RESUMO
As Toxoplasma gondii disseminates through its host, the parasite must sense and adapt to its environment and scavenge nutrients. Oxygen (O2) is one such environmental factor and cytoplasmic prolyl 4-hydroxylases (PHDs) are evolutionarily conserved O2 cellular sensing proteins that regulate responses to changes in O2 availability. Toxoplasma expresses 2 PHDs. One of them, TgPHYa hydroxylates SKP1, a subunit of the SCF-E3 ubiquitin ligase complex. In vitro, TgPHYa is important for growth at low O2 levels. However, studies have yet to examine the role that TgPHYa or any other pathogen-encoded PHD plays in virulence and disease. Using a type II ME49 Toxoplasma TgPHYa knockout, we report that TgPHYa is important for Toxoplasma virulence and brain cyst formation in mice. We further find that while TgPHYa mutant parasites can establish an infection in the gut, they are unable to efficiently disseminate to peripheral tissues because the mutant parasites are unable to survive within recruited immune cells. Since this phenotype was abrogated in IFNγ knockout mice, we studied how TgPHYa mediates survival in IFNγ-treated cells. We find that TgPHYa is not required for release of parasite-encoded effectors into host cells that neutralize anti-parasitic processes induced by IFNγ. In contrast, we find that TgPHYa is required for the parasite to scavenge tryptophan, which is an amino acid whose levels are decreased after IFNγ up-regulates the tryptophan-catabolizing enzyme, indoleamine dioxygenase (IDO). We further find, relative to wild-type mice, that IDO knockout mice display increased morbidity when infected with TgPHYa knockout parasites. Together, these data identify the first parasite mechanism for evading IFNγ-induced nutritional immunity and highlight a novel role that oxygen-sensing proteins play in pathogen growth and virulence.
Assuntos
Interferon gama , Oxigênio , Proteínas de Protozoários , Toxoplasma , Animais , Toxoplasma/patogenicidade , Interferon gama/metabolismo , Camundongos , Proteínas de Protozoários/metabolismo , Proteínas de Protozoários/genética , Oxigênio/metabolismo , Camundongos Endogâmicos C57BL , Virulência , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/genética , Feminino , Encéfalo/parasitologia , Encéfalo/metabolismo , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/metabolismo , Toxoplasmose Animal/parasitologia , Toxoplasmose/imunologia , Toxoplasmose/metabolismo , Toxoplasmose/parasitologiaRESUMO
Introduction: Ets1 is a lymphoid-enriched transcription factor that regulates B- and Tcell functions in development and disease. Mice that lack Ets1 (Ets1 KO) develop spontaneous autoimmune disease with high levels of autoantibodies. Naïve CD4 + T cells isolated from Ets1 KO mice differentiate more readily to Th17 cells that secrete IL-17, a cytokine implicated in autoimmune disease pathogenesis. To determine if increased IL-17 production contributes to the development of autoimmunity in Ets1 KO mice, we crossed Ets1 KO mice to mice lacking the IL-17 receptor A subunit (IL17RA KO) to generate double knockout (DKO) mice. Methods: In this study, the status of the immune system of DKO and control mice was assessed utilizing ELISA, ELISpot, immunofluorescent microscopy, and flow cytometric analysis of the spleen, lymph node, skin. The transcriptome of ventral neck skin was analyzed through RNA sequencing. S. aureus clearance kinetics in in exogenously infected mice was conducted using bioluminescent S. aureus and tracked using an IVIS imaging experimental scheme. Results: We found that the absence of IL17RA signaling did not prevent or ameliorate the autoimmune phenotype of Ets1 KO mice but rather that DKO animals exhibited worse symptoms with striking increases in activated B cells and secreted autoantibodies. This was correlated with a prominent increase in the numbers of T follicular helper (Tfh) cells. In addition to the autoimmune phenotype, DKO mice also showed signs of immunodeficiency and developed spontaneous skin lesions colonized by Staphylococcus xylosus. When DKO mice were experimentally infected with Staphylococcus aureus, they were unable to clear the bacteria, suggesting a general immunodeficiency to staphylococcal species. γδ T cells are important for the control of skin staphylococcal infections. We found that mice lacking Ets1 have a complete deficiency of the γδ T-cell subset dendritic epidermal T cells (DETCs), which are involved in skin woundhealing responses, but normal numbers of other skin γδ T cells. To determine if loss of DETC combined with impaired IL-17 signaling might promote susceptibility to staph infection, we depleted DETC from IL17RA KO mice and found that the combined loss of DETC and impaired IL-17 signaling leads to an impaired clearance of the infection. Conclusions: Our studies suggest that loss of IL-17 signaling can result in enhanced autoimmunity in Ets1 deficient autoimmune-prone mice. In addition, defects in wound healing, such as that caused by loss of DETC, can cooperate with impaired IL-17 responses to lead to increased susceptibility to skin staph infections.
