Project description:In this study, we show that the host response to DENV infection in immunocompetent mice recapitulates transcriptional changes that have been described in human studies. We found that DENV infection induced metabolic dysregulation and inflammatory responses, and also affected the immune cell content of the spleen and liver. Use of the mast cell stabilization drug, ketotifen, reversed many of these responses, and induced additional changes in the transcriptome and immune cell repertoire that contribute to decreased dengue disease.
Project description:In this study, we show that the host response to DENV infection in immunocompetent mice recapitulates transcriptional changes that have been described in human studies. We found that DENV infection induced metabolic dysregulation and inflammatory responses, and also affected the immune cell content of the spleen and liver. Use of the mast cell stabilization drug, ketotifen, reversed many of these responses, and induced additional changes in the transcriptome and immune cell repertoire that contribute to decreased dengue disease.
Project description:Background: Dengue virus (DENV) infection induces various clinical manifestations and even causes organ injuries, leading to severe dengue haemorrhagic fever and dengue shock syndrome. Hepatic dysfunction was identified as a risk predictor of progression to severe disease during the febrile phase of dengue. However, the underlying mechanisms of hepatic injury remain unclear. Methods: A model of dengue disease was established in IFNAR−/− C57BL/6 mice by challenge with DENV-2. Body weight, symptoms, haematological parameters and liver pathological observations in mice were used to determine the effects of DENV infection. Liver transcriptome sequencing was performed to evaluate the features of the host response FNAR mice challenged with DENV. Functional enrichment analysis and analysis of significantly differentially expressed genes (DEGs) were used to determine the critical molecular mechanism of hepatic injury. Results: We observed haemoconcentration, leukopenia and liver pathologies in mice, consistent with findings in clinical dengue patients. Some differences in gene expression and biological processes were identified in this study. Transcriptional patterns in the liver indicated that antiviral responses to DENV and tissue damage via abnormal expression of proinflammatory cytokines were induced. Further analysis showed that the upregulated DEGs were significantly enriched in the leukocyte transendothelial migration, complement and coagulation cascades, and cytokine-cytokine receptor interactions signalling pathways, which are considered to be closely associated with the pathogenic mechanism of dengue. IL6, IL 10, ICAM-1, VCAM-1, MMP9 and NLRP3 were identified as biomarkers of progression to severe disease. Conclusions: The interactions of these cytokines, which activate inflammatory signalling, may lead to organ injury and haemoconcentration and even to vascular leakage in tissues, including the mouse liver. Our study identifies candidate host targets that could be used for further functional verification. In this study, we aimed to evaluate the transcriptomics features of liver injury in a mouse model of dengue virus infection based on a lethal animal model, and then perform a series of functional analyses to partially elucidate the underlying pathogenesis of DENV-induced liver injury.
Project description:In this study, we show that the host response to DENV1-4 infection in immunocompetent mice recapitulates transcriptional and immunological changes that have been described in human studies. Dengue virus (DENV), a Flavivirus, causes a broad spectrum of disease in humans with key clinical signs including thrombocytopenia, vascular leakage and hemorrhaging. A major obstacle to understanding DENV immunity has been the lack of a validated immune-competent mouse model. Here, we report the infection profiles of human clinical isolates of DENV serotypes 1-4 in an immune-competent mouse model. We detected replicating DENV in the peritoneal cells, liver and the spleen that was generally resolved within 2 weeks. The DENV target cell types for infection were monocytes/macrophages, dendritic cells, endothelial cells, and we identified a novel DENV cellular target, fibroblast reticular cells of the spleen. We observed gross pathologies in the spleen and liver that are consistent with dengue disease, including hemorrhaging as well as transcriptional patterns suggesting that antiviral responses and tissue damage were induced. Key clinical blood parameters that define human DENV disease such as hemoconcentration, leukopenia and reduced number of platelets were also observed. Thus, immune-competent mice sustain replicating infection and experience signs, such as hemorrhaging, that define DENV disease in humans. This study thoroughly characterizes DENV1-4 infection in immune-competent mice and confirms the wild-type mouse model as a valid and reproducible system for investigating the mechanisms of DENV pathogenesis.
Project description:In this study, we show that the host response to DENV1-4 infection in immunocompetent mice recapitulates transcriptional and immunological changes that have been described in human studies. Dengue virus (DENV), a Flavivirus, causes a broad spectrum of disease in humans with key clinical signs including thrombocytopenia, vascular leakage and hemorrhaging. A major obstacle to understanding DENV immunity has been the lack of a validated immune-competent mouse model. Here, we report the infection profiles of human clinical isolates of DENV serotypes 1-4 in an immune-competent mouse model. We detected replicating DENV in the peritoneal cells, liver and the spleen that was generally resolved within 2 weeks. The DENV target cell types for infection were monocytes/macrophages, dendritic cells, endothelial cells, and we identified a novel DENV cellular target, fibroblast reticular cells of the spleen. We observed gross pathologies in the spleen and liver that are consistent with dengue disease, including hemorrhaging as well as transcriptional patterns suggesting that antiviral responses and tissue damage were induced. Key clinical blood parameters that define human DENV disease such as hemoconcentration, leukopenia and reduced number of platelets were also observed. Thus, immune-competent mice sustain replicating infection and experience signs, such as hemorrhaging, that define DENV disease in humans. This study thoroughly characterizes DENV1-4 infection in immune-competent mice and confirms the wild-type mouse model as a valid and reproducible system for investigating the mechanisms of DENV pathogenesis.
