EB病毒致病机制研究进展

EB病毒(Epstein-Barr virus,EBV)是一种常见的人类4型疱疹病毒,原发感染后可终身携带病毒。EBV感染无法从宿主中清除,呈现潜伏状态,一旦激活即可成为很多疾病的相关病因,与人类多种疾病特别是恶性肿瘤相关,包括Burkitt淋巴瘤、鼻咽癌、胃癌等。EBV致病机制复杂多样,目前致病机制的具体分子遗传机制尚未明确。本文主要从EBV与宿主细胞相互作用、免疫逃逸、EBV感染周期表达的相关产物与宿主的相互作用等几个方面,综述目前EBV致病机制的研究进展。     

抗多药耐药靶点及相关药物的研究进展

抗多药耐药是指在疾病的治疗过程中,细胞对多种药物产生广泛的耐受,导致治疗效果不理想的现象。多药耐药多发于感染与肿瘤疾病的治疗中,已成为治愈这2 类疾病的主要障碍。从转运蛋白和离子通道、酶以及核糖体这3 个方面综述抗多药耐药靶点的机制及相关药物的研究进展,旨在为抗多药耐药药物的研发提供参考。     

艰难梭菌的研究进展

艰难梭菌为革兰阳性厌氧芽胞杆菌,可引起艰难梭菌相关性腹泻,导致一系列肠道感染症状和相关临床表现。近年来由于高致病株的出现、菌株耐药性的增加,艰难梭菌感染在全球呈蔓延趋势。本文就艰难梭菌的耐药机制、检测技术、防治及国内感染现状等作一简要综述。     

人腺病毒的研究进展

人腺病毒(Human adenovirus,HAdV)是引起婴幼儿急性呼吸道感染等多种疾病的重要病原体之一,本文回顾了有关HAdV的分子生物学特征、检测方法及分型、致病机制、相关疾病的临床特征、流行病学特征、HAdV感染的预防和控制研究的文献。迄今为止明确的HAdV有67种不同型别,包括近几年发现的重组变异株。导致急性呼吸道感染的主要流行株为HAdV-3和HAdV-7,属于B亚组,也可以引起其他系统的疾病,所致疾病的临床表现与其他呼吸道病毒相关病毒相似,但多伴消化道症状,其致病机制尚不清楚。对于新发现的变异重组株,其与疾病的相关性研究甚少,需要进一步研究证实。由于没有前瞻性的、大样本的随机对照治疗试验,HAdV感染的治疗目前存在争议。疫苗是降低呼吸道HAdV感染最有效的措施,但还没有上市的产品。     

质粒介导的喹诺酮耐药基因qnr的分类、耐药机制及其在国内的流行状况北大核心CSCD

喹诺酮类抗菌药物从早期主要用于治疗尿道感染发展到后来治疗肠道感染和呼吸道感染,目前已在临床、畜牧业和水产业中广泛使用,细菌对其耐药性也逐渐呈蔓延趋势,耐药机制日趋复杂。喹诺酮类耐药机制主要分为染色体介导的耐药和质粒介导的耐药,后者对细菌耐药性的广泛传播起着重要作用。1998年首次报道了质粒介导的喹诺酮类耐药机制,即质粒上qnr基因介导的细菌对氟喹诺酮耐药机制,qnr基因可在不同细菌中迅速水平传播,引发的感染不易控制,使得院内感染大范围的流行。此外,qnr基因通常与β-内酰胺类耐药基因相关或存在于复杂整合子中与其它多重耐药基因共同整合,缩小了临床医生治疗相关细菌感染时选药或联合用药的空间,给我们带来了严峻的挑战。本文就qnr基因的发现历史、耐药机理及在国内的流行状况做了详细概述。     

