Microsomal prostaglandin E2 synthase-1 and its inhibitors: Molecular mechanisms and therapeutic significance

Design and synthesis of new dihydropyrimidine/sulphonamide hybrids as promising anti-inflammatory agents via dual mPGES-1/5-LOX inhibition

A novel series of dihydropyrimidine/sulphonamide hybrids 3a-j with anti-inflammatory properties have been developed and tested as dual mPGES-1/5-LOX inhibitors. In vitro assay, results showed that compounds 3c, 3e, 3h, and 3j were the most effective dual inhibitors of mPGES-1 and 5-LOX activities. Compound 3j was the most potent dual inhibitor with IC50 values of 0.92 µM and 1.98 µM, respectively. In vivo, anti-inflammatory studies demonstrated that compounds 3c, 3e, 3h, and 3e had considerable anti-inflammatory activity, with EI% ranging from 29% to 71%. Compounds 3e and 3j were equivalent to celecoxib after the first hour but exhibited stronger anti-inflammatory effects than celecoxib after the third and fifth hours. Moreover, compounds 3e and 3j significantly reduced the levels of pro-inflammatory cytokines (PGE2, TNF-α, and IL-6) with gastrointestinal safety profiles. Molecular docking simulations explored the most potent derivatives' binding affinities and interaction patterns within mPGES-1 and 5-LOX active sites. This study disclosed that compound 3j is a promising anti-inflammatory lead with dual mPGES-1/5-LOX inhibition that deserves further preclinical investigation.

Neuro-bone tissue engineering: emerging mechanisms, potential strategies, and current challenges

The skeleton is a highly innervated organ in which nerve fibers interact with various skeletal cells. Peripheral nerve endings release neurogenic factors and sense skeletal signals, which mediate bone metabolism and skeletal pain. In recent years, bone tissue engineering has increasingly focused on the effects of the nervous system on bone regeneration. Simultaneous regeneration of bone and nerves through the use of materials or by the enhancement of endogenous neurogenic repair signals has been proven to promote functional bone regeneration. Additionally, emerging information on the mechanisms of skeletal interoception and the central nervous system regulation of bone homeostasis provide an opportunity for advancing biomaterials. However, comprehensive reviews of this topic are lacking. Therefore, this review provides an overview of the relationship between nerves and bone regeneration, focusing on tissue engineering applications. We discuss novel regulatory mechanisms and explore innovative approaches based on nerve-bone interactions for bone regeneration. Finally, the challenges and future prospects of this field are briefly discussed.

Sinomenine ameliorates collagen-induced arthritis in mice by targeting GBP5 and regulating the P2X7 receptor to suppress NLRP3-related signaling pathways

Sinomenine (SIN) is an isoquinoline alkaloid isolated from Sinomenii Caulis, a traditional Chinese medicine used to treat rheumatoid arthritis (RA). Clinical trials have shown that SIN has comparable efficacy to methotrexate in treating patients with RA but with fewer adverse effects. In this study, we explored the anti-inflammatory effects and therapeutic targets of SIN in LPS-induced RAW264.7 cells and in collagen-induced arthritis (CIA) mice. LPS-induced RAW264.7 cells were pretreated with SIN (160, 320, 640 µM); and CIA mice were administered SIN (25, 50 and 100 mg·kg-1·d-1, i.p.) for 30 days. We first conducted a solvent-induced protein precipitation (SIP) assay in LPS-stimulated RAW264.7 cells and found positive evidence for the direct binding of SIN to guanylate-binding protein 5 (GBP5), which was supported by molecular simulation docking, proteomics, and binding affinity assays (KD = 3.486 µM). More importantly, SIN treatment markedly decreased the expression levels of proteins involved in the GBP5/P2X7R-NLRP3 pathways in both LPS-induced RAW264.7 cells and the paw tissue of CIA mice. Moreover, the levels of IL-1β, IL-18, IL-6, and TNF-α in both the supernatant of inflammatory cells and the serum of CIA mice were significantly reduced. This study illustrates a novel anti-inflammatory mechanism of SIN; SIN suppresses the activity of NLRP3-related pathways by competitively binding GBP5 and downregulating P2X7R protein expression, which ultimately contributes to the reduction of IL-1β and IL-18 production. The binding specificity of SIN to GBP5 and its inhibitory effect on GBP5 activity suggest that SIN has great potential as a specific GBP5 antagonist.

Pharmacological mechanisms of sinomenine in anti-inflammatory immunity and osteoprotection in rheumatoid arthritis: A systematic review

BACKGROUND

Sinomenine (SIN) is the main pharmacologically active component of Sinomenii Caulis and protects against rheumatoid arthritis (RA). In recent years, many studies have been conducted to elucidate the pharmacological mechanisms of SIN in the treatment of RA. However, the molecular mechanism of SIN in RA has not been fully elucidated.