Project description:Background: Organ dysfunction, especially liver injury, caused by dengue virus (DENV) infection has been associated with fatal cases in dengue patients around the world. However, the pathophysiological mechanisms of liver involvement in dengue remain unclear. There is accumulating evidence that miRNAs are playing an important role in regulating viral pathogenesis, and it can help in diagnostic and anti-viral therapies development. Methods: We collected liver tissues of DENV-infected for small RNA sequencing to identify significantly different express miRNAs during dengue virus infection, and the identified target genes of these miRNAs were annotated by biological function and pathway enrichment. Results: 31 significantly altered miRNAs were identified, including 16 up-regulated and 15 down-regulated miRNAs. By performing a series of miRNA prediction and signaling pathway enrichment analyses, the down-regulated miRNAs of mmu-miR-484, mmu-miR-1247-5p and mmu-miR-6538 were identified to be the crucial miRNAs. Further analysis revealed that the inflammation and immune responses involving Hippo, PI3K-Akt, MAPK, Wnt, mTOR, TGF-beta, Tight junction, and Platelet activation were modulated collectively by these three key miRNAs during DENV infection. These pathways are considered to be closely associated with the pathogenic mechanism and treatment strategy of dengue patients. Conclusion: The miRNAs identified by sequencing, especially miR-484 may be the potential therapeutic targets for liver involvement in dengue patients which involves the regulation of vascular permeability and expression of inflammatory cytokines. In this study, RNA-Seq analysis of liver tissues from a mouse model after DENV infection was performed to identify differential miRNA expression profiles, predicted target genes, and analyzed the biological functions and pathways involved in the regulation of differential miRNAs, contributing to the understanding of the mechanisms of liver tissue involvement after DENV infection.
Project description:Retinopathy of prematurity (ROP) is the most common cause of childhood blindness worldwide and is caused by oxygen therapy necessary to prevent mortality after premature birth. We have previously demonstrated the efficacy of systemic hypoxia inducible factor (HIF) stabilization through HIF prolyl hydroxylase inhibition (HIF PHi) in protecting retinal vasculature from oxygen toxicity in a mouse model of ROP or oxygen induced retinopathy (OIR). We definitively demonstrated that hepatic HIF-1 can be activated to confer this protection using systemic dimethyloxalylglycine (DMOG) to prevent HIF-1α degradation. In this study we compare Roxadustat, a small molecule stabilizer of HIF-1 currently in phase 3 clinical trials for increasing erythropoiesis in adult patients with chronic kidney disease, to DMOG. We demonstrate that Roxadustat induces vascular protection during hyperoxia to induce the coordinated sequential growth of retinal vasculature with a 3-fold reduction in oxygen induced capillary loss (p-=0.001). In order to define the molecular mechanism of protection, we further compared the transcriptome of both liver and retina after systemic treatment with Roxadustat or DMOG. Similar gene expression profiles were identified in liver but very different effects on transcription were found in retinal tissues because Roxadustat, in contrast to DMOG, directly targets retina, confirmed by western blot and by rescue of the hepatic HIF-1 KO, two criteria that DMOG treatment is unable to fulfill. Systems pharmacologic analysis demonstrates that Roxadustat induces typical HIF regulated genes critical to aerobic glycolysis in liver and retinal tissues whereas DMOG, acting through either secreted hepatokines or by influence of systemic DMOG, downregulates cell adhesion/extracellular matrix interaction pathways while increasing expression of histone cluster genes. Stratification of liver transcriptomes to secreted gene products again shows close consensus of hepatic genes induced by both small molecules, and includes upregulation of a plethora of angiogenic proteins such as plasminogen activator inhibitor (PAI-1), erythropoietin (EPO), and orosomucosoid 2 (ORM2). Secondary validation of these transcripts by serum ELISA confirms secretion of EPO and PAI-1 into blood from liver. These findings definitively demonstrate that HIF stabilization can prevent OIR by two pathways: direct retinal HIF stabilization and induction of aerobic glycolysis or indirect, hepatic HIF-1 stabilization and increased serum angiokines. Systems pharmacology analysis therefore explains why intermittent, low dosage of small molecule HIF stabilizers creates a profound protective phenotype, because both pathways can take advantage of cytoprotection induced by the liver and by retina synergistically. These data provide a rationale for considering low dose, intermittent systemic administration of Roxadustat, currently in phase 3 trials in adults with chronic kidney disease, to eradicate ROP in children.
Project description:In patients with chronic pulmonary disease colonization with the mold Aspergillus fumigatus is associated with declining pulmonary function and obstructive airway disease. One potential effector of this inflammatory response is the pulmonary mast cell. In vitro studies have demonstrated that A. fumigatus contact induces IgE-independent mast cell degranulation. Conversely, the Aspergillus secondary metabolite gliotoxin has been shown to suppress mast cell activation. These contradictory results emphasize the need for a better understanding of the interactions between A. fumigatus and mast cells. Thus, the objective of this work was to identify A. fumigatus genes that are differentially regulated upon exposure to mast cells. Transcriptional profiling experiments indicated that, in addition to genes encoding for iron acquisition systems, allergens and putative virulence factors, genes from the gliotoxin biosynthesis cluster were significantly down-regulated upon exposure to mast cells. Globally, the results from this study provide insight into the A. fumigatus response to mast cells and suggest that one mechanism by which the host may circumvent the effects of gliotoxin is via the suppression of fungal gliotoxin synthesis by mast cells.