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IMPORTANCE: It is well known that influenza A viruses (IAV) initiate host cell infection by binding to sialic acid, a sugar molecule present at the ends of various sugar chains called glycoconjugates. These sugar chains can vary in chain length, structure, and composition. However, it remains unknown if IAV strains preferentially bind to sialic acid on specific glycoconjugate type(s) for host cell infection. Here, we utilized CRISPR gene editing to abolish sialic acid on different glycoconjugate types in human lung cells, and evaluated human versus avian IAV infections. Our studies show that both human and avian IAV strains can infect human lung cells by utilizing any of the three major sialic acid-containing glycoconjugate types, specifically N-glycans, O-glycans, and glycolipids. Interestingly, simultaneous elimination of sialic acid on all three major glycoconjugate types in human lung cells dramatically decreased human IAV infection, yet had little effect on avian IAV infection. These studies show that avian IAV strains effectively utilize other less prevalent glycoconjugates for infection, whereas human IAV strains rely on a limited repertoire of glycoconjugate types. The remarkable ability of avian IAV strains to utilize diverse glycoconjugate types may allow for easy transmission into new host species.
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Vírus da Influenza A , Influenza Humana , Pulmão , Receptores de Superfície Celular , Animais , Humanos , Proteínas de Transporte/metabolismo , Glicoconjugados/metabolismo , Vírus da Influenza A/metabolismo , Pulmão/virologia , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/metabolismo , Açúcares/metabolismo , Influenza Aviária/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores Virais/metabolismoRESUMO
Infections caused by multi-drug-resistant (MDR) bacteria are a global threat to human health. As venoms are the source of biochemically diverse bioactive proteins and peptides, we investigated the antimicrobial activity and murine skin infection model-based wound healing efficacy of a 13 kDa protein. The active component PaTx-II was isolated from the venom of Pseudechis australis (Australian King Brown or Mulga Snake). PaTx-II inhibited the growth of Gram-positive bacteria in vitro, with moderate potency (MICs of 25 µM) observed against S. aureus, E. aerogenes, and P. vulgaris. The antibiotic activity of PaTx-II was associated with the disruption of membrane integrity, pore formation, and lysis of bacterial cells, as evidenced by scanning and transmission microscopy. However, these effects were not observed with mammalian cells, and PaTx-II exhibited minimal cytotoxicity (CC50 > 1000 µM) toward skin/lung cells. Antimicrobial efficacy was then determined using a murine model of S. aureus skin infection. Topical application of PaTx-II (0.5 mg/kg) cleared S. aureus with concomitant increased vascularization and re-epithelialization, promoting wound healing. As small proteins and peptides can possess immunomodulatory effects to enhance microbial clearance, cytokines and collagen from the wound tissue samples were analyzed by immunoblots and immunoassays. The amounts of type I collagen in PaTx-II-treated sites were elevated compared to the vehicle controls, suggesting a potential role for collagen in facilitating the maturation of the dermal matrix during wound healing. Levels of the proinflammatory cytokines interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and interleukin-10 (IL-10), factors known to promote neovascularization, were substantially reduced by PaTx-II treatment. Further studies that characterize the contributions towards efficacy imparted by in vitro antimicrobial and immunomodulatory activity with PaTx-II are warranted.
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Anti-Infecciosos , Venenos de Cnidários , Colubridae , Humanos , Animais , Camundongos , Staphylococcus aureus , Austrália , Cicatrização , Anti-Infecciosos/farmacologia , Venenos de Cnidários/farmacologia , Colágeno/farmacologia , Peptídeos/farmacologia , Citocinas/farmacologia , MamíferosRESUMO
Virus-based tumour vaccines offer many advantages compared to other antigen-delivering systems. They generate concerted innate and adaptive immune response, and robust CD8+ T cell responses. We engineered a non-replicating pseudotyped influenza virus (S-FLU) to deliver the well-known cancer testis antigen, NY-ESO-1 (NY-ESO-1 S-FLU). Intranasal or intramuscular immunization of NY-ESO-1 S-FLU virus in mice elicited a strong NY-ESO-1-specific CD8+ T cell response in lungs and spleen that resulted in the regression of NY-ESO-1-expressing lung tumour and subcutaneous tumour, respectively. Combined administration with anti-PD-1 antibody, NY-ESO-1 S-FLU virus augmented the tumour protection by reducing the tumour metastasis. We propose that the antigen delivery through S-FLU is highly efficient in inducing antigen-specific CD8+ T cell response and protection against tumour development in combination with PD-1 blockade.
