Cyclic Guanosine Monophosphate-adenosine Monophosphate Research Articles

Single-Dose Physically Cross-Linked Hyaluronic Acid and Lipid Hybrid Nanoparticles Containing Cyclic Guanosine Monophosphate-Adenosine Monophosphate Eliminate Established Tumors.

Activating the STING pathway in the cytosol of tumor-infiltrating antigen-presenting cells (APCs) represents a promising strategy to elicit potent antitumor immune responses for cancer therapy. However, STING agonists are mostly small hydrophilic molecules that suffer from rapid clearance and poor cytosolic delivery following systemic administration. While various nanoparticles have been developed to promote cytosolic delivery, they often exhibit premature drug release during circulation. Alternatively, stable nanoparticles with sustained release during circulation have poor cytosolic delivery. In this study, we have developed physically cross-linked hyaluronic acid (HA) and lipid hybrid nanoparticles containing cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), denoted as HLHC, to address these challenges. The HLH delivery system has sustained drug release due to multiple lipid layers physically cross-linked by HA. HLHC efficiently delivers cGAMP to the cytosol of APCs, inducing more IFNβ than cGAMP and liposomal cGAMP. HLH also improves the drug circulation time and biodistribution to the tumor compared with the liposomal formulation and free drug. Strikingly, a single dose of HLHC, but not liposomal cGAMP or free cGAMP, elicits potent antitumor immunity and regresses established MC38 tumors. A single dose of HLHC even regresses established B16F10 tumors upon combination with αPD-L1. Moreover, cured animals were protected from rechallenge with the same tumor cells. HLHC represents an efficient strategy to address delivery challenges associated with STING agonists and may have broad applications for the delivery of drugs acting in the cytosol.

Novel Photo-STING Agonists Delivered by Erythrocyte Efferocytosis-Mimicking Pattern to Repolarize Tumor-Associated Macrophages for Boosting Anticancer Immunotherapy.

Immunotherapy has emerged as a highly effective therapeutic strategy for cancer treatment. Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon gene (STING) pathway activation facilitates tumor-associated macrophage (TAM) polarization toward M1 phenotype, and Mn2+ are effective agents for this pathway activation. However, the high in vivo degradation rate and toxicity of Mn2+ hamper clinical application of immunotherapy. Here, this work has newly synthesized and screened manganese porphyrins for Mn2+ transport, referred to as photo-STING agonists (PSAs), and further encapsulate them into core-shell nanoparticles named Rm@PP-GA with dual specificity for tumor tissue and TAMs. Not only do PSAs achieve higher Mn2+ delivery efficiency compared to Mn2+, but they also generate reactive oxygen species under light exposure, promoting mitochondrial DNA release for cGAS-STING pathway activation. In Rm@PP-GA, globin and red blood cell membranes (Rm) are used for erythrocyte efferocytosis-mimicking delivery. Rm can effectively prolong the in vivo circulation period while globin enables PSAs to be taken up by TAMs via CD163 receptors. After Rm rupture mediated by perfluorohexane in nanoparticles under ultrasonication, drugs are specifically released for TAM repolarization. Further, dendritic cells mature, as well as T lymphocyte infiltrate, both of which favor tumor eradication. Therefore, cancer immunotherapy is optimized by novel PSAs delivered by erythrocyte efferocytosis-mimicking delivery pattern.

STING agonists and PI3Kγ inhibitor co-loaded ferric ion-punicalagin networks for comprehensive cancer therapy

Nanoparticles-based drug delivery system has been a promising approach for the treatment of colorectal cancer (CRC), which can be combined with chemotherapy, targeted therapy and immunotherapy to improve the treatment of CRC. 2′3’ cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) is an agonist of the STING signaling pathway activating antitumor immunity. IPI-549 is a small-molecule inhibitor for phosphatidylinositol 3-kinase γ (PI3Kγ), which can induce M1 macrophages polarization to provide pro-inflammatory microenvironment to suppress tumors. Here, we developed a ferric ion-punicalagin network (Fe-PU), which can be not only used as an inducer of ferroptosis, but also serve as a carrier to load cGAMP and IPI-549 to obtain nanohybrid (Fe-PU/CD-IPI). In order to improve the delivery effect and targeted ability to CRC, a cyclic arginine-glycine-aspartic acid peptide linked-bovine serum albumin were utilized to modify Fe-PU/CD-IPI to prepare nanohybrid Fe-PU/CD-IPI@cBSA. The therapeutic effect of various nanohybrids were validated in the mice with spontaneous tumor in the colorectal area and tumor-bearing mice, which lead to the increase of ferroptosis, the activation of STING signaling pathway, and the repolarization of macrophages. Collectively, the cGAMP and IPI-549 co-loaded nanohybrids effectively reshaped the tumor immune microenvironment, and exhibited prominent treatment effect of anti-colorectal cancer in vitro, patient-derived organoids, and in vivo.

