Synthetic Lipopeptide Enhances Protective Immunity Against Helicobacter pylori Infection

Abstract

Over fifty percent of the people around the world is infected with Helicobacter pylori ( H. pylori ), which is the main cause of gastric diseases such as chronic gastritis and stomach cancer. H. pylori adhesin A (HpaA), which is a surface-located lipoprotein, is essential for bacterial colonization in the gastric mucosa. HpaA had been proposed to be a promising vaccine candidate against H. pylori infection. However, the effect of non-lipidated recombinant HpaA (rHpaA) to stimulate immune response was not very ideal, and the protective effect against H. pylori infection was also limited. Here, we hypothesized that low immunogenicity of rHpaA may attribute to lacking the immunostimulatory properties endowed by the lipid moiety. In this study, two novel lipopeptides, LP1 and LP2, which mimic the terminal structure of the native HpaA (nHpaA), were synthesized and TLR2 activation activity was confirmed in vitro . To investigate whether two novel lipopeptides could improve the protective effect of rHpaA against the infection of H. pylori , groups of mice were immunized either intramuscularly or intranasally with rHpaA together with LP1 or LP2. Compared with rHpaA alone, the bacterial colonization of the mice immunized with rHpaA plus LP2 via intranasal route was significantly decreased and the expression levels of serum IgG2a, IFN-γ, and IL-17 cytokines in spleen lymphocyte culture supernatant increased obviously, indicating that the enhanced protection of LP2 may be associated with elevated specific Th1 and Th17 responses. In conclusion, LP2 has been shown to improve the protective effect of rHpaA against H. pylori infection, which may be closely related to its ability in activating TLR2 by mimicking the terminal structure of nHpaA.

Development of Different Methods for Preparing Acinetobacter baumannii Outer Membrane Vesicles Vaccine: Impact of Preparation Method on Protective Efficacy

“…Mouse bone marrow cells were isolated from tibia and femurs, and then were cultured in RPMI 1640 medium containing 10% FCS, recombinant murine GM-CSF (6 ng/mL), and IL-4 (20 ng/mL) at 37 • C, 5% CO 2 . The non-adherent cells were removed on day 5 and adherent cells were cultured in a fresh complete medium for another 2 days (34). BMDCs (4 × 10 6 cells) were stimulated with either AbOMV (200 ng) or PBS for 48 h. After three washes, the cells were incubated with FITC-αCD11c, PE-αCD40, APC-αCD80, and PerCP/Cy5.5-αCD86 in the dark for 30 min at 4 • C. Flow cytometry data were acquired with a FACS Canto II (BD Biosciences).…”

Identification of Functional Interactome of Gastric Cancer Cells with Helicobacter pylori Outer Membrane Protein HpaA by HPLC-MS/MS

“…HpaA as an important adhesin consequently assists the life-long colonization of H. pylori to human stomach [17,18]. It has been proved that the amino acid sequences of HpaA were highly conserved [5,8]. However, the basis of binding specificity is still poorly understood due to lack of detailed information.…”

“…H. pylori must be able to colonize gastric epithelial cells to prevent the bacteria from being eliminated by mucus turnover and facilitate evasion from the immune system and further injure the gastric mucosa [2]. The adhesion of H. pylori to the gastric epithelium was mediated by the expression of adhesins and the receptor system [2][3][4], among which H. pylori adhesin (HpaA) as an outer mem-brane protein with approximately 29 kDa detected on the surface and flagellar sheath of H. pylori plays an important role in bacterial adhesion [5][6][7][8].…”

Helicobacter pylori adhesins: HpaA a potential antigen in experimental vaccines for H. pylori

“…Compared to native HpaA (nHpaA), the absence of lipid modification on rHpaA could be related to the weak immunostimulatory and protective effects. To simulate the N‐terminal lipidation structure of nHpaA, two new lipopeptides, LP1 and LP2, were synthesized by Xue et al 98 LP2 unlike LP1 were able to significantly promote DCs maturation, which may be associated with their ability to activate TLR‐2. By using real‐time PCR, the authors reported that H. pylori copy number in the group immunized intranasally with rHpaA + LP2 was significantly lower than in the control group ( P < .01).…”