Characterization of angiotensin II-receptor subtypes in podocytes

Glomerular podocytes play a key role in maintaining the integrity of the glomerular filtration barrier. This function may be regulated by angiotensin II (Ang II) through activation of cell-surface receptors. Although studies suggest that podocytes express receptors for Ang II, the Ang II binding site has not been characterized with radioligand binding techniques. We therefore used iodine 125-labeled Ang II to monitor Ang II-receptor density during differentiation of a mouse podocyte cell line. Scatchard analyses of equilibrium binding data revealed a single class of high-affinity binding sites (dissociation constant approximately 3 nmol/L) in both differentiated and nondifferentiated cells. During differentiation, the density of Ang II-receptor sites increased roughly 15-fold in differentiated podocytes (maximal density of specific binding sites 881 fmol/mg protein) compared with that in nondifferentiated cells (52 fmol/mg protein; P<.005). Glomerular podocytes expressed messenger RNA for AT1A, AT1B, and AT2 receptor subtypes, and competitive binding studies found that differentiated podocytes expressed mostly AT1 receptors (approximately 75%) with lesser amounts of AT2 (approximately 25%). Up-regulation of Ang II-receptor number was associated with increased Ang II-receptor responsiveness, as evidenced by enhanced Ang II-stimulated inositol phosphate (IP) generation and incorporation of tritiated thymidine. Both [3H]thymidine incorporation and IP generation were mediated by AT1-receptor activation. These data suggest that glomerular podocytes express a high-affinity binding site for Ang II with pharmacologic characteristics of both AT1 and AT2 receptors. This receptor site is up-regulated during podocyte differentiation, and receptor activation induces both IP generation and DNA synthesis by AT1-dependent mechanisms. We speculate that activation of podocyte Ang II receptors contributes to glomerular damage in disease states.     

An effect of moderate hepatic impairment on the pharmacokinetics and safety of darapladib

Aim/MethodsThis was a phase 1, open label, non-randomized study designed to assess the pharmacokinetics and safety/tolerability of 10 consecutive once daily 40 mg oral doses of darapladib in subjects with moderate hepatic impairment (n = 12) compared with matched healthy volunteers (n = 12).ResultsFor total darapladib, a small increase in total and peak exposure was observed in the subjects with moderate hepatic impairment compared with the subjects with normal hepatic function. The area under the plasma concentration−time curve during a dosing interval of duration τ (AUC(0,τ), geometric mean 223 ng ml⁻¹ h [90% CI 158, 316 ng ml⁻¹h], in moderate hepatic impaired subjects, vs. geometric mean 186 ng ml⁻¹h [90% CI 159, 217 ng ml⁻¹h], in healthy subjects) and maximum concentration (C_max) were 20% and 7% higher, respectively, in the subjects with moderate hepatic impairment than in the healthy control subjects and there was no change in time to maximum concentration (t_max). Protein binding was performed to measure the amount of unbound drug vs. bound. Steady-state was achieved by day 10 for darapladib and its metabolites (M4, M3 and M10). Darapladib was generally well tolerated, with adverse events (AEs) reported by seven subjects in the hepatic impairment group and three subjects in the healthy matched group (five and one of which were drug-related AEs, respectively). The most common AEs were gastrointestinal. These AEs were mostly mild to moderate and there were no deaths, serious AEs or withdrawals due to AEs.ConclusionsThe results of this phase 1 study show that darapladib (40 mg) is well tolerated and its pharmacokinetics remain relatively unchanged in patients with moderate hepatic impairment.     

人Ⅰ型磷脂酶A_2的N末端衍生多肽PLA_2N_(1-15)的杀菌活性研究

目的:观察人Ⅰ型磷脂酶A2(PLA2)的N末端衍生多肽PLA2N1-15对不同细菌的体外杀菌活性。方法:以人Ⅰ型PLA2N末端的15个氨基酸残基为模板,合成多肽PLA2N1-15。采用琼脂铺板计数法,记录并计算不同质量浓度(1 000、250、62.5、15.625μg/ml)的PLA2N1-15对革兰阳性(G+)菌(金黄色葡萄球菌、粪肠球菌、枯草芽孢杆菌)和革兰阴性(G-)菌(大肠埃希菌、铜绿假单胞菌、变形杆菌)的杀菌率。结果:15.625、62.5、250、1 000μg/ml的PLA2N1-15对G+菌的杀菌率分别为10%¹9%、36.55%19%、36.55%⁸9.73%、83%89.73%、83%¹00%、96%100%、96%¹00%,对G-菌的杀菌率分别为8.86%100%,对G-菌的杀菌率分别为8.86%²2.63%、21.61%22.63%、21.61%⁴0.55%、40%40.55%、40%⁸3%、87%83%、87%⁹3%。结论:高浓度PLA2N1-15对G+和G-均具有较强的杀菌活性,特别是对G+。     

