Membrane prostaglandin E synthase-1: a novel therapeutic target

PTGES is involved in myofibroblast differentiation via HIF-1α-dependent glycolysis pathway

Lung cancer is the leading cause of cancer-related deaths worldwide. Patients with lung cancer usually exhibit poor prognoses and low 5-year survival rates. Idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) are both chronic lung dysfunctions resulting in lung fibrosis and increased risk of lung cancer. Myofibroblasts contribute to the progression of asthma, COPD and IPF, leading to fibrosis in the airway and lungs. A growing body of evidence demonstrates that metabolic reprogramming is a major hallmark of fibrosis, being important in the progression of fibrosis. Using gene expression microarray, we identified and validated that the lipid metabolic pathway was upregulated in lung fibroblasts upon interleukin (IL)-4, IL-13 and tumour necrosis factor (TNF)-α treatment. In this study, we described that prostaglandin E synthase (PTGES) was upregulated in lung fibroblasts after IL-4, IL-13 and TNF-α treatments. PTGES increased α-SMA levels and promoted lung fibroblast cell migration and invasion abilities. Furthermore, PTGES was upregulated in a lung fibrosis rat model in vivo. PTGES increased AKT phosphorylation, leading to activation of the HIF-1α-glycolysis pathway in lung fibroblast cells. HIF-1α inhibitor or 2-DG treatments reduced α-SMA expression in recombinant PTGES (rPTGES)-treated lung fibroblast cells. Targeting PGE2 signalling in PTGES-overexpressing cells by a PTGES inhibitor reduced α-SMA expression. In conclusion, the results of this study demonstrate that PTGES increases the expression of myofibroblast marker via HIF-1α-dependent glycolysis and contributes to myofibroblast differentiation.

Multifunctional injectable microspheres for osteoarthritis therapy via spatiotemporally modulating macrophage polarization and inflammation

Local injection of anti-inflammatory drugs for osteoarthritis emerged as a promising administration in the clinic, and sustained-release dosage forms have great potential for future therapeutic applications. Controlling the response of patients only in the acute inflammatory phase is currently the focus of therapeutic interventions. To relieve acute pain in patients and to improve the long-term prognosis effect of osteoarthritis treatment, we designed a two-pronged approach in this research: an injectable double-layer microsphere containing a "nonsteroidal anti-inflammatory drug - macrophage polarizing factor" was constructed. The results indicated that microspheres could regulate the intra-articular environment by inhibiting local inflammatory cytokine production, promoting macrophage polarization to the M2-phenotype, and increasing the expression of cartilage repair factors. Polymers chosen could govern the biocompatibility of microspheres and control the release sequence of the two drugs. Injection of microspheres into the degenerative articular cavity of rats leads to suppressed inflammation and well-promoted cartilage regeneration.

Exposure to nicotine regulates prostaglandin E2 secretion and autophagy of granulosa cells to retard follicular maturation in mammals

Exposure to nicotine by cigarette smoking have shown strongly defectives on the physiological function of ovaries, which in turn leads to disorders of fertility in women. However, the potential molecular mechanisms remain to be elucidated. In this study, we notably found that nicotine was likely to specifically raise the expression of histone deacetylase 3 (HDAC3) to promote the apoptosis and autophagy of granulosa cells (GCs) and block follicular maturation. Moreover, prostaglandin E2 (PGE2) inhibited the apoptosis of GCs and facilitated follicular maturation, and nicotine appeared to inhibit PGE2 secretion by freezing the expression of cyclooxygenase 1 (COX1), which was the rate-limiting and essential enzyme for PGE2 synthesis. Epigenetically, the nicotine was observed to diminish the histone H3 lysine 9 acetylation (H3K9ac) level and compact the chromatin accessibility in -1776/-1499 bp region of COX1 by evoking the expression of HDAC3, with the deactivated Cas9-HDAC3/sgRNA system. Mechanistically, the COX1 protein was found to pick up and degrade the autophagy related protein beclin 1 (BECN1) to control the autophagy of GCs. These results provided a potential new molecular therapy to recover the damage of female fertility induced by nicotine from cigarette smoking.

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Chronic inflammation and cancer; the two sides of a coin

The correlation between chronic inflammation and cancer was initially identified in the 19th century. Biomolecules like interleukins, chemokines, tumor necrosis factors, growth factors, and adhesion molecules, which regulate inflammation, are recognized contributors to neoplastic transformation through various mechanisms, including oncogenic mutations, resistance to apoptosis, and adaptive responses like angiogenesis. This review aims to establish connections between the intricate and complex mechanisms of chronic inflammation and cancer. We illuminate implicit signaling mechanisms that drive the association between chronic inflammation and the initiation/progression of cancer, exploring potential impacts on other diseases. Additionally, we discuss the modalities of currently available therapeutic options for chronic inflammation and cancer, emphasizing the dual nature of such therapies. A thorough understanding of the molecular basis of chronic inflammation is crucial for developing novel approaches in the prevention and treatment of cancer.

Influenza A virus selectively elevates prostaglandin E2 formation in pro-resolving macrophages

Respiratory influenza A virus (IAV) infections are major health concerns worldwide, where bacterial superinfections substantially increase morbidity and mortality. The underlying mechanisms of how IAV impairs host defense remain elusive. Macrophages are pivotal for the innate immune response and crucially regulate the entire inflammatory process, occurring as inflammatory M1- or pro-resolving M2-like phenotypes. Lipid mediators (LM), produced from polyunsaturated fatty acids by macrophages, are potent immune regulators and impact all stages of inflammation. Using LM metabololipidomics, we show that human pro-resolving M2-macrophages respond to IAV infections with specific and robust production of prostaglandin (PG)E2 along with upregulation of cyclooxygenase-2 (COX-2), which persists after co-infection with Staphylococcus aureus. In contrast, cytokine/interferon production in macrophages was essentially unaffected by IAV infection, and the functionality of M1-macrophages was not influenced. Conclusively, IAV infection of M2-macrophages selectively elevates PGE2 formation, suggesting inhibition of the COX-2/PGE2 axis as strategy to limit IAV exacerbation.

Iristectorigenin C suppresses LPS-induced macrophages activation by regulating mPGES-1 expression and p38/JNK pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been used clinically to treat inflammatory diseases clinically. However, the adverse effects of NSAIDs cannot be ignored. Therefore, it is critical for us to find alternative anti-inflammatory drugs that can reduce adverse reactions to herbal medicine, such as Iris tectorum Maxim., which has therapeutic effects and can treat inflammatory diseases and liver-related diseases.

AIM OF THE STUDY

This study aimed to isolate active compounds from I. tectorum and investigate their anti-inflammatory effects and action mechanisms.

MATERIALS AND METHODS

Fourteen compounds were isolated from I. tectorum using silica gel column chromatography, Sephadex LH-20, ODS and high performance liquid chromatography, and their structures were identified by examining physicochemical properties, ultraviolet spectroscopy, infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. Classical inflammatory cell models were established using lipopolysaccharide (LPS)-stimulated RAW264.7 cells and rat primary peritoneal macrophages to examine the effect of these compounds. To examine the action mechanisms, the nitric oxide (NO) levels were measured by Griess reagent and the levels of inflammatory cytokines in the supernatant were measured by ELISA; The expressions of major proteins in prostaglandin E2 (PGE2) synthesis and the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways were examined by Western blotting, and the mRNA expression levels were measured by quantitative real-time polymerase chain reaction; and the nuclear translocation of p65 was examined by high content imaging. Molecular docking was used to predict the binding of active compound to target protein.

RESULTS

Our findings revealed that Iristectorigenin C (IT24) significantly inhibited the levels of NO and PGE2 without affecting cyclooxygenase (COX)-1/COX-2 expression in LPS-induced RAW264.7 cells and rat peritoneal macrophages. Furthermore, IT24 was shown to decrease the expression of microsomal prostaglandin synthetase-1 (mPGES-1) in LPS-induced rat peritoneal macrophages. IT24 did not suppress the phosphorylation and nuclear translocation of proteins in the NF-κB pathway, but it inhibited the phosphorylation of p38/JNK in LPS-stimulated RAW264.7 cells. Additionally, molecular docking analysis indicated that IT24 may directly bind to the mPGES-1 protein.

CONCLUSION

IT24 might inhibit mPGES-1 and the p38/JNK pathway to exert its anti-inflammatory effects and could be also developed as an inhibitor of mPGES-1 to prevent and treat mPGES-1-related diseases, such as inflammatory diseases, and holds promise for further research and drug development.

