here, we combined network pharmacology with experimental verification to predict and verify the key targets of quercetin against OLP. First, 66 quercetin-OLP common targets were analyzed from various databases. The protein-protein interaction (PPI) network was constructed. Topology analysis and MCODE cluster analysis of common targets were conducted to identify 12 key targets including TP53, IL-6 and IFN-γ and their connections. Gene functions and key signaling pathways, including reactive oxygen species metabolism, IL-17 pathway and AGE-RAGE pathway, were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Then, in vitro experiments showed that quercetin interfered with Th1/Th2 balance by acting on IL-6 and IFN-γ to modulate the immune system in treating OLP. Quercetin considerably affected the apoptosis and migration of T lymphocytes in OLP patients. Our study reveals the potential therapeutic targets and signaling pathways of quercetin associated with OLP, and establishes the groundwork for future clinical applications.

Effects of an oral mucosa protective formulation on chemotherapy- and/or radiotherapy-induced oral mucositis: a prospective study.

BACKGROUND: Oral mucositis (OM) associated with cancer treatment not only impairs patients' quality of life but also causes treatment delays or changes. This prospective exploratory study was conducted to evaluate the efficacy of Episil® oral liquid, which is an approved protective formulation for the oral mucosa in patients with OM. The extent of the pain-relieving effect, feeling during use, and adverse events or problems were evaluated. METHODS: In total, 10 Japanese cancer patients with OM receiving chemotherapy, pretreatment therapy for hematopoietic stem cell transplantation, or radiation therapy for head and neck cancer were enrolled. RESULTS: A numerical rating scale (NRS) was used to assess oral pain intensity due to OM. Compared to baseline, the mean NRS began to decrease at 5 min after using Episil® (7.1 ± 1.4 to 4.6 ± 2.87; p = 0.264). A significant decrease was observed in the pain score after using Episil® compared with that before using Episil®, and this effect lasted up to 120 min. The protective effects of Episil® were observed 3-5 min after application. Some patients felt slight soreness or discomfort when applying Episil®. However, this discomfort due to Episil®'s stimulation was within the allowable range and transient. No adverse events were observed in any of the cases. CONCLUSIONS: The results of this prospective study showed that Episil® could be an effective treatment to relieve oral pain in Japanese patients with moderate to severe OM, and this newly approved product might adequately support patients' oral intake. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) ( UMIN000031921 ).

Reduction of oxidative stress blunts the NLRP3 inflammatory cascade in LPS stimulated human gingival fibroblasts and oral mucosal epithelial cells.

The therapeutic armamentarium for the treatment of oral mucositis is very poor. Catechin and baicalin are two natural flavonoids that have been individually reported to have a curative potential. Flavocoxid is a mixed extract containing baicalin and catechin showing antioxidant effects and anti-inflammatory activity mainly due to a dual inhibition of inducible cyclooxygenase (COX-2), 5-lipoxygenase (5-LOX) and NLRP3 pathway. The aim of this study was to evaluate the anti-inflammatory and anti-oxidant effects of flavocoxid in an "in vitro" model of oral mucositis induced by triggering an inflammatory phenotype in human gingival fibroblasts (GF) and human oral mucosal epithelial cells (EC). GF and EC were challenged with lipopolysaccharide (LPS 2 µg/ml) alone or in combination with flavocoxid (32 µg/ml). Flavocoxid increased Nrf2, prompted a marked reduction in malondialdehyde levels and reduced the expression of COX-2 and 5-LOX together with PGE2, and LTB4 levels. Flavocoxid caused also a great decrease in the expression of NF-κB and turned off NLRP3 inflammasome and its downstream effectors signal, as caspase-1, IL-1ß and IL-18 in both GF and EC cells stimulated with LPS. These results suggest a correlation between oxidative stress and NLRP3 activation and indicate that flavocoxid suppresses the inflammatory storm that accompanies oral mucositis. This preclinical evidence deserves to be confirmed in a clinical setting.

Modulation of the oral glucocorticoid system during black raspberry mediated oral cancer chemoprevention.

