Synergistically targeting synovium STING pathway for rheumatoid arthritis treatment

A dual dynamically cross-linked hydrogel promotes rheumatoid arthritis repair through ROS initiative regulation and microenvironment modulation-independent triptolide release

High oxidative stress and inflammatory cell infiltration are major causes of the persistent bone erosion and difficult tissue regeneration in rheumatoid arthritis (RA). Triptolide (TPL) has become a highly anticipated anti-rheumatic drug due to its excellent immunomodulatory and anti-inflammatory effects. However, the sudden drug accumulation caused by the binding of "stimulus-response" and "drug release" in a general smart delivery system is difficult to meet the shortcoming of extreme toxicity and the demand for long-term administration of TPL. Herein, we developed a dual dynamically cross-linked hydrogel (SPT@TPL), which demonstrated sensitive RA microenvironment regulation and microenvironment modulation-independent TPL release for 30 days. The abundant borate ester/tea polyphenol units in SPT@TPL possessed the capability to respond and regulate high reactive oxygen species (ROS) levels on-demand. Meanwhile, based on its dense dual crosslinked structure as well as the spontaneous healing behavior of numerous intermolecular hydrogen bonds formed after the breakage of borate ester, TPL could remain stable and slowly release under high ROS environments of RA, which dramatically reduced the risk of TPL exerting toxicity while maximized its long-term efficacy. Through the dual effects of ROS regulation and TPL sustained-release, SPT@TPL alleviated oxidative stress and reprogrammed macrophages into M2 phenotype, showing marked inhibition of inflammation and optimal regeneration of articular cartilage in RA rat model. In conclusion, this hydrogel platform with both microenvironment initiative regulation and TPL long-term sustained release provides a potential scheme for rheumatoid arthritis.

Pharmacological potential of cyclic nucleotide signaling in immunity

Cyclic nucleotides are important signaling molecules that play many critical physiological roles including controlling cell fate and development, regulation of metabolic processes, and responding to changes in the environment. Cyclic nucleotides are also pivotal regulators in immune signaling, orchestrating intricate processes that maintain homeostasis and defend against pathogenic threats. This review provides a comprehensive examination of the pharmacological potential of cyclic nucleotide signaling pathways within the realm of immunity. Beginning with an overview of the fundamental roles of cAMP and cGMP as ubiquitous second messengers, this review delves into the complexities of their involvement in immune responses. Special attention is given to the challenges associated with modulating these signaling pathways for therapeutic purposes, emphasizing the necessity for achieving cell-type specificity to avert unintended consequences. A major focus of the review is on the recent paradigm-shifting discoveries regarding specialized cyclic nucleotide signals in the innate immune system, notably the cGAS-STING pathway. The significance of cyclic dinucleotides, exemplified by 2'3'-cGAMP, in controlling immune responses against pathogens and cancer, is explored. The evolutionarily conserved nature of cyclic dinucleotides as antiviral agents, spanning across diverse organisms, underscores their potential as targets for innovative immunotherapies. Findings from the last several years have revealed a striking diversity of novel bacterial cyclic nucleotide second messengers which are involved in antiviral responses. Knowledge of the existence and precise identity of these molecules coupled with accurate descriptions of their associated immune defense pathways will be essential to the future development of novel antibacterial therapeutic strategies. The insights presented herein may help researchers navigate the evolving landscape of immunopharmacology as it pertains to cyclic nucleotides and point toward new avenues or lines of thinking about development of therapeutics against the pathways they regulate.

cGAS-STING pathway in pathogenesis and treatment of osteoarthritis and rheumatoid arthritis

Osteoarthritis (OA) and Rheumatoid Arthritis (RA) are significant health concerns with notable prevalence and economic impact. RA, affecting 0.5% to 1.0% of the global population, leads to chronic joint damage and comorbidities. OA, primarily afflicting the elderly, results in joint degradation and severe pain. Both conditions incur substantial healthcare expenses and productivity losses. The cGAS-STING pathway, consisting of cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING), is a crucial component of mammalian immunity. This pathway is responsible for detecting foreign DNA, particularly double-stranded DNA (dsDNA), triggering innate immune defense responses. When cGAS recognizes dsDNA, it catalyzes the synthesis of cyclic GMP-AMP (cGAMP), which then binds to and activates STING. Activated STING, in turn, initiates downstream signaling events leading to the production of interferons and other immune mediators. The cGAS-STING pathway is essential for defending against viral infections and maintaining cellular balance. Dysregulation of this pathway has been implicated in various inflammatory diseases, including arthritis, making it a target for potential therapeutic interventions. Understanding the intricate molecular signaling network of cGAS-STING in these arthritis forms offers potential avenues for targeted therapies. Addressing these challenges through improved early detection, comprehensive management, and interventions targeting the cGAS-STING pathway is crucial for alleviating the impact of OA and RA on individuals and healthcare systems. This review offers an up-to-date comprehension of the cGAS-STING pathway's role in the development and therapeutic approaches for these arthritis types.

