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The miniferritin HP-NAP of Helicobacter pylori was originally described as a neutrophil-activating protein because of the capacity to activate neutrophils to generate oxygen radicals and adhere to endothelia. Currently, the main feature for which HP-NAP is known is the ability to promote Th1 responses and revert the immune suppressive profile of macrophages. In this review, we discuss the immune modulating properties of the protein regarding the H. pylori infection and the evidence that support the potential clinical application of HP-NAP in allergy and cancer immunotherapy.

Human syphilis is a multistage disease, with diverse and wide-ranging manifestations caused by Treponema pallidum. Despite the fact that a cell-mediated immune response takes part in the course of syphilis, T. pallidum often manages to evade host immunity and, in untreated individuals, may trigger chronic infection. With this study, we demonstrate for the first time, to our knowledge, that Treponema pallidum induces a regulatory T (Treg) response in patients with secondary syphilis and we found that the miniferritin TpF1, produced by the bacterium, is able to expand this response and promote the production of TGF-β. Accordingly, TpF1 stimulates monocytes to release IL-10 and TGF-β, the key cytokines in driving Treg cell differentiation. Interestingly, we also found that TpF1 stimulates monocytes to synthesize and release several proinflammatory cytokines, such as TNF-α, IL-6, and IL-1β, the latter following the activation of the multiprotein complex inflammasome. Collectively, these data strongly support a central role for TpF1 both in the inflammation process, which occurs in particular during the early stage of syphilis, and in the long-term persistence of the spirochete within the host by promoting Treg response and TGF-β production.

OBJECTIVE: Human Lyme arthritis caused by Borrelia burgdorferi is characterized by an inflammatory infiltrate that consists mainly of neutrophils and T cells. This study was undertaken to evaluate the role of the innate and acquired immune responses elicited by the neutrophil-activating protein A (NapA) of B burgdorferi in patients with Lyme arthritis. METHODS: Serum anti-NapA antibodies were measured in 27 patients with Lyme arthritis and 30 healthy control subjects. The cytokine profile of synovial fluid T cells specific for NapA was investigated in 5 patients with Lyme arthritis. The cytokine profile induced by NapA in neutrophils and monocytes was also investigated. RESULTS: Serum anti-NapA antibodies were found in 48% of the patients with Lyme arthritis but were undetectable in the healthy controls. T cells from the synovial fluid of patients with Lyme arthritis produced interleukin-17 (IL-17) in response to NapA. Moreover, NapA was able to induce the expression of IL-23 in neutrophils and monocytes, as well as the expression of IL-6, IL-1beta, and transforming growth factor beta (TGFbeta) in monocytes, via Toll-like receptor 2. CONCLUSION: These findings indicate that NapA of B burgdorferi is able to drive the expression of IL-6, IL-1beta, IL-23, and TGFbeta by cells of the innate immune system and to elicit a synovial fluid Th17 cell response that might play a crucial role in the pathogenesis of Lyme arthritis.

Helicobacter pylori induces an acute inflammatory response followed by a chronic infection of the human gastric mucosa characterized by infiltration of neutrophils/polymorphonuclear cells (PMNs) and mononuclear cells. The H. pylori neutrophil-activating protein (HP-NAP) activates PMNs, monocytes, and mast cells, and promotes PMN adherence to the endothelium in vitro. By using intravital microscopy analysis of rat mesenteric venules exposed to HP-NAP, we demonstrated, for the first time in vivo, that HP-NAP efficiently crosses the endothelium and promotes a rapid PMN adhesion. This HP-NAP-induced adhesion depends on the acquisition of a high affinity state of β2 integrin on the plasma membrane of PMNs, and this conformational change requires a functional p38 MAPK. We also show that HP-NAP stimulates human PMNs to synthesize and release a number of chemokines, including CXCL8, CCL3, and CCL4. Collectively, these data strongly support a central role for HP-NAP in the inflammation process in vivo: indeed, HP-NAP not only recruits leukocytes from the vascular lumen, but also stimulates them to produce messengers that may contribute to the maintenance of the flogosis associated with the H. pylori infection.

BACKGROUND & AIMS: Progressive liver disease is a severe complication of cystic fibrosis, a genetic disease characterized by impaired epithelial adenosine 3',5'-cyclic monophosphate-dependent secretion caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). In the liver, CFTR is expressed in cholangiocytes and regulates the fluid and electrolyte content of the bile. Glibenclamide, a sulfonylurea and a known CFTR inhibitor, paradoxically stimulates cholangiocyte secretion. We studied the molecular mechanisms underlying this effect and whether glibenclamide could restore cholangiocyte secretion in cystic fibrosis. METHODS: NRC-1 cells, freshly isolated rat cholangiocytes, isolated rat biliary ducts, and isolated biliary ducts from CFTR-defective mice (Cftr tm1Unc ) were used to study fluid secretion (by video-optical planimetry), glibenclamide-induced secretion (by high-performance liquid chromatography in cell culture medium), intracellular pH and intracellular Ca 2+ concentration transients [2'7'-bis(2-carboxyethyl)-5,6,carboxyfluorescein-acetoxymethylester and Fura-2 f-AM (5-Oxazolecarboxylic acid, 2-(6-(bis(2-((acetyloxy)methoxy)-2-oxoethyl)amino)-5-(2-(2-(bis(2-((acetyloxy)methoxy)-2-oxoethyl)amino)-5-methylphenoxy)ethoxy)-2-benzofuranyl)-, (acetyloxy)methyl ester) microfluorometry], gene expression (by reverse-transcription polymerase chain reaction), and changes in membrane capacitance (by patch-clamp experiments). RESULTS: Stimulation of cholangiocyte secretion by glibenclamide and tolbutamide required Cl - and was mediated by the sulfonylurea receptor 2B. Glibenclamide-induced secretion was blocked by inhibitors of exocytosis (colchicine, wortmannin, LY294002, and N -ethylmaleimide) and by inhibitors of secretory granule acidification (vanadate, bafilomycin A1, and niflumic acid) but was Ca 2+ and depolarization independent; membrane capacitance measurements were consistent with stimulation of vesicular transport and fusion. Glibenclamide, unlike secretin and forskolin, was able to stimulate secretion in Cftr tm1Unc mice, thus indicating that this secretory mechanism was preserved. CONCLUSIONS: The ability of glibenclamide to stimulate secretion in CFTR-defective mice makes sulfonylureas a model class of compounds to design drugs useful in the treatment of cystic fibrosis with liver impairment and possibly of other cholestatic diseases.

The VacA cytotoxin, produced by toxigenic strains of Helicobacter pylori, induces the formation of large vacuoles highly enriched in the small GTPase rab7. To probe the role of rab7 in vacuolization, HeLa cells were transfected with a series of rab mutants and exposed to VacA. Dominant-negative mutants of rab7 effectively prevented vacuolization, whereas homologous rab5 and rab9 mutants were only partially inhibitory or ineffective, respectively. Expression of wild-type or GTPase-deficient rab mutants synergized with VacA in inducing vacuolization. In vitro fusion of late endosomes was enhanced by active rab7 and inhibited by inactive rab7, consistent with vacuole formation by merging of late endosomes in a process that requires functional rab7. Taken together, the effects of overexpressed rab proteins described here indicate that continuous membrane flow along the endocytic pathway is necessary for vacuole growth.