Salvia miltiorrhiza bge. f. alba ameliorates type 2 diabetes mellitus-associated non-alcoholic fatty liver disease via the STING pathway.

OBJECTIVE: To elucidate the functional role and underlying mechanism of Salvia miltiorrhiza bge. f. alba (SMBFA) in patients with type 2 diabetes mellitus (T2DM) accompanied by non-alcoholic fatty liver disease (NAFLD). METHODS: A retrospective analysis was conducted on 90 patients with T2DM-NAFLD who met the inclusion criteria. The control group was comprised of 45 patients treated with Fenofibrate, while the observation group consisted of 45 patients who received SMBFA in addition to the control treatment. An in vivo mouse model of T2DM-NAFLD was established using a high-fat diet combined with streptozotocin. Serum levels of fasting plasma glucose (FPG), 2-hour postprandial glucose (2h PG), hemoglobin A1c (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol (TC), and triglyceride (TG) were measured in both patients and mice using an automated biochemical analyzer. Liver indices and function were also evaluated. ELISA assays were performed to quantify inflammatory cytokine levels. Western blotting was utilized to assess the protein levels related to the stimulator of interferon genes (STING)-interferon regulatory factor 3 (IRF3) pathway. RESULTS: After treatment, significant reductions in blood glucose indices, HOMA-IR, lipid metabolism markers, liver function indices, and inflammatory cytokines were observed in both groups of T2DM-NAFLD patients. Notably, the decreases were more pronounced in the observation group compared to the control group. Similarly, in T2DM-NAFLD mouse models, the levels of these parameters were significantly lower in the observation group than in the normal control (NC) group. Additionally, SMBFA suppressed the elevated levels of STING, p-IRF3, and p-TANK-binding kinase 1 in the T2DM-NAFLD mice. CONCLUSION: SMBFA exhibits the potential to regulate glucose and lipid metabolism, inhibit insulin resistance, and protect liver function by modulating the STING signaling pathway.

High levels of tumor cell-intrinsic STING signaling are associated with increased infiltration of CD8+ T cells in dMMR/MSI-H gastric cancer.

Mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) gastric cancer (GC) exhibits an immune-active tumor microenvironment (TME) compared to MMR proficient (pMMR)/microsatellite stable/Epstein-Barr virus-negative [EBV (-)] GC. The tumor cell-intrinsic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been considered a key regulator of immune cell activation in the TME. However, its significance in regulating the immune-active TME in dMMR/MSI-H GC remains unclear. Here, we demonstrated that tumor cell-intrinsic cGAS-STING was highly expressed in dMMR GC compared to pMMR/EBV (-) GC. The expression of tumor cell-intrinsic STING was significantly and positively associated with the number of CD8+ tumor-infiltrating lymphocytes in GC. Analysis of TCGA datasets revealed that the expression of interferon-stimulated genes and STING downstream T-cell attracting chemokines was significantly higher in MSI-H GC compared to other subtypes of GC with EBV (-). These results suggest that tumor cell-intrinsic STING signaling plays a key role in activating immune cells in the dMMR/MSI-H GC TME and might serve as a novel biomarker predicting the efficacy of immunotherapy for GC treatment.

MnO2@CeOx-GAMP radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities for radiosensitization-mediated STING pathway activation.

Activation of the stimulator of interferon genes (STING) pathway by radiotherapy (RT) has a significant effect on eliciting antitumor immune responses. The generation of hydroxyl radical (·OH) storm and the sensitization of STING-relative catalytic reactions could improve radiosensitization-mediated STING activation. Herein, multi-functional radiosensitizer with oxygen vacancies depended mimicking enzyme-like activities was fabricated to produce more dsDNA which benefits intracellular 2', 3'-cyclic GMP-AMP (cGAMP) generation, together with introducing exogenous cGAMP to activate immune response. MnO2@CeOx nanozymes present enhanced superoxide dismutase (SOD)-like and peroxidase (POD)-like activities due to induced oxygen vacancies accelerate the redox cycles from Ce4+ to Ce3+ via intermetallic charge transfer. CeOx shells not only serve as radiosensitizer, but also provide the conjugation site for AMP/GMP to form MnO2@CeOx-GAMP (MCG). Upon X-ray irradiation, MCG with SOD-like activity facilitates the conversion of superoxide anions generated by Ce-sensitization into H2O2 within tumor microenvironment (TME). The downstream POD-like activity catalyzes the elevated H2O2 into a profusion of ·OH for producing more damage DNA fragments. TME-responsive decomposed MCG could supply exogenous cGAMP, meanwhile the releasing Mn2+ improve the sensitivity of cyclic GMP-AMP synthase to dsDNA for producing more cGAMP, resulting in the promotion of STING pathway activation.

