Fibrinogen-Like Protein 1 as a Novel Biomarker of Psoriasis Severity

Abstract

Background: Psoriasis is an immune-mediated chronic systemic inflammatory skin disease whose diagnosis and severity assessment pose challenges for clinicians worldwide. The use of serum biomarkers facilitates the early diagnosis and treatment of psoriasis.

Methods: This case-control study compared tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-17, IL-10, and fibrinogen-like protein 1 (FGL1) levels of 139 untreated psoriasis patients and 140 healthy controls. Serum samples were collected, and enzyme-linked immunosorbent assays were performed to quantify their levels. Subgroups were analyzed according to abnormal lipid metabolism status.

Results: Compared to controls, patients with psoriasis exhibited lower concentrations of serum TNF-α, IL-17, and FGL1 (P < 0.05). A correlation analysis showed that FGL1 was inversely correlated with high-density lipoprotein cholesterol and IL-17 in the psoriatic state. Stepwise multiple regression analysis revealed that FGL1 and total cholesterol were the independent determinants of Psoriasis Area and Severity Index (PASI) score in psoriasis patients. The area under the receiver operating characteristic curve of FGL1 assessing moderate-to-severe psoriasis and mild psoriasis was 0.70, while the area under the curve (AUC) assessing severe psoriasis and mild-to-moderate psoriasis was 0.67, better than that of IL-17. In addition, FGL1, but not IL-17, was able to identify psoriasis with abnormal lipid metabolism to a certain extent (AUC = 0.60).

Conclusion: In conclusion, serum FGL1 may be a promising biomarker for diagnosing and staging psoriasis. It may also be involved in its progression and comorbid abnormal lipid metabolism.

Keywords: biomarker; disease severity; fibrinogen-like protein 1; lipid metabolism; psoriasis.

Figure 1

Heat map of correlation coefficients of serum cytokine levels and blood lipid indexes in psoriasis versus normal controls. *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 2

ROC curves of FGL1 and IL-17 for differentiating different disease status of psoriasis. (A) ROC curve of FGL1 for differentiating normal controls from psoriasis patients; (B) ROC curve of IL-17 for differentiating normal controls from psoriasis patients; (C) ROC curve of FGL1 for differentiating severe psoriasis from mild-to-moderate psoriasis; (D) ROC curve of FGL1 for differentiating moderate-to-severe psoriasis from mild psoriasis.