Transcriptomic Analysis of the Major Orphan Ichthyosis Subtypes Reveals Shared Immune and Barrier Signatures

Area of Science:

• Dermatology
• Immunology
• Genomics

Background:

• Inflammatory pathways are implicated in common ichthyosis.
• Comprehensive skin characterization across ichthyosis subtypes is lacking.
• This gap hinders the development of targeted treatments for ichthyosis.

Purpose of the Study:

• To characterize immune and barrier profiles in ichthyosis subtypes.
• To analyze skin transcriptomes from a large cohort of ichthyosis patients.
• To identify subtype-specific molecular signatures in ichthyosis.

Main Methods:

• Global RNA-sequencing of skin samples from 54 ichthyosis patients and 40 controls.
• Analysis included Netherton syndrome, epidermolytic ichthyosis, lamellar ichthyosis, and congenital ichthyosiform erythroderma.
• Differentially expressed genes identified using fold change > 2 and false discovery rate < 0.05.

Main Results:

• All ichthyosis subtypes exhibited significant T helper (Th) 22/Th17 skewing (e.g., IL-17A/C/F, S100A7/8/9/12).
• Lipid metabolism and barrier junction markers were downregulated across subtypes, while epidermal cornification and proliferation markers were upregulated.
• Netherton syndrome showed modest Th2 changes, and congenital ichthyosiform erythroderma showed Th1 skewing.

Conclusions:

• Common ichthyosis variants share Th17/Th22 pathway aberrations and barrier function defects.
• Minimal Th2 pathway modulation was observed.
• Findings may elucidate ichthyosis pathogenesis and inform subtype-specific therapeutic strategies.