Vatairea guianensis lectin stimulates changes in gene expression and release of TNF-α from rat peritoneal macrophages via glycoconjugate binding.

Using a rat model of peritonitis, we herein report the inflammatory effect induced by the lectin isolated from Vatairea guianensis (VGL) seeds in the context of interactions between VGL and both toll-like receptor 4 (TLR4) and tumor necrosis factor receptor 1 (TNFR1). Peritoneal macrophages were stimulated with VGL for dose-dependent gene expression and release of TNF-α. In vivo results showed that VGL (1 mg/kg; intraperitoneal) induced peritonitis in female Wistar rats. Leukocyte migration, macrophage activation, and protein leakage were measured 3 and 6 hours after induction. In vitro, peritoneal macrophages were stimulated with VGL for gene expression and TNF-α dosage (mean ± SEM (n = 6), analysis of variance, and Bonferroni's test (P < .05)). In silico, VGL structure was applied in molecular docking with representative glycans. It was found that (a) VGL increases vascular permeability and stimulates leukocyte migration, both rolling and adhesion; (b) lectin-induced neutrophil migration occurs via macrophage stimulation, both in vitro and in vivo; (c) lectin interacts with TLR4 and TNFR1; and (d) stimulates TNF-α gene expression (RT-PCR) and release from peritoneal macrophages. Thus, upon lectin-glycan binding on the cell surface, our results suggest that VGL induces an acute inflammatory response, in turn activating the release of peritoneal macrophages via TNF-α and TLR and/or TNFR receptor pathways.

The nitric oxide pathway is involved in the anti-inflammatory effect of the rutheniumcomplex [Ru(bpy)2(2-MIM)(NO)](PF6)3.

Metal coordination complexes are chemotherapeutic and anti-inflammatory agents. The ruthenium complex FOR811A ([Ru(bpy)2(2-MIM)Cl](PF6)3) FOR811A was evaluated in mice models of acute inflammation and behavioral tests. Animals received FOR811A (3, 10 or 30 mg/kg; i.p.), indomethacin (20 mg/kg; i.p.), L-NAME (20 mg/kg; i.v.) aminoguanidine (50 mg/kg; i.p.) or dexamethasone (0.5 mg/kg; s.c.) 30 min before inflammatory stimulation. Paw edema was induced by carrageenan (400 µg/paw), TNF-α or L-arginine (15 nmol/paw) (5 ng/paw) and evaluated by hydropletismometry 4 h later. Peritonitis was induced by carrageenan (500 µg; i.p.) and evaluated 4 h later for hypernociception and quantification of total/differential leukocytes, total protein reduced glutathione (GSH) and myeloperoxidase (MPO). FOR811A inhibited the paw edema induced by carrageenan at 3 (64%; p < 0.0001), 10 (73%; p < 0.0001) and 30 mg/kg (66%; p < 0.0001), and at 10 mg/kg that induced with L-arginine by 75% or TNF-α by 55% (p = 0.0012). Paw tissues histological analysis showed reduction in mast cells (46%; p = 0.0027), leukocyte infiltrate (66%; p < 0.0001), edema and hemorrhagic areas. Immunohistochemical evaluation revealed inhibition of iNOS (62%; p < 0.0001) and TNF-α (35%; p < 0.0001). In the peritonitis model FOR811A increased (2.8X; p < 0.0001) hypernociceptive threshold, reduced total leukocytes (29%; p < 0.0001), neutrophils (47%; p = 0.0003) and total proteins (36%; p = 0.0082). FOR811A also inhibited MPO (47%; p = 0.0296) and increased GSH (1.8X; p < 0.0001). In the behavioral tests, FOR811A reduced (30.6%) the number of crossings in the open field, and increased (16%) the number of falls in the Rota rod. Concluding, FOR811A presents anti-inflammatory and antioxidant effects, via nitric oxide pathway.

The Lectin Isolated from the Alga Hypnea cervicornis Promotes Antinociception in Rats Subjected to Zymosan-Induced Arthritis: Involvement of cGMP Signalization and Cytokine Expression.

This study investigated the effects of the alga lectin Hypnea cervicornis agglutinin (HCA) on rat zymosan-induced arthritis (ZyA). Zymosan (50-500 µg/25 µL) or sterile saline (Sham) was injected into the tibio-tarsal joint of female Wistar rats (180-200 g). Arthritic animals received morphine (4 mg/kg, intraperitoneal), indomethacin (5 mg/kg, intraperitoneal), or 2% lidocaine (100 µL, subcutaneous). HCA (0.3-3 mg/kg) was administered by intravenous route 30 min before or 2 h after zymosan. 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one (ODQ, 4 µg, intra-articular) was given 30 min prior HCA. Hypernociception was measured every hour until 6 h, time in which animals were sacrificed for evaluation of leukocytes of the intra articular fluid and gene expression of TNF-α, IL-1, IL-10, and iNOS in the joint tissues using PCR techniques. Hypernociception was responsive to morphine and indomethacin, and its threshold was not altered by lidocaine. The post-treatment of HCA reduced both hypernociception and leukocyte influx. This antinociceptive effect was abolished either by ODQ and glibenclamide. HCA also reduced gene expression of iNOS and TNF-α. In conclusion, the antinociceptive effect of HCA in ZyA involves cyclic GMP signalization and selective modulation of cytokine expression.

Structural analysis, molecular docking and molecular dynamics of an edematogenic lectin from Centrolobium microchaete seeds.