慢性HBV感染者外周血PNPLA3/PRKAA1基因多态性与肝硬化发生关系研究*

目的 探讨Patatin样磷脂酶域蛋白3(PNPLA3)和腺苷活化蛋白激酶α1亚基(PRKAA1)基因多态性与感染HBV后肝硬化发生的关系。方法 2016年1月～2021年7月我院诊治的乙型肝炎肝硬化患者101例和同期慢性无症状HBV携带者90例,采用聚合酶链反应-限制性片段长度多态性检测血浆PNPLA3基因rs738409、rs139047、rs2294919和PRKAA1基因rs3792822、rs10036575、rs154268位点多态性,应用Logistic回归分析疾病风险关联。结果 肝硬化组PNPLA3基因rs139047位点AA、GA、GA基因型比率分别为18.8%、51.5%和29.7%,与HBV携带者的16.7%、51.1%和32.2%比,无显著性差异(P＞0.05),rs2294919位点CC、TC、TT基因型比率分别为41.6%、45.5%和12.9%,与HBV携带者的38.9%、50.0%和11.1%比,无显著性差异(P＞0.05);PRKAA1基因rs3792822位点GG、GA、AA基因型比率分别为54.5%、38.6%和6.9%,与HBV携带者的55.6%、37.8%和6.7%比,无显著性差异(P＞0.05),rs154268位点CC、CT、TT基因型比率分别为5.0%、35.6%和59.4%,与HBV携带者的4.4%、34.4%和61.1%比,无显著性差异(P＞0.05);肝硬化组PNPLA3基因rs738409位点GG基因型和等位基因G比率分别为19.8%和44.6%,显著高于HBV携带者的8.9%和29.4%(P＜0.05);肝硬化组PRKAA1基因rs10036575位点CC基因型和等位基因C比率分别为38.6%和63.9%,显著高于HBV携带者的23.3%和45.5%(P＜0.05);经非条件Logistic回归模型分析显示PNPLA3基因rs738409位点GG基因型【OR为1.605(95%CI:1.150～2.239)】和PRKAA1基因rs10036575位点CC基因型【OR值为1.507((95%CI:1.097～2.070)】是影响感染HBV后肝硬化发生的危险基因型。结论 感染HBV后发生肝硬化可能与某些特殊基因有关,研究PNPLA3基因和PRKAA1基因可能有助于阐明其中的分子机制。     

Bariatric surgery in morbidly obese patients improves the atherogenic qualitative properties of the plasma lipoproteins

Objective

The purpose of this study was to evaluate the effect of weight loss induced in morbidly obese subjects by Roux-en-Y gastric bypass bariatric surgery on the atherogenic features of their plasma lipoproteins.

Methods

Twenty-one morbidly obese subjects undergoing bariatric surgery were followed up for up to 1 year after surgery. Plasma and lipoproteins were assayed for chemical composition and lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Lipoprotein size was assessed by non-denaturing polyacrylamide gradient gel electrophoresis, and oxidised LDL by ELISA. Liver samples were assayed for mRNA abundance of oxidative markers.

Results

Lipid profile analysis revealed a reduction in the plasma concentrations of cholesterol and triglycerides, which were mainly associated with a significant reduction in the plasma concentration of circulating apoB-containing lipoproteins rather than with changes in their relative chemical composition. All patients displayed a pattern A phenotype of LDL subfractions and a relative increase in the antiatherogenic plasma HDL-2 subfraction (>2-fold; P < 0.001). The switch towards predominantly larger HDL particles was due to an increase in their relative cholesteryl ester content. Excess weight loss also led to a significant decrease in the plasma concentration of oxidised LDL (∼−25%; P < 0.01) and in the total Lp-PLA2 activity. Interestingly, the decrease in plasma Lp-PLA2 was mainly attributed to a decrease in the apoB-containing lipoprotein-bound Lp-PLA2.

Conclusion

Our data indicate that the weight loss induced by bariatric surgery ameliorates the atherogenicity of plasma lipoproteins by reducing the apoB-containing Lp-PLA2 activity and oxidised LDL, as well as increasing the HDL-2 subfraction.     

