Helicobacter pylori-associated immune thrombocytopenia: Clinical features and pathogenic mechanisms

Abstract

Immune thrombocytopenia (ITP) is an autoimmune disease mediated by anti-platelet autoantibodies. There is growing evidence that the eradication of Helicobacter pylori (H. pylori) effectively increases platelet count in a considerable proportion of ITP patients infected with this bacterium. In the majority of ITP patients responding to H. pylori eradication therapy, the anti-platelet autoantibody response is completely resolved with no relapse for more than 7 years, indicating that the disease is cured. Therefore, adult patients with suspected ITP should be examined for H. pylori infection, and eradication therapy is recommended if the infection is present. Notably, however, the efficacy of H. pylori eradication therapy in ITP patients varies widely among countries, with a higher response rate in Japan compared with the United States and European countries other than Italy. The pathogenesis of H. pylori-associated ITP is still uncertain, although the mechanisms are known to involve multiple factors. H. pylori may modulate the Fcγ-receptor balance of monocytes/macrophages in favor of activating Fcγ receptors, and H. pylori components may mimic the molecular makeup of platelet antigens. Further studies of the pathogenic process of H. pylori-associated ITP may be useful for the development of new therapeutic strategies for ITP.

Helicobacter pylori Eradication in Patients with Immune Thrombocytopenic Purpura: A Review and the Role of Biogeography

“…As most of the studies included in the meta-analysis by Stasi et al [29] considered H. pylori eradication in primarily severe cases of ITP, absolute patient response rates to bacterial eradication treatment may exceed 50% efficacy. In patients that respond to H. pylori eradication therapy, autoplatelet Ab responses are completely resolved, without relapse for over 7 years [95]. However, platelet response to H. pylori eradication for the treatment of ITP appears to correlate with geographic location: higher response rates are observed in Japan and Italy (ranging from 28 to 100%) than in the United States and other European countries (<13%) [95].…”

“…In patients that respond to H. pylori eradication therapy, autoplatelet Ab responses are completely resolved, without relapse for over 7 years [95]. However, platelet response to H. pylori eradication for the treatment of ITP appears to correlate with geographic location: higher response rates are observed in Japan and Italy (ranging from 28 to 100%) than in the United States and other European countries (<13%) [95]. A study from Iran reported that H. pylori eradication led to increased platelet count in those with mild ITP (platelet count >50 × 10 3 μL), but was less successful in patients with severe ITP (platelet count <50 × 10 3 μL) [96].…”

Regulatory and Memory B Lymphocytes in Children With Newly Diagnosed Immune Thrombocytopenia

“…It usually resolves spontaneously within 6 months of diagnosis. However, approximately 20% of newly diagnosed children with ITP progress to a chronic form, defined as persistence of thrombocytopenia for more than 12 months [1].…”

“…It is characterized by a diminished peripheral platelet count (< 100 × 10 9 /L) caused by platelet destruction with an increased risk of mucocutaneous bleeding [1]. It is usually a benign, self-limiting disease in children [2].…”

Recent Guidelines for H. Pylori Eradication Therapy

“…The pathogenesis is unknown but may involve the development of cross reactive antibodies to H. pylori and platelet antigens. [15] H. pylori infection activates monocyte/macrophage function which increases platelet removal. Also, H. pylori infection causes a non-specific stimulation of the immune system which may lead to platelet removal.…”