Role of the cGAS-STING pathway in systemic and organ-specific diseases

Comparative analysis of N/TERT-1 and N/TERT-2G keratinocyte responses to oxidative stress and immune challenges

The responses of N/TERT-1 and N/TERT-2G keratinocyte cell lines to oxidative stress and immune challenges were investigated to assess their suitability for dermatological testing. The cell lines were exposed to various stimuli, including PAMPs, DAMPs, H₂O₂, and menadione, to assess cytokine production, oxidative stress markers, cell viability, apoptosis, and membrane integrity. IL-1α, IL-6, IL-8, TNF-α, and TGF-β levels significantly increased in N/TERT-1 cells following exposure to LPS, while N/TERT-2G cells remained unaffected. Both cell lines showed increased production of IL-1α, IL-1β, TNF-α, IL-6, and IL-8 in response to dsDNA and LMW and HMW Poly I:C, although TGF-β significantly decreased only in N/TERT-1 cells. In response to H₂O₂, a dose-dependent increase in cytokine levels was observed in N/TERT-2G, whereas N/TERT-1 did not exhibit a clear dose-dependent response. Markers of oxidative stress, including SOD and GSH, displayed similar patterns in both cell lines, with N/TERT-2G showing slightly higher sensitivity. Lipid peroxidation and mitochondrial membrane potential fluctuations were more pronounced in N/TERT-2G, suggesting greater oxidative stress sensitivity. The baseline GSH levels were higher in N/TERT-1 cells, which may contribute towards the enhanced resilience to oxidative stress. Despite decreased viability in MTT assays following H₂O₂ exposure, the lack of significant changes in cleaved Caspase-3 levels indicated that apoptosis was not the primary mechanism of cell death. These findings highlight the distinct characteristics of N/TERT-1 and N/TERT-2G cells, with N/TERT-1 showing higher baseline resilience to oxidative stress and N/TERT-2G displaying greater sensitivity, particularly to H₂O₂. The study underscores the importance of selecting the appropriate cell line for specific research applications in skin biology and disease modelling, considering the differences in their responses to oxidative and immune challenges.

Conjugated STING agonists

An innate immune system is the first line of defense and prevents the host from infection and attacks the invading pathogens. Stimulator of interferon genes (STING) plays a vital role in the innate immune system. STING activation by STING agonists leads to phosphorylation of TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3) with the release of type I interferons and proinflammatory cytokines, further promoting the adaptive immune response and activating T cells by increased antigen presentation. Natural STING agonist cyclic dinucleotides (CDNs) encounter many defects such as high polarity by negative charges, low stability and circulative half-life, off-target systemic toxicity, and low response efficacy in clinical trials. To overcome these challenges, massive efforts have addressed chemical modifications of CDNs, development of non-CDN STING agonists, and delivery of these STING agonists either by conjugation or liposomes/nanoparticles. Considering there have been a great number of reports regarding nanosystem-aided delivery, here, we examine the development of STING agonists, especially for non-CDNs and their delivery specifically by conjugation strategy, with a focus on the STING agonists in clinical trials and current challenges of their potential in cancer immunotherapy.

Design, synthesis, and activity evaluation of novel STING inhibitors based on C170 and H151

Stimulating the STING signaling pathway for immune system activation is considered a promising strategy for cancer treatment. However, activating the STING pathway can lead to adverse effects, as aberrant activation or specific mutations in STING may result in autoimmune and inflammatory diseases. Therefore, the development of STING inhibitors is equally important. In this study, we first introduced hydroxyl groups into the STING inhibitors C170 and H151, creating functional sites for further modification. Then the introduction of various substituents resulted in the identification of more potent inhibitors, Y2 and HY2, which effectively suppressed the activation of the STING pathway in THP1 and RAW264.7 cells. Compounds Y2 and HY2 demonstrated potent anti-inflammatory effects in mice cisplatin-induced acute kidney injury models by inhibiting the STING pathway. Collectively, Y2 and HY2 warrant further investigation as novel anti-inflammatory agents.

Saturated fatty acid-induced neutrophil extracellular traps contribute to exacerbation and biologic therapy resistance in obesity-related psoriasis

Psoriasis patients who are obese tend to have serious clinical manifestations and poor responses to various biological agents in most cases. However, the mechanisms by which obesity exacerbates psoriasis remain enigmatic. In this study, we found that the abundance of systemic and localized cutaneous neutrophil extracellular traps (NETs) associated with the obesity-induced aggravation of psoriasis was positively correlated with disease severity and that the inhibition of NETs alleviated psoriatic dermatitis in obese mice. Mechanistically, we found that changes in fatty acid composition in obese subjects resulted in the deposition of saturated fatty acids (SFAs), which promoted the release of NETs via the TLR4-MD2/ROS signaling pathway. We further revealed that NETs potentiate IL-17 inflammation, especially γδT17-mediated immune responses, in obesity-exacerbated psoriasis patients. Moreover, SFAs induced a decreased response to anti-IL17A treatment in psoriasis-like mice, whereas the inhibition of NETs improved the beneficial effects of anti-IL17A in psoriasis-like mice with lipid metabolism disorders. Our findings collectively suggest that SFA-induced NETs play a critical role in the exacerbation of obesity-related psoriasis and provide potential new strategies for the clinical treatment of refractory psoriasis patients with lipid metabolism disorders.

Inhibiting fatty acid-binding protein 4 reverses inflammation and apoptosis in wasp sting-induced acute kidney injury

Fatty acid-binding protein 4 (FABP4) has been implicated in the pathogenesis of several forms of acute kidney injury (AKI), including rhabdomyolysis, ischemia/reperfusion, sepsis, and cisplatin-induced AKI. However, whether FABP4 inhibition confers a renoprotective effect in wasp sting-induced AKI remains unclear. Therefore, in this study, we investigated the role of FABP4 in wasp sting-induced AKI in vivo and in vitro. We assessed renal dysfunction, mitochondrial injury, cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway-mediated inflammation, and apoptosis. FABP4 expression was significantly higher in wasp sting-induced models of AKI than in the control groups, and pharmacological inhibition of FABP4 attenuated renal dysfunction and tubular injury. Wasp sting-induced AKI was associated with mitochondrial damage induced by excessive mitochondrial fission, which was effectively mitigated by FABP4 inhibition. The FABP4 inhibitor reduced the release of mitochondrial DNA (mtDNA) and cytochrome c (Cyt-c) from damaged mitochondria. cGAS-STING activation induced by mtDNA was downregulated by FABP4 inhibition. Subsequently, inflammation and apoptosis in wasp sting-induced AKI were significantly alleviated, as evidenced by decreased levels of inflammatory mediators and apoptosis-related proteins. In conclusion, FABP4 was found to play a key role in the occurrence and progression of wasp sting-induced AKI.

Inflammatory Bowel Disease (IBD)-Associated Colorectal Cancer (CRC): Is cGAS-STING Pathway Targeting the Key to Chemoprevention?

Inflammatory bowel disease (IBD)-associated colorectal cancer (CRC) remains a significant clinical challenge due to its link with chronic inflammation and the inherent limitations of current prevention and surveillance strategies. The cGAS-STING pathway has emerged as a key player in the immune regulation of inflammation-driven carcinogenesis, demonstrating both protective and pathogenic roles. This review examines the contrasting roles of the cGAS-STING signaling pathway in intestinal inflammation and colitis-associated cancer (CAC), emphasizing its promise as a target for cancer prevention strategies. Evidence suggests that modulating this pathway could preserve epithelial integrity, limit chronic inflammation, and bolster anti-tumor immunity. Despite advancements in therapies like mesalazine and surveillance colonoscopy programs, gaps in efficacy remain, particularly for Crohn's disease and high-risk populations. Future research should focus on integrating cGAS-STING-targeted approaches with existing modalities to provide personalized and less invasive strategies for CAC prevention. By harnessing this pathway's therapeutic potential, a paradigm shift in managing IBD-associated CRC may be achieved, addressing the challenges of long-term disease surveillance and prevention.

cGAS-STING targeting offers a novel therapeutic paradigm in cardiovascular diseases

Cyclic GMP/AMP (cGAMP) synthase (cGAS), along with the endoplasmic reticulum (ER)-associated stimulator of interferon genes (STING), are crucial elements of the type 1 interferon response. cGAS senses microbial DNA and self-DNA, labeling cGAS-STING as a crucial mechanism in autoimmunity, sterile inflammatory responses, and cellular senescence. However, chronic and aberrant activation of the cGAS/STING axis results in inflammatory and autoimmune diseases. cGAS-STING has emerged as a vital mechanism driving inflammation-related diseases, including cardiovascular diseases (CVDs). Insights into the biology of the cGAS-STING pathway have enabled the discovery of small-molecule agents which have the potential to inhibit the cGAS-STING axis in many human diseases. In this review, we first outline the principal components of the cGAS-STING signaling cascade. From such we discuss recent research that highlights general mechanisms by which cGAS-STING contributes to CVDs. Then, we summarize a list of bioactive small-molecule compounds which modulate the cGAS-STING axis, reviewing their potential clinical applications. Finally, we discuss key limitations of this new proposed therapeutic approach and provide possible techniques to overcome them.These review highlights a novel groundbreaking therapeutic possibilities through targeting cGAS-STING in CVDs.

Cutaneous lupus features specialized stromal niches and altered retroelement expression

Cutaneous Lupus is an inflammatory skin disease causing highly morbid inflamed skin and hair loss. In order to investigate the pathophysiology of cutaneous lupus, we performed single-cell RNA and spatial sequencing of lesional and non-lesional cutaneous lupus skin compared to healthy controls. Pathway enrichment analyses of lesional keratinocytes revealed elevated responses to type I interferon, type II interferon, tumor necrosis factor, and apoptotic signaling. Detailed clustering demonstrated unique fibroblasts specific to lupus skin with likely roles in inflammatory cell recruitment and fibrosis. We also evaluated the association of retroelement expression with type I interferons in the skin. We observed increased retroelement expression which correlated with interferon-stimulated genes across multiple cell types. Moreover, we saw elevated expression of genes involved in RIG-I and cGAS-STING pathways, which transduce elevated nucleic acid signals. Treatment of active cutaneous lupus with Anifrolumab reduced RIG-I and cGAS-STING pathways in addition to the most abundant retroelement family, L2b. Our studies better define type I interferon-mediated immunopathology in cutaneous lupus and identify an association between retroelement expression and interferon signatures in cutaneous lupus.

Berbamine as potential STING inhibitor For KRAS-mutant non-small cell lung cancer

Lung adenocarcinoma (LUAD) is a leading cause of cancer-related mortality. Poor prognostic results in LUAD are frequently associated with KRAS mutations and drug resistance. KRAS mutations can induce STING activation by triggering DNA damage response (DDR) activation. This persistently activated STING signaling gives rise to an immunosuppressive microenvironment, thereby complicating treatment efforts. In this study, we identified that the low-toxicity pro-apoptotic drug Berbamine (BBM) as a potential therapeutic agent for LUAD cells with KRAS mutations. BBM exhibits anti-tumor effects by triggering cell cycle arrest, enhancing senescence, and activating apoptosis. BBM also targets STING, leading to the downregulation of p-STING (Ser366) and CCL2. This in turn reduced the infiltration of M-MDSCs into the tumor microenvironment. These combined mechanisms not only suppress STING-dependent tumor growth but also remodel the immunosuppressive tumor microenvironment, thereby enhancing anti-tumor immunity. Collectively, our findings position BBM as a promising therapeutic agent for LUAD with KRAS mutations, offering a strategy to target STING-associated pathways, overcome immune suppression, and ultimately improve patient outcomes.

A strain of Lactobacillus plantarum from piglet intestines enhances the anti-PoRV effect via the STING-IFN-I pathway

BACKGROUND

Rotavirus infection represents a major etiology of severe diarrheal disease in neonatal and weaned piglets, causing substantial economic burdens to the global swine industry. Lactobacillus plantarum, a ubiquitous probiotic in natural ecosystems, has demonstrated multifaceted biological functions. The stimulator of the interferon gene (STING) is involved in type I interferon (IFN-I) mediated host antiviral innate immunity, which is a pivotal adaptor in response to the microbial DNA/RNA-activated signaling pathways. Emerging evidence suggests that certain probiotic strains can activate the STING-dependent pathway to induce IFN-I responses. In the present study, we successfully isolated a strain of Lactobacillus plantarum (designated LP1)from porcine intestinal contents and investigate its potential to counteract porcine rotavirus (PoRV) infection via modulation of antiviral signaling pathway.

RESULT

LP1 exhibited superior tolerance to simulated gastrointestinal conditions (pH 3.0 and 0.3% bile salts) compared with other isolated Lactobacillus strains. In vitro adhesion assays demonstrated that LP1effectively colonized porcine intestinal epithelial cells (IPEC-J2) without inducing cytotoxicity or apoptosis. Animal experiments also confirmed the protective effect of LP1 in mice against rotavirus, by reducing body weight loss, promoting viral clearance in feces, and alleviating intestinal mucosal damage. Mechanistic investigations identified STING-IRF3 pathway activation as the pivotal antiviral mechanism. Both phosphorylation of STING and IRF3 in LP1-treated IPEC-J2 cells accompanied by upregulated transcription and secretion of IFN-β and interferon-stimulated genes (ISGs). Consistent findings were observed in intestinal tissues of LP1-protected mice with STING pathway activation correlating with reduction in viral titers. Crucially, STING inhibitor (C-170) administration could reverse LP1-mediated antiviral effects.

CONCLUSION

LP1 exerts potent anti-PoRV activity in both murine models and porcine intestinal epithelial (IPEC-J2) cells through STING-IRF3 signaling axis-mediated IFN-β production.

Crosstalk Between Mitochondrial DNA and Immune Response: Focus on Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by multiple dysfunctions in behavior, the nervous system, and the immune system. Increasing evidence suggests that mitochondrial DNA (mtDNA) plays a crucial role in the pathology of ASD. In clinical practice, altered mtDNA levels have been observed in various tissues of individuals with ASD. Mutation or oxidation of mtDNA is also closely related to the immune response associated with the pathology of autism. With mtDNA identified as a causal factor, much interest has focused on how its production affects neurodevelopment and neurophysiology. Here, we review how mtDNA leads to dysfunction of cellular mitochondria and immune response. We also illustrate the relationship between mtDNA alterations and the pathology of autism. Finally, we discuss the existing evidence on cell-free mtDNA associated with ASD and look forward to its application in clinical diagnosis and treatment.

Discovery of Potent STING Inhibitors Bearing a Difluorobenzodioxol Structural Motif as Potent Anti-Inflammatory Agents

Given the critical role of STING in autoimmune and inflammatory disorders, the development of targeted small-molecule inhibitors has been a promising strategy for the treatment of these diseases. Nevertheless, the currently reported STING inhibitors suffer from limited structural diversity, species sensitivity, and poor activity; therefore, none are suitable for clinical investigation. Herein, we performed a structural modification campaign on the tool compound 6 (H-151) based on its potential metabolic hotspots. Compound 66, bearing a difluorobenzodioxol moiety, was identified as one of the most potent STING inhibitors with IC50 values of 116 and 96.3 nM for h- and m-STING, respectively. This compound exhibited a notable enhancement in metabolic properties, especially in terms of metabolic stability. A mechanism study verified that 66 engaged with STING in a covalent manner akin to that of 6. In both the cisplatin-induced acute kidney injury and TREX1 D18N mouse models, 66 significantly alleviated tissue injury and inflammation.

The induction of type I interferonopathy in Trex1-P212fs mice is mediated by activation of the cGAS-STING pathway

The cGAS-STING pathway is crucial for immune tolerance, pathogen resistance, and tumor immunity. Knocking out the cGAS gene can reverse the type I interferonopathy seen in Trex1-/- and Trex1D18N/D18N mice. TREX1, a key DNA-specific exonuclease in mammalian cells, degrades cytoplasmic DNA to prevent excessive immune activation. Mutations in TREX1 are linked to various autoimmune diseases. In prior research, we generated a Trex1-P212fs mouse model associated with systemic lupus erythematosus (SLE) using CRISPR-Cas9 gene editing. This model displays systemic inflammation that mirrors numerous characteristics of both Aicardi-Goutières syndrome (AGS) and SLE in humans. In this study, we found that the TREX1-P212fs mutation resulted in reduced dsDNA enzyme activity. DNA accumulation was present in the cytoplasm of Trex1P212fs/P212fs MEFs. Nonetheless, the role of the cGAS-STING pathway in mediating the disease phenotype in Trex1-P212fs mice associated with SLE has yet to be elucidated. We observed that cGas knockout mitigated systemic inflammation, lymphocyte proliferation, vasculitis, renal disease, and spontaneous T cell activation in Trex1-P212fs mice. Similarly, inhibition of STING with C-176 treatment ameliorated the disease phenotype in Trex1-P212fs mice. These findings elucidate the pathogenesis of TREX1-P212fs-associated type I interferonopathy and offer potential therapeutic targets for their treatment.

STING activation and overcoming the challenges associated with STING agonists using ADC (antibody-drug conjugate) and other delivery systems

In current immunotherapy cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway considered as most focused area after CAR-T cell. Exploitation of host immunity against cancer using STING agonists generates the most interest as a therapeutic target. Classically cGAS activation through cytoplasmic DNA generates 2'3'cGAMP that is naturally identified STING agonist. Activation of STING leads to activation of type-1 interferon response and pro-inflammatory cytokines through TBK/IRF-3, TBK/NF-κB pathways. Pro-inflammatory cytokines attract immune cells to the tumor microenvironment and type-1 interferon exposes tumor antigens to T cells and NK cells, which leads to the activation of cellular immunity against tumor cells and eliminates tumor cells. Initially bacterial-derived c-di-AMP and c-di-GMP were identified as CDNs (Cyclic-dinucleotide) STING agonists. Moreover, chemically modified CDNs and completely synthetic STING agonists have been developed. Even though the breakthrough preclinical development none of the STING agonists were approved the by FDA for cancer therapy. All identified natural CDNs have poor pharmacokinetic properties due to high hydrophilicity and negative charge. Moreover, phosphodiester bonds in CDNs are most vulnerable to enzymatic degradation. Synthetic STING agonists have an off-target effect that generates autoimmunity and cytokine storm. STING agonist needs to improve for pharmacokinetics, efficacy, and safety. In this scenario delivery systems can overcome the challenges associated with STING agonists. Here, we highlight the ways of STING agonisms as direct and indirect, and further, we also discuss the existing STING agonists associated challenges and ongoing efforts for delivery of STING agonists in the tumor microenvironment (TME) via different non-targeted carriers like Nanoparticle, Hydrogel, Micelle, Liposome. We also discussed the most advanced targeted deliveries of ADC (Antibody-drug conjugate) and aptamers-based delivery.

Endothelial dysfunction in the aging kidney

Global population aging is an escalating challenge in modern society, especially as it impairs the function of multiple organs and increases the burden of age-related diseases. The kidneys, in particular, experience function decline, reduced regenerative capacity, and increased susceptibility to injury as they age. As a result, the prevalence of chronic kidney disease (CKD) rises with aging, further contributing to the growing health burden in older populations. One of the key factors in this process is the dysfunction of specialized renal endothelial cells (RECs), which are essential for maintaining kidney health by regulating blood flow and supporting filtration, solute and water reabsorption, and vascular integrity. As the kidneys age, REC dysfunction drives vascular and microenvironmental changes, contributing to the overall decline in kidney function. In this review, we outline the structural and functional effects of aging on the kidney's macrovascular and microvascular compartments and provide a phenotypic description of the aged endothelium. We particularly focus on the molecular and metabolic rewiring driving and sustaining growth-arrested EC senescence phenotype. We finally give an overview of senotherapies acting on ECs, especially of those modulating metabolism. Given that the pathophysiological processes underlying kidney aging largely overlap with those observed in CKD, REC rejuvenation could also benefit patients with CKD. Moreover, such interventions may hold promise in improving the outcomes of aged kidney transplants. Hence, advancing our understanding of REC and kidney aging will create opportunities for innovations that could improve outcomes for both elderly individuals and patients with CKD.

Non-Canonical STING-PERK Pathway Modulation of Cellular Senescence and Therapeutic Response in Sepsis-Associated Acute Kidney Injury

Abstract-This study explored the role of the non-canonical STING-PERK signaling pathway in sepsis-associated acute kidney injury (SA-AKI). Gene expression data from the GEO database and serum STING protein levels in patients with SA-AKI were analyzed. An LPS-induced mouse model and an in vitro model using HK-2 cells were used to investigate the role of STING in SA-AKI. STING expression was suppressed using shRNA silencing technology and the STING inhibitor C176. Kidney function, inflammatory markers, apoptosis, and senescence were measured. The role of the STING-PERK pathway was investigated by silencing PERK in HK-2 cells and administering the PERK inhibitor GSK2606414. STING mRNA expression and serum STING protein levels were significantly higher in patients with SA-AKI. Suppressing STING expression improved kidney function, reduced inflammation, and inhibited apoptosis and senescence. Silencing PERK or administering GSK2606414 suppressed the inflammatory response, cell apoptosis, and senescence, suggesting that PERK is a downstream effector in the STING signaling pathway. The STING-PERK signaling pathway exacerbates cell senescence and apoptosis in SA-AKI. Inhibiting this pathway could provide potential therapeutic targets for SA-AKI treatment.

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.

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.

The cGAS-STING pathway in cancer immunity: dual roles, therapeutic strategies, and clinical challenges

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is a crucial component of the host's innate immunity and plays a central role in detecting cytosolic double-stranded DNA from endogenous and exogenous sources. Upon activation, cGAS synthesizes cGAMP, which binds to STING, triggering a cascade of immune responses, including the production of type I interferons and pro-inflammatory cytokines. In the context of cancers, the cGAS-STING pathway can exert dual roles: on the one hand, it promotes anti-tumor immunity by enhancing antigen presentation, stimulating T-cell responses, and inducing direct tumor cell apoptosis. On the other hand, chronic activation, particularly in tumors with chromosomal instability, can lead to immune suppression and tumor progression. Persistent cGAS-STING signaling results in the up-regulation of immune checkpoint molecules such as PD-L1, contributing to immune evasion and metastasis. Consequently, anti-tumor strategies targeting the cGAS-STING pathway have to consider the balance of immune activation and the immune tolerance caused by chronic activation. This review explores the mechanisms underlying both the anti-tumor and protumor roles of the cGAS-STING pathway, with a focus on potential therapeutic approaches, and the challenges faced in their clinical application, along with corresponding solutions.

Universal STING Pathway-Activating Complexes Counteract Viral Immune Evasion and Boost Antiviral Responses

Viruses have evolved multiple mechanisms to counteract the stimulator of the interferon genes (STING) pathway, resulting in the suppression of antiviral responses. Accordingly, in addition to developing STING agonist analogs with enhanced stability and deliverability, overcoming the defective STING function in virus-infected cells is essential for defense against viral infections. In this study, we developed STING pathway-activating complexes (SPAC) based on bioinspired vesicles that display and multimerize STING molecules with a specific affinity for agonist binding. As a broad-spectrum antiviral agent, this universal STING mimic triggers IFN-I signaling independently of endogenous STING. In infectious models, including CMV and SARS-CoV-2 infection, both prophylactic and therapeutic regimens of SPAC can reduce viral load and disease severity. These results indicate that SPAC, functioning as a host-targeted immune modulator, provides the distinct advantage of broad-spectrum therapy against infectious diseases caused by both DNA and RNA viruses, particularly those with strong STING antagonistic functions. The endogenous STING-independent activation mechanisms of SPAC may provide a universal therapy for infectious diseases, potentially serving as a candidate option to defend against future pandemics of "Disease X".

SIRT5 mediated succinylation of SUCLA2 regulates TCA cycle dysfunction and mitochondrial damage in pancreatic acinar cells in acute pancreatitis

Acute pancreatitis (AP) is a severe inflammatory disorder associated with metabolic reprogramming and mitochondrial dysfunction. This study investigated central carbon metabolism alterations in pancreatic acinar cells during AP, elucidated the molecular mechanisms of tricarboxylic acid (TCA) cycle disorders, and explored the role of protein hypersuccinylation in AP pathogenesis. Using in vitro and in vivo AP models, targeted metabolomics and bioinformatics analyses revealed TCA cycle dysregulation characterized by elevated succinyl-CoA and decreased succinate levels. Colorimetric assays, mass spectrometry, and site-directed mutagenesis demonstrated that SIRT5 downregulation led to SUCLA2 hypersuccinylation at K118, inhibiting succinyl-CoA synthetase activity and triggering a vicious cycle of succinyl-CoA accumulation and SUCLA2 succinylation. Adenovirus-mediated SIRT5 overexpression and SUCLA2 knockdown clarified the SIRT5-SUCLA2 pathway's role in regulating TCA cycle disorders. Protein succinylation levels positively correlated with pancreatic tissue damage and mitochondrial injury severity. Succinylome analysis identified cytochrome c1 (CYC1) as a key hypersuccinylated protein, and the SIRT5-SUCLA2 pathway regulated its succinylation level and electron transport chain complex III activity. Hypersuccinylation induced mitochondrial DNA release, activating the cGAS-STING pathway, contributing to multiple organ dysfunction syndrome. Modulating the SIRT5-SUCLA2 axis attenuated TCA cycle dysregulation, protein hypersuccinylation, mitochondrial damage, and inflammatory responses in AP. These findings reveal novel mechanisms linking the SIRT5-SUCLA2 axis, TCA cycle dysfunction, and protein hypersuccinylation in AP pathogenesis, providing potential therapeutic targets for AP treatment.

Nucleases: From Primitive Immune Defenders to Modern Biotechnology Tools

The story of nucleases begins on the ancient battlefields of early Earth, where simple bacteria fought to survive against viral invaders. Nucleases are enzymes that degrade nucleic acids, with restriction endonucleases emerging as some of the earliest defenders, cutting foreign DNA to protect their bacteria hosts. However, bacteria sought more than just defence. They evolved the CRISPR-Cas system, an adaptive immune mechanism capable of remembering past invaders. The now-famous Cas9 nuclease, a key player in this system, has been harnessed for genome editing, revolutionising biotechnology. Over time, nucleases evolved from basic viral defence tools into complex regulators of immune function in higher organisms. In humans, DNases and RNases maintain immune balance by clearing cellular debris, preventing autoimmunity, and defending against pathogens. These enzymes have transformed from simple bacterial defenders to critical players in both human immunity and biotechnology. This review explores the evolutionary history of nucleases and their vital roles as protectors in the story of life's defence mechanisms.

Irisin-mediated muscle-renal crosstalk as a protective mechanism against contrast-induced acute kidney injury via cGAS-STING signalling inhibition

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) continues to pose a pressing clinical challenge during invasive cardiovascular procedures due to the limited availability of preventative strategies. We aimed to demonstrate that irisin, a myokine induced by exercise, protects against CI-AKI by inhibiting the cGAS-STING inflammatory pathway.

METHODS AND RESULTS

We explored the relationship between serum irisin levels and CI-AKI incidence in patients administered the contrast media iohexol. Notably, lower serum irisin levels were strongly associated with an increased incidence of CI-AKI following contrast media administration. To establish a causal link between serum irisin levels and CI-AKI, we utilised a mouse model that simulates exercise by overexpressing muscle-specific PGC-1α. This approach showed a significant reduction in tubular injury and mitochondrial dysfunction induced by iohexol via cGAS/STING suppression, thereby diminishing inflammation. Mechanistically, irisin was found to inhibit the activation of cGAS/STING, preventing double stranded DNA (dsDNA) leakage and reducing inflammation in tubular epithelial cells (TECs). Pharmacological inhibition of STING further corroborated these observations. Moreover, we identified integrin complex αV/β5 as the irisin receptor on TECs, which is essential for irisin-mediated suppression of cGAS-STING signalling and resolution of inflammation.

CONCLUSIONS

Our data position irisin as a crucial factor in muscle‒kidney crosstalk, inhibiting cGAS-STING signalling and preventing dsDNA leakage via integrin αV/β5 in TECs, thus mitigating tubular injury and inflammation. These data underscore the potential of irisin as both a predictive biomarker for CI-AKI and a promising candidate for preventative strategies against CI-AKI.

HIGHLIGHTS

Irisin mediated muscle-kidney crosstalk mitigated tubular injury and inflammation. Irisin inhibited the cGAS-STING signalling activation via integrin αV/β5 in tubular epithelial cells. Irisin was a predictive biomarker and a promising candidate for CI-AKI.

MAVS: The next STING in cancers and other diseases

The mitochondrial antiviral signaling protein (MAVS) is a pivotal adaptor in the antiviral innate immune signaling pathway and plays a crucial role in the activation of antiviral defences. This comprehensive review delves into the multifaceted functions of MAVS, spanning from its integral role in the RIG-I-like receptor (RLR) pathway to its emerging roles in tumor biology and autoimmune diseases. We discuss the structural and functional aspects of MAVS, its activation mechanisms, and the intricate regulatory networks that govern its activity. The potential of MAVS as a therapeutic target has been explored, highlighting its promise in personalized cancer therapy and developing combination treatment strategies. Additionally, we compare it with the STING signaling pathway and discuss the synergistic potential of targeting both pathways in immunotherapy. Our review underscores the importance of MAVS in maintaining immune homeostasis and its implications for a broad spectrum of diseases, offering new avenues for therapeutic intervention.

A Single-Atom Mn/MoO3- x Nanoagonist for Cascade cGAS/STING Activation in Tumor-Specific Catalytic Metalloimmunotherapy

The cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway plays a crucial role in initiating anti-tumor immunity. Despite the development of various STING agonists, their effectiveness is often limited by suboptimal activation efficiency and poor sustainability. To address this, a Mn/MoO3- x nanoagonist featuring Mn single-atom sites is presented, designed for cascade cGAS/STING activation in tumor-specific catalytic metalloimmunotherapy. The single-atom nanoagonist (SANA) is meticulously crafted by doping Mn atoms into defective molybdenum oxide (MoO3- x), enabling robust peroxidase-mimicking catalysis and inducing severe double-stranded DNA (dsDNA) damage in tumors. Of note, Mn2+ and MoO4 2- can be responsively released from Mn/MoO3- x SANA and enhance the sensitivity of cGAS to dsDNA. Importantly, MoO4 2- with a relatively slow-release profile and facile cellular accumulation compensates for Mn2+ that has poor cellular accumulation due to continuous efflux, thus continuatively triggering the secretion of type I interferon for beyond 72 h. Remarkably, Mn/MoO3- x SANA significantly inhibits tumor growth and metastasis without supplementary STING agonists or external stimulation. This study offers a promising cascade cGAS/STING activation approach to enhance the efficacy and sustainability of catalytic metalloimmunotherapy.

cGAS-STING targeting offers novel therapeutic opportunities in neurological diseases

Cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS) is a cytosolic DNA sensor that produces the secondary messenger cGAMP. cGAMP activates the endoplasmic reticulum-associated adaptor stimulator of interferon genes (STING) and activates the innate immune system to produce a type I interferon response. Besides sensing microbial DNA, cGAS can also be activated by self-DNA or endogenous DNA, including that derived from genotoxic extranuclear chromatin and mitochondrially released DNA, indicating that cGAS-STING is an important mechanism in sterile inflammatory responses, autoimmunity, and cellular senescence. However, aberrant activation of the cGAS-STING pathway results in inflammatory and autoimmune diseases. cGAS-STING has emerged as a vital mechanism driving the pathogenesis of inflammation, implicating cGAS-STING signaling in neurological diseases. In this review, we first outline the principal elements of the cGAS-STING signaling cascade, summarizing recent research highlighting how cGAS-STING activation contributes to the pathogenesis of neurological diseases, including various autoimmune, autoinflammatory, and neurodegenerative diseases. Next, we outline selective small-molecule modulators that function as cGAS-STING inhibitors and summarize their mechanisms for treating multiple neurological diseases. Finally, we discuss key limitations of the current therapeutic paradigm and generate possible strategies to overcome them.

Huangqi-Danshen decoction alleviates renal fibrosis through targeting SCD1 to modulate cGAS/STING signaling

ETHNOPHARMACOLOGICAL RELEVANCE

The Huangqi-Danshen decoction (HDD) is composed of Huangqi (Astragali Radix) and Danshen (Salviae Miltiorrhizae Radix et Rhizoma) and has been shown to alleviate renal fibrosis. However, the potential therapeutic mechanisms and effective components of HDD remain unclear.

AIM OF THE STUDY

Both lipid metabolism and cGAS/STING signaling play vital roles in the development and progression of renal fibrosis. However, their relationship in renal fibrosis is largely unknown. The present study aimed to investigate the antifibrotic mechanisms of HDD from the perspective of lipid remodeling and cGAS/STING signaling.

MATERIALS AND METHODS

In vivo, renal fibrosis was induced by feeding male C57BL/6 mice with 0.2% adenine-diet for 28 consecutive days. The treatment groups were orally administered HDD at low, medium, and high doses of 3.4 g/kg/d, 6.8 g/kg/d, and 13.6 g/kg/d simultaneously with modeling. Renal function was evaluated by the serum levels of urea nitrogen and creatinine, pathological changes of renal tissue were evaluated by Periodic acid-Schiff and Masson's trichrome staining, and renal lipid metabolites were analyzed by lipidomics. Western blotting, immunohistochemistry, and immunofluorescence were used to detect the expressions of fibrosis-related proteins, SCD1, and cGAS/STING signaling-related proteins in renal tissue. In vitro, mouse primary proximal tubular epithelial cells (PTECs) were treated with transforming growth factor-β1 (TGF-β1) or stearoyl-CoA desaturase 1 (SCD1) inhibitor A939572. Additionally, UHPLC-QE-MS analysis and TCMSP database were used to screen the effective components of HDD, and the action mechanisms of these components were verified in mouse primary PTECs.

RESULTS

HDD dose-dependently improved renal function, pathological injury, and fibrosis in adenine-induced chronic kidney disease (CKD) mice model. Moreover, cGAS/STING signaling was significantly activated in fibrotic kidney and was suppressed by HDD treatment. In renal lipidomics analysis, 521 and 138 differential lipids were identified in control vs. CKD and CKD vs. CKD + HDD, respectively. Of note, lipids increased in fibrotic kidneys were more saturated (fewer double bonds), whereas lipids increased by HDD were less saturated (more double bonds). Further, SCD1 expression was significantly down-regulated in fibrotic kidney and could be restored by HDD treatment. The expression of SCD1 was also down-regulated in Ju CKD patients' dataset and TGF-β1-induced fibrogenic responses in mouse primary PTECs. Mechanistically, specific inhibition of SCD1 expression could activate cGAS/STING signaling in primary PTECs. In addition, three components of HDD (isoimperatorin, baicalin, and miltirone) were screened out. Furthermore, administration of these three components, especially isoimperatorin and miltirone, counteracted the activation of cGAS/STING signaling induced by SCD1 pharmacological inhibition.

CONCLUSION

HDD could alleviate renal fibrosis, which may be related to the regulation of cGAS/STING signaling through targeting SCD1.

Exposure to Manganese Induces Autophagy-Lysosomal Pathway Dysfunction-Mediated Tauopathy by Activating the cGAS-STING Pathway in the Brain

Manganese (Mn) exposure leads to pathological accumulation of Tau-associated neurodegenerative disease and has become a major public health concern. However, the precise mechanism underlying this effect remains unclear. Here, the mechanism by which Mn induces dysfunction of autophagy-lysosomal pathway-mediated tauopathy by activating the cGAS-STING pathway was explored both in vitro and in vivo. Mn exposure induced tauopathy in microglia and in mice while activating the cGAS-STING pathway, inducing type I interferon production, and impairing the degradation function of the autophagy-lysosomal pathway. Importantly, inactivation of the cGAS-STING pathway rescued the degradation activity of the autophagy-lysosomal pathway, while tauopathy was markedly attenuated, as shown in both cGAS-knockout and STING-knockout BV2 microglia and in mice. Moreover, the autophagy inhibitor 3-methyladenine (3-MA) restored the impaired degradation activity of the autophagy-lysosomal pathway by inactivating the cGAS-STING pathway, thereby clearing Tau aggregation. Taken together, these results indicate that Mn exposure induces tauopathy by impairing the function of the autophagy-lysosomal pathway through the activation of the cGAS-STING pathway. Thus, this study identifies a novel mechanism by which Mn exposure induces Tau aggregation, which in turn triggers potential neurotoxicity, providing a foundation for future drug target research.

NLRP3 Inflammasome Targeting Offers a Novel Therapeutic Paradigm for Sepsis-Induced Myocardial Injury

Cardiac or myocardial dysfunction induced by sepsis, known as sepsis-induced cardiomyopathy or sepsis-induced myocardial injury (SIMI), is a common complication of sepsis and is associated with poor outcomes. However, the pathogenesis and molecular mechanisms underlying SIMI remain poorly understood, requiring further investigations. Emerging evidence has shown that NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes contribute to SIMI. Compounds that inhibit NLRP3-associated pyroptosis may exert therapeutic effects against SIMI. In this review, we first outlined the principal elements of the NLRP3 signaling cascade and summarized the recent studies highlighting how NLRP3 activation contributes to the pathogenesis of SIMI. We outlined selective small-molecule modulators that function as NLRP3 inhibitors and delineated their mechanisms of action to attenuate SIMI. Finally, we discuss the major limitations of the current therapeutic paradigm and propose possible strategies to overcome them. This review highlights the pharmacological inhibition of SIMI as a promising therapeutic strategy.

CerS6 links ceramide metabolism to innate immune responses in diabetic kidney disease

Ectopic lipid deposition, mitochondrial injury, and inflammatory responses contribute to the development of diabetic kidney disease (DKD); however, the mechanistic link between these processes remains unclear. In this study, we demonstrate that the ceramide synthase 6 (CerS6) is primarily localized in podocytes of the glomeruli and is upregulated in two different models of diabetic mice. Podocyte-specific CerS6 knockout ameliorates glomerular injury and inflammatory responses in male diabetic mice and in male mice with adriamycin-induced nephropathy. In contrast, podocyte-specific overexpression of CerS6 sufficiently induces proteinuria. Mechanistically, CerS6-derived ceramide (d18:1/16:0) can bind to the mitochondrial channel protein VDAC1 at Glu59 residue, initiating mitochondrial DNA (mtDNA) leakage, activating the cGAS-STING signaling pathway, and ultimately promoting an immune-inflammatory response in the kidney. Importantly, CERS6 expression is increased in podocytes from kidney biopsies of patients with DKD and focal segmental glomerulosclerosis (FSGS), and the expression level of CERS6 is correlated negatively with glomerular filtration rate and positively with proteinuria. Thus, our findings suggest that targeting CerS6 may be a potential therapeutic strategy for proteinuric kidney diseases.

cGAS-STING targeting offers therapy choice in lung diseases

Cyclic GMP/AMP (cGAMP) synthase (cGAS), along with the endoplasmic reticulum (ER)-associated stimulator of interferon genes (STING), are crucial elements of the type 1 interferon response. cGAS senses microbial DNA and self-DNA, labeling cGAS-STING as a crucial mechanism in autoimmunity, sterile inflammatory responses, and cellular senescence. However, chronic and aberrant activation of the cGAS-STING axis results in inflammatory and autoimmune diseases. cGAS-STING has emerged as a vital mechanism driving inflammation-related diseases, including lung diseases. Insights into the biology of the cGAS-STING pathway have enabled the discovery of small-molecule agents which have the potential to inhibit the cGAS-STING axis in lung diseases. In this review, we first outline the principal components of the cGAS-STING signaling cascade. Then, we discuss recent research that highlights general mechanisms by which cGAS-STING contributes to lung diseases. Then, we focus on summarizing a list of bioactive small-molecule compounds which inhibit the cGAS-STING pathway, reviewing their potential mechanisms.These review highlights a novel groundbreaking therapeutic possibilities through targeting cGAS-STING in lung diseases.

Targeting ferroptosis offers therapy choice in sepsis-associated acute lung injury

Sepsis-associated acute lung injury (SALI) is a common complication of sepsis, consisting of a dysfunctional host response to infection-mediated heterogenous complexes. SALI is reported in up to 50 % of patients with sepsis and causes poor outcomes. Despite high incidence, there is a lack of understanding in its pathogenesis and optimal treatment. A better understanding of the molecular mechanisms underlying SALI may help produce better therapeutics. The effects of altered cell-death mechanisms, such as non-apoptotic regulated cell death (RCD) (i.e., ferroptosis), on the development of SALI are beginning to be discovered, while targeting ferroptosis as a meaningful target in SALI is increasingly being recognized. Here, we outline how a susceptible lung alveoli may develop SALI. Then we discuss the general mechanisms underlying ferroptosis, and how it contributes to SALI. We then outline the chemical structures of the emerging agents or compounds that can protect against SALI by inhibiting ferroptosis, summarizing their potential pharmacological effects. Finally, we highlight key limitations and possible strategies to overcome them. This review suggests that a detailed mechanistic and biological understanding of ferroptosis can foster the development of pharmacological antagonists in the treatment of SALI.

BRG1 Deficiency Promotes Cardiomyocyte Inflammation and Apoptosis by Activating the cGAS-STING Signaling in Diabetic Cardiomyopathy

Brahma-related gene 1 (BRG1) has been implicated in the repair of DNA double-strand breaks (DSBs). Downregulation of BRG1 impairs DSBs repair leading to accumulation of double-stranded DNA (dsDNA). Currently, the role of BRG1 in diabetic cardiomyopathy (DCM) has not been clarified. In this study, we aimed to explore the function and molecular by which BRG1 regulates DCM using mice and cell models. We found that BRG1 was downregulated in the cardiac tissues of DCM mice and in cardiomyocytes cultured with high glucose and palmitic acid (HG/PA), which was accompanied by accumulation of dsDNA and activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. shRNA-mediated Brg1 knockdown aggravated DCM mice cardiac functions, enhanced dsDNA accumulation, cGAS-STING signaling activation, which induced inflammation and apoptosis. In addition, the results were further verified in HG/PA-treated primary neonatal rat cardiomyocytes (NRCMs). Overexpression of BRG1 in NRCMs yielded opposite results. Furthermore, a selective cGAS inhibitor RU.521 or STING inhibitor C-176 partially reversed the BRG1 knockdown-induced inflammation and apoptosis in vitro. In conclusion, our results demonstrate that BRG1 is downregulated during DCM in vivo and in vitro, resulting in cardiomyocyte inflammation and apoptosis due to dsDNA accumulation and cGAS-STING signaling activation. Therefore, targeting the BRG1-cGAS-STING pathway may represent a novel therapeutic strategy for improving cardiac function of patients with DCM.

The cross-talk between the cGAS-STING signaling pathway and chronic inflammation in the development of musculoskeletal disorders

Musculoskeletal disorders (MSDs) comprise diverse conditions affecting bones, joints, and muscles, leading to pain and loss of function, and are one of the most prevalent and major global health concerns. One of the hallmarks of MSDs is DNA damage. Once accumulated in the cytoplasm, the damaged DNA is sensed by the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway, which triggers the induction of type I interferons and inflammatory cytokines. Thus, this pathway connects the musculoskeletal and immune systems. Inhibitors of cGAS or STING have shown promising therapeutic effects in the pre-clinical models of several MSDs. Systemic, chronic, low-grade inflammation (SCLGI) underlies the development and maintenance of many MSDs. Failure to resolve SCLGI has been hypothesized to play a critical role in the development of chronic diseases, suggesting that the successful resolution of SCLGI will result in the alleviation of their related symptomatology. The process of inflammation resolution is feasible by specialized pro-resolving mediators (SPMs), which are enzymatically generated from dietary essential polyunsaturated fatty acids (PUFAs). The supplementation of SPMs or their stable, small-molecule mimetics and receptor agonists has revealed beneficial effects in inflammation-related animal models, including arthropathies, osteoporosis, and muscle dystrophy, suggesting a translational potential in MSDs. In this review, we substantiate the hypothesis that the use of cGAS-STING signaling pathway inhibitors together with SCLG-resolving compounds may serve as a promising new therapeutic approach for MSDs.

The Stimulator of Interferon Genes Deficiency Attenuates Diabetic Myopathy Through Inhibiting NLRP3-Mediated Pyroptosis

BACKGROUND

Diabetic myopathy is characterized by the loss of skeletal muscle mass and function. NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated pyroptosis is a type of proinflammatory cell death, which can exacerbate significant muscle cell loss and adverse remodelling. The stimulator of interferon genes (STING) is an essential molecule involved in the regulation of inflammation and immune responses across various diseases. The regulatory mechanism by which STING affects muscle pyroptosis in diabetic myopathy remains unclear.

METHODS

STING-knockout and wild-type (WT) mice underwent intraperitoneal injection of streptozotocin (STZ). STING small interfering RNA (siRNA) was transfected into fully differentiated C2C12 myotubes prior to glucose treatment. Muscle function tests, body composition analysis, transmission electron microscopy, scanning electron microscopy, western blotting, immunofluorescence, immunohistochemistry, histology, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction were performed. Co-immunoprecipitation assays were employed to investigate the interaction between STING and NLRP3.

RESULTS

STING expression was elevated in the gastrocnemius muscle (GM) tissues of WT diabetic mice. STING-deficient diabetic mice exhibited pronounced hyperglycaemia accompanied by hypoinsulinaemia, with no significant difference compared with WT diabetic mice. However, STING-deficient diabetic mice demonstrated a significantly increased body weight and lean mass. A significant decrease in muscle weight, myofibrillar diameter and area, muscle function, and the expression of genes related to muscle atrophy (MuRF1, Atrogin1) were observed in WT diabetic mice, which was mitigated in STING-deficient diabetic mice. STING deficiency reduced the number of GSDMD-N formed pores and pyroptosis-related components (NLRP3, caspase-1, cle-caspase-1, GSDMD, and GSDMD-N) in the GM tissues and was associated with a reduction in inflammatory chemokines. Similar changes were observed in vitro with glucose-induced myotube atrophy and pyroptosis as seen in vivo. Activation of STING by the agonist diABZI exacerbated muscle atrophy and pyroptosis in C2C12 myotubes. Co-localization of STING and NLRP3 was observed, and the interaction between STING and NLRP3 was enhanced in GM tissues from WT diabetic mice. We also found that STING could activate NLRP3 dependent on its channel activity, which can be attenuated by treated with C53 (an inhibitor of STING's ion-channel function).

CONCLUSIONS

In conclusion, our results indicate that STING-induced activation of the NLRP3 inflammasome leads to pyroptosis, resulting in muscle atrophy and dysfunction. These findings not only elucidate the mechanism of STING-induced pyroptosis but also identify STING as a potential therapeutic target for diabetic myopathy.

When two signals cross paths: cGAS-STING and ER stress in kidney disease progression

Previous reports have suggested that both the endoplasmic reticulum (ER) stress and cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathways contribute to the progression of chronic kidney disease; however, the relationship between these 2 pathways in kidney injury has not been fully elucidated. Andrade-Silva et al. revealed that the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway can enhance ER stress through the protein kinase R-like ER kinase (PERK)-mediated signaling cascade in kidney tubular epithelial cells and sequentially augment fibrosis during kidney injury. Further studies are needed to elucidate the precise mechanisms by which the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway activates PERK-dependent ER stress in kidney tubular epithelial cells post injury.

cGAS/STING signaling pathway in gynecological malignancies: From molecular mechanisms to therapeutic values

Gynecological cancers, including cervical, ovarian, and endometrial malignancies, remain a significant global health burden, exacerbated by disparities in access to preventive measures such as HPV vaccination and routine screening. The cGAS/STING signaling pathway, a pivotal mechanism in innate immunity, detects cytosolic DNA from pathogens or cellular damage, triggering immune responses via type I interferons and inflammatory cytokines. This pathway's dual role in gynecological cancers, either promoting antitumor immunity or facilitating tumor immune evasion, makes it a compelling target for innovative therapies. The article outlines cGAS/STING's influence on tumor microenvironments, immune surveillance, and inflammation, with emphasis on molecular mechanisms driving cancer progression. It explores interactions between DNA damage response pathways and immune modulation, highlighting the impact of cGAS/STING activation or suppression in ovarian, cervical, and endometrial cancers. The therapeutic potential of STING agonists, PARP inhibitors, and targeted immunotherapies is reviewed, demonstrating how these approaches can boost immune responses, counteract chemotherapy resistance, and improve patient outcomes. The study also discusses strategies for leveraging cGAS/STING signaling to enhance the efficacy of immunotherapies and address tumor-mediated immune suppression, providing insights into future directions for personalized cancer treatments.

