RESUMO
Plasmacytoid dendritic cells (pDCs) specialize in the production of type I IFN (IFN-I). pDCs can be depleted in vivo by injecting diphtheria toxin (DT) in a mouse in which pDCs express a diphtheria toxin receptor (DTR) transgene driven by the human CLEC4C promoter. This promoter is enriched for binding sites for TCF4, a transcription factor that promotes pDC differentiation and expression of pDC markers, including CLEC4C. Here, we found that injection of DT in CLEC4C-DTR+ mice markedly augmented Th2-dependent skin inflammation in a model of contact hypersensitivity (CHS) induced by the hapten fluorescein isothiocyanate. Unexpectedly, this biased Th2 response was independent of reduced IFN-I accompanying pDC depletion. In fact, DT treatment altered the representation of conventional dendritic cells (cDCs) in the skin-draining lymph nodes during the sensitization phase of CHS; there were fewer Th1-priming CD326+ CD103+ cDC1 and more Th2-priming CD11b+ cDC2. Single-cell RNA-sequencing of CLEC4C-DTR+ cDCs revealed that CD326+ DCs, like pDCs, expressed DTR and were depleted together with pDCs by DT treatment. Since CD326+ DCs did not express Tcf4, DTR expression might be driven by yet-undefined transcription factors activating the CLEC4C promoter. These results demonstrate that altered DC representation in the skin-draining lymph nodes during sensitization to allergens can cause Th2-driven CHS.
Assuntos
Células Dendríticas/imunologia , Dermatite de Contato/imunologia , Interferon Tipo I/genética , Lectinas Tipo C/genética , Receptores Imunológicos/genética , Pele/imunologia , Animais , Antígenos CD/genética , Antígenos CD/imunologia , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Dermatite de Contato/genética , Dermatite de Contato/patologia , Toxina Diftérica/genética , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/genética , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/imunologia , Humanos , Cadeias alfa de Integrinas/genética , Cadeias alfa de Integrinas/imunologia , Linfonodos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Regiões Promotoras Genéticas/genética , Células Th2/imunologia , Fator de Transcrição 4/genética , Fator de Transcrição 4/imunologiaRESUMO
Plasmacytoid dendritic cells (pDCs) produce abundant type I IFNs (IFN-I) in response to viral nucleic acids. Generation of pDCs from bone marrow dendritic cell (DC) progenitors and their maintenance is driven by the transcription factor E2-2 and inhibited by its repressor Id2. In this study, we find that mouse pDCs selectively express the receptor for LIF that signals through STAT3. Stimulation of pDCs with LIF inhibited IFN-I, TNF, and IL-6 responses to CpG and induced expression of the STAT3 targets SOCS3 and Bcl3, which inhibit IFN-I and NF-κB signaling. Moreover, although STAT3 has been also reported to induce E2-2, LIF paradoxically induced its repressor Id2. A late-stage bone marrow DC progenitor expressed low amounts of LIFR and developed into pDCs less efficiently after being exposed to LIF, consistent with the induction of Id2. Conversely, pDC development and serum IFN-I responses to lymphocytic choriomeningitis virus infection were augmented in newly generated mice lacking LIFR in either CD11c+ or hematopoietic cells. Thus, an LIF-driven STAT3 pathway induces SOCS3, Bcl3, and Id2, which render pDCs and late DC progenitors refractory to physiological stimuli controlling pDC functions and development. This pathway can be potentially exploited to prevent inappropriate secretion of IFN-I in autoimmune diseases or promote IFN-I secretion during viral infections.
Assuntos
Células Dendríticas/citologia , Células Dendríticas/imunologia , Fator Inibidor de Leucemia/metabolismo , Animais , Interferon Tipo I/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fator de Transcrição STAT3/imunologia , Transdução de Sinais/imunologiaRESUMO
Cathelicidins are a family of cationic peptides expressed in mammals that possess numerous bactericidal and immunomodulatory properties. In vitro analyses showed that human, mouse, and pig cathelicidins inhibited Bacillus anthracis bacterial growth at micromolar concentrations in the presence or absence of capsule. Combined in vitro analyses of the effects of each peptide on spore germination and vegetative outgrowth by time lapse phase contrast microscopy, transmission electron microscopy, and flow cytometric analysis showed that only the pig cathelicidin was capable of directly arresting vegetative outgrowth and killing the developing bacilli within the confines of the exosporium. C57BL/6 mice were protected from spore-induced death by each cathelicidin in a time- and dose-dependent manner. Protection afforded by the porcine cathelicidin was due to its bactericidal effects, whereas the human and mouse cathelicidins appeared to mediate protection through increased recruitment of neutrophils to the site of infection. These findings suggest that cathelicidins might be utilized to augment the initial innate immune response to B. anthracis spore exposure and prevent the development of anthrax.
