Korean J Dermatol.  2024 Jun;62(5):285-293.

Immunohistochemical Profiling Reveals Distinct Inflammatory Landscape in Rosacea Subtypes

• Kim TM
• Lee JS
• Cho S

Abstract

Background
The immunological and histopathological understanding of rosacea subtypes remain unclear. This study aimed to characterize erythematotelangiectatic rosacea (ETR), papulopustular rosacea (PPR), and granulomatous rosacea (GR) immunologically through facial punch biopsy samples.
Objective
Our goal was to investigate the immunohistochemical profile of rosacea subtypes, providing insights into pathogenesis for targeted therapies.
Methods
Biopsy samples from 52 rosacea patients and 25 controls were stained for antibodies retrospectively. Statistical analyses identified expression differences.
Results
In the rosacea group (average age, 55.0; male-to-female ratio, 1:2.1), Langerhans cell count, p53, and vitamin D receptor expression showed no differences from controls or among subtypes. Claudin-1 and occludin expression decreased in rosacea compared to controls, with no variance among subtypes. Demodex mites were present in 40.4% of rosacea cases vs. 8.0% in controls (p=0.003), more frequently in PPR than GR, and absent in ETR. Neutrophil elastase expression mirrored the Demodex pattern. The CD4/CD8 ratio averaged 2.15 in rosacea without differences among subtypes. CD20 and CD68 expression increased in rosacea, escalating in the order of ETR, PPR, and GR, mirroring matrix metalloproteinase-2 (MMP-2). ETR exhibited insignificant CD20 and MMP-2 expression.
Conclusion
Our findings validate a CD4＋ T cell-driven response across all rosacea subtypes. Increased neutrophils, B cells, and macrophages, likely influenced by Demodex, were observed in PPR and GR. Demodex mites may recruit additional B cells and macrophages, potentially linked to MMP-2 expression. This comprehensive characterization offers additional insights into the immunopathogenesis of rosacea, paving the way for targeted interventions.

Keyword

CD4-positive T-lymphocytes; Demodex; Etiology; Immunohistochemistry; Rosacea; Rosacea subtype