title: Concurrent proinflammatory and apoptotic activity of a Helicobacter pylori protein (HP986) points to its role in chronic persistence.
abstract: Helicobacter pylori induces cytokine mediated changes in gastroduodenal pathophysiology, wherein, the activated macrophages at the sub-mucosal space play a central role in mounting innate immune response against the antigens. The bacterium gains niche through persistent inflammation and local immune-suppression causing peptic ulcer disease or chronic gastritis; the latter being a significant risk factor for the development of gastric adenocarcinoma. What favors persistence of H. pylori in the gastric niches is not clearly understood. We report detailed characterization of a functionally unknown gene (HP986), which was detected in patient isolates associated with peptic ulcer and gastric carcinoma. Expression and purification of recombinant HP986 (rHP986) revealed a novel, ∼29 kDa protein in biologically active form which associates with significant levels of humoral immune responses in diseased individuals (p<0.001). Also, it induced significant levels of TNF-α and Interleukin-8 in cultured human macrophages concurrent to the translocation of nuclear transcription factor-κB (NF-κB). Further, the rHP986 induced apoptosis of cultured macrophages through a Fas mediated pathway. Dissection of the underlying signaling mechanism revealed that rHP986 induces both TNFR1 and Fas expression to lead to apoptosis. We further demonstrated interaction of HP986 with TNFR1 through computational and experimental approaches. Independent proinflammatory and apoptotic responses triggered by rHP986 as shown in this study point to its role, possibly as a survival strategy to gain niche through inflammation and to counter the activated macrophages to avoid clearance.
authors.affiliation: Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad, India.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Alvi
authors.forename: Suhail A
authors.initials: SA
authors.lastname: Ansari
authors.forename: Nasreen Z
authors.initials: NZ
authors.lastname: Ehtesham
authors.forename: Mohammed
authors.initials: M
authors.lastname: Rizwan
authors.forename: Savita
authors.initials: S
authors.lastname: Devi
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Sechi
authors.forename: Insaf A
authors.initials: IA
authors.lastname: Qureshi
authors.forename: Seyed E
authors.initials: SE
authors.lastname: Hasnain
authors.forename: Niyaz
authors.initials: N
authors.lastname: Ahmed
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D005767:Gastrointestinal Diseases / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D056426:Genetic Loci / Q000235:genetics; D016481:Helicobacter Infections / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D056724:Immunity, Humoral; D018836:Inflammation Mediators / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C491901:FAS protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; D016328:NF-kappa B; D047888:Receptors, Tumor Necrosis Factor, Type I; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor