Liang-Yin Ke

Highly electronegative LDL from patients with ST-elevation myocardial infarction triggers platelet activation and aggregation

Platelet activation and aggregation underlie acute thrombosis that leads to ST-elevation myocardial infarction (STEMI). L5-highly electronegative low-density lipoprotein (LDL)-is significantly elevated in patients with STEMI. Thus, we examined the role of L5 in thrombogenesis. Plasma LDL from patients with STEMI (n = 30) was chromatographically resolved into 5 subfractions (L1-L5) with increasing electronegativity. In vitro, L5 enhanced adenosine diphosphate-stimulated platelet aggregation twofold more than did L1 and induced platelet-endothelial cell (EC) adhesion. L5 also increased P-selectin expression and glycoprotein (GP)IIb/IIIa activation and decreased cyclic adenosine monophosphate levels (n = 6, P < .01) in platelets. In vivo, injection of L5 (5 mg/kg) into C57BL/6 mice twice weekly for 6 weeks shortened tail bleeding time by 43% (n = 3; P < .01 vs L1-injected mice) and increased P-selectin expression and GPIIb/IIIa activation in platelets. Pharmacologic blockade experiments revealed that L5 signals through platelet-activating factor receptor and lectin-like oxidized LDL receptor-1 to attenuate Akt activation and trigger granule release and GPIIb/IIIa activation via protein kinase C-α. L5 but not L1 induced tissue factor and P-selectin expression in human aortic ECs (P < .01), thereby triggering platelet activation and aggregation with activated ECs. These findings indicate that elevated plasma levels of L5 may promote thrombosis that leads to STEMI.

Interplay between CRP, Atherogenic LDL, and LOX-1 and Its Potential Role in the Pathogenesis of Atherosclerosis

BACKGROUND Studies have shown that the classic acute-phase protein C-reactive protein (CRP) has proinflammatory effects on vascular cells and may play a causal role in the pathogenesis of coronary artery disease. A growing body of evidence has suggested that interplay between CRP, lectin-like oxidized LDL receptor-1 (LOX-1), and atherogenic LDL may underlie the mechanism of endothelial dysfunction that leads to atherosclerosis. CONTENT We review the biochemical evidence for an association of CRP, LOX-1, and either oxidized LDL (OxLDL) or electronegative L5 LDL with the pathogenesis of coronary artery disease. Artificially oxidized OxLDL has been studied extensively for its role in atherogenesis, as has electronegative L5 LDL, which is present at increased levels in patients with increased cardiovascular risks. OxLDL and L5 have been shown to stimulate human aortic endothelial cells to produce CRP, indicating that CRP is synthesized locally in the endothelium. The ligand-binding face (B-face) of CRP has been shown to bind the LOX-1 scavenger receptor and increase LOX-1 expression in endothelial cells, thereby promoting the uptake of OxLDL or L5 by LOX-1 into endothelial cells to induce endothelial dysfunction. SUMMARY CRP and LOX-1 may form a positive feedback loop with OxLDL or L5 in atherogenesis, whereby increased levels of atherogenic LDL in patients with cardiovascular risks induce endothelial cells to express CRP, which may in turn increase the expression of LOX-1 to promote the uptake of atherogenic LDL into endothelial cells. Further research is needed to confirm a causal role for CRP in atherogenesis.

Suppressor of cytokine signaling 1 gene expression and polymorphisms in systemic lupus erythematosus

With the aim of investigating the role of suppressor of cytokine signaling 1 (SOCS1) in the pathogenesis of systemic lupus erythematosus, 107 patients with systemic lupus erythematosus, 101 healthy controls, and 151 patients with ankylosing spondylitis were enrolled in this study. SOCS1 mRNA level was measured by the method of quantitative real-time polymerase chain reaction. SOCS1 polymorphisms were detected by the polymerase chain reaction/restriction fragment length polymorphisms method. Systemic lupus erythematosus disease activity was evaluated with the SLEDAI. This study showed that the SOCS1 mRNA expression was significantly higher in the patients with systemic lupus erythematosus than in the healthy controls (p = 0.0014). Patients with active systemic lupus erythematosus had a higher expression of SOCS1 mRNA than the patients with inactive systemic lupus erythematosus (p = 0.035). There was no significant difference in the frequencies of the SOCS1-1478CA/del polymorphisms among the patients with systemic lupus erythematosus, healthy controls, and patients with ankylosing spondylitis. The genotype frequency of the SOCS1-1478 polymorphisms in the dominant model (CA/del+del/del versus CA/CA) was significantly decreased in the patients with thrombocytopenia compared with those without thrombocytopenia (pc = 0.035). Moreover, the allele frequency of SOCS1-1478del was also significantly lower in the patients with thrombocytopenia than in those without thrombocytopenia (p c = 0.02). In conclusion, this study demonstrated that the expression of SOCS1 mRNA was significantly increased in patients with systemic lupus erythematosus. Moreover, SOCS1 mRNA levels in patients with active systemic lupus erythematosus were significantly higher than those in the inactive patients. We also found that the systemic lupus erythematosus patients with thrombocytopenia have a lower frequency of SOCS1-1478del compared with patients without thrombocytopenia. Lupus (2010) 19, 696—702.

Chemical composition-oriented receptor selectivity of L5, a naturally occurring atherogenic low-density lipoprotein.

Anion-exchange chromatography resolves human plasma low-density lipoprotein (LDL) into 5 subfractions, with increasing negative surface charge in the direction of L1 to L5. Unlike the harmless L1 to L4, the exclusively atherogenic L5 is rejected by the normal LDL receptor (LDLR) but endocytosed into vascular endothelial cells (ECs) through the lectin-like oxidized LDL receptor-1 (LOX-1). Analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 2-dimensional electrophoresis showed that the protein framework of L1 was composed mainly of apolipoprotein (apo) B100, with an isoelectric point (pI) of 6.620. There was a progressively increased association of additional proteins, including apoE (pI 5.5), apoAI (pI 5.4), apoCIII (pI 5.1), and apo(a) (pI 5.5), from L1 to L5. Liquid chromatography data-independent parallel-fragmentation mass spectrometry (LC/MSE) was used to quantify protein distribution in all subfractions. On the basis of weight percentages, L1 contained 99 % apoB-100 and trace amounts of other proteins. In contrast, L5 contained 60 % apoB100 and substantially increased amounts of apo(a), apoE, apoAI, and apoCIII. The compositional characteristics contribute to L5’s electronegativity, rendering it unrecognizable by LDLR. LOX-1, which has a high affinity for negatively charged ligands, is known to mediate the signaling of proinflammatory cytokines. Thus, the chemical composition-oriented receptor selectivity hinders normal metabolism of L5, enhancing its atherogenicity through abnormal receptors, such as LOX-1.

The Underlying Chemistry of Electronegative LDL’s Atherogenicity

Electronegative low-density lipoprotein (LDL) found in human plasma is highly atherogenic, and its level is elevated in individuals with increased cardiovascular risk. In this review, we summarize the available data regarding the elevation of the levels of electronegative LDL in the plasma of patients with various diseases. In addition, we discuss the harmful effects and underlying mechanisms of electronegative LDL in various cell types. We also highlight the known biochemical properties of electronegative LDL that may contribute to its atherogenic functions, including its lipid and protein composition, enzymatic activities, and structural features. Given the increasing recognition of electronegative LDL as a potential biomarker and therapeutic target for the prevention of cardiovascular disease, key future goals include the development of a standard method for the detection of electronegative LDL that can be used in a large-scale population survey and the identification and testing of strategies for eliminating electronegative LDL from the blood.

Increased Expression of Suppressor of Cytokine Signaling 1 mRNA in Patients With Rheumatoid Arthritis

The objective of this study was to investigate the associations between suppressor of cytokine signaling 1 (SOCS1) mRNA expression and SOCS1 polymorphisms with the development of rheumatoid arthritis (RA). One hundred and eighty‐one patients with RA and 96 healthy controls were enrolled in this study. The SOCS1 mRNA level in peripheral blood mononuclear cells (PBMCs) was detected by quantitative real‐time polymerase chain reaction. SOCS1 polymorphisms were determined by the polymerase chain reaction/restriction fragment length polymorphism method. We found that the expression of SOCS1 mRNA in PBMCs was significantly greater in patients with RA than in healthy controls. There were no significant differences in the expression of SOCS1 mRNA among patients with different disease activities. The increment in SOCS1 mRNA after stimulation with various cytokines was slightly lower in the patients with RA than in the healthy controls. This study also demonstrated that the SOCS1 polymorphisms were not associated with susceptibility to RA. In conclusion, the expression of SOCS1 mRNA in PBMCs is higher in patients with RA than in healthy controls. The increment in SOCS1 mRNA expression in PBMCs after stimulation with different cytokines seems to be lower in patients with RA than in healthy controls.

