RESUMO
Upon detecting pathogens or cell stress, several NOD-like receptors (NLRs) form inflammasome complexes with the adapter ASC and caspase-1, inducing gasdermin D (GSDMD)-dependent cell death and maturation and release of IL-1ß and IL-18. The triggers and activation mechanisms of several inflammasome-forming sensors are not well understood. Here we show that mitochondrial damage activates the NLRP10 inflammasome, leading to ASC speck formation and caspase-1-dependent cytokine release. While the AIM2 inflammasome can also sense mitochondrial demise by detecting mitochondrial DNA (mtDNA) in the cytosol, NLRP10 monitors mitochondrial integrity in an mtDNA-independent manner, suggesting the recognition of distinct molecular entities displayed by the damaged organelles. NLRP10 is highly expressed in differentiated human keratinocytes, in which it can also assemble an inflammasome. Our study shows that this inflammasome surveils mitochondrial integrity. These findings might also lead to a better understanding of mitochondria-linked inflammatory diseases.
Assuntos
Citocinas , Inflamassomos , Humanos , Inflamassomos/metabolismo , Caspase 1/metabolismo , Citocinas/metabolismo , Morte Celular , DNA Mitocondrial/genética , Interleucina-1beta/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismoRESUMO
The receptor interacting serine/threonine kinase 2 (RIPK2) is essential for signal transduction induced by the pattern recognition receptors NOD1 and NOD2 (referred to collectively as NOD1/2). Upon NOD1/2 activation, RIPK2 forms complexes in the cytoplasm of human cells. Here, we identified the molecular composition of these complexes. Infection with Shigella flexneri to activate NOD1-RIPK2 revealed that RIPK2 formed dynamic interactions with several cellular proteins, including A20 (also known as TNFAIP3), erlin-1, erlin-2 and 14-3-3. Whereas interaction of RIPK2 with 14-3-3 proteins was strongly reduced upon infection with Shigella, erlin-1 and erlin-2 (erlin-1/2) specifically bound to RIPK2 complexes. The interaction of these proteins with RIPK2 was validated using protein binding assays and immunofluorescence staining. Beside bacterial activation of NOD1/2, depletion of the E3 ubiquitin ligase XIAP and treatment with RIPK2 inhibitors also led to the formation of RIPK2 cytosolic complexes. Although erlin-1/2 were recruited to RIPK2 complexes following XIAP inhibition, these proteins did not associate with RIPK2 structures induced by RIPK2 inhibitors. While the specific recruitment of erlin-1/2 to RIPK2 suggests a role in innate immune signaling, the biological response regulated by the erlin-1/2-RIPK2 association remains to be determined.
Assuntos
Proteína Adaptadora de Sinalização NOD2 , Proteína Serina-Treonina Quinase 2 de Interação com Receptor , Proteínas 14-3-3 , Citosol/metabolismo , Humanos , Proteína Adaptadora de Sinalização NOD1 , Proteína Adaptadora de Sinalização NOD2/genética , Proteína Adaptadora de Sinalização NOD2/metabolismo , Ligação Proteica , Proteína Serina-Treonina Quinase 2 de Interação com Receptor/genética , Proteína Serina-Treonina Quinase 2 de Interação com Receptor/metabolismo , Transdução de SinaisRESUMO
NOD-like receptors (NLR) are critical regulators of innate immune signaling. The NLR family consists of 22 human proteins with a conserved structure containing a central oligomerization NACHT domain, an N-terminal interaction domain, and a variable number of C-terminal leucine-rich repeats. Most NLR proteins function as cytosolic pattern recognition receptors with activation of downstream inflammasome signaling, NF-κB, or MAPK activation. Although NLRP10 is the only NLR protein lacking the leucine rich repeats, it has been implicated in multiple immune pathways, including the regulation of inflammatory responses toward Leishmania major and Shigella flexneri infection. In this study, we identify Abin-1, a negative regulator of NF-κB, as an interaction partner of NLRP10 that binds to the NACHT domain of NLRP10. Using S. flexneri as an infection model in human epithelial cells, our work reveals a novel function of NLRP10 in destabilizing Abin-1, resulting in enhanced proinflammatory signaling. Our data give insight into the molecular mechanism underlying the function of NLRP10 in innate immune responses.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ligação a DNA/metabolismo , Disenteria Bacilar/imunologia , Células Epiteliais/fisiologia , Inflamação/imunologia , Shigella flexneri/fisiologia , Animais , Proteínas Reguladoras de Apoptose/genética , Células HEK293 , Humanos , Imunidade Inata , Inflamassomos/metabolismo , Camundongos , Camundongos Knockout , NF-kappa B/metabolismo , Ligação Proteica , Estabilidade Proteica , Transdução de SinaisRESUMO
