Association between lipoprotein-associated phospholipase A2 gene polymorphism and coronary artery disease in the Chinese Han population

The role of the lipoprotein-associated phospholipase A(2) gene (PLA2G7) in atherosclerosis remains controversial. We investigated the frequency of single-nucleotide polymorphisms (SNPs) of PLA2G7 (rs16874954 and rs1051931) and their association with coronary artery disease (CAD) in a cohort of CAD patients (n= 806) and age-matched healthy controls (n= 482) in the Chinese Han population. The VF and FF genotype of rs16874954 was significantly more frequent in the CAD patients (13.5%) than in the controls (9.3%, P= 0.024). The association remained after adjustment for age, gender, body mass index, smoking status, history of diabetes, positive family history of CAD, high-density lipoprotein cholesterol, and triglyceride (OR = 1.922; 95% CI [1.146-3.224]; P= 0.013). There was no significant difference in the frequency of any genotype of rs1051931 between the two groups. However, the frequency of the allele V379 was significantly greater in CAD patients with a history of myocardial infarction (MI) than in those without a history of MI (18.7% and 14.8%, P= 0.038). We conclude that there is significant association between the rs16874954 mutation and CAD in the Chinese Han population. The expression of rs1051931 variant in CAD patients may entail increased risk of MI.     

The association among lipoprotein-associated phospholipase A2 levels, total antioxidant capacity and arousal in male patients with OSA

Background: The mechanisms of the increased cardiac and vascular events in patients with OSA are not well understood. Arousal which is an important component of OSA was associated with increased sympathetic activation and electrocardiographic changes which prone to arrhythmias. We planned to examine the association among arousal, circulating Lp-PLA2 and total antioxidant capacity in male patients with OSA.Methods: Fifty male patients with newly diagnosed OSA were enrolled the study. A full-night polysomnography was performed and arousal index was obtained. Lp-PLA2 concentrations were measured in serum samples with the PLAC Test. Total antioxidant capacity in patients was determined with Antioxidant Assay Kit.Results: Arousal was positively correlated with LP-PLA2 levels (r=0.43, p=0.002) and was negatively correlated with total antioxidant capacity (r= -0.29, p=0.04). Elevated LP-PLA2 levels and decreased total antioxidant activities were found in the highest arousal quartile compared with the lowest and 2nd quartiles (p=0.02, p=0.05, respectively). LP-PLA2 was an independently predictor of arousal index in regression model (β=0.357, p=0.002)Conclusions: This study demonstrated a moderate linear relationship between arousal and LP-PLA2 levels. Also, total antioxidant capacities were decreased in the higher arousal index. Based on the study result, the patients with higher arousal index may be prone to vascular events.     

Oxidized phospholipids and lipoprotein-associated phospholipase A2 as important determinants of Lp(a) functionality and pathophysiological role

Lipoprotein(a) [Lp(a)] is composed of a low density lipoprotein (LDL)-like particle to which apolipoprotein (a) [apo(a)] is linked by a single disulfide bridge. Lp(a) is considered a causal risk factor for ischemic cardiovascular disease (CVD) and calcific aortic valve stenosis (CAVS). The evidence for a causal role of Lp(a) in CVD and CAVS is based on data from large epidemiological databases, mendelian randomization studies, and genome-wide association studies. Despite the well-established role of Lp(a) as a causal risk factor for CVD and CAVS, the underlying mechanisms are not well understood. A key role in the Lp(a) functionality may be played by its oxidized phospholipids (OxPL) content. Importantly, most of circulating OxPL are associated with Lp(a); however, the underlying mechanisms leading to this preferential sequestration of OxPL on Lp(a) over the other lipoproteins, are mostly unknown. Several studies support the hypothesis that the risk of Lp(a) is primarily driven by its OxPL content. An important role in Lp(a) functionality may be played by the lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzyme that catalyzes the degradation of OxPL and is bound to plasma lipoproteins including Lp(a). The present review article discusses new data on the pathophysiological role of Lp(a) and particularly focuses on the functional role of OxPL and Lp-PLA2 associated with Lp(a)     

超敏C反应蛋白,脂蛋白相关磷脂酶A2及D-二聚体与冠心病患者相关性研究的临床意义

目的 探讨冠心病患者的脂蛋白相关磷脂酶A2(1 ipoprotein associated phospholipase A2,LpPLA2)、超敏C反应蛋白(hypersensitive C reactive protein,hs-CRP)和D-二聚体的相关性情况,从而为临床提供更多的参考价值.方法 选择2014年1月至2016年1月期间在荷泽市立医院急诊就诊的150例冠心病患者作为观察组,并取同时期的130例健康志愿者作为对照组,对入组者的血清Lp-PLA2、hsCRP以及D-二聚体进行检测.同时对其低密度脂蛋白(low density lipoprotein,LDL)、肌钙蛋白(Cardian troponin I,TNI)、肌红蛋白(myoglobin,Myo)、肌酸激酶同工酶(creatine kinase isoenzyme,CK-MB)进行检测.结果 观察组患者的Lp-PLA2、hs-CRP以及D-二聚体水平分别是(43.62±13.23) g/L、5.09 mg/L、173.0 mg/L,明显高于对照组志愿者的(21.49±7.63) g/L、2.61 mg/L、68.0 mg/L,差异有统计学意义(P＜0.05).观察组的Lp-PLA2与LDL密切相关,并和冠脉病变的支数相关;D-二聚体和hs-CRP相关,同时和心功能等级相关.结论 Lp-PLA2主要和LDL等脂类代谢以及冠脉病变的程度密切相关,hs-CRP则是和D-二聚体水平以及心肌损伤标志物有密切关联,说明了炎症和血栓、心肌损伤有关.心功能降低容易导致D-二聚体水平升高从而诱发血栓.因此,对于冠心病患者,可以通过Lp-PLA2、hs-CRP以及D-二聚体水平指标来预测其预后情况.     

Activity of phospholipase A2 with different localization in liposomes

Damages to liposomal membranes resulted from intensification of lipid peroxidation with iron ions in the presence of ascorbate or treatment with the membrane disintegrator tetrachloromethane led to activation of phospholipase A2, which depended on the enzyme localization in liposomes. Activity of phospholipase A2 located on the inner liposome surface increased less significantly compared to the enzyme bound to the outer surface.     

Antibacterial effects of human group IIA and group XIIA phospholipase A2 against Helicobacter pylori in vitro

Group IIA phospholipase A2 (PLA2-IIA) is an enzyme which has important roles in inflammation and infection. Recently, a novel human secretory PLA2 called group XIIA PLA2 (PLA2-XIIA) has been identified. Both PLA2-IIA and PLA2-XIIA are bactericidal against Gram-positive bacteria like many other secretory PLA2s. However, PLA2-XIIA is the only known PLA2 displaying significant bactericidal activity against the Gram-negative bacterium Escherichia coli. We examined the antibacterial properties of recombinant human PLA2-IIA and PLA2-XIIA against Helicobacter pylori, a Gram-negative bacterium, in vitro. PLA2-IIA was not bactericidal against H. pylori, whereas PLA2-XIIA effectively killed H. pylori at a concentration of 50 microg/ml but was not bactericidal at concentrations of 0.5 microg/ml and 5 microg/ml.     

蛇血清分泌型磷脂酶A2抑制剂防治人炎症的生物信息学分析

目的 比较人和蛇毒分泌型磷脂酶A2(sPLA2)结构相似性,分析蛇血清磷脂酶A2抑制剂(PLI)对sPLA2特异性抑制的结构与功能关系,评价蛇血清PLI对人炎症的抑制作用.方法 用Clustal W2对人和五步蛇sPLA2氨基酸序列进行多重序列比对.用Swiss-model对各种sPLA2的空间结构进行同源建模预测,并...     