STING regulates aging-related osteoporosis by mediating the Hk2-Vdac1 mitochondrial axis.

Metabolic abnormalities and mild inflammation are hallmarks of aging and major driving factors for aging-related damage and bone metabolic diseases. Mitochondria are crucial links in energy metabolism and immune homeostasis regulation. Mitochondrial dysfunction is considered one of the pathogenic factors of aging-related osteoporosis, but its mechanism of action needs further research. Here, we demonstrated that the interaction between stimulator of interferon genes (STING)-mediated regulation of hexokinase 2 (Hk2)-voltage-dependent anion channel-1 (Vdac1) is a critical factor contributing to mitochondrial dysfunction and osteogenic abnormalities during aging. As the aging process progresses, factors related to aging cause an increase in STING expression, which disrupts the interaction between Hk2 and Vdac1. Dissociation of Hk2 from Vadc1 triggered the opening of the mitochondrial inner mitochondrial permeability transition pore (mPTP), leading to mitochondrial dysfunction and abnormal osteogenic differentiation, thereby disrupting bone homeostasis. In brief, this study demonstrates that STING acts as an intracellular metabolic Checkpoint, influencing mitochondrial function to promote the development of osteoporosis. These findings significantly enhance the development of STING-targeted treatments for aging-related osteoporosis.

Development of STING probes and visualization of STING in multiple tumor types.

PURPOSE: The stimulator of interferon genes (STING) is a critical component of the innate immune system and plays a pivotal role in tumor immunotherapy. Developing non-invasive in vivo diagnostic methods for visualizing STING is highly valuable for STING-related immunotherapy. This work aimed to build a noninvasive imaging platform that can dynamically and quantitatively monitor tumor STING expression. METHODS: We investigated the in vivo positron emission tomography (PET) imaging of STING-expressing tumors (B16F10, MC38, and Panc02) with STING-targeted radioprobe ([18F]F-CRI1). The expression of STING in tumors was quantified, and correlation analysis was performed between these results and the outcomes of PET imaging. Furthermore, we optimized the structure of [18F]F-CRIn with polyethylene glycol (PEG) to improve the pharmacokinetic characteristics in vivo. A comprehensive comparison of the imaging and biodistribution results obtained with the optimized probes was conducted in the B16F10 tumors. RESULTS: The PET imaging results showed that the uptake of [18F]F-CRI1 in tumors was positively correlated with the expression of STING in tumors (r = 0.9184, P < 0.001 at 0.5 h). The lipophilicity of the optimized probes was significantly reduced. As a result of employing optimized probes, B16F10 tumor-bearing mice exhibited significantly improved tumor visualization in PET imaging, along with a marked reduction in retention within non-target areas such as the gallbladder and intestines. Biodistribution experiments further validated the efficacy of probe optimization in reducing uptake in non-target areas. CONCLUSION: In summary, this work demonstrated a promising pathway for the development of STING-targeted radioprobes, advancing in vivo PET imaging capabilities.

Overcome the challenge for intratumoral injection of STING agonist for pancreatic cancer by systemic administration.

