The cGAS-STING pathway as a therapeutic target in inflammatory diseases

Lycopene: A potent antioxidant to alleviate kidney disease

Kidney disease is a major public health problem worldwide and one of the common causes of death in patients. How to effectively treat or alleviate renal diseases has not only attracted the attention of a large number of scholars, but is likewise a great challenge. Oxidative stress is the main mechanism leading to kidney injury. Natural antioxidant substances not only have efficient antioxidant capacity, but also have the advantage of high safety and low side effects. Lycopene is a naturally occurring carotenoid found mainly in tomatoes or tomato products. Epidemiologic investigations have shown that lycopene has potent antioxidant properties, scavenges reactive substances, and has a protective role in kidney disease. This paper summarizes the biochemical properties and antioxidant mechanisms of lycopene in the context of animal experiments and clinical studies of lycopene in renal diseases. We found that lycopene exerts its protective effects against kidney injury mainly through anti-oxidative stress and anti-inflammatory effects. Meanwhile, lycopene has been found to reduce the incidence of Chronic Kidney Disease (CKD) as well as mortality in some CKD patients. In addition to this, lycopene intake is negatively correlated with the incidence of kidney cancer and also mitigates the nephrotoxic damage of cisplatin. Therefore, lycopene has a promising application in the treatment of kidney diseases. However, there are relatively few clinical studies on lycopene in renal diseases, and subsequent research studies in large-scale populations are still needed to determine the value of lycopene in renal diseases even further.

ZNFX1 Functions as a Master Regulator of Epigenetically Induced Pathogen Mimicry and Inflammasome Signaling in Cancer

DNA methyltransferase (DNMT) and PARP inhibitors induce a stimulator of IFN gene-dependent pathogen mimicry response (PMR) in ovarian and other cancers. In this study, we showed that combining DNMT and PARP inhibitors upregulates expression of the nucleic acid sensor NFX1-type zinc finger-containing 1 (ZNFX1) protein. ZNFX1 mediated the induction of PMR in mitochondria, serving as a gateway for stimulator of IFN gene-dependent IFN/inflammasome signaling. Loss of ZNFX1 in ovarian cancer cells promoted proliferation and spheroid formation in vitro and tumor growth in vivo. In patient ovarian cancer databases, expression of ZNFX1 was elevated in advanced stage disease, and ZNFX1 expression alone significantly correlated with an increase in overall survival in a phase III trial for patients with therapy-resistant ovarian cancer receiving bevacizumab in combination with chemotherapy. RNA sequencing revealed an association between inflammasome signaling through ZNFX1 and abnormal vasculogenesis. Together, this study identified that ZNFX1 is a tumor suppressor that controls PMR signaling through mitochondria and may serve as a biomarker to facilitate personalized therapy in patients with ovarian cancer. Significance: DNMT and PARP inhibitors induce a nucleic acid sensor, ZNFX1, that serves as a mitochondrial gateway to STING-dependent inflammasome signaling with tumor suppressor properties in ovarian cancer.

Targeting KIF18A triggers antitumor immunity and enhances efficiency of PD-1 blockade in colorectal cancer with chromosomal instability phenotype

Colorectal cancer with chromosomal instability (CIN+) phenotype is immunosuppressive and refractory to immune checkpoint blockade (ICB) therapy. Recently, KIF18A is found to be a mitotic vulnerability in chromosomally unstable cancers, but whether targeting KIF18A affects antitumor immunity in CIN+ colorectal cancer is unknown. In our study, western blot, cell viability assay, transwell migration and invasion assays, flow cytometry, animal model, immunohistochemistry (IHC) staining, reverse transcription-quantitative PCR (RT-qPCR) and ELISA assay were conducted to evaluate the potential function of KIF18A in CIN+ colorectal cancer. We found that KIF18A inhibition by short hairpin RNAs (ShRNAs) or small inhibitor AM-1882 suppressed proliferation, migration, invasion and tumor growth and metastasis of CIN+ colorectal cancer cells in vitro and in vivo. Moreover, targeting KIF18A disrupted cell-cycle progression and induced G2/M arrest in CIN+ colorectal cancer cells. In addition, KIF18A inhibition promoted immune infiltration and activation in CIN+ colorectal tumors. KIF18A inhibition suppressed proliferation of Tregs and increased infiltration and activation of cytotoxic CD8+ T cells in CIN+ colorectal tumors. Mechanically, KIF18A inhibition stimulated type I IFN signaling and cGAS-STING activation in CIN+ colorectal tumors. Finally, targeting KIF18A enhanced PD-1 blockade efficiency in CIN+ colorectal tumors through T cells. Our data elucidated a novel role of KIF18A in antitumor immunity of CIN+ colorectal cancer.

Nuclear receptor coactive 4-mediated ferritinophagy: a key role of heavy metals toxicity

Nuclear receptor coactive 4 (NCOA4) is a specific receptor for ferritinophagy, transporting ferritin to lysosomal degradation, releasing free iron, and excessive iron levels may lead to cellular redox imbalance, contributing to cell death, predominantly ferroptosis. NCOA4 is regulated by a variety of transcriptional, post-transcriptional, translational, and post-translational modifications. Targeted modulation of NCOA4-mediated ferritinophagy has been successfully used as a therapeutic strategy in several disease models. Recent evidences have elucidated that ferritinophagy and ferroptosis played a major role in heavy metals toxicity. In this review, we explored the regulatory mechanism of NCOA4 as the sole receptor for ferritinophagy from multiple perspectives based on previous studies. The significant role of ferritinophagy-mediated ferroptosis in heavy metals toxicity was discussed in detail, emphasizing the great potential of NCOA4 as a target for heavy metals toxicity.

Enhancing immunotherapy with tumour-responsive nanomaterials

The targeted delivery of immunotherapies to tumours using tumour-responsive nanomaterials is a promising area of cancer research with the potential to address the limitations of systemic administration such as on-target off-tumour toxicities and a lack of activity owing to the immunosuppressive tumour microenvironment (TME). Attempts to address these challenges include the design and functionalization of nanomaterials capable of releasing their cargoes in response to specific TME characteristics, thus facilitating the targeted delivery of immune-checkpoint inhibitors, cytokines, mRNAs, vaccines and, potentially, chimaeric antigen receptors as well as of agents that modulate the extracellular matrix and induce immunogenic cell death. In this Review, we describe these various research efforts in the context of the dynamic properties of the TME, such as pH, reductive conditions, reactive oxygen species, hypoxia, specific enzymes, high levels of ATP and locoregional aspects, which can be leveraged to enhance the specificity and efficacy of nanomaterial-based immunotherapies. Highlighting preclinical successes and ongoing clinical trials, we evaluate the current landscape and potential of these innovative approaches. We also consider future research directions as well as the most important barriers to successful clinical translation, emphasizing the transformative potential of tumour-responsive nanomaterials in overcoming the barriers that limit the activity of traditional immunotherapies, thus improving patient outcomes.

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.

Based on the Sam50-MICOS-ATAD3-mtDNA axis: Exploring oligomeric proanthocyanidins to alleviate molybdenum and cadmium co-induced liver inflammation in sheep

Molybdenum (Mo) and cadmium (Cd), well-defined hazardous pollutants in the environment, exhibit potential toxic effects on liver tissues by inducing oxidative stress and inflammatory responses. This study aims to investigate the role of the Sam50-MICOS-ATAD3-mtDNA axis in mediating the inflammatory response in liver inflammation induced by co-exposure to Mo and Cd in sheep, as well as the protective effects of oligomeric proanthocyanidins (OPC). The findings indicated that co-exposure to Mo and Cd induced cellular degeneration, rupture of hepatic mitochondrial membranes and mitochondrial dysfunction that was accompanied by the levels of ATP, SDH and GSH-Px reduced in the sheep liver tissue. Furthermore, the co-exposure downregulated the expression levels of mitochondrial membrane proteins (Sam50, MICOS and ATAD3) and degree of co-localization between Sam50 and Mic60. In addition, co-exposure to Mo and Cd elicited an increase in mtDNA content and promoted the upregulation of inflammation-related factor levels, which resulted in an augmentation of TNF-α, CRP, and IL-18 contents. However, OPC alleviated the above changes induced by the combination of Mo and Cd. In conclusion, co-exposure to Mo and Cd decreases mtDNA stability by disrupting the Sam50-MICOS-ATAD3 axis, thereby inducing liver inflammation in sheep. Nevertheless, OPC could alleviate this damage.

