RESUMO
T cells reorganize their metabolic profiles after being activated, but the systemic metabolic effect of sustained activation of the immune system has remained unexplored. Here we report that augmented T cell responses in Pdcd1-/- mice, which lack the inhibitory receptor PD-1, induced a metabolic serum signature characterized by depletion of amino acids. We found that the depletion of amino acids in serum was due to the accumulation of amino acids in activated Pdcd1-/- T cells in the lymph nodes. A systemic decrease in tryptophan and tyrosine led to substantial deficiency in the neurotransmitters serotonin and dopamine in the brain, which resulted in behavioral changes dominated by anxiety-like behavior and exacerbated fear responses. Together these data indicate that excessive activation of T cells causes a systemic metabolomic shift with consequences that extend beyond the immune system.
Assuntos
Ansiedade/fisiopatologia , Comportamento Animal/fisiologia , Medo/fisiologia , Ativação Linfocitária/imunologia , Receptor de Morte Celular Programada 1/genética , Linfócitos T/imunologia , Aminoácidos/sangue , Animais , Encéfalo/metabolismo , Dopamina/deficiência , Interferon gama/sangue , Cinurenina/sangue , Linfonodos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor de Morte Celular Programada 1/deficiência , Serotonina/deficiência , Linfócitos T/metabolismo , Triptofano/metabolismo , Tirosina/metabolismoRESUMO
Disruption of the gut microbiota is thought to contribute to disease onset in individuals with a genetic predisposition to autoimmunity. In a recent issue of Science, Manfredo Vieira et al. (2018) identify translocation of the gut commensal Enterococcus gallinarum into the liver as a trigger for the autoimmune disease systemic lupus erythematous.
Assuntos
Autoimunidade , Lobos , Animais , Galinhas , Feminino , Microbioma Gastrointestinal , Humanos , CamundongosRESUMO
The central nervous system (CNS) is an immunologically privileged site protected from uncontrolled access of T cells by the blood-brain barrier (BBB), which is breached upon autoimmune inflammation. Here we have shown that receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) on T cells regulates C-C type chemokine ligand 20 (CCL20) production by astrocytes and T cell localization in the CNS. Importantly, mice specifically lacking RANKL in T cells were resistant to experimental autoimmune encephalomyelitis (EAE) due to altered T cell trafficking. Pharmacological inhibition of RANKL prevented the development of EAE without affecting the peripheral immune response, indicating that RANKL is a potential therapeutic target for treating autoimmune diseases in the CNS.
Assuntos
Quimiotaxia de Leucócito/imunologia , Encefalomielite Autoimune Experimental/imunologia , Ligante RANK/imunologia , Linfócitos T/imunologia , Animais , Astrócitos/imunologia , Técnicas de Cocultura , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Imuno-Histoquímica , Ativação Linfocitária/imunologia , Camundongos , Camundongos Knockout , Ligante RANK/deficiência , Reação em Cadeia da Polimerase em Tempo RealRESUMO
OBJECTIVE: RANKL is mainly expressed by synovial fibroblasts and T cells within the joints of rheumatoid arthritis patients. The relative importance of RANKL expression by these cell types for the formation of bone erosions is unclear. We therefore aimed to quantify the contribution of RANKL by each cell type to osteoclast differentiation and bone destruction during inflammatory arthritis. METHODS: RANKL was specifically deleted in T cells (Tnfsf11(flox/Δ) Lck-Cre), in collagen VI expressing cells including synovial fibroblasts (Tnfsf11(flox/Δ) Col6a1-Cre) and in collagen II expressing cells including articular chondrocytes (Tnfsf11(flox/Δ) Col2a1-Cre). Erosive disease was induced using the collagen antibody-induced arthritis (CAIA) and collagen-induced arthritis (CIA) models. Osteoclasts and cartilage degradation were assessed by histology and bone erosions were assessed by micro-CT. RESULTS: The inflammatory joint score during CAIA was equivalent in all mice regardless of cell-targeted deletion of RANKL. Significant increases in osteoclast numbers and bone erosions were observed in both the Tnfsf11(flox/Δ) and the Tnfsf11(flox/Δ) Lck-Cre groups during CAIA; however, the Tnfsf11(flox/Δ) Col6a1-Cre mice showed significant protection against osteoclast formation and bone erosions. Similar results on osteoclast formation and bone erosions were obtained in CIA mice. The deletion of RANKL on any cell type did not prevent articular cartilage loss in either model of arthritis used. CONCLUSIONS: The expression of RANKL on synovial fibroblasts rather than T cells is predominantly responsible for the formation of osteoclasts and erosions during inflammatory arthritis. Synovial fibroblasts would be the best direct target in RANKL inhibition therapies.
