用原子力显微镜研究炎症反应中粘附分子间相互作用

在炎症反应中,白细胞在血液流动动力和粘附分子的作用下在血管内皮上的滚动,是白细胞从流动的血液中浸润、迁移到炎症部位整个过程的第一步。白细胞在内皮细胞上滚动由选择素分子与其配体分子相互作用所导致,其中P选择素分子（P-selectin）与其对应的P-选择素糖蛋白配体-1（PSGL-1）的相互作用起着重要的作用。原子力显微镜技术能定量分析P-seleetin／PSGL-1相互作用的动力学反应。     

炎症反应中选择素粘附分子与配体间相互作用的研究

在炎症反应中,白细胞在内皮细胞上滚动由选择素分子与其配体分子相互作用所导致,选择素分子有3种,P选择素分子（P—selectin）、E选择素分子（E—selectin）、L选择素分子（L—selectin）,选择素分子与其对应的P-选择素糖蛋白配体-1（PSGL-1）的相互作用起着重要的作用。用等离子共振、流动腔、原子力显微镜等技术能定量分析选择素分子与其配体分子相互作用的动力学反应。     

P-选择素及其细胞黏附与血栓形成

P-选择素是选择素家族的重要黏附分子,作为血小板/内皮细胞活化标志和细胞黏附受体,其可通过介导血小板、内皮细胞黏附及与白细胞的相互作用,启动参与了包括炎症和血栓形成等多种病理生理起始过程,是炎症/血栓的重要介质和靶分子。抑制P-选择素及其与配体的结合和作用,可使病理状态下血栓局部白细胞聚集减少、细胞因子及组织因子表达降低、纤维蛋白生成减少,从而有助于抑制血栓的形成。因此,随着P-选择素及其细胞黏附与血栓形成研究的不断深入和阐明,以P-选择素为靶标的血栓性疾病的诊断和抗黏附治疗,也已引起人们关注并具有良好的临床应用价值和前景。     

L-选择素在白细胞活化中的作用

白细胞沿着血管内皮滚动、稳定黏附,最终到达炎症部位是一个复杂的、多步骤的过程,该过程需要众多分子协同完成。选择素家族分子对于白细胞沿着血管内皮的滚动起重要作用。L-选择素是选择素家族的一员,组成性的表达在白细胞微绒毛顶端,在白细胞沿血管内皮起始黏附过程中起主要作用。除具有黏附作用外,L-选择素还作为信号分子在黏附事件中发挥作用。该文结合作者的研究工作,综述了L-选择素在白细胞活化过程中的功能。     

重组人P-选凝素及P-选凝素糖蛋白配基-1的表达与鉴定

P-选凝素表达于血管内皮细胞及血小板膜上,它可以与白细胞膜表面的P-选凝素糖蛋白配基-1(P-selectin glyco-protein ligand-1,PSGL-1)相互作用,在炎症过程中介导白细胞的滚动并启动随后的白细胞迁移级联过程.我们构建了重组人野生型可溶性P-选凝素及其钙离子结合位点突变体,同时构建了重组PSGL-1免疫球蛋白融合分子(PSGL-1-Rg),并应用昆虫杆状病毒表达系统在Sf9细胞中表达这些重组蛋白,最后用镍金属螯和柱或Protein A亲和柱予以纯化.结果显示,用该系统表达的P-选凝素或PSGL-1是有活性的,但是P-选凝素的4个钙离子结合位点突变体却没有活性.该研究证明了P-选凝素钙离子结合位点在其与配基相互作用中的重要性.     

选择素与肿瘤转移

选择素是已知的细胞粘附分子家族之一,其生理功能是在炎症发生时介导白细胞与血管内皮间的起始粘附.近年来,大量实验证据表明选择素在肿瘤转移的过程中也起重要作用,主要是介导肿瘤细胞与血小板及血管内皮间的起始粘附,另外选择素及其配体也可以作为信号分子促进肿瘤的转移.因此,在将来的临床应用中,选择素及其配体可以作为血清诊断标记监控肿瘤及肿瘤转移的发生;通过抑制选择素与其配体的相互作用,或阻断选择素表达的途径防止肿瘤转移.     

