RESUMO
Background: Alzheimer's disease (AD) is the most common neurodegenerative disorder affecting memory and cognition. The disease is accompanied by an abnormal deposition of ß-amyloid plaques in the brain that contributes to neurodegeneration and is known to induce glial inflammation. Studies in the APP/PS1 mouse model of ß-amyloid-induced neuropathology have suggested a role for inflammasome activation in ß-amyloid-induced neuroinflammation and neuropathology. Methods: Here, we evaluated the in vivo role of microglia-selective and full body inflammasome signalling in several mouse models of ß-amyloid-induced AD neuropathology. Results: Microglia-specific deletion of the inflammasome regulator A20 and inflammasome effector protease caspase-1 in the AppNL-G-F and APP/PS1 models failed to identify a prominent role for microglial inflammasome signalling in ß-amyloid-induced neuropathology. Moreover, global inflammasome inactivation through respectively full body deletion of caspases 1 and 11 in AppNL-G-F mice and Nlrp3 deletion in APP/PS1 mice also failed to modulate amyloid pathology and disease progression. In agreement, single-cell RNA sequencing did not reveal an important role for Nlrp3 signalling in driving microglial activation and the transition into disease-associated states, both during homeostasis and upon amyloid pathology. Conclusion: Collectively, these results question a generalizable role for inflammasome activation in preclinical amyloid-only models of neuroinflammation.
Assuntos
Doença de Alzheimer , Camundongos , Animais , Doença de Alzheimer/patologia , Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Peptídeos beta-Amiloides , Precursor de Proteína beta-Amiloide/genética , Doenças Neuroinflamatórias , Camundongos Transgênicos , Amiloide , Proteínas AmiloidogênicasRESUMO
Protein ubiquitination regulates protein stability and modulates the composition of signaling complexes. A20 is a negative regulator of inflammatory signaling, but the molecular mechanisms involved are ill understood. Here, we generated Tnfaip3 gene-targeted A20 mutant mice bearing inactivating mutations in the zinc finger 7 (ZnF7) and ZnF4 ubiquitin-binding domains, revealing that binding to polyubiquitin is essential for A20 to suppress inflammatory disease. We demonstrate that a functional ZnF7 domain was required for recruiting A20 to the tumor necrosis factor receptor 1 (TNFR1) signaling complex and to suppress inflammatory signaling and cell death. The combined inactivation of ZnF4 and ZnF7 phenocopied the postnatal lethality and severe multiorgan inflammation of A20-deficient mice. Conditional tissue-specific expression of mutant A20 further revealed the key role of ubiquitin-binding in myeloid and intestinal epithelial cells. Collectively, these results demonstrate that the anti-inflammatory and cytoprotective functions of A20 are largely dependent on its ubiquitin-binding properties.
Assuntos
Inflamação/metabolismo , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/metabolismo , Animais , Células Epiteliais/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Células Mieloides/metabolismo , Poliubiquitina/metabolismo , Ligação Proteica/fisiologia , Transdução de Sinais/fisiologia , Fator de Necrose Tumoral alfa/metabolismo , Ubiquitina/metabolismo , Ubiquitinação/fisiologia , Dedos de Zinco/fisiologiaRESUMO
Inflammatory signaling pathways are tightly regulated to avoid chronic inflammation and the development of disease. OTULIN is a deubiquitinating enzyme that controls inflammation by cleaving linear ubiquitin chains generated by the linear ubiquitin chain assembly complex. Here, we show that ablation of OTULIN in liver parenchymal cells in mice causes severe liver disease which is characterized by liver inflammation, hepatocyte apoptosis, and compensatory hepatocyte proliferation, leading to steatohepatitis, fibrosis, and hepatocellular carcinoma (HCC). Genetic ablation of Fas-associated death domain (FADD) completely rescues and knockin expression of kinase inactive receptor-interacting protein kinase 1 (RIPK1) significantly protects mice from developing liver disease, demonstrating that apoptosis of OTULIN-deficient hepatocytes triggers disease pathogenesis in this model. Finally, we demonstrate that type I interferons contribute to disease in hepatocyte-specific OTULIN-deficient mice. Our study reveals the critical importance of OTULIN in protecting hepatocytes from death, thereby preventing the development of chronic liver inflammation and HCC.