Origin and function of anti-interferon type I viral proteins

Type I interferons (IFN-I) are the most important innate immune cytokines produced by vertebrate host cells following, virus infection. Broadly speaking, detection of infecting viral nucleic acids by pattern recognition receptors (PRR) and subsequent downstream signaling triggers synthesis of a large number of IFN-I-stimulated genes (ISGs), endowed with diverse antiviral effector function. The co-evolution of virus-host interactions over million years has resulted in the emergence of viral strategies that target and inhibit host PRR-mediated detection, signal transduction pathways and IFN-I-mediated stimulation of ISGs. In this review, we illustrate the multiple mechanisms of viral immune evasion and discuss the co-evolution of anti-IFN-I viral proteins by summarizing key examples from recent literature. Due to the large number of anti-IFN-I proteins described, we provide here an evaluation of the prominent examples from different virus families. Understanding the unrelenting evolution of viral evasion strategies will provide mechanistic detail concerning these evolving interactions but will further enhance the development of tailored antiviral approaches.

Cross-priming in cancer immunology and immunotherapy

Cytotoxic T cell immune responses against cancer crucially depend on the ability of a subtype of professional antigen-presenting cells termed conventional type 1 dendritic cells (cDC1s) to cross-present antigens. Cross-presentation comprises redirection of exogenous antigens taken from other cells to the major histocompatibility complex class I antigen-presenting machinery. In addition, once activated and having sensed viral moieties or T helper cell cooperation via CD40-CD40L interactions, cDC1s provide key co-stimulatory ligands and cytokines to mount and sustain CD8+ T cell immune responses. This regulated process of cognate T cell activation is termed cross-priming. In cancer mouse models, CD8+ T cell cross-priming by cDC1s is crucial for the efficacy of most, if not all, immunotherapy strategies. In patients with cancer, the presence and abundance of cDC1s in the tumour microenvironment is markedly associated with the level of T cell infiltration and responsiveness to immune checkpoint inhibitors. Therapeutic strategies to increase the numbers of cDC1s using FMS-like tyrosine kinase 3 ligand (FLT3L) and/or their activation status show evidence of efficacy in cancer mouse models and are currently being tested in initial clinical trials with promising results so far.

Therapeutic potential of apoptotic vesicles in modulating inflammation, immune responses, and tissue regeneration

The process of apoptosis plays a crucial role in tissue homeostasis, immune system regulation, and organ formation. Apoptotic vesicles (ApoEVs) are involved in efferocytosis, the process by which phagocytes ingest dead cells. ApoEVs also have potential therapeutic applications in cancer treatment, ischemic diseases, and their anti-inflammatory properties make them incredibly versatile for medical applications. These vesicles can induce apoptosis in cancer cells, provide tumor antigens for cancer vaccines, and even serve as effective drug delivery systems. Moreover, they can target hypoxic cells, inhibit inflammatory cell death pathways, and promote tissue regeneration. Also, their potential in addressing inflammatory disorders such as gastrointestinal ailments, osteoarthritis, and diabetes is promising. Additionally, ApoEVs can polarize anti-inflammatory immune cells and suppress inflammatory immune responses which make them a viable option for addressing the unmet need for novel anti-inflammatory medications. Despite a wealth of reviews examining the applications of ApoEVs, very few have thoroughly investigated the mechanisms underlying their anti-inflammatory effects. This distinctive approach positions the current review as timely and immensely relevant, illuminating the intriguing ways these entities function beyond their established advantages.

A novel biosensor for the spatiotemporal analysis of STING activation during innate immune responses to dsDNA

The cGAS-STING signalling pathway has a central role in the innate immune response to extrinsic and intrinsic sources of cytoplasmic dsDNA. At the core of this pathway is cGAS-dependent production of the intra- and extra-cellular messenger cGAMP, which activates STING and leads to IRF3-dependent expression of cytokines and interferons. Despite its relevance to viral and bacterial infections, cell death, and genome instability, the lack of specific live-cell reporters has precluded spatiotemporal analyses of cGAS-STING signalling. Here, we generate a fluorescent biosensor termed SIRF (STING-IRF3), which reports on the functional interaction between activated STING and IRF3 at the Golgi. We show that cells harbouring SIRF react in a time- and concentration-dependent manner both to STING agonists and to microenvironmental cGAMP. We demonstrate that the new biosensor is suitable for single-cell characterisation of immune responses to HSV-1 infection, mtDNA release upon apoptosis, or other sources of cytoplasmic dsDNA. Furthermore, our results indicate that STING signalling is not activated by ruptured micronuclei, suggesting that other cytosolic pattern recognition receptors underlie the interferon responses to chromosomal instability.

Regulation of the cGAS-STING Pathway

The cGAS-cGAMP-STING pathway is essential for immune defense against pathogens. Upon binding DNA, cGAS synthesizes cGAMP, which activates STING, leading to potent innate immune effector responses. However, lacking specific features to distinguish between self and nonself DNA, cGAS-STING immunity requires precise regulation to prevent aberrant activation. Several safeguard mechanisms acting on different levels have evolved to maintain tolerance to self DNA and ensure immune homeostasis under normal conditions. Disruption of these safeguards can lead to erroneous activation by self DNA, resulting in inflammatory conditions but also favorable antitumor immunity. Insights into structural and cellular checkpoints that control and terminate cGAS-STING signaling are essential for comprehending and manipulating DNA-triggered innate immunity in health and disease.

Carnosic Acid Directly Targets STING C-Terminal Tail to Improve STING-Mediated Inflammatory Diseases

cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) signaling plays a vital role in innate immunity, while its deregulation may lead to a wide variety of autoinflammatory and autoimmune diseases. It is essential to identify specifically effective lead compounds to inhibit the signaling. Herein, it is shown that carnosic acid (CA), an active ingredient of medicinal plant Rosmarinus officinalis L., specifically suppressed cGAS-STING pathway activation and the subsequent inflammatory responses. Mechanistically, CA directly bound to STING C-terminal tail (CTT), impeded the recruitment of TANK-binding kinase 1 (TBK1) onto STING signalosome, thereby blocking the phosphorylation of STING and interferon regulatory factor 3 (IRF3) nuclear translocation. Importantly, CA dramatically attenuated STING-mediated inflammatory responses in vivo. Consistently, CA has a salient ameliorative effect on autoinflammatory disease model mediated by Trex1 deficiency, via inhibition of the cGAS-STING signaling. Notably, the study further indicates that phenolic hydroxyl groups are essential for CA-mediated STING inhibitory activity. Collectively, the results thus identify STING as one of the crucial targets of CA for mediating CA's anti-inflammatory activity, and further reveal that STING CTT may be a novel promising target for drug development.

Bimetallic MnZnSX Nanotheranostics for Self-Activatable Chemo-Immunotherapy of Hepatocellular Carcinoma via H₂S-Triggered Arsenic Prodrug Activation and Binary cGAS-STING Pathway Modulation

Arsenic trioxide (As2O3) has long been utilized in traditional Chinese medicine due to its therapeutic properties. While it exhibits potent anticancer activity, its clinical application is hindered by systemic toxicity and limited tissue specificity. In this study, an advanced therapeutic approach is developed using arsenic prodrug-loaded bimetallic sulfide MnZnSX nanorods (As-MnZnSX NRs) to enhance both the efficacy and safety of As2O3 in hepatocellular carcinoma treatment. These nanorods are engineered to release Mn2+ and H2S within the tumor microenvironment, facilitating binary-cooperative activation of the cGAS-STING pathway. This dual activation mechanism enhances immune responses while converting the arsenic prodrug into its cytotoxic form, AsIII. The results demonstrate that Mn2+ amplifies the cGAS-STING pathway by inducing TBK1 phosphorylation and IRF3 activation, leading to dendritic cell maturation and improved tumor antigen cross-presentation. Simultaneously, H2S promotes prodrug conversion and enhances immune activation, collectively driving binary stimulation of the cGAS-STING pathway. This strategy significantly augments the antitumor efficacy of As2O3 by integrating immune modulation with targeted cytotoxic effects. Furthermore, MnZnSX nanorods enable in vivo MRI, allowing real-time monitoring of treatment progression. This study represents a substantial advancement in liver cancer therapy by integrating chemoimmunotherapy with diagnostic imaging, thereby improving therapeutic precision while minimizing systemic toxicity.

ATG16L1 restrains macrophage NLRP3 activation and alveolar epithelial cell injury during septic lung injury

BACKGROUND

The lung is the organ most commonly affected by sepsis. Additionally, acute lung injury (ALI) resulting from sepsis is a major cause of death in intensive care units. Macrophages are essential for maintaining normal lung physiological functions and are implicated in various pulmonary diseases. An essential autophagy protein, autophagy-related protein 16-like 1 (ATG16L1), is crucial for the inflammatory activation of macrophages.

METHODS

ATG16L1 expression was measured in lung from mice with sepsis. ALI was induced in myeloid ATG16L1-, NLRP3- and STING-deficient mice by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). Using immunofluorescence and flow cytometry to assess the inflammatory status of LPS-treated bone marrow-derived macrophages (BMDMs). A co-culture system of BMDMs and MLE-12 cells was established in vitro.

RESULTS

Myeloid ATG16L1-deficient mice exhibited exacerbated septic lung injury and a more intense inflammatory response following LPS treatment. Mechanistically, ATG16L1-deficient macrophages exhibited impaired LC3B lipidation, damaged mitochondria and reactive oxygen species (ROS) accumulation. These abnormalities led to the activation of NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), subsequently enhancing proinflammatory response. Overactivated ATG16L1-deficient macrophages aggravated the damage to alveolar epithelial cells and enhanced the release of double-stranded DNA (dsDNA), thereby promoting STING activation and subsequent NLRP3 activation in macrophages, leading to positive feedback activation of macrophage NLRP3 signalling. Scavenging mitochondrial ROS or inhibiting STING activation effectively suppresses NLRP3 activation in macrophages and alleviates ALI. Furthermore, overexpression of myeloid ATG16L1 limits NLRP3 activation and reduces the severity of ALI.

CONCLUSIONS

Our findings reveal a new role for ATG16L1 in regulating macrophage NLRP3 feedback activation during sepsis, suggesting it as a potential therapeutic target for treating sepsis-induced ALI.

KEY POINTS

Myeloid-specific ATG16L1 deficiency exacerbates sepsis-induced lung injury. ATG16L1-deficient macrophages exhibit impaired LC3B lipidation and ROS accumulation, leading to NLRP3 inflammasome activation. Uncontrolled inflammatory responses in ATG16L1-deficient macrophages aggravate alveolar epithelial cell damage. Alveolar epithelial cells release dsDNA, activating the cGAS-STING-NLRP3 signaling pathway, which subsequently triggers a positive feedback activation of NLRP3. Overexpression of ATG16L1 helps mitigate lung tissue inflammation, offering a novel therapeutic direction for sepsis-induced lung injury.

Circulating cell-free DNA promotes inflammation in dermatomyositis patients with anti-NXP2 antibodies via the cGAS/STING pathway

OBJECTIVES

DM is a rare type I IFN (IFN-I)-driven autoimmune disease, and anti-nuclear matrix protein 2 (NXP2) antibody is related to severe muscle disease and poor prognosis. Circulating cell-free DNA (ccf-DNA), including ccf-mitochondrial DNA and ccf-nuclear DNA, activates the cGAS/STING pathway to induce IFN-I production in autoimmune diseases. We investigated whether serum-derived ccf-DNA had a pathogenic effect on skeletal muscle in anti-NXP2 antibody-positive DM.

METHODS

Serum ccf-DNA levels were measured, and correlations between ccf-DNA and clinicopathological indicators were performed. RNA sequencing, immunofluorescence, western blotting and reverse transcriptase quantitative polymerase chain reaction were performed on skeletal muscle samples. The serum-induced expression of p-STING in C2C12 cells was assessed in vitro.

RESULTS

We found that increased ccf-DNA levels were positively correlated with MYOACT scores in anti-NXP2 antibody-positive DM. RNA sequencing and immunofluorescence results revealed that the cytosolic DNA-sensing pathway was upregulated and that increased cytosolic dsDNA was colocalized with cGAS in skeletal muscle in anti-NXP2 antibody-positive DM. Western blot analysis revealed activation of the cGAS/STING pathway in patients with perifascicular atrophy (PFA) but not in patients without PFA. Reverse transcriptase quantitative polymerase chain reaction showed increased IFN-I scores in both patients with PFA and patients without PFA. Sera from patients with PFA increased p-STING expression in C2C12 cells, and DNase I treatment and STING inhibitor efficiently inhibited p-STING expression, respectively.

CONCLUSION

Increased ccf-DNA levels may be potential biomarkers for monitoring disease activity in anti-NXP2 antibody-positive DM. Activation of the cGAS/STING pathway is associated with PFA. Our findings identified a pathogenic effect of ccf-DNA on skeletal muscle via the cGAS/STING pathway.

Optogenetics in medicine: innovations and therapeutic applications

Optogenetics, an innovative approach integrating photonics and genetic engineering, enables precise control over molecular and cellular processes, opening up exciting new opportunities for precision-guided medicine. In this review, we highlight recent advances in optogenetic tools and their applications across a range of medical conditions, including vision restoration in retinitis pigmentosa via light-activated ion channels, precise immune response modulation in cancer immunotherapy, and blood glucose management in diabetes through controllable drug release. Optogenetics also plays a critical role in bioelectronic medicine, enabling seamless communication between electronic systems and biological tissues to enhance therapeutic precision. Finally, we discuss the challenges and potential transition of optogenetics from experimental models to clinical therapies, emphasizing its immense potential to transform future medical treatments.

TRIM21 promotes type I interferon by inhibiting the autophagic degradation of STING via p62/SQSTM1 ubiquitination in systemic lupus erythematosus

The cGAS-STING signaling pathway serves as a pivotal surveillance mechanism for cytosolic double-stranded DNA (dsDNA) detection in mammalian systems. While STING-mediated type I interferon production is crucial for host defense, sustained activation of this pathway contributes to autoimmune pathologies, including systemic lupus erythematosus (SLE). Maintaining immune homeostasis requires precise regulation of STING activity to prevent hyperactivation. Our study identifies TRIM21 as a novel positive regulator of cGAS-STING signaling in SLE pathogenesis. Our results demonstrate that TRIM21 overexpression stabilizes STING by suppressing autophagic degradation, whereas TRIM21 depletion accelerates this clearance process. Mechanistically, TRIM21 catalyzes the K63-linked polyubiquitylation of the selective autophagy receptor p62/SQSTM1, disrupting its interaction with STING. This post-translational modification prevents the sequestration of STING into autophagosomes, thereby stabilizing the adaptor protein and amplifying downstream type I interferon responses. Our findings reveal a previously unrecognized regulatory circuit in which TRIM21 orchestrates cross-talk between ubiquitin signaling and autophagy to control STING turnover. The TRIM21-p62 axis represents a potential therapeutic target for attenuating pathological interferon production in STING-dependent autoimmune disorders. This work advances our understanding of immune regulation by demonstrating how E3 ligase-mediated ubiquitin modifications modulate cargo recognition in selective autophagy pathways. The identified mechanism provides new insights into the molecular interplay between protein ubiquitylation and autophagic degradation in maintaining the innate immune balance, offering novel perspectives for developing targeted therapies against interferonopathies associated with cGAS-STING hyperactivity.

ALDH1A3 Regulates Cellular Senescence and Senescence-Associated Secretome in Prostate Cancer

Background: Radiotherapy is a key treatment for cancer, effectively controlling local tumor growth through DNA damage that induces senescence or apoptosis in cancer cells. However, radiotherapy can trigger complex cellular reactions, such as cell senescence, which is characterized by irreversible cell cycle arrest and the secretion of pro-inflammatory factors known as the senescent-associated secretory phenotype (SASP). Methods: This study investigates the regulatory role of ALDH1A3, a key enzyme implicated in cancer cell metabolism and radiotherapy resistance, in the induction of senescence and SASP. Using in vitro models, we demonstrate that ALDH1A3 knockdown accelerates cellular senescent-like phenotype while regulating the SASP through the cGAS-STING immune response pathway. Results: Our results indicate that while ALDH1A3 knockdown promotes senescence, it reduces the secretion of pro-inflammatory factors via inhibition of the cGAS-STING pathway, potentially mitigating SASP-related tumor progression. Conclusions: These findings provide insights into the molecular mechanisms underlying prostate cancer cell senescence and suggest that ALDH1A3 could be a potential therapeutic target to enhance the efficacy of radiotherapy while controlling the adverse effects of SASP.

Reciprocal regulation between ferroptosis and STING-type I interferon pathway suppresses head and neck squamous cell carcinoma growth through dendritic cell maturation

Head and neck squamous cell carcinoma (HNSCC) presents a serious clinical challenge mainly due to its resistance to conventional therapies and its complex, immunosuppressive tumor microenvironment. While recent studies have identified ferroptosis as a new therapeutic option, its impact on the immune microenvironment in HNSCC remains controversial, which may hinder its translational application. Although the role of the stimulator of interferon genes (STING)-type I interferon (IFN-I) pathway in antitumor immune responses has been widely investigated, its relationship with ferroptosis in HNSCC has not been fully explored. In this study, we discovered that ferroptosis in HNSCC inhibited tumor growth, activated STING-IFN-I pathway and subsequently improved recruitment and maturation of dendritic cells. We further demonstrated that IFN-I could enhance ferroptosis by inhibiting xCT-glutathione peroxidase 4 (GPX4) antioxidant system. To harness this positive feedback loop, we treated HNSCC tumors with both ferroptosis inducer and STING agonist, resulting in significant tumor suppression, elevated ferroptosis levels and enhanced dendritic cell infiltration. Overall, our findings reveal a mutually regulatory relationship between ferroptosis and the intrinsic STING-IFN-I pathway, providing novel insights into immune-mediated tumor suppression and suggesting its potential as therapeutic approach in HNSCC.

Protective effects of berberine on MASLD: regulation of glucose and lipid metabolism through PI3K/Akt and STING pathways

This study is aimed at exploring the therapeutic potential of berberine (BBR) in mitigating metabolic dysfunction-associated steatotic liver disease (MASLD) and at elucidating its mechanisms of action, with a focus on the modulation of glucose and lipid metabolism via the PI3K/Akt and STING signaling pathways. Male C57BL/6 J mice were fed a high-fat diet (HFD) to induce MASLD and subsequently treated with BBR or metformin. HepG2 cells were cultured in vitro, and palmitic acid (PA) was used to construct the cell model. Comprehensive analyses, including network pharmacology, transcriptome sequencing, and Western blotting, were conducted to identify critical pathways and molecular targets. Biochemical, histological, and molecular assays were performed to evaluate metabolic and inflammatory responses. BBR significantly attenuated HFD-induced hepatic steatosis, inflammation, and glucose intolerance. It effectively reduced lipid accumulation, enhanced insulin sensitivity, and modulated the expression of genes involved in lipid metabolism. Network pharmacology and transcriptome analysis highlighted the involvement of the PI3K/Akt and STING pathways. BBR activated PI3K/Akt signaling while suppressing the STING pathway, thereby reducing lipid accumulation in both in vivo and in vitro models. The inhibition of AKT negated the beneficial effects of BBR, underscoring the pivotal role of PI3K/Akt in regulating STING signaling. BBR ameliorates MASLD by activating the PI3K/Akt pathway and inhibiting the STING pathway, leading to improved glucose and lipid metabolism. These findings position BBR as a promising therapeutic candidate for the treatment of MASLD.

Viral Infection and Connexin Dysfunction in the Heart

PURPOSE OF REVIEW

Gap junctions, comprising connexin proteins, enable the direct intercellular electrical coupling of cardiomyocytes, and disruption of this process is arrhythmogenic. In addition, gap junctions effect metabolic coupling and of relevance to this review, propagate host antiviral immune responses. Accordingly, connexins have emerged as viral targets during infection. This review summarizes current knowledge regarding contributions of inflammation vs virally encoded factors in driving alterations to cardiac gap junction function.

RECENT FINDINGS

In addition to host immune-mediated effects on cardiac electrophysiology and gap junctions in myocarditis, there is now increasing appreciation for virally encoded factors targeting connexin function in acute/active infection. We now know diverse viral species have independently evolved to directly target connexin function during infection. Understanding both the direct and indirect effects of viral infection on cardiac gap junctions is critical to inform treatment strategies and development of novel therapeutics for acute infection as a distinct disease process from chronic myocarditis.

Cellular Discrepancy of Platinum Complexes in Interfering with Mitochondrial DNA

Mitochondria are associated with cellular energy metabolism, proliferation, and mode of death. Damage to mitochondrial DNA (mtDNA) greatly affects mitochondrial function by interfering with energy production and the signaling pathway. Monofunctional trinuclear platinum complex MTPC demonstrates different actions on the mtDNA of cancerous and normal cells. It severely impairs the integrity and function of mitochondria in the human lung cancer A549 cells, such as dissipating mitochondrial membrane potential, decreasing the copy number of mtDNA, interfering in nucleoid proteins and polymerase gamma gene, reducing adenosine triphosphate (ATP), and inducing mitophagy, whereas it barely affects the mtDNA of the human kidney 2 (HK-2) cells. Moreover, MTPC promotes the release of mtDNA into the cytosol and stimulates the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, thus showing the potential to trigger antitumor immunity. MTPC displays significant cytotoxicity against A549 cells, while it exhibits weak toxicity toward HK-2 cells, therefore displaying great advantage to overcome the lingering nephrotoxicity of platinum anticancer drugs. Discrepant effects of a metal complex on mitochondria of different cells mean that targeting mitochondria has special significance in cancer therapy.

DNA-RNA hybrids in inflammation: sources, immune response, and therapeutic implications

Cytoplasmic DNA-RNA hybrids are emerging as important immunogenic nucleic acids, that were previously underappreciated. DNA-RNA hybrids, formed during cellular processes like transcription and replication, or by exogenous pathogens, are recognized by pattern recognition receptors (PRRs), including cGAS, DDX41, and TLR9, which trigger immune responses. Post-translational modifications (PTMs) including ubiquitination, phosphorylation, acetylation, and palmitoylation regulate the activity of PRRs and downstream signaling molecules, fine-tuning the immune response. Targeting enzymes involved in DNA-RNA hybrid metabolism and PTMs regulation offers therapeutic potential for inflammatory diseases. Herein, we discuss the sources, immune response, and therapeutic implications of DNA-RNA hybrids in inflammation, highlighting the significance of DNA-RNA hybrids as potential targets for the treatment of inflammation.

Pharmacological inhibition of STING-mediated GPX4 autophagic degradation by 4-octyl itaconate ameliorates sepsis-induced acute kidney injury

The precise pathogenic mechanisms underlying sepsis-induced acute kidney injury (AKI) remain elusive. Emerging evidence suggests a link between tubular ferroptosis and the pathogenesis of AKI, though the regulatory pathways are not fully understood. Stimulator of interferon genes (STING), previously recognized as a pivotal mediator of innate immunity via DNA-sensing pathways, is increasingly associated with lipid peroxidation, a hallmark of ferroptosis, and 4-octyl itaconate (4-OI) has been shown to inhibit STING activation, exerting anti-inflammatory effects. This study investigates the protective mechanisms of 4-OI in sepsis-AKI. Following cecal ligation and puncture (CLP), inflammation, oxidative stress, and ferroptosis levels in kidney tissue increased. Both 4-OI and ferrostatin-1 (Fer-1) mitigated renal ferroptosis, exerting anti-inflammatory and antioxidant stress effects, and improved renal function. Consistently, in vitro experiments demonstrated that 4-OI reduced ferroptosis in human renal proximal tubule (HK-2) cells induced by lipopolysaccharide (LPS). Mechanistically, 4-OI suppressed LPS-induced activation of the STING pathway and reduced levels of inflammatory cytokines in a manner independent of NF-E2-related factor 2 (Nrf2). Additionally, 4-OI inhibited STING transcription through the activation of Nrf2. These dual actions effectively suppressed LPS-induced STING pathway activation, thereby inhibiting STING-mediated autophagic degradation of glutathione peroxidase 4 (GPX4), reducing reactive oxygen species (ROS) accumulation, and alleviating ferroptosis. In summary, 4-OI is a promising therapeutic candidate, functioning both as a STING inhibitor and a ferroptosis inhibitor, with potential applications in the treatment of sepsis.

Structural insight into the cGAS active site explains differences between therapeutically relevant species

Cyclic GMP-AMP synthase (cGAS) is an intracellular sensor of double-stranded DNA that triggers a pro-inflammatory response upon binding. The interest in cGAS as a drug discovery target has increased substantially over the past decade due to growing evidence linking its activation to numerous peripheral and neurological diseases. Here, we report the binding mode of previously described cGAS inhibitors while also uncovering the structural basis for the interspecies potency shifts within this chemotype. A single threonine to isoleucine substitution between human and mouse cGAS drives compound activity, as demonstrated by biochemical, cellular, and in vivo studies. Finally, we utilize a structurally enabled design approach to engineer a novel chemical inhibitor with excellent potency for both human and mouse enzymes by targeting key interactions within the enzyme active site. Overall, this work provides the framework for rational optimization of cGAS inhibitors and potential preclinical translational strategies.

