Carreadores lipídicos nanoestruturados associados ou não ao valerato de betametasona e/ou alfa tocoferol para uso tópico em modelo experimental de dermatite atópica: desenvolvimento, caracterização e avaliação da eficácia terapêutica

Abstract

Atopic dermatitis (AD) is of great importance for public health, being considered the most prevalent chronic inflammatory skin disease globally. Emollients to reduce skin dryness, topical corticosteroids for inflammation, and oral antihistamines to reduce itching are among the first-line AD therapies. Despite the proven effectiveness of these treatments, frequent use is associated with adverse effects, limiting patient adherence to therapy. Therefore, the idea is to propose a product, using nanotechnology to encapsulate alpha tocopherol and/or betamethasone valerate (VB) in topical formulations for the treatment of AD. The formulations developed by ultrasonication presented sizes between 190.8 ± 1.5 nm and 209.0 ± 3.5 nm and polydispersity index (PDI) values lower than 0.20, indicating a homogeneous nanocarrier population with low variability. Transmission electron microscopy (TEM) images showed spherical and monodisperse lipid nanocarriers (NLCs), indicating good reproducibility. Zeta potential (PZ) presented values between -25.9 ± 0.90 and -34.1 ± 0.87 mV compatible with stable formulations, with charge repulsion between particles, preventing aggregation. The pH of the NLCs formulations were slightly acidic, varying between 6 and 7, like the pH of the skin and high VB encapsulation efficiency (>98%), suggesting good applicability for topical use. The formulations had concentrations in the order of 1013 NLCs/mL, indicating good yield. At 25°C, NLCcontrol, NLCa e NLCBV showed good stability over 12 months, while NLCBVa is recommended for use within 10 months. Assays with HaCat cells showed that betamethasone valerate (VB) encapsulation reduces the cytotoxicity presented by the free drug, while the cytotoxicity of alpha tocopherol is increased with encapsulation. With the encapsulation of alpha tocopherol with VB, this cytotoxicity is reduced. Rheology data showed that hydrogels produced with xanthan gum and collagen exhibited non-Newtonian behavior, compatible with providing slow drug flow and easy distribution into the skin. Dinitrochlorobenzene (DNCB) sensitization and challenges were effective in producing an AD model. Animals treated with Hydrogel, NLCcontrol and NLCa exhibited increased epidermal thickening and high scores for clinical signs of AD. Histological analyzes revealed a thick epidermis and an intense infiltrate of inflammatory cells, demonstrating a severe condition of AD. Treatment with NLCBV, NLCBVa, VBcommercial reduced ear thickness and showed improvement in clinical parameters, suggesting improvement in AD symptoms, with an epidermis of similar thickness to control animals and a significant reduction in inflammatory cells in epithelial lesions. Treatment with BV had no effect on serum IgE production, but NLCVB and VBcommercial reduced IgE levels locally. The DNCB-induced AD model stimulates a Th1 and Th2 response, with the production of IFNg, TNFa, IL-6 and IL-4, but not IL-2, IL-17A and IL-10, suggesting a chronic inflammation. NLCBV, NLCBVa and VBcommercial, effectively reduced the release of cytokines produced in epithelial inflammation caused by the topical application of DNCB. Finally, we believe that the formulations developed with NLCBV and NLCBVa effectively treat experimental AD.