Ultraflexible lipid vesicles loaded with cyanocobalamin or cyclosporin A downregulate acute and chronic immuno-inflammatory skin states

Inflammatory skin conditions affect chronically a notable number of patients worldwide. Despite their prevalence, effective long-term treatments with minimal side effects remain limited. In this piece of work, three lipid-based nanocarriers were developed and applied topically to enhance the dermal delivery of two drugs, cyanocobalamin (vitamin B12) and cyclosporine A (CsA), with different physicochemical properties and negligible skin absorption (>500 Da). Previous reports show potential activity of both drugs to tackle inflammatory states. However, these studies provide only partial insights into the formulation process or lack strategies to optimize B12 and CsA skin delivery. Herein, we report a comprehensive approach covering the design, development, and complete evaluation of these systems, representing the first complete evidence of B12 and CsA application to inflammatory skin purposes through a nanotechnological strategy. Specifically, conventional liposomes (L), transfersomes (T) and ethosomes (E) were designed, produced and characterized. They showed optimal properties in terms of size (<300 nm) and homogeneity (PDI <0.3) for transdermal and dermal administration. Besides, the drug entrapment efficiency was adequate according to the physicochemical properties of each one of the loaded drugs. The drug permeability through the skin was assessed ex vivo, showing negligible passive diffusion of free-drugs and enhanced skin absorption of both drugs when the lipid-based nanosystems were used. Particularly, transfersomes and ethosomes provided the best permeation flux through the skin. At high nanoparticle concentrations, liposomal and transfersomal dispersions exhibited good biocompatibility (>70 %). Transfersomal formulations (T-CsA and T-B12) were selected to test their activity in three in vivo murine models of skin inflammation: TPA-induced cutaneous inflammation and delayed type hypersensitivity (DTH) models. Both formulations demonstrated promising activity in the TPA model, mainly regarding leukocyte infiltration. Nevertheless, only T-B12 showed anti-inflammatory effects in the acute DTH model, mainly regarding edema formation and slightly concerning cell infiltration. Finally, these formulations exhibit their full potential in diminishing chronic skin inflammatory states, as T-CsA and T-B12 notably normalized the inflammatory response: pro-inflammatory cytokine downregulation, decrease of cellular infiltration, edema reduction and negligible histopathological damage.