In vitro and in vivo assessment of meadowsweet (Filipendula ulmaria) as anti-inflammatory agent.

ETHNOPHARMACOLOGICAL RELEVANCE: Meadowsweet (Filipendula ulmaria (L.) Maxim, Rosaceae) has been traditionally used in most European countries for the treatment of inflammatory diseases due to its antipyretic, analgesic, astringent, and anti-rheumatic properties. However, there is little scientific evidence on F. ulmaria anti-inflammatory effects regarding its impact on cyclooxygenases enzymatic activity and in vivo assessment of anti-inflammatory potential. This study aims to reveal the anti-inflammatory activity of methanolic extracts from the aerial parts (FUA) and roots (FUR) of F. ulmaria, both in in vitro and in vivo conditions. MATERIALS AND METHODS: The characteristic phenolic compounds in F. ulmaria extracts were monitored via high performance thin layer chromatography (HPTLC). The in vitro anti-inflammatory activity of F. ulmaria extracts was evaluated using cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzyme assays, and an assay for determining COX-2 gene expression. The in vivo anti-inflammatory effect of F. ulmaria extracts was determined in two doses (100 and 200 mg/kg b.w.) with hot plate test and carrageenan-induced paw edema test in rats. Inflammation was also evaluated by histopathological and immunohistochemical analysis. RESULTS: FUA extract showed the presence of rutoside, spiraeoside, and isoquercitrin. Both F. ulmaria extracts at a concentration of 50µg/mL were able to inhibit COX-1 and -2 enzyme activities, whereby FUA extract (62.84% and 46.43% inhibition, respectively) was double as effective as the root extract (32.11% and 20.20%, respectively). Extracts hardly inhibited the level of COX-2 gene expression in THP-1 cells at a concentration of 25µg/mL (10.19% inhibition by FUA and 8.54% by FUR). In the hot plate test, both extracts in two doses (100 and 200mg/kg b.w.), exhibited an increase in latency time when compared with the control group (p<0.05). In the carrageenan-induced acute inflammation test, FUA at doses of 100 and 200mg/kg b.w., and FUR at 200mg/kg, were able to significantly reduce the mean maximal swelling of rat paw until 6h of treatment. Indomethacin, FUA, and FUR extracts significantly decreased inflammation score and this effect was more pronounced after 24h, compared to the control group (p<0.05). CONCLUSIONS: The observed results of in vitro and, for the first time, in vivo anti-inflammatory activity of meadowsweet extracts, provide support of the traditional use of this plant in the treatment of different inflammatory conditions. Further investigation of the anti-inflammatory compounds could reveal the mechanism of anti-inflammatory action of these extracts.

Inhibition of Kv channel expression by NSAIDs depolarizes membrane potential and inhibits cell migration by disrupting calpain signaling.

Clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is well known to cause gastrointestinal ulcer formation via several mechanisms that include inhibiting epithelial cell migration and mucosal restitution. The drug-affected signaling pathways that contribute to inhibition of migration by NSAIDs are poorly understood, though previous studies have shown that NSAIDs depolarize membrane potential and suppress expression of calpain proteases and voltage-gated potassium (Kv) channel subunits. Kv channels play significant roles in cell migration and are targets of NSAID activity in white blood cells, but the specific functional effects of NSAID-induced changes in Kv channel expression, particularly on cell migration, are unknown in intestinal epithelial cells. Accordingly, we investigated the effects of NSAIDs on expression of Kv1.3, 1.4, and 1.6 in vitro and/or in vivo and evaluated the functional significance of loss of Kv subunit expression. Indomethacin or NS-398 reduced total and plasma membrane protein expression of Kv1.3 in cultured intestinal epithelial cells (IEC-6). Additionally, depolarization of membrane potential with margatoxin (MgTx), 40mM K(+), or silencing of Kv channel expression with siRNA significantly reduced IEC-6 cell migration and disrupted calpain activity. Furthermore, in rat small intestinal epithelia, indomethacin and NS-398 had significant, yet distinct, effects on gene and protein expression of Kv1.3, 1.4, or 1.6, suggesting that these may be clinically relevant targets. Our results show that inhibition of epithelial cell migration by NSAIDs is associated with decreased expression of Kv channel subunits, and provide a mechanism through which NSAIDs inhibit cell migration and may contribute to NSAID-induced gastrointestinal (GI) toxicity.

Nimesulide binding site in the B0AT1 (SLC6A19) amino acid transporter. Mechanism of inhibition revealed by proteoliposome transport assay and molecular modelling.

The effect of pharmaceutical compounds on the rat kidney B0AT1 transporter in proteoliposomes has been screened. To this aim, inhibition of the transport activity by the different compounds was measured on Na(+)-[(3)H]glutamine co-transport in the presence of membrane potential positive outside. Most of the tested drugs had no effect on the transport activity. Some compounds exhibited inhibitory effects from 5 to 88% at concentration of 300µM. Among the tested compounds, only the anti-inflammatory drug nimesulide exerted potent inhibition on B0AT1. From dose response analysis, an IC50 value of 23µM was found. Inhibition kinetic analysis was performed: noncompetitive inhibition of the glutamine transport was observed while competitive behaviour was found when the inhibition was analyzed with respect to the Na(+) concentration. Several molecules harbouring functional groups of nimesulide (analogues) were tested as inhibitors. None among the tested molecules has the capacity to inhibit the transport with the exception of the compound NS-398, whose chemical structure is very close to that of whole nimesulide. The IC50 for this compound was 131µM. Inhibition kinetics showed behaviour of NS-398 identical to that of nimesulide, i.e., noncompetitive inhibition respect to glutamine and competitive inhibition respect to Na(+). Molecular docking of nimesulide suggested that this drug is able to bind B0AT1 in an external dedicated binding site and that its binding produces a steric hindrance effect of the protein translocation path abolishing the transporter activity.

Montelukast prevents microparticle-induced inflammatory and functional alterations in human bronchial smooth muscle cells.

Microparticles (MPs) are membrane fragments that may play a role in the pathogenesis of chronic respiratory diseases. We aimed to investigate whether human monocytes/macrophage-derived MPs could induce a pro-inflammatory phenotype in human bronchial smooth muscle cells (BSMC) and the effect of montelukast in this setting. Experimental methods included isolation of human monocytes/macrophages and generation of monocyte-derived MPs, RT-PCR analysis of gene expression, immunoenzymatic determination of pro-inflammatory factor release, bioluminescent assay of intracellular cAMP levels and electromobility shift assay analysis of NF-κB nuclear translocation. Stimulation of human BSMC with monocyte-derived MPs induced a pro-inflammatory switch in human BSMC by inducing gene expression (COX-2 and IL-8), protein release in the supernatant (PGE2 and IL-8), and heterologous ß2-adrenoceptor desensitization. The latter effect was most likely related to autocrine PGE2 since pre-treatment with COX inhibitors restored the ability of salbutamol to induce cAMP synthesis in desensitized cells. Challenge with MPs induced nuclear translocation of NF-κB and selective NF-κB inhibition decreased MP-induced cytokine release in the supernatant. Montelukast treatment prevented IL-8 release and heterologous ß2-adrenoceptor desensitization in human BSMC exposed to monocyte-derived MPs by blocking NF-κB nuclear translocation. These findings provide evidence on the role of human monocyte-derived MPs in the airway smooth muscle phenotype switch as a novel potential mechanism in the progression of chronic respiratory diseases and on the protective effects by montelukast in this setting.