Proprotein convertase subtilisin/kexin type 9 in patients with systemic sclerosis

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that regulates cholesterol metabolism through low-density lipoprotein receptor degradation, and which has been linked to cardiovascular risk. The purpose of the present study was to examine whether PCSK9 serum levels are disrupted in patients with systemic sclerosis (SS) compared to controls, and if PCSK9 is related to disease-related data and the subclinical atherosclerosis that occurs in these patients.

Cross-sectional study that encompassed 146 individuals; 73 patients with SS and 73 age- and sex-matched controls. PCSK9, lipoproteins serum concentrations, and standard lipid profiles were assessed in patients and controls. Carotid intima-media thickness (cIMT) and the presence of carotid plaques were evaluated in SS patients. A multivariable analysis, adjusted for traditional cardiovascular risk factors, was performed to evaluate the differences in PCSK9 between patients and controls, the association of SS-related manifestations with PCSK9 levels, and if PCSK9 was associated with subclinical carotid atherosclerosis in SS patients.

After multivariable analysis, PCSK9 was downregulated in SS patients compared to controls (beta coefficient -78 (95%CI -106 - -50) ng/ml, p=0.000) and skin thickness was associated with higher serum levels of PCSK9 (beta coef. 22 (7-37) units, p=0.005). PCSK9 was significantly and positively associated with cIMT (beta coef. 0.65 (0.06-1.24) ng/ml, p=0.031) in SS patients after multivariable adjustment.

PCSK9 serum concentration is downregulated in SS patients compared to controls and is directly associated with disease severity subrogated parameters. PCSK9 was independently related to cIMT in SS patients.