CRISPR/Cas9在EB病毒感染免疫中的研究进展

爱泼斯坦巴尔病毒(Epstein-Barr virus,EBV)人群感染率高,不同地区、不同年龄人群感染后引发疾病类型各异,除少数急性感染者可自愈外,大部分慢性和潜伏感染者迁延不愈,而且具有潜在的致癌风险;目前机体感染EBV后的免疫机制仍不明确,临床上缺乏有效的治疗药物和根治措施,总体预后较差。作为第三代基因编辑工具,成簇的规律间隔短回文重复序列及相关核酸酶9 (clustered regular interspaced short palindromic repeats/CRISPR-associated nuclease 9,CRISPR/Cas9)技术可在向导RNA引导下,对目的基因组序列进行靶向编辑。因其操作简便、经济高效,目前已广泛应用于农作物品种改良、动物疾病模型构建以及人类疾病精准诊治等领域。本文介绍了CRISPR/Cas9技术应用于EBV感染免疫研究的最新进展,包括EBV致病基因亚型和宿主依赖基因筛选,关键致病机制探索以及基因靶向编辑治疗EBV相关疾病等,为阐明EBV相关疾病的发病机制和探索新型抗病毒治疗策略提供理论依据。     

不可分型流感嗜血杆菌诱导14-3-3ε表达负向调控肺部炎症反应

该文旨在观察14-3-3ε在不可分型流感嗜血杆菌(NTHi)诱导人支气管上皮细胞分泌促炎细胞因子中的作用,并研究其作用机制。分别采用感染复数(MOI)为5、10和20的NTHi感染BEAS-2B细胞,实时定量PCR或Western blot检测感染前后细胞内14-3-3ε的表达情况以及酪氨酸激酶c-Src在其中的作用。同时通过免疫共沉淀检测14-3-3ε与TLR2的结合水平。采用RNA干扰或使细胞内过表达14-3-3ε,免疫荧光和ELISA等方法测定其对NF-κB的活化以及培养上清中TNF-α和IL-6浓度的影响。最后通过动物实验观察抑制14-3-3ε的活性对NTHi感染后肺部炎症反应的影响。结果显示, NTHi感染上皮细胞后, 14-3-3ε的蛋白和mRNA水平随着MOI的递增而增高,采用ActD和CHX预处理细胞后, 14-3-3ε表达水平和对照组相比分别降低了71.05%和59.21%。NTHi感染15min后BEAS-2B细胞中c-Src磷酸化水平增高了3.63倍,而抑制c-Src活性后14-3-3ε表达水平降低了50.60%。免疫共沉淀结果也显示不同MOI NTHi感染后, ...     

流感病毒感染动物疾病模型的研究进展

流感主要是指由甲型流感病毒（Influenza A virus, IAV）感染引起的急性呼吸道疾病。构建差异化的感染动物模型模拟IAV的感染、发病及传播过程不仅有助于揭示流感病毒的传播机制与致病机理,而且对流感大流行的预警和防治有着重要意义。本文基于IAV跨种间传播的差异机制从不同动物模型呼吸道唾液酸受体亚型分布的表型差异及其对人流感病毒的易感性等多方面综述了流感病毒感染动物模型的优缺点及其最新研究进展,以期为IAV致病机制研究,疫苗药物的研发提供理论参考。     

马拉色菌相关疾病研究现状

马拉色菌感染是皮肤科常见的真菌感染性疾病,其中花斑癖的发病与该菌属存在着直接的相关性,目前研究表明脂溢性皮炎、特应性皮炎、马拉色菌毛囊炎、银屑病等相关疾病的发生与发展与马拉色菌属的感染存在着一定的联系。本研究综述结合相关文献报道,对马拉色菌属在一些常见皮肤疾病中的发病机制和相关致病机制作了一定概述。     

念珠菌耐药机制的研究进展

近年来,真菌感染尤其是机会性真菌感染的发生率和病死率呈不断上升的趋势,这主要与真菌耐药和抗真菌药物品种有限有关。念珠菌是人体内的重要条件致病真菌,其常见的耐药机制包括靶酶的改变、靶位的缺乏、真菌细胞膜对药物的通透性下降、多药耐药蛋白表达增高、固醇合成旁路下游的改变、生物膜的形成等,最新文献报道分泌型天冬氨酸蛋白酶在念珠菌的耐药形成中存在一定作用。该文就念珠菌感染的流行病学和念珠菌的耐药机制两个方面进行综述。     

Study of genetic diversity of nontypeable Haemophilus influenzae strains isolated from healthy children and patients with infection symptoms

In the study the usefulness of genotyping methods for genetic variability examinations of non-typeable H. influenzae strains circulating in population as well as level the variability of NTHi strains isolated from healthy children and from symptomatic infection cases have been evaluated. Among genotyping methods evaluated, AFLP method of the MfeI/BglII set has been found most useful to study level of genetic variability of NTHi strains population. It has been shown that NTHi strains colonizing nasopharyngeal of healthy children present higher polymorphism level than strains isolated from patient with clinical symptoms of NTHi infection.     

