RESUMO
The extracellular matrix (ECM) is the basis for virtually all cellular processes and is also related to tumor metastasis. Fibronectin (FN), a major ECM macromolecule expressed by different cell types and also present in plasma, consists of multiple functional modules that bind to ECM-associated, plasma, and cell-surface proteins such as integrins and FN itself, thus ensuring its cell-adhesive and modulatory role. Here we show that FN constitutes an immune checkpoint. Thus, FN was identified as a physiological ligand for a tumor/leukemia/lymphoma- as well as autoimmune-associated checkpoint, ILT3/LILRB4 (B4, CD85k). Human B4 and the murine ortholog, gp49B, bound FN with sub-micromolar affinities as assessed by bio-layer interferometry. The major B4-binding site in FN was located at the N-terminal 30-kDa module (FN30), which is apart from the major integrin-binding site present at the middle of the molecule. Blockade of B4-FN binding such as with B4 antibodies or a recombinant FN30-Fc fusion protein paradoxically ameliorated autoimmune disease in lupus-prone BXSB/Yaa mice. The unexpected nature of the B4-FN checkpoint in autoimmunity is discussed, referring to its potential role in tumor immunity.
Assuntos
Doenças Autoimunes/metabolismo , Fibronectinas/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismo , Animais , Doenças Autoimunes/imunologia , Autoimunidade/imunologia , Comunicação Celular/imunologia , Linhagem Celular Tumoral , Células Cultivadas , Fibronectinas/imunologia , Células Endoteliais da Veia Umbilical Humana/imunologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Glicoproteínas de Membrana/imunologia , Camundongos , Fagocitose/imunologia , Células RAW 264.7 , Receptores Imunológicos/imunologia , Células THP-1/imunologia , Células THP-1/metabolismoRESUMO
Bee venom (BV) induces skin inflammation, characterized by erythema, blisters, edemas, pain and itching. Although BV has been found to have an inhibitory effect on toll-like receptors (TLRs), we here show that BV enhances keratinocyte responses to polyinosinic-polycytidylic acid [poly(I:C)], a ligand for TLR3. Our results revealed that the enhanced TLR activity was primarily induced by secretory phospholipase A2 (sPLA2), a component of BV (BV-sPLA2). PLA2 mediates the hydrolysis of membrane phospholipids into lysophospholipids and free fatty acids. We demonstrated that BV-sPLA2 increased the intracellular uptake of poly(I:C), phosphorylation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs), and poly(I:C)-mediated interleukin 8 production in human keratinocytes. We further showed that the enzymatic activity of BV-sPLA2 was essential for the increased uptake of poly(I:C). These findings suggest that BV-sPLA2 may induce a modification of the cell membrane structure, leading to enhanced poly(I:C) uptake in keratinocytes. BV-sPLA2 might be able to promote wound healing by enhancing TLR3 responses.
Assuntos
Venenos de Abelha/enzimologia , Queratinócitos/metabolismo , Fosfolipases A2/metabolismo , Poli I-C/metabolismo , Animais , Abelhas , Células Cultivadas , Humanos , Interleucina-8/biossíntese , Receptores Toll-Like/metabolismoRESUMO
IgE plays a key role in allergies by binding to allergens and then sensitizing mast cells through the Fc receptor, resulting in the secretion of proinflammatory mediators. Therefore, IgE is a major target for managing allergies. Previous studies have reported that oligomannose on IgE can be a potential target to inhibit allergic responses. However, enzymes that can modulate IgE activity are not yet known. Here, we found that the commercial receptor-destroying enzyme (RDE) (II) from Vibrio cholerae culture fluid specifically modulates IgE, but not IgG, and prevents the initiation of anaphylaxis. RDE (II)-treated IgE cannot access its binding site on bone marrow-derived mast cells, resulting in reduced release of histamine and cytokines. We also noted that RDE (II)-treated IgE could not induce passive cutaneous anaphylaxis in mouse ears. Taken together, we concluded that RDE (II) modulates the IgE structure and renders it unable to mediate allergic responses. To reveal the mechanism by which RDE (II) interferes with IgE activity, we performed lectin microarray analysis to unravel the relationship between IgE modulation and glycosylation. We observed that RDE (II) treatment significantly reduced the binding of IgE to Lycopersicon esculentum lectin, which recognizes poly-N-acetylglucosamine and poly-N-acetyllactosamine. These results suggest that RDE (II) specifically modulates branched glycans on IgE, thereby interfering with its ability to induce allergic responses. Our findings may provide a basis for the development of drugs to inhibit IgE activity in allergies.
