RESUMO
Respiratory syncytial virus (RSV) is an exceptional mucosal pathogen. It specializes in infection of the ciliated respiratory epithelium, causing disease of variable severity with little or no direct systemic effects. It infects virtually all children by the age of three years and then repeatedly infects throughout life; this it does despite relatively slight variations in antigenicity, apparently by inducing selective immunological amnesia. Inappropriate or dysregulated responses to RSV can be pathogenic, causing disease-enhancing inflammation that contributes to short- and long-term effects. In addition, RSV's importance as a largely unrecognized pathogen of debilitated older people is increasingly evident. Vaccines that induce nonpathogenic protective immunity may soon be available, and it is possible that different vaccines will be optimal for infants; older children; young to middle-age adults (including pregnant women); and elderly persons. At the dawn of RSV vaccination, it is timely to review what is known (and unknown) about immune responses to this fascinating virus.
Assuntos
Mucosa Respiratória/imunologia , Infecções por Vírus Respiratório Sincicial/imunologia , Vírus Sinciciais Respiratórios/imunologia , Vacinas Virais/imunologia , Adulto , Idoso , Animais , Criança , Humanos , Evasão da Resposta Imune , Imunomodulação , Mucosa Respiratória/virologiaRESUMO
Early life is a time of increased susceptibility to infectious diseases and development of allergy. Innate lymphocytes are crucial components of the initiation and regulation of immune responses at mucosal surfaces, but functional differences in innate lymphocytes early in life are not fully described. We aimed to characterize the abundance and function of different innate lymphocyte cell populations in cord blood in comparison to that of adults. Blood was collected from adult donors and umbilical vessels at birth. Multicolor flow cytometry panels were used to identify and characterize lymphocyte populations and their capacity to produce hallmark cytokines. Lymphocytes were more abundant in cord blood compared to adults, however, mucosal-associated invariant T cells and natural killer T (NKT)-like cells, were far less abundant. The capacity of NKT-like cells to produce cytokines and their expression of the cytotoxic granule protein granzyme B and the marker of terminal differentiation CD57 were much lower in cord blood than in adults. In contrast, natural killer (NK) cells were as abundant in cord blood as in adults, they could produce IFNγ, and their expression of granzyme B was not significantly different from that of adult NK cells, although CD57 expression was lower. All innate lymphoid cell (ILC) subsets were more abundant in cord blood, and ILC1 and ILC2 were capable of production of IFNγ and IL-13, respectively. In conclusion, different innate lymphoid cells differ in both abundance and function in peripheral blood at birth and with important implications for immunity in early life.
Assuntos
Imunidade Inata , Células Matadoras Naturais , Humanos , Adulto , Recém-Nascido , Citocinas/metabolismo , Subpopulações de Linfócitos , Expressão GênicaRESUMO
UNLABELLED: During respiratory-virus infection, excessive lymphocyte activation can cause pathology both in acute infection and in exacerbations of chronic respiratory diseases. The costimulatory molecule CD161 is expressed on lymphocyte subsets implicated in promoting respiratory inflammation, including Th2, Th17, mucosally associated invariant T (MAIT) cells, and type 2 innate lymphoid cells. We asked whether the CD161 ligand LLT1 could be expressed on respiratory epithelial cells following respiratory-virus infection as a mechanism by which respiratory-virus infection could promote activation of proinflammatory lymphocytes. In response to respiratory syncytial virus (RSV) infection, expression of LLT1 was upregulated in the BEAS-2B respiratory epithelial cell line and primary human bronchial epithelial cells. Imaging studies revealed that LLT1 expression increased in both RSV-infected and cocultured uninfected cells, suggesting that soluble factors produced during infection stimulate LLT1 expression. TLR3 and TLR2/6 ligands led to a rapid increase in LLT1 mRNA in respiratory epithelial cells, as did the proinflammatory cytokines type I interferons, interleukin 1ß (IL-1ß), and tumor necrosis factor alpha (TNF-α), which are produced early in respiratory-virus infection. Immunohistochemistry confirmed the increase in LLT1 protein on the epithelial cell surface, and live-cell confocal microscopy demonstrated accumulation of epithelial LLT1 at synapses formed with CD161(+) T lymphocytes. LLT1 expression by the respiratory epithelium in response to respiratory-virus infection and inflammatory cytokines represents a novel link between innate immunity and lymphocyte activation. As a regulator of CD161(+) proinflammatory lymphocytes, LLT1 could be a novel therapeutic target in inflammation caused by respiratory-virus infection. IMPORTANCE: The immune response to respiratory-virus infection is essential for clearing the pathogen but, if excessive, can lead to tissue damage and obstruction of the airways. How viral infection activates immune cells in the lungs is not fully understood. Here, we show that LLT1 can be expressed in lung cells in response to infection. LLT1 triggers CD161, a receptor on inflammatory immune cells. This mechanism may promote activation of immune cells in the lungs in viral infection and could be a novel target for therapies aimed at reducing lung inflammation.
