Corticosteroid delivery using oral mucosa equivalents for the treatment of inflammatory mucosal diseases

What can we learn from treatments of oral lichen planus?

Oral lichen planus (OLP), a T-lymphocyte-mediated disease of the oral mucosa, has a complex pathogenesis that involves a number of factors. The disease is characterized by recurrent episodes and requires continuous follow up, and there is no curative treatment available. Erosive lichen planus, among others, has a risk of malignant transformation and requires standardized treatment to control its progression. Different clinical subtypes of oral lichen planus require appropriate treatment. Pharmacological treatments are the most widely available and have the greatest variety of options and a number of novel pharmacological treatments are presented as highlights, including JAK enzyme inhibitors. The second is photodynamic therapy, which is the leading physiological treatment. In addition, periodontal treatment and psychological treatment should not be neglected. In this review, we briefly discuss the most recent developments in therapies for oral lichen planus after summarizing the most widely used clinical treatments, aiming to provide different proposals for future clinical treatment.

Evaluation of therapeutic effects of nanofibrous mat containing mycophenolate mofetil on oral lichen planus: In vitro and clinical trial study

Objectives

Recently, topical drug delivery system has gained increasing interest in the treatment of oral lesions. Lichen planus is a chronic inflammatory disease affecting mucous membranes and skin. The current study aimed to fabricate a drug delivery system containing mycophenolate mofetil for the treatment of oral lichen planus lesions.

Methods

Firstly, a nanofibrous mat containing mycophenolate mofetil, zinc oxide nanoparticles, and aloe vera was designed and fabricated. The antimicrobial, cytocompatibility, anti-inflammatory, and antioxidative characteristics of fabricated scaffolds were evaluated. Then, this nanofibrous mat was applied to 12 patients suffering from bilateral erythematous/erosive Oral Lichen planus (OLP) lesions for 2 weeks. The treatment outcomes, including oral symptoms and lesion size, were compared with the routine topical treatment of these lesions; Triamcinolone ointment.

Results

The characterization of nanofibrous mat approved the successful fabrication of scaffolds. The fabricated nanofibers showed notable antimicrobial activity. The amounts of TNF 𝛼, IL6, and reactive oxygen species (ROS) of stimulated human gingival fibroblasts were decreased after exposure to NFs/Myco/Alv/ZnO scaffolds. The clinical trial results demonstrated the same therapeutic effects compared to the commercial ointment, while the symptoms of patients were significantly improved in the mats group.Significance. Considering the successful results of this study, the application of nanofibrous mat can be a promising product for improving treatment outcomes of OLP.

3D printed mucoadhesive orodispersible films manufactured by direct powder extrusion for personalized clobetasol propionate based paediatric therapies

The aim of this work is the development and production by Direct Powder Extrusion (DPE) 3D printing technique of novel oral mucoadhesive films delivering Clobetasol propionate (CBS), useful in paediatric treatment of Oral Lichen Planus (OLP), a rare chronic disease. The DPE 3D printing of these dosage forms can allow the reduction of frequency regimen, the therapy personalization, and reduction of oral cavity administration discomfort. To obtain suitable mucoadhesive films, different polymeric materials, namely hydroxypropylmethylcellulose or polyethylene oxide blended with chitosan (CS), were tested and hydroxypropyl-β-cyclodextrin was added to increase the CBS solubility. The formulations were tested in terms of mechanical, physico-chemical, and in vitro biopharmaceutical properties. The film showed a tenacious structure, with drug chemical-physical characteristics enhancement due to its partial amorphization during the printing stage and owing to cyclodextrins multicomponent complex formation. The presence of CS enhanced the mucoadhesive properties leading to a significant increase of drug exposure time on the mucosa. Finally, the printed films permeation and retention studies through porcine mucosae showed a marked retention of the drug inside the epithelium, avoiding drug systemic absorption. Therefore, DPE-printed films could represent a suitable technique for the preparation of mucoadhesive film potentially usable for paediatric therapy including OLP.

Oral Mucosa Models to Evaluate Drug Permeability

Due to its numerous advantages, such as excellent drug accessibility, rapid absorption, and bypass of first-pass metabolism, the route of drug administration that involves crossing the oral mucosa is highly favored. As a result, there is significant interest in investigating the permeability of drugs through this region. The purpose of this review is to describe the various ex vivo and in vitro models used to study the permeability of conveyed and non-conveyed drugs through the oral mucosa, with a focus on the most effective models. Currently, there is a growing need for standardized models of this mucosa that can be used for developing new drug delivery systems. Oral Mucosa Equivalents (OMEs) may provide a promising future perspective as they are capable of overcoming limitations present in many existing models.

