Methods for assessing modified LDL immune complexes in subjects having or at risk of coronary artery disease
Inventors
Lopes-Virella, Maria F. • Virella, Gabriel T.
Assignees
MUSC Foundation for Research and Development • US Department of Veterans Affairs
Publication Number
US-8911958-B2
Publication Date
2014-12-16
Expiration Date
2030-09-17
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Abstract
The present invention relates to the analysis of modified LDL in the context of immune complexes. In particular, ox-LDL and AGE-LDL are shown to predict the development of coronary artery disease and other micro- and macrovascular disorders, particularly in the context of diabetes.
Core Innovation
The invention relates to methods for analyzing modified low density lipoprotein-immune complexes (mod-LDL-IC) to assess human diseases including type 1 diabetes and coronary artery disease (CAD). Specifically, the invention provides methods of predicting risk of CAD by measuring oxidized-LDL immune complexes (ox-LDL-IC) and advanced glycation endproduct-LDL immune complexes (AGE-LDL-IC) in biological samples such as serum or plasma from a subject, comparing these levels to normal standards, and predicting risk based on elevated levels.
The problem addressed by the invention arises from the complexity and technical difficulties in measuring antibodies to modified LDL and corresponding immune complexes due to interference by pre-formed immune complexes and non-specific isolation methods. Existing assays have limitations in specificity, reliability, and practicality for large patient cohorts. Moreover, conventional risk factors are insufficient in early prediction of coronary artery disease, especially in type 1 diabetes patients.
The invention overcomes these problems by providing methods that isolate mod-LDL-IC (e.g., by polyethylene glycol precipitation and affinity chromatography), separate mod-LDL from antibodies, and determine ox-LDL and/or AGE-LDL levels using immunoassays or chromatography techniques. Elevated levels of ox-LDL-IC and/or AGE-LDL-IC measured at a young age in subjects without manifest macrovascular disease strongly predict progression of atherosclerosis, measured as carotid intima-media thickening over extended follow-up periods. These measurements provide better predictive power for coronary artery disease risk than conventional risk factors such as LDL cholesterol, blood pressure, albumin excretion rate, and hemoglobin A1c levels.
Claims Coverage
The patent includes one independent claim focused on a method of detecting elevated levels of low density lipoprotein immune complexes in subjects by measuring specific types of modified LDL immune complexes.
Detection of oxidized and advanced glycation endproduct LDL immune complexes in a subject sample
A method comprising providing a mod-LDL-IC-containing biological sample from a subject, measuring oxidized-LDL immune complexes (ox-LDL-IC) and/or advanced glycation endproduct-LDL immune complexes (AGE-LDL-IC) in the sample, and comparing the measured levels to a normal standard.
Isolation and characterization of modified LDL immune complexes
The method includes isolating mod-LDL-IC from the sample, separating mod-LDL from antibodies via precipitation and affinity chromatography followed by selective elution, and determining levels of ox-LDL and/or AGE-LDL by immunoassays, gas chromatography, mass spectrometry, gel electrophoresis or column chromatography.
Applicability regardless of subject's mod-LDL-IC status and clinical background
The method applies to subjects exhibiting elevated ox-LDL, elevated AGE-LDL, both, or neither. It is useful for subjects with familial history of type 1 diabetes with micro- and/or macrovascular complications including cardiovascular disease, peripheral vascular disease, neuropathy, retinopathy, and nephropathy.
The claims cover methods for detecting and measuring specific modified LDL immune complexes in biological samples by isolation and immunoassays, enabling prediction of coronary artery disease and related complications in subjects, especially those with type 1 diabetes.
Stated Advantages
High levels of oxLDL and AGE-LDL immune complexes measured at a young age strongly predict accelerated carotid intima-media thickening, which is a surrogate marker for coronary artery disease.
Measurement of these modified LDL immune complexes provides superior predictive power for coronary artery disease progression compared to conventional risk factors such as LDL cholesterol, blood pressure, HbA1c, and albumin excretion rate.
The assays distinguish pathogenic immune complexes by isolating mod-LDL-IC and specifically measuring oxLDL and AGE-LDL, overcoming prior technical difficulties of non-specific immune complex measurements.
The methods help identify subjects at high risk for coronary artery disease and micro- and macrovascular complications early, enabling potentially improved clinical management and treatment decisions.
Documented Applications
Predicting risk of coronary artery disease in subjects including those with type 1 diabetes or other chronic autoimmune disorders by measuring ox-LDL-IC and/or AGE-LDL-IC in serum or plasma.
Predicting risk of developing micro- and/or macrovascular complications of type 1 diabetes such as cardiovascular disease, peripheral vascular disease, neuropathy, retinopathy, and nephropathy.
Predicting efficacy of treatments for type 1 diabetes complications by measuring changes in ox-LDL-IC and/or AGE-LDL-IC levels before and after treatment, to inform decisions on continuing or modifying therapy.
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