title: Isocitrate dehydrogenase of Helicobacter pylori potentially induces humoral immune response in subjects with peptic ulcer disease and gastritis.
abstract: BACKGROUND
  H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori.
  
  
  RESULTS
  Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD.
  
  
  CONCLUSIONS
  ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent.
authors.affiliation: Pathogen Evolution Laboratory, Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India.
authors.forename: M Abid
authors.initials: MA
authors.lastname: Hussain
authors.forename: Shaik A
authors.initials: SA
authors.lastname: Naveed
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Sechi
authors.forename: Sarita
authors.initials: S
authors.lastname: Ranjan
authors.forename: Ayesha
authors.initials: A
authors.lastname: Alvi
authors.forename: Irshad
authors.initials: I
authors.lastname: Ahmed
authors.forename: Akash
authors.initials: A
authors.lastname: Ranjan
authors.forename: Sangita
authors.initials: S
authors.lastname: Mukhopadhyay
authors.forename: Niyaz
authors.initials: N
authors.lastname: Ahmed
mesh_terms: D000917:Antibody Formation; D004797:Enzyme-Linked Immunosorbent Assay; D005756:Gastritis / Q000276:immunology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000201:enzymology*; D006801:Humans; D016209:Interleukin-8 / Q000097:blood; D007521:Isocitrate Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D010437:Peptic Ulcer / Q000276:immunology* / Q000382:microbiology
chemical_list: D016209:Interleukin-8; D007521:Isocitrate Dehydrogenase