RESUMO
Preterm birth (PTB) is a major cause of neonatal mortality and morbidity, often triggered by chorioamnionitis or intrauterine inflammation (IUI) with or without infection. Recently, there has been a strong association of IL-1 with PTB. We hypothesized that IL-1R-associated kinase 1 (IRAK1), a key signaling mediator in the TLR/IL-1 pathway, plays a critical role in PTB. In human fetal membranes (FM) collected immediately after birth from women delivering preterm, p-IRAK1 was significantly increased in all the layers of FM with chorioamnionitis, compared with no-chorioamnionitis subjects. In a preterm rhesus macaque model of IUI given intra-amniotic LPS, induction of p-IRAK1 and downstream proinflammatory signaling mediators were seen in the FM. In a C57BL/6J wild-type PTB mouse model of IUI given intrauterine LPS, an IRAK1 inhibitor significantly decreased PTB and increased live birth in a dose-dependent manner. Furthermore, IRAK1 knockout mice were protected from LPS-induced PTB, which was seen in wild-type controls. Activation of IRAK1 was maintained by K63-mediated ubiquitination in preterm FM of humans with chorioamnionitis and rhesus and mouse IUI models. Mechanistically, IRAK1 induced PTB in the mouse model of IUI by upregulating expression of COX-2. Thus, our data from human, rhesus, and mouse demonstrates a critical role IRAK1 in IUI and inflammation-associated PTB and suggest it as potential therapeutic target in IUI-induced PTB.
Assuntos
Membranas Extraembrionárias/metabolismo , Quinases Associadas a Receptores de Interleucina-1/metabolismo , Nascimento Prematuro/metabolismo , Útero/imunologia , Adulto , Animais , Corioamnionite , Modelos Animais de Doenças , Membranas Extraembrionárias/patologia , Feminino , Humanos , Quinases Associadas a Receptores de Interleucina-1/genética , Lipopolissacarídeos/imunologia , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , Nascimento Prematuro/imunologia , Adulto JovemRESUMO
Inflammatory responses are controlled by signaling mediators that are regulated by various posttranslational modifications. Recently, transcription-independent functions for glucocorticoids (GC) in restraining inflammation have emerged, but the underlying mechanisms are unknown. In this study, we report that GC receptor (GR)-mediated actions of GC acutely suppress TLR9-induced inflammation via inhibition of IL-1R-associated kinase 1 (IRAK1) ubiquitination. ß-TrCP-IRAK1 interaction is required for K48-linked ubiquitination of IRAK1 at Lys134 and subsequent membrane-to-cytoplasm trafficking of IRAK1 interacting partners TNFR-associated factor 6 and TAK1 that facilitates NF-κB and MAPK activation. Upon costimulation of macrophages with GC and TLR9-engaging ligand, GR physically interacts with IRAK1 and interferes with protein-protein interactions between ß-TrCP and IRAK1. Ablation of GR in macrophages prevents GC-dependent suppression of ß-TrCP-IRAK1 interactions. This GC-mediated suppression of IRAK1 activation is unique to TLR9, as GC treatment impairs TLR9 but not TLR4 ligand-induced K48-linked IRAK1 ubiquitination and trafficking of IRAK1 interacting partners. Furthermore, mutations in IRAK1 at Lys134 prevent TLR9 ligand-induced activation of inflammatory signaling mediators and synthesis of proinflammatory cytokines to an extent comparable to GC-mediated inhibition. Collectively, these findings identify a transcription-independent, rapid, and nongenomic GC suppression of TLR9 ligand-mediated IRAK1 ubiquitination as a novel mechanism for restraining acute inflammatory reactions.
Assuntos
Glucocorticoides/metabolismo , Inflamação/imunologia , Quinases Associadas a Receptores de Interleucina-1/metabolismo , Macrófagos/imunologia , Proteínas Contendo Repetições de beta-Transducina/metabolismo , Animais , Células Cultivadas , Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , Quinases Associadas a Receptores de Interleucina-1/genética , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , NF-kappa B/metabolismo , Ligação Proteica , Transporte Proteico , Receptor Toll-Like 9/metabolismo , UbiquitinaçãoRESUMO
How to cite this article: Pachisia AV, Bhattacharyya S. Post-cardiac Arrest Ventilator Triggering. Indian J Crit Care Med 2019;23(4):196.
RESUMO
Glucocorticoids (GC) are among the most effective anti-inflammatory drugs, but are often associated with serious adverse effects or inadequate therapeutic responses. Here, we use activation of different Toll-like receptors (TLRs) by their respective ligands to evaluate context-specific GC sensitivity in the macrophage. Recruitment and activation of transforming growth factor-ß-activated kinase 1 (TAK1), downstream of TLR engagement, is crucial in activating multiple inflammatory pathways, and contributes to inflammatory disorders. We hypothesize that GC exert anti-inflammatory effects through regulation of TAK1. Both in vivo and in vitro, in comparison to other TLRs, there was limited GC potency in restricting TLR4 ligand-mediated secretion of interleukin-6, tumour necrosis factor-α and interleukin-12. Also, we found that inactivation of TAK1 both in vivo and in vitro strongly inhibits TLR4-induced inflammation-associated genes beyond the suppressive effects from GC treatment. However, there was no effect of TAK1 inactivation on GC inhibition of TLR3- or TLR9-initiated inflammatory actions. Together, our findings demonstrate that GC resistance for TAK1 activation associated with TLR4 engagement may be an important contributor to GC resistance in inflammatory disorders.
Assuntos
Resistência a Medicamentos/imunologia , Glucocorticoides/farmacologia , MAP Quinase Quinase Quinases/imunologia , Macrófagos Peritoneais/imunologia , Receptor 4 Toll-Like/imunologia , Animais , Citocinas/imunologia , Inflamação/tratamento farmacológico , Inflamação/imunologia , Inflamação/patologia , Macrófagos Peritoneais/patologia , Camundongos , Receptor 3 Toll-Like/imunologia , Receptor Toll-Like 9/imunologiaRESUMO
Endogenous and pharmacologic glucocorticoids (GCs) limit inflammatory cascades initiated by Toll-like receptor (TLR) activation. A long-standing clinical observation has been the delay between GC administration and the manifestation of GC's anti-inflammatory actions. We hypothesized that the GCs would have inhibitory effects that target late temporal pathways that propagate proinflammatory signals. Here we interrogated signal transducer and activator of transcription 1 (STAT1) regulation by GC and its consequences for cytokine production during activation of macrophages with TLR-specific ligands. We found that robust STAT1 activation does not occur until 2-3 h after TLR engagement, and that GC suppression of STAT1 phosphorylation first manifests at this time. GC attenuates TLR4-mediated STAT1 activation only through induction of suppressor of cytokine signaling 1 (SOCS1), which increases throughout the 6-h period after treatment. Inhibition of TLR3-mediated STAT1 activation occurs via two mechanisms, impairment of type I IFN secretion and induction of SOCS1. Our data show that SOCS1 and type I interferons are critical GC targets for regulating STAT1 activity and may account for overall GC effectiveness in inflammation suppression in the clinically relevant time frame.
Assuntos
Glucocorticoides/farmacologia , Interferon-alfa/metabolismo , Macrófagos/efeitos dos fármacos , Fator de Transcrição STAT1/metabolismo , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Receptores Toll-Like/metabolismo , Animais , Western Blotting , Células Cultivadas , Dexametasona/farmacologia , Fator Regulador 3 de Interferon/metabolismo , Interferon beta/farmacologia , Subunidade p40 da Interleucina-12/metabolismo , Interleucina-6/metabolismo , Janus Quinase 2/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Macrófagos/metabolismo , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação/efeitos dos fármacos , Poli I-C/farmacologia , Receptores de Interferon/metabolismo , Fator de Transcrição STAT1/genética , Proteína 1 Supressora da Sinalização de Citocina , Proteínas Supressoras da Sinalização de Citocina/genéticaRESUMO
Glucocorticoids potently attenuate the production of inflammatory mediators by macrophages, a primary effector of innate immunity. Activation of different macrophage Toll-like receptors (TLRs) by their respective ligands presents a powerful system by which to evaluate stimulus-dependent glucocorticoid effects in the same cell type. Here, we test the hypothesis that glucocorticoids, acting through the glucocorticoid receptor, modulate macrophage activation preferentially depending upon the TLR-selective ligand and TLR adapters. We established that 2 adapters, Trif, MyD88, or both, determine the ability of glucocorticoids to suppress inhibitor of kappaB (IkappaB) degradation or Janus kinase (JNK) activation. Moreover, the sensitivity of transforming growth factor beta-activated kinase 1 (TAK1) activation to glucocorticoids determines these effects. These findings identify TAK1 as a novel target for glucocorticoids that integrates their anti-inflammatory action in innate immunity signaling pathways.
Assuntos
Glucocorticoides/farmacologia , Proteínas I-kappa B/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , MAP Quinase Quinase Quinases/antagonistas & inibidores , Ativação de Macrófagos/efeitos dos fármacos , Polidesoxirribonucleotídeos/farmacologia , Receptores Toll-Like/agonistas , Animais , Dexametasona/farmacologia , Sistemas de Liberação de Medicamentos , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/genética , MAP Quinase Quinase Quinases/genética , Ativação de Macrófagos/genética , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Receptor 3 Toll-Like/antagonistas & inibidores , Receptor 3 Toll-Like/metabolismo , Receptor Toll-Like 9/antagonistas & inibidores , Receptor Toll-Like 9/metabolismo , Receptores Toll-Like/metabolismo , Receptores Toll-Like/fisiologiaRESUMO
Human and rodent studies indicate a role for circadian rhythmicity and associated clock gene expression in supporting normal parturition. The importance of clock gene expression in tissues besides the suprachiasmatic nucleus is emerging. Here, a Bmal1 conditional knockout mouse line and a novel Cre transgenic mouse line were used to examine the role of myometrial Bmal1 in parturition. Ninety-two percent (22/24) of control females but only 64% (14/22) of females with disrupted myometrial Bmal1 completed parturition during the expected time window of 5p.m. on Day 19 through to 9a.m. on Day 19.5 of gestation. However, neither serum progesterone levels nor uterine transcript expression of the contractile-associated proteins Connexin43 and Oxytocin receptor differed between females with disrupted myometrial Bmal1 and controls during late gestation. The data indicate a role for myometrial Bmal1 in maintaining normal time of day of parturition.
Assuntos
Fatores de Transcrição ARNTL/genética , Miométrio/metabolismo , Parto , Fatores de Transcrição ARNTL/metabolismo , Fatores de Transcrição ARNTL/fisiologia , Animais , Relógios Biológicos/genética , Feminino , Técnicas de Transferência de Genes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Especificidade de Órgãos/genética , Parto/genética , Parto/metabolismo , Parto/fisiologia , Gravidez , Fatores de TempoRESUMO
It is essential to assess bone density among mandible teeth as well as among patients and also to observe the variation in all mechanical parameters of the bone for accurate design of patient-specific dental implants. This information helps in the design of implants to create a more osseointegration-friendly environment at the bone adjacent to the implant. For this study, 40 patients were chosen irrespective of age, sex, and bone density. Hounsfield Units were calculated using cone beam computed tomography data. Seven teeth were studied: central incisor, lateral incisor, canine, first premolar, second premolar, first molar, and second molar. A total of 12 arbitrary points were chosen in both buccal and lingual sides which were further divided into external and internal. From the analysis, it was observed that the bone density of the central incisor and that of the canine is greater than that of the molars.
Assuntos
Implantes Dentários , Dente Pré-Molar , Tomografia Computadorizada de Feixe Cônico , Humanos , Mandíbula/diagnóstico por imagem , MaxilaRESUMO
Visceral leishmaniasis, caused by the protozoan parasite Leishmania donovani, is characterized by the loss of ability of the host to generate an effective immune response. In the present study, the comparative potential of CXC chemokines, interferon-gamma-inducible protein-10 (IP-10) and interleukin-8 (IL-8) in restricting Leishmania donovani infection via the release of nitric oxide and proinflammatory cytokines was studied in an in vitro model. Nitric oxide, a crucial mediator for IP-10-mediated leishmanicidal activity, was found to be dependent on inducible nitric oxide synthase 2 (iNOS2) expression and was linked to the mitogen-activated protein kinases (MAPK) signaling pathway. Further, IP-10 was also able to abrogate the survival of Leishmania in an in vivo model of visceral leishmaniasis by restoration of Th1 cytokines and nitric oxide. Thus, this study strongly demonstrates that IP-10, like CC chemokines, is involved in rendering a protective response in visceral leishmaniasis via up-regulation of proinflammatory mediators.
Assuntos
Quimiocinas CXC/metabolismo , Leishmaniose Visceral/imunologia , Macrófagos Peritoneais/metabolismo , Animais , Quimiocinas CXC/genética , Feminino , Regulação da Expressão Gênica/fisiologia , Leishmania donovani/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Fatores de TempoRESUMO
The pathogenesis of glucocorticoid-induced (GC-induced) bone loss is unclear. For example, osteoblast apoptosis is enhanced by GCs in vivo, but they stimulate bone formation in vitro. This conundrum suggests that an intermediary cell transmits a component of the bone-suppressive effects of GCs to osteoblasts in the intact animal. Bone remodeling is characterized by tethering of the activities of osteoclasts and osteoblasts. Hence, the osteoclast is a potential modulator of the effect of GCs on osteoblasts. To define the direct impact of GCs on bone-resorptive cells, we compared the effects of dexamethasone (DEX) on WT osteoclasts with those derived from mice with disruption of the GC receptor in osteoclast lineage cells (GRoc-/- mice). While the steroid prolonged longevity of osteoclasts, their bone-degrading capacity was suppressed. The inhibitory effect of DEX on bone resorption reflects failure of osteoclasts to organize their cytoskeleton in response to M-CSF. DEX specifically arrested M-CSF activation of RhoA, Rac, and Vav3, each of which regulate the osteoclast cytoskeleton. In all circumstances GRoc-/- mice were spared the impact of DEX on osteoclasts and their precursors. Consistent with osteoclasts modulating the osteoblast-suppressive effect of DEX, GRoc-/- mice are protected from the steroid's inhibition of bone formation.
Assuntos
Desenvolvimento Ósseo/fisiologia , Dexametasona/farmacologia , Glucocorticoides/farmacologia , Osteoclastos/fisiologia , Animais , Desenvolvimento Ósseo/efeitos dos fármacos , Reabsorção Óssea/prevenção & controle , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Camundongos Knockout , Osteoclastos/citologia , Osteoclastos/efeitos dos fármacos , Receptores de Glucocorticoides/deficiência , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/fisiologiaRESUMO
A rare malposition of central venous catheter in the left superior intercostal vein is described. The diagnostic features and the possible ways to prevent this complication are discussed.
RESUMO
Neutrophil infiltration of the chorioamnion-decidua tissue at the maternal-fetal interface (chorioamnionitis) is a leading cause of prematurity, fetal inflammation, and perinatal mortality. We induced chorioamnionitis in preterm rhesus macaques by intraamniotic injection of LPS. Here, we show that, during chorioamnionitis, the amnion upregulated phospho-IRAK1-expressed neutrophil chemoattractants CXCL8 and CSF3 in an IL-1-dependent manner. IL-1R blockade decreased chorio-decidua neutrophil accumulation, neutrophil activation, and IL-6 and prostaglandin E2 concentrations in the amniotic fluid. Neutrophils accumulating in the chorio-decidua had increased survival mediated by BCL2A1, and IL-1R blockade also decreased BCL2A1+ chorio-decidua neutrophils. Readouts for inflammation in a cohort of women with preterm delivery and chorioamnionitis were similar to findings in the rhesus macaques. IL-1 is a potential therapeutic target for chorioamnionitis and associated morbidities.
Assuntos
Corioamnionite/imunologia , Corioamnionite/metabolismo , Decídua/imunologia , Inflamação/imunologia , Interleucina-1/metabolismo , Infiltração de Neutrófilos/imunologia , Transdução de Sinais , Âmnio/metabolismo , Animais , Apoptose , Corioamnionite/genética , Corioamnionite/patologia , Córion , Citocinas/metabolismo , Decídua/efeitos dos fármacos , Decídua/patologia , Feminino , Humanos , Recém-Nascido , Quinases Associadas a Receptores de Interleucina-1/metabolismo , Interleucina-8/metabolismo , Lipopolissacarídeos/efeitos adversos , Macaca mulatta , Antígenos de Histocompatibilidade Menor/metabolismo , Neutrófilos/imunologia , Gravidez , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Receptores de Interleucina-1/metabolismoRESUMO
Glucocorticoid (GC)-induced bone loss is the most common cause of secondary osteoporosis but its pathogenesis is controversial. GCs clearly suppress bone formation in vivo but the means by which they impact osteoblasts is unclear. Because bone remodeling is characterized by tethering of the activities of the two cells, the osteoclast is a potential modulator of the effect of GCs on osteoblasts. To address this issue we compared the effects of dexamethasone on wild-type (WT) osteoclasts with those derived from mice with disruption of the GC receptor in osteoclast lineage cells and found that the bone-degrading capacity of GC-treated WT cells is suppressed. The inhibitory effect of dexamethasone on bone resorption reflects failure of osteoclasts to organize their cytoskeleton in response to M-CSF. Dexamethasone specifically arrests M-CSF activation of RhoA, Rac, and Vav3, each of which regulate the osteoclast cytoskeleton. In all circumstances, mice lacking the GC receptor in osteoclast lineage cells are spared the impact of dexamethasone on osteoclasts and their precursors. Consistent with osteoclasts modulating the osteoblast-suppressive effect of dexamethasone, GC receptor-deficient mice are protected from the steroid's inhibition of bone formation.
Assuntos
Glucocorticoides/efeitos adversos , Osteoclastos/citologia , Animais , CamundongosRESUMO
Glucocorticoids are central to treating inflammatory and immune disorders. These steroids, however, profoundly impact the skeleton, particularly when administered for prolonged periods. In fact, high-dose glucocorticoid therapy is almost universally associated with bone loss, prompting among the most common forms of crippling osteoporosis. Despite the frequency and severity of glucocorticoid-induced osteoporosis, its treatment is less than satisfactory, suggesting that its pathogenesis is incompletely understood. Net bone mass represents the relative activities of osteoblasts and osteoclasts and there is little question that glucocorticoids suppress the bone-forming cells, in vivo, via a process involving accelerated apoptosis (Weinstein 2001; Weinstein, Jilka, Parfitt, et al. 1998). Surprisingly, however, addition of glucocorticoids to cultures of osteoprogenitor cells actually increases their capacity to form mineralized bone nodules (Aubin 1999; Purpura, Aubin, and Zandstra 2004). This paradox raises the possibility that glucocorticoid suppression of bone formation, in vivo, reflects, at least in part, the steroid's targeting intermediary cells, which in turn inhibit the osteoblast. Bone remodeling is an ever-occuring event in mammals which is characterized by tethering of osteoclast and osteoblast function. The process is initiated by osteoclasts (OCs) resorbing a packet of bone, which in turn leads to osteoblasts being recruited to the site of resorption. This process establishes that osteoclastic bone resorption, in some manner, promotes osteoblastic bone formation at the same location. Consequently, pathologically or pharmacologically inhibited resorption eventuates in arrested osteoblast activity.
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Dexametasona/farmacologia , Glucocorticoides/farmacologia , Osteoblastos/efeitos dos fármacos , Osteoclastos/efeitos dos fármacos , Osteoclastos/metabolismo , Osteogênese/efeitos dos fármacos , Animais , Reabsorção Óssea , Células Cultivadas , Humanos , Osteoblastos/metabolismo , Ligante RANK/metabolismoRESUMO
The etiology and mechanisms for inflammatory bowel disease (IBD) are incompletely known. Determination of new, clinically important mechanisms for intestinal inflammation is imperative for developing effective therapies to treat IBD We sought to define a widespread mechanism for colon mucosal inflammation via the activation of TGF-ß activated Kinase 1 (TAK1), a central regulator of cellular inflammatory actions. Activation of TAK1 and the downstream inflammatory signaling mediators was determined in pediatric patients with ulcerative colitis (UC) or Crohn's disease (CD) as well as in DSS-induced and spontaneous IBD in mice. The role of TAK1 in facilitating intestinal inflammation in murine models of IBD was investigated by using (5Z)-7-Oxozeaenol, a highly selective pharmacological inhibitor of TAK1. We found hyper-activation of TAK1 in patients with UC or CD and in murine models of IBD Pharmacological inhibition of TAK1 prevented loss in body weight, disease activity, microscopic histopathology, infiltration of inflammatory cells in the colon mucosa, and elevated proinflammatory cytokine production in two murine models of IBD We demonstrated that at the early phase of the disease activation of TAK1 is restricted in the epithelial cells. However, at a more advanced stage of the disease, TAK1 activation predominantly occurs in nonepithelial cells, especially in macrophages. These findings elucidate the activation of TAK1 as crucial in promoting intestinal inflammation. Thus, the TAK1 activation pathway may represent a suitable target to design new therapies for treating IBD in humans.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Colo/metabolismo , Doenças Inflamatórias Intestinais/metabolismo , Mucosa Intestinal/metabolismo , Adolescente , Animais , Criança , Pré-Escolar , Colo/patologia , Feminino , Humanos , Doenças Inflamatórias Intestinais/patologia , Interleucina-10/genética , Interleucina-10/metabolismo , Mucosa Intestinal/patologia , Masculino , Camundongos , Camundongos KnockoutRESUMO
