Characterization of outer membrane vesicles from a neonatal meningitic strain of Cronobacter sakazakii

Abstract

Cronobacter sakazakii is associated with severe and often fatal cases of infant meningitis and necrotizing enterocolitis. The form of meningitis differs from that due to Neisseria meningitidis and Streptococcus spp., in that it is highly invasive and destructive towards human brain cells. However, there is relatively little understanding of the cytopathogenic interaction of C. sakazakii with host cells which results in stimulation of an inflammatory immune response. The production of Cronobacter outer membrane vesicles (OMV) and their potential pathogenic functions have not yet been elucidated. This study is the first to show that C. sakazakii produce OMV, which may play a role in the activation of cytopathogenic and host cell responses on human intestinal epithelial cells. Cronobacter sakazakii strain 767 was used which had been isolated from a fatal outbreak of neonatal meningitis and necrotizing enterocolitis. Cronobacter sakazakii OMV were internalized by Caco-2 cells, increased cell proliferation and stimulated the host's innate proinflammatory response without inducing overt toxicity. A total of 18 OMV-associated proteins were identified by mass spectrometry and their potential pathogenicity roles were evaluated. Collectively, these data indicate that C. sakazakii OMV could play a role in pathogenesis by delivering bacterial toxins into host epithelial cells, driving proliferative and proinflammatory responses.

Otopathogenic Pseudomonas aeruginosa Enters and Survives Inside Macrophages

“…Bacterial OMPs play a crucial role in interaction of pathogens with host cells (Toma et al, 2014; Alzahrani et al, 2015; Bulir et al, 2015). OprF is the major OMP/porin of P. aeruginosa that has been demonstrated to facilitate biofilm formation under anaerobic conditions and adhesion to host cells (Azghani et al, 2002; Yoon et al, 2002).…”

Comparative Analysis of Membrane Vesicles from Three Piscirickettsia salmonis Isolates Reveals Differences in Vesicle Characteristics

“…We cannot, however, fully exclude the presence of cytoplasmic contaminants in the samples, which could contribute to a higher number of proteins been identified as cytoplasmic. The presence of several cytoplasmic proteins have, nonetheless, been identified in proteomic studies of several bacterial derived MVs [ 5 , 9 , 76 – 77 ], and it has been suggested that some of these proteins could be sorted into the vesicles during the MV formation [ 2 , 78 – 79 ]. This may implicate that the MV production is specific and not a random event, allowing for selective incorporation of proteins into the vesicles.…”

“…Together they represent several aspects of the bacteria, but in a non-replicative form. MVs have also been reported to contain several important immunogenic factors, such as toxins [ 8 ], chaperons [ 9 ], and active enzymes [ 5 ]. The mechanisms of the MV formation and their biological role have yet to be clearly defined.…”

Bacterial membrane vesicles: Biogenesis, immune regulation and pathogenesis

“…Interactions between OMVs and epithelial cells can modulate cellular mechanisms that control proliferation (Li et al, ), apoptosis (Kunsmann et al, ; Mondal et al, ), and ultimately immune responses. Cronobacter sakazakii , a causative agent of infant meningitis and enterocolitis, produces OMVs that are internalized by intestinal epithelial cells inducing cell proliferation, IL‐8 secretion and facilitating bacterial persistence (Alzahrani, Winter, Boocock, De Girolamo, & Forsythe, ).…”