Assuntos
Anafilaxia/prevenção & controle , Enzimas/metabolismo , Imunoglobulina E/imunologia , Vibrio cholerae/enzimologia , Anafilaxia/imunologia , Animais , Sítios de Ligação , Células da Medula Óssea/imunologia , Imunoglobulina E/química , Imunoglobulina E/metabolismo , Imunoglobulina G/química , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Mastócitos/imunologia , Camundongos , Polissacarídeos/metabolismo , Inibidores de Proteases/farmacologia , Conformação Proteica , Tripsina/metabolismoRESUMO
AbstractImmune homeostasis is critically regulated by the balance between activating and inhibitory receptors expressed on various immune cells such as T and B lymphocytes, and myeloid cells. The inhibitory receptors play a fundamental role in the immune checkpoint pathway, thus maintaining peripheral tolerance. We recently found that expression of leukocyte immunoglobulin-like receptor (LILR)B4, an inhibitory member of the human LILR family, is augmented in auto-antibody-producing plasmablasts/plasma cells of systemic lupus erythematosus (SLE) patients. However, the mechanism behind the 'paradoxical' up-regulation of this inhibitory receptor upon pathogenic antibody-secreting cells is yet to be known. To this end, in this study, we examined if glycoprotein 49B (gp49B), the murine counterpart of human LILRB4, is also elevated in auto-antibody-producing cells in several SLE mouse models, and tried to clarify the underlying mechanism. We found that gp49B is expressed on plasma cells of lupus-prone models but not of healthy C57BL/6 mice, and the level was positively correlated to the anti-double-stranded DNA IgG titer in serum. Gp49B genetic deletion, however, did not abolish the serum auto-antibodies or fully ameliorate the lethal glomerulonephritis, indicating that gp49B is not the sole regulator of lupus but a pathogenic element in the disease. We conclude that the elevated expression of this inhibitory receptor on pathogenic plasma cells was also relevant upon the murine SLE model. The mechanism of gp49B underlying the disease progression in lupus-prone mice has been discussed.
Assuntos
Células Produtoras de Anticorpos/imunologia , Biomarcadores/metabolismo , Glomerulonefrite/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Nefrite Lúpica/imunologia , Glicoproteínas de Membrana/metabolismo , Plasmócitos/imunologia , Receptores Imunológicos/metabolismo , Animais , Anticorpos Antinucleares/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Humanos , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Imunológicos/genéticaRESUMO
Plasma cells (PCs) acquiring long lifespans in the bone marrow (BM) play a pivotal role in the humoral arm of immunological memory. The PCs reside in a special BM niche and produce antibodies against past-encountered pathogens or vaccine components for a long time. In BM, cysteine-X-cysteine (CXC) chemokine receptor type 4 (CXCR4)-expressing PCs and myeloid cells such as dendritic cells are attracted to and held by CXC chemokine ligand 12 (CXCR12)-secreting stromal cells, where survival of the PCs is supported by soluble factors such as IL-6 and APRIL (a proliferation-inducing ligand) produced by neighboring myeloid cells. Although these stromal cells are also supposed to be involved in the support of the survival and antibody production, the full molecular mechanism has not been clarified yet. Here, we show that BM PDGFRα+Sca-1+-enriched mesenchymal stem cells (MSCs), which can contribute as stromal cells for hematopoietic stem cells, also support in vitro survival of and antibody production by BM PCs. IL-6 produced by MSCs was found to be involved in the support. Immunohistochemistry of BM sections suggested a co-localization of a minor population of PCs with PDGFRα+Sca-1+ MSCs in the BM. We also found that the sort-purified MSC preparation was composed of multiple cell groups with different gene expression profiles, as found on single-cell RNA sequencing, to which multiple roles in the in vitro PC support could be attributed.
