RESUMO
Lectins are a group of proteins of non-immune origin recognized for their ability to bind reversibly to carbohydrates. Researchers have been intrigued by oligosaccharides and glycoconjugates for their involvement as mediators of complex cellular events and then many biotechnological applications of lectins are based on glycocode decoding and their activities. Here, we report a structural and biological study of a ConA-like mannose/glucose-specific lectin from Canavalia bonariensis seeds, CaBo. More specifically, we evaluate the binding of CaBo with α-methyl-D-mannoside (MMA) and mannose-1,3-α-D-mannose (M13) and the resultant in vivo effects on a rat model of acute inflammation. A virtual screening was also carried out to cover a larger number of possible bindings of CaBo. In silico analysis demonstrated the stability of CaBo interaction with mannose-type ligands, and the lectin was able to induce acute inflammation in rats with the participation of the carbohydrate recognition domain (CRD) and histamine release. These results confirm the ability of CaBo to interact with hybrid and high-mannose N-glycans, supporting the hypothesis that CaBo's biological activity occurs primarily through its interaction with cell surface glycosylated receptors.
Assuntos
Carboidratos/química , Inflamação/tratamento farmacológico , Lectinas de Ligação a Manose/farmacologia , Lectinas de Plantas/farmacocinética , Animais , Sítios de Ligação , Histamina/farmacologia , Humanos , Inflamação/induzido quimicamente , Inflamação/patologia , Manose/química , Lectinas de Ligação a Manose/química , Manosídeos/química , Lectinas de Plantas/química , Lectinas de Plantas/farmacologia , Polissacarídeos/química , RatosRESUMO
BACKGROUND: Lectins have been studied in recent years due to their immunomodulatory activities. OBJECTIVE: We purified a lectin named OniL from tilapia fish (Oreochromis niloticus) and here we analyzed the cell proliferation and cytokine production in Balb/c mice splenocytes. METHODS: Cells were stimulated in vitro in 24, 48, 72 hours and 6 days with different concentrations of OniL and Con A. Evaluation of cell proliferation was performed through [3H]-thymidine incorporation, cytokines were investigated using ELISA assay and cell viability assay was performed by investigation of damage through signals of apoptosis and necrosis. RESULTS: OniL did not promote significant cell death, induced high mitogenic activity in relation to control and Con A and stimulated the cells to release high IL-2 and IL-6 cytokines. CONCLUSION: These findings suggest that, like Con A, OniL lectin can be used as a mitogenic agent in immunostimulatory assays.
Assuntos
Proliferação de Células/efeitos dos fármacos , Lectinas de Ligação a Manose/farmacologia , Mitógenos/farmacologia , Baço/citologia , Animais , Morte Celular , Linhagem Celular , Sobrevivência Celular , Concanavalina A/farmacologia , Citocinas/biossíntese , Masculino , Camundongos Endogâmicos BALB C , TilápiaRESUMO
Carbohydrate-binding proteins, also known as lectins, are valuable tools for biotechnology, including pharmacological uses. Mannose lectins obtained from plant and animal sources are applied to protection and characterization of autoimmune diseases as well as defense proteins against pathogens. The presence of mannose-binding lectins in plants that also recognize glucose could be entitled Man/Glc lectins; such specificity has allowed employing these vegetal lectins for several applications. Animal mannose-binding lectins are synthesized in the liver and secreted into the blood stream where both concentration and activity are greatly affected due to gene polymorphisms; these serum proteins play important roles in the immune system by recognizing mannose-like carbohydrate ligands found exclusively on pathogenic microorganisms. Mannose lectins already showed strong binding to relevant bacteria, viruses, protozoa and helminth species, initiating potent host defense mechanisms by inducing growth inhibition or death of such organisms; the ability to prevent the formation or destruction of microbial biofilms has also been reported. Mannose-binding lectins have attracted considerable attention against carcinogenesis and atherogenesis. The aim of this review article is to approach biotechnology characteristics of these lectins from different sources and microorganism/cell surface interactions with mannose; in addition, aspects of mechanisms associated to lectin antipathogenic activities are described.
