Pertussis Toxin and Lipopolysaccharide Influence Phagocytosis ofBordetella pertussisby Human Monocytes

Abstract

The potential of human monocytes to mediate the clearance of Bordetella pertussis infection was examined. Bacteria expressing green fluorescent protein were incubated with adherent peripheral blood monocytes, and phagocytosis was quantified by using fluorescence microscopy. Monocytes internalized only a small percentage of the adherent bacteria. Surface-associated Bvg-regulated virulence factors, including adenylate cyclase toxin and filamentous hemagglutinin, did not affect attachment or phagocytosis. However, 1-h pretreatment with purified pertussis toxin inhibited the ability of monocytes to internalize wild-type bacteria. Mutations affecting the terminal trisaccharide of lipopolysaccharide resulted in reduced internalization without affecting adherence of bacteria to monocytes. Opsonization with human serum played only a modest role in promoting phagocytosis. The viability of internalized bacteria was determined by colony counts following treatment with polymyxin B and gentamicin. Less than 1% of internalized bacteria remained viable. These results suggest that pertussis toxin plays a role in the evasion of monocyte phagocytosis and that these cells represent a potential mediator of the clearance of B. pertussis infection.

Interactions of Pulmonary Collectins with Bordetella bronchiseptica and Bordetella pertussis Lipopolysaccharide Elucidate the Structural Basis of Their Antimicrobial Activities

“…7). As observed in previous studies with human peripheral blood monocytes (33), phagocytosis of unopsonized B. pertussis by rat alveolar macrophages was relatively inefficient, with less than one internalized bacterium per monocyte when experiments were conducted at an MOI of 5 (Fig. 7).…”

“…7). Phagocytosis of B. pertussis by monocytes (33) and macrophages (Fig. 3) appears to be inherently inefficient, and resistance to phagocytosis does not cor- It was previously reported that wild-type LPS of B. pertussis is resistant to binding, aggregation, opsonization, and permeabilization by SP-A (32).…”

Loss of microglial ramification in microglia‐astrocyte cocultures: Involvement of adenylate cyclase, calcium, phosphatase, and Gi‐protein systems

“…Pretreatment of human monocytes with purified pertussis toxin, an inhibitor of G-proteins, blocks the ability of monocytes to internalize wild-type bacteria (Schaeffer and Weiss, 2001). Similar inhibitory effect was also reported for okadaic acid (Stromhaug et al, 1997;Pahan et al, 1998), the inhibitor of serine/threonine protein phosphatases PP1 and PP2A.…”

Bordetella pertussis-Infected Human Monocyte-Derived Dendritic Cells Undergo Maturation and Induce Th1 Polarization and Interleukin-23 Expression

“…However, studies addressing the abilities of monocytes and neutrophils to phagocytose B. pertussis have suggested that evasion of phagocytes, rather than intracellular survival, allows bacterial cells to escape the effector cells of innate immunity (38,45).…”

“…iMDDC (10 6 /ml) were resuspended in complete medium without penicillin and streptomycin (referred to below as Bp medium) and then infected with B. pertussis cells at bacterium-to-cell ratios of 20:1 and 100:1. iMDDC and bacteria were centrifuged for 2 min at 640 ϫ g to facilitate contact (38) and then incubated for 2 h at 37°C under 5% CO 2 . Cells were then extensively washed and incubated for 3 h in Bp medium in the presence of polymyxin B (20 g/ml) to kill adherent extracellular bacteria.…”