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1.
J Pharmacol Exp Ther ; 367(3): 494-508, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30305428

RESUMO

Monoacylglycerol lipase (MGLL) is the primary degradative enzyme for the endocannabinoid 2-arachidonoylglycerol (2-AG). The first MGLL inhibitors have recently entered clinical development for the treatment of neurologic disorders. To support this clinical path, we report the pharmacological characterization of the highly potent and selective MGLL inhibitor ABD-1970 [1,1,1,3,3,3-hexafluoropropan-2-yl 4-(2-(8-oxa-3-azabicyclo[3.2.1]octan-3-yl)-4-chlorobenzyl)piperazine-1-carboxylate]. We used ABD-1970 to confirm the role of MGLL in human systems and to define the relationship between MGLL target engagement, brain 2-AG concentrations, and efficacy. Because MGLL contributes to arachidonic acid metabolism in a subset of rodent tissues, we further used ABD-1970 to evaluate whether selective MGLL inhibition would affect prostanoid production in several human assays known to be sensitive to cyclooxygenase inhibitors. ABD-1970 robustly elevated brain 2-AG content and displayed antinociceptive and antipruritic activity in a battery of rodent models (ED50 values of 1-2 mg/kg). The antinociceptive effects of ABD-1970 were potentiated when combined with analgesic standards of care and occurred without overt cannabimimetic effects. ABD-1970 also blocked 2-AG hydrolysis in human brain tissue and elevated 2-AG content in human blood without affecting stimulated prostanoid production. These findings support the clinical development of MGLL inhibitors as a differentiated mechanism to treat pain and other neurologic disorders.


Assuntos
Endocanabinoides/metabolismo , Inibidores Enzimáticos/farmacologia , Monoacilglicerol Lipases/antagonistas & inibidores , Analgésicos/farmacologia , Animais , Antipruriginosos/farmacologia , Ácidos Araquidônicos/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Linhagem Celular Tumoral , Inibidores de Ciclo-Oxigenase/farmacologia , Glicerídeos/metabolismo , Humanos , Hidrólise/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Células PC-3 , Dor/tratamento farmacológico , Dor/metabolismo , Piperidinas/farmacologia , Prostaglandinas/farmacologia , Ratos , Ratos Sprague-Dawley , Roedores
2.
J Med Chem ; 61(20): 9062-9084, 2018 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-30067909

RESUMO

The serine hydrolase monoacylglycerol lipase (MGLL) converts the endogenous cannabinoid receptor agonist 2-arachidonoylglycerol (2-AG) and other monoacylglycerols into fatty acids and glycerol. Genetic or pharmacological inactivation of MGLL leads to elevation in 2-AG in the central nervous system and corresponding reductions in arachidonic acid and eicosanoids, producing antinociceptive, anxiolytic, and antineuroinflammatory effects without inducing the full spectrum of psychoactive effects of direct cannabinoid receptor agonists. Here, we report the optimization of hexafluoroisopropyl carbamate-based irreversible inhibitors of MGLL, culminating in a highly potent, selective, and orally available, CNS-penetrant MGLL inhibitor, 28 (ABX-1431). Activity-based protein profiling experiments verify the exquisite selectivity of 28 for MGLL versus other members of the serine hydrolase class. In vivo, 28 inhibits MGLL activity in rodent brain (ED50 = 0.5-1.4 mg/kg), increases brain 2-AG concentrations, and suppresses pain behavior in the rat formalin pain model. ABX-1431 (28) is currently under evaluation in human clinical trials.


Assuntos
Descoberta de Drogas , Monoacilglicerol Lipases/antagonistas & inibidores , Doenças do Sistema Nervoso/tratamento farmacológico , Doenças do Sistema Nervoso/enzimologia , Piperazina/farmacologia , Piperazinas/farmacologia , Pirrolidinas/farmacologia , Animais , Cães , Relação Dose-Resposta a Droga , Humanos , Masculino , Camundongos , Terapia de Alvo Molecular , Dor/tratamento farmacológico , Dor/enzimologia , Piperazina/farmacocinética , Piperazina/uso terapêutico , Piperazinas/farmacocinética , Piperazinas/uso terapêutico , Pirrolidinas/farmacocinética , Pirrolidinas/uso terapêutico , Ratos , Distribuição Tecidual
3.
PLoS One ; 9(12): e114521, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25474204

