Activated STING in a vascular and pulmonary syndrome

Endothelia-targeting eye drops deliver a STING inhibitor to effectively reduce retinal neovascularization in ischemic retinopathy

Retinal neovascularization is the main pathologic feature of ischemic retinopathy, which eventually leads to vision loss and even blindness. Current treatments like laser photocoagulation and intravitreal injection of anti-vascular endothelial growth factor A drugs are invasive, expensive, and incompetent. Therefore, it is urgent to explore optimized therapies, particularly eye drops, to improve treatment effects. Our recent study reported that abnormal up-regulation of stimulator of interferon genes (STING) is closely associated with retinal vascular diseases, and it is highly enriched in retinal endothelial cells with retinopathy. Thus, we evaluated whether endothelial STING affects retinal neovascularization. In addition, we constructed iRGD- and TAT-decorated nanoparticles (NPs) loaded with C-176 (I/T-C-NP), capable of penetrating the cornea and targeting retinal endothelial cells. The I/T-C-NP eye drops were applied to the eyes of oxygen-induced retinopathy mice, resulting in attenuated activation of the STING pathway. Consequently, retinal neovascularization and vascular tortuosity were effectively reduced, astrocyte activation was prohibited, and pericyte coverage was improved. These observations suggest that I/T-C-NP eye drops can be a potential solution for the treatment of retinal neovascularization.

MINT3 promotes STING activation and facilitates antiviral immune responses

Stimulator-of-interferon genes (STING) translocation is the rate-limiting step in the cGAS-STING signaling which detects cytosolic DNA and produces type I interferons. However, the mechanism by which this process is modulated remains to be further clarified. In the present study, we identified munc18-1-interacting protein 3 (MINT3) as a positive regulator of STING signaling. MINT3 promotes type I interferons production induced by herpes simplex virus-1 (HSV-1) infection and ISD or cGAMP stimulation in mouse peritoneal macrophages. Deficiency of Mint3 greatly inhibited STING and IRF3 activation in macrophages. Mint3 knockdown also attenuated STING and IRF3 activation in macrophages, human THP-1 cells, and RAW264.7 cells. Mechanistically, MINT3 interacted with STING, selectively enhanced its K63-linked polyubiquitination and facilitated STING translocation to the Golgi, resulting in the enhancement of the STING and TBK1 interaction. Furthermore, MINT3 also facilitated HSV-1-induced innate antiviral immune responses and impaired HSV-1 replication in vitro and in vivo. Interestingly, we showed that the expression of MINT3 was dramatically elevated during HSV-1 infection, and ISD stimulation in macrophages. Thus, we have revealed a feedback mechanism for the regulation of the cGAS-STING pathway, providing a promising therapeutic target for the treatment of disorders triggered by aberrant STING activity.

A novel STING1-activating mutation is identified in a patient with childhood-onset systemic lupus erythematosus

Gain-of-function variants in stimulator of interferon genes (STING1) are known to cause STING-associated vasculopathy with onset in infancy (SAVI), a disorder characterized by cutaneous vasculopathy, interstitial lung disease (ILD), and systemic inflammation. Here, we report a novel STING1 N188H variant in a patient who met the classification criteria for systemic lupus erythematosus (SLE) but lacked typical SAVI features. In vitro assays demonstrated that the N188H variant drives constitutive STING activation and enhances type I interferon signaling. Consistent with this, the patient exhibited elevated interferon-stimulated genes (ISGs) expression, and RNA sequencing confirmed significant upregulation of type I IFN signaling compared to healthy controls. Our findings expand the molecular spectrum of STING-associated disease.

Repurposing oxiconazole to inhibit STING trafficking via OSBP and alleviate autoimmune pathology in Trex1-/- mice

The cGAS-STING pathway is a critical component of the innate immune response to cytosolic DNA, driving the production of type I interferons (IFNs) and pro-inflammatory cytokines. However, excessive activation of this pathway is associated with various autoimmune and inflammatory diseases. In this study, we evaluated the regulation of FDA-approved azole antifungal drugs on the cGAS-STING pathway. Among these drugs, oxiconazole, miconazole, and itraconazole demonstrate significant inhibitory effects, with oxiconazole showing the strongest activity. Our data demonstrates that oxiconazole significantly suppressed type I IFN production and downstream inflammatory responses in macrophages and fibroblasts stimulated with synthetic DNA or infected with HSV-1. Mechanistically, oxiconazole hindered STING trafficking via oxysterol-binding protein OSBP. Using the Listeria monocytogenes infection model and the Trex1-/- mouse disease model, both representing in vivo models of inflammation driven by excessive cGAS-STING activation, we demonstrate that oxiconazole enhanced bacterial clearance and reduced tissue damage in the Listeria monocytogenes infection model. Moreover, oxiconazole treatment significantly alleviated multi-organ inflammation and normalized aberrant IFN responses in the Trex1-/- autoimmune disease mouse model. These findings highlight the potential of oxiconazole as a promising therapeutic agent for STING-driven autoimmune and inflammatory diseases.

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.

French protocol for diagnosis and management of type 1 interferonopathies

Type I interferonopathies are rare genetic diseases characterised by excessive production or signalling of type I interferons (IFN-I), which are key cytokines in the antiviral response. These conditions lead to inappropriate activation of IFN-I pathway, even in the absence of viral stimulation. Over thirty monogenic conditions have been identified, with Aicardi-Goutières syndrome being the most common. The genes involved often relate to the metabolism of intracellular nucleic acids, their detection and signalling pathways, contributing to excessive IFN-I production or signalling. Features usually appear early in life, often within the first year, but diagnosis can also occur in adulthood. It is important to investigate whether there is a family history of consanguinity or vertically transmitted conditions. Key diagnostic features include: (1) Neurological: pseudo-encephalitic phase, psychomotor development retardation or regression, static encephalopathy, spasticity, microcephaly, aseptic lymphocytic meningitis. (2) Radiological: cerebral calcifications, white matter signal abnormalities, cerebral atrophy. (3) Dermatological: chilblains, skin necrosis, skin lesions suggestive of systemic lupus erythematosus (SLE), vasculitis, livedo, panniculitis. (4) Ophthalmological: early-onset glaucoma. (5) Musculoskeletal: myalgia, myositis, joint deformity with calcification, joint subluxation. (6) Pulmonary and renal: interstitial lung disease, pulmonary fibrosis, alveolar haemorrhage, lupus nephritis. (7) Laboratory evidence: lymphopenia, elevated erythrocyte sedimentation rate with normal C-reactive protein, positive antinuclear antibodies. Type I interferonopathies can mimic more common conditions like viral foetopathy or systemic lupus erythematosus. The disease expressivity is variable, even within the same family, making a detailed family history essential. The hallmark of these diseases is increased IFN-I levels in peripheral blood and/or cerebrospinal fluid, a test available only in specialised laboratories. Based on clinical suspicion, patients should be referred to an expert centre. There is no curative treatment to date. Management is multidisciplinary, focusing on symptomatic treatment. In cases of systemic or dermatological involvement, immunosuppressive therapy may be considered, though it increases susceptibility to viral infections. Vaccinations should be updated, with live vaccines contraindicated during immunosuppression unless otherwise specified (Supplemental 2). Monitoring development, supporting disability, and coordinating with social and medical institutions are also crucial aspects of care.

