The influence of curli, a MHC-I-binding bacterial surface structure, on macrophage-T cell interactions.
Escherichia coli express thin surface fimbriae called curli which bind soluble matrix proteins and major histocompatibility complex (MHC)-I molecules. The present study addressed the ability of purified curli or curliated E. coli to influence peptide presentation on MHC-I, T cell proliferation and bacterial uptake by macrophages. In vitro studies with curli-proficient E. coli YMel and the isogenic curli-deficient strain YMel-1, both expressing the model antigen Crl-OVA, showed that curli expression by E. coli does not appear to influence the efficiency by which the bacteria are processed by murine macrophages for OVA(257-264) presentation on K(b). Furthermore, curli expression by E. coli did not influence the binding of exogenously added OVA(257-264) peptide to K(b) on the surface of prefixed macrophages. In addition, neither curliated nor non-curliated heat-killed bacteria influenced proliferation of either murine or human T cells stimulated with anti-CD3. Finally, curliated E. coli adhered to and were internalized by macrophages from C57BL/6 and MHC-I-deficient TAP1(-/-) mice equally well. Together these studies show that curli expression by E. coli does not appear to influence phagocytic processing of bacteria expressing Crl-OVA for OVA(257-264)/K(b) presentation, the binding of exogenously added OVA(257-264) to K(b) or T cell proliferation. In addition, although curli expression by E. coli enhances bacterial interaction with macrophages, curli interaction with MHC-I does not significantly contribute to this adherence.
Johansson
C
C
Department of Cell and Molecular Biology, Section of Immunology, Lund University, Sweden.
Nilsson
T
T
Olsén
A
A
Wick
M J
MJ
D000818:Animals; D017951:Antigen Presentation; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000378:metabolism; D029968:Escherichia coli Proteins; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D010587:Phagocytosis; D013601:T-Lymphocytes / Q000276:immunology*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D015395:Histocompatibility Antigens Class I; C489688:csgA protein, E coli; C077481:Crl protein, Bacteria