RESUMO
Activated macrophages undergo metabolic reprogramming, which drives their pro-inflammatory phenotype, but the mechanistic basis for this remains obscure. Here, we demonstrate that upon lipopolysaccharide (LPS) stimulation, macrophages shift from producing ATP by oxidative phosphorylation to glycolysis while also increasing succinate levels. We show that increased mitochondrial oxidation of succinate via succinate dehydrogenase (SDH) and an elevation of mitochondrial membrane potential combine to drive mitochondrial reactive oxygen species (ROS) production. RNA sequencing reveals that this combination induces a pro-inflammatory gene expression profile, while an inhibitor of succinate oxidation, dimethyl malonate (DMM), promotes an anti-inflammatory outcome. Blocking ROS production with rotenone by uncoupling mitochondria or by expressing the alternative oxidase (AOX) inhibits this inflammatory phenotype, with AOX protecting mice from LPS lethality. The metabolic alterations that occur upon activation of macrophages therefore repurpose mitochondria from ATP synthesis to ROS production in order to promote a pro-inflammatory state.
Assuntos
Inflamação/imunologia , Ativação de Macrófagos , Macrófagos/imunologia , Mitocôndrias/enzimologia , Succinato Desidrogenase/metabolismo , Ácido Succínico/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Ciclo do Ácido Cítrico , Glicólise , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Inflamação/genética , Interleucina-10/metabolismo , Lipopolissacarídeos/imunologia , Macrófagos/metabolismo , Malonatos/farmacologia , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Proteínas Mitocondriais/metabolismo , Oxirredução/efeitos dos fármacos , Fosforilação Oxidativa/efeitos dos fármacos , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Análise de Sequência de RNA , Succinato Desidrogenase/genética , TranscriptomaRESUMO
Inflammation observed in SARS-CoV-2-infected patients suggests that inflammasomes, proinflammatory intracellular complexes, regulate various steps of infection. Lung epithelial cells express inflammasome-forming sensors and constitute the primary entry door of SARS-CoV-2. Here, we describe that the NLRP1 inflammasome detects SARS-CoV-2 infection in human lung epithelial cells. Specifically, human NLRP1 is cleaved at the Q333 site by multiple coronavirus 3CL proteases, which triggers inflammasome assembly and cell death and limits the production of infectious viral particles. Analysis of NLRP1-associated pathways unveils that 3CL proteases also inactivate the pyroptosis executioner Gasdermin D (GSDMD). Subsequently, caspase-3 and GSDME promote alternative cell pyroptosis. Finally, analysis of pyroptosis markers in plasma from COVID-19 patients with characterized severe pneumonia due to autoantibodies against, or inborn errors of, type I interferons (IFNs) highlights GSDME/caspase-3 as potential markers of disease severity. Overall, our findings identify NLRP1 as a sensor of SARS-CoV-2 infection in lung epithelia.
Assuntos
COVID-19 , Proteases 3C de Coronavírus , Células Epiteliais , Inflamassomos , Proteínas NLR , SARS-CoV-2 , COVID-19/genética , COVID-19/metabolismo , COVID-19/virologia , Caspase 3/metabolismo , Proteases 3C de Coronavírus/genética , Proteases 3C de Coronavírus/metabolismo , Células Epiteliais/metabolismo , Humanos , Inflamassomos/genética , Inflamassomos/metabolismo , Pulmão/metabolismo , Pulmão/virologia , Proteínas NLR/genética , Proteínas NLR/metabolismo , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Proteínas de Ligação a Fosfato/genética , Proteínas de Ligação a Fosfato/metabolismo , Proteínas Citotóxicas Formadoras de Poros/genética , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Piroptose , SARS-CoV-2/enzimologia , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , SARS-CoV-2/patogenicidadeRESUMO
Programmed cell death contributes to host defense against pathogens. To investigate the relative importance of pyroptosis, necroptosis, and apoptosis during Salmonella infection, we infected mice and macrophages deficient for diverse combinations of caspases-1, -11, -12, and -8 and receptor interacting serine/threonine kinase 3 (RIPK3). Loss of pyroptosis, caspase-8-driven apoptosis, or necroptosis had minor impact on Salmonella control. However, combined deficiency of these cell death pathways caused loss of bacterial control in mice and their macrophages, demonstrating that host defense can employ varying components of several cell death pathways to limit intracellular infections. This flexible use of distinct cell death pathways involved extensive cross-talk between initiators and effectors of pyroptosis and apoptosis, where initiator caspases-1 and -8 also functioned as executioners when all known effectors of cell death were absent. These findings uncover a highly coordinated and flexible cell death system with in-built fail-safe processes that protect the host from intracellular infections.