Assuntos
Antraz/prevenção & controle , Antibacterianos/administração & dosagem , Antibacterianos/uso terapêutico , Peptídeos Catiônicos Antimicrobianos/administração & dosagem , Peptídeos Catiônicos Antimicrobianos/uso terapêutico , Bacillus anthracis/efeitos dos fármacos , Animais , Antraz/imunologia , Antraz/microbiologia , Antraz/mortalidade , Antibacterianos/toxicidade , Peptídeos Catiônicos Antimicrobianos/toxicidade , Bacillus anthracis/crescimento & desenvolvimento , Bacillus anthracis/imunologia , Bacillus anthracis/patogenicidade , Feminino , Humanos , Imunidade Inata , Injeções Intraperitoneais , Injeções Subcutâneas , Camundongos , Camundongos Endogâmicos A , Camundongos Endogâmicos C57BL , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/imunologia , Esporos Bacterianos/patogenicidade , Suínos , Virulência/efeitos dos fármacos , Virulência/imunologia , CatelicidinasRESUMO
Anthrax, a disease caused by Bacillus anthracis, affects animals and humans. Because the inert spore is the infectious form of the organism that first contacts the potential host, the interaction between the host and spore exosporium is vital to the initiation of disease. Here, we demonstrate that the integrin Mac-1 is essential for the recognition of the major exosporium protein BclA by phagocytic cells. Expression of Mac-1, but not p150/95, in CHO cells markedly enhanced infection with Sterne strain of B. anthracis spores (WT spores). Conversely, CD11b(-/-) macrophages demonstrated a significant decrease in spore uptake when compared with macrophages from normal C57BL/6 mice. However, when CD11b(-/-) macrophages were infected with DeltabclA spores, spore ingestion was no different from their C57BL/6 counterparts. DeltabclA spores were also efficiently internalized by all CHO cell lines tested, independently of Mac-1 expression. Taken together, these results show that there is an alternative Mac-1-independent pathway involved in spore uptake that is unmasked only in the absence of BclA. Survival studies, using C57BL/6 and CD11b(-/-) mice, revealed that CD11b(-/-) mice are more resistant to infection with WT but not DeltabclA spores. Our experiments also show that DeltabclA spores are more virulent than WT spores in C57BL/6 and A/J mice. Overall, our data indicate that the Mac-1/BclA interaction may play a major role in B. anthracis pathogenesis by promoting spore uptake by professional phagocytes and subsequent access to a favorable niche for transport, germination, and outgrowth in lymphoid tissues.
Assuntos
Bacillus anthracis/fisiologia , Antígeno de Macrófago 1/fisiologia , Fagócitos/imunologia , Fagócitos/microbiologia , Animais , Bacillus anthracis/crescimento & desenvolvimento , Bacillus anthracis/patogenicidade , Células CHO , Linhagem Celular Tumoral , Células Cultivadas , Cricetinae , Cricetulus , Feminino , Humanos , Líquido Intracelular/imunologia , Líquido Intracelular/metabolismo , Líquido Intracelular/microbiologia , Macrófagos Alveolares/imunologia , Macrófagos Alveolares/metabolismo , Macrófagos Alveolares/microbiologia , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/fisiologia , Camundongos , Camundongos Endogâmicos A , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fagócitos/metabolismo , Fagocitose/imunologia , Ligação Proteica/imunologia , Transdução de Sinais/imunologia , Esporos Bacterianos/metabolismo , Esporos Bacterianos/patogenicidade , Esporos Bacterianos/fisiologia , Análise de SobrevidaRESUMO
Plasmacytoid dendritic cells (pDC) specialize in the secretion of type I interferon (IFN). Although multiple pathways that modulate type I IFN responses have been described they are inadequately defined. In this issue of the European Journal of Immunology, evidence for a B cell receptor (BCR)-like signaling cascade in pDC that suppresses type I IFN production is provided.
Assuntos
Células Dendríticas/metabolismo , Interferon Tipo I/metabolismo , Lectinas Tipo C/imunologia , Glicoproteínas de Membrana/imunologia , Receptores Imunológicos/imunologia , Transdução de Sinais/imunologia , Animais , Humanos , Lectinas Tipo C/metabolismo , Glicoproteínas de Membrana/metabolismo , Camundongos , Modelos Imunológicos , Proteínas Tirosina Quinases/fisiologia , Receptores de IgG/imunologia , Receptores Imunológicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
All members of the Bacillus genus produce endospores as part of their life cycle; however, it is not possible to determine the identity of spores by casual or morphological examination. The 2001 anthrax attacks demonstrated a need for fast, dependable methods for detecting Bacillus anthracis spores in vitro and in vivo. We have developed a variety of isotypes and specificities of mAbs that were able to distinguish B. anthracis spores from other Bacillus spores. The majority of Abs were directed toward BclA, a major component of the exosporium, although other components were also distinguished. These Abs did not react with vegetative forms. Some Abs distinguished B. anthracis spores from spores of distantly related species in a highly specific manner, whereas others discriminated among strains that are the closest relatives of B. anthracis. These Abs provide a rapid and reliable means of identifying B. anthracis spores, for probing the structure and function of the exosporium, and in the analysis of the life cycle of B. anthracis.