Therapy response monitoring of the early effects of a new BRAF inhibitor on melanoma xenograft in mice: evaluation of 18F‐FDG‐PET and 18F‐FLT‐PET

Inhibition of the V600E mutated BRAF kinase gene (BRAF^V600E) is an important and effective approach to treating melanomas. A new specific small molecule inhibitor of BRAF^V600E, PLX3603, showed potent melanoma growth‐inhibiting characteristics in preclinical studies and is currently under clinical investigation. In this study we investigated the feasibility of ¹⁸F‐FDG and ¹⁸F‐FLT‐PET to monitor the early effects of the BRAF^V600E inhibitor in mice with melanoma xenografts. SCID/beige mice with subcutaneous (s.c.) A375 melanoma xenografts, expressing BRAF^V600E, received the BRAF^V600E inhibitor twice daily orally (0, 25, 50 and 75 mg/kg). At 1, 3 and 7 days after start of therapy, the uptake of ¹⁸F‐FDG and ¹⁸F‐FLT in the tumor and normal tissues was determined in ex vivo tissue samples. Serial ¹⁸F‐FDG and ¹⁸F‐FLT‐PET scans were acquired of animals at 1 day before and 1, 3 and 7 days after start of treatment with 75 mg/kg BRAF^V600E inhibitor. A dose‐dependent decrease in ¹⁸F‐FDG uptake in the A375 tumors was observed by ex vivo biodistribution analysis. Administration of 75 mg/kg BRAF inhibitor for 1, 3 and 7 days resulted in a significantly decreased ¹⁸F‐FDG uptake in A375 tumors (41, 35 and 51%, respectively). ¹⁸F‐FLT uptake in the A375 tumors was low at baseline and no significant changes in ¹⁸F‐FLT uptake were observed at any of the doses administered. These effects were corroborated by serial in vivo ¹⁸F‐FDG and ¹⁸F‐FLT‐PET imaging. These data demonstrate that ¹⁸F‐FDG‐PET can be used as an imaging biomarker to noninvasively evaluate the early effects of PLX3603. Copyright © 2014 John Wiley & Sons, Ltd.     

Preliminary evaluation of novel 68Ga‐DOTAVAP‐PEG‐P2 peptide targeting vascular adhesion protein‐1

Introduction: Expression of vascular adhesion protein‐1 (VAP‐1) is induced at the sites of inflammation where extravasation of leukocytes from blood to the peripheral tissue occurs. VAP‐1 is a potential target for anti‐inflammatory therapy and for in vivo imaging of inflammation. Purpose of this study was to preliminarily evaluate a novel VAP‐1‐targeting peptide as a potential PET imaging agent. Methods: Cyclic 17‐amino‐acid peptide selected from phage display libraries was 1,4,7,10‐tetraazacyclododecane‐N,N′,N′′,N′′′‐tetraacetic acid (DOTA) conjugated via 8‐amino‐3,6‐diooxaoctanoyl linker (polyethylene glycol, PEG derivative) and labelled with ⁶⁸Ga (⁶⁸Ga‐DOTAVAP‐PEG‐P2). In vitro stability of ⁶⁸Ga‐DOTAVAP‐PEG‐P2 was determined in saline, rat plasma and human plasma by radio‐HLPC. Lipophilicity was measured by calculating octanol‐water partition coefficient (logP). Whole‐body distribution kinetics and stability after intravenous injection in healthy rats was studied in vivo by PET imaging, ex vivo by measuring radioactivity of excised tissues, and by radio‐HPLC. Results: In vitro the ⁶⁸Ga‐DOTAVAP‐PEG‐P2 remained stable >4 h in saline and rat plasma, but degraded slowly in human plasma after 2 h of incubation. The logP value of ⁶⁸Ga‐DOTAVAP‐PEG‐P2 was ?1·3. In rats, ⁶⁸Ga‐radioactivity cleared rapidly from blood circulation and excreted quickly in urine. At 120 min after injection the fraction of intact ⁶⁸Ga‐DOTAVAP‐PEG‐P2 were 77 ± 6·0% and 99 ± 1·0% in rat plasma and urine, respectively. Conclusions: These basic and essential in vitro and in vivo studies of the new VAP‐1 targeting peptide revealed promising properties for an imaging agent. Further investigations to clarify in vivo VAP‐1 targeting are warranted.     