Assuntos
Carcinoma Hepatocelular/metabolismo , Endopeptidases/metabolismo , Proteína de Domínio de Morte Associada a Fas/antagonistas & inibidores , Hepatite/metabolismo , Neoplasias Hepáticas/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/antagonistas & inibidores , Animais , Apoptose/fisiologia , Células CHO , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , Cricetulus , Proteína de Domínio de Morte Associada a Fas/metabolismo , Hepatite/genética , Hepatite/patologia , Humanos , Interferon Tipo I/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Transdução de SinaisRESUMO
Neuroinflammation and neurodegeneration often result from the aberrant deposition of aggregated host proteins, including amyloid-ß, α-synuclein, and prions, that can activate inflammasomes. Inflammasomes function as intracellular sensors of both microbial pathogens and foreign as well as host-derived danger signals. Upon activation, they induce an innate immune response by secreting the inflammatory cytokines interleukin (IL)-1ß and IL-18, and additionally by inducing pyroptosis, a lytic cell death mode that releases additional inflammatory mediators. Microglia are the prominent innate immune cells in the brain for inflammasome activation. However, additional CNS-resident cell types including astrocytes and neurons, as well as infiltrating myeloid cells from the periphery, express and activate inflammasomes. In this review, we will discuss current understanding of the role of inflammasomes in common degenerative diseases of the brain and highlight inflammasome-targeted strategies that may potentially treat these diseases.
Assuntos
Encéfalo/imunologia , Imunidade Inata , Inflamassomos/imunologia , Microglia/imunologia , Doenças Neurodegenerativas/imunologia , Animais , Encéfalo/patologia , Humanos , Interleucina-18/imunologia , Interleucina-1beta/imunologia , Microglia/patologia , Doenças Neurodegenerativas/patologia , alfa-Sinucleína/imunologiaRESUMO
Microglia are the resident macrophages of the central nervous system (CNS). They have important physiological functions in maintaining tissue homeostasis but also contribute to CNS pathology. Microglia respond to changes in the microenvironment, and the resulting reactive phenotype can be very diverse, with both neuroinflammatory and neuroprotective properties, illustrating the plasticity of these cells. Recent progress in understanding the autoimmune neuroinflammatory disease multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis suggests major roles for microglia in the disease, which have drastically changed our view on the function of microglia in MS.
Assuntos
Sistema Nervoso Central/patologia , Inflamação/patologia , Microglia/patologia , Esclerose Múltipla/patologia , Animais , Sistema Nervoso Central/imunologia , Humanos , Inflamação/imunologia , Microglia/imunologia , Esclerose Múltipla/imunologiaRESUMO
Microglia, the mononuclear phagocytes of the central nervous system (CNS), are important for the maintenance of CNS homeostasis, but also critically contribute to CNS pathology. Here we demonstrate that the nuclear factor kappa B (NF-κB) regulatory protein A20 is crucial in regulating microglia activation during CNS homeostasis and pathology. In mice, deletion of A20 in microglia increases microglial cell number and affects microglial regulation of neuronal synaptic function. Administration of a sublethal dose of lipopolysaccharide induces massive microglia activation, neuroinflammation, and lethality in mice with microglia-confined A20 deficiency. Microglia A20 deficiency also exacerbates multiple sclerosis (MS)-like disease, due to hyperactivation of the Nlrp3 inflammasome leading to enhanced interleukin-1ß secretion and CNS inflammation. Finally, we confirm a Nlrp3 inflammasome signature and IL-1ß expression in brain and cerebrospinal fluid from MS patients. Collectively, these data reveal a critical role for A20 in the control of microglia activation and neuroinflammation.
