Abstract P106: Stabilization Muscles Drive Associations Between Lipoproteins And Total Abdominal Muscle And Intermuscular Adipose Tissue In The Multi-ethnic Study Of Atherosclerosis

Introduction: Quality and quantity of skeletal muscle decrease with age, largely due to adipose tissue infiltration, and are important determinants of metabolic health. To inform efforts to slow aging-related decline in muscle mass and prevent myosteatosis, a better understanding of the biological determinants of muscle atrophy and quality is needed. We used targeted lipidomics to identify, with a greater specificity, lipoproteins associated with muscle and intermuscular adipose tissue (IMAT) area (quantity) and density (quality) of the total abdominal, locomotion, and stabilization muscles in the Multi-Ethnic Study of Atherosclerosis. Hypothesis: Lower density lipoproteins will be positively associated with muscle and IMAT quantity, but negatively associated with quality. Methods: At visit one, 105 serum lipoproteins were measured by Bruker lipoprotein subclass analysis with 1 H-Nuclear Magnetic Resonance spectroscopy. Muscle and IMAT area (cm 2 ) and density (Hounsfield units) were estimated 2.6 years, on average, after visit 1 for the total abdominal, locomotion (psoas), and stabilization (paraspinal, oblique, and rectus abdominis) muscles from computed-tomography scans at the L4/L5 spinal junction. We identified lipoproteins associated with body composition using linear regression adjusting for age, gender, race, diet, physical activity, lipid-lowering medication, and multiple comparisons using a 1% false discovery rate. Results: Participants (N=947) were 44-84 years old (mean: 63), 51% men, 40% White, 16% Black, 16% Chinese American, and 27% Hispanic American. Among 105 lipoproteins, 24 were associated with total muscle area, whereas none were associated with muscle density. When examining specific muscle groups, 25 lipoproteins were associated with stabilization muscle area, driven by the oblique muscles. As for total IMAT area, there were 27 associations with lipoproteins. Specifically, 27 lipoproteins were associated with stabilization muscle IMAT area, driven by oblique and rectus abdominis muscles. Last, 39 lipoproteins were associated with total IMAT density, with 28 and 33 associated with locomotion and stabilization (driven by obliques) IMAT density, respectively. Higher VLDL: cholesterols, free cholesterols, phospholipids, and triglycerides and lower HDL: cholesterols and free cholesterols were associated with higher muscle area and IMAT area, but lower IMAT density (