DysfunctionalH5 HDLl is a carrier of pro-inflammatory sphingolipid cargo: large-scale lipidomic and apolipoprotein profiling

Background

HDL functionality, rather than HDL-cholesterol levels, is a critical determinant of cardiovascular risk. The most electronegative HDL subfraction (H5) has been identified as a dysfunctional and pro-atherogenic particle, yet the bioactive lipid components contributing to its pathogenicity remain insufficiently characterized.

Purpose

To compare the apolipoprotein composition and lipidomic profile of the most electronegative HDL subfraction (H5) with the least electronegative, cardioprotective subfraction (H1) in a large-scale cohort.

Methods

In 1,918 samples, HDL was fractionated into H1 and H5 subfractions. Apolipoproteins and lipid species were quantified using liquid chromatography–mass spectrometry (LC-MS). Differential abundance was assessed using fold-change and statistical significance criteria.

Results

H5 exhibited a pronounced shift toward an atherogenic apolipoprotein profile (all p<0.0001), characterized by enrichment of ApoB, Apo(a), ApoC3, and ApoE, whereas H1 was enriched in ApoA1, ApoA2, ApoC1, and ApoA4.

Lipidomic analysis identified 1,138 lipid features. Compared with H1, H5 demonstrated selective remodeling, with 46 lipids significantly reduced and six significantly increased. Upregulated species included pro-inflammatory sphingolipids (C16 sphinganine-1-phosphate, phytosphingosine-1-phosphate, and dehydrophytosphingosine) and glycerolipids (1-palmitoylglycerone-3-phosphate and 1-O-(2-methoxy-4-hexadecenyl)-sn-glycerol), molecules implicated in vascular inflammation and endothelial dysfunction.

Conclusions

The electronegative H5 HDL subfraction is defined by coordinated apolipoprotein remodeling and selective enrichment of pro-inflammatory sphingolipids. These findings indicate that dysfunctional HDL actively carries pathogenic lipid cargo rather than simply losing protective components. Targeting sphingolipid-enriched electronegative HDL may represent a novel strategy to attenuate vascular inflammation and cardiovascular risk.Lipodimics Volcano Plot of H5 over H1Proteomics Boxchart of H1 vs H5