Due to the challenge for intratumoral administration, innate agonists have not made it beyond preclinical studies for efficacy testing in most tumor types. Pancreatic ductal adenocarcinoma (PDAC) has a hostile tumor microenvironment that renders T cells dysfunctional. Innate agonist treatments may serve as a T cell priming mechanism to sensitize PDACs to anti-PD-1 antibody (a-PD-1) treatment. Using a transplant mouse model with spontaneously formed liver metastasis, a genetically engineered KPC mouse model that spontaneously develops PDAC, and a human patient-derived xenograft model, we compared the antitumor efficacy between intrahepatic/intratumoral and intramuscular systemic administration of BMS-986301, a next-generation STING agonist. Flow cytometry, Nanostring, and cytokine assays were used to evaluate local and systemic immune responses. This study demonstrated that administration of STING agonist systemically via intramuscular injection is equivalent to its intratumoral injection in inducing both effector T cell response and antitumor efficacy. Compared to intratumoral administration, T cell exhaustion and immunosuppressive signals induced by systemic administration were attenuated. Nonetheless, either intratumoral or systemic treatment of STING agonist was associated with increased expression of CTLA-4 on tumor-infiltrating T cells. However, the combination of a-PD-1 and anti-CTLA-4 antibody with systemic STING agonist demonstrated the antitumor efficacy in the KPC mouse spontaneous PDAC model. The mouse pancreatic and liver orthotopic model of human patient-derived xenograft reconstituted with PBMC also showed that antitumor and abscopal effects of both intratumoral and intramuscular STING agonist are equivalent. Taken together, this study supports the clinical development of innate agonists via systemic administration for treating PDAC.

ß-Mangostin targets and suppresses glioma via STING activation and tumor-associated microglia polarization.

Glioma, a common and highly malignant central nervous system tumor, markedly influences patient prognosis via interactions with glioma-associated macrophages. Previous research has revealed the anticancer potential of ß-mangostin, a xanthone derivative obtained from the mangosteen fruit. This research investigated the role of ß-mangostin on microglia in the glioma microenvironment and evaluated the efficacy of ß-mangostin combined with anti-PD-1 antibody (αPD-1) in glioma-bearing mice. The results showed that, ß-mangostin attenuated M2 polarization in BV2 cells and promoted M1-related interleukin (IL)-1ß and IL-6 secretion, thereby inhibiting glioma invasion. In addition, ß-mangostin improved the anti-glioma effects of αPD-1 and increased CD8+T cell and M1-type microglia infiltration. Mechanistically, ß-mangostin bound to the stimulator of interferon genes (STING) protein, which is crucial for the anti-tumor innate immune response, and promoted STING phosphorylation in microglia, both in vivo and in vitro. These results provide insights into its mode of action and supporting further investigation into ß-mangostin as a therapeutic agent.

Fangchinoline induces antiviral response by suppressing STING degradation.

The stimulator of interferon genes (STING), an integral adaptor protein in the DNA-sensing pathway, plays a pivotal role in the innate immune response against infections. Additionally, it presents a valuable therapeutic target for infectious diseases and cancer. We observed that fangchinoline (Fan), a bis-benzylisoquinoline alkaloid (BBA), effectively impedes the replication of vesicular stomatitis virus (VSV), encephalomyocarditis virus (EMCV), influenza A virus (H1N1), and herpes simplex virus-1 (HSV-1) in vitro. Fan treatment significantly reduced the viral load, attenuated tissue inflammation, and improved survival in a viral sepsis mouse model. Mechanistically, Fan activates the antiviral response in a STING-dependent manner, leading to increased expression of interferon (IFN) and interferon-stimulated genes (ISGs) for potent antiviral effects in vivo and in vitro. Notably, Fan interacts with STING, preventing its degradation and thereby extending the activation of IFN-based antiviral responses. Collectively, our findings highlight the potential of Fan, which elicits antiviral immunity by suppressing STING degradation, as a promising candidate for antiviral therapy.

Electroacupuncture alleviates motor dysfunction by regulating neuromuscular junction disruption and neuronal degeneration in SOD1G93A mice.

Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease characterized by the progressive destruction of the neuromuscular junction (NMJ) and the degeneration of motor neurons, eventually leading to atrophy and paralysis of voluntary muscles responsible for motion and breathing. NMJs, synaptic connections between motor neurons and skeletal muscle fibers, are extremely fragile in ALS. To determine the effects of early electroacupuncture (EA) intervention on nerve reinnervation and regeneration following injury, a model of sciatic nerve injury (SNI) was first established using SOD1G93A mice, and early electroacupuncture (EA) intervention was conducted at Baihui (DU20), and bilateral Zusanli (ST36). The results revealed that EA increased the Sciatic nerve Functional Index, the structural integrity of the gastrocnemius muscles, and the cross-sectional area of muscle fibers, as well as up-regulated the expression of acetylcholinesterase and facilitated the co-location of α7 nicotinic acetate choline receptors and α-actinin. Overall, these results suggested that EA can promote the repair and regeneration of injured nerves and delay NMJ degeneration in SOD1G93A-SNI mice. Moreover, analysis of the cerebral cortex demonstrated that EA alleviated cortical motor neuron damage in SOD1G93A mice, potentially attributed to the inhibition of the cyclic GMP-AMP synthase-stimulator of interferon genes pathway and the release of interferon-ß suppressing the activation of natural killer cells and the secretion of interferon-γ, thereby further inhibiting microglial activation and the expression of inflammatory factors. In summary, EA delayed the degeneration of NMJ and mitigated the loss of cortical motor neurons, thus delaying disease onset, accompanied by alleviation of muscle atrophy and improvements in motor function in SOD1G93A mice.

Tumor phagocytosis-driven STING activation invigorates antitumor immunity and reprograms the tumor micro-environment.

Immunogenic cell death (ICD) holds the potential for in situ tumor vaccination while concurrently eradicating tumors and stimulating adaptive immunity. Most ICD inducers, however, elicit insufficient immune responses due to negative feedback against ICD biomarkers, limited infiltration of antitumoral immune cells, and the immunosuppressive tumor micro-environment (TME). Recent findings highlight the pivotal roles of stimulators of interferon gene (STING) activation, particularly in stimulating antigen-presenting cells (APCs) and TME reprogramming, addressing ICD limitations. Herein, we introduced 'tumor phagocytosis-driven STING activation', which involves the activation of STING in APCs during the recognition of ICD-induced cancer cells. We developed a polypeptide-based nanocarrier encapsulating both doxorubicin (DOX) and diABZI STING agonist 3 (dSA3) to facilitate this hypothesis in vitro and in vivo. After systemic administration, nanoparticles predominantly accumulated in tumor tissue and significantly enhanced anticancer efficacy by activating tumor phagocytosis-driven STING activation in MC38 and TC1 tumor models. Immunological activation of APCs occurred within 12 h, subsequently leading to the activation of T cells within 7 days, observed in both the TME and spleen. Furthermore, surface modification of nanoparticles with cyclic RGD (cRGD) moieties, which actively target integrin αvß3, enhances tumor accumulation and eradication, thereby verifying the establishment of systemic immune memory. Collectively, this study proposes the concept of tumor phagocytosis-driven STING activation and its effectiveness in generating short-term and long-term immune responses.

An updated patent review of stimulator of interferon genes agonists (2021 - present).

INTRODUCTION: Stimulator of Interferon Genes (STING) is an innate immune sensor. Activation of STING triggers a downstream response that results in the expression of proinflammatory cytokines (TNF-α, IL-1ß) via nuclear factor kappa-B (NF-κB) or the expression of type I interferons (IFNs) via an interferon regulatory factor 3 (IRF3). IFNs can eventually result in promotion of the adaptive immune response including activation of tumor-specific CD8+ T cells to abolish the tumor. Consequently, activation of STING has been considered as a potential strategy for cancer treatment. AREAS COVERED: This article provides an overview on structures and pharmacological data of CDN-like and non-nucleotide STING agonists acting as anticancer agents (January 2021 to October 2023) from a medicinal chemistry perspective. The data in this review come from EPO, WIPO, RCSB PDB, CDDI. EXPERT OPINION: In recent years, several structurally diverse STING agonists have been identified. As an immune enhancer, they are used in the treatment of tumors, which has received extensive attention from scientific community and pharmaceutical companies. Despite the multiple challenges that have appeared, STING agonists may offer opportunities for immunotherapy.

[Correlation Analysis between STING Promoter Polymorphism and Susceptibility to Infection after Chemotherapy for Multiple Myeloma].

