Evaluating serum biomarkers in keratoconus: the role of PCPE-1 and PCPE-2 in collagen metabolism and disease progression.

PURPOSE

This study aimed to compare the levels of procollagen C proteinase-enhancing protein 1 and Procollagen C Proteinase Enhancing Protein 2 (PCPE-1/PCPE-2) in the serum of patients with keratoconus and healthy individuals, and to evaluate their potential effects on keratoconus.

METHODS

This study prospectively included 65 patients diagnosed with keratoconus and followed up between October 2023 and May 2024, and 65 healthy individuals. 65 patients diagnosed with keratoconus were examined in the four groups. Serum PCEP-1 and PCEP-2 levels were measured in venous blood samples from the patient and control groups using ELISA.

RESULTS

A total of 130 patients were included in the study and divided into two groups: patients (n = 65) and controls (n = 65). The PCPE1 levels were 8.89 ± 4.45 (median: 7.38) in the patient group and 16.91 ± 11.30 (median: 13.18) in the control group, with a statistically significant difference (p = 0.001). In the patient group, PCPE2 levels were 10.32 ± 8.01 (median: 6.75), whereas in the control group, they were 19.62 ± 13.81 (median: 13.96), with this difference being statistically significant (p = 0.001). A significant positive correlation was observed between PCPE1 and PCPE2 expression in the patient group (r = 0.768, p = 0.001). Significant differences were detected between the stages in terms of PCPE1 (p = 0.001) and PCPE2 (p = 0.001) levels.

CONCLUSIONS

Serum PCPE-1 and PCPE-2 levels were significantly decreased in keratoconus and correlated with disease stage, indicating their potential as systemic biomarkers of collagen remodeling and disease progression.

KEY MESSAGES

What is known Keratoconus is an idiopathic, non-inflammatory, and progressive ectatic disease characterized by an irregular conical shape and thinning of the central and peripheral parts of the cornea. The extracellular matrix (ECM) of the cornea is particularly rich in collagen, and the synthesis of these components follows a specific program during corneal development and maturation. What is new PCPE-1 plays an important role in collagen fibril formation and tissue repair. PCPE-2 has a strong collagen-binding capacity and is highly expressed in developmental tissues and the adult heart. Dysfunction in the balance of corneal collagen synthesis and extracellular matrix formation in keratoconus indicates that these molecules may play an active role in corneal pathology.