抗菌肽抗肿瘤作用机制的研究进展

抗菌肽(antimicrobal peptides,AMPs)是天然免疫系统中的一种小分子多肽,一些具有抗肿瘤活性,毒副反应小,不易产生耐药性.近年来,研究已经明确了抗菌肽对肿瘤细胞的杀伤抑制作用及其作用机制,其中作用机制包括以下5方面:(1)在肿瘤细胞膜上形成穿膜孔道,使肿瘤细胞死亡;(2)作用于细胞骨架使其结构紊乱...     

抗菌肽抗肿瘤作用机制的研究进展

抗菌肽(antimicrobal peptides,AMPs)是天然免疫系统中的一种小分子多肽,一些具有抗肿瘤活性,毒副反应小,不易产生耐药性.近年来,研究已经明确了抗菌肽对肿瘤细胞的杀伤抑制作用及其作用机制,其中作用机制包括以下5方面:(1)在肿瘤细胞膜上形成穿膜孔道,使肿瘤细胞死亡;(2)作用于细胞骨架使其结构紊乱;(3)抑制DNA合成,影响细胞增殖;(4)作用于线粒体,引起肿瘤细胞凋亡;(5)影响免疫效应进而杀伤肿瘤细胞.该文就抗菌肽抗肿瘤细胞的作用机制作一综述.     

抗肿瘤效果截然不同的两种昆虫抗菌肽

目的观测家蝇幼虫抗菌肽与美洲大蠊若虫抗菌肽对肿瘤细胞109(人食管癌细胞株)、K562(人髓样白血病细胞株)的作用。方法通过针刺感染大肠杆菌诱导这两种昆虫产生抗菌肽,再经研磨、离心、层析等步骤提取抗菌肽,然后作用于109和K562肿瘤细胞,用流式细胞仪检测有效杀伤率。结果家蝇幼虫抗菌肽对109的有效杀伤率M1为91．0%(对照50．9%),对K562的有效杀伤率M1为95．5%(对照71．3%);而美洲大蠊若虫抗菌肽对109的有效杀伤率M1为12．6%(对照57．9%),对K562的有效杀伤率M1仅为3．3%(对照68．5%)。家蝇幼虫抗菌肽对两种肿瘤细胞都有较明显的杀伤效果;美洲大蠊若虫抗菌肽对两种肿瘤细胞除了有很小的杀伤力外,更主要的是对其具有促进生长的作用(45．3%,65．2%)。结论两种昆虫抗菌肽产生的抗肿瘤效果不同。     

抗菌肽对肿瘤细胞的作用机制及应用前景

抗菌肽(antibacterial peptide)是具有抗菌活性的一类多肽,广泛存在于生物界。它是宿主免疫防御系统的重要成分,具有广谱杀菌、相对分子量较小、热稳定性及水溶性好等优点,更重要的是它可以选择性作用于肿瘤细胞,对正常细胞损伤小,毒性小,不易产生耐药性,有望开发成为新一代具有广阔应用前景的抗癌药物。该文综合近年来抗菌肽的研究,概述了抗菌肽对肿瘤细胞的作用机制及其应用前景。     

抗菌肽LL-37抗寄生虫活性研究进展

由原虫、蠕虫感染导致的寄生虫病在全球范围内广泛流行,尤其是在热带和亚热带地区,对儿童和成人生命健康均造成威胁。抗寄生虫药的长期使用导致寄生虫对药物敏感性下降甚至出现耐药性。研究表明抗菌肽可抑制寄生虫生长发育,具有潜在抗寄生虫价值,其中LL-37作为组织蛋白酶抑制素(cathelicidin)家族中唯一的人源抗菌肽被广泛研究。本文综述了LL-37抗寄生虫作用的研究进展,并对其作为抗寄生虫药物的候选资源的应用前景进行了探讨。     