Topical Mupirocin Treatment Reduces Interferon and Myeloid Signatures in Cutaneous Lupus Erythematous Lesions Through Targeting of Staphylococcus Species

OBJECTIVE

Cutaneous lupus erythematosus (CLE) is an inflammatory skin manifestation of systemic lupus erythematosus. Type I interferons (IFNs) promote inflammatory responses and are elevated in CLE lesions. We recently reported that CLE lesions are frequently colonized with Staphylococcus aureus. Here, we follow up via a proof-of-concept study to investigate whether type I IFN and inflammatory gene signatures in CLE lesions can be modulated with mupirocin, a topical antibiotic treatment against S aureus-mediated skin infections.

METHODS

Participants with active CLE lesions (n = 12) were recruited and randomized into a week of topical treatment with either 2% mupirocin or petroleum jelly vehicle. Paired samples were collected before and after seven days of treatment to assess microbial lesional skin responses. Microbial samples from nares and lesional skin were used to determine baseline and posttreatment Staphylococcus abundance and microbial community profiles by 16S ribosomal RNA gene sequencing. Inflammatory responses were evaluated by bulk RNA sequencing of lesional skin biopsies.

RESULTS

We identified 173 differentially expressed genes in CLE lesions after topical mupirocin treatment. Decreased lesional Staphylococcus burden correlated with decreased IFN pathway signaling and inflammatory gene expression and barrier dysfunction. Interestingly, mupirocin treatment lowered skin monocyte levels, and this mupirocin-associated depletion of monocytes correlated with decreased inflammatory gene expression.

CONCLUSION

Mupirocin treatment decreased lesional Staphylococcus, and this correlated with decreased IFN signaling and inflammatory gene expression. This study suggests a topical antibiotic could be employed to decrease lupus skin inflammation and type I IFN responses by reducing Staphylococcus colonization.

Rebalancing redox homeostasis: A pivotal regulator of the cGAS-STING pathway in autoimmune diseases

Autoimmune diseases (ADs) arise from the breakdown of immune tolerance to self-antigens, leading to pathological tissue damage. Proinflammatory cytokine overproduction disrupts redox homeostasis across diverse cell populations, generating oxidative stress that induces DNA damage through multiple mechanisms. Oxidative stress-induced alterations in membrane permeability and DNA damage can lead to the recognition of double-stranded DNA (dsDNA), mitochondrial DNA (mtDNA) and micronuclei-DNA (MN-DNA) by DNA sensors, thereby initiating activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. While previous reviews have characterized cGAS-STING activation in autoimmunity, the reciprocal regulation between redox homeostasis and cGAS-STING activation remains insufficiently defined. This narrative review examines oxidative stress-mediated DNA damage as a critical driver of pathological cGAS-STING signaling and delineates molecular mechanisms linking redox homeostasis to autoimmune pathogenesis. Furthermore, we propose therapeutic strategies that combine redox restoration with the attenuation of aberrant cGAS-STING activation, thereby establishing a mechanistic foundation for precision interventions in autoimmune disorders. METHODS: The manuscript is formatted as a narrative review. We conducted a comprehensive search strategy using electronic databases such as PubMed, Google Scholar and Web of Science. Various keywords were used, such as "cGAS-STING," "Redox homeostasis," "Oxidative stress," "pentose phosphate pathway," "Ferroptosis," "mtDNA," "dsDNA," "DNA damage," "Micronuclei," "Reactive oxygen species," "Reactive nitrogen species," "Nanomaterial," "Autoimmune disease," "Systemic lupus erythematosus," "Type 1 diabetes," "Rheumatoid arthritis," "Multiple sclerosis," "Experimental autoimmune encephalomyelitis," "Psoriasis," etc. The titles and abstracts were reviewed for inclusion into this review. After removing duplicates and irrelevant studies, 174 articles met inclusion criteria (original research, English language).

Tanshinone IIA alleviates myocarditis in Trex1-D18N lupus-like mice by inhibiting the interaction between STING and SEC24C

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway serves as a crucial component of the innate immune defense, playing a vital role in combating pathogen invasion. However, its dysregulation or abnormal activation can trigger the development of autoimmune diseases. This study demonstrated that Tanshinone IIA, a major lipid-soluble component of Salvia miltiorrhiza Bunge, can effectively inhibit the activation of the cGAS-STING signaling pathway. Mechanistically, Tanshinone IIA inhibits the transport of STING from the ER to the Golgi apparatus by weakening the interaction between STING and SEC24C, thereby preventing the activation of the cGAS-STING signaling pathway. Furthermore, Tanshinone IIA significantly ameliorated myocardial inflammation in WT and Trex1D18N/D18N mice. Our research indicates that Tanshinone IIA shows potential therapeutic value in alleviating autoimmune diseases by effectively inhibiting the abnormal activation of the cGAS-STING pathway.

DNA binding effects of LDH nanozyme for aseptic osteolysis mitigation through STING pathway modulation

Persistent and intense inflammation is recognized as the primary cause of wear-particle-induced aseptic osteolysis, which ultimately resulting in aseptic prosthesis loosening. Reducing inflammation plays a significant role in mitigating osteolysis, and the STING pathway has emerged as a promising therapeutic target for its prevention. Specifically, damaged periprosthetic cells of aseptic osteolysis release double-stranded DNA (dsDNA) into the osteolytic microenvironment, serving as a specific stimulus for the STING pathway. Herein, we found that layered double hydroxide (LDH) nanozyme exhibited a robust DNA-binding capacity primarily mediated by van der Waals interactions, which showed superior performance in inhibiting dsDNA-induced inflammation of aseptic osteolysis. Importantly, such binding capability enabled effective co-loading LDH with STING inhibitor C176, thus facilitating inhibition of the STING pathway. Such synergistic actions contributed to ameliorate the inflammatory milieu and remodel the osteolysis microenvironment successfully to reduce cranial bone damage, which was confirmed on animal model of osteolysis. Collectively, this strategy demonstrated an effective approach by utilizing synergistic effects to establish a positive feedback loop in the treatment of osteolysis, thereby alleviating TiPs-induced periprosthetic osteolysis and preventing postoperative complications.

Design of Potent Small-Molecule Stimulator of Interferon Gene Inhibitor and Stimulator of Interferon Gene Mutant-Specific Degrader

Stimulator of interferon genes (STING) is involved in various autoimmune diseases. However, it is challenging to develop small-molecule STING inhibitors with potent activity. Herein, we designed a small-molecule STING inhibitor and STING mutant-specific degrader by binding two coupled pockets of a STING dimer. Structure optimization selected SI-24, SI-42, and SI-43 with low nanomolar activity to inhibit 2'3'-cyclic GMP-AMP (cGAMP)-induced STING activation and release of IFN-β and CXCL-10, which were far more potent than reported STING inhibitors. Moreover, the three lead compounds suppressed cGAMP-induced oligomerization of STING and phosphorylation of interferon regulatory factor 3 (IRF3) and STING. Surprisingly, SI-43 promoted mutant-specific and proteasome-independent degradation of STINGS154 and STINGM155. Subcutaneous or oral administration of SI-24, SI-42, and SI-43 reduced serum IFN-β and CXCL-10 in the cGAMP-induced autoimmune disease mouse model. Our dual-functional compounds provide a new strategy to investigate STING function through both inhibition and mutant-specific degradation in autoimmune diseases.

The pathogenesis, clinical presentations and treatment of monogenic systemic vasculitis

Many monogenic autoinflammatory diseases, including DADA2 (deficiency of adenosine deaminase 2), HA20 (haploinsufficiency of A20), SAVI (STING-associated vasculopathy with onset in infancy), COPA syndrome, LAVLI (LYN kinase-associated vasculopathy and liver fibrosis) and VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, present predominantly with vasculitis and constitute a substantial subgroup of vasculitic conditions associated with a 'probable aetiology'. The spectrum of monogenic vasculitis encompasses all sizes and types of blood vessel, ranging from large vessels to medium-size and small vessels, and from the arterial side to the venous side of the vasculature. Monogenic vasculitis typically starts early in life during infancy or childhood; VEXAS syndrome, which presents in late adulthood, is an exception. The activation of myeloid cells via inflammasome and nuclear factor-κB pathways, type I interferon-enhanced autoimmune mechanisms and/or dysregulated adaptive immune responses have an important role in the development of immune-mediated endothelial dysfunction and vascular damage. Genetic testing is essential for the diagnosis of underlying monogenic autoinflammatory diseases; however, the penetrance of genetic variants can vary. Increased awareness and recognition of distinctive clinical findings could facilitate earlier diagnosis and allow for more-targeted treatments.

AUP1 and UBE2G2 complex targets STING signaling and regulates virus-induced innate immunity

Stimulator of interferon genes (STING) is an endoplasmic reticulum (ER) signaling adaptor that is essential for the host immune response triggered by DNA pathogens. Precise regulation of STING is crucial for maintaining a balanced immune response and preventing harmful autoinflammation. Activation of STING requires its translocation from the ER to the Golgi apparatus. However, the mechanisms that maintain STING in its resting state remain largely unclear. Here, we find that deficiency of the ancient ubiquitous protein 1 (AUP1) causes spontaneous activation of STING and enhances the expression of type I interferons (IFNs) under resting conditions. Furthermore, deficiency of UBE2G2, a cofactor of AUP1, also promotes the abnormal activation of STING. AUP1 deficiency significantly enhances STING signaling induced by DNA virus, and AUP1 deficiency exhibits increased resistance to DNA virus infection in vitro and in vivo. Mechanistically, AUP1 may form a complex with UBE2G2 to interact with STING, preventing its exit from the ER membrane. Notably, infection with the RNA virus vesicular stomatitis virus (VSV) promotes the accumulation of lipid droplets (LDs) and AUP1 proteins. Additionally, AUP1 deficiency markedly inhibits the replication of VSV because AUP1 deficiency reduces lipid accumulation and alters the expression of lipid metabolism genes, such as carnitine palmitoyltransferase 1A (CPT1A), monoglyceride lipase (MGLL), and sterol regulatory element-binding transcription factor 1 (SREBF1). This study uncovers the essential roles of AUP1 in the STING signaling pathway and lipid metabolism pathway, highlighting its dual role in regulating virus replication.IMPORTANCEThe stimulator of interferon genes (STING) signaling cascade plays an essential role in coordinating innate immunity against DNA pathogens and autoimmunity. Precise regulation of the innate immune response is essential for maintaining homeostasis. In this study, we demonstrate that ancient ubiquitous protein 1 (AUP1) and UBE2G2 act as negative regulators of the innate immune response by targeting STING. Notably, AUP1 interacts with STING to retain STING in the endoplasmic reticulum (ER), preventing STING translocation and thereby limiting STING signaling in the resting state. In addition, deficiency of AUP1 markedly inhibits the replication of DNA virus and RNA virus. Our findings provide new insights into the regulation of STING signaling and confirm AUP1 has a dual role in regulating virus replication.

Microbial dysbiosis fuels STING-driven autoinflammation through cyclic dinucleotides

Aberrant activation of the stimulator of interferon genes (STING) pathway is a hallmark of autoinflammatory disorders such as STING-associated vasculopathy with onset in infancy (SAVI), characterized by systemic inflammation affecting blood vessels, skin, and lungs. Despite its clinical significance, the mechanisms linking STING activation to disease pathology remain poorly defined. In this study, we demonstrated that SAVI mice harboring the N153S STING mutation exhibit diverse disease phenotypes, with a subset developing severe colitis and diarrhea alongside exacerbated systemic inflammation. These diarrheal SAVI mice showed pronounced dysbiosis, marked by reduced short-chain fatty acid-producing bacteria and an enrichment of segmented filamentous bacteria. This microbial imbalance was accompanied by elevated levels of both microbial and host-derived cyclic dinucleotides (CDNs), potent activators of the STING pathway. Notably, antibiotic treatment ameliorated inflammation, underscoring the role of dysbiosis in driving STING-mediated autoinflammation. Furthermore, in SAVI patients, elevated systemic microbial and host-derived CDNs were observed. In conditions such as systemic lupus erythematosus (SLE)-a heterogeneous autoimmune disease with potential STING involvement-systemic microbial CDNs were significantly correlated with disease biomarkers, including type I interferon scores and anti-dsDNA antibodies. In contrast, no such correlations were observed in STING-independent conditions like rheumatoid arthritis (RA). Importantly, this study highlights that both microbial and host-derived CDNs are key drivers of STING activation, suggesting that personalized treatment strategies could target cGAS or the microbiome based on a patient's specific CDN profile. These findings position systemic CDNs as valuable biomarkers and therapeutic targets for STING-driven diseases.

cGAS mRNA-Based Immune Agonist Promotes Vaccine Responses and Antitumor Immunity

mRNA vaccines are a potent tool for immunization against viral diseases and cancer. However, the lack of a vaccine adjuvant limits the efficacy of these treatments. In this study, we used cGAS mRNA, which encodes the DNA innate immune sensor, complexed with lipid nanoparticles (LNP), to boost the immune response. By introducing specific mutations in human cGAS mRNA (hcGASK187N/L195R), we significantly enhanced cGAS activity, resulting in a more potent and sustained stimulator of interferon gene (STING)-mediated IFN response. cGAS mRNA-LNPs exhibited stimulatory effects on maturation, antigen engulfment, and antigen presentation by antigen-presenting cells, both in vitro and in vivo. Moreover, the hcGASK187N/L195R mRNA-LNP combination demonstrated a robust adjuvant effect and amplified the potency of mRNA and protein vaccines, which was a result of strong humoral and cell-mediated responses. Remarkably, the hcGASK187N/L195R mRNA-LNP complex, either alone or in combination with antigens, demonstrated exceptional efficacy in eliciting antitumor immunity. In addition to its immune-boosting properties, hcGASK187N/L195R mRNA-LNP exerted antitumor effects with IFNγ directly on tumor cells, further promoting tumor restriction. In conclusion, we developed a cGAS mRNA-based immunostimulatory adjuvant compatible with various vaccine forms to boost the adaptive immune response and cancer immunotherapies.

STING-∆C, a novel splice isoform of STING, inhibits DNA virus-induced innate immunity and autophagy

Stimulator of interferon genes (STING) plays a critical role in the innate immune response to cytosolic DNA, primarily activating type I interferons (IFNs). Although alternative splicing is known to modulate immune pathways, the influence of STING splice isoforms requires further exploration. Here, we identified STING-∆C, a novel splice isoform of STING generated by retention of intron 6, resulting in a truncated C-terminus. While STING-∆C shares its N-terminal domain with full-length STING, it contains a unique C-terminal sequence. STING-∆C acts as a dominant negative regulator of cGAS-STING signaling pathway by suppressing cGAS-, 2'3'-cGAMP-, and STING-mediated activation of the IFN response. Gain- and loss-of-function experiments showed that STING-∆C inhibited IFN production in response to double-stranded DNA and DNA virus, including HSV-1 and HPV. Furthermore, STING-∆C promoted HSV-1 replication and reduces STING-induced autophagy. Mechanistically, STING-∆C interacts with full-length STING, preventing its oligomerization and assembly with TBK1, a vital component of the STING-TBK1-IRF3 signalsome. This interaction blocks IRF3 phosphorylation and nuclear translocation, thereby halting IFN production. STING-∆C thus represents a newly identified splice isoform that negatively regulates cGAS-STING signaling. These findings broaden our understanding of STING's regulatory mechanisms and may guide therapeutic strategies for autoimmune diseases and viral infections linked to excessive STING activation.

Nano-delivery of STING agonists: Unraveling the potential of immunotherapy

The cyclic GMP-AMP synthetase-interferon gene stimulator (cGAS-STING) pathway possesses tremendous potential in immune responses, viral defense, and anti-tumor treatment. Currently, an increasing number of nanocarriers are being engineered to convey STING agonists, with the goal of booSTING the conveying capacity of cGAS-STING agonists and augment the therapeutic potency of STING agonists. In this review, we explore the mechanisms of cGAS-STING activators, the application of different nanocarriers in the STING pathway, and the application of nanocarriers in anti-tumor therapy, antiviral therapy and autoimmune diseases. Additionally, we also discuss the adverse effects of STING pathway activation and the challenges encountered in nano delivery, we hope that future research will delve into the development of new nanocarriers and the clinical translation of nanocarriers in STING-mediated immunotherapy. STATEMENT OF SIGNIFICANCE: The cyclic GMP-AMP synthetase-interferon gene stimulator (cGAS-STING) pathway possesses tremendous potential in immune responses, viral defense, and anti-tumor treatment. In this review, we first explore the activation mechanism of cGAS-STING signal pathway and the diverse array of nanocarriers that have been employed in the context of the STING pathway, such as natural carrier, lipid nanoparticles, polymeric nanoparticles, and inorganic nanoparticles, highlighting their unique properties and the challenges they present in clinical applications. Furthermore, we discuss the research progress regarding nanocarriers in STING-mediated immunotherapy, such as the application of nanocarriers in anti-tumor therapy, antiviral therapy and autoimmune diseases therapy. Finally, the side effects of STING pathway activation and the issues encountered in nano delivery will be discussed, hoping that future research will delve into the development of new nanocarriers and the clinical translation of nanocarriers in STING-mediated immunotherapy.

Role of STING Deficiency in Amelioration of Mouse Models of Lupus and Atherosclerosis

OBJECTIVE

Systemic lupus erythematosus (SLE) is a systemic autoimmune syndrome characterized by autoreactive responses to nucleic acids, dysregulation of the type I interferon (IFN-I) pathway, and accelerated atherosclerosis. The stimulator of IFN genes (STING), a cytosolic DNA sensor, has pathogenic implications in various inflammatory diseases. However, its specific role in SLE pathogenesis, particularly in tissue damage, remains unclear. This study aimed to elucidate the role of STING in murine models of Toll-like receptor 7 (TLR7)-driven lupus and atherosclerosis.

METHODS

A TLR7-driven lupus model was induced using imiquimod (IMQ) in wild-type (WT) and STING knockout (Sting1-/-) mice on a B6 background. Mice were assessed for organ involvement, serum autoantibodies, and innate and adaptive immune responses. Additionally, Sting1-/- mice were backcrossed to apolipoprotein E knockout (Apoe-/-) mice, and both Apoe-/- and Apoe-/-Sting1-/- mice were fed a high-fat chow diet to induce atherosclerosis. Phenotypic assessments were conducted.

RESULTS

Compared with IMQ-treated WT mice, Sting1-/- mice exhibited reduced disease severity in the lupus-like phenotype, characterized by decreased splenomegaly, lower renal immune complex deposition and renal damage, diminished expansion of myeloid cells, and reduced activation of T and B lymphocytes. IMQ-induced DNA release associated with IFN-β production and subsequent IFN-induced responses were attenuated in Sting1-/- mice. DNase I treatment mitigated IMQ-induced proinflammatory responses in WT mice but had no effect in Sting1-/- mice. Furthermore, STING deficiency conferred protection against vascular damage and reduced atherosclerosis burden, accompanied by decreased IFN-I production. Human monocyte-derived macrophages treated with IFN-I significantly internalized more acetylated low-density lipoprotein when compared with untreated cells, whereas an association between oxidized nucleic acids and disease activity and vascular damage was found in human SLE.

CONCLUSION

These findings highlight a pathogenic role of STING and downstream IFN responses in TLR7-driven autoimmunity, vascular damage and atherosclerosis, supporting a therapeutic potential for STING inhibition in SLE treatment. Further research is warranted to elucidate the mechanisms underlying STING's involvement in these processes and to explore the feasibility of targeting STING as a therapeutic strategy in SLE and related autoimmune disorders.

XMT-2056, a HER2-Directed STING Agonist Antibody-Drug Conjugate, Induces Innate Antitumor Immune Responses by Acting on Cancer Cells and Tumor-Resident Immune Cells

PURPOSE

Targeted tumor delivery may be required to potentiate the clinical benefit of innate immune modulators. The objective of the study was to apply an antibody-drug conjugate (ADC) approach to STING agonism and develop a clinical candidate.

EXPERIMENTAL DESIGN

XMT-2056, a HER2-directed STING agonist ADC, was designed, synthesized, and tested in pharmacology and toxicology studies. The ADC was compared with a clinical benchmark intravenously administered a STING agonist.

RESULTS

XMT-2056 achieved tumor-targeted delivery of the STING agonist upon systemic administration in mice and induced innate antitumor immune responses; single dose administration of XMT-2056 induced tumor regression in a variety of tumor models with high and low HER2 expressions. Notably, XMT-2056 demonstrated superior efficacy and reduced systemic inflammation compared with a free STING agonist. XMT-2056 exhibited concomitant immune-mediated killing of HER2-negative cells specifically in the presence of HER2-positive cancer cells, supporting the potential for activity against tumors with heterogeneous HER2 expression. The antibody does not compete for binding with trastuzumab or pertuzumab, and a benefit was observed when combining XMT-2056 with each of these therapies as well as with trastuzumab deruxtecan ADC. The combination of XMT-2056 with anti-PD-1 conferred benefit on antitumor activity and induced immunologic memory. XMT-2056 was well tolerated in nonclinical toxicology studies.

CONCLUSIONS

These data provide a robust preclinical characterization of XMT-2056 and provide rationale and strategy for its clinical evaluation.

Therapeutic Approaches for Periodic Fever Syndromes and Autoinflammatory Disorders

As immunologists, we evaluate patients with a large spectrum of disorders, which include impaired immunity, autoimmunity, and autoinflammatory features. Recent discoveries in inflammatory pathways have elucidated disease pathogenesis and also treatment targets to best focus on the most involved cytokine pathways. Autoinflammatory diseases center around the inability to quell a nonantigenic inflammatory response due to missing suppressive components of the immune system. Management is mostly directed to minimize the sequelae of uncontrolled, chronic inflammation. In this article, an array of classic periodic fever syndromes will be discussed along with disorders involving dysregulated IL-1, TNF, NF-kb, and Type 1 interferon pathways.

cGAS-STING: mechanisms and therapeutic opportunities

The cGAS-STING pathway plays a crucial role in the innate immune system by detecting mislocalized double-stranded DNA (dsDNA) in the cytoplasm and triggering downstream signal transduction. Understanding the mechanisms by which cGAS and STING operate is vital for gaining insights into the biology of this pathway. This review provides a detailed examination of the structural features of cGAS and STING proteins, with a particular emphasis on their activation and inhibition mechanisms. We also discuss the novel discovery of STING functioning as an ion channel. Furthermore, we offer an overview of key agonists and antagonists of cGAS and STING, shedding light on their mechanisms of action. Deciphering the molecular intricacies of the cGAS-STING pathway holds significant promise for the development of targeted therapies aimed at maintaining immune homeostasis within both innate and adaptive immunity.

STING: a multifaced player in cellular homeostasis

The stimulator of interferon gene (STING) is an important innate immune mediator of the cytoplasmic DNA sensing pathway. As a mediator known for its role in the immune response to infections, STING is also surprisingly at the center of a variety of non-infectious human diseases, including cancer, autoimmune diseases and neurodegenerative diseases. Recent studies have shown that STING has many signaling activities, including type I interferon (IFN-I) and other IFN-independent activities, many of which are poorly understood. STING also has the unique property of being continuous transported from the ER to the Golgi then to the lysosome. Mutations of STING or trafficking cofactors are associated with human diseases affecting multiple immune and non-immune organs. Here, we review recent advances in STING trafficking and signaling mechanisms based in part on studies of STING-associated monogenic inborn error diseases.

The emerging concept of ANCA-associated vasculitis related to inborn errors of immunity

ANCA-associated vasculitis (AAV) is a group of rare small vessels vasculitis that preferentially affect the kidneys, lungs and upper airways. Although the detailed pathophysiology remains unclear, genetic background has been shown to play a role in sporadic forms of AAV. The discovery of these susceptibility genes (and associated biological pathways) involved in AAV have shaped the current understanding of AAV pathophysiology. In addition to common genetic polymorphisms, specific rare inborn errors of immunity (IEI) have been described with a high frequency of ANCA (antineutrophil cytoplasmic antibodies) positivity and vasculitis features in young individuals (in addition to other manifestations). A systematic literature search revealed that patients with pathogenic variants in COPA, STING1, DNASE1L3, and PIK3CD are at increased risk of developing ANCA and AAV features, including alveolar hemorrhage, interstitial lung disease, pauciimmune glomerulonephritis, and upper airways involvement (septum perforation, saddle-nose deformity, chronic nasal/sinuses ulceration). Some of these IEI may also present with a mixed phenotype and/or auto-antibodies profile associating features of AAV and other autoimmune diseases (in particular systemic lupus erythematosus). Notably, a proportion of reports and series lack serological (ANCA specificity and titers) and/or histopathological data, making challenging to assess the likelihood for ANCA pathogenicity in some patients with IEI (as opposed to unspecific signs of biologic autoimmunity). This point is nonetheless essential to make appropriate therapeutic decisions. In addition, since most of the genes mentioned above are involved in the type 1 interferon signaling, the role of this pathway in AAV etiopathogenesis deserves further investigation. In this review, we will describe these IEI, their overlap with sporadic AAV, and their evocative features. Next, we will discuss how these monogenic conditions might inform our general understanding of AAV pathophysiology. We also propose some directions for future research in order to better define the link between ANCA and IEI. Finally, we will consider how making the diagnosis of an IEI in a patient with AAV features might impact individual management.

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.

