出血性蛇毒诱导血管内皮细胞凋亡的成分及作用机制研究进展

出血性蛇毒能专一性诱导血管内皮细胞(vascular endothelial cells，VEC)凋亡，研究人员已从中分离出5种VEC凋亡诱导成份，其中2种为L—aa氧化酶类，3种属于金属蛋白酶／解整联蛋白家族。研究证实前者可通过氧化VEC细胞膜上的L—leu产生H2O2而诱导其凋亡，后者则通过干扰膜整联蛋白与其配体的结合而使VEC凋亡。在由蛇毒诱导的VEC凋亡过程中，p53和bcl-2基因表达增加，且bcl-2的mRNA被剪辑成2条。已证实锚定依赖性信号分子αvβ3和磷脂信号分子PC-PLC参与该过程的信号转导。对该领域进一步研究，有望从蛇毒中纯化出或人工构建出专一地诱导肿瘤血管细胞凋亡的成分。本文总结了出血性蛇毒方面的研究进展。     

Importance of Metalloproteinases and Macrophages in Viper Snake Envenomation–Induced Local Inflammation

The inflammatory action of jararhagin, a hemorrhagic metalloproteinase from Bothrops jararaca venom, was studied in mice using dorsal air pouches. The injection of the toxin in 6-day-old air pouches resulted in a leukocyte accumulation comparable to that induced by LPS and whole venom. Polymorphonuclear and mononuclear cells were present in this infiltrate, with a predominance of neutrophils. Treatment of jararhagin with 1,10-phenantroline abolished its proteolytic activity and reduced the pro-inflammatory effect in approximately 50%. Cell influx was not observed when jararhagin was injected into 1-hr air pouches devoid of macrophages, except when it was injected together with 10⁶ syngeneic peritoneal macrophages. Supernatants of macrophages stimulated in vitro with jararhagin did not induce leukocyte influx in 1-hr air pouches; the influx occurred after injection of the pellets of stimulated cultures. In summary, jararhagin is an important pro-inflammatory component of B. jararaca venom, and its activity is dependent upon the proteolytic activity and the presence of macrophages.     

A novel metalloprotease from Vipera lebetina venom induces human endothelial cell apoptosis.

A novel endothelial cell apoptosis inducing metalloprotease (VLAIP) was found in the snake venom of Vipera lebetina. This metalloprotease is a heterodimeric glycoprotein with molecular mass of about 106 kDa. The protease hydrolyzes azocasein, fibrinogen and oxidized insulin B-chain. The enzyme readily hydrolyzes the Aalpha-chain and more slowly Bbeta-chain of fibrinogen. VLAIP does not cleave fibrin. The complete amino acid sequences of the two different monomers of VLAIP are deduced from the nucleotide sequences of cDNAs encoding these proteins. The full-length cDNA sequences of the VLAIP-A and VLAIP-B encode open reading frames of 616 and 614 amino acids that include signal peptide, propeptide and mature metalloproteinase with disintegrin-like and cysteine-rich domains. VLAIP belongs to the metalloprotease/disintegrin family of reprolysins and has high identity with the proteins that induce apoptosis of endothelial cells. Treatment of HUVEC cells with VLAIP induces changes in the attachment of cells to the substrate and causes cell death. We demonstrated that VLAIP inhibits endothelial cell adhesion to extracellular matrix proteins: fibrinogen, fibronectin, vitronectin, collagen I, and collagen IV. The induction of apoptosis by VLAIP was shown by means of a typical DNA fragmentation pattern of apoptotic cells as well as by monitoring phosphatidylserine externalization using annexin V-FITC staining and flow cytometric analysis.     

