RESUMO
Uric acid (UA), a product of purine nucleotide degradation able to initiate an immune response, represents a breakpoint in the evolutionary history of humans, when uricase, the enzyme required for UA cleavage, was lost. Despite being inert in human cells, UA in its soluble form (sUA) can increase the level of interleukin-1ß (IL-1ß) in murine macrophages. We, therefore, hypothesized that the recognition of sUA is achieved by the Naip1-Nlrp3 inflammasome platform. Through structural modelling predictions and transcriptome and functional analyses, we found that murine Naip1 expression in human macrophages induces IL-1ß expression, fatty acid production and an inflammation-related response upon sUA stimulation, a process reversed by the pharmacological and genetic inhibition of Nlrp3. Moreover, molecular interaction experiments showed that Naip1 directly recognizes sUA. Accordingly, Naip may be the sUA receptor lost through the human evolutionary process, and a better understanding of its recognition may lead to novel anti-hyperuricaemia therapies.
Assuntos
Inflamassomos/metabolismo , Macrófagos/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteína Inibidora de Apoptose Neuronal/metabolismo , Ácido Úrico/farmacologia , Animais , Ácidos Graxos/metabolismo , Humanos , Inflamassomos/genética , Inflamassomos/imunologia , Interleucina-1beta/metabolismo , Macaca mulatta , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína Inibidora de Apoptose Neuronal/genética , Ligação Proteica , Células THP-1 , Ácido Úrico/metabolismoRESUMO
Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic ß-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1ß protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1ß secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.
Assuntos
Anti-Inflamatórios/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 1/tratamento farmacológico , Ácidos Docosa-Hexaenoicos/farmacologia , Inflamação/tratamento farmacológico , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Adulto , Animais , Células Cultivadas , Citocinas/metabolismo , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/enzimologia , Diabetes Mellitus Experimental/imunologia , Diabetes Mellitus Tipo 1/induzido quimicamente , Diabetes Mellitus Tipo 1/enzimologia , Diabetes Mellitus Tipo 1/imunologia , Feminino , Humanos , Inflamação/induzido quimicamente , Inflamação/enzimologia , Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/imunologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Knockout , Pessoa de Meia-Idade , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Gravidez , Transdução de Sinais , EstreptozocinaRESUMO
Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic β-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1β protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1β secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.
RESUMO
Atherosclerosis, a chronic inflammatory disease of the arterial wall, is the leading cause of cardiac disorders and stroke. The onset and progression of these diseases are linked with the inflammatory response, especially NLRP3 inflammasome activation, inducing the production of proinflammatory cytokines, such as interleukin 1ß (IL-1ß). Because high-density lipoproteins (HDLs) have shown significant antiatherogenic and anti-inflammatory properties, we evaluated their immunomodulatory activity in response to cholesterol crystals and other innate immune activators. Human primary monocyte-derived macrophages, THP-1 cells, and murine macrophages were stimulated to activate NLRP3 inflammasome and other pattern recognition receptors, in the presence or absence of HDL. Then, HDL immunomodulatory effects were evaluated through IL-1ß and IL-6 production by enzyme-linked immunosorbent assay. Furthermore, in vivo HDL anti-inflammatory effects were evaluated in a murine model of peritoneal inflammatory infiltration. HDLs have an immunomodulatory effect on different cellular models, including peripheral blood mononuclear cells, THP-1 cells, and murine macrophages, by affecting the activity of innate immunity sensors, such as Toll-like receptors (TLRs), dectin-1, and inflammasomes. HDL reduces the proinflammatory role of cholesterol crystals, nigericin, and other NLRP3 and AIM2 inflammasome agonists, and several TLR agonists, leading to a decreased production of IL-1ß and IL-6. The results suggest that HDLs are highly important in the regulation of the innate immune response and may have a beneficial role in controlling diseases associated with the inflammatory response.
