Peek R M, van Doorn L J, Donahue J P, Tham K T, Figueiredo C, Blaser M J, Miller G G
Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2279, USA.
Infect Immun. 2000 Oct;68(10):5488-95. doi: 10.1128/IAI.68.10.5488-5495.2000.
The iceA locus of Helicobacter pylori includes one of two mutually exclusive gene families, iceA1 and iceA2. Colonization with iceA1 strains is associated with enhanced acute mucosal inflammation, and adherence to gastric epithelial cells in vitro induces expression of iceA1 but not iceA2 mRNA; however, both transcripts can be detected in vivo. The aim of this study was to determine whether differing levels of iceA transcription in vivo may contribute to disease pathogenesis. RNA from 41 H. pylori-positive gastric biopsy specimens was reverse transcribed to cDNA. Quantitative PCR was performed using biotinylated iceA1, iceA2, and 16S rRNA primers, and binding of biotinylated products to streptavidin-coated plates was detected by hybridization with a fluorescein-labeled probe. iceA genotypes were determined by PCR and sequence analysis. All 41 samples contained detectable H. pylori 16S rRNA, with similar levels in iceA1- (n = 10) and iceA2 (n = 31)-colonized patients (P = 0.34). Biopsy specimens from four (40%) and 19 (61%) persons colonized with iceA1 or iceA2 strains, respectively, had detectable iceA RNA. Acute inflammatory scores were significantly higher in iceA1 RNA-positive patients than in iceA1 RNA-negative, iceA2 RNA-positive, or iceA2 RNA-negative subjects (P </= 0.05 for each). Within the iceA2 RNA-positive group, H. pylori strains with a single 35-amino-acid cassette were associated with significantly higher mucosal iceA2 transcript levels (P = 0.014 versus strains with two cassettes). These results indicate that the levels of transcription of H. pylori iceA1 and iceA2 and of 16S rRNA are independent and that particular iceA2 gene structures are associated with enhanced transcription. The finding that iceA1 transcription levels are significantly associated with the intensity of neutrophilic infiltration suggests that heterogeneity in inflammatory scores among persons colonized with H. pylori iceA1 strains reflects levels of iceA1 transcription in vivo.
幽门螺杆菌的iceA基因座包含两个互斥基因家族之一，即iceA1和iceA2。iceA1菌株的定植与急性黏膜炎症增强相关，并且在体外对胃上皮细胞的黏附可诱导iceA1而非iceA2 mRNA的表达；然而，两种转录本在体内均可检测到。本研究的目的是确定体内iceA转录水平的差异是否可能导致疾病发病机制。来自41例幽门螺杆菌阳性胃活检标本的RNA被逆转录为cDNA。使用生物素化的iceA1、iceA2和16S rRNA引物进行定量PCR，并通过与荧光素标记的探针杂交检测生物素化产物与链霉亲和素包被板的结合。通过PCR和序列分析确定iceA基因型。所有41个样本均含有可检测到的幽门螺杆菌16S rRNA，iceA1定植（n = 10）和iceA2定植（n = 31）患者中的水平相似（P = 0.34）。分别有4例（40%）和19例（61%）被iceA1或iceA2菌株定植的人的活检标本中可检测到iceA RNA。iceA1 RNA阳性患者的急性炎症评分显著高于iceA1 RNA阴性、iceA2 RNA阳性或iceA2 RNA阴性的受试者（每组P≤0.05）。在iceA2 RNA阳性组中，具有单个35个氨基酸盒的幽门螺杆菌菌株与黏膜iceA2转录本水平显著更高相关（与具有两个盒的菌株相比，P = 0.014）。这些结果表明，幽门螺杆菌iceA1和iceA2以及16S rRNA的转录水平是独立的，并且特定的iceA2基因结构与转录增强相关。iceA1转录水平与嗜中性粒细胞浸润强度显著相关这一发现表明，被幽门螺杆菌iceA1菌株定植的个体之间炎症评分的异质性反映了体内iceA1的转录水平。
