Atopic dermatitis and the stratum corneum: part 3: the immune system in atopic dermatitis.

Part 3 of this three-part review of atopic dermatitis and the stratum corneum barrier discerns how immune dysregulation, including upregulation of a TH2 inflammation pattern, augmented allergic sensitization, sustained wound healing inflammation, and impaired innate immunity, plays an integral role in the pathogenesis of atopic dermatitis. An increased understanding of the interdependence, polymorphisms, and dysregulations of epidermal barrier functions, including the stratum corneum permeability barrier, immune defense, and antimicrobial barriers, should provide further knowledge about the pathophysiological mechanisms that are clinically relevant and that contribute to the development of atopic dermatitis. Further understanding of these mechanisms should lead to newer therapies that target specific pathogenic components of atopic dermatitis.

Atopic dermatitis and the stratum corneum: part 2: other structural and functional characteristics of the stratum corneum barrier in atopic skin.

This three-part review presents what is currently known about the involvement and interdependency of the epidermal barrier and immune response in the etiopathogenesis of atopic dermatitis. Part 1 of this review depicted the role of filaggrin in atopic dermatitis while this article, Part 2, evaluates the role of serine proteases and specific lipids in the structural and functional integrity of the stratum corneum and its multiple barrier functions in atopic dermatitis. Upregulation of serine protease activity causes adverse structural changes of the stratum corneum due to degradation of certain stratum corneum proteins that are integral to epidermal structure and functions, interference with the formation of the stratum corneum intercellular lipid membrane, which normally regulates epidermal water flux and gradient, and induction of a TH2 pattern of inflammation, which is the hallmark profile of atopic skin.

Atopic dermatitis and the stratum corneum: part 1: the role of filaggrin in the stratum corneum barrier and atopic skin.

This three-part review presents what is currently known about the involvement and interdependency of the barrier properties of the epidermis, especially the stratum corneum and various specific immunological responses in the etiopathogenesis of atopic dermatitis. Part 1 of this review depicts the role of filaggrin in atopic dermatitis while Part 2 (which will be published in an upcoming issue of The Journal of Clinical and Aesthetic Dermatology) evaluates the role of serine proteases and specific lipids in the structural and functional integrity of the stratum corneum and related barrier functions in atopic dermatitis. Filaggrin is a key component of the stratum corneum that is derived from a larger precursor protein and contributes to its physical strength, hydration status, skin pH, and buffering capacity among other physiochemical properties.