Arachidonic acid-derived lipid mediators in multiple sclerosis pathogenesis: fueling or dampening disease progression?

BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS), characterized by neuroinflammation, demyelination, and neurodegeneration. Considering the increasing prevalence among young adults worldwide and the disabling phenotype of the disease, a deeper understanding of the complexity of the disease pathogenesis is needed to ultimately improve diagnosis and personalize treatment opportunities. Recent findings suggest that bioactive lipid mediators (LM) derived from ω-3/-6 polyunsaturated fatty acids (PUFA), also termed eicosanoids, may contribute to MS pathogenesis. For example, disturbances in LM profiles and especially those derived from the ω-6 PUFA arachidonic acid (AA) have been reported in people with MS (PwMS), where they may contribute to the chronicity of neuroinflammatory processes. Moreover, we have previously shown that certain AA-derived LMs also associated with neurodegenerative processes in PwMS, suggesting that AA-derived LMs are involved in more pathological events than solely neuroinflammation. Yet, to date, a comprehensive overview of the contribution of these LMs to MS-associated pathological processes remains elusive. MAIN BODY: This review summarizes and critically evaluates the current body of literature on the eicosanoid biosynthetic pathway and its contribution to key pathological hallmarks of MS during different disease stages. Various parts of the eicosanoid pathway are highlighted, namely, the prostanoid, leukotriene, and hydroxyeicosatetraenoic acids (HETEs) biochemical routes that include specific enzymes of the cyclooxygenases (COXs) and lipoxygenases (LOX) families. In addition, cellular sources of LMs and their potential target cells based on receptor expression profiles will be discussed in the context of MS. Finally, we propose novel therapeutic approaches based on eicosanoid pathway and/or receptor modulation to ultimately target chronic neuroinflammation, demyelination and neurodegeneration in MS. SHORT CONCLUSION: The eicosanoid pathway is intrinsically linked to specific aspects of MS pathogenesis. Therefore, we propose that novel intervention strategies, with the aim of accurately modulating the eicosanoid pathway towards the biosynthesis of beneficial LMs, can potentially contribute to more patient- and MS subtype-specific treatment opportunities to combat MS.

Vasorelaxing effect of Garcinia cowa leaf extract in rat thoracic aorta and its underlying mechanisms.

Background and aim: The leaves of Garcinia cowa (G. cowa) are used in Thai traditional medicine to improve blood circulation. However, there is no scientific evidence to confirm this therapeutic claim. Here, we investigated the vasorelaxing effect and its underlying mechanisms of an aqueous extract of G. cowa leaves in rat thoracic aortic rings. Materials and methods: Dried leaves of G. cowa were extracted with water, followed by phytochemical analysis. Vascular reactivity experiments were performed in isolated rat thoracic aortic rings using an organ bath system. The results were recorded using the data acquisition system Power Lab. Results: Phytochemical analysis showed that the leaves of G. cowa are rich in polyphenols and flavonoids, especially kaempferol, vitexin, and isovitexin. The G. cowa leaf extract caused a concentration-dependent relaxation of aortic rings. This effect was attenuated by denudation of the endothelium, or by pre-treatment of the aortic rings with l-NAME, ODQ, indomethacin, or glibenclamide, but not with TEA. Conclusion: This study indicates that G. cowa leaf extract induces vasorelaxation through both endothelium-dependent and endothelium-independent manners. Its mechanism of action mainly involves the production of nitric oxide and prostanoids, as well as opening ATP-sensitive K+ channels. The vasorelaxing effect of G. cowa leaf extract is probable promoted by the action of flavonoids.

