Project description:Virulence of Cryptococcus neoformans for mammals was proposed to emerge from evolutionary pressures on its natural environment by protozoan predators, which selected for strategies that allow survival within macrophages. In fact, Acanthamoeba castellanii ingests yeast cells, which then replicate intracellularly. In addition, most fungal factors needed to establish infection in the mammalian host are also important for survival within the amoeba. To better understand the origin of C. neoformans virulence, we compared the transcriptional profile of yeast cells internalized by amoebae and murine macrophages after 6 h of infection. Our results showed 656 and 293 genes whose expression changed at least two-fold in response to the intracellular environments of amoebae and macrophages, respectively. Among the genes common to both groups, we focused on the ORF CNAG_05662, which was potentially related to sugar transport. We constructed a mutant strain and evaluated its ability to grow on various carbon sources. The results showed that this gene, named PTP1 (Polyol Transporter Protein 1), is involved in the transport of 5- and 6-carbon polyols but its absence had no effect on virulence. Overall, our results are consistent with the hypothesis that mammalian virulence originated from fungal-protozoal interactions and provide a better understanding of how C. neoformans adapts to the mammalian host.
Project description:Virulence of Cryptococcus neoformans for mammals was proposed to emerge from evolutionary pressures on its natural environment by protozoan predators, which selected for strategies that allow survival within macrophages. In fact, Acanthamoeba castellanii ingests yeast cells, which then replicate intracellularly. In addition, most fungal factors needed to establish infection in the mammalian host are also important for survival within the amoeba. To better understand the origin of C. neoformans virulence, we compared the transcriptional profile of yeast cells internalized by amoebae and murine macrophages after 6 h of infection. Our results showed 656 and 293 genes whose expression changed at least two-fold in response to the intracellular environments of amoebae and macrophages, respectively. Among the genes common to both groups, we focused on the ORF CNAG_05662, which was potentially related to sugar transport. We constructed a mutant strain and evaluated its ability to grow on various carbon sources. The results showed that this gene, named PTP1 (Polyol Transporter Protein 1), is involved in the transport of 5- and 6-carbon polyols but its absence had no effect on virulence. Overall, our results are consistent with the hypothesis that mammalian virulence originated from fungal-protozoal interactions and provide a better understanding of how C. neoformans adapts to the mammalian host. Four conditions, pairwise-compared: cells in vegetative growth at 28C versus cells within amoebae at 28C; and cells in vegetative growth at 37C/5% CO2 versus cells within macrophages at 37C/5% CO2. Three biological replicates for each condition. One replicate per array.
Project description:Cryptococcus neoformans interactions with murine macrophages are critical for disease. In this project we analyzed fungal proteins which were co-purified with murine host proteins after interaction. H99 C. neoformans was opsonized with mAb 18B7 and addedd to murine macrophages. Then murine cells were lysed and cell extracts submitted to proteomics.
Project description:We measured protein translation (by ribosome profiling) and RNA levels (by polyA-enriched RNA-seq) in Cryptococcus neoformans strain H99 and Cryptococcus neoformans strain JEC21. This is the first transcriptome-wide map of translation in this species complex.
Project description:We examined four subsets of alveolar macrophages differentiated by CXCL2 expression and FLT3 fate mapping induced by Cryptococcus neoformans infection. These four subpopulations have distinct mRNA expression pattern indicating the heterogenity within alveolar macrophages.
Project description:We examined two subpopulations of alveolar macrophages differentiated by CXCL2 expression stimulated by Cryptococcus neoformans. The two subpopulations have distinct mRNA expression pattern indicating the heterogenity within alveolar macrophages.
Project description:Cryptococcal meningitis (CM) is a fatal compliation. Macrophages work as Trojan horses transferring Cryptococcus neoformans (C. neoformans) into the brain. Mechanisms for C. neoformans Trojan horses are largely elusive. In this study, we performed scRNA-Seq on immune cells infiltrated into the brain in a murine model of CM. Bioinformatics analysis reveals that phosphodiesterase 4B (PDE4B) ranks top in regulating macrophage Trojan horses. Melanin, a virulence factor for Cn, decreased PDE4B in macrophages. PDE4B inhibitor promoted the Cn Trojan horse across the blood-brain-barrier (BBB) in vitro and in vivo. As similar, PDE4B knockout increased fungi burden in the brain, which is, at least partially, rescued by macrophages depletion. In contrast, PDE4B activation diminished C. neoformans brain infection. Mechanistically, PDE4B inhibition increased CXCR4 and CCR7 on C. neoformans macrophage Trojan horses, a process regulated by the cAMP/PKA signaling pathway. Dexamethasone, commonly used to treat Pneumocystis infections in AIDS patients, significantly decreased PDE4B expression in macrophages. Overall, this study reveals that PDE4B plays a crucial role in C. neoformans macrophage Trojan horses and serves as a potential therapeutic target for CM.
Project description:Cryptococcus neoformans is a human fungal pathogen found ubiquitously within the environment and associated with infection of primarily immunocompromised individuals. Without the activation of an effective immune response, the pathogen can survive, proliferate, and disseminate throughout the host through the action of diverse virulence factors. These virulence factors include a polysaccharide capsule to protect the fungus from phagocytosis by macrophages, melanin production to neutralize reactive oxygen species, thermotolerance to survive at human physiological temperatures, and extracellular enzymes for host tissue degradation and invasion. We previously used mass spectrometry-based proteomics to explore the production of fungal virulence factors during infection using in vitro (macrophages) and in vivo (murine) models of disease. Based on our studies, we investigated the proteome response of C. neoformans upon disruption of CipC, a virulence-associated fungal protein.
Project description:We investigated the effects of the hypoxia-mimetic CoCl2 on the gene expression of pathogenic fungus Cryptococcus neoformans. Keywords: compound treatment design
Project description:Human infection with Cryptococcus neoformans (Cn), a prevalent fungal pathogen, occurs by inhalation and deposition in the lung alveoli of infectious particles. The subsequent host pathogen interaction is multifactorial and can result either in eradication, latency or extra-pulmonary dissemination. Successful control of Cn infection is dependent on host macrophages as shown by numerous studies. However in vitro macrophages display little ability to kill Cn. Recently, we reported that ingestion of Cn by macrophages induces early cell cycle progression that is subsequently followed by mitotic arrest, an event that almost certainly reflects damage to the host cell. The goal of the present work was to understand macrophage pathways affected by Cn toxicity. Infection of J774.16 macrophage-like cell line macrophages by Cn in vitro was associated with changes in gene pattern expression. Concomitantly we observed depolarization of macrophage mitochondria and alterations in protein translation rate. Our results indicate that Cn infection impairs multiple host cellular functions. Therefore we conclude Cn intracellular residence in macrophages undermines the health of these critical phagocytic cells interfering with their ability to clear the fungal pathogen.