Assuntos
Citocinas/metabolismo , Regulação da Expressão Gênica , Lectinas Tipo C/genética , Subfamília B de Receptores Semelhantes a Lectina de Células NK/metabolismo , Receptores de Superfície Celular/genética , Mucosa Respiratória/metabolismo , Mucosa Respiratória/virologia , Vírus Sincicial Respiratório Humano/fisiologia , Receptor 3 Toll-Like/metabolismo , Linhagem Celular , Técnicas de Cocultura , Citocinas/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Sinapses Imunológicas/imunologia , Mediadores da Inflamação/metabolismo , Mediadores da Inflamação/farmacologia , Lectinas Tipo C/metabolismo , Ligantes , Receptores de Superfície Celular/metabolismo , Mucosa Respiratória/efeitos dos fármacos , Infecções por Vírus Respiratório Sincicial/genética , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Replicação ViralRESUMO
Infection with respiratory syncytial virus (RSV) in neonatal mice leads to exacerbated disease if mice are reinfected with the same virus as adults. Both T cells and the host major histocompatibility complex genotype contribute to this phenomenon, but the part played by innate immunity has not been defined. Since macrophages and natural killer (NK) cells play key roles in regulating inflammation during RSV infection of adult mice, we studied the role of these cells in exacerbated inflammation following neonatal RSV sensitization/adult reinfection. Compared to mice undergoing primary infection as adults, neonatally sensitized mice showed enhanced airway fluid levels of interleukin-6 (IL-6), alpha interferon (IFN-α), CXCL1 (keratinocyte chemoattractant/KC), and tumor necrosis factor alpha (TNF-α) at 12 to 24 h after reinfection and IL-4, IL-5, IFN-γ, and CCL11 (eotaxin) at day 4 after reinfection. Weight loss during reinfection was accompanied by an initial influx of NK cells and granulocytes into the airways and lungs, followed by T cells. NK cell depletion during reinfection attenuated weight loss but did not alter T cell responses. Depletion of alveolar macrophages with inhaled clodronate liposomes reduced both NK and T cell numbers and attenuated weight loss. These findings indicate a hitherto unappreciated role for the innate immune response in governing the pathogenic recall responses to RSV infection.
Assuntos
Imunidade Inata , Infecções por Vírus Respiratório Sincicial/complicações , Animais , Animais Recém-Nascidos , Sequência de Bases , Células Cultivadas , Primers do DNA , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Vírus Respiratório Sincicial/imunologiaRESUMO
BACKGROUND: The diverse roles of innate immune cells in the pathogenesis of asthma remain to be fully defined. Natural killer (NK) cells are innate lymphocytes that can regulate adaptive immune responses. NK cells are activated in asthma; however, their role in allergic airway inflammation is not fully understood. OBJECTIVE: We investigated the importance of NK cells in house dust mite (HDM)-triggered allergic pulmonary inflammation. Specifically, we aimed to determine the role of the major NK-cell activating receptor NKG2D and NK-cell effector functions mediated by granzyme B. METHODS: Allergic airway inflammation was induced in the airways of mice by repeated intranasal HDM extract administration and responses in wild-type and NKG2D-deficient mice were compared. Adoptive transfer studies were used to identify the cells and mechanisms involved. RESULTS: Mice that lacked NKG2D were resistant to the induction of allergic inflammation and showed little pulmonary eosinophilia, few airway TH2 cells, and no rise in serum IgE after multiple HDM-allergen exposures. However, NKG2D was not required for pulmonary inflammation after a single inoculation of allergen. NKG2D-deficient mice showed no alteration in responses to respiratory virus infection. Transfer of wild-type NK cells (but not CD3(+) cells) into NKG2D-deficient mice restored allergic inflammatory responses only if the NK cells expressed granzyme B. CONCLUSIONS: These studies established a pivotal role for NK-cell NKG2D and granzyme B in the pathogenesis of HDM-induced allergic lung disease, and identified novel therapeutic targets for the prevention and treatment of asthma.