Tagetes erecta L. flowers, a medicinal plant traditionally used to promote diuresis, induced diuretic and natriuretic effects in normotensive and hypertensive rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Tagetes erecta L., known as marigold, belongs to the Asteraceae family and is mainly found in South America. Despite reports that T. erecta flowers are used in folk medicine to treat cardiovascular and renal diseases, there is no study regarding its diuretic effect. AIM: This study aimed to evaluate the chemical composition and the diuretic efficacy of the hydroethanolic extract from T. erecta (HETE) in normotensive (NTR) and hypertensive (SHR) rats. MATERIAL AND METHODS: The HETE was analyzed by liquid chromatography coupled to diode array detector and mass spectrometry (LC-DAD-MS). Female and male NTR and SHR received the treatment with vehicle, HETE (0.01 mg/kg, 0.1 mg/kg, and 1 mg/kg) or hydrochlorothiazide (HCTZ; 5 mg/kg) orally. The urinary parameters were measured at the end of the 8-h experiment. RESULTS: From HETE, saccharides and triterpenes were the main annotated compounds, such as erythrodiol and ß-amyrin. The urine volume was significantly increased in the groups treated with HETE, in both male and female NTR and SHR rats, compared to the respective vehicle-treated groups. Regarding electrolytes elimination, the treatment with HETE did not reveal significant changes in the urine levels of K+ or Cl-, but it showed a natriuretic and Ca2+-sparing effects. The HETE beneficial result in reducing Ca2+ excretion was confirmed through the protective effect found in front of the urinary calcium oxalate precipitation and crystallization. The combination with HCTZ, a classic diuretic and saluretic medicine, significantly enhanced HETE-induced diuresis, natriuresis, and the Ca2+-sparing effect. On the other hand, the K+-sparing action was improved in the combination of HETE with amiloride, a standard K+-sparing diuretic. In contrast, the combination of HETE with atropine (a non-selective muscarinic receptor antagonist) and indomethacin (an inhibitor of the cyclooxygenase enzyme), promoted an important reduction in urinary volume, but interestingly the natriuretic effect was maintained. CONCLUSION: This study contributed to the preclinical validation of the diuretic efficacy of T. erecta, highlighting this species as promising for the development of new pharmacological strategies for the management of kidney disorders.

Lippia alnifolia essential oil induces relaxation on Guinea-pig trachea by multiple pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Lippia alnifolia Mart. & Schauer, known as "alecrim-do-mato", "alecrim-de-vaqueiro" and "pedrécio", is used in folk medicine as antiseptic and to treat diseases that affect respiratory system, like bronchitis and asthma. AIM OF THE STUDY: The aim of this work was to investigate the spasmolytic activity and relaxant mechanism of the Lippia alnifolia essential oil (EOLA) on isolated guinea-pig trachea and to correlate with its use in folk medicine. MATERIALS AND METHODS: Leaves from L. alnifolia were collected in Pico das Almas, Chapada Diamantina, situated in the city of Rio de Contas, Bahia, Brazil. EOLA was extracted by hydrodistillation, analyzed by GC/FID and GC/MS and the volatile constituents were identified. Spasmolytic activity was assayed in isolated guinea-pig trachea pre-contracted with carbachol 1 µM or histamine 10 µM. Relaxant mechanism of EOLA was determined comparing concentration-response curves in the presence or absence of different blockers. RESULTS: Chemical analysis revealed the presence of carvone (60 ±â€¯0.8%) as major constituent. EOLA (1-243 µg/mL) relaxed isolated guinea-pig trachea pre-contracted with carbachol 1 µM [EC50 = 53.36 (44.75-63.51) µg/mL] or histamine 10 µM [EC50 = 5.42 (4.42-6.65) µg/mL]. The pre-incubation of 4-aminopyridine in histamine-induced contractions did not alter significantly the relaxant effect of EOLA. However, the presence of cesium chloride, glibenclamide, tetraethylammonium, propranolol, indomethacin, dexamethasone, hexamethonium, atropine, L-NAME, methylene blue or ODQ reduced EOLA relaxant effect. EOLA 18 µg/mL pre-incubation in calcium-free medium reduced histamine-evoked contractions, but did not alter histamine contractions in the presence of nifedipine. CONCLUSIONS: Lippia alnifolia essential oil has spasmolytic activity on isolated guinea-pig trachea and its mechanism of action possibly involves the activation of multiple signal transduction pathways, which culminate in potassium channels activation and cytosolic calcium reduction.

Preclinical evaluation of the diuretic and saluretic effects of (-)-epicatechin and the result of its combination with standard diuretics.