Assuntos
Apoptose/imunologia , Macrófagos/imunologia , Necroptose/imunologia , Piroptose/imunologia , Infecções por Salmonella/imunologia , Salmonella/imunologia , Animais , Caspase 1/deficiência , Caspase 1/genética , Caspase 12/deficiência , Caspase 12/genética , Caspase 8/genética , Caspases Iniciadoras/deficiência , Caspases Iniciadoras/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Proteína Serina-Treonina Quinases de Interação com Receptores/genéticaRESUMO
Inflammatory bowel disease is a chronic, relapsing condition with two subtypes, Crohn's disease (CD) and ulcerative colitis (UC). Genome-wide association studies (GWASs) in UC implicate a FCGR2A variant that alters the binding affinity of the antibody receptor it encodes, FcγRIIA, for immunoglobulin G (IgG). Here, we aimed to understand the mechanisms whereby changes in FcγRIIA affinity would affect inflammation in an IgA-dominated organ. We found a profound induction of anti-commensal IgG and a concomitant increase in activating FcγR signaling in the colonic mucosa of UC patients. Commensal-IgG immune complexes engaged gut-resident FcγR-expressing macrophages, inducing NLRP3- and reactive-oxygen-species-dependent production of interleukin-1ß (IL-1ß) and neutrophil-recruiting chemokines. These responses were modulated by the FCGR2A genotype. In vivo manipulation of macrophage FcγR signal strength in a mouse model of UC determined the magnitude of intestinal inflammation and IL-1ß-dependent type 17 immunity. The identification of an important contribution of IgG-FcγR-dependent inflammation to UC has therapeutic implications.
Assuntos
Anticorpos Antibacterianos/imunologia , Colite Ulcerativa/imunologia , Microbioma Gastrointestinal/imunologia , Imunoglobulina G/imunologia , Interleucina-1beta/imunologia , Células Th17/imunologia , Animais , Colite/induzido quimicamente , Colite/imunologia , Colite/microbiologia , Colite/patologia , Colite Ulcerativa/microbiologia , Colite Ulcerativa/patologia , Sulfato de Dextrana/toxicidade , Regulação da Expressão Gênica , Genótipo , Humanos , Inflamação , Interleucina-8/biossíntese , Interleucina-8/genética , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Macrófagos/imunologia , Camundongos , Fagócitos/imunologia , RNA Mensageiro/biossíntese , Espécies Reativas de Oxigênio , Receptores de IgG/biossíntese , Receptores de IgG/genética , Receptores de IgG/imunologiaRESUMO
Mechano-immunity, the intersection between cellular or tissue mechanics and immune cell function, is emerging as an important factor in many inflammatory diseases. Mechano-sensing defines how cells detect mechanical changes in their environment. Mechano-response defines how cells adapt to such changes, e.g. form synapses, signal or migrate. Inflammasomes are intracellular immune sensors that detect changes in tissue and cell homoeostasis during infection or injury. We and others recently found that mechano-sensing of tissue topology (swollen tissue), topography (presence and distribution of foreign solid implant) or biomechanics (stiffness), alters inflammasome activity. Once activated, inflammasomes induce the secretion of inflammatory cytokines, but also change cellular mechanical properties, which influence how cells move, change their shape, and interact with other cells. When overactive, inflammasomes lead to chronic inflammation. This clearly places inflammasomes as important players in mechano-immunity. Here, we discuss a model whereby inflammasomes integrate pathogen- and tissue-injury signals, with changes in tissue mechanics, to shape the downstream inflammatory responses and allow cell and tissue mechano-adaptation. We will review the emerging evidence that supports this model.