Abdominal hyperalgesia in secretory phospholipase A2‐induced rat pancreatitis: Distinct roles of NK1 receptors

We investigated the potential of secretory phospholipase A₂ (sPLA₂)‐induced pancreatitis to promote abdominal hyperalgesia, as well as to depolarize sensory fibres in vitro using a grease‐gap technique. Pancreatitis was induced by the injection of sPLA₂ from Crotalus durissus terrificus (sPLA₂ Cdt, 300μgkg^?1) venom into the common bile duct of rats. Pancreatic inflammatory signs, serum amylase levels and abdominal hyperalgesia were evaluated in rats treated or not with SR140333, a tachykinin NK₁ receptor antagonist. Injection of sPLA₂ Cdt caused pancreatic oedema formation and increased pancreatic neutrophil infiltration and serum amylase at 4 h, which returned to normality by 24 h, except for the neutrophil infiltration, which was still increased at this time point. Animals injected with sPLA₂ exhibited a lower withdrawal threshold to electronic von Frey stimulation in the upper abdominal region at 4 h, but not 24 h, post‐injection when compared with saline‐injected rats. Pre‐treatment of animals with SR140333 significantly reduced the sPLA₂ Cdt‐induced abdominal hyperalgesia, without affecting the other parameters. Neither sPLA₂ Cdt nor sPLA₂ from Naja mocambique mocambique venom depolarized capsaicin‐sensitive sensory fibres from rat vagus nerve, but they decreased the propagated compound action potentials in both A and C fibres. These data show for the first time that NK₁ receptors play an important role in the early abdominal hyperalgesia in a rat model of sPLA₂‐induced pancreatitis, suggesting that these receptors are of importance in the development of pain in the pancreatitis condition. We also provide evidence that sPLA₂s do not directly depolarize sensory fibres in vitro.     

Transgenic analysis of the BmBLOS2 gene that governs the translucency of the larval integument of the silkworm,Bombyx mori

The larval integument of the silkworm, Bombyx mori, is opaque because urate granules accumulate in the epidermis. Although the biosynthetic pathway of uric acid is well studied, little is known about how uric acid accumulates as urate granules in epidermal cells. In the distinct oily (od) mutant silkworm, the larval integument is translucent because of the inability to construct urate granules. Recently, we have found that the od mutant has a genomic deletion in the B. mori homologue of the human biogenesis of lysosome‐related organelles complex1, subunit 2 (BLOS2) gene (BmBLOS2). Here, we performed a molecular and functional characterization of BmBLOS2. Northern blot analysis showed that BmBLOS2 was ubiquitously expressed in various tissues. We analysed the structure of a newly isolated mutant (od^B) allelic to od and found a premature stop codon in the coding sequence of BmBLOS2 in this new mutation. Moreover, the translucent phenotype was rescued by the germ‐line transformation of the wild‐type BmBLOS2 allele into the od mutant. Our results suggest that BmBLOS2 is responsible for the od mutant phenotype and plays a crucial role in biogenesis of urate granules in the larval epidermis of the silkworm. The relationships amongst Hermansky–Pudlak syndrome (HPS) genes in mammals, granule group genes in Drosophila and translucent mutant genes in B. mori are discussed.     

Spectroscopic,radiochemical, and theoretical studies of the Ga3+‐N‐2‐hydroxyethyl piperazine‐N′‐2‐ethanesulfonic acid (HEPES buffer) system: evidence for the formation of Ga3+‐ HEPES complexes in 68 Ga labeling reactions

Recent reports have claimed a superior performance of HEPES buffer in comparison to alternative buffer systems for ^67/68 Ga labeling in aqueous media. In this paper we report spectroscopic (¹H and ⁷¹ Ga NMR), radiochemical, mass spectrometry and theoretical modeling studies on the Ga³⁺/HEPES system (HEPES = N‐2‐hydroxyethylpiperazine‐N′‐2‐ethanesulfonic acid) performed with the aim of elucidating a potential contribution of HEPES in the ^68/67 Ga radiolabeling process. Our results demonstrate that HEPES acts as a weakly but competitive chelator of Ga³⁺ and that this interaction depends on the relative Ga³⁺: HEPES concentration. A by‐product formed in the labeling mixture has been identified as a [⁶⁸ Ga]Ga(HEPES) complex via chromatographic comparison with the nonradioactive analog. The formation of this complex was verified to compete with [⁶⁸ Ga]Ga(NOTA) complexation at low NOTA concentration. Putative chelation of Ga³⁺ by the hydroxyl and adjacent ring nitrogen of HEPES is proposed on the basis of ¹H NMR shifts induced by Ga³⁺ and theoretical modeling studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Catalytic function of an Epsilon‐class glutathione S‐transferase of the silkworm