Assuntos
Anti-Infecciosos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Lectinas/farmacologia , Lectinas de Ligação a Manose/farmacologia , Plantas/química , Animais , Anti-Infecciosos/química , Antineoplásicos Fitogênicos/química , Sítios de Ligação , Biotecnologia , Proliferação de Células/efeitos dos fármacos , Glicosilação , Lectinas/química , Manose/química , Manose/metabolismo , Lectinas de Ligação a Manose/química , Modelos Moleculares , Lectinas de Plantas/farmacologia , Ligação ProteicaAssuntos
Dioclea/química , Lectinas de Ligação a Manose/química , Lectinas de Plantas/química , Sementes/química , Animais , Apoptose/efeitos dos fármacos , Sítios de Ligação , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cristalização , Glioma , Lectinas de Ligação a Manose/isolamento & purificação , Lectinas de Ligação a Manose/farmacologia , Simulação de Acoplamento Molecular , Lectinas de Plantas/isolamento & purificação , Lectinas de Plantas/farmacologia , Ligação Proteica , Conformação Proteica , RatosRESUMO
With important carbohydrate binding properties, lectins are proteins able to decipher the glycocode, and as such, they can be used in bioassays involving cell-cell communication, protein targeting, inflammation, and hypernociception, among others. In this study, a new glucose/mannose-specific lectin from Canavalia villosa seeds (Cvill) was isolated by a single affinity chromatography step in a Sephadex® G-50 column, with a purification yield of 19.35mg of lectin per gram of powdered seed. Analysis of intact protein by mass spectrometry showed the lectin is composed of three polypeptide chains, including a 25.6kDa α chain, 12.9KDa ß, and 12.6 KDa γ fragments, similar to the profile of ConA-like glucose/mannose-specific lectins. Partial sequence of the protein was obtained by MS-MALDI TOF/TOF covering 41.7% of its primary structure. Cvill presented sugar specificity to d-glucose, α-methyl-d-mannoside, d-mannose, and glycoproteins fetuin and ovoalbumin. The lectin characterization showed that Cvill presents high stability within a broad range of pH and temperature, also showing average toxicity against Artemia nauplii. The proinflammatory effect of Cvill was observed by induction of paw edema and hypernociception in mice, with the participation of the carbohydrate binding site, showing its potential to be used as tool in inflammation studies.
Assuntos
Analgésicos/farmacologia , Canavalia/química , Glucose/metabolismo , Lectinas de Ligação a Manose/farmacologia , Manose/metabolismo , Lectinas de Plantas/farmacologia , Sementes/química , Sequência de Aminoácidos , Analgésicos/química , Analgésicos/metabolismo , Analgésicos/uso terapêutico , Animais , Artemia/efeitos dos fármacos , Edema/tratamento farmacológico , Concentração de Íons de Hidrogênio , Inflamação/tratamento farmacológico , Masculino , Lectinas de Ligação a Manose/química , Lectinas de Ligação a Manose/metabolismo , Lectinas de Ligação a Manose/uso terapêutico , Camundongos , Lectinas de Plantas/química , Lectinas de Plantas/metabolismo , Lectinas de Plantas/uso terapêutico , TemperaturaRESUMO
The recognition of cell surface glycans by lectins may be critical for the innate and adaptive immune responses. ArtinM, a d-mannose-binding lectin from Artocarpus heterophyllus, activates antigen-presenting cells by recognizing TLR2 N-glycans and induces Th1 immunity. We recently demonstrated that ArtinM stimulated CD4⺠T cells to produce proinflammatory cytokines. Here, we further studied the effects of ArtinM on adaptive immune cells. We showed that ArtinM activates murine CD4⺠and CD8⺠T cells, augmenting their positivity for CD25, CD69, and CD95 and showed higher interleukin (IL)-2 and interferon (IFN)-γ production. The CD4⺠T cells exhibited increased T-bet expression in response to ArtinM, and IL-2 production by CD4⺠and CD8⺠T cells depended on the recognition of CD3εγ-chain glycans by ArtinM. The ArtinM effect on aberrantly-glycosylated neoplastic lymphocytes was studied in Jurkat T cells, in which ArtinM induced IL-2, IFN-γ, and IL-1ß production, but decreased cell viability and growth. A higher frequency of AnnexinV- and propidium iodide-stained cells demonstrated the induction of Jurkat T cells apoptosis by ArtinM, and this apoptotic response was reduced by caspases and protein tyrosine kinase inhibitors. The ArtinM effects on murine T cells corroborated with the immunomodulatory property of lectin, whereas the promotion of Jurkat T cells apoptosis may reflect a potential applicability of ArtinM in novel strategies for treating lymphocytic leukemia.