Assuntos
Asma/etiologia , Granzimas/fisiologia , Células Matadoras Naturais/imunologia , Subfamília K de Receptores Semelhantes a Lectina de Células NK/fisiologia , Pneumonia/etiologia , Animais , Asma/imunologia , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Pneumonia/imunologia , Pyroglyphidae/imunologiaRESUMO
Severe respiratory viral infection in early life is associated with recurrent wheeze and asthma in later childhood. Neonatal immune responses tend to be skewed toward T helper 2 (Th2) responses, which may contribute to the development of a pathogenic recall response to respiratory infection. Since neonatal Th2 skewing can be modified by stimulation with Toll-like receptor (TLR) ligands, we investigated the effect of exposure to CpG oligodeoxynucleotides (TLR9 ligands) prior to neonatal respiratory syncytial virus (RSV) infection in mice. CpG preexposure was protective against enhanced disease during secondary adult RSV challenge, with a reduction in viral load and an increase in Th1 responses. A similar Th1 switch and reduction in disease were observed if CpG was administered in the interval between neonatal infection and challenge. In neonates, CpG pretreatment led to a transient increase in expression of major histocompatibility complex class II (MHCII) and CD80 on CD11c-positive cells and gamma interferon (IFN-γ) production by NK cells after RSV infection, suggesting that the protective effects may be mediated by antigen-presenting cells (APC) and NK cells. We conclude that the adverse effects of early-life respiratory viral infection on later lung health might be mitigated by conditions that promote TLR activation in the infant lung.
Assuntos
Oligodesoxirribonucleotídeos , Infecções por Vírus Respiratório Sincicial/imunologia , Animais , Células Apresentadoras de Antígenos/citologia , Ilhas de CpG , Metilação de DNA , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Recém-Nascido , Interferon gama/metabolismo , Células Matadoras Naturais/citologia , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Infecções por Vírus Respiratório Sincicial/genética , Vírus Sinciciais Respiratórios/metabolismo , Células Th1 , Receptor Toll-Like 9/metabolismoRESUMO
Natural killer (NK) cells discern the health of other cells by recognising the balance of activating and inhibitory ligands expressed by each target cell. However, how the integration of activating and inhibitory signals relates to formation of the NK cell immune synapse remains a central question in our understanding of NK cell recognition. Here we report that ligation of LFA-1 on NK cells induced asymmetrical cell spreading and migration. In contrast, ligation of the activating receptor NKG2D induced symmetrical spreading of ruffled lamellipodia encompassing a dynamic ring of f-actin, concurrent with polarization towards a target cell and a "stop" signal. Ligation of both LFA-1 and NKG2D together resulted in symmetrical spreading but co-ligation of inhibitory receptors reverted NK cells to an asymmetrical migratory configuration leading to inhibitory synapses being smaller and more rapidly disassembled. Using micropatterned activating and inhibitory ligands, signals were found to be continuously and locally integrated during spreading. Together, these data demonstrate that NK cells spread to form large, stable, symmetrical synapses if activating signals dominate, whereas asymmetrical migratory "kinapses" are favoured if inhibitory signals dominate. This clarifies how the integration of activating and inhibitory receptor signals is translated to an appropriate NK cell response.
