RESUMEN
Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to systemic and articular bone loss by activating bone resorption and suppressing bone formation. Despite current therapeutic agents, inflammation-induced bone loss in RA continues to be a significant clinical problem due to joint deformity and lack of articular and systemic bone repair. Here, we identify the suppressor of bone formation, Schnurri-3 (SHN3), as a potential target to prevent bone loss in RA. SHN3 expression in osteoblast-lineage cells is induced by proinflammatory cytokines. Germline deletion or conditional deletion of Shn3 in osteoblasts limits articular bone erosion and systemic bone loss in mouse models of RA. Similarly, silencing of SHN3 expression in these RA models using systemic delivery of a bone-targeting recombinant adenoassociated virus protects against inflammation-induced bone loss. In osteoblasts, TNF activates SHN3 via ERK MAPK-mediated phosphorylation and, in turn, phosphorylated SHN3 inhibits WNT/ß-catenin signaling and up-regulates RANKL expression. Accordingly, knock-in of a mutation in Shn3 that fails to bind ERK MAPK promotes bone formation in mice overexpressing human TNF due to augmented WNT/ß-catenin signaling. Remarkably, Shn3-deficient osteoblasts are not only resistant to TNF-induced suppression of osteogenesis, but also down-regulate osteoclast development. Collectively, these findings demonstrate SHN3 inhibition as a promising approach to limit bone loss and promote bone repair in RA.
Asunto(s)
Artritis Reumatoide , Resorción Ósea , Ratones , Humanos , Animales , beta Catenina/metabolismo , Proteínas de Unión al ADN/metabolismo , Huesos/metabolismo , Osteoblastos/metabolismo , Osteogénesis/genética , Artritis Reumatoide/genética , Artritis Reumatoide/metabolismo , Resorción Ósea/metabolismo , Inflamación/metabolismo , Osteoclastos/metabolismoRESUMEN
The AM14 BCR, derived from an autoimmune MRL/lpr mouse, binds autologous IgG2aa/j with low affinity, and as a result, AM14 B cells only proliferate in response to IgG2a immune complexes that incorporate DNA, RNA, or nucleic acid-binding proteins that serve as autoadjuvants. As such, AM14 B cells have served as a useful model for demonstrating the importance of BCR/TLR coengagement in the activation of autoreactive B cells. We now show that the same receptor recognizes an additional murine-encoded Ag, expressed by B6 splenocytes, with sufficient avidity to induce a TLR-independent proliferative response of BALB/c AM14 Vκ8 B cells both in vivo and in vitro. Moreover, detection of this cross-reactive Ag by B6 AM14 Vκ8 B cells promotes an anergic phenotype as reflected by suboptimal responses to BCR cross-linking and the absence of mature B cells in the bone marrow. The B6 Ag further impacts B cell development as shown by a dramatically expanded marginal zone compartment and extensive receptor editing in B6 AM14 Vκ8 mice but not BALB/c AM14 Vκ8 mice. Despite their anergic phenotypes, B6 AM14 Vκ8 B cells can respond robustly to autoantigen/autoadjuvant immune complexes and could therefore participate in both autoimmune responses and host defense.
RESUMEN
Detection of endogenous nucleic acids by cytosolic receptors, dependent on STING, and endosomal sensors, dependent on Unc93b1, can provoke inflammatory responses that contribute to a variety of autoimmune and autoinflammatory diseases. In DNase II-deficient mice, the excessive accrual of undegraded DNA leads to both a STING-dependent inflammatory arthritis and additional Unc93b1-dependent autoimmune manifestations, including splenomegaly, extramedullary hematopoiesis, and autoantibody production. In this study, we use bone marrow chimeras to show that clinical and histological inflammation in the joint depends upon DNase II deficiency in both donor hematopoietic cells and host radioresistant cells. Additional features of autoimmunity in these mice, known to depend on Unc93b1 and therefore endosomal TLRs, also require DNase II deficiency in both donor and host compartments, but only require functional TLRs in the hematopoietic cells. Collectively, our data demonstrate a major role of both stromal and hematopoietic cells in all aspects of DNA-driven autoimmunity. These findings further point to the importance of cytosolic nucleic acid sensors in creating an inflammatory environment that facilitates the development of Unc93b1-dependent autoimmunity.