生物抗菌肽毕赤酵母表达系统研究进展

抗菌肽是具有抗菌活性的一类短肽,广泛存在生物界。抗菌肽具有广谱抗菌活性,有良好的应用前景,使其走向临床的最大的挑战是如何用基因工程技术低成本大量生产抗菌肽产品。抗菌肽天然提取资源有限且提取难度大,难以实现规模化生产;人工合成成本太高,难以实现产业化,目前多局限于研究用途。毕赤酵母表达系统适用于多种生物抗菌肽的表达,多种表达策略的采用可以提高表达量,毕赤酵母表达抗菌肽具有良好的应用前景。本文综述了抗菌肽毕赤酵母表达的研究进展。     

抗结核抗菌肽及其纳米药物递送系统的研究进展

由结核分枝杆菌复合群菌株引起的结核病是世界上最致命的传染病之一,同时由于愈发严重的耐药问题,使得对新型抗结核药物的需求更为迫切。抗菌谱广、耐药性低的抗菌肽在治疗结核病方面展现出巨大的潜力,但天然抗菌肽的低稳定性等局限使其临床应用受到限制。药物递送系统,特别是纳米药物递送载体成为解决该问题的重要途径之一。本文综述了抗结核抗菌肽的特征、作用机制和靶点,及近年来抗结核抗菌肽的生产、修饰和优化、与化疗药物联用等方面的研究现状;针对抗结核抗菌肽治疗面临的问题和抗结核药物纳米药物递送系统的发展,分析和展望了多种纳米材料作为抗结核抗菌肽递送载体的研究与应用,期望对更有效的结核病疗法的研发提供思路和指导。     

芒果甙抗肿瘤作用机制研究进展

芒果甙是一种黄酮类化合物,具有多种生理和药理作用,近期的研究报道芒果甙具有抗肿瘤作用。芒果甙抗肿瘤作用主要包括抑制肿瘤细胞增殖生长、阻断细胞周期、诱导细胞凋亡、抑制NF-κB信号途径激活、影响E-cad介导的细胞黏附及信号转导、干预线粒体通透性转换及与化疗药物发挥联合作用等。     

褪黑素抗肿瘤作用及其机制的研究进展

褪黑素(MT)是人体内的一种神经内分泌激素,研究表明MT对恶性肿瘤具有明显抑制作用,其抗瘤机制复杂而广泛。此文就近年来对MT的抗肿瘤机制及其临床试验研究作一综述。     

RNA测序研究抗菌肽KT2治疗溃疡性结肠炎的作用机制

目的 通过RNA测序（RNA-seq）研究抗菌肽KT2治疗溃疡性结肠炎（UC）小鼠的分子机制。方法 用葡聚糖硫酸钠（DSS）构造小鼠UC模型,将60只小鼠随机分为对照组、DSS组、KT2组、mCRAMP组和美沙拉嗪组5组,每组12只。评估小鼠结肠炎症程度。从对照组、DSS组和KT2组中每组随机选4只小鼠的结肠组织进行测序,鉴定差异表达基因（DEGs）并进行基因富集分析,随后用定量逆转录聚合酶链反应（qRT-PCR）进行验证。结果 KT2组小鼠炎症程度比mCRAMP组和美沙拉嗪组更低;KT2组与DSS组相比,共得到113个DEGs,其中下调DEGs71个,上调DEGs42个。基因富集分析显示下调DEGs主要与胶原代谢有关,上调DEGs主要与生物氧化有关,筛选出差异较大且研究甚少的DEGs进行qRT-PCR验证,发现Foxp3、FUT4、IFRD1、VEGF在DSS干预后表达下调,经抗菌肽KT2治疗后表达上调;Arg2、FXR在DSS干预后表达上调,经抗菌肽KT2治疗后表达下调。结论 抗菌肽KT2治疗UC小鼠效果优于mCRAMP和美沙拉嗪;抗菌肽KT2可能通过上调Foxp3、FUT4、IF...     