Assuntos
Movimento Celular/fisiologia , Sinapses Imunológicas/imunologia , Células Matadoras Naturais/imunologia , Transdução de Sinais , Actinas/metabolismo , Separação Celular , Células Cultivadas , Sinapses Imunológicas/metabolismo , Células Matadoras Naturais/metabolismo , Ligantes , Antígeno-1 Associado à Função Linfocitária/metabolismo , Transdução de Sinais/imunologia , TransfecçãoRESUMO
The General Medical Council's publication 'Outcomes for Graduates' places emphasis on doctors being able to integrate biomedical science, research and scholarship with clinical practice. In response, a new paradigm of assessment was introduced for the intercalated Bachelor of Science program at Imperial College School of Medicine in 2019. This innovative approach involves authentic "active learning" assessments analogous to tasks encountered in a research environment and intends to test a wider range of applied scientific skills than traditional examinations. Written assessments include a "Letter to the Editor", scientific abstract, and production of a lay summary. A clinical case study titled "Science in Context" presents a real or virtual patient, with evaluation of current and emerging evidence within that field. Another assessment emulates the academic publishing process: groups submit a literature review and engage in reciprocal peer review of another group's work. A rebuttal letter accompanies the final submission, detailing how feedback was addressed. Scientific presentation skills are developed through tasks including a research proposal pitch, discussion of therapies or diagnostics, or review of a paper. A data management assignment develops skills in hypothesis generation, performing analysis, and drawing conclusions. Finally, students conduct an original research project which is assessed via a written report in the format of a research paper and an oral presentation involving critical analysis of their project. We aspire to train clinicians who apply scientific principles to critique the evidence base of medical practice and possess the skillset to conduct high-quality research underpinned by the principles of best clinical and academic practice. Assessment drives learning, and active learning has been demonstrated to enhance academic performance and reduce attainment gaps in science education. We therefore believe this strategy will help to successfully shape our students as future scientists and scholars as well as clinical practitioners and professionals.
RESUMO
We report the supramolecular organization of killer Ig-like receptor (KIR) phosphorylation using a technique applicable to imaging phosphorylation of any green fluorescent protein-tagged receptor at an intercellular contact or immune synapse. Specifically, we use fluorescence lifetime imaging (FLIM) to report Förster resonance energy transfer (FRET) between GFP-tagged KIR2DL1 and a Cy3-tagged generic anti-phosphotyrosine monoclonal antibody. Visualization of KIR phosphorylation in natural killer (NK) cells contacting target cells expressing cognate major histocompatibility complex class I proteins revealed that inhibitory signaling is spatially restricted to the immune synapse. This explains how NK cells respond appropriately when simultaneously surveying susceptible and resistant target cells. More surprising, phosphorylated KIR was confined to microclusters within the aggregate of KIR, contrary to an expected homogeneous distribution of KIR signaling across the immune synapse. Also, yellow fluorescent protein-tagged Lck, a kinase important for KIR phosphorylation, accumulated in a multifocal distribution at inhibitory synapses. Spatial confinement of receptor phosphorylation within the immune synapse may be critical to how activating and inhibitory signals are integrated in NK cells.
Assuntos
Estruturas da Membrana Celular/metabolismo , Junções Intercelulares/imunologia , Células Matadoras Naturais/metabolismo , Receptores Imunológicos/metabolismo , Transdução de Sinais/imunologia , Linhagem Celular , Estruturas da Membrana Celular/ultraestrutura , Transferência Ressonante de Energia de Fluorescência , Humanos , Junções Intercelulares/ultraestrutura , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/imunologia , Fosforilação , Pirimidinas/farmacologia , Agregação de Receptores/imunologia , Receptores Imunológicos/antagonistas & inibidores , Receptores KIR , Receptores KIR2DL1 , Transdução de Sinais/efeitos dos fármacos , Quinases da Família src/antagonistas & inibidores , Quinases da Família src/metabolismoRESUMO
Influenza during pregnancy can affect the health of offspring in later life, among which neurocognitive disorders are among the best described. Here, we investigate whether maternal influenza infection has adverse effects on immune responses in offspring. We establish a two-hit mouse model to study the effect of maternal influenza A virus infection (first hit) on vulnerability of offspring to heterologous infections (second hit) in later life. Offspring born to influenza A virus infected mothers are stunted in growth and more vulnerable to heterologous infections (influenza B virus and MRSA) than those born to PBS- or poly(I:C)-treated mothers. Enhanced vulnerability to infection in neonates is associated with reduced haematopoetic development and immune responses. In particular, alveolar macrophages of offspring exposed to maternal influenza have reduced capacity to clear second hit pathogens. This impaired pathogen clearance is partially reversed by adoptive transfer of alveolar macrophages from healthy offspring born to uninfected dams. These findings suggest that maternal influenza infection may impair immune ontogeny and increase susceptibility to early life infections of offspring.