To explore the role of glucocorticoids in regulation of kinase pathways during innate immune responses, we generated mice with conditional deletion of glucocorticoid receptor (GR) in macrophages (MGRKO). Activation of toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) caused greater mortality and cytokine production in MGRKO mice than in controls. Ex vivo, treatment with dexamethasone (Dex) markedly inhibited LPS-mediated induction of inflammatory genes in control but not GR-deficient macrophages. We show that Dex inhibits p38 MAPK, but not PI3K/Akt, ERK, or JNK, in control macrophages. Associated with p38 inhibition, Dex induced MAP kinase phosphatase-1 (MKP-1) in control, but not MGRKO, macrophages. Consistent with the ex vivo studies, treatment with a p38 MAPK-specific inhibitor resulted in rescue of MGRKO mice from LPS-induced lethality. Taken together, we identify p38 MAPK and its downstream targets as essential for GR-mediated immunosuppression in macrophages.
Assuntos
Inflamação/imunologia , Inflamação/metabolismo , Macrófagos/fisiologia , Receptores de Glucocorticoides/fisiologia , Receptor 4 Toll-Like/fisiologia , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Animais , Proteínas de Ciclo Celular/metabolismo , Citocinas/metabolismo , Dexametasona/farmacologia , Fosfatase 1 de Especificidade Dupla , Inibidores Enzimáticos/farmacologia , Proteínas Imediatamente Precoces/metabolismo , Inflamação/induzido quimicamente , Inflamação/mortalidade , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Fosfoproteínas Fosfatases/metabolismo , Proteína Fosfatase 1 , Proteínas Tirosina Fosfatases/metabolismo , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Receptor 4 Toll-Like/metabolismoRESUMO
The protein kinase C (PKC) family regulates macrophage function involved in host defense against infection. In the case of Leishmania donovani infection, the impairment of PKC-mediated signaling is one of the crucial events for the establishment of parasite into the macrophages. Earlier reports established that C-C chemokines mediated protection against leishmaniasis via the generation of nitric oxide after 48 h. In this study, we investigated the role of MIP-1alpha and MCP-1 in the regulation of impaired PKC activity in the early hours (6 h) of infection. These chemokines restored Ca2+-dependent PKC activity and inhibited Ca2+-independent atypical PKC activity in L. donovani-infected macrophages under both in vivo and in vitro conditions. Pretreatment of macrophages with chemokines induced superoxide anion generation by activating NADPH oxidase components in infected cells. Chemokine administration in vitro induced the migration of infected macrophages and triggered the production of reactive oxygen species. In vivo treatment with chemokines significantly restricted the parasitic burden in livers as well as in spleens. Collectively, these results indicate a novel regulatory role of C-C chemokines in controlling the intracellular growth and multiplication of L. donovani, thereby demonstrating the antileishmanial properties of C-C chemokines in the disease process.
Assuntos
Quimiocinas CC/farmacologia , Leishmania donovani , Leishmaniose Visceral/imunologia , Macrófagos/enzimologia , Proteína Quinase C/metabolismo , Animais , Quimiocinas CC/metabolismo , Quimiotaxia , Leishmaniose Visceral/enzimologia , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Proteína Quinase C/genética , Proteína Quinase C beta , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Transdução de Sinais , Baço/citologia , Baço/enzimologia , Superóxidos/metabolismoRESUMO
Interleukin-10 (IL-10) has potent immunoregulatory effects on the maturation and the antigen-presenting cell (APC) function of dendritic cells (DCs). The molecular basis underlying these effects in DCs, however, is ill defined. It is well established that the transcription factor NF-kappaB is a key regulator of DC development, maturation, and APC function. This study was initiated to determine the effects of IL-10 on the NF-kappaB signaling pathway in immature DCs. IL-10 pretreatment of myeloid DCs cultured from bone marrow resulted in reduced DNA binding and nuclear translocation of NF-kappaB after anti-CD40 antibody or lipopolysaccharide (LPS) stimulation. Furthermore, inhibited NF-kappaB activation was characterized by reduced degradation, phosphorylation, or both of IkappaBalpha and IkappaBepsilon but not IkappaBbeta and by reduced phosphorylation of Ser536, located in the trans-activation domain of p65. Notably, IL-10-mediated inhibition of NF-kappaB coincided with suppressed IkappaB kinase (IKK) activity in vitro. Furthermore, IL-10 blocked inducible Akt phosphorylation, and inhibitors of phosphatidylinositol 3-kinase (PI3K) effectively suppressed the activation of Akt, IKK, and NF-kappaB. These findings demonstrate that IL-10 targets IKK activation in immature DCs and that suppressing the PI3K pathway in part mediates blockade of the pathway.
