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Ascending infections of equine uterus frequently result in placentitis and abortions; most of these infections are bacterial and are less commonly due to fungi. This report describes an abortion case in an Arab mare due to Candida guilliermondii that was diagnosed via cytological, histological, cultural and biomolecular assays. The histological lesions found were severe necrotizing placentitis associated with fetal pneumonia. To our knowledge this is the first case of C. guilliermondii abortion reported in equine species.

The C-type lectin receptor Dectin-1 plays a pivotal role in antifungal immunity. In this study, the recently characterized human DECTIN1 Y238X early stop codon polymorphism leading to diminished Dectin-1 receptor activity was studied in relation to invasive aspergillosis susceptibility and severity in patients receiving hematopoietic stem cell transplantation. We found that the presence of the DECTIN1 Y238X polymorphism in either donors or recipients of hematopoietic stem cell transplantation increased susceptibility to aspergillosis, with the risk being highest when the polymorphism was present simultaneously in both donors and recipients (adjusted hazard ratio = 3.9; P = .005). Functionally, the Y238X polymorphism impaired the production of interferon-γ and interleukin-10 (IL-10), in addition to IL-1β, IL-6, and IL-17A, by human peripheral mononuclear cells and Dectin-1 on human epithelial cells contributed to fungal recognition. Mechanistically, studies on preclinical models of infection in intact or bone marrow-transplanted Dectin-1 knockout mice revealed that protection from infection requires a distinct, yet complementary, role of both donor and recipient Dectin-1. This study discloses Dectin-1 deficiency as a novel susceptibility factor for aspergillosis in high-risk patients and identifies a previously unsuspected role for Dectin-1 in antifungal immunity that is the ability to control both resistance and tolerance to the fungus contingent on hematopoietic/nonhematopoietic compartmentalization.

Fungi are a major threat in immunocompromised patients. Despite presenting similar degrees of immunosuppression, not all individuals at-risk ultimately develop fungal diseases. The traditional view of immune suppression as a key risk factor for susceptibility to fungal infections needs to be accommodated within new conceptual advances on host immunity and its relationship to fungal disease. The critical role of the immune system emphasizes the contribution of host genetic polymorphisms to fungal disease susceptibility. This review highlights the present knowledge on innate immunity genetics that associates with susceptibility to fungal diseases., (Copyright 2009 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Reactivation of latent human cytomegalovirus (HCMV) following allogeneic transplantation is a major cause of morbidity and mortality and predisposes to severe complications, including superinfection by Aspergillus species (spp). Antimicrobial polypeptides, including defensins and mannan-binding lectin, are known to block viral fusion by cross-linking sugars on cell surface. Pentraxin 3 (PTX3), a member of the long pentraxin family, successfully restored antifungal immunity in experimental hematopoietic transplantation. We assessed here whether PTX3 binds HCMV and murine virus (MCMV) and the impact on viral infectivity and superinfection in vivo. We found that PTX3 bound both viruses, reduced viral entry and infectivity in vitro, and protected from MCMV primary infection and reactivation as well as Aspergillus superinfection. This occurred through the activation of interferon (IFN) regulatory factor 3 (IRF3) in dendritic cells via the TLR9/MyD88-independent viral recognition sensing and the promotion of the interleukin-12 (IL-12)/IFN-gamma-dependent effector pathway.

Dendritic cells (DCs) show a remarkable functional plasticity in the recognition of Aspergillus fumigatus and orchestrate the antifungal immune resistance in the lungs. Here, we show that thymosin alpha 1, a naturally occurring thymic peptide, induces functional maturation and interleukin-12 production by fungus-pulsed DCs through the p38 mitogen-activated protein kinase/nuclear factor (NF)-kappaB-dependent pathway. This occurs by signaling through the myeloid differentiation factor 88-dependent pathway, involving distinct Toll-like receptors. In vivo, the synthetic peptide activates T-helper (Th) cell 1-dependent antifungal immunity, accelerates myeloid cell recovery, and protects highly susceptible mice that received hematopoietic transplants from aspergillosis. By revealing the unexpected activity of an old molecule, our finding provides the rationale for its therapeutic utility and qualify the synthetic peptide as a candidate adjuvant promoting the coordinated activation of the innate and adaptive Th immunity to the fungus.

Dendritic cells (DCs) have a remarkable functional plasticity in response to conidia and hyphae of the fungus Aspergillus fumigatus. In the present study we sought to assess the capacity of DCs activated by live fungi or fungal RNA to generate antifungal immunity in vivo. We found that both human and murine DCs pulsed with live fungi or transfected with fungal RNA underwent functional maturation, as revealed by the up-regulated expression of histocompatibility class II antigen and costimulatory molecules and the production of interleukin 12 (IL-12) in response to conidia or conidial RNA and of IL-4/IL-10 in response to hyphae or hyphal RNA. DCs pulsed with conidia or transfected with conidial RNA activated antigen-specific, interferon gamma (IFN-gamma)-producing T lymphocytes in vitro and in vivo on adoptive transfer in mice otherwise susceptible to aspergillosis. TH1-dependent antifungal resistance could also be induced in mice receiving allogeneic bone marrow transplants and was associated with an accelerated recovery of myeloid and lymphoid cells. Because the efficacy of the infusion of DCs was superior to that obtained on the adoptive transfer of Aspergillus-specific T cells, these results indicate the vaccinating potential of DCs pulsed with Aspergillus conidia or conidial RNA in hematopoietic transplantation.

