HDL as markers of pathological remodelling and anti-protease vectors – HDLomics

Beneficial effects of HDL in atherosclerosis remains chiefly associated with reverse transport of cholesterol, even if other anti-atherogenic properties are well documented (anti-oxidant, anti-inflammatory or anti-thrombotic effects). Proteomic approaches have shown that HDL are more than lipids associated with apolipoprotein A1. We and others have reported the presence of alpha-1 antitrypsin (AAT) associated with HDL. This serine protease inhibitor is the natural inhibitor of neutrophil elastase, reported that to play a role in atherothrombotic lesions, including aortic abdominal aneurysm (AAA) in which it can be responsible for the arterial wall fragilization.

The aims of this project are:
- to identify new proteins associated with HDL in pathological conditions by comparing HDL from atherothrombotic patients versus controls, using a proteomic approach (task 1)
- to use HDL as a vector of anti-proteases and in particular of anti-elastase in order to target diseased tissue and thus counteract the proteases responsible for degradation of the extracellular matrix and cell death (tasks 2, 3, 4)

The search of biomarkers in atherosclerosis is of major importance in order to predict the onset of clinical complications, to evaluate the efficacy of treatments and to understand its pathophysiology, in order to define new therapeutic targets.
In the task #1, we aim to discover new proteins/peptides associated with HDL in normal and pathological conditions. For this purpose, we will isolate HDL by two different techniques:
- ultracentrifugation
- immunoabsorption
HDL will be isolated from plasma of coronary patient versus stable angina or control subjects (BIOCore Study “Biomarkers of COronary Events” PIs: Pr L. Feldman- Dr O. Meilhac). HDL will also be isolated from atherothrombotic samples (human carotid endarterectomy samples with or without intraplaque hemorrhages) and compared to those isolated from fatty streaks of human aortas.

In the tasks #2, 3, 4, we plan to use HDL as natural vector to deliver anti-proteases within diseased areas in different pathologies.
We will use 4 animal models in which leukocyte elastase plays a pivotal role:
- A rat model of AAA in which the thrombus and neutrophils that it contains are a source of elastase
- A mouse model of emphysema induced by elastase and characterized by an acute influx of neutrophils into the lung, leading to the destruction of alveolae,
- A rat model of cerebral ischemia by injection of a thrombus, in which we already have shown that HDL are protective in acute conditions. A model of blood brain barrier will be used to get insights into the mechanisms involved in HDL protection.
- A mouse model of neoangiogenesis, allowing us to test the effect of elastase on destabilization of neovessels and the potential protective effect of HDL

Both fields of HDL proteomics and the use of HDL for therapeutic application emerged very recently. The aims of the proposed project are highly innovative and ambitious. This project is totally original in the context of the Inserm Unit 698 since nobody in the laboratory works on lipoproteins and HDL in particular. Albeit very original, it will provide many opportunities of collaborations with all the teams composing the Inserm Unit 698 (hemostasis, cardiovascular remodelling, bio-engineering, immunopathology and clinical research).
This nascent team should perpetuate after the 36-period of this ANR funding, coinciding with the application for de novo creation of this Inserm Unit.

Finally, this project has a great potential of valorisation: we already protected the use of HDL as a vector of pharmacologic coumpounds including anti-proteases by a European patent (July 09). A collaboration has been initiated with CSL Behring (specialized in commercialization of HDL and AAT). Valorisation process will be conducted in close collaboration with Inserm Tranfert.