Assuntos
Formação de Anticorpos , Antígenos Ly/metabolismo , Medula Óssea/metabolismo , Interleucina-6/metabolismo , Proteínas de Membrana/metabolismo , Células-Tronco Mesenquimais/metabolismo , Plasmócitos/citologia , Plasmócitos/imunologia , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Animais , Sobrevivência Celular , Células Cultivadas , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
Plasmablasts and plasma cells (PBs and PCs) producing pathogenic auto-antibodies in patients with systemic autoimmune diseases could be a better target for specific therapies for the disease than general immunosuppression or pan- or activated B-cell targeting. Our previous study indicated that leukocyte immunoglobulin-like receptor (LILR) B4 (B4, also known as ILT3/LIR-5/CD85k), a tolerogenic receptor in antigen-presenting cells, is ectopically expressed on the PB/PC surface in healthy individuals. Here, we show that the enlarged population size of PBs/PCs with augmented B4 expression is characteristic in non-treated systemic lupus erythematosus (SLE). Paradoxically, the transcription frequency of the anti-double-strand DNA immunoglobulin-coding VH sequence in the B4+ population of non-treated SLE was significantly higher than that in B4- cells. B4+ and B4- PBs/PCs were suggested to be developmentally equivalent based on the simultaneous generation of these populations upon activation of memory B cells in vitro B4 expression was found to be induced efficiently by IL-2, while IFN-α effectively induced B4+ PBs/PCs in vitro Utilizing the elevated B4 will support opening a new avenue for identifying the mechanism for generation of, and additional molecular markers for, pathogenic cells.
Assuntos
Autoanticorpos/imunologia , Tolerância Imunológica/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/patologia , Plasmócitos/imunologia , Receptores de Superfície Celular/imunologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Glicoproteínas de Membrana , Pessoa de Meia-Idade , Receptores Imunológicos , Adulto JovemRESUMO
TLRs are distributed in their characteristic cellular or subcellular compartments to efficiently recognize specific ligands and to initiate intracellular signaling. Whereas TLRs recognizing pathogen-associated lipids or proteins are localized to the cell surface, nucleic acid-sensing TLRs are expressed in endosomes and lysosomes. Several endoplasmic reticulum (ER)-resident proteins are known to regulate the trafficking of TLRs to the specific cellular compartments, thus playing important roles in the initiation of innate immune responses. In this study, we show that an ER-resident protein, Nogo-B (or RTN4-B), is necessary for immune responses triggered by nucleic acid-sensing TLRs, and that a newly identified Nogo-B-binding protein (glucosyltransferases, Rab-like GTPase activators and myotubularins [GRAM] domain containing 4 [GRAMD4]) negatively regulates the responses. Production of inflammatory cytokines in vitro by macrophages stimulated with CpG-B oligonucleotides or polyinosinic:polycytidylic acid was attenuated in the absence of Nogo-B, which was also confirmed in serum samples from Nogo-deficient mice injected with polyinosinic:polycytidylic acid. Although a deficiency of Nogo-B did not change the incorporation or delivery of CpG to endosomes, the localization of TLR9 to endolysosomes was found to be impaired. We identified GRAMD4 as a downmodulator for TLR9 response with a Nogo-B binding ability in ER, because our knockdown and overexpression experiments indicated that GRAMD4 suppresses the TLR9 response and knockdown of Gramd4 strongly enhanced the response in the absence of Nogo-B. Our findings indicate a critical role of Nogo-B and GRAMD4 in trafficking of TLR9.
Assuntos
Endossomos/metabolismo , Imunidade Inata/imunologia , Proteínas Mitocondriais/metabolismo , Proteínas da Mielina/metabolismo , Receptor Toll-Like 9/imunologia , Animais , Linhagem Celular , Ilhas de CpG/genética , Citocinas/biossíntese , Retículo Endoplasmático/metabolismo , Endossomos/imunologia , Células HEK293 , Humanos , Imunidade Inata/genética , Macrófagos/imunologia , Proteínas de Membrana Transportadoras/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Mitocondriais/genética , Proteínas da Mielina/genética , Proteínas Nogo , Oligonucleotídeos/farmacologia , Poli I-C/farmacologia , Ligação Proteica , Transporte Proteico , Interferência de RNA , RNA Interferente Pequeno , Transdução de Sinais/imunologiaRESUMO
A pressure-induced structural change of a polymer isotactic poly(4-methyl-1-pentene) (P4MP1) in the melted state at 270 °C has been investigated by high-pressure in situ x-ray diffraction, where high pressures up to 1.8 kbar were applied using helium gas. The first sharp diffraction peak (FSDP) position of the melt shows a less pressure dependence than that of the normal compression using a solid pressure transmitting medium. The contraction using helium gas was about 10% at 2 kbar, smaller than about 20% at the same pressure using a solid medium. The result indicates that helium entered the interstitial space between the main chains. The helium/monomer molar ratio was estimated to be 0.3 at 2 kbar from the FSDP positions. These results suggest that the compressibility of the P4MP1 melt can be largely dependent on the pressure transmitting media. As the pore size is reversibly and continuously controllable by compression, we suggest that the P4MP1 melt can be an ideal porous liquid for investigating a novel mechanical response of the pores in a non-crystalline substance.
