Alterations in the free radical generation and nitric oxide release from rat peripheral polymorphonuclear leukocytes following thrombosis

L-Arginine and tetrahydrobiopterin supported nitric oxide production is crucial for the microbicidal activity of neutrophils

Recent report from this lab has shown role of Rac2 in the translocation of inducible nitric oxide synthase (iNOS) to the phagosomal compartment of polymorphonuclear leukocytes (PMNs) following phagocytosis of beads. This study was undertaken to further assess the status and role of tetrahydrobiopterin (BH4), a redox-sensitive cofactor, L-arginine, and the substrate of nitric oxide synthase (NOS) in sustained nitric oxide (˙NO) production in killing of phagocytosed microbes (Escherichia coli) by human PMNs. Time-dependent study revealed consistent NO and reactive oxygen species (ROS) production in the PMNs following phagocytosis of beads. In addition, levels of L-arginine and BH4 were maintained or increased simultaneously to support the enzymatic activity of NOS in the bead activated PMNs. Moreover, translocation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) subunits along with iNOS was reconfirmed in the isolated phagosomes. We demonstrate that increase in the level of NO was supported by L-arginine and BH4 to kill E. coli, by using PMNs from NOS2-/- mice, human PMNs treated with biopterin inhibitor, N-acetyl serotonin (NAS), or by suspending human PMNs in L-arginine deficient medium. Altogether, this study demonstrates that following phagocytosis, sustained. NO production in the PMNs was well-maintained by redox sensitive cofactor, BH4 and substrate, and L-arginine to enable microbial killing. Further results suggest NO production in the human PMNs, along with ROS and myeloperoxidase (MPO) is important to execute antimicrobial activity.

Anti-aggregatory effect of boswellic acid in high-fat fed rats: involvement of redox and inflammatory cascades

INTRODUCTION

A high-fat diet is one of the main dietary factors promoting platelet aggregation. The present study was conducted to elucidate the involvement of boswellic acid (BA) on the platelet hyperaggregability in HFD-fed rats. As platelet hyperaggregability in HFD rats is closely linked to inflammation and enhanced free radical production, the present study was extended to evaluate the anti-inflammatory and anti-oxidative effect of BA on HFD-promoted platelet aggregation.

MATERIAL AND METHODS

Rats were assigned to normal, HFD-fed, aspirin-treated (30 mg/kg), and BA-treated (250 and 500 mg/kg) groups.

RESULTS

Boswellic acid administration in a high dose was effective in attenuating the severity of hyperlipidemia and platelet aggregation, indicated by lower collagen/epinephrine-induced platelet aggregation, as evidenced by the significant increase (p < 0.05) in the circulating platelet count and reduction in the number of thrombi in the lungs. Moreover, it attenuated the oxidative stress and the intensity of inflammatory mediators associated with platelet hyperaggregability, as evidenced by the inhibitory effects on interlukin-1β, COX-2 and tumor necrosis factor-α, indicating that the antiplatelet activity of BA is likely a consequence of controlling oxidative stress and inflammation.

CONCLUSIONS

The present data suggest that BA shows a promising anti-aggregatory effect by attenuating the enhanced hyperlipidemia, oxidative stress and inflammation associated with HFD.

Effect of evening primrose oil and ω-3 polyunsaturated fatty acids on the cardiovascular risk of celecoxib in rats

Experimental data raised the specter of increased cardiovascular risk with selective cyclooxygenase-2 inhibitors. The study aimed to investigate the cardiovascular risk caused by celecoxib by studying its effect on blood pressure (BP) and thrombogenesis in rats. We tested the possible protective effects of evening primrose oil (EPO) or ω-3 polyunsaturated fatty acids (n-3 PUFAs). Male Wistar rats were assigned to the following groups: vehicle, celecoxib, celecoxib/n-3 PUFAs, celecoxib/EPO, n-3 PUFAs, and EPO. The rats were treated with celecoxib (20 mg·kg(-1)·d(-1)) by gastric gavage for 6 weeks. The mean BP was recorded, and blood samples were collected for testing prothrombin time and activated partial thromboplastin time. Platelet aggregation assay and collagen-induced platelet consumption test were used as models of thrombogenesis. Celecoxib increased the BP without affecting coagulation parameters and accelerated thrombogenesis by increasing platelet aggregation and collagen-induced thrombocytopenia. EPO and n-3 PUFAs decreased the celecoxib-induced elevation in BP. Although EPO significantly decreased platelet aggregation and collagen-induced thrombocytopenia, n-3 PUFAs did not. Celecoxib elevated BP and increased the risk of thrombogenesis in rats. A combination of celecoxib and the selected natural supplements is suggested as a novel approach to minimize cardiovascular risk caused by celecoxib.