Assuntos
Infecções Bacterianas/imunologia , Vírus da Influenza A/imunologia , Infecções por Orthomyxoviridae/virologia , Parto , Animais , Animais Recém-Nascidos , Modelos Animais de Doenças , Feminino , Hematopoese , Humanos , Influenza Humana/imunologia , Pulmão/imunologia , Macrófagos Alveolares , Camundongos , Camundongos Endogâmicos C57BL , Mães , Poli I-C , GravidezRESUMO
Infants experiencing severe respiratory syncytial virus (RSV) bronchiolitis have an increased frequency of wheeze and asthma in later childhood. Since most severe RSV infections occur between the 8th and 24th postnatal week, we examined whether age at first infection determines the balance of cytokine production and lung pathology during subsequent rechallenge. Primary RSV infection in newborn mice followed the same viral kinetics as in adults but was associated with reduced and delayed IFN-gamma responses. To study rechallenge, mice were infected at 1 day or 1, 4, or 8 weeks of age and reinfected at 12 weeks. Neonatal priming produced more severe weight loss and increased inflammatory cell recruitment (including T helper 2 cells and eosinophils) during reinfection, whereas delayed priming led to enhanced interferon gamma production and less severe disease during reinfection. These results show the crucial importance of age at first infection in determining the outcome of reinfection and suggest that the environment of the neonatal lung is a major determinant of cytokine production and disease patterns in later life. Thus, simply delaying RSV infection beyond infancy might reduce subsequent respiratory morbidity in later childhood.
Assuntos
Fatores Etários , Infecções por Vírus Respiratório Sincicial/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Animais Recém-Nascidos , Sequência de Bases , Primers do DNA , Camundongos , Camundongos Endogâmicos BALB C , RecidivaRESUMO
We have applied fluorescence imaging of two-photon linear dichroism to measure the subresolution organization of the cell membrane during formation of the activating (cytolytic) natural killer (NK) cell immune synapse (IS). This approach revealed that the NK cell plasma membrane is convoluted into ruffles at the periphery, but not in the center of a mature cytolytic NK cell IS. Time-lapse imaging showed that the membrane ruffles formed at the initial point of contact between NK cells and target cells and then spread radialy across the intercellular contact as the size of the IS increased, becoming absent from the center of the mature synapse. Understanding the role of such extensive membrane ruffling in the assembly of cytolytic synapses is an intriguing new goal.
Assuntos
Membrana Celular/fisiologia , Membrana Celular/ultraestrutura , Sinapses Imunológicas/fisiologia , Sinapses Imunológicas/ultraestrutura , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/ultraestrutura , Algoritmos , Linhagem Celular Transformada , Linhagem Celular Tumoral , Vesículas Citoplasmáticas/fisiologia , Vesículas Citoplasmáticas/ultraestrutura , Fluorescência , Glicosilfosfatidilinositóis/metabolismo , Antígenos HLA-C/metabolismo , Humanos , Microscopia Confocal , Receptores KIR2DL1/metabolismo , SoftwareRESUMO
The lungs are a major site of entry of pathogens into the body and thus require rapid and effective innate responses to prevent pathogens establishing infection and to limit their spread. Additionally, the immune response in the lung must be tightly regulated such that pathogens are cleared, but immunopathology and chronic inflammation are prevented. In this review, I consider the role of natural killer (NK) cells in pulmonary infection and inflammation, specifically their contributions to influenza, tuberculosis, asthma and chronic obstructive pulmonary disease (COPD), which are major causes of morbidity and mortality world-wide. Despite evidence of the importance of NK cells in these diseases, there are still major gaps in our understanding of how their function is regulated in this unique tissue environment. Understanding how different beneficial and detrimental effector functions of NK cells are triggered will be crucial if NK cells are to be exploited therapeutically in respiratory disease.
Assuntos
Células Matadoras Naturais/imunologia , Infecções Respiratórias/imunologia , Asma/imunologia , Humanos , Influenza Humana/imunologia , Pulmão/imunologia , Pneumonia/imunologia , Fibrose Pulmonar/imunologia , Tuberculose Pulmonar/imunologiaRESUMO
Early life is a period of particular susceptibility to respiratory infections and symptoms are frequently more severe in infants than in adults. The neonatal immune system is generally held to be deficient in most compartments; responses to innate stimuli are weak, antigen-presenting cells have poor immunostimulatory activity and adaptive lymphocyte responses are limited, leading to poor immune memory and ineffective vaccine responses. For mucosal surfaces such as the lung, which is continuously exposed to airborne antigen and to potential pathogenic invasion, the ability to discriminate between harmless and potentially dangerous antigens is essential, to prevent inflammation that could lead to loss of gaseous exchange and damage to the developing lung tissue. We have only recently begun to define the differences in respiratory immunity in early life and its environmental and developmental influences. The innate immune system may be of relatively greater importance than the adaptive immune system in the neonatal and infant period than later in life, as it does not require specific antigenic experience. A better understanding of what constitutes protective innate immunity in the respiratory tract in this age group and the factors that influence its development should allow us to predict why certain infants are vulnerable to severe respiratory infections, design treatments to accelerate the development of protective immunity, and design age specific adjuvants to better boost immunity to infection in the lung.
