Development of image analysis tool to evaluate Langerhans cell migration after exposure to isothiazolinones.

Summary

Using an open-source QuPath-based, machine learning-assisted pipeline, the authors automated detection of epidermal layers and Langerhans cell positions to quantify migration in ex vivo human skin after isothiazolinone exposure. Only octylisothiazolinone induced migration toward the basal lamina consistent with sensitizers, and the water vehicle itself affected migration patterns.

Key Findings

• Developed and validated open-source QuPath/ML scripts for automated detection of skin layers and Langerhans cell positions.
• Ex vivo human skin exposed for 24 hours to four isothiazolinones showed vehicle-dependent effects on Langerhans cell migration.
• Only octylisothiazolinone induced migration toward the basal lamina consistent with known sensitizer behavior; methylisothiazolinone and benzothiazolinone showed different patterns.

Clinical Implications

Enables more objective preclinical assessment of potential skin sensitizers in cosmetics and household products, potentially reducing false negatives/positives and guiding safer ingredient selection.

Limitations

• Number of human donors and replicates not specified; preliminary dataset
• Short exposure window (24 hours) and limited chemical set
• Translational correlation with clinical ACD incidence not established

Future Directions

Expand to larger panels of sensitizers/vehicles, report donor variability, align metrics with OECD guidelines/AOPs, and evaluate predictive performance against clinical patch-test data.