Interactions ofHaemophilus parasuisand its LOS with porcine brain microvascular endothelial cells

Abstract

-Haemophilus parasuis is a swine pathogen that causes Glässer's disease, which is characterized by polyserositis and meningitis. The pathogenesis of the H. parasuis infection is poorly understood. To cause meningitis, H. parasuis has to cross the blood-brain barrier (BBB) to gain access to the central nervous system (CNS). We recently showed that H. parasuis adheres to and invades porcine brain microvascular endothelial cells (PBMEC). The aim of this study was to evaluate the role of H. parasuis lipooligosaccharide (LOS) in the adhesion to PBMEC and to determine if H. parasuis (and/or its LOS) is able to induce apoptosis and activation of PBMEC. Results showed that adhesion of H. parasuis to PBMEC was partially mediated by LOS. Moreover, H. parasuis induces caspase-3-mediated apoptosis of PBMEC in a time -and dosedependent manner, but its LOS did not seem to be involved in such a process. Furthermore, H. parasuis and, to a lesser extent, its LOS, was able to induce the release of IL-8 and IL-6 by PBMEC. Field strains of H. parasuis serotypes 4 and 5 induced similar levels of these inflammatory mediators. Our data suggest that H. parasuis uses cellular adhesion, induction of apoptosis and up-regulation of inflammatory mediators as mechanisms to invade the CNS via the BBB, and that LOS would play a certain but limited role in such pathological process. Haemophilus parasuis / LOS / endothelial cells / BBB / meningitis

Novel bla ROB-1 -Bearing Plasmid Conferring Resistance to β-Lactams in Haemophilus parasuis Isolates from Healthy Weaning Pigs

“…All strains tested triggered the secretion of the proinflammatory cytokine IL-8 by cultured epithelial cells to comparable levels, independently of the presence or absence of the lsgB and group 1 vtaA genes. Following this notion, H. parasuis field strains belonging to serotypes 4 and 5 have been shown to induce the release of IL-8 and IL-6 by porcine brain microvascular endothelial cells to a similar extent (60). A different finding was that H. parasuis has previously been shown to stimulate IL-8 and IL-6 release by newborn pig tracheal cells, and serotype 4 field isolates induced higher levels of these mediators than did serotype 5 isolates (44).…”

Haemophilus parasuis serovar 5 Nagasaki strain adheres and invades PK-15 cells

“…investigations on the specific interactions between this bacterium and host epithelial cells have been mainly focused on interactions with porcine brain microvascular endothelial cells (Vanier et al, 2006;Bouchet et al, 2008;Aragó n et al, 2010). To further understand the pathogenesis of Glä sser's disease, the aim of this study was to investigate the in vitro adherence and internalization abilities of epithelial PK-15 cell line by H. parasuis serovars 3 (nonvirulent) and 5 (highly virulent).…”

Haemophilus parasuis α-2,3-sialyltransferase-mediated lipooligosaccharide sialylation contributes to bacterial pathogenicity

“…Additionally, things will get worse in piglets co-infected with some other respiratory pathogens or immunosuppressive pathogens, for example, swine influenza virus could aggravate the lesions to the lung and thus facilitates microbial replication in the lung [28]. Despite of these external causes, H. parasuis also utilizes its internal factors for initial colonization, probably via adhesion to and invasion of host epithelial cells [29–31], disrupting mucosal immunity by degradation of IgA [32], resisting against phagocytosis by macrophage as well as bactericidal effect by the complement system [33–35]. Therefore, identification and characterization of the critical virulence factors that participating in these important phenotypes should provide better understanding of H. parasuis pathogenicity.…”

“…Both PK15 and PIEC cells were used to test the adhesion and invasion abilities of the wild-type, ΔlsgB mutant, and C- lsgB strains as previously described [29,31,54]. For the adhesion assay, bacteria were grown overnight in 5 mL TSB/V/S at 37°C with agitation.…”