The C-terminal region of HPNAP activates neutrophils and promotes their adhesion to endothelial cells

The Role of Helicobacter pylori Neutrophil-Activating Protein in the Pathogenesis of H. pylori and Beyond: From a Virulence Factor to Therapeutic Targets and Therapeutic Agents

Helicobacter pylori neutrophil-activating protein (HP-NAP), a major virulence factor of H. pylori, plays a role in bacterial protection and host inflammation. HP-NAP activates a variety of innate immune cells, including neutrophils, monocytes, and mast cells, to induce their pro-oxidant and pro-inflammatory activities. This protein also induces T-helper type 1 (Th1) immune response and cytotoxic T lymphocyte (CTL) activity, supporting that HP-NAP is able to promote gastric inflammation by activation of adaptive immune responses. Thus, HP-NAP is a potential therapeutic target for the treatment of H. pylori-induced gastric inflammation. The inflammatory responses triggered by HP-NAP are mediated by a PTX-sensitive G protein-coupled receptor and Toll-like receptor 2. Drugs designed to block the interactions between HP-NAP and its receptors could alleviate the inflammation in gastric mucosa caused by H. pylori infection. In addition, HP-NAP acts as a promising therapeutic agent for vaccine development, allergy treatment, and cancer immunotherapy. The high antigenicity of HP-NAP makes this protein a component of vaccines against H. pylori infection. Due to its immunomodulatory activity to stimulate the Th1-inducing ability of dendritic cells, enhance Th1 immune response and CTL activity, and suppress Th2-mediated allergic responses, HP-NAP could also act as an adjuvant in vaccines, a drug candidate against allergic diseases, and an immunotherapeutic agent for cancer. This review highlights the role of HP-NAP in the pathogenesis of H. pylori and the potential for this protein to be a therapeutic target in the treatment of H. pylori infection and therapeutic agents against H. pylori-associated diseases, allergies, and cancer.

Dps Is a Universally Conserved Dual-Action DNA-Binding and Ferritin Protein

The DNA-binding protein from starved cells, Dps, is a universally conserved prokaryotic ferritin that, in many species, also binds DNA. Dps homologs have been identified in the vast majority of bacterial species and several archaea. Dps also may play a role in the global regulation of gene expression, likely through chromatin reorganization. Dps has been shown to use both its ferritin and DNA-binding functions to respond to a variety of environmental pressures, including oxidative stress. One mechanism that allows Dps to achieve this is through a global nucleoid restructuring event during stationary phase, resulting in a compact, hexacrystalline nucleoprotein complex called the biocrystal that occludes damaging agents from DNA. Due to its small size, hollow spherical structure, and high stability, Dps is being developed for applications in biotechnology.

Nanoparticle-based immunotherapy of breast cancer using recombinant Helicobacter pylori proteins

Breast cancer is the most common cancer in women worldwide and is associated with substantial medical and economic burden. We report the development of a hybrid immunotherapeutic system based on recombinant Nap protein from Helicobacter pylori (HP-Nap) for the treatment of breast tumors. Chitosan nanoparticles with pseudo-spherical morphology and positive zeta potential were synthesized as carriers for HP-Nap. In vitro study was performed on mouse breast cancer cell line (4T1) and human breast cancer cell lines (MCF7). In vivo study was done on 4T1 tomural mice. TUNEL assay and real time PCR test were performed on tumor mice receiving the nanoparticle treatment. The nanoparticle-protein complex induced apoptosis in vitro in cultured breast cancer cells. In-vivo studies on inbred, female BALB/c mice confirmed the shrinkage of tumor mass after administration of the nanoparticle complex containing HP-Nap. The TUNEL assay further confirmed apoptosis in extracted mouse breast cancer cells. A decrease in the expression of VEGF and MMP9 genes was observed in 4T1 cells as shown by real time PCR. Our data suggesting that the therapeutic nanocomplex may have led to decreased tumor growth in mice through changing the production rate of cytokines and increasing tumoricidal activities of the immune system.