RESUMO

Genetic alterations or pharmacological treatments affecting endocannabinoid signaling have profound effects on synaptic and neuronal properties and, under certain conditions, may improve higher brain functions. Down syndrome (DS), a developmental disorder caused by triplication of chromosome 21, is characterized by deficient cognition and inevitable development of the Alzheimer disease (AD) type pathology during aging. Here we used JZL184, a selective inhibitor of monoacylglycerol lipase (MAGL), to examine the effects of chronic MAGL inhibition on the behavioral, biochemical, and synaptic properties of aged Ts65Dn mice, a genetic model of DS. In both Ts65Dn mice and their normosomic (2N) controls, JZL184-treatment increased brain levels of 2-arachidonoylglycerol (2-AG) and decreased levels of its metabolites such as arachidonic acid, prostaglandins PGD2, PGE2, PGFα, and PGJ2. Enhanced spontaneous locomotor activity of Ts65Dn mice was reduced by the JZL184-treatement to the levels observed in 2N animals. Deficient long-term memory was also improved, while short-term and working types of memory were unaffected. Furthermore, reduced hippocampal long-term potentiation (LTP) was increased in the JZL184-treated Ts65Dn mice to the levels observed in 2N mice. Interestingly, changes in synaptic plasticity and behavior were not observed in the JZL184-treated 2N mice suggesting that the treatment specifically attenuated the defects in the trisomic animals. The JZL184-treatment also reduced the levels of Aß40 and Aß42, but had no effect on the levels of full length APP and BACE1 in both Ts65Dn and 2N mice. These data show that chronic MAGL inhibition improves the behavior and brain functions in a DS model suggesting that pharmacological targeting of MAGL may be considered as a perspective new approach for improving cognition in DS.


Assuntos
Ansiolíticos/uso terapêutico , Benzodioxóis/uso terapêutico , Síndrome de Down/tratamento farmacológico , Piperidinas/uso terapêutico , Animais , Ansiolíticos/farmacologia , Benzodioxóis/farmacologia , Região CA1 Hipocampal/efeitos dos fármacos , Região CA1 Hipocampal/metabolismo , Modelos Animais de Doenças , Síndrome de Down/psicologia , Avaliação Pré-Clínica de Medicamentos , Endocanabinoides/metabolismo , Masculino , Aprendizagem em Labirinto , Memória de Curto Prazo/efeitos dos fármacos , Camundongos Transgênicos , Monoacilglicerol Lipases/antagonistas & inibidores , Monoacilglicerol Lipases/metabolismo , Atividade Motora/efeitos dos fármacos , Piperidinas/farmacologia , Reconhecimento Psicológico
4.
PLoS One ; 7(11): e47835, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23139754

RESUMO

Mannose-binding lectin (MBL) is a humoral pattern-recognition molecule important for host defense. Although recent genetic studies suggest an involvement of MBL/MASP2-associated pathways in Chagas' disease, it is currently unknown whether MBL plays a role in host resistance to the intracellular protozoan Trypanosoma cruzi, the causative agent of Chagas' disease. In this study we employed MBL(-/-) mice to assess the role of MBL in resistance to experimental infection with T. cruzi. T. cruzi infection enhanced tissue expression of MBL both at the mRNA and protein level. Similarly, symptomatic acute Chagas' disease patients displayed increased serum concentrations of MBL compared to patients with indeterminate, asymptomatic forms of the disease. Furthermore, increased parasite loads in the blood and/or tissue were observed in MBL(-/-) mice compared to WT controls. This was associated with reduced systemic levels of IL-12/23p40 in MBL(-/-) mice. Importantly, MBL(-/-) mice infected with a cardiotropic strain of T. cruzi displayed increased myocarditis and cardiac fibrosis compared to WT controls. The latter was accompanied by elevated hydroxyproline content and mRNA levels of collagen-1 and -6 in the heart. These observations point to a previously unappreciated role for MBL in regulating host resistance and cardiac inflammation during infection with a major human pathogen.


Assuntos
Doença de Chagas/patologia , Doença de Chagas/parasitologia , Resistência à Doença/imunologia , Interações Hospedeiro-Parasita/imunologia , Lectina de Ligação a Manose/metabolismo , Trypanosoma cruzi/fisiologia , Animais , Cardiomiopatias/sangue , Cardiomiopatias/parasitologia , Cardiomiopatias/patologia , Doença de Chagas/sangue , Fibrose , Humanos , Subunidade p40 da Interleucina-12/biossíntese , Lectina de Ligação a Manose/sangue , Lectina de Ligação a Manose/deficiência , Camundongos , Miocárdio/patologia , Carga Parasitária
5.
J Infect Dis ; 203(2): 175-9, 2011 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-21288816