Recent reports suggest that glucocorticoids (GCs), which can be synthesized in the oral mucosa, play an important role in cancer development. Therefore, the objectives of this study were to characterize the role of the oral GC system in oral cancer, and determine the effect of black raspberry (BRB) administration on GC modulation during oral cancer chemoprevention. We determined the expression of GC enzymes in various oral cancer cell lines, and investigated the role of the GC inactivating enzyme HSD11B2 on CAL27 oral cancer cells using siRNA mediated knockdown approaches. Using two in vivo models of oral carcinogenesis with 4-nitroquinoline 1-oxide carcinogen on C57Bl/6 mice and F344 rats, we determined the effect of BRB on GC modulation during head and neck squamous cell carcinoma chemoprevention. Our results demonstrate that HSD11B2, which inactivates cortisol to cortisone, is downregulated during oral carcinogenesis in clinical and experimental models. Knockdown of HSD11B2 in oral cancer cells promotes cellular proliferation, invasion and expression of angiogenic biomarkers EGFR and VEGFA. An ethanol extract of BRB increased HSD11B2 expression on oral cancer cells. Dietary administration of 5% BRB increased Hsd11b2 gene and protein expression and reduced the active GC, corticosterone, in cancer-induced mouse tongues. Our results demonstrate that the oral GC system is modulated during oral carcinogenesis, and BRB administration upregulates Hsd11b2 during oral cancer chemoprevention. In conclusion, our findings challenge the use of synthetic GCs in head and neck cancer, and support the use of natural product alternatives that potentially modulate GC metabolism in a manner that supports oral cancer chemoprevention.

Formulation and characterization of hydroxyethyl cellulose-based gel containing metronidazole-loaded solid lipid nanoparticles for buccal mucosal drug delivery.

Local delivery of drug is a promising strategy to manage periodontitis characterized by chronic inflammation of the soft tissue surrounding the teeth. An optimized system should prolong the drug retention time and exhibit controlled drug permeation through the buccal mucosal layer. This study was aimed to develop hydroxyethyl cellulose (HEC)-based gel containing metronidazole (MTZ) loaded in solid lipid nanoparticles (SLNs), and to enhance the antimicrobial activity of MTZ. SLNs were prepared using a combination method of solvent evaporation and hot homogenization. The results showed that the fabricated SLNs, comprising of Precirol (2.93%, w/v), Tween 80 (1.8%, w/v), and the drug:lipid ratio of 19.3% (w/w), were approximately 200 nm in size, with a narrow distribution. The HEC (3%, w/w)-based gel formed a smooth, homogeneous structure and had preferable mechanical and rheological properties. Moreover, the MTZ-loaded SLNs-based HEC gel (equivalent to 1% of MTZ, w/w) exhibited a sustained in vitro drug release pattern, optimal ex vivo permeability, and enhanced in vitro antimicrobial activity after 24 h of treatment. These findings indicate the potential of the MTZ-loaded SLNs-based HEC formulation for local drug delivery at the buccal mucosa in managing periodontal disease.

The broadening scope of oral mucositis and oral ulcerative mucosal toxicities of anticancer therapies.

Oral mucositis (OM) is a common, highly symptomatic complication of cancer therapy that affects patients' function, quality of life, and ability to tolerate treatment. In certain patients with cancer, OM is associated with increased mortality. Research on the management of OM is ongoing. Oral mucosal toxicities are also reported in targeted and immune checkpoint inhibitor therapies. The objective of this article is to present current knowledge about the epidemiology, pathogenesis, assessment, risk prediction, and current and developing intervention strategies for OM and other ulcerative mucosal toxicities caused by both conventional and evolving forms of cancer therapy.

Safety and efficacy of Oro-T oral rinse in oral mucositis during cancer radiotherapy and/or chemotherapy: Cumulative analysis of two studies.

INTRODUCTION: Oral mucositis is inflammation of the mucosa of the mouth which ranges from redness to severe ulceration. It results from the local effects of radiation to the oral mucosa. OBJECTIVES: The study is cumulative analysis of two studies (one comparative and the other open labeled) evaluated in individuals with oral mucositis during cancer radiotherapy and/or chemotherapy for the safety and efficacy of Oro-T mouthwash in a comparative design with normal saline. METHODOLOGY: Both the studies were similar with respect to clinical and laboratory parameters for analysis. The participants were advised to use 10 ml of Oro-T for 1 min 4 times daily for 6 weeks starting from day 1 of standard care. Patients were followed up, and the results were assessed from baseline on visit days: At entry and at the end of every week for 6 weeks. Clinical assessment of oral condition was done objectively (by the investigator) and also subjectively. Clinical symptoms such as sore throat, number of ulcer, burning sensation, pain, difficulty in chewing, difficulty in drinking, and mucositis grading along with Patient Reported Outcome Measures Scale were evaluated at each interval. Data was available for 40 subjects in Oro-T and 15 subjects in NS groups respectively. RESULTS AND CONCLUSION: The significant positive outcome was reported both subjectively and objectively in Oro-T group as compared to NS group with the delay in the onset of symptoms and less severe manifestation of oral mucositis with an improvement in quality of life. No adverse effects were reported that prompted discontinuation of study medication. Overall compliance to study medication was good.