α-Lipoic acid - a promising agent for attenuating inflammation and preventing steatohepatitis in rats fed a high-fat diet

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent liver disorder affecting a significant part of the global population. This study aimed to investigate the potential therapeutic effects of α-lipoic acid (α-LA) on the inflammatory response during simple steatosis development and progression into steatohepatitis. The study used the MASLD model in male Wistar rats that were fed a standard diet or a high-fat diet (HFD) for 8 weeks. Throughout the entire experiment, half of the animals received α-LA supplementation. The hepatic activity of pro-inflammatory n-6 and anti-inflammatory n-3 polyunsaturated fatty acid (PUFA) pathways and the concentration of arachidonic acid (AA) in selected lipid fractions were determined by the gas-liquid chromatography (GLC). The hepatic expression of proteins from inflammatory pathway was measured by the Western blot technique. The level of eicosanoids, cytokines and chemokines was assessed by the ELISA or multiplex assay kits. The results showed that α-LA supplementation attenuated the activity of n-6 PUFA pathway in FFA and DAG and increased the activity of n-3 PUFA pathway in PL, TAG and DAG. In addition, the administration of α-LA decreased the concentration of AA in DAG and FFA, indicating its potential protective effect on the deterioration of simple hepatic steatosis. The supplementation of α-LA also increased the expression of COX-1 and COX-2 with the lack of significant changes in prostaglandins profile. We observed an increase in the expression of 12/15-LOX, which was reflected in an increase in lipoxin A4 (LXA4) level. A decrease in pro-inflammatory cytokines and an increase in anti-inflammatory cytokines was also noticed in the liver of rats treated with HFD and α-LA. Our observations confirm that α-LA treatment has potential protective effects on inflammation development in the MASLD model. We believe that α-LA has a preventive impact when it comes to the progression of simple steatosis lesions to steatohepatitis.

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.

The multiple functions of miR-574-5p in the neuroblastoma tumor microenvironment

Neuroblastoma is the most common extracranial solid tumor in childhood and arises from neural crest cells of the developing sympathetic nervous system. Prostaglandin E2 (PGE2) has been identified as a key pro-inflammatory mediator of the tumor microenvironment (TME) that promotes neuroblastoma progression. We report that the interaction between the microRNA miR-574-5p and CUG-binding protein 1 (CUGBP1) induces the expression of microsomal prostaglandin E2 synthase 1 (mPGES-1) in neuroblastoma cells, which contributes to PGE2 biosynthesis. PGE2 in turn specifically induces the sorting of miR-574-5p into small extracellular vesicles (sEV) in neuroblastoma cell lines. sEV are one of the major players in intercellular communication in the TME. We found that sEV-derived miR-574-5p has a paracrine function in neuroblastoma. It acts as a direct Toll-like receptor 7/8 (TLR7/8) ligand and induces α-smooth muscle actin (α-SMA) expression in fibroblasts, contributing to fibroblast differentiation. This is particularly noteworthy as it has an opposite function to that in the TME of lung carcinoma, another PGE2 dependent tumor type. Here, sEV-derived miR-574-5p has an autokrine function that inhibits PGE2 biosynthesis in lung cancer cells. We report that the tetraspanin composition on the surface of sEV is associated with the function of sEV-derived miR-574-5p. This suggests that the vesicles do not only transport miRs, but also appear to influence their mode of action.

Novel pharmacological approaches in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe vascular disease and a major public health issue with an unmet medical need for therapy. This disease is featured by a progressive dilation of the abdominal aorta, boosted by atherosclerosis, ageing, and smoking as major risk factors. Aneurysm growth increases the risk of aortic rupture, a life-threatening emergency with high mortality rates. Despite the increasing progress in our knowledge about the etiopathology of AAA, an effective pharmacological treatment against this disorder remains elusive and surgical repair is still the unique available therapeutic approach for high-risk patients. Meanwhile, there is no medical alternative for patients with small aneurysms but close surveillance. Clinical trials assessing the efficacy of antihypertensive agents, statins, doxycycline, or anti-platelet drugs, among others, failed to demonstrate a clear benefit limiting AAA growth, while data from ongoing clinical trials addressing the benefit of metformin on aneurysm progression are eagerly awaited. Recent preclinical studies have postulated new therapeutic targets and pharmacological strategies paving the way for the implementation of future clinical studies exploring these novel therapeutic strategies. This review summarises some of the most relevant clinical and preclinical studies in search of new therapeutic approaches for AAA.

Inhibition of mPGES-2 ameliorates NASH by activating NR1D1 via heme

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD), a complex metabolic syndrome, has limited therapeutic options. Microsomal prostaglandin E synthase-2 (mPGES-2) was originally discovered as a prostaglandin E 2 (PGE 2 ) synthase; however, it does not produce PGE 2 in the liver. Moreover, the role of mPGES-2 in NAFLD remains undefined. Herein, we aimed to determine the function and mechanism of mPGES-2 in liver steatosis and steatohepatitis.

APPROACH AND RESULTS

To evaluate the role of mPGES-2 in NAFLD, whole-body or hepatocyte-specific mPGES-2-deficient mice fed a high-fat or methionine-choline-deficient diet were used. Compared with control mice, mPGES-2-deficient mice showed reduced hepatic lipid accumulation, along with ameliorated liver injury, inflammation, and fibrosis. Furthermore, the protective effect of mPGES-2 deficiency against NAFLD was dependent on decreased cytochrome P450 4A14 and increased acyl-CoA thioesterase 4 levels regulated by the heme receptor nuclear receptor subfamily 1 group D member 1 (NR1D1), but not PGE 2 . Heme regulated the increased NR1D1 activity mediated by mPGES-2 deficiency. Further, we confirmed the protective role of the mPGES-2 inhibitor SZ0232 in NAFLD therapy.

CONCLUSION

Our study indicates the pathogenic role of mPGES-2 and outlines the mechanism in mediating NAFLD, thereby highlighting the therapeutic potential of mPGES-2 inhibition in liver steatosis and steatohepatitis.

Single hormone or synthetic agonist induces Gs/Gi coupling selectivity of EP receptors via distinct binding modes and propagating paths

To accomplish concerted physiological reactions, nature has diversified functions of a single hormone at at least two primary levels: 1) Different receptors recognize the same hormone, and 2) different cellular effectors couple to the same hormone-receptor pair [R.P. Xiao, Sci STKE 2001, re15 (2001); L. Hein, J. D. Altman, B.K. Kobilka, Nature 402, 181-184 (1999); Y. Daaka, L. M. Luttrell, R. J. Lefkowitz, Nature 390, 88-91 (1997)]. Not only these questions lie in the heart of hormone actions and receptor signaling but also dissecting mechanisms underlying these questions could offer therapeutic routes for refractory diseases, such as kidney injury (KI) or X-linked nephrogenic diabetes insipidus (NDI). Here, we identified that Gs-biased signaling, but not Gi activation downstream of EP4, showed beneficial effects for both KI and NDI treatments. Notably, by solving Cryo-electron microscope (cryo-EM) structures of EP3-Gi, EP4-Gs, and EP4-Gi in complex with endogenous prostaglandin E2 (PGE2)or two synthetic agonists and comparing with PGE2-EP2-Gs structures, we found that unique primary sequences of prostaglandin E2 receptor (EP) receptors and distinct conformational states of the EP4 ligand pocket govern the Gs/Gi transducer coupling selectivity through different structural propagation paths, especially via TM6 and TM7, to generate selective cytoplasmic structural features. In particular, the orientation of the PGE2 ω-chain and two distinct pockets encompassing agonist L902688 of EP4 were differentiated by their Gs/Gi coupling ability. Further, we identified common and distinct features of cytoplasmic side of EP receptors for Gs/Gi coupling and provide a structural basis for selective and biased agonist design of EP4 with therapeutic potential.

Update on the pathological roles of prostaglandin E2 in neurodegeneration in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective degeneration of upper and lower motor neurons. The pathogenesis of ALS remains largely unknown; however, inflammation of the spinal cord is a focus of ALS research and an important pathogenic process in ALS. Prostaglandin E₂ (PGE₂) is a major lipid mediator generated by the arachidonic-acid cascade and is abundant at inflammatory sites. PGE₂ levels are increased in the postmortem spinal cords of ALS patients and in ALS model mice. Beneficial therapeutic effects have been obtained in ALS model mice using cyclooxygenase-2 inhibitors to inhibit the biosynthesis of PGE₂, but the usefulness of this inhibitor has not yet been proven in clinical trials. In this review, we present current evidence on the involvement of PGE₂ in the progression of ALS and discuss the potential of microsomal prostaglandin E synthase (mPGES) and the prostaglandin receptor E-prostanoid (EP) 2 as therapeutic targets for ALS. Signaling pathways involving prostaglandin receptors mediate toxic effects in the central nervous system. In some situations, however, the receptors mediate neuroprotective effects. Our recent studies demonstrated that levels of mPGES-1, which catalyzes the final step of PGE₂ biosynthesis, are increased at the early-symptomatic stage in the spinal cords of transgenic ALS model mice carrying the G93A variant of superoxide dismutase-1. In addition, in an experimental motor-neuron model used in studies of ALS, PGE₂ induces the production of reactive oxygen species and subsequent caspase-3-dependent cytotoxicity through activation of the EP2 receptor. Moreover, this PGE₂-induced EP2 up-regulation in motor neurons plays a role in the death of motor neurons in ALS model mice. Further understanding of the pathophysiological role of PGE₂ in neurodegeneration may provide new insights to guide the development of novel therapies for ALS.

