TSLP expression in the skin is mediated via RARγ-RXR pathways

Area of Science:

• Immunodermatology
• Molecular Biology
• Endocrinology

Background:

• Thymic stromal lymphopoietin (TSLP) is a key initiator of atopic diseases, including atopic dermatitis (AD).
• Nuclear hormone receptor agonists, such as vitamin A and D derivatives, are known to upregulate TSLP in skin.
• Understanding TSLP regulation via nuclear hormone receptors is crucial for AD pathogenesis.

Purpose of the Study:

• To investigate the specific nuclear hormone receptor pathways regulating TSLP expression.
• To determine the connection between these pathways and the development/phenotype of atopic dermatitis.
• To elucidate the role of retinoic acid receptors (RARs), retinoid X receptors (RXRs), and vitamin D receptor (VDR) in TSLP regulation.

Main Methods:

• Topical administration of synthetic RAR, RXR, and VDR agonists and antagonists in mice.
• Quantification of TSLP expression in skin via quantitative reverse transcription polymerase chain reaction (QRT-PCR).
• Measurement of serum TSLP levels using enzyme-linked immunosorbent assay (ELISA).

Main Results:

• VDR and RARγ agonists, along with all-trans retinoic acid (ATRA), increased skin TSLP expression.
• RXR agonists alone did not affect TSLP; however, combined VDR-RXR and RARγ-RXR agonists showed significant TSLP induction (up to 48-fold).
• RAR and RXR antagonists, and RARα agonists, reduced skin TSLP expression.

Conclusions:

• RARγ-RXR mediated pathways are critical triggers for elevated skin TSLP, alongside VDR signaling.
• Topically applied or internally stimulated retinoids induce TSLP production, contributing to atopic dermatitis.
• Targeting these nuclear hormone receptor pathways could offer new therapeutic strategies for atopic dermatitis.