Invasion of human respiratory epithelial cells by Bordetella pertussis: Possible role for a filamentous hemagglutinin Arg-Gly-Asp sequence and α5β1 integrin

Abstract

Bordetella pertussis, the agent of whooping cough, is capable of invading human respiratory epithelial cells. In this study, we investigated the mechanisms by which B. pertussis invades the human lung epithelial cell line A549 and normal human bronchial epithelial (NHBE) cells. In vitro adhesion and invasion assays using both cell types with a virulent B. pertussis strain and its isogenic mutants revealed profound defects in a mutant deficient in filamentous hemagglutinin (FHA) expression. In addition, a mutant in which an FHA Arg-Gly-Asp (RGD) site had been changed to Arg-Ala-Asp had significantly diminished invasiveness, although its adhesiveness was comparable to that of the parental strain. Furthermore, a synthetic RGD-containing hexapeptide inhibited invasion of both cell types by the virulent strain. These results demonstrate that an RGD sequence of FHA is involved in B. pertussis invasion of epithelial cells in vitro. Monoclonal antibodies directed against human alpha5beta1 integrin, but not other integrins, blocked invasion, indicating that this integrin is involved in B. pertussis invasion. Taken together, these findings suggest that B. pertussis FHA may promote invasion of human respiratory epithelial cells through the interaction of its RGD sequence with host cell alpha5beta1 integrin.

Bordetellafilamentous hemagglutinin plays a critical role in immunomodulation, suggesting a mechanism for host specificity

“…A third possibility is that FHA Bp is inherently immunomodulatory (even in rodents), but this ability requires that the bacteria first be able to adhere specifically to host cells, i.e., that adherence and immunomodulation are mediated by separate domains within FHA and that each domain may display different abilities to distinguish receptors from different hosts. This hypothesis is supported by the fact that multiple binding domains within FHA Bp , with apparently different specificity, have been identified (20,29,30,(55)(56)(57).…”

ERK 1/2- and JNKs-dependent Synthesis of Interleukins 6 and 8 by Fibroblast-like Synoviocytes Stimulated with Protein I/II, a Modulin from Oral Streptococci, Requires Focal Adhesion Kinase

“…Transient transfection of FLSs was performed using the Nucleofector TM kit. 2 g of plasmidic DNA was added to 5 ϫ 10 5 FLSs suspended in 100 l of human dermal fibroblast Nucleofector™ solution. The program U-23 was selected for a high density of transfection according to the manufacturer's instructions.…”

“…Cell lysates were analyzed directly by blotting with specific anti-FAK (pY397) antibodies. Stimulation of FLSs with protein I/II for various times (1,5,15,30, and 60 min) resulted in an increased amount of phosphorylated FAK (Fig. 2), which was detectable within 5 min and remained elevated for at least 30 min.…”

“…For example, ␣ 5 ␤ 1 integrin is the known receptor of several bacterial PAMPs such as invasin of Yersinia pseudotuberculosis (2), fimbrillin A of Porphyromonas gingivalis (3), ipa proteins of Shigella spp. (4), filamentous hemagglutinin of Bordetella pertussis (5), and protein I/II of Streptococcus mutans (6). In addition, several other observations have demonstrated that integrin recognition of fibronectin promotes adhesion and internalization of bacteria expressing fibronectin-binding proteins, for example, protein M1 of Streptococcus pyogenes (7) or fibronectin-binding protein A of Staphylococcus aureus (8).…”

A family of variably expressed outer-membrane proteins (Vomp) mediates adhesion and autoaggregation in Bartonella quintana

“…18), which was confirmed for VompA, VompB, and VompC by N-terminal sequencing of the mature proteins. Interestingly, no Vomp has an Arg-Gly-Asp (RGD) motif that might mediate host-cell binding (19).…”