Science
Mechanism of Action
Kallikreins (KLKs) are enzymes essential for stratum corneum homeostasis. KLK5, KLK6, KLK7, KLK8, KLK13, and KLK14 specifically degrade corneodesmosomes, which are junctional structures between corneocytes, facilitating natural desquamation. For example, KLK5 targets corneodesmosin, desmoglein 1, and desmocollin 1. Furthermore, KLK5, KLK6, KLK13, and KLK14 are critical for processing profilaggrin into filaggrin, a protein vital for skin barrier integrity and natural moisturizing factor production. Kallikreins also interact with Protease-Activated Receptors (PARs), particularly PAR1 and PAR2, on keratinocytes, triggering signaling pathways that influence cell differentiation, proliferation, and migration, including roles in wound healing. However, dysregulation, such as overexpression of KLK5 and KLK7, can contribute to inflammatory responses and increased cathelicidin, implicated in conditions like rosacea.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
No specific concentration recommendations or common topical uses for exogenous kallikrein in skincare are available in the provided research data to suggest it is commonly 'dusted'.
The Formula
Formulation
Stability
As enzymes, kallikreins are sensitive to pH fluctuations. While optimal activity is often observed between pH 7.0 and 8.0, they can maintain activity within a broader range, including the acidic conditions of the outer stratum corneum (pH 4.5-7.5). For instance, KLK5 and KLK7 demonstrate proteolytic efficacy at pH 7.2 and 5.6 on certain substrates, and KLK5's cleavage of desmoglein 1 occurs at acidic pH. Stability and activity can be modulated by natural protease inhibitors (e.g., LEKTI) and certain metal ions like calcium.
Conflicts
- pH values significantly outside the optimal range (7.0-8.0) can diminish efficacy or stability.
- Known protease inhibitors will interfere with kallikrein activity.
- The presence of multiple strong active ingredients may increase skin irritation or compromise barrier function, especially if interfering with enzymatic processes.
- Ingredients that chemically destabilize or neutralize protein-based enzymes can reduce kallikrein's effectiveness.
Safety
Safety Profile
There is no specific safety assessment from the Cosmetic Ingredient Review (CIR) or SCCS for kallikrein as a cosmetic ingredient. The FDA regulates cosmetics but does not pre-approve most ingredients, and kallikrein is not listed among prohibited or restricted substances. General safety data sheets for Human Kallikrein indicate that its toxicological effects have not been thoroughly studied.
Your Skin
Skin Compatibility
Our Assessment
Verdict
While kallikreins are intrinsically vital for healthy skin desquamation and barrier function, there is currently insufficient research data regarding the topical application efficacy, optimal concentrations, and comprehensive safety profile for its use as an exogenous cosmetic ingredient.
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