RESUMO

Mannose-binding lectin (MBL) targets diverse microorganisms for phagocytosis and complement-mediated lysis by binding specific surface glycans. Although recombinant human MBL (rhMBL) trials have focused on reconstitution therapy, safety studies have identified no barriers to its use at higher levels. Ebola viruses cause fatal hemorrhagic fevers for which no treatment exists and that are feared as potential biothreat agents. We found that mice whose rhMBL serum concentrations were increased ≥7-fold above average human levels survived otherwise fatal Ebola virus infections and became immune to virus rechallenge. Because Ebola glycoproteins potentially model other glycosylated viruses, rhMBL may offer a novel broad-spectrum antiviral approach.


Assuntos
Ebolavirus/imunologia , Ebolavirus/patogenicidade , Doença pelo Vírus Ebola/tratamento farmacológico , Doença pelo Vírus Ebola/patologia , Fatores Imunológicos/administração & dosagem , Lectina de Ligação a Manose/administração & dosagem , Animais , Antivirais/administração & dosagem , Humanos , Camundongos , Camundongos Knockout , Proteínas Recombinantes/administração & dosagem , Análise de Sobrevida , Resultado do Tratamento
6.
J Biol Chem ; 285(32): 24729-39, 2010 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-20516066

RESUMO

Ebola viruses constitute a newly emerging public threat because they cause rapidly fatal hemorrhagic fevers for which no treatment exists, and they can be manipulated as bioweapons. We targeted conserved N-glycosylated carbohydrate ligands on viral envelope surfaces using novel immune therapies. Mannose-binding lectin (MBL) and L-ficolin (L-FCN) were selected because they function as opsonins and activate complement. Given that MBL has a complex quaternary structure unsuitable for large scale cost-effective production, we sought to develop a less complex chimeric fusion protein with similar ligand recognition and enhanced effector functions. We tested recombinant human MBL and three L-FCN/MBL variants that contained the MBL carbohydrate recognition domain and varying lengths of the L-FCN collagenous domain. Non-reduced chimeric proteins formed predominantly nona- and dodecameric oligomers, whereas recombinant human MBL formed octadecameric and larger oligomers. Surface plasmon resonance revealed that L-FCN/MBL76 had the highest binding affinities for N-acetylglucosamine-bovine serum albumin and mannan. The same chimeric protein displayed superior complement C4 cleavage and binding to calreticulin (cC1qR), a putative receptor for MBL. L-FCN/MBL76 reduced infection by wild type Ebola virus Zaire significantly greater than the other molecules. Tapping mode atomic force microscopy revealed that L-FCN/MBL76 was significantly less tall than the other molecules despite similar polypeptide lengths. We propose that alterations in the quaternary structure of L-FCN/MBL76 resulted in greater flexibility in the collagenous or neck region. Similarly, a more pliable molecule might enhance cooperativity between the carbohydrate recognition domains and their cognate ligands, complement activation, and calreticulin binding dynamics. L-FCN/MBL chimeric proteins should be considered as potential novel therapeutics.


Assuntos
Antivirais/farmacologia , Ebolavirus/metabolismo , Lectinas/química , Lectina de Ligação a Manose/química , Calreticulina/química , Linhagem Celular Tumoral , Química Farmacêutica/métodos , Proteínas do Sistema Complemento/química , Desenho de Fármacos , Humanos , Cinética , Microscopia de Força Atômica/métodos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes/química , Ressonância de Plasmônio de Superfície/métodos , Ficolinas
7.
Clin Immunol ; 130(3): 264-71, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18996748

RESUMO

Mannose-binding lectin (MBL), a pattern recognition innate immune molecule, selectively binds distinct chemical patterns, including carbohydrates expressed on Group B streptococcus (GBS). MBL interacts with IgM, resulting in the activation of MBL-associated serine proteases (MASPs), thus is initiating a lectin complement pathway. Complement proteins and IgM modulate production of antigen specific antibody. In this study, we investigated the relative effect of MBL in antibody response against tetanus toxoid-conjugated GBS polysaccharide vaccines (GBS PS-TT) by comparing wild type and null mice for MBL, complement 3 (C3), IgM, MBL/C3, and MBL/IgM. We found that GBS PS specific IgG response was upregulated in MBL deficient mice following immunization with GBS PS-TT but not GBS PS. B1 cells were expanded in peritonium but not in spleen of MBL null mice. The mechanisms of heightened IgG response in MBL null mice were related to C3, and share the same pathway with IgM.


