Cytosolic DNA-sensing Pathway Research Articles

Abstract B031: Heat-inactivated modified vaccinia virus ankara induces type I IFN and antitumor immunity via the cytosolic DNA-sensing pathway

Abstract Type I interferon (IFN), well known for its antiviral activity, is a critical component of cancer immune surveillance through its direct actions on cancer cells as well as on tumor microenvironment. Advanced melanoma remains a therapeutic challenge despite recent progress in targeted therapy and immunotherapy. Novel approaches are needed to alter the tumor immune suppressive microenvironment and to facilitate the recognition of tumor antigens that leads to antitumor immunity. Poxviruses are cytosolic DNA viruses that have been investigated as oncolytic and immunotherapeutic agents. We recently reported that the highly attenuated modified vaccinia virus Ankara (MVA), a safe vaccine for smallpox, triggers type I IFN production in conventional dendritic cells (cDCs) via the cytosolic DNA sensor cGAS and its adaptor STING, and that it requires transcription factors IRF3 and IRF7. Here we show that infection of cDCs with heat-inactivated MVA leads to higher levels of IFN induction than MVA. This induction is also mediated by the cytosolic DNA-sensing pathway cGAS/STING/IRF3/IRF7. In addition, we found that intratumoral injection of Heat-MVA caused tumor eradication in a murine B16 melanoma model as well as the generation of adaptive anti-tumor immunity. Furthermore, Heat-MVA-induced anti-tumor therapy is less effective in STING, IRF7, or Batf3-deficient mice than in wild-type mice, indicating that both the innate immune-sensing pathway and CD8α+DCs are essential for Heat-MVA-based immunotherapy. Lastly, the combination of intratumoral delivery of Heat-MVA with systemic delivery of anti-CTLA-4, PD-1 or PD-L1 antibodies achieved enhanced efficacy in tumor eradication and survival than Heat-MVA alone. Our results have strong implications for the development of poxvirus-based cancer immunotherapeutics as well novel strategies to overcome resistance to immune checkpoint blockade therapy. Citation Format: Peihong Dai, Weiyi Wang, Cristian Serna-Tamayo, Dimitriy Zamarin, Stewart Shuman, Taha Merghoub, Jedd D. Wolchok, Liang Deng. Heat-inactivated modified vaccinia virus ankara induces type I IFN and antitumor immunity via the cytosolic DNA-sensing pathway. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B031.

Expression analysis of cytosolic DNA-sensing pathway genes in the intestinal mucosal layer of necrotic enteritis-induced chicken

Necrotic enteritis (NE) is a serious problem to the poultry farms, which report NE outbreaks more than once per year, as a result of the inappropriate use of antibiotics in the feed. The NE affected bird die rapidly as a result of various pathophysiological complications in the intestine and immune system. Also, several studies have reported that the genes exclusively related to intestine and immune functions are significantly altered in response to NE. In this study, NE was induced in two genetically disparate chicken lines that are resistant (line 6.3) and sensitive (line 7.2) to avian leukosis and Marek's disease. The intestinal mucosal layer was collected from NE-induced and control chickens, and subjected to RNA-sequencing analysis. The involvement of differentially expressed genes in the intestinal mucosal layer of line 6.3 and 7.2 with the immune system-related pathways was investigated. Among the identified immune system-related pathways, a candidate pathway known as chicken cytosolic DNA-sensing pathway (CDS pathway) was selected for further investigation. RNA-sequencing and pathway analysis identified a total of 21 genes that were involved in CDS pathway and differentially expressed in the intestinal mucosal layer of lines 6.3 and 7.2. The expression of CDS pathway genes was further confirmed by real-time qPCR. In the results, a majority of the CDS pathway genes were significantly altered in the NE-induced intestinal mucosal layer from lines 6.3 and 7.2. In conclusion, our study indicate that NE seriously affects several genes involved in innate immune defense and foreign DNA sensing mechanisms in the chicken intestinal mucosal layer. Identifying the immune genes affected by NE could be an important evidence for the protective immune response to NE-causative pathogens.

Serum cytokine profiling analysis for zheng differentiation in chronic hepatitis B.