Asunto(s)
Artritis Experimental/inmunología , Autoinmunidad/inmunología , Células Madre Hematopoyéticas/inmunología , Células del Estroma/inmunología , Animales , Modelos Animales de Enfermedad , Endodesoxirribonucleasas/deficiencia , Endodesoxirribonucleasas/inmunología , Citometría de Flujo , Proteínas de la Membrana/inmunología , Proteínas de Transporte de Membrana/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Quimera por RadiaciónRESUMEN
Systemic lupus erythematosus (SLE) is a chronic, life-threatening autoimmune disorder, leading to multiple organ pathologies and kidney destruction. Analyses of numerous murine models of spontaneous SLE have revealed a critical role for endosomal TLRs in the production of autoantibodies and development of other clinical disease manifestations. Nevertheless, the corresponding TLR9-deficient autoimmune-prone strains consistently develop more severe disease pathology. Injection of BALB/c mice with 2,6,10,14-tetramethylpentadecane (TMPD), commonly known as pristane, also results in the development of SLE-like disease. We now show that Tlr9(-/-) BALB/c mice injected i.p. with TMPD develop more severe autoimmunity than do their TLR-sufficient cohorts. Early indications include an increased accumulation of TLR7-expressing Ly6C(hi) inflammatory monocytes at the site of injection, upregulation of IFN-regulated gene expression in the peritoneal cavity, and an increased production of myeloid lineage precursors (common myeloid progenitors and granulocyte myeloid precursors) in the bone marrow. TMPD-injected Tlr9(-/-) BALB/c mice develop higher autoantibody titers against RNA, neutrophil cytoplasmic Ags, and myeloperoxidase than do TMPD-injected wild-type BALB/c mice. The TMP-injected Tlr9(-/-) mice, and not the wild-type mice, also develop a marked increase in glomerular IgG deposition and infiltrating granulocytes, much more severe glomerulonephritis, and a reduced lifespan. Collectively, the data point to a major role for TLR7 in the response to self-antigens in this model of experimental autoimmunity. Therefore, the BALB/c pristane model recapitulates other TLR7-driven spontaneous models of SLE and is negatively regulated by TLR9.
Asunto(s)
Linaje de la Célula , Nefritis Lúpica/patología , Células Mieloides/patología , Receptor Toll-Like 9/deficiencia , Animales , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Ensayo de Immunospot Ligado a Enzimas , Citometría de Flujo , Inmunosupresores/toxicidad , Nefritis Lúpica/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Células Mieloides/inmunología , Reacción en Cadena de la Polimerasa , Terpenos/toxicidadRESUMEN
Cytosolic DNA-sensing pathways that signal via Stimulator of interferon genes (STING) mediate immunity to pathogens and also promote autoimmune pathology in DNaseII- and DNaseIII-deficient mice. In contrast, we report here that STING potently suppresses inflammation in a model of systemic lupus erythematosus (SLE). Lymphoid hypertrophy, autoantibody production, serum cytokine levels, and other indicators of immune activation were markedly increased in STING-deficient autoimmune-prone mice compared with STING-sufficient littermates. As a result, STING-deficient autoimmune-prone mice had significantly shorter lifespans than controls. Importantly, Toll-like receptor (TLR)-dependent systemic inflammation during 2,6,10,14-tetramethylpentadecane (TMPD)-mediated peritonitis was similarly aggravated in STING-deficient mice. Mechanistically, STING-deficient macrophages failed to express negative regulators of immune activation and thus were hyperresponsive to TLR ligands, producing abnormally high levels of proinflammatory cytokines. This hyperreactivity corresponds to dramatically elevated numbers of inflammatory macrophages and granulocytes in vivo. Collectively these findings reveal an unexpected negative regulatory role for STING, having important implications for STING-directed therapies.