Research on the effect and mechanism of antimicrobial peptides HPRP‐A1/A2 work against Toxoplasma gondii infection

With increasing antibiotic resistance and drug safety concerns, novel therapeutics are urgently needed. Antimicrobial peptides are promising candidates that could address the spread of multidrug‐resistant pathogens. HPRP‐A1/A2 are known to display antimicrobial activity against gram‐negative bacteria, gram‐positive bacteria and some pathogenic fungi, but whether HPRP‐A1/A2 work on Toxoplasma gondii (T gondii) is unknown. In this study, we found that the viability of tachyzoites that received HPRP‐A1/A2 treatment was significantly decreased, and there was a reduction in the adhesion to and invasion of macrophages by tachyzoites after HPRP‐A1/A2 treatment. HPRP‐A1/A2 damaged the integrity of tachyzoite membranes, as characterized by membrane disorganization in and cytoplasm outflow from tachyzoites. In addition, in vivo injection with HPRP‐A1/A2 resulted in a significantly decreased number of tachyzoites and an accelerated Th1/Tc1 response, and elicited pro‐inflammatory cytokines in T gondii‐infected mice. Furthermore, HPRP‐A1/A2‐treated splenocytes exhibited a significantly increased Tc1/Th1 response, and HPRP‐A1/A2‐stimulated macrophages inhibited the growth of carboxyfluorescein succinimidyl amino ester (CFSE)‐labelled tachyzoites, which had higher TNF‐α/IL‐12 mRNA levels. Altogether, these results imply that HPRP‐A1/A2 are effective against T gondii through damaging the structure of tachyzoites and inducing a protective immune response, which could offer an alternative approach against T gondii infection.     

胃泌素释放肽前体的研究进展及其临床意义

胃泌素释放肽前体(ProGRP)是一种最近发现的小细胞肺癌(SCLC)的特异性的肿瘤标志物.国内外大量研究发现ProGRP在正常个体的血清水平大都在正常范围,仅在少量的良性疾病患者中超过正常上限,这主要集中在肾功能不全患者.在恶性肿瘤中,血ProGRP水平增高主要集中在神经内分泌肿瘤及肺癌,尤其SCLC.ProGRP对SCLC的敏感度和特异性分别高达79.7%和95%,较神经元特异性烯醇化酶更能准确监测疾病过程和预测肿瘤复发,但神经元特异性烯醇化酶较ProGRP能更好地预示化疗效果.两者具有互补性,联合检测将使SCLC的诊断、预后和监测复发更加准确.     

Research progress on antimicrobial peptides against malaria parasite

Antimicrobial peptides have broad-spectrum antibacterial activity and high thermal stability. Researches prove that they can inhibit the development of Plasmodium or kill them. The paper focuses on research advances in their biological characteristics, natural or synthetic peptides as potential anti-Plasmodium agents in malaria research.     

抗弓形虫靶向抗菌肽的构建及其效应的初步评价

目的构建弓形虫主要表面抗原1单链抗体S1与爪蟾抗菌肽（magainin）的融合基因,在大肠杆菌中诱导表达,观察纯化的靶向抗菌蛋白抗弓形虫感染的效果. 方法根据弓形虫主要表面抗原1单链抗体S1的编码序列设计引物从噬菌粒S1/pIT-2中扩增到S1基因;以其为模板,加入接头抗菌肽序列,采用重叠PCR法扩增得到S1基因与爪蟾抗菌肽的融合基因（S1M）,将其克隆到原核表达载体pET-32c中,构建成S1与爪蟾抗菌肽基因的重组表达质粒S1M/pET-32c;测序验证后转化E.coli BL21,以IPTG诱导表达,用Ni^2＋螯合柱亲和纯化融合蛋白S1M,SDS-PAGE检测融合基因的表达和纯化的融合蛋白S1M;分别采用体内和体外试验观察纯化的靶向抗菌蛋白抗弓形虫感染效果. 结果测序结果表明,成功地将弓形虫主要表面抗原1单链抗体S1与爪蟾抗菌肽的融合基因构建到原核表达载体pET-32c中;SDS-PAGE显示IPTG诱导表达的融合蛋白S1M大小约为43 kDa,与预期的大小相一致,以包涵体的形式存在;通过变性条件下Ni^2＋亲和柱纯化获得S1M重组融合蛋白;体内和体外试验证实,经靶向抗菌蛋白处理过的弓形虫对小鼠的致病能力下降,应用靶向抗菌蛋白的弓形虫感染小鼠的存活时间与对照组相比有明显的提高. 结论以抗弓形虫速殖子人源单链抗体作为靶向分子,以爪蟾抗菌肽作为效应分子,构建成功的靶向抗菌蛋白通过体内、外试验证实,具有一定的抗弓形虫感染的作用,虽然还不能完全杀灭弓形虫,但是在弓形虫生物治疗药物的研制方面进行了有益的探索,为弓形虫病的生物治疗提供了新的思路.     

