探討幽門螺旋桿菌熱休克蛋白 60 對人類周邊血液單核球抑制增生活性之位置

Abstract

Chronic infection with Helicobacter pylori (H. pylori) is recognized as the cause of upper gastrointestinal disorder, such as chronic active gastritis, peptic ulcer diseases, mucosa-associated lymphoid tissue (MALT) lymphoma and is an important risk factor for the development of gastric cancer. Recently, it was also reported that heat shock protein 60 of H. pylori (HpHsp60) are associated with gastric inflammation. Hsp60 of H. pylori has been found that it can induce immune cells to express the strong pro-inflammatory cytokines, such as TNF-α, IL-8, IL-6, and IFN-γ. Interestingly, some literatures indicated that Hsp60 derived from different species seem to be related to the regulation of immune responses. For example, the Hsp60 of S. japonicum can generate regulatory T cell (Treg) and suppress immunity. Our lab’s previous studies have shown that H. pylori Hsp60 can decrease human peripheral blood mononuclear cells (PBMCs) proliferation rate, inhibit cytokine secretion, and induce cell cycle arrest. These findings indicate that HpHsp60 may have two functions, induction of the inflammation and immune suppression. The mechanisms of HpHsp60-induced inflammation in which TLR-2 pathway is the major signaling pathway have been confirmed. On the other hand, the amino acid domains 300-435 of H. pylori Hsp60 is associated with induction of IL-8 in monocytic cell has been explored. What domain of the HpHsp60-induced immune suppression is still remains unknown. Thus, the aim in this study is to investigate which domains of HpHsp60 function for immune suppression. For the purpose of this study, we construct whole Hsp60 (amino acid sequence: 1-547) and five partial domains (sequence: a. a. 1-200, 101-200, 1-250, 200-300, 300-547). Since Treg cells inhibit proliferation of CD4+ T cells either via IL-10 or TGF-β production, we demonstrate which domains of HpHsp60 function for immune suppression by monitoring the two cytokines (IL-10 and TGF-β) expression. The preliminary data showed rHsp60s (sequence: a. a. 101-200 and 300-547) induced IL-10 secretion. The monoclonal Abs against rHsp60 (sequence: a. a. 101-200) to prove that rHsp60 (sequence: a. a. 101-200) could down-regulate the immune responses. These results propose that the sequence from 101 to 200 of H. pylori Hsp60 may be closely associated with immune suppression.