RESUMO
The IL-1 Family member IL-38 has been characterized primarily as an antiinflammatory cytokine in human and mouse models of systemic diseases. Here, we examined the role of IL-38 in the murine small intestine (SI). Immunostaining of SI revealed that IL-38 expression partially confines to intestinal stem cells. Cultures of intestinal organoids reveal IL-38 functions as a growth factor by increasing organoid size via inducing WNT3a. In contrast, organoids from IL-38-deficient mice develop more slowly. This reduction in size is likely due to the downregulation of intestinal stemness markers (i.e., Fzd5, Ephb2, and Olfm4) expression compared with wild-type organoids. The IL-38 binding to IL-1R6 and IL-1R9 is still a matter of debate. Therefore, to analyze the molecular mechanisms of IL-38 signaling, we also examined organoids from IL-1R9-deficient mice. Unexpectedly, these organoids, although significantly smaller than wild type, respond to IL-38, suggesting that IL-1R9 is not involved in IL-38 signaling in the stem cell crypt. Nevertheless, silencing of IL-1R6 disabled the organoid response to the growth property of IL-38, thus suggesting IL-1R6 as the main receptor used by IL-38 in the crypt compartment. In organoids from wild-type mice, IL-38 stimulation induced low concentrations of IL-1ß which contribute to organoid growth. However, high concentrations of IL-1ß have detrimental effects on the cultures that were prevented by treatment with recombinant IL-38. Overall, our data demonstrate an important regulatory function of IL-38 as a growth factor, and as an antiinflammatory molecule in the SI, maintaining homeostasis.
Assuntos
Mucosa Intestinal , Via de Sinalização Wnt , Animais , Camundongos , Homeostase , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Interleucinas/metabolismo , Mucosa Intestinal/metabolismo , Organoides/metabolismo , Células-Tronco/metabolismoRESUMO
Sarcoidosis and chronic beryllium disease are noninfectious lung diseases that are characterized by the presence of noncaseating granulomatous inflammation. Chronic beryllium disease is caused by occupational exposure to beryllium containing particles, whereas the etiology of sarcoidosis is not known. Genetic susceptibility for both diseases is associated with particular MHC class II alleles, and CD4+ T cells are implicated in their pathogenesis. The innate immune system plays a critical role in the initiation of pathogenic CD4+ T cell responses as well as the transition to active lung disease and disease progression. In this review, we highlight recent insights into Ag recognition in chronic beryllium disease and sarcoidosis. In addition, we discuss the current understanding of the dynamic interactions between the innate and adaptive immune systems and their impact on disease pathogenesis.
Assuntos
Beriliose , Pneumopatias , Sarcoidose , Imunidade Adaptativa , Berílio , Doença Crônica , Granuloma , Humanos , Sarcoidose/complicaçõesRESUMO
T cell effector functions can be elicited by noncognate stimuli, but the mechanism and contribution of this pathway to the resolution of intracellular macrophage infections have not been defined. Here, we show that CD4(+) T helper 1 (Th1) cells could be rapidly stimulated by microbe-associated molecular patterns during active infection with Salmonella or Chlamydia. Further, maximal stimulation of Th1 cells by lipopolysaccharide (LPS) did not require T-cell-intrinsic expression of toll-like receptor 4 (TLR4), interleukin-1 receptor (IL-1R), or interferon-γ receptor (IFN-γR) but instead required IL-18R, IL-33R, and adaptor protein MyD88. Innate stimulation of Th1 cells also required host expression of TLR4 and inflammasome components that together increased serum concentrations of IL-18. Finally, the elimination of noncognate Th1 cell stimulation hindered the resolution of primary Salmonella infection. Thus, the in vivo bactericidal capacity of Th1 cells is regulated by the response to noncognate stimuli elicited by multiple innate immune receptors.
Assuntos
Imunidade Inata/imunologia , Inflamassomos/metabolismo , Transdução de Sinais , Células Th1/imunologia , Receptores Toll-Like/metabolismo , Animais , Carga Bacteriana/imunologia , Antígenos CD4/imunologia , Chlamydia/fisiologia , Citometria de Fluxo , Interleucina-18/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , Salmonella/fisiologia , Receptor 4 Toll-Like/metabolismoRESUMO
Inflammasomes have been implicated in the detection and clearance of a variety of bacterial pathogens, but little is known about whether this innate sensing mechanism has any regulatory effect on the expression of stimulatory ligands by the pathogen. During infection with Salmonella and many other pathogens, flagellin is a major activator of NLRC4 inflammasome-mediated macrophage pyroptosis and pathogen eradication. Salmonella switches to a flagellin-low phenotype as infection progresses to avoid this mechanism of clearance by the host. However, the host cues that Salmonella perceives to undergo this switch remain unclear. Here, we report an unexpected role of the NLRC4 inflammasome in promoting expression of its microbial ligand, flagellin, and identify a role for type 1 IFN signaling in switching of Salmonella to a flagellin-low phenotype. Early in infection, activation of NLRC4 by flagellin initiates pyroptosis and concomitant release of lysophospholipids which in turn enhance expression of flagellin by Salmonella thereby amplifying its ability to elicit cell death. TRIF-dependent production of type 1 IFN, however, later represses NLRC4 and the lysophospholipid biosynthetic enzyme iPLA2, causing a decline in intracellular lysophospholipids that results in down-regulation of flagellin expression by Salmonella These findings reveal a previously unrecognized immune-modulating regulatory cross-talk between endosomal TLR signaling and cytosolic NLR activation with significant implications for the establishment of infection with Salmonella.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Flagelina/metabolismo , Fosfolipases A2 do Grupo VI/metabolismo , Interferon Tipo I/metabolismo , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas de Ligação ao Cálcio/genética , Células Cultivadas , Modelos Animais de Doenças , Regulação para Baixo , Flagelina/imunologia , Fosfolipases A2 do Grupo VI/antagonistas & inibidores , Humanos , Imunidade Inata , Inflamassomos/efeitos dos fármacos , Inflamassomos/imunologia , Inflamassomos/metabolismo , Cetonas/administração & dosagem , Lipopolissacarídeos/administração & dosagem , Lipopolissacarídeos/imunologia , Lisofosfolipídeos/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Naftalenos/administração & dosagem , Cultura Primária de Células , Piroptose/imunologia , Infecções por Salmonella/microbiologia , Salmonella typhimurium/isolamento & purificação , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/imunologiaRESUMO
HIV type 1 is associated with pulmonary dysfunction that is exacerbated by cigarette smoke. Alveolar macrophages (AM) are the most prominent immune cell in the alveolar space. These cells play an important role in clearing inhaled pathogens and regulating the inflammatory environment; however, how HIV infection impacts AM phenotype and function is not well understood, in part because of their autofluorescence and the absence of well-defined surface markers. The main aim of this study was to evaluate the impact of HIV infection on human AM and to compare the effect of smoking on their phenotype and function. Time-of-flight mass cytometry and RNA sequencing were used to characterize macrophages from human bronchoalveolar lavage of HIV-infected and -uninfected smokers and nonsmokers. We found that the frequency of CD163+ anti-inflammatory AM was decreased, whereas CD163-CCR7+ proinflammatory AM were increased in HIV infection. HIV-mediated proinflammatory polarization was associated with increased levels of inflammatory cytokines and macrophage activation. Conversely, smoking heightened the inflammatory response evident by change in the expression of CXCR4 and TLR4. Altogether, these findings suggest that HIV infection, along with cigarette smoke, favors a proinflammatory macrophage phenotype associated with enhanced expression of inflammatory molecules. Further, this study highlights time-of-flight mass cytometry as a reliable method for immunophenotyping the highly autofluorescent cells present in the bronchoalveolar lavage of cigarette smokers.
Assuntos
Anti-Inflamatórios/imunologia , Infecções por HIV/imunologia , Inflamação/imunologia , Macrófagos Alveolares/imunologia , Adulto , Líquido da Lavagem Broncoalveolar/imunologia , Citocinas/imunologia , Feminino , Humanos , Imunofenotipagem/métodos , Pulmão/imunologia , Masculino , Pessoa de Meia-Idade , Fumantes , Fumar/imunologiaRESUMO
Early recognition of neoantigen-expressing cells is complex, involving multiple immune cell types. In this study, in vivo, we examined how antigen-presenting cell subtypes coordinate and induce an immunological response against neoantigen-expressing cells, particularly in the absence of a pathogen-associated molecular pattern, which is normally required to license antigen-presenting cells to present foreign or self-antigens as immunogens. Using two reductionist models of neoantigen-expressing cells and two cancer models, we demonstrated that natural IgM is essential for the recognition and initiation of adaptive immunity against neoantigen-expressing cells. Natural IgM antibodies form a cellular immune complex with the neoantigen-expressing cells. This immune complex licenses surveying monocytes to present neoantigens as immunogens to CD4+ T cells. CD4+ T helper cells, in turn, use CD40L to license cross-presenting CD40+ Batf3+ dendritic cells to elicit a cytotoxic T cell response against neoantigen-expressing cells. Any break along this immunological chain reaction results in the escape of neoantigen-expressing cells. This study demonstrates the surprising, essential role of natural IgM as the initiator of a sequential signaling cascade involving multiple immune cell subtypes. This sequence is required to coordinate an adaptive immune response against neoantigen-expressing cells.
Assuntos
Imunidade Adaptativa , Antígenos de Neoplasias/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/imunologia , Imunoglobulina M/imunologia , Neoplasias Pulmonares/imunologia , Melanoma Experimental/imunologia , Animais , Células Apresentadoras de Antígenos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/patologia , Ligante de CD40/imunologia , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/patologia , Células Cultivadas , Células Dendríticas/metabolismo , Células Dendríticas/patologia , Feminino , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Ativação Linfocitária , Masculino , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Monócitos/imunologia , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
The current paradigm in macrophage biology is that some tissues mainly contain macrophages from embryonic origin, such as microglia in the brain, whereas other tissues contain postnatal-derived macrophages, such as the gut. However, in the lung and in other organs, such as the skin, there are both embryonic and postnatal-derived macrophages. In this study, we demonstrate in the steady-state lung that the mononuclear phagocyte system is comprised of three newly identified interstitial macrophages (IMs), alveolar macrophages, dendritic cells, and few extravascular monocytes. We focused on similarities and differences between the three IM subtypes, specifically, their phenotype, location, transcriptional signature, phagocytic capacity, turnover, and lack of survival dependency on fractalkine receptor, CX3CR1. Pulmonary IMs were located in the bronchial interstitium but not the alveolar interstitium. At the transcriptional level, all three IMs displayed a macrophage signature and phenotype. All IMs expressed MER proto-oncogene, tyrosine kinase, CD64, CD11b, and CX3CR1, and were further distinguished by differences in cell surface protein expression of CD206, Lyve-1, CD11c, CCR2, and MHC class II, along with the absence of Ly6C, Ly6G, and Siglec F. Most intriguingly, in addition to the lung, similar phenotypic populations of IMs were observed in other nonlymphoid organs, perhaps highlighting conserved functions throughout the body. These findings promote future research to track four distinct pulmonary macrophages and decipher the division of labor that exists between them.