OBJECTIVE: To investigate the correlation between the stimulator of interferon genes (STING ) promoter polymorphism and the susceptibility to infection after chemotherapy for multiple myeloma. METHODS: A total of 102 patients who had undergone chemotherapy for multiple myeloma in our hospital from January 2016 to July 2022 were selected. Depending on the presence or absence of infection after chemotherapy, the enrolled patients were divided into infection group (53 cases) and non-infection group (49 cases). The infection sites and distribution characteristics of pathogenic bacteria of the infection group were analyzed. The genotype distribution of STING gene promoter rs587777609 was compared between the two groups, and the risk factors of infection after chemotherapy for multiple myeloma were analyzed. RESULTS: For infection site, digestive system, respiratory system, urinary system, skin and mucous membranes accounted for 43.40%, 26.42%, 20.75%, and 9.43%, respectively. For pathogenic bacteria, Gram-negative bacteria, Gram-positive bacteria and fungi accounted for 57.14%, 26.98%, and 15.87%, respectively. The CC genotype frequency of STING gene rs587777609 locus in the infection group was lower than that in the non-infection group, while the TT genotype frequency was higher than that in the non-infection group (P < 0.05). The proportions of patients with diabetes, chronic obstructive pulmonary disease, renal insufficiency, serum albumin level< 35 g/L, ISS stage III, mechanical ventilation, and indwelling catheter in the infection group were higher than those in the non-infection group (P < 0.05). Multivariate logistic regression analysis showed that diabetes (OR =1.992), serum albumin level< 35 g/L (OR =2.782), ISS stage III (OR =2.707), mechanical ventilation (OR =3.031), and TT genotype (OR =2.401) were risk factors of infection after chemotherapy for multiple myeloma (P < 0.05). CONCLUSION: There is a correlation between STING promoter polymorphism and the susceptibility to infection after chemotherapy for multiple myeloma, and patients with TT genotype have a higher risk of infection.

Lipo/TK-CDN/TPP/Y6 nanoparticles inhibit cutaneous melanoma formation.

Stimulation of the innate immune stimulator of interferon genes (STING) pathway has been shown to boost anti-tumour immunity. Nevertheless, the systemic delivery of STING agonists to the tumour presents challenges. Therefore, we designed a cyclic dinucleotide (CDN)-based drug delivery system (DDS) combined photothermal therapy (PTT)/photodynamic therapy (PDT)/immunotherapy for cutaneous melanoma. We coencapsulated a reactive oxygen species (ROS)-responsive prodrug thioketone-linked CDN (TK-CDN), and photoresponsive agents chlorin E6 (Y6) within mitochondria-targeting reagent triphenylphosphonium (TPP)-modified liposomes (Lipo/TK-CDN/TPP/Y6). Lipo/TK-CDN/TPP/Y6 exhibited a photothermal effect similar to Y6, along with a superior cellular uptake rate. Upon endocytosis by B16F10 cells, Lipo/TK-CDN/TPP/Y6 generated large amounts of ROS under laser irradiation for PDT. Mice bearing B16F10 tumours were intravenously injected with Lipo/TK-CDN/TPP/Y6 and exposed to irradiation, resulting in a substantial inhibition of tumour growth. Exploration of the mechanism of anti-tumour action showed that Lipo/TK-CDN/TPP/Y6 had a stronger stimulation of STING activation and anti-tumour immune cell infiltration compared to other groups. Hence, the Lipo/TK-CDN/TPP/Y6 nanoparticles offer great potential as a DDS for targeted and on-demand drug release at tumour sites. These nanoparticles exhibit promise as a candidate for precise and controllable combination therapy in the treatment of tumours.

Development of nitroalkene-based inhibitors to target STING-dependent inflammation.

Stimulator of Interferon Genes (STING) is essential for the inflammatory response to cytosolic DNA. Despite that aberrant activation of STING is linked to an increasing number of inflammatory diseases, the development of inhibitors has been challenging, with no compounds in the pipeline beyond the preclinical stage. We previously identified endogenous nitrated fatty acids as novel reversible STING inhibitors. With the aim of improving the specificity and efficacy of these compounds, we developed and tested a library of nitroalkene-based compounds for in vitro and in vivo STING inhibition. The structure-activity relationship study revealed a robustly improved electrophilicity and reduced degrees of freedom of nitroalkenes by conjugation with an aromatic moiety. The lead compounds CP-36 and CP-45, featuring a ß-nitrostyrene moiety, potently inhibited STING activity in vitro and relieved STING-dependent inflammation in vivo. This validates the potential for nitroalkene compounds as drug candidates for STING modulation to treat STING-driven inflammatory diseases, providing new robust leads for preclinical development.