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Inibidores de Checkpoint Imunológico , Orthomyxoviridae , Masculino , Camundongos , Animais , Antígenos de Neoplasias , Proteínas de Membrana , Imunização , Anticorpos , Linfócitos T CD8-PositivosRESUMO
Objectives: Metastasis is the principal cause of breast cancer mortality. Vaccines targeting breast cancer antigens have yet to demonstrate clinical efficacy, and there remains an unmet need for safe and effective treatment to reduce the risk of metastasis, particularly for people with triple-negative breast cancer (TNBC). Certain glycolipids can act as vaccine adjuvants by specifically stimulating natural killer T (NKT) cells to provide a universal form of T-cell help. Methods: We designed and made a series of conjugate vaccines comprising a prodrug of the NKT cell-activating glycolipid α-galactosylceramide covalently linked to tumor-expressed peptides, and assessed these using E0771- and 4T1-based breast cancer models in vivo. We employed peptides from the model antigen ovalbumin and from clinically relevant breast cancer antigens HER2 and NY-ESO-1. Results: Glycolipid-peptide conjugate vaccines that activate NKT cells led to antigen-presenting cell activation, induced inflammatory cytokines, and, compared with peptide alone or admixed peptide and α-galactosylceramide, specifically enhanced CD8+ T-cell responses against tumor-associated peptides. Primary tumor growth was delayed by vaccination in all tumor models. Using 4T1-based cell lines expressing HER2 or NY-ESO-1, a single administration of the relevant conjugate vaccine prevented tumor colonisation of the lung following intravenous inoculation of tumor cells or spontaneous metastasis from breast, respectively. Conclusion: Glycolipid-peptide conjugate vaccines that activate NKT cells prevent lung metastasis in breast cancer models and warrant investigation as adjuvant therapies for high-risk breast cancer.
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BACKGROUND: NY-ESO-1 is a tumor-specific, highly immunogenic, human germ cell antigen of the MAGE-1 family that is a promising vaccine and cell therapy candidate in clinical trial development. The mouse genome does not encode an NY-ESO-1 homolog thereby not subjecting transgenic T-cells to thymic tolerance mechanisms that might impair in-vivo studies. We hypothesized that an NY-ESO-1 T cell receptor (TCR) transgenic mouse would provide the unique opportunity to study avidity of TCR response against NY-ESO-1 for tumor vaccine and cellular therapy development against this clinically relevant and physiological human antigen. METHODS: To study in vitro and in vivo the requirements for shaping an effective T cell response against the clinically relevant NY-ESO-1, we generated a C57BL/6 HLA-A*0201 background TCR transgenic mouse encoding the 1G4 TCR specific for the human HLA-A2 restricted, NY-ESO-1157-165 SLLMWITQC (9C), initially identified in an NY-ESO-1 positive melanoma patient. RESULTS: The HLA-A*0201 restricted TCR was positively selected on both CD4+ and CD8+ cells. Mouse 1G4 T cells were not activated by endogenous autoimmune targets or a large library of non-cognate viral antigens. In contrast, their activation by HLA-A2 NY-ESO-1157-165 complexes was evident by proliferation, CD69 upregulation, interferon-γ production, and interleukin-2 production, and could be tuned using a twofold higher affinity altered peptide ligand, NY-ESO-1157-165V. NY-ESO-1157-165V recombinant vaccination of syngeneic mice adoptively transferred with m1G4 CD8+ T cells controlled tumor growth in vivo. 1G4 transgenic mice suppressed growth of syngeneic methylcholanthrene (MCA) induced HHD tumor cells expressing the full-length human NY-ESO-1 protein but not MCA HHD tumor cells lacking NY-ESO-1. CONCLUSIONS: The 1G4 TCR mouse model for the physiological human TCR against the clinically relevant antigen, NY-ESO-1, is a valuable tool with the potential to accelerate clinical development of NY-ESO-1-targeted T-cell and vaccine therapies.