PURPOSE

To summarize the pharmacological effects and molecular mechanisms of SIN in RA and clarify the most valuable regulatory mechanisms of SIN to provide clues and a basis for basic research and clinical applications.

METHODS

We systematically searched SciFinder, Web of Science, PubMed, China National Knowledge Internet (CNKI), the Wanfang Databases, and the Chinese Scientific Journal Database (VIP). We organized our work based on the PRISMA statement and selected studies for review based on predefined selection criteria.

OUTCOME

After screening, we identified 201 relevant studies, including 88 clinical trials and 113 in vivo and in vitro studies on molecular mechanisms. Among these studies, we selected key results for reporting and analysis.

CONCLUSIONS

We found that most of the known pharmacological mechanisms of SIN are indirect effects on certain signaling pathways or proteins. SIN was manifested to reduce the release of inflammatory cytokines such as Tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), and IL-1β, thereby reducing the inflammatory response, and apparently blocking the destruction of bone and cartilage. The regulatory effects on inflammation and bone destruction make SIN a promising drug to treat RA. More notably, we believe that the modulation of α7nAChR and the regulation of methylation levels at specific GCG sites in the mPGES-1 promoter by SIN, and its mechanism of directly targeting GBP5, certainly enriches the possibilities and the underlying rationale for SIN in the treatment of inflammatory immune-related diseases.

Discovering the Active Ingredients of Medicine and Food Homologous Substances for Inhibiting the Cyclooxygenase-2 Metabolic Pathway by Machine Learning Algorithms

Cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase (mPGES-1) are two key targets in anti-inflammatory therapy. Medicine and food homology (MFH) substances have both edible and medicinal properties, providing a valuable resource for the development of novel, safe, and efficient COX-2 and mPGES-1 inhibitors. In this study, we collected active ingredients from 503 MFH substances and constructed the first comprehensive MFH database containing 27,319 molecules. Subsequently, we performed Murcko scaffold analysis and K-means clustering to deeply analyze the composition of the constructed database and evaluate its structural diversity. Furthermore, we employed four supervised machine learning algorithms, including support vector machine (SVM), random forest (RF), deep neural networks (DNNs), and eXtreme Gradient Boosting (XGBoost), as well as ensemble learning, to establish 640 classification models and 160 regression models for COX-2 and mPGES-1 inhibitors. Among them, ModelA_ensemble_RF_1 emerged as the optimal classification model for COX-2 inhibitors, achieving predicted Matthews correlation coefficient (MCC) values of 0.802 and 0.603 on the test set and external validation set, respectively. ModelC_RDKIT_SVM_2 was identified as the best regression model based on COX-2 inhibitors, with root mean squared error (RMSE) values of 0.419 and 0.513 on the test set and external validation set, respectively. ModelD_ECFP_SVM_4 stood out as the top classification model for mPGES-1 inhibitors, attaining MCC values of 0.832 and 0.584 on the test set and external validation set, respectively. The optimal regression model for mPGES-1 inhibitors, ModelF_3D_SVM_1, exhibited predictive RMSE values of 0.253 and 0.35 on the test set and external validation set, respectively. Finally, we proposed a ligand-based cascade virtual screening strategy, which integrated the well-performing supervised machine learning models with unsupervised learning: the self-organized map (SOM) and molecular scaffold analysis. Using this virtual screening workflow, we discovered 10 potential COX-2 inhibitors and 15 potential mPGES-1 inhibitors from the MFH database. We further verified candidates by molecular docking, investigated the interaction of the candidate molecules upon binding to COX-2 or mPGES-1. The constructed comprehensive MFH database has laid a solid foundation for the further research and utilization of the MFH substances. The series of well-performing machine learning models can be employed to predict the COX-2 and mPGES-1 inhibitory capabilities of unknown compounds, thereby aiding in the discovery of anti-inflammatory medications. The COX-2 and mPGES-1 potential inhibitor molecules identified through the cascade virtual screening approach provide insights and references for the design of highly effective and safe novel anti-inflammatory drugs.

Aspirin eugenol ester ameliorates LPS-induced inflammatory responses in RAW264.7 cells and mice

Introduction: Inflammation is a defensive response of the body and the pathological basis of many diseases. However, excessive inflammation and chronic inflammation impair the homeostasis of the organism. Arachidonic acid (AA) has a close relationship with inflammation and is the main mediator of the pro-inflammatory response. Based on the prodrug principle, the new pharmaceutical compound aspirin eugenol ester (AEE) was designed and synthesized. However, the effects of AEE on key enzymes, metabolites and inflammatory signaling pathways in the AA metabolic network have not been reported. Methods: In this study, the anti-inflammation effects of AEE were first investigated in mice and RAW264.7 cells in LPS induced inflammation model. Then, the changes of the key enzymes and AA metabolites were explored by RT-PCR and targeted metabolomics. Moreover, the regulatory effects on NF-kB and MAPKS signaling pathways were explored by Western Blotting. Results: Results indicated that AEE significantly reduced the number of leukocyte and increased the lymphocyte percentage. AEE decreased the expression levels of IL-1β, IL-6, IL-8 and TNF-α both in vivo and in vitro. In the liver of mice, AEE downregulated the levels of AA, prostaglandin D2 (PGD2) and upregulated 12- hydroxyeicosatetraenoic acid (12-HETE). However, the changes of PGE2, PGF2α, 6-keto-prostaglandin F1α (6-KETO-PGF1α), 9-hydroxy-octadecenoic acid (9- HODE), 13-HODE, 15-HETE, docosahexaenoic acid (DHA) and thromboxane B2 (TXB2) were not significant. Additionally, it was found that AEE decreased the relative mRNA expression levels of p65 and p38 and the ratio of p-p65/p65. Discussion: It was concluded that AEE might inhibit the LPS-induced inflammatory response through the regulation of AA metabolism. This study provides the theoretical foundation for the development of AEE as a medicinal anti-inflammatory drug.

Far upstream element-binding protein 1 confers lobaplatin resistance by transcriptionally activating PTGES and facilitating the arachidonic acid metabolic pathway in osteosarcoma

Drug resistance is a major obstacle in cancer treatment and recurrence prevention and leads to poor outcomes in patients suffering from osteosarcoma. Clarification of the mechanism of drug resistance and exploration of effective strategies to overcome this obstacle could lead to clinical benefits for these patients. The expression of far upstream element-binding protein 1 (FUBP1) was found to be markedly elevated in osteosarcoma cell lines and clinical specimens compared with osteoblast cells and normal bone specimens. High expression of FUBP1 was correlated with a more aggressive phenotype and a poor prognosis in osteosarcoma patients. We found that overexpression of FUBP1 confers lobaplatin resistance, whereas the inhibition of FUBP1 sensitizes osteosarcoma cells to lobaplatin-induced cytotoxicity both in vivo and in vitro. Chromatin immunoprecipitation-seq and RNA-seq were performed to explore the potential mechanism. It was revealed that FUBP1 could regulate the transcription of prostaglandin E synthase (PTGES) and subsequently activate the arachidonic acid (AA) metabolic pathway, which leads to resistance to lobaplatin. Our investigation provides evidence that FUBP1 is a potential therapeutic target for osteosarcoma patients. Targeting FUBP1, its downstream target PTGES and the AA metabolic pathway may be promising strategies for sensitizing chemoresistant osteosarcoma cells to lobaplatin.

Microsomal prostaglandin E synthase-1 inhibition promotes shunting in arachidonic acid metabolism during inflammatory responses in vitro

Microsomal Prostaglandin E Synthase 1 (mPGES-1) is the key enzyme for the generation of the pro-inflammatory lipid mediator prostaglandin E₂ (PGE₂), which contributes to several pathological features of many diseases. Inhibition of mPGES-1 has been shown to be a safe and effective therapeutic strategy in various pre-clinical studies. In addition to reduced PGE₂ formation, it is also suggested that the potential shunting into other protective and pro-resolving prostanoids may play an important role in resolution of inflammation. In the present study, we analysed the eicosanoid profiles in four in vitro inflammation models and compared the effects of mPGES-1 inhibition with those of cyclooxygenase-2 (Cox-2) inhibition. Our results showed a marked shift to the PGD₂ pathway under mPGES-1 inhibition in A549 cells, RAW264.7 cells and mouse bone marrow-derived macrophages (BMDMs), whereas enhanced prostacyclin production was observed in rheumatoid arthritis synovial fibroblasts (RASFs) treated with an mPGES-1 inhibitor. As expected, Cox-2 inhibition completely suppressed all prostanoids. This study suggests that the therapeutic effects of mPGES-1 inhibition may be mediated by modulation of other prostanoids in addition to PGE₂ reduction.

Cooperation between Prostaglandin E2 and Epidermal Growth Factor Receptor in Cancer Progression: A Dual Target for Cancer Therapy

It is recognized that prostaglandin E2 (PGE2) is one key lipid mediator involved in chronic inflammation, and it is directly implicated in tumor development by regulating cancer cell growth and migration, apoptosis, epithelial-mesenchymal transition, angiogenesis, and immune escape. In addition, the expression of the enzymes involved in PGE2 synthesis, cyclooxygenase 2 (COX-2) and microsomal prostaglandin E synthase 1 (mPGES1), positively correlates with tumor progression and aggressiveness, clearly indicating the crucial role of the entire pathway in cancer. Moreover, several lines of evidence suggest that the COX2/mPGES1/PGE2 inflammatory axis is involved in the modulation of epidermal growth factor receptor (EGFR) signaling to reinforce the oncogenic drive of EGFR activation. Similarly, EGFR activation promotes the induction of COX2/mPGES1 expression and PGE2 production. In this review, we describe the interplay between COX2/mPGES1/PGE2 and EGFR in cancer, and new therapeutic strategies that target this signaling pathway, to outline the importance of the modulation of the inflammatory process in cancer fighting.

Virtual screening, molecular simulations and bioassays: Discovering novel microsomal prostaglandin E Synthase-1 (mPGES-1) inhibitors

Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible prostaglandin E synthase expressed following exposure to pro-inflammatory stimuli. The mPGES-1 enzyme represents a new target for the therapeutic treatment of acute and chronic inflammatory disorders and cancer. In the present study, compounds from the ZINC15 database with an indole scaffold were docked at the mPGES-1 binding site using Glide (high-throughput virtual screening [HTVS], standard precision [SP] and extra precision [XP]), and the stabilities of the complexes were determined by molecular simulation studies. Following HTVS, the top 10% compounds were retained and further screened by SP. Again, the top 10% of these compounds were retained. Finally, the Glide XP scores of the compounds were determined, 20% were analyzed, and the Prime MM-GBSA total free binding energies of the compounds were calculated. The molecular simulations (100 ns) of the reference ligand, LVJ, and the two best-scoring compounds were performed with the Desmond program to analyze the dynamics of the target protein-ligand complexes. In human lung cells treated with the hit compounds, cell viability by colorimetric method and PGE₂ levels by immunoassay method were determined. These in vitro experiments demonstrated that the two indole-containing hit compounds are potential novel inhibitors of mPGES-1 and are, therefore, potential therapeutic agents for cancer/inflammation therapies. Moreover, the compounds are promising lead mPGES-1 inhibitors for novel molecule design.

Effects of 2-carba-cyclic phosphatidic acid derivatives on IL-1β-stimulated human chondrocytes

Osteoarthritis (OA) is a common joint disease characterized by the breakdown of subchondral bone and cartilage damage, most often affecting middle-aged and elderly people. Although the etiology of OA is still unknown, some reports suggest that inflammatory factors such as interleukin (IL)- 1β mediate the progression of OA. To investigate the effect of IL-1β and the possibility of treatment for OA, we applied 2-carba-cyclic phosphatidic acid (2ccPA) and its derivatives on human chondrocytes. 2ccPA is a synthesized phospholipid derived from a bioactive phospholipid mediator: cyclic phosphatidic acid (cPA). It has been previously reported that 2ccPA exhibits anti-inflammatory and chondroprotective effects in an OA animal model. 2ccPA and its ring-opened body (ROB) derivative significantly suppressed IL-1β-induced upregulation of IL-6, matrix metalloproteinase-13, and cyclooxygenase-2, as well as the degradation of type II collagen and aggrecan. However, the other two derivatives, namely the deacylated and ring-opened deacylated bodies, showed little effect on an IL-1β-exposed human chondrosarcoma cell-line. These data suggest that the intactness of 2ccPA and ROB is essential for anti-inflammatory effects on OA. Collectively, this study provides evidence that 2ccPA and ROB would be novel therapeutic agents for OA.

Chemical Constituents of the Roots of Polygala tenuifolia and Their Anti-Inflammatory Effects

Increasing scientific evidence has demonstrated that the roots of Polygala tenuifolia Willd. have pharmacological effects related to anti-inflammation. Therefore, the aim of this study is to investigate the chemical constituents from P. tenuifolia roots as anti-inflammatory drug candidates. In the present work, twenty-three compounds were isolated from P. tenuifolia roots, including three saponins (1-3), ten phenylpropanoid sucrose esters (4-12), one benzoic acid sugar ester derivative (13), four xanthones (14-17), two hydroxy benzophenone derivatives (18 and 19), two phenolic derivatives (20 and 21), and two ionones (22 and 23). All isolates were tested for their inhibitory effects of LPS-stimulated NO and PGE₂ production in RAW 264.7 macrophages. Among these, 3-O-(3,4,5-trimethoxy-cinnamoyl),6'-O-(p-methoxybenzoyl) sucrose ester (TCMB; 11) together with compounds 3 and 21 exhibited significant inhibitory effects on NO production, while TCMB and compounds 17, 19, and 21 showed strong inhibitory effects on PGE₂ production. Specifically, TCMB (11) downregulated the protein levels of iNOS and COX-2 in LPS-induced RAW 264.7 macrophages. In addition, TCMB (11) dose-dependently diminished the relative mRNA expression levels of iNOS, PGE₂, and proinflammatory cytokines (TNF-α, IL-1β, and IL-6). A molecular docking study showed that TCMB (11) has strong binding affinities with iNOS and COX-2.