Cyclooxygenases and platelet functions

Cyclooxygenase (COX) isozymes, i.e., COX-1 and COX-2, are encoded by separate genes and are involved in the generation of the same products, prostaglandin (PG)G₂ and PGH₂ from arachidonic acid (AA) by the COX and peroxidase activities of the enzymes, respectively. PGH₂ is then transformed into prostanoids in a tissue-dependent fashion due to the different expression of downstream synthases. Platelets present almost exclusively COX-1, which generates large amounts of thromboxane (TX)A₂, a proaggregatory and vasoconstrictor mediator. This prostanoid plays a central role in atherothrombosis, as shown by the benefit of the antiplatelet agent low-dose aspirin, a preferential inhibitor of platelet COX-1. Recent findings have shown the relevant role played by platelets and TXA₂ in developing chronic inflammation associated with several diseases, including tissue fibrosis and cancer. COX-2 is induced in response to inflammatory and mitogenic stimuli to generate PGE₂ and PGI₂ (prostacyclin), in inflammatory cells. However, PGI₂ is constitutively expressed in vascular cells in vivo and plays a crucial role in protecting the cardiovascular systems due to its antiplatelet and vasodilator effects. Here, platelets' role in regulating COX-2 expression in cells of the inflammatory microenvironment is described. Thus, the selective inhibition of platelet COX-1-dependent TXA₂ by low-dose aspirin prevents COX-2 induction in stromal cells leading to antifibrotic and antitumor effects. The biosynthesis and functions of other prostanoids, such as PGD₂, and isoprostanes, are reported. In addition to aspirin, which inhibits platelet COX-1 activity, possible strategies to affect platelet functions by influencing platelet prostanoid receptors or synthases are discussed.

The role of metabolic reprogramming of tumor-associated macrophages in shaping the immunosuppressive tumor microenvironment

Macrophages are potent immune effector cells in innate immunity and exert dual-effects in the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) make up a significant portion of TME immune cells. Similar to M1/M2 macrophages, TAMs are also highly plastic, and their functions are regulated by cytokines, chemokines and other factors in the TME. The metabolic changes in TAMs are significantly associated with polarization towards a protumour or antitumour phenotype. The metabolites generated via TAM metabolic reprogramming in turn promote tumor progression and immune tolerance. In this review, we explore the metabolic reprogramming of TAMs in terms of energy, amino acid and fatty acid metabolism and the potential roles of these changes in immune suppression.

Design, synthesis and characterization of lead compounds as anti-inflammatory drugs targeting mPGES-1 via enzymelink screening

Aim: The objective of this study was to synthesize and validate a set of compounds that selectively inhibit mPGES-1, with the potential to be developed into a novel anti-inflammatory drug. Methods: The synthesized compounds were characterized using 1H NMR spectroscopy and LC-MS to confirm their structure. Cellular and enzymatic assays were used to demonstrate their inhibitory activity on prostaglandin E2 production. Results: Docking studies revealed that compounds containing fluoro-, chloro- and methyl- groups displayed strong inhibitory activity against prostaglandin E2. The inhibitory activity of synthesized trimethyl and trifluoro was further validated using enzymatic and cell migration assays. Conclusion: The findings demonstrated that the synthesized compounds possess significant potential as a new generation of nonsteroidal anti-inflammatory drugs that selectively target mPGES-1 with fewer side effects.

Network pharmacology and experimental studies for deciphering the molecular targets and mechanisms of Chaihu Shugan powder in the treatment of functional dyspepsia

BACKGROUND

Chaihu Shugan powder (CSP) is a prevalent prescription product used in the treatment functional dyspepsia (FD) in China. However, the underlying pharmacological mechanisms involved in the treatment of FD remain unclear.

OBJECTIVE

To explore the key components of CSP and their molecular targets and mechanisms in the treatment of FD.

METHODS

Active compounds for CSP were identified from the TCMSP and SymMap databases, and the relevant targets were predicted. FD-related targets were obtained from the CTD database. In addition, using the protein-protein interactions (PPI) analysis, the common targets were obtained. Furthermore, the compound-target networks were created with Cytoscape. Finally, molecular docking was performed to identify the core targets and validate them experimentally.

RESULTS

In total, 78 active compounds and 671 related targets of CSP were obtained. PPI network analysis identified 15 key FD-related compound targets. Molecular docking revealed that sitosterol and hyndarin exhibited good binding activities with AKT1 and IL6, respectively. Animal experiments have shown that CSP effectively increased the protein levels of AKT1 and reduced the serum levels of IL-6 in FD rats.

CONCLUSION

This study provides a theoretical evidence for the analysis of the molecular targets and mechanisms of the action of CSP in FD.

Staphylococcus aureus increases Prostaglandin E2 secretion in cow neutrophils by activating TLR2, TLR4, and NLRP3 inflammasome signaling pathways

Introduction

In clinical settings, dairy cows are often attacked by pathogenic bacteria after delivery, especially Staphylococcus aureus (S. aureus). Neutrophils have long been regarded as essential for host defense against S. aureus. Prostaglandin E₂ (PGE₂) can additionally be used as an inflammatory mediator in pathological conditions to promote the repair of inflammatory injuries. However, whether S. aureus can promote the accumulation of PGE₂ after the infection of neutrophils in cows and its mechanism remain unclear. Lipoprotein is an important immune bioactive ingredient of S. aureus.

Methods

In this study, the changes in neutrophils were monitored in dairy cows infected with wild-type S. aureus (SA113) and an S. aureus lipoprotein-deficient strain (Δlgt); meanwhile, we established whether pattern recognition receptors mediate this process and whether S. aureus lipoproteins are necessary for causing the release of PGE₂ from cow neutrophils.

Results

The results showed that Δlgt was less effective than SA113 in inducing the production of IL-1β, IL-6, IL-8, IL-10, and PGE₂ within neutrophils; furthermore, TLR2, TLR4, and NLRP3 receptors were found to mediate the inducible effect of lipoprotein on the above inflammation mediators and cytokines, which depended on MAPK and Caspase-1 signaling pathways. In addition, TLR2, TLR4, and NLRP3 inhibitors significantly inhibited PGE₂ and cytokine secretion, and PGE₂ was involved in the interaction of S. aureus and neutrophils in dairy cows, which could be regulated by TLR2, TLR4, and NLRP3 receptors. We also found that S. aureus was more likely to be killed by neutrophils when it lacked lipoprotein and TLR2, TLR4, and NLRP3 were involved, but PGE₂ seemed to have no effect.

Discussion

Taken together, these results suggest that lipoprotein is a crucial component of S. aureus in inducing cytokine secretion by neutrophils as well as killing within neutrophils, which could be accomplished by the accumulation of PGE₂ by activating MAPK and the Caspase-1 signaling pathways through TLR2, TLR4, and NLRP3 receptors. These results will contribute to a better understanding of the interaction between S. aureus and host immune cells in dairy cows.

PGE2 pathway mediates oxidative stress-induced ferroptosis in renal tubular epithelial cells

Prostaglandin E2 (PGE2) is one of the most abundant prostaglandins and has been implicated in various diseases. Here, we aimed to explore the role of the PGE2 pathway in mediating ferroptosis during acute kidney injury. When renal tubular epithelial cells stimulated by H₂ O₂ , the contents of glutathione (GSH) and glutathione peroxidase 4 (GPX4) decreased, whereas the level of lipid peroxide increased. Ferrostatin-1 can effectively attenuate these changes. In this process, the expression levels of cyclooxygenase (COX)-1 and COX-2 were up-regulated. Meanwhile, the expression of microsomal prostaglandin E synthase-2 was elevated, whereas the expression of microsomal prostaglandin E synthase-1 and cytosolic prostaglandin E synthase were down-regulated. Furthermore, the expression of 15-hydroxyprostaglandin dehydrogenase decreased. An excessive accumulation of PGE2 promoted ferroptosis, whereas the PGE2 inhibitor pranoprofen minimized the changes for COX-2, GSH, GPX4 and lipid peroxides. A decrease in the levels of the PGE2 receptor E-series of prostaglandin 1/3 partially restored the decline of GSH and GPX4 levels and inhibited the aggravation of lipid peroxide. Consistent with the in vitro results, increased PGE2 levels led to increased levels of 3,4-methylenedioxyamphetamine, Fe²⁺ accumulation and decreased GSH and GPX4 levels during renal ischaemia/reperfusion injury injury in mice. Our results indicate that the PGE2 pathway mediated oxidative stress-induced ferroptosis in renal tubular epithelial cells.