淋浆对内毒素休克大鼠微循环障碍的干预作用

目的：探讨淋浆对内毒素休克的干预作用及其机制。方法：Wistar雄性大鼠60只,随机分为对照组、模型组和淋浆组,以颈静脉注射LPS（15 mg/kg）复制内毒素休克模型,造模15 min后,淋浆组自颈静脉注射正常淋浆（占全血量1/15）,观察对平均动脉血压（MAP）、回肠下段肠系膜微循环、细静脉壁白细胞粘附数、血浆P-选择素和细胞间粘附分子（ICAM-1）含量的影响。结果：正常淋浆可防止内毒素休克的MAP进行性下降,解除肠系膜微血管的病理性缩窄,减少白细胞在细静脉壁的粘附,改善微循环的流态,降低血浆P-选择素和ICAM-1的水平。结论：小量正常淋浆对LPS攻击导致内毒素休克的微循环障碍和低血压均有良好的干预作用,其机制与减少细胞粘附分子生成有关。     

肺炎支原体对宿主细胞黏附机制的研究进展

肺炎支原体通过其末梢尖端结构即黏附细胞器与呼吸道黏膜上皮细胞受体(唾液酸共轭物或糖脂结构域)结合并定植于人体呼吸道,引起原发性非典型性肺炎等疾病。因此,其黏附机制引起了人们的重视。本文着重阐述了肺炎支原体黏附细胞器的形态、结构,黏附素与黏附辅助蛋白的种类、定位、功能及在黏附过程中的协同作用。     

D-二聚体、P-选择素及血管内皮生长因子与下肢骨折患者深静脉血栓形成的关系

摘要 目的：探究D-二聚体(D-D)、P-选择素及血管内皮生长因子(VEGF)与下肢骨折患者深静脉血栓(DVT)形成的关系。方法：选取2017年2月至2019年10月期间我院诊治的80例下肢骨折并发DVT患者作为DVT组,选择同期治疗的95例下肢骨折但未并发DVT患者作为无DVT组。比较两组患者的各项临床资料,采用多因素Logistic回归分析下肢骨折患者DVT发生的危险因素,采用受试者工作特征（ROC）曲线分析血清D-D、P-选择素、VEGF对下肢骨折患者DVT的诊断价值。结果：与无DVT组相比,DVT组血清D-D、P-选择素和VEGF水平明显升高（P<0.05）。多因素Logistic回归分析结果显示血清D-D、P-选择素、VEGF是下肢骨折患者DVT发生的危险因素（OR=1.996、2.335、1.743,P<0.05）。ROC曲线分析结果显示血清D-D、P-选择素、VEGF诊断下肢骨折患者DVT的曲线下面积（AUC）分别为0.771、0.790、0.812,血清D-D、P-选择素、VEGF联合诊断下肢骨折患者DVT的AUC为0.945。结论：下肢骨折合并DVT患者血清D-D、P-选择素、VEGF水平明显升高,并且血清D-D、P-选择素和VEGF是下肢骨折患者发生DVT的危险因素,三者联合检测在下肢骨折患者发生DVT的诊断和预测中具有一定临床意义。     

P-选择素为靶标磁共振分子成像在血栓早期诊断中的应用研究

血栓性疾病是临床常见疾病,涉及全身各脏器,其发生与血管损伤、血液成分变化及局部血流淤滞等改变有关.P-选择素作为血小板/内皮细胞活化标志及黏附受体,参与血栓形成起始过程,并是连接炎症与血栓的重要介质和靶分子.为此,进行了以P-选择素为靶标的分子磁共振成像(magnetic resonance imaging,MRI)在血栓早期诊断中的应用研究.利用自制的抗P-选择素单抗(PsL-EGFmAb),制备了具有P-选择素靶特异性的MR对比剂(Gd-DTPA)n-BSA-PsL- EGFmAb,并在体外MR成像基础上,进行了犬静脉血栓模型活体观察.结果显示,该对比剂可明显增强体外模拟血小板血栓和全血血栓的显像信号.进一步发现,相应于P-选择素在建模后即刻犬受损静脉血管内膜及形成的血栓部位表达,模型犬在损伤局部注射对比剂后30 min,MR成像即显示高于周围肌肉显影的血管信号,1 h可见附壁血栓增强信号,至3 h随血栓形成增大而持续强化,显示了与P-选择素表达一致的信号强化效果.另从股静脉损伤部位的远心端注射对比剂后30 min至1 h,也显示上述成像效果,2 h 至4 h血栓信号强度由明显上升渐见趋缓,延迟24 h信号强度减弱.此外,该对比剂对实验犬的生命体征及心、肺、肝、肾等理化指标均无明显影响.研究结果提示,研制的MR对比剂对P-选择素具有靶向特异性,可活体内早期定位显像及反映血栓形成状态,且对机体重要脏器功能无影响,这为早期诊断血栓性疾病提供了一种可行的方法.     