Characterization of Nontypable Haemophilus influenzae Isolates Recovered from Adult Patients with Underlying Chronic Lung Disease Reveals Genotypic and Phenotypic Traits Associated with Persistent Infection

Nontypable Haemophilus influenzae (NTHi) has emerged as an important opportunistic pathogen causing infection in adults suffering obstructive lung diseases. Existing evidence associates chronic infection by NTHi to the progression of the chronic respiratory disease, but specific features of NTHi associated with persistence have not been comprehensively addressed. To provide clues about adaptive strategies adopted by NTHi during persistent infection, we compared sequential persistent isolates with newly acquired isolates in sputa from six patients with chronic obstructive lung disease. Pulse field gel electrophoresis (PFGE) identified three patients with consecutive persistent strains and three with new strains. Phenotypic characterisation included infection of respiratory epithelial cells, bacterial self-aggregation, biofilm formation and resistance to antimicrobial peptides (AMP). Persistent isolates differed from new strains in showing low epithelial adhesion and inability to form biofilms when grown under continuous-flow culture conditions in microfermenters. Self-aggregation clustered the strains by patient, not by persistence. Increasing resistance to AMPs was observed for each series of persistent isolates; this was not associated with lipooligosaccharide decoration with phosphorylcholine or with lipid A acylation. Variation was further analyzed for the series of three persistent isolates recovered from patient 1. These isolates displayed comparable growth rate, natural transformation frequency and murine pulmonary infection. Genome sequencing of these three isolates revealed sequential acquisition of single-nucleotide variants in the AMP permease sapC, the heme acquisition systems hgpB, hgpC, hup and hxuC, the 3-deoxy-D-manno-octulosonic acid kinase kdkA, the long-chain fatty acid transporter ompP1, and the phosphoribosylamine glycine ligase purD. Collectively, we frame a range of pathogenic traits and a repertoire of genetic variants in the context of persistent infection by NTHi.     

Binding of the non-typeable Haemophilus influenzae lipooligosaccharide to the PAF receptor initiates host cell signalling

Non-typeable Haemophilus influenzae (NTHi) invades host cells by binding of the platelet-activating factor (PAF) receptor via lipooligosaccharide (LOS) glycoforms containing phosphorylcholine (ChoP). The effect of NTHi infection on host cell signalling and its role in NTHi invasion was examined. The infection of human bronchial epithelial cells with NTHi 2019 increased cytosolic Ca²⁺ levels, and the invasion of bronchial cells by NTHi 2019 was inhibited by pretreatment with the cell-permeant intracellular Ca²⁺ chelator BAPTA-AM ( P  = 0.022) or thapsigargin ( P  = 0.016). Cytosolic inositol phosphate (IP) levels were also increased after infection with NTHi 2019 ( P  < 0.001), but not after infection with isogenic mutants expressing altered LOS glycoforms lacking ChoP. PAF receptor antagonist reduced NTHi 2019-stimulated IP production in a dose-dependent manner. NTHi 2019 invasion was inhibited by pertussis toxin (PTX) and the phosphatidylinositol-3-kinase inhibitors wortmannin and LY294002. The less invasive strain NTHi 7502 also initiated IP production, but was unaffected by PAF receptor antagonist or PTX. These data demonstrate that the binding of the PAF receptor by NTHi initiates receptor coupling to a PTX-sensitive heterotrimeric G protein complex, resulting in a multifactorial host cell signal cascade and bacterial invasion. Moreover, the data suggest that NTHi strains initiate cell signalling and invade by different mechanisms, and that invasion mediated by PAF receptor activation is more efficient than macropinocytosis.     