Mitigation of the toxic effects of nitrite: Role and mechanism of isoleucine in mitigating mitochondrial DNA leakage-induced inflammation in grass carp (Ctenopharyngodon idella) under nitrite exposure

The physiological and growth processes of fish are closely associated with their surrounding environment. This study investigated the role and underlying mechanisms of isoleucine (Ile) in alleviating mitochondrial DNA (mtDNA) leakage-induced inflammation in grass carp under nitrite exposure. Grass carp were fed six experimental diets containing different Ile levels (0.00, 3.00, 6.00, 9.00, 12.00 and 15.00 g/kg) for 9 weeks, followed by a 96-hour nitrite exposure trial. Ile supplementation mitigated the deterioration of blood parameters including glutamic oxaloacetic transaminase (GOT), glutamic alanine transaminase (GPT), glucose, cortisol and lactate dehydrogenase (LDH) induced by nitrite exposure. Additionally, Ile enhanced its transport to the liver and mitochondria, as well as increased metabolism of Ile in mitochondria. Histological analyses revealed that Ile mitigated nitrite exposure-induced liver damage and mitochondrial cristae disruption. Furthermore, Ile preserved the mitochondrial cristae homeostasis by upregulating key proteins involved in mitochondrial structure maintenance, while inhibiting mtDNA leakage. Mechanistically, Ile attenuated mtDNA leakage-induced inflammation under nitrite exposure associated with the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-Stimulator of Interferon Genes (STING) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) pathways. These findings highlight the protective role of Ile in reducing inflammation triggered by environmental nitrite exposure, offering new insights into aquatic toxicology, and determined that Ile concentration of 11.13 g/kg diet could be optimal for mitigating nitrite-induced stress in grass carp, providing a theoretical basis for formulating anti- nitrite stress diets in aquaculture.

Identification of cytochrome P450 2E1 as a novel target in neuroinflammation and development of its inhibitor Q11 as a treatment strategy

Neuroinflammation is implicated in nearly all pathological processes of central nervous system (CNS) diseases. However, no medications specifically targeting neuroinflammation are clinically available, and conventional anti-inflammatory drugs exhibit limited efficacy. Here, we identified cytochrome P450 2E1 (CYP2E1) as a novel therapeutic target in neuroinflammation. Elevated CYP2E1 levels were observed in hippocampal tissues of mouse and rat neuroinflammation models, as well as in LPS-stimulated primary microglia. Genetic ablation of Cyp2e1 improved spatial learning and memory in neuroinflammatory rats and reduced pro-inflammatory cytokine levels in Cyp2e1-deficient microglia. Furthermore, Q11 (1-(4-methyl-5-thiazolyl) ethanone), a novel CYP2E1 inhibitor developed and synthesized in our laboratory, effectively ameliorated Alzheimer's disease-related spatial learning and memory functions and depression-related anxiety-like behaviors in mice/rats. Mechanistically, Q11 attenuated microglial activation, neuronal damage, oxidative stress, and neuroinflammation by suppressing the PI3K/Akt, STAT1/3, and NF-κB signaling pathways. These findings establish CYP2E1 as a druggable target for neuroinflammation and propose Q11 as a promising candidate for treating neuroinflammation-related diseases.

Role of long non-coding RNAs in the regulation of ferroptosis in tumors

Normal cells begin to grow indefinitely and immortalize to form tumor cells after an external stimulus resulting in a genetic mutation. Effective killing of tumor cells is the basis of various cancer therapies. Ferroptosis is a class of cell death types dependent on iron and cellular lipid peroxidation. Tumors themselves are iron-dependent, and conventional radiotherapy also sensitizes cancer cells to ferroptosis. Increasing the sensitivity of tumor cells to ferroptosis may be a potential therapeutic strategy to overcome the resistance mechanisms of conventional cancer therapy. Long noncoding RNAs (LncRNAs) are a class of transcripts more than 200 nucleotides in length that regulate gene expression at multiple levels and are involved in biological processes such as cell differentiation, cell cycle arrest, and maintenance of tumor stemness. Recent studies have found that lncRNAs regulate ferroptosis of tumor cells through multiple mechanisms and may influence or ameliorate tumor resistance to chemotherapeutic agents. With the continuous maturation of nanomaterials technology, it may provide new means for cancer treatment by regulating the levels of ferroptosis-related lncRNAs inside tumors as well as increasing the levels of Fe2+ and ROS inside tumors. In this paper, we systematically introduce the regulatory mechanism of lncRNAs in ferroptosis, the role of ferroptosis in tumor immunotherapy and the application of lncRNAs combined with ferroptosis in nanomaterials, which provides new perspectives for tumor therapy.

ArfGAP2 promotes STING proton channel activity, cytokine transit, and autoinflammation

Stimulator of interferon genes (STING) transmits signals downstream of the cytosolic DNA sensor cyclic guanosine monophosphate-AMP synthase (cGAS), leading to transcriptional upregulation of cytokines. However, components of the STING signaling pathway, such as IRF3 and IFNAR1, are not essential for autoinflammatory disease in STING gain-of-function (STING-associated vasculopathy with onset in infancy [SAVI]) mice. Recent discoveries revealed that STING also functions as a proton channel that deacidifies the Golgi apparatus. Because pH impacts Golgi enzyme activity, protein maturation, and trafficking, we hypothesized that STING proton channel activity influences multiple Golgi functions. Here, we show that STING-mediated proton efflux non-transcriptionally regulates Golgi trafficking of protein cargos. This process requires the Golgi-associated protein ArfGAP2, a cell-type-specific dual regulator of STING-mediated proton efflux and signaling. Deletion of ArfGAP2 in hematopoietic and endothelial cells markedly reduces STING-mediated cytokine and chemokine secretion, immune cell activation, and autoinflammatory pathology in SAVI mice. Thus, ArfGAP2 facilitates STING-mediated signaling and cytokine release in hematopoietic cells, significantly contributing to autoinflammatory disease pathogenesis.

Immp2l gene knockout induces granulosa cell senescence by activation of cGAS-STING pathway via TFAM-mediated mtDNA leakage

Granulosa cell-produced inflammatory factors may be key contributors to ovarian dysfunction, and Immp2l deficiency accelerates ovarian aging via granulosa cell senescence; however, the role of inflammation in granulosa cell senescence is largely unknown. Therefore, in this study, cGAS-STING-mediated inflammation was explored in Immp2l deficiency-induced granulosa cell senescence. Immp2l deficiency led to senescence-associated secretory phenotype (SASP) and granulosa cell senescence. Immp2l knockout caused mitochondrial dysfunction and mitochondrial DNA (mtDNA) leakage into the cytoplasm. The cytoplasmic mtDNA was recognized by the DNA-sensing molecule cGAS-STING, which activates cGAS-STING and key downstream interferon-stimulated genes (ISGs) and then promotes the secretion of proinflammatory factors, leading to SASP in senescent granulosa cells. Interestingly, the mitochondrial inner membrane pore protein (Cyclophilin D40) CyPD40 and the outer membrane pore protein voltage-dependent-anion channel 1 (VDAC1) were markedly increased in senescent granulosa cells, accompanied by significantly increased expression of the mtDNA stability protein mitochondrial transcription factor A (TFAM). Downregulation of TFAM with siRNA in senescent granulosa cells improved mitochondrial function, significantly decreased mtDNA in the cytoplasm, inhibited the cGAS-STING pathway and markedly decreased CyPD40 and VDAC1 protein levels in TFAM-treated senescent granulosa cells. The SASP phenotype was also alleviated. In addition, senescent granulosa cells were treated with procyanidin B2 (PCB2), which has anti-inflammatory effects, and the TFAM-mediated mtDNA-cGAS-STING pathway was inhibited, accompanied by a markedly reduced SASP phenotype and granulosa cell senescence. In conclusion, Immp2l gene knockout induced granulosa cell senescence by activation of the cGAS-STING pathway via TFAM-mediated mtDNA leakage into the cytoplasm through the CyPD40 and the VDAC1.