Gasdermin E benefits CD8+T cell mediated anti-immunity through mitochondrial damage to activate cGAS-STING-interferonß axis in colorectal cancer.

BACKGROUND: Pyroptosis belongs to a unique type of programmed cell death among which GSDME is reported to exert anti-tumor immunity. However, the underlying mechanisms of how to boost tumor-infiltrating lymphocytes and whether it could benefit the efficacy of ICIs are still unknown. METHODS: CRC samples were used to analyze its relationship with CD8+T cells. GSDME in mouse CRC cell lines CT26/MC38 was overexpressed. The infiltration of CD8+T cells in grafted tumors was determined by multiplex flow cytometric analysis and immunohistochemistry. Transcriptomic analysis was performed in cell lines to define key signatures related to its overexpression. The mechanism of how mtDNA was released by GSDME-induced mitochondrial damage and activated cGAS-STING pathway was observed. Whether GSDME benefited ICIs and the relationships with the genotypes of CRC patients were investigated. RESULTS: It had favorable prognostic value in CRC and was positively associated with increased number and functionality of CD8+T cells both in human samples and animal models. This was due to mitochondrial damage and activation of cGAS-STING-IFNß pathway for the recruitment of CD8+T cells. Mechanically, GSDME overexpression enhanced N-GSDME level, leading to the mitochondrial damage and mtDNA was released into cytosol. Finally, GSDME benefited with ICIs and exhibited positive relationships with MSI in CRC patients. CONCLUSION: We presented the mechanism of GSDME in anti-tumor immunity through activating cGAS-STING-IFNß axis mediated by mitochondrial damage, leading to more infiltration of CD8+T cells with synergistic efficacy with ICIs.

Combination of MHI148 Targeted Photodynamic Therapy and STING Activation Inhibits Tumor Metastasis and Recurrence.

Metastasis and recurrence are notable contributors to mortality associated with breast cancer. Although immunotherapy has shown promise in mitigating these risks after conventional treatments, its effectiveness remains constrained by significant challenges, such as impaired antigen presentation by dendritic cells (DCs) and inadequate T cell infiltration into tumor tissues. To address these limitations, we developed a multifunctional nanoparticle platform, termed GM@P, which consisted of a hydrophobic shell encapsulating the photosensitizer MHI148 and a hydrophilic core containing the STING agonist 2'3'-cGAMP. This design elicited robust type I interferon responses to activate antitumor immunity. The GM@P nanoparticles loaded with MHI148 specifically targeted breast cancer cells. Upon exposure to 808 nm laser irradiation, the MHI148-loaded nanoparticles produced toxic reactive oxygen species (ROS) to eradicate tumor cells through photodynamic therapy (PDT). Notably, PDT stimulated immunogenic cell death (ICD) to foster the potency of antitumor immune responses. Furthermore, the superior photoacoustic imaging (PAI) capabilities of MHI148 enabled the simultaneous visualization of diagnostic and therapeutic procedures. Collectively, our findings uncovered that the combination of PDT and STING activation facilitated a more conducive immune microenvironment, characterized by enhanced DC maturation, infiltration of CD8+ T cells, and proinflammatory cytokine release. This strategy stimulated local immune responses to augment systemic antitumor effects, offering a promising approach to suppress tumor growth, inhibit metastasis, and prevent recurrence.

Porphyromonas gingivalis OMVs promoting endothelial dysfunction via the STING pathway in periodontitis.

OBJECTIVE: This study aimed to assess the effects of Porphyromonas gingivalis outer membrane vesicles (Pg-OMVs) in chronic periodontitis and explore the underlying mechanism involved. METHODS: In vitro, Pg-OMVs were incubated with Ea.hy926 (vessel endothelial cells, ECs) to evaluate their effects on endothelial functions and to investigate the underlying mechanism. The effects of endothelial dysfunction on MG63 osteoblast-like cells were verified using an indirect co-culture method. For in vivo studies, micro-CT was conducted to identify alveolar bone mass. Immunofluorescence staining was conducted to confirm the levels of stimulator of interferon genes (STING) in the blood vessel and the number of Runx2+ cells around the alveolar bone. RESULTS: Pg-OMVs were endocytosed by ECs, leading to endothelial dysfunction. The cGAS-STING-TBK1 pathway was activated in ECs, which subsequently inhibited MG63 migration and early osteogenesis differentiation. In vivo, Pg-OMVs promoted alveolar bone resorption, increased STING levels in the blood vessel, and decreased Runx2+ cells around the alveolar bone. CONCLUSIONS: Pg-OMVs caused endothelial dysfunction and activated the cGAS-STING-TBK1 signal cascade in ECs, thereby impairing ECs-mediated osteogenesis. Furthermore, Pg-OMVs aggregated alveolar bone loss and altered the blood vessel-mediated osteogenesis with elevated STING.