金黄色葡萄球菌持留菌形成机制的研究进展

金黄色葡萄球菌(Staphylococcus aureus)是一种重要的院内感染致病菌,是导致人类各类感染最重要的病原体之一。金黄色葡萄球菌耐药问题一直是临床慢性感染治疗的最大障碍。随着细菌耐药机制研究的不断深入,研究者发现持留菌可能是导致疾病的持续性和复发性感染的真正原因。近年来持留菌的存在引起的耐药问题被高度重视,金黄色葡萄球菌持留菌的基本特征和形成机制的研究对临床上更好地控制耐药及感染问题具有重要的意义。为此,本文将从金黄色葡萄球菌持留菌的特性、生物膜、能量代谢、基因调控等多方面对金黄色葡萄球菌持留菌进行系统全面的综述。     

Immunity to antigens of nontypeable Haemophilus influenzae strains

Nonencapsulated (nontypeable) Haemophilus influenzae (NTHi) is a Gram-negative coccobacillus colonizing upper respiratory tract of most healthy people and causing such diseases as otitis media, sinusitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. NTHi may cause systemic infection. As a result, over the past decade the bacterium has been the subject of intense research. However immune response to NTHi has not been well characterized. Data on research of immune response to NTHi are presented.     

A chalcone with potent inhibiting activity against biofilm formation by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi), an important human respiratory pathogen, frequently causes biofilm infections. Currently, resistance of bacteria within the biofilm to conventional antimicrobials poses a major obstacle to effective medical treatment on a global scale. Novel agents that are effective against NTHi biofilm are therefore urgently required. In this study, a series of natural and synthetic chalcones with various chemical substituents were evaluated in vitro for their antibiofilm activities against strong biofilm‐forming strains of NTHi. Of the test chalcones, 3‐hydroxychalcone (chalcone 8 ) exhibited the most potent inhibitory activity, its mean minimum biofilm inhibitory concentration (MBIC₅₀) being 16 μg/mL (71.35 μM), or approximately sixfold more active than the reference drug, azithromycin (MBIC₅₀ 419.68 μM). The inhibitory activity of chalcone 8 , which is a chemically modified chalcone, appeared to be superior to those of the natural chalcones tested. Significantly, chalcone 8 inhibited biofilm formation by all studied NTHi strains, indicating that the antibiofilm activities of this compound occur across multiple strong‐biofilm forming NTHi isolates of different clinical origins. According to antimicrobial and growth curve assays, chalcone 8 at concentrations that decreased biofilm formation did not affect growth of NTHi, suggesting the biofilm inhibitory effect of chalcone 8 is non‐antimicrobial. In terms of structure–activity relationship, the possible substituent on the chalcone backbone required for antibiofilm activity is discussed. These findings indicate that 3‐hydroxychalcone (chalcone 8 ) has powerful antibiofilm activity and suggest the potential application of chalcone 8 as a new therapeutic agent for control of NTHi biofilm‐associated infections.     

Relative Contribution of P5 and Hap Surface Proteins to Nontypable Haemophilus influenzae Interplay with the Host Upper and Lower Airways

Nontypable Haemophilus influenzae (NTHi) is a major cause of opportunistic respiratory tract disease, and initiates infection by colonizing the nasopharynx. Bacterial surface proteins play determining roles in the NTHi-airways interplay, but their specific and relative contribution to colonization and infection of the respiratory tract has not been addressed comprehensively. In this study, we focused on the ompP5 and hap genes, present in all H. influenzae genome sequenced isolates, and encoding the P5 and Hap surface proteins, respectively. We employed isogenic single and double mutants of the ompP5 and hap genes generated in the pathogenic strain NTHi375 to evaluate P5 and Hap contribution to biofilm growth under continuous flow, to NTHi adhesion, and invasion/phagocytosis on nasal, pharyngeal, bronchial, alveolar cultured epithelial cells and alveolar macrophages, and to NTHi murine pulmonary infection. We show that P5 is not required for bacterial biofilm growth, but it is involved in NTHi interplay with respiratory cells and in mouse lung infection. Mechanistically, P5_NTHi375 is not a ligand for CEACAM1 or α5 integrin receptors. Hap involvement in NTHi375-host interaction was shown to be limited, despite promoting bacterial cell adhesion when expressed in H. influenzae RdKW20. We also show that Hap does not contribute to bacterial biofilm growth, and that its absence partially restores the deficiency in lung infection observed for the ΔompP5 mutant. Altogether, this work frames the relative importance of the P5 and Hap surface proteins in NTHi virulence.     

