Toxicity of two drugs towards the marine filter feeder Mytilus spp, using biochemical and shell integrity parameters

The increasing presence of anthropogenic contaminants in the environment may constitute a challenge to non-target biota, considering that most contaminants can exert deleterious effects. Salicylic acid (SA) is a non-steroid anti-inflammatory drug (NSAID) which exerts its activity by inhibiting the enzyme cyclooxygenase (COX). Another class of drugs is that of the diuretics, in which acetazolamide (ACZ) is included. This pharmaceutical acts by inhibiting carbonic anhydrase (CA), a key enzyme in acid-base homeostasis, regulation of pH, being also responsible for the bio-availability of Ca²⁺ for shell biomineralization processes. In this work, we evaluated the chronic (28-day) ecotoxicological effects resulting from the exposures to SA and ACZ (alone, and in combination) on individuals of the marine mussel species Mytillus spp., using enzymatic (catalase (CAT), glutathione S-transferases (GSTs), COX and CA), non-enzymatic (lipid peroxidation, TBARS levels) and morphological and physiological (shell hardness, shell index and feeding behaviour) biomarkers. Exposure to ACZ and SA did not cause significant alterations in CAT and GSTs activities, and in TBARS levels. In terms of CA, this enzyme was inhibited by the highest concentration of ACZ in gills of exposed animals, but no effects occurred in the mantle tissue. The activity of COX was not altered after exposure to the single chemicals. However, animals exposed to the mixture of ACZ and SA evidenced a significant inhibition of COX activity. Morphological and physiological processes (namely, feeding, shell index, and shell hardness) were not affected by the here tested pharmaceutical drugs. Considering the general absence of adverse effects, further studies are needed to fully evaluate the effects of these pharmaceutical drugs on alternative biochemical and physiological pathways.

Facilitation of colonic T cell immune responses is associated with an exacerbation of dextran sodium sulfate-induced colitis in mice lacking microsomal prostaglandin E synthase-1

Background

Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme that acts downstream of cyclooxygenase and plays a major role in inflammation by converting prostaglandin (PG) H₂ to PGE₂. The present study investigated the effect of genetic deletion of mPGES-1 on the development of immunologic responses to experimental colitis induced by dextran sodium sulfate (DSS), a well-established model of inflammatory bowel disease (IBD).

Methods

Colitis was induced in mice lacking mPGES-1 (mPGES-1^−/− mice) and wild-type (WT) mice by administering DSS for 7 days. Colitis was assessed by body weight loss, diarrhea, fecal bleeding, and histological features. The colonic expression of mPGES-1 was determined by real-time PCR, western blotting, and immunohistochemistry. The impact of mPGES-1 deficiency on T cell immunity was determined by flow cytometry and T cell depletion in vivo.

Results

After administration of DSS, mPGES-1^−/− mice exhibited more severe weight loss, diarrhea, and fecal bleeding than WT mice. Histological analysis further showed significant exacerbation of colonic inflammation in mPGES-1^−/− mice. In WT mice, the colonic expression of mPGES-1 was highly induced on both mRNA and protein levels and colonic PGE₂ increased significantly after DSS administration. Additionally, mPGES-1 protein was localized in the colonic mucosal epithelium and infiltrated inflammatory cells in underlying connective tissues and the lamina propria. The abnormalities consistent with colitis in mPGES-1^−/− mice were associated with higher expression of colonic T-helper (Th)17 and Th1 cytokines, including interleukin 17A and interferon-γ. Furthermore, lack of mPGES-1 increased the numbers of Th17 and Th1 cells in the lamina propria mononuclear cells within the colon, even though the number of suppressive regulatory T cells also increased. CD4⁺ T cell depletion effectively reduced symptoms of colitis as well as colonic expression of Th17 and Th1 cytokines in mPGES-1^−/− mice, suggesting the requirement of CD4⁺ T cells in the exacerbation of DSS-induced colitis under mPGES-1 deficiency.

Conclusions

These results demonstrate that mPGES-1 is the main enzyme responsible for colonic PGE₂ production and deficiency of mPGES-1 facilitates the development of colitis by affecting the development of colonic T cell–mediated immunity. mPGES-1 might therefore impact both the intestinal inflammation and T cell–mediated immunity associated with IBD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41232-021-00188-1.

Profiling oxylipins released from human platelets activated through the GPVI collagen receptor

In addition to haemostasis, platelets are involved in pathological processes, often driven by material released upon activation. Interaction between collagen and glycoprotein VI (GPVI) is a primary platelet stimulus that liberates arachidonic acid and linoleic acid from membrane phospholipids. These are oxidised by cyclooxygenase-1 (COX-1) and 12-lipoxygenase (12-LOX) to eicosanoids and other oxylipins with various biological properties. Using liquid chromatography-tandem mass spectrometry we found that GPVI-stimulated platelets released significant levels of ten oxylipins; the well documented TxA2 and 12-HETE, PGD₂ and PGE_2, as well as 8-, 9-, 11-, and 15-HETE, 9- and 13-HODE.¹ Levels of oxylipins released from washed platelets mirrored those from platelets stimulated in the presence of plasma, indicating generation from intracellular, rather than exogenous AA/LA. Inhibition of COX-1 with aspirin, as expected, completely abolished production of TxA₂ and PGD/E₂, but also significantly inhibited the release of 11-HETE (89 ± 3%) and 9-HODE (74 ± 6%), and reduced 15-HETE and 13-HODE by ∼33 %. Inhibition of 12-LOX by either esculetin or ML355 inhibited the release of all oxylipins apart from 15-HETE. These findings suggest routes to modify the production of bioactive molecules released by activated platelets.

