Retnla down-regulation and IL-13-rich environment correlate with inflammation severity in experimental actinomycetoma by Nocardia brasiliensis

Nocardia brasiliensis (Nb) is a facultative intracellular pathogen that may cause actinomycetoma when immune response is unable to control the pathogenic invasion. We used comparative real-time PCR to evaluate the expression level of molecules indicative of either classical or alternative activation of macrophages, as well as of cytokines involved in macrophage polarization, during the experimental infection in BALB/c mice. We found induction or increased expression of the proinflammatory markers csf2/GM-CSF, interferon-gamma, and nos2/iNOS. The expression of Ym1 and IL-13, which are usually related with alternative activation of macrophage, was also increased. However, retnla/FIZZ1 expression decreased sharply during the infection. We concluded that Nb infection induces both a proinflammatory and anti-inflammatory environment, in which there is a strong inverse correlation between IL-13 and retnla expression.