cGAS-STING Signaling Research Articles

Tandem-Controlled Dynamic DNA Assembly Enables Temporally-Selective Orthogonal Regulation of cGAS-STING Stimulation.

Despite advances in the controlled reconfiguration of DNA structures for biological applications, the dearth of strategies that allow for orthogonal regulation of immune pathways remains a challenge. Here, we report for the first time an endogenous and exogenous tandem-regulated DNA assembly strategy that enables orthogonally controlled stimulation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway. A DNA motif containing two palindromic sequences is engineered with an abasic site (AP)-connected blocking sequence to inhibit its self-assembly function, while apurinic/apyrimidinic endonuclease 1 (APE1)-triggered enzymatic cleavage of the AP site enables the reconfiguration and self-assembly of DNA motif into long double-stranded structures, thus realizing allosteric activation of the catalytic activity of cGAS to produce 2'3'-cyclic-GMP-AMP for STING stimulation. Importantly, we demonstrate that APE1-regulated DNA assembly allows for cell-selective activation of cGAS-STING signaling. Furthermore, by re-engineering the DNA motif with a photocleavable group, enzyme-triggered DNA assembly allows the cGAS-STING stimulation to operate (switched "ON''), whereas light-mediated fragmentation of the double-stranded DNA enables termination of such stimulation (switched "OFF"), thereby achieving orthogonal control over immune regulation. This work highlights an endogenous and exogenous tandem regulated strategy to modulate the cGAS-STING pathway in an orthogonally controlled manner.

Decursin protects against DSS-induced experimental colitis in mice by inhibiting the cGAS-STING signaling pathway.

While studies have shown that Angelica gigas Nakai (A. gigas) can alleviate ulcerative colitis in mice, the therapeutic role of its main active ingredient, decursin, is uncertain. Therefore, we aimed to investigate the protective effect and mechanism of decursin against inflammatory bowel disease (IBD) in vivo using mice. IBD was simulated via induction with 3% dextran sodium sulfate (DSS), with or without daily treatment with decursin (10 mg/kg or 20 mg/kg) or 5-amino salicylic acid (5-ASA; 100 mg/kg) for 14 days. Mice were weighed and monitored daily for disease activity index (DAI) scoring. Colon tissues were collected for histopathological staining analysis, and serum was collected for ELISA measurement of proinflammatory cytokines. Western blotting was employed to analyze colonic expression levels of the tight junction-related proteins ZO-1, Occludin, and Claudin 1, as well as cGAS-STING signaling pathway-associated proteins. The expression levels of major proteins were verified using immunohistochemistry and immunofluorescence. Compared with the control group, DSS-induced mice showed decreased body weight, increased DAI scores, shortening of the colon, disrupted colon tissue structure, increased serum levels of proinflammatory cytokines, increased expression of factors involved in activating the cGAS-STING signaling pathway, and reduced expression of ZO-1, Occludin, and Claudin 1. Under decursin treatment, the pathological state of IBD was less severe, proinflammatory factors were downregulated, and activation of the cGAS-STING signaling pathway was inhibited. Our findings indicate that decursin helps restore the intestinal mucosal barrier and prevents activation of the cGAS-STING signaling cascade, alleviating experimental IBD in mice.

The cGAS-STING pathway in HIV-1 and Mycobacterium tuberculosis coinfection.

Mycobacterium tuberculosis (M. tuberculosis) infection is the most common opportunistic infection in human immunodeficiency virus-1 (HIV-1)-infected individuals, and the mutual reinforcement of these two pathogens may accelerate disease progression and lead to rapid mortality. Therefore, HIV-1/M. tuberculosis coinfection is one of the major global public health concerns. HIV-1 infection is the greatest risk factor for M. tuberculosis infection and increases the likelihood of endogenous relapse and exogenous reinfection with M. tuberculosis. Moreover, M. tuberculosis further increases HIV-1 replication and the occurrence of chronic immune activation, accelerating the progression of HIV-1 disease. Exploring the pathogenesis of HIV-1/M. tuberculosis coinfections is essential for the development of novel treatments to reduce the global burden of tuberculosis. Innate immunity, which is the first line of host immune defense, plays a critical role in resisting HIV-1 and M. tuberculosis infections. The role of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway, which is a major DNA-sensing innate immune signaling pathway, in HIV-1 infection and M. tuberculosis infection has been intensively studied. This paper reviews the role of the cGAS-STING signaling pathway in HIV-1 infection and M. tuberculosis infection and discusses the possible role of this pathway in HIV-1/M. tuberculosis coinfection to provide new insight into the pathogenesis of HIV-1/M. tuberculosis coinfection and the development of novel therapeutic strategies.

