Inflammation-inducing Factors of Mycoplasma pneumoniae
#MMPMID27065977
Shimizu T
Front Microbiol
2016[]; 7
(?): 414
PMID27065977
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Mycoplasma pneumoniae, which causes mycoplasmal pneumonia in human, mainly causes
pneumonia in children, although it occasionally causes disease in infants and
geriatrics. Some pathogenic factors produced by M. pneumoniae, such as hydrogen
peroxide and Community-Acquired Respiratory Distress Syndrome (CARDS) toxin have
been well studied. However, these factors alone cannot explain this predilection.
The low incidence rate of mycoplasmal pneumonia in infants and geriatrics implies
that the strong inflammatory responses induced by M. pneumoniae coordinate with
the pathogenic factors to induce pneumonia. However, M. pneumoniae lacks a cell
wall and does not possess an inflammation-inducing endotoxin, such as
lipopolysaccharide (LPS). In M. pneumoniae, lipoproteins were identified as an
inflammation-inducing factor. Lipoproteins induce inflammatory responses through
Toll-like receptors (TLR) 2. Because Mycoplasma species lack a cell wall and
lipoproteins anchored in the membrane are exposed, lipoproteins and TLR2 have
been thought to be important for the pathogenesis of M. pneumoniae. However,
recent reports suggest that M. pneumoniae also induces inflammatory responses
also in a TLR2-independent manner. TLR4 and autophagy are involved in this
TLR2-independent inflammation. In addition, the CARDS toxin or M. pneumoniae
cytadherence induces inflammatory responses through an intracellular receptor
protein complex called the inflammasome. In this review, the
inflammation-inducing factors of M. pneumoniae are summarized.
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