Potent Analgesic Action of 2-acetoxy-5-(2-4 (trifluoromethyl)-phenethylamino)-benzoic Acid (Flusalazine) in Experimental Mice

PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase (COX)-2 selective inhibitors are the most widely used drugs to treat pain. Conventional NSAIDs and COX-2 selective inhibitors, however, cause several side effects such as gastric damage, kidney damage, and cardiovascular problems. Our previous study showed that 2-acetoxy-5-(2-4-(trifluoromethyl)-phenethylamino)-benzoic acid ie, flusalazine (also known as ND-07), which exerts dual actions by serving both as an anti-inflammatory agent and a free radical scavenger, is an effective and safe treatment for severe inflammatory diseases in mice. The goal of the present study was to examine the potential analgesic action and safety of flusalazine in mice models of pain.

METHODS AND RESULTS

Flusalazine showed a significant analgesic effect in an acetic acid-induced abdominal constriction model. Likewise, total paw licking was reduced significantly in neurogenic (early stage) and inflammatory (late stage) pain induced by formalin in flusalazine-treated mice. In the tail immersion test, flusalazine significantly increased tail withdrawal time at 2 h after its administration. Also, the formation of paw edema in the flusalazine-treated group was significantly inhibited in a carrageenan-induced inflammatory pain model. Gastric damage was not induced by flusalazine even up to 1000 mg/kg, while aspirin and indomethacin caused critical gastric bleeding.

CONCLUSION

These findings suggest that flusalazine's safety profile and analgesic effects have high translational potential for the clinical treatment of patients experiencing pain.

In vitro and in vivo neuroprotective effect of novel mPGES-1 inhibitor in animal model of Parkinson's Disease

mPGES-1 is found to be up-regulated in the dopaminergic neurons of the substantia nigra pars compacta (SNpc) of postmortem brain tissue from Parkinson's disease (PD) patients and neurotoxin 6-hydroxydopamine (6-OHDA)-induced PD mice. Since the genetic deletion of mPGES-1 abolished 6-OHDA-induced PGE₂ production and 6-OHDA-induced dopaminergic neurodegeneration in vitro and in vivo models, mPGES-1 enzyme has the potential to be an important target for PD therapy. In the present work, we investigated whether a small organic molecule as mPGES-1 inhibitor could exhibit the neuroprotective effects against 6-OHDA-induced neurotoxicity in in vitro and in vivo models. For this research goal, a new series of arylsulfonyl hydrazide derivatives was prepared and investigated whether these compounds may protect neurons against 6-OHDA-induced neurotoxicity in both in vitro and in vivo studies. Among them, compound 7s (MPO-0144) as a mPGES-1 inhibitor (PGE₂ IC₅₀ = 41.77 nM; mPGES-1 IC₅₀ = 1.16 nM) exhibited a potent neuroprotection (ED₅₀ = 3.0 nM) against 6-OHDA-induced in PC12 cells without its own neurotoxicity (IC₅₀ = >10 μM). In a 6-OHDA-induced mouse model of PD, administration of compound 7s (1 mg/kg/day, for 7days, i.p.) ameliorated motor impairments and dopaminergic neuronal damage. These significant biological effects of compound 7s provided the first pharmacological evidence that mPGES-1 inhibitor could be a promising therapeutic agent for PD patients.

Targeting EP2 receptor with multifaceted mechanisms for high-risk neuroblastoma

Prostaglandin E₂ (PGE₂) promotes tumor cell proliferation, migration, and invasion, fostering an inflammation-enriched microenvironment that facilitates angiogenesis and immune evasion. However, the PGE₂ receptor subtype (EP1–EP4) involved in neuroblastoma (NB) growth remains elusive. Herein, we show that the EP2 receptor highly correlates with NB aggressiveness and acts as a predominant Gα_s-coupled receptor mediating PGE₂-initiated cyclic AMP (cAMP) signaling in NB cells with high-risk factors, including 11q deletion and MYCN amplification. Knockout of EP2 in NB cells blocks the development of xenografts, and its conditional knockdown prevents established tumors from progressing. Pharmacological inhibition of EP2 by our recently developed antagonist TG6-129 suppresses the growth of NB xenografts in nude mice and syngeneic allografts in immunocompetent hosts, accompanied by anti-inflammatory, antiangiogenic, and apoptotic effects. This proof-of-concept study suggests that the PGE₂/EP2 signaling pathway contributes to NB malignancy and that EP2 inhibition by our drug-like compounds provides a promising strategy to treat this deadly pediatric cancer.

Hou et al. discover that prostaglandin receptor EP2 highly correlates with the aggressiveness of neuroblastoma, where it acts as the primary PGE₂ receptor mediating cAMP signaling. EP2 deficiency or inhibition suppresses neuroblastoma with high-risk factors including 11q deletion and MYCN amplification, demonstrating EP2 as a promising therapeutic target for neuroblastoma.

(9S,13R)-12-oxo-phytodienoic acid attenuates inflammation by inhibiting mPGES-1 and modulating macrophage polarization via NF-κB and Nrf2/HO-1 pathways

Non-steroidal anti-inflammatory drugs (NSAIDs) relieve inflammation by suppressing prostaglandin E₂/cyclooxygenase 2 (PGE₂/COX-2) with cardiovascular and gastrointestinal bleeding risk. Theoretically, suppressing PGE₂ through inhibiting the terminal synthase microsomal prostaglandin E₂ synthase-1 (mPGES-1) instead of upstream COX-2 is ideal for inflammation. Here, (9S,13R)-12-oxo-phytodienoic acid (AA-24) extracted from Artemisia anomala was first screened as an anti-inflammatory candidate and decreased inducible nitric oxide synthase (iNOS), nitric oxide (NO), mPGES-1, and PGE₂ without affecting COX-1/2, thromboxane A₂ (TXA₂) and prostaglandin I₂ (PGI₂). Besides, AA-24 suppressed the differentiation of M0 macrophages to M1 phenotype but enhanced it to M2 phenotype, blocked the activation of NF-κB pathway, and increased the activation of Nrf2 and heme oxygenase-1 (HO-1). Moreover, AA-24 selectively inhibited mPGES-1 and reduced inflamed paw edema in carrageenan-induced mice. In conclusion, AA-24 attenuates inflammation by inhibiting mPGES-1 and modulating macrophage polarization via the NF-κB and Nrf2/HO-1 pathways and could be a promising candidate for developing anti-inflammatory drugs.

α-Lipoic acid ameliorates inflammation state and oxidative stress by reducing the content of bioactive lipid derivatives in the left ventricle of rats fed a high-fat diet

Lipid mediators derived from arachidonic acid (AA) are implicated with the occurrence of inflammation and oxidative stress. The current knowledge of AA metabolism focuses on searching for the therapeutic strategy to subvert affected AA metabolism. The aim of our study was to evaluate the potential protective effect of chronic α-lipoic acid (α-LA) supplementation on myocardial inflammation state and oxidative stress in obesity-related cardiovascular dysfunction. The experiment was carried out on male Wistar rats receiving a standard or a high-fat diets with intragastric α-LA administration for 8 weeks. Plasma and myocardial AA concentration was determined using gas-liquid chromatography (GLC). The Western blot technique was used to examine the expression of proteins from the inflammatory pathway. The content of selected cytokines, inflammatory mediators, and oxidative stress indicators was detected by ELISA, colorimetric, and multiplex assay kits. Our results revealed that α-LA caused a notable reduction in AA content, mainly in the phospholipid fraction with a simultaneous diminishment in the synthesis of pro-inflammatory mediators, i.e., prostaglandin E2, leukotrienes B4 and C4 by decreasing the expression of COX-2 and 5-LOX. α-LA also augmented the level of antioxidative SOD2 and GSH and decreased the level of lipid peroxidation products, which improved oxidative system impairment in the left ventricle tissue. The data clearly showed that α-lipoic acid has a significant role in inflammation and oxidative stress development ameliorating the risk of cardiac obesity induced by high-fat feeding.

Orai2 channel regulates prostaglandin E2 production in TNFα/IL1α-stimulated astrocytes

Astrocytes are glial cells that serve homeostatic functions in the central nervous system (CNS). Recent research, however, suggests that under pathological conditions, astrocytes are stimulated by various factors and actively participate in CNS inflammation. In the present study, we found that astrocytes upregulate various inflammatory factors including prostaglandin E₂ (PGE₂ ) by co-stimulation with tumor necrosis factor-alpha (TNFα) and interleukin-1alpha (IL1α). These TNFα/IL1α-stimulated astrocytes also showed increased Ca²⁺ release from the endoplasmic reticulum (ER) and increased expression of Orai2, a member of the store-operated calcium channel (SOCC) family. To reveal the role of Orai2, we used astrocytes in which Orai2 was knocked-down (KD) or knocked-out (KO). The expression of the prostaglandin E synthase Ptges and the production of PGE₂ were higher in Orai2-KD astrocytes than in WT astrocytes when stimulated with TNFα and IL1α. Orai2-KO astrocytes also showed increased expression of Ptges and increased PGE₂ production. The expression of Ptgs2, another PGE₂ synthetic enzyme, was also upregulated in Orai2-KO astrocytes. Moreover, Orai2-KO astrocytes showed increased store-operated calcium entry (SOCE) and increased Orai1 expression. These results suggest that Orai2 is upregulated in TNFα/IL1α-stimulated astrocytes and reduces PGE₂ production to some extent, modulating CNS inflammation. Our findings may aid in understanding how astrocytes are associated with inflammatory responses, and the identification of new targets that modulate astrocytic reactivity.