Assuntos
Formação de Anticorpos , Lectina de Ligação a Manose/deficiência , Lectina de Ligação a Manose/imunologia , Animais , Linfócitos B/imunologia , Modelos Animais de Doenças , Feminino , Imunização , Imunoglobulina G/metabolismo , Camundongos , Modelos Imunológicos , Regulação para Cima
8.
J Exp Med ; 205(1): 169-81, 2008 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-18180310

RESUMO

Innate immunity is the first-line defense against pathogens and relies on phagocytes, soluble components, and cell-surface and cytosolic pattern recognition receptors. Despite using hard-wired receptors and signaling pathways, the innate immune response demonstrates surprising specificity to different pathogens. We determined how combinatorial use of innate immune defense mechanisms defines the response. We describe a novel cooperation between a soluble component of the innate immune system, the mannose-binding lectin, and Toll-like receptor 2 that both specifies and amplifies the host response to Staphylococcus aureus. Furthermore, we demonstrate that this cooperation occurs within the phagosome, emphasizing the importance of engulfment in providing the appropriate cellular environment to facilitate the synergy between these defense pathways.


Assuntos
Lectina de Ligação a Manose/metabolismo , Fagossomos/metabolismo , Staphylococcus aureus/metabolismo , Receptor 2 Toll-Like/metabolismo , Receptor 6 Toll-Like/metabolismo , Animais , Linhagem Celular , Ativação do Complemento , Evolução Molecular , Humanos , Sistema Imunitário , Imunidade Inata , Camundongos , Camundongos Endogâmicos C57BL , Modelos Biológicos , Análise Serial de Proteínas
9.
J Cereb Blood Flow Metab ; 27(12): 1954-64, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17457366

RESUMO

Complement component C4 mediates C3-dependent tissue damage after systemic ischemia-reperfusion injury. Activation of C3 also contributes to the pathogenesis of experimental and human traumatic brain injury (TBI); however, few data exist regarding the specific pathways (classic, alternative, and lectin) involved. Using complement knockout mice and a controlled cortical impact (CCI) model, we tested the hypothesis that the classic pathway mediates secondary damage after TBI. After CCI, C4c and C3d immunostaining were detected in cortical vascular endothelial cells in wild-type (WT) mice; however, C4c and C3d immunostaining were also detected in C1q(-/-) mice, and C3d immunostaining was detected in C4(-/-) mice. After CCI, WT and C1q(-/-) mice had similar motor deficits, Morris water maze performance, and brain lesion size. Naive C4(-/-) and WT mice did not differ in baseline motor performance, but C4(-/-) mice had reduced postinjury motor deficits (days 1 to 7, P<0.05) and decreased brain tissue damage (days 14 and 35, P<0.05) versus WT. Reconstitution of C4(-/-) mice with human C4 (hC4) reversed their protection against postinjury motor deficits (P<0.05 versus vehicle), but administration of hC4 did not impair postinjury motor performance (versus vehicle) in WT mice. The protective effects of C4(-/-) were functionally distinct from the classic pathway and terminal complement, as C1q(-/-) and C3(-/-) mice had postinjury tissue damage and motor dysfunction similar to WT. Thus, C4 contributes to motor deficits and brain tissue damage after CCI by mechanism(s) fundamentally different from those involved in experimental systemic ischemia-reperfusion injury.


Assuntos
Lesões Encefálicas/patologia , Lesões Encefálicas/fisiopatologia , Complemento C4/fisiologia , Movimento/fisiologia , Animais , Pressão Sanguínea/fisiologia , Edema Encefálico/genética , Edema Encefálico/patologia , Lesões Encefálicas/psicologia , Complemento C4/deficiência , Complemento C4/farmacologia , Humanos , Imuno-Histoquímica , Inflamação/patologia , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Knockout , Desempenho Psicomotor/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa
10.
J Immunol ; 177(7): 4727-34, 2006 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-16982912

RESUMO

Reperfusion of ischemic tissues elicits an acute inflammatory response involving serum complement, which is activated by circulating natural IgM specific to self-Ags exposed by ischemia. Recent reports demonstrating a role for the lectin pathway raise a question regarding the initial events in complement activation. To dissect the individual roles of natural IgM and lectin in activation of complement, mice bearing genetic deficiency in early complement, IgM, or mannan-binding lectin were characterized in a mesenteric model of ischemia reperfusion injury. The results reveal that IgM binds initially to ischemic Ag providing a binding site for mannan-binding lectin which subsequently leads to activation of complement and injury.


