Overexpression of specific cysteine peptidases confers pathogenicity to a nonpathogenic Entamoeba histolytica clone.
Overexpression of specific cysteine peptidases confers pathogenicity to a nonpathogenic Entamoeba histolytica clone.
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DOI：
10.1128/mbio.00072-13
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发表时间：
2013-03-26
期刊：
影响因子：
6.4
通讯作者：
Bruchhaus I
中科院分区：
文献类型：
--
作者：
Matthiesen J;Bär AK;Bartels AK;Marien D;Ofori S;Biller L;Tannich E;Lotter H;Bruchhaus I
溶组织内阿米巴的半胱氨酸肽酶(CPS)被认为是重要的致病因子。以往的研究发现，在标准的无菌培养条件下，在溶组织型乳杆菌基因组中存在的35个木瓜蛋白酶样EHCP基因中，只有4个(EHCP-A1、EHCP-a2、EHCP-a5和EHCP-A7)高水平表达。在阿米巴肝脓肿(ALA)形成过程中，CPS在溶组埃希菌中的表达情况鲜为人知。在目前的研究中，建立了一种实时荧光定量聚合酶链式反应方法，以确定各种EHCP基因在动物模型ALA形成过程中的表达。在沙土鼠和小鼠模型中检测到四个EHCP基因(EHCP-a3、-a4、-a10和-c13)的表达增加。另外三个EHCP基因(ehcp-a5、-a6和-a7)仅在小鼠模型中表达增加，另外两个Ehcp基因(ehcp-b8和-b9)仅在沙土鼠模型中表达增加。将不能诱导ALA的非致病性溶组埃希氏菌HM-1：IMSS克隆A1的滋养体，导入能够在培养条件下或在ALA形成过程中高水平表达的CP的载体中。有趣的是，EHCP-b8、-b9和-c13的过表达恢复了非致病克隆A1的致病表型，而其他各种多肽酶基因的过表达对该克隆的致病性没有影响。溶组织内阿米巴是一种分布广泛、临床重要的原虫寄生虫。它通常存在于人的肠道中，不会引起临床症状，但可以侵袭肠道粘膜，导致严重的肠道(阿米巴结肠炎)和肠外(阿米巴肝脓肿[ALA])疾病。确定导致寄生虫入侵和疾病形成的因素是该领域的一个主要课题。在这里，我们研究了不同的木瓜蛋白酶样半胱氨酸肽酶(CPS)作为致病因子的作用。我们发现，在ALA形成过程中，一些通常低水平表达的肽酶的表达增加。此外，非致病性阿米巴可以转化为致病性阿米巴，只需通过这些CP的特定过表达。我们的发现加强了CPS作为溶组织埃希氏菌致病因子的重要性。
Cysteine peptidases (CPs) of Entamoeba histolytica are considered to be important pathogenicity factors. Previous studies have found that under standard axenic culture conditions, only four (ehcp-a1, ehcp-a2, ehcp-a5, and ehcp-a7) out of 35 papain-like ehcp genes present in the E. histolytica genome are expressed at high levels. Little is known about the expression of CPs in E. histolytica during amoebic liver abscess (ALA) formation. In the current study, a quantitative real-time PCR assay was developed to determine the expression of the various ehcp genes during ALA formation in animal models. Increased expression of four ehcp genes (ehcp-a3, -a4, -a10, and -c13) was detected in the gerbil and mouse models. Increased expression of another three ehcp genes (ehcp-a5, -a6, and -a7) was detected in the mouse model only, and two other ehcp genes (ehcp-b8 and -b9) showed increased expression in the gerbil model only. Trophozoites of the nonpathogenic E. histolytica HM-1:IMSS clone A1, which was unable to induce ALAs, were transfected with vectors enabling overexpression of those CPs that are expressed at high levels under culture conditions or during ALA formation. Interestingly, overexpression of ehcp-b8, -b9, and -c13 restored the pathogenic phenotype of the nonpathogenic clone A1 whereas overexpression of various other peptidase genes had no effect on the pathogenicity of this clone. Entamoeba histolytica is a widespread and clinically important protozoan parasite. It normally exists in the human intestine without causing clinical symptoms but can invade the intestinal mucosa, which causes serious intestinal (amoebic colitis) and extraintestinal (amoebic liver abscess [ALA]) diseases. The identification of factors responsible for the invasion of the parasite and disease formation is a major topic in the field. Here, we investigate the roles of different papain-like cysteine peptidases (CPs) as pathogenicity factors. We show that the expression of some of the peptidases that are normally expressed at low levels increases during ALA formation. Furthermore, nonpathogenic amoebae can be transformed to pathogenic amoebae, simply by specific overexpression of some of these CPs. Our findings reinforce the importance of CPs as pathogenicity factors of E. histolytica.