KeratinoSens

KeratinoSens is an in vitro assay used to predict the skin sensitization potential of chemicals. It assesses an early event in the adverse outcome pathway by measuring activation of the Nrf2-ARE pathway in a human keratinocyte cell line that contains a luciferase reporter gene under the control of an antioxidant response element (ARE). When exposed to electrophilic chemicals capable of triggering sensitization, ARE-driven luciferase expression increases, detected as luminescence. In parallel, cytotoxicity is measured to determine usable concentrations and avoid false positives.

Method and interpretation: The test involves exposing the KeratinoSens cells to test substances for a defined period, typically about 24 hours. The concentration causing cytotoxicity is determined, and luminescence is measured at non-cytotoxic concentrations. A result is classified as positive (sensitizer) if ARE-driven luminescence exceeds a predefined threshold, negative if it does not. The assay is used within an integrated testing strategy, often alongside other in vitro methods to build a weight of evidence for regulatory decisions.

Regulatory status and use: KeratinoSens is one of the in vitro skin sensitization assays recognized for regulatory toxicology and contributed to international guidelines such as OECD Test Guideline 442D. It is widely used in industry and regulatory settings to reduce reliance on animal testing and to support hazard classification and risk assessment for cosmetics and chemicals.

Advantages and limitations: Advantages include a human-relevant mechanism and relatively high throughput. Limitations include coverage of only one key event of the sensitization pathway and possible discordance with in vivo results, so findings should be interpreted within a broader data set.

Related assays: KeratinoSens is part of a family of ARE-based assays for skin sensitization, often used in combination with others, such as LuSens, to form an integrated testing strategy.