Lectins represent a class of proteins or glycoproteins capable of reversibly binding to carbohydrates. Seed lectins from the Dalbergieae tribe (Leguminosae) have structural variability, carbohydrate specificity, and biological effects, such as inflammation, vasorelaxation and cancer antigen binding. To comprehensively address these factors, the present work aimed to establish and characterize the three-dimensional structure of Centrolobium microchaete lectin (CML) by homology modeling, investigate protein-carbohydrate interactions and evaluate its inflammatory effect on mice. Molecular docking was performed to analyze interactions of the lectin with monosaccharides, disaccharides and N-glycans. Two dimannosides, methyl mannose-1,3-α-D-mannose (MDM) and mannose-1,3-α-D-mannose (M13), were used in molecular dynamics (MD) simulations to study the behavior of the carbohydrate-recognition domain (CRD) over time. Results showed an expanded domain within which hydrophobic interactions with the methyl group in the MDM molecule were established, thus revealing novel interactions for mannose-specific Dalbergieae lectins. To examine its biological activities, CML was purified in a single step by affinity chromatography on Sepharose-mannose matrix. The lectin demonstrated inflammatory response in the paw edema model and stimulated leukocyte migration to the animal peritoneal cavities, an effect elicited by CRD. For the first time, this work reports the molecular dynamics of a lectin from the Dalbergieae tribe.

The lectin isolated from Lonchocarpus araripensis seed elicits endothelium-dependent vasorelaxation / A lectina isolada de sementes de Lonchocarpus araripensis promove efeito vasorelaxante dependente de endotélio

Background: The vasorelaxant effect of lectins from leguminous plants (Diocleinae subtribe) is well described. However, this effect has been little explored for lectins isolated from Dalbergieae tribe, except for that of Vatairea guianensis, that induces vasorelaxation involving nitric oxide and the lectin domain. Objective: To evaluate the vasorelaxant effect of a lectin isolated from Lonchocarpus araripensis (LAL), Dalbergieae tribe, and the involvement of the lectin domain and endothelium derived relaxing factors. Methods: Aortic rings of Wistar rats (250 - 300 g) were mounted in organ bath and mantained in physiological conditions (CEUA No. 10130208-8/40). LAL (0.1­100 µg/ml) was added to phenylephrine (0.1 µM)-contracted tissues with either endothelium intact or denuded. In order to investigate the mechanisms of LAL relaxation, inhibitors of NOS (L-NAME: 100 µM), cyclooxygenase (indomethacin: 10 µM), or potassium channels (TEA: 5 mM) were added to endothelized tissues 30 min before contraction. The involvement of lectin domain was assessed by previous incubation of LAL (30 µg/ml) with GlcNAc (0.1 M). Results: LAL (0.1-100 µg/ml) induced relaxation only in endothelized aorta, being maximal at 100 µg/ml (62.57 ± 7.8%). The relaxant effect induced by LAL at 30 µg/ml (52.49 ± 10.32%) was abolished by previous incubation with GlcNAc. LAL relaxant effect (IC50 9.75 ± 7.1) was partially reversed by indomethacin (IC50 LAL + indomethacin: 30.47 ± 10.93) and was abolished by L-NAME or TEA. Conclusion: LAL exhibits vasorelaxant activity in contracted endothelized aorta of rats, involving the lectin domain, muscarinic receptor of acetylcholine and endothelial derived relaxing factors. (AU)

Introdução: O efeito vasorrelaxante de lectinas de plantas leguminosas (Subtribo Diocleinae) já é bem descrito, embora pouco explorado para lectinas isoladas da tribo Dalbergieae, com exceção da lectina de Vatairea guianensis, que induz relaxamento com envolvimento de óxido nítrico e do domínio lectínico. Objetivo: Avaliar o efeito vasorrelaxante da lectina isolada de Lonchocarpus araripensis (LAL), tribo Dalbergieae, e o envolvimento do domínio lectínico e de fatores relaxantes derivados do endotélio (EDRF). Métodos: Anéis de aorta de ratos Wistar (250-300 g) foram montados em banho de órgãos em condições fisiológicas (Tyrode, 37 ° C, 95% de O2 e 5% de CO2, pH = 7,4) (CEUA No. 10130208-8/40). LAL (0,1-100 µg/ml) foi adicionada a tecidos pré-contraídos com fenilefrina (0,1 µM) com ou sem endotélio. Para investigar os mecanismos de relaxamento, foram adicionados inibidores de NOS (L-NAME: 100 µM), guanilato ciclase (ODQ: 10 µM), receptor muscarínico (atropina: 1 µM), ciclooxigenase (indometacina: 10 µM) ou canais de potássio (TEA: 5 mM) aos tecidos endotelizados 30 minutos antes da contração. O envolvimento do domínio lectínico foi avaliado por incubação prévia da LAL (30 µg/ml) com GlcNAc (0,1 M). Resultados: LAL (0,1-100 µg/ml) relaxou apenas anéis de aorta endotelizadas, com efeito máximo na dose de 100 µg/ml (62,57 ± 7,8%). O efeito relaxante da LAL a 30 µg/ml (52,49 ± 10,32%) foi abolido por incubação prévia com GlcNAc, atropina ou ODQ. O relaxamento da LAL (IC50 9,75 ± 7,1) a 10, 30 e 100 µg/ml foi parcialmente revertido por indometacina (IC50 LAL + indometacina: 30,47 ± 10,93) e abolido por L-NAME e TEA. Conclusão: A LAL exibe atividade vasorrelaxante em aorta endotelizada de ratos, no estado contraído, envolvendo o domínio lectínico, receptor muscarínico e fatores relaxantes derivados do endotélio. (AU)