Prevention of the proliferation of oral pathogens due to prolonged mask use based on α-cyclodextrin and hydroxytyrosol mouthwash.

OBJECTIVE: Face masks help contain the aerosol-mediated transmission of infectious viral particles released from individuals via cough and sneezes. However, the prolonged use of face masks has raised concerns regarding oral hygiene. Here, we present a mouthwash formulation based on α-cyclodextrin and hydroxytyrosol that can maintain healthy oral microbiota. MATERIALS AND METHODS: We isolated and cultured Candida albicans, Staphylococcus aureus, and a mix of Streptococcus sp., Staphylococcus sp. and Neisseria sp. from oral and throat swabs. The microorganisms were cultured in a standard medium with or without the mouthwash. To evaluate the effect of the mouthwash on the oral microbiota, the DNA from the saliva of 3 volunteers that used the mouthwash was extracted. Then, the DNA was amplified using primer pairs specific for bacterial and fungal DNA. Twelve further volunteers were offered to use the mouthwash and a questionnaire was submitted to them to assess the possible beneficial effects of mouthwash on halitosis and other oral disturbances. RESULTS: The bacteria and fungi cultured in media containing the mouthwash showed a growth reduction ranging from 20 to 80%. The PCR amplification of fungal and bacterial DNA extracted from volunteers that used the mouthwash showed a reduction of both bacteria and fungi. Volunteers that used the mouthwash reported a tendency towards a reduction of halitosis, gingival and mouth inflammation, and dry mouth. CONCLUSIONS: The use of a mouthwash containing α-cyclodextrin and hydroxytyrosol is not aggressive against oral mucosa; it is safe and effective to reduce the bacterial and fungal load due to the continuous use of face masks.

Development and Evaluation of Thermosensitive Hydrogels with Binary Mixture of Scutellariae baicalensis radix Extract and Chitosan for Periodontal Diseases Treatment.

Scutellaria baicalensis root displays anti-inflammatory and antibacterial properties due to the presence of flavonoids, particularly baicalin, baicalein, and wogonin. Our work aimed at developing thermosensitive hydrogels containing a binary mixture of S. baicalensis radix lyophilized extract and chitosan as a novel approach for periodontal diseases treatment. Two types of chitosan were employed in preliminary studies on binary mixtures with S. baicalensis radix lyophilized extract standardized for baicalin, baicalein, and wogonin. Thermosensitive hydrogels were prepared of poloxamer 407, alginate sodium, and cellulose derivatives and evaluated in terms of rheological and mucoadhesive behavior. The presence of chitosan altered the release profile of active compounds but did not affect their in vitro permeation behavior in PAMPA assay. The synergistic effects of S. baicalensis radix lyophilized extract and chitosan toward ferrous ion-chelating activity, inhibition of hyaluronidase, and pathogen growth were observed. The thermosensitive gelling system showed shear-thinning properties, gelation temperature between 25 and 27 °C, and favorable mucoadhesiveness in contact with porcine buccal mucosa, which was enhanced in the presence of binary mixture of S. baicalensis radix extract and chitosan. The release tests showed that baicalin and baicalein were liberated in a prolonged manner with a fast onset from hydrogel formulations.

Analgesic Mechanisms of Steroid Ointment against Oral Ulcerative Mucositis in a Rat Model.