Assuntos
Artrite Experimental/metabolismo , Reabsorção Óssea/metabolismo , Fibroblastos/metabolismo , Ligante RANK/metabolismo , Membrana Sinovial/metabolismo , Animais , Artrite Experimental/imunologia , Artrite Experimental/patologia , Remodelação Óssea/fisiologia , Reabsorção Óssea/etiologia , Reabsorção Óssea/patologia , Linfócitos T CD4-Positivos/imunologia , Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Diferenciação Celular , Condrócitos/metabolismo , Deleção de Genes , Masculino , Camundongos Endogâmicos C57BL , Osteoclastos/patologia , Ligante RANK/genéticaRESUMO
Autosomal recessive osteopetrosis is usually associated with normal or elevated numbers of nonfunctional osteoclasts. Here we report mutations in the gene encoding RANKL (receptor activator of nuclear factor-KB ligand) in six individuals with autosomal recessive osteopetrosis whose bone biopsy specimens lacked osteoclasts. These individuals did not show any obvious defects in immunological parameters and could not be cured by hematopoietic stem cell transplantation; however, exogenous RANKL induced formation of functional osteoclasts from their monocytes, suggesting that they could, theoretically, benefit from exogenous RANKL administration.
Assuntos
Osteopetrose/genética , Ligante RANK/genética , Animais , Consanguinidade , Feminino , Genes Recessivos , Humanos , Masculino , Camundongos , Osteoclastos , LinhagemRESUMO
Bone and immune systems are tightly linked. In the past years, many molecules originally believed to belong to the immune system were found to function in bone cells. It is now evident that the two systems are coregulated by many shared cytokines and signaling molecules. Here we exemplify the complex interaction between bone metabolism and immune response focusing on the multifaceted role of receptor activator of NF-κB ligand (RANKL). RANKL is expressed by cells of both systems, is an essential regulator of bone degradation and exerts either pro or anti-inflammatory effects on the immune response. In the present review, we summarize the multiple functions of RANKL in bone and in the immune systems, aiming to provide an overview of the field of osteoimmunology.
Assuntos
Artrite Reumatoide/imunologia , Osso e Ossos/imunologia , Citocinas/imunologia , Imunidade Inata/imunologia , Linfócitos/imunologia , Ligante RANK/imunologia , Animais , Artrite Reumatoide/patologia , Humanos , Modelos ImunológicosRESUMO
Autosomal-Recessive Osteopetrosis (ARO) comprises a heterogeneous group of bone diseases for which mutations in five genes are known as causative. Most ARO are classified as osteoclast-rich, but recently a subset of osteoclast-poor ARO has been recognized as due to a defect in TNFSF11 (also called RANKL or TRANCE, coding for the RANKL protein), a master gene driving osteoclast differentiation along the RANKL-RANK axis. RANKL and RANK (coded for by the TNFRSF11A gene) also play a role in the immune system, which raises the possibility that defects in this pathway might cause osteopetrosis with immunodeficiency. From a large series of ARO patients we selected a Turkish consanguineous family with two siblings affected by ARO and hypogammaglobulinemia with no defects in known osteopetrosis genes. Sequencing of genes involved in the RANKL downstream pathway identified a homozygous mutation in the TNFRSF11A gene in both siblings. Their monocytes failed to differentiate in vitro into osteoclasts upon exposure to M-CSF and RANKL, in keeping with an osteoclast-intrinsic defect. Immunological analysis showed that their hypogammaglobulinemia was associated with impairment in immunoglobulin-secreting B cells. Investigation of other patients revealed a defect in both TNFRSF11A alleles in six additional, unrelated families. Our results indicate that TNFRSF11A mutations can cause a clinical condition in which severe ARO is associated with an immunoglobulin-production defect.