Several studies have suggested that (-)-epicatechin-containing foods and plant extracts benefit conditions that affect the cardiovascular system, such as hypertension and endothelial dysfunction. However, no study was conducted so far to evaluate the potential of this flavonoid on diuretic activity assay. For that, female Wistar normotensive (NTR) and spontaneously hypertensive rats (SHR) received a single oral treatment with (-)-epicatechin (EPI), hydrochlorothiazide (HCTZ) or just vehicle (VEH). The effects of EPI in combination with diuretics for clinical use, as well as with L-NAME, atropine and indomethacin were also explored. Cumulative urine volume, plasma and urinary parameters were evaluated at the end of 8 h experiment. When given to NTR and SHR, at doses of 0.3, 1 and 3 mg/kg, EPI was able to stimulate both diuresis and saluresis (Na+, K+ and Cl-), without interfering with plasma electrolyte content or urinary pH and uric acid values, when compared with VEH-treated only rats. The combination with HCTZ, but not with furosemide or amiloride, successfully strengthened EPI-induced diuresis. This effect was not accompanied by a potentiation of the saluretic effects. On the other hand, when given EPI in combination with amiloride, a significant increase in Cl- excretion and maintenance of the potassium-sparing effects characteristic of this class of diuretics were detected. In addition, the diuretic effect of EPI was enhanced after pretreatment with L-NAME and its action was significantly precluded in the presence of indomethacin, a cyclooxygenase inhibitor. In conclusion, this study shows the diuretic and saluretic properties of EPI in rats, adding another biological activity whose effect may contribute to the different positive actions already described.

Cytotoxic and pro-oxidative effects of Imperata cylindrica aerial part ethyl acetate extract in colorectal cancer in vitro.

BACKGROUND: Colorectal cancer (CRC) is the third most common cancer. Its global incidence and mortality have been on the rise. Recent strategy of therapies has involved the use of non-steroid anti-inflammatory drugs and cyclooxygenase-selective inhibitors. Aerial parts of Imperata cylindrical L. Raeusch (IMP) have been used as an anti-inflammatory agent in traditional Chinese medicine. HYPOTHESIS: Asarachidonate acid cascadeis often involved in inflammation-related malignancy and IMP is an anti-inflammatory agent, hence it is hypothesized that IMP aerial part ethyl acetate extract exerts cytotoxic effects on colorectal cancer cells in vitro. STUDY DESIGN: The HT-29 adenocarcinoma cell line was used to elucidate its pro-apoptotic activities. Flow cytometry and fluorescent microscopy were performed to assess cell cycle arrest and the accumulation of reactive oxygen species (ROS). The mRNA and hormone levels of arachidonate acid pathways were studied via quantitative reverse transcription PCR (qRT-PCR) and ELISA. RESULTS: The 50% growth inhibitory effect (GI50) of the IMP extract on HT-29 was measured with a value of 14.5 µg/ml. Immuno-blot and caspase-3/7 activity assay showed the pro-apoptotic effect of IMP on the activation of caspase cascade. G2/M arrest was observed via flow cytometry. The ROS activity was modulated by the IMP extraction a concentration-dependent manner in HT-29 cells. The IMP extract increased PGE2 and PGF2α levels qRT-PCR revealed that transcripts of rate-limiting PGE2- and PGF2α-biosynthetic enzymes - COX-1, mPGES1 and AKR1C3 were notably up-regulated. Among the prostanoid receptors, EP1 and FP transcripts were up-regulated while EP4 transcripts decreased. The findings suggest that the proliferative effect of PGE2, which is generally believed to associate with heightened DNA synthesis and cross-talk with MAPK pathways, is likely triggered by the pro-apoptotic or -oxidative effects exerted by IMP extract in HT-29 cells. Concurring with this notion, indomethacin (COX-1/2-inhibitor) was demonstrated to potentiate the cytotoxic effect of IMP extract (GI50 ≦ 10.8 µg/ml). The results show that the cytotoxic effect of IMP extract predominates over the influence of proliferative prostanoids released by challenged colorectal cancer cells, and may present a potential source for development of novel anti-cancer drugs.

Areca nut components stimulate ADAM17, IL-1α, PGE2 and 8-isoprostane production in oral keratinocyte: role of reactive oxygen species, EGF and JAK signaling.

