Assessment of Pasteurella multocida A Lipopolysaccharide, as an Adhesin in an In Vitro Model of Rabbit Respiratory Epithelium.

Carolina Gallego,Paula Esquinas,Stefany Romero,Pilar Patiño,Nhora Martínez,Carlos Iregui

doi:10.1155/2017/8967618

Abstract

The role of the P. multocida lipopolysaccharide (LPS) as a putative adhesin during the early stages of infection with this bacterium in the respiratory epithelium of rabbits was investigated. By light microscopy and double enzyme labeling of nasal septa tissues, the amount of bacteria attached to the respiratory epithelium and the amount of LPS present in goblet cells at different experimental times were estimated. Transmission electron microscopy (TEM) and LPS labeling with colloidal gold particles were also used to determine the exact location of LPS in the cells. Septa that were challenged with LPS of P. multocida and 30 minutes later with P. multocida showed more adherent bacteria and more severe lesions than the other treatments. Free LPS was observed in the lumen of the nasal septum, forming bilamellar structures and adhering to the cilia, microvilli, cytoplasmic membrane, and cytoplasm of epithelial ciliated and goblet cells. The above findings suggest that P. multocida LPS plays an important role in the process of bacterial adhesion and that it has the ability of being internalized into host cells.

Highlights

Pasteurella multocida is considered the most important causal agent of respiratory diseases in rabbits and in other species; this group of microorganisms is responsible for the largest economic losses in production farm animals [1]
The LPS of Gram-negative bacteria is considered one of the main virulence factors of these pathogens, causing severe systemic damage in the interaction with their hosts [39,40,41]; a similar role has been recognized for the LPS of P. multocida [39,40,41,42]
Much less effort has been dedicated to investigating the role of LPS in its respective bacteria during the first phases of an infection and attachment to the mucosal surfaces of the corresponding hosts [45]

Summary

Introduction

Pasteurella multocida is considered the most important causal agent of respiratory diseases in rabbits and in other species; this group of microorganisms is responsible for the largest economic losses in production farm animals [1]. Adhesion is considered the first essential step that a pathogen must overcome to cause disease [6,7,8,9] Such interactions occur between molecules located on the surface of host epithelial cells as well as molecules on the bacteria. Lipopolysaccharide (LPS) is the most abundant superficial constituent of Gram-negative bacteria. This glycolipid molecule is fundamental for the survival of these microorganisms and is responsible for causing severe systemic effects in the hosts, such as endotoxemia; LPS is considered an important virulence factor of these pathogens [10,11,12,13]. Studies on the involvement of LPS during the first steps of infection, namely, during adhesion and colonization of the surface epithelia before the bacteria causes systemic

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Results

Conclusion