The outer membrane protein X from Escherichia coli exhibits immune properties.
Outer membrane proteins (OMP) are expressed in Gram-negative bacterial cell wall. OmpA from Klebsiella pneumoniae (KpOmpA) has been shown to bind and to activate selectively antigen presenting cells (APCs), eliciting protective CTL responses. In this study, we investigated whether OmpX, another member of the OMP family and structurally related to OmpA, exhibits the same immune properties. Using recombinant OmpX from Escherichia coli (EcOmpX), we report that EcOmpX binds to and is internalized by human APCs. However, EcOmpX does not activate APCs. EcOmpX acts as an efficient carrier protein as it induces a potent and Th1/Th2 mixed anti-TNP humoral response. However, adjuvant is required to generate a protective anti-tumoral immune response in mice injected with a tumor model antigen coupled to EcOmpX. Collectively, these data show that EcOmpX is recognized by innate cells but does not activate them, suggesting that EcOmpX does not provide a signal danger to APCs. In conclusion, this study provides information on the molecular mechanisms involved in the recognition and activation of innate cells by bacterial outer membrane proteins.
Maisnier-Patin
Karine
K
Centre d'Immunologie Pierre Fabre, 5 Avenue Napoléon III, 74160 Saint Julien en Genevois, France.
Malissard
Martine
M
Jeannin
Pascale
P
Haeuw
Jean François
JF
Corbière
Jean-Claude
JC
Hoeffel
Guillaume
G
Gauchat
Jean-François
JF
Nguyen
Thien
T
Saez
José M
JM
Delneste
Yves
Y
D000818:Animals; D000912:Antibodies, Neoplasm / Q000096:biosynthesis; D000917:Antibody Formation / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000276:immunology*; D001710:Biotin; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004926:Escherichia coli / Q000276:immunology* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000276:immunology*; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006241:Haptens / Q000276:immunology; D006801:Humans; D006867:Hydrolases; D007111:Immunity, Cellular / Q000276:immunology; D008262:Macrophage Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D009000:Monocytes / Q000276:immunology; D009368:Neoplasm Transplantation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology; D013745:Tetanus Toxoid / Q000276:immunology
D000912:Antibodies, Neoplasm; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D006241:Haptens; D011994:Recombinant Proteins; D013745:Tetanus Toxoid; C482905:OmpX protein, E coli; D001710:Biotin; D006867:Hydrolases; D016650:Fluorescein-5-isothiocyanate