Development of RT h-CLAT, a Rapid Assessment Method for Skin Sensitizers Using THP-1 Cells as a Biosensor.

Area of Science:

• Toxicology
• Dermatology
• Molecular Biology

Background:

• In vitro skin sensitization assays are crucial animal-free alternatives for cosmetic and drug safety assessments.
• Current methods, though adopted by OECD guidelines, are often complex and expensive.
• There is a need for more efficient, cost-effective, and accurate in vitro skin sensitization testing.

Purpose of the Study:

• To refine an existing RT-PCR based assay using THP-1 cells for faster skin sensitization assessment.
• To identify optimal gene expression markers and conditions for reliable sensitization evaluation.
• To enhance the accuracy and reduce the time required for in vitro skin sensitization testing.

Main Methods:

• Comprehensive RNA sequencing (RNA-Seq) was performed on THP-1 cells exposed to sensitizers.
• Identification and selection of key sensitization marker genes (JUN and HMOX1).
• Development and application of the refined assay, RT h-CLAT, for evaluating chemical sensitization potential.

Main Results:

• A 5-hour exposure of THP-1 cells followed by measuring JUN and HMOX1 gene expression reliably predicts sensitization.
• A >2-fold increase in either gene expression indicates a sensitizing compound.
• The RT h-CLAT method demonstrated higher accuracy and reduced testing time (1 day vs. 2 days) compared to the OECD h-CLAT.

Conclusions:

• The RT h-CLAT assay provides a significantly improved, rapid, and accurate method for in vitro skin sensitization assessment.
• This refined assay offers a more efficient alternative to existing methods, supporting animal-free safety evaluations.
• The identified gene markers and optimized protocol advance the field of toxicological testing for topical products.