Assuntos
Citocinas , Inflamassomos , Humanos , InflamaçãoRESUMO
SignificanceImplantable electronic medical devices (IEMDs) are used for some clinical applications, representing an exciting prospect for the transformative treatment of intractable conditions such Parkinson's disease, deafness, and paralysis. The use of IEMDs is limited at the moment because, over time, a foreign body reaction (FBR) develops at the device-neural interface such that ultimately the IEMD fails and needs to be removed. Here, we show that macrophage nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activity drives the FBR in a nerve injury model yet integration of an NLRP3 inhibitor into the device prevents FBR while allowing full healing of damaged neural tissue to occur.
Assuntos
Corpos Estranhos , Inflamassomos , Humanos , Macrófagos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Próteses e ImplantesRESUMO
The alarm cytokine interleukin-1ß (IL-1ß) is a potent activator of the inflammatory cascade following pathogen recognition. IL-1ß production typically requires two signals: first, priming by recognition of pathogen-associated molecular patterns leads to the production of immature pro-IL-1ß; subsequently, inflammasome activation by a secondary signal allows cleavage and maturation of IL-1ß from its pro-form. However, despite the important role of IL-1ß in controlling local and systemic inflammation, its overall regulation is still not fully understood. Here we demonstrate that peritoneal tissue-resident macrophages use an active inhibitory pathway, to suppress IL-1ß processing, which can otherwise occur in the absence of a second signal. Programming by the transcription factor Gata6 controls the expression of prostacyclin synthase, which is required for prostacyclin production after lipopolysaccharide stimulation and optimal induction of IL-10. In the absence of secondary signal, IL-10 potently inhibits IL-1ß processing, providing a previously unrecognized control of IL-1ß in tissue-resident macrophages.
Assuntos
Epoprostenol/imunologia , Interleucina-10/imunologia , Interleucina-1beta/imunologia , Macrófagos Peritoneais/imunologia , Animais , Epoprostenol/genética , Fator de Transcrição GATA6/genética , Fator de Transcrição GATA6/imunologia , Inflamação/genética , Inflamação/imunologia , Inflamação/patologia , Interleucina-10/genética , Interleucina-1beta/genética , Macrófagos Peritoneais/patologia , Camundongos , Camundongos TransgênicosRESUMO
The specific biology of the male breast remains relatively unexplored in spite of the increasing global prevalence of male breast cancer. Delineation of the microenvironment of the male breast is restricted by the low availability of human samples and a lack of characterisation of appropriate animal models. Unlike the mouse, the male ovine gland persists postnatally. We suggest that the male ovine mammary gland constitutes a promising adjunctive model for the male breast. In this study, we evaluate the male ovine mammary gland microenvironment, comparing intact and neutered males. Assessment of the glandular histo-anatomy highlights the resemblance of the male gland to that of neonatal female sheep and confirms the presence of rudimentary terminal duct lobular units. Irrespective of neutered status, cell proliferation in epithelial and stromal compartments is similarly low in males, and cell proliferation in epithelial cells and in the intralobular stroma is significantly lower than in pubertal female sheep. Between 42% and 72% of the luminal mammary epithelial cells in the male gland express the androgen receptor and expression is significantly reduced by neutering. Luminal epithelial cells within the intact and neutered male gland also express oestrogen receptor alpha, but minimal progesterone receptor expression is observed. The distribution of leukocytes within the ducts and stroma is similar to the mammary gland of female sheep and females of other species. Both macrophages and T lymphocytes are intercalated in the epithelial bilayer and are more abundant in the intralobular stroma than the interlobular stroma, suggesting that they may have a protective immunological function within the vestigial glandular tissue of the male sheep. Mast cells are also observed within the stroma. These cells cluster near the glandular tissue and are frequently located adjacent to blood vessels. The abundance of mast cells is significantly higher in intact males compared to neutered males, suggesting that hormone signalling may impact mast cell recruitment. In this study, we demonstrate the utility of the male ovine mammary gland as a model for furthering our knowledge of postnatal male mammary biology.
Assuntos
Glândulas Mamárias Animais , Animais , Masculino , Glândulas Mamárias Animais/anatomia & histologia , Glândulas Mamárias Animais/metabolismo , Ovinos , Modelos Animais , Feminino , Proliferação de Células/fisiologia , Células Epiteliais/metabolismoRESUMO
Inflammation driven by the NLRP3 inflammasome in macrophages is an important contributor to chronic metabolic diseases that affect growing numbers of individuals. Many of these diseases involve the pathologic accumulation of endogenous lipids or their oxidation products, which can activate NLRP3. Other endogenous lipids, however, can inhibit the activation of NLRP3. The intracellular mechanisms by which these lipids modulate NLRP3 activity are now being identified. This review discusses emerging evidence suggesting that organelle stress, particularly involving mitochondria, lysosomes, and the endoplasmic reticulum, may be key in lipid-induced modification of NLRP3 inflammasome activity.
Assuntos
Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Estresse do Retículo Endoplasmático , Humanos , Lipídeos , MitocôndriasRESUMO
Infection of human macrophages with Salmonella enterica serovar Typhimurium (S. Typhimurium) leads to inflammasome activation. Inflammasomes are multiprotein complexes facilitating caspase-1 activation and subsequent gasdermin D-mediated cell death and IL-1ß and IL-18 cytokine release. The NAIP/NLRC4 inflammasome is activated by multiple bacterial protein ligands, including flagellin from the flagellum and the needle protein PrgI from the S. Typhimurium type III secretion system. In this study, we show that transfected ultrapure flagellin from S Typhimurium induced cell death and cytokine secretion in THP-1 cells and primary human monocyte-derived macrophages. In THP-1 cells, NAIP/NLRC4 and NLRP3 played redundant roles in inflammasome activation during infection with S. Typhimurium. Knockout of NAIP or NLRC4 in THP-1 cells revealed that flagellin, but not PrgI, now activated the NLRP3 inflammasome through a reactive oxygen species- and/or cathepsin-dependent mechanism that was independent of caspase-4/5 activity. In conclusion, our data suggest that NLRP3 can be activated by flagellin to act as a "safety net" to maintain inflammasome activation under conditions of suboptimal NAIP/NLRC4 activation, as observed in THP-1 cells, possibly explaining the redundant role of NLRP3 and NAIP/NLRC4 during S. Typhimurium infection.
Assuntos
Proteínas Adaptadoras de Sinalização CARD/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Inflamassomos/metabolismo , Macrófagos/imunologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteína Inibidora de Apoptose Neuronal/metabolismo , Salmonella typhi/fisiologia , Febre Tifoide/imunologia , Apoptose , Proteínas Adaptadoras de Sinalização CARD/genética , Proteínas de Ligação ao Cálcio/genética , Caspases Iniciadoras/metabolismo , Flagelina , Humanos , Proteína Inibidora de Apoptose Neuronal/genética , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Células THP-1 , Sistemas de Secreção Tipo III/metabolismoRESUMO
The mammalian innate immune system deals with invading pathogens and stress by activating pattern-recognition receptors (PRRs) in the host. Initially proposed to be triggered by the discrimination of defined molecular signatures from pathogens rather than from self, it is now clear that PRRs can also be activated by endogenous ligands, bacterial metabolites and, following pathogen-induced alterations of cellular processes, changes in the F-actin cytoskeleton. These processes are collectively referred to as effector-triggered immunity (ETI). Here, we summarize the molecular and conceptual advances in our understanding of cell autonomous innate immune responses against bacterial pathogens, and discuss how classical activation of PRRs and ETI interplay to drive inflammatory responses.
