Stratum corneum surface pH and pH-sensitive enzymes

The stratum corneum (SC) surface pH, commonly known as the "acid mantle," is a critical physiological parameter typically maintained between 4.5 and 5.5 (NIH, 2024). This acidic environment is essential for the optimal function of various pH-sensitive enzymes involved in skin barrier maintenance and desquamation (ResearchGate, 2024). Key enzymes include β-glucocerebrosidase and acidic sphingomyelinase, which process lipids into ceramides to maintain the permeability barrier, and kallikrein-related peptidases (KLK5 and KLK7), which regulate the shedding of dead skin cells (NIH, 2020; Frontiers in Medicine, 2011). In conditions such as atopic dermatitis, psoriasis, and aging, the SC pH becomes elevated, leading to impaired lipid processing and excessive protease activity that compromises barrier integrity and triggers inflammation (NIH, 2024; ResearchGate, 2024). Therapeutic interventions often target this system by applying acidic formulations, such as pH-buffered cleansers and moisturizers containing alpha-hydroxy acids, to restore the natural acidic milieu (NIH, 2024). By normalizing the SC pH, these treatments help reactivate ceramide-generating enzymes and inhibit the pro-inflammatory protease cascades associated with barrier dysfunction (NIH, 2024).

Other names

Acid mantleSkin surface pHStratum corneum aciditySC pHEpidermal acid mantle

Restoration of the skin's acidic pH (acid mantle) to optimize the activity of lipid-processing enzymes and inhibit the activity of desquamatory serine proteases, thereby improving barrier function and reducing inflammation.