Antiarthritic activity of OA-DHZ; a gastroprotective NF-κB/MAPK/COX inhibitor

Arthritis, a primary autoimmune disorder having a global incidence of 2.03% person/year, is presently being treated by many commercially available drugs that treat symptomatically or improve the disease's clinical state; however, all the therapies pose varying amount of side effects. Therefore, it has become a fundamental need to search for therapeutics that offer better efficacy and safety profile, and the natural or nature-derived products are known for their outstanding performance in this arena. OA-DHZ, known to possess anti-inflammatory and analgesic properties, when explored for its efficacy against arthritis in adjuvant-induced arthritis (AIA) model, was found to inhibit paw edema by 34% and TNF-α, IL-6, and IL-1β by 67%, 39%, and 45% respectively when compared to diseased control. It was also able to reduce the inflamed spleen size by 45% and successfully normalized biochemical and hematological changes that followed arthritis. In vitro studies revealed that the underlying mechanism for inhibiting arthritis progression might be due to NF-κB /MAPK pathway modulation. OA-DHZ also showed selective inhibition of COX-2 in vitro while showing gastroprotective effects when evaluated for ulcerogenic and antiulcer potential in vivo. In contrast to the results obtained from in vivo experimentation, there is a disparity in the pharmacokinetic profile of OA-DHZ, where it showed low oral exposure and high clearance rate. OA-DHZ being antiarthritic acting via NF-κB /MAPK/ COX inhibition while showing gastroprotective effects, can be a suitable candidate to be in the drug pipeline and further exploration.

RNAseq analysis of treatment-dependent signaling changes during inflammation in a mouse cutaneous wound healing model

BACKGROUND

Despite proven therapeutic effects in inflammatory conditions, the specific mechanisms of phytochemical therapies are not well understood. The transcriptome effects of Traumeel (Tr14), a multicomponent natural product, and diclofenac, a non-selective cyclooxygenase (COX) inhibitor, were compared in a mouse cutaneous wound healing model to identify both known and novel pathways for the anti-inflammatory effect of plant-derived natural products.

METHODS

Skin samples from abraded mice were analyzed by single-molecule, amplification-free RNAseq transcript profiling at 7 points between 12 and 192 h after injury. Immediately after injury, the wounds were treated with either diclofenac, Tr14, or placebo control (n = 7 per group/time). RNAseq levels were compared between treatment and control at each time point using a systems biology approach.

RESULTS

At early time points (12-36 h), both control and Tr14-treated wounds showed marked increase in the inducible COX2 enzyme mRNA, while diclofenac-treated wounds did not. Tr14, in contrast, modulated lipoxygenase transcripts, especially ALOX12/15, and phospholipases involved in arachidonate metabolism. Notably, Tr14 modulated a group of cell-type specific markers, including the T cell receptor, that could be explained by an overarching effect on the type of cells that were recruited into the wound tissue.

CONCLUSIONS

Tr14 and diclofenac had very different effects on the COX/LOX synthetic pathway after cutaneous wounding. Tr14 allowed normal autoinduction of COX2 mRNA, but suppressed mRNA levels for key enzymes in the leukotriene synthetic pathway. Tr14 appeared to have a broad 'phytocellular' effect on the wound transcriptome by altering the balance of cell types present in the wound.

Effects of dietary aspirin on high-LET radiation-induced prostaglandin E2 levels and gastrointestinal tumorigenesis in Apc1638N/+ mice

Inevitable exposure to high-LET ionizing radiation (IR) present in galactic cosmic radiation (GCR) could enhance gastrointestinal (GI) cancer incidence among astronauts undertaking deep space exploration and GI-cancer mortality has been predicted to far exceed NASA's limit of < 3% REID (Radiation exposure-induced death) from cancer. Therefore, the development of countermeasure agents against high-LET radiation-induced GI cancer is needed to safeguard astronauts during and after an outer space mission. The cyclooxygenase-2/prostaglandin E2 (COX2/PGE2) mediated activation of pro-inflammatory and oncogenic signaling has been reported to play an important role in persistent inflammation and GI-tumorigenesis after high-LET radiation exposure. Therefore, aspirin, a well-known inhibitor of the COX/PGE2 pathway, was evaluated as a potential countermeasure against ²⁸Si-induced PGE2 and tumorigenesis in Apc^1638N/+, a murine model of human GI-cancer. Animals were fed either standard or aspirin supplemented diet (75, 150, or 300 mg/day of human equivalent dose) starting at the age of 4 weeks and continued till the end of the study, while mice were exposed to ²⁸Si-ions (300 MeV/n; 69 keV/μm) at the age of 8 weeks. Serum PGE2 level, GI tumor size (>2mm²), number, and cluster (>5 adjoining tumors) were analyzed at 150 days post-exposure. Aspirin led to a significant reduction in PGE2 in a dose-dependent manner but did not reduce ²⁸Si-induced GI tumorigenesis even at the highest (300 mg/day) dose. In summary, this study suggests that aspirin could reduce high-LET IR-induced pro-inflammatory PGE2 levels, however, lacks the ability to reduce high-LET IR-induced GI tumorigenesis in Apc^1638N/+ mice.

