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. 2007 Dec 7;3(12):e187. doi: 10.1371/journal.ppat.0030187

Figure 6. A Schematic Model for the Modulation of sPLA2-IIA Expression in AMs by B. anthracis .

Figure 6

At the earlier stages of infection, PG constitutively present in B. anthracis cell walls induces sPLA2-IIA and IL-8 expression via an NF-κB–dependent process. After being taken up by AMs, B. anthracis spores undergo germination, which subsequently leads to bacilli formation and ET production. ET down-regulates sPLA2-IIA expression through sequential cAMP accumulation and PKA activation. The mechanisms by which PKA activation leads to down-regulation of sPLA2-IIA expression remains to be elucidated. As sPLA2-IIA is involved in pulmonary host defense against B. anthracis, its repression may lead to the proliferation of this bacterium in lung tissues. The black arrows represent the stimulatory pathway involving spores, and the red arrows correspond to the inhibitory pathway involving bacilli. ET appears to inhibit basal expression and induce sPLA2-IIA expression by various mechanisms (for more detail, see Discussion).

IκB, inhibitor of κ B.