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Antígeno HLA-A2/metabolismo , Proteínas de Neoplasias/administração & dosagem , Fragmentos de Peptídeos/administração & dosagem , Receptores de Antígenos de Linfócitos T/genética , Timoma/tratamento farmacológico , Neoplasias do Timo/tratamento farmacológico , Animais , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Vacinas Anticâncer/administração & dosagem , Vacinas Anticâncer/imunologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas de Neoplasias/imunologia , Fragmentos de Peptídeos/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Timoma/genética , Timoma/imunologia , Neoplasias do Timo/genética , Neoplasias do Timo/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Seasonal influenza virus infections cause mild illness in healthy adults, as timely viral clearance is mediated by the functions of cytotoxic T cells. However, avian H5N1 influenza virus infections can result in prolonged and fatal illness across all age groups, which has been attributed to the overt and uncontrolled activation of host immune responses. Here, we investigate how excessive innate immune responses to H5N1 impair subsequent adaptive T cell responses in the lungs. Using recombinant H1N1 and H5N1 strains sharing 6 internal genes, we demonstrate that H5N1 (2:6) infection in mice causes higher stimulation and increased migration of lung dendritic cells to the draining lymph nodes, resulting in greater numbers of virus-specific T cells in the lungs. Despite robust T cell responses in the lungs, H5N1 (2:6)-infected mice showed inefficient and delayed viral clearance compared with H1N1-infected mice. In addition, we observed higher levels of inhibitory signals, including increased PD-1 and interleukin-10 (IL-10) expression by cytotoxic T cells in H5N1 (2:6)-infected mice, suggesting that delayed viral clearance of H5N1 (2:6) was due to the suppression of T cell functions in vivo Importantly, H5N1 (2:6)-infected mice displayed decreased numbers of tissue-resident memory T cells compared with H1N1-infected mice; however, despite the decreased number of tissue-resident memory T cells, H5N1 (2:6) was protected against a heterologous challenge from H3N2 virus (X31). Taken together, our study provides mechanistic insight for the prolonged viral replication and protracted illness observed in H5N1-infected patients.IMPORTANCE Influenza viruses cause upper respiratory tract infections in humans. In healthy adults, seasonal influenza virus infections result in mild disease. Occasionally, influenza viruses endemic in domestic birds can cause severe and fatal disease even in healthy individuals. In avian influenza virus-infected patients, the host immune system is activated in an uncontrolled manner and is unable to control infection in a timely fashion. In this study, we investigated why the immune system fails to effectively control a modified form of avian influenza virus. Our studies show that T cell functions important for clearing virally infected cells are impaired by higher negative regulatory signals during modified avian influenza virus infection. In addition, memory T cell numbers were decreased in modified avian influenza virus-infected mice. Our studies provide a possible mechanism for the severe and prolonged disease associated with avian influenza virus infections in humans.
Assuntos
Virus da Influenza A Subtipo H5N1/genética , Influenza Humana/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Aves , Humanos , Imunidade Inata/imunologia , Memória Imunológica/imunologia , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Virus da Influenza A Subtipo H5N1/metabolismo , Vírus da Influenza A/fisiologia , Influenza Humana/metabolismo , Pulmão/virologia , Camundongos , Infecções por Orthomyxoviridae/virologia , Replicação Viral/genéticaRESUMO
Invariant NKT (iNKT) cells have the unique ability to shape immunity during antitumor immune responses and other forms of sterile and nonsterile inflammation. Recent studies have highlighted a variety of classes of endogenous and pathogen-derived lipid antigens that can trigger iNKT cell activation under sterile and nonsterile conditions. However, the context and mechanisms that drive the presentation of self-lipid antigens in sterile inflammation remain unclear. Here we report that endoplasmic reticulum (ER)-stressed myeloid cells, via signaling events modulated by the protein kinase RNA-like ER kinase (PERK) pathway, increase CD1d-mediated presentation of immunogenic endogenous lipid species, which results in enhanced iNKT cell activation both in vitro and in vivo. In addition, we demonstrate that actin cytoskeletal reorganization during ER stress results in an altered distribution of CD1d on the cell surface, which contributes to enhanced iNKT cell activation. These results define a previously unidentified mechanism that controls iNKT cell activation during sterile inflammation.