Sinomenine increases the methylation level at specific GCG site in mPGES-1 promoter to facilitate its specific inhibitory effect on mPGES-1

Prostaglandin E₂ (PGE₂) in cancer and inflammatory diseases is a key mediator of disease progression. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to inhibit the expression of PGE₂ by depressing cyclooxygenase (COX) in inflammatory treatments. However, the inhibition to COXs may cause serious side effects. Thus, it is urgent to develop new anti-inflammatory drugs aiming new targets to inhibit PGE₂ production. Microsomal prostaglandin E synthase 1 (mPGES-1) catalyzes the final step of PGE₂ biosynthesis. Therefore, the selective inhibition of mPGES-1 has become a promising strategy in the treatments of cancer and inflammatory diseases. Our previous studies confirmed that sinomenine (SIN) is a specific mPGES-1 inhibitor. However, the exact mechanism by which SIN inhibits mPGES-1 remains unknown. This study aimed to explain the regulation effect of SIN to mPGES-1 gene expression by its DNA methylation induction effect. We found that the demethylating agent 5-azacytidine (5-AzaC) reversed the inhibitory effect of SIN to mPGES-1. Besides, SIN selectively increased the methylation level of the promoter region in the mPGES-1 gene while the pretreatment of 5-AzaC suppressed this effect. The results also shows that pretreatment with SIN increased the methylation level of specific GCG sites in the promoter region of mPGES-1. This specific methylation site may become a new biomarker for predicting and diagnosing RA and cancer with high expression of mPGES-1. Also, our research provides new ideas and solutions for clinical diagnosis and treatment of diseases related to mPGES-1 and for targeted methylation strategy in drug development.

Computer-Aided Drug Design of Anti-inflammatory Agents Targeting Microsomal Prostaglandin E2 Synthase-1 (mPGES-1)

Inflammation is a natural process in response to external stimuli associated with organism protection. However, this reaction could be exaggerated, leading to severe damages related to physiopathological processes, such as rheumatoid arthritis, cancer, diabetes, allergies, infections, among others. Inflammation is mainly characterized by pain, increased temperature, flushing, and edema, which can be controlled using anti-inflammatory drugs. In this context, prostaglandin E2 (PGE2) inhibition has been targeted for designing new compounds with anti-inflammatory properties. It is a bioactive lipid overproduced during an inflammatory process, in which its increased production is carried out mainly by COX-1, COX-2, and microsomal prostaglandin E2 synthase-1 (mPGES-1). Recently, studies have demonstrated that mPGES-1 inhibition is a safe strategy to develop anti-inflammatory agents, which could protect against pain, acute inflammation, arthritis, autoimmune diseases, and different types of cancers. To decrease production costs and increase the probability of discovering active substances, computer-aided drug design (CADD) approaches have been increasingly used for designing new inhibitors. Thus, this review will cover all aspects involving high-throughput virtual screening, molecular docking, dynamics, fragment-based drug design, quantitative structure-activity relationship in seeking new promising mPGES-1 inhibitors.

Combined royal jelly 10-hydroxydecanoic acid and aspirin has a synergistic effect against memory deficit and neuroinflammation

Alzheimer's disease (AD), the most common form of neurodegenerative dementia among the older population, is associated with acute or chronic inflammation. As a nonsteroidal anti-inflammatory drug, aspirin has recently been widely studied in the prevention and treatment of neurodegenerative diseases. However, there is a controversy about the efficacy as well as the adverse effects of aspirin. 10-Hydroxydecanoic acid (10-HDAA) is a characteristic fatty acid found in the honey bee product royal jelly. In this study, we found that 10-HDAA attenuated the activation of the NF-κB pathway, then targeted Ptgs-1/2, the well-known target of aspirin. Hence, combined therapy of 10-HDAA and aspirin was conducted. In vitro assays suggested that this combinatory group alleviated LPS-induced inflammation in BV-2 cells, as assessed by the downregulation of nitric oxide, COX-2, and IL-6 compared to 10-HDAA or aspirin treatment alone. In vivo assays showed that the combined treatment synergistically inhibited the overactivation of glial cells and decreased the levels of pro-inflammatory mediators. Moreover, 10-HDAA alleviated the adverse effects of aspirin on gastrointestinal injuries and microbiota dysbiosis. The Morris water maze test indicated that neither 10-HDAA nor aspirin effectively improved LPS-induced memory dysfunction, but the combined therapy showed synergistic effects. Altogether, our findings support 10-HDAA and aspirin combinatory therapy as the basis for future therapeutics for AD and other neuroinflammation-related diseases with minimal adverse effects.

In Silico, In Vitro, and In Vivo Analysis of Tanshinone IIA and Cryptotanshinone from Salvia miltiorrhiza as Modulators of Cyclooxygenase-2/mPGES-1/Endothelial Prostaglandin EP3 Pathway

Tanshinone IIA (TIIA) and cryptotanshinone (CRY) from Salvia miltiorrhiza Bunge were investigated for their inhibitory activity against the cyclooxygenase-2 (COX-2)/microsomal prostaglandin E synthase-1 (mPGES-1)/endothelial prostaglandin 3 (EP3) pathway using in silico, in vitro, in vivo, and ex vivo assays. From the analysis of the docking poses, both diterpenoids were able to interact significantly with COX-2, 5-lipoxygenase (5-LO), platelet-activating factor receptor (PAFR), and mPGES-1. This evidence was further corroborated by data obtained from a cell-free assay, where CRY displayed a significant inhibitory potency against mPGES-1 (IC50 = 1.9 ± 0.4 µM) and 5-LO (IC50 = 7.1 µM), while TIIA showed no relevant inhibition of these targets. This was consistent with their activity to increase mice bleeding time (CRY: 2.44 ± 0.13 min, p ≤ 0.001; TIIA: 2.07 ± 0.17 min p ≤ 0.01) and with the capability to modulate mouse clot retraction (CRY: 0.048 ± 0.011 g, p ≤ 0.01; TIIA: 0.068 ± 0.009 g, p ≤ 0.05). For the first time, our results show that TIIA and, in particular, CRY are able to interact significantly with the key proteins involved not only in the onset of inflammation but also in platelet activity (and hyper-reactivity). Future preclinical and clinical investigations, together with this evidence, could provide the scientific basis to consider these compounds as an alternative therapeutic approach for thrombotic- and thromboembolic-based diseases.

Protectin DX promotes the inflammatory resolution via activating COX-2/L-PGDS-PGD2 and DP1 receptor in acute respiratory distress syndrome

PURPOSE

Acute respiratory distress syndrome (ARDS) is characterized by uncontrollable inflammation. Cyclooxygenase-2(COX-2) and its metabolite prostaglandins are known to promote the inflammatory resolution of ARDS. Recently, a newly discovered endogenous lipid mediator, Protectin DX (PDX), was also shown to mediate the resolution of inflammation. However, the regulatory of PDX on the pro-resolving COX-2 in ARDS remains unknown.

MATERIAL AND METHODS

PDX (5 μg/kg) was injected into rats intravenously 12 h after the lipopolysaccharide (LPS, 3 mg/kg) challenge. Primary rat lung fibroblasts were incubated with LPS (1 μg/ml) and/or PDX (100 nM). Lung pathological changes examined using H&E staining. Protein levels of COX-2, PGDS and PGES were evaluated using western blot. Inflammatory cytokines were tested by qPCR, and the concentration of prostaglandins measured by using ELISA.

RESULTS

Our study revealed that, COX-2 and L-PGDS has biphasic activation characteristics that LPS could induce induced by LPS both in vivo and in vitro.. The secondary peak of COX-2, L-PGDS-PGD2 promoted the inflammatory resolution in ARDS model with the DP1 receptor being activated and PDX up-regulated the inflammatory resolutionvia enhancing the secondary peak of COX-2/L-PGDS-PGD2 and activating the DP1 receptor.

CONCLUSION

PDX promoted the resolution of inflammation of ARDS model via enhancing the expression of secondary peak of COX-2/L-PGDS-PGD2 and activating the DP1 receptor. PDX shows promising therapeutic potential in the clinical management of ARDS.

Analysis of Sex-Specific Prostanoid Production Using a Mouse Model of Selective Cyclooxygenase-2 Inhibition

Background:

Prostanoids are a family of lipid mediators formed from arachidonic acid by cyclooxygenase enzymes and serve as biomarkers of vascular function. Prostanoid production may be different in males and females indicating that different therapeutic approaches may be required during disease.