RESUMO
CD20(+)CD27(+)CD43(+) B (CD43(+) B) cells have been newly defined among PBMCs and proposed to be human B1 cells. However, it is controversial as to whether they are orthologs of murine B1 cells and how they are related to other B-cell populations, particularly CD20(+)CD27(+)CD43(-) memory B cells and CD20(low)CD27(high)CD43(high) plasmablasts. Our objective is to identify phenotypically the position of CD43(+) B cells among peripheral B-lineage cell compartments in healthy donors, with reference to B-cell subsets from patients with systemic lupus erythematosus (SLE). We found that CD43(+) B cells among PBMCs from healthy subjects were indistinguishable phenotypically from memory B cells in terms of surface markers, and spontaneous in vitro Ig and IL-10 secretion capability, but quite different from plasmablasts. However, a moderate correlation was found in the frequency of CD43(+) B cells with that of plasmablasts in healthy donors but not in SLE patients. An in vitro differentiation experiment indicated that CD43(+) B cells give rise to plasmablasts more efficiently than do memory B cells, suggesting that they are more closely related to plasmablasts developmentally than are memory B cells, which is also supported by quantitative PCR analysis of mRNA expression of B-cell and plasma cell signature genes. Thus, we conclude that, in healthy individuals, CD43(+) B cells are closely related not only to memory B cells phenotypically but also to plasmablasts developmentally, although the developmental origin of CD43(+) B cells is not necessarily the same as that of plasmablasts.
Assuntos
Subpopulações de Linfócitos B/imunologia , Leucossialina/imunologia , Plasmócitos/imunologia , Adulto , Feminino , Voluntários Saudáveis , Humanos , Masculino , Fenótipo , Adulto JovemRESUMO
BACKGROUND: Monocytes and macrophages produce interleukin (IL)-10, an immunoregulatory cytokine and a potent therapeutic tool for immune disorders. Augmentation of IL-10 production with a concomitant reduction of proinflammatory cytokines in macrophages in vitro is attained by doubly stimulating the cells with a toll-like receptor ligand and immunoglobulin (Ig)G immune complexes, a response known as that of regulatory (or alternatively activated/M2) macrophages. However, it has not been explored sufficiently how such a regulatory response could be exploited for anti-inflammation. Our objective is to find a potential way or condition for augmenting IL-10 by monocytes/macrophages in vivo and in vitro. RESULTS: We show that platelets, when they are opsonized with IgG, can convert human peripheral blood circulating monocytes to IL-10-producing regulatory monocytes in vitro and also in a murine in vivo model. Co-culturing of platelets and monocytes in the presence of anti-integrin IgG and a bacterial lipopolysaccharide augmented IL-10 production via a direct interaction between platelets and monocytes. This novel way of enhancing IL-10 was mediated by activating-type Fc receptors for IgG. CONCLUSION: These findings indicate that the IgG-bound platelet-induced conversion of monocytes to regulatory cells might provide a novel strategy for controlling inflammation.