Asunto(s)
Autoinmunidad/fisiología , Proteínas de la Membrana/fisiología , Animales , Autoanticuerpos/biosíntesis , Células Dendríticas/inmunología , Regulación de la Expresión Génica/fisiología , Factor 3 Regulador del Interferón/genética , Factor 3 Regulador del Interferón/fisiología , Interferones/fisiología , Activación de Linfocitos , Proteínas de la Membrana/genética , RatonesRESUMEN
In mice that fail to express the phagolysosomal endonuclease DNase II and the type I IFN receptor, excessive accrual of undegraded DNA results in a STING-dependent, TLR-independent inflammatory arthritis. These double-knockout (DKO) mice develop additional indications of systemic autoimmunity, including anti-nuclear autoantibodies and splenomegaly, that are not found in Unc93b1(3d/3d) DKO mice and, therefore, are TLR dependent. The DKO autoantibodies predominantly detect RNA-associated autoantigens, which are commonly targeted in TLR7-dominated systemic erythematosus lupus-prone mice. To determine whether an inability of TLR9 to detect endogenous DNA could explain the absence of dsDNA-reactive autoantibodies in DKO mice, we used a novel class of bifunctional autoantibodies, IgM/DNA dual variable domain Ig molecules, to activate B cells through a BCR/TLR9-dependent mechanism. DKO B cells could not respond to the IgM/DNA dual variable domain Ig molecule, despite a normal response to both anti-IgM and CpG ODN 1826. Thus, DKO B cells only respond to RNA-associated ligands because DNase II-mediated degradation of self-DNA is required for TLR9 activation.
Asunto(s)
Autoanticuerpos/inmunología , Autoantígenos/inmunología , Autoinmunidad/inmunología , Linfocitos B/inmunología , Endodesoxirribonucleasas/deficiencia , Activación de Linfocitos/inmunología , Animales , Especificidad de Anticuerpos/inmunología , ADN , Endodesoxirribonucleasas/inmunología , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Humanos , Ligandos , Ratones , Ratones Noqueados , Receptores de Antígenos de Linfocitos B/inmunología , Receptor Toll-Like 9/inmunologíaRESUMEN
Endosomal TLRs play an important role in systemic autoimmune diseases, such as systemic erythematosus lupus, in which DNA- and RNA-associated autoantigens activate autoreactive B cells through TLR9- and TLR7-dependent pathways. Nevertheless, TLR9-deficient autoimmune-prone mice develop more severe clinical disease, whereas TLR7-deficient and TLR7/9-double deficient autoimmune-prone mice develop less severe disease. To determine whether the regulatory activity of TLR9 is B cell intrinsic, we directly compared the functional properties of autoantigen-activated wild-type, TLR9-deficient, and TLR7-deficient B cells in an experimental system in which proliferation depends on BCR/TLR coengagement. In vitro, TLR9-deficient cells are less dependent on survival factors for a sustained proliferative response than are either wild-type or TLR7-deficient cells. The TLR9-deficient cells also preferentially differentiate toward the plasma cell lineage, as indicated by expression of CD138, sustained expression of IRF4, and other molecular markers of plasma cells. In vivo, autoantigen-activated TLR9-deficient cells give rise to greater numbers of autoantibody-producing cells. Our results identify distinct roles for TLR7 and TLR9 in the differentiation of autoreactive B cells that explain the capacity of TLR9 to limit, as well as TLR7 to promote, the clinical features of systemic erythematosus lupus.