Assembly of 2′,3′-Cyclic guanosine Monophosphate-Adenosine monophosphate and their spontaneous intracellular disassembly for enhanced antitumor immunity via natural STING pathway activation

The stimulator of interferon genes (STING) pathway plays an important role in remodeling the immunosuppressive tumor microenvironment (TME). Cyclic dinucleotides (CDNs), the natural ligands of STING, activate innate immunity to enhance tumor immunogenicity. However, the anionic properties of CDNs result in poor membrane permeability, while their rapid metabolism by enzymes hinders the efficient targeting and activation of STING in vitro and in vivo. To improve the bioavailability and antitumor immunity of CDNs, we designed a hydrogen-bonding-based supramolecular approach for 2′,3′-cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP). Leveraging the synthetic molecules cytosine-uracil-hexane (CUH), we formulated supramolecular micelles of cGAMP via specific hydrogen bonds in aqueous solutions. Micelles comprising the CUH-cGAMP complex enhanced the biological efficacy of cGAMP by increasing its stability, thereby prolonging the activation of STING-mediated innate and adaptive immunity. We demonstrated that CUH-cGAMP stands as a promising candidate for immunotherapy, exhibiting significant inhibition of tumor growth in a CT26 syngeneic mouse model.

The Role of STING-Mediated Activation of Dendritic Cells in Cancer Immunotherapy.

The signaling pathway that comprises cyclic guanosine monophosphate-adenosine monophosphate (cGAMP or GMP-AMP) synthase (cGAS) and Stimulator of Interferon Genes (STING) is emerging as a druggable target for immunotherapy, with tumor-resident dendritic cells (DC) playing a critical role in mediating its effects. The STING receptor is part of the DNA-sensing cellular machinery, that can trigger the secretion of pro-inflammatory mediators, priming effector T cells and initiating specific antitumor responses. Yet, recent studies have highlighted the dual role of STING activation in the context of cancer: STING can either promote antitumor responses or enhance tumor progression. This dichotomy often depends on the cell type in which cGAS-STING signaling is induced and the activation mode, namely acute versus chronic. Of note, STING activation at the DC level appears to be particularly important for tumor eradication. This review outlines the contribution of the different conventional and plasmacytoid DC subsets and describes the mechanisms underlying STING-mediated activation of DCs in cancer. We further highlight how the STING pathway plays an intricate role in modulating the function of DCs embedded in tumor tissue. Additionally, we discuss the strategies being employed to harness STING activation for cancer treatment, such as the development of synthetic agonists and nano-based delivery systems, spotlighting the current techniques used to prompt STING engagement specifically in DCs.

Manganese-Modified Aluminum Adjuvant Enhances both Humoral and Cellular Immune Responses.

Aluminum adjuvants remain the most commonly used vaccine adjuvants. Being rather effective in triggering humoral immunity, however, aluminum adjuvants usually show limited abilities in activating cellular immunities. Herein, by adding manganese ions during the preparation of aluminum adjuvant, a manganese-modified aluminum (Mn-Al) adjuvant is obtained, which can effectively stimulate both humoral and cellular immune responses. Such Mn-Al adjuvant can enhance antigen adsorption and promote antigen internalization by dendritic cells (DCs). Subsequently, the released Mn2+ can activate the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway to further promote DC activation. When combines with the model antigen ovalbumin (OVA), the Mn-Al-adjuvantes vaccine can induce high levels of antigen-specific antibody titers and high proportions of antigen-specific cytotoxic T cells in vivo. Moreover, the Mn-Al-adjuvanted vaccine elicited stronger antigen-specific humoral and cellular immune responses than high-dose of the aluminum-based adjuvant. Additionally, immunization of mice with OVA in the presence of the Mn-Al adjuvant significantly inhibited the growth of B16-OVA tumors. Furthermore, when formulated with human papillomavirus antigens, Mn-Al-adjuvanted vaccines show better in vivo vaccination performance than aluminum-adjuvanted vaccines. Therefore, the manganese-modified aluminum adjuvant may thus become a new vaccine adjuvant with the potential to replace conventional aluminum adjuvants.