Cell-Autonomous Immunity: From Cytosolic Sensing to Self-Defense

As an evolutionarily conserved and ubiquitous mechanism of host defense, non-immune cells in vertebrates possess the intrinsic ability to autonomously detect and combat intracellular pathogens. This process, termed cell-autonomous immunity, is distinct from classical innate immunity. In this review, we comprehensively examine the defense mechanisms employed by non-immune cells in response to intracellular pathogen invasion. We provide a detailed analysis of the cytosolic sensors that recognize aberrant nucleic acids, lipopolysaccharide (LPS), and other pathogen-associated molecular patterns (PAMPs). Specifically, we elucidate the molecular mechanisms underlying key signaling pathways, including the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mitochondrial antiviral signaling (MAVS) axis, and the guanylate-binding proteins (GBPs)-mediated pathway. Furthermore, we critically evaluate the involvement of these pathways in the pathogenesis of various diseases, including autoimmune disorders, inflammatory conditions, and malignancies, while highlighting their potential as therapeutic targets.

Oligomerization of STING and Chemical Regulatory Strategies

Stimulator of interferon genes (STING) plays a crucial role in innate immunity. Upon the recognition of cytosolic dsDNA, STING undergoes several structural changes, with oligomerization playing a key role in initiating a cascade of immune responses. Therefore, controlling the STING pathway by manipulating STING oligomerization is a practical strategy. This review focuses on the detailed mechanism of STING oligomerization, highlighting its decisive role. It also describes oligomerization-based strategies to regulate STING protein, such as the use of small-molecule agonists and biomacromolecules, highlighting their interaction modes and potential therapeutic applications. This knowledge may lead to the development of innovative approaches for treating cancer and immune disorders.

Leveraging genetics to understand ADAR1-mediated RNA editing in health and disease

Endogenous, long double-stranded RNA (dsRNA) can resemble viral dsRNA and be recognized by cytosolic dsRNA sensors, triggering autoimmunity. Genetic studies of rare, inherited human diseases and experiments using mouse models have established the importance of adenosine-to-inosine RNA editing by the enzyme adenosine deaminase acting on RNA 1 (ADAR1) as a critical safeguard against autoinflammatory responses to cellular dsRNA. More recently, human genetic studies have revealed that dsRNA editing and sensing mechanisms are involved in common inflammatory diseases, emphasizing the broader role of dsRNA in modulating immune responses and disease pathogenesis. These findings have highlighted the therapeutic potential of targeting dsRNA editing and sensing, as exemplified by the emergence of ADAR1 inhibition in cancer therapy.

cGAS-STING signaling in melanoma: regulation and therapeutic targeting

Melanocytes are the source of the skin cancer known as melanoma. It usually affects the viscera, mucous membranes, and skin. Even so, melanoma only makes for 7% of all skin cancer occurrences. By triggering the generation of type I interferons (IFN-I) and inflammatory cytokines upon identifying microbial DNA, the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway promotes anti-microbial innate immunity. A growing body of research indicates that antitumor immunity depends on the cGAS-STING axis being activated. The cGAS-STING-regulated downstream cytokines, particularly IFN-I, act as linkages between adaptive and innate immunity. As a result, an increasing amount of research has concentrated on the synthesis and screening of agonists of the STING pathway. As a result, an increasing amount of research has concentrated on the synthesis and screening of agonists of the STING pathway. The many implications of the cGAS-STING pathway in the pathophysiology and therapy of melanoma are thoroughly examined in this study. Our research highlights the significance of the cGAS-STING pathway in melanoma and identifies it as a key target for boosting immunity against tumors.

A mechanoresponsive heterochiral hydrogelator as a potential matrix metalloproteinase-2 inhibitor: unravelling its anti-inflammatory efficacy in vitro and in vivo

Inflammations are innate and adaptive immune responses that get instigated in reciprocation to infection. However, if left unchecked, they pose a formidable challenge in clinical settings. In search of user-friendly solutions, our work delineated a rational combinatorial strategy, harnessing chiral orchestration in a triphenylalanine fragment and appending it to δ-amino valeric acid at the N-terminus (hydrogelators I-VIII) such that a potential matrix metalloproteinase-2 (MMP2) inhibitor could be fished out from the design. Our rigorous investigations revealed that from a pool of eight constructs, hydrogelator VIII, with a DLL configuration at the triphenylalanines, displayed excellent MMP2 inhibitory activities in vitro, which was further supported by molecular modelling studies. Besides, the β-sheet structured scaffold not only showed substantial antibacterial efficacy against the Gram-positive pathogens S. aureus, S. mutans, B. subtilis and E. fecalis but also exhibited proteolytic stability and biocompatibility towards mammalian cells. Furthermore, the scaffold possessed high mechanical strength at physiological pH and mechanical stress-triggered gel-sol-gel transition properties. Finally, the in vivo efficacy was evaluated using an air pouch model of acute inflammation in albino mice that certified hydrogelator VIII as a promising anti-inflammatory therapeutic to pave the path for future healthcare management.

The cGAS‒STING pathway in cancer immunity: mechanisms, challenges, and therapeutic implications

Innate immunity represents the body's first line of defense, effectively countering the invasion of external pathogens. Recent studies have highlighted the crucial role of innate immunity in antitumor defense, beyond its established function in protecting against external pathogen invasion. Enhancing innate immune signaling has emerged as a pivotal strategy in cancer therapy. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway is a key innate immune signal that activates the immune response and exerts antitumor effects; this is primarily attributed to the DNA receptor function of cGAS, which recognizes exogenous DNA to activate downstream STING signaling. This, in turn, promotes the activation of downstream targets such as IRF-3(Interferon Regulatory Factor 3) and NF-κB, leading to the secretion of type I interferons and proinflammatory cytokines, thereby increasing cellular immune activity. The activation of the cGAS-STING pathway may thus play a crucial role in enhancing anticancer immunity. In this paper, we reviewed the role of cGAS-STING signaling in anticancer immunity and its molecular mechanisms. Additionally, we briefly discuss the current applications of the cGAS-STING pathway in cancer immunity, summarize recent developments in STING agonists, and address the challenges facing the use of the cGAS-STING pathway in cancer therapy. Finally, we provide insights into the role of the cGAS‒STING pathway in cancer and propose new directions for cancer immunotherapy.

The Application of scRNA-Seq in Heart Development and Regeneration

Single-cell RNA sequencing (scRNA-seq) is a rapidly developing and useful technique for elucidating biological mechanisms and characterizing individual cells. Tens of millions of patients worldwide suffer from heart injuries and other types of heart disease. Neonatal mammalian hearts and certain adult vertebrate species, such as zebrafish, can fully regenerate after myocardial injury. However, the adult mammalian heart is unable to regenerate the damaged myocardium. scRNA-seq provides many new insights into pathological and normal hearts and facilitates our understanding of cellular responses to cardiac injury and repair at different stages, which may provide critical clues for effective therapies for adult heart regeneration. In this review, we summarize the application of scRNA-seq in heart development and regeneration and describe how important molecular mechanisms can be harnessed to promote heart regeneration.

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.

The CGAS-STING1 Pathway as a Mediator of Innate Immune Response in Cardiovascular Disease

The innate immune response, a rapid and cell-autonomous response of the cell to the pathogens, recognizes the external as well as the internal pathogens, such as self-DNA, released from the damaged cells. The response activates a set of molecules that induce the expression of proinflammatory cytokines and chemokines and leads to inflammation, fibrosis, and cell death. The innate immune response comprised of DNA-sensing protein cyclic guanosine monophosphate-adenosine monophosphate synthase (CGAS) and its downstream molecules, the stimulator of interferon genes 1 (STING1), TANK-binding kinase 1 (TBK1), interferon regulatory factor 3 (IRF3), and nuclear factor kappa B (NFκB), are activated in several cardiovascular diseases, including hereditary cardiomyopathies, myocardial infarction, hypertension, atherosclerosis, and aortic aneurysm. The genetic deletion of key molecules in this pathway, such as CGAS, STING1, and interferon regulatory factor 3, affords salubrious effects, including improving survival and cardiac dysfunction, rendering the CGAS-STING1 pathway an attractive therapeutic target in cardiovascular disease.

Palmitic acid exacerbates experimental autoimmune uveitis by activating T helper 17 cells via regulating STING signaling

Recent studies found that palmitic acid (PA), the most abundant fatty acid in human body, was increased in uveitis patients. However, its exact effect on uveitis has not been clarified. In this study, experimental autoimmune uveitis (EAU), an animal model of human uveitis, was successfully induced with interphotoreceptor retinoid-binding protein (IRBP) 651-670 and pertussis toxin. The immunized mice were treated with daily intragastric PA or vehicle from day 1-14. The results showed that PA could aggravate EAU activities and increase the proportion of T helper (Th) 17 cells as well as mRNA expression level of Il17a. There were no significant changes in Th1/Treg cell responses between these two groups. In vitro experiments showed that PA treatment could promote IRBP-specific Th17 cell response in association with increased proportion of Th17 cells as well as up-regulated expression of IL-17A. Proteomics showed an increased expression of stimulator of interferon genes protein (STING) in PA-treated mice as compared to vehicle-treated mice. H-151, a potent antagonist of STING, attenuated the activities of EAU and Th17 cell responses induced by PA. Moreover, NF-κB/IL-6 signaling pathway was found to be downregulated after H-151 treatment. Collectively, PA could exacerbate EAU severity possibly through the activation of Th17 cells mediated by up-regulating STING.

Decoding Immunobiology Through Genetic Errors of Immunity

Throughout biology, the pursuit of genotype-phenotype relationships has provided foundational knowledge upon which new concepts and hypotheses are built. Genetic perturbation, whether occurring naturally or in experimental settings, is the mainstay of mechanistic dissection in biological systems. The unbiased discovery of causal genetic lesions via forward genetics in patients who have a rare disease elucidates a particularly impactful set of genotype-phenotype relationships. Here, we review the field of genetic errors of immunity, often termed inborn errors of immunity (IEIs), in a framework aimed at highlighting the powerful real-world immunology insights provided collectively and individually by these (approximately) 500 disorders. By conceptualizing essential immune functions in a model of the adaptive arsenal of rapid defenses, we organize IEIs based on immune circuits in which sensors, relays, and executioners cooperate to carry out pathogen clearance functions in an effective yet regulated manner. We review and discuss findings from IEIs that not only reinforce known immunology concepts but also offer surprising phenotypes, prompting an opportunity to refine our understanding of immune system function.

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.

Progress Update on STING Agonists as Vaccine Adjuvants

Low antigen immunogenicity poses a significant challenge in vaccine development, often leading to inadequate immune responses and reduced vaccine efficacy. Therefore, the discovery of potent immune-enhancing adjuvants is crucial. STING (stimulator of interferon genes) agonists are a promising class of adjuvants which have been identified in various immune cells and are activated in response to DNA fragments, triggering a broad range of type-I interferon-dependent immune responses. Integrating STING agonists with vaccine components is an ideal strategy to bolster vaccine-induced immunity to infections and cancer cells. Several STING agonists are currently under investigation in preclinical studies and clinical trials; however, some have shown limited efficacy, while others exhibit off-target effects. To ensure safety, they are typically delivered with carriers that exhibit high biocompatibility and insolubility. In this review, we present the latest research on natural and synthetic STING agonists that have been effectively used in vaccine development, and summarize their application in adjuvant preventive and therapeutic vaccines. Additionally, we discuss the safety of STING agonists as vaccine adjuvants by reviewing potential delivery strategies. Overall, incorporating STING agonists into vaccine formulations represents a significant advancement in vaccine research with the potential to significantly enhance immune responses and improve vaccine efficacy. However, ongoing research is still required to identify the most effective and safe delivery strategies for STING agonists, as well as to evaluate their long-term safety and efficacy in clinical trials.

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.

Tissue inflammation induced by constitutively active STING is mediated by enhanced TNF signaling

Constitutive activation of STING by gain-of-function mutations triggers manifestation of the systemic autoinflammatory disease STING-associated vasculopathy with onset in infancy (SAVI). In order to investigate the role of signaling by tumor necrosis factor (TNF) in SAVI, we used genetic inactivation of TNF receptors 1 and 2 in murine SAVI, which is characterized by T cell lymphopenia, inflammatory lung disease, and neurodegeneration. Genetic inactivation of TNFR1 and TNFR2, however, rescued the loss of thymocytes, reduced interstitial lung disease, and neurodegeneration. Furthermore, genetic inactivation of TNFR1 and TNFR2 blunted transcription of cytokines, chemokines, and adhesions proteins, which result from chronic STING activation in SAVI mice. In addition, increased transendothelial migration of neutrophils was ameliorated. Taken together, our results demonstrate a pivotal role of TNFR signaling in the pathogenesis of SAVI in mice and suggest that available TNFR antagonists could ameliorate SAVI in patients.

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.

Dynamic STING repression orchestrates immune cell development and function

STING is an essential component of the innate immune system, yet homeostatic STING expression patterns and regulation are unknown. Using Sting1IRES-EGFP reporter and conditional Sting1 transgenic mice, we found that regulation of STING expression is critical for immune cell development and functionality. STING expression was repressed in neutrophils, and forced STING expression or signaling drove systemic inflammatory disease. During T lymphocyte development, STING expression was restricted at the double-positive stage via epigenetic silencing by DNA methyltransferase 1. Forced STING expression or signaling impaired T lymphocyte development independent of type I interferon and promoted lineage commitment to innate-like γδ T cells over adaptive αβ T cells. In the tumor microenvironment, CD8+ T lymphocytes repressed STING expression, correlating with features of T cell exhaustion in syngeneic mouse tumors and human colorectal cancer. Our data demonstrate the necessity of controlled, rather than ubiquitous, STING expression, uncovering a previously unappreciated dimension of STING pathobiology.