BackgroundLiver-gallbladder dampness-heat (LGDH) and liver kidney yin deficiency (LKYD) syndromes are Chinese medicine (CM) zhengs in chronic hepatitis B (CHB) patients. This study aims to investigate the changes in cytokines and their profiles accompanied by different biological responses in LGDH and LKYD in CHB.MethodsDuring 2010–2012, a total of 138 morning fasting venous blood samples were obtained from participants in Shuguang Hospital, Shanghai University of Traditional Chinese Medicine in Shanghai, China. First, serum samples from 20 health controls (HCs) and 40 CHB patients (20 LGDH, 20 LKYD) were collected to detect the profiles of cytokines by multiplex biometric ELISA-based immunoassay. Random forest (RF) with a fivefold cross-validation was used to analyze the significant cytokines. Then the significant cytokines were validated using serum samples from an independent cohort of 60 CHB patients (30 LGDH, 30 LKYD) and 18 HCs.ResultsThere were different profiles of cytokines in LGDH and LKYD. Twenty-three significantly differentially expressed cytokines were detected, among which three cytokines, interleukin (IL)-17, macrophage inflammatory protein (MIP)-1α, and MIP-1β, with the largest Gini scores were identified by RF, and further evaluated for their significant changes in serum levels. A receiver-operator characteristic analysis revealed that the logistic regression panel could differentiate LGDH from LKYD (P < 0.001; AUC = 0.827). A functional pathway analysis showed that cytokine–cytokine receptor interaction, cytosolic DNA-sensing pathway, and chemokine signaling pathway overlapped between LGDH and LKYD, whereas Toll-like receptor signaling pathway, intestinal immune network for IgA production, NOD-like receptor signaling pathway, and Jak-STAT signaling pathway were only enriched in LGDH.ConclusionsThere were characteristic cytokines profiles in LGDH and LKYD with different inflammatory and immune responses. IL-17, MIP-1α, and MIP-1β might be involved in the differentiation of LGDH and LKYD in CHB.Electronic supplementary materialThe online version of this article (doi:10.1186/s13020-015-0055-8) contains supplementary material, which is available to authorized users.

Abstract SY39-03: Radiation-mediated DNA sensing pathway for immunity and tumor regression

Abstract It is thought that ablative radiotherapy (RT), used for rapid control tumor growth, induces genotoxic stress and mitosis crisis leading to prolonged dormancy of irradiated tumor at local and distal site in most patients. We have unexpectedly observed that initial reduction of tumor burden following ablative RT also depends largely on type I IFN for CTL. Targeting tumor with IFN can control tumor growth through initiating a coordinated innate and adaptive immune attack against tumor cells. However, the mechanism for radiation-mediated type I IFN induction remains unclear. Here, we demonstrated that STING, but not MYD88, was required for type I IFN-dependent antitumor effects of radiation. STING in dendritic cells (DCs) controlled radiation-mediated IFN-β induction and was activated by irradiated-tumor cells. The cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) mediated DCs sensing of irradiated-tumor cells. Moreover, STING was essential for radiation-induced adaptive immune responses, which relied on type I IFN signaling on DCs. Exogenous IFN-β treatment rescued cGAS/STING-deficient immune responses. Accordingly, enhancing STING signaling by cGAMP administration promoted antitumor efficacy of radiation. Our results reveal that the molecular mechanism of radiation-mediated antitumor immunity depends on a proper cytosolic DNA-sensing pathway, pointing towards a new understanding of radiation and host interactions. Furthermore, we uncover a new strategy to improve radiotherapy by cGAMP treatment. RT induced IFN can also upregulate PD-L1 that suppress T cell-mediated damage and develop radiation resistance for relapse over time. Anti-PDL-1 antibody can greatly reduce radiation resistance leading to complete tumor regression. Furthermore, our study challenges the rationale for current radio/chemotherapy strategies and highlights the importance of immune activation in preventing tumor relapse. Citation Format: Yang-xin Fu. Radiation-mediated DNA sensing pathway for immunity and tumor regression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr SY39-03. doi:10.1158/1538-7445.AM2015-SY39-03

Conservation of the STING-Mediated Cytosolic DNA Sensing Pathway in Zebrafish.