Despite the long history of use of steroid ointments for oral mucositis, the analgesic mechanism has not been fully elucidated. In this study, we examined the effects of triamcinolone acetonide (Tmc) on oral ulcerative mucositis-induced pain in conscious rats by our proprietary assay system. Based on evaluations of the physical properties and retention periods in the oral mucosa of human volunteers and rats, we selected TRAFUL® ointment as a long-lasting base. In oral ulcerative mucositis model rats, TRAFUL® with Tmc suppressed cyclooxygenase-dependent inflammatory responses with upregulations of glucocorticoid receptor-induced anti-inflammatory genes and inhibited spontaneous nociceptive behavior. When an ointment with a shorter residual period was used, the effects of Tmc were not elicited or were induced to a lesser extent. Importantly, TRAFUL® with Tmc also improved oral ulcerative mucositis-induced mechanical allodynia, which has been reported to be independent of cyclooxygenase. Ca2+ imaging in dissociated trigeminal ganglion neurons showed that long-term preincubation with Tmc inhibited the hypertonic stimulation-induced Ca2+ response. These results suggest that the representative steroid Tmc suppresses oral ulcerative mucositis-induced pain by general anti-inflammatory actions and inhibits mechanical sensitivity in peripheral nerves. For drug delivery, long-lasting ointments such as TRAFUL® are needed to sufficiently induce the therapeutic effects.

Study of the Possible Alleviated Role of Atorvastatin on Irinotecan-Induced Lingual Mucosal Damage: Histological and Molecular Study.

BACKGROUND: Oral mucositis is the most debilitating and troublesome adverse effect of irinotecan (CPT-11) treatment. It adversely affects the patient quality of life. The aim of this work was to study the histological, immunohistochemical, and molecular changes in the oral mucosa by CPT-11 and the possible alleviated role of atorvastatin. METHODS: Rats were randomly divided into control, CPT-11-treated group, and CPT-11+ atorvastatin-treated group. At the end of the experiment, the anterior two-thirds of the tongue was dissected out and divided into two parts: one part for light microscopic examination and the second for molecular study. RESULTS: CPT-11-treated group revealed loss of normal mucosal organization, areas of ulceration and inflammation, and loss of architecture of lingual papillae. A significant decrease in immunohistochemical and molecular gene expression of Ki-67 and antiapoptotic Bcl-2 levels was observed. A significant increase in NF-κB immunohistochemical and mRNA gene expression level and a nonsignificant increase in Nrf2 gene expression were detected. Coadministration of atorvastatin showed remarkable improvement in the histopathological picture with a significant increase in Ki-67 and Bcl-2, a significant decrease in NF-κB protein and gene expression, and a significant increase in Nrf2 gene expression. CONCLUSION: Atorvastatin substantially attenuates CPT-11-induced oral mucositis through the initiation of the antiapoptotic gene, modulation of the inflammatory, and antioxidant gene expression.

Protocol for analyzing and visualizing antiviral immune responses after acute infection of the murine oral mucosa.

The oral mucosa is an important site for virus infection and transmission, yet few animal models exist to examine the virology, pathology, and immunology of acute oral mucosal viral infection. Here, we provide a protocol for infecting and imaging the inner lip (labial mucosa) of mice with the poxvirus vaccinia virus (VACV). Inoculation of the labial mucosa with a bifurcated needle results in viral replication and priming of an adaptive antiviral response that can be imaged using intravital microscopy. For complete details on the use and execution of this protocol, please refer to Shannon et al. (2021).

Electron Spin Resonance Evaluation of Buccal Membrane Fluidity Alterations by Sodium Caprylate and L-Menthol.

The ability of sodium caprylate and l-menthol to fluidize phospholipid bilayers composed of lipids simulating the buccal epithelium was investigated using electron spin resonance (ESR) to evaluate the action of these agents as permeation enhancers. 5-Doxyl stearic acid (5-DSA) and 16-doxyl stearic acid (16-DSA) were used as spin labels to identify alterations in membrane fluidity near the polar head groups or inner acyl regions of the lipid bilayer, respectively. The molecular motion of both 5-DSA and 16-DSA showed increased disorder near the polar and inner hydrophobic regions of the bilayer in the presence of sodium caprylate suggesting fluidization in both the regions, which contributes to its permeation enhancing effects. L-menthol decreased the order parameter for 16-DSA, showing membrane fluidization only in the inner acyl regions of the bilayer, which also corresponded to its weaker permeation enhancing effects. The rapid evaluation of changes in fluidity of the bilayer in the presence of potential permeation enhancers using ESR enables improved selection of effective permeation enhancers and enhancer combinations based on their effect on membrane fluidization.

Repeated exposure of the oral mucosa over 12 months with cold plasma is not carcinogenic in mice.