Assuntos
Imunidade Inata/imunologia , Inflamação/imunologia , Lipoproteínas HDL/imunologia , Animais , Células Cultivadas , Humanos , CamundongosRESUMO
Uric acid is a damage-associated molecular pattern (DAMP), released from ischemic tissues and dying cells which, when crystalized, is able to activate the NLRP3 inflammasome. Soluble uric acid (sUA) is found in high concentrations in the serum of great apes, and even higher in some diseases, before the appearance of crystals. In the present study, we sought to investigate whether uric acid, in the soluble form, could also activate the NLRP3 inflammasome and induce the production of IL-1ß. We monitored ROS, mitochondrial area and respiratory parameters from macrophages following sUA stimulus. We observed that sUA is released in a hypoxic environment and is able to induce IL-1ß release. This process is followed by production of mitochondrial ROS, ASC speck formation and caspase-1 activation. Nlrp3-/- macrophages presented a protected redox state, increased maximum and reserve oxygen consumption ratio (OCR) and higher VDAC protein levels when compared to WT and Myd88-/- cells. Using a disease model characterized by increased sUA levels, we observed a correlation between sUA, inflammasome activation and fibrosis. These findings suggest sUA activates the NLRP3 inflammasome. We propose that future therapeutic strategies for renal fibrosis should include strategies that block sUA or inhibit its recognition by phagocytes.
Assuntos
Inflamassomos/metabolismo , Nefropatias/metabolismo , Rim/patologia , Macrófagos/fisiologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Ácido Úrico/metabolismo , Animais , Caspase 1/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Fibrose , Interleucina-1beta/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Canais de Ânion Dependentes de Voltagem/metabolismoRESUMO
BACKGROUND/AIMS: Inflammasomes are multimolecular complexes that regulate caspase-1. They act as sensors for endogenous and exogenous signals, and mediate the processing of pro-IL-1ß into its secreted, biologically active form. The NLRP3 inflammasome and IL-1ß are particularly interesting because they are required for efficient control of viral infections. Indeed, HIV-1 induces expression of NLRP3 and IL-1ß in healthy controls, but not in HIV-1-infected patients. Here we evaluate whether HIV-1 can induce activation of the NLRP3 inflammasome. METHODS: Human primary monocyte-derived macrophages were infected with HIV-1 in the absence or presence of classical NLRP3 inflammasome activators, and IL-1ß release was assessed by ELISA. RESULTS: HIV-1 initiates the priming signal for NLRP3 inflammasome activation through the NF-κB-associated pathway in human primary monocyte-derived macrophages. Furthermore, priming of NLRP3 activation in response to HIV-1 was independent of the viral envelope, since similar results were observed with HIV-1 and pseudotyped HIV-1 lacking the env gene. CONCLUSION: Our findings suggest that HIV-1 infection promotes IL-1ß secretion by inducing the first signal for NLRP3 inflammasome activation, a phenomenon that may contribute to AIDS progression.
Assuntos
Proteínas de Transporte/metabolismo , HIV-1/imunologia , Inflamassomos/metabolismo , Macrófagos/imunologia , Macrófagos/virologia , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Humanos , Interleucina-1beta/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLRRESUMO
Toll-like receptors (TLRs) play a critical role in innate immunity against pathogens. Their stimulation induces the activation of NF-κB, an important inducer of HIV-1 replication. In recent years, an increasing number of studies using several cells types from HIV-infected patients indicate that TLRs play a key role in regulating the expression of proinflammatory cytokines and viral pathogenesis. In the present study, the effect of HIV-1 stimulation of monocyte-derived macrophage (MDM) and peripheral blood mononuclear cell (PBMC) subpopulations from healthy donors on the expression and functions of TLR2 and TLR4 was examined. In addition, and to complete the in vitro study, the expression pattern of TLR2 and TLR4 in 49 HIV-1-infected patients, classified according to viral load and the use of HAART, was determined and compared with 25 healthy subjects. An increase of TLR expression and production of proinflammatory cytokines were observed in MDMs and PBMCs infected with HIV-1 in vitro and in response to TLR stimulation, compared to the mock. In addition, an association between TLR expression and up-regulation of CD80 in plasmacytoid dendritic cells (pDCs) was observed. The ex vivo analysis indicated increased expression of TLR2 and TLR4 in myeloid dendritic cells (mDCs), but only of TLR2 in monocytes obtained from HIV-1-infected patients, compared to healthy subjects. Remarkably, the expression was higher in cells from patients who do not use HAART. In monocytes, there was a positive correlation between both TLRs and viral load, but not CD4(+) T cell numbers. Together, our in vitro and ex vivo results suggest that TLR expression and function can be up-regulated in response to HIV-1 infection and could affect the inflammatory response. We propose that modulation of TLRs represents a mechanism to promote HIV-1 replication or AIDS progression in HIV-1-infected patients.