Local inflammatory mediators alterations induced by Daboia siamensis venom

The ability of Russell's viper (Daboia siamensis) venom (total RVV) and phospholipase A₂ (purified PLA₂) to induce the local pathological effects were investigated by the local inflammatory events and the release of inflammatory mediators. Both 0.5 μg of total RVV/mouse and 0.15 μg of purified PLA₂/mouse were administered via intra-peritoneal injection. After 30 min, 1 h, 2 h, and 4 h incubation time, the peritoneal cavity was flooded with normal saline and the total leukocytes were collected. The eicosanoids (lipid mediators) and the leukocyte expression of cyclooxygenase (COX-1 and COX-2) were investigated by ELISA assay and western blotting, respectively. The amounts of total leukocytes were increased from 30 min to 2 h, then decreased at 4 h, by both total RVV and purified PLA₂. Both treatments also induced the expression of COX-2 which was increased at 2 h and then decreased at 4 h, whereas only purified PLA₂ induced the expression level of a COX-1 protein which was increased at 30 min, then constantly expressed until 4 h. In addition, total RVV and purified PLA₂ caused the release of the eicosanoids; PGE₂, TXB₂, and LTB₄, which reached the peak after 2 h. The findings of this study indicate that purified PLA₂ has the potential effects to induce the local inflammation relating the amounts of leukocytes cells, lipid mediators and COX-2 more than the total RVV.

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Purified phospholipase A₂ or the venom could induce eicosanoids and cyclooxygenase-2 expression relating to leukocytes cells.

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Thromboxane B₂ could be the important mediator induced by Russell's viper venom and purified phospholipase A₂.

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Russell's viper venom and purified phospholipase A₂ involved the cyclooxygenase-2 expression, but not cyclooxygenase-1.

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The purified phospholipase A₂ showed more predominant inflammatory response at site than total Russell's viper venom.

Different forms of vitamin E and metabolite 13'-carboxychromanols inhibit cyclooxygenase-1 and its catalyzed thromboxane in platelets, and tocotrienols and 13'-carboxychromanols are competitive inhibitors of 5-lipoxygenase

Cyclooxygenase (COX-1 and COX-2)- and 5-lipoxygenase (5-LOX)-catalyzed biosynthesis of eicosanoids play important roles in inflammation and chronic diseases. The vitamin E family has four tocopherols and tocotrienols. We have shown that the metabolites of δ-tocopherol (δT) and δ-tocotrienol (δTE), i.e., δT-13'-carboxychromanol (COOH) and δTE-13'-COOH, respectively, inhibit COX-1/-2 and 5-LOX activity, but the nature of how they inhibit 5-LOX is not clear. Further, the impact of tocopherols and tocotrienols on COX-1/-2 or 5-LOX activity has not been fully delineated. In this study, we found that tocopherols and tocotrienols inhibited human recombinant COX-1 with IC50s of 1-12 µM, and suppressed COX-1-mediated formation of thromboxane in collagen-stimulated rat's platelets with IC50s of 8-50 µM. None of the vitamin E forms directly inhibited COX-2 activity. 13'-COOHs inhibited COX-1 and COX-2 enzyme activity with IC50s of 3-4 and 4-10 µM, respectively, blocked thromboxane formation in collagen- and ionophore-stimulated rats' platelets with IC50s of 1.5-2.5 µM, and also inhibited COX-2-mediated prostaglandins in stimulated cells. Using enzyme kinetics, we observed that δT-13'-COOH, δTE-13'-COOH and δTE competitively inhibited 5-LOX activity with Ki of 1.6, 0.8 and 2.2 µM, respectively. These compounds decreased leukotriene B₄ from stimulated neutrophil-like cells without affecting translocation of 5-LOX from cytosol to the nucleus. Our study reveals inhibitory effects of vitamin E forms and 13'-COOHs on COX-1 activity and thromboxane formation in platelets, and elucidates mechanisms underlying their inhibition of 5-LOX. These observations are useful for understanding the role of these compounds in disease prevention and therapy.

Evaluation of Serum Cyclooxygenase, Hepcidin Levels in Acute Renal Injury (AKI) Patients Following Cardiac Catheterization

Background

Acute kidney damage is a severe condition common in patients who have undergone heart surgery (catheterization) and secondary injury is also referred to as being synonymous with surgery. The goal of this research is to determine the rate of cyclooxygenase and hepcidin levels in patients with acute renal injury (AKI) following cardiac catheterization.

Methods

The study is performed on (81) patients (64 males and 17 females) aged 40-75 years. Data from most patients are reported in the form of age, gender, and smoking background questionnaire.

Results

The results indicate a significant increase in serum levels of cyclooxygenase and hepcidin levels in patients with severe renal insufficiency after cardiac catheterization by (79%) males versus (21%) females.

Conclusion

In this study, improved risk prediction could enhance patient monitoring and treatment after surgery, direct patient treatment and decision making, and enhance participation in AKI interventional trials.

