Extracellular Paracoccidioides brasiliensis phospholipase B involvement in alveolar macrophage interaction

Abstract

BackgroundPhospholipase B (PLB) has been reported to be one of the virulence factors for human pathogenic fungi and has also been described as necessary for the early events in infection. Based on these data, we investigated the role of PLB in virulence and modulation of the alveolar pulmonary immune response during infection using an in-vitro model of host-pathogen interaction, i.e. Paracoccidioides brasiliensis yeast cells infecting alveolar macrophage (MH-S) cells.ResultsThe effect of PLB was analyzed using the specific inhibitor alexidine dihydrochloride (0.25 μM), and pulmonary surfactant (100 μg mL-1), during 6 hours of co-cultivation of P. brasiliensis and MH-S cells. Alexidine dihydrochloride inhibited PLB activity by 66% and significantly decreased the adhesion and internalization of yeast cells by MH-S cells. Genes involved in phagocytosis (trl2, cd14) and the inflammatory response (nfkb, tnf-α, il-1β) were down-regulated in the presence of this PLB inhibitor. In contrast, PLB activity and internalization of yeast cells significantly increased in the presence of pulmonary surfactant; under this condition, genes such as clec2 and the pro-inflammatory inhibitor (nkrf) were up-regulated. Also, the pulmonary surfactant did not alter cytokine production, while alexidine dihydrochloride decreased the levels of interleukin-10 (IL-10) and increased the levels of IL-12 and tumor necrosis factor-α (TNF-α). In addition, gene expression analysis of plb1, sod3 and icl1 suggests that P. brasiliensis gene re-programming is effective in facilitating adaptation to this inhospitable environment, which mimics the lung-environment interaction.ConclusionP. brasiliensis PLB activity is involved in the process of adhesion and internalization of yeast cells at the MH-S cell surface and may enhance virulence and subsequent down-regulation of macrophage activation.

Inhibitors of V-ATPase Proton Transport Reveal Uncoupling Functions of Tether Linking Cytosolic and Membrane Domains of V0 Subunit a (Vph1p)

“…Although V-ATPase inhibitors that have therapeutic applications have yet to be identified, the Prestwick Chemical Library is a useful resource for drug repurposing, as most of the compounds have known safety and toxicity profiles. In fact, cytotoxicity by alexidine dihydrochloride has been shown previously in Cryptococcus neoformans, C. albicans, and Paracoccidioides brasiliensis (55,56). Together, those studies and our current findings make alexidine dihydrochloride and thonzonium bromide attractive candidates to evaluate for repurposing as potential antifungal therapeutic drugs.…”

Alginate oligosaccharides modify hyphal infiltration ofCandida albicansin anin vitromodel of invasive human candidosis

“…The pathogenicity of SAPs, however, remains contentious (Correia et al 2010) with poor correlation found between individual SAP gene expression and epithelial damage (Naglik et al 2008). SAP expression is also dependent on environmental pH (Staib et al 2000), therefore, it is unsurprising that SAP production in C. albicans was not detected phenotypically in this study. The marked reductions in hyphal formation, which were induced by OligoG, were mirrored by alterations in the gene expression of PLB2, SAP4 and SAP6, evident by qPCR analysis.…”

“…) and local immune responses (Soares et al . ). While PL expression has, however, previously been shown not to correlate with RHE invasion in this model (Malic et al .…”

Phospholipid acylhydrolases trigger membrane degradation during fungal sporogenesis

“…Furthermore, the cryptococcal PLB is involved in cell wall stabilization (Siafakas et al, 2007). Like the related bacterial enzymes (Flieger et al, 2004;Pankhaniya et al, 2004), extracellular PLBs produced by pathogenic fungi are key players in adhesion to host cells (Ganendren et al, 2006;Soares et al, 2010), in cellular infection through membrane perturbation (Santangelo et al, 2004) and in the modulation of the lipid-mediated immune response (Noverr et al, 2003). Presumably, a PLB also contributes to symbiontic interactions such as nutrient exchange in mycorrhiza (Krause and Kothe, 2006).…”