Assuntos
Morte Celular/efeitos dos fármacos , Ativação Linfocitária/efeitos dos fármacos , Lectinas de Ligação a Manose/farmacologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo , Animais , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/metabolismo , Proliferação de Células/efeitos dos fármacos , Citometria de Fluxo , Interferon gama/metabolismo , Interleucina-1beta/metabolismo , Interleucina-2/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
ArtinM is a D-mannose-binding lectin extracted from Artocarpus heterophyllus that promotes interleukin-12 production by macrophages and dendritic cells. This property is considered responsible for T helper 1 immunity induced in vivo after ArtinM administration. In this study, we investigated the effect of native (jArtinM) and recombinant (rArtinM) forms of lectin on murine spleen cells and isolated T lymphocytes. We found that ArtinM binds to the surface of spleen cells. This interaction, which was blocked by D-mannose, induced cell activation, as manifested by increased mitochondrial activity, interleukin-2 production, and cell proliferation. We verified that a 30-times higher concentration of rArtinM was required to trigger optimal activation of spleen cells compared with that needed with jArtinM, although these proteins have identical sugar recognition properties and use the same signaling molecules to trigger cell activation. Because the distinction between native and recombinant is restricted to their tertiary structure (tetrameric and monomeric, respectively), we postulated that the multi-valence of jArtinM accounts for its superiority in promoting clustering of cell surface glycoreceptors and activation. The jArtinM and rArtinM activation effect exerted on spleen cells was reproduced on purified CD4(+) T cells. Our results suggest that ArtinM interaction with T cells leads to responses that may act in concert with the interleukin-12 produced by antigen-presenting cells to modulate immunity toward the T helper 1 axis. Further studies are necessary to dissect ArtinM/T-cell interactions to more fully understand the immunomodulation induced by carbohydrate recognition.
Assuntos
Fatores Imunológicos/farmacologia , Lectinas de Ligação a Manose/farmacologia , Baço/citologia , Animais , Artocarpus/química , Complexo CD3/metabolismo , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/metabolismo , Metabolismo dos Carboidratos/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Interleucina-2/biossíntese , Ativação Linfocitária/efeitos dos fármacos , Masculino , Lectinas de Ligação a Manose/metabolismo , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Ligação Proteica/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Receptor 2 Toll-Like/metabolismo , Receptor 4 Toll-Like/metabolismoRESUMO
Lectin from the seeds of Dioclea lasiophylla (DlyL) was purified in a single step by affinity chromatography on a Sephadex® G-50 column. DlyL strongly agglutinated rabbit erythrocytes and was inhibited by monosaccharides (D-mannose and α-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). Similar to other Diocleinae lectins, DlyL has three chains, α, ß and γ, with mass of 25,569 ± 2, 12,998 ± 1 and 12,588 ± 1 Da, respectively, and has no disulfide bonds. The hemagglutinating activity of DlyL was optimal in pH 8.0, stable at a temperature of 70 °C and decreased in EDTA solution, indicating that lectin activity is dependent on divalent metals. DlyL exhibited low toxicity on Artemia sp. nauplii, but this effect was dependent on the concentration of lectin in solution. DlyL immobilized on cyanogen bromide-activated Sepharose® 4B bound 0.917 mg of ovalbumin per cycle, showing the ability to become a tool for glycoproteomics studies.
