Koumine inhibits RANKL-induced ubiquitination and NF-κB activation to prevent ovariectomy and aging-induced bone loss.

Osteoporosis (OP) is a bone remodeling disease characterized by an imbalance between bone resorption and formation. Osteoclasts are the primary therapeutic targets for treating bone destruction. Koumine (KM), the most bioactive component in Gelsemium alkaloids, exhibits antitumor, immunosuppressive, anti-inflammatory, and analgesic properties. However, the effects of bone loss have not been well studied. This study conducted in vitro and in vivo verification experiments on KM. The results showed that KM inhibited bone resorption and tartrate-resistant acid phosphatase positive (TRAP+) osteoclasts development by mature osteoclasts in a dose-dependent manner. Moreover, KM prevented OVX-induced OP in vivo and potentially inhibited ubiquitination, a process closely related to various biological activities, including protein interaction, transcription, and transmembrane signal transduction regulation, especially within the nuclear factor-κB (NF-κB) pathway. Previous studies have demonstrated that several proteins ubiquitination promotes osteoclastogenesis, our study indicated that KM inhibits early NF-κB activation and receptor activator of NF-κB ligand induced ubiquitination, a critical factor in osteoclast differentiation. In conclusion, our research suggests that KM holds potential as an effective therapeutic agent for OP.

Anti-Inflammatory Ergosteroid Derivatives from the Coral-Associated Fungi Penicillium oxalicum HL-44.

To obtain the optimal fermentation condition for more abundant secondary metabolites, Potato Dextrose Agar (PDA) medium was chosen for the scale-up fermentation of the fungus Penicillium oxalicum HL-44 associated with the soft coral Sinularia gaweli. The EtOAc extract of the fungi HL-44 was subjected to repeated column chromatography (CC) on silica gel and Sephadex LH-20 and semipreparative RP-HPLC to afford a new ergostane-type sterol ester (1) together with fifteen derivatives (2-16). Their structures were determined with spectroscopic analyses and comparisons with reported data. The anti-inflammatory activity of the tested isolates was assessed by evaluating the expression of pro-inflammatory factors Tnfα and Ifnb1 in Raw264.7 cells stimulated with LPS or DMXAA. Compounds 2, 9, and 14 exhibited significant inhibition of Ifnb1 expression, while compounds 2, 4, and 5 showed strong inhibition of Tnfα expression in LPS-stimulated cells. In DMXAA-stimulated cells, compounds 1, 5, and 7 effectively suppressed Ifnb1 expression, whereas compounds 7, 8, and 11 demonstrated the most potent inhibition of Tnfα expression. These findings suggest that the tested compounds may exert their anti-inflammatory effects by modulating the cGAS-STING pathway. This study provides valuable insight into the chemical diversity of ergosteroid derivatives and their potential as anti-inflammatory agents.

Stimulator of interferon genes (STING): Key therapeutic targets in ischemia/reperfusion injury.

The Stimulator of Interferon Genes (STING) is predominantly expressed in immune cells, including macrophages, natural killer cells, dendritic cells, and T cells, functioning as a pattern recognition receptor. STING activation upon detecting cytosolic DNA released from damaged cells initiates downstream pathways, leading to the production of inflammatory cytokines such as IFNs, IL-6, and TNF-α. Dysregulated STING activation has been implicated in inflammatory and metabolic diseases. Ischemia/reperfusion injury (I/RI) is common in stroke, acute myocardial infarction, organ transplantation, and surgeries for certain end-stage diseases. Recent studies suggest that STING could be a novel therapeutic target for I/RI treatment. In this review, we provide a concise overview of the cGAS-STING signaling pathway's general functions and summarize STING's role in I/RI across various organs, including the heart, liver, kidney, and lung. Moreover, we explore potential therapeutic approaches for I/RI by targeting STING.

Gelsevirine is a novel STING-specific inhibitor and mitigates STING-related inflammation in sepsis.

Background: Stimulation of IFN genes (STING) is central to the production of interferon and proinflammatory cytokines in response to microbial DNA or self-DNA in the cytosol. The detrimental role of the activation of STING during sepsis has been well documented. Methods: Here, we found that gelsevirine (GS) potently inhibit interferon and inflammatory cytokine induction in macrophages exposed to STING agonists (2'3'-cGAMP, IFN stimulatory DNA (ISD), and poly(dA:dT)). I n silico docking analysis and surface plasmon resonance binding study showed that GS bonds with high affinity to the cyclic dinucleotide (CDN)-binding pocket of STING. Biotin pull-down assay also confirmed that GS competitively bonded to STING protein. Furthermore, GS inhibited 2'3'-cGAMP-induced STING dimerization and subsequent activation. In addition, GS induced K48-linked STING ubiquitination and degradation, which was likely through upregulating and recruiting TRIM21. In mice exposed to cecal ligation and puncture (CLP)-induced sepsis, post-operative administration of GS significantly extended the survival period and mitigated acute organ damage. Results: Overall, GS inhibited STING signaling by competitively binding to the CDN-binding pocket to lock STING in an inactive open conformation, while also promoting K48-linked STING ubiquitination and degradation. Conclusions: Our findings identify a novel STING-specific inhibitor that could be applied in the treatment of sepsis.

