Fibronectin Binding Protein and Host Cell Tyrosine Kinase Are Required for Internalization ofStaphylococcus aureusby Epithelial Cells

Abstract

Staphylococcus aureus expresses several surface proteins that promote adherence to host cell extracellular matrix proteins, including fibronectin (Fn). Since this organism has recently been shown to be internalized by nonprofessional phagocytes, a process that typically requires high-affinity binding to host cell receptors, we investigated the role of its Fn binding proteins (FnBPs) and other surface proteins in internalization by the bovine mammary gland epithelial cell line (MAC-T). Efficient internalization of S. aureus 8325-4 required expression of FnBPs; an isogenic mutant (DU5883), not expressing FnBPs, was reduced by more than 95% in its ability to invade MAC-T cells. Moreover, D3, a synthetic peptide derived from the ligand binding domain of FnBP, inhibited the internalization of the 8325-4 strain in a dose-dependent fashion and the efficiency of staphylococcal internalization was partially correlated with Fn binding ability. Interestingly, Fn also inhibited the internalization and adherence of S. aureus 8325-4 in a dose-dependent manner. In contrast to internalization, adherence of DU5883 to MAC-T was reduced by only approximately 40%, suggesting that surface binding proteins, other than FnBPs, can mediate bacterial adherence to cells. Adherence via these proteins, however, does not necessarily result in internalization of the staphylococci. An inhibitor of protein tyrosine kinase, genistein, reduced MAC-T internalization of S. aureus by 95%, indicating a requirement for a host signal transduction system in this process. Taken together, these results indicate that S. aureusinvades nonprofessional phagocytes by a mechanism requiring interaction between FnBP and the host cell, leading to signal transduction and subsequent rearrangement of the host cell cytoskeleton.

The molecular basis of fibronectin‐mediated bacterial adherence to host cells

“…In addition, the streptococcal FnBP SfbI/F1 has been shown to mediate invasion of HEp-2 (Molinari et al, 1997;Jadoun et al, 1998) and HeLa cells and human umbilical vein endothelial cells (HUVECs; Rohde et al, 2003). The role of the integrin a 5 b 1 in the FnBP-mediated invasion process has been demonstrated for S. aureus (Dziewanowska et al, 1999;Sinha et al, 1999) and S. pyogenes invasion of epithelial cells, and for S. aureus invasion of mouse fibroblasts (Fowler et al, 2000) and endothelial cells (Massey et al, 2001). The a v b 3 integrin has also been implicated in the uptake of S. pyogenes by a b1-null mutant mouse cell line .…”

Repeat regions R1 and R2 in the P97 paralogue Mhp271 of Mycoplasma hyopneumoniae bind heparin, fibronectin and porcine cilia

“…As infection evolves and M. hyopneumoniae elicits epithelial cell damage (DeBey and Ross, 1994), other ECM components become exposed that M. hyopneumoniae may bind leading to stronger and more complex interactions. Numerous bacterial Fn-binding proteins are also involved in host cell invasion (Dziewanowska et al, 1999;Sinha et al, 1999;Talay et al, 2000;Secott et al, 2004;Gillen et al, 2008). M. hyopneumoniae has been isolated from liver, spleen, kidneys and lymph nodes of pigs experimentally challenged and contact-exposed cohorts (Le Carrou et al, 2006;Marois et al, 2007) and from the pericardium fluid of commercially reared swine (Buttenschon et al, 1997).…”

Demonstration of intracellular Staphylococcus aureus in bovine mastitis alveolar cells and macrophages isolated from naturally infected cow milk

“…Macrophage Supernatant of macrophage by this bacterium. The demonstration of the invasion and survival of S. aureus inside a protective intracellular niche can explain the long term persistence of this disease a¡ecting lactating dairy cows and its key role played in the internalization [10]. Internalization and survival of S. aureus allows the understanding of why the immune system is ine¤cient and why the antibiotic treatment fails to eliminate this pathogen, so well adapted to its environment [8].…”