DETECTION OF HELICOBACTER-PYLORI GENE-EXPRESSION IN HUMAN GASTRIC-MUCOSA

Mucosal and systemic immunologic recognition of cogA by Helicobacter p ylori-infected individuals is associated with peptic ulcer disease; ho wever, in the laboratory, expression of cogA is subject to artificial conditions which may not accurately reflect the conditions in host tis sues. Gastric antral and body biopsy specimens and serum for anti-H. p glori immunoglobulin G serology were obtained from 42 patients. Biopsy specimens were studied by histology, culture, and reverse transcripti on PCR (RT-PCR). Oligonucleotide primers specific for H. pylori (16S r RNA, ureA, and cagA) were used to detect bacterial mRNA in gastric bio psy specimens. PCR was performed on DNA from corresponding H. pylori i solates to detect genomic 16S rRNA, ureA, and cagA. Of the 42 patients from whom clinical specimens were obtained, 25 were infected with H. pylori on the basis of both serology and histology or culture (i,e., t issue positive); 13 were negative by serology, histology, and culture; and 4 were positive by serology only. RT-PCR with 16S rRNA primers de tected 24 of 25 tissue-positive and 0 of 17 tissue-negative patients ( P < 0.001). RT-PCR with ureA primers detected 16 of 25 tissue-positive and 0 of 17 tissue-negative patients (P < 0.001). CagA mRNA was detec ted by RT-PCR in 14 of 25 gastric biopsy specimens in the tissue-posit ive group and in 0 of 17 gastric biopsy specimens in the tissue-negati ve group. PCR of genomic DNA for the presence of the cagA gene in the corresponding bacterial isolates correlated absolutely with cagA gene expression in gastric tissue. These results indicate that RT-PCR is a sensitive and specific method for the detection of the presence of H. pylori and the expression of H. pglori genes in human gastric tissue. Detection of H. pylori gene expression in vivo by this approach may co ntribute to improving the diagnosis and understanding the pathogenesis of H. pylori infections.