Association Between Composite Dietary Antioxidant Index and the Risk of Endometriosis-Related Rheumatoid Arthritis in Women of Childbearing Age: A Cross-Sectional Study Based on the National Health and Nutrition Examination Survey Database

Purpose

To evaluate the association between Composite Dietary Antioxidant Index (CDAI) and the risk of endometriosis (EM)-related rheumatoid arthritis (RA) in women of childbearing age.

Methods

Using the data from the National Health and Nutrition Examination Survey database, this cross-sectional study included women of childbearing age. The CDAI was obtained by summing the standardized Z-values of the dietary intakes. EM was diagnosed based on a questionnaire-based survey. The outcome of this study was the presence of RA, which was defined by a questionnaire. The associations of CDAI and EM with the risk of RA were determined using weighted logistic analysis. Additive interaction was evaluated using the relative excess risk due to interaction (RERI), the attributable proportion due to interaction (AP), and the synergy index (S).

Results

In total, 3803 patients were included, of which 74 patients (1.99%) were with RA. A lower CDAI [odds ratio (OR): 1.85, 95% confidence interval (CI): 1.12 to 3.04, P= 0.015] and the presence of EM (OR: 3.05, 95% CI: 1.19 to 7.81, P= 0.023) was associated with the risk of RA. The result demonstrated an additive interaction of a lower CDAI and the presence of EM on the risk of RA (OR: 6.19, 95% CI: 2.33 to 16.43, P <0.001, P of trend =0.007). Nevertheless, there was no significant additive interaction after being assessed by the RERI, AP, and S. However, a joint effect of a lower CDAI and EM on the risk of RA (OR: 3.94, 95% CI: 1.35 to 11.51, P= 0.013) was observed.

Conclusion

Our study identified EM, and lower CDAI, was related to the risk of RA. Lower CDAI score was also associated with the risk of EM-related RA. This study indicates the importance of antioxidant intake in daily diet for the management of EM-related RA.

STING inhibition alleviates bone resorption in apical periodontitis

AIM

The goal of this study was to investigate the potential effects of an immunotherapeutic drug targeting STING to suppress the overreactive innate immune response and relieve the bone defect in apical periodontitis.

METHODOLOGY

We established an apical periodontitis mouse model in Sting-/- and WT mice in vivo. The progression of apical periodontitis was analysed by micro-CT analysis and H&E staining. The expression level and localization of STING in F4/80+ cells were identified by IHC and immunofluorescence staining. RANKL in periapical tissues was tested by IHC staining. TRAP staining was used to detect osteoclasts. To clarify the effect of STING inhibitor C-176 as an immunotherapeutic drug, mice with apical periodontitis were treated with C-176 and the bone loss was identified by H&E, TRAP, RANKL staining and micro-CT. Bone marrow-derived macrophages (BMMs) were isolated from Sting-/- and WT mice and induced to osteoclasts in a lipopolysaccharide (LPS)-induced inflammatory environment in vitro. Moreover, WT BMMs were treated with C-176 to determine the effect on osteoclast differentiation by TRAP staining. The expression levels of osteoclast-related genes were tested using qRT-PCR.

RESULTS

Compared to WT mice, the bone resorption and inflammatory cell infiltration were reduced in exposed Sting-/- mice. In the exposed WT group, STING was activated mainly in F4/80+ macrophages. Histological staining revealed the less osteoclasts and lower expression of osteoclast-related factor RANKL in Sting-/- mice. The treatment of the STING inhibitor C-176 in an apical periodontitis mice model alleviated inflammation progression and bone loss, similar to the effect observed in Sting-/- mice. Expression of RANKL and osteoclast number in periapical tissues were also decreased after C-176 administration. In vitro, TRAP staining showed fewer positive cells and qRT-PCR reflected decreased expression of osteoclastic marker, Src and Acp5 were detected during osteoclastic differentiation in Sting-/- and C-176 treated BMMs.