PINK1-mediated mitophagy attenuates pathological cardiac hypertrophy by suppressing the mtDNA release-activated cGAS-STING pathway.

Sterile inflammation is implicated in the development of heart failure (HF). Mitochondria plays important roles in triggering and maintaining inflammation. Mitophagy is important for regulation of mitochondrial quality and maintenance of cardiac function under pressure overload. The association of mitophagy with inflammation in HF is largely unclear. As PINK1 is a central mediator of mitophagy, our objective was to investigate its involvement in cardiac hypertrophy, and the effect of PINK1-mediated mitophagy on cGAS-STING activation during cardiac hypertrophy. PINK1 knockout and cardiac-specific PINK1-overexpressing transgenic mice were created and subsequently subjected to transverse aortic constriction (TAC) surgery. In order to explore whether PINK1 regulates STING-mediated inflammation during HF, PINK1/STING (stimulator of interferon genes) double-knockout mice were created. Pressure overload was induced by TAC. Our findings indicate a significantly decline in PINK1 expression in TAC-induced hypertrophy. Cardiac hypertrophic stimuli caused the release of mitochondrial DNA (mtDNA) into the cytosol, activating the cGAS-STING signaling, which in turn initiated cardiac inflammation and promoted the progression of cardiac hypertrophy. PINK1 deficiency inhibited mitophagy activity, promoted mtDNA release, and then drove the overactivation of cGAS-STING signaling, exacerbating cardiac hypertrophy. Conversely, cardiac-specific PINK1 overexpression protected against hypertrophy thorough inhibition of the cGAS-STING signaling. Double-knockout mice revealed that the effects of PINK1 on hypertrophy were dependent on STING. Our findings suggest that PINK1-mediated mitophagy plays a protective role in pressure overload-induced cardiac hypertrophy via inhibiting the mtDNA-cGAS-STING pathway.

How Does African Swine Fever Virus Evade the cGAS-STING Pathway?

African swine fever (ASF), a highly infectious and devastating disease affecting both domestic pigs and wild boars, is caused by the African swine fever virus (ASFV). ASF has resulted in rapid global spread of the disease, leading to significant economic losses within the swine industry. A significant obstacle to the creation of safe and effective ASF vaccines is the existing knowledge gap regarding the pathogenesis of ASFV and its mechanisms of immune evasion. The cyclic GMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) pathway is a major pathway mediating type I interferon (IFN) antiviral immune response against infections by diverse classes of pathogens that contain DNA or generate DNA in their life cycles. To evade the host’s innate immune response, ASFV encodes many proteins that inhibit the production of type I IFN by antagonizing the cGAS-STING signaling pathway. Multiple proteins of ASFV are involved in promoting viral replication by protein–protein interaction during ASFV infection. The protein QP383R could impair the function of cGAS. The proteins EP364R, C129R and B175L could disturb the function of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP). The proteins E248R, L83L, MGF505-11R, MGF505-7R, H240R, CD2v, E184L, B175L and p17 could interfere with the function of STING. The proteins MGF360-11L, MGF505-7R, I215L, DP96R, A151R and S273R could affect the function of TANK Binding Kinase 1 (TBK1) and IκB kinase ε (IKKε). The proteins MGF360-14L, M1249L, E120R, S273R, D129L, E301R, DP96R, MGF505-7R and I226R could inhibit the function of Interferon Regulatory Factor 3 (IRF3). The proteins MGF360-12L, MGF505-7R/A528R, UBCv1 and A238L could inhibit the function of nuclear factor kappa B (NF-Κb).