联合检测血浆脂蛋白相关磷脂酶A2、降钙素原和C反应蛋白在急性脑梗死的临床诊断价值

目的 通过联合检测人血浆脂蛋白相关磷脂酶A2、降钙素原和C反应蛋白水平,分析它们对急性脑梗死的临床诊断价值.方法 选取2014年6月至2014年12月间住院脑卒中病人128例作为研究对象,并选取46例健康体检者作为对照组,用酶联免疫吸附实验(ELISA)检测其血浆脂蛋白相关磷脂酶A2(Lp-PLA2)含量,罗氏P800生化仪检测血清中C反应蛋白(CRP)含量,免疫比浊法检测降钙素原(PCT)水平,将急性脑梗死组与正常组相关指标比较后进行Logistic多元回归分析,绘制ROC曲线,比较各指标的预测价值.结果 与正常对照组水平比,Lp-PLA2、PCT及CRP水平在急性脑梗死患者不同梗死面积分组中,差异均有统计学意义(P＜0.05).经多元Logistic回归分析筛选出3个的变量,分别为Lp-PLA2、PCT和CRP,OR值分别为2.35、1.85、1.61,曲线下面积(AUC)分别为0.82、0.80、0.82.Lp-PLA2+ PCT+ CRP的预测作用最好,AUC为0.88.结论 Lp-PLA2+ PCT+ CRP组合对急性脑梗死的诊断价值最高,临床工作中应重视这些指标,对Lp-PLA2、PCT和CRP联合升高的患者尤其需要注意,可着重考虑急性脑梗死的可能,尽早做出诊断.     

Expression of group XIIA phospholipase A2 in human digestive organs

Cellular distribution of group XIIA phospholipase A₂ (GXIIA PLA₂) was studied in human digestive organs by immunohistochemistry. GXIIA PLA₂ protein was detected in epithelial cells of normal gastrointestinal tract, gallbladder and pancreatic acinar cells. The GXIIA PLA₂ protein was evenly distributed in the cytoplasm in contrast to secretory granular distribution of GIB PLA₂ and GIIA PLA₂ in pancreatic acinar cells and small intestinal Paneth cells respectively. Epithelial cells of intestinal glands in Crohn's disease and ulcerative colitis expressed abundant GXIIA PLA₂, whereas inflammatory cells were devoid of the enzyme protein. Tumour cells in colonic adenomas and carcinomas and pancreatic ductogenic carcinomas expressed GXIIA PLA₂ protein at varying intensity levels. The putative functions of GXIIA PLA₂ remain to be investigated and its role in healthy and diseased digestive organs can only be speculated on at present.     

急性脑梗死患者血清脂蛋白相关磷脂酶A2、超敏C反应蛋白及D-二聚体水平

目的:检测分析急性脑梗死患者血清脂蛋白相关磷脂酶A2(Lp-PLA2)、超敏C反应蛋白(hs-CRP)及D-二聚体(D-Dimer)水平变化及临床意义。方法:急性脑梗死患者105例(急性脑梗死组),同期体检健康人群100例(健康对照组)。平行检测两组血清Lp-PLA2、hs-CRP及D-Dimer含量,比较不同组及不同程度脑梗患者上述指标水平的差异。结果:急性梗死组血清Lp-PLA2、hs-CRP及D-Dimer含量明显高于健康对照组(P<0.01),且各指标水平变化呈显著正相关(r分别为0.323,0.599,0.283,P均<0.01)。重度梗死组血清Lp-PLA2、hs-CRP及D-Dimer水平明显高于轻度和中度梗死组(P<0.05)。血清Lp-PLA2、hs-CRP及D-Dimer含量与急性脑梗死患者病情严重程度均呈高度正相关(r分别为0.721,0.623,0.718,P均<0.01)。结论:检测急性脑梗死患者血清Lp-PLA2、hs-CRP及D-Dimer水平,对临床诊断有一定参考价值。     