STING signaling in inflammaging: a new target against musculoskeletal diseases.

Stimulator of Interferon Gene (STING) is a critical signaling linker protein that plays a crucial role in the intrinsic immune response, particularly in the cytoplasmic DNA-mediated immune response in both pathogens and hosts. It is also involved in various signaling processes in vivo. The musculoskeletal system provides humans with morphology, support, stability, and movement. However, its aging can result in various diseases and negatively impact people's lives. While many studies have reported that cellular aging is a leading cause of musculoskeletal disorders, it also offers insight into potential treatments. Under pathological conditions, senescent osteoblasts, chondrocytes, myeloid cells, and muscle fibers exhibit persistent senescence-associated secretory phenotype (SASP), metabolic disturbances, and cell cycle arrest, which are closely linked to abnormal STING activation. The accumulation of cytoplasmic DNA due to chromatin escape from the nucleus following DNA damage or telomere shortening activates the cGAS-STING signaling pathway. Moreover, STING activation is also linked to mitochondrial dysfunction, epigenetic modifications, and impaired cytoplasmic DNA degradation. STING activation upregulates SASP and autophagy directly and indirectly promotes cell cycle arrest. Thus, STING may be involved in the onset and development of various age-related musculoskeletal disorders and represents a potential therapeutic target. In recent years, many STING modulators have been developed and used in the study of musculoskeletal disorders. Therefore, this paper summarizes the effects of STING signaling on the musculoskeletal system at the molecular level and current understanding of the mechanisms of endogenous active ligand production and accumulation. We also discuss the relationship between some age-related musculoskeletal disorders and STING, as well as the current status of STING modulator development.

Regulation of microglia related neuroinflammation contributes to the protective effect of Gelsevirine on ischemic stroke.

Stroke, especially ischemic stroke, is an important cause of neurological morbidity and mortality worldwide. Growing evidence suggests that the immune system plays an intricate function in the pathophysiology of stroke. Gelsevirine (Gs), an alkaloid from Gelsemium elegans, has been proven to decrease inflammation and neuralgia in osteoarthritis previously, but its role in stroke is unknown. In this study, the middle cerebral artery occlusion (MCAO) mice model was used to evaluate the protective effect of Gs on stroke, and the administration of Gs significantly improved infarct volume, Bederson score, neurobiological function, apoptosis of neurons, and inflammation state in vivo. According to the data in vivo and the conditioned medium (CM) stimulated model in vitro, the beneficial effect of Gs came from the downregulation of the over-activity of microglia, such as the generation of inflammatory factors, dysfunction of mitochondria, production of ROS and so on. By RNA-seq analysis and Western-blot analysis, the JAK-STAT signal pathway plays a critical role in the anti-inflammatory effect of Gs. According to the results of molecular docking, inhibition assay, and thermal shift assay, the binding of Gs on JAK2 inhibited the activity of JAK2 which inhibited the over-activity of JAK2 and downregulated the phosphorylation of STAT3. Over-expression of a gain-of-function STAT3 mutation (K392R) abolished the beneficial effects of Gs. So, the downregulation of JAK2-STAT3 signaling pathway by Gs contributed to its anti-inflammatory effect on microglia in stroke. Our study revealed that Gs was benefit to stroke treatment by decreasing neuroinflammation in stroke as a potential drug candidate regulating the JAK2-STAT3 signal pathway.

Anti-inflammatory Oleanane-Type Triterpenoids Produced by Nonomuraea sp. MYH522 through Microbial Transformation.

Eleven oleanane-type triterpenoids named soyasapogenols B1-B11 have been obtained unexpectedly from a marine actinomycete Nonomuraea sp. MYH522. Their structures have been determined by extensive analysis of spectroscopic experiments and X-ray crystallographic data. Soyasapogenols B1-B11 exhibit subtle differences in the positions and degrees of oxidation on an oleanane skeleton. The feeding experiment suggested that soyasapogenols might be derived from soyasaponin Bb through microbial-mediated conversion. The biotransformation pathways from soyasaponin Bb to five oleanane-type triterpenoids and six A-ring cleaved analogues were proposed. The assumed biotransformation involves an array of reactions including regio- and stereo-selective oxidation. These compounds alleviated the 5,6-dimethylxanthenone-4-acetic acid-induced inflammation in Raw264.7 cells via the stimulator of interferon genes/TBK1/NF-κB signaling pathway. The present work provided an efficient approach for rapid diversification of soyasaponins and for developing food supplements with potent anti-inflammatory effects.