Transcriptome-based characterization of 3’2’-cGAMP signaling mediated immune responses

Cyclic dinucleotides (CDNs) are critical adjuvants in antiviral vaccines and cancer immunotherapy, primarily through the activation of the cGAS-STING signaling pathway. Evaluating the immune responses triggered by CDNs is essential for the development of effective adjuvants. In this study, we performed a comparative transcriptome analysis to characterize the immune responses elicited by the recently identified nuclease-resistant Drosophila and bacterial CDN, 3’2’-cGAMP, in mammalian immune cells. We detected a robust induction of innate immune gene signature following 3’2’-cGAMP stimulation in digitonin-permeabilized mouse primary macrophages, comparable to the response observed with the canonical mammalian CDN, 2’3’-cGAMP. STING deficiency remarkably reduced 3’2’-cGAMP-induced phosphorylation of TBK1 and IRF3 and the induction of IFN-β, indicating that 3’2’-cGAMP signaling-mediated immune responses were mainly STING dependent. In comparison to 2’3’-cGAMP signaling, 3’2’-cGAMP signaling preferentially elicited many STING-dependent genes involved in transcription and nucleosome positioning and assembly in the nucleus, which are likely associated with several enriched pathways, including cellular senescence, HDACs deacetylate histones, and epigenetic regulation of gene expression. The integrative analysis further revealed that 3’2’-cGAMP signaling preferentially induced genes were associated with autoimmune disease-related processes, suggesting a potential side effect that requires monitoring when used as an adjuvant. In conclusion, this study provides the first transcriptional landscape of 3’2’-cGAMP signaling in mammals and reveals the immune response characteristics and potential side effects mediated by 3’2’-cGAMP signaling. These findings may aid in the development of 3’2’-cGAMP-based adjuvants for antiviral vaccines and cancer immunotherapy.

Bioengineering human heavy-chain nanoferritin for glioblastoma multiforme-specific delivery and efficient immunotherapy

The blood–brain barrier (BBB) caused limited drug accumulation and programmed death-ligand 1 (PD-L1) compromised immunosuppressive microenvironment are bottlenecks in glioblastoma multiforme (GBM) treatment. Herein, we bioengineered a human heavy chain nanoferritin (HTE NPs) for GBM-specific delivery and efficient immunotherapy. To achieve targeted mitochondrial metabolic regulation, we connected triphenylphosphonium (TPP) with the photosensitive agent IR780 to form T780, which self-assembles with esomeprazole magnesium (EM) and human H-ferritin (HFn) to obtain HTE NPs. HFn endows HTE NPs with BBB penetration and specific site-targeting capabilities, thereby enhancing tumor accumulation and pH-responsive release within GBM cells. T780 subsequently induces mitochondrial damage, activating the AMP-dependent protein kinase (AMPK) pathway and blocking the transmission of T-cell inhibitory signals through the phosphorylation of PD-L1, thereby promoting T-cell activation. Moreover, EM inhibits the release of extracellular vesicles (EVs), reducing the inhibitory effect of PD-L1 on circulating T cells. Furthermore, mitochondrial impairment-induced mitochondrial DNA (mtDNA) leakage activates the cGAS-STING signaling pathway, inducing the maturation of dendritic cells (DCs), recruiting supportive immune cells to clear GBM cells, and improving the immunosuppressive microenvironment. Therefore, HTE NPs not only achieve efficient tumor accumulation but also facilitate the activation immune response, providing a promising strategy for the clinical treatment of GBM.

The cGAS-STING mediated crosstalk between innate immunity and autophagy in leishmaniasis using mathematical modeling: Uncovering new therapeutic avenues

The present paper deals with the investigation into the cGAS-STING pathway, focusing on the signaling of interferons through mathematical modeling and identifying a significant positive feedback loop regulated by STING for activation of type 1 interferons (IFN-1). Cyclic GMP-AMP synthase (cGAS) is responsible for detecting cytosolic DNA and initiating the STING (stimulator of interferon genes) pathway, which in turn causes the synthesis of pro-inflammatory cytokines and type I interferons. In addition to being crucial for pathogen identification, this route interacts with autophagy, a cellular mechanism that is necessary for immunological homeostasis and pathogen removal. In the context of Leishmania infection, the cGAS-STING signaling axis has come to light as a critical mediator of the crosstalk between innate immunity and autophagy. Further, the protein-protein interaction studies underscored the significance of two distinct domains in mediating interactions with IRF3 and LC3. Importantly, our findings suggest the possibility of manipulating STING concomitantly to regulate IRF3 and LC3 independently. This study remarkably advances our understanding of STING's multifaceted roles, particularly in regulating IFN-1 and autophagy, highlighting its pivotal role as a cross-talk point in leishmaniasis.