新的血管生成抑制肽(手性制剂)抗肿瘤血管生成的实验研究

目的 观察一种新的血管生成抑制胜对肿瘤的抑制作用，并探讨其作用机制。方法 体外药效实验，采用MTT法及血管内皮细胞迁移法，体内用Lewis肺癌瘤株皮下接种C57BL／6N小鼠，观察皮下移植瘤生长情况。结果 新的血管生成抑制胜对血管内皮细胞增殖、迁移有明显的抑制作用，在体内使Lewis肺癌皮下移植田体积明显缩小，毛细血管稀少。结论 新的血管生成抑制肽能明显抑制Lewis的肿瘤生长，其机制可能与抑制肿瘤血管生成有关。     

Inoculum effect of antimicrobial peptides

The activity of many antibiotics depends on the initial density of cells used in bacterial growth inhibition assays. This phenomenon, termed the inoculum effect, can have important consequences for the therapeutic efficacy of the drugs, because bacterial loads vary by several orders of magnitude in clinically relevant infections. Antimicrobial peptides are a promising class of molecules in the fight against drug-resistant bacteria because they act mainly by perturbing the cell membranes rather than by inhibiting intracellular targets. Here, we report a systematic characterization of the inoculum effect for this class of antibacterial compounds. Minimum inhibitory concentration values were measured for 13 peptides (including all-D enantiomers) and peptidomimetics, covering more than seven orders of magnitude in inoculated cell density. In most cases, the inoculum effect was significant for cell densities above the standard inoculum of 5 × 10⁵ cells/mL, while for lower densities the active concentrations remained essentially constant, with values in the micromolar range. In the case of membrane-active peptides, these data can be rationalized by considering a simple model, taking into account peptide–cell association, and hypothesizing that a threshold number of cell-bound peptide molecules is required in order to cause bacterial killing. The observed effect questions the clinical utility of activity and selectivity determinations performed at a fixed, standardized cell density. A routine evaluation of the dependence of the activity of antimicrobial peptides and peptidomimetics on the inoculum should be considered.