Determination of phenolic profiles of Herniaria polygama and Herniaria incana fractions and their in vitro antioxidant and anti-inflammatory effects

The study is based on phytochemical profiling and in vitro evaluation of biological effects of phenolic acid derivatives-rich Herniaria fractions, isolated from two rupturewort (Herniaria L.) species, i.e. Herniaria incana Lam. (syn. H. besseri Fisch. ex Hornem) and H. polygama J. Gay (syn. H. odorata). For the first time, the composition of phenolic compounds of these species was extensively evaluated by both LC-HR-QTOF-ESI-MS and Nuclear Magnetic Resonance spectroscopy (NMR). LC-MS analyses of H. polygama revealed 72 tentatively identified compounds, while H. incana - 63. Only 8% of the metabolites reported in this work have been previously described for Herniaria spp. Most of the identified specialized metabolites were cinnamic and benzoic acid derivatives. Phenolic fraction of H. incana herb contained flavonoids as well. A multi-step chromatographic separation of phenolic fractions from H. polygama yielded three known cinnamic and one benzoic acid derivates, and from H. incana - 4 known flavonoids and one previously undescribed, i.e. rhamnocitrin-3-O-[3-hydroxy-3-methylglutaryl-(1 → 6'')]-[α-rhamnopyranosyl-(1 → 2'')]-β-glucopyranoside. Antioxidant properties of the examined fractions (1-50 μg/ml) were assessed in human blood plasma under the conditions of peroxynitrite-induced oxidative stress. Measurements of well-known biomarkers such as 3-nitrotyrosine, protein thiol groups, thiobarbituric acid-reactive substances and the ferric reducing ability of blood plasma revealed the protective effect of Herniaria fractions against oxidative damage to blood plasma components. Furthermore, the examined fractions effectively ameliorated the inflammatory response of the concanavalin A-stimulated human peripheral blood mononuclear cells (PBMCs). Additionally, cellular safety of the fractions was confirmed in PBMCs.

Morphological changes of macrophages and their potential contribution to tendon healing

Poor healing ability and adhesion formation greatly hinder the recovery of injured tendon function. Previously, our local sustained gene delivery system by using cyclooxygenases (COX-1 and COX-2)-engineered miRNA plasmid/nanoparticles loaded hydrogel significantly inhibited adhesion formation and promoted tendon healing. The present study aims to study morphological changes of the macrophages in the healing tendons after above treatment with the hydrogel. Firstly, we assessed the therapeutic effect of localized delivery of the hydrogel on cyclooxygenases in the injured rat Achilles tendon model. We found ultimate strengths of the healing tendons were significantly increased at week 2 and 3. We then studied the distribution of macrophages before and after tendon injury, and found macrophages were rapidly recruited into injured sites of tendons. After being isolated and cultured, macrophages were transfected with 6-Carboxyfluorescein (FAM) labeled siRNA/nanoparticles and presented a high transfection efficiency (>70%). We further compared the change of iNOS/CD206 in macrophages between negative control siRNA/nanoparticle group and COX siRNA/nanoparticle group. The major finding is that the morphology of the macrophages changed from type I macrophages to type II macrophages after transfection of COX siRNA/nanoparticles in vitro. Subsequently, rat Achilles tendon cells were cultured with supernatant collected from macrophages transfected with negative control siRNA/nanoparticles and COX siRNA/nanoparticles, and the proliferation of tendon cells was significantly increased in COX siRNA/nanoparticle supernatant group. Because type II macrophages are responsible for tissue repair, the changes in macrophage polarization from M1 to M2 may be one of the important events in promoting the tendon healing.

Galantamine prevents and reverses neuroimmune induction and loss of adult hippocampal neurogenesis following adolescent alcohol exposure

BACKGROUND

Binge ethanol exposure during adolescence reduces hippocampal neurogenesis, a reduction which persists throughout adulthood despite abstinence. This loss of neurogenesis, indicated by reduced doublecortin+ immunoreactivity (DCX+IR), is paralleled by an increase in hippocampal proinflammatory signaling cascades. As galantamine, a cholinesterase inhibitor, has anti-inflammatory actions, we tested the hypothesis that galantamine would prevent (study 1) or restore (study 2) AIE induction of proinflammatory signals within the hippocampus as well as AIE-induced loss of hippocampal neurogenesis.

METHODS

Galantamine (4 mg/kg) or vehicle (saline) was administered to Wistar rats during adolescent intermittent ethanol (AIE; 5.0 g/kg ethanol, 2 days on/2 days off, postnatal day [P] 25-54) (study 1, prevention) or after AIE during abstinent maturation to adulthood (study 2, restoration).

RESULTS

Results indicate AIE reduced DCX+IR and induced cleaved caspase3 (Casp3) in DCX-expressing immature neurons. Excitingly, AIE induction of activated Casp3 in DCX-expressing neurons is both prevented and reversed by galantamine treatment, which also resulted in prevention and restoration of neurogenesis (DCX+IR). Similarly, galantamine prevented and/or reversed AIE induction of proinflammatory markers, including the chemokine (C-C motif) ligand 2 (CCL2), cyclooxygenase-2 (COX-2), and high mobility group box 1 (HMGB1) protein, suggesting that AIE induction of proinflammatory signaling mediates both cell death cascades and hippocampal neurogenesis. Interestingly, galantamine treatment increased Ki67+IR generally as well as increased pan-Trk expression specifically in AIE-treated rats but failed to reverse AIE induction of NADPH-oxidase (gp91phox).

CONCLUSIONS

Collectively, our studies suggest that (1) loss of neurogenesis after AIE is mediated by persistent induction of proinflammatory cascades which drive activation of cell death machinery in immature neurons, and (2) galantamine can prevent and restore AIE disruptions in the hippocampal environmental milieu to then prevent and restore AIE-mediated loss of neurogenesis.

Discovery of pyrazole N-aryl sulfonate: A novel and highly potent cyclooxygenase-2 (COX-2) selective inhibitors

Based on a new pyrazole sulfonate synthetic method, a novel class of molecules with a basic structure of pyrazole N-aryl sulfonate have been designed and synthesized. The interest in conducting intensive research stems from quite evident anti-inflammatory effects exhibited by the compounds in preliminary animal experiments. A series of compounds were synthesized by different substitutions of the R¹, R², and R³ groups. Within the series, 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and phenyl 5-methyl-3-(4-(trifluoromethyl) phenyl)-1H-pyrazole-1-sulfonate exhibited excellent anti-inflammatory activity (% inhibition of auricular edemas = 27.0 and 35.9, respectively); the in vivo analgesic activity of phenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate was confirmed to be effective (inhibition ratio of writhing = 50.7% and 48.5% separately), and compounds phenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate , 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate were identified as selective COX-2 inhibitors (SI = 455, 10,497 and >189 severally). In Acute Oral Toxicity assays conducted in vivo, the lethal dose 50 (LD₅₀) of 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate to mice was >2000 mg/kg BW.

Limitations of drug concentrations used in cell culture studies for understanding clinical responses of NSAIDs

In this review, the in vitro cellular effects of six nonsteroidal anti-inflammatory drugs (NSAIDs), salicylate, ibuprofen, naproxen, indomethacin, celecoxib and diclofenac, are examined. Inhibition of prostanoid synthesis in vitro generally occurs within the therapeutic range of plasma concentrations that are observed in vivo, consistent with the major action of NSAIDs being inhibition of prostanoid production. An additional probable cellular action of NSAIDs has been discovered recently, viz. decreased oxidation of the endocannabinoids, 2-arachidonoyl glycerol and arachidonyl ethanolamide. Many effects of NSAIDs, other than decreased oxidation of arachidonic acid and endocannabinoids, have been put forward but almost all of these additional processes are observed at supratherapeutic concentrations when the concentration of albumin, the major protein that binds NSAIDs, is taken into account. However, one exception is salicylate, a very potent inhibitor of the neutrophilic enzyme, myeloperoxidase, the inhibition of which leads to reduced production of the inflammatory mediator, hypochlorous acid, and inhibition of the inflammation associated with rheumatoid arthritis.

Cyclooxygenase-dependent mechanisms mediate in part the anti-dilatory effects of perivascular adipose tissue in uterine arteries from pregnant rats

Uterine perivascular adipose tissue (PVAT) contributes to uterine blood flow regulation in pregnancy, at least in part, due to its effects on uterine artery reactivity. We tested the hypothesis that uterine PVAT modulates the balance between the contribution of nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent pathways to acetylcholine (ACh)-induced relaxation in isolated uterine arteries. Concentration-response curves to ACh (1 nM - 30 µM) were performed on uterine arteries from pregnant and non-pregnant rats. Arteries were exposed to Krebs-Henseleit solution (control) or PVAT-conditioned media (PVATmedia) in the presence of the following inhibitors: L-NAME (NOS inhibitor), indomethacin (COX inhibitor), SC560 (COX-1 inhibitor), NS398 (COX-2 inhibitor), SQ 29,548 (thromboxane receptor (TP) inhibitor). In arteries incubated with PVATmedia, the presence of indomethacin increased ACh-induced relaxation, reversing the anti-dilatory effect of PVATmedia. NOS inhibition reduced ACh-induced relaxation in uterine arteries from pregnant rats, and exposure to PVATmedia did not change this effect. Selective inhibition of COX-1 but not COX-2 suppressed relaxation responses to ACh in control arteries. The presence of PVATmedia abolished the effect of COX-1 inhibition. Incubation of uterine arteries from pregnant rats with PVATmedia increased production of thromboxane B2 (TxB2, p = 0.01) but thromboxane receptor (TP) inhibition did not affect the anti-dilatory properties of PVATmedia. In conclusion, inhibition of COX signaling suppressed the anti-dilatory effects of PVATmedia, while PVATmedia had no effect on the contribution of the NOS/NO pathway to ACh-induced relaxation in uterine arteries from pregnant rats, indicating that the anti-dilatory effects of uterine PVAT are mediated in part by COX-dependent mechanisms.

Montelukast potentiates the antiinflammatory effect of NSAIDs in the rat paw formalin model and simultaneously minimizes the risk of gastric damage

OBJECTIVE AND DESIGN

Montelukast, a cysteinyl leukotriene receptor antagonist, exhibits antiinflammatory action. We tested whether exposure to montelukast plus nonsteroidal antiinflammatory drugs (NSAIDs) elicits better control of paw inflammation in the rat formalin test and improves associated gastric damage.

MATERIALS

A total of 46 adult male rats were used in the study.

TREATMENTS

We evaluated separate and combined effects of montelukast (20 mg/kg), celecoxib (COX2 inhibitor, 10 mg/kg), and diclofenac (nonselective COX1/COX2 inhibitor, 10 mg/kg) on paw and gastric damage in the rat formalin test.

RESULTS

Individual pretreatments of rats with montelukast, diclofenac, or celecoxib partly reduced formalin-induced increases in (i) paw edema, fibrosis, and inflammatory cells, (iii) serum interleukin-6 (IL-6) and leukotrienes (LTB4 and LTD4), and (iv) paw expressions of inducible nitric oxide synthase (iNOS) and COX2. These effects were accentuated in rats treated with montelukast plus diclofenac or montelukast plus celecoxib. Alternatively, montelukast or celecoxib, but not diclofenac, alleviated formalin-evoked gastric damage and increments in tumor necrosis factor-α and decrements in prostaglandin-E₂. These advantageous gastric influences were potentiated in rats treated with montelukast plus celecoxib.

CONCLUSIONS

While montelukast equally enhances antiinflammatory action of diclofenac or celecoxib via downregulating iNOS/COX2/LTs/IL-6 signaling, its gastroprotective action is preferentially potentiated by celecoxib.

Bioactive stigmastadienone from Isodon rugosus as potential anticholinesterase, α-glucosidase and COX/LOX inhibitor: In-vitro and molecular docking studies

Natural product is a well-known source of bioactive compounds. Herein, a steroidal compound stigmasta-7,22-diene-3-one (stigmastadienone) has been isolated from Isodon rugosus. The potency of isolated compound has been tested for several in-vitro targets. The acetyl and butyrylcholinesterase assays were performed using Ellman's procedure. For the in-vitro antidiabetic potential, α-glucosidase inhibitory assay was performed. Similarly, the cyclo and lipoxygenase pathways were studied to find its potential role in the management of inflammation and analgesia. The 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydrogen peroxide (H₂O₂) assays were performed for the antioxidant potentials. Docking studies were performed against acetylcholinesterase, cyclooxygenase and lipoxygenase targets. In anticholinesterase assays, stigmastadienone exhibited half-maximal inhibitory concentration (IC₅₀) values of 13.52 and 11.53 μg/ml for acetyl and butyrylcholinesterase respectively. The observed IC₅₀ values for that of galantamine were 6.07 and 4.42 μg/ml for acety and butyrylcholinesterase respectively. In inhibiting α-glucosidase enzyme, the compound showed mediocre IC₅₀ of 109.40 μg/ml compared to the standard acarbose (7.60 μg/ml). The stigmastadienone proved to be an excellent inhibitor of cyclooxygenase 2 (COX-2) and 5-lipoxygenase (5-LOX) attaining IC₅₀ values of 4.72 and 3.36 μg/ml respectively. The standard drugs IC₅₀ values for COX-2 (celecoxib) and 5-LOX (montelukast) were 3.81 and 2.74 μg/ml respectively. The enzymatic activities of stigmastadienone were also supplemented with antioxidant results, specifically it was more dominant against DPPH and ABTS free radicals. Docking studies showed that only the carbonyl oxygen is able to form hydrogen bond interaction with the residues. In conclusions, the stigmastadienone has been isolated from Isodon rugosus for the first time. Moreover, the compound has been evaluated for several biochemical pathways which suggest its pharmacological role on the explored targets.

Tepoxalin increases chemotherapy efficacy in drug-resistant breast cancer cells overexpressing the multidrug transporter gene ABCB1

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The COX-2 encoding gene PTGS2 is up-regulated upon ABCB1 overexpression in mammary epithelial cells.

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The 5-LOX, COX-1/2 inhibitor tepoxalin plus chemotherapy improves treatment efficacy in ABCB1-expressing cells.

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Tepoxalin reduces chemotherapy-induced selection for drug-resistant ABCB1-expressing cells.

Effective cancer chemotherapy treatment requires both therapy delivery and retention by malignant cells. Cancer cell overexpression of the multidrug transmembrane transporter gene ABCB1 (MDR1, multi-drug resistance protein 1) thwarts therapy retention, leading to a drug-resistant phenotype. We explored the phenotypic impact of ABCB1 overexpression in normal human mammary epithelial cells (HMECs) via acute adenoviral delivery and in breast cancer cell lines with stable integration of inducible ABCB1 expression. One hundred sixty-two genes were differentially expressed between ABCB1-expressing and GFP-expressing HMECs, including the gene encoding the cyclooxygenase-2 protein, PTGS2. Several breast cancer cell lines with inducible ABCB1 expression demonstrated sensitivity to the 5-lipoxygenase, cyclooxygenase-1/2 inhibitor tepoxalin in two-dimensional drug response assays, and combination treatment of tepoxalin either with chemotherapies or with histone deacetylase (HDAC) inhibitors improved therapeutic efficacy in these lines. Moreover, selection for the ABCB1-expressing cell population was reduced in three-dimensional co-cultures of ABCB1-expressing and GFP-expressing cells when chemotherapy was given in combination with tepoxalin. Further study is warranted to ascertain the clinical potential of tepoxalin, an FDA-approved therapeutic for use in domesticated mammals, to restore chemosensitivity and improve drug response in patients with ABCB1-overexpressing drug-resistant breast cancers.