Assuntos
Doenças Autoimunes , Proteína Proto-Oncogênica c-ets-1 , Receptores de Interleucina-17 , Infecções Estafilocócicas , Animais , Camundongos , Autoanticorpos , Doenças Autoimunes/genética , Autoimunidade , Interleucina-17 , Receptores de Interleucina-17/metabolismo , Staphylococcus aureus , Proteína Proto-Oncogênica c-ets-1/metabolismoRESUMO
Toxoplasma gondii infection has proven to be an ideal model to understand the delicate balance between protective immunity and immune-mediated pathology during infection. Lethal infection causes a collapse of T regulatory cells (Tregs) mediated by the loss of IL-2 and conversion of Tregs to IFN-γ-producing cells. Importantly, these Tregs highly express the Th1 transcription factor Tbet. To determine the role of Tbet in Tregs, we infected Tbx21f/f -Foxp3YFPCre and control Foxp3YFPCre mice with the type II strain of T. gondii, ME49. The majority of Tbx21f/f -Foxp3YFPCre mice succumbed to a nonlethal dose. Notably, parasite burden was reduced in Tbx21f/f -Foxp3YFPCre compared with Foxp3YFPCre control mice. We found that Tbx21f/f -Foxp3YFPCre mice have significantly higher serum levels of proinflammatory cytokines IFN-γ and TNF-α, suggestive of a heightened immune response. To test if CD4+ T cells were driving immunopathology, we treated Tbx21f/f -Foxp3YFPCre mice with anti-CD4-depleting Abs and partially rescued these mice. Broad-spectrum antibiotic treatment also improved survival, demonstrating a role for commensal flora in immunopathology in Tbx21f/f -Foxp3YFPCre mice. RNA sequencing analysis reinforced that Tbet regulates several key cellular pathways, including leukocyte activation, regulation of lymphocyte activation, and cell cycle progression, that help to maintain fitness in Tregs during Th1 responses. Taken together, our data show an important role for Tbet in Tregs in preventing lethal immunopathology during T. gondii infection, further highlighting the protective role of Treg plasticity in controlling immune responses to infection and the microbiota.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Proteínas com Domínio T/metabolismo , Linfócitos T Reguladores/imunologia , Toxoplasmose/imunologia , Animais , Feminino , Fatores de Transcrição Forkhead/genética , Interferon gama/metabolismo , Ativação Linfocitária , Masculino , Camundongos , Proteínas com Domínio T/genética , Toxoplasmose/metabolismo , Toxoplasmose/patologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
The safety and efficacy of several life-saving therapeutic proteins are compromised due to their immunogenicity. Once a sustained immune response against a protein-based therapy is established, clinical options that are safe and cost-effective become limited. Prevention of immunogenicity of therapeutic proteins prior to their initial use is critical as it is often difficult to reverse an established immune response. Here, we discuss a rational design and testing of a phosphatidylserine-containing nanoparticle platform for novel oral prophylactic reverse vaccination approach, i.e., pre-treatment of a therapeutic protein in the presence of nanoparticles to prevent immunogenicity of protein therapies.
