Capsular Polysaccharide is a Main Component ofMycoplasma ovipneumoniaein the Pathogen-Induced Toll-Like Receptor-Mediated Inflammatory Responses in Sheep Airway Epithelial Cells

Abstract

Mycoplasma ovipneumoniae (M. ovipneumoniae) is characterized as an etiological agent of primary atypical pneumonia that specifically infects sheep and goat. In an attempt to better understand the pathogen-host interaction between the invading M. ovipneumoniae and airway epithelial cells, we investigated the host inflammatory responses against capsular polysaccharide (designated as CPS) of M. ovipneumoniae using sheep bronchial epithelial cells cultured in an air-liquid interface (ALI) model. Results showed that CPS derived from M. ovipneumoniae could activate toll-like receptor- (TLR-) mediated inflammatory responses, along with an elevated expression of nuclear factor kappa B (NF-κB), activator protein-1 (AP-1), and interferon regulatory factor 3 (IRF3) as well as various inflammatory-associated mediators, representatively including proinflammatory cytokines, such as IL1β, TNFα, and IL8, and anti-inflammatory cytokines such as IL10 and TGFβ of TLR signaling cascade. Mechanistically, the CPS-induced inflammation was TLR initiated and was mediated by activations of both MyD88-dependent and MyD88-independent signaling pathways. Of importance, a blockage of CPS with specific antibody led a significant reduction of M. ovipneumoniae-induced inflammatory responses in sheep bronchial epithelial cells. These results suggested that CPS is a key virulent component of M. ovipneumoniae, which may play a crucial role in the inflammatory response induced by M. ovipneumoniae infections.

Genome-Wide Analysis of Mycoplasma dispar Provides Insights into Putative Virulence Factors and Phylogenetic Relationships

“…The capsule is also an important virulence factor in Mycoplasma (Pilo et al 2007; Jiang et al 2017). ClpB is part of a stress-induced multi-chaperone system in bacteria and involved in the processing of protein aggregates and assisting in the refolding of denatured proteins.…”

“…CPS are important virulence factors for many Mycoplasma species, such as M. mycoides subsp. SC (Pilo et al 2007) and M. ovipneumoniae (Jiang et al 2017). For M. dispar , CPS is involved in suppressing of several alveolar macrophage functions and also considered a major virulence factor (Almeida et al 1992).…”

“…The virulence tests and statistical analysis method are indicated in File S1. Putative virulence genes were predicted by searching against the VFDB database (Chen et al 2012) and related studies (Chastanet et al 2004; Hames et al 2009; Song et al 2012; Groisman et al 2013; Bürki et al 2015; Gründel et al 2015; Zheng et al 2015; Jiang et al 2017).…”

Mycoplasma ovipneumoniae-derived lipid-associated membrane proteins induce cytokine secretion in mouse peritoneal macrophages through TLR2 signalling

“…However, when the stimulus was LAMPs, IL-1β was found to be markedly reduced. Zhongjia Jiang et al have reported that capsular polysaccharide (CP) is a primary component of M. ovi in the pathogen-induced Toll-like receptor-mediated inflammatory responses in sheep airway epithelial cells [29]. However, several other inflammasome sensors e.g.…”

In vivo role of capsular polysaccharide in Mycoplasma mycoides

“…Based on in vitro experiments, it has been suggested that the Mycoplasma gallisepticum capsule is involved in adhesion and virulence [2], the exopolysaccharides of Mycoplasma pulmonis protect against the complement system [3], CPS of Mycoplasma dispar down-regulates macrophage function [4], and purified CPS of Mycoplasma ovipneumoniae induces an inflammatory response through Toll-like receptor signaling in airway epithelial cells [5]. The exopolysaccharides of members of the “ Mycoplasma mycoides cluster” have been characterized [6] and free CPS of M. mycoides induces the production of interleukin 10 in bovine macrophages, which acts as an anti-inflammatory [7].…”