CONCLUSIONS

STING was activated and was proven to be a positive factor in bone loss and osteoclastogenesis in apical periodontitis. The STING inhibitor C-176 administration could alleviate the bone loss via modulating local immune response, which provided immunotherapy to the treatment of apical periodontitis.

Polydopamine nanomaterials and their potential applications in the treatment of autoimmune diseases

The conventional treatment methods used for the management of autoimmune diseases (ADs) have limited efficacy and also exhibit significant side effects. Thus, identification of novel strategies to improve the efficacy and safety of ADs treatment is urgently required. Overactivated immune response and oxidative stress are common characteristics associated with ADs. Polydopamine (PDA), as a polymer material with good antioxidant and photothermal conversion properties, has displayed useful application potential against ADs. In addition, PDA possesses good biosafety, simple preparation, and easy functionalization, which is conducive for the pharmacological development of PDA nanomaterials with clinical transformation prospects. Here, we have first reviewed the preparation of PDA, the different functional integration strategies of PDA-based biomaterials, and their potential applications in ADs. Next, the mechanism of action of PDA in ADs has been elaborated in detail. Finally, the application opportunities and challenges linked with PDA nanomaterials for ADs treatment are discussed. This review is contributed to design reasonable and effective PDA nanomaterials for the diagnosis and treatment of ADs.

Engineering and Delivery of cGAS-STING Immunomodulators for the Immunotherapy of Cancer and Autoimmune Diseases

The cyclic GMP-AMP synthase-stimulator interferon gene (cGAS-STING) pathway is an emerging therapeutic target for the prophylaxis and therapy of a variety of diseases, ranging from cancer, infectious diseases, to autoimmune disorders. As a cytosolic double stranded DNA (dsDNA) sensor, cGAS can bind with relatively long dsDNA, resulting in conformational change and activation of cGAS. Activated cGAS catalyzes the conversion of adenosine triphosphate (ATP) and guanosine triphosphate (GTP) into cGAMP, a cyclic dinucleotide (CDN). CDNs, including 2'3'-cGAMP, stimulate adapter protein STING on the endoplasmic membrane, triggering interferon regulatory factor 3 (IRF3) phosphorylation and nuclear factor kappa B (NF-κB) activation. This results in antitumor and antiviral type I interferon (IFN-I) responses. Moreover, cGAS-STING overactivation and the resulting IFN-I responses have been associated with a number of inflammatory and autoimmune diseases. This makes cGAS-STING appealing immunomodulatory targets for the prophylaxis and therapy of various related diseases. However, drug development of CDNs and CDN derivatives is challenged by their limited biostability, difficult formulation, poor pharmacokinetics, and inefficient tissue accumulation and cytosolic delivery. Though recent synthetic small molecular CDN- or non-CDN-based STING agonists have been reported with promising preclinical therapeutic efficacy, their therapeutic efficacy and safety remain to be fully evaluated preclinically and clinically. Therefore, it is highly desirable and clinically significant to advance drug development for cGAS-STING activation by innovative approaches, such as drug delivery systems and drug development for pharmacological immunomodulation of cGAS. In this Account, we summarize our recent research in the engineering and delivery of immunostimulatory or immunoregulatory modulators for cGAS and STING for the immunotherapy of cancer and autoimmune diseases. To improve the delivery efficiency of CDNs, we developed ionizable and pH-responsive polymeric nanocarriers to load STING agonists, aiming to improve the cellular uptake and facilitate the endosomal escape to induce efficient STING activation. We also codelivered STING agonists with complementary immunostimulatants in nanoparticle-in-hydrogel composites to synergetically elicit potent innate and adaptive antitumor responses that eradicate local and distant large tumors. Further, taking advantage of the simplicity of manufacturing and the established nucleic acid delivery system, we developed oligonucleotide-based cGAS agonists as immunostimulant immunotherapeutics as well as adjuvants for peptide antigens for cancer immunotherapy. To suppress the overly strong proinflammatory responses associated with cGAS-STING overactivation in some of the autoimmune disorders, we devised nanomedicine-in-hydrogel (NiH) that codelivers a cGAS inhibitor and cell-free DNA (cfDNA)-scavenging cationic nanoparticles (cNPs) for systemic immunosuppression in rheumatoid arthritis (RA) therapy. Lastly, we discussed current drug development by targeting cGAS-STING for cancer, infectious diseases, and autoimmune diseases, as well as the potential opportunities for utilizing cGAS-STING pathway for versatile applications in disease treatment.