Assuntos
Pulmão/citologia , Macrófagos/citologia , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Perfilação da Expressão Gênica , Macrófagos/metabolismo , Macrófagos Alveolares/citologia , Macrófagos Alveolares/metabolismo , Camundongos Endogâmicos C57BL , Especificidade de Órgãos , Fagócitos/citologia , Fagócitos/metabolismo , Fenótipo , Transcrição GênicaRESUMO
Alveolar macrophages (AMs) reside on the luminal surfaces of the airways and alveoli where they maintain host defense and promote alveolar homeostasis by ingesting inhaled particulates and regulating inflammatory responses. Recent studies have demonstrated that AMs populate the lungs during embryogenesis and self-renew throughout life with minimal replacement by circulating monocytes, except under extreme conditions of depletion or radiation injury. Here we demonstrate that on a global scale, environment appears to dictate AM development and function. Indeed, transcriptome analysis of embryonic host-derived and postnatal donor-derived AMs coexisting within the same mouse demonstrated >98% correlation and overall functional analyses were similar. However, we also identified several genes whose expression was dictated by origin rather than environment. The most differentially expressed gene not altered by environment was Marco, a gene recently demonstrated to have enhancer activity in embryonic-derived but not postnatal-derived tissue macrophages. Overall, we show that under homeostatic conditions, the environment largely dictates the programming and function of AMs, whereas the expression of a small number of genes remains linked to the origin of the cell.
Assuntos
Macrófagos Alveolares/citologia , Macrófagos Alveolares/metabolismo , Animais , Transplante de Medula Óssea , Linhagem da Célula/genética , Microambiente Celular/genética , Citocinas/biossíntese , Perfilação da Expressão Gênica , Mediadores da Inflamação/metabolismo , Macrófagos Alveolares/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Análise de Sequência com Séries de Oligonucleotídeos , Fagocitose/genética , Alvéolos Pulmonares/citologia , Alvéolos Pulmonares/embriologia , Alvéolos Pulmonares/metabolismo , Receptores Imunológicos/genética , Quimeras de TransplanteRESUMO
In transplantation, a major obstacle for graft acceptance in MHC-matched individuals is the mismatch of minor histocompatibility Ags. Minor histocompatibility Ags are peptides derived from polymorphic proteins that can be presented by APCs on MHC molecules. The APC subtype uniquely responsible for the rejection of minor Ag-mismatched grafts has not yet been identified. In this study, we examined graft rejection in three mouse models: 1) mismatch of male-specific minor Ags, 2) mismatch of minor Ags distinct from male-specific minor Ags, and 3) skin transplant. This study demonstrates that in the absence of pathogen-associated molecular patterns, Batf3-dependent dendritic cells elicit the rejection of cells and grafts expressing mismatched minor Ags. The implication of our findings in clinical transplantation may be significant, as minor Ag reactivity has been implicated in the pathogenesis of multiple allograft tissues.
Assuntos
Fatores de Transcrição de Zíper de Leucina Básica/imunologia , Células Dendríticas/imunologia , Regulação da Expressão Gênica no Desenvolvimento , Rejeição de Enxerto , Antígenos de Histocompatibilidade Menor/imunologia , Proteínas Repressoras/imunologia , Transplante de Pele , Transferência Adotiva , Animais , Fatores de Transcrição de Zíper de Leucina Básica/genética , Células Dendríticas/citologia , Feminino , Teste de Histocompatibilidade , Linfonodos/citologia , Linfonodos/imunologia , Masculino , Camundongos , Camundongos Knockout , Antígenos de Histocompatibilidade Menor/genética , Proteínas Repressoras/genética , Transdução de Sinais , Baço/citologia , Baço/imunologia , Transplante HomólogoRESUMO
RATIONALE: The pulmonary mononuclear phagocyte system is a critical host defense mechanism composed of macrophages, monocytes, monocyte-derived cells, and dendritic cells. However, our current characterization of these cells is limited because it is derived largely from animal studies and analysis of human mononuclear phagocytes from blood and small tissue resections around tumors. OBJECTIVES: Phenotypic and morphologic characterization of mononuclear phagocytes that potentially access inhaled antigens in human lungs. METHODS: We acquired and analyzed pulmonary mononuclear phagocytes from fully intact nondiseased human lungs (including the major blood vessels and draining lymph nodes) obtained en bloc from 72 individual donors. Differential labeling of hematopoietic cells via intrabronchial and intravenous administration of antibodies within the same lobe was used to identify extravascular tissue-resident mononuclear phagocytes and exclude cells within the vascular lumen. Multiparameter flow cytometry was used to identify mononuclear phagocyte populations among cells labeled by each route of antibody delivery. MEASUREMENTS AND MAIN RESULTS: We performed a phenotypic analysis of pulmonary mononuclear phagocytes isolated from whole nondiseased human lungs and lung-draining lymph nodes. Five pulmonary mononuclear phagocytes were observed, including macrophages, monocyte-derived cells, and dendritic cells that were phenotypically distinct from cell populations found in blood. CONCLUSIONS: Different mononuclear phagocytes, particularly dendritic cells, were labeled by intravascular and intrabronchial antibody delivery, countering the notion that tissue and blood mononuclear phagocytes are equivalent systems. Phenotypic descriptions of the mononuclear phagocytes in nondiseased lungs provide a precedent for comparative studies in diseased lungs and potential targets for therapeutics.