The Finding of a Group IIE Phospholipase A2 Gene in a Specified Segment of Protobothrops flavoviridis Genome and Its Possible Evolutionary Relationship to Group IIA Phospholipase A2 Genes

The genes encoding group IIE phospholipase A₂, abbreviated as IIE PLA₂, and its 5'' and 3'' flanking regions of Crotalinae snakes such as Protobothrops flavoviridis, P. tokarensis, P. elegans, and Ovophis okinavensis, were found and sequenced. The genes consisted of four exons and three introns and coded for 22 or 24 amino acid residues of the signal peptides and 134 amino acid residues of the mature proteins. These IIE PLA₂s show high similarity to those from mammals and Colubridae snakes. The high expression level of IIE PLA₂s in Crotalinae venom glands suggests that they should work as venomous proteins. The blast analysis indicated that the gene encoding OTUD3, which is ovarian tumor domain-containing protein 3, is located in the 3'' downstream of IIE PLA₂ gene. Moreover, a group IIA PLA₂ gene was found in the 5'' upstream of IIE PLA₂ gene linked to the OTUD3 gene (OTUD3) in the P. flavoviridis genome. It became evident that the specified arrangement of IIA PLA₂ gene, IIE PLA₂ gene, and OTUD3 in this order is common in the genomes of humans to snakes. The present finding that the genes encoding various secretory PLA₂s form a cluster in the genomes of humans to birds is closely related to the previous finding that six venom PLA₂ isozyme genes are densely clustered in the so-called NIS-1 fragment of the P. flavoviridis genome. It is also suggested that venom IIA PLA₂ genes may be evolutionarily derived from the IIE PLA₂ gene.     

Phospholipase D1 inhibition sensitizes glioblastoma to temozolomide and suppresses its tumorigenicity

Resistance of glioblastoma to the chemotherapeutic compound temozolomide is associated with the presence of glioblastoma stem cells in glioblastoma and is a key obstacle for the poor prognosis of glioblastoma. Here, we show that phospholipase D1 is elevated in CD44^High glioblastoma stem cells and in glioblastoma, especially recurring glioblastoma. Phospholipase D1 elevation positively correlated with the level of CD44 and poor prognosis in glioblastoma patients. Temozolomide significantly upregulated the expression of phospholipase D1 in the low and moderate CD44 populations of glioblastoma stem cells, but not in the CD44^High population in which phospholipase D1 is highly expressed. Phospholipase D1 conferred resistance to temozolomide in CD44^High glioblastoma stem cells and increased their self-renewal capacity and maintenance. Phospholipase D1 expression significantly correlated with levels of temozolomide resistance factors, which were suppressed by microRNA-320a and -4496 induced by phospholipase D1 inhibition. Genetic and pharmacological targeting of phospholipase D1 attenuated glioblastoma stem cell-derived intracranial tumors of glioblastoma using the microRNAs, and improved survival. Treatment solely with temozolomide produced no benefits on the glioblastoma, whereas in combination, phospholipase D1 inhibition sensitized glioblastoma stem cells to temozolomide and reduced glioblastoma tumorigenesis. Together, these findings indicate that phospholipase D1 inhibition might overcome resistance to temozolomide and represents a potential treatment strategy for glioblastoma. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.     

冷冻与石蜡肾活检标本中PLA2R1表达的临床诊断意义比较

目的探讨磷脂酶A2受体1(PLA2R1)在肾脏穿刺的冷冻标本及石蜡标本中的表达,分析不同标本中阳性率的临床病理诊断意义。方法收集2013年1月~2019年2月江门市中心医院行肾脏穿刺患者的标本及临床病理资料,其中同时有肾活检冷冻标本及石蜡标本的患者215例,仅有石蜡标本的患者785例。分别利用免疫荧光及免疫组化法检测PLA2R1在肾活检冷冻和石蜡标本中的表达,并分析PLA2R1表达与临床病理特征的相关性。结果在215例冷冻标本中,PLA2R1阳性率为19.1%;在1000例石蜡标本中,PLA2R1阳性率为32.9%,两组中PLA2R1的阳性率差异有统计学意义(P<0.001)。在冷冻和石蜡标本中,PLA2R1表达与患者性别、年龄及临床分期无关,与病理类型相关。在冷冻和石蜡标本中,PLA2R1阳性均集中于特发性膜性肾病(72.0%和79.8%),但非特发性膜性肾病中,则分别为3.0%和19.4%。结论肾活检冷冻及石蜡标本中PLA2R1表达均与特发性膜性肾病相关,但冷冻标本在特发性膜性肾病诊断中更有价值。