Pattern of cytokine gene expression in brains of mice protected by picolinic acid against lethal intracerebral infection with Candida albicans.

Recently, we demonstrated that intracerebral (i.c.) administration of picolinic acid (PLA) confers protection against a lethal local challenge with the opportunistic pathogen Candida albicans. By histopathological studies, we show here that mice receiving PLA treatment survive challenge and no evidence of fungal invasion is found within the brain compartment. In contrast, PLA-untreated mice succumb to infection within 7-10 days and show massive brain colonization with extensive granulomatous reaction. By PCR analysis, we show that, unlike naive brains, PLA-treated brains show transient activation of TNF alpha, IL-1 beta and IL-6 genes. C. albicans infection results in high levels of all cytokine transcripts, the phenomenon being long-lasting in PLA-untreated brains, while gradually declining in PLA-treated brains. The only exception is IL-1 beta, whose levels remain high at the latest time-points tested, also in PLA-treated brains. Finally, IL-1 alpha, constitutively detectable in naive brains, is slightly enhanced by C. albicans challenge, regardless of prior treatment. These findings, together with the knowledge that PLA is a potent co-stimulus for macrophages, suggest the involvement of cytokine circuits, likely of macrophage origin, in anti-Candida resistance established by PLA at the cerebral level.