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Enhanced adhesion of Pasteurella multocida to cultured turkey peripheral blood monocytes
I M Pruimboom1, R B Rimler, M R Ackermann
1Avian and Swine Respiratory Diseases Research Unit, USDA Agricultural Research Service National Animal Disease Center, Ames, Iowa 50010, USA.
Abstract:
Capsular hyaluronic acid (HA) mediates adhesion of serogroup A strains of Pasteurella multocida to elicited turkey air sac macrophages (TASM). In contrast, freshly isolated turkey peripheral blood monocytes (TPBM) do not bind serogroup A strains. Following culture of TPBM for 6 days in chamber slides, adhesion of the bacteria to TPBM increased gradually. Incubation in chamber slides coated with entactin-collagen IV-laminin (ECL) attachment matrix or exposure to phorbol myristate acetate (PMA) further enhanced the adhesion of P. multocida to TPBM. Addition of HA, but not Arg-Gly-Asp peptide, to TPBM culture inhibited bacterial adherence similarly to the inhibition previously reported for TASM. Exposure of TPBM to monoclonal antibody directed against HA-binding cell surface proteoglycan (CD44) decreased binding of P. multocida. Collectively, these findings indicate that P. multocida adhesion to TPBM is mediated by capsular HA and can be increased by culture on ECL attachment matrix or PMA exposure. Additionally, the findings suggest that the capsular mucopolysaccharide of serogroup A strains of P. multocida recognizes an isoform of CD44 expressed on cultured TPBM.
Insights
Pasteurella multocida serogroup A uses hyaluronic acid (HA) to adhere to turkey immune cells. This adhesion is enhanced by cell culture and involves CD44, a cell surface proteoglycan.
Area of Science:
- Veterinary Microbiology
- Immunology
Background:
- Capsular hyaluronic acid (HA) is crucial for Pasteurella multocida serogroup A adhesion to turkey air sac macrophages (TASM).
- Freshly isolated turkey peripheral blood monocytes (TPBM) exhibit limited binding to these bacteria.
Purpose of the Study:
- To investigate the mechanisms of Pasteurella multocida serogroup A adhesion to turkey peripheral blood monocytes (TPBM).
- To determine the role of hyaluronic acid and CD44 in bacterial-monocyte interactions.
Main Methods:
- TPBM were cultured and their adhesion to P. multocida serogroup A was assessed.
- Adhesion was evaluated after incubation with entactin-collagen IV-laminin (ECL) matrix or phorbol myristate acetate (PMA).
- Inhibition studies used hyaluronic acid and anti-CD44 monoclonal antibody.
Main Results:
- Bacterial adhesion to cultured TPBM increased over time and was enhanced by ECL matrix or PMA.
- Hyaluronic acid addition inhibited bacterial adherence to TPBM.
- Monoclonal antibody against CD44 reduced P. multocida binding to TPBM.
Conclusions:
- Pasteurella multocida serogroup A adhesion to cultured TPBM is mediated by capsular HA.
- CD44 expressed on cultured TPBM is involved in the recognition of P. multocida HA.
- Culture conditions significantly influence bacterial adhesion to monocytes.