Assuntos
Dioclea/química , Hemaglutininas/farmacologia , Lectinas de Ligação a Manose/farmacologia , Extratos Vegetais/farmacologia , Sementes/química , Animais , Artemia , Quelantes/química , Cromatografia de Afinidade , Ácido Edético/química , Eritrócitos/efeitos dos fármacos , Hemaglutinação , Hemaglutininas/química , Hemaglutininas/isolamento & purificação , Concentração de Íons de Hidrogênio , Dose Letal Mediana , Lectinas de Ligação a Manose/química , Lectinas de Ligação a Manose/isolamento & purificação , Ovalbumina/química , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Ligação Proteica , Coelhos , Sefarose/químicaRESUMO
ArtinM, a D-mannose-binding lectin from Artocarpus heterophyllus (jackfruit), interacts with N-glycosylated receptors on the surface of several cells of hematopoietic origin, triggering cell migration, degranulation, and cytokine release. Because malignant transformation is often associated with altered expression of cell surface glycans, we evaluated the interaction of ArtinM with human myelocytic leukemia cells and investigated cellular responses to lectin binding. The intensity of ArtinM binding varied across 3 leukemia cell lines: NB4>K562>U937. The binding, which was directly related to cell growth suppression, was inhibited in the presence of Manα1-3(Manα1-6)Manß1, and was reverted in underglycosylated NB4 cells. ArtinM interaction with NB4 cells induced cell death (IC(50)â=â10 µg/mL), as indicated by cell surface exposure of phosphatidylserine and disruption of mitochondrial membrane potential unassociated with caspase activation or DNA fragmentation. Moreover, ArtinM treatment of NB4 cells strongly induced reactive oxygen species generation and autophagy, as indicated by the detection of acidic vesicular organelles in the treated cells. NB4 cell death was attributed to ArtinM recognition of the trimannosyl core of N-glycans containing a ß1,6-GlcNAc branch linked to α1,6-mannose. This modification correlated with higher levels of N-acetylglucosaminyltransferase V transcripts in NB4 cells than in K562 or U937 cells. Our results provide new insights into the potential of N-glycans containing a ß1,6-GlcNAc branch linked to α1,6-mannose as a novel target for anti-leukemia treatment.
Assuntos
Leucemia Mieloide/patologia , Lectinas de Ligação a Manose/metabolismo , Polissacarídeos/metabolismo , Caspases/metabolismo , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Leucemia Mieloide/enzimologia , Lectinas de Ligação a Manose/farmacologia , Modelos Biológicos , Espécies Reativas de Oxigênio/metabolismoRESUMO
ArtinM and Jacalin (JAC) are lectins from the jackfruit (Artocarpus integrifolia) that have important role in modulation of immune responses to pathogens. Neospora caninum is an Apicomplexa parasite that causes neuromuscular disease in dogs and reproductive disorders in cattle, with economic impact on the livestock industry. Hence, we evaluated the adjuvant effect of ArtinM and JAC in immunization of mice against neosporosis. Six C57BL/6 mouse groups were subcutaneously immunized three times at 2-week intervals with Neospora lysate antigen (NLA) associated with lectins (NLA+ArtinM and NLA+JAC), NLA, ArtinM and JAC alone, and PBS (infection control). Animals were challenged with lethal dose of Nc-1 isolate and evaluated for morbidity, mortality, specific antibody response, cytokine production by spleen cells, brain parasite burden and inflammation. Our results demonstrated that ArtinM was able to increase NLA immunogenicity, inducing the highest levels of specific total IgG and IgG2a/IgG1 ratio, ex vivo Th1 cytokine production, increased survival, the lowest brain parasite burden, along with the highest inflammation scores. In contrast, NLA+JAC immunized group showed intermediate survival, the highest brain parasite burden and the lowest inflammation scores. In conclusion, ArtinM presents stronger immunostimulatory and adjuvant effect than Jacalin in immunization of mice against neosporosis, by inducing a protective Th1-biased pro-inflammatory immune response and higher protection after parasite challenge.