Asunto(s)
Linfocitos B/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Receptor Toll-Like 7/inmunología , Receptor Toll-Like 9/inmunología , Animales , Autoanticuerpos/inmunología , Autoanticuerpos/metabolismo , Autoantígenos/inmunología , Autoinmunidad/genética , Autoinmunidad/inmunología , Linfocitos B/metabolismo , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Proliferación Celular/genética , Células Cultivadas , Citometría de Flujo , Factores Reguladores del Interferón/inmunología , Factores Reguladores del Interferón/metabolismo , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Ratones Endogámicos BALB C , Ratones Noqueados , Ratones Transgénicos , Análisis de Secuencia por Matrices de Oligonucleótidos , Células Plasmáticas/inmunología , Células Plasmáticas/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor Reumatoide/inmunología , Sindecano-1/inmunología , Sindecano-1/metabolismo , Receptor Toll-Like 7/deficiencia , Receptor Toll-Like 7/genética , Receptor Toll-Like 9/deficiencia , Receptor Toll-Like 9/genética , Transcriptoma/inmunologíaRESUMEN
OBJECTIVES: The goal of this study was to determine whether endosomal Toll-like receptors (TLRs) contribute to the clinical manifestation of systemic autoimmunity exhibited by mice that lack the lysosomal nuclease DNaseII. METHODS: DNaseII/IFNaR double deficient mice were intercrossed with Unc93b13d/3d mice to generate DNaseII-/-mice with non-functional endosomal TLRs. The resulting triple deficient mice were evaluated for arthritis, autoantibody production, splenomegaly, and extramedullary haematopoiesis. B cells from both strains were evaluated for their capacity to respond to endogenous DNA by using small oligonucleotide based TLR9D ligands and a novel class of bifunctional anti-DNA antibodies. RESULTS: Mice that fail to express DNaseII, IFNaR, and Unc93b1 still develop arthritis but do not make autoantibodies, develop splenomegaly, or exhibit extramedullary haematopoiesis. DNaseII-/- IFNaR-/- B cells can respond to synthetic ODNs, but not to endogenous dsDNA. CONCLUSIONS: RNA-reactive TLRs, presumably TLR7, are required for autoantibody production, splenomegaly, and extramedullary haematopoiesis in the DNaseII-/- model of systemic autoimmunity.
Asunto(s)
Artritis/metabolismo , Autoinmunidad , ADN/metabolismo , Endosomas/metabolismo , ARN/metabolismo , Receptores Toll-Like/metabolismo , Animales , Artritis/genética , Artritis/inmunología , Autoanticuerpos/inmunología , Autoanticuerpos/metabolismo , ADN/inmunología , Endodesoxirribonucleasas/deficiencia , Endodesoxirribonucleasas/genética , Endosomas/inmunología , Genotipo , Hematopoyesis Extramedular , Ligandos , Glicoproteínas de Membrana/inmunología , Glicoproteínas de Membrana/metabolismo , Proteínas de Transporte de Membrana/deficiencia , Proteínas de Transporte de Membrana/genética , Ratones Noqueados , Fenotipo , ARN/inmunología , Receptor de Interferón alfa y beta/deficiencia , Receptor de Interferón alfa y beta/genética , Transducción de Señal , Esplenomegalia , Receptor Toll-Like 7/inmunología , Receptor Toll-Like 7/metabolismo , Receptor Toll-Like 9/inmunología , Receptor Toll-Like 9/metabolismo , Receptores Toll-Like/inmunologíaRESUMEN
Interferon regulatory factor 5-deficient (IRF5 (-/-) ) mice have been used for many studies of IRF5 biology. A recent report identifies a mutation in dedicator of cytokinesis 2 (DOCK2) as being responsible for the abnormal B-cell development phenotype observed in the IRF5 (-/-) line. Both dedicator of cytokinesis 2 (DOCK2) and IRF5 play important roles in immune cell function, raising the issue of whether immune effects previously associated with IRF5 are due to IRF5 or DOCK2. Here, we defined the insertion end-point of the DOCK2 mutation and designed a novel PCR to detect the mutation in genomic DNA. We confirmed the association of the DOCK2 mutation and the abnormal B-cell phenotype in our IRF5 (-/-) line and also established another IRF5 (-/-) line without the DOCK2 mutation. These two lines were used to compare the role of IRF5 in dendritic cells (DCs) and B cells in the presence or absence of the DOCK2 mutation. IRF5 deficiency reduces IFN-α, IFN-ß and IL-6 production by Toll-like receptor 9 (TLR9)- and TLR7-stimulated DCs and reduces TLR7- and TLR9-induced IL-6 production by B cells to a similar extent in the two lines. Importantly however, IRF5 (-/-) mice with the DOCK2 mutation have higher serum levels of IgG1 and lower levels of IgG2b, IgG2a/c and IgG3 than IRF5 (-/-) mice without the DOCK2 mutation, suggesting that the DOCK2 mutation confers additional Th2-type effects. Overall, these studies help clarify the function of IRF5 in B cells and DCs in the absence of the DOCK2 mutation. In addition, the PCR described will be useful for other investigators using the IRF5 (-/-) mouse line.
