Project description:The stimulator-of-interferon-gene (STING) pathway controls both DNA and RNA virus infection. STING is essential for induction of innate immune responses during DNA virus infection, while its mechanism against RNA virus remains largely elusive. We show that STING signaling is crucial for restricting Chikungunya virus infection and arthritis pathogenesis. Sting-deficient mice (Stinggt/gt) had elevated viremia throughout the viremic stage and viral burden in the feet transiently, along with a normal type I IFN response. Stinggt/gt mice presented much greater foot swelling, joint damage and immune cell infiltration than WT mice. Intriguingly, expression of interferon gamma and its induced Cxcl10 was continuously upregulated by ~7-10-fold, and further elevated in Stinggt/gt mice synchronously with arthritis progression. However, expression of chemoattractants for and activators of neutrophils, Cxcl5, Cxcl7 and Cxcr2 was suppressed in Stinggt/gt joints. These results demonstrate that STING deficiency leads to an aberrant chemokine response that promotes pathogenesis of CHIKV arthritis.
Project description:The stimulator of interferon gene (STING) pathway controls both DNA and RNA virus infection. STING is essential for induction of innate immune responses during DNA virus infection, while its mechanism against RNA virus remains largely elusive. We show that STING signaling is crucial for restricting chikungunya virus infection and arthritis pathogenesis. Sting-deficient mice (Stinggt/gt) had elevated viremia throughout the viremic stage and viral burden in feet transiently, with a normal type I IFN response. Stinggt/gt mice presented much greater foot swelling, joint damage, and immune cell infiltration than wild-type mice. Intriguingly, expression of interferon-γ and Cxcl10 was continuously upregulated by approximately 7 to 10-fold and further elevated in Stinggt/gt mice synchronously with arthritis progression. However, expression of chemoattractants for and activators of neutrophils, Cxcl5, Cxcl7, and Cxcr2 was suppressed in Stinggt/gt joints. These results demonstrate that STING deficiency leads to an aberrant chemokine response that promotes pathogenesis of CHIKV arthritis.
Project description:In this study, we aim to identify common host genes involved in pathogenesis of different Chikungunya virus strains as an attempt to recognize probable antiviral targets. We have compared the host gene regulation after infection of monkey kidney cell line (Vero) with two different wild type CHIKV strains i.e. S 27 (human, ECSA), and DRDE-06 (human, ECSA). Vero cells were mock infected or infected with two Chikungunya virus strains (S 27 and DRDE-06) and harvested at 8hpi and 18hpi. The total RNA was extracted and microarray was done using Agilent protocol.
Project description:Chikungunya virus (CHIKV) is a mosquito-borne virus that causes acute, subacute, and chronic human diseases and can cause neurological complications and death. Here, we combined epidemiological, virological, histopathological, cytokine, molecular dynamics, metabolomics, proteomics, and genomic analyses to investigate viral and pathophysiologic factors that contribute to deaths caused by chikungunya (CHIK). Our results indicate that CHIK-deaths presented multiple organs infection, central nervous system damage, and exhibited significantly elevated serum levels of pro-inflammatory cytokines and chemokines compared to survivors. The histopathology, metabolite, and proteomic signatures of CHIK-deaths revealed hemodynamic disorders and dysregulated immune system response. CHIKV East-Central-South-African lineage caused fatal and survivor cases, and CHIKV crosses the blood–brain barrier without tight junction alterations. IFN-λ3 was highly expressed in fatal cases but did not present a direct antiviral effect on CHIKV replication in vitro. In summary, our results reveal insights to improve understanding of CHIK pathogenesis, especially the pathophysiology of fatal infections.
Project description:Cellular lipid requirements are achieved through a combination of biosynthesis and import programs. Using isotope tracer analysis, we show that type I interferon (IFN) signaling rapidly shifts the balance of these programs by decreasing synthesis and increasing import of cholesterol and long chain fatty acids. Genetically enforcing this metabolic shift in macrophages is sufficient to render mice resistant to viral challenge, demonstrating the importance of reprogramming the balance of these two metabolic pathways in vivo. Unexpectedly, mechanistic studies reveal that limiting flux through the cholesterol biosynthetic pathway spontaneously engages a type I IFN response in a STING-dependent manner. The upregulation of type I IFNs was traced to a decrease in the pool size of synthesized cholesterol, and could be inhibited by replenishing cells with free cholesterol. Taken together, these studies delineate a metabolic-inflammatory circuit that links perturbations in cholesterol biosynthesis with activation of innate immunity. shRNA to SREBF1 (shSREBP1) or SREBF2 (shSREBP2) were stably introduced via 3rd generation lentivirus into human THP1 monocytic cells under puromycin selection. Non-targeting shRNA scramble was used for a control (shControl). shControl, shSREBP1 and shSREBP2 modified cell types were analyzed by RNA-seq in duplicate.
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from wild type murine embryonic fibroblasts (WT MEFs), STING deficient MEFs (SKO), Trex1 deficient MEFs (TKO), and both STING and Trex1 deficient MEFs (STKO) treated with DMBA and examined cytokine production by these cells.
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from DMBA or acetone treated wild type (WT) or STING deficient (SKO) mouse skin or skin tumor was examined for gene expression.
Project description:A number of inhibitors of chemokine CCL2 and its receptor CCR2 are in development and may find application for treating a range of inflammatory conditions, including autoimmune and viral arthritides. Herein we sought to determine the effect of CCR2 deficiency on arthritis caused by an arthritogenic alphavirus, Chikungunya virus. Chikungunya virus (LR2006-OPY1) was injected subcutaneously into the hind foot of either CCR2 knockout or wild-type control mice (n=4-6). At day 0 and d7 post infection, RNA from the feet was harvested, the RNA was pooled (4-6 feet per time point per mouse strain) and gene expression analysis was performed using Mouse Gene ST arrays (Affymetrix).