Assuntos
Plaquetas/imunologia , Imunoglobulina G/metabolismo , Interleucina-10/metabolismo , Monócitos/imunologia , Receptores de IgG/metabolismo , Anticorpos Bloqueadores/farmacologia , Circulação Sanguínea , Plaquetas/efeitos dos fármacos , Comunicação Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Humanos , Imunomodulação , Integrinas/imunologia , Integrinas/metabolismo , Lipopolissacarídeos/metabolismo , Monócitos/efeitos dos fármacosRESUMO
BACKGROUND: The significance of a unique inhibitory Fc receptor for IgG, FcγRIIB (RIIB), in the prevention of spontaneous production of autoantibodies remains controversial, due mainly to the fact that the RIIB locus is adjacent to the autoimmune-related SLAM locus harboring the genes coding for signaling lymphocyte activation molecules, making it difficult to isolate the effect of RIIB deletion from that of SLAM in gene-targeted mice. Our objective was to determine the influence of RIIB deletion on the spontaneous development of autoimmune diseases and to compare it with that of potentially pathogenic SLAM. RESULTS: We established two congenic C57BL/6 (B6) strains, one with the RIIB deletion and the other with SLAM, by backcrossing 129/SvJ-based RIIB-deficient mice into the B6 genetic background extensively. The RIIB deficiency indeed led to the production and/or accumulation of a small amount of anti-nuclear autoantibodies (ANAs) and to weak IgG immune-complex deposition in glomeruli without any obvious manifestation of lupus nephritis. In contrast, pathogenic SLAM in the B6 genetic background induced ANAs but no IgG immune-complex deposition in the kidneys. Naïve SLAM mice but not RIIB-deficient mice exhibited hyperplasia of splenic germinal centers. CONCLUSION: The present results clarify the roles of RIIB in preventing production and/or accumulation of a small amount of ANAs, and development of glomerulonephritis. The combined effects of RIIB deletion and pathogenic SLAM can lead to severe lupus nephritis in the B6 genetic background.
Assuntos
Antígenos CD/metabolismo , Autoanticorpos/imunologia , Doenças Autoimunes/imunologia , Glomerulonefrite/imunologia , Haplótipos/genética , Receptores de Superfície Celular/metabolismo , Receptores de IgG/deficiência , Animais , Anticorpos Antinucleares/imunologia , Linfócitos B/imunologia , Cromossomos de Mamíferos/genética , Feminino , Loci Gênicos , Centro Germinativo/metabolismo , Contagem de Linfócitos , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Receptores de Superfície Celular/deficiência , Receptores de IgG/metabolismo , Membro 1 da Família de Moléculas de Sinalização da Ativação Linfocitária , Baço/patologiaRESUMO
We performed small-angle x-ray scattering measurements of liquid Te using a synchrotron radiation facility and observed maximum scattering intensity near 620 K in the supercooled region (melting temperature 723 K). This indicates that density inhomogeneity exists in liquid Te, and the fact that this temperature coincides with the temperature at which the specific heat, sound velocity, and thermal expansion coefficient reach their maxima means that this density inhomogeneity is the cause of these thermodynamic anomalies. The thermodynamic anomalies in liquid Te had already been shown in the 1980s to be comprehensively explained by the inhomogeneity associated with the continuous liquid-liquid phase transition (LLT), but direct experimental evidence for the existence of the inhomogeneity had not been obtained. The present results, together with those already obtained for mixture systems (Te-Se, Te-Ge), indicate the existence of inhomogeneity associated with LLT in liquid Te systems, and strongly support the model. Recently, similar maximum scattering intensity has also been observed in supercooled liquid water, which exhibits thermodynamic anomalies similar to those of Te, indicating the universality of the inhomogeneous model or LLT scenario to explain the thermodynamics of such 'anomalous liquids'. Further development of the LLT scenario is expected in near future.