Assuntos
Agamaglobulinemia/sangue , Osteoclastos/patologia , Osteopetrose/genética , Receptor Ativador de Fator Nuclear kappa-B/genética , Fosfatase Ácida/metabolismo , Actinas/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Argentina , Arginina/metabolismo , Biópsia , Estudos de Casos e Controles , Linhagem Celular Transformada , Proliferação de Células , Transformação Celular Viral , Células Cultivadas , Estudos de Coortes , Consanguinidade , Cisteína/metabolismo , Análise Mutacional de DNA , Dendritos/fisiologia , Feminino , Genes Recessivos , Herpesvirus Humano 4/fisiologia , Heterozigoto , Homozigoto , Humanos , Ílio/cirurgia , Isoenzimas/metabolismo , Antígenos Comuns de Leucócito/metabolismo , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/patologia , Lipopolissacarídeos/farmacologia , Fator Estimulador de Colônias de Macrófagos/farmacologia , Masculino , Modelos Imunológicos , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Osteoclastos/metabolismo , Osteoclastos/ultraestrutura , Osteopetrose/diagnóstico , Osteopetrose/diagnóstico por imagem , Osteopetrose/patologia , Osteopetrose/fisiopatologia , Osteoprotegerina/metabolismo , Paquistão , Linhagem , Polimorfismo Genético , Estrutura Terciária de Proteína , Ligante RANK/metabolismo , Radiografia Torácica/métodos , Receptor Ativador de Fator Nuclear kappa-B/química , Receptor Ativador de Fator Nuclear kappa-B/imunologia , Receptores de Vitronectina/metabolismoRESUMO
Human recessive osteopetrosis (ARO) represents a group of diseases in which, due to a defect in osteoclasts, bone resorption is prevented. The deficit could arise either from failure in osteoclast differentiation or from inability to perform resorption by mature, multinucleated, but nonfunctional cells. Historically, osteopetrosis due to both these mechanisms was found in spontaneous and artificially created mouse mutants, but the first five genes identified in human ARO (CA-II, TCIRG1, ClCN7, OSTM1, and PLEKHM1) were all involved in the effector function of mature osteoclasts, being linked to acidification of the cell/bone interface or to intracellular processing of the resorbed material. Differentiation defects in human ARO have only recently been described, following the identification of mutations in both RANKL and RANK, which define a new form of osteoclast-poor ARO, as expected from biochemical, cellular, and animal studies. The molecular dissection of ARO has prognostic and therapeutic implications. RANKL-dependent patients, in particular, represent an interesting subset which could benefit from mesenchymal cell transplant and/or administration of soluble RANKL cytokine.
Assuntos
Osteoclastos/patologia , Osteopetrose/genética , Osteopetrose/patologia , Ligante RANK/genética , Receptor Ativador de Fator Nuclear kappa-B/genética , Animais , Diferenciação Celular/genética , Criança , Humanos , Lactente , Camundongos , Osteoclastos/metabolismo , Osteopetrose/metabolismo , Osteopetrose/terapiaRESUMO
Monoamine neurotransmitters are released by specialized neurons regulating behavioral, motor, and cognitive functions. Although the localization of monoaminergic neurons in the brain is well known, the distribution and kinetics of monoamines remain unclear. Here, we generated a murine brain atlas of serotonin (5-HT), dopamine (DA), and norepinephrine (NE) levels using mass spectrometry imaging (MSI). We found several nuclei rich in both 5-HT and a catecholamine (DA or NE) and identified the paraventricular nucleus of the thalamus (PVT), where 5-HT and NE are co-localized. The analysis of 5-HT fluctuations in response to acute tryptophan depletion and infusion of isotope-labeled tryptophan in vivo revealed a close kinetic association between the raphe nuclei, PVT, and amygdala but not the other nuclei. Our findings imply the existence of a highly dynamic 5-HT-mediated raphe to PVT pathway that likely plays a role in the brain monoamine system.
RESUMO
Many studies describe dysbiosis as a change in the microbiota that accompanies autoimmune illnesses, but little is known about whether these changes are a cause or consequence of an altered immune state. The immune system actively shapes the composition of the microbiota, with divergent outcomes in healthy or autoimmune-prone individuals. The gut microbiota in turn acts as an acquired endocrine organ, influencing the physiology of the host via release of nutrients and chemical messengers. Dysbiosis arising from abnormal immune function can initiate or amplify autoimmunity through multiple mechanisms. We examine how the bidirectional relationship between resident microbes and the immune system contributes to autoimmune diseases.