The STING in Non-Alcoholic Fatty Liver Diseases: Potential Therapeutic Targets in Inflammation-Carcinogenesis Pathway.

Non-alcoholic fatty liver disease (NAFLD), an important chronic disease, is one of the major causes of high mortality and creates a substantial financial burden worldwide. The various immune cells in the liver, including macrophages, NK cells, dendritic cells, and the neutrophils involved in the innate immune response, trigger inflammation after recognizing the damage signaled from infection or injured cells and tissues. The stimulator of interferon genes (STING) is a critical molecule that binds to the cyclic dinucleotides (CDNs) generated by the cyclic GMP-AMP synthase (cGAS) to initiate the innate immune response against infection. Previous studies have demonstrated that the cGAS-STING pathway plays a critical role in inflammatory, auto-immune, and anti-viral immune responses. Recently, studies have focused on the role of STING in liver diseases, the results implying that alterations in its activity may be involved in the pathogenesis of liver disorders. Here, we summarize the function of STING in the development of NAFLD and present the current inhibitors and agonists targeting STING.

Gelsevirine improves age-related and surgically induced osteoarthritis in mice by reducing STING availability and local inflammation.

Low-grade and chronic inflammation is recognized as an important mediator of the pathogenesis of osteoarthritis (OA). The aim of current work was to test the therapeutic effects of gelsevirine on age-related and surgically induced OA in mice and elucidate the underlying mechanism. The in vitro studies revealed that gelsevirine treatment mitigated IL-1ß-induced inflammatory response and degeneration in cultured chondrocytes, evidenced by reduced apoptosis and expression of MMP3, MMP9, MMP13, IFNß, TNFɑ, and Il6, and increased expression of Col2A and Il10. Furthermore, gelsevirine treatment in IL-1ß-stimulated chondrocytes reduced the protein expression of stimulator of IFN genes (STING, also referred to Tmem173) and p-TBK1. Importantly, gelsevirine treatment did not provide further protection in STING-deficient chondrocytes against IL-1ß stimulation. The in vivo studies revealed that gelsevirine treatment mitigated articular cartilage destruction in age-related and destabilization of the medial meniscus (DMM)-induced OA. Similarly, gelsevirine treatment did not provide further beneficial effects against OA in STING deficient mice. Mechanistically, gelsevirine promoted STING K48-linked poly-ubiquitination and MG-132 (a proteasome inhibitor) reversed the inhibitive effects of gelsevirine on IL-1ß-induced activation of STING/TBK1 pathway in chondrocytes. Collectively, we identify that gelsevirine targets STING for K48 ubiquitination and degradation and improves age-related and surgically induced OA in mice.

An Acid-Sensitive Bone Targeting Delivery System Carrying Acacetin Prevents Osteoporosis in Ovariectomized Mice.

One effective treatment for postmenopausal osteoporosis is to inhibit osteoclasts and subsequent bone resorption. In our study, we demonstrated that acacetin, a flavone with potential therapeutic effects in infections, cancers, and several metabolic disorders, inhibited osteoclast differentiation and bone resorption in vitro. For improving the efficacy of acacetin in vivo, we developed an acid-sensitive bone-targeting delivery system composed of an acid-sensitive linker (N-ε-maleimidocaproic acid hydrazide, EMCH) for ensuring an effective release of acacetin at the site of action and a hydrophilic aspartic acid hexapeptide ((Asp)6, D6) as the effective bone targeting agent. Our results revealed that Acacetin-EMCH-D6 specifically bound to the bone surface once administrated in vivo, prolonged the retention time in bone and released acacetin at the osteoclastic bone resorption sites where the acidity is higher. We further demonstrated that, in ovariectomy-induced osteoporosis mice, treatment with Acacetin-EMCH-D6 inhibited osteoclast formation and increased trabecular bone mass. On the contrary, neither acacetin nor EMCH-D6 with the same dosage alone showed significant anti-osteoporosis effects in vivo. Mechanistically, targeted delivery of acacetin to the bone resorption sites by Acacetin-EMCH-D6 inhibited autophagy through activating PI3K/AKT/mTOR pathway in osteoclasts, while the activation of autophagy by rapamycin partially reversed the inhibitory effects of acacetin in vitro and in vivo. In summary, our study, for the first time, showed that the acid-sensitive bone-targeting delivery system carrying acacetin was effective for the treatment of postmenopausal osteoporosis. Thus, targeted delivery of acacetin using Acacetin-EMCH-D6 to bone resorption sites is a promising therapy for osteoporosis.