Keeping up with recent developments in immunodeficiency

Inborn errors of immunity (IEIs) are a rapidly expanding group of monogenetic disorders affecting the immune system. Advancements in genetic testing and functional validation studies have accelerated the pace of IEI gene discovery and mechanism of disease, particularly in the past 5 years. To keep up with this rapid expansion, the International Union of Immunological Societies Expert Committee has periodically, since 1999, released updated IEI classifications with corresponding genotypic and phenotypic catalogues with its most recent update in 2022. Now, there are more than 485 monogenetic disorders of the immune system described among 10 main groups of classification. This article reviews recent clinical developments in IEI, including a closer look at some of the more recently described IEI disorders. In particular, we highlight a few disorders with the following clinical phenotypes of IEI: severe atopy, immunodeficiency with immune dysregulation, immune dysregulation with lymphoproliferation, autoinflammation, and innate phenotype. To aid the clinician, we also provide a diagnostic approach to use when there is suspicion of IEI and a discussion of management and treatment.

Somatic mosaicism in genetic errors of immunity

Genetic mosaicism in somatic cells can lead to the presence of pathogenic variants in a subset of immune cells causing genetic errors of immunity, often phenocopying germline inborn errors of immunity. Over the last 2 decades, significant progress has been made in the identification of these disorders in patients, including discovery of new diseases. Diagnosis of disease-causing somatic mosaicism provides a target for treatment and monitoring of patients and has implications for genetic counseling. However, there continue to be barriers in the identification of somatic mosaicism, particularly for the clinical diagnosis of patients, based on the limitations of current diagnostic sequencing and analysis approaches. This review focuses on how somatic mosaicism can lead to genetic errors of immunity, the genes known to be associated with somatic genetic errors of immunity, and challenges in the field for accurate diagnosis of patients.

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.

Just Autoimmunity? The Role of the Innate Immune Response in Lupus

ABSTRACT

Systemic lupus erythematosus is considered a prototype of human autoimmune disease based on the appearance of multiple autoantibodies, some of which can have a direct pathogenic effect on tissues. Most therapeutic modalities aim to check the enhanced humoral responses by targeting T and B cells with conventional or biologic drugs. However, in some cases, the clinical response is limited and frequently takes a high toll of toxicity in patients. The last 2 decades have brought up novel discoveries showing profound disturbances of innate immune cell function in systemic lupus erythematosus, including dysregulated NETosis, increased apoptosis, type 1 interferon, and granulopoiesis signatures that are grounded in basic cell biology abnormalities, including response to excessive oxidative stress, mitochondrial dysfunction, and upregulation of the cGAS-STING pathway. Whether the prominent autoimmunity component of lupus patients is sufficient to drive this chronic disease or follows a breakdown of innate immune homeostasis in response to the environmental factors triggering disease is the subject of this revision.

Sustained Interferon Signature Suppression With Anifrolumab in a Patient With STING-Associated Vasculopathy with Onset in Infancy Refractory to JAK Inhibitor and Dazukibart Therapy

OBJECTIVE

The objective was to report the safety and efficacy of an anti-IFNAR1 antibody (anifrolumab) in a patient with STING-associated vasculopathy with onset in infancy (SAVI) who presented with vasculitic ulcers and systemic inflammation refractory to JAK inhibition (JAKi) and to the interferon-β-neutralizing monoclonal antibody dazukibart.

METHODS

A patient with SAVI and a de novo STING1 p.(Asn154Ser) mutation, a known pathogenic variant, and uncontrolled disease received 21 doses of dazukibart under a compassionate use investigational new drug protocol, which was followed by treatment with the anti-IFNAR1 antibody anifrolumab. Clinical and laboratory parameters, including wound healing, whole-blood type I interferon (IFN I) signature, and safety markers were closely monitored throughout both treatment periods.

RESULTS

Despite initial reductions in C-reactive protein levels and IFN I scores following dazukibart administration, the patient experienced rebound inflammation and recurrent vasculitic lesions. Dazukibart dose adjustments failed to sustainably control IFN I signaling. Subsequent combination therapy of baricitinib and tocilizumab proved partially effective. Treatment with anifrolumab, an IFNAR1 blocker, in conjunction with tocilizumab led to sustained suppression of IFN I scores, allowed discontinuation of JAKi, and resulted in significant improvement in vasculitic wounds.

CONCLUSION

This case underscores the challenges in treating patients with SAVI and highlights the utility of IFN I scores as a theragnostic biomarker. Although high-dose JAKi and dazukibart failed to achieve sustained control of IFN I signaling, treatment with anifrolumab durably suppressed IFN scores and demonstrated promising efficacy, which allows for the investigation of the role of IFN I signaling in the disease pathogenesis of SAVI and other interferonopathies in future clinical trials.

Phase I dose-escalation and pharmacodynamic study of STING agonist E7766 in advanced solid tumors

E7766 is a novel stimulator of interferon genes (STING) agonist, capable of potent activation of immune cells and generating strong antitumor response in preclinical murine tumor models. Here we present the safety, efficacy, and biomarker results of the first-in-human phase I/Ib study of intratumoral E7766 in patients with advanced solid tumors. Eligible patients with relapsing/refractory cancers (n=24) were enrolled in dose-escalating cohorts to receive intratumoral injections of E7766 from 75 to 1000 µg. The most frequent treatment-related treatment-emergent adverse events were chills (50.0%; 85.7%), fever (40.0%; 85.7%), and fatigue (30.0%; 35.7%) in patients who received non-visceral and visceral injections, respectively. Eight patients (33.3%) achieved stable disease as their best response per modified Response Evaluation Criteria In Solid Tumors version 1.1 with variability between injected and non-injected lesions. Plasma levels of IFN-α, IFN-β, IFN-γ, TNF-α, IL-6, IP-10, MCP1, and MIP1b transiently increased in all evaluable patients within 10 hours postinjection, then dropped to baseline levels. Levels of blood and tumor gene expression increased in most interferon-related and STING genes tested. Further increases in programmed death ligand 1 and cluster of differentiation 8 expression at both the RNA and protein levels were also observed in some patients across dose levels. In total, E7766 generated on-target pharmacodynamic effects in patients with solid tumors. Further exploration in a homogeneous patient population is necessary to assess efficacy.