RESUMO
Semaphorins and their receptors have diverse functions in axon guidance, organogenesis, vascularization and/or angiogenesis, oncogenesis and regulation of immune responses. The primary receptors for semaphorins are members of the plexin family. In particular, plexin-A1, together with ligand-binding neuropilins, transduces repulsive axon guidance signals for soluble class III semaphorins, whereas plexin-A1 has multiple functions in chick cardiogenesis as a receptor for the transmembrane semaphorin, Sema6D, independent of neuropilins. Additionally, plexin-A1 has been implicated in dendritic cell function in the immune system. However, the role of plexin-A1 in vivo, and the mechanisms underlying its pleiotropic functions, remain unclear. Here, we generated plexin-A1-deficient (plexin-A1(-/-)) mice and identified its important roles, not only in immune responses, but also in bone homeostasis. Furthermore, we show that plexin-A1 associates with the triggering receptor expressed on myeloid cells-2 (Trem-2), linking semaphorin-signalling to the immuno-receptor tyrosine-based activation motif (ITAM)-bearing adaptor protein, DAP12. These findings reveal an unexpected role for plexin-A1 and present a novel signalling mechanism for exerting the pleiotropic functions of semaphorins.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Osso e Ossos/fisiologia , Imunidade , Proteínas do Tecido Nervoso/fisiologia , Receptores de Superfície Celular/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Homeostase , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/metabolismo , Receptores de Superfície Celular/deficiência , Receptores de Superfície Celular/metabolismo , Receptores Imunológicos/metabolismo , Transdução de SinaisRESUMO
The injection of Clostridium difficile toxin A into the ileal loops caused fluid accumulation with the destruction of intestinal epithelial structure and the recruitment of neutrophils and macrophages. Concomitantly, intraileal gene expression of CX3CL1/fractalkine (FKN) and its receptor, CX3CR1, was enhanced. When treated with toxin A in a similar manner, CX3CR1-deficient (CX3CR1(-/-)) mice exhibited exaggerated fluid accumulation, histopathological alterations, and neutrophil recruitment, but not macrophage infiltration. Mice reconstituted with CX3CR1(-/-) mouse-derived bone marrow cells exhibited exacerbated toxin A-induced enteritis, indicating that the lack of the CX3CR1 gene for hematopoietic cells aggravated toxin A-induced enteritis. A heme oxygenase-1 (HO-1) inhibitor, tin-protoporphyrin-IX, markedly increased fluid accumulation in toxin A-treated wild-type mice, indicating the protective roles of HO-1 in this situation. HO-1 expression was detected mainly in F4/80-positive cells expressing CX3CR1, and CX3CR1(-/-) mice failed to increase HO-1 expression after toxin A treatment. Moreover, CX3CL1/FKN induced HO-1 gene expression by isolated lamina propria-derived macrophages or a mouse macrophage cell line, RAW264.7, through the activation of the ERK signal pathway. Thus, CX3CL1/FKN could induce CX3CR1-expressing macrophages to express HO-1, thereby ameliorating toxin A-induced enteritis.
Assuntos
Toxinas Bacterianas/toxicidade , Enterite/imunologia , Enterite/prevenção & controle , Enterotoxinas/toxicidade , Regulação Enzimológica da Expressão Gênica/imunologia , Heme Oxigenase-1/biossíntese , Sistema de Sinalização das MAP Quinases/imunologia , Receptores de Quimiocinas/fisiologia , Animais , Toxinas Bacterianas/administração & dosagem , Toxinas Bacterianas/antagonistas & inibidores , Receptor 1 de Quimiocina CX3C , Linhagem Celular , Quimiocina CX3CL1/biossíntese , Quimiocina CX3CL1/genética , Clostridioides difficile/imunologia , Relação Dose-Resposta Imunológica , Enterite/enzimologia , Enterotoxinas/administração & dosagem , Enterotoxinas/antagonistas & inibidores , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Heme Oxigenase-1/genética , Heme Oxigenase-1/uso terapêutico , Sistema de Sinalização das MAP Quinases/genética , Macrófagos/enzimologia , Macrófagos/imunologia , Macrófagos/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mucosa/enzimologia , Mucosa/imunologia , Mucosa/microbiologia , Receptores de Quimiocinas/deficiência , Receptores de Quimiocinas/genética , Regulação para Cima/genética , Regulação para Cima/imunologiaRESUMO
Inelastic x-ray scattering (IXS) measurements were performed for observing the excitation of bulk plasmons in metallic liquid silicon (Si). The peak due to plasmon excitation was observed within the energy loss around 17 eV. Combined with IXS data of crystalline Si measured at several elevated temperatures, it was found that temperature dependence of the excitation energy in the crystalline solid state is explained by the electron gas including the band gap effect, whereas in the metallic liquid state near the melting point, it exhibits a departure from the electron gas; the plasmon energy takes a lower value than that of the electron gas. Such lowering of plasmon energies is reasonably explained by a model incorporating semiconducting component to the electron gas. Non-simple metallic nature in liquid silicon is highlighted by the observation of electron collective dynamics.