Cytosolic nucleic acid sensing as driver of critical illness: mechanisms and advances in therapy

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

Chromosomal Instability Is Associated with cGAS-STING Activation in EGFR-TKI Refractory Non-Small-Cell Lung Cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are standard therapies for EGFR-mutated non-small-cell lung cancer (NSCLC); however, their efficacy is inconsistent. Secondary mutations in the EGFR or other genes that lead to resistance have been identified, but resistance mechanisms have not been fully identified. Chromosomal instability (CIN) is a hallmark of cancer and results in genetic diversity. In this study, we demonstrated by transcriptomic analysis that CIN activates the cGAS-STING signaling pathway, which leads to EGFR-TKI refractoriness in a subset of EGFR-mutated NSCLC patients. Furthermore, EGFR-mutated H1975dnMCAK cells, which frequently underwent chromosomal mis-segregation, demonstrated refractoriness to the EGFR-TKI osimertinib compared to control cells. Second, H1975dnMCAK cells exhibited activation of cGAS-STING signaling and its downstream signaling, including tumor-promoting cytokine IL-6. Finally, chromosomally unstable EGFR-mutated NSCLC exhibited enhanced epithelial-mesenchymal transition (EMT). Blockade of cGAS-STING-TBK1 signaling reversed EMT, resulting in restored susceptibility to EGFR-TKIs in vitro and in vivo. These results suggest that CIN may lead to the activation of cGAS-STING signaling in some EGFR-mutated NSCLC, resulting in EMT-associated EGFR-TKI resistance.

Activated NETosis of bone marrow neutrophils up-regulates macrophage osteoclastogenesis via cGAS-STING/AKT2 pathway to promote osteoporosis

Bone marrow (BM) of postmenopausal osteoporosis has been found highly inflammatory, resulting from dysregulated immune cells induced by both estrogen efficiency and body aging. NETosis of neutrophils has been found aberrantly activated in age-related chronic inflammation, while their role in postmenopausal osteoporosis remains unclear. Here we found NETosis of BM neutrophils of OVX (ovariectomy) mice was significantly activated, and we verified NETs released by neutrophils induced M1 polarization and osteoclastogenesis of RAW264.7 macrophages. Further, we demonstrated effects of NETs on osteoclastogenesis was mediated by cGAS-STING/AKT2 pathway. Finally, we found in vivo NETs-clearance through GSK484 significantly inhibited osteoclastogenesis and attenuated osteoporosis of OVX mice. Our study highlights the role of neutrophil NETosis in activating osteoclastogenesis and bone resorption of postmenopausal osteoporosis, thereby providing novel targets for bone loss treatment.

STING coordinates resolution of inflammation during wound repair by modulating macrophage trafficking through STAT3

Efficient cutaneous wound healing requires a coordinated transition between inflammatory phases mediated by dynamic changes in leukocyte subset populations. Here, we identify STING as a key innate immune mediator governing timely resolution of inflammation by regulating macrophage dynamics during skin repair. Using a mouse model, we show STING deficiency caused delayed wound closure associated with abnormal persistence of TNF-α+ leukocytes. This resulted from the impaired macrophage recruitment. STING controlled the trafficking of bone marrow myeloid cells into blood and wounds, intrinsically enhancing macrophage migratory capacity through STAT3 activation. Specifically, STING modulated the production of monocyte chemokines and their receptors CCR2/CCR5 to enable efficient egress and wound infiltration. Consequently, disrupted systemic and local STING-STAT3-chemokine signaling combine to delay macrophage influx. This study elucidates STING as a critical rheostat tuning macrophage responses through STAT3 to orchestrate inflammatory resolution necessary for efficient wound healing. Our findings have broad implications for targeting STING therapeutically in both regenerative medicine and inflammatory disease contexts.

Discovery of a Novel CRBN-Recruiting cGAS PROTAC Degrader for the Treatment of Ulcerative Colitis

Cyclic GMP-AMP synthase (cGAS), a critical cytosolic DNA sensor initiating innate immune responses in the presence of cytosolic DNA, is increasingly recognized as a promising therapeutic target for ulcerative colitis (UC). Here, we reported the design, synthesis, structure-activity relationship exploration and biological evaluation of a novel class of CRBN-recruiting cGAS-targeting PROTAC degraders. Among them, TH35 exhibited the most favorable degradation profile, achieving potent and selective degradation of cGAS, and markedly attenuated dsDNA-induced activation of cGAS signaling in both human and murine cells, with minimal cytotoxic effects. In vivo, TH35 demonstrated superior therapeutic efficacy in a dextran sulfate sodium (DSS)-induced mouse model of UC compared to the corresponding cGAS inhibitor, while also displaying acceptable pharmacokinetic properties. Collectively, TH35 as the first CRBN-recruiting cGAS PROTAC holds promise for augmenting anti-inflammatory responses and offers a new avenue for treating cGAS-driven inflammatory diseases.

Orally Bioavailable and Site-Selective Covalent STING Inhibitor Derived from a Macrocyclic Marine Diterpenoid

Pharmacological inhibition of the cGAS-STING-controlled innate immune pathway is an emerging therapeutic strategy for a myriad of inflammatory diseases. Here, we report GHN105 as an orally bioavailable covalent STING inhibitor. Late-stage diversification of the briarane-type diterpenoid excavatolide B allowed the installation of solubility-enhancing functional groups while enhancing its activity as a covalent STING inhibitor against multiple human STING variants, including the S154 variant responsible for a genetic autoimmune disease. Selectively engaging the membrane-proximal Cys91 residue of STING, GHN105 dose-dependently inhibited cGAS-STING signaling and type I interferon responses in cells and in vivo. Moreover, orally administered GHN105 exhibited on-target engagement in vivo and markedly reversed key pathological features in a delayed treatment of the acute colitis mouse model. Our study provided proof of concept that the synthetic briarane analog GHN105 serves as a safe, site-selective, and orally active covalent STING inhibitor and devises a regimen that allows long-term systemic administration.

YAP/TAZ-mediated nuclear membrane rupture in promoting senescence of skeletal muscle associated with COPD

Patients with chronic obstructive pulmonary disease (COPD) often develop complications associated with sarcopenia; however, the underlying mechanisms remain unclear. Through a combination of in vitro and in vivo experiments, as well as bioinformatics analysis, our study identified YAP/TAZ as a key regulator of the aging phenotype in the skeletal muscle of COPD patients. In skeletal muscle affected by cigarette smoke-induced COPD, we observed significant reductions in YAP/TAZ levels, alongside markers indicative of skeletal muscle aging and dysfunction. Notably, overexpression of YAP/TAZ significantly improved these conditions. Our results suggest a novel mechanism whereby the maintenance of YAP/TAZ activity interacts with ACTR2 to preserve nuclear membrane integrity and reduce cytoplasmic dsDNA levels, thereby attenuating STING activation and cellular senescence. Additionally, we found that YAP is involved in the transcriptional regulation of the ACTR2 promoter region. Overall, preserving YAP/TAZ activity may help prevent skeletal muscle aging associated with COPD, representing a new strategy for intervening in COPD-related sarcopenia.

Regulation and Function of the cGAS-STING Pathway: Mechanisms, Post-Translational Modifications, and Therapeutic Potential in Immunotherapy

Autoimmune diseases arise when the immune system attacks healthy tissues, losing tolerance for self-tissues. Normally, the immune system recognizes and defends against pathogens like bacteria and viruses. The cGAS-STING pathway, activated by pattern-recognition receptors (PRRs), plays a key role in autoimmune responses. The cGAS protein senses pathogenic DNA and synthesizes cGAMP, which induces conformational changes in STING, activating kinases IKK and TBK1 and leading to the expression of interferon genes or inflammatory mediators. This pathway is crucial in immunotherapy, activating innate immunity, enhancing antigen presentation, modulating the tumor microenvironment, and integrating into therapeutic strategies. Modulation strategies include small molecule inhibitors, oligonucleotide therapies, protein and antibody therapies, genetic and epigenetic regulation, cytokine and metabolite modulation, and nanoscale delivery systems. Post-translational modifications (PTMs) of the cGAS-STING pathway, such as phosphorylation, acetylation, ubiquitination, methylation, palmitoylation, and glycosylation, fine-tune immune responses by regulating protein activity, stability, localization, and interactions. These modifications are interconnected and collectively influence pathway functionality. We summarize the functions of cGAS-STING and its PTMs in immune and non-immune cells across various diseases, and explore potential clinical applications.