Assuntos
Adjuvantes Imunológicos/farmacologia , Coccidiose/prevenção & controle , Lectinas de Ligação a Manose/farmacologia , Neospora/patogenicidade , Lectinas de Plantas/farmacologia , Animais , Anticorpos Antiprotozoários/sangue , Anticorpos Antiprotozoários/imunologia , Artocarpus/química , Encéfalo/parasitologia , Coccidiose/imunologia , Citocinas/imunologia , Feminino , Imunização , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Lectinas de Ligação a Manose/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Carga Parasitária , Lectinas de Plantas/imunologia , Baço/citologia , Baço/imunologiaRESUMO
The D-mannose binding lectin ArtinM from Artocarpus integrifolia, previously known as KM+ and artocarpin, is considered a stimulant of Th1-type immunity, which is able to confer resistance to some intracellular pathogens. In addition, ArtinM induces neutrophil migration by haptotaxis through simultaneous interactions of its carbohydrate recognition domains (CRDs) with glycans expressed on the extracellular matrix and the neutrophil surface. In the present study, we have expanded the characterization of ArtinM as a neutrophil activator. Exposure of neutrophils to ArtinM for 15 min resulted in tyrosine phosphorylation of intracellular proteins, a process that was selectively inhibited by d-mannose or mannotriose. Shortly after stimulation, neutrophils secreted high levels of LTB(4) and underwent shedding of L-selectin from their surface. Exposure to ArtinM enhanced neutrophil functions, such as respiratory burst and zymozan and Listeria monocytogenes phagocytosis. In addition, ArtinM-stimulated neutrophils displayed increased CXCL-8 secretion and TLR2 gene transcription. These results demonstrate that ArtinM is able to induce potent neutrophil activation, a feature that should be strongly considered in the assessment of the lectin capacity to confer resistance against infections.
Assuntos
Movimento Celular , Lectinas de Ligação a Manose/farmacologia , Ativação de Neutrófilo , Neutrófilos/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Humanos , Interleucina-8/biossíntese , Interleucina-8/imunologia , Interleucina-8/farmacologia , Selectina L/efeitos dos fármacos , Selectina L/imunologia , Selectina L/metabolismo , Leucotrieno B4/biossíntese , Leucotrieno B4/imunologia , Neutrófilos/imunologia , Fagocitose/imunologia , Receptor 2 Toll-Like/efeitos dos fármacos , Receptor 2 Toll-Like/imunologia , Receptor 2 Toll-Like/metabolismoRESUMO
Neutrophil influx is essential for corneal regeneration (Gan et al. 1999). KM+, a lectin from Artocarpus integrifolia, induces neutrophil migration (Santos-de-Oliveira et al. 1994). This study aims at investigating a possible effect of KM+ on corneal regeneration in rabbits. A 6.0-mm diameter area of debridement was created on the cornea of both eyes by mechanical scraping. The experimental eyes received drops of KM+ (2.5 microg/ml) every 2 h. The control eyes received buffer. The epithelial wounded areas of the lectin-treated and untreated eyes were stained with fluorescein, photographed and measured. The animals were killed 12 h (group 1, n = 5), 24 h (group 2, n = 10) and 48 h (group 3, n = 5) after the scraping. The corneas were analysed histologically (haematoxylin and eosin and immunostaining for proliferation cell nuclear antigen, p63, vascular endothelial growth factor, c-Met and laminin). No significant differences were found at the epithelial gap between treated and control eyes in the group 1. However, the number of neutrophils in the wounded area was significantly higher in treated eyes in this group. Three control and seven treated eyes were healed completely and only rare neutrophils persisted in the corneal stroma in group 2. No morphological distinction was observed between treated and control eyes in group 3. In treated corneas of group 2, there was an increase in immunostaining of factors involved in corneal healing compared to controls. Thus, topical application of KM+ may facilitate corneal epithelial wound healing in rabbits by means of a mechanism that involves increased influx of neutrophils into the wounded area induced by the lectin.