蛇毒解离素的结构特征及其与生物学活性的关系

目前已从蛇毒中分离出 80余种解离素多肽,根据其结构及来源可分为五大类,即短链、中链、长链解离素、金属蛋白酶P Ⅲ的类解离素区释放的解离素以及二聚体解离素。不同解离素的分子结构共同点包括RGD活性中心、半胱氨酸残基配对形成的二硫键、RGD三肽的C 端和N 端的氨基酸序列以及解离素多肽分子的C 末端。这些结构决定了解离素的抑制血小板聚集、抑制细胞粘附以及血管形成等生物学活性。     

Evaluation of a chromogenic commercial assay using VWF-73 peptide for ADAMTS13 activity measurement

Introduction

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA), related to a severe functional deficiency of ADAMTS13 activity (< 10% of normal). ADAMTS13 activity is thus crucial to confirm the clinical suspicion of TTP, to distinguish it from other TMAs, and to perform the follow-up of TTP patients.

Material and methods

We compared the performance of the commercial chromogenic assay Technozym® ADAMTS13 Activity ELISA (chromogenic VWF73 substrate, Chr-VWF73, Technoclone, Vienna, Austria), to that of our in-house FRETS-VWF73 used as reference method. A large group of 247 subjects (30 healthy volunteers and 217 patients with miscellaneaous TMAs) was studied.

Results

The lower limit of detection of the Chr-VWF73 was 3%, which is well adapted to the clinically relevant threshold for TTP diagnosis (10%). Our results showed a reasonable agreement between FRETS-VWF73 and Chr-VWF73 assays to distinguish samples with an ADAMTS13 activity < 10% from those with an ADAMTS13 activity > 10%. However, Chr-VWF73 assay provided false negative results in ~ 12% of acute TTP patients. Inversely, the Chr-VWF73 assay globally underestimated ADAMTS13 activity in detectable values ranging from 11 to 100% (with a great variability compared to FRETS-VWF73), which may be a concern for the follow-up of TTP patients in remission.

Conclusion

In-house assays developed and performed by expert laboratories remain the reference methods that should be used without limitation to control values provided by commercial assays when needed. Also, the development of an international reference preparation will be crucial to improve standardization.     

多配体蛋白聚糖-4和新型金属蛋白酶-1在组织愈合过程中的作用

多配体蛋白聚糖-4是一种新发现的多肽,广泛存在于多种组织中,调控着多种生物学效应。含Ⅰ型血小板结合蛋白基序的解聚蛋白样金属蛋白酶(ADAMTS)-1是一种新型金属蛋白酶,广泛存在于哺乳动物和无脊椎动物体内,在保持凝血系统的稳态、器官生成、炎症和生育等方面起着重要的作用。二者均参与组织的创伤愈合过程,且ADAMTS-1特异性地作用于多配体蛋白聚糖-4,使其胞外区脱落。本文就多配体蛋白聚糖、ADAMTS-1、多配体蛋白聚糖-4与ADAMTS-1、多配体蛋白聚糖-4与牙周组织等研究进展作一综述,为探究牙周组织的损伤修复机制提供理论依据。     

A disintegrin and metalloprotease (ADAM) 33 protein in patients with pulmonary sarcoidosis

Background and objective: A disintegrin and metalloproteinase (ADAM) 33 is a susceptibility gene associated with inflammatory lung and skin diseases. It is selectively expressed in mesenchymal cells, and its metalloprotease activity has been linked to angiogenesis and tissue remodelling. A soluble form of ADAM33 (sADAM33) has been identified in the bronchoalveolar lavage fluid (BALF) of asthmatic patients, and its levels inversely correlate with lung function. Because of its association with inflammatory lung diseases, it was hypothesized that sADAM33 is elevated in BALF of patients with pulmonary sarcoidosis. Methods: After removal of Ig using Protein A/G and enrichment using Concanavalin A beads, sADAM33 was identified in BALF by Western blotting. A fluorescence resonance energy transfer peptide cleavage assay was used to assess ADAM33‐like activity in BALF. Results: sADAM33 protein in BALF was detected as a 25 kDa fragment, and levels were significantly increased in samples from sarcoid patients when compared to healthy controls (P < 0.05). Levels of sADAM33 were inversely correlated with lung function (FVC%) (P < 0.05) and DL_CO % predicted (P < 0.01). No difference in sADAM33 enzymatic activity was observed between healthy and sarcoid BALF samples. Conclusions: Release of sADAM33 is increased in sarcoid and may be associated with abnormal lung function. sADAM33 may be a biomarker of lung tissue inflammation and remodelling in sarcoid.     