Self-Cascaded Pyroptosis-STING Initiators for Catalytic Metalloimmunotherapy

Gasdermin (GSDM)-mediated pyroptosis involves the induction of mitochondrial damage and the subsequent release of mitochondrial DNA (mtDNA), which is anticipated to activate the cGAS-STING pathway, thereby augmenting the antitumor immune response. However, challenges lie in effectively triggering pyroptosis in cancer cells and subsequently enhancing the cGAS-STING activation with specificity. Herein, we developed intelligent self-cascaded pyroptosis-STING initiators of cobalt fluoride (CoF2) nanocatalysts for catalytic metalloimmunotherapy. CoF2 nanocatalysts with a semiconductor structure and enzyme-like activity generated a substantial amount of reactive oxygen species (ROS) under stimulation by endogenous H2O2 and exogenous ultrasound. Importantly, we discovered that Co-based nanomaterials themselves induce pyroptosis in cancer cells. Therefore, CoF2 nanocatalysts initially acted as pyroptosis inducers, triggering caspase-1/GSDMD-dependent pyroptosis in cancer cells via Co2+ and ROS, leading to mtDNA release. Subsequently, CoF2 nanocatalysts were further utilized as intelligent STING agonists that were specifically capable of detecting mtDNA and augmenting the activation of the cGAS-STING pathway. These cascade events triggered a robust immune response, effectively modulating the immunosuppressive tumor microenvironment into an immune-supportive state, thereby providing favorable support for antitumor therapy. This innovative strategy not only significantly impeded the growth of the primary tumor but also elicited an immune response to further augment the efficacy of immune checkpoint inhibitors in preventing distant tumor progression. Overall, this study proposed a self-cascade strategy for activating and amplifying the cGAS-STING pathway with specificity mediated by pyroptosis, representing a valuable avenue for future cancer catalytic metalloimmunotherapy.

Emerging regulatory mechanisms and functions of biomolecular condensates: implications for therapeutic targets

Cells orchestrate their processes through complex interactions, precisely organizing biomolecules in space and time. Recent discoveries have highlighted the crucial role of biomolecular condensates-membrane-less assemblies formed through the condensation of proteins, nucleic acids, and other molecules-in driving efficient and dynamic cellular processes. These condensates are integral to various physiological functions, such as gene expression and intracellular signal transduction, enabling rapid and finely tuned cellular responses. Their ability to regulate cellular signaling pathways is particularly significant, as it requires a careful balance between flexibility and precision. Disruption of this balance can lead to pathological conditions, including neurodegenerative diseases, cancer, and viral infections. Consequently, biomolecular condensates have emerged as promising therapeutic targets, with the potential to offer novel approaches to disease treatment. In this review, we present the recent insights into the regulatory mechanisms by which biomolecular condensates influence intracellular signaling pathways, their roles in health and disease, and potential strategies for modulating condensate dynamics as a therapeutic approach. Understanding these emerging principles may provide valuable directions for developing effective treatments targeting the aberrant behavior of biomolecular condensates in various diseases.

Mitochondrial dysfunction, cause or consequence in neurodegenerative diseases?

Neurodegenerative diseases encompass a spectrum of conditions characterized by the gradual deterioration of neurons in the central and peripheral nervous system. While their origins are multifaceted, emerging data underscore the pivotal role of impaired mitochondrial functions and endolysosomal homeostasis to the onset and progression of pathology. This article explores whether mitochondrial dysfunctions act as causal factors or are intricately linked to the decline in endolysosomal function. As research delves deeper into the genetics of neurodegenerative diseases, an increasing number of risk loci and genes associated with the regulation of endolysosomal and autophagy functions are being identified, arguing for a downstream impact on mitochondrial health. Our hypothesis centers on the notion that disturbances in endolysosomal processes may propagate to other organelles, including mitochondria, through disrupted inter-organellar communication. We discuss these views in the context of major neurodegenerative diseases including Alzheimer's and Parkinson's diseases, and their relevance to potential therapeutic avenues.

Platelet's plea to Immunologists: Please do not forget me

Platelets are non-nucleated mammalian cells originating from the cytoplasmic expulsion of the megakaryocytes. Megakaryocytes develop during hematopoiesis through megakaryopoiesis, whereas platelets develop from megakaryocytes through thrombopoiesis. Since their first discovery, platelets have been studied as critical cells controlling hemostasis or blood coagulation. However, coagulation and innate immune response are evolutionarily linked processes. Therefore, it has become critical to investigate the immunological functions of platelets to maintain immune homeostasis. Advances in immunology and platelet biology research have explored different critical roles of platelets, including phagocytosis, release of different immune mediators, and controlling functions of different immune cells by direct interaction and immune mediators. The current article discusses platelet's development and their critical role as innate immune cells, which express different pattern recognition receptors (PRRs), recognizing different pathogen or microbe-associated molecular patterns (PAMPs or MAMPs) and death/damage-associated molecular patterns (DAMPs) and their direct interactions with innate and adaptive immune cells to maintain immune homeostasis.

Nanomedicines harnessing cGAS-STING pathway: sparking immune revitalization to transform 'cold' tumors into 'hot' tumors

cGAS-STING pathway stands at the forefront of innate immunity and plays a critical role in regulating adaptive immune responses, making it as a key orchestrator of anti-tumor immunity. Despite the great potential, clinical outcomes with cGAS-STING activators have been disappointing due to their unfavorable in vivo fate, signaling an urgent need for innovative solutions to bridge the gap in clinical translation. Recent advancements in nanotechnology have propelled cGAS-STING-targeting nanomedicines to the cutting-edge of cancer therapy, leveraging precise drug delivery systems and multifunctional platforms to achieve remarkable region-specific biodistribution and potent therapeutic efficacy. In this review, we provide an in-depth exploration of the molecular mechanisms that govern cGAS-STING signaling and its potential to dynamically modulate the anti-tumor immune cycle. We subsequently introduced several investigational cGAS-STING-dependent anti-tumor agents and summarized their clinical trial progress. Additionally, we provided a comprehensive review of the unique advantages of cGAS-STING-targeted nanomedicines, highlighting the transformative potential of nanotechnology in this field. Furthermore, we comprehensively reviewed and comparatively analyzed the latest breakthroughs cGAS-STING-targeting nanomedicine, focusing on strategies that induce cytosolic DNA generation via exogenous DNA delivery, chemotherapy, radiotherapy, or dynamic therapies, as well as the nanodelivery of STING agonists. Lastly, we discuss the future prospects and challenges in cGAS-STING-targeting nanomedicine development, offering new insights to bridge the gap between mechanistic research and drug development, thereby opening new pathways in cancer treatment.

Classification and functional characterization of regulators of intracellular STING trafficking identified by genome-wide optical pooled screening

Stimulator of interferon genes (STING) traffics across intracellular compartments to trigger innate responses. Mutations in factors regulating this process lead to inflammatory disorders. To systematically identify factors involved in STING trafficking, we performed a genome-wide optical pooled screen (OPS). Based on the subcellular localization of STING in 45 million cells, we defined 464 clusters of gene perturbations based on their cellular phenotypes. A secondary, higher-dimensional OPS identified 73 finer clusters. We show that the loss of the gene of unknown function C19orf25, which clustered with USE1, a protein involved in Golgi-to-endoplasmic reticulum (ER) transport, enhances STING signaling. Additionally, HOPS deficiency delayed STING degradation and consequently increased signaling. Similarly, GARP/RIC1-RGP1 loss increased STING signaling by delaying STING Golgi exit. Our findings demonstrate that genome-wide genotype-phenotype maps based on high-content cell imaging outperform other screening approaches and provide a community resource for mining factors that impact STING trafficking and other cellular processes.

The cGAS-STING pathway in ischemia-reperfusion injury in acute cerebral infarction: a new therapeutic opportunities?

The innate immune response is the body's first line of defense against external pathogens and endogenous damage signals. The cGAS-STING pathway is a crucial component of the innate immune response, playing a key role in initiating antiviral and anti-infective immune responses by recognizing cytosolic DNA. Acute cerebral infarction is one of the leading causes of death and disability worldwide, with the primary treatment approach being the restoration of blood flow to ischemic brain tissue. However, reperfusion injury remains a significant challenge during treatment. The overactivation of the cGAS-STING pathway and its association with ischemia-reperfusion injury have been confirmed in numerous studies. This article will systematically elucidate the mechanisms of the cGAS-STING pathway, its role in ischemia-reperfusion injury in acute cerebral infarction, the current research status of cGAS-STING inhibitors, and the application of nanomaterials in this context, evaluating the therapeutic potential of this pathway.