Objectives:

We examined sex-dependent differences in COX-related metabolites in genetically modified mice that produce a cyclooxygenase-2 (COX2) enzyme containing a tyrosine 385 to phenylalanine (Y385F) mutation. This mutation renders the COX2 enzyme unable to form a key intermediate radical required for complete arachidonic acid metabolism and provides a model of selective COX2 inhibition.

Design and Methods:

Mice heterozygous for the Y385F mutation in COX2 were mated to produce cohorts of wild-type, heterozygous, and COX2 mutant mice. We investigated whether the genotype distribution followed Mendelian genetics and studied whether sex-specific differences could be found in certain prostanoid levels measured in peritoneal macrophages and in urinary samples.

Results:

The inheritance of the COX2 mutation displayed a significant deviation with respect to Mendel’s laws of genetics, with a lower-than-expected progeny of weaned COX2 mutant pups. In macrophages, prostaglandin E2 (PGE2) production following lipopolysaccharide (LPS) and interferon gamma (IFNγ) stimulation was COX2-dependent in both males and females, and data indicated that crosstalk between the nitric oxide (NO) and COX2 pathways may be sex specific. We observed significant differences in urinary PGE2 production by male and female COX2 mutant mice, with the loss of COX2 activity in male mice decreasing their ability to produce urinary PGE2. Finally, female mice across all 3 genotypes produced similar levels of urinary thromboxane (measured as 11-dehydro TxB2) at significantly higher levels than males, indicating a sex-related difference that is likely COX1-derived.

Conclusions:

Our findings clearly demonstrate that sex-related differences in COX-derived metabolites can be observed, and that other pathways (such as the NO pathway) are affected.

Characterization of airborne PAHs and metals associated with PM10 fractions collected from an urban area of Sri Lanka and the impact on airway epithelial cells

Airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are significant contributors leading to many human health issues. Thus, this study was designed to perform chemical analysis and biological impact of airborne particulate matter 10 (PM₁₀) in the World heritage City of Kandy City in Sri Lanka. 12 priority PAHs and 34 metals, including 10 highly toxic HMs were quantified. The biological effects of organic extracts were assayed using an in vitro primary porcine airway epithelial cell culture model. Cytotoxicity, DNA damage, and gene expressions of selected inflammatory and cancer-related genes were also assessed. Results showed that the total PAHs ranged from 3.062 to 36.887 ng/m³. The metals were dominated by Na > Ca > Mg > Al > K > Fe > Ti, while a few toxic HMs were much higher in the air than the existing ambient air quality standards. In the bioassays, a significant cytotoxicity (p < 0.05) was observed at 300 μg/mL treatment, and significant (p < 0.05) DNA damages were noted in all treatment groups. All genes assessed were found to be significantly up-regulated (p < 0.05) after 24 h of exposure and after 48 h, only TGF-β1 and p53 did not significantly up-regulate (p < 0.05). These findings confirm that the Kandy city air contains potential carcinogenic and mutagenic compounds and thus, exposure to Kandy air may increase the health risks and respiratory tract-related anomalies.

Ethoxy acetalated dextran-based nanocarriers accomplish efficient inhibition of leukotriene formation by a novel FLAP antagonist in human leukocytes and blood

Leukotrienes are pro-inflammatory lipid mediators generated by 5-lipoxygenase aided by the 5-lipoxygenase-activating protein (FLAP). BRP-201, a novel benzimidazole-based FLAP antagonist, inhibits leukotriene biosynthesis in isolated leukocytes. However, like other FLAP antagonists, BRP-201 fails to effectively suppress leukotriene formation in blood, which limits its therapeutic value. Here, we describe the encapsulation of BRP-201 into poly(lactide-co-glycolide) (PLGA) and ethoxy acetalated dextran (Ace-DEX) nanoparticles (NPs), aiming to overcome these detrimental pharmacokinetic limitations and to enhance the bioactivity of BRP-201. NPs loaded with BRP-201 were produced via nanoprecipitation and the physicochemical properties of the NPs were analyzed in-depth using dynamic light scattering (size, dispersity, degradation), electrophoretic light scattering (effective charge), NP tracking analysis (size, dispersity), scanning electron microscopy (size and morphology), UV-VIS spectroscopy (drug loading), an analytical ultracentrifuge (drug release, degradation kinetics), and Raman spectroscopy (chemical attributes). Biological assays were performed to study cytotoxicity, cellular uptake, and efficiency of BRP-201-loaded NPs versus free BRP-201 to suppress leukotriene formation in primary human leukocytes and whole blood. Both PLGA- and Ace-DEX-based NPs were significantly more efficient to inhibit leukotriene formation in neutrophils versus free drug. Whole blood experiments revealed that encapsulation of BRP-201 into Ace-DEX NPs strongly increases its potency, especially upon pro-longed (≥ 5 h) incubations and upon lipopolysaccharide-challenge of blood. Finally, intravenous injection of BRP-201-loaded NPs significantly suppressed leukotriene levels in blood of mice in vivo. These results reveal the feasibility of our pharmacological approach using a novel FLAP antagonist encapsulated into Ace-DEX-based NPs with improved efficiency in blood to suppress leukotriene biosynthesis.

Sperm-Guiding Unconventional Prostaglandins in C. elegans: Synthesis and Signaling

Prostaglandins comprise a family of lipid signaling molecules derived from polyunsaturated fatty acids and are involved in a wide array of biological processes, including fertilization. Prostaglandin-endoperoxide synthase (a.k.a. cyclooxygenase or Cox) initiates prostaglandin synthesis from 20-carbon polyunsaturated fatty acids, such as arachidonic acid. Oocytes of Caenorhabditis elegans (C. elegans) have been shown to secrete sperm-guidance cues prostaglandins, independent of Cox enzymes. Both prostaglandin synthesis and signal transduction in C. elegans are environmentally modulated pathways that regulate sperm guidance to the fertilization site. Environmental factors such as food triggers insulin and TGF-β secretion and their levels regulate tissue-specific prostaglandin synthesis in C. elegans. This novel PG pathway is abundant in mouse and human ovarian follicular fluid, where their functions, mechanism of synthesis and pathways remain to be established. Given the importance of prostaglandins in reproductive processes, a better understanding of how diets and other environmental factors influence their synthesis and function may lead to new strategies towards improving fertility in mammals.

Microsomal Prostaglandin E Synthase-1 (mPGES-1) is involved in the metabolic and cardiovascular alterations associated with obesity

BACKGROUND AND PURPOSE

Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible isomerase responsible for prostaglandin E₂ production in inflammatory conditions. We evaluated the role of mPGES-1 in obesity development and in the metabolic and cardiovascular alterations associated.

EXPERIMENTAL APPROACH

mPGES-1^+/+ and mPGES-1^-/- mice were fed with normal or high fat diet (HFD, 60% fat). The glycaemic and lipid profile was studied by glucose and insulin tolerance tests and colorimetric assays. Vascular function, structure and mechanics were evaluated by myography. Histological studies, q-RT-PCR and Western Blot analyses were performed in adipose tissue depots and cardiovascular tissues. Gene expression in abdominal fat and perivascular adipose tissue (PVAT) from patients and its correlation with vascular damage was determined.

KEY RESULTS

Male mPGES-1^-/- mice fed with HFD were protected against body weight gain and showed reduced adiposity, better glucose tolerance and insulin sensitivity, lipid levels and less white adipose tissue and PVAT inflammation and fibrosis, compared to mPGES-1^+/+ mice. mPGES-1 knockdown prevented cardiomyocyte hypertrophy, cardiac fibrosis, endothelial dysfunction, aortic insulin resistance, and vascular inflammation and remodeling, induced by HFD. Obesity-induced weight gain and endothelial dysfunction of resistance arteries were ameliorated in female mPGES-1^-/- mice. In humans, we found a positive correlation between mPGES-1 expression in abdominal fat and vascular remodeling, vessel stiffness and systolic blood pressure. In human PVAT, there was a positive correlation between mPGES-1 expression and inflammatory markers.

CONCLUSIONS AND IMPLICATIONS

mPGES-1 inhibition might be a novel therapeutic approach for the management of obesity and the associated cardiovascular and metabolic alterations.

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

Inflammation is closely linked to the abnormal phospholipid metabolism chain of cyclooxygenase-2/microsomal prostaglandin E₂ synthase-1/prostaglandin E₂ (COX-2/mPGES-1/PGE₂). In clinical practice, non-steroidal anti-inflammatory drugs (NSAIDs) as upstream COX-2 enzyme activity inhibitors are widely used to block COX-2 cascade to relieve inflammatory response. However, NSAIDs could also cause cardiovascular and gastrointestinal side effects due to its inhibition on other prostaglandins generation. To avoid this, targeting downstream mPGES-1 instead of upstream COX is preferable to selectively block overexpressed PGE₂ in inflammatory diseases. Some mPGES-1 inhibitor candidates including synthetic compounds, natural products and existing anti-inflammatory drugs have been proved to be effective in in vitro experiments. After 20 years of in-depth research on mPGES-1 and its inhibitors, ISC 27864 have completed phase II clinical trial. In this review, we intend to summarize mPGES-1 inhibitors focused on their inhibitory specificity with perspectives for future drug development.