Assuntos
Imunoterapia , Nanopartículas , Animais , CamundongosRESUMO
Toxoplasmic encephalitis can develop in individuals infected with the protozoan parasite Toxoplasma gondii and is typified by parasite replication and inflammation within the brain. Patients often present with seizures, but the parasite genes and host pathways involved in seizure development and/or propagation are unknown. We previously reported that seizure induction in Toxoplasma-infected mice is parasite strain dependent. Using quantitative trait locus mapping, we identify four loci in the Toxoplasma genome that potentially correlate with seizure development. In one locus, we identify the polymorphic virulence factor, GRA15, as a Toxoplasma gene associated with onset of seizures. GRA15 was previously shown to regulate host NF-κB-dependent gene expression during acute infections, and we demonstrate a similar role for GRA15 in brains of toxoplasmic encephalitic mice. GRA15 is important for increased expression of interleukin 1 beta (IL-1ß) and other IL-1 pathway host genes, which is significant since IL-1 signaling is involved in onset of seizures. Inhibiting IL-1 receptor signaling reduced seizure severity in Toxoplasma-infected mice. These data reveal one mechanism by which seizures are induced during toxoplasmic encephalitis. IMPORTANCE Inflammation in the brain caused by infections lead to seizures and other neurological symptoms. But the microbial products that induce seizures as well as the host pathways downstream of these factors are largely unknown. Using a nonbiased genetic screening approach, we identify 4 loci in the Toxoplasma genome that correlate with the induction of seizures in Toxoplasma-infected mice. One of these loci contains the gene, GRA15, which we demonstrate is associated with seizure development in toxoplasmic encephalitic mice. GRA15 accomplishes this in part by activating host pathways that lead to increased IL-1 receptor signaling and that inhibition of this signaling inhibits Toxoplasma-induced seizures.
Assuntos
Encéfalo/imunologia , Interações Hospedeiro-Parasita/imunologia , Interleucina-1beta/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Transdução de Sinais/imunologia , Toxoplasma/genética , Animais , Encéfalo/parasitologia , Encéfalo/patologia , Feminino , Expressão Gênica , Genoma de Protozoário , Humanos , Interleucina-1beta/genética , Camundongos , Camundongos Endogâmicos C57BL , Convulsões/imunologia , Convulsões/parasitologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/parasitologia , Fatores de VirulênciaRESUMO
Cryptococcus neoformans is a devastating opportunistic fungal pathogen. It mostly impacts people in an immunocompromised state, such as people living with HIV/AIDS and following organ transplantation. Macrophages, in addition to being a major cellular reservoir of HIV-1, represent a unique niche in which both C. neoformans and HIV-1 can coinhabit in the course of natural infection. Here, we report the observation that HIV-1 infection of THP-1 macrophages increases the rate at which they phagocytose C. neoformans cells. We investigated the tumor necrosis factor alpha (TNF-α) signaling and nuclear factor kappa B (NF-κB) activation in human monocyte-derived macrophages infected with HIV-1 alone, as well as those coinfected with HIV-1 and C. neoformans Our findings showed that while HIV-1 infection alone upregulates TNF-α production and activates NF-κB signaling, C. neoformans coinfection drastically and rapidly dampens this proinflammatory response. These data suggest an antagonism between two important human pathogens during coinfection of macrophages.IMPORTANCE Fungal infections are one of the leading causes of death for people who live with HIV/AIDS. Even though these pathogens are independently well studied, it is still enigmatic how coinfection with HIV-1 and C. neoformans alters gene expression and cellular processes, especially in clinically relevant cell types. Understanding the interplay between these two pathogens is especially critical because C. neoformans mortality largely depends on the host's immunocompromised state during viral infection. Studying this coinfection is challenging since HIV-1 only infects human cells, and the modified murine HIV-1 virus does not reproduce the clinical landmarks of HIV-1 infection or AIDS in mice. Our observations shed light on how these two pathogens trigger opposing trends in TNF-α and NF-κB signaling in human monocyte-derived macrophages.