Is the large plasmid of 120 MDa in Shigella sonnei composed of two DNA segments—90 and 30 MDa?

Abstract The reversibility of adhesion of 3 representative strains of oral streptococci from a phosphate-buffered suspension onto 5 different solid substrata was studied.
Streptococcus mitis T9 (surface free energy γ_b= 39 mJ · m⁻²). Streptococcus sanguis CH3 (γ_b= 95 mJ · m⁻²) and Streptococcus mutans NS (γ_b= 117 mJ · m⁻²) were selected on basis of their surface free energy. Solid substrata were employed with a surface free energy γ_s ranging from 20 mJ · m⁻² for polytetrafluorethylene to 109 mJ · m⁻² for glass. Bacterial suspensions containing 2.5 × 10⁹ cells per ml were incubated with 2 samples of each substratum. After 1 h the number of adhering bacteria was evaluated on one sample, while the second sample was kept for another hour at a 10-fold lower bacterial concentration. Bacteria with a low surface free energy desorbed only from substrata with a high surface free energy, while bacteria with a high surface free energy desorbed from substrata with a low surface free energy. Thus low energy bacterial strains adhered reversibly to high energy substrata and vice versa. Similar observations were made with polystyrene particles. Calculation of the interfacial free energy of adhesion (Δ F _adh) for each bacterial strain as well as for the polystyrene particles showed that a reversible adhesion was associated with a positive Δ F _adh, denoting unfavourable adhesion conditions upon a thermodynamic basis.     

白细胞与内皮细胞的粘附

白细胞与内皮细胞相互作用由粘附分子介导.整合素、免疫球蛋白及选择素家族的粘附分子在这两种细胞的粘附中起关键作用.粘附的起始阶段由选择素介导,随后由CD11/CD18复合物与ICAM-1形成更为紧密的结合.多种细胞因子及炎症反应可诱导粘附.抗粘附分子单抗、药物等可抑制粘附.     

Integrin adhesions

Cell migration requires the coordination of adhesion site assembly and turnover. Canonical models for nascent adhesion formation postulate that integrin binding to extracellular matrix (ECM) proteins results in the rapid recruitment of cytoskeletal proteins such as talin and paxillin to integrin cytoplasmic domains. It is thought that integrin-talin clusters recruit and activate tyrosine kinases such as focal adhesion kinase (FAK). However, the molecular connections of this linkage remain unresolved. Our recent findings support an alternative model whereby FAK recruits talin to new sites of β1 integrin-mediated adhesion in mouse embryonic fibroblasts and human ovarian carcinoma cells. This is dependent on a direct binding interaction between FAK and talin and occurs independently of direct talin binding to β1 integrin. Herein, we discuss differences between nascent and mature adhesions, interactions between FAK, talin and paxillin, possible mechanisms of FAK activation and how this FAK-talin complex may function to promote cell motility through increased adhesion turnover.     

Stabilization of polyvinyl alcohol coating of polyester cloth for reduction of bacterial adhesion

Bacterial adhesion onto polyester cloth was greatly reduced by coating the cloth with polyvinyl alcohol (PVA). Under autoclaving conditions, the PVA coating was stable in water but not in 1% SDS. However, the treatment of the PVA-coated cloth with acidic 1% glutaraldehyde stabilized the coating to retain full resistance to bacterial adhesion even after autoclaving in 1% SDS.     

植物乳杆菌黏附大鼠小肠黏液及机制的研究

分析了6种植物乳杆菌黏附大鼠小肠粘液的能力,并分析了介导黏附性的主要因素。结果表明,植物乳酸杆菌向大鼠小肠粘液的黏附具有菌种特异性,其黏附作用是甘露糖特异性的,细胞外表蛋白质、碳水化合物和(脂)磷壁酸可能参与了黏附过程。     

The Kindlins: subcellular localization and expression during murine development

The three Kindlins are a novel family of focal adhesion proteins. The Kindlin-1 (URP1) gene is mutated in Kindler syndrome, the first skin blistering disease affecting actin attachment in basal keratinocytes. Kindlin-2 (Mig-2), the best studied member of this family, binds ILK and Migfilin, which links Kindlin-2 to the actin cytoskeleton. Kindlin-3 is expressed in hematopoietic cells. Here we describe the genomic organization, gene expression and subcellular localization of murine Kindlins-1 to -3. In situ hybridizations showed that Kindlin-1 is preferentially expressed in epithelia, and Kindlin-2 in striated and smooth muscle cells. Kindlins-1 and -2 are both expressed in the epidermis. While both localize to integrin-mediated adhesion sites in cultured keratinocytes Kindlin-2, but not Kindlin-1, colocalizes with E-cadherin to cell-cell contacts in differentiated keratinocytes. Using a Kindlin-3-specific antiserum and an EGFP-tagged Kindlin-3 construct, we could show that Kindlin-3 is present in the F-actin surrounding ring structure of podosomes, which are specialized adhesion structures of hematopoietic cells.     