Tetanus neurotoxin (TT), a product of microbial origin, acts as a zinc endopeptidase on vesicle-associated membrane proteins (VAMP). We have demonstrated that TT displays inhibitory effects on secretory and accessory functions in the murine macrophage (Mphi) cell line GG2EE. Nitric oxide (NO) secretion was decreased when interferon (IFN)-gamma-pretreated GG2EE Mphis were coincubated with a fungal costimulus (SMP200) and TT. When heat-inactivated TT was used this effect was not evident. The TT-mediated phenomenon was dose-dependent and specific since, under the same experimental conditions, it did not affect interleukin-6 or tumor necrosis factor-alpha secretion. Furthermore, IFN-gamma-induced major histocompatibility complex class II molecule expression and GG2EE accessory function, assessed by SMP200-stimulated lymphoproliferation, were also inhibited by TT. Such inhibition was incomplete, in line with our previous results showing that TT partially cleaves VAMP proteins in murine Mφ., (Copyright 1999 Academic Press.)

The light chain of tetanus neurotoxin (TeTx) is a zinc endopeptidase specific for VAMP/synaptobrevin (VAMP), a 120-amino-acid integral protein previously described in the small synaptic vesicles of neuronal cells. TeTx has been shown to be active also on nonneuronal cells. By SDS-PAGE and quantitative immunoblotting on proteins derived from murine macrophages (Mphi) exposed to TeTx, we have shown that: (1) VAMP-related proteins are also present in Mphi and (2) such proteins are sensitive to TeTx proteolytic cleavage. The demonstration that TeTx acts on VAMP-related proteins also in Mphi offers a new and useful tool for molecular studies on Mphi exocytosis.

Using an in vitro experimental model, we have recently demonstrated that Candida albicans in its hyphal form (H-Candida), similarly to lipopolysaccharide (LPS), enhances tumor necrosis factor (TNF) secretory response in the cloned macrophage (M phi) population ANA-1. Here we show that H-Candida and LPS each differ in their requirements for intact protein kinase functions, susceptibility to 0.4-microns micropore-size membranes, and sensitivity to polymyxin B. These results, together with the synergistic effect occurring between H-Candida and LPS in inducing TNF response, indicate the existence of different receptor(s) and/or signal-transduction pathway(s) through which the two stimuli act.

In the present study, we have examined the ability of phagocytes from different anatomical districts to discriminate between the two morphogenetic forms of Candida albicans. We have demonstrated that resident peritoneal macrophages (RP-M phi) and thioglycollate-elicited peritoneal macrophages (TP-M phi) were able to distinguish between the hyphal (H-Candida) and the yeast (Y-Candida) form of the fungus, since TNF production was observed only upon exposure of RP-M phi and TP-M phi to H-Candida. In contrast, splenic macrophages (S-M phi), bone marrow-derived macrophages (BM-M phi) and polymorphonuclear neutrophils (PMN) did not discriminate between the two forms because S-M phi and PMN produced TNF regardless of the morphogenetic status of the fungus, while BM-M phi did not. Under the same experimental conditions, we failed to observe IL-1 production from any of the phagocytic cell populations examined, with the exception of PMN. This implies that the interaction between phagocytes and C. albicans triggers differential secretory responses depending upon the morphogenetic status of the fungus and the anatomical localization of the immune cells.

We have demonstrated that Candida albicans in its hyphal form (H-Candida) acts as a stimulating agent in the cloned macrophage population ANA-1. Both tumor necrosis factor (TNF) mRNA levels and secreted biological activity augment in ANA-1 macrophages exposed to H-Candida. Such effects are observed at an effector-to-target cell ratio of 1:1 and occur after 1 and 3 hr of coincubation, respectively. The phenomenon is independent of the metabolic status of the fungus, since viable as well as heat-killed H-Candida are comparable in inducing TNF mRNA levels. The extent and kinetics of H-Candida-mediated effects are similar to those observed following exposure of ANA-1 macrophages to lipopolysaccharide (LPS). This implies that C. albicans in its hyphal form is a potent macrophage modulator; whether it acts through the same mechanism(s) as LPS remains to be elucidated.

An indirect immunofluorescence microassay, which permits automated reading, has been employed for simple, rapid and objective detection of surface and intracellular antigens. Initially, the cells, spun in microplates, are fixed with glutaraldehyde (0.25% v/v in PBS). Following fixation, the cells can be stored at 4 degrees C for up to 2 weeks before being used in the immunofluorescence microassay. The fixed cells are then stained according to standard procedures using appropriate first and fluorescein-conjugated second antibodies. An automated and quantitative evaluation of the fluorescence intensity of the cell samples was achieved using the Titertek Fluoroskan II automatic reader. This microassay was shown to be suitable for the detection of the surface MAC1 antigen and intracellular v-myc protein in the GG2EE macrophage cell line.