Assuntos
Autoimunidade/imunologia , Microbioma Gastrointestinal/imunologia , Animais , Doenças Autoimunes/imunologia , Disbiose/imunologia , HumanosRESUMO
Autosomal recessive osteopetrosis (ARO) is a genetically heterogeneous disorder attributed to reduced bone resorption by osteoclasts. Most human AROs are classified as osteoclast rich, but recently two subsets of osteoclast-poor ARO have been recognized as caused by defects in either TNFSF11 or TNFRSF11A genes, coding the RANKL and RANK proteins, respectively. The RANKL/RANK axis drives osteoclast differentiation and also plays a role in the immune system. In fact, we have recently reported that mutations in the TNFRSF11A gene lead to osteoclast-poor osteopetrosis associated with hypogammaglobulinemia. Here we present the characterization of five additional unpublished patients from four unrelated families in which we found five novel mutations in the TNFRSF11A gene, including two missense and two nonsense mutations and a single-nucleotide insertion. Immunological investigation in three of them showed that the previously described defect in the B cell compartment was present only in some patients and that its severity seemed to increase with age and the progression of the disease. HSCT performed in all five patients almost completely cured the disease even when carried out in late infancy. Hypercalcemia was the most important posttransplant complication. Overall, our results further underline the heterogeneity of human ARO also deriving from the interplay between bone and the immune system, and highlight the prognostic and therapeutic implications of the molecular diagnosis.
Assuntos
Mutação/genética , Osteopetrose/congênito , Receptor Ativador de Fator Nuclear kappa-B/genética , Sequência de Aminoácidos , Linfócitos B/metabolismo , Compartimento Celular , Diferenciação Celular , Feminino , Seguimentos , Transplante de Células-Tronco Hematopoéticas , Humanos , Lactente , Recém-Nascido , Masculino , Dados de Sequência Molecular , Osteoclastos/patologia , Osteopetrose/genética , Receptor Ativador de Fator Nuclear kappa-B/químicaRESUMO
In the last decades the molecular basis of monogenic diseases has been largely unraveled, although their treatment has often remained unsatisfactory. Autosomal recessive osteopetrosis (ARO) belongs to the small group of genetic diseases that are usually treated with hematopoietic stem cell transplantation (HSCT). However, this approach is not effective in the recently identified form carrying mutations in the receptor activator of NF-κB ligand (RANKL) gene. In this subset, therapy replacement approach based on RANKL delivery has a strong rationale. Here we demonstrate that the systematic administration of RANKL for 1 month to Rankl(-/-) mice, which closely resemble the human disease, significantly improves the bone phenotype and has beneficial effects on bone marrow, spleen and thymus; major adverse effects arise only when mice are clearly overtreated. Overall, we provide evidence that the pharmacological administration of RANKL represents the appropriate treatment option for RANKL-deficient ARO patients, to be validated in a pilot clinical trial.
Assuntos
Osteopetrose/tratamento farmacológico , Osteopetrose/genética , Ligante RANK/uso terapêutico , Animais , Células da Medula Óssea/efeitos dos fármacos , Reabsorção Óssea/induzido quimicamente , Osso e Ossos/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Osteopetrose/patologia , Fenótipo , Ligante RANK/administração & dosagem , Ligante RANK/efeitos adversos , Ligante RANK/genética , Receptor Ativador de Fator Nuclear kappa-B/deficiência , Receptor Ativador de Fator Nuclear kappa-B/genéticaRESUMO
Adenosine deaminase (ADA) deficiency is caused by a purine metabolic dysfunction, leading to severe combined immunodeficiency (SCID) and multiple organ damage. To investigate the efficacy of ex vivo gene therapy with self-inactivating lentiviral vectors (LVs) in correcting this complex phenotype, we used an ADA(-/-) mouse model characterized by early postnatal lethality. LV-mediated ADA gene transfer into bone marrow cells combined with low-dose irradiation rescued mice from lethality and restored their growth, as did transplantation of wild-type bone marrow. Mixed chimerism with multilineage engraftment of transduced cells was detected in the long term in animals that underwent transplantation. ADA activity was normalized in lymphocytes and partially corrected in red blood cells (RBCs), resulting in full metabolic detoxification and prevention of severe pulmonary insufficiency. Moreover, gene therapy restored normal lymphoid differentiation and immune functions, including antigen-specific antibody production. Similar degrees of detoxification and immune reconstitution were obtained in mice treated early after birth or after 1 month of enzyme-replacement therapy, mimicking 2 potential applications for ADA-SCID. Overall, this study demonstrates the efficacy of LV gene transfer in correcting both the immunological and metabolic phenotypes of ADA-SCID and supports the future clinical use of this approach.