Assuntos
Células Dendríticas/imunologia , Interleucina-10/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Apresentação de Antígeno/efeitos dos fármacos , Células Dendríticas/efeitos dos fármacos , Quinase I-kappa B , Fatores Imunológicos/farmacologia , Camundongos , Camundongos Endogâmicos , Células Mieloides , NF-kappa B/efeitos dos fármacos , NF-kappa B/metabolismo , Fosfatidilinositol 3-Quinases/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/efeitos dos fármacos , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-aktRESUMO
This study explored the role of the proinflammatory chemokines macrophage inflammatory protein (MIP)-1alpha and macrophage chemoattractant protein (MCP)-1 for development of antileishmanial activity. There was substantial inhibition in nitrite generation in Leishmania donovani-infected macrophages. A marked elevation of nitrite generation and induction of inducible nitric oxide (NO) synthase (iNOS) mRNA was found in chemokine-primed parasite-infected macrophages. Tumor necrosis factor-alpha, which is the priming signal for NO production, was also up-regulated under similar experimental conditions. The priming with chemokine inhibited the multiplication of L. donovani amastigotes within the intramacrophageal milieu. The antileishmanial effect of chemokines was almost completely abrogated when the macrophages were preincubated with l-N-monomethyl arginine, the specific inhibitor of iNOS. The results of this investigation suggest that the CC chemokines MIP-1alpha and MCP-1 orchestrate an antileishmanial armamentarium via the induction of an NO-mediated regulatory mechanism to control the intracellular growth and multiplication of the Leishmania protozoan.
Assuntos
Quimiocina CCL2/fisiologia , Leishmania donovani , Proteínas Inflamatórias de Macrófagos/fisiologia , Macrófagos Peritoneais/metabolismo , Óxido Nítrico/biossíntese , Animais , Quimiocina CCL3 , Quimiocina CCL4 , Indução Enzimática , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico Sintase/biossíntese , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo II , Nitritos/metabolismo , RNA Mensageiro/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Regulação para Cima , ômega-N-Metilarginina/farmacologiaRESUMO
In vitro infection of murine peritoneal macrophages with the protozoan Leishmania donovani has been found to alter the signaling parameters of the host. The present study indicates that the enhancement of intracellular ceramide level in macrophages after infection is a major event relating to macrophage dysfunction. We have previously demonstrated that increased ceramide synthesis in host macrophages was involved in the dephosphorylation of extracellular signal-regulated kinase (ERK). In the present study, we further show that downregulation of ERK by ceramide was found to be associated with the inhibition of activated protein 1 (AP-1) and NF-kappaB transactivation. Pharmacological inhibition of ceramide synthesis by Fumonisin B1 restored the induction of AP-1 and NF-kappaB DNA-binding activities in infected BALB/c macrophages. On the contrary, in the case of macrophages from the leishmaniasis-resistant C.D2 mice, L. donovani failed to induce sustained ceramide synthesis. Enhanced mitogen-activated protein kinase phosphorylation, AP-1 and NF-kappaB DNA-binding activity, and the generation of nitric oxide (NO) were observed in L. donovani-infected C.D2 macrophages. ERK activation was necessary for the activation of transcription factors AP-1 and NF-kappaB, NO generation, and restriction of the parasite burden in the resistant murine host macrophages. Hence, the induction of ceramide synthesis in host macrophages appears to be instrumental and one of the turning points leading to silencing of the macrophage antileishmanial responses.