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Eosinophils and IL-4 Support Nematode Growth Coincident with an Innate Response to Tissue Injury.

Huang L, Beiting DP, Gebreselassie NG, Gagliardo LF, Ruyechan MC, Lee NA, Lee JJ, Appleton JA - PLoS Pathog. (2015)

Bottom Line: The eosinophil-mediated effect operates in the absence of adaptive immunity.Redistribution of glucose transporter 4 (GLUT4) and phosphorylation of Akt were observed in nurse cells, consistent with enhancement of glucose uptake and glycogen storage by larvae that is known to occur.Our findings document a novel interaction between parasite and host in which worms have evolved a strategy to co-opt an innate host cell response in a way that facilitates their growth.

View Article: PubMed Central - PubMed

Affiliation: Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
It has become increasingly clear that the functions of eosinophils extend beyond host defense and allergy to metabolism and tissue regeneration. These influences have strong potential to be relevant in worm infections in which eosinophils are prominent and parasites rely on the host for nutrients to support growth or reproduction. The aim of this study was to investigate the mechanism underlying the observation that eosinophils promote growth of Trichinella spiralis larvae in skeletal muscle. Our results indicate that IL-4 and eosinophils are necessary for normal larval growth and that eosinophils from IL-4 competent mice are sufficient to support growth. The eosinophil-mediated effect operates in the absence of adaptive immunity. Following invasion by newborn larvae, host gene expression in skeletal muscle was compatible with a regenerative response and a shift in the source of energy in infected tissue. The presence of eosinophils suppressed local inflammation while also influencing nutrient homeostasis in muscle. Redistribution of glucose transporter 4 (GLUT4) and phosphorylation of Akt were observed in nurse cells, consistent with enhancement of glucose uptake and glycogen storage by larvae that is known to occur. The data are consistent with a mechanism in which eosinophils promote larval growth by an IL-4 dependent mechanism that limits local interferon-driven responses that otherwise alter nutrient metabolism in infected muscle. Our findings document a novel interaction between parasite and host in which worms have evolved a strategy to co-opt an innate host cell response in a way that facilitates their growth.

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Transcriptional reprogramming of skeletal muscle during T. spiralis infection in Rag1-/- mice.Microarray-based gene expression profiling of diaphragms of uninfected and infected Rag1-/- mice on 0, 2 and 7 post IV infection. (A) Hierarchical clustering and heatmap representation of 1529 genes differentially regulated during a time course of T. spirals muscle infection (2-fold, FDR ≤ 0.05). Four clusters of coordinately regulated genes are indicated. Color pattern represents row Z-score. (B) Bubble chart showing results of Gene Ontology (GO) enrichment analysis. Bubble size indicates number of genes associated with each term. Bubble color indicates whether genes associated with each term were upregulated (red) or downregulated (green), while color intensity indicates fold enrichment. (C) GSEA enrichment plot for four selected pathways with normalized enrichment scores (NES) and false discover rates (FDR). Collagen formation, TCA cycle/electron trans. and glycolysis: 7dpi vs naïve. Interferon signaling: 2dpi vs naïve. (D) Six selected genes from each GSEA signature panel (C). Maximum mean fold change (FC) between naïve and infected Rag1-/- mice is shown.
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ppat.1005347.g005: Transcriptional reprogramming of skeletal muscle during T. spiralis infection in Rag1-/- mice.Microarray-based gene expression profiling of diaphragms of uninfected and infected Rag1-/- mice on 0, 2 and 7 post IV infection. (A) Hierarchical clustering and heatmap representation of 1529 genes differentially regulated during a time course of T. spirals muscle infection (2-fold, FDR ≤ 0.05). Four clusters of coordinately regulated genes are indicated. Color pattern represents row Z-score. (B) Bubble chart showing results of Gene Ontology (GO) enrichment analysis. Bubble size indicates number of genes associated with each term. Bubble color indicates whether genes associated with each term were upregulated (red) or downregulated (green), while color intensity indicates fold enrichment. (C) GSEA enrichment plot for four selected pathways with normalized enrichment scores (NES) and false discover rates (FDR). Collagen formation, TCA cycle/electron trans. and glycolysis: 7dpi vs naïve. Interferon signaling: 2dpi vs naïve. (D) Six selected genes from each GSEA signature panel (C). Maximum mean fold change (FC) between naïve and infected Rag1-/- mice is shown.