Betel quid (BQ) chewing is an etiologic factor of oral submucous fibrosis (OSF) and oral cancer. There are 600 million BQ chewers worldwide. The mechanisms for the toxic and inflammatory responses of BQ are unclear. In this study, both areca nut (AN) extract (ANE) and arecoline stimulated epidermal growth factor (EGF) and interleukin-1α (IL-1α) production of gingival keratinocytes (GKs), whereas only ANE can stimulate a disintegrin and metalloproteinase 17 (ADAM17), prostaglandin E2 (PGE2) and 8-isoprostane production. ANE-induced EGF production was inhibited by catalase. Addition of anti-EGF neutralizing antibody attenuated ANE-induced cyclooxygenase-2 (COX-2), mature ADAM9 expression and PGE2 and 8-isoprostane production. ANE-induced IL-1α production was inhibited by catalase, anti-EGF antibody, PD153035 (EGF receptor antagonist) and U0126 (MEK inhibitor) but not by α-naphthoflavone (cytochrome p450-1A1 inhibitor). ANE-induced ADAM17 production was inhibited by pp2 (Src inhibitor), U0126, α-naphthoflavone and aspirin. AG490 (JAK inhibitor) prevented ANE-stimulated ADAM17, IL-1α, PGE2 production, COX-2 expression, ADAM9 maturation, and the ANE-induced decline in keratin 5 and 14, but showed little effect on cdc2 expression and EGF production. Moreover, ANE-induced 8-isoprostane production by GKs was inhibited by catalase, anti-EGF antibody, AG490, pp2, U0126, α-naphthoflavone, Zinc protoporphyrin (ZnPP) and aspirin. These results indicate that AN components may involve in BQ-induced oral cancer by induction of reactive oxygen species, EGF/EGFR, IL-1α, ADAMs, JAK, Src, MEK/ERK, CYP1A1, and COX signaling pathways, and the aberration of cell cycle and differentiation. Various blockers against ROS, EGF, IL-1α, ADAM, JAK, Src, MEK, CYP1A1, and COX can be used for prevention or treatment of BQ chewing-related diseases.

Organotypical vascular model for characterization of radioprotective compounds: studies on antioxidant 2,3-diaryl-substituted indole-based cyclooxygenase-2 inhibitors.

Radiotherapy of various cancers is closely associated with increased cardiovascular morbidity and mortality. Arachidonic acid metabolites are supposed to play a key role in radiation-induced vascular dysfunction. This study was designed to evaluate the effects of novel, antioxidative 2,3-diaryl-substituted indole-based selective cyclooxygenase-2 (COX-2) inhibitors (2,3-diaryl-indole coxibs) on radiation-induced formation of arachidonic acid metabolites via COX-2 and oxidant stress pathways in an organotypical vascular model of rat aortic rings. Acute and subacute effects of X-ray radiation (4 and 10 Gy; 1 and 3 days post irradiation) with or without the presence of 1 µM of the 2,3-diaryl-indole coxib 2-[4-(aminosulfonyl)phenyl]-3-(4-methoxyphenyl)-1H-indole (C1) or celecoxib as reference compared to sham-irradiated controls were assessed. The following parameters were measured: metabolic activity of the aortic rings; induction and regulation of COX-2 expression; release of prostaglandin E2 and F2α-isoprostane. Irradiation without presence of coxibs resulted in a dose-dependent augmentation of all parameters studied. When aortic rings were exposed to the 2,3-diaryl-indole coxib 1 h before irradiation, metabolic activity was restored and the release of both prostaglandin and isoprostane was inhibited. The latter indicates a direct interaction with oxidant stress pathways. By contrast, celecoxib exhibited only slight effects on the formation of isoprostane. The reduction of radiation-induced vascular dysfunction by antioxidative coxibs may widen the therapeutic window of COX-2 targeted treatment.

Effects of the chronic ingestion of an infusion of Ruta chalepensis on the vasomotor responses of rat aortic rings / Efectos de la ingestión crónica de una infusión de Ruta chalepensis sobre las respuestas vasomotoras de anillos de aorta de rata

Ruta chalepensis, is used, in traditional medicine, as emmenagogue, abortive, and analgesic. We analyzed, in male Wistar rats, the effects of the chronic intake of an infusion of Ruta chalepensis (20 g/L) on the vasomotor responses of, either intact or endothelium-denuded aortic rings, to phenylephrine or carbachol. Only in rings with endothelium significant effects were observed. The infusion induced a leftward shift of the concentration-response curve to phenylephrine and an increase in maximal tension development. These effects were abolished by indomethacin. In these rings, inhibiting the synthesis of nitric oxide, in the presence of indomethacin, induced a leftward shift of the concentration response curve to phenylephrine, as well as an increase in maximal tension. These results suggest that the chronic ingestion of a Ruta chalepensis infusion induces an endothelium dependent increase in the synthesis/release of cyclooxygenase-dependent vasoconstrictor prostanoids, and an increase in the basal synthesis/release of nitric oxide.

