Keratinocytes and other skin cell types

Keratinocytes are the primary structural and functional cells of the epidermis, constituting approximately 90% of the skin's outermost layer [1, 13]. Their fundamental biological role is the creation of a semi-permeable barrier that protects the body from mechanical injury, pathogens, and dehydration through the production of keratin and lipids [2, 9]. Beyond keratinocytes, the skin contains specialized cells such as melanocytes for UV protection, Langerhans cells for immune surveillance, and Merkel cells for sensory perception [3, 4]. Dysregulation of these cell populations is central to the pathogenesis of various dermatological diseases, including psoriasis, atopic dermatitis, and skin cancers like squamous cell carcinoma [7, 12]. Although these cells represent a tissue category rather than a single molecular target, they house numerous receptors—such as retinoic acid receptors (RAR) and vitamin D receptors (VDR)—that are targeted by pharmacological agents [8, 9]. Drugs like tretinoin and calcipotriene interact with these targets to modulate cell proliferation and differentiation, while modern biologics target the cytokine signaling pathways that influence skin cell behavior in inflammatory conditions [10, 15].

Other names

Epidermal cellsSkin cellsKCsMelanocytesLangerhans cellsMerkel cellsFibroblastsAdipocytes

Pharmacological agents targeting these cells typically act as agonists for nuclear receptors such as retinoic acid receptors (RAR) and vitamin D receptors (VDR), or as inhibitors of cytokine signaling pathways (e.g., IL-17, IL-4/13) to normalize cell proliferation, differentiation, and inflammatory responses [8, 10, 12].