Polymeric Micelles Enhance Mucosal Contact Time and Deposition of Fluocinolone Acetonide

This study used polymeric micelles to improve quality by increasing drug solubility, extending mucosal drug retention time, enhancing mucoadhesiveness, and promoting drug permeation and deposition. Fluocinolone acetonide (FA) was loaded into polymeric micelles (FPM), which were composed of poloxamer 407 (P407), sodium polyacrylate (SPA), and polyethylene glycol 400, and their physicochemical properties were examined. Small-angle X-ray scattering (SAXS) revealed a hexagonal micellar structure at all temperatures, and the concentrations of P407 and SPA were shown to significantly affect the solubility, mucoadhesion, release, and permeation of FPMs. The proportion of P407 to PEG at a ratio of 7.5:15 with or without 0.1% w/v of SPA provided suitable FPM formulations. Moreover, the characteristics of FPMs revealed crystalline states inside the micelles, which was consistent with the morphology and nano-hexagonal structure. The results of ex vivo experiments using focal plane array (FPA)-based Fourier transform infrared (FTIR) imaging showed that the FPM with SPA penetrated quickly through the epithelium, lamina propria, and submucosa, and remained in all layers from 5-30 min following administration. In contrast, the FPM without SPA penetrated and passed through all layers. The FPM with extended mucoadhesion, improved drug-mucosal retention time, and increased FA permeation and deposition were successfully developed, and could be a promising innovation for increasing the efficiency of mouth rinses, as well as other topical pharmaceutical and dental applications.

Immune mechanisms in oral lichen planus

Oral lichen planus (OLP) is a T-cell-mediated inflammatory disease of the oral mucosa that has been extensively researched over many years but as yet the mechanisms of pathogenesis are still not fully understood. Whilst the specific etiologic factors driving OLP remain ambiguous, evidence points to the development of a chronic, dysregulated immune response to OLP-mediating antigens presented by innate immune cells and oral keratinocytes leading to increased cytokine, chemokine and adhesion molecule expression. These molecules recruit T-cells and mast cells to the diseased site and orchestrate a complex interplay between cells that culminates in keratinocyte cell death, mucosal basement membrane destruction and long-term chronicity of the disease. The main lymphocytes involved are thought to be CD8+ cytotoxic and CD4+ Th1 polarised T-cells although recent evidence indicates the involvement of other Th subsets such as Th9, Th17 and Tregs, suggesting that a more complex immune cell relationship exists during the disease process. This review provides an overview of the immune mechanisms at play in OLP pathogenesis with particular emphasis on the role of the different Th subsets and how these recent discoveries may guide research toward identifying potential therapeutic targets.

Immunoresponsive Tissue-Engineered Oral Mucosal Equivalents Containing Macrophages

Macrophages play a key role in orchestrating the host immune response toward invading organisms or non-self molecules in the oral mucosa. Three-dimensional (3D) oral mucosal equivalents (OME) containing oral fibroblasts and keratinocytes are used extensively to mimic the human oral mucosa where they have been employed to examine innate immune responses to both bacterial and fungal pathogens as well as to biomaterials. Although the presence of immune cells is critical in generating an immune response, very few studies have incorporated leukocytes into OME, and to date, none have contained primary human macrophages. In this study, we report the generation of an immunocompetent OME to investigate immune responses toward bacterial challenge. Primary human monocyte-derived macrophages (MDM) were as responsive to bacterial lipopolysaccharide (LPS) challenge when cultured within a 3D hydrogel in terms of proinflammatory cytokine (IL-6, CXCL8, and TNF-α) gene expression and protein secretion compared with culture as two-dimensional monolayers. MDM were incorporated into a type 1 collagen hydrogel along with oral fibroblasts and the apical surface seeded with oral keratinocytes to generate an MDM-containing OME. Full-thickness MDM-OME displayed a stratified squamous epithelium and a fibroblast-populated connective tissue containing CD68-positive MDM that could be readily isolated to a single-cell population for further analysis by collagenase treatment followed by flow cytometry. When stimulated with LPS, MDM-OME responded with increased proinflammatory cytokine secretion, most notably for TNF-α that increased 12-fold when compared with OME alone. Moreover, this proinflammatory response was inhibited by pretreatment with dexamethasone, showing that MDM-OME are also amenable to drug treatment. Dual-labeled immunofluorescence confocal microscopy revealed that MDM were the sole source of TNF-α production within MDM-OME. These data show functional activity of MDM-OME and illustrate their usefulness for investigations aimed at monitoring the immune response of the oral mucosa to pathogens, biomaterials, and for tissue toxicity and anti-inflammatory drug delivery studies.