Assuntos
Lectina de Ligação a Manose da Via do Complemento/imunologia , Imunoglobulina M/metabolismo , Lectina de Ligação a Manose/metabolismo , Traumatismo por Reperfusão/imunologia , Sequência de Aminoácidos , Animais , Complexo Antígeno-Anticorpo , Autoantígenos/genética , Autoantígenos/imunologia , Modelos Animais de Doenças , Imunoglobulina M/imunologia , Imuno-Histoquímica , Imunoprecipitação , Inflamação/imunologia , Inflamação/patologia , Lectina de Ligação a Manose/imunologia , Espectrometria de Massas , Mesentério/irrigação sanguínea , Mesentério/metabolismo , Mesentério/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , Cadeias Pesadas de Miosina/genética , Cadeias Pesadas de Miosina/imunologia , Miosina Tipo II/genética , Miosina Tipo II/imunologia , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia
11.
Int Arch Allergy Immunol ; 141(1): 11-23, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16804320

RESUMO

BACKGROUND: Systemic anaphylaxis is the most severe form of immediate hypersensitivity reaction. The activation of the complement system occurs during anaphylactic shock. The purpose of this study was to determine in a mouse model whether the lectin pathway of complement activation is involved in anaphylaxis. METHODS: To see whether the lectin pathway is involved in anaphylactic shock, serum mannan-binding lectin (MBL) levels were measured after passive anaphylaxis. Also MBL expression and binding to potential ligands were investigated. To determine whether complement or mast cell activation is essential for hypothermia in anaphylactic shock, mouse strains deficient in MBL-A and MBL-C, C1q, factors B and C2, C5, C5aR, or mast cells were tested. RESULTS: After antigenic challenge a marked drop in body temperature as well as a rapid decrease in serum MBL levels were observed. The decrease of serum MBL levels in shock could not be attributed to MBL binding to immune complexes or tissues, but an interaction of MBL with mast cell-derived proteoglycans was seen. In contrast to mast cell-deficient mice, none of the complement-deficient mouse strains were protected from shock-associated hypothermia. CONCLUSIONS: These results indicate that neither MBL nor activation of the complement cascade is crucial for the induction of anaphylaxis. In contrast mast cell activation is associated with the development of hypothermia and possibly the observed decrease in serum MBL levels.


Assuntos
Anafilaxia/imunologia , Ativação do Complemento , Lectina de Ligação a Manose/metabolismo , Anafilaxia/sangue , Anafilaxia/fisiopatologia , Animais , Ensaio de Imunoadsorção Enzimática , Feminino , Hipotermia/etiologia , Hipotermia/fisiopatologia , Imuno-Histoquímica , Lectina de Ligação a Manose/sangue , Mastócitos/imunologia , Camundongos , Camundongos Endogâmicos DBA , Camundongos Mutantes , Ovalbumina/imunologia , Reação em Cadeia da Polimerase , Proteoglicanas/imunologia , RNA Mensageiro/análise
12.
Biochem Biophys Res Commun ; 343(3): 928-36, 2006 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-16574074

RESUMO

The mannose-binding lectin (MBL), a pattern recognition serum protein, participates in the innate immune system of mammals as an opsonin. In humans, MBL plays a key role in first-line host defense against infection during the lag period prior to the development of a specific immune response. MBL also activates complement via the lectin pathway that requires a MBL-associated serine protease-2 (MASP-2). Homologues of human MBL (hMBL) have been identified in a variety of mammals, fish, and primitive animals such as ascidians. In this study, we report that equine MBL (eMBL) has properties that are similar to hMBL. In addition, we found low levels of MBL:MASP activity in sick horses compared to healthy horses. These results suggest that eMBL is involved in the immune response of the horse and that low MBL:MASP activity could be used to monitor immune function and clinical outcome.


