Project description:The opportunistic fungal pathogen Candida albicans is a common cause of life-threatening nosocomial bloodstream infections. In the murine model of systemic candidiasis the kidney is the primary target organ while the fungal load declines over time in liver and spleen. To get a better understanding of the organ-specific differences in host-pathogen interaction during systemic murine candidiasis, we performed a time-course gene expression profiling to investigate the differential responses of murine kidney, liver and spleen and determined the fungal transcriptome in liver and kidney. We clearly demonstrate a delayed immune response on the transcriptional level in kidney accompanied by late induction of fungal stress response genes in this organ. In contrast, early upregulation of the proinflammatory response in the liver was associated with a fungal transcriptional profile resembling that of phagocytosed cells, suggesting that the resident phagocytic system contributes significantly to fungal control in the liver. Although no visible filamentation occurred in the liver, C. albicans hypha-associated genes were upregulated, indicating an uncoupling of gene expression and morphology during infection of this organ. In vitro the induction of hypha-associated gene expression in yeast cells led to altered interaction with macrophages, suggesting that the observed transcriptional changes affect host-pathogen interaction in vivo. Consistently, the combination of host and pathogen transcriptional data in an inference network model implied that C. albicans cell wall remodeling and metabolism were connected to the immune responses in kidney and liver. Furthermore, the network suggested links between fungal iron acquisition and amino acid metabolism in the kidney and host organ homeostasis. Thus, this work provides novel insights into the organ-specific host-pathogen interactions during systemic C. albicans infection.
Project description:The opportunistic fungal pathogen Candida albicans is a common cause of life-threatening nosocomial bloodstream infections. In the murine model of systemic candidiasis the kidney is the primary target organ while the fungal load declines over time in liver and spleen. To get a better understanding of the organ-specific differences in host-pathogen interaction during systemic murine candidiasis, we performed a time-course gene expression profiling to investigate the differential responses of murine kidney, liver and spleen and determined the fungal transcriptome in liver and kidney. We clearly demonstrate a delayed immune response on the transcriptional level in kidney accompanied by late induction of fungal stress response genes in this organ. In contrast, early upregulation of the proinflammatory response in the liver was associated with a fungal transcriptional profile resembling that of phagocytosed cells, suggesting that the resident phagocytic system contributes significantly to fungal control in the liver. Although no visible filamentation occurred in the liver, C. albicans hypha-associated genes were upregulated, indicating an uncoupling of gene expression and morphology during infection of this organ. In vitro the induction of hypha-associated gene expression in yeast cells led to altered interaction with macrophages, suggesting that the observed transcriptional changes affect host-pathogen interaction in vivo. Consistently, the combination of host and pathogen transcriptional data in an inference network model implied that C. albicans cell wall remodeling and metabolism were connected to the immune responses in kidney and liver. Furthermore, the network suggested links between fungal iron acquisition and amino acid metabolism in the kidney and host organ homeostasis. Thus, this work provides novel insights into the organ-specific host-pathogen interactions during systemic C. albicans infection.
Project description:The opportunistic fungal pathogen Candida albicans is a common cause of life-threatening nosocomial bloodstream infections. In the murine model of systemic candidiasis the kidney is the primary target organ while the fungal load declines over time in liver and spleen. To get a better understanding of the organ-specific differences in host-pathogen interaction during systemic murine candidiasis, we performed a time-course gene expression profiling to investigate the differential responses of murine kidney, liver and spleen and determined the fungal transcriptome in liver and kidney. We clearly demonstrate a delayed immune response on the transcriptional level in kidney accompanied by late induction of fungal stress response genes in this organ. In contrast, early upregulation of the proinflammatory response in the liver was associated with a fungal transcriptional profile resembling that of phagocytosed cells, suggesting that the resident phagocytic system contributes significantly to fungal control in the liver. Although no visible filamentation occurred in the liver, C. albicans hypha-associated genes were upregulated, indicating an uncoupling of gene expression and morphology during infection of this organ. In vitro the induction of hypha-associated gene expression in yeast cells led to altered interaction with macrophages, suggesting that the observed transcriptional changes affect host-pathogen interaction in vivo. Consistently, the combination of host and pathogen transcriptional data in an inference network model implied that C. albicans cell wall remodeling and metabolism were connected to the immune responses in kidney and liver. Furthermore, the network suggested links between fungal iron acquisition and amino acid metabolism in the kidney and host organ homeostasis. Thus, this work provides novel insights into the organ-specific host-pathogen interactions during systemic C. albicans infection.
Project description:The light-organ symbiosis between the squid Euprymna scolopes and the luminous bacterium Vibrio fischeri offers the opportunity to decipher the hour-by-hour events that occur during the natural colonization of an animal's epithelial surface by its microbial partners. To determine the genetic basis of these events, a glass-slide microarray was used to characterize the light-organ transcriptome of juvenile squid in response to the initiation of symbiosis. Patterns of gene expression were compared between animals not exposed to the symbiont, exposed to the wild-type symbiont, or exposed to a mutant symbiont defective in either of two key characters of this association: bacterial luminescence or autoinducer (AI) production. Hundreds of genes were differentially regulated as a result of symbiosis initiation, and a hierarchy existed in the magnitude of the host's response to three symbiont features: bacterial presence > luminescence > AI production. Putative host receptors for bacterial surface molecules known to induce squid development are up-regulated by symbiont light production, suggesting that bioluminescence plays a key role in preparing the host for bacteria-induced development. Further, because the transcriptional response of tissues exposed to AI in the natural context (i.e., with the symbionts) differed from that to AI alone, the presence of the bacteria potentiates the role of quorum signals in symbiosis. Comparison of these microarray data with those from other symbioses, such as germ-free/conventionalized mice and zebrafish, revealed a set of shared genes that may represent a core set of ancient host responses conserved throughout animal evolution.