Zebrafish (Danio rerio) is a unique potential model animal for dissecting innate immune signaling. Here we demonstrate that herpes simplex virus 1 (HSV-1) could infect zebrafish at its different developmental stages and trigger the expression of type I interferons (IFNs) as well as interferon-stimulated genes (ISGs) in zebrafish larvae. Silencing of zSTING, but not zMAVS, markedly attenuates the DNA virus-induced antiviral responses. Notably, a conserved serine residue (S373) is essential for the action of zSTING. Unexpectedly, zebrafish cyclic GMP-AMP synthase (cGAS) is dispensable for the STING signaling, whereas zDHX9 and zDDX41 are potential sensors for HSV-1 infection in vivo. Taken together, this proof-of-concept study establishes the zebrafish larva as a feasible model for investigating the cytosolic DNA sensing mechanism, shedding light on the conservation of the STING antiviral signaling pathway. The zebrafish larva provides technical advantages for understanding host-pathogen interactions. In this study, we established the zebrafish larva as a useful model for studying HSV-1 infection. HSV-1 infection triggers strong type I interferon production, which depends on STING expression. In addition, STING-mediated antiviral signaling is conserved in zebrafish. Interestingly, zDHX9 and zDDX41 are indispensable for detecting HSV-1, while cGAS is dispensable. This proof-of-concept study indicates that the zebrafish represents an amenable model for the investigation of cytosolic DNA sensing mechanisms.

STING Negatively Regulates Double-Stranded DNA-Activated JAK1-STAT1 Signaling via SHP-1/2 in B Cells.

Recognition of cytosolic DNA initiates a series of innate immune responses by inducing IFN-I production and subsequent triggering JAK1-STAT1 signaling which plays critical roles in the pathogenesis of infection, inflammation and autoimmune diseases through promoting B cell activation and antibody responses. The stimulator of interferon genes protein (STING) has been demonstrated to be a critical hub of type I IFN induction in cytosolic DNA-sensing pathways. However, it still remains unknown whether cytosolic DNA can directly activate the JAK1-STAT1 signaling or not. And the role of STING is also unclear in this response. In the present study, we found that dsDNA directly triggered the JAK1-STAT1 signaling by inducing phosphorylation of the Lyn kinase. Moreover, this response is not dependent on type I IFN receptors. Interestingly, STING could inhibit dsDNA-triggered activation of JAK1-STAT1 signaling by inducing SHP-1 and SHP-2 phosphorylation. In addition, compared with normal B cells, the expression of STING was significantly lower and the phosphorylation level of JAK1 was significantly higher in B cells from MRL/lpr lupus-prone mice, highlighting the close association between STING low-expression and JAK1-STAT1 signaling activation in B cells in autoimmune diseases. Our data provide a molecular insight into the novel role of STING in dsDNA-mediated inflammatory disorders.

Evasion of innate cytosolic DNA sensing by a gammaherpesvirus facilitates establishment of latent infection.

Herpesviruses are DNA viruses harboring the capacity to establish lifelong latent-recurrent infections. There is limited knowledge about viruses targeting the innate DNA-sensing pathway, as well as how the innate system impacts on the latent reservoir of herpesvirus infections. In this article, we report that murine gammaherpesvirus 68 (MHV68), in contrast to α- and β-herpesviruses, induces very limited innate immune responses through DNA-stimulated pathways, which correspondingly played only a minor role in the control of MHV68 infections in vivo. Similarly, Kaposi's sarcoma-associated herpesvirus also did not stimulate immune signaling through the DNA-sensing pathways. Interestingly, an MHV68 mutant lacking deubiquitinase (DUB) activity, embedded within the large tegument protein open reading frame (ORF)64, gained the capacity to stimulate the DNA-activated stimulator of IFN genes (STING) pathway. We found that ORF64 targeted a step in the DNA-activated pathways upstream of the bifurcation into the STING and absent in melanoma 2 pathways, and lack of the ORF64 DUB was associated with impaired delivery of viral DNA to the nucleus, which, instead, localized to the cytoplasm. Correspondingly, the ORF64 DUB active site mutant virus exhibited impaired ability to establish latent infection in wild-type, but not STING-deficient, mice. Thus, gammaherpesviruses evade immune activation by the cytosolic DNA-sensing pathway, which, in the MHV68 model, facilitates establishment of infections.

