Track

Basic Science

Abstract

Background: Frontal fibrosing alopecia (FFA) has been considered a variant of lichen planopilaris (LPP) due to shared histopathologic features. However, FFA presents distinct clinical characteristics and variable therapeutic responses. Objectives: Evaluating the expression of Peroxisome Proliferator-Activated Receptor gamma (PPARγ), Toll-Like Receptors 2 and 4 (TLR2, TLR4), Nucleotide-binding Oligomerization Domain-containing proteins 1 and 2 (NOD1, NOD2), Matrix Metalloproteinases 1 and 2 (MMP-1, MMP-2), and the tumor suppressor protein p53 by using immunohistochemistry (IHC) patients with LPP or FFA. Materials and Methods: IHC was performed on 40 biopsy-confirmed cases of LPP or FFA and 20 controls. A semi-quantitative analysis assessed expression levels and distribution of the target markers. Results: Compared to control, FFA cases showed significantly higher PPARγ expression in sebaceous glands (SG, p=0.007), hair follicles (HF, p=0.001), and keratinocytes (KT, p=0.009); increased TLR2 in SG (p=0.005); NOD1 in HF (p=0.025) and lymphocytes (p<0.001); NOD2 in lymphocytes (p=0.002); and p53 in HF and KT (both p<0.001). Compared to LPP, FFA showed greater expression of PPARγ (p=0.006), TLR2 in SG (p=0.005), NOD1 in HF (p=0.013), and TLR4 in SG (p=0.006). The LPP group had higher positivity for p53 in HF and KT versus control (both p<0.001). MMP-1 and MMP-2 showed no significant differences between groups. Conclusion: PPARγ, TLR2, TLR4, NOD1, NOD2, and p53 may contribute highly to FFA pathogenesis, while p53 seems to be a more exclusive pathway in the LPP pathogenesis.