The minimum inhibitory concentration (MIC) is one of the most common measures for the efficacy of antimicrobial compounds (1, 2). According to the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines, the MIC is the lowest drug concentration that abolishes in vitro bacterial growth during a short period (typically 20 h) when using a standard initial cell density (inoculum) of ∼5 × 10⁵ colony-forming units (CFU)/mL in assays performed in broth (with an acceptable range of 2 × 10⁵ to 8 × 10⁵ CFU/mL for CLSI and 3 × 10⁵ to 7 × 10⁵ CFU/mL for EUCAST) (3–5). The choice of a specific value for the inoculum to be applied is dictated by a need for standardizing the assay in clinical practice (2), albeit bacterial cell densities in clinically relevant infections in vivo range from 1 CFU/mL to 10⁹ CFU/mL (in soft tissue or peritoneal infections) (6–8).Soon after the introduction of penicillin for civilian use in the 1940s, it was realized that the active concentration of antibiotics might need to be increased significantly when higher bacterial cell densities are inoculated in the assay medium (9, 10), a phenomenon termed the “inoculum effect” (IE) (11). The IE can be caused by different mechanisms (12, 13), including enzymatic degradation of the drug (11, 13), a simple consequence of the number of available drug molecules per cell (14, 15), or inhibition of antibiotics by intracellular material released by dead cells, causing enhanced survival of the remaining bacterial population (16). Traditionally, an IE has been defined as a change in MIC greater than or equal to eightfold when an inoculum 100-fold greater than the CLSI recommendation is used, but recent studies have shown that even subtle differences in inoculum may have a dramatic effect on MIC values (17). The IE is commonly examined by determining the MIC; in this assay, the cell density varies by several orders of magnitude with respect to the initial inoculum, during the many hours in which the bacteria are allowed to grow. However, an IE has been demonstrated also under conditions of constant cell density (12).High-density bacterial infections, including septic bloodstream and urinary tract infections, endocarditis, and abscesses, are quite prevalent and lack efficacious therapies (18). Although some reports have contested the therapeutic relevance of the IE (19, 20), several studies have demonstrated its clinical significance, showing that the MICs determined in the standardized assay were ineffective in the clinical treatment of high-density infections (12, 21–28). In some cases, a concentration 1,000-fold higher than the MIC is required to cure the infection (22, 23).While the IE is well characterized for traditional antibiotics, little is known about this phenomenon for other antimicrobial compounds. Antimicrobial peptides (AMPs), sometimes referred to as “host defense peptides,” are produced by all living organisms as a first line of defense against pathogens (29–31). These peptides can have many functions (32), but most of them exert direct bactericidal effects that typically involve perturbation of the membrane integrity of microbial cells (31, 33). The majority of known AMPs are short, amphipathic, and cationic peptides capable of binding selectively to the anionic membranes of bacterial cells (34–37). Most AMPs accumulate on the outer leaflet of cell membranes, thereby perturbing their surface tension (36, 38). When a threshold of membrane-bound molecules is reached, the stress is released by the formation of pores or other membrane defects. This mechanism of action has been termed the “carpet” model (39, 40), and it makes the development of bacterial resistance particularly difficult (30, 41, 42). Therefore, AMPs represent promising lead compounds in the fight against multidrug-resistant bacteria (30, 42, 43), which constitute a dramatically increasing worldwide threat (44), and several peptides are undergoing clinical trials (43).Considering their characteristic mechanism of action as compared to that of commonly used antibiotics, the existence of a pronounced IE is not obvious in the case of AMPs. Surprisingly, the IE within this class of molecules has been investigated only in a handful of studies (45–50), which are summarized in Table 1. In some of these reports (46, 49), the minimum bactericidal concentrations (MBCs; i.e., the minimum drug concentration killing more than 99.9% of the original bacterial cells) (51), rather than the MICs, were measured. While Jones (46) determined the MBC under normal growth conditions, in our previous report (49) we used a minimal medium that ensured a constant cell density. Different media were used also for the MIC assays: salt-free Luria broth (47), Müller–Hinton broth (MHB) (48), or 3–morpholinopropane–1–sulfonic acid (MOPS)–based rich defined media (RDM) (50). In another study concerning the activity of MSI–94 against Pseudomonas aeruginosa (52), quantitative MIC or MBC determinations were not performed, and hence, it is not included in Table 1. However, the time–kill curves obtained at different cell densities were indicative of a significant IE.Table 1.Literature studies of IE for AMPs

抗菌肽的原核表达及应用前景

抗菌肽是具有抗菌活性的一类短肽,广泛存在于生物界,是先天免疫的重要防御成分,其杀细胞机制为在靶细胞膜上穿孔,靶细胞因渗透压改变而死亡。抗菌肽具有广谱抗菌活性,并有抗病毒、抗真菌、抗寄生虫及抗肿瘤等生物活性,有良好的应用前景,使其走向临床的最大挑战是如何用基因工程技术低成本大量生产抗菌肽产品。该文综述了抗菌肽的原核表达研究进展及其应用前景。