Asunto(s)
Linfocitos B/metabolismo , Células Dendríticas/metabolismo , Proteínas Activadoras de GTPasa/genética , Factores Reguladores del Interferón/deficiencia , Animales , Proteínas Activadoras de GTPasa/metabolismo , Factores de Intercambio de Guanina Nucleótido , Factores Reguladores del Interferón/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , FenotipoRESUMEN
Gain-of-function mutations in the dsDNA sensing adaptor STING lead to a severe autoinflammatory syndrome known as STING-associated vasculopathy with onset in infancy (SAVI). Patients with SAVI develop interstitial lung disease (ILD) and produce autoantibodies that are commonly associated with systemic autoimmune diseases. Mice expressing the most common SAVI mutation, STING V154M (VM), similarly develop ILD but exhibit severe T and B cell lymphopenia and low serum Ig titers, and they lack autoantibodies. Importantly, lethally irradiated VM hosts reconstituted with WT stem cells (WTâVM) still develop ILD. In this study, we find that WTâVM chimeras had restored B cell function, produced autoantibodies, and thereby recapitulated the loss of tolerance seen in patients with SAVI. Lymphocytes derived from both WT and BCR or TCR transgenic (Tg) donors accumulated in the extravascular lung tissue of WT+TgâVM mixed chimeras, but lymphocyte activation and germinal center formation required WT cells with a diverse repertoire. Furthermore, when T cells isolated from the WTâVM chimeras were adoptively transferred to naive Rag1-deficient secondary hosts, they trafficked to the lung and recruited neutrophils. Overall, these findings indicated that VM expression by radioresistant cells promoted the activation of autoreactive B cells and T cells that then differentiated into potentially pathogenic effector subsets.
Asunto(s)
Mutación con Ganancia de Función , Activación de Linfocitos , Proteínas de la Membrana , Animales , Ratones , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Activación de Linfocitos/inmunología , Pulmón/inmunología , Pulmón/patología , Autoanticuerpos/inmunología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Enfermedades Pulmonares Intersticiales/genética , Enfermedades Pulmonares Intersticiales/inmunología , Tolerancia a Radiación/genética , Tolerancia a Radiación/inmunología , Ratones Transgénicos , Linfocitos T/inmunología , Linfocitos T/metabolismo , Femenino , Humanos , Ratones Endogámicos C57BL , Modelos Animales de EnfermedadRESUMEN
Gain-of-function mutations in the dsDNA sensing adaptor STING lead to a severe autoinflammatory syndrome known as STING-associated vasculopathy with onset in Infancy (SAVI). SAVI patients develop interstitial lung disease (ILD) and commonly produce anti-nuclear antibodies (ANAs), indicative of concomitant autoimmunity. Mice heterozygous for the most common SAVI mutation, V154M (VM), also develop ILD, triggered by nonhematopoietic VM cells, but exhibit severe peripheral lymphopenia, low serum Ig titers and fail to produce autoantibodies. In contrast, we now show that lethally irradiated VM mice reconstituted with WT stem cells (WTâVM chimeras) develop ANAs and lung-reactive autoantibodies associated with accumulation of activated lymphocytes and formation of germinal centers in lung tissues. Moreover, when splenocytes from WTâVM chimeras were adoptively transferred into unmanipulated Rag1 -/- mice, donor T cells accumulated in the lung. Overall, these findings demonstrate that expression of the VM mutation in non-hematopoietic cells can promote the activation of immunocompetent autoreactive lymphocytes. Summary: Chimeric mice expressing STING only in non-hematopoietic cells develop systemic and lung directed autoimmunity which recapitulates what is seen in pediatric patients with SAVI disease.