Assuntos
Doenças dos Cavalos/imunologia , Lectinas de Ligação a Manose/química , Lectinas de Ligação a Manose/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Feminino , Cavalos , Lectinas de Ligação a Manose/genética , Serina Proteases Associadas a Proteína de Ligação a Manose/metabolismo , Dados de Sequência Molecular , Filogenia , Alinhamento de Sequência
13.
J Immunol ; 176(3): 1769-75, 2006 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-16424207

RESUMO

Burn injury disrupts the mechanical and biological barrier that the skin presents against infection by symbionts like the Pseudomonas aeruginosa, a Gram-negative bacteria. A combination of local factors, antimicrobial peptides, and resident effector cells form the initial response to mechanical injury of the skin. This activity is followed by an inflammatory response that includes influx of phagocytes and serum factors, such as complement and mannose-binding lectin (MBL), which is a broad-spectrum pattern recognition molecule that plays a key role in innate immunity. A growing consensus from studies in humans and mice suggests that lack of MBL together with other comorbid factors predisposes the host to infection. In this study we examined whether MBL deficiency increases the risk of P. aeruginosa infection in a burned host. We found that both wild-type and MBL null mice were resistant to a 5% total body surface area burn alone or s.c. infection with P. aeruginosa alone. However, when mice were burned then inoculated s.c. with P. aeruginosa at the burn site, all MBL null mice died by 42 h from septicemia, whereas only one-third of wild-type mice succumbed (p = 0.0005). This result indicates that MBL plays a key role in containing and preventing a systemic spread of P. aeruginosa infection following burn injury and suggests that MBL deficiency in humans maybe a premorbid variable in the predisposition to infection in burn victims.


Assuntos
Queimaduras/microbiologia , Lectina de Ligação a Manose/deficiência , Infecções por Pseudomonas , Animais , Queimaduras/sangue , Queimaduras/genética , Modelos Animais de Doenças , Inflamação/metabolismo , Interleucina-6/sangue , Camundongos , Camundongos Knockout , Especificidade de Órgãos/genética , Especificidade de Órgãos/imunologia , Infecções por Pseudomonas/sangue , Pseudomonas aeruginosa , Fatores de Risco , Sepse/microbiologia , Fator de Necrose Tumoral alfa/metabolismo
14.
Curr Opin Immunol ; 18(1): 16-23, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16368230

RESUMO

The innate immune system is comprised of a sophisticated network of recognition and effector molecules that act together to protect the host in the first minutes or hours of exposure to an infectious challenge. The mannose-binding lectin (MBL) is an evolutionary conserved circulating host defense protein that acts as a broad-spectrum recognition molecule against a wide variety of infectious agents. Target binding triggers the MBL pathway of complement activation. MBL can be considered conceptually as an 'ante-antibody' because it has a role in mammals during the lag period that is required to develop an antibody response against infectious agents. Additionally, there are MBL-like homologues in animals that lack adaptive immunity that activate a primitive complement system, and under these circumstances these MBL-like molecules play an analogous role to antibodies in higher animals. These molecules might be considered to be functional antecedents of antibodies. Recent work also indicates that MBL recognizes altered self-antigens, and as such MBL has a role that extends beyond a traditional role in first line host defense as it appears to play a role as a modulator of inflammation.


Assuntos
Imunidade Inata , Lectina de Ligação a Manose/química , Lectina de Ligação a Manose/metabolismo , Animais , Predisposição Genética para Doença , Humanos , Ligantes , Lectina de Ligação a Manose/genética , Especificidade por Substrato
15.
Infect Immun ; 73(12): 8188-93, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16299314

RESUMO

Staphylococcus aureus is a major cause of severe nosocomial and community-acquired infections. Phagocytes and humoral molecules, including complement, have been proposed to cooperate in host defense against gram-positive bacteria. Circumstantial evidence indicates a role for complement, but this has not been formally defined. Complement activation is initiated by the classical, alternative, or lectin pathway, with the latter requiring mannose-binding lectin (MBL, also known as mannose-binding protein). MBL is an oligomeric serum protein that recognizes carbohydrates decorating a broad range of infectious agents, including S. aureus. We previously reported that MBL null mice were highly susceptible to S. aureus infection, confirming that MBL plays a key role in first-line host defense. In this study, we evaluated the relative roles of C3 and MBL against S. aureus infection by generating MBL x C3 null mice to compare with C3 single null mice. C3 deficiency alone significantly reduced survival to 19% from 97% of wild-type mice (P < 0.0001). Surprisingly, an additional MBL deficiency reduced the survival further to 7% (P < 0.0001). However, the MBL deficiency alone had a smaller though significant effect on survival, which was 77% (P = 0.018 versus wild-type mice). These results confirm an essential function for complement in host resistance against S. aureus infection but also identify an MBL-dependent mechanism that is C3 independent.