Assuntos
Coinfecção/microbiologia , Coinfecção/virologia , Cryptococcus neoformans/imunologia , HIV-1/imunologia , Macrófagos/imunologia , Macrófagos/virologia , Fator de Necrose Tumoral alfa/análise , Coinfecção/imunologia , Cryptococcus neoformans/patogenicidade , HIV-1/patogenicidade , Humanos , Pulmão , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/imunologia , Células THP-1 , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Regulação para Cima , Quinase Induzida por NF-kappaBRESUMO
The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is a candidate vaccine antigen that binds angiotensin-converting enzyme 2 (ACE2), leading to virus entry. Here, it is shown that rapid conversion of recombinant RBD into particulate form via admixing with liposomes containing cobalt-porphyrin-phospholipid (CoPoP) potently enhances the functional antibody response. Antigen binding via His-tag insertion into the CoPoP bilayer results in a serum-stable and conformationally intact display of the RBD on the liposome surface. Compared to other vaccine formulations, immunization using CoPoP liposomes admixed with recombinant RBD induces multiple orders of magnitude higher levels of antibody titers in mice that neutralize pseudovirus cell entry, block RBD interaction with ACE2, and inhibit live virus replication. Enhanced immunogenicity can be accounted for by greater RBD uptake into antigen-presenting cells in particulate form and improved immune cell infiltration in draining lymph nodes. QS-21 inclusion in the liposomes results in an enhanced antigen-specific polyfunctional T cell response. In mice, high dose immunization results in minimal local reactogenicity, is well-tolerated, and does not elevate serum cobalt levels. Taken together, these results confirm that particulate presentation strategies for the RBD immunogen should be considered for inducing strongly neutralizing antibody responses against SARS-CoV-2.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , COVID-19/prevenção & controle , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Enzima de Conversão de Angiotensina 2/imunologia , Animais , Sítios de Ligação , COVID-19/imunologia , Feminino , Células HEK293 , Humanos , Imunogenicidade da Vacina/imunologia , Camundongos , Pandemias/prevenção & controle , Coelhos , Vacinação , Replicação Viral/efeitos dos fármacosRESUMO
Neutrophils can shape adaptive immunity; however, their role in vaccine-induced protection against infections in vivo remains unclear. Here, we tested their role in the clinically relevant polysaccharide conjugate vaccine against Streptococcus pneumoniae (pneumococcus). We antibody depleted neutrophils during vaccination, allowed them to recover, and 4 weeks later challenged mice with pneumococci. We found that while isotype-treated vaccinated controls were protected against an otherwise lethal infection in naive mice, full protection was lost upon neutrophil depletion. Compared to vaccinated controls, neutrophil-depleted mice had higher lung bacterial burdens, increased incidence of bacteremia, and lower survival rates. Sera from neutrophil-depleted mice had less antipneumococcal IgG2c and IgG3, were less efficient at inducing opsonophagocytic killing of bacteria by neutrophils in vitro, and were worse at protecting naive mice against pneumococcal pneumonia. In summary, neutrophils are required during vaccination for optimal host protection, which has important implications for future vaccine design against pneumococci and other pathogens.
