Nail plate keratin and fungal cells

The nail plate keratin and fungal cells represent the pathological environment of onychomycosis, where fungal pathogens invade the hard keratinized structure of the nail. The nail plate is a complex arrangement of hard alpha-keratins, which are fibrous proteins cross-linked by disulfide bonds, providing a protective but highly impermeable barrier (StatPearls, 2023). Fungal cells, most commonly dermatophytes like Trichophyton rubrum, colonize this environment by secreting keratinases that degrade the nail's structural proteins for sustenance (Journal of Fungi, 2021). Effective therapeutic intervention requires drugs that can successfully traverse the dense keratin matrix to reach the fungi residing in the nail bed and plate. Modern topical treatments like efinaconazole and tavaborole are specifically formulated to have low keratin binding and high nail penetration to achieve fungicidal concentrations at the site of infection (Drugs, 2015). This target complex is characterized by its resistance to treatment, often requiring months of therapy due to the slow growth rate of the nail. Understanding the biochemical properties of nail keratin and the life cycle of the invading fungal cells is essential for improving clinical outcomes in chronic nail infections. Challenges in targeting this complex include the high affinity of many antifungals for keratin, which can sequester the drug and prevent it from reaching the underlying pathogens (Journal of Pharmaceutical Sciences, 2014).

Other names

Onychomycosis complexNail keratinDermatophyte-infected nailTinea unguium target

Antifungal agents must penetrate the dense keratin matrix of the nail plate to reach the fungal cells, where they inhibit essential processes such as ergosterol biosynthesis (via squalene epoxidase or 14-alpha-demethylase) or protein synthesis (via leucyl-tRNA synthetase) (Journal of Fungi, 2021; FDA, 2014).