Reprogramming the Tolerogenic Immune Response Against Pancreatic Cancer Metastases by Lipid Nanoparticles Delivering a STING Agonist Plus Mutant KRAS mRNA

We demonstrate reprogramming of the tolerogenic immune environment in the liver for mounting an effective immune response against often-fatal pancreatic cancer metastases. This was achieved by engineering a lipid nanoparticle (LNP) to deliver mRNA encoding the KRAS G12D neoantigenic epitope along with cGAMP, a dinucleotide agonist of the stimulator of the interferon genes (STING) pathway, capable of activating a type I interferon response. cGAMP/mKRAS/LNP were synthesized by a microfluidics approach involving nanoprecipitation of mRNA and cGAMP by an ionizable lipid, MC3. Controls included nanoparticles delivering individual components or a wild-type RAS sequence. The dual delivery carrier successfully activated the type I interferon pathway in vitro as well as in vivo, with reprogramming of costimulatory receptor (CD80 and CD86) and MHC-I expression on liver antigen-presenting cells (APC). This allowed the generation of IFN-γ producing cytotoxic T cells, capable of mounting an effective immune response in the metastatic KRAS pancreatic cancer (KPC) mouse model. Noteworthy, intravenous injection of cGAMP/mKRAS/LNP suppressed metastatic growth significantly and prolonged animal survival, both prophylactically and during treatment of established metastases. The protective immune response was mediated by the generation of perforin-releasing CD8+ cytotoxic T cells, engaged in pancreatic cancer cell killing. Importantly, the immune response could also be adoptively transferred by injecting splenocytes (containing memory T cells) from treated into nontreated recipient mice. This study demonstrates that reprogramming the immune-protective niche for metastatic pancreatic cancer can be achieved by the delivery of a STING agonist and mutant KRAS mRNA via ionizable LNPs, offering both prophylactic and therapeutic advantages.

Metal-Phenolic Network Hydrogel Vaccine Platform for Enhanced Humoral Immunity against Lethal Rabies Virus

Rabies, caused by rabies virus (RABV), is a zoonotic disease with a high mortality rate that has attracted global attention with the goal of eradication by 2030. However, rabies can only be prevented by appropriate and multiple vaccinations, which impede widespread vaccination in developing countries due to its high expenditure. Designing single-dose vaccines is a pressing challenge in the prevention of rabies and other infectious diseases. Herein, a metal-phenolic network (MPN)-based hydrogel vaccine (designated as CGMR) was developed to stimulate potent humoral immunity against RABV infection by a single immunization, resulting in 4.3-fold and 1.8-fold enhancements of virus-neutralizing antibody compared with that induced by inactivated RABV and alum adjuvant. The CGMR, cross-linked by phenol-modified chitosan with manganese ion, could prolong residence time by confining the antigen to the network of hydrogel, acting as a "hydrogel antigen depot". It also stimulated the activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon gene (STING) pathway, facilitating dendritic cell maturation and antigen presentation. The vaccine formulation recruited immunocytes and activated the germinal center, enhancing and sustaining humoral immune responses against the virulent RABV challenge. Collectively, this injectable manganese-based hydrogel vaccine provides a universal and ideal avenue for rabies and other infectious diseases.

Targeting GOLPH3L improves glioblastoma radiotherapy by regulating STING-NLRP3-mediated tumor immune microenvironment reprogramming

Radiotherapy (RT) has been the standard-of-care treatment for patients with glioblastoma (GBM); however, the clinical effectiveness is hindered by therapeutic resistance. Here, we demonstrated that the tumor immune microenvironment (TIME) exhibited immunosuppressive properties and high expression of Golgi phosphoprotein 3 like (GOLPH3L) in RT-resistant GBM. Our study showed that GOLPH3L interacted with stimulator of interferon genes (STING) at the aspartic acid residue 184 in Golgi after RT, leading to coat protein complex II-mediated retrograde transport of STING from Golgi to endoplasmic reticulum. This suppressed the STING-NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated pyroptosis, resulting in suppressive TIME, driving GBM resistance to RT. Genetic GOLPH3L ablation in RT-resistant GBM cells augmented antitumor immunity and overcame tumor resistance to RT. Moreover, we have identified a small molecular inhibitor of GOLPH3L, vitamin B5 calcium (VB5), which improved the therapeutic efficacy of RT and immune checkpoint blockade by inducing a robust antitumor immune response in mouse models. Clinically, patients with GBM treated with VB5 exhibited improved responses to RT. Thus, reprogramming the TIME by targeting GOLPH3L may offer a potential opportunity to improve RT in GBM.

PARP inhibitor radiosensitization enhances anti-PD-L1 immunotherapy through stabilizing chemokine mRNA in small cell lung cancer

Immunotherapy (IO) is an effective treatment for various cancers; however, the benefits are modest for small cell lung cancer (SCLC). The poor response of SCLC to anti-PD-1/PD-L1 IO is due in part to the lack of cytotoxic T cells because of limited chemokine expression from SCLC tumors. Immunogenic radiosensitizers that enhance chemokine expression may be a promising strategy forward. Here, we show that the PARP inhibitors (PARPi), including olaparib, talazoparib and veliparib, in combination with radiotherapy (RT) enhance the immune activation and anti-tumor efficacy in SCLC cell lines, patient-derived xenograft (PDX) and syngeneic mouse models. The effect is further enhanced by continued delivery of adjuvant PARPi. The combination treatment (PARPi with RT) activates the cGAS-STING pathway and increases the mRNA levels of the T cell chemo-attractants CCL5 and CXCL10. In addition to upregulation of transcription, the combination treatment increases chemokine CXCL10 protein levels via stabilization of CXCL10 mRNA in an EIF4E2-dependent manner. The incorporation of anti-PD-L1 IO into the PARPi with RT combination therapy further improves the anti-tumor efficacy by increasing T cell infiltration and function. This study thus provides a proof of principle for the combination of PARP inhibitors, RT and anti-PD-L1 IO as a treatment strategy for SCLC.

cGAMP promotes inner blood-retinal barrier breakdown through P2RX7-mediated transportation into microglia

BACKGROUND

Impairment of the inner blood-retinal barrier (iBRB) leads to various blinding diseases including diabetic retinopathy (DR). The cGAS-STING pathway has emerged as a driving force of cardiovascular destruction, but its impact on the neurovascular system is unclear. Here, we show that cGAMP, the endogenous STING agonist, causes iBRB breakdown and retinal degeneration thorough P2RX7-mediated transport into microglia.

METHODS

Extracellular cGAMP and STING pathway were determined in tissue samples from patients with proliferative DR (PDR) and db/db diabetic mice. Histological, molecular, bioinformatic and behavioral analysis accessed effects of cGAMP on iBRB. Single-cell RNA sequencing identified the primary retinal cell type responsive to cGAMP. Specific inhibitors and P2RX7-deficienct mice were used to evaluate P2RX7' role as a cGAMP transporter. The therapeutic effects of P2RX7 inhibitor were tested in db/db mice.

RESULTS

cGAMP was detected in the aqueous humor of patients with PDR and elevated in the vitreous humor with STING activation in db/db mouse retinas. cGAMP administration led to STING-dependent iBRB breakdown and neuron degeneration. Microglia were the primary cells responding to cGAMP, essential for cGAMP-induced iBRB breakdown and visual impairment. The ATP-gated P2RX7 transporter was required for cGAMP import and STING activation in retinal microglia. Contrary to previous thought that mouse P2RX7 nonselectively transports cGAMP only at extremely high ATP concentrations, human P2RX7 directly binds to cGAMP and activates STING under physiological conditions. Clinically, cGAMP-induced microglial signature was recapitulated in fibrovascular membranes from patients with PDR, with P2RX7 being predominantly expressed in microglia. Inhibiting P2RX7 reduced cGAMP-STING activation, protected iBRB and improved neuron survival in diabetic mouse retinas.

CONCLUSIONS

Our study reveals a mechanism for cGAMP-mediated iBRB breakdown and suggests that targeting microglia and P2RX7 may mitigate the deleterious effects of STING activation in retinal diseases linked to iBRB impairment.

Immune checkpoint inhibitors mediate myocarditis by promoting macrophage polarization via cGAS/STING pathway

BACKGROUND

Immune checkpoint inhibitors has opened up new avenues for cancer treatment, but serious cardiac injury has emerged in their use. A large number of data have shown that abnormal activation of cytosolic DNA-sensing cyclic GMP-AMP synthase-interferon gene activator pathway is closely related to cardiovascular inflammation and autoimmune diseases. However, the pathophysiological function of the cGAS-STING cascade in myocarditis induced by Immune checkpoint inhibitors is unclear.

METHODS

In order to establish a Immune checkpoint inhibitors-associated myocarditis model, BALB/c mice were injected with mouse cardiac troponin I peptide and anti-mouse programmed death 1 antibody. Echocardiography and HE staining were then performed to assess cardiac function and inflammation. Macrophages and damaged DNA in mouse heart tissue were detected by immunofluorescence. The mitochondrial damage of macrophages was observed by electron microscope. In vitro experiments, RAW264.7 was used to detect macrophage polarization after anti-PD-1 antibody induction and STING inhibition by qPCR and flow cytometry. Mitochondrial damage was detected by immunofluorescence, and activation of the cGAS-STING signaling pathway was evaluated by protein imprinting analysis.