Assuntos
Anticorpos Antibacterianos/imunologia , Neutrófilos/imunologia , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas/imunologia , Streptococcus pneumoniae/imunologia , Animais , Formação de Anticorpos , Carga Bacteriana , Feminino , Imunização , Switching de Imunoglobulina , Camundongos , Camundongos Endogâmicos C57BL , Infecções Pneumocócicas/imunologia , Infecções Pneumocócicas/microbiologia , Vacinas Pneumocócicas/administração & dosagem , Vacinas Conjugadas/administração & dosagem , Vacinas Conjugadas/imunologiaRESUMO
Infection and inflammation within the brain induces changes in neuronal connectivity and function. The intracellular protozoan parasite, Toxoplasma gondii, is one pathogen that infects the brain and can cause encephalitis and seizures. Persistent infection by this parasite is also associated with behavioral alterations and an increased risk for developing psychiatric illness, including schizophrenia. Current evidence from studies in humans and mouse models suggest that both seizures and schizophrenia result from a loss or dysfunction of inhibitory synapses. In line with this, we recently reported that persistent T. gondii infection alters the distribution of glutamic acid decarboxylase 67 (GAD67), an enzyme that catalyzes GABA synthesis in inhibitory synapses. These changes could reflect a redistribution of presynaptic machinery in inhibitory neurons or a loss of inhibitory nerve terminals. To directly assess the latter possibility, we employed serial block face scanning electron microscopy (SBFSEM) and quantified inhibitory perisomatic synapses in neocortex and hippocampus following parasitic infection. Not only did persistent infection lead to a significant loss of perisomatic synapses, it induced the ensheathment of neuronal somata by myeloid-derived cells. Immunohistochemical, genetic, and ultrastructural analyses revealed that these myeloid-derived cells included activated microglia. Finally, ultrastructural analysis identified myeloid-derived cells enveloping perisomatic nerve terminals, suggesting they may actively displace or phagocytose synaptic elements. Thus, these results suggest that activated microglia contribute to perisomatic inhibitory synapse loss following parasitic infection and offer a novel mechanism as to how persistent T. gondii infection may contribute to both seizures and psychiatric illness.
Assuntos
Comunicação Celular/fisiologia , Microglia/metabolismo , Inibição Neural/fisiologia , Neurônios/metabolismo , Sinapses/metabolismo , Toxoplasmose/metabolismo , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/parasitologia , Microglia/patologia , Neurônios/parasitologia , Neurônios/patologia , Sinapses/parasitologia , Sinapses/patologia , Toxoplasma , Toxoplasmose/patologiaRESUMO
A common feature shared by systemic fungal pathogens of environmental origin, such as Cryptococcus neoformans, is their ability to adapt to mammalian core body temperature. In C. neoformans, this adaptation is accompanied by Ccr4-mediated decay of ribosomal protein mRNAs. Here we use the related, but thermo-intolerant species Cryptococcus amylolentus to demonstrate that this response contributes to host-temperature adaptation and pathogenicity of cryptococci. In a C. neoformans ccr4Δ mutant, stabilized ribosomal protein mRNAs are retained in the translating pool, and stress-induced transcriptomic changes are reduced in comparison with the wild type strain, likely due to ineffective translation of transcription factors. In addition, the mutant displays increased exposure of cell wall glucans, and recognition by Dectin-1 results in increased phagocytosis by lung macrophages, linking mRNA decay to adaptation and immune evasion.
Assuntos
Cryptococcus neoformans/genética , Estabilidade de RNA/genética , RNA Mensageiro/metabolismo , Proteínas Ribossômicas/genética , Termotolerância/genética , Animais , Antígenos de Fungos/imunologia , Cryptococcus/genética , Cryptococcus/imunologia , Cryptococcus/metabolismo , Cryptococcus neoformans/imunologia , Cryptococcus neoformans/metabolismo , Regulação Fúngica da Expressão Gênica , Glucanos/imunologia , Evasão da Resposta Imune/imunologia , Lectinas Tipo C/imunologia , Macrófagos Alveolares/imunologia , Camundongos , Fagocitose/imunologia , Ribonucleases/genéticaRESUMO
Maintenance of tissue integrity in skeletal muscle requires the immunomodulatory and regenerative functions of muscle-resident regulatory T cells (Tregs). Chronic skeletal muscle infections, such as with Toxoplasma gondii disrupt normal immuno-regulatory networks and lead to pathogenic changes in Treg function. Specifically, Tregs during chronic T. gondii infection reinforce an inflammatory macrophage bias that exacerbates injury in skeletal muscle. In this study, we investigated whether the aberrations in skeletal muscle Treg function during chronic infection could be overcome by treatment with Treg-related factors associated with enhanced muscle regeneration during sterile injury. We show treatment of chronically infected mice with the Treg promoting therapies, interleukin-2 complexed with anti-IL-2 antibody or interleukin-33 (IL-33), did not restore macrophage dynamics or muscle function, respectively, in vivo. However supplementation of known Treg-derived factors, interleukin-10 (IL-10) and amphiregulin (Areg) improved muscle function and skewed macrophages toward a restorative phenotype in the presence of chronic infection. These shifts in macrophage phenotype are coupled with enhanced physiologic parameters of regeneration. Together, these data suggest that while Treg-mediated immuno-regulation is compromised during chronic skeletal muscle infection, supplementation of canonical Treg-derived factors such as IL-10 and Areg can restore immunologic balance and enhance muscle repair.