白念珠菌唑类药物耐药相关转录因子研究进展

近年来白念珠菌的感染率呈逐年上升趋势,随着唑类药物的广泛应用,耐药菌株不断增多,已成为临床治疗的一大难题.白念珠菌的耐药机制主要与ERG 11基因的突变和过表达、药物外排泵相关基因表达增多及生物膜的形成等有关,由于转录因子是耐药基因表达的关键调节因子,关于锌簇转录因子与耐药关系的研究越来越多,如TAC 1、MRR 1、MRR 2、UPC 2、NDT 80等,其点突变可引起某些耐药基因的过表达而介导耐药,该领域研究已成为热点,该文就此研究进展做一概述.     

Rhinovirus Attenuates Non-typeable Hemophilus influenzae-stimulated IL-8 Responses via TLR2-dependent Degradation of IRAK-1

Bacterial infections following rhinovirus (RV), a common cold virus, are well documented, but pathogenic mechanisms are poorly understood. We developed animal and cell culture models to examine the effects of RV on subsequent infection with non-typeable Hemophilus influenzae (NTHi). We focused on NTHI-induced neutrophil chemoattractants expression that is essential for bacterial clearance. Mice infected with RV1B were superinfected with NTHi and lung bacterial density, chemokines and neutrophil counts determined. Human bronchial epithelial cells (BEAS-2B) or mouse alveolar macrophages (MH-S) were infected with RV and challenged with NHTi, TLR2 or TLR5 agonists. Chemokine levels were measured by ELISA and expression of IRAK-1, a component of MyD88-dependent TLR signaling, assessed by immunoblotting. While sham-infected mice cleared all NTHi from the lungs, RV-infected mice showed bacteria up to 72 h post-infection. However, animals in RV/NTHi cleared bacteria by day 7. Delayed bacterial clearance in RV/NTHi animals was associated with suppressed chemokine levels and neutrophil recruitment. RV-infected BEAS-2B and MH-S cells showed attenuated chemokine production after challenge with either NTHi or TLR agonists. Attenuated chemokine responses were associated with IRAK-1 protein degradation. Inhibition of RV-induced IRAK-1 degradation restored NTHi-stimulated IL-8 expression. Knockdown of TLR2, but not other MyD88-dependent TLRs, also restored IRAK-1, suggesting that TLR2 is required for RV-induced IRAK-1 degradation.In conclusion, we demonstrate for the first time that RV infection delays bacterial clearance in vivo and suppresses NTHi-stimulated chemokine responses via degradation of IRAK-1. Based on these observations, we speculate that modulation of TLR-dependent innate immune responses by RV may predispose the host to secondary bacterial infection, particularly in patients with underlying chronic respiratory disorders.     

Cellular content plays a crucial role in Non‐typeable Haemophilus influenzae infection of preinflamed Junbo mouse middle ear

Non‐typeable Haemophilus influenzae (NTHi) is a major pathogen causing acute otitis media (AOM). The relationship between the cellular content of the middle ear fluid (MEF) during AOM and infection of NTHi is poorly understood. Using the Junbo mouse, a characterised NTHi infection model, we analysed the cellular content of MEF and correlated the data with NTHi titres. The MEF of the Junbo mouse was heterogeneous between ears and was graded from 1 to 5; 1 being highly serous/clear and 5 being heavily viscous/opaque. At seven‐day post‐intranasal inoculation, NTHi was not found in grade‐1 or 2 fluids, and the proportion of MEF that supported NTHi increased with the grade. Analyses by flow cytometry indicated that the cellular content was highest in grade‐4 and 5 fluids, with a greater proportion of necrotic cells and a low‐live cell count. NTHi infection of the middle ear increased the cell count and led to infiltration of immune cells and changes in the cytokine and chemokine levels. Following NTHi inoculation, high‐grade infected MEFs had greater neutrophil infiltration whereas monocyte infiltration was significantly higher in serous noninfected low‐grade fluids. These data underline a role for immune cells, specifically monocytes and neutrophils, and cell necrosis in NTHi infection of the Junbo mouse middle ear.