RESUMO
The evolutionary pressures exerted by viral infections have led to the development of various cellular proteins with potent antiviral activities, some of which are known as antiviral restriction factors. TRIpartite Motif-containing protein 5 alpha (TRIM5α) is a well-studied restriction factor of retroviruses that exhibits virus- and host-species-specific functions in protecting against cross-primate transmission of specific lentiviruses. This specificity is achieved at the level of the host gene through positive selection predominantly within its C-terminal B30.2/PRYSPRY domain, which is responsible for the highly specific recognition of retroviral capsids. However, more recent work has challenged this paradigm, demonstrating TRIM5α as a restriction factor for retroelements as well as phylogenetically distinct viral families, acting similarly through the recognition of viral gene products via B30.2/PRYSPRY. This spectrum of antiviral activity raises questions regarding the genetic and structural plasticity of this protein as a mediator of the recognition of a potentially diverse array of viral molecular patterns. This review highlights the dynamic evolutionary footprint of the B30.2/PRYSPRY domain in response to retroviruses while exploring the guided 'specificity' conferred by the totality of TRIM5α's additional domains that may account for its recently identified promiscuity.
Assuntos
Imunidade Inata , Retroviridae , Proteínas com Motivo Tripartido , Ubiquitina-Proteína Ligases , Animais , Humanos , Fatores de Restrição Antivirais/metabolismo , Evolução Molecular , Interações Hospedeiro-Patógeno/imunologia , Retroviridae/imunologia , Retroviridae/genética , Retroviridae/fisiologia , Proteínas com Motivo Tripartido/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
ABSTRACT Toxoplasma gondii infection can cause ocular manifestations after acquired and congenital disease. We report two cases of symptomatic congenital toxoplasmosis with ocular involvement in non-twin siblings, with a 2-year interval between pregnancies. Vertical transmission of toxoplasmosis in successive pregnancies, which was once considered impossible, is now found to be plausible even in immunocompetent subjects.
RESUMO A infecção pelo Toxoplasma gondii pode causar manifestações oculares tanto após a sua forma congênita quanto a sua forma adquirida. Reportamos aqui dois casos de toxoplasmose congênita sintomática com envolvimento ocular em irmãos não gêmeos, com intervalo de 2 anos entre gestações. A transmissão vertical da toxoplasmose em gestações sucessivas, outrora considerada impossível, é um evento plausível mesmo em indivíduos imunocompetentes.
RESUMO
The severity of toxoplasmosis depends on a combination of host and parasite factors. Among them, the Toxoplasma strain causing the infection is an important determinant of the disease outcome. Type 2 strains dominate in Europe, whereas in North America type 2, followed by type 3 and 12 strains are commonly isolated from wildlife and patients. To identify the strain type a person is infected with, serological typing provides a promising alternative to the often risky and not always possible biopsy-based DNA methods of genotyping. However, despite recent advances in serotyping, improvements in the sensitivity and specificity are still needed, and it does not yet discriminate among the major Toxoplasma lineages infecting people. Moreover, since infections caused by non-1/2/3 strains have been associated with more severe disease, the ability to identify these is critical. In the present study we investigated the diagnostic potential of an ELISA-based assay using 28 immunogenic Toxoplasma peptides derived from a recent large-scale peptide array screen. Our results show that a discrete number of peptides, derived from Toxoplasma dense granule proteins (GRA3, GRA5, GRA6, and GRA7) was sufficient to discriminate among archetypal strains that infect mice and humans. The assay specifically relies on ratios that compare individual serum reactivities against GRA-specific polymorphic peptide variants in order to determine a "reactivity fingerprint" for each of the major strains. Importantly, nonarchetypal strains that possess a unique combination of alleles, different from types 1/2/3, showed either a non-reactive, or different combinatorial, mixed serum reactivity signature that was diagnostic in its own right, and that can be used to identify these strains. Of note, we identified a distinct "HG11/12" reactivity pattern using the GRA6 peptides that is able to distinguish HG11/12 from archetypal North American/European strain infections.
Assuntos
Toxoplasma , Toxoplasmose , Animais , Antígenos de Protozoários/genética , Europa (Continente) , Humanos , Camundongos , América do Norte , Peptídeos , Proteínas de Protozoários/genética , Toxoplasma/genética , Toxoplasmose/diagnósticoRESUMO
The intracellular parasite Toxoplasma gondii can cause chronic infections in most warm-blooded animals, including humans. In the USA, strains belonging to four different Toxoplasma clonal lineages (types 1, 2, 3, and 12) are commonly isolated, whereas strains not belonging to these lineages are predominant in other continents such as South America. Strain type plays a pivotal role in determining the severity of Toxoplasma infection. Therefore, it is epidemiologically relevant to develop a non-invasive and inexpensive method for determining the strain type in Toxoplasma infections and to correlate the genotype with disease outcome. Serological typing is based on the fact that many host antibodies are raised against immunodominant parasite proteins that are highly polymorphic between strains. However, current serological assays can only reliably distinguish type 2 from non-type 2 infections. To improve these assays, mouse, rabbit, and human infection serum were reacted against 950 peptides from 62 different polymorphic Toxoplasma proteins by using cellulose membrane peptide arrays. This allowed us to identify the most antigenic peptides and to pinpoint the most relevant polymorphisms that determine strain specificity. Our results confirm the utility of previously described peptides and identify novel peptides that improve and increase the specificity of the assay. In addition, a large number of novel proteins showed potential to be used for Toxoplasma diagnosis. Among these, peptides derived from several rhoptry, dense granule, and surface proteins represented promising candidates that may be used in future experiments to improve Toxoplasma serotyping. Moreover, a redesigned version of the published GRA7 typing peptide performed better and specifically distinguished type 3 from non-type 3 infections in sera from mice, rabbits, and humans.
Assuntos
Peptídeos , Análise Serial de Proteínas/métodos , Proteínas de Protozoários , Sorotipagem/métodos , Toxoplasma/classificação , Toxoplasmose/diagnóstico , Toxoplasmose/parasitologia , Sequência de Aminoácidos , Epitopos/química , Epitopos/imunologia , Genoma de Protozoário , Genótipo , Humanos , Peptídeos/química , Peptídeos/imunologia , Proteínas de Protozoários/imunologia , Sensibilidade e Especificidade , Toxoplasma/genética , Toxoplasma/imunologia , Toxoplasmose/imunologia , Sequenciamento Completo do GenomaRESUMO
Neospora caninum, a cyst-forming apicomplexan parasite, is a leading cause of neuromuscular diseases in dogs as well as fetal abortion in cattle worldwide. The importance of the domestic and sylvatic life cycles of Neospora, and the role of vertical transmission in the expansion and transmission of infection in cattle, is not sufficiently understood. To elucidate the population genomics of Neospora, we genotyped 50 isolates collected worldwide from a wide range of hosts using 19 linked and