Assuntos
Bactérias/imunologia , Imunidade Inata/imunologia , Inflamação/imunologia , Receptores de Reconhecimento de Padrão/imunologia , Animais , Humanos , Inflamação/patologiaRESUMO
Leucine-rich repeat kinase 2 (LRRK2) encodes a complex protein that includes kinase and GTPase domains. Genome-wide association studies have identified dominant LRRK2 alleles that predispose their carriers to late-onset idiotypic Parkinson's disease (PD) and also to autoimmune disorders such as Crohn's disease. Considerable evidence indicates that PD initiation and progression involve activation of innate immune functions in microglia, which are brain-resident macrophages. Here we asked whether LRRK2 modifies inflammatory signaling and how this modification might contribute to PD and Crohn's disease. We used RNA-Seq-based high-resolution transcriptomics to compare gene expression in activated primary macrophages derived from WT and Lrrk2 knockout mice. Remarkably, expression of a single gene, Rap guanine nucleotide exchange factor 3 (Rapgef3), was strongly up-regulated in the absence of LRRK2 and down-regulated in its presence. We observed similar regulation of Rapgef3 expression in cells treated with a highly specific inhibitor of LRRK2 protein kinase activity. Rapgef3 encodes an exchange protein, activated by cAMP 1 (EPAC-1), a guanine nucleotide exchange factor that activates the small GTPase Rap-1. Rap-1 mediates cell adhesion, polarization, and directional motility, and our results indicate that LRRK2 modulates chemotaxis of microglia and macrophages. Dominant PD-associated LRRK2 alleles may suppress EPAC-1 activity, further restricting motility and preventing efficient migration of microglia to sites of neuronal damage. Functional analysis in vivo in a subclinical infection model also indicated that Lrrk2 subtly modifies the inflammatory response. These results indicate that LRRK2 modulates the expression of genes involved in murine immune cell chemotaxis.
Assuntos
Adesão Celular , Polaridade Celular , Quimiotaxia , Regulação da Expressão Gênica , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Ativação de Macrófagos , Macrófagos/enzimologia , Animais , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Camundongos , Camundongos Knockout , Microglia/enzimologia , Proteínas rap1 de Ligação ao GTP/genética , Proteínas rap1 de Ligação ao GTP/metabolismoRESUMO
In the published article, the Fig. 2 was published incorrectly. The correct Fig. 2 is given below.
RESUMO
Cardiolipins (CLs) are tetra-acylated diphosphatidylglycerols found in bacteria, yeast, plants, and animals. In healthy mammals, CLs are unsaturated, whereas saturated CLs are found in blood cells from Barth syndrome patients and in some Gram-positive bacteria. Here, we show that unsaturated but not saturated CLs block LPS-induced NF-κB activation, TNF-α and IP-10 secretion in human and murine macrophages, as well as LPS-induced TNF-α and IL-1ß release in human blood mononuclear cells. Using HEK293 cells transfected with Toll-like receptor 4 (TLR4) and its co-receptor Myeloid Differentiation 2 (MD2), we demonstrate that unsaturated CLs compete with LPS for binding TLR4/MD2 preventing its activation, whereas saturated CLs are TLR4/MD2 agonists. As a consequence, saturated CLs induce a pro-inflammatory response in macrophages characterized by TNF-α and IP-10 secretion, and activate the alternative NLRP3 inflammasome pathway in human blood-derived monocytes. Thus, we identify that double bonds discriminate between anti- and pro-inflammatory properties of tetra-acylated molecules, providing a rationale for the development of TLR4 activators and inhibitors for use as vaccine adjuvants or in the treatment of TLR4-related diseases.
Assuntos
Cardiolipinas/farmacologia , Macrófagos/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo , Animais , Anti-Infecciosos/química , Anti-Infecciosos/metabolismo , Anti-Infecciosos/farmacologia , Ligação Competitiva , Cardiolipinas/química , Cardiolipinas/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Quimiocina CXCL10/metabolismo , Células HEK293 , Humanos , Receptores de Lipopolissacarídeos/metabolismo , Lipopolissacarídeos/metabolismo , Lipopolissacarídeos/farmacologia , Antígeno 96 de Linfócito/genética , Antígeno 96 de Linfócito/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Camundongos , Monócitos/citologia , Monócitos/metabolismo , NF-kappa B/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Ligação Proteica , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/agonistas , Receptor 4 Toll-Like/antagonistas & inibidores , Receptor 4 Toll-Like/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Analysis of oxylipins by liquid chromatography mass spectrometry (LC/MS) is challenging because of the small mass range occupied by this diverse lipid class, the presence of numerous structural isomers, and their low abundance in biological samples. Although highly sensitive LC/MS/MS methods are commonly used, further separation is achievable by using drift tube ion mobility coupled with high-resolution mass spectrometry (DTIM-MS). Herein, we present a combined analytical and computational method for the identification of oxylipins and fatty acids. We use a reversed-phase LC/DTIM-MS workflow able to profile and quantify (based on chromatographic peak area) the oxylipin and fatty acid content of biological samples while simultaneously acquiring full scan and product ion spectra. The information regarding accurate mass, collision-cross-section values in nitrogen (DTCCSN2), and retention times of the species found are compared to an internal library of lipid standards as well as the LIPID MAPS Structure Database by using specifically developed processing tools. Features detected within the DTCCSN2 and m/ z ranges of the analyzed standards are flagged as oxylipin-like species, which can be further characterized using drift-time alignment of product and precursor ions distinctive of DTIM-MS. This not only helps identification by reducing the number of annotations from LIPID MAPS but also guides discovery studies of potentially novel species. Testing the methodology on Salmonella enterica serovar Typhimurium-infected murine bone-marrow-derived macrophages and thrombin activated human platelets yields results in agreement with literature. This workflow has also annotated features as potentially novel oxylipins, confirming its ability in providing further insights into lipid analysis of biological samples.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Eicosanoides/análise , Ácidos Graxos/análise , Oxilipinas/análise , Espectrometria de Massas em Tandem/métodos , Animais , Células Cultivadas , Humanos , Espectrometria de Mobilidade Iônica/métodos , Camundongos Endogâmicos C57BLRESUMO
Caspase-8 is an apical component of cell death pathways. Activated caspase-8 can drive classical caspase-dependent apoptosis and actively inhibits cell death mediated by RIPK3-driven necroptosis. Genetic deletion of Casp8 results in embryonic lethality as a result of uncontrolled necroptosis. This lethality can be rescued by simultaneous deletion of Ripk3. Recently, caspase-8 has been additionally connected to inflammatory pathways within the cell. In particular, caspase-8 has been shown to be crucially involved in the induction of pro-IL-1ß synthesis and processing via both non-canonical and canonical pathways. In this review, we bring together current knowledge regarding the role of caspase-8 in cellular inflammation with a particular emphasis on the interplay between caspase-8 and the classical and non-canonical inflammasomes.
Assuntos
Caspase 8/metabolismo , Inflamassomos/metabolismo , Inflamação/metabolismo , Interleucina-1beta/metabolismo , Animais , Caspase 8/genética , Morte Celular , Humanos , Inflamassomos/imunologia , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Transdução de SinaisRESUMO
Biofilm formation on abiotic surfaces in the food and medical industry can cause severe contamination and infection, yet how biological and physical factors determine the cellular architecture of early biofilms and the bacterial behavior of the constituent cells remains largely unknown. In this study, we examined the specific role of type I fimbriae in nascent stages of biofilm formation and the response of microcolonies to environmental flow shear at the single-cell resolution. The results show that type I fimbriae are not required for reversible adhesion from plankton, but they are critical for the irreversible adhesion of Escherichia coli strain MG1655 cells that form biofilms on polyethylene terephthalate (PET) surfaces. Besides establishing firm cell surface contact, the irreversible adhesion seems necessary to initiate the proliferation of E. coli on the surface. After the application of shear stress, bacterial retention is dominated by the three-dimensional architecture of colonies, independent of the population size, and the multilayered structure could protect the embedded cells from being insulted by fluid shear, while the cell membrane permeability mainly depends on the biofilm population size and the duration of the shear stress.IMPORTANCE Bacterial biofilms could lead to severe contamination problems in medical devices and food processing equipment. However, biofilms are usually studied at a rough macroscopic level; thus, little is known about how individual bacterium behavior within biofilms and the multicellular architecture are influenced by bacterial appendages (e.g., pili/fimbriae) and environmental factors during early biofilm formation. We applied confocal laser scanning microscopy (CLSM) to visualize Escherichia coli microcolonies at a single-cell resolution. Our findings suggest that type I fimbriae are vital to the initiation of bacterial proliferation on surfaces. We also found that the fluid shear stress affects the biofilm architecture and cell membrane permeability of the constituent bacteria in a different way: the onset of the biofilm is linked with the three-dimensional morphology, while membranes are regulated by the overall population of microcolonies.
