ABSTRACT
Listeria monocytogenes is the etiological agent of meningitis that affects individuals at high risk such as pregnant women, neonates, the elderly and immunocompromised individuals. Infection by this intracellular pathogen can be lethal if not diagnosed and treated. Mouse neuroblastoma Neuro-2a cells, a neuron-like cell line, were infected with L. monocytogenes. In this study apoptotic changes of neuroblastoma Neuro-2a cells infected with strains of Listeria producing different listeriolysin O levels are investigated by cytotoxicity assay, cellular viability assay, DAPI staining, intranucleosomal DNA fragmentation test, and monoclonal antibodies against ss-DNA. Results show that after internalization, the bacteria induced morphological, functional and genetic changes in the cells characteristic of apoptosis, which was dose-and time-dependent on listeriolysin O. Neuroblastoma Neuro-2a cells represent an interesting model cell line to further the understanding of Listeria pathogenesis within the central nervous system.
Subject(s)
Apoptosis/physiology , Bacterial Toxins/metabolism , Heat-Shock Proteins/metabolism , Hemolysin Proteins/metabolism , Listeria monocytogenes/metabolism , Listeriosis/metabolism , Neuroblastoma/metabolism , Neurons/microbiology , Animals , Antibodies, Monoclonal , Cell Line, Tumor , DNA Fragmentation , DNA, Single-Stranded , Indoles , Mice , Neurons/metabolism , Staining and Labeling , Time FactorsABSTRACT
Mycoplasma pneumoniae has classically been considered an extracellular (or membrane-associated) organism. Nevertheless, the recently elucidated genomic structure of this pathogen strongly suggest that this organism may have been subjected to the process of reductive genetic evolution which is characteristic of intracellular bacteria. We studied the Mycoplasma pneumoniae RYC15989 strain, recovered from a pericardial biopsy sample from a patient with atypical pneumonia and acute pericarditis. The interaction of this strain with human hepatocytes Hep-G2 and mouse neuroblastoma N2-A cell lines was investigated. Confocal laser scanning microscopy and electronic microscopy evidence is presented of the intracellular location of fluorochrome-labelled Mycoplasma pneumoniae in cell lines infected with the organism in vitro. This finding provides preliminary evidence of cellular invasive capacity of Mycoplasma pneumoniae and casts some new light on the pathogenic potential of Mycoplasma pneumoniae in host infection.
