A M _r 34,000 proinflammatory outer membrane protein ( oipA ) of Helicobacter pylori

Abstract

The complete genome sequence revealed a family of 32 outer membrane proteins (OMPs) in Helicobacter pylori. We examined the effect of four OMPs (HP0638, HP0796, HP1501, and babA2 ) on the production of the proinflammatory cytokine, IL-8. Mutants of the four OMPs, as well as cagE and galE from H. pylori from the U.S. and Japan, were constructed by inserting a chloramphenicol-resistant cassette into the gene. Twenty-two pairs of parental and mutant H. pylori strains, as well as 160 clinical isolates (80 from Japanese and 80 from U.S.), were cocultured with gastric cancer cell lines. IL-8 production in the supernatant and adhesion was assayed by ELISA. HP0796, HP1501, babA2 , and galE gene knockouts had no significant effect on IL-8 production. Knockout of the HP0638 gene in 81% of cag -positive strains reduced IL-8 production approximately 50%. The three cag -positive strains in which IL-8 levels were unchanged by HP0638 knockout had five or seven CT dinucleotide repeats in the 5′ region, resulting in a frame shift and truncation. Strains with naturally inactive HP0638 gene were all from the U.S.; Japanese strains were always “on” and thus, on average, may be more virulent. Although cag -negative isolates produced a limited IL-8 response, cag -negative strains that contained a functional HP0638 gene produced more than 3-fold greater IL-8 than cag -negative nonfunctional HP0638 strains. We hypothesize that functional HP0638 gene may be an important virulence factor in relation to the risk of clinically significant outcomes of H. pylori infection. We denote HP0638 gene as outer inflammatory protein ( oipA ).

Pattern of Transcription Factor Activation in Helicobacter pylori–Infected Mongolian Gerbils

“…Long-term studies (eg, 18 months) used wild-type (WT) strain TN2GF4, whereas the cag PAI mutant (isogenic cagE mutant) was used for shortterm studies (ie, 1 and 3 months). The isogenic cagE mutant was constructed previously 10 and was chloramphenicol resistant.…”

Correlation betweenHelicobacter pyloriOipA Protein Expression andoipAGene Switch Status

“…The Helicobacter pylori outer inflammatory protein, OipA, is an important virulence factor associated with enhanced interleukin-8 secretion and increased inflammation in vitro as well as the clinically important presentation of peptic ulcer (11,13,14). Expression of OipA is regulated by the slipped-strand repair mechanism based on the number of CT dinucleotide repeats in the 5Ј region of the oipA gene (switch on ϭ functional and switch off ϭ nonfunctional) (11), such that gene switch status may affect bacterial characteristics such as virulence.…”

“…Expression of OipA is regulated by the slipped-strand repair mechanism based on the number of CT dinucleotide repeats in the 5Ј region of the oipA gene (switch on ϭ functional and switch off ϭ nonfunctional) (11), such that gene switch status may affect bacterial characteristics such as virulence. Isolates that contain the cag pathogenicity island (CagA is a marker) typically also have oipA with functional status "on" (1,3,12,13).…”

“…H. pylori isolates from Japan and the United States were used to ensure that slight sequence differences in oipA sequences between strains from Asia and Western countries did not influence the results (1,11). We studied 105 isolates with oipA gene status "on" and 45 with status "off" as determined by PCR-based sequencing of the signal region of the oipA as previously described (11). The strains were selected to consist of equal numbers from patients with gastritis only, duodenal ulcer, and gastric cancer.…”

“…The protocols under which the strains were obtained were approved by local ethics committees, and written informed consent was obtained. Controls consisted of isogenic oipA and cagE mutant strains (11).…”