Exploration of Long-Chain Vitamin E Metabolites for the Discovery of a Highly Potent, Orally Effective, and Metabolically Stable 5-LOX Inhibitor that Limits Inflammation

Endogenous long-chain metabolites of vitamin E (LCMs) mediate immune functions by targeting 5-lipoxygenase (5-LOX) and increasing the systemic concentrations of resolvin E3, a specialized proresolving lipid mediator. SAR studies on semisynthesized analogues highlight α-amplexichromanol (27a), which allosterically inhibits 5-LOX, being considerably more potent than endogenous LCMs in human primary immune cells and blood. Other enzymes within lipid mediator biosynthesis were not substantially inhibited, except for microsomal prostaglandin E2 synthase-1. Compound 27a is metabolized by sulfation and β-oxidation in human liver-on-chips and exhibits superior metabolic stability in mice over LCMs. Pharmacokinetic studies show distribution of 27a from plasma to the inflamed peritoneal cavity and lung. In parallel, 5-LOX-derived leukotriene levels decrease, and the inflammatory reaction is suppressed in reconstructed human epidermis, murine peritonitis, and experimental asthma in mice. Our study highlights 27a as an orally active, LCM-inspired drug candidate that limits inflammation with superior potency and metabolic stability to the endogenous lead.

Sex-dependent compensatory mechanisms preserve blood pressure homeostasis in prostacyclin receptor-deficient mice

Inhibitors of microsomal prostaglandin E synthase 1 (mPGES-1) are in the early phase of clinical development. Deletion of mPges-1 in mice confers analgesia, restrains atherogenesis, and fails to accelerate thrombogenesis, while suppressing prostaglandin E2 (PGE2), but increasing the biosynthesis of prostacyclin (PGI2). In low-density lipoprotein receptor-deficient (Ldlr-/-) mice, this last effect represents the dominant mechanism by which mPges-1 deletion restrains thrombogenesis, while suppression of PGE2 accounts for its antiatherogenic effect. However, the effect of mPges-1 depletion on blood pressure (BP) in this setting remains unknown. Here, we show that mPges-1 depletion significantly increased the BP response to salt loading in male Ldlr-/- mice, whereas, despite the direct vasodilator properties of PGI2, deletion of the I prostanoid receptor (Ipr) suppressed this response. Furthermore, combined deletion of the Ipr abrogated the exaggerated BP response in male mPges-1-/- mice. Interestingly, these unexpected BP phenotypes were not observed in female mice fed a high-salt diet (HSD). This is attributable to the protective effect of estrogen in Ldlr-/- mice and in Ipr-/- Ldlr-/- mice. Thus, estrogen compensates for a deficiency in PGI2 to maintain BP homeostasis in response to high salt in hyperlipidemic female mice. In male mice, by contrast, the augmented formation of atrial natriuretic peptide (ANP) plays a similar compensatory role, restraining hypertension and oxidant stress in the setting of Ipr depletion. Hence, men with hyperlipidemia on a HSD might be at risk of a hypertensive response to mPGES-1 inhibitors.

Pharmacogenomics of Hypersensitivity to Non-steroidal Anti-inflammatory Drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are extensively prescribed in daily clinical practice. NSAIDs are the main cause of drug hypersensitivity reactions all over the world. The inhibition of cyclooxygenase enzymes by NSAIDs can perpetuate arachidonic acid metabolism, shunting to the 5-lipoxygenase pathway and its downstream inflammatory process. Clinical phenotypes of NSAID hypersensitivity are diverse and can be classified into cross-reactive or selective responses. Efforts have been made to understand pathogenic mechanisms, in which, genetic and epigenetic backgrounds are implicated in various processes of NSAID-induced hypersensitivity reactions. Although there were some similarities among patients, several genetic polymorphisms are distinct in those exhibiting respiratory or cutaneous symptoms. Moreover, the expression levels, as well as the methylation status of genes related to immune responses were demonstrated to be involved in NSAID-induced hypersensitivity reactions. There is still a lack of data on delayed type reactions. Further studies with a larger sample size, which integrate different genetic pathways, can help overcome current limitations of gen etic/epigenetic studies, and provide valuable information on NSAID hypersensitivity reactions.

From Vietnamese plants to a biflavonoid that relieves inflammation by triggering the lipid mediator class switch to resolution

Chronic inflammation results from excessive pro-inflammatory signaling and the failure to resolve the inflammatory reaction. Lipid mediators orchestrate both the initiation and resolution of inflammation. Switching from pro-inflammatory to pro-resolving lipid mediator biosynthesis is considered as efficient strategy to relieve chronic inflammation, though drug candidates exhibiting such features are unknown. Starting from a library of Vietnamese medical plant extracts, we identified isomers of the biflavanoid 8-methylsocotrin-4'-ol from Dracaena cambodiana, which limit inflammation by targeting 5-lipoxygenase and switching the lipid mediator profile from leukotrienes to specialized pro-resolving mediators (SPM). Elucidation of the absolute configurations of 8-methylsocotrin-4'-ol revealed the 2S,γS-isomer being most active, and molecular docking studies suggest that the compound binds to an allosteric site between the 5-lipoxygenase subdomains. We identified additional subordinate targets within lipid mediator biosynthesis, including microsomal prostaglandin E2 synthase-1. Leukotriene production is efficiently suppressed in activated human neutrophils, macrophages, and blood, while the induction of SPM biosynthesis is restricted to M2 macrophages. The shift from leukotrienes to SPM was also evident in mouse peritonitis in vivo and accompanied by a substantial decrease in immune cell infiltration. In summary, we disclose a promising drug candidate that combines potent 5-lipoxygenase inhibition with the favorable reprogramming of lipid mediator profiles.

Discovery of N-amido-phenylsulfonamide derivatives as novel microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors

Our previous research showed that N-carboxy-phenylsulfonyl hydrazide (scaffold A) could reduce LPS-stimulated PGE₂ levels in RAW 264.7 macrophage cells by an inhibition of mPGES-1 enzyme. However, a number of scaffold A derivatives showed the drawbacks such as the formation of regioisomers and poor liver metabolic stability. In order to overcome these synthetic and metabolic problems, therefore, we decided to replace N-carboxy-phenylsulfonyl hydrazide (scaffold A) with N-carboxy-phenylsulfonamide (scaffold B) or N-amido-phenylsulfonamide frameworks (scaffold C) as a bioisosteric replacement. Among them, MPO-0186 (scaffold C) inhibited the production of PGE₂ (IC₅₀: 0.24 μM) in A549 cells via inhibition of mPGES-1 (IC₅₀: 0.49 μM in a cell-free assay) and was found to be approximately 9- and 8-fold more potent than MK-886 as a reference inhibitor, respectively. A molecular docking study theoretically suggests that MPO-0186 could inhibit PGE₂ production by blocking the PGH₂ binding site of mPGES-1 enzyme. Furthermore, MPO-0186 demonstrated good liver metabolic stability and no significant inhibition observed in clinically relevant CYP isoforms except CYP2C19. This result provides a potential starting point for the development of selective and potent mPGES-1 inhibitor with a novel scaffold.

Syk/NF-κB-targeted anti-inflammatory activity of Melicope accedens (Blume) T.G. Hartley methanol extract

ETHNOPHARMACOLOGICAL RELEVANCE

Melicope accedens (Blume) Thomas G. Hartley is a plant included in the family Rutaceae and genus Melicope. It is a native plant from Vietnam that has been used for ethnopharmacology. In Indonesia and Malaysia, the leaves of M. accedens are applied externally to decrease fever.

AIM OF THE STUDY

The molecular mechanisms of the anti-inflammatory properties of M. accedens are not yet understood. Therefore, we examined those mechanisms using a methanol extract of M. accedens (Ma-ME) and determined the target molecule in macrophages.

MATERIALS AND METHODS

We evaluated the anti-inflammatory effects of Ma-ME in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and in an HCl/EtOH-triggered gastritis model in mice. To investigate the anti-inflammatory activity, we performed a nitric oxide (NO) production assay and ELISA assay for prostaglandin E2 (PGE₂). RT-PCR, luciferase gene reporter assays, western blotting analyses, and a cellular thermal shift assay (CETSA) were conducted to identify the mechanism and target molecule of Ma-ME. The phytochemical composition of Ma-ME was analyzed by HPLC and LC-MS/MS.