RESUMO
The robust regenerative potential of skeletal muscle is imperative for the maintenance of tissue function across a host of potential insults including exercise, infection, and trauma. The highly coordinated action of multiple immune populations, especially macrophages, plays an indispensable role in guiding this reparative program. However, it remains unclear how skeletal muscle repair proceeds in a chronically inflamed setting, such as infection, where an active immune response is already engaged. To address this question, we used a cardiotoxin injury model to challenge the reparative potential of chronically infected muscle. Compared with regenerating naive skeletal muscle, infected skeletal muscle exhibited multiple indicators of delayed muscle repair including a divergent morphologic response to injury and dysregulated expression of myogenic regulatory factors. Further, using both flow cytometric and single-cell RNA sequencing approaches, we show that reduced macrophage heterogeneity due to delayed emergence of restorative subsets underlies dysfunctional tissue repair during chronic infection. Our findings highlight how the preexisting inflammatory environment within tissue alters reparative immunity and ultimately the quality of tissue regeneration.
Assuntos
Macrófagos/metabolismo , Desenvolvimento Muscular/imunologia , Desenvolvimento Muscular/fisiologia , Músculo Esquelético/metabolismo , Animais , Doença Crônica , Doenças Transmissíveis/imunologia , Biologia Computacional , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Camundongos , Camundongos Endogâmicos C57BL , Desenvolvimento Muscular/genética , Músculo Esquelético/lesões , Músculo Esquelético/patologia , Fatores de Regulação Miogênica/genética , Fatores de Regulação Miogênica/metabolismo , Toxoplasma , ToxoplasmoseRESUMO
The CD4+ lineage-specific transcription factor Thpok is required for intrathymic CD4+ T cell differentiation and, together with its homolog LRF, supports CD4+ T cell helper effector responses. However, it is not known whether these factors are needed for the regulatory T cell (Treg) arm of MHC class II responses. In this study, by inactivating in mice the genes encoding both factors in differentiated Tregs, we show that Thpok and LRF are redundantly required to maintain the size and functions of the postthymic Treg pool. They support IL-2-mediated gene expression and the functions of the Treg-specific factor Foxp3. Accordingly, Treg-specific disruption of Thpok and Lrf causes a lethal inflammatory syndrome similar to that resulting from Treg deficiency. Unlike in conventional T cells, Thpok and LRF functions in Tregs are not mediated by their repression of the transcription factor Runx3. Additionally, we found that Thpok is needed for the differentiation of thymic Treg precursors, an observation in line with the fact that Foxp3+ Tregs are CD4+ cells. Thus, a common Thpok-LRF node supports both helper and regulatory arms of MHC class II responses.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Linfócitos T Reguladores/imunologia , Fatores de Transcrição/metabolismo , Animais , Diferenciação Celular , Linhagem da Célula , Células Cultivadas , Proteínas de Ligação a DNA/genética , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Antígenos de Histocompatibilidade Classe II/metabolismo , Interleucina-2/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Linfócitos T Reguladores/microbiologia , Fatores de Transcrição/genéticaRESUMO
Toxoplasma gondii is a widespread parasitic pathogen that infects over a third of the world's population. Following an acute infection, the parasite can persist within its mammalian host as intraneuronal or intramuscular cysts. Cysts will occasionally reactivate, and - depending on the host's immune status and site of reactivation - encephalitis or myositis can develop. Because these diseases have high levels of morbidity and can be lethal, it is important to understand how Toxoplasma traffics to these tissues, how the immune response controls parasite burden and contributes to tissue damage, and what mechanisms underlie neurological and muscular pathologies that toxoplasmosis patients present with. This review aims to summarize recent important developments addressing these critical topics.