Assuntos
Citometria de Fluxo , Pulmão/imunologia , Linfonodos/imunologia , Sistema Fagocitário Mononuclear/imunologia , Fagócitos/imunologia , Adulto , Cadáver , Feminino , Humanos , MasculinoRESUMO
Toll-like receptors (TLRs) can recognize microbial patterns and utilize adaptor molecules, such as-MyD88 or (TRIF TIR-domain-containing adapter-inducing interferon-ß), to initiate downstream signaling that ultimately affects the initiation of adaptive immunity. In addition to this inflammatory role, TLR5 expression on dendritic cells can favor antigen presentation of flagellin peptides and thus increase the sensitivity of flagellin-specific T-cell responses in vitro and in vivo. Here, we examined the role of alternative signaling pathways that might regulate flagellin antigen presentation in addition to MyD88. These studies suggest a requirement for spleen tyrosine kinase, a noncanonical TLR-signaling adaptor molecule, and its downstream molecule CARD9 in regulating the sensitivity of flagellin-specific CD4(+) T-cell responses in vitro and in vivo. Thus, a previously unappreciated signaling pathway plays an important role in regulating the dominance of flagellin-specific T-cell responses.
Assuntos
Proteínas Adaptadoras de Sinalização CARD/genética , Linfócitos T CD4-Positivos/imunologia , Células Dendríticas/imunologia , Flagelina/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Tirosina Quinases/genética , Transdução de Sinais/imunologia , Imunidade Adaptativa , Animais , Apresentação de Antígeno , Proteínas Adaptadoras de Sinalização CARD/imunologia , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/metabolismo , Comunicação Celular , Proliferação de Células , Células Dendríticas/citologia , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Flagelina/imunologia , Regulação da Expressão Gênica , Imunidade Inata , Interleucina-2/genética , Interleucina-2/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Lisossomos/imunologia , Lisossomos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/deficiência , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/imunologia , Fagossomos/imunologia , Fagossomos/metabolismo , Proteínas Tirosina Quinases/imunologia , Receptores de Interleucina-2/genética , Receptores de Interleucina-2/imunologia , Quinase Syk , Receptor 5 Toll-Like/genética , Receptor 5 Toll-Like/imunologiaRESUMO
CD4(+) T cells and B cells are both essential for acquired immunity to Salmonella infection. It is well established that Salmonella inhibit host CD4(+) T-cell responses, but a corresponding inhibitory effect on B cells is less well defined. Here, we utilize an Ag tetramer and pull-down enrichment strategy to directly visualize OVA-specific B cells in mice, as they respond to infection with Salmonella-OVA. Surprisingly, OVA-specific B-cell expansion and germinal center formation was not detected until bacteria were cleared from the host. Furthermore, Salmonella infection also actively inhibited both B- and T-cell responses to the same coinjected Ag but this did not require the presence of iNOS. The Salmonella Pathogenicity Island 2 (SPI2) locus has been shown to be responsible for inhibition of Salmonella-specific CD4(+) T-cell responses, and an examination of SPI2-deficient bacteria demonstrated a recovery in B-cell expansion in infected mice. Together, these data suggest that Salmonella can simultaneously inhibit host B- and T-cell responses using SPI2-dependent mechanisms.