Assuntos
Síndrome da Imunodeficiência Adquirida/imunologia , Células Dendríticas/imunologia , HIV-1/metabolismo , Receptor 2 Toll-Like/imunologia , Receptor 4 Toll-Like/imunologia , Síndrome da Imunodeficiência Adquirida/genética , Adolescente , Adulto , Contagem de Linfócito CD4 , Feminino , Citometria de Fluxo , Regulação Viral da Expressão Gênica , Humanos , Imunidade Inata , Macrófagos/imunologia , Masculino , Pessoa de Meia-Idade , RNA Viral/metabolismo , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/genética , Regulação para Cima , Carga Viral , Adulto JovemRESUMO
The ability to trigger an innate immune response against opportunistic pathogens associated with HIV-1 infection is an important aspect of AIDS pathogenesis. Toll-like receptors (TLRs) play a critical role in innate immunity against pathogens, but in HIV-1 patients coinfected with opportunistic infections, the regulation of TLR expression has not been studied. In this context, we have evaluated the expression of TLR2 and TLR4 in monocytes, plasmacytoid dendritic cells, and myeloid dendritic cells of HIV-1 patients with or without opportunistic infections. Forty-nine HIV-1-infected individuals were classified according to viral load, highly active antiretroviral therapy (HAART), and the presence or absence of opportunistic infections, and 21 healthy subjects served as controls. Increased expression of TLR2 and TLR4 was observed in myeloid dendritic cells of HIV-1 patients coinfected with opportunistic infections (without HAART), while TLR4 increased in plasmacytoid dendritic cells, compared to both HIV-1 without opportunistic infections and healthy subjects. Moreover, TLR2 expression was higher in patients with opportunistic infections without HAART and up-regulation of TLR expression in HIV-1 patients coinfected with opportunistic infections was more pronounced in dendritic cells derived from individuals coinfected with Mycobacterium tuberculosis. The results indicate that TLR expression in innate immune cells is up-regulated in patients with a high HIV-1 load and coinfected with opportunistic pathogens. We suggest that modulation of TLRs expression represents a mechanism that promotes HIV-1 replication and AIDS pathogenesis in patients coinfected with opportunistic pathogens.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/imunologia , Coinfecção , Células Dendríticas/imunologia , Infecções por HIV/imunologia , Receptor 2 Toll-Like/imunologia , Receptor 4 Toll-Like/imunologia , Infecções Oportunistas Relacionadas com a AIDS/microbiologia , Infecções Oportunistas Relacionadas com a AIDS/virologia , Adulto , Terapia Antirretroviral de Alta Atividade , Infecções Bacterianas/complicações , Infecções Bacterianas/imunologia , Infecções Bacterianas/microbiologia , Contagem de Linfócito CD4 , Candida/imunologia , Candida/patogenicidade , Candidíase/complicações , Candidíase/imunologia , Candidíase/microbiologia , Estudos de Casos e Controles , Feminino , Citometria de Fluxo , Regulação da Expressão Gênica , Infecções por HIV/complicações , Infecções por HIV/microbiologia , Infecções por HIV/virologia , HIV-1/imunologia , HIV-1/patogenicidade , Humanos , Masculino , Pessoa de Meia-Idade , Monócitos/imunologia , Mycobacterium tuberculosis/imunologia , Mycobacterium tuberculosis/patogenicidade , RNA Mensageiro/análise , RNA Viral/sangue , RNA Viral/genética , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/genética , Regulação para Cima , Carga Viral , Adulto JovemRESUMO
TLR9 is critical in parasite recognition and host resistance to experimental infection with Trypanosoma cruzi. However, no information is available regarding nucleotide sequences and cellular events involved on T. cruzi recognition by TLR9. In silico wide analysis associated with in vitro screening of synthetic oligonucleotides demonstrates that the retrotransposon VIPER elements and mucin-like glycoprotein (TcMUC) genes in the T. cruzi genome are highly enriched for CpG motifs that are immunostimulatory for mouse and human TLR9, respectively. Importantly, infection with T. cruzi triggers high levels of luciferase activity under NF-kappaB-dependent transcription in HEK cells cotransfected with human TLR9, but not in control (cotransfected with human MD2/TLR4) HEK cells. Further, we observed translocation of TLR9 to the lysosomes during invasion/uptake of T. cruzi parasites by dendritic cells. Consistently, potent proinflammatory activity was observed when highly unmethylated T. cruzi genomic DNA was delivered to the endo-lysosomal compartment of host cells expressing TLR9. Thus, together our results indicate that the unmethylated CpG motifs found in the T. cruzi genome are likely to be main parasite targets and probably become available to TLR9 when parasites are destroyed in the lysosome-fused vacuoles during parasite invasion/uptake by phagocytes.