Non-steroidal anti-inflammatory drugs and bone healing in animal models-a systematic review and meta-analysis

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAID) have excellent anti-inflammatory and analgesic properties and are extensively used to treat post-traumatic or surgical musculoskeletal pain. Although an extensive literature exists on the administration of NSAID on animal bone healing, no systematic review and meta-analysis of animal studies that investigate the effect of NSAID administration on bone fracture healing. Objective of this study is to conduct a systematic review and meta-analysis to estimate the effect of NSAIDs administration on bone healing biomechanical and histomorphometric measurements in different animal models after bone fracture surgery.

METHODS

We performed a systematic review and meta-analysis of animal studies to estimate the effect of NSAID administration after bone fracture on healing outcomes. We searched eight databases without limiting the search to starting date up to 1 February 2021 for articles on fractured bone healing in animal models in which NSAID were administered.

RESULTS

Out of 6732 articles screened, 47 were included and 3 common bone healing outcomes were analysed: biomechanical properties (maximum force to break, stiffness, and work-to-failure), micro-computed tomography (μ-CT), and histomorphometric measurements. The studies were generally of low-quality scores because crucial information, especially concerning randomization, blinding, and allocation concealment, was poorly reported. Our results show that the negative effects of NSAID after bone fracture on certain biomechanical properties of the healing bones was not statistically significant in mice compared with other animals, in females compared with males, and in younger compared with older animals.

CONCLUSION

The findings demonstrated that NSAIDs administration decreased the biomechanical properties of healing bones after fracture surgery in comparison to the control group. Moreover, different effect on certain outcomes was detected among different sites, sex of the animals, and the time of assessment.

TRIAL REGISTRATION

Protocol published and registered in SYstematic Review Center for Laboratory animal Experimentation (SYRCLE) in 2017, https://www.radboudumc.nl/getmedia/757ec408-7a9e-4635-8233-ae951effea54/Non-Steroidal-Anti-inflammatory-Drugs-and-bone-healing-in-animal-Models-Systematic-Review-and-Meta-Analysis.aspx.

Prostaglandin D2 inhibits mediator release and antigen induced bronchoconstriction in the Guinea pig trachea by activation of DP1 receptors

The mechanism by which cyclooxygenase (COX) inhibition increases antigen-induced responses in airways remains unknown. Male albino guinea pigs were sensitized to ovalbumin (OVA). Intact rings of the trachea were isolated and mounted in organ baths for either force measurements or lipid mediator release analysis by UPLC-MS/MS or EIA following relevant pharmacological interventions. First, challenge with OVA increased the release of all primary prostanoids (prostaglandin (PG) D₂/E₂/F_2α/I₂ and thromboxanes). This release was eliminated by unselective COX inhibition (indomethacin) whereas selective inhibition of COX-2 (lumiracoxib) did not inhibit release of PGD₂ or thromboxanes. Additionally, the increased levels of leukotriene B₄ and E₄ after OVA were further amplified by unselective COX inhibition. Second, unselective inhibition of COX and selective inhibition of the prostaglandin D synthase (2-Phenyl-Pyrimidine-5-Carboxylic Acid (2,3-dihydro-indol-1-yl)-amide) amplified the antigen-induced bronchoconstriction which was reversed by exogenous PGD₂. Third, a DP₁ receptor agonist (BW 245c) concentration-dependently reduced the antigen-induced constriction as well as reducing released histamine and cysteinyl-leukotrienes, a response inhibited by the DP₁ receptor antagonist (MK-524). In contrast, a DP₂ receptor agonist (15(R)-15-methyl PGD₂) failed to modulate the OVA-induced constriction. In the guinea pig trachea, endogenous PGD₂ is generated via COX-1 and mediates an inhibitory effect of the antigen-induced bronchoconstriction via DP₁ receptors inhibiting mast cell release of bronchoconstrictive mediators. Removal of this protective function by COX-inhibition results in increased release of mast cell mediators and enhanced bronchoconstriction.

Mechanism of reactivation of the peroxidase catalytic activity of human cyclooxygenases by reducing cosubstrate quercetin

Our earlier studies show that the peroxidase activity of cyclooxygenase 1 and 2 (COX-1 and COX-2) can be reactivated in vitro and in vivo by the presence of certain naturally-occurring flavonoids such as quercetin and myricetin, which serve as reducing cosubstrates. These compounds can activate COX at nanomolar concentrations. In the present study, quercetin is used as a representative model compound to investigate the chemical mechanism by which the peroxidase activity of human COX-1 and COX-2 is reactivated after each catalytic cycle. Molecular docking and quantum mechanics calculations are carried out to probe the interactions of quercetin with the peroxidase sites of COX-1/2 and the reactivation mechanism. It is found that some of the partially-ionized states of quercetin can bind tightly and closely inside the peroxidase active sites of the COX enzymes and directly interact with heme Fe ion. While quercetin contains several phenolic hydroxyl groups, it is found that only the C-3'-OH group can effectively donate an electron for the reduction of heme because it not only can bind closely and tightly inside the peroxidase sites of COX-1/2, but it can also facilely donate an electron to heme Fe ion. This investigation provides a mechanistic explanation for the chemical process by which quercetin reactivates COX-1/2 peroxidases. This knowledge would aid in the rational design of drugs that can selectively target the peroxidase sites of COX-1/2 either as activators or inhibitors.

