Genetically Determined Hypercholesterolaemia Results into Premature Leucocyte Telomere Length Shortening and Reduced Haematopoietic Precursors.

Aims Leucocyte telomere length (LTL) shortening is a marker of cellular senescence and associates with increased risk of cardiovascular disease (CVD). A number of cardiovascular risk factors affect LTL, but the correlation between elevated LDL cholesterol (LDL-C) and shorter LTL is debated: in small cohorts including subjects with a clinical diagnosis of familial hypercholesterolaemia (FH). We assessed the relationship between LDL-C and LTL in subjects with genetic familial hypercholesterolaemia (HeFH) compared to those with clinically diagnosed, but not genetically confirmed FH (CD-FH), and normocholesterolaemic subjects. Methods and results LTL was measured in mononuclear cells-derived genomic DNA from 206 hypercholesterolaemic subjects (135 HeFH and 71 CD-FH) and 272 controls. HeFH presented shorter LTL vs. controls (1.27 +/- 0.07 vs. 1.59 +/- 0.04, P = 0.045). In particular, we found shorter LTL in young HeFH as compared to young controls (<35 y) (1.34 +/- 0.08 vs. 1.64 +/- 0.08, P = 0.019); moreover, LTL was shorter in statin-naive HeFH subjects as compared to controls (1.23 +/- 0.08 vs. 1.58 +/- 0.04, P = 0.001). HeFH subjects presented shorter LTL compared to LDL-C matched CD-FH (1.33 +/- 0.05 vs. 1.55 +/- 0.08, P = 0.029). Shorter LTL was confirmed in leucocytes of LDLR-KO vs. wild-type mice and associated with lower abundance of long-term haematopoietic stem and progenitor cells (LT-HSPCs) in the bone marrow. Accordingly, HeFH subjects presented lower circulating haematopoietic precursors (CD34 + CD45dim cells) vs. CD-FH and controls. Conclusions We found (i) shorter LTL in genetically determined hypercholesterolaemia, (ii) lower circulating haematopoietic precursors in HeFH subjects, and reduced bone marrow resident LT-HSPCs in LDLR-KO mice. We support early cellular senescence and haematopoietic alterations in subjects with FH.