RESULTS

In the Immune checkpoint inhibitors-associated myocarditis model, DNA damage was found to activate the cGAS-STING pathway and macrophages were polarized to M1 type. In vitro experiments, anti-PD-1 antibody activate the cGAS-STING pathway through the release of damaged DNA from macrophage mitochondrial damage, causing macrophage polarization into a pro-inflammatory phenotype leading to autoimmune myocarditis.

CONCLUSION

Our results suggested that the cGAS-STING pathway played a key role in myocarditis caused by immune checkpoint inhibitors. It provided a new possibility for Immune checkpoint inhibitors to be widely used in clinic.

Dual functional nanoplatforms potentiate osteosarcoma immunotherapy via microenvironment modulation

Osteosarcoma (OS), a highly aggressive bone tumor, presents significant challenges in terms of effective treatment. We identified that cellular autophagy was impaired within OS by comparing clinical OS samples through bioinformatic analyses and further validated the inhibition of mitochondrial autophagy in OS at the transcriptomic level. Based on this finding, we investigated the therapeutic potential of a dual functional metal nanoplatform (MnSx) to facilitate a transition from the protective effect of low-level autophagy in OS to the killing effect of high-level autophagy in OS. MnSx facilitated intracellular H2S generation via endocytosis, leading to the S-sulfhydration of ubiquitin-specific peptidase 8 (USP8) and subsequent promotion of mitochondrial autophagy in vitro. Additionally, MnSx activated the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway, further enhancing the cellular autophagic response and accelerating tumor cell death. Moreover, it was demonstrated in vivo that MnSx, on the one hand, mediated the activation of tumor autophagy by USP8 via intracellular H2S, while Mn2+ promoted the maturation of dendritic cells, activated cytotoxic T lymphocytes and contributed to tumor eradication. Such tumor killing could be suppressed by the autophagy inhibitor chloroquine. Importantly, synergistic combination therapy with immune checkpoint inhibitors showed promise for achieving complete remission of OS. This study highlights the potential of MnSx as a dual-functional therapeutic platform for OS treatment and offers novel directions for future research in this field.

Facile integration of a binary nano-prodrug with αPD-L1 as a translatable technology for potent immunotherapy of TNBC

Immune checkpoint blockers (ICBs)-based immunotherapy is a favorable approach for efficient triple-negative breast cancer (TNBC) treatment. However, the therapeutic efficacy of ICBs is greatly compromised by immunosuppressive tumor microenvironments (TMEs) and low expression levels of programmed cell death ligand-1 (PD-L1). Herein, we constructed an amphiphilic prodrug by linking a hydrophobic STING agonist, MSA-2 and a hydrophilic chemotherapeutic drug, gemcitabine (GEM) via an ester bond, which can self-assemble into GEM-MSA-2 (G-M) nanoparticles (NPs) with a tumor growth inhibition (TGI) value of 87.1 % in a murine 4T1 transplantation tumor model. Notably, the immunogenic cell death (ICD)-triggering effect of GEM together with the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway activation properties of MSA-2 enables efficient infiltration of non-exhausting T cells and repolarization of macrophages from M2 to M1 types in the tumor microenvironment for transforming a cold tumor to a hot one. Most importantly, G-M NPs treatment increases the PD-L1 expression levels, thus providing a unique opportunity for further integration with anti-PD-L1 monoclonal antibody (αPD-L1) for eliciting stronger immunity that ultimately leads to a TGI value of 98.0 % in the primary tumor and significantly protects against distal and disseminated tumor rechallenge. Overall, this study presents a minimalist nano-prodrug combined with αPD-L1 as a simple yet robust translatable nanotechnology for potent chemo-immunotherapy of TNBC. STATEMENT OF SIGNIFICANCE: Enhancing the therapeutic efficacy of αPD-L1 for tumor immunotherapy via a translatable technology remains a challenge. We report herein facile integration of a binary nano-prodrug with αPD-L1 for potent immunotherapy of TNBC. An amphiphilic prodrug is constructed by linking a hydrophobic STING agonist, MSA-2 and a hydrophilic chemotherapeutic drug, gemcitabine (GEM) via an ester bond. The resulting self-assembled GEM-MSA-2 (G-M) nanoparticles (NPs) show a tumor growth inhibition (TGI) value of 87.1 % in a murine 4T1 transplantation tumor model. Besides the induced immunogenic cell death (ICD) and activated cGAS-STING pathway, G-M NPs increase the PD-L1 expression levels, providing a unique opportunity for further integration with αPD-L1 to elicit stronger immunity that ultimately leads to a TGI value of 98.0 % in the primary tumor and significantly protects against distal and disseminated tumor rechallenge.

STING in cancer immunoediting: Modeling tumor-immune dynamics throughout cancer development

Cancer immunoediting is a dynamic process of tumor-immune system interaction that plays a critical role in cancer development and progression. Recent studies have highlighted the importance of innate signaling pathways possessed by both cancer cells and immune cells in this process. The STING molecule, a pivotal innate immune signaling molecule, mediates DNA-triggered immune responses in both cancer cells and immune cells, modulating the anti-tumor immune response and shaping the efficacy of immunotherapy. Emerging evidence has shown that the activation of STING signaling has dual opposing effects in cancer progression, simultaneously provoking and restricting anti-tumor immunity, and participating in every phase of cancer immunoediting, including immune elimination, equilibrium, and escape. In this review, we elucidate the roles of STING in the process of cancer immunoediting and discuss the dichotomous effects of STING agonists in the cancer immunotherapy response or resistance. A profound understanding of the sophisticated roles of STING signaling pathway in cancer immunoediting would potentially inspire the development of novel cancer therapeutic approaches and overcome the undesirable protumor effects of STING activation.

STING-dependent induction of neutrophilic asthma exacerbation in response to house dust mite

BACKGROUND

Severe refractory, neutrophilic asthma remains an unsolved clinical problem. STING agonists induce a neutrophilic response in the airways, suggesting that STING activation may contribute to the triggering of neutrophilic exacerbations. We aim to determine whether STING-induced neutrophilic lung inflammation mimics severe asthma.

METHODS

We developed new models of neutrophilic lung inflammation induced by house dust mite (HDM) plus STING agonists diamidobenzimidazole (diABZI) or cGAMP in wild-type, and conditional-STING-deficient mice. We measured DNA damage, cell death, NETs, cGAS/STING pathway activation by immunoblots, N1/N2 balance by flow cytometry, lung function by plethysmography, and Th1/Th2 cytokines by multiplex. We evaluated diABZI effects on human airway epithelial cells from healthy or patients with asthma, and validated the results by transcriptomic analyses of rhinovirus infected healthy controls vs patients with asthma.

RESULTS

DiABZI administration during HDM challenge increased airway hyperresponsiveness, neutrophil recruitment with prominent NOS2+ARG1- type 1 neutrophils, protein extravasation, cell death by PANoptosis, NETs formation, extracellular dsDNA release, DNA sensors activation, IFNγ, IL-6 and CXCL10 release. Functionally, STING agonists exacerbated airway hyperresponsiveness. DiABZI caused DNA and epithelial barrier damage, STING pathway activation in human airway epithelial cells exposed to HDM, in line with DNA-sensing and PANoptosis pathways upregulation and tight-junction downregulation induced by rhinovirus challenge in patients with asthma.

CONCLUSIONS

Our study identifies that triggering STING in the context of asthma induces cell death by PANoptosis, fueling the flame of inflammation through a mixed Th1/Th2 immune response recapitulating the features of severe asthma with a prognostic signature of type 1 neutrophils.

To cleave or not and how? The DNA exonucleases and endonucleases in immunity

DNA exonucleases and endonucleases are key executors of the genome during many physiological processes. They generate double-stranded DNA by cleaving damaged endogenous or exogenous DNA, triggering the activation of the innate immune pathways such as cGAS-STING-IFN, and enabling the body to produce anti-viral or anti-tumor immune responses. This is of great significance for maintaining the stability of the genome and improving the therapeutic efficacy of tumors. In addition, genomic instability caused by exonuclease mutations contributes to the development of various autoimmune diseases. This review summarizes the DNA exonucleases and endonucleases which have critical functions in immunity and associated diseases.