Assuntos
Complemento C3/fisiologia , Lectina de Ligação a Manose/fisiologia , Infecções Estafilocócicas/imunologia , Animais , Bacteriemia/genética , Bacteriemia/imunologia , Complemento C3/deficiência , Complemento C3/genética , Predisposição Genética para Doença , Inflamação/genética , Inflamação/imunologia , Lectina de Ligação a Manose/deficiência , Lectina de Ligação a Manose/genética , Camundongos , Camundongos Mutantes , Mutação , Infecções Estafilocócicas/genética , Staphylococcus aureus
16.
Clin Infect Dis ; 41 Suppl 7: S440-4, 2005 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-16237644

RESUMO

The innate immune system, which includes mannose-binding lectin (MBL), recognizes a broad range of molecular patterns on a broad range of infectious agents and is able to distinguish them from self. MBL is a liver-derived serum protein and is secreted into the serum, where it can activate an immune response before the induction of antigen-specific immunity. Circumstantial evidence in human populations suggests that low serum levels of MBL predispose to infection. To analyze the role of MBL in vivo, we created MBL-null mice and challenged these mice with infection under various conditions. Our results suggest that MBL plays an important role as a first-line host defense against certain infectious agents. In addition, it is likely that MBL is a key regulator of inflammation beyond expected roles in the infection.


Assuntos
Predisposição Genética para Doença , Imunidade Inata/genética , Lectinas de Ligação a Manose/genética , Lectinas de Ligação a Manose/imunologia , Animais , Doenças Autoimunes/sangue , Infecções Bacterianas/sangue , Infecções Bacterianas/imunologia , Fibrose Cística/sangue , Humanos , Lectinas de Ligação a Manose/sangue , Camundongos , Camundongos Knockout , Polimorfismo de Nucleotídeo Único
17.
Cell ; 123(2): 335-46, 2005 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-16239149

RESUMO

Phagocytosis is a complex, evolutionarily conserved process that plays a central role in host defense against infection. We have identified a predicted transmembrane protein, Eater, which is involved in phagocytosis in Drosophila. Transcriptional silencing of the eater gene in a macrophage cell line led to a significant reduction in the binding and internalization of bacteria. Moreover, the N terminus of the Eater protein mediated direct microbial binding which could be inhibited with scavenger receptor ligands, acetylated, and oxidized low-density lipoprotein. In vivo, eater expression was restricted to blood cells. Flies lacking the eater gene displayed normal responses in NF-kappaB-like Toll and IMD signaling pathways but showed impaired phagocytosis and decreased survival after bacterial infection. Our results suggest that Eater is a major phagocytic receptor for a broad range of bacterial pathogens in Drosophila and provide a powerful model to address the role of phagocytosis in vivo.


Assuntos
Proteínas de Drosophila/fisiologia , Drosophila/microbiologia , Genes de Insetos , Proteínas de Insetos/fisiologia , Proteínas de Membrana/fisiologia , Fagocitose , Receptores de Superfície Celular/fisiologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Infecções Bacterianas/prevenção & controle , Drosophila/citologia , Drosophila/embriologia , Drosophila/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Embrião não Mamífero , Escherichia coli/patogenicidade , Citometria de Fluxo , Mutação da Fase de Leitura , Histidina/química , Hibridização In Situ , Proteínas de Insetos/química , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Macrófagos/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Dados de Sequência Molecular , Fases de Leitura Aberta , Interferência de RNA , RNA Mensageiro/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Homologia de Sequência de Aminoácidos , Serratia marcescens/patogenicidade
18.
J Cell Biol ; 170(3): 477-85, 2005 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-16061696

RESUMO

Phagocyte recognition and clearance of bacteria play essential roles in the host response to infection. In an on-going forward genetic screen, we identify the Drosophila melanogaster scavenger receptor Croquemort as a receptor for Staphylococcus aureus, implicating for the first time the CD36 family as phagocytic receptors for bacteria. In transfection assays, the mammalian Croquemort paralogue CD36 confers binding and internalization of Gram-positive and, to a lesser extent, Gram-negative bacteria. By mutational analysis, we show that internalization of S. aureus and its component lipoteichoic acid requires the COOH-terminal cytoplasmic portion of CD36, specifically Y463 and C464, which activates Toll-like receptor (TLR) 2/6 signaling. Macrophages lacking CD36 demonstrate reduced internalization of S. aureus and its component lipoteichoic acid, accompanied by a marked defect in tumor necrosis factor-alpha and IL-12 production. As a result, Cd36-/- mice fail to efficiently clear S. aureus in vivo resulting in profound bacteraemia. Thus, response to S. aureus requires CD36-mediated phagocytosis triggered by the COOH-terminal cytoplasmic domain, which initiates TLR2/6 signaling.