RESUMO
Group B streptococcus and respiratory syncytial virus are leading causes of infant morbidity and mortality worldwide. No licensed vaccines are available for either disease, but vaccines for both are under development. Severe respiratory syncytial virus disease can be prevented by passively administered antibody. The presence of maternal IgG antibody specific to respiratory syncytial virus is associated with reduced prevalence and severity of respiratory syncytial virus disease in the first few weeks of life, whereas maternal serotype-specific anticapsular antibody is associated with protection against both early-onset and late-onset group B streptococcus disease. Therefore, vaccination in pregnancy might protect infants against both diseases. This report describes what is known about immune protection against group B streptococcus and respiratory syncytial virus, identifies knowledge gaps regarding the immunobiology of both diseases, and aims to prioritise research directions in maternal immunisation.
Assuntos
Imunidade Materno-Adquirida , Imunização/métodos , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Vacinas contra Vírus Sincicial Respiratório/administração & dosagem , Infecções Estreptocócicas/prevenção & controle , Vacinas Estreptocócicas/administração & dosagem , Feminino , Humanos , Imunização/estatística & dados numéricos , Lactente , Gravidez , Infecções por Vírus Respiratório Sincicial/imunologia , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Vírus Sincicial Respiratório Humano/imunologia , Infecções Estreptocócicas/microbiologia , Streptococcus agalactiae/isolamento & purificação , VacinaçãoRESUMO
We investigated the roles of the regulatory molecules glucocorticoid-induced TNF receptor family-related protein (GITR) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) in murine infection with the nematode parasite Trichinella spiralis. Expression of GITR and CTLA-4 was rapidly upregulated on cells in the mesenteric lymph nodes and spleen, with approximately 80% of CD4+ lymphocytes expressing GITR by day 7 post-infection, coinciding with release and dissemination of newborn larvae. As the infection progressed to the chronic muscle phase, expression of GITR returned to normal, whereas CTLA-4 was sustained as late as day 60. Mice treated with anti-GITR antibodies rapidly developed higher titres of parasite-specific IgG1, IgG2a, IgG2b and IgM than controls. This was accompanied by elevated background lymphocyte proliferation, but parasite establishment in the intestine or the muscle was unaffected. In contrast, treatment with anti-CTLA-4 antibody resulted in elevated serum IgE, enhanced production of interleukin-4 and interleukin-10, and lower numbers of parasites recovered from skeletal muscle. These results reveal different temporal and regulatory roles for CTLA-4 and GITR in immune responses to helminth infection.
Assuntos
Antígenos CD/imunologia , Antígenos de Diferenciação/imunologia , Receptores de Fator de Crescimento Neural/imunologia , Receptores do Fator de Necrose Tumoral/imunologia , Trichinella spiralis/imunologia , Triquinelose/imunologia , Animais , Anticorpos Anti-Helmínticos/sangue , Antígenos CD/biossíntese , Antígenos de Diferenciação/biossíntese , Linfócitos T CD4-Positivos/imunologia , Antígeno CTLA-4 , Proliferação de Células , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Feminino , Citometria de Fluxo , Proteína Relacionada a TNFR Induzida por Glucocorticoide , Imunoglobulina E/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Interleucina-10 , Interleucina-4/análise , Intestinos/parasitologia , Linfonodos/imunologia , Subpopulações de Linfócitos/imunologia , Camundongos , Músculo Esquelético/parasitologia , Receptores de Fator de Crescimento Neural/biossíntese , Receptores do Fator de Necrose Tumoral/biossíntese , Baço/imunologia , Regulação para CimaRESUMO
Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections. Immunity to RSV is initiated upon detection of the virus by pattern recognition receptors, such as RIG-I-like receptors. RIG-I-like receptors signal via MAVS to induce the synthesis of proinflammatory mediators, including type I interferons (IFNs), which trigger and shape antiviral responses and protect cells from infection. Alveolar macrophages (AMs) are amongst the first cells to encounter invading viruses and the ones producing type I IFNs. However, it is unclear whether IFNs act to prevent AMs from serving as vehicles for viral replication. In this study, primary AMs from MAVS (Mavs-/-)- or type I IFN receptor (Ifnar1-/-)-deficient mice were exposed to RSV ex vivo. Wild-type (wt) AMs but not Mavs-/- and Ifnar1-/- AMs produced inflammatory mediators in response to RSV. Furthermore, Mavs-/- and Ifnar1-/- AMs accumulated more RSV proteins than wt AMs, but the infection was abortive. Thus, RIG-I-like receptor-MAVS and IFNAR signalling are important for the induction of proinflammatory mediators from AMs upon RSV infection, but this signalling is not central for controlling viral replication. The ability to restrict viral replication makes AMs ideal sensors of RSV infection and important initiators of immune responses in the lung.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Macrófagos Alveolares/imunologia , Receptor de Interferon alfa e beta/metabolismo , Infecções por Vírus Respiratório Sincicial/imunologia , Vírus Sinciciais Respiratórios/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Células Cultivadas , Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , Interferon Tipo I/metabolismo , Macrófagos Alveolares/virologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor de Interferon alfa e beta/genética , Transdução de Sinais , Replicação ViralRESUMO
The study investigated the role of P-selectin in the responses of eosinophil transmigration and eotaxin generation in vivo elicited by interleukin (IL)-13, as compared with IL-4. Two murine models of leukocyte transmigration were used, migration into cytokine-stimulated peritoneal cavities and through stimulated cremasteric venules, as observed by intravital microscopy. In mice lacking P-selectin, eosinophil infiltration elicited by the cytokines in the peritonitis model was totally inhibited. In the cremaster muscle, however, although spontaneous leukocyte-rolling flux and stimulated leukocyte firm adhesion were inhibited by approximately 97% and approximately 48%, respectively, stimulated transmigration was unaffected. However, IL-13-induced leukocyte transmigration was totally blocked in P-selectin-deficient mice treated with an anti-alpha(4) integrin monoclonal antibody (mAb; PS/2). In comparison, treatment of wild-type mice with the anti-alpha(4) integrin mAb resulted in only partial suppression of IL-13-induced leukocyte transmigration. Significant levels of eotaxin were detected in response to IL-13/IL-4 in both tissues in P-selectin-deficient animals. In conclusion, the regulatory role of P-selectin in leukocyte transmigration elicited by IL-13 appears to be tissue-specific, a phenomenon that is independent of the ability of the cytokine to stimulate eotaxin generation.
Assuntos
Quimiocinas CC/biossíntese , Quimiotaxia de Leucócito , Eosinófilos/citologia , Interleucina-13/fisiologia , Selectina-P/fisiologia , Animais , Quimiocina CCL11 , Integrina alfa4/fisiologia , Interleucina-4/fisiologia , Migração e Rolagem de Leucócitos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia de Vídeo , Músculo Esquelético/irrigação sanguínea , Selectina-P/genética , Cavidade Peritoneal/citologia , Vênulas/citologiaRESUMO
Type I interferons (IFNs) are important for host defense from viral infections, acting to restrict viral production in infected cells and to promote antiviral immune responses. However, the type I IFN system has also been associated with severe lung inflammatory disease in response to respiratory syncytial virus (RSV). Which cells produce type I IFNs upon RSV infection and how this directs immune responses to the virus, and potentially results in pathological inflammation, is unclear. Here, we show that alveolar macrophages (AMs) are the major source of type I IFNs upon RSV infection in mice. AMs detect RSV via mitochondrial antiviral signaling protein (MAVS)-coupled retinoic acid-inducible gene 1 (RIG-I)-like receptors (RLRs), and loss of MAVS greatly compromises innate immune restriction of RSV. This is largely attributable to loss of type I IFN-dependent induction of monocyte chemoattractants and subsequent reduced recruitment of inflammatory monocytes (infMo) to the lungs. Notably, the latter have potent antiviral activity and are essential to control infection and lessen disease severity. Thus, infMo recruitment constitutes an important and hitherto underappreciated, cell-extrinsic mechanism of type I IFN-mediated antiviral activity. Dysregulation of this system of host antiviral defense may underlie the development of RSV-induced severe lung inflammation.