RESULTS

Ma-ME suppressed the production of NO and PGE₂ and the mRNA expression of proinflammatory genes (iNOS, IL-1β, and COX-2) in LPS-stimulated RAW264.7 cells without cytotoxicity. Ma-ME inhibited NF-κB activation by suppressing signaling molecules such as IκBα, Akt, Src, and Syk. Moreover, the CETSA assay revealed that Ma-ME binds to Syk, the most upstream molecule in the NF-κB signal pathway. Oral administration of Ma-ME not only alleviated inflammatory lesions, but also reduced the gene expression of IL-1β and p-Syk in mice with HCl/EtOH-induced gastritis. HPLC and LC-MS/MS analyses confirmed that Ma-ME contains various anti-inflammatory flavonoids, including quercetin, daidzein, and nevadensin.

CONCLUSIONS

Ma-ME exhibited anti-inflammatory activities in vitro and in vivo by targeting Syk in the NF-κB signaling pathway. Therefore, we propose that Ma-ME could be used to treat inflammatory diseases such as gastritis.

Canagliflozin ameliorates hepatic fat deposition in obese diabetic mice: Role of prostaglandin E2

Clinical and animal studies have suggested a possible beneficial effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors on nonalcoholic fatty liver disease (NAFLD) including nonalcoholic steatohepatitis (NASH). Although SGLT2 inhibitors have been shown to reduce hepatic fat deposition in association with loss of body weight, the mechanism of this action has remained unknown. We here show that the SGLT2 inhibitor canagliflozin ameliorated fatty liver and hyperglycemia without affecting body weight or epididymal fat weight in obese diabetic KKAy mice. Lipidomics analysis based on liquid chromatography and tandem mass spectrometry revealed that canagliflozin treatment increased the amounts of prostaglandin E₂ (PGE₂) and resolvin E3 in the liver of these mice. We also found that PGE₂ attenuated fat deposition in mouse primary hepatocytes exposed to palmitic acid. Our results thus suggest that PGE₂ may play an important role in the amelioration of hepatic fat deposition by canagliflozin, with elucidation of its mechanism of action potentially providing a basis for the development of new therapeutics for NAFLD-NASH.

Ibuprofen-based advanced therapeutics: breaking the inflammatory link in cancer, neurodegeneration, and diseases

Ibuprofen is a classical nonsteroidal anti-inflammatory drug (NSAID) highly prescribed to reduce acute pain and inflammation under an array of conditions, including rheumatoid arthritis, osteoarthritis, dysmenorrhea, and gout. Ibuprofen acts as a potential inhibitor for cyclooxygenase enzymes (COX-1 and COX-2). In the past few decades, research on this small molecule has led to identifying other possible therapeutic benefits. Anti-tumorigenic and neuroprotective functions of Ibuprofen are majorly recognized in recent literature and need further consideration. Additionally, several other roles of this anti-inflammatory molecule have been discovered and subjected to experimental assessment in various diseases. However, the major challenge faced by Ibuprofen and other drugs of similar classes is their side effects, and tendency to cause gastrointestinal injury, generate cardiovascular risks, modulate hepatic and acute kidney diseases. Future research should also be conducted to deduce new methods and approaches of suppressing the unwanted toxic changes mediated by these drugs and develop new therapeutic avenues so that these small molecules continue to serve the purposes. This article primarily aims to develop a comprehensive and better understanding of Ibuprofen, its pharmacological features, therapeutic benefits, and possible but less understood medicinal properties apart from major challenges in its future application.KEY POINTSIbuprofen, an NSAID, is a classical anti-inflammatory therapeutic agent.Pro-apoptotic roles of NSAIDs have been explored in detail in the past, holding the key in anti-cancer therapies.Excessive and continuous use of NSAIDs may have several side effects and multiple organ damage.Hyperactivated Inflammation initiates multifold detrimental changes in multiple pathological conditions.Targeting inflammatory pathways hold the key to several therapeutic strategies against many diseases, including cancer, microbial infections, multiple sclerosis, and many other brain diseases.

IL-17-induced inflammation modulates the mPGES-1/PPAR-γ pathway in monocytes/macrophages

BACKGROUND AND PURPOSE

Recent biochemical and pharmacological studies have reported that in several tissues and cell types, microsomal PGE₂ synthase (mPGES) and PPAR-γ expression are modulated by a variety of inflammatory factors and stimuli. Considering that very little is known about the biological effects promoted by IL-17 in the context of mPGES-1/PPAR-γ modulation, we sought to investigate the contribution of this unique cytokine on this integrated pathway during the onset of inflammation.

EXPERIMENTAL APPROACH

We evaluated effects of PF 9184 (mPGES-1 inhibitor) and troglitazone (PPAR-γ agonist) in vitro, using the mouse macrophage cell line J774A.1. In vivo, the dorsal air pouch model in CD1 mice was used, and inflammatory infiltrates were analysed by flow cytometry. Locally produced cyto-chemokines and PGs were assessed using elisa assays. Western blots were also employed to determine the activity of various enzymes involved in downstream signalling pathways.

KEY RESULTS

PF 9184 and troglitazone, in a time- and dose-dependent manner, modulated leukocyte infiltration, myeloperoxidase activity, and the expression of COX-2/mPGES-1, NF-кB/IкB-α, and mPTGDS-1/PPAR-γ, induced by IL-17. Moreover, both PF 9184 and troglitazone modulated PG (PGE₂ , PGD₂ , and PGJ₂ ) production, the expression of different pro-inflammatory cyto-chemokines, and the recruitment of inflammatory monocytes, in response to IL-17.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that IL-17 may constitute a specific modulator of inflammatory monocytes during later phases of the inflammatory response. The results of this study show, for the first time, that the IL-17/mPGES-1/PPAR-γ pathway could represent a potential therapeutic target for inflammatory-based and immune-mediated diseases.

Overview on the Discovery and Development of Anti-Inflammatory Drugs: Should the Focus Be on Synthesis or Degradation of PGE2?

Inflammation is a protective response that develops against tissue injury and infection. Chronic inflammation, on the other hand, is the key player in the pathogenesis of many inflammatory disorders including cancer. The cytokine storm, an inflammatory response flaring out of control, is mostly responsible for the mortality in COVID-19 patients. Anti-inflammatory drugs inhibit cyclooxygenases (COX), which are involved in the biosynthesis of prostaglandins that promote inflammation. The conventional non-steroidal anti-inflammatory drugs (NSAIDs) are associated with gastric and renal side-effects, as they inhibit both the constitutive COX-1 and the inducible COX-2. The majority of selective COX-2 inhibitors (COXIBs) are without gastric side-effects but are associated with cardiac side-effects on long-term use. The search for anti-inflammatory drugs without side-effects, therefore, has become a dream and ongoing effort of the Pharma companies. As PGE₂ is the key mediator of inflammatory disorders, coming up with a strategy to reduce the levels of PGE₂ alone without affecting other metabolites may form a better choice for the development of next generation anti-inflammatory drugs. In this direction the options being explored are on synthesis of PGE₂-mPGES-1; PGE₂ degradation through a specific PG dehydrogenase, 15-PGDH, and by blocking its activity mediated through a specific PGE receptor, EP4. As leukotrienes formed via the 5-lipoxygenase (5-LOX) pathway also play an important role in the mediation of inflammation, efforts are also being made to target both COX and LOX pathways. This review focuses on addressing the following three points: 1) How NSAIDs and COXIBs are associated with gastric, renal and cardiac side-effects; 2) Should the focus be on the targets upstream or downstream of PGE₂; and 3) the status of alternative targets being explored for the discovery and development of anti-inflammatory drugs without side-effects.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/8Uufep6ipBQ

New insights into the obligatory nature of cyclooxygenase-2 and PGE2 during early chick embryogenesis

Temporal expression patterns and activity of two cyclooxygenase (COX-1 and COX-2) isoforms were analysed during early chick embryogenesis to evaluate their roles in development. COX-2 inhibition with etoricoxib resulted in significant structural anomalies such as anophthalmia (born without one or both eyes), phocomelia (underdeveloped or truncated limbs), and gastroschisis (an opening in the abdominal wall), indicating its significance in embryogenesis. Furthermore, the levels of PGE₂, PGD₂, PGF_2α, and TXB₂ were assessed using quantitative LC-MS/MS to identify which effector prostanoid (s) had their synthesis initiated by COX-2. COX-2 inhibition was only shown to reduce the level of PGE₂ significantly_, and hence it could be inferred that the later could be largely under the regulation of activated COX-2 in chick embryos. The compensatory increase in the activity of COX-1 observed in the etoricoxib-treated group helped to maintain the levels of PGD₂, PGF_2α, and TXB₂. Though the roles of these three prostanoids in embryogenesis need to be further clarified, it appears that their contribution to the observed developmental anomalies is minimal. This study has shown that COX-2 is functionally active during chick embryogenesis, and it plays a central role in the structural configuration of several organs and tissues through its downstream effector molecule PGE₂.