RESUMEN
Central B cell tolerance is believed to be regulated by B cell receptor signaling induced by the recognition of self-antigens in immature B cells. Using humanized mice with defective MyD88, TLR7, or TLR9 expression, we demonstrate that TLR9/MYD88 are required for central B cell tolerance and the removal of developing autoreactive clones. We also show that CXCL4, a chemokine involved in systemic sclerosis (SSc), abrogates TLR9 function in B cells by sequestering TLR9 ligands away from the endosomal compartments where this receptor resides. The in vivo production of CXCL4 thereby impedes both TLR9 responses in B cells and the establishment of central B cell tolerance. We conclude that TLR9 plays an essential early tolerogenic function required for the establishment of central B cell tolerance and that correcting defective TLR9 function in B cells from SSc patients may represent a novel therapeutic strategy to restore B cell tolerance.
Asunto(s)
Factor Plaquetario 4 , Esclerodermia Sistémica , Receptor Toll-Like 9 , Animales , Humanos , Ratones , Linfocitos B , Ligandos , Factor 88 de Diferenciación Mieloide/metabolismo , Factor Plaquetario 4/metabolismo , Esclerodermia Sistémica/metabolismo , Receptor Toll-Like 7 , Receptor Toll-Like 9/metabolismoRESUMEN
BACKGROUNDInfluenza A virus (IAV) and SARS-CoV-2 are pandemic viruses causing millions of deaths, yet their clinical manifestations are distinctly different.METHODSWith the hypothesis that upper airway immune and epithelial cell responses are also distinct, we performed single-cell RNA sequencing (scRNA-Seq) on nasal wash cells freshly collected from adults with either acute COVID-19 or influenza or from healthy controls. We focused on major cell types and subtypes in a subset of donor samples.ResultsNasal wash cells were enriched for macrophages and neutrophils for both individuals with influenza and those with COVID-19 compared with healthy controls. Hillock-like epithelial cells, M2-like macrophages, and age-dependent B cells were enriched in COVID-19 samples. A global decrease in IFN-associated transcripts in neutrophils, macrophages, and epithelial cells was apparent in COVID-19 samples compared with influenza samples. The innate immune response to SARS-CoV-2 appears to be maintained in macrophages, despite evidence for limited epithelial cell immune sensing. Cell-to-cell interaction analyses revealed a decrease in epithelial cell interactions in COVID-19 and highlighted differences in macrophage-macrophage interactions for COVID-19 and influenza.ConclusionsOur study demonstrates that scRNA-Seq can define host and viral transcriptional activity at the site of infection and reveal distinct local epithelial and immune cell responses for COVID-19 and influenza that may contribute to their divergent disease courses.FundingMassachusetts Consortium on Pathogen Readiness, the Mathers Foundation, and the Department of Defense (W81XWH2110029) "COVID-19 Expansion for AIRe Program."
