Using the AP1 Transcription Factor FOSL1 to Assess the Exacerbation of Psoriasis

The transcription factor AP1 plays a crucial role in the proliferation, apoptosis, and terminal differentiation of epidermal keratinocytes.

This study aimed to clarify whether the subunit of AP1, FOSL1 protein, can be used to assess the exacerbation of psoriasis by evaluating its changes in protein and mRNA levels in cultured epidermal keratinocytes and skin specimens of the patients prescribed with bathwater PUVA (Psoralen and UVA) therapy. This study aimed to investigate FOSL1, a subunit of the transcription factor AP-1, as a potential biomarker for psoriasis by examining its protein and mRNA expression in skin specimens from patients undergoing bathwater PUVA (Psoralen and UVA) therapy and cultured epidermal keratinocytes.

The distribution of FOSL1 in patients' skin was explored by immunohistochemistry. Changes in gene and protein expression were quantitatively assessed by qPCR and ELISA, respectively.

Immunohistochemistry analysis revealed that FOSL1 accumulated in lesional skin. The expression of FOSL1 significantly increased during disease flare-ups but decreased following the treatment with bathwater PUVA therapy. Furthermore, silencing FOSL1 led to a marked reduction in the expression of ten FOSL1 target genes associated with the disease.

Our study suggests that FOSL1 shows potential as a biomarker for psoriasis. This is supported by two key findings: first, the expression of FOSL1 correlates with disease activity, and second, its expression is linked to changes in the expression of genes previously implicated in the pathogenesis of psoriasis, namely MMP1, MMP9, IVL, CCNA2, CCL2, HMOX1, PLAU, PLAUR, and THBD.