ADAM33基因单核苷酸多态性及单体型与慢性阻塞性肺疾病的关联性研究

目的 探讨中国华北地区汉族人群ADAM33基因S1、S2位点单核苷酸多态性及单体型与慢性阻塞性肺疾病(COPD)及肺功能的关联性.方法 应用DNA直接测序的方法,对90例COPD患者和90名健康对照者的ADAM33基因S1、S2位点基因型进行检测;应用SHEsis在线软件构建单体型并进行单体型关联分析.结果 ①病例组和对照组中S1位点基因型及等位基因频率分布比较差异无统计学意义(P＞0.05),S2位点基因型及等位基因频率分布比较差异有统计学意义(P ＜0.05).②Logistic回归分析表明:ADAM33基因S1位点不同基因型COPD发生的相对危险度比较差异无统计学意义(P＞0.05);S2位点不同基因型COPD发生的相对危险度比较,差异有统计学意义(P＜0.05),其中G/G+C/G基因型的OR值为2.364(95％CI 1.251～4.466).③COPD病例组S2位点基因型与肺功能相关临床指标的关系显示:3种基因型FEV1％预计值比较差异无统计学意义而FEV1/FVC比较差异有统计学意义,其中G/G基因型与C/C、C/G基因型相比FEV1/FVC下降更明显.④SHEsis在线软件对S1、S2位点进行单体型分析结果显示,单体型CG在COPD组和对照组中比较差异有统计学意义(P＜0.05).结论 在中国华北地区汉族人群中,ADAM33基因与COPD的易感性有关,但与疾病的严重程度无关.     

Transmembrane tumor necrosis factor is a potent inducer of colitis even in the absence of its secreted form

BACKGROUND & AIMS: Tumor necrosis factor (TNF) is cleaved proteolytically from a 26-kilodalton transmembrane precursor protein into secreted 17-kilodalton monomers. Transmembrane (tm) and secreted trimeric TNF are biologically active and may mediate distinct activities. We assessed the consequences of a complete inhibition of TNF processing on the course of colitis in recombination activating gene (RAG)2 -/- mice on transfer of CD4 CD45RB hi T cells. METHODS: TNF -/- mice, transgenic for a noncleavable mutant TNF gene, were used as donors of CD4 T cells, and, on a RAG2 -/- background, also as recipients. Kinetics of disease development were compared in the absence of TNF, in the absence of secreted TNF, and in the presence of secreted and tmTNF. The analysis at the end of the observation period included the histopathologic assessment of the intestine and the localization of TNF and interferon gamma (IFNgamma)-expressing cells. RESULTS: The complete prevention of TNF secretion in tmTNF transgenic RAG2 -/- mice neither prevented nor delayed disease induction by transferred transgenic for a noncleavable transmembrane mutant of mouse TNF (tmTNF tg) CD4 CD45RB hi T cells. tmTNF expression by transferred CD4 T cells, however, was not required for disease induction because severe colitis and weight loss also were observed in tmTNF RAG2 -/- recipients of TNF -/- CD4 CD45RB hi T cells. In the presence of tmTNF, the absence of secreted TNF did not affect frequency and distribution of TNF and interferon-gamma messenger RNA (mRNA)-expressing cells. CONCLUSIONS: These results indicate that specific inhibitors of TNF processing are not appropriate for modulating the pro-inflammatory and disease-inducing effects of TNF in chronic inflammatory disorders of the intestine.