Temporal and spatial variations in macrofouling of silicone fouling‐release coatings

Nontoxic, low surface free energy silicone coatings having reduced biofouling adhesion strength have been developed as an alternative to antifouling paints. Silicone coatings permit macrofouling to adhere; however, fouling can be removed easily by water pressure or light scrubbing. One of the current methods used to evaluate the performance of non‐toxic silicone fouling‐release coatings relies heavily on fouling coverage. The organismal community structure as well as total coverage can affect the ease of fouling removal from these coatings. This paper explores fouling coverage and organismal adhesion over time. Long‐term fouling coverage data were collected at four sites (in Massachusetts, Hawaii and Florida) using static immersion panels coated with silicone and oil‐amended silicone systems. Inter‐site differences in fouling coverage and community structure were observed for each coating. Intra‐site variation and temporal change in coverage of fouling was minimal, regardless of coating formulation. The extent of coverage was affected by the duration of immersion and the local environmental conditions; these factors may also have an impact on the foul‐release capability of the silicone coatings. Organismal adhesion data was collected in Hawaii and Florida. These adhesion measurements were used as a tool to discriminate and rank fouling release coatings.     

RGD-grafted poly-L-lysine-graft-(polyethylene glycol) copolymers block non-specific protein adsorption while promoting cell adhesion

A novel class of surface-active copolymers is described, designed to protect surfaces from nonspecific protein adsorption while still inducing specific cell attachment and spreading. A graft copolymer was synthesized, containing poly-(L-lysine) (PLL) as the backbone and substrate binding and poly(ethylene glycol) (PEG) as protein adsorption-resistant pendant side chains. A fraction of the grafted PEG was pendantly functionalized by covalent conjugation to the peptide motif RGD to induce cell binding. The graft copolymer spontaneously adsorbs from dilute aqueous solution onto negatively charged surfaces. The performance of RGD-modified PLL-g-PEG copolymers was analyzed in protein adsorption and cell culture assays. These coatings efficiently blocked the adsorption of serum proteins to Nb(2)O(5) and tissue culture polystyrene while specifically supporting attachment and spreading of human dermal fibroblasts. This surface functionalization technology is expected to be valuable in both the biomaterial and biosensor fields, because different signals can easily be combined, and sterilization and application are straightforward and cost-effective.     

白念珠菌对宿主的黏附机制

白念珠菌对宿主的黏附是白念珠菌感染过程的关键的第一步,因此阐明白念珠菌对宿主的黏附机制对探索新的方法预防和治疗白念珠菌感染至关重要。近年来,研究者们从白念珠菌的表面结构、黏附素以及黏附相关基因等方面对白念珠菌与宿主的黏附机制进行了大量研究。该文就白念珠菌对宿主的黏附机制进行综述。     

FAK dimerization controls its kinase‐dependent functions at focal adhesions

Focal adhesion kinase (FAK) controls adhesion‐dependent cell motility, survival, and proliferation. FAK has kinase‐dependent and kinase‐independent functions, both of which play major roles in embryogenesis and tumor invasiveness. The precise mechanisms of FAK activation are not known. Using x‐ray crystallography, small angle x‐ray scattering, and biochemical and functional analyses, we show that the key step for activation of FAK's kinase‐dependent functions—autophosphorylation of tyrosine‐397—requires site‐specific dimerization of FAK. The dimers form via the association of the N‐terminal FERM domain of FAK and are stabilized by an interaction between FERM and the C‐terminal FAT domain. FAT binds to a basic motif on FERM that regulates co‐activation and nuclear localization. FAK dimerization requires local enrichment, which occurs specifically at focal adhesions. Paxillin plays a dual role, by recruiting FAK to focal adhesions and by reinforcing the FAT:FERM interaction. Our results provide a structural and mechanistic framework to explain how FAK combines multiple stimuli into a site‐specific function. The dimer interfaces we describe are promising targets for blocking FAK activation.