Assuntos
Biofilmes/crescimento & desenvolvimento , Escherichia coli/isolamento & purificação , Fímbrias Bacterianas/metabolismo , Estresse Fisiológico , Aderência Bacteriana , Equipamentos e Provisões/microbiologia , Escherichia coli/crescimento & desenvolvimento , Microscopia Confocal , Polietilenotereftalatos/química , Propriedades de SuperfícieRESUMO
Candida spp. elicit cytokine production downstream of various pathogen recognition receptors, including C-type lectin-like receptors, TLRs, and nucleotide oligomerization domain (NOD)-like receptors. IL-12 family members IL-12p70 and IL-23 are important for host immunity against Candida spp. In this article, we show that IL-27, another IL-12 family member, is produced by myeloid cells in response to selected Candida spp. We demonstrate a novel mechanism for Candida parapsilosis-mediated induction of IL-27 in a TLR7-, MyD88-, and NOD2-dependent manner. Our data revealed that IFN-ß is induced by C. parapsilosis, which in turn signals through the IFN-α/ß receptor and STAT1/2 to induce IL-27. Moreover, IL-27R (WSX-1)-deficient mice systemically infected with C. parapsilosis displayed enhanced pathogen clearance compared with wild-type mice. This was associated with increased levels of proinflammatory cytokines in the serum and increased IFN-γ and IL-17 responses in the spleens of IL-27R-deficient mice. Thus, our data define a novel link between C. parapsilosis, TLR7, NOD2, IFN-ß, and IL-27, and we have identified an important role for IL-27 in the immune response against C. parapsilosis Overall, these findings demonstrate an important mechanism for the suppression of protective immune responses during infection with C. parapsilosis, which has potential relevance for infections with other fungal pathogens.
Assuntos
Candida/fisiologia , Candidíase/imunologia , Interleucina-27/metabolismo , Células Mieloides/imunologia , Receptor 7 Toll-Like/metabolismo , Animais , Células Cultivadas , Citocinas/metabolismo , Evasão da Resposta Imune , Mediadores da Inflamação/metabolismo , Interferon beta/metabolismo , Interleucina-27/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Adaptadora de Sinalização NOD2/genética , Proteína Adaptadora de Sinalização NOD2/metabolismo , Receptores de Citocinas/genética , Receptores de Interleucina , Transdução de SinaisRESUMO
BACKGROUND: The aggregation of the protein É-synuclein (ÉS) underlies a range of increasingly common neurodegenerative disorders including Parkinson's disease. One widely explored therapeutic strategy for these conditions is the use of antibodies to target aggregated ÉS, although a detailed molecular-level mechanism of the action of such species remains elusive. Here, we characterize ÉS aggregation in vitro in the presence of two ÉS-specific single-domain antibodies (nanobodies), NbSyn2 and NbSyn87, which bind to the highly accessible C-terminal region of ÉS. RESULTS: We show that both nanobodies inhibit the formation of ÉS fibrils. Furthermore, using single-molecule fluorescence techniques, we demonstrate that nanobody binding promotes a rapid conformational conversion from more stable oligomers to less stable oligomers of ÉS, leading to a dramatic reduction in oligomer-induced cellular toxicity. CONCLUSIONS: The results indicate a novel mechanism by which diseases associated with protein aggregation can be inhibited, and suggest that NbSyn2 and NbSyn87 could have significant therapeutic potential.