The role of the cGAS-STING pathway in chronic pulmonary inflammatory diseases.

The innate immune system plays a vital role in the inflammatory process, serving as a crucial mechanism for the body to respond to infection, cellular stress, and tissue damage. The cGAS-STING signaling pathway is pivotal in the onset and progression of various autoimmune diseases and chronic inflammation. By recognizing cytoplasmic DNA, this pathway initiates and regulates inflammation and antiviral responses within the innate immune system. Consequently, the regulation of the cGAS-STING pathway has become a prominent area of interest in the treatment of many diseases. Chronic inflammatory lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, and pulmonary fibrosis, are characterized by persistent or recurrent lung inflammation and tissue damage, leading to diminished respiratory function. This paper explores the mechanism of action of the cGAS-STING signaling pathway in these diseases, examines the development of STING inhibitors and nanomaterial applications, and discusses the potential clinical application prospects of targeting the cGAS-STING pathway in chronic inflammatory lung diseases.

Dual-tDCS Ameliorates Cerebral Injury and Promotes Motor Function Recovery via cGAS-STING Signaling Pathway in a Rat Model of Ischemic Stroke.

Ischemic stroke is one of the leading causes of death and disability. Dual transcranial direct current stimulation (dual-tDCS) is a promising intervention to treat ischemic stroke, but its efficacy and underlying mechanism remain to be verified. Cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has recently emerged as a key mediator in cerebral injury. However, little is known about the effect of cGAS-STING on neuronal damage in ischemic stroke, and it remains to be studied whether the cGAS-STING pathway is involved in tDCS intervention for ischemic stroke. Therefore, we aimed to investigate whether dual-tDCS can alleviate ischemic brain injury in a rat model of ischemic stroke and if so, whether via cGAS-STING pathway. Middle cerebral artery occlusion (MCAO) was employed to induce a rat model of ischemic stroke. Male SD rats weighing 250-280g were randomly assigned to the Sham, MCAO, Dual-tDCS, Dual-tDCS + RU.521, and Dual-tDCS + 2'3'-cGAMP groups, with 10 rats in each group completing the experiment. Behavioral, morphological, MRI, and molecular biological methods were performed. We found that the cGAS-STING pathway was activated and expressed in neurons after MCAO. Dual-tDCS improved motor function and infarct volume, inhibited neuronal apoptosis, promoted the expression of neurotrophins (BDNF and NGF), CD31, and VEGF, and suppressed inflammation reaction after MCAO via the cGAS-STING pathway. Taken together, dual-tDCS may improve MCAO-induced brain injury and promote the recovery of motor function, resulting from the inhibition of neuronal apoptosis and inflammation reaction, as well as promotion of the expression of nerve plasticity- and angiogenesis-related proteins, via cGAS-STING pathway.

Toxoplasma gondii ROP5 Enhances Type I IFN Responses by Promoting Ubiquitination of STING.

Toxoplasma gondii is a widely spread opportunistic pathogen that can infect nearly all warm-blooded vertebrates and cause serious toxoplasmosis in immunosuppressed animals and patients. However, the relationship between the host's innate immune system and effector proteins is poorly understood, particularly with regard to how effectors antagonize cGAS-STING signaling during T. gondii infection. In this study, the ROP5 from the PRU strain of T. gondii was found to promote cGAS-STING-mediated immune responses. Mechanistically, ROP5 interacted with STING through predicted domain 2 and modulated cGAS-STING signaling in a predicted domain 3-dependent manner. Additionally, ROP5 strengthened cGAS-STING signaling by enhancing the K63-linked ubiquitination of STING. Consistently, ROP5 deficient PRU (PRUΔROP5) induced fewer type I IFN-related immune responses and replicated faster than the parental strain in RAW264.7 cells. Taken together, this study provides new insights into the mechanism by which ROP5 regulates T. gondii infection and provides new clues for strategies to prevent and control toxoplasmosis.

