Effect of Helicobacter pylori cdrA on interleukin-8 secretions and nuclear factor kappa B activation

AIM： To investigate genetic diversity of Helicobacter pylori （H. pylorl） cell division-related gene A （cdrA） and its effect on the host response.METHODS： Inactivation of H. py/ori cdrA, which is involved in ceil division and morphological elonga- tion, has a role in chronic persistent infections. Ge- netic property of H. pylori cdrA was evaluated using polymerase chain reaction and sequencing in 128 （77 American and 51 Japanese） clinical isolates obtained from 48 and 51 patients, respectively. Enzyme-linked immunosorbent assay was performed to measure in- terleukin-8 （IL-8） secretion with gastric biopsy speci- mens obtained from American patients colonized with cdrA-positive or -negative strains and AGS cells co- cultured with wild-type HPK5 （cdrA-positive） or its de- rivative HPKT510 （cdrA-disruptant）. Furthermore, the cytotoxin-associated gene A （cagA） status （transloca- tion and phosphorylation） and kinetics of transcription factors [nuclear factor-kappa B （NF-~：B） and inhibition kappa B] were investigated in AGS cells co-cultured with HPK5, HPKT510 and its derivative HPKSCA （cagA- disruptant） by western blotting analysis with immuno- precipitation. RESULTS： Genetic diversity of the H. pylori cdrA gene demonstrated that the cdrA status segregated into two categories including four allele types, cdrA-positive （al- lele types, I and 11 ） and cdrA-negative （allele types; 111 and IV） categories, respectively. Almost all Japanese isolates were cdrA-positive （ 1 ： 7.8% and 11 ： 90.2%）, whereas 16.9% of American isolates were cdrA-positive （11） and 83.1% were cdrA-negative （nl： 37.7% and IV： 45.5%）, indicating extended diversity of cdrA in individual American isolates. Comparison of each isolate from different regions （antrum and corpus） in the stomach of 29 Americans revealed that cdrA status was identical in both isolates from different regions in 17 cases. However, 12 cases had a different cdrA al- lele and 6 of them exhibited a different cdrA category between two regions in the stomach. Furthermore, in 5 of the 6 cases possessing a different cdrA category, cdrA-negative isolate existed in the corpus, suggesting that cdrA-negative strain is more adaptable to coloni- zation in the corpus. IL-8 secretions from AGS revealed that IL-8 levels induced by a cdrA-disrupted HPKT510 was significantly lower （P 〈 0.01） compared to wild- type HPK5： corresponding to 50%-60% of those of wild-type HPK5. These data coincided with in vivo data that an average value of IL-8 in biopsy specimens from cdrA-positive and cdrA-negative groups was 215.6 and 135.9 pg/mL, respectively. Western blotting analysis documented that HPKT510 had no effect on CagA translocation and phosphorylation, however, nuclear accumulation of NF-κB was lower by HPKT510 com- pared to HPK5. CONCLUSION： Colonization by a cdrA-negative or cdrA-dysfunctional strain resulted in decreased IL-8 production and repression of NF-κB, and hence, atten- uate the host immunity leading to persistent infection.