Suppression of systemic autoimmunity by the innate immune adaptor STING

Cytosolic DNA-sensing pathways that signal via Stimulator of interferon genes (STING) mediate immunity to pathogens and also promote autoimmune pathology in DNaseII- and DNaseIII-deficient mice. In contrast, we report here that STING potently suppresses inflammation in a model of systemic lupus erythematosus (SLE). Lymphoid hypertrophy, autoantibody production, serum cytokine levels, and other indicators of immune activation were markedly increased in STING-deficient autoimmune-prone mice compared with STING-sufficient littermates. As a result, STING-deficient autoimmune-prone mice had significantly shorter lifespans than controls. Importantly, Toll-like receptor (TLR)-dependent systemic inflammation during 2,6,10,14-tetramethylpentadecane (TMPD)-mediated peritonitis was similarly aggravated in STING-deficient mice. Mechanistically, STING-deficient macrophages failed to express negative regulators of immune activation and thus were hyperresponsive to TLR ligands, producing abnormally high levels of proinflammatory cytokines. This hyperreactivity corresponds to dramatically elevated numbers of inflammatory macrophages and granulocytes in vivo. Collectively these findings reveal an unexpected negative regulatory role for STING, having important implications for STING-directed therapies.

STING-Dependent Cytosolic DNA Sensing Promotes Radiation-Induced Type I Interferon-Dependent Antitumor Immunity in Immunogenic Tumors

Ionizing radiation-mediated tumor regression depends on type I interferon (IFN) and the adaptive immune response, but several pathways control I IFN induction. Here, we demonstrate that adaptor protein STING, but not MyD88, is required for type I IFN-dependent antitumor effects of radiation. In dendritic cells (DCs), STING was required for IFN-? induction in response to irradiated-tumor cells. The cytosolic DNA sensor cyclic GMP-AMP (cGAMP) synthase (cGAS) mediated sensing of irradiated-tumor cells in DCs. Moreover, STING was essential for radiation-induced adaptive immune responses, which relied on type I IFN signaling on DCs. Exogenous IFN-? treatment rescued the cross-priming bycGAS or STING-deficient DCs. Accordingly, activation of STING by a second messenger cGAMP administration enhanced antitumor immunity induced by radiation. Thus radiation-mediated antitumor immunity in immunogenic tumors requires a functional cytosolic DNA-sensing pathway and suggests that cGAMP treatment might provide a new strategy to improve radiotherapy.

Dnase2a Deficiency Uncovers Lysosomal Clearance of Damaged Nuclear DNA via Autophagy

Deficiencies in DNA-degrading nucleases lead to accumulation of self DNA and induction of autoimmunity in mice and in monogenic and polygenic human diseases. However, the sources of DNA and the mechanisms that trigger immunity remain unclear. We analyzed mice deficient for the lysosomal nuclease Dnase2a and observed elevated levels of undegraded DNA in both phagocytic and nonphagocytic cells. In nonphagocytic cells, the excess DNA originated from damaged DNA in the nucleus based on colocalization studies, live-cell imaging, and exacerbation by DNA-damaging agents. Removal of damaged DNA by Dnase2a required nuclear export and autophagy-mediated delivery of the DNA to lysosomes. Finally, DNA was found to accumulate in Dnase2a(-/-) or autophagy-deficient cells and induce inflammation via the Sting cytosolic DNA-sensing pathway. Our results reveal a cell-autonomous process for removal of damaged nuclear DNA with implications for conditions with elevated DNA damage, such as inflammation, cancer, and chemotherapy.

Modified vaccinia virus Ankara triggers type I IFN production in murine conventional dendritic cells via a cGAS/STING-mediated cytosolic DNA-sensing pathway.