Assuntos
Inflamassomos/imunologia , Microglia/imunologia , Esclerose Múltipla/imunologia , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Encéfalo/imunologia , Encéfalo/patologia , Modelos Animais de Doenças , Feminino , Humanos , Interleucina-1beta/metabolismo , Lipopolissacarídeos/imunologia , Masculino , Camundongos , Microglia/patologia , Pessoa de Meia-Idade , Esclerose Múltipla/líquido cefalorraquidiano , Esclerose Múltipla/patologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Transdução de Sinais/imunologia , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/genética , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/imunologiaRESUMO
Vitiligo is a chronic skin condition characterized by progressive depigmentation of the skin. S100B is a damage-associated molecular pattern protein expressed in melanocytes that has been proposed as a marker of melanocyte cytotoxicity. Although the use of S100B as a biomarker in melanoma is well established, to our knowledge its association with vitiligo activity has not yet been investigated. Here, we show that S100B serum levels were significantly increased in patients with active nonsegmental vitiligo and strongly correlated with the affected body surface area. Prospective follow-up showed a predictive value of serum S100B levels on disease progression. In vitro experiments using repeated freeze-thaw procedures showed an intracellular up-regulation of S100B in normal and vitiligo melanocytes before an extensive release in the environment. This phenomenon may explain the increased S100B serum values in the active phase of vitiligo. In a monobenzone-induced vitiligo mouse model we could show the potential of S100B inhibition as a therapeutic strategy in vitiligo. In conclusion, this report shows the possible use of S100B as a biomarker for disease activity in vitiligo. Our data suggest that this damage-associated molecular pattern protein could play a substantial role in the pathogenesis of vitiligo and may be a potential new target for treatment.
Assuntos
Regulação da Expressão Gênica , RNA/genética , Subunidade beta da Proteína Ligante de Cálcio S100/genética , Adulto , Animais , Biomarcadores/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Ensaio de Imunoadsorção Enzimática , Feminino , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Masculino , Melanócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Estudos Prospectivos , Subunidade beta da Proteína Ligante de Cálcio S100/biossíntese , Vitiligo/metabolismo , Adulto JovemRESUMO
Oxidative stress, a central mediator of cardiovascular disease, results in loss of the prosthetic haem group of soluble guanylate cyclase (sGC), preventing its activation by nitric oxide (NO). Here we introduce Apo-sGC mice expressing haem-free sGC. Apo-sGC mice are viable and develop hypertension. The haemodynamic effects of NO are abolished, but those of the sGC activator cinaciguat are enhanced in apo-sGC mice, suggesting that the effects of NO on smooth muscle relaxation, blood pressure regulation and inhibition of platelet aggregation require sGC activation by NO. Tumour necrosis factor (TNF)-induced hypotension and mortality are preserved in apo-sGC mice, indicating that pathways other than sGC signalling mediate the cardiovascular collapse in shock. Apo-sGC mice allow for differentiation between sGC-dependent and -independent NO effects and between haem-dependent and -independent sGC effects. Apo-sGC mice represent a unique experimental platform to study the in vivo consequences of sGC oxidation and the therapeutic potential of sGC activators.
Assuntos
Sistema Cardiovascular/metabolismo , Guanilato Ciclase/genética , Heme/genética , Músculo Liso Vascular/metabolismo , Óxido Nítrico/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Animais , Benzoatos/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Técnicas de Introdução de Genes , Hipertensão/genética , Hipotensão/induzido quimicamente , Hipotensão/genética , Camundongos , Camundongos Transgênicos , Músculo Liso Vascular/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Guanilil Ciclase Solúvel , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
BACKGROUND: The paracaspase mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is crucial for lymphocyte activation through signaling to the transcription factor NF-κB. Besides functioning as a scaffold signaling protein, MALT1 also acts as a cysteine protease that specifically cleaves a number of substrates and contributes to specific T cell receptor-induced gene expression. Recently, small molecule inhibitors of MALT1 proteolytic activity were identified and shown to have promising anticancer properties in subtypes of B cell lymphoma. However, information on the therapeutic potential of small compound inhibitors that target MALT1 protease activity in autoimmunity is still lacking. METHODS: The present study aimed to elucidate whether MALT1 protease inhibitors are also useful in the treatment of lymphocyte-mediated autoimmune pathologies such as multiple sclerosis (MS). For this, we studied the therapeutic potential of a recently identified inhibitor of MALT1 protease activity, the phenothiazine derivative mepazine, in the context of experimental autoimmune encephalomyelitis (EAE), the main animal model for MS. RESULTS: We demonstrate that administration of mepazine prophylactically or after disease onset, can attenuate EAE. Importantly, while complete absence of MALT1 affects the differentiation of regulatory T (Treg) cells in vivo, the MALT1 protease inhibitor mepazine did not affect Treg development. CONCLUSIONS: Altogether, these data indicate that small molecule inhibitors of MALT1 not only hold great promise for the treatment of B cell lymphomas but also for autoimmune disorders such as MS.