Assuntos
Linfócitos B/imunologia , Proteínas de Bactérias/genética , Linfócitos T CD4-Positivos/imunologia , Centro Germinativo/imunologia , Proteínas de Membrana/genética , Salmonella typhimurium/imunologia , Animais , Linfócitos B/microbiologia , Linfócitos B/patologia , Proteínas de Bactérias/imunologia , Linfócitos T CD4-Positivos/microbiologia , Linfócitos T CD4-Positivos/patologia , Proliferação de Células , Células Clonais , Citometria de Fluxo/métodos , Expressão Gênica , Centro Germinativo/microbiologia , Centro Germinativo/patologia , Interações Hospedeiro-Patógeno , Imunização , Imunofenotipagem , Lipopolissacarídeos/administração & dosagem , Proteínas de Membrana/deficiência , Proteínas de Membrana/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/imunologia , Ovalbumina/administração & dosagem , Ovalbumina/química , Ovalbumina/imunologia , Fatores de TempoRESUMO
Salmonella enterica serovar Typhi is associated with a disseminated febrile illness in humans, termed typhoid fever, while Salmonella enterica serovar Typhimurium causes localized gastroenteritis in immunocompetent individuals. One of the genetic differences between both pathogens is the presence in S. Typhi of TviA, a regulatory protein that shuts down flagellin (FliC) expression when bacteria transit from the intestinal lumen into the intestinal mucosa. Here we investigated the consequences of TviA-mediated flagellum gene regulation on flagellin-specific CD4 T cell responses in a mouse model of S. Typhimurium infection. Introduction of the S. Typhi tviA gene into S. Typhimurium suppressed antigen presentation of dendritic cells to flagellin-specific CD4 T cells in vitro. Furthermore, TviA-mediated repression of flagellin expression impaired the activation and proliferation of naive flagellin-specific CD4 T cells in Peyer's patches and mesenteric lymph nodes, which was accompanied by increased bacterial dissemination to the spleen. We conclude that TviA-mediated repression of flagellin expression reduces antigen availability, thereby weakening flagellin-specific CD4 T cell responses.
Assuntos
Antígenos de Bactérias/metabolismo , Linfócitos T CD4-Positivos/imunologia , Infecções por Salmonella/imunologia , Salmonella typhi/imunologia , Salmonella typhimurium/imunologia , Animais , Carga Bacteriana , Proteínas de Bactérias/fisiologia , Modelos Animais de Doenças , Flagelina/metabolismo , Regulação Bacteriana da Expressão Gênica , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Transcrição/fisiologiaRESUMO
Recent studies have shed light on the connection between elevated erythropoetin production/spleen erythropoiesis and increased susceptibility to Salmonella infection. In this article, we provide another mouse model, the SIRPα-deficient (Sirpαâ»/â») mouse, that manifests increased erythropoiesis as well as heightened susceptibility to Salmonella infection. Sirpαâ»/â» mice succumbed to systemic infection with attenuated Salmonella, possessing significantly higher bacterial loads in both the spleen and the liver. Moreover, Salmonella-specific Ab production and Ag-specific CD4 T cells were reduced in Sirpαâ»/â» mice compared with wild-type controls. To further characterize the potential mechanism underlying SIRPα-dependent Ag-specific CD4 T cell priming, we demonstrate that lack of SIRPα expression on dendritic cells results in less efficient Ag processing and presentation in vitro. Collectively, these findings demonstrate an indispensable role of SIRPα for protective immunity to Salmonella infection.