Vascular Progenitor Cells in Diabetes Mellitus: Roles of Wnt Signaling and Negatively Charged Low-Density Lipoprotein

See related article, pages 1095–1102 Over the centuries, diabetes mellitus–associated ischemic ulcers have driven physicians to continue to improve their skills in healing the ulcers to prevent devastating complications.1 Unfortunately, extremity amputation still remains the outcome in many cases. The recent development of vascular progenitor cell (PC) transplantation aimed at enhancing angiogenesis and wound healing may, however, provide new hope in the treatment of this old ailment.2,3 In this issue of Circulation Research , Barcelos et al show in a murine diabetes mellitus model that topical transplantation of human fetal CD133+ PCs significantly accelerates the healing of skin wounds on ischemic hind limbs.4 Their data suggest that the reparative angiogenesis is mediated by the wingless (Wnt) signaling pathway. The prominin-1 (PROM1)/CD133 gene encodes a pentaspan transmembrane glycoprotein expressed in a variety of stem cells, including hematopoietic stem cells, endothelial PCs (EPCs), and neuronal/glial stem cells.5,6 By suppressing further differentiation, PROM1 helps these cells maintain their stem cell properties. Mutations in PROM1 may result in retinitis pigmentosa,7 and its overexpression is also associated with cancer formation.8 In view of this cancer potential, overstimulation of CD133+ cells may also lead to unwanted consequences. Additionally, that human fetal CD133+ cells are not easily accessible …

MOLECULAR EPIDEMIOLOGY OF DENGUE VIRUS SEROTYPE 2 IN THE TAIWAN 2002 OUTBREAK WITH ENVELOPE GENE AND NONSTRUCTURAL PROTEIN 1 GENE ANALYSIS

The genetic relationships among dengue virus serotype 2 (DEN‐2) isolates from the Taiwan 2002 epidemic were studied by sequence analysis of the envelope (E) and nonstructural protein 1 (NS1) genes. A 0–0.4% divergence among 10 isolates revealed an epidemic strain in the outbreak. Phylogenetic study demonstrated that the 2002 Taiwan isolates were of the Cosmopolitan genotype, which is different from the Asian 1 and Asian 2 genotypes of Taiwan DEN‐2 isolates from 1981 to 1998 and the American/Asian genotype of 2005 Taiwan isolates. Although grouping results from both E and NS1 gene sequence analyses were the same, the usage of the NS1 gene as a sequence analysis target has not been validated for the lower bootstrap support values of branches in the phylogenetic tree. Our result showing the same genotype changes in Taiwan and Philippines isolates suggests strain transfer of DEN‐2 to nearby countries resulting in the same trend of genotype change.

High seroprevalence of human herpesvirus 8 infection in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that is associated with genetic and environmental factors and microbial infection. With respect to microbial infection, the Epstein‐Barr virus (EBV) has been a widely discussed issue in recent decades. Human herpesvirus 8 (HHV‐8) belongs to the same γ‐herpesvirus subfamily as EBV and is closely related to it. Until now, only one paper has reported the prevalence of HHV‐8 infection in SLE patients. The goal of this study was to detect the prevalence of HHV‐8 infection in SLE patients to elucidate the relationship between HHV‐8 and SLE.

The role of electronegative low-density lipoprotein in cardiovascular diseases and its therapeutic implications

Cardiovascular disease (CVD) is a health problem of great concern to both the public and medical authorities. Low-density lipoprotein (LDL) has been reported to play an important role in both the development and progression of CVD, but studies are underway to determine how LDL exerts its effects. In recent years, it has been found that LDL has several subfractions, each of which affects endothelial function differently; L5, the most electronegative fraction, has been shown to be unique in that it induces an atherogenic response. This review examines the current knowledge concerning the relationships between L5 and CVD and highlights the role of L5 in the pathophysiology of CVD, especially with regards to atherosclerosis.