Recent advancements in cGAS-STING activation, tumor immune evasion, and therapeutic implications.

The cGAS-STING signaling pathway is indeed a pivotal component of the immune system and serve as a crucial link between innate and adaptive immune responses. STING is involved in the cellular response to pathogen invasion and DNA damage, and which has important consequences for host defense mechanisms and cancer regulation. Ongoing research aiming to modulate the cGAS-STING pathway for improved clinical outcomes in cancer and autoimmune diseases is underway. Indeed, the interaction between the cGAS-STING pathway and immune evasion mechanisms is a complex and critical aspect of cancer biology. Pathogens and various host factors can exploit this pathway to reduce the effectiveness of cancer therapies, particularly immunotherapies. Thus, immunotherapies or combination therapies may assist in overcoming the immune suppression and improving clinical outcomes. This review explores recent advancements in understanding the cGAS-STING signaling pathway, with particular emphasis on its activation mechanisms and role in tumor immune evasion. The dual role of the pathway in boosting immune responses while simultaneously enabling tumors to evade the immune system makes it a crucial target for innovative cancer treatment approaches.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 2 Given name: [Md Mazedul] Last name [Islam], Author 3 Given name: [Mst Rubaiat Nazneen] Last name [Akhand] and Author 5 Given name: [Md Rashedunnabi] Last name [Akanda]. Also, kindly confirm the details in the metadata are correct.AQ1: Here Author 4 given name: [Byung-Yong] Last name [Park] is missing. Metadata are correct.

T-2 Toxin Induces Immunosenescence in RAW264.7 Macrophages by Activating the HIF-1α/cGAS-STING Pathway.

T-2 toxin induces cell immunotoxicity by triggering an intracellular hypoxic microenvironment and activates hypoxia-inducible factor-1α (HIF-1α), which exerts cellular protective effects. Mycotoxins can also induce senescence. The aging of immune function, termed "immunosenescence," is an important factor in the decline of biological immunity and accelerates senescence. However, the mechanism underlying T-2 toxin-induced immunosenescence remains unclear. This study aimed to elucidate the roles of HIF-1α and cGAS-STING signaling in this process and uncover the mechanisms through which T-2 toxin impacts cytoskeletal integrity and cellular senescence using a RAW264.7 macrophage model. The cells were treated with T-2 toxin (14 nM) for 1-24 h. We revealed that T-2 toxin-induced immunosenescence in RAW264.7 cells by activating the HIF-1α/cGAS-STING axis. The cGAS-STING pathway promotes cell senescence and apoptosis; however, we revealed that HIF-1α negatively regulated this pathway, thereby inhibiting cellular senescence and apoptosis. However, PARP 1 cleavage by caspase 3/9 inhibited DNA repair and accelerated the transition from senescence to apoptosis. At the late stages of T-2 toxin exposure (12 h), HIF-1α accelerated cellular senescence by disrupting the dynamic balance of cytoskeletal α-tubulin and F-actin and destabilizing the cytoskeletal structure. Our research demonstrates that T-2 toxin induces immunosenescence in RAW264.7 cells by activating the cGAS-STING pathway, with HIF-1α signaling serving as a negative regulator. This study provides a deeper understanding of T-2 toxin-induced immunosenescence.

Corilagin inhibits human cytomegalovirus infection and replication via activating the cGAS-STING signaling pathway in vitro and in vivo

AimThe existence of human cytomegalovirus (HCMV) is extremely widespread, causing serious diseases in patients with low immune function. The purpose of this study is to explore the efficacy and mechanism of Corilagin in the control of CMV infection, in order to provide scientific basis for the control of CMV infection. MethodsOur study employed an animal model in Balb/c mice, infected with MCMV, alongside cellular models in HFF cells and THP-1 cells, stimulated with HCMV. The expression of cGAS-STING signaling pathway molecules was detected in liver tissue, lung tissue, serum, cells and cell supernatant. The liver function and histopathological changes of mice were evaluated. ResultsIn vivo and in vitro experiments showed that Corilagin significantly inhibits CMV levels and attenuates pathological damage in liver and lung tissues in vivo, and similarly inhibits viral load in cells in vitro. Corilagin promotes the expression levels of STING and its downstream molecules in vivo and in vitro. Inhibition/down-regulation of STING significantly promotes CMV replication, on the contrary, activation/up-regulation of STING inhibits CMV replication, and Corilagin also promotes the expression levels of molecules related to the cGAS-STING signaling pathway in the above cases. ConclusionCorilagin could effectively inhibit the infection and replication of CMV in vitro and in vivo, which may be through the activation of cGAS-STING signaling pathway.