The glutathione S‐transferase (GST) superfamily is involved in the detoxification of various xenobiotics. A silkworm GST, belonging to a previously reported Epsilon‐class GST family, was identified, named bmGSTE, cloned, and produced in Escherichia coli. Investigation of this enzyme's properties showed that it was able to catalyse glutathione (GSH) with 1‐chloro‐2,4‐dinitrobenzene and ethacrynic acid, and also that it possessed GSH‐dependent peroxidase activity. The enzyme's highly conserved amino acid residues, including Ser11, His53, Val55, Ser68 and Arg112, were of interest regarding their possible involvement in its catalytic activity. These residues were replaced with alanine by site‐directed mutagenesis and subsequent kinetic analysis of bmGSTE mutants indicated that His53, Val55, and Ser68 were important for enzyme function.     

Flow mediated vasodilation and circulating concentrations of high sensitive C‐reactive protein,interleukin‐6 and tumor necrosis factor‐α in normal pregnancy – The Cardiovascular Risk in Young Finns Study

Background: Traditional risk factors such as hyperlipidemia induce a state of inflammation that impairs vascular function. Despite marked maternal hyperlipidemia, endothelial function improves during pregnancy. In non‐pregnant state increased circulating levels of pro‐inflammatory cytokines and high sensitive C‐reactive protein (hsCRP) lead to attenuated flow mediated vasodilation. Relation between endothelial function and pro‐inflammatory cytokines has not been studied thoroughly in pregnancy. The aim of this study was to evaluate the effect of pregnancy on hsCRP and pro‐inflammatory cytokines and their associations with vascular endothelial function. Methods: As part of population‐based, prospective cohort Cardiovascular Risk in Young Finns study conducted in Finland we measured brachial artery flow mediated dilation (FMD) and serum concentrations of hsCRP, interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α) in 57 pregnant Finnish women throughout gestation and 62 control women matched for age and smoking. Results: HsCRP‐concentration was greater in pregnancy compared to non‐pregnant controls (median hsCRP 2·52 mg l^?1 versus 1·21 mg l^?1, P<0·001). IL‐6‐concentration was slightly increased in pregnancy compared with the non‐pregnant controls (median 1·66 versus 1·32 mg l^?1, non‐significant [NS]) and TNF‐α‐concentration was slightly decreased in pregnant group (2·11 versus 2·38 pg ml^?1, NS). FMD increased during pregnancy and IL‐6 had a positive correlation to the FMD in pregnancy (R = 0·288, P = 0·031). Conclusions: Improvement of FMD in normal pregnancy was not affected by increase in hsCRP concentration. We found an association with IL‐6 and FMD but we believe that improvement in endothelial function during normal pregnancy is not caused by variation in hsCRP, IL‐6 or TNF‐α.     

COX‐1+/−COX‐2−/− genotype in mice is associated with shortened time to carotid artery occlusion through increased PAI‐1

Summary. Background: We found a high incidence of thrombotic deaths in COX‐1^+/?COX‐2^?/? mice and sought to define the mechanism of these events. The cyclooxygenase products thromboxane A₂ and prostacyclin are important in the regulation of coagulation but their role in fibrinolysis is largely unexplored. PAI‐1 blocks fibrinolysis by inhibiting plasminogen activator. Aim: Our objective was to explain the mechanism of increased thrombosis associated with the COX‐1^+/?COX‐2^?/? genotype. Methods: Carotid artery occlusion times were measured after photochemical injury. PAI‐1 levels were measured in the plasma by ELISA. PAI‐1 levels in the aorta were measured by RT‐PCR and Western blotting. Urinary metabolites of Thromboxane A₂ and prostacyclin were measured by ELISA. Results: The COX‐1^+/?COX‐2^?/? genotype is associated with a decreased time to occlusion in the carotid artery thrombosis model (30 ± 5 minutes vs 60 ± minutes in wild type, p<.001). The COX‐1^?/?COX‐2^+/+, COX‐1^+/?COX‐2^+/? and COX‐1^+/? COX‐2^+/+ all had occlusion times similar to wild type. COX‐1^+/+ COX‐2^?/? had a prolonged occlusion time. COX‐1^+/? COX‐2^?/? had increased PAI‐1 levels in the plasma and aorta and with a prolonged euglobulin lysis time (37.4 ± 10.2 hours vs 15.6 ± 9.8 hours in wild type, p<.004). The decreased time to occlusion in the COX‐1^+/?COX2^?/? mice was normalized by an inhibitory antibody to PAI‐1 whereas the antibody had no effect on the time to occlusion in wild type mice. Conclusion: The COX‐1^+/?COX‐2^?/? genotype is associated with a shortened time to occlusion in the carotid thrombosis model and the shortened time to occlusion is mediated through increased PAI‐1 levels resulting in decreased fibrinolysis.     

In‐depth comparison of N‐glycosylation of human plasma‐derived factor VIII and different recombinant products: from structure to clinical implications

Essentials

• Glycosylation heterogeneity of recombinant proteins affects pharmacokinetics and immunogenicity.
• N‐glycomics/glycoproteomics of plasma‐derived Factor VIII and 6 recombinant FVIIIs were compared.
• Depending on cell line, significant differences to plasma‐derived FVIII were observed.
• Recombinant FVIIIs expressed distinct and immunologically relevant epitopes.

Summary

Background/Objective

Human factor VIII (FVIII) is a plasma glycoprotein, defects of which result in hemophilia A. Current substitution therapy uses FVIII products purified from human plasma or from various cell lines (recombinant FVIII) with different levels of B‐domain deletion. Glycosylation is a post‐translational protein modification in FVIII that has a substantial influence on its physical, functional and antigenic properties. Variation in glycosylation is likely to be the reason that FVIII products differ in their pharmacokinetics, pharmacodynamics and immunogenicity. However, the literature on FVIII glycosylation is inconsistent, preventing assembly into a coherent model. Seeking to better understand the glycosylation mechanisms underlying FVIII biology, we studied the N‐glycosylation of human plasma‐derived (pd)FVIII and six rFVIII products expressed in CHO, BHK or HEK cell lines.

Methods

FVIII samples were subjected to head‐to‐head detailed glycomic and glycoproteomic characterization using a combination of MALDI‐MS and MS/MS, GC‐MS and UPLC‐UV‐MS^E technologies.

Results/Conclusion

The results of our study detail the N‐glycan repertoire of pdFVIII to an unprecedented level, and for the first time, provide evidence of N‐glycolylneuraminic acid (NeuGc) found on pdFVIII. Although site‐specific glycosylation of rFVIII proved consistent with pdFVIII regardless of the expression system, the entire N‐glycan content of each sample appeared significantly different. Although the proportion of biologically important epitopes common to all samples (i.e. sialylation and high‐mannose) varied between samples, some recombinant products expressed distinct and immunologically relevant epitopes, such as LacdiNAc (LDN), fucosylated LacdiNAc (FucLDN), NeuGc, Lewis^X/Y and Gal_α1,3Gal epitopes. rFVIII expressed in HEK cells showed the greatest glycomic differences to human pdFVIII.     

The nuclear hormone receptor E75A regulates vitellogenin gene (Al‐Vg) expression in the mirid bug Apolygus lucorum

Apolygus lucorum is the predominant pest of Bacillus thuringiensis (Bt) cotton in China. 20‐hydroxyecdysone (20E) plays a key role in the reproduction of this insect. To better understand the mechanism underlying 20E‐regulated reproduction, the nuclear hormone receptor E75 isoform‐A of Ap. lucorum (Al‐E75A) was cloned and its expression analysed. A 2241‐bp sequence of Al‐E75A cDNA encoded an open reading frame of a polypeptide with a predicted molecular mass of 69.04 kDa. Al‐E75A mRNA was detected in female adult stages of Ap. lucorum with peak expression in 7‐day‐old animals. Al‐E75A was also expressed in several tissues, particularly in the fat body and ovary. A 3.2 kb Al‐E75A mRNA was detected in all tissues by Northern blot. The fecundity and longevity were significantly decreased in female adults treated with Al‐E75A small interfering RNA. The rates of egg incubation rates were considerably lower in the RNA interference‐treated animals compared to the untreated controls. In order to investigate the molecular mechanism underlying the effects described above, vitellogenin (Al‐Vg) was selected for further investigation. The expression pattern of Al‐Vg was similar to that of Al‐E75A and was up‐regulated by 20E. After knockdown of Al‐E75A, the expression profile of Al‐Vg and the protein levels were down‐regulated. These findings suggest that Al‐E75A plays a crucial role in the regulation of Al‐Vg expression in Ap. lucorum.     