Assuntos
Células Apresentadoras de Antígenos/imunologia , Células Dendríticas/imunologia , Estresse do Retículo Endoplasmático/imunologia , Ativação Linfocitária , Células T Matadoras Naturais/imunologia , Animais , Apresentação de Antígeno , Antígenos CD1d/biossíntese , Antígenos CD1d/imunologia , Autoantígenos/imunologia , Carcinoma Pulmonar de Lewis/patologia , Linhagem Celular Tumoral , Técnicas de Cocultura , Citoesqueleto/ultraestrutura , Endossomos/imunologia , Glicoesfingolipídeos/imunologia , Glicoesfingolipídeos/metabolismo , Humanos , Subunidade alfa de Receptor de Interleucina-2/biossíntese , Lipídeos/imunologia , Lisossomos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Células THP-1 , Tapsigargina/farmacologia , Resposta a Proteínas não Dobradas/imunologia , eIF-2 Quinase/deficiência , eIF-2 Quinase/fisiologiaRESUMO
The emergence of influenza A viruses (IAVs) from zoonotic reservoirs poses a great threat to human health. As seasonal vaccines are ineffective against zoonotic strains, and newly transmitted viruses can quickly acquire drug resistance, there remains a need for host-directed therapeutics against IAVs. Here, we performed a genome-scale CRISPR/Cas9 knockout screen in human lung epithelial cells with a human isolate of an avian H5N1 strain. Several genes involved in sialic acid biosynthesis and related glycosylation pathways were highly enriched post-H5N1 selection, including SLC35A1, a sialic acid transporter essential for IAV receptor expression and thus viral entry. Importantly, we have identified capicua (CIC) as a negative regulator of cell-intrinsic immunity, as loss of CIC resulted in heightened antiviral responses and restricted replication of multiple viruses. Therefore, our study demonstrates that the CRISPR/Cas9 system can be utilized for the discovery of host factors critical for the replication of intracellular pathogens.
Assuntos
Sistemas CRISPR-Cas/genética , Técnicas de Inativação de Genes/métodos , Virus da Influenza A Subtipo H5N1/fisiologia , Células A549 , Biblioteca Gênica , Genoma Humano , Humanos , Virus da Influenza A Subtipo H5N1/genética , Lentivirus/genética , Proteínas de Transporte de Nucleotídeos/genética , Proteínas de Transporte de Nucleotídeos/metabolismo , Internalização do Vírus , Replicação ViralRESUMO
BACKGROUND: Microbiota integrity is essential for a growing number of physiological processes. Consequently, disruption of microbiota homeostasis correlates with a variety of pathological states. Importantly, commensal microbiota provide a shield against invading bacterial pathogens, probably by direct competition. The impact of viral infections on host microbiota composition and dynamics is poorly understood. Influenza A viruses (IAV) are common respiratory pathogens causing acute infections. Here, we show dynamic changes in respiratory and intestinal microbiota over the course of a sublethal IAV infection in a mouse model. RESULTS: Using a combination of 16S rRNA gene-specific next generation sequencing and qPCR as well as culturing of bacterial organ content, we found body site-specific and transient microbiota responses. In the lower respiratory tract, we observed only minor qualitative changes in microbiota composition. No quantitative impact on bacterial colonization after IAV infection was detectable, despite a robust antimicrobial host response and increased sensitivity to bacterial super infection. In contrast, in the intestine, IAV induced robust depletion of bacterial content, disruption of mucus layer integrity, and higher levels of antimicrobial peptides in Paneth cells. As a functional consequence of IAV-mediated microbiota depletion, we demonstrated that the small intestine is rendered more susceptible to bacterial pathogen invasion, in a Salmonella typhimurium super infection model. CONCLUSION: We show for the first time the consequences of IAV infection for lower respiratory tract and intestinal microbiobiota in a qualitative and quantitative fashion. The discrepancy of relative 16S rRNA gene next-generation sequencing (NGS) and normalized 16S rRNA gene-specific qPCR stresses the importance of combining qualitative and quantitative approaches to correctly analyze composition of organ associated microbial communities. The transiently induced dysbiosis underlines the overall stability of microbial communities to effects of acute infection. However, during a short-time window, specific ecological niches might lose their microbiota shield and remain vulnerable to bacterial invasion.
Assuntos
Bactérias/classificação , Infecções por Orthomyxoviridae/microbiologia , Celulas de Paneth/microbiologia , RNA Ribossômico 16S/genética , Animais , Bactérias/genética , Bactérias/isolamento & purificação , DNA Bacteriano/genética , DNA Ribossômico/genética , Modelos Animais de Doenças , Disbiose/microbiologia , Feminino , Microbioma Gastrointestinal , Vírus da Influenza A/patogenicidade , Camundongos , Análise de Sequência de DNARESUMO
A wealth of in vitro data has demonstrated a central role for receptor ubiquitination in endocytic sorting. However, how receptor ubiquitination functions in vivo is poorly understood. Herein, we report that ablation of B cell antigen receptor ubiquitination in vivo uncouples the receptor from CD19 phosphorylation and phosphatidylinositol 3-kinase (PI3K) signals. These signals are necessary and sufficient for accumulating phosphatidylinositol (3,4,5)-trisphosphate (PIP3) on B cell receptor-containing early endosomes and proper sorting into the MHC class II antigen-presenting compartment (MIIC). Surprisingly, MIIC targeting is dispensable for T cell-dependent immunity. Rather, it is critical for activating endosomal toll-like receptors and antiviral humoral immunity. These findings demonstrate a novel mechanism of receptor endosomal signaling required for specific peripheral immune responses.
Assuntos
Antígenos CD79/metabolismo , Endossomos/metabolismo , Fosfatidilinositol 3-Quinase/metabolismo , Transdução de Sinais , Ubiquitinação , Animais , Linfócitos B/metabolismo , Endocitose , Antígenos de Histocompatibilidade Classe II/metabolismo , Imunidade Humoral , Masculino , Camundongos Endogâmicos C57BL , Fosfatos de Fosfatidilinositol/metabolismo , Receptores de Antígenos de Linfócitos B/metabolismo , Receptores Toll-Like/metabolismo , Ubiquitina/metabolismoRESUMO
The cellular and molecular mechanisms underpinning the unusually high virulence of highly pathogenic avian influenza H5N1 viruses in mammalian species remains unknown. Here, we investigated if the cell tropism of H5N1 virus is a determinant of enhanced virulence in mammalian species. We engineered H5N1 viruses with restricted cell tropism through the exploitation of cell type-specific microRNA expression by incorporating microRNA target sites into the viral genome. Restriction of H5N1 replication in endothelial cells via miR-126 ameliorated disease symptoms, prevented systemic viral spread and limited mortality, despite showing similar levels of peak viral replication in the lungs as compared to control virus-infected mice. Similarly, restriction of H5N1 replication in endothelial cells resulted in ameliorated disease symptoms and decreased viral spread in ferrets. Our studies demonstrate that H5N1 infection of endothelial cells results in excessive production of cytokines and reduces endothelial barrier integrity in the lungs, which culminates in vascular leakage and viral pneumonia. Importantly, our studies suggest a need for a combinational therapy that targets viral components, suppresses host immune responses, and improves endothelial barrier integrity for the treatment of highly pathogenic H5N1 virus infections.
Assuntos
Células Endoteliais/virologia , Virus da Influenza A Subtipo H5N1/fisiologia , Virus da Influenza A Subtipo H5N1/patogenicidade , Infecções por Orthomyxoviridae/patologia , Tropismo Viral/fisiologia , Animais , Western Blotting , Modelos Animais de Doenças , Feminino , Furões , Citometria de Fluxo , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , VirulênciaRESUMO
Gouty arthritis results from the generation of monosodium urate (MSU) crystals within joints. These MSU crystals elicit acute inflammation characterized by massive infiltration of neutrophils and monocytes that are mobilized by the pro-inflammatory cytokine IL-1ß. MSU crystals also activate the complement system, which regulates the inflammatory response; however, it is unclear whether or how MSU-mediated complement activation is linked to IL-1ß release in vivo, and the various roles that might be played by individual components of the complement cascade. Here we show that exposure to MSU crystals in vivo triggers the complement cascade, leading to the generation of the biologically active complement proteins C3a and C5a. C5a, but not C3a, potentiated IL-1ß and IL-1α release from LPS-primed MSU-exposed peritoneal macrophages and human monocytic cells in vitro; while in vivo MSU-induced C5a mediated murine neutrophil recruitment as well as IL-1ß production at the site of inflammation. These effects were significantly ameliorated by treatment of mice with a C5a receptor antagonist. Mechanistic studies revealed that C5a most likely increased NLRP3 inflammasome activation via production of reactive oxygen species (ROS), and not through increased transcription of inflammasome components. Therefore we conclude that C5a generated upon MSU-induced complement activation increases neutrophil recruitment in vivo by promoting IL-1 production via the generation of ROS, which activate the NLRP3 inflammasome. Identification of the C5a receptor as a key determinant of IL-1-mediated recruitment of inflammatory cells provides a novel potential target for therapeutic intervention to mitigate gouty arthritis.
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This study evaluates the ability of Lactobacillus rhamnosus GG (LGG) to activate DC and neutrophils and modulate T cell activation and the impact of bacterial dose on these responses. Murine bone marrow derived DC or neutrophils were stimulated with LGG at ratios of 5 : 1, 10 : 1, and 100 : 1 (LGG : cells) and DC maturation (CD40, CD80, CD86, CD83, and MHC class II) and cytokine production (IL-10, TNF-α, and IL-12p70) were examined after 2 h and 18 h coculture and compared to the ability of BCG (the present immunotherapeutic agent for bladder cancer) to stimulate these cells. A 2 h exposure to 100 : 1 (high dose) or an 18 h exposure to 5 : 1 or 10 : 1 (low dose), LGG : cells, induced the highest production of IL-12 and upregulation of CD40, CD80, CD86, and MHC II on DC. In DCs stimulated with LGG activated neutrophils IL-12 production decreased with increasing dose. LGG induced 10-fold greater IL-12 production than BCG. T cell IFNγ and IL-2 production was significantly greater when stimulated with DC activated with low dose LGG. In conclusion, DC or DC activated with neutrophils exposed to low dose LGG induced greater Th1 polarization in T cells and this could potentially exert stronger antitumor effects. Thus the dose of LGG used for immunotherapy could determine treatment efficacy.
