Identification of secretory immunoglobulin A antibody targets from human milk in cultured cells infected with enteropathogenic Escherichia coli (EPEC)

• Published in: Microbial pathogenesis Vol. 64; pp. 48 - 56
• Main Authors: Gavilanes-Parra, Sandra, Mendoza-Hernández, Guillermo, Chávez-Berrocal, María E., Girón, Jorge A., Orozco-Hoyuela, Gabriel, Manjarrez-Hernández, Angel
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2013
• Subjects: antibodies; Antigens; bacterial proteins; breast milk; cell membranes; cytoskeleton; Enteropathogenic Escherichia coli; Enteropathogenic Escherichia coli - immunology; EPEC; Escherichia coli Proteins - immunology; fermented milk; heat-shock protein 70; Hep G2 Cells; human cell lines; Human milk; Humans; immunoglobulin A; Immunoglobulin A, Secretory - immunology; intimin; Milk, Human - immunology; pathogens; Secretory IgA antibodies; type III secretion system; Virulence Factors - immunology; Western blotting; Human milk; Antigens; EPEC; Enteropathogenic Escherichia coli; Secretory IgA antibodies
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2013.09.001

Enteropathogenic Escherichia coli (EPEC) uses a type III secretion system (T3SS) to inject effectors into host cells and alter cellular physiology. The aim of the present study was to identify targets of human secretory immunoglobulin A (sIgA) antibodies from the proteins delivered by EPEC into HEp-2 cells after infection. Bacterial proteins delivered into EPEC-infected cells were obtained in sub-cellular fractions (cytoplasmic, membrane, and cytoskeleton) and probed with sIgA antibodies from human milk and analyzed by Western blotting. These sIgA antibodies reacted with Tir and EspB in the cytoplasmic and membrane fractions, and with intimin in the membrane fraction mainly. The sIgA also identified an EPEC surface-associated Heat-shock protein 70 (Hsp70) in HEp-2 cells infected with EPEC. Purified Hsp70 from EPEC was able to bind to HEp-2 cells, suggesting adhesive properties in this protein. EspC secreted to the medium reacted strongly with the sIgA antibodies. An EPEC 115 kDa protein, unrelated to the EspC protein, was detected in the cytoplasm of infected HEp-2 cells, suggesting that this is a new protein translocated by EPEC. The results suggest that there is a strong host antibody response to Tir and intimin, which are essential proteins for attaching and effacing (A/E) pathogen mediated disease. •EPEC antigens that interact with epithelial cells were identified with this model.•Human sIgA antibodies recognized EPEC proteins; intimin, tir, EspB, Hsp70 and EspC.•Hsp70 and an unknown EPEC 115-kDa protein may contributes to EPEC adherence.•Detection of a new protein (115-kDa) translocated by EPEC into cells.