INTRODUCTION: Chronic kidney disease (CKD) is associated with an increased cardiovascular morbidity/mortality and the altered biological properties of HDL particles have been pointed out in this burden. Post-translational modifications (PTM) of HDL were highlighted as potential mediators of HDL dysfunction. We aimed to describe the adductome of HDL from non-diabetic hemodialysis patients and the nature of the modified proteins.
METHODS: HDL were sampled from the plasma of 9 non-diabetic hemodialysis and 9 potential kidney-donors patients with a sequential ultracentrifugation. Samples were analyzed using an nano-RSLC/Q-Orbitrap. Database using SequestHT with Proteome Discoverer 2.2 software against a Swissprot database and quantified with a label free quantitation approach. Oxidation, acetylation, carbonylation (4-HNE), carbamylation, guanydination, chlorination, nitration and nitrosylation were set as variable modifications.Protein quantitation was based on pairwise ratios and ANOVA hypothesis test.
RESULTS: 522 proteins were identified in HDL from HD patients and controls among which 40 (i.e. 7.6%) presented adduction sites. The main PTM were carbamylation (43%), 4-HNE (31%) and nitrosylation (26%) while guanidylation and chlorination were not found. Those proteins were involved in lipid metabolism, acute phase response, hemostasis, wound healing and muscular metabolism. Regarding the amount of amino-acids in the protein sequence, apoA1 and 2 were the proteins the more prone to adduction (11.61 and 10% respectively) followed by serum albumin (5.25%), apolipoprotein C1 (4.04%) and serum amyloid A4 (3.08%, Figure 1). Most of the key-proteins of HDL metabolism were found to be adductable.
CONCLUSIONS: HDL from HD patients presented several post-translational modifications of their proteins. Those proteins are involved in most of the biological functions of HDL and their modifications could contribute the dysfunction of HDL in CKD.
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