Assuntos
Células Dendríticas/imunologia , Lacticaseibacillus rhamnosus/imunologia , Ativação de Neutrófilo/imunologia , Neutrófilos/imunologia , Animais , Antígenos de Superfície/metabolismo , Sobrevivência Celular/imunologia , Células Cultivadas , Citocinas/metabolismo , Células Dendríticas/metabolismo , Imunofenotipagem , Ativação Linfocitária/imunologia , Camundongos , Neutrófilos/metabolismo , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Fatores de TempoRESUMO
Retinoic acid inducible gene-I (RIG-I) is an innate RNA sensor that recognizes the influenza A virus (IAV) RNA genome and activates antiviral host responses. Here, we demonstrate that RIG-I signaling plays a crucial role in restricting IAV tropism and regulating host immune responses. Mice deficient in the RIG-I-MAVS pathway show defects in migratory dendritic cell (DC) activation, viral antigen presentation, and priming of CD8+ and CD4+ T cell responses during IAV infection. These defects result in decreased frequency of polyfunctional effector T cells and lowered protection against heterologous IAV challenge. In addition, our data show that RIG-I activation is essential for protecting epithelial cells and hematopoietic cells from IAV infection. These diverse effects of RIG-I signaling are likely imparted by the actions of type I interferon (IFN), as addition of exogenous type I IFN is sufficient to overcome the defects in antigen presentation by RIG-I deficient BMDC. Moreover, the in vivo T cell defects in RIG-I deficient mice can be overcome by the activation of MDA5 -MAVS via poly I:C treatment. Taken together, these findings demonstrate that RIG-I signaling through MAVS is critical for determining the quality of polyfunctional T cell responses against IAV and for providing protection against subsequent infection from heterologous or novel pandemic IAV strains.
Assuntos
Proteínas de Membrana/imunologia , Proteínas do Tecido Nervoso/imunologia , Infecções por Orthomyxoviridae/imunologia , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Técnicas de Cocultura , Células Dendríticas/imunologia , Modelos Animais de Doenças , Citometria de Fluxo , Vírus da Influenza A/imunologia , Interferon Tipo I/biossíntese , Interferon Tipo I/imunologia , Ativação Linfocitária/imunologia , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/metabolismo , Reação em Cadeia da Polimerase , Receptores de Superfície Celular , Linfócitos T/metabolismoRESUMO
Alveolar macrophages (AMs), localized at the pulmonary air-tissue interface, are one of the first lines of defense that interact with inhaled airborne pathogens such as influenza viruses. By using a new CD169-DTR transgenic mouse strain we demonstrate that specific and highly controlled in vivo ablation of this myeloid cell subset leads to severe impairment of the innate, but not adaptive, immune responses and critically affects the progression of the disease. In fact, AM-ablated mice, infected with a normally sublethal dose of PR8 influenza virus, showed dramatically increased virus load in the lungs, severe airway inflammation, pulmonary edema and vascular leakage, which caused the death of the infected animals. Our data highlight the possibilities for new therapeutic strategies focusing on modulation of AMs, which may efficiently boost innate responses to influenza infections.
