Oxidised high-density lipoprotein in sarcopenia: a pilot study

The aging of society is progressing in developed countries, and sarcopenia is recognized as an age-related entity that manifests a low muscle mass with muscle dysfunction [1]. Of note, not only musculoskeletal disorders but also atherosclerotic cardiovascular diseases occur in sarcopenia [1, 2]. Although sarcopenia has multifactorial causes and its pathophysiology is not fully understood, oxidative stress is known to be involved in muscle damage detected in sarcopenia [3, 4].
With regard to a link between sarcopenia and atherosclerotic cardiovascular diseases, lipoprotein oxidation is considered to be possibly involved. In fact, an epidemiological study previously reported that low-density lipoprotein (LDL) oxidation predicted mobility limitation, and a high level of it was able to accurately predict severe mobility limitation [5]. However, other than that previous study [5], we do not know of any other study that has investigated lipoprotein oxidation in sarcopenia. In particular, as high-density lipoprotein (HDL) affects not only atherosclerotic formation but also muscle cell metabolism [6], a potential relationship between HDL oxidation and sarcopenia is of concern. We therefore performed a pilot study that compared the levels of oxidized HDL (oxHDL) between subjects with and without severe sarcopenia, as severe sarcopenia carries a definite risk of mortality [7].
A total of 64 older women (age: 60–89 years old) were enrolled in a clinical setting. We excluded those with acute-phase disease conditions and obvious heart disease. The Institutional Ethics Committee approved the study, and the subjects gave their informed consent. Severe sarcopenia was defined as having low levels of all three criteria: muscle mass of < 5.7 kg/m2 according to a bioimpedance analysis (InBody Inc., Tokyo, Japan), grip strength of < 18 kg according to a dynamometer, and gait speed of < 1.0 m/s according to an accelerometer, as described in the guideline [2]. The existence of diabetes mellitus was based on the medical history. In fasted serum samples, the HDL and LDL cholesterol levels were enzymatically determined, and the oxHDL levels were measured using an enzyme-linked immunosorbent assay (Hoken-Kagaku West, Co. Ltd., Kyoto, Japan) [8, 9]. A t-test and χ2 test were conducted between the groups, as well as a general linear model analysis for the oxHDL levels with adjustment for variables. p < 0.05 was considered significant.
Table I shows the clinical...


View full text...