Therapeutic perspective of thiosemicarbazones derivatives in inflammatory pathologies: A summary of in vitro/in vivo studies

Following induction of inflammation, the nuclear factor kappa B (NF-κB) in activated macrophages induces the transcription of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and cyclooxygenase (COX), an inflammatory enzyme implicated in the synthesis of prostaglandins (PGs). The latter are involved in the transition and the maintenance of chronic inflammation underling various chronic disorders that require treatment. Concerning this, many anti-inflammatory drugs are available to treat the inflammatory disorders, but their therapeutic use is associated with a variety of side effects. Therefore, the discovery of new safer and potential anti-inflammatory drugs is necessary. In this regard, thiosemicarbazones (TSC) compounds and their metals complexes attracted high interest due to their wide range of biological activities, interestingly, the anti-inflammatory activity. They are formed by the action of thiosemicarbazide on an aldehyde or ketone, and contain a sulfur atom in place of the oxygen atom. Their ability to form a stable complex with transition metal is known to enhances the biological activity and reduces the side effects of the parent compound. Thus, this review article describes the inflammatory response mediated by NF-κB-COX-PGs and summarizes the anti-inflammatory activity of different thiosemicarbazones derivatives synthesized in research area.

Divergent PGD2 and leukotriene C4 metabolite excretion following aspirin therapy: Ten patients with systemic mastocytosis

Aspirin-exacerbated respiratory disease and some cases of chronic idiopathic urticaria are disorders in which increased baseline urinary excretion of leukotriene(LT)E4 further increases following aspirin administration. Increased urinary excretion of the metabolites of prostaglandin D2, 11β-prostaglandin(PG)F2α and (2,3-dinor)-11β-PGF2α, have been documented in systemic mastocytosis (SM) and in mast cell activation syndrome (MCAS). Symptoms due to increased baseline and/or episodic release of PGD2 can be prevented with aspirin, an inhibitor of cyclooxygenase (COX)1 and COX2. Here by retrospective chart review we discovered 8 of 10 patients with SM in whom normalization of an elevated urinary (2,3-dinor)-11β-PGF2α occurred with aspirin therapy also had a parallel increased excretion of LTE4 by an average of nearly 13-fold. How widespread this phenomenon occurs in SM is unknown; however, this occurrence needs to be considered when interpreting changes in these urinary mast cell mediator metabolites during aspirin therapy.

The intermediary role of the central cyclooxygenase / lipoxygenase enzymes in intracerebroventricular injected nesfatin-1-evoked cardiovascular effects in rats

That nesfatin-1 is a neuromodulatory peptide for the cardiovascular system is well documented. Several central receptors have been shown to mediate the cardiovascular effects of nesfatin-1. Immunohistochemistry and Western blot studies showed that nesfatin-1 activated the expression of the central cyclooxygenase (COX) -1, -2 and lipoxygenase (LOX). In addition, microdialysis study showed that nesfatin-1 increased the release of total prostaglandins and leukotrienes from the hypothalamus. The present study investigated whether the central COX and LOX enzymes have a direct mediating role in the MAP and HR responses of nesfatin-1. Intracerebroventricularly administered nesfatin-1 produced dose-dependent pressor and phasic HR responses in normotensive conscious rats Sprague Dawley. Central pretreatment with a COX1/2 inhibitor, ibuprofen, completely blocked the nesfatin-1-induced responses. However, central pretreatment with a nonselective LOX inhibitor, nordihydroguaiaretic acid, partially attenuated the cardiovascular responses induced by nesfatin-1. The results suggest that centrally administered nesfatin-1 activates the central enzymes COX and LOX, which may be involved in the cardiovascular responses as a novel central mechanism for nesfatin-1.

Inhibition of cyclooxygenase by blocking the reducing cosubstrate at the peroxidase site: Discovery of galangin as a novel cyclooxygenase inhibitor

Earlier we have shown that certain flavonoids (e.g., quercetin) are high-affinity reducing cosubstrates for cyclooxygenase (COX) 1 and 2. These compounds can bind inside the peroxidase active sites of COXs and donate an electron from one of their B-ring hydroxyl groups to hematin. Based on these earlier findings, it is postulated that some of the natural flavonoids such as galangin that are structural analogs of quercetin but lack the proper B-ring hydroxyl groups might function as novel inhibitors of COXs by blocking the effect of the reducing cosubstrates. This idea is tested in the present study. Computational docking analysis together with quantum chemistry calculation shows that galangin can bind inside the peroxidase active sites of COX-1 and COX-2 in a similar manner as quercetin, but it has little ability to effectively donate its electrons, thereby blocking the effect of the reducing cosubstrates like quercetin. Further experimental studies confirm that galangin can inhibit, both in vitro and in vivo, quercetin-mediated activation of the peroxidase activity of the COX-1/2 enzymes. The results of the present study demonstrate that galangin is a novel naturally-occurring inhibitor of COX-1 and COX-2, acting by blocking the function of the reducing cosubstrates at the peroxidase sites.