Napabucasin deactivates STAT3 and promotes mitoxantrone-mediated cGAS-STING activation for hepatocellular carcinoma chemo-immunotherapy

The immune resistance of tumor microenvironment (TME) causes immune checkpoint blockade therapy inefficient to hepatocellular carcinoma (HCC). Emerging strategies of using chemotherapy regimens to reverse the immune resistance provide the promise for promoting the efficiency of immune checkpoint inhibitors. The induction of cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) in tumor cells evokes the adaptive immunity and remodels the immunosuppressive TME. In this study, we report that mitoxantrone (MIT, a chemotherapeutic drug) activates the cGAS-STING signaling pathway of HCC cells. We provide an approach to augment the efficacy of MIT using a signal transducer and activator of transcription 3 (STAT3) inhibitor called napabucasin (NAP). We prepare an aminoethyl anisamide (AEAA)-targeted polyethylene glycol (PEG)-modified poly (lactic-co-glycolic acid) (PLGA)-based nanocarrier for co-delivery of MIT and NAP. The resultant co-nanoformulation can elicit the cGAS-STING-based immune responses to reshape the immunoresistant TME in the mice orthotopically grafted with HCC. Consequently, the resultant co-nanoformulation can promote anti-PD-1 antibody for suppressing HCC development, generating long-term survival, and inhibiting tumor recurrence. This study reveals the potential of MIT to activate the cGAS-STING signaling pathway, and confirms the feasibility of nano co-delivery for MIT and NAP on achieving HCC chemo-immunotherapy.

Shuangdan Jiedu Decoction improved LPS-induced acute lung injury by regulating both cGAS-STING pathway and inflammasome

Ethnopharmacological relevanceShuangdan Jiedu Decoction (SJD) is a formula composed of six Chinese herbs with heat-removing and detoxifying, antibacterial, and anti-inflammatory effects, which is clinically used in the therapy of various inflammatory diseases of the lungs including COVID-19, but the therapeutic material basis of its action as well as its molecular mechanism are still unclear. Aim of the studyThe study attempted to determine the therapeutic effect of SJD on LPS-induced acute lung injury (ALI), as well as to investigate its mechanism of action and assess its therapeutic potential for the cure of inflammation-related diseases in the clinical setting. Materials and methodsWe established an ALI model by tracheal drip LPS, and after the administration of SJD, we collected the bronchoalveolar lavage fluid (BALF) and lung tissues of mice and examined the expression of inflammatory factors in them. In addition, we evaluated the effects of SJD on the cyclic guanosine monophosphate-adenosine monophosphate synthase –stimulator of interferon genes (cGAS-STING) and inflammasome by immunoblotting and real-time quantitative polymerase chain reaction (RT-qPCR). ResultsWe demonstrated that SJD was effective in alleviating LPS-induced ALI by suppressing the levels of pro-inflammatory cytokines in the BALF, improving the level of lung histopathology and the number of neutrophils, as well as decreasing the inflammatory factor-associated gene expression. Importantly, we found that SJD could inhibit multiple stimulus-driven activation of cGAS-STING and inflammasome. Further studies showed that the Chinese herbal medicines in SJD had no influence on the cGAS-STING pathway and inflammasome alone at the formulated dose. By increasing the concentration of these herbs, we observed inhibitory effects on the cGAS-STING pathway and inflammasome, and the effect exerted was maximal when the six herbs were combined, indicating that the synergistic effects among these herbs plays a crucial role in the anti-inflammatory effects of SJD. ConclusionsOur research demonstrated that SJD has a favorable protective effect against ALI, and its mechanism of effect may be associated with the synergistic effect exerted between six Chinese medicines to inhibit the cGAS-STING and inflammasome abnormal activation. These results are favorable for the wide application of SJD in the clinic as well as for the development of drugs for ALI from herbal formulas.