Functional impairment of two novel mutations detected in lipoprotein-associated phospholipase A2 (Lp-PLA2) deficiency patients

Plasma lipoprotein-associated phospholipase A2 (Lp-PLA2), also known as platelet-activating factor (PAF) acetylhydrolase (PAF-AH), is a member of the serine-dependent class of A2 phospholipases that hydrolyze sn2-ester bonds of fragmented or oxidized phospholipids at sites where atherosclerotic plaques are forming. Most circulating Lp-PLA2 is bound to low-density lipoprotein (LDL) particles in plasma and the rest to high-density lipoprotein (HDL). Deficiency of Lp-PLA2 is a predisposing factor for cardiovascular diseases in the Japanese population. We describe here two novel mutations of the gene encoding Lp-PLA2, InsA191 and I317N in Japanese subjects. The first patient, with partial Lp-PLA2 deficiency, was heterozygous for the InsA191 mutation; macrophages from this patient secreted only half the normal amount of Lp-PLA2 in vitro. The other patient, who showed complete Lp-PLA2 deficiency, was a compound heterozygote for the novel I317N mutation and a common V279F mutation; macrophages from that patient failed to secrete any Lp-PLA2. Measurement of Lp-PLA2 mass, activity and Western blotting verified impaired production and secretion of the enzyme after transfection of mutant construct into COS-7 cells. These results indicated that both novel mutants, InsA191 and I317N, impair function of the Lp-PLA2 gene.     

Progesterone regulates IL12 expression in pregnancy lymphocytes by inhibiting phospholipase A2

PROBLEM: Progesterone-induced blocking factor (PIBF) is one of the pathways that mediate the immunological effects of progesterone. PIBF inhibits natural killer (NK) cytotoxic activity. Recently we showed that neutralization of PIBF results in an increased interleukin (IL)-12 expression, which is corrected by cyclooxygenase inhibitors. As exogenous arachidonic acid (AA) voids the NK blocking effect of PIBF, it is likely that PIBF acts before the level of the cyclooxygenase enzyme. Therefore in this study we investigated the effect of PIBF neutralizing antibody and simultaneous phospholipase A2 inhibitor quinacrine (Q) treatment on IL-12 production. METHODS: Pregnancy lymphocytes were treated with anti-PIBF antibody or lipopolysaccharide (LPS) as a positive control, in the presence or absence of Q. IL-12 expression by PBMC was detected by immunocytochemistry. RESULTS: Neutralization of PIBF as well as LPS treatment resulted in an increased IL-12 expression, which was corrected by simultaneous Q treatment. Pre-treatment of lymphocytes with progesterone prevented the stimulating effect of LPS on IL-12 production. CONCLUSION: Progesterone binding of the lymphocytes is followed by the release of PIBF that inhibits AA release. The subsequent block of prostaglandin synthesis reduces IL-12 production and results in a lowered cytotoxic NK activity, which may contribute to a normal pregnancy outcome.     

Increased specificity of diagnostic tests with recombinant major bee venom allergen phospholipase A2