[68Ga]‐HP‐DO3A‐nitroimidazole: a promising agent for PET detection of tumor hypoxia

The goal of this study is to evaluate a new ⁶⁸Ga‐based imaging agent for detecting tumor hypoxia using positron emission tomography (PET). The new hypoxia targeting agent reported here, [⁶⁸Ga]‐HP‐DO3A‐nitroimidazole ([⁶⁸Ga]‐HP‐DO3A‐NI), was constructed by linking a nitroimidazole moiety with the macrocyclic ligand component of ProHance®, HP‐DO3A. The hypoxia targeting capability of this agent was evaluated in A549 lung cancer cells in vitro and in SCID mice bearing subcutaneous A549 tumor xenografts. The cellular uptake assays showed that significantly more [⁶⁸Ga]‐HP‐DO3A‐NI accumulates in hypoxic tumor cells at 30, 60 and 120 min than in the same cells exposed to 21% O₂. The agent also accumulated in hypoxic tumors in vivo to give a tumor/muscle ratio (T/M) of 5.0 ± 1.2 (n = 3) as measured by PET at 2 h post‐injection (p.i.). This was further confirmed by ex vivo biodistribution data. In addition, [⁶⁸Ga]‐HP‐DO3A‐NI displayed very favorable pharmacokinetic properties, as it was cleared largely through the kidneys with little to no accumulation in liver, heart or lung (%ID/g < 0.5%) at 2 h p.i. The specificity of the agent for hypoxic tissues was further validated in a comparative study with a control compound, [⁶⁸Ga]‐HP‐DO3A, which lacks the nitroimidazole moiety, and by PET imaging of tumor‐bearing mice breathing air versus 100% O₂. Given the commercial availability of cGMP ⁶⁸Ge/⁶⁸Ga generators and the ease of ⁶⁸Ga labeling, the new agent could potentially be widely applied for imaging tumor hypoxia prior to radiation therapy. Copyright © 2015 John Wiley & Sons, Ltd.     

Involvement of Pro‐Nociceptive 5‐HT2A Receptor in the Pathogenesis of Medication‐Overuse Headache

(Headache 2010;50:185‐197) Objectives.— To determine the involvement of 5‐HT_2A (5‐HT_2A) receptor in the process of trigeminal plasticity induced by chronic analgesic exposure and in the process of inflammatory‐induced thermal hyperalgesia. Background.— Derangement in 5‐HT_2A serotonin receptor has been reported to implicate in pathogenesis of medication‐overuse headache. No clear explanation concerning the precise roles of these receptors in the process. Methods.— Wistar rats were daily administered with paracetamol (200 mg/kg) for 30 days. On the next day, ketanserin, a 5‐HT_2A antagonist, or saline was given prior to cortical spreading depression (CSD) induction. Electrocorticogram, cortical blood flow, Fos and 5‐HT_2A‐immunoreactivity in cortex and trigeminal pathway were studied. In the other experiment, complete Freund's adjuvant was injected into the rat hind paw to induce tissue inflammation. Three days later, ketanserin was given and noxious heat was applied to both inflamed and noninflamed paws. The response between 2 sides was compared by measuring paw withdrawal latency. Results.— Chronic paracetamol exposure led to an increase in CSD frequency and CSD‐evoked Fos expression in cerebral cortex indicating the increase in neuronal excitability. Prolonged medication exposure also facilitated trigeminal nociception as evident by an increase in CSD‐evoked Fos expression in trigeminal nucleus caudalis. The expression of 5‐HT_2A receptor in cerebral cortex and trigeminal ganglia was enhanced by chronic paracetamol administration. Pretreatment with ketanserin significantly attenuated these effects. The second experiment showed that ketanserin was able to lengthen the paw withdrawal latency in the inflamed side but did not alter nociceptive response in the noninflamed side. Conclusion.— These findings suggest that up‐regulation of pro‐nociceptive 5‐HT_2A receptor is an important step in the process of cortical hyper‐excitation and nociceptive facilitation induced by chronic analgesic exposure.     