RESUMO
The dynamic structure factorS(Q,E), whereQandEare momentum and energy transfer, respectively, has been measured for liquid Eu8Ga16Ge30(EGG), using inelastic x-ray scattering. The excitation energy of the longitudinal acoustic mode in the liquid was scaled to that in liquid Ba8Ga16Sn30(BGS) with the effective mass. This result means that the local structure in both liquids are similar. The longitudinal acoustic excitation energy of type-I clathrate compound EGG disperses faster than that in the liquid, suggesting that the interatomic force is weakened on melting. The lower energy excitation was observed in both liquid EGG and liquid BGS. In comparison with the longitudinal phonon dispersion in crystalline clathrate compound EGG obtained by density functional theory-based calculations, the lower energy in the liquid was found to be near the optical mode energy. The result indicates that the lower energy mode arises from the relative motion between Eu and (Ga, Ge) atoms.
RESUMO
Sa15-21, a monoclonal antibody against mouse Toll-like receptor (TLR) 4, can protect mice from lipopolysaccharide (LPS)/D-galactosamine-induced acute lethal hepatitis. Herein, we investigated the molecular mechanisms underlying Sa15-21-mediated regulation of TLR4 signaling in macrophages. Results showed that Sa15-21 enhanced the production of proinflammatory cytokines and attenuated the production of anti-inflammatory cytokines in LPS-stimulated macrophages. Western blotting analysis revealed that Sa15-21 pretreatment had no effect on NF-κB and MAPK signaling in LPS-stimulated macrophages; however, Sa15-21 treatment alone led to a weak and delayed activation of NF-κB and MAPK signaling without any effect on proinflammatory cytokine production. By contrast, Sa15-21 failed to induce the activation of interferon regulatory factor 3. Taken together, our results indicate that Sa15-21 sensitizes macrophages to facilitate the inflammatory response via TLR signaling.
Assuntos
Lipopolissacarídeos , NF-kappa B , Animais , Camundongos , Lipopolissacarídeos/farmacologia , Macrófagos , Citocinas , Anticorpos Monoclonais/farmacologiaRESUMO
Osteoclasts, cells of myeloid lineage, play a unique role in bone resorption, maintaining skeletal homeostasis in concert with bone-producing osteoblasts. Osteoclast development and maturation (osteoclastogenesis) is driven by receptor activator of NF-kappaB ligand and macrophage-colony stimulating factor and invariably requires a signal initiated by immunoreceptor tyrosine-based activation motif (ITAM)-harboring Fc receptor common gamma chain or DNAX-activating protein (DAP)12 (also referred to as KARAP or TYROBP) that associates with the cognate immunoreceptors. Here, we show that a third adaptor, YINM costimulatory motif-harboring DAP10, triggers osteoclastogenesis and bone remodeling. DAP10-deficient (DAP10(-/-)) mice become osteopetrotic with age, concomitant with a reduction in osteoclasts. The DAP10-associating receptor was identified as myeloid DAP12-associating lectin-1 (MDL-1), whose physiologic function has not been found. MDL-1-mediated stimulation of osteoclast precursor cells resulted in augmented osteoclastogenesis in vitro. MDL-1 associates with both DAP12 and DAP10 in osteoclasts and bone marrow-derived macrophages, where DAP10 association depends almost entirely on DAP12, suggesting a formation of MDL-1-DAP12/DAP10 trimolecular complexes harboring ITAM/YINM stimulatory/costimulatory motifs within a complex that could be a novel therapeutic target for skeletal and inflammatory diseases.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Lectinas Tipo C/metabolismo , Osteoclastos/citologia , Osteoclastos/metabolismo , Osteogênese , Receptores de Superfície Celular/metabolismo , Receptores Imunológicos/metabolismo , Envelhecimento/imunologia , Envelhecimento/patologia , Animais , Osso e Ossos/patologia , Contagem de Células , Camundongos , Osteopetrose/metabolismo , Osteopetrose/patologia , Ligação Proteica , Receptores Imunológicos/deficiênciaRESUMO
Immunoglobulin-like receptors (IgLR) , expressed in a wide range of cells in immune system, provide a positive and negative regulation of immune responses. Activation signals initiated by activating IgLR associating with ITAM-containing adapter proteins DAP12 and FcRγ are indispensable for the development of osteoclasts. On the other hand, ITIM signals induced by inhibitory IgLR regulate osteoclast development and activation. Thus, ITAM and ITIM play important roles in the maintenance of bone homeostasis.