Objective: Eradication of Helicobacter pylori was reported to increase the platelet counts in some H. pylori-positive patients with chronic idiopathic thrombocytopenic purpura (cITP). However, the efficacy of the eradication was quite different according to the previous reports. To determine whether H. pylori infection can contribute to cITP, we performed a randomized controlled trial for the first time. In addition, to investigate the possible pathogenic mechanisms and to predict the platelet response after eradication of H. pylori in each cITP patient, several H. pylori virulence factors, the urease activities of the infected H. pylori strains, and the titers of anti-CagA IgG antibodies were analyzed.
Methods: Patients with cITP underwent gastroscopy and gastric H. pylori infection was confirmed by culture. H. pylori-positive cITP patients were randomly assigned to either the eradication or the non-eradication group. The eradication group received a standard antibiotic therapy for H. pylori. Response to treatment was defined as complete (CR) if the platelet count was above 150x10(3)/microl and partial (PR) if the platelet count increased by more than 50x10(3)/microl above the pretreatment count. The virulence factors were investigated by PCR and PCR-based direct sequencing. Anti-CagA IgG antibody titer of each patient's serum was measured by ELISA.
Results: Of the 36 ITP patients, 25 (69.4%) were positive for H. pylori and eradication was achieved in 84.6% of these patients. The platelet response was significantly different between the eradication group (46.2%) and the non-eradication group (0%). No significant differences were found in clinical factors between the responders and the nonresponders. H. pylori virulence factors and the urease activity were not associated with the response. The titers of anti-CagA antibodies in the responders were significantly higher than those in the nonresponders (p=0.04).
Conclusions: H. pylori eradication treatment is a favorable therapeutic option for H. pylori-positive patients with cITP. Moreover, an ELISA titer of serum anti-CagA antibody may be a good predictor of platelet recovery, and immunological reaction between platelet and anti-CagA antibodies may have some relation to the pathogenesis of H. pylori-positive patients with cITP.