Tumor vascular disrupting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA): Suppresses macrophage capping protein beyond STING activation.

The vascular disrupting agent (VDA) 5,6-dimethylxanthenone-4-acetic acid (DMXAA) induces apoptosis in vascular endothelial cells and leads to tumor hemorrhagic necrosis. While DMXAA has been proven to be a potent agonist of murine stimulator of interferon genes (mSTING), it has little effect on human-STING (hSTING). This species selectivity of DMXAA may explain its effectiveness against solid tumors in mice and its failure in clinical trials. However, DMXAA did reduce tumor volume in some patients during clinical trials. These paradoxical results have prompted us to investigate the anti-tumor mechanism of DMXAA beyond STING in the destruction of tumor vasculature in humans. In this study, we demonstrated that DMXAA binds to both human and mouse macrophage capping protein (CapG), with a KD of 5.839 µM for hCapG and a KD of 2.867 µM for mCapG, as determined by surface plasmon resonance (SPR) analysis. Homology modeling and molecular docking analysis of hCapG indicated that the critical residues involved in the hydrogen bond interaction of DMXAA with hCapG were Arg153, Thr151, and GLN141, Asn234. In addition, electrostatic pi-cation interaction occurred between DMXAA and hCapG. Further functional studies revealed that CapG protein plays a crucial role in the effects of DMXAA on human umbilical endothelial vein cell (HUEVC) angiogenesis and migration, as well as the expression of cytoskeletal proteins actin and tubulin, and the invasion of A549 lung adenocarcinoma cells. Our study has originally uncovered a novel cross-species pathway underlying the antitumor vascular disruption of DMXAA extends beyond STING activation. This finding deepens our understanding of the multifaceted actions of flavonoid VDAs in animal models and in clinical settings, and may provide insights for the precise therapy of DMXAA based on the biomarker CapG protein.

STING-Targeted PET Imaging for Specific Detection and Therapeutic Monitoring of Myocarditis.

Imaging strategies for the specific detection and therapeutic monitoring of myocarditis are still lacking. Stimulator of interferon genes (STING) is a signal transduction molecule involved in an innate immune response. Here, we evaluated the feasibility of the recently developed STING-targeted radiotracer [18F]FBTA for positron emission tomography (PET) imaging to detect myocardial inflammation and monitor treatment in myocarditis mice. [18F]FBTA-PET imaging was performed in myocarditis mice and normal mice to verify the specificity of [18F]FBTA for the diagnosis of myocarditis. We also performed PET imaging in mice with myocarditis treated to verify the ability of [18F]FBTA in therapeutic monitoring. The expression of STING and inflammatory cell types was confirmed by flow cytometry and immunohistochemistry. [18F]FDG-PET imaging of myocarditis was used as a contrast. [18F]FBTA-PET imaging showed that the average radioactive uptake was significantly higher in the hearts of the myocarditis group than in the control group. STING was highly overexpressed in cardiac inflammatory cells, including macrophages, dendritic cells (DCs), and T cells. However, there was no significant difference in cardiac radiotracer uptake of [18F]FDG between the myocarditis group and the control group. Moreover, cardiac uptake of [18F]FBTA was significantly reduced in cyclosporin A-treated myocarditis mice and myocardial STING expression was also significantly reduced after the treatment. Overall, we showed that a STING-targeted PET tracer [18F]FBTA can be used to monitor changes in the inflammatory microenvironment in myocarditis. Besides, [18F]FBTA-PET is also suitable for real-time monitoring of myocarditis treatment, representing a promising diagnostic and therapeutic monitoring approach for myocarditis.