Background In diagnosis of type I allergy recombinant allergens have potential advantages over conventional allergenic extracts, both regarding specificity and reproducibility. Objectives We therefore decided to study honey bee venom (BV) and its major allergen phospholipase A2 (PLA) in native and recombinant form for diagnosis of bee sting allergy. Method We investigated 85 patients with a history of a recent systemic allergic bee sting reaction and positive intracutaneous skin test to BV, and 21 controls with no history of allergic bee sting reaction and negative skin test to BV. Intracutaneous skin tests and determination of specific IgE by ImmunoCAP^R to BV, native PLA (nPLA) and recomhinant PLA (rPLA) were done in all patients and controls. Results In skin testing 84 (99%) of the 85 patients reacted to nPLA and 81 (95%) to rPLA, while none of the 21 controls was positive with nPLA or rPLA. Specific serum IgE to BV could be detected in 82 of the patients (96%), to nPLA in 73 (86%) and to rPLA in 66 (78%). Four (19%) of the controls had a positive CAP to BV, one (4.8%) to nPLA and none to rPLA. Analysis of discordant results in CAP showed, that most patients with specific IgE to BV, but not to nPLA and rPLA, had positive skin tests to both PLA preparations and low levels of BV specific IgE. Patients with specific IgE to nPLA but not to rPLA were usually sensitized to minor allergens of BV which contaminated the commercial nPLA. Conclusions PLA is the major allergen in BV. While diagnostic tests with BV are more sensitive, the specificity of tests with PLA, especially rPLA is clearly increased as compared with BV.     

The phospholipase A2 inhibitor quinacrine prevents increased immunoreactivity to cytoplasmic phospholipase A2 (cPLA2) and hydroxynonenal (HNE) in neurons of the lateral septum following fimbria-fornix transection

The distribution of cytoplasmic phospholipase A₂ (cPLA₂), 4-hydroxynonenal (HNE), and choline acetyltransferase (ChAT) was studied in the septum and hippocampus of rats at various time intervals after fimbria-fornix (FF) transection. Very little cPLA₂ or HNE immunoreactivity was observed in the normal medial or lateral septum, whereas a large increase in immunoreactivity with both antibodies was observed in the lateral septum one week after transection. The increase in cPLA₂ or HNE staining in the lateral septum after FF transection was completely blocked by intraperitoneal injections (once daily) of a lipophilic inhibitor of phospholipase A₂, quinacrine (5 mg/kg), showing the importance of phospholipase A₂ in generation of arachidonic acid, which is a target for lipid peroxidation and formation of 4-hydroxynonenal. Quinacrine prevented not only a rise in HNE immunoreactivity, but also a rise in cPLA₂ immunoreactivity, showing that cPLA₂ expression itself is depressed by the drug, in addition to its well-known effect on blocking the catalytic action of phospholipase A₂. No increase in cPLA₂ or HNE immunoreactivity was observed in neurons of the medial septum after fimbria-fornix transection, even though these showed a decrease in ChAT staining after the lesion. This suggests that glutamate released from transected hippocamposeptal afferents or increased activity of the supramammillary area following FF transection may lead to increased cPLA₂ and HNE immunreactivity, whereas retrograde degeneration in neurons may not. We conclude that there is free-radical damage, as evidenced by HNE formation in neurons of the lateral septum after fimbria-fornix transection, and that this increase in HNE is dependent on phospholipase A₂ activity. Electronic Publication     

Group IIA phospholipase A2 as a prognostic marker in prostate cancer: relevance to clinicopathological variables and disease‐specific mortality

Group IIA Phospholipase A₂ (PLA2‐IIA), a key enzyme in arachidonic acid and eicosanoid metabolism, participates in a variety of inflammatory processes but possibly also plays a role in tumor progression in vivo. Our aim was to determine the mRNA and protein expression of PLA2‐IIA during prostate cancer progression in localized and metastatic prostate tumors. We evaluated the prognostic significance of PLA2‐IIA expression in biochemical recurrence, clinical recurrence and disease‐specific survival after surgical treatment. The expression of PLA2‐IIA was examined by immunohistochemistry and chromogenic in situ hybridization in tissue microarrays of radical prostatectomy specimens and advanced/metastatic carcinomas. The expression data were analyzed in conjunction with clinical follow‐up information and clinicopathological variables. The mRNA and protein expression of PLA2‐IIA was significantly increased in Gleason pattern grade 2–4 carcinomas compared with benign prostate (p‐values 0.042–0.001). In metastases, the expression was significantly lower than in local cancers (p=0.001). The PLA2‐IIA expression correlated positively with Ki‐67 and α‐methylacyl CoA racemase (AMACR) expression. The prognostic evaluation revealed decreased PLA2‐IIA protein expression among patients who had died of prostate cancer. In conclusion, PLA2‐IIA expression is increased in carcinoma when compared with benign prostate. However, metastatic carcinoma showed decreased expression of PLA2‐IIA when compared with primary carcinomas. PLA2‐IIA may serve as a marker for highly proliferating, possibly poorly differentiated prostate carcinomas. The protein expression of PLA2‐IIA may be diminished in patients who consequently die of prostate cancer.     