Mentions: To further investigate the mechanism of eosinophil-mediated larval growth in skeletal muscle, we performed whole genome transcriptional profiling to identify genes altered early in the course of muscle infection, coincident with the interval during which eosinophils are required. In order to limit the numbers of infiltrating cells in muscle tissue, experiments were performed with Rag1-/- mice. Muscle infection in Rag1-/- mice resulted in differential expression of 1529 genes (S1 Table). Hierarchical clustering revealed at least four distinct clusters of co-regulated genes (Fig 5A). Genes in cluster 1 are repressed early during infection, with the greatest effect evident on 7 days post infection (dpi). Gene Ontology enrichment analysis revealed that this cluster included genes involved in muscle organ development and acetyl-CoA metabolism (Fig 5B). Cluster 2 is an early response profile that incorporates genes whose expression peaks at 2dpi. This gene set was highly enriched for genes in the defense response (Fig 5B). In contrast, cluster 3 includes genes that are strongly induced at 7dpi and largely involved in cellular remodeling and wound healing (Fig 5B). Finally, genes in cluster 4 are induced at 2dpi and further increased at 7dpi. This cluster included genes involved in antigen presentation and immune activation (Fig 5B). To identify pathways enriched in infected muscle, relative to uninfected muscle, gene set enrichment analysis (GSEA) was performed on 2 and 7 dpi samples. At 2dpi, there was marked induction of genes involved in interferon signaling (Fig 5C), including the STAT1 target genes Igtp, Irgm2, Cxcl9 and Cxcl10, as well as master regulators of the interferon response, Irf1 and Stat1 (Fig 5D). GSEA at 7dpi identified signatures primarily associated with collagen formation and muscle repair (Fig 5C). This included tenascin C (Tnc), a tissue remodeling factor; lysyl oxidase (Lox), a secreted enzyme that initiates crosslinking of collagen and elastin; and a series of collagen genes (Col12a1, Col5a1, Col4a1 and Col1a1) (Fig 5D). These finding were consistent with substantial muscle cell hypertrophy and initiation of nurse cell transformation and formation of the collagen capsule at this time. Notably, many genes of glycolysis were significantly induced at 7dpi, including several key regulatory enzymes such as Pfkp, Pygb, Pfkl and Hk3 (Fig 5D). A large set of genes was also markedly reduced in expression by 7dpi and included signatures related to the TCA cycle (e.g. Idh2, Dlat and Mdh1) and striated muscle cell development (e.g. Myh4, Synm and Myot) (Fig 5C and 5D). Collectively, these changes in gene expression programs following infection by NBL describe a robust early induction of STAT1-dependent genes and subsequent loss of myofibers, a strong regenerative response, and a shift in the sources of energy in infected muscle.


Eosinophils and IL-4 Support Nematode Growth Coincident with an Innate Response to Tissue Injury.

Huang L, Beiting DP, Gebreselassie NG, Gagliardo LF, Ruyechan MC, Lee NA, Lee JJ, Appleton JA - PLoS Pathog. (2015)

Transcriptional reprogramming of skeletal muscle during T. spiralis infection in Rag1-/- mice.Microarray-based gene expression profiling of diaphragms of uninfected and infected Rag1-/- mice on 0, 2 and 7 post IV infection. (A) Hierarchical clustering and heatmap representation of 1529 genes differentially regulated during a time course of T. spirals muscle infection (2-fold, FDR ≤ 0.05). Four clusters of coordinately regulated genes are indicated. Color pattern represents row Z-score. (B) Bubble chart showing results of Gene Ontology (GO) enrichment analysis. Bubble size indicates number of genes associated with each term. Bubble color indicates whether genes associated with each term were upregulated (red) or downregulated (green), while color intensity indicates fold enrichment. (C) GSEA enrichment plot for four selected pathways with normalized enrichment scores (NES) and false discover rates (FDR). Collagen formation, TCA cycle/electron trans. and glycolysis: 7dpi vs naïve. Interferon signaling: 2dpi vs naïve. (D) Six selected genes from each GSEA signature panel (C). Maximum mean fold change (FC) between naïve and infected Rag1-/- mice is shown.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4697774&req=5