Peri-implantitis may result in the loss of dental implants. Cold atmospheric pressure plasma (CAP) was suggested to promote re-osseointegration, decrease antimicrobial burden, and support wound healing. However, the long-term risk assessment of CAP treatment in the oral cavity has not been addressed. Treatment with two different CAP devices was compared against UV radiation, carcinogen administration, and untreated conditions over 12 months. Histological analysis of 406 animals revealed that repeated CAP exposure did not foster non-invasive lesions or squamous cell carcinoma (SCCs). Carcinogen administration promoted non-invasive lesions and SCCs. Molecular analysis by a qPCR screening of 144 transcripts revealed distinct inflammatory profiles associated with each treatment regimen. Interestingly, CAP treatment of carcinogen-challenged mucosa did not promote but instead left unchanged or reduced the proportion of non-invasive lesions and SCC formation. In conclusion, repeated CAP exposure of murine oral mucosa was well tolerated, and carcinogenic effects did not occur, motivating CAP applications in patients for dental and implant treatments in the future.

Does Panoramic X-ray Induce Cytogenetic Damage to Oral Cells? A Systematic Review With Meta-analysis.

AIM: The aim of this review was to evaluate the scientific literature regarding the cytogenetic damage in oral exfoliated cells of adult patients submitted to panoramic X-ray. MATERIALS AND METHODS: An extensive search of the literature was conducted on PubMed, Scopus and Web of Science databases for all studies published until April 2021 using combinations of the following keywords: "panoramic X-ray," "DNA damage," "genetic damage", "genotoxicity", "mutagenicity", cytotoxicity", "buccal cells", "oral mucosa", "tongue", "gingiva", "micronucleus assay", according to the PRISMA guidelines. All clinical studies in English language were included in the study. A total of 10 studies were identified. RESULTS: As expected, the results regarding the cytogenetic damage induced by panoramic X-ray are conflicting. Some authors have demonstrated that panoramic X-ray induces mutagenesis in oral cells, whereas others did not. After reviewing the 10 studies, two were classified as strong, four were considered moderate, and four were considered weak, according to the quality assessment components of the Effective Public Health Practice Project (EPHPP). Meta-analysis data revealed a negative response related to mutagenicity in oral cells by panoramic X-ray. CONCLUSION: Taken together, this review failed to demonstrate the association between micronucleus frequency and panoramic X-ray.

Fat mass and obesity-associated protein regulates tumorigenesis of arecoline-promoted human oral carcinoma.

Arecoline, a major alkaloid within areca nut extract, is recognized as the primary active carcinogen promoting oral squamous cell carcinoma (OSCC) pathological development. Dysregulation of N6-methyladenosine (m6A) methyltransferase components (e.g., Fat mass and obesity-associated protein [FTO] and methyltransferase-like 3 [METTL3]) are closely associated with multiple cancer progression, including oral cancer. However, the biological function role of FTO in arecoline-induced oral cancer is largely unknown. We identified that FTO was significantly upregulated in OSCC tissues from patients with areca nut chewing habits and chronic arecoline-treated OSCC cell lines. Depletion of FTO attenuated the arecoline-promoted stemness, chemoresistance, and oncogenicity of OSCC cells. Finally, we revealed that FTO was negatively regulated by a transcription factor forkhead box protein A2 (FOXA2) in OSCC cells. This study, for the first time, demonstrated that FTO plays an oncogenic role in arecoline-induced OSCC progression. Thus, developing new therapeutic agents targeting FTO may serve as a promising method to treatment OSCC patients, especially those with areca nut chewing habits.

Quercetin protects oral mucosal keratinocytes against lipopolysaccharide-induced inflammatory toxicity by suppressing the AKT/AMPK/mTOR pathway.

BACKGROUND: Cytokines can induce a chronic inflammatory response in the periodontium, leading to periodontitis. Quercetin, a naturally occuring flavonoid, has been shown to inhibit periodontitis, but how it works is poorly understood. In this study, we assessed the impact of quercetin on lipopolysaccharide (LPS)-induced inflammatory damage in oral mucosal keratinocytes (hOMK107) and explored its underlying mechanism. METHODS: The viability and apoptosis of hOMK107 cells were measured after exposure to LPS, followed or not by quercetin. The production of IL-1ß, IL-6, IL-8, TNF-ɑ, iNOS, and COX-2 was quantified by enzyme-linked immunosorbent assay (ELISA), while levels of Akt, AMPK, and mTOR and their phosphorylation were detected semi-quantitatively by western blotting. RESULTS: Quercetin significantly improved cell viability and apoptosis by reversing LPS-induced upregulation of Bax and downregulation of Bcl-2 in hOMK107 cells. Quercetin decreased the production of IL-1ß, IL-6, IL-8, TNF-ɑ, iNOS, and COX-2, as well as signal transduction via the Akt/AMPK/mTOR pathway. Inhibitors of Akt, AMPK, and mTOR strengthened the anti-apoptotic effects of quercetin, while agonists of Akt, AMPK, or mTOR or Akt overexpression weakened the anti-apoptotic effects. CONCLUSION: These results indicate that quercetin may have a potential protective effect against the chronic inflammation-related periodontitis via suppressing Akt/AMPK/mTOR pathway.