Strategies Used by SARS-CoV-2 to Evade the Innate Immune System in an Evolutionary Perspective

By the end of 2019, the COVID-19 pandemic, resulting from the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), had diffused widely across the globe, with 770 million infected individuals and over 7 million deaths reported. In addition to its high infectivity and pathogenicity and its rapid mutation rate, the unique capacity of SARS-CoV-2 to circumvent the immune system has also contributed to the widespread nature of this pandemic. SARS-CoV-2 elicits the onset of innate immune system activation and initiates antiviral responses once it has infected the host. While battling the host's immune responses, SARS-CoV-2 has established many countermeasures to evade attack and clearance. As the exploration of SARS-CoV-2 continues, substantial evidence has revealed that the 29 proteins synthesized by the SARS-CoV-2 genome are integral to the viral infection process. They not only facilitate viral replication and transmission, but also assist SARS-CoV-2 in escaping the host's immune defenses, positioning them as promising therapeutic targets that have attracted considerable attention in recent studies. This review summarizes the manner in which SARS-CoV-2 interfaces with the innate immune system, with a particular focus on the continuous evolution of SARS-CoV-2 and the implications of mutations.

Fantastic proteins and where to find them - histones, in the nucleus and beyond

Animal genomes are packaged into chromatin, a highly dynamic macromolecular structure of DNA and histone proteins organised into nucleosomes. This accommodates packaging of lengthy genomic sequences within the physical confines of the nucleus while also enabling precise regulation of access to genetic information. However, histones existed before chromatin and have lesser-known functions beyond genome regulation. Most notably, histones are potent antimicrobial agents, and the release of chromatin to the extracellular space is a defence mechanism nearly as ancient and widespread as chromatin itself. Histone sequences have changed very little throughout evolution, suggesting the possibility that some of their 'non-canonical' functions are at play in parallel or in concert with their genome regulatory functions. In this Review, we take an evolutionary perspective of histone, nuclear chromatin and extracellular chromatin biology and describe the known extranuclear and extracellular functions of histones. We detail molecular mechanisms of chromatin release and extracellular chromatin sensing, and we discuss their roles in physiology and disease. Finally, we present evidence and give a perspective on the potential of extracellular histones to act as bioactive, cell modulatory factors.

Discovery of Potent and Orally Bioavailable Pyrimidine Amide cGAS Inhibitors via Structure-Guided Hybridization

Using a high-throughput screening (HTS) approach, a new GTP-site binding pyridine-carboxylate series of cGAS inhibitors was discovered. The biochemical potency of this new pyridine carboxylate series was improved 166-fold from the original hit to double-digit nanomolar levels using structure-based design insights, but the series was found to suffer from low permeability and low bioavailability. A structure-based hybridization of the metal-binding motifs of the pyridine carboxylate series and our previously disclosed tetrahydrocarboline GTP-site ligand 23 identified pyrimidine amide compound 36. Compound 36 is potent against both human and mouse cGAS isoforms and has a favorable pharmacokinetic (PK) profile in mice. Additionally, compound 36 displayed a dose-dependent reduction in cGAMP production in a ConA pharmacodynamic mouse model of acute liver injury, demonstrating potential utility as an in vivo tool compound for further investigation of the cGAS pathway.

TRIM-endous functional network of tripartite motif 29 (TRIM29) in cancer progression and beyond

While most Tripartite motif (TRIM) family proteins are E3 ubiquitin ligases, some members have functions beyond the regulation of ubiquitination, impacting normal physiological processes and disease progression. TRIM29, an important member of the TRIM family, exerts a predominant influence on cancer growth, epithelial-to-mesenchymal transition, stemness and metastatic progression by directly potentiating multiple canonical oncogenic pathways. The cancer-promoting effect of TRIM29 is also evident in metabolic interventions and interference with the efficacy of cancer therapeutics. As expected for any key node in cancer, the expression of TRIM29 is tightly regulated by non-coding RNAs, epigenetic modulation, and post-translational regulation. A systematic discussion of how TRIM29 is regulated in cancer, its influences on cancer progression, and its impact on cancer therapeutics is presented in this review. We also explore the context-dependent alterations between TRIM29 function from oncogenic to tumor suppression. As TRIM29 is involved in multiple aspects of cancer progression, a better understanding of its biological impact in cancer may help improve prognosis and develop novel therapeutic combinations, leading to improved personalized cancer care.

Navigating monkeypox: identifying risks and implementing solutions

Monkeypox is a zoonotic disease caused by the orthopox virus, a double-stranded DNA virus that belongs the Poxviridae virus family. It is known to infect both animals (especially monkeys and rodents) and humans and causes a rash similar to smallpox. Humans can become infected with monkeypox virus (MPXV) when they get in close contact with infected animals (zoonotic transmission) or other infected people (human-human transmission) through their body fluids such as mucus, saliva, or even skin sores. Frequently observed symptoms of this disease include fever, headaches, muscle aches, and a rash that initially looks like a tiny bump before becoming a lump that is filled with fluid. Monkeypox symptoms also include an incubation period of 5-21 days, divided into prodromal and eruption phases. Several contributing factors, such as smallpox vaccine discontinuation, widespread intake of infected animal products as a source of protein, and high population density, amongst others, have been linked to an increase in the frequency of monkeypox outbreaks. The best course of action for diagnosing individuals who may be suffering from active monkeypox is to collect a sample of skin from the lesion and perform PCR molecular testing. Monkeypox does not presently have a specific therapy; however, supportive care can assist in managing symptoms, such as medication to lower body temperature and pain. Three major orthopoxvirus vaccines have been approved to serve as a preventive measure against monkeypox: LC16, JYNNEOS, and ACAM2000. The discovery that the monkeypox outbreak is communicable both among humans and within a population has sparked new public health worries on the possibility of the outbreak of another viral pandemic. Research and studies are still being conducted to gain a deeper understanding of this zoonotic viral disease. This review is therefore focused on deciphering monkeypox, its etiology, pathogenesis, transmission, risk factors, and control.

Activation of α7 Nicotinic Acetylcholine Receptors Inhibits Hepatic Necroptosis and Ameliorates Acute Liver Injury in Mice

BACKGROUND

Acute liver injury is a disease characterized by severe liver dysfunction, caused by significant infiltration of immune cells and extensive cell death with a high mortality. Previous studies demonstrated that the α7 nicotinic acetylcholine receptor (α7nAChR) played a crucial role in various liver diseases. The hypothesis of this study was that activating α7nAChR could alleviate acute liver injury and investigate its possible mechanisms.

METHODS

Acute liver injury was induced by intraperitoneal injection of lipopolysaccharide (LPS)/D-galactosamine (D-Gal) in wild type, α7nAChR knockout (α7nAChR-/-) and stimulator of interferon gene (STING) mutation (Stinggt/gt) mice in the presence or absence of a pharmacologic selective α7nAChR agonist (PNU-282987). The effects of α7nAChR on hepatic injury, inflammatory response, mitochondrial damage, necroptosis, and infiltration of immune cells during acute liver injury were assessed.

RESULTS

The expression of α7nAChR in liver tissue was increased in LPS/D-Gal-induced acute liver injury mice. Compared to the age-matched wild-type mice, α7nAChR deficiency decreased the survival rate, exacerbated the hepatic injury accompanied with enhanced inflammatory response and oxidative stress, and aggravated hepatic mitochondrial damage and necroptosis. Conversely, pharmacologic activation of α7nAChR by PNU-282987 displayed the opposite trends. Furthermore, PNU-282987 significantly reduced the proportion of infiltrating monocyte-derived macrophages (CD45+CD11bhiF4/80int), M1 macrophages (CD45+CD11b+F4/80+CD86hiCD163low), and Ly6Chi monocytes (CD45+CD11b+MHC [major histocompatibility complex] ⅡlowLy6Chi), but increased the resident Kupffer cells (CD45+CD11bintF4/80hiTIM4hi) in the damaged hepatic tissues caused by LPS/D-Gal. Interestingly, α7nAChR deficiency promoted the STING signaling pathway under LPS/D-Gal stimulation, while PNU-282987 treatment significantly prevented its activation. Finally, it was found that Sting mutation abolished the protective effects against hepatic injury by activating α7nAChR.

CONCLUSIONS

The authors' study revealed that activating α7nAChR could protect against LPS/D-Gal-induced acute liver injury by inhibiting hepatic inflammation and necroptosis possibly via regulating immune cells infiltration and inhibiting STING signaling pathway.

EDITOR’S PERSPECTIVE