Assuntos
Antígenos CD36/imunologia , Fagocitose/fisiologia , Staphylococcus aureus/fisiologia , Animais , Bacteriemia/imunologia , Bacteriemia/microbiologia , Antígenos CD36/genética , Antígenos CD36/metabolismo , Células Cultivadas , Citoplasma/metabolismo , Proteínas de Drosophila/genética , Interleucina-12/biossíntese , Lipopolissacarídeos/metabolismo , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/microbiologia , Glicoproteínas de Membrana/fisiologia , Camundongos , Camundongos Knockout , Estrutura Terciária de Proteína , Receptores de Superfície Celular/fisiologia , Receptores Imunológicos/genética , Receptores Depuradores , Transdução de Sinais , Ácidos Teicoicos/metabolismo , Receptor 2 Toll-Like , Receptores Toll-Like , Fator de Necrose Tumoral alfa/biossíntese
19.
J Immunol ; 175(1): 541-6, 2005 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-15972690

RESUMO

The mannose-binding lectin (MBL), a circulating pattern recognition molecule, recognizes a wide range of infectious agents with resultant initiation of the complement cascade in an Ab-independent manner. MBL recognizes infectious non-self and altered self in the guise of apoptotic and necrotic cells. In this study, we demonstrate that mice lacking MBL, and hence are devoid of MBL-dependent lectin pathway activation but have fully active alternative and classical complement pathways, are protected from cardiac reperfusion injury with resultant preservation of cardiac function. Significantly, mice that lack a major component of the classical complement pathway initiation complex (C1q) but have an intact MBL complement pathway, are not protected from injury. These results suggest that the MBL-dependent pathway of complement activation is a key regulator of myocardial reperfusion ischemic injury. MBL is an example of a pattern recognition molecule that plays a dual role in modifying inflammatory responses to sterile and infectious injury.


Assuntos
Mediadores da Inflamação/metabolismo , Inflamação/etiologia , Inflamação/imunologia , Lectina de Ligação a Manose/metabolismo , Traumatismo por Reperfusão Miocárdica/etiologia , Traumatismo por Reperfusão Miocárdica/imunologia , Animais , Complemento C1q/deficiência , Complemento C1q/genética , Complemento C2/deficiência , Complemento C2/genética , Fator B do Complemento/deficiência , Fator B do Complemento/genética , Fator D do Complemento/deficiência , Fator D do Complemento/genética , Via Alternativa do Complemento , Via Clássica do Complemento , Lectina de Ligação a Manose da Via do Complemento , Masculino , Lectina de Ligação a Manose/deficiência , Lectina de Ligação a Manose/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Traumatismo por Reperfusão Miocárdica/prevenção & controle
20.
Blood ; 106(7): 2551-8, 2005 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-15956276

RESUMO

Innate immune responses to bacteria require cooperative interactions between host recognition molecules and phagocytes. The peptidoglycan recognition proteins (PGRPs) are a large group of proteins found in insects and mammals that bind to bacterial peptidoglycan (PGN). PGRP-S is located with other antimicrobial proteins, such as lysozyme, in the granules of human neutrophils. Whereas both PGRP-S and lysozyme recognize PGN, the exact binding specificity of human PGRP-S, its functional activity, and its potential synergy with other neutrophil-derived bactericidal proteins such as lysozyme have not been determined. Here we show that human PGRP-S binds to and inhibits the growth of Staphylococcus aureus (containing lysine-type PGN) and Escherichia coli (containing mesodiaminopimelic acid-type PGN). The binding affinity and thus antimicrobial activity of PGRP-S is determined by the third amino acid in the PGN stem peptide. Furthermore, the antimicrobial effect of PGRP-S against E coli is synergistic with lysozyme, and lysozyme and PGRP-S colocalize in neutrophil extracellular traps (NETs), suggesting that these granule-derived proteins act together to kill bacteria trapped in the NETs. Taken together, these results indicate that human PGRP-S plays a role in innate immunity in the context of neutrophils by contributing to the killing of intracellular and extracellular bacteria.


Assuntos
Proteínas de Transporte/metabolismo , Proteínas de Transporte/fisiologia , Imunidade Inata , Neutrófilos/metabolismo , Neutrófilos/microbiologia , Anti-Infecciosos/farmacologia , Biotinilação , Escherichia coli/metabolismo , Humanos , Cinética , Microscopia de Fluorescência , Muramidase/química , Peptidoglicano/química , Ligação Proteica , Proteínas Recombinantes/metabolismo , Staphylococcus aureus/metabolismo , Fatores de Tempo
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