CGAS-STING activation by nanodelivery of teniposide achieves colorectal cancer chemo-immunotherapy

Colorectal cancer (CRC) has become the second leading cause of cancer-related death. Recently, the strategies to combine chemotherapy and immunotherapy (termed chemo-immunotherapy) have provided new opportunities for treating cancers. The activation of cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) signaling pathway elicits the anticancer immune response. Certain chemotherapy drugs can not only cause cancer cell death, but are also able to trigger the cGAS-STING activation of cancer cells, giving rise to chemo-immunotherapy to cancers. In the present study, teniposide (TEN; a semi-synthetic derivative of podophyllotoxin) caused the cytotoxicity and apoptosis to CRC cells and, during this process, induced the cGAS-STING activation in CRC cells. A nanoformulation was prepared using the aminoethyl anisamide (AEAA)-targeted polyethylene glycol (PEG)-decorated poly(lactic-co-glycolic acid) (PLGA) to achieve CRC-specific delivery of TEN. Consequently, the obtained nanoformulation caused the cancer cell apoptosis, and induced the cGAS-STING-mediated anticancer immune response, collectively leading to chemotherapeutic and immunotherapeutic effects in mice orthotopically grafted by CRC. The present study confirms the capacity of TEN for inducing the cGAS-STING activation of CRC cells, and demonstrates the feasibility of nanodelivery of TEN for CRC chemo-immunotherapy.

CGAS-activated endothelial cell-T cell cross-talk initiates tertiary lymphoid structure formation.

Aberrant activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway causes autoimmunity in humans and mice; however, the exact mechanism by which the cGAS-STING pathway initiates adaptive immunity and tissue pathology is still not fully understood. Here, we used a cGAS knockin (KI) mouse model that develops systemic autoimmunity. In the lungs of cGAS-KI mice, blood vessels were enclosed by organized lymphoid tissues that resemble tertiary lymphoid structures (TLSs). Cell-intrinsic cGAS induction promoted up-regulation of CCR5 in CD8+ T cells and led to CCL5 production in vascular endothelial cells. Peripheral CD8+ T cells were recruited to the lungs and produced CXCL13 and interferon-γ. The latter triggered endothelial cell death, potentiated CCL5 production, and was essential for TLS establishment. Blocking CCL5 or CCR5, or depleting CD8+ T cells, impaired TLS formation. cGAS-mediated TLS formation also enhanced humoral and antitumor responses. These data demonstrate that cGAS signaling drives a specialized lymphoid structure that underlies autoimmune tissue pathology.

STING activation disrupts tumor vasculature to overcome the EPR limitation and increase drug deposition.

The low success rate of cancer nanomedicines has raised debate on the role of the enhanced permeability and retention (EPR) effect on tumor deposition of nanotherapeutics. Here, we report a bifunctional nanoscale coordination polymer (NCP), oxaliplatin (OX)/2',3'-cyclic guanosine monophosphate-adenosine monophosphate (GA), to overcome the EPR limitation through stimulator of interferon genes (STING) activation and enhance chemotherapeutic and STING agonist delivery for tumor eradication. OX/GA encapsulates GA and OX in the NCP to protect GA from enzymatic degradation and improve GA and OX pharmacokinetics. STING activation by OX/GA disrupts tumor vasculatures and increases intratumoral deposition of OX by 4.9-fold over monotherapy OX-NCP. OX/GA demonstrates exceptional antitumor effects with >95% tumor growth inhibition and high cure rates in subcutaneous, orthotopic, spontaneous, and metastatic tumor models. OX/GA induces immunogenic cell death of tumor cells and STING activation of innate immune cells to enhance antigen presentation. NCPs provide an excellent nanoplatform to overcome the EPR limitation for effective cancer therapy.

H-151, a Selective STING Inhibitor, Has Potential as a Treatment for Neovascular Age-Related Macular Degeneration.

The cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) stimulator of interferon gene (STING) pathway is a crucial cascade in the inflammatory response initiated by the recognition of cytosolic double-stranded DNA (dsDNA). The aim of this study was to evaluate the effect of STING inhibitor in murine choroidal neovascularization (CNV). To investigate whether the cGAS-STING pathway is activated during CNV, CNV was induced using laser photocoagulation in male C57BL/6J mice. The expression of change of cGAS and STING during CNV development was confirmed by Western-blotting. H-151, a potent STING palmitoylation antagonist, was used as a STING inhibitor. H-151 was administered intravitreally immediately after laser induction. To confirm the role of the cGAS-STING pathway in CNV formation, we evaluated CNV size and performed fundus fluorescein angiography. The expression levels of cGAS and STING were significantly upregulated in the RPE-choroid complex after CNV induction, and dsDNA merged with cGAS was observed in CNV lesions. Intravitreal administration of H-151 suppressed CNV development and fluorescent leakage from neovessels. In CNV lesions, the high expression of STING and cGAS was observed in infiltrating F4/80+ macrophages. H-151 administration attenuated downstream signals of the cGAS-STING pathway, including the phosphorylation of nuclear factor-κB, and downregulated the expression of interleukin 1β. These findings support that the inhibition of cGAS-STING pathway treats abnormal ocular angiogenesis.

PiSTING: A Pocket-Independent Agonist Based on Multivalency-Driven STING Oligomerization.

The stimulator of interferon genes (STING) pathway is a potent therapeutic target for innate immunity. Despite the efforts to develop pocket-dependent small-molecule STING agonists that mimic the endogenous STING ligand, cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), most of these agonists showed disappointing results in clinical trials owing to the limitations of the STING pocket. In this study, we developed novel pocket-independent STING-activating agonists (piSTINGs), which act through multivalency-driven oligomerization to activate STING. Additionally, a piSTING-adjuvanted vaccine elicited a significant antibody response and inhibited tumour growth in therapeutic models. Moreover, a piSTING-based vaccine combination with aPD-1 showed remarkable potential to enhance the effectiveness of immune checkpoint blockade (ICB) immunotherapy. In particular, piSTING can strengthen the impact of STING pathway in immunotherapy and accelerate the clinical translation of STING agonists.

Robust anti-tumor immunity through the integration of targeted lipid nanoparticle-based mRNA nanovaccines with PD-1/PD-L1 blockade

Tumor mRNA vaccines present a personalized approach in cancer immunotherapy, encoding distinct tumor antigens to evoke robust immune responses and offering the potential against emerging tumor variants. Despite this, the clinical advancement of tumor mRNA vaccines has been hampered by their limited delivery capacity and inefficient activation of antigen-presenting cells (APCs). Herein, we employed microfluidics technology to engineer mannose-modified lipid-based nanovaccines for specifically targeting APCs. The encapsulation process efficiently entrapped the cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) agonist along with mRNA encoding antigens. The targeted nanovaccines (TNVs) exhibited a narrow particle size distribution, ensuring consistent and efficient delivery. These TNVs significantly enhanced gene expression of mRNA, facilitating antigen presentation and immune activation. When compared to non-targeted nanovaccines, TNVs outperformed in terms of antigen presentation and immune activation. Furthermore, the combination of anti-PD-L1 antibodies with TNVs elicited a synergistic anti-tumor effect. This was attributed to the anti-PD-L1 antibodies' ability to overcome the immune suppression of tumor cells. Our findings suggest that the combination treatment elicited the most robust anti-tumor immune activation and immune memory effect. These results indicate that integrating tumor mRNA vaccines with immune checkpoint inhibitors or other immunostimulatory agents may be crucial for enhancing the immune response.

Nervous necrosis virus capsid protein and Protein A dynamically modulate the fish cGAS-mediated IFN signal pathway to facilitate viral evasion.