Bidirectional regulation of the cGAS-STING pathway in the immunosuppressive tumor microenvironment and its association with immunotherapy.

Adaptive anti-tumor immunity is currently dependent on the natural immune system of the body. The emergence of tumor immunotherapy has improved prognosis and prolonged the survival cycle of patients. Current mainstream immunotherapies, including immune checkpoint blockade, chimeric antigen receptor T-cell immunotherapy, and monoclonal antibody therapy, are linked to natural immunity. The cGAS-STING pathway is an important natural immunity signaling pathway that plays an important role in fighting against the invasion of foreign pathogens and maintaining the homeostasis of the organism. Increasing evidence suggests that the cGAS-STING pathway plays a key role in tumor immunity, and the combination of STING-related agonists can significantly enhance the efficacy of immunotherapy and reduce the emergence of immunotherapeutic resistance. However, the cGAS-STING pathway is a double-edged sword, and its activation can enhance anti-tumor immunity and immunosuppression. Immunosuppressive cells, including M2 macrophages, MDSC, and regulatory T cells, in the tumor microenvironment play a crucial role in tumor escape, thereby affecting the immunotherapy effect. The cGAS-STING signaling pathway can bi-directionally regulate this group of immunosuppressive cells, and targeting this pathway can affect the function of immunosuppressive cells, providing new ideas for immunotherapy. In this study, we summarize the activation pathway of the cGAS-STING pathway and its immunological function and elaborate on the key role of this pathway in immune escape mediated by the tumor immunosuppressive microenvironment. Finally, we summarize the mainstream immunotherapeutic approaches related to this pathway and explore ways to improve them, thereby providing guidelines for further clinical services.

Singapore grouper iridovirus VP12 evades the host antiviral immune response by targeting the cGAS-STING signalling pathway.

The emergence of Singapore grouper iridovirus (SGIV) has caused huge losses to grouper farming. SGIV is a DNA virus and belongs to the genus Ranavirus. Groupers infected with SGIV showed haemorrhaging and swelling of the spleen, with a mortality rate of more than 90% within a week. Therefore, it is of great significance to study the escape mechanism of SGIV from host innate immunity for the prevention and treatment of viral diseases in grouper. In this study, the viral proteins that interact with EccGAS were identified by mass spectrometry, and the SGIV VP12 protein that inhibits cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-mediated antiviral innate immunity was screened by the dual-luciferase reporter gene assay. VP12 belongs to the late gene of the virus. The immunofluorescence analysis demonstrated that VP12 was aggregated and distributed in the cytoplasm during the early stage of virus infection and translocated into the nucleus at the late stage of virus infection. VP12 inhibited the activation of IFN3, ISRE and NF-κB promoter activities mediated by cGAS-STING, EcTBK1 and EcIRF3. Quantitative real-time PCR analysis showed that VP12 inhibited the expression of interferon-related genes, including those mediated by cGAS-STING. VP12 enhanced the inhibition of IFN3, ISRE and NF-κB promoter activity by EccGAS, EccGAS-mab-21 and EccGAS-delete-mab21. The interaction between VP12 and EccGAS was found to be domain independent. The immunoprecipitation results demonstrated that VP12 interacted and co-localized with EccGAS, EcTBK1 and EcIRF3. VP12 degraded the protein levels of EcTBK1 and EcIRF3 and degraded EcIRF3 through the protease pathway. These results suggest that SGIV VP12 protein escapes the cGAS-STING signalling pathway and degrades EcIRF3 protein expression through the protease pathway.