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Imunidade Adaptativa , Vírus da Influenza A Subtipo H1N1 , Macrófagos Alveolares/fisiologia , Infecções por Orthomyxoviridae/imunologia , Animais , Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/fisiologia , Feminino , Pulmão/virologia , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae/patologia , Infecções por Orthomyxoviridae/virologia , Lectina 1 Semelhante a Ig de Ligação ao Ácido Siálico/fisiologia , Carga ViralRESUMO
Basic phospholipase A2 was identified from the venom of the eastern diamondback rattlesnake. The Crotalus adamanteus toxin-II (CaTx-II) induced bactericidal effects (7.8 µg/ml) on Staphylococcus aureus, while on Burkholderia pseudomallei (KHW), and Enterobacter aerogenes were killed at 15.6 µg/ml. CaTx-II caused pore formation and membrane damaging effects on the bacterial cell wall. CaTx-II was not cytotoxic on lung (MRC-5), skin fibroblast (HEPK) cells and in mice. CaTx-II-treated mice showed significant wound closure and complete healing by 16 days as compared to untreated controls (**P<0.01). Histological examination revealed enhanced collagen synthesis and neovascularization after treatment with CaTx-II versus 2% Fusidic Acid ointment (FAO) treated controls. Measurement of tissue cytokines revealed that interleukin-1 beta (IL-1ß) expression in CaTx-II treated mice was significantly suppressed versus untreated controls. In contrast, cytokines involved in wound healing and cell migration i.e., monocyte chemotactic protein-1 (MCP-1), fibroblast growth factor-basic (FGF-b), chemokine (KC), granulocyte-macrophage colony-stimulating factor (GM-CSF) were significantly enhanced in CaTx-II treated mice, but not in the controls. CaTx-II also modulated nuclear factor-kappa B (NF-κB) activation during skin wound healing. The CaTx-II protein highlights distinct snake proteins as a potential source of novel antimicrobial agents with significant therapeutic application for bacterial skin infections.
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Antibacterianos/farmacologia , Venenos de Crotalídeos/farmacologia , Crotalus/metabolismo , Cicatrização/efeitos dos fármacos , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/toxicidade , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Bactérias/ultraestrutura , Morte Celular/efeitos dos fármacos , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Colágeno/metabolismo , Contagem de Colônia Microbiana , Venenos de Crotalídeos/química , Venenos de Crotalídeos/isolamento & purificação , Venenos de Crotalídeos/toxicidade , Citocinas/metabolismo , Epitélio/efeitos dos fármacos , Epitélio/patologia , Humanos , Mediadores da Inflamação/metabolismo , L-Lactato Desidrogenase/metabolismo , Masculino , Camundongos , Testes de Sensibilidade Microbiana , NF-kappa B/metabolismo , Análise de Sequência de Proteína , Pele/efeitos dos fármacos , Pele/patologiaRESUMO
The factors that regulate the contraction of the CD8 T cell response and the magnitude of the memory cell population against localized mucosal infections such as influenza are important for generation of efficient vaccines but are currently undefined. In this study, we used a mouse model of influenza to demonstrate that the absence of gamma interferon (IFN-γ) or IFN-γ receptor 1 (IFN-γR1) leads to aberrant contraction of antigen-specific CD8 T cell responses. The increased accumulation of the effector CD8 T cell population was independent of viral load. Reduced contraction was associated with an increased fraction of CD8 T cells expressing the interleukin-7 receptor (IL-7R) at the peak of the response, resulting in enhanced numbers of memory/memory precursor cells in IFN-γ(-/-) and IFN-γR(-/-) compared to wild-type (WT) mice. Blockade of IL-7 within the lungs of IFN-γ(-/-) mice restored the contraction of influenza virus-specific CD8 T cells, indicating that IL-7R is important for survival and is not simply a consequence of the lack of IFN-γ signaling. Finally, enhanced CD8 T cell recall responses and accelerated viral clearance were observed in the IFN-γ(-/-) and IFN-γR(-/-) mice after rechallenge with a heterologous strain of influenza virus, confirming that higher frequencies of memory precursors are formed in the absence of IFN-γ signaling. In summary, we have identified IFN-γ as an important regulator of localized viral immunity that promotes the contraction of antigen-specific CD8 T cells and inhibits memory precursor formation, thereby limiting the size of the memory cell population after an influenza virus infection.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Memória Imunológica , Vírus da Influenza A/imunologia , Influenza Humana/imunologia , Interferon gama/imunologia , Animais , Linfócitos T CD8-Positivos/citologia , Feminino , Humanos , Vírus da Influenza A/genética , Influenza Humana/genética , Influenza Humana/virologia , Interferon gama/deficiência , Interferon gama/genética , Contagem de Linfócitos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Interferon/deficiência , Receptores de Interferon/genética , Receptores de Interferon/imunologia , Receptores de Interleucina-7/genética , Receptores de Interleucina-7/imunologia , Especificidade da Espécie , Receptor de Interferon gamaRESUMO
The complement system is a potent component of the innate immune response, promoting inflammation and orchestrating defense against pathogens. However, dysregulation of complement is critical to several autoimmune and inflammatory syndromes. Elevated expression of the proinflammatory cytokine IL-1ß is often linked to such diseases. In this study, we reveal the mechanistic link between complement and IL-1ß secretion using murine dendritic cells. IL-1ß secretion occurs following intracellular caspase-1 activation by inflammasomes. We show that complement elicits secretion of both IL-1ß and IL-18 in vitro and in vivo via the NLRP3 inflammasome. This effect depends on the inflammasome components NLRP3 and ASC, as well as caspase-1 activity. Interestingly, sublethal complement membrane attack complex formation, but not the anaphylatoxins C3a and C5a, activated the NLRP3 inflammasome in vivo. These findings provide insight into the molecular processes underlying complement-mediated inflammation and highlight the possibility of targeting IL-1ß to control complement-induced disease and pathological inflammation.