Ruta chalepensis se utiliza en la medicina tradicional como emenagogo, abortivo y analgésico. Se analizaron, en ratas Wistar macho, los efectos de la ingesta crónica de una infusión de Ruta chalepensis (20 g /L), sobre las respuestas vasomotoras de anillos de aorta con y sin endotelio, a la fenilefrina o al carbacol Se observaron efectos significativos sólo en anillos con endotelio. La infusión indujo un desplazamiento a la izquierda de la curva de concentración-respuesta a fenilefrina y un incremento en la tensión máxima desarrollada. Estos efectos fueron abolidos por la indometacina. La inhibición de la síntesis de óxido nítrico, en presencia de indometacina, produjo un desplazamiento a la izquierda de la curva de concentración-respuesta a la fenilefrina, así como un incremento en la tensión máxima. Estos resultados sugieren que la ingesta crónica de una infusión de Ruta chalepensis induce un incremento en la síntesis/liberación de prostanoides vasoconstrictores dependientes de la ciclooxigenasa y un aumento en la síntesis /liberación basal de óxido nítrico.

Therapeutic strategies in pulmonary hypertension.

Pulmonary hypertension (PH) is a life-threatening condition characterized by elevated pulmonary arterial pressure. It is clinically classified into five groups: patients in the first group are considered to have pulmonary arterial hypertension (PAH) whereas patients of the other groups have PH that is due to cardiopulmonary or other systemic diseases. The management of patients with PH has advanced rapidly over the last decade and the introduction of specific treatments especially for PAH has lead to an improved outcome. However, despite the progress in the treatment, the functional limitation and the survival of these patients remain unsatisfactory and there is no cure for PAH. Therefore the search for an "ideal" therapy still goes on. At present, two levels of treatment can be identified: primary and specific therapy. Primary therapy is directed at the underlying cause of the PH. It also includes a supportive therapy consisting in oxygen supplementation, diuretics, and anticoagulation which should be considered in all patients with PH. Specific therapy is directed at the PH itself and includes treatment with vasodilatators such as calcium channel blockers and with vasodilatator and pathogenetic drugs such as prostanoids, endothelin receptor antagonists and phosphodiesterase type-5 inhibitors. These drugs act in several pathogenetic mechanisms of the PH and are specific for PAH although they might be used also in the other groups of PH. Finally, atrial septostomy and lung transplantation are reserved for patients refractory to medical therapy. Different therapeutic approaches can be considered in the management of patients with PH. Therapy can be established on the basis of both the clinical classification and the functional class. It is also possible to adopt a goal-oriented therapy in which the timing of treatment escalation is determined by inadequate response to known prognostic indicators.

The Role of Prostanoids in vivo Feline Penile Erection / 대한비뇨기과학회지

PURPOSE: The widespread use of intracorporeal prostaglandin E1 (PGE 1) injection for the treatment of erectile dysfunction has focused interest on the physiological functions of prostanoids with the mechanism of action. We investigated in vivo feline penile erectile and contractile responses to prostanoids. MATERIALS AND METHODS: Under the general anesthesia, 26 mature male cats were conditioned normoxia and hypoventilated hypoxia with ventilator in room air(PH: 7.14+/- 0.47, PO2: 25.52+/-5.89mmHg, PCO2: 74.27+/-10.86mmHg). Vasoactive substances were infused via internal pudendal artery and the changes of intracavernous pressure to vasoactive substances were monitored with physiograph under normoxia and hypoxia with acidosis. RESULTS: Under normoxia, PGE1 induced dose-dependent cavernous relaxation and PGE1 was more potent than papaverine but less than acetylcholine. PGE1- induced cavernous relaxation was blocked by the K+-channel blockers, tetraethylammonium(TEA) and 4-aminopyridine, in dose-dependent manner but was completely reversed by the K+-channel opener, pinacidil. Calcium ionophore, ionomycin(10-3M/0.2ml) prevented the cavernous relaxation by PGE1 under hypoxia(n=6, p<0.01). PGI2 showed minimal cavernous relaxation with tumescence. Thromboxane A2(TXA2) attenuated the acetylcholine-induced relaxation CONCLUSIONS: This study showed that PGE2 relax feline cavernous smooth muscle. But the mechanism of PGE2 on feline cavernosum should be elucidated by the receptor binding study. These results suggest that PGE2 induced smooth muscle relaxation by the opening of Maxi-K+ (Kca) channel and subsequent hyperpolarization. It would be followed by a reduced opening of voltage-dependent Ca2+-channel and subsequent decrease of intracellular Ca2+concentration.