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

Oral lichen planus (OLP) is an immune-mediated disease of the oral mucosa with idiopathic aetiology. It is frequently treated with topical corticosteroids (applied as gels, mouthwashes, or sprays); however, the mucosal exposure times of topical corticosteroids are short because of removal by the constant flow of saliva and mechanical forces. In this study we used cell monolayers, as well as oral mucosal equivalents (OMEs) containing activated T-cells, to examine corticosteroid potency and delivery of clobetasol-17-propionate from a novel electrospun mucoadhesive patch. The OMEs displayed tight junctions, desmosomes, hemidesmosomes, and an efficient permeability barrier. Following application of corticosteroids to cells cultured as monolayers, the degree of cytotoxicity measured correlated to the level of potency recognized for each corticosteroid; by contrast, OMEs were largely unaffected by corticosteroid treatment. Permeation of clobetasol-17-propionate into and through the OMEs was time- and dose-dependent, regardless of whether this corticosteroid was delivered in liquid form or from a mucoadhesive patch, and both liquid- and patch-delivered clobetasol-17-propionate significantly reduced the secretion of interleukin-2 by activated T-cells. This study confirms that OMEs are more suitable models than cell monolayers for evaluating toxicity and drug delivery. After topical exposure, clobetasol-17-propionate accumulated in OMEs at a higher level than betamethasone-17-valerate and hydrocortisone-17-valerate, and exerted its immunosuppressive actions following application via the patch delivery system, highlighting the efficacy of this mode of drug delivery to treat OLP.