Involvement of carbohydrate on phospholipase A2, a bee-venom allergen, in in vivo antigen-specific IgE synthesis in mice.

BACKGROUND: Carbohydrates on allergens are known to be important for allergenicity. However, most findings have been made with epitope analysis. In this study, we investigated the involvement of N-glycan on phospholipase A2 (PLA2), the major allergen of honeybee venom, in in vivo synthesis of specific IgE in mice. METHODS: CBA/J and C57BL/6 mice were sensitized intranasally with either native or deglycosylated PLA2 in the absence of adjuvant. After repeated sensitization, serum Ab titers against PLA2 were determined. PLA2 was deglycosylated chemically with anhydrous trifluoromethanesulfonic acid (TFMS). RESULTS: CBA/J mice showed PLA2-specific IgE production after repeated sensitization with native PLA2. They also produced PLA2-specific IgG1 predominantly, suggesting that Th2-type Ab production was induced. When we used deglycosylated PLA2 as a competitor in ELISA for detecting PLA2-specific IgE, deglycosylated PLA2 completely inhibited the binding between native PLA2 and IgE. Deglycosylated PLA2 had the same potential for inducing specific IgE synthesis as native PLA2, since sensitization with deglycosylated PLA2 also elicited IgE production in CBA/J mice. CONCLUSIONS: These results suggest that carbohydrate on PLA2 is less important than previously thought not only as a dominant IgE epitope but also in synthesis of PLA2-specific IgE in vivo.     

脂蛋白相关磷脂酶A2对预测冠心病事件的临床价值

目的：探讨脂蛋白相关磷脂酶A2（Lp-PLA2）对预测国人冠心病（CHD）事件的临床价值。方法：通过检测108例CHD患者、40例健康体检者血液中Lp-PLA2、低密度脂蛋白胆固醇（LDL）的含量情况。结果：急性心肌梗死（AMI）组、不稳定型心绞痛（UAP）组、稳定型心绞痛（SAP）组和对照组,各组间Lp-PLA2、LDL含量呈现明显的梯度差异（均P〈0.05）。经线性相关分析,血浆Lp-PLA2与LDL水平呈正相关（P〈0.05）。结论：Lp-PLA2可作为国人的CHD事件的独立预测因子;血浆Lp-PLA2与LDL含量密切相关。     

Intrinsic phospholipase A2 activity of adeno-associated virus is involved in endosomal escape of incoming particles

The unique region of the VP1 capsid protein of adeno-associated viruses (AAV) in common with autonomously replicating parvoviruses comprises a secreted phospholipase A2 (sPLA2) homology domain. While the sPLA2 domain of Minute Virus of Mice has recently been shown to mediate endosomal escape by lipolytic pore formation, experimental evidence for a similar function in AAV infection is still lacking. Here, we explored the function of the sPLA2 domain of AAV by making use of the serotype 2 mutant ⁷⁶HD/AN. The sPLA2 defect in ⁷⁶HD/AN, which severely impairs AAV's infectivity, could be complemented in trans by co-infection with wild-type AAV2. Furthermore, co-infection with endosomolytically active, but not with inactive adenoviral variants partially rescued ⁷⁶HD/AN, providing the first evidence for a function of this domain in endosomal escape of incoming AAV particles.