Nervous necrosis virus (NNV), an aquatic RNA virus belonging to Betanodavirus, infects a variety of marine and freshwater fishes, leading to massive mortality of cultured larvae and juveniles and substantial economic losses. The enzyme cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) is widely recognized as a central component in the innate immune response to cytosolic DNA derived from different pathogens. However, little is known about the response of cGAS to aquatic RNA viruses. This study found that Epinephelus coioides cGAS (EccGAS) overexpression inhibited NNV replication, whereas EccGAS silencing promoted NNV replication. The anti-NNV activity of EccGAS was involved in interferon (IFN) signaling activation including tumor necrosis factor receptor-associated factor family member-associated NF-kappa-B activator-binding kinase 1 (TBK1) phosphorylation, interferon regulatory factor 3 (IRF3) nuclear translocation, and the subsequent induction of IFNc and ISGs. Interestingly, NNV employed its capsid protein (CP) or Protein A (ProA) to negatively or positively modulate EccGAS-mediated IFN signaling by simultaneously targeting EccGAS. CP interacted with EccGAS via the arm-P, S-P, and SD structural domains and promoted its polyubiquitination with K48 and K63 linkages in an EcUBE3C (the ubiquitin ligase)-dependent manner, ultimately leading to EccGAS degradation. Conversely, ProA bound to EccGAS and inhibited its ubiquitination and degradation. In regulating EccGAS protein content, CP's inhibitory action was more pronounced than ProA's protective effect, allowing successful NNV replication. These novel findings suggest that NNV CP and ProA dynamically modulate the EccGAS-mediated IFN signaling pathway to facilitate the immune escape of NNV. Our findings shed light on a novel mechanism of virus-host interaction and provide a theoretical basis for the prevention and control of NNV.IMPORTANCEAs a well-known DNA sensor, cGAS is a pivotal component in innate anti-viral immunity to anti-DNA viruses. Although there is growing evidence regarding the function of cGAS in the resistance to RNA viruses, the mechanisms by which cGAS participates in RNA virus-induced immune responses in fish and how aquatic viruses evade cGAS-mediated immune surveillance remain elusive. Here, we investigated the detailed mechanism by which EccGAS positively regulates the anti-NNV response. Furthermore, NNV CP and ProA interacted with EccGAS, regulating its protein levels through ubiquitin-proteasome pathways, to dynamically modulate the EccGAS-mediated IFN signaling pathway and facilitate viral evasion. Notably, NNV CP was identified to promote the ubiquitination of EccGAS via ubiquitin ligase EcUBE3C. These findings unveil a novel strategy for aquatic RNA viruses to evade cGAS-mediated innate immunity, enhancing our understanding of virus-host interactions.

DNA of neutrophil extracellular traps promote NF-κB-dependent autoimmunity via cGAS/TLR9 in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterised by persistent airway inflammation even after cigarette smoking cessation. Neutrophil extracellular traps (NETs) have been implicated in COPD severity and acute airway inflammation induced by short-term cigarette smoke (CS). However, whether and how NETs contribute to sustained airway inflammation in COPD remain unclear. This study aimed to elucidate the immunoregulatory mechanism of NETs in COPD, employing human neutrophils, airway epithelial cells (AECs), dendritic cells (DCs), and a long-term CS-induced COPD mouse model, alongside cyclic guanosine monophosphate-adenosine monophosphate synthase and toll-like receptor 9 knockout mice (cGAS-−/−, TLR9−/−); Additionally, bronchoalveolar lavage fluid (BALF) of COPD patients was examined. Neutrophils from COPD patients released greater cigarette smoke extract (CSE)-induced NETs (CSE-NETs) due to mitochondrial respiratory chain dysfunction. These CSE-NETs, containing oxidatively-damaged DNA (NETs-DNA), promoted AECs proliferation, nuclear factor kappa B (NF-κB) activation, NF-κB-dependent cytokines and type-I interferons production, and DC maturation, which were ameliorated/reversed by silencing/inhibition of cGAS/TLR9. In the COPD mouse model, blocking NETs-DNA-sensing via cGAS−/− and TLR9−/− mice, inhibiting NETosis using mitoTEMPO, and degrading NETs-DNA with DNase-I, respectively, reduced NETs infiltrations, airway inflammation, NF-κB activation and NF-κB-dependent cytokines, but not type-I interferons due to IFN-α/β receptor degradation. Elevated NETs components (myeloperoxidase and neutrophil elastase activity) in BALF of COPD smokers correlated with disease severity and NF-κB-dependent cytokine levels, but not type-I interferon levels. In conclusion, NETs-DNA promotes NF-κB-dependent autoimmunity via cGAS/TLR9 in long-term CS exposure-induced COPD. Therefore, targeting NETs-DNA and cGAS/TLR9 emerges as a potential strategy to alleviate persistent airway inflammation in COPD.

STING agonist-conjugated metal-organic framework induces artificial leukocytoid structures and immune hotspots for systemic antitumor responses.

