High- density lipoprotein function is abnormal in idiopathic inflammatory myopathies

Area of Science:

• Cardiovascular Medicine
• Immunology
• Rheumatology

Background:

• Idiopathic inflammatory myopathies (IIM) involve vascular endothelium damage.
• High-density lipoprotein (HDL) normally protects the vascular endothelium from oxidized phospholipids.
• Oxidative stress contributes to IIM pathogenesis.

Purpose of the Study:

• To evaluate the antioxidant function of HDL in IIM patients.
• To investigate the relationship between HDL antioxidant function and IIM characteristics.

Main Methods:

• Assessed HDL antioxidant function using a cell-free assay measuring HDL's ability to inhibit LDL oxidation (HDL inflammatory index - HII).
• Analyzed cholesterol profiles, oxidized fatty acids in HDL, and plasma MPO activity.
• Compared a subgroup of IIM patients with healthy controls.

Main Results:

• HDL antioxidant function was significantly worse in IIM patients (HII 1.12) compared to controls (HII 0.82).
• Higher HII correlated with increased plasma MPO activity and oxidized fatty acids in HDL.
• Impaired HDL function was noted in patients with anti-MDA5 or anti-synthetase antibodies, and associated with higher disease activity and DM diagnosis.

Conclusions:

• HDL antioxidant function is abnormal in IIM patients.
• This dysfunction may contribute to microvascular inflammation and damage in IIM.
• Further investigation into HDL's role in IIM pathogenesis is warranted.