Facilitated Buccal Insulin Delivery via Hydrophobic Ion-Pairing Approach: In vitro and ex vivo Evaluation.

BACKGROUND: The clinical use of therapeutic peptides has been limited because of their inefficient delivery approaches and, therefore, inadequate delivery to target sites. Buccal administration of therapeutic peptides offers patients a potential alternative to the current invasive routes of administration. PURPOSE: The aim of the study was to fabricate hydrophobic ion-pairing (HIP)-nanocomplexes (C1 and C2) utilizing anionic bile salts and cationic peptides, and to assess their permeability across TR146 buccal cell layers and porcine buccal tissue. METHODS: C1 and C2-nanocomplexes were fabricated using the HIP approach. In addition, their physiochemical and morphological attributes, in vitro and ex vivo permeability properties, and qualitative and quantitative cellular uptake were evaluated and compared. The localization of C1 and C2-nanocomplexes in porcine buccal tissue was determined using confocal laser scanning microscopy. RESULTS: The C1-nanocomplex was the superior nanocarrier and significantly enhanced the transport of insulin across TR146 cell layers and porcine buccal tissue, exhibiting a 3.00- and 51.76-fold increase in permeability coefficient, respectively, when compared with insulin solution (p < 0.01). C1-nanocomplex was more efficient than C2-nanocomplex at facilitating insulin permeability, with a 2.18- and 27.64-fold increase across TR146 cell layers and porcine buccal tissue, respectively. The C1-nanocomplex demonstrated immense uptake and localization of insulin in TR146 cells and porcine buccal tissue, as evidenced by a highly intense fluorescence in TR146 cells, and a great shift of fluorescence intensity towards the inner region of buccal tissue over time. The increase in fluorescence intensity was observed in the order of C1 > C2 > insulin solution. CONCLUSION: In this study, we highlighted the efficacy of potential nanocarriers in addressing the daunting issues associated with the invasive administration of insulin and indicated a promising strategy for the buccal administration and delivery of this life-saving peptide hormone.

Inhibition of mTOR signaling and clinical activity of metformin in oral premalignant lesions.

BACKGROUNDThe aberrant activation of the PI3K/mTOR signaling circuitry is one of the most frequently dysregulated signaling events in head and neck squamous cell carcinoma (HNSCC). Here, we conducted a single-arm, open-label phase IIa clinical trial in individuals with oral premalignant lesions (OPLs) to explore the potential of metformin to target PI3K/mTOR signaling for HNSCC prevention.METHODSIndividuals with OPLs, but who were otherwise healthy and without diabetes, underwent pretreatment and posttreatment clinical exam and biopsy. Participants received metformin for 12 weeks (week 1, 500 mg; week 2, 1000 mg; weeks 3-12, 2000 mg daily). Pretreatment and posttreatment biopsies, saliva, and blood were obtained for biomarker analysis, including IHC assessment of mTOR signaling and exome sequencing.RESULTSTwenty-three participants were evaluable for response. The clinical response rate (defined as a ≥50% reduction in lesion size) was 17%. Although lower than the proposed threshold for favorable clinical response, the histological response rate (improvement in histological grade) was 60%, including 17% complete responses and 43% partial responses. Logistic regression analysis revealed that when compared with never smokers, current and former smokers had statistically significantly increased histological responses (P = 0.016). Remarkably, a significant correlation existed between decreased mTOR activity (pS6 IHC staining) in the basal epithelial layers of OPLs and the histological (P = 0.04) and clinical (P = 0.01) responses.CONCLUSIONTo our knowledge this is the first phase II trial of metformin in individuals with OPLs, providing evidence that metformin administration results in encouraging histological responses and mTOR pathway modulation, thus supporting its further investigation as a chemopreventive agent.TRIAL REGISTRATIONNCT02581137FUNDINGNIH contract HHSN261201200031I, grants R01DE026644 and R01DE026870.