Asunto(s)
COVID-19 , Inmunidad Innata , Virus de la Influenza A , Gripe Humana , Macrófagos , RNA-Seq , SARS-CoV-2 , Adulto , COVID-19/genética , COVID-19/inmunología , Femenino , Humanos , Virus de la Influenza A/genética , Virus de la Influenza A/inmunología , Gripe Humana/genética , Gripe Humana/inmunología , Macrófagos/inmunología , Macrófagos/virología , Masculino , Lavado Nasal (Proceso) , SARS-CoV-2/genética , SARS-CoV-2/inmunologíaRESUMEN
Gain-of-function polymorphisms in the transcription factor IFN regulatory factor 5 (IRF5) are associated with an increased risk of developing systemic lupus erythematosus. However, the IRF5-expressing cell type(s) responsible for lupus pathogenesis in vivo is not known. We now show that monoallelic IRF5 deficiency in B cells markedly reduced disease in a murine lupus model. In contrast, similar reduction of IRF5 expression in macrophages, monocytes, and neutrophils did not reduce disease severity. B cell receptor and TLR7 signaling synergized to promote IRF5 phosphorylation and increase IRF5 protein expression, with these processes being independently regulated. This synergy increased B cell-intrinsic IL-6 and TNF-α production, both key requirements for germinal center (GC) responses, with IL-6 and TNF-α production in vitro and in vivo being substantially lower with loss of 1 allele of IRF5. Mechanistically, TLR7-dependent IRF5 nuclear translocation was reduced in B cells from IRF5-heterozygous mice. In addition, we show in multiple lupus models that IRF5 expression was dynamically regulated in vivo with increased expression in GC B cells compared with non-GC B cells and with further sequential increases during progression to plasmablasts and long-lived plasma cells. Overall, a critical threshold level of IRF5 in B cells was required to promote disease in murine lupus.
Asunto(s)
Linfocitos B/metabolismo , Factores Reguladores del Interferón , Interleucina-6/metabolismo , Lupus Eritematoso Sistémico , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Autoinmunidad , Modelos Animales de Enfermedad , Mutación con Ganancia de Función , Regulación de la Expresión Génica/inmunología , Centro Germinal , Factores Reguladores del Interferón/deficiencia , Factores Reguladores del Interferón/genética , Factores Reguladores del Interferón/metabolismo , Lupus Eritematoso Sistémico/genética , Lupus Eritematoso Sistémico/inmunología , Ratones , Transducción de Señal/inmunologíaRESUMEN
OBJECTIVE: Patients with hypomorphic mutations in DNase II develop a severe and debilitating autoinflammatory disease. This study was undertaken to compare the disease parameters in these patients to those in a murine model of DNase II deficiency, and to evaluate the role of specific nucleic acid sensors and identify the cell types responsible for driving the autoinflammatory response. METHODS: To avoid embryonic death, Dnase2-/- mice were intercrossed with mice that lacked the type I interferon (IFN) receptor (Ifnar-/- ). The hematologic changes and immune status of these mice were evaluated using complete blood cell counts, flow cytometry, serum cytokine enzyme-linked immunosorbent assays, and liver histology. Effector cell activity was determined by transferring T cells from Dnase2-/- × Ifnar-/- double-knockout (DKO) mice into Rag1-/- mice, and 4 weeks after cell transfer, induced changes were assessed in the recipient mice. RESULTS: In Dnase2-/- × Ifnar-/- DKO mice, many of the disease features found in DNase II-deficient patients were recapitulated, including cytopenia, extramedullary hematopoiesis, and liver fibrosis. Dnase2+/+ × Rag1-/- mice (n > 22) developed a hematologic disorder that was attributed to the transfer of an unusual IFNγ-producing T cell subset from the spleens of donor Dnase2-/- × Ifnar-/- DKO mice. Autoinflammation in this murine model did not depend on the stimulator of IFN genes (STING) pathway but was highly dependent on the chaperone protein Unc93B1. CONCLUSION: Dnase2-/- × Ifnar-/- DKO mice may be a valid model for exploring the innate and adaptive immune mechanisms responsible for the autoinflammation similar to that seen in DNASE2-hypomorphic patients. In this murine model, IFNγ is required for T cell activation and the development of clinical manifestations. The role of IFNγ in DNASE2-deficient patient populations remains to be determined, but the ability of Dnase2-/- mouse T cells to transfer disease to Rag1-/- mice suggests that T cells may be a relevant therapeutic target in patients with IFN-related systemic autoinflammatory diseases.