Silencing of SIRPα enhances the antitumor efficacy of CAR-M in solid tumors

The potential of macrophage-mediated phagocytosis as a cancer treatment is promising. Blocking the CD47–SIRPα interaction with a CD47-specific antibody significantly enhances macrophage phagocytosis. However, concerns regarding their toxicity to nontumor cells remain substantial. Here, we engineered chimeric antigen receptor macrophages (CAR-Ms) by fusing a humanized single-chain variable fragment with FcγRIIa and integrating short hairpin RNA to silence SIRPα, thereby disrupting the CD47–SIRPα signaling pathway. These modified CAR-shSIRPα-M cells exhibited an M1-like phenotype, superior phagocytic function, substantial cytotoxic effects on HER2-positive tumor cells, and the ability to eliminate patient-derived organoids. In vivo, CAR-M cells significantly inhibited tumor growth and prolonged survival in tumor-bearing mice. Notably, CAR-shSIRPα-M cells enhanced cytotoxic T-cell infiltration into tumors, thereby enhancing the antitumor response in both the humanized immune system mouse model and immunocompetent mice. Mechanistically, SIRPα inhibition activated inflammatory pathways and the cGAS-STING signaling cascade in CAR-M cells, leading to increased production of proinflammatory cytokines, reactive oxygen species, and nitric oxide, thereby enhancing their antitumor effects. These findings underscore the potential of SIRPα inhibition as a novel strategy to increase the antitumor efficacy of CAR-M cells in cancer immunotherapy, particularly against solid tumors.

Neuroprotection of celastrol against postoperative cognitive dysfunction through dampening cGAS-STING signaling

Neuroinflammation is a central player in postoperative cognitive dysfunction (POCD), an intractable and highly confounding neurological complication with finite therapeutic options. Celastrol, a quinone methide triterpenoid, is a bioactive ingredient extracted from Tripterygium wilfordii with talented anti-inflammatory capacity. However, it is unclear whether celastrol can prevent anesthesia/surgery-evoked cognitive deficits in an inflammation-specific manner. The STING agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was used to determine whether celastrol possesses neuroprotection dependent on the STING pathway in vivo and in vitro. Isoflurane and laparotomy triggered cGAS-STING activation, caspase-3/GSDME-dependent pyroptosis, and enhanced Iba-1 immunoreactivity. Celastrol improved cognitive performance and decreased the levels of cGAS, 2′3′-cGAMP, STING, NF-κB phosphorylation, Iba-1, TNF-α, IL-6, and IFN-β. Downregulation of cleaved caspase-3 and N-GSDME was observed in the hippocampus of POCD mice and HT22 cells after celastrol administration, accompanied by limited secretion of pyroptosis-pertinent pro-inflammatory cytokines IL-1β and IL-18. DMXAA neutralized the favorable influences of celastrol on cognitive function, as confirmed by the activation of the STING/caspase-3/GSDME axis. These findings implicate celastrol as a therapeutic agent for POCD through anti-inflammation and anti-pyroptosis.

Intricate Role of the Cyclic Guanosine Monophosphate Adenosine Monophosphate Synthase-Stimulator of Interferon Genes (cGAS-STING) Pathway in Traumatic Brain Injury-Generated Neuroinflammation and Neuronal Death.

The secondary insult in the aftermath of traumatic brain injury (TBI) causes detrimental and self-perpetuating alteration in cells, resulting in aberrant function and the death of neuronal cells. The secondary insult is mainly driven by activation of the neuroinflammatory pathway. Among several classical pathways, the cGAS-STING pathway, a primary neuroinflammatory route, encompasses the cyclic GMP-AMP synthase (cGAS), stimulator of interferon genes (STING), and downstream signaling adaptor. Recently, the cGAS-STING research domain has gained exponential attention. The aberrant stimulation of cGAS-STING machinery and corresponding neuroinflammation have also been reported after TBI. In addition to the critical contribution to neuroinflammation, the cGAS-STING signaling also provokes neuronal cell death through various cell death mechanisms. This review highlights the structural and molecular mechanisms of the cGAS-STING machinery associated with TBI. We also focus on the intricate relationship and framework between cGAS-STING signaling and cell death mechanisms (autophagy, apoptosis, pyroptosis, ferroptosis, and necroptosis) in the aftermath of TBI. We suggest that the targeting of cGAS-STING signaling may open new therapeutic strategies to combat neuroinflammation and neurodegeneration in TBI.

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.