A comparative exploration of immunohistochemical markers in patients with papulopustular rosacea undergoing treatment with oral isotretinoin versus doxycycline.

BACKGROUND: Rosacea is a chronic inflammatory disease, and doxycycline is a widely recommended treatment for it due to its anti-inflammatory action. Oral isotretinoin reduces sebaceous gland activity and modulates toll-like receptors, reducing inflammation. Our aim was to investigate the effect of these two drugs on the expression of cutaneous immunohistochemical biomarkers related to etiopathogenic factors involved in rosacea. METHODS: We conducted a randomized, comparative, and evaluator-blinded trial, including 40 participants with moderate and severe papulopustular and ocular rosacea. Participants were treated with doxycycline (DOXY) 100 mg or isotretinoin (ISO) 0.3 mg/kg daily. Immunohistochemistry at baseline and after 4 months was used to demonstrate the expression of the biomarker on the affected skin. RESULTS: The following changes were detected: a reduction in the vessel count after using VEGF with DOXY (P = 0.010); a decrease in VEGF intensity with ISO (P < 0.001) and DOXY (P = 0.020); a reduction of nitric oxide synthase enzyme with both drugs in the inflammatory infiltrate (ISO P < 0.001; DOXY P = 0.003); however, only with ISO was there a significant (P = 0.030) decrease at the level of the sebaceous glands, indicating a reduction of nitric oxide synthesis; a reduction of TRPV-1 expression at the level of the sebaceous glands was observed only with DOXY (P = 0.041); a decrease of cathelicidin LL37 expression, a key antimicrobial peptide in the etiopathogenesis of rosacea, was noted with both drugs, although at the level of sebaceous glands, only with DOXY (P = 0.007). CONCLUSIONS: Oral isotretinoin and doxycycline have modified the expression of cutaneous biomarkers related to rosacea etiopathogenesis, demonstrating their role in controlling inflammatory and vascular processes.