Asunto(s)
Enfermedades Autoinmunes/etiología , Endodesoxirribonucleasas/deficiencia , Inflamación/inmunología , Interferón gamma/biosíntesis , Células TH1/metabolismo , Animales , Modelos Animales de Enfermedad , Interferón Tipo I , Ratones , Ratones Endogámicos C57BLRESUMEN
A spectrum of human autoinflammatory conditions result from defects in cytosolic nucleic acid clearance or overexpression of the nucleic acid sensor STING. These patients often develop severely debilitating lesions and invariably show robust IFN signatures that have been attributed to the cGAS/STING signaling cascade and type I IFN. However, murine models that recapitulate major features of these syndromes have now shown that autoinflammation is more likely to depend on type II IFN/IFNgamma or type III IFN/IFNlambda, and further revealed a critical role for Th1 cells in tissue damage and the persistence of inflammation. These studies provide important insights about the types of IFNs, and the interplay of the innate and adaptive immune systems mediated by these IFNs, that can initiate and maintain the corresponding human diseases. They further point to type II/III IFNs and effector T cells as targets for more effective therapeutic strategies in the treatment of these patient populations.
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Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/metabolismo , Autoinmunidad , Inflamación/inmunología , Inflamación/metabolismo , Interferón Tipo I/metabolismo , Ácidos Nucleicos/inmunología , Animales , Enfermedades Autoinmunes/genética , Susceptibilidad a Enfermedades , Exodesoxirribonucleasas/genética , Exodesoxirribonucleasas/metabolismo , Predisposición Genética a la Enfermedad , Humanos , Inflamación/genética , Mutación con Pérdida de Función , Ratones , Ácidos Nucleicos/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismoRESUMEN
Both endosomal and cytosolic-nucleic acid-sensing receptors can detect endogenous ligands and promote autoimmunity and autoinflammation. These responses involve a complex interplay among and between the cytosolic and endosomal sensors involving both hematopoietic and radioresistant cells. Cytosolic sensors directly promote inflammatory responses through the production of type I IFNs and proinflammatory cytokines. Inflammation-associated tissue damage can further promote autoimmune responses indirectly, as receptor-mediated internalization of the resulting cell debris can activate endosomal Toll-like receptors (TLR). Both endosomal and cytosolic receptors can also negatively regulate inflammatory responses. A better understanding of the factors and pathways that promote and constrain autoimmune diseases will have important implications for the development of agonists and antagonists that modulate these pathways.
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Enfermedades Autoinmunes/metabolismo , Proteínas de la Membrana/metabolismo , Receptores Toll-Like/metabolismo , Animales , Enfermedades Autoinmunes/patología , Endosomas/metabolismo , Humanos , Inflamación/patología , Ácidos Nucleicos/metabolismoRESUMEN
Mature B cell pools retain a substantial proportion of polyreactive and self-reactive clonotypes, suggesting that activation checkpoints exist to reduce the initiation of autoreactive B cell responses. Here, we have described a relationship among the B cell receptor (BCR), TLR9, and cytokine signals that regulate B cell responses to DNA-containing antigens. In both mouse and human B cells, BCR ligands that deliver a TLR9 agonist induce an initial proliferative burst that is followed by apoptotic death. The latter mechanism involves p38-dependent G1 cell-cycle arrest and subsequent intrinsic mitochondrial apoptosis and is shared by all preimmune murine B cell subsets and CD27- human B cells. Survival or costimulatory signals rescue B cells from this fate, but the outcome varies depending on the signals involved. B lymphocyte stimulator (BLyS) engenders survival and antibody secretion, whereas CD40 costimulation with IL-21 or IFN-γ promotes a T-bet+ B cell phenotype. Finally, in vivo immunization studies revealed that when protein antigens are conjugated with DNA, the humoral immune response is blunted and acquires features associated with T-bet+ B cell differentiation. We propose that this mechanism integrating BCR, TLR9, and cytokine signals provides a peripheral checkpoint for DNA-containing antigens that, if circumvented by survival and differentiative cues, yields B cells with the autoimmune-associated T-bet+ phenotype.