Assuntos
Proteínas de Transporte/metabolismo , Caspase 1/metabolismo , Células Dendríticas/imunologia , Inflamassomos/imunologia , Interleucina-1beta/imunologia , Animais , Células da Medula Óssea , Proteínas de Transporte/genética , Células Cultivadas , Complemento C6/deficiência , Complemento C6/genética , Proteínas do Sistema Complemento/imunologia , Células Dendríticas/metabolismo , Ativação Enzimática , Inflamação/imunologia , Interleucina-18/biossíntese , Interleucina-18/imunologia , Interleucina-18/metabolismo , Interleucina-1beta/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR , Receptor da Anafilatoxina C5a/deficiência , Receptor da Anafilatoxina C5a/genética , Receptores de Complemento/deficiência , Receptores de Complemento/genética , Transdução de SinaisRESUMO
Trafficking of lung dendritic cells (DCs) to the draining lymph node (dLN) is a crucial step for the initiation of T cell responses upon pathogen challenge. However, little is known about the factors that regulate lung DC migration to the dLN. In this study, using a model of influenza infection, we demonstrate that complement component C3 is critically required for efficient emigration of DCs from the lung to the dLN. C3 deficiency affect lung DC-mediated viral antigen transport to the dLN, resulting in severely compromised priming of virus-specific T cell responses. Consequently, C3-deficient mice lack effector T cell response in the lungs that affected viral clearance and survival. We further show that direct signaling by C3a and C5a through C3aR and C5aR respectively expressed on lung DCs is required for their efficient trafficking. However, among lung DCs, only CD103(+) DCs make a significant contribution to lung C5a levels and exclusively produce high levels of C3 and C5 during influenza infection. Collectively, our findings show that complement has a profound impact on immune regulation by controlling tissue DC trafficking and highlights a potential utility for complement as an adjuvant in novel vaccine strategies.
Assuntos
Antígenos CD/metabolismo , Complemento C3/metabolismo , Complemento C5a/metabolismo , Células Dendríticas/metabolismo , Cadeias alfa de Integrinas/metabolismo , Pulmão/metabolismo , Infecções por Orthomyxoviridae/metabolismo , Animais , Antígenos Virais , Movimento Celular , Complemento C3/deficiência , Células Dendríticas/virologia , Pulmão/virologia , Camundongos , Camundongos Knockout , Infecções por Orthomyxoviridae/mortalidade , Infecções por Orthomyxoviridae/virologia , Receptor da Anafilatoxina C5a/metabolismo , Receptores de Complemento/metabolismo , Transdução de Sinais , Taxa de Sobrevida , Linfócitos T/metabolismo , Carga Viral , VírusRESUMO
Lactobacillus rhamnosus strain GG (LGG) is a probiotic organism. In this present study, LGG that express the green fluorescence protein (LGG-GFP) and IL-2 and GFP as a fusion protein (LGG-IL-2-GFP) were used to examine bacterial uptake and the immune response induced by oral immunization. Using TEM to examine the intestinal tissue, the Lactobacilli were localized in M cells and in venules. After oral immunization, most of the bacteria were excreted in feces only a small fraction (0.15%) was retained in the intestine at 48 hr. However, more LGG-IL-2-GFP was found in the MLN and spleen than LGG-GFP. The loop ligation method was used to evaluate LGG uptake and both LGG-GFP and LGG-IL-2-GFP were found to translocate at the same rate. Analysis of LGG internalization in J774 macrophage cells indicated that IL-2 increased survival of LGG and this may explain the increased presence of these bacteria in the MLN for a longer period. After oral immunization, specific mucosal antibody production as well as GFP specific CTL activity was demonstrated. IL-2 co-expression with GFP further enhanced antibody production and CTL activity. In conclusion, Lactobacillus rhamnosus GG expressing an antigen could generate an effective immune response to the antigen and IL-2 improved the response generated probably by increasing LGG expressing antigen survival in immune cells.