Assuntos
Sistema Nervoso Central/parasitologia , Músculo Esquelético/parasitologia , Toxoplasmose/parasitologia , Animais , Sistema Nervoso Central/patologia , Humanos , Músculo Esquelético/patologia , Toxoplasmose/imunologiaRESUMO
The coordination of macrophage polarization is essential for the robust regenerative potential of skeletal muscle. Repair begins with a phase mediated by inflammatory monocytes (IM) and proinflammatory macrophages (M1), followed by polarization to a proregenerative macrophage (M2) phenotype. Recently, regulatory T cells (Tregs) were described as necessary for this M1 to M2 transition. We report that chronic infection with the protozoan parasite Toxoplasma gondii causes a nonresolving Th1 myositis with prolonged tissue damage associated with persistent M1 accumulation. Surprisingly, Treg ablation during chronic infection rescues macrophage homeostasis and skeletal muscle fiber regeneration, showing that Tregs can directly contribute to muscle damage. This study provides evidence that the tissue environment established by the parasite could lead to a paradoxical pathogenic role for Tregs. As such, these findings should be considered when tailoring therapies directed at Tregs in inflammatory settings.
Assuntos
Macrófagos/imunologia , Miosite/imunologia , Linfócitos T Reguladores/imunologia , Toxoplasmose/imunologia , Transferência Adotiva , Animais , Diferenciação Celular/imunologia , Feminino , Citometria de Fluxo , Ativação Linfocitária/imunologia , Ativação de Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/imunologia , Músculo Esquelético/microbiologia , Músculo Esquelético/patologia , Miosite/microbiologia , Miosite/patologia , Reação em Cadeia da Polimerase em Tempo Real , Toxoplasmose/patologiaRESUMO
In vitro culture is an important complement, or substitute, to in vivo approaches in order to study T cell effector differentiation. Here, we describe culture conditions that generate specific effector cell types by exposing naïve T cells to appropriate cytokine signals.
Assuntos
Diferenciação Celular , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/metabolismo , Animais , Células Apresentadoras de Antígenos/citologia , Células Apresentadoras de Antígenos/metabolismo , Separação Celular , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Citometria de Fluxo , Imunofluorescência , Imunofenotipagem , Técnicas In Vitro , Camundongos , Baço/citologiaRESUMO
Mice sensitized to ovalbumin (OVA) develop allergic airway disease (AAD) with short-term daily OVA aerosol challenge; inflammation resolves with long-term OVA aerosol exposure, resulting in local inhalational tolerance (LIT). Cbl-b is an E3 ubiquitin ligase involved with CD28 signaling; Cbl-b(-/-) effector T cells are resistant to regulatory T cell-mediated suppression in vitro and in vivo. The present study utilized Cbl-b(-/-) mice to investigate the role of Cbl-b in the development of AAD and LIT. Cbl-b(-/-) mice exhibited increased airway inflammation during AAD, which failed to resolve with long-term OVA aerosol exposure. Exacerbation of inflammation in Cbl-b(-/-) mice correlated with increased proinflammatory cytokine levels and expansion of effector T cells in the BAL during AAD, but did not result in either a modulation of lymphocyte subsets in systemic tissues or in OVA-specific IgE in serum. These results implicate a role for Cbl-b in the resolution of allergic airway inflammation.
RESUMO
The transcription factor ThPOK promotes CD4(+) T cell differentiation in the thymus. Here, using a mouse strain that allows post-thymic gene deletion, we show that ThPOK maintains CD4(+) T lineage integrity and couples effector differentiation to environmental cues after antigenic stimulation. ThPOK preserved the integrity and amplitude of effector responses and was required for proper differentiation of types 1 and 2 helper T cells in vivo by restraining the expression and function of Runx3, a nuclear factor crucial for cytotoxic T cell differentiation. The transcription factor LRF acts redundantly with ThPOK to prevent the transdifferentiation of mature CD4(+) T cells into CD8(+) T cells. As such, the ThPOK-LRF transcriptional module was essential for CD4(+) T cell integrity and responses.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Proteínas de Ligação a DNA/imunologia , Timo/imunologia , Fatores de Transcrição/imunologia , Animais , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular/imunologia , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Subunidade alfa 3 de Fator de Ligação ao Core/genética , Subunidade alfa 3 de Fator de Ligação ao Core/imunologia , Subunidade alfa 3 de Fator de Ligação ao Core/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Citometria de Fluxo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Análise de Sequência com Séries de Oligonucleotídeos , Células Th1/imunologia , Células Th1/metabolismo , Células Th2/imunologia , Células Th2/metabolismo , Timo/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcriptoma/imunologiaRESUMO
FOXP3(+) regulatory T cells (Treg cells) are abundant in the intestine, where they prevent dysregulated inflammatory responses to self and environmental stimuli. It is now appreciated that Treg cells acquire tissue-specific adaptations that facilitate their survival and function; however, key host factors controlling the Treg response in the intestine are poorly understood. The interleukin (IL)-1 family member IL-33 is constitutively expressed in epithelial cells at barrier sites, where it functions as an endogenous danger signal, or alarmin, in response to tissue damage. Recent studies in humans have described high levels of IL-33 in inflamed lesions of inflammatory bowel disease patients, suggesting a role for this cytokine in disease pathogenesis. In the intestine, both protective and pathological roles for IL-33 have been described in murine models of acute colitis, but its contribution to chronic inflammation remains ill defined. Here we show in mice that the IL-33 receptor ST2 is preferentially expressed on colonic Treg cells, where it promotes Treg function and adaptation to the inflammatory environment. IL-33 signalling in T cells stimulates Treg responses in several ways. First, it enhances transforming growth factor (TGF)-ß1-mediated differentiation of Treg cells and, second, it provides a necessary signal for Treg-cell accumulation and maintenance in inflamed tissues. Strikingly, IL-23, a key pro-inflammatory cytokine in the pathogenesis of inflammatory bowel disease, restrained Treg responses through inhibition of IL-33 responsiveness. These results demonstrate a hitherto unrecognized link between an endogenous mediator of tissue damage and a major anti-inflammatory pathway, and suggest that the balance between IL-33 and IL-23 may be a key controller of intestinal immune responses.
Assuntos
Interleucinas/imunologia , Intestinos/citologia , Intestinos/imunologia , Linfócitos T Reguladores/imunologia , Animais , Colite/imunologia , Colite/patologia , Colo/citologia , Colo/imunologia , Colo/patologia , Modelos Animais de Doenças , Feminino , Imunidade nas Mucosas , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Interleucina-23/imunologia , Interleucina-33 , Interleucinas/antagonistas & inibidores , Interleucinas/metabolismo , Intestinos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Interleucina/metabolismo , Transdução de Sinais/imunologia , Linfócitos T Reguladores/citologia , Timo/citologia , Fator de Crescimento Transformador beta/metabolismoRESUMO
Mutations of STAT3 underlie the autosomal dominant form of hyperimmunoglobulin E syndrome (HIES). STAT3 has critical roles in immune cells and thus, hematopoietic stem cell transplantation (HSCT), might be a reasonable therapeutic strategy in this disease. However, STAT3 also has critical functions in nonhematopoietic cells and dissecting the protean roles of STAT3 is limited by the lethality associated with germline deletion of Stat3. Thus, predicting the efficacy of HSCT for HIES is difficult. To begin to dissect the importance of STAT3 in hematopoietic and nonhematopoietic cells as it relates to HIES, we generated a mouse model of this disease. We found that these transgenic mice recapitulate multiple aspects of HIES, including elevated serum IgE and failure to generate Th17 cells. We found that these mice were susceptible to bacterial infection that was partially corrected by HSCT using wild-type bone marrow, emphasizing the role played by the epithelium in the pathophysiology of HIES.