Synergistic Effects of Azithromycin and STING Agonist Promote IFN-I Production by Enhancing the Activation of STING-TBK1 Signaling

Background

Azithromycin (AZM) is a macrolide antibiotic that exhibits anti-inflammatory and anti-viral infection properties by enhancing type-I interferon (IFN-I) responses. The stimulator of interferon genes (STING) can directly induce IFN-I production. However, elevated IFN-I induces auto-immune phenotypes such as systemic lupus erythematosus (SLE). The effects of AZM and STING on the production of IFN-I are unclear.

Objective

Therefore, this study aims to evaluate the role of AZM and STING on IFN-I responses in macrophages.

Methods

RAW 264.7 macrophages were treated with AZM with and without a STING-agonist (DMXAA), and the maturation of macrophages was determined using flow cytometry. Gene expression and pro-inflammatory cytokines were analyzed using qPCR and ELISA, respectively. Moreover, protein expression was investigated using Western blot assays and immunofluorescence.

Results

Our results show that AZM significantly induced M1 phenotypes, promoting surface molecule expansion of CD80 and MHC-II and production of IL-6 and TNF-α cytokines on DMXAA-stimulated macrophages. Furthermore, we found that AZM-increased mRNA levels of interferon-stimulated genes (ISGs) could be due to the high expression of STNG-TBK1 signaling in the presence of DMXAA.

Conclusion

Our data suggest that AZM enhancement of IFN-I responses was STING dependent in DMXAA-stimulated macrophages. These data underline a novel approach to AZM action-mediated STING-TBK1 signaling for regulating IFN-I responses and may further augment the scientific basis and potential use of AZM in clinical applications.

The battle between the innate immune cGAS-STING signaling pathway and human herpesvirus infection

The incidence of human herpesvirus (HHVs) is gradually increasing and has affected a wide range of population. HHVs can result in serious consequences such as tumors, neonatal malformations, sexually transmitted diseases, as well as pose an immense threat to the human health. The cGAS-STING pathway is one of the innate immune pattern-recognition receptors discovered recently. This article discusses the role of the cGAS-STING pathway in human diseases, especially in human herpesvirus infections, as well as highlights how these viruses act on this pathway to evade the host immunity. Moreover, the author provides a comprehensive overview of modulators of the cGAS-STING pathway. By focusing on the small molecule compounds based on the cGAS-STING pathway, novel targets and concepts have been proposed for the development of antiviral drugs and vaccines, while also providing a reference for the investigation of disease models related to the cGAS-STING pathway. HHV is a double-stranded DNA virus that can trigger the activation of intracellular DNA sensor cGAS, after which the host cells initiate a cascade of reactions that culminate in the secretion of type I interferon to restrict the viral replication. Meanwhile, the viral protein can interact with various molecules in the cGAS-STING pathway. Viruses can evade immune surveillance and maintain their replication by inhibiting the enzyme activity of cGAS and reducing the phosphorylation levels of STING, TBK1 and IRF3 and suppressing the interferon gene activation. Activators and inhibitors of the cGAS-STING pathway have yielded numerous promising research findings in vitro and in vivo pertaining to cGAS/STING-related disease models. However, there remains a dearth of small molecule modulators that have been successfully translated into clinical applications, which serves as a hurdle to be overcome in the future.

Intra-articular nanoparticles based therapies for osteoarthritis and rheumatoid arthritis management

Osteoarthritis (OA) and rheumatoid arthritis (RA) are chronic and progressive inflammatory joint diseases that affect a large population worldwide. Intra-articular administration of various therapeutics is applied to alleviate pain, prevent further progression, and promote cartilage regeneration and bone remodeling in both OA and RA. However, the effectiveness of intra-articular injection with traditional drugs is uncertain and controversial due to issues such as rapid drug clearance and the barrier afforded by the dense structure of cartilage. Nanoparticles can improve the efficacy of intra-articular injection by facilitating controlled drug release, prolonged retention time, and enhanced penetration into joint tissue. This review systematically summarizes nanoparticle-based therapies for OA and RA management. Firstly, we explore the interaction between nanoparticles and joints, including articular fluids and cells. This is followed by a comprehensive analysis of current nanoparticles designed for OA/RA, divided into two categories based on therapeutic mechanisms: direct therapeutic nanoparticles and nanoparticles-based drug delivery systems. We highlight nanoparticle design for tissue/cell targeting and controlled drug release before discussing challenges of nanoparticle-based therapies for efficient OA and RA treatment and their future clinical translation. We anticipate that rationally designed local injection of nanoparticles will be more effective, convenient, and safer than the current therapeutic approach.