Serum Immunoglobulin G Immune Response to Helicobacter pylori Antigens in Mongolian Gerbils

Abstract

The Mongolian gerbil model for Helicobacter pylori infection is an animal model that mimics human disease. We examined the serum immune response to H. pylori infection in gerbils by enzyme-linked immunosorbent assay (ELISA) and Western blotting, both with whole-cell (H. pylori) extracts. A total of 66 7-week-old specificpathogen-free male gerbils were inoculated orogastrically with H. pylori strain ATCC 43504. Sera were collected 1, 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sixty-nine noninfected gerbils and their sera were used as controls. The specificity of the ELISA was 95.7%. The frequency of seropositivity increased over time: 2 of 10 (20%), 7 of 10 (70%), and 7 of 7 (100%) samples of sera from inoculated gerbils were positive for H. pylori at 2, 4, and 8 weeks postinoculation, respectively. Western blot assays showed that the primary immunoglobulin G (IgG) response against low-molecular-mass (25-, 30-, and 20-kDa) proteins appeared after a lag period of 2 to 8 weeks after inoculation. Antibodies against 160-, 150-, 110-, 120-, 80-, 66-, and 63-kDa proteins were observed 12 weeks after inoculation. The early reactive 30-kDa protein was identified as a urease ␣ subunit by N-terminal amino acid sequencing. After 26 weeks, two groups of animals could be distinguished: one group developed ulcers (n ‫؍‬ 5), and the other developed hyperplastic polyps without ulcers (n ‫؍‬ 19). Gerbils in the gastric ulcer group showed significantly higher serum anti-H. pylori IgG levels than did gerbils in the hyperplastic group (P ‫؍‬ 0.001) as measured by ELISA. Furthermore, a higher proportion of animals developed antibodies to H. pylori proteins of 26, 25, and 20 kDa in the ulcer group than those animals with hyperplastic polyps (75 to 100% versus 17 to 50%) in Western blot assays. These results highlight the importance of the immune response of the host in the development of H. pylori-related gastric lesions.

Natural History of Gastric Mucosal Cytokine Expression inHelicobacter pyloriGastritis in Mongolian Gerbils

“…Macroscopic and histological changes in H. pylori-inoculated gerbils were similar to those observed in our previous studies (14,16). In brief, there were no visible changes in the gastric mucosa of any uninfected gerbils or gerbils at 2 weeks after inoculation.…”

“…We used H. pylori strain ATCC 43504 (American Type Culture Collection, Manassas, Va.), which has been shown to colonize gerbils consistently for at least 1 year and to cause reproducible mucosal damage (14,16,23). The genotype and/or phenotype with regard to putative virulence factors is cag pathogenicity island positivity, vacA s1-m1 (production of the vacuolating cytotoxin), and functional BabA and OipA.…”

“…After DNase treatment, a 5-g portion of total RNA solution was subjected to reverse transcription with 200 U of Moloney murine leukemia virus reverse transcriptase (Life Technologies, Inc., Gaithersburg, Md.) and 1 mol of oligo(dT) 16 primers/liter. To identify gerbil-specific cytokine cDNA clones, we used a cross-species RT-PCR technique.…”

“…Before euthanasia, blood samples were obtained from the orbital plexus by using hematocrit tubes. Sera were used to measure the titer of anti-H. pylori immunoglobulin G (IgG) antibody as previously described (14,16). The titers of antibody were expressed as an arbitrary index as previously described (14).…”

Long-Term Infection of Mongolian Gerbils withHelicobacter pylori:Microbiological, Histopathological, and Serological Analyses

“…Since Hirayama et al (10) reported the establishment of persistent H. pylori infection in Mongolian gerbils as an animal model in 1996, many investigations on the association between H. pylori and gastric diseases have been carried out (12,17,21,29,30) and, recently, some reported that H. pylori was directly related to gastric carcinogenesis (9,11,32,40). The purposes of almost all of the studies which have ever been carried out were predominantly focused on the measurement of the amount of gastric colonization, the serum antibody titer against H. pylori, and histopathological observation of the stomach.…”