Helicobacter pylori neutrophil-activating protein: From molecular pathogenesis to clinical applications

Helicobacter pylori (H. pylori) neutrophil-activating protein (HP-NAP) was originally identified as a virulence factor of H. pylori for its ability to activate neutrophils to generate respiratory burst by releasing reactive oxygen species. Later on, HP-NAP was also found to be involved in the protection of H. pylori from DNA damage, supporting the survival of H. pylori under oxidative stress. This protein is highly conserved and expressed by virtually all clinical isolates of H. pylori. The majority of patients infected with H. pylori produced antibodies specific for HP-NAP, suggesting its important role in immunity. In addition to acting as a pathogenic factor by activating the innate immunity through a wide range of human leukocytes, including neutrophils, monocytes, and mast cells, HP-NAP also mediates adaptive immunity through the induction of T helper cell type I responses. The pro-inflammatory and immunomodulatory properties of HP-NAP not only make it play an important role in disease pathogenesis but also make it a potential candidate for clinical use. Even though there is no convincing evidence to link HP-NAP to a disease outcome, recent findings supporting the pathogenic role of HP-NAP will be reviewed. In addition, the potential clinical applications of HP-NAP in vaccine development, clinical diagnosis, and drug development will be discussed.

Development of monoclonal antibody-based immunoassays for detection of Helicobacter pylori neutrophil-activating protein

Neutrophil-activating protein (NAP) is a major virulence factor expressed by Helicobacter pylori isolates associated with severe chronic gastroduodenal inflammation and peptic ulcers. NAP is one of the main protective antigens and a target for vaccine development against Helicobacter infection. In addition, NAP is a potent immune stimulator with potential application as a general vaccine adjuvant and in treatment of allergic diseases and cancer immunotherapy. NAP-specific immunoassays are needed for both H. pylori diagnostics and characterization of NAP-based vaccines and immunomodulatory preparations. We generated a panel of NAP-specific monoclonal antibodies (MAbs) by immunization of BALB/c mice with synthetic NAP peptides. The antibody reactivity against recombinant or native NAP antigen was characterized by enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluorescence. A sensitive capture ELISA was developed using MAbs 23C8 and 16F4 (directed against different NAP epitopes) for detection of native or measles virus (MV) vector-expressed recombinant NAP in a concentration range of 4 ng/ml to 2000 ng/ml. MAb 23C8 antigen-binding depends on Tyr101 in a variable amino acid sequence of the NAP molecule, indicating the existence of antigenic variants among H. pylori strains. MAb 16F4 reacted with NAP from different H. pylori strains and was a sensitive tool for detection of small amounts of isolated NAP antigen or whole bacteria by immunoblotting or immunofluorescence. In conclusion, MAb-based immunoassays are highly specific and sensitive for detection of native NAP antigen and recombinant NAP immunostimulatory transgenes expressed by replication competent virus vectors.

Helicobacter pylori neutrophil activating protein as target for new drugs against H. pylori inflammation

Helicobacter pylori (H. pylori) infection is among the most common human infections and the major risk factor for peptic ulcer disease and gastric cancer. Within this work we present the implication of C-terminal region of H. pylori neutrophil activating protein in the stimulation of neutrophil activation as well as the evidence that the C-terminal region of H. pylori activating protein is indispensable for neutrophil adhesion to endothelial cells, a step necessary to H. pylori inflammation. In addition we show that arabino galactan proteins derived from chios mastic gum, the natural resin of the plant Pistacia lentiscus var. Chia inhibit neutrophil activation in vitro.

Dps-like proteins: structural and functional insights into a versatile protein family

Dps-like proteins are key factors involved in the protection of prokaryotic cells from oxidative damage. They act by either oxidizing iron to prevent the formation of oxidative radicals or by forming Dps-DNA complexes to physically protect DNA. All Dps-like proteins are characterized by a common three-dimensional architecture and are found as spherical dodecamers with a hollow central cavity. Despite their structural similarities, recent biochemical and structural data have suggested different functions among members of the family that range from protection inside the cells in response to various stress signals to adhesion and virulence during bacterial infections. Moreover, the Dps-like proteins have lately attracted considerable interest in the field of nanotechnology owing to their ability to act as protein cages for iron and various other metals. A better understanding of their function and mechanism could therefore lead to novel applications in biotechnology and nanotechnology.