The incidence of inflammatory bowel disease is increasing all over the world, especially in industrialized countries. The aim of the present work was to verify the anti‐inflammatory activity of metabolites. In particular, cell‐free supernatants of Lactobacillus acidophilus, Lactobacillus casei, Lactococcus lactis, Lactobacillus reuteri, and Saccharomyces boulardii have been investigated. Metabolites produced by these probiotics were able to downregulate the expression of PGE‐2 and IL‐8 in human colon epithelial HT‐29 cells. Moreover, probiotic supernatants can differently modulate IL‐1β, IL‐6, TNF‐α, and IL‐10 production by human macrophages, suggesting a peculiar anti‐inflammatory activity. Furthermore, supernatants showed a significant dose‐dependent radical scavenging activity. This study suggests one of the mechanisms by which probiotics exert their anti‐inflammatory activity affecting directly the intestinal epithelial cells and the underlying macrophages. This study provides a further evidence to support the possible use of probiotic metabolites in preventing and downregulating intestinal inflammation as adjuvant in anti‐inflammatory therapy.

In this study we tested the in vitro and in vivo anti- Cryptococcus neoformans activity of an antilaminarin (anti-β-glucan) monoclonal antibody (MAb 2G8) (immunoglobulin G2b) which was previously shown to inhibit the growth of β-glucan-exposing Candida albicans cells. Here we show that MAb 2G8 binds to the cell wall of C. neoformans and inhibits its growth to an extent comparable to that observed for C. albicans . Binding and growth inhibition were detected almost equally for encapsulated and acapsular C. neoformans strains. In addition, at subinhibitory concentrations, MAb 2G8 reduced the capsule thickness without affecting protease or phospholipase production. Acapsular fungal cells, but not encapsulated fungal cells, were opsonized by the antibody and more efficiently phagocytosed and killed by human monocytes and by murine peritoneal macrophages. A single administration of MAb 2G8 resulted in a reduction in the fungal burden in the brains and livers of mice systemically infected with a highly virulent, encapsulated C. neoformans strain. This protective effect was also detected in neutropenic mice. Overall, these findings demonstrate that cell wall β-glucan of encapsulated C. neoformans is accessible to antibodies which can exert remarkable anticryptococcal activities in vitro and in vivo.

Real-time monitoring of the spatial and temporal progression of infection/gene expression in animals will contribute greatly to our understanding of host-pathogen interactions while reducing the number of animals required to generate statistically significant data sets. Sensitive in vivo imaging technologies can detect low levels of light emitted from luciferase reporters in vivo, but the existing reporters are not optimal for fungal infections. Therefore, our aim was to develop a novel reporter system for imaging Candida albicans infections that overcomes the limitations of current luciferase reporters for this major fungal pathogen. This luciferase reporter was constructed by fusing a synthetic, codon-optimized version of the Gaussia princeps luciferase gene to C. albicans PGA59 , which encodes a glycosylphosphatidylinositol-linked cell wall protein. Luciferase expressed from this PGA59-gLUC fusion (referred to as gLUC59 ) was localized at the C. albicans cell surface, allowing the detection of luciferase in intact cells. The analysis of fusions to strong ( ACT1 and EFT3 ), oxidative stress-induced ( TRX1 , TRR1 , and IPF9996 ), and morphogenesis-dependent ( HWP1 ) promoters confirmed that gLUC59 is a convenient and sensitive reporter for studies of gene regulation in yeast or hyphal cells, as well as a flexible screening tool. Moreover, the ACT1 - gLUC59 fusion represented a powerful tool for the imaging of disease progression in superficial and subcutaneous C. albicans infections. gLUC59 and related cell surface-exposed luciferase reporters might find wide applications in molecular biology, cell biology, pathobiology, and high-throughput screens.

In a recent report, we demonstrated that distinct members of the secreted aspartic protease (Sap) family of Candida albicans are able to induce secretion of proinflammatory cytokines by human monocytes, independently of their proteolytic activity and specific pH optima. In particular, C. albicans Sap2 and Sap6 potently induced IL‐1β, TNF‐α, and IL‐6 production. Here, we demonstrate that Sap2 and Sap6 proteins trigger IL‐1β and IL‐18 production through inflammasome activation. This occurs via NLRP3 and caspase‐1 activation, which cleaves pro‐IL‐1β into secreted bioactive IL‐1β, a cytokine that was induced by Saps in monocytes, in monocyte‐derived macrophages and in dendritic cells. Downregulation of NLRP3 by RNA interference strongly reduced the secretion of bioactive IL‐1β. Inflammasome activation required Sap internalization via a clathrin‐dependent mechanism, intracellular induction of K⁺ efflux, and ROS production. Inflammasome activation of monocytes induced by Sap2 and Sap6 differed from that induced by LPS‐ATP in several aspects. Our data reveal novel immunoregulatory mechanisms of C. albicans and suggest that Saps contribute to the pathogenesis of candidiasis by fostering rather than evading host immunity.

Th17 cells play a major role in coordinating the host defence in oropharyngeal candidiasis. In this study we investigated the involvement of the Th17 response in an animal model of vulvovaginal candidiasis (VVC). To monitor the course of infection we exploited a new in vivo imaging technique. i) The progression of VVC leads to a strong influx of neutrophils in the vagina soon after the challenge which persisted despite the resolution of infection; ii) IL-17, produced by vaginal cells, particularly CD4 T cells, was detected in the vaginal wash during the infection, reaching a maximum 14 days after the challenge; iii) The amount and kinetics of IL-23 in vaginal fluids were comparable to those in vaginal cells; iv) The inhibition of Th17 differentiation led to significant inhibition of IL-17 production with consequent exacerbation of infection; v) An increased production of βdefensin 2 was manifested in cells of infected mice. This production was strongly reduced when Th17 differentiation was inhibited and was increased by rIL-17 treatment. These results imply that IL-17 and Th17, along with innate antimicrobial factors, have a role in the immune response to vaginal candidiasis.