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Sobenin et al. Desialylated LDL in diabetes

INTRODUCTION on the desialylated LDL isolated from the blood of
diabetic patients and healthy individuals, to examine
Accelerated coronary and peripheral vascular their distribution by hydrated density and the relationship
atherosclerosis is the most common long-term between the LDL density and atherogenicity.
complication of diabetes mellitus. [1-3] The mortality
rate of coronary heart disease (CHD) is up to four METHODS
times higher in diabetic than nondiabetic individuals.
Therefore, CHD is the leading cause of death in Patients
diabetic patients. [4-6] Many factors contribute to the This study was conducted in accordance with the
increased rate of atherosclerosis progression in Helsinki Declaration of 1975 as revised in 1983. It
diabetes, including alterations in plasma lipid profile, was approved by the local ethics committee of the
platelet function, clotting factors, metabolism of arterial Institute for Atherosclerosis Research, Skolkovo
wall cells, and elevated blood pressure. The precise Innovation Center, Moscow, Russia. All participants
mechanisms of premature atherogenesis in diabetic gave their written informed consent prior to inclusion
patients, however, remain unclear. in the study. The study group comprised of 10 type 1
diabetic patients, 10 type 2 diabetic patients, and 10
At the cellular level, the deposition of intracellular healthy control subjects, free from coronary artery
cholesterol in the arterial wall and subsequent foam- disease [Table 1]. The diagnosis of diabetes mellitus
cell formation is a typical feature of early atherosclerotic was verified according to the 1997 criteria by the
lesions. Low-density lipoprotein (LDL) has been Expert Committee on the Diagnosis and Classification
[7]
associated with sourcing of accumulating lipids. [6,8,9] of Diabetes Mellitus (ADA), 1998 WHO consultation
However, LDL isolated from healthy individuals failed to criteria, and 1985 WHO criteria. [19] Type 1 diabetic
produce notable cholesterol accumulation in cultured patients were on insulin therapy, and type 2 diabetic
arterial smooth muscle cells or macrophages. [10,11] It patients were treated with oral hypoglycemic agents,
was hence accepted that LDL is required to undergo namely sulfonylurea derivatives.
structural alterations or chemical modifications to
become atherogenic. [12] However, modified LDL LDL isolation, lectin chromatography, and
particles are still not considered as clinical biomarkers density fractionation
or therapeutic targets because of insufficient evidence.
Therefore, additional studies, both basic and clinical, Venous blood (15 mL) was drawn after overnight
are necessary to fill the existing gap in the knowledge. fasting in plastic tubes containing 0.1% EDTA. Plasma
was separated by centrifugation, and ε-aminocaproic
Previously, we have shown that LDL from diabetic acid (1 mmol/L) was added. LDL (density, 1.025-
patients, unlike LDL from healthy individuals, is able 1.063 g/mL) was isolated by sequential preparative
[20]
to induce significant lipid deposition in cultured cells ultracentrifugation according to Lindgren in a Beckman
derived from uninvolved (non-atherosclerotic) human L8-55 ultracentrifuge (Beckman Instruments Inc., Palo
aortic intima. [13] LDL from diabetic patients was Alto, CA) using Type 50Ti fixed angle rotor operated at
subdivided into two fractions by lectin chromatography 40,000 g at 10 ºC, and sterilized by filtration (pore size,
on Ricinus communis agarose, wherein bound 0.45 μm). The LDL preparations were dialyzed against
(desialylated) LDL showed substantial dissimilarity 2,000 volumes of phosphate buffered saline (PBS) at
with non-bound (native) LDL with respect to chemical pH 7.4, overnight at 4 ºC. LDL was subfractionated into
composition and atherogenic properties, i.e. it was two fractions [non-bound (sialylated) LDL and bound
just a fraction of in vivo modified LDL presumably Table 1: Demographic findings and subject characteristics
responsible for lipid accumulation in cultured cells. [13,14] of study groups
Healthy Type 1 diabetic Type 2 diabetic
In the past few years, it was demonstrated that even Characteristic subjects patients patients
in healthy individuals, LDL is heterogeneous in size Gender, M/F 4:6 4:6 5:5
and hydrated density, and the presence of small dense Age, years 32.3 (2.1) 46.0 (17.7) 56.3 (3.5)*
LDL (sdLDL) in blood is associated with a higher Diabetes, years - 24.7 (17.0) 16.0 (6.1)
risk of clinical manifestations of atherosclerosis. [15-17] Glycemia, mmol/L 4.6 (0.3) 9.1 (2.1)* 11.3 (1.8)*
We have shown that multiple-modified atherogenic TG, mmol/L 1.6 (0.2) 1.7 (0.6) 2.2 (0.4)
LDL occurring in blood of atherosclerotic patients is Cho, mmol/L 4.7 (0.2) 5.2 (1.0) 5.5 (0.8)
characterized also by increased hydrated density, and HDL-Cho, mmol/L 1.3 (0.1) 1.4 (0.2) 1.3 (0.3)
therefore may be easily regarded as sdLDL. [18]
*Significant difference from healthy subjects, P < 0.05. TG: plasma
triglycerides; Cho: plasma cholesterol; HDL-Cho: plasma high-
This study was undertaken to obtain more information density lipoprotein-cholesterol
30 Vessel Plus ¦ Volume 1 ¦ March 31, 2017