Assuntos
Epitélio Corneano/lesões , Lectinas de Ligação a Manose/farmacologia , Lectinas de Plantas/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Avaliação Pré-Clínica de Medicamentos/métodos , Epitélio Corneano/efeitos dos fármacos , Epitélio Corneano/patologia , Masculino , Infiltração de Neutrófilos/efeitos dos fármacos , Coelhos , Cicatrização/fisiologiaRESUMO
A single membrane-bound aminopeptidase N (APN) occurs in the pea aphid (Acyrthosiphon pisum Harris) midgut, with a pH optimum of 7.0, pI of 8.1 and molecular mass of 130 kDa. This enzyme accounts for more than 15.6% of the total gut proteins. After being solubilized in detergent, APN was purified to homogeneity. The enzyme is a glycoprotein rich in mannose residues, which binds the entomotoxic lectins of the concanavalin family. The internal sequence of APN is homologous with a conservative domain in APNs, and degenerated primers of highly conserved APN motifs were used to screen a gut cDNA library. The complete sequence of APN has standard residues involved in zinc co-ordination and catalysis and a glycosyl-phosphatidylinositol anchor, as in APNs from Lepidoptera. APN has a broad specificity towards N-terminal amino acids, but does not hydrolyze acidic aminoacyl-peptides, thus resembling the mammalian enzyme (EC 3.4.11.2). The kcat/Km ratios for different di-, tri-, tetra-, and penta-peptides suggest a preference for tripeptides, and that subsites S1, S2' and S3' are pockets able to bind bulky aminoacyl residues. Bestatin and amastatin bound APN in a rapidly reversible mode, with Ki values of 1.8 microM and 0.6 microM, respectively. EDTA inactivates this APN (k(obs) 0.14 M(-1) x s(-1), reaction order of 0.44) at a rate that is reduced by competitive inhibitors. In addition to oligopeptide digestion, APN is proposed to be associated with amino-acid-absorption processes which, in contrast with aminopeptidase activity, may be hampered on lectin binding.
Assuntos
Aminopeptidases/isolamento & purificação , Aminopeptidases/metabolismo , Afídeos/enzimologia , Sistema Digestório/enzimologia , Lectinas de Ligação a Manose/metabolismo , Sequência de Aminoácidos , Aminopeptidases/genética , Animais , Afídeos/citologia , Sequência de Bases , Sítios de Ligação , Ligação Competitiva , DNA Complementar/biossíntese , DNA Complementar/genética , Cinética , Lepidópteros/enzimologia , Lectinas de Ligação a Manose/farmacologia , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência , Especificidade por SubstratoRESUMO
The lectin KM+ from Artocarpus integrifolia, also known as artocarpin, induces neutrophil migration by haptotaxis. The interactions of KM+ with both neutrophils and the extracellular matrix depend on the lectin's ability to recognize mannose-containing glycans. In the present study, we characterized the binding of KM+ to human neutrophils and the responses stimulated by this binding. Exposure to KM+ results in cell polarization, formation of a lamellipodium, and induction of deep ruffles on the cell surface. By fluorescence microscopy, we observed that KM+ is distributed homogeneously over the cell surface. KM+/ligand complexes are rapidly internalized, reaching maximum intracellular concentrations at 120 min, and decreasing thereafter. Furthermore, KM+ binding to the surface of human neutrophils is inhibited by the specific sugars, d-mannose or mannotriose. KM+-induced neutrophil migration is inhibited by pertussis toxin as well as by inhibition of CXCR2 activity. These results suggest that the KM+ ligand on the neutrophil surface is a G protein-coupled receptor (GPCR). The results also suggest that neutrophil migration induced by KM+ involves binding to CXCR2.