Aging and hypertension decrease endothelial NO‐related dilating function and gamma‐glutamyl transferase activity but not S‐nitrosoglutathione‐induced aortic vasodilation

S‐nitrosoglutathione (GSNO), which is involved in the transport and the storage of NO, induces vasorelaxation. It requires gamma‐glutamyl transferase (GGT), an enzyme present on the endothelium, to transfer NO into the cell. We evaluated whether aging and hypertension, which induce NO‐related dilating dysfunction, are associated with decreased vascular GGT activity and modify the vasorelaxant effect of GSNO. Thoracic aortic rings isolated from male spontaneous hypertensive rats (SHR) and Wistar‐Kyoto rats (WKY) aged 20–22 (adult) or 57–60 weeks (mature) were preconstricted with phenylephrine, then submitted to concentration‐vasorelaxant response curves (maximal response: E_max; pD₂) to GSNO and carbachol (the latter to measure NO‐related dilating function). GGT activity was measured using chromogenic substrate. Both aging and hypertension lowered E_max values for carbachol (E_max ?8% in adult SHR, ?42% in mature SHR vs. age‐matched WKY, p_age and p_hypertension < 0.05) demonstrating NO‐related dilating dysfunction. Aortic GGT activity also decreased with aging and hypertension (?22% in adult and ?75%, reaching 3 nmol/min/g of tissue, in mature SHR vs. 12 in age‐matched WKY and 23 in adult WKY, p_age and p_hypertension < 0.05). The pD₂ values of GSNO were similar in mature SHR and WKY but higher in adult SHR (p_interaction < 0.05). Aging in hypertensive rats decreased NO‐related vasorelaxant function and vascular GGT activity, but did not lower the vasorelaxant response to GSNO. This opens perspectives for GSNO‐based therapeutics restoring nitric oxide bioavailability and vascular protection in a context of endothelial dysfunction.     

Establishment of a specific cell death induction system in Bombyx mori by a transgene with the conserved apoptotic regulator,mouse Bcl‐2‐associated X protein (mouse Bax)

The induction of apoptosis in vivo is a useful tool for investigating the functions and importance of particular tissues. B‐cell leukaemia/lymphoma 2‐associated X protein (Bax) functions as a pro‐apoptotic factor and induces apoptosis in several organisms. The Bax‐mediated apoptotic system is widely conserved from Caenorhabditis elegans to humans. In order to establish a tissue‐specific cell death system in the domestic silkworm, Bombyx mori, we constructed a transgenic silkworm that overexpressed mouse Bax (mBax) in particular tissues by the Gal4‐upstream activation sequence system. We found that the expression of mBax induced specific cell death in the silk gland, fat body and sensory cells. Fragmentation of genomic DNA was observed in the fat body, which expressed mBax, thereby supporting apoptotic cell death in this tissue. Using this system, we also demonstrated that specific cell death in sensory cells attenuated the response to the sex pheromone bombykol. These results show that we successfully established a tissue‐specific cell death system in vivo that enabled specific deficiencies in particular tissues. The inducible cell death system may provide useful means for industrial applications of the silkworm and possible utilization for other species.     

Inhibitors of Microsomal Prostaglandin E2 Synthase‐1 Enzyme as Emerging Anti‐Inflammatory Candidates

Cyclooxygenases (COX‐1 and COX‐2) catalyze the conversion of arachidonic acid (AA) into PGH₂ that is further metabolized by terminal prostaglandin (PG) synthases into biologically active PGs, for example, prostaglandin E₂ (PGE₂), prostacyclin I₂ (PGI₂), thromboxane A₂ (TXA₂), prostaglandin D₂ (PGD₂), and prostaglandin F₂ alpha (PGF_2α). Among them, PGE₂ is a widely distributed PG in the human body, and an important mediator of inflammatory processes. The successful modulation of this PG provides a beneficial strategy for the potential anti‐inflammatory therapy. For instance, nonsteroidal anti‐inflammatory agents (NSAIDs), both classical nonselective (cNSAIDs) and the selective COX‐2 inhibitors (coxibs) attenuate the generation of PGH₂ from AA that in turn reduces the synthesis of PGE₂ and modifies the inflammatory conditions. However, the long‐term use of these agents causes severe side effects due to the nonselective inhibition of other PGs, such as PGI₂ and TXA₂, etc. Microsomal prostaglandin E₂ synthase‐1 (mPGES‐1), a downstream PG synthase, specifically catalyzes the biosynthesis of COX‐2‐derived PGE₂ from PGH₂, and describes itself as a valuable therapeutic target for the treatment of acute and chronic inflammatory disease conditions. Therefore, the small molecule inhibitors of mPGES‐1 would serve as a beneficial anti‐inflammatory therapy, with reduced side effects that are usually associated with the nonselective inhibition of PG biosynthesis.