Application of nano- and micro-particles on the topical therapy of skin-related immune disorders.

Several immune disorders may occur in the skin, such as psoriasis, atopic dermatitis and vitiligo. As the largest organ in the human body, skin provides a unique and non-invasive platform to deliver active pharmaceutical ingredients into superficial lesions or even circulations. In recent years, novel pharmaceutical particles were applied in the topical treatment for skin-related immune disorders to keep the stability, improve the bioactivity, as well as reduce the toxicity of APIs, or even provide a targeting property for the agents. As the pathogenesis of these diseases is increasingly highlighted, the target site and function of topical delivery of particles become more clear and specific. Therefore, diversified surface engineering of vehicles has gradually gained more attention. Appropriate size, charge and surface modification of API-loaded particles can bring out a favorable effect for skin disorders. In this review, comparison of normal and pathological skin structure, penetration route of various drug particles, nano- and micro- particles applied for skin-related immune disorders are summarized. In-vitro and in-vivo evaluation methods for topical therapy of immune disorders will be discussed. Moreover, recent applications of particles loaded with active ingredients from herbal medicines or biological agents for skin immune disorders are also highlighted.