High density lipoprotein can modulate the inhibitory effect of oxLDL on prostacyclin generation by rat aorta in vitro

Alterations of HDL particle phospholipid composition and role of inflammation in rheumatoid arthritis

The increased cardiovascular risk in RA (rheumatoid arthritis) cannot be explained by common quantitative circulating lipid parameters. The objective of the study was to characterize the modifications in HDL phosphosphingolipidome in patients with RA to identify qualitative modifications which could better predict the risk for CVD. Nineteen patients with RA were compared to control subjects paired for age, sex, BMI, and criteria of metabolic syndrome. The characterization of total HDL phosphosphingolipidome was performed by LC-MS/MS. RA was associated with an increased HDL content of lysophosphatidylcholine and a decreased content of PC (phosphatidylcholine), respectively, positively and negatively associated with cardiovascular risk. A discriminant molecular signature composed of 18 lipids was obtained in the HDL from RA patients. The detailed analysis of phospholipid species showed that molecules carrying omega-3 FA (fatty acids), notably docosahexaenoic acid (C22:6 n-3), were depleted in HDL isolated from RA patients. By contrast, two PE (phosphatidylethanolamine) species carrying arachidonic acid (C20:4 n-6) were increased in HDL from RA patients. Furthermore, disease activity and severity indexes were associated with altered HDL content of 4 PE and 2 PC species. In conclusion, the composition of HDL phosphosphingolipidome is altered during RA. Identification of a lipidomic signature could therefore represent a promising biomarker for CVD risk. Although a causal link remains to be demonstrated, pharmacological and nutritional interventions targeting the normalization of the FA composition of altered phospholipids could help to fight against RA-related inflammation and CVD risk.

Proinflammatory high-density lipoprotein results from oxidized lipid mediators in the pathogenesis of both idiopathic and associated types of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by abnormal elaboration of vasoactive peptides, endothelial cell dysfunction, vascular remodeling, and inflammation, which collectively contribute to its pathogenesis. We investigated the potential for high-density lipoprotein (HDL) dysfunction (i.e., proinflammatory effects) and abnormal plasma eicosanoid levels to contribute to the pathobiology of PAH and assessed ex vivo the effect of treatment with apolipoprotein A-I mimetic peptide 4F on the observed HDL dysfunction. We determined the "inflammatory indices" HII and LII for HDL and low-density lipoprotein (LDL), respectively, in subjects with idiopathic PAH (IPAH) and associated PAH (APAH) by an in vitro monocyte chemotaxis assay. The 4F was added ex vivo, and repeat LII and HII values were obtained versus a sham treatment. We further determined eicosanoid levels in plasma and HDL fractions from patients with IPAH and APAH relative to controls. The LIIs were significantly higher for IPAH and APAH patients than for controls. Incubation of plasma with 4F before isolation of LDL and HDL significantly reduced the LII values, compared with sham-treated LDL, for IPAH and APAH. The increased LII values reflected increased states of LDL oxidation and thereby increased proinflammatory effects in both cohorts. The HIIs for both PAH cohorts reflected a "dysfunctional HDL phenotype," that is, proinflammatory HDL effects. In contrast to "normal HDL function," the determined HIIs were significantly increased for the IPAH and APAH cohorts. Ex vivo 4F treatment significantly improved the HDL function versus the sham treatment. Although there was a significant "salutary effect" of 4F treatment, this did not entirely normalize the HII. Significantly increased levels for both IPAH and APAH versus controls were evident for the eicosanoids 9-HODE, 13-HODE, 5-HETE, 12-HETE, and 15-HETE, while no statistical differences were evident for comparisons of IPAH and APAH for the determined plasma eicosanoid levels in the HDL fractions. Our study has further implicated the putative role of "oxidant stress" and inflammation in the pathobiology of PAH. Our data suggest the influences on the "dysfunctional HDL phenotype" of increased oxidized fatty acids, which are paradoxically proinflammatory. We speculate that therapies that target either the "inflammatory milieu" or the "dysfunctional HDL phenotype," such as apoA-I mimetic peptides, may be valuable avenues of further research in pulmonary vascular diseases.