Assuntos
Predisposição Genética para Doença , Receptores Imunológicos/deficiência , Infecções por Salmonella/imunologia , Regulação para Cima/imunologia , Animais , Infecções por Chlamydia/genética , Infecções por Chlamydia/imunologia , Infecções por Chlamydia/patologia , Chlamydia muridarum/imunologia , Camundongos , Camundongos da Linhagem 129 , Camundongos Congênicos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Receptores Imunológicos/genética , Infecções por Salmonella/genética , Infecções por Salmonella/patologia , Salmonella typhimurium/imunologia , Regulação para Cima/genéticaRESUMO
Colorectal cancer has been linked to chronic colitis and red meat consumption, which can increase colonic iron and heme. Heme oxygenase-1 ( Hmox1 ) metabolizes heme and releases ferrous iron, but its role in colonic tumorigenesis is not well-described. Recent studies suggest that ferroptosis, the iron-dependent form of cell death, protects against colonic tumorigenesis. Ferroptosis culminates in excessive lipid peroxidation that is constrained by the antioxidative glutathione pathway. We observed increased mucosal markers of ferroptosis and glutathione metabolism in the setting of murine and human colitis, as well as murine colonic neoplasia. We obtained similar results in murine and human colonic epithelial organoids exposed to heme and the ferroptosis activator erastin, especially induction of Hmox1 . RNA sequencing of colonic organoids from mice with deletion of intestinal epithelial Hmox1 (Hmox1 ΔIEC ) revealed increased ferroptosis and activated glutathione metabolism after heme exposure. In a colitis-associated cancer model we observed significantly fewer and smaller tumors in Hmox1 ΔIEC mice compared to littermate controls. Transcriptional profiling of Hmox1 ΔIEC tumors and tumor organoids revealed increased ferroptosis and oxidative stress markers in tumor epithelial cells. In total, our findings reveal ferroptosis as an important colitis-associated cancer signature pathway, and Hmox1 as a key regulator in the tumor microenvironment.
RESUMO
TLR5-deficient mice have been reported to develop spontaneous intestinal inflammation and metabolic abnormalities. However, we report that TLR5-deficient mice from two different animal colonies display no evidence of basal inflammatory disease, metabolic abnormalities, or enhanced resistance to Salmonella infection. In contrast, the absence of TLR5 hindered the initial activation and clonal expansion of intestinal flagellin-specific CD4 T cells following oral Salmonella infection. Together, these data demonstrate that a basal inflammatory phenotype is not a consistent feature of TLR5-deficient mice and document a novel role for TLR5 in the rapid targeting of flagellin by intestinal pathogen-specific CD4 T cells.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Flagelina/imunologia , Salmonelose Animal/imunologia , Salmonelose Animal/metabolismo , Receptor 5 Toll-Like/deficiência , Animais , Inflamação/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Salmonelose Animal/patologia , Receptor 5 Toll-Like/imunologiaRESUMO
The severe acute respiratory syndrome coronavirus (SARS-CoV-2) has infected millions of individuals and continues to be a major health concern worldwide. While reverse transcription-polymerase chain reaction remains a reliable method for detecting infections, limitations of this technology, particularly cost and the requirement of a dedicated laboratory, prevent rapid viral monitoring. Antigen tests filled this need to some extent but with limitations including sensitivity and specificity, particularly against emerging variants of concern. Here, we developed aptamers against the SARS-CoV-2 Nucleocapsid protein to complement or replace antibodies in antigen detection assays. As detection reagents in ELISA-like assays, our DNA aptamers were able to detect as low as 150 pg/mL of the protein and under 150 k copies of inactivated SARS-CoV-2 Wuhan Alpha strain in viral transport medium with little cross-reactivity to other human coronaviruses (HCoVs). Further, our aptamers were reselected against the SARS-CoV-2 Omicron variant of concern, and we found two sequences that had a more than two-fold increase in signal compared to our original aptamers when used as detection reagents against protein from the Omicron strain. These findings illustrate the use of aptamers as promising alternative detection reagents that may translate for use in current tests and our findings validate the method for the reselection of aptamers against emerging viral strains.