Assuntos
Lectinas de Ligação a Manose/farmacologia , Ativação de Neutrófilo/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Receptores de Interleucina-8B/metabolismo , Membrana Celular , Movimento Celular/efeitos dos fármacos , Polaridade Celular , Humanos , Ligantes , Lectinas de Ligação a Manose/metabolismo , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Neutrófilos/ultraestrutura , Lectinas de Plantas/metabolismo , Pseudópodes , Receptores Acoplados a Proteínas GRESUMO
The lectin KM+ from Artocarpus integrifolia, also known as artocarpin, induces neutrophil migration by haptotaxis. The interactions of KM+ with both the extracellular matrix (ECM) and neutrophils depend on the lectin ability to recognize mannose-containing glycans. Here, we report the binding of KM+ to laminin and demonstrate that this interaction potentiates the KM+-induced neutrophil migration. Labeling of lung tissue by KM+ located its ligands on the endothelial cells, in the basement membrane, in the alveolus, and in the interstitial connective tissue. Such labeling was inhibited by 400 mM D-mannose, 10 mM Manalpha1-3[Manalpha1-6]Man or 10 microM peroxidase (a glycoprotein-containing mannosyl heptasaccharide). Laminin is a tissue ligand for KM+, since both KM+ and anti-laminin antibodies not only reacted with the same high molecular mass components of a lung extract, but also determined colocalized labeling in basement membranes of the lung tissue. The relevance of the KM+-laminin interaction to the KM+ property of inducing neutrophil migration was evaluated. The inability of low concentrations of soluble KM+ to induce human neutrophil migration was reversed by coating the microchamber filter with laminin. So, the interaction of KM+ with laminin promotes the formation of a substrate-bound KM+ gradient that is able to induce neutrophil haptotaxis.
Assuntos
Quimiotaxia de Leucócito/efeitos dos fármacos , Laminina/metabolismo , Lectinas de Ligação a Manose/farmacologia , Neutrófilos/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Animais , Membrana Basal/metabolismo , Sítios de Ligação , Humanos , Ligantes , Pulmão/metabolismo , Lectinas de Ligação a Manose/metabolismo , Neutrófilos/imunologia , Lectinas de Plantas/metabolismo , Ratos , Ratos WistarRESUMO
The mammalian lectin macrophage-derived neutrophil chemotactic factor (MNCF) and the plant lectin KM+ were characterized for their ability to activate and degranulate mast cells. The association between mast cell activation and the induction of neutrophil migration was also investigated. Incubation of rat peritoneal mast cells with these lectins resulted in degranulation and mediator release. By confocal microscopy, both lectins were evenly distributed on the cell surface. MNCF activated RBL-2H3 mast cells only if the cells had been sensitized with IgE. KM+ was able to activate either unsensitized or IgE sensitized RBL-2H3 cells. In microplate assays MNCF, but not KM+, bound to rat IgE. In rats that were depleted of mast cells, neutrophil recruitment by MNCF and KM+ were significantly reduced indicating that mast cell activation provides an amplification loop for the neutrophil recruitment induced by these lectins. The present study supports the concept that mammalian lectins play a fundamental role in innate immunity.
Assuntos
Degranulação Celular/efeitos dos fármacos , Interleucina-8/farmacologia , Lectinas/farmacologia , Lectinas de Ligação a Manose/farmacologia , Mastócitos/fisiologia , Neutrófilos/fisiologia , Animais , Imunidade Inata , Interleucina-8/metabolismo , Lectinas de Ligação a Manose/metabolismo , Mastócitos/ultraestrutura , Ratos , Ratos WistarRESUMO
The effects of the snowdrop lectin, Galanthus nivalis agglutinin (GNA), delivered through an artificial diet, on growth, development, and life history parameters of the Mexican rice borer, Eoreuma loftini (Dyar), were evaluated in the laboratory. Incorporation of GNA at three treatment levels, 0.5, 1.0, and 2.0% of total dietary protein, in the larval diet significantly decreased larval survivorship and percentage of adults emerging relative to a control diet lacking GNA, whereas differences were not observed among the three treatment levels. Both larvae and pupae in the control were 8-25% larger than those in the GNA treatments, but differences were not observed between larvae in the GNA treatments. Furthermore, presence of GNA did not affect larval and pupal developmental periods, longevities, and fecundities compared with the control. Mexican rice borer life history parameters, such as net reproductive rate and intrinsic rate of increase, were substantially reduced by the presence of GNA in the diet, but differences were not evident among the three GNA treatment levels.