Proprotein Convertase Subtilisin/Kexin type 9 affects insulin but not lipid metabolism in cystic fibrosis.

Purpose: Cystic Fibrosis (CF) is the most common genetic disorder and, with improved survival, glucose abnormalities have emerged as a major comorbidity. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a regulator of plasma LDL-cholesterol homeostasis, is associated with lipid and glucose metabolism in healthy individuals. Here we report on the link between PCSK9 and markers of metabolism in CF.

Methods: Cross-sectional analysis was performed on CF patients (≥ 18 years, N=94) from the Montreal Cohort, without known diabetes, and on healthy individuals (N=19). The levels of PCSK9 and lipid markers were quantified and all subjects underwent a 2 h oral glucose tolerance test.

Results: No significant differences in PCSK9 levels were found between healthy individuals and patients with CF, or between the groups with different degrees of glucose tolerance. No association was found between PCSK9 and markers of lipid metabolism; however, a positive correlation was found between PCSK9 and total insulin secretion and a negative one with insulin sensitivity in CF patients who had normal glucose tolerance.

Conclusion: Circulating levels of PCSK9 in the CF population are comparable to those in the healthy population. There are no associations between PCSK9 levels and either glucose or lipid homeostasis parameters. Nevertheless, a statistically significant link was observed between PCSK9 and markers of insulin homeostasis, solely in CF patients who presented normal glucose tolerance. Further exploration of the relationship between PCSK9 and insulin homeostasis in CF patients with normal glucose tolerance is warranted.