ppat.1005347.g005: Transcriptional reprogramming of skeletal muscle during T. spiralis infection in Rag1-/- mice.Microarray-based gene expression profiling of diaphragms of uninfected and infected Rag1-/- mice on 0, 2 and 7 post IV infection. (A) Hierarchical clustering and heatmap representation of 1529 genes differentially regulated during a time course of T. spirals muscle infection (2-fold, FDR ≤ 0.05). Four clusters of coordinately regulated genes are indicated. Color pattern represents row Z-score. (B) Bubble chart showing results of Gene Ontology (GO) enrichment analysis. Bubble size indicates number of genes associated with each term. Bubble color indicates whether genes associated with each term were upregulated (red) or downregulated (green), while color intensity indicates fold enrichment. (C) GSEA enrichment plot for four selected pathways with normalized enrichment scores (NES) and false discover rates (FDR). Collagen formation, TCA cycle/electron trans. and glycolysis: 7dpi vs naïve. Interferon signaling: 2dpi vs naïve. (D) Six selected genes from each GSEA signature panel (C). Maximum mean fold change (FC) between naïve and infected Rag1-/- mice is shown.
Mentions: To further investigate the mechanism of eosinophil-mediated larval growth in skeletal muscle, we performed whole genome transcriptional profiling to identify genes altered early in the course of muscle infection, coincident with the interval during which eosinophils are required. In order to limit the numbers of infiltrating cells in muscle tissue, experiments were performed with Rag1-/- mice. Muscle infection in Rag1-/- mice resulted in differential expression of 1529 genes (S1 Table). Hierarchical clustering revealed at least four distinct clusters of co-regulated genes (Fig 5A). Genes in cluster 1 are repressed early during infection, with the greatest effect evident on 7 days post infection (dpi). Gene Ontology enrichment analysis revealed that this cluster included genes involved in muscle organ development and acetyl-CoA metabolism (Fig 5B). Cluster 2 is an early response profile that incorporates genes whose expression peaks at 2dpi. This gene set was highly enriched for genes in the defense response (Fig 5B). In contrast, cluster 3 includes genes that are strongly induced at 7dpi and largely involved in cellular remodeling and wound healing (Fig 5B). Finally, genes in cluster 4 are induced at 2dpi and further increased at 7dpi. This cluster included genes involved in antigen presentation and immune activation (Fig 5B). To identify pathways enriched in infected muscle, relative to uninfected muscle, gene set enrichment analysis (GSEA) was performed on 2 and 7 dpi samples. At 2dpi, there was marked induction of genes involved in interferon signaling (Fig 5C), including the STAT1 target genes Igtp, Irgm2, Cxcl9 and Cxcl10, as well as master regulators of the interferon response, Irf1 and Stat1 (Fig 5D). GSEA at 7dpi identified signatures primarily associated with collagen formation and muscle repair (Fig 5C). This included tenascin C (Tnc), a tissue remodeling factor; lysyl oxidase (Lox), a secreted enzyme that initiates crosslinking of collagen and elastin; and a series of collagen genes (Col12a1, Col5a1, Col4a1 and Col1a1) (Fig 5D). These finding were consistent with substantial muscle cell hypertrophy and initiation of nurse cell transformation and formation of the collagen capsule at this time. Notably, many genes of glycolysis were significantly induced at 7dpi, including several key regulatory enzymes such as Pfkp, Pygb, Pfkl and Hk3 (Fig 5D). A large set of genes was also markedly reduced in expression by 7dpi and included signatures related to the TCA cycle (e.g. Idh2, Dlat and Mdh1) and striated muscle cell development (e.g. Myh4, Synm and Myot) (Fig 5C and 5D). Collectively, these changes in gene expression programs following infection by NBL describe a robust early induction of STAT1-dependent genes and subsequent loss of myofibers, a strong regenerative response, and a shift in the sources of energy in infected muscle.

Bottom Line: The eosinophil-mediated effect operates in the absence of adaptive immunity.Redistribution of glucose transporter 4 (GLUT4) and phosphorylation of Akt were observed in nurse cells, consistent with enhancement of glucose uptake and glycogen storage by larvae that is known to occur.Our findings document a novel interaction between parasite and host in which worms have evolved a strategy to co-opt an innate host cell response in a way that facilitates their growth.

View Article: PubMed Central - PubMed

Affiliation: Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
It has become increasingly clear that the functions of eosinophils extend beyond host defense and allergy to metabolism and tissue regeneration. These influences have strong potential to be relevant in worm infections in which eosinophils are prominent and parasites rely on the host for nutrients to support growth or reproduction. The aim of this study was to investigate the mechanism underlying the observation that eosinophils promote growth of Trichinella spiralis larvae in skeletal muscle. Our results indicate that IL-4 and eosinophils are necessary for normal larval growth and that eosinophils from IL-4 competent mice are sufficient to support growth. The eosinophil-mediated effect operates in the absence of adaptive immunity. Following invasion by newborn larvae, host gene expression in skeletal muscle was compatible with a regenerative response and a shift in the source of energy in infected tissue. The presence of eosinophils suppressed local inflammation while also influencing nutrient homeostasis in muscle. Redistribution of glucose transporter 4 (GLUT4) and phosphorylation of Akt were observed in nurse cells, consistent with enhancement of glucose uptake and glycogen storage by larvae that is known to occur. The data are consistent with a mechanism in which eosinophils promote larval growth by an IL-4 dependent mechanism that limits local interferon-driven responses that otherwise alter nutrient metabolism in infected muscle. Our findings document a novel interaction between parasite and host in which worms have evolved a strategy to co-opt an innate host cell response in a way that facilitates their growth.

Show MeSH
Related in: MedlinePlus