Radiotherapy is widely used for cancer treatment, but its clinical utility is limited by radioresistance and its inability to target metastases. Nanoscale metal-organic frameworks (MOFs) have shown promise as high-Z nanoradiosensitizers to enhance radiotherapy and induce immunostimulatory regulation of the tumor microenvironment. We hypothesized that MOFs could deliver small-molecule therapeutics to synergize with radiotherapy for enhanced antitumor efficacy. Herein, we develop a robust nanoradiosensitizer, GA-MOF, by conjugating a STING agonist, 2',3'-cyclic guanosine monophosphate-adenosine monophosphate (GA), on MOFs for synergistic radiosensitization and STING activation. GA-MOF demonstrated strong anticancer efficacy by forming immune-cell-rich nodules (artificial leukocytoid structures) and transforming them into immunostimulatory hotspots with radiotherapy. Further combination with an immune checkpoint blockade suppressed distant tumors through systemic immune activation. Our work not only demonstrates the potent radiosensitization of GA-MOF, but also provides detailed mechanisms regarding MOF distribution, immune regulatory pathways and long-term immune effects.

Cyclic guanosine monophosphate-adenosine monophosphate synthetase/stimulator of interferon genes signaling aggravated corneal allograft rejection through neutrophil extracellular traps

The activation of innate immunity following transplantation has been identified as a crucial factor in allograft inflammation and rejection. However, the role of cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)/stimulator of interferon genes (STING) signaling-mediated innate immunity in the pathogenesis of allograft rejection remains unclear. Utilizing a well-established murine model of corneal transplantation, we demonstrated increased expression of cGAS and STING in rejected-corneal allografts compared with syngeneic (Syn) and normal (Nor) corneas, along with significant activation of the cGAS/STING pathway, as evidenced by the enhanced phosphorylation of TANK-binding kinase 1and interferon regulatory factor 3. Pharmacological and genetic inhibition of cGAS/STING signaling markedly delayed corneal transplantation rejection, resulting in prolonged survival time and reduced inflammatory infiltration. Furthermore, we observed an increase in the formation of neutrophil extracellular traps (NETs) in rejected allografts, and the inhibition of NET formation through targeting peptidylarginine deiminase 4 and DNase I treatment significantly alleviated immune rejection and reduced cGAS/STING signaling activity. Conversely, subconjunctival injection of NETs accelerated corneal transplantation rejection and enhanced the activation of the cGAS/STING pathway. Collectively, these findings demonstrate that NETs contribute to the exacerbation of allograft rejection via cGAS/STING signaling, highlighting the targeting of the NETs/cGAS/STING signaling pathway as a potential strategy for prolonging allograft survival.

Synthetic cationic helical polypeptides for the stimulation of antitumour innate immune pathways in antigen-presenting cells.

Intracellular DNA sensors regulate innate immunity and can provide a bridge to adaptive immunogenicity. However, the activation of the sensors in antigen-presenting cells (APCs) by natural agonists such as double-stranded DNAs or cyclic nucleotides is impeded by poor intracellular delivery, serum stability, enzymatic degradation and rapid systemic clearance. Here we show that the hydrophobicity, electrostatic charge and secondary conformation of helical polypeptides can be optimized to stimulate innate immune pathways via endoplasmic reticulum stress in APCs. One of the three polypeptides that we engineered activated two major intracellular DNA-sensing pathways (cGAS-STING (for cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes) and Toll-like receptor 9) preferentially in APCs by promoting the release of mitochondrial DNA, which led to the efficient priming of effector T cells. In syngeneic mouse models of locally advanced and metastatic breast cancers, the polypeptides led to potent DNA-sensor-mediated antitumour responses when intravenously given as monotherapy or with immune checkpoint inhibitors. The activation of multiple innate immune pathways via engineered cationic polypeptides may offer therapeutic advantages in the generation of antitumour immune responses.

Role and Mechanism of cGAS-STING Pathway in Cardiovascular System.

The cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway is a part of the innate immune system that plays a role in the cardiovascular system. It acts as a surveillance system, detecting and responding to cytosolic DNA, viral DNA, and other intracellular DNA species. Activation of the cGAS-STING pathway leads to the production of inflammatory cytokines and type I interferons, which are involved in the immune response. In the cardiovascular system, the cGAS-STING pathway has been implicated in various physiological and pathological processes. It contributes to vascular inflammation, atherosclerosis, endothelial dysfunction and cardiac remodeling and heart failure. In this review, we will elaborate on the research progress of the role of cGAS-STING in cardiovascular system.