Modified vaccinia virus Ankara (MVA) is an attenuated poxvirus that has been engineered as a vaccine against infectious agents and cancers. Our goal is to understand how MVA modulates innate immunity in dendritic cells (DCs), which can provide insights to vaccine design. In this study, using murine bone marrow-derived dendritic cells, we assessed type I interferon (IFN) gene induction and protein secretion in response to MVA infection. We report that MVA infection elicits the production of type I IFN in murine conventional dendritic cells (cDCs), but not in plasmacytoid dendritic cells (pDCs). Transcription factors IRF3 (IFN regulatory factor 3) and IRF7, and the positive feedback loop mediated by IFNAR1 (IFN alpha/beta receptor 1), are required for the induction. MVA induction of type I IFN is fully dependent on STING (stimulator of IFN genes) and the newly discovered cytosolic DNA sensor cGAS (cyclic guanosine monophosphate-adenosine monophosphate synthase). MVA infection of cDCs triggers phosphorylation of TBK1 (Tank-binding kinase 1) and IRF3, which is abolished in the absence of cGAS and STING. Furthermore, intravenous delivery of MVA induces type I IFN in wild-type mice, but not in mice lacking STING or IRF3. Treatment of cDCs with inhibitors of endosomal and lysosomal acidification or the lysosomal enzyme Cathepsin B attenuated MVA-induced type I IFN production, indicating that lysosomal enzymatic processing of virions is important for MVA sensing. Taken together, our results demonstrate a critical role of the cGAS/STING-mediated cytosolic DNA-sensing pathway for type I IFN induction in cDCs by MVA. We present evidence that vaccinia virulence factors E3 and N1 inhibit the activation of IRF3 and the induction of IFNB gene in MVA-infected cDCs.

Discovery of significant pathways in breast cancer metastasis via module extraction and comparison.

Discovering significant pathways rather than single genes or small gene sets involved in metastasis is becoming more and more important in the study of breast cancer. Many researches have shed light on this problem. However, most of the existing works are relying on some priori biological information, which may bring bias to the models. The authors propose a new method that detects metastasis-related pathways by identifying and comparing modules in metastasis and non-metastasis gene co-expression networks. The gene co-expression networks are built by Pearson correlation coefficients, and then the modules inferred in these two networks are compared. In metastasis and non-metastasis networks, 36 and 41 significant modules are identified. Also, 27.8% (metastasis) and 29.3% (non-metastasis) of the modules are enriched significantly for one or several pathways with p-value <0.05. Many breast cancer genes including RB1, CCND1 and TP53 are included in these identified pathways. Five significant pathways are discovered only in metastasis network: glycolysis pathway, cell adhesion molecules, focal adhesion, stathmin and breast cancer resistance to antimicrotubule agents, and cytosolic DNA-sensing pathway. The first three pathways have been proved to be closely associated with metastasis. The rest two can be taken as a guide for future research in breast cancer metastasis.

Construction of the influenza A virus infection-induced cell-specific inflammatory regulatory network based on mutual information and optimization

BackgroundInfluenza A virus (IAV) infection-induced inflammatory regulatory networks (IRNs) are extremely complex and dynamic. Specific biological experiments for investigating the interactions between individual inflammatory factors cannot provide a detailed and insightful multidimensional view of IRNs. Recently, data from high-throughput technologies have permitted system-level analyses. The construction of large and cell-specific IRNs from high-throughput data is essential to understanding the pathogenesis of IAV infection.ResultsIn this study, we proposed a computational method, which combines nonlinear ordinary differential equation (ODE)-based optimization with mutual information, to construct a cell-specific optimized IRN during IAV infection by integrating gene expression data with a prior knowledge of network topology. Moreover, we used the average relative error and sensitivity analysis to evaluate the effectiveness of our proposed approach. Furthermore, from the optimized IRN, we confirmed 45 interactions between proteins in biological experiments and identified 37 new regulatory interactions and 8 false positive interactions, including the following interactions: IL1β regulates TLR3, TLR3 regulates IFN-β and TNF regulates IL6. Most of these regulatory interactions are statistically significant by Z-statistic. The functional annotations of the optimized IRN demonstrated clearly that the defense response, immune response, response to wounding and regulation of cytokine production are the pivotal processes of IAV-induced inflammatory response. The pathway analysis results from the Kyoto Encyclopaedia of Genes and Genomes (KEGG) showed that 8 pathways are enriched significantly. The 5 pathways were validated by experiments, and 3 other pathways, including the intestinal immune network for IgA production, the cytosolic DNA-sensing pathway and the allograft rejection pathway, are the predicted novel pathways involved in the inflammatory response.ConclusionsIntegration of knowledge-driven and data-driven methods allows us to construct an effective IRN during IAV infection. Based on the constructed network, we have identified new interactions among inflammatory factors and biological pathways. These findings provide new insight into our understanding of the molecular mechanisms in the inflammatory network in response to IAV infection. Further characterization and experimental validation of the interaction mechanisms identified from this study may lead to a novel therapeutic strategy for the control of infections and inflammatory responses.

Streptococcus pneumoniaeStimulates a STING- and IFN Regulatory Factor 3-Dependent Type I IFN Production in Macrophages, which Regulates RANTES Production in Macrophages, Cocultured Alveolar Epithelial Cells, and Mouse Lungs

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia. In this study, we examine an innate immune recognition pathway that senses pneumococcal infection, triggers type I IFN production, and regulates RANTES production. We found that human and murine alveolar macrophages as well as murine bone marrow macrophages, but not alveolar epithelial cells, produced type I IFNs upon infection with S. pneumoniae. This response was dependent on the pore-forming toxin pneumolysin and appeared to be mediated by a cytosolic DNA-sensing pathway involving the adapter molecule STING and the transcription factor IFN regulatory factor 3. Indeed, DNA was present in the cytosol during pneumococcal infection as indicated by the activation of the AIM2 inflammasome, which is known to sense microbial DNA. Type I IFNs produced by S. pneumoniae-infected macrophages positively regulated gene expression and RANTES production in macrophages and cocultured alveolar epithelial cells in vitro. Moreover, type I IFNs controlled RANTES production during pneumococcal pneumonia in vivo. In conclusion, we identified an immune sensing pathway detecting S. pneumoniae that triggers a type I IFN response and positively regulates RANTES production.

STING and IRF3 mediate cytosolic innate immune recognition of Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of community-acquired pneumonia and sepsis world-wide. The innate immune system detects S. pneumoniae through pattern-recognition receptors including Toll-like receptors (TLRs) and NOD-like receptors (NLRs). In this project, we examine an additional innate immune recognition pathway sensing pneumococcal infection. We found that both murine and human alveolar macrophages produced type I Interferons (IFNs) upon infection with S. pneumoniae. This response was dependent on the pore-forming toxin pneumolysin but independent of the capsule. Moreover, it was mediated through a cytosolic DNA-sensing pathway involving the adaptor molecule STING as well as the transcription factor IRF3. It was, however, independent of TLRs, NOD2, as well as the RIG-I-like receptors. In conclusion, we identified an immune sensing pathway detecting S. pneumoniae that triggers type I IFN responses. Type I IFNs might be important regulators of the immune response in pneumococcal pneumonia.

TLR9 and IRF3 Cooperate to Induce a Systemic Inflammatory Response in Mice Injected With Liposome:DNA

Liposome:DNA is a promising gene therapy vector. However, this vector can elicit a systemic inflammatory response syndrome (SIRS). Prior reports indicate that liposome:DNA vectors activate Toll-like receptor (TLR)9. We hypothesized that liposome:DNA vectors also activate the cytosolic DNA-sensing pathway, which signals via interferon (IFN) regulatory factor (IRF)3. To test this, we treated dendritic cells (DCs) with liposome:DNA in vitro and found that IRF3 was phosphorylated independent of TLR9. To test the contribution of this pathway in vivo, we injected a liposome:DNA vector into wild-type (WT), TLR9-knockout (KO), IRF3-KO, and TLR9-IRF3-double-KO (DKO) mice. WT mice exhibited a systemic inflammatory response, evidenced by elevations in serum cytokines, serum enzyme changes indicating organ damage, hypothermia, and mortality. The cytokine response was reduced in TLR9-KO, IRF3-KO, and TLR9-IRF3-DKO mice and all three groups survived. We found that IFN-gamma-KO mice that receive liposome:DNA had a reduced cytokine response and 100% survival. CD11c(+) and NK1.1(+) cells produced IFN-gamma and depleting CD11c(+) cells reduced the cytokine response in mice injected with liposome:DNA. These findings may facilitate the development of immunologically inert gene therapy vectors and may provide general insight into the mechanisms of SIRS.

New DNA-sensing pathway feeds RIG-I with RNA

Cytosolic DNA sensors have remained poorly defined so far. Two recent studies identify a previously undefined cytosolic DNA-sensing pathway that depends on the RNA polymerase III–mediated conversion of microbial DNA into 5′-triphosphate double-stranded RNA that activates the RNA helicase RIG-I.