Type I interferon signaling contributes to the development of innate and adaptive immune responses to either viruses, fungi, or bacteria. However, amplitude and timing of the interferon response is of utmost importance for preventing an underwhelming outcome, or tissue damage. While several pathogens evolved strategies for disturbing the quality of interferon signaling, there is growing evidence that this pathway can be regulated by several members of the Nod-like receptor (NLR) family, although the precise mechanism for most of these remains elusive. NLRs consist of a family of about 20 proteins in mammals, which are capable of sensing microbial products as well as endogenous signals related to tissue injury. Here we provide an overview of our current understanding of the function of those NLRs in type I interferon responses with a focus on viral infections. We discuss how NLR-mediated type I interferon regulation can influence the development of auto-immunity and the immune response to infection.
Assuntos
Interferon Tipo I/metabolismo , Proteínas NLR/metabolismo , Viroses/metabolismo , Imunidade Adaptativa , Animais , Humanos , Imunidade Inata , Transdução de SinaisRESUMO
Graft-versus-host disease (GVHD) represents the major nonrelapse complication of allogeneic hematopoietic cell transplantation. Although rare, the CNS and the eye can be affected. In this study, manifestation in the retina as part of the CNS and T-cell epitopes recognized by the allogeneic T cells were evaluated. In 2 of 6 patients with posttransplantation retina diseases and 6 of 22 patients without ocular symptoms, antigen-specific T-cell responses against retina-specific epitopes were observed. No genetic differences between donor and recipient could be identified indicating T-cell activation against self-antigens (graft versus self). Transplantation of a preexisting immunity and cross-reactivity with ubiquitous epitopes was excluded in family donors and healthy individuals. In summary, an immunological reaction against retina cells represents a mechanism of graft-versus-host interaction following hematopoietic cell transplantation.
Assuntos
Autoantígenos/imunologia , Epitopos de Linfócito T/imunologia , Doença Enxerto-Hospedeiro/imunologia , Doenças Retinianas/imunologia , Adulto , Idoso , Feminino , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/patologia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Ativação Linfocitária/imunologia , Masculino , Pessoa de Meia-Idade , Doenças Retinianas/etiologia , Doenças Retinianas/patologia , Linfócitos T/imunologia , Transplante Homólogo/efeitos adversosRESUMO
Tight regulation of inflammatory cytokine and interferon (IFN) production in innate immunity is pivotal for optimal control of pathogens and avoidance of immunopathology. The human Nod-like receptor (NLR) NLRP11 has been shown to regulate type I IFN and pro-inflammatory cytokine responses. Here, we identified the ATP-dependent RNA helicase DDX3X as a novel binding partner of NLRP11, using co-immunoprecipitation and LC-MS/MS. DDX3X is known to enhance type I IFN responses and NLRP3 inflammasome activation. We demonstrate that NLRP11 can abolish IKKϵ-mediated phosphorylation of DDX3X, resulting in lower type I IFN induction upon viral infection. These effects were dependent on the LRR domain of NLRP11 that we mapped as the interaction domain for DDX3X. In addition, NLRP11 also suppressed NLRP3-mediated caspase-1 activation in an LRR domain-dependent manner, suggesting that NLRP11 might sequester DDX3X and prevent it from promoting NLRP3-induced inflammasome activation. Taken together, our data revealed DDX3X as a central target of NLRP11, which can mediate the effects of NLRP11 on type I IFN induction as well as NLRP3 inflammasome activation. This expands our knowledge of the molecular mechanisms underlying NLRP11 function in innate immunity and suggests that both NLRP11 and DDX3X might be promising targets for modulation of innate immune responses.
Assuntos
RNA Helicases DEAD-box/metabolismo , Inflamassomos/metabolismo , Interferon Tipo I/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas NLR/metabolismo , Cromatografia Líquida , Citocinas/metabolismo , Humanos , Imunidade Inata , Mediadores da Inflamação , Ligação Proteica , Espectrometria de Massas em TandemRESUMO
Background: Meal skipping has become an increasing trend of the modern lifestyle that may lead to obesity and type 2 diabetes.Objective: We investigated whether the timing of meal skipping impacts these risks by affecting circadian regulation of energy balance, glucose metabolism, and postprandial inflammatory responses.Design: In a randomized controlled crossover trial, 17 participants [body mass index (in kg/m2): 23.7 ± 4.6] underwent 3 isocaloric 24-h interventions (55%, 30%, and 15% carbohydrate, fat, and protein, respectively): a breakfast skipping day (BSD) and a dinner skipping day (DSD) separated by a conventional 3-meal-structure day (control). Energy and macronutrient balance was measured in a respiration chamber. Postprandial glucose, insulin, and inflammatory responses in leukocytes as well as 24-h glycemia and insulin secretion were analyzed.Results: When compared with the 3-meal control, 24-h energy expenditure was higher on both skipping days (BSD: +41 kcal/d; DSD: +91 kcal/d; both P < 0.01), whereas fat oxidation increased on the BSD only (+16 g/d; P < 0.001). Spontaneous physical activity, 24-h glycemia, and 24-h insulin secretion did not differ between intervention days. The postprandial homeostasis model assessment index (+54%) and glucose concentrations after lunch (+46%) were, however, higher on the BSD than on the DSD (both P < 0.05). Concomitantly, a longer fasting period with breakfast skipping also increased the inflammatory potential of peripheral blood cells after lunch.Conclusions: Compared with 3 meals/d, meal skipping increased energy expenditure. In contrast, higher postprandial insulin concentrations and increased fat oxidation with breakfast skipping suggest the development of metabolic inflexibility in response to prolonged fasting that may in the long term lead to low-grade inflammation and impaired glucose homeostasis. This trial was registered at clinicaltrials.gov as NCT02635139.
Assuntos
Desjejum , Ritmo Circadiano , Diabetes Mellitus Tipo 2/etiologia , Metabolismo Energético , Comportamento Alimentar/fisiologia , Refeições , Obesidade/etiologia , Adulto , Glicemia/metabolismo , Índice de Massa Corporal , Estudos Cross-Over , Diabetes Mellitus Tipo 2/sangue , Exercício Físico , Jejum , Feminino , Homeostase , Humanos , Hiperglicemia/etiologia , Inflamação/etiologia , Insulina/metabolismo , Secreção de Insulina , Leucócitos Mononucleares/metabolismo , Lipólise , Almoço , Masculino , Obesidade/metabolismo , Período Pós-Prandial , Fatores de Risco , Adulto JovemRESUMO
PURPOSE: Prolonged aplasia and graft failure (GF) represent life-threatening complications after hematopoietic cell transplantation (HCT) requiring suitable biomarkers for early detection and differentiation between GF and poor graft function (PGF). Uric acid (UA) is a strong immunological danger signal. METHODS: Laboratory results were analyzed from patients undergoing either allogeneic or autologous HCT or induction chemotherapy for acute leukemia (n = 50 per group, n = 150 total). RESULTS: During therapy, UA levels declined from normal values to hypouricemic values (all p < 0.001). Alongside hematopoietic recovery, UA serum levels returned to baseline values. During aplasia, UA levels remained low and started steadily increasing (defined as >two consecutive days, median one 2-day increase) at a median of 1 day before rising leukocytes in allogeneic HCT (p = 0.01) and together with leukocytes in autologous HCT (median one 2-day increase). During induction chemotherapy, a UA increase was also observed alongside rising leukocytes/neutrophils but also several times during aplasia (median 3 increases). Most HCT patients had no detectable leukocytes during aplasia, while some leukocytes remained detectable after induction therapy. No increase in UA levels was observed without concomitant or subsequent rise of leukocytes. CONCLUSIONS: Changes in UA serum levels can indicate incipient or remaining immunological activity after HCT or induction therapy. They may, therefore, help to differentiate between PGF and GF.
Assuntos
Anemia/sangue , Biomarcadores Tumorais/sangue , Medula Óssea/fisiopatologia , Transplante de Células-Tronco Hematopoéticas/métodos , Leucemia Mieloide Aguda/sangue , Leucemia Mieloide Aguda/terapia , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangue , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Ácido Úrico/sangue , Adulto , Idoso , Anemia/etiologia , Anemia/imunologia , Anemia/patologia , Contagem de Células Sanguíneas , Medula Óssea/imunologia , Medula Óssea/patologia , Feminino , Sobrevivência de Enxerto/imunologia , Sobrevivência de Enxerto/fisiologia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/patologia , Masculino , Pessoa de Meia-Idade , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Adulto JovemRESUMO
BACKGROUND: Heat shock proteins (HSP) are highly conserved immunogenic proteins serving as potent danger signals. They are upregulated under stress conditions like fever and hypoxia. Extracellular HSP are involved in antigen presentation, cytokine release and maturation of antigen presenting cells. METHODS: The release of the inducible members of the HSP70 family, Hsp72 and Hsp70B', into the serum of 20 patients undergoing allogeneic hematopoietic cell transplantation and 20 healthy donors was evaluated using enzyme linked immunosorbent assay (ELISA) kits. RESULTS: Eight patients (40%) did not receive anti-thymocyte globulin (ATG) for prophylaxis of graft versus host disease (GvHD). These patients had no detectable or low serum levels of Hsp72 (n=3, 0.03 to 1.92ng/ml) which were in line with levels detected in 20 healthy individuals (p=0.07). Measurable HSP was not associated with any medication or transplantation-related procedures. In twelve patients (60%) receiving ATG, detected high levels of HSP reflected cross-reactivity of the rabbit-derived ATG with the anti-rabbit antibody used in the ELISA. CONCLUSIONS: Assumed HSP70 expression detected such ELISA has to be regarded carefully after ATG application. Neither radiochemotherapy, nor inflammation or sepsis during aplasia induced HSP70 release into the serum. Thus, soluble HSP70 may not be involved in the pathogenesis of acute GvHD.
Assuntos
Biomarcadores/sangue , Doença Enxerto-Hospedeiro/diagnóstico , Proteínas de Choque Térmico HSP70/sangue , Proteínas de Choque Térmico HSP72/sangue , Transplante de Células-Tronco Hematopoéticas , Adulto , Idoso , Animais , Reações Cruzadas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Coelhos , Transplante HomólogoRESUMO
The epidermal growth factor receptor HER2/neu is expressed on various cancers and represents a negative prognostic marker, but is also a target for the therapeutic monoclonal antibody Trastuzumab. In about 30% of cases, HER2/neu is expressed on acute lymphoblastic leukemia (ALL) cells and was proposed to be associated with a deleterious prognosis. Here we evaluated clinical data from 65 ALL patients (HER2/neu+, n = 17; HER2/neu-, n = 48) with a median follow-up of 19.4 months (range 0.6-176.5 months) and observed no association of HER2/neu expression with response to chemotherapy, disease free or overall survival. In vitro, treatment of primary ALL cells (CD20+HER2/neu+, CD20+HER2/neu- and CD20-HER2/neu-) with Rituximab and Trastuzumab led to activation of NK cells in strict dependence of the expression of the respective antigen. NK reactivity was more pronounced with Rituximab as compared to Trastuzumab, and combined application could lead to additive effects in cases where both antigens were expressed. Besides providing evidence that HER2/neu expression is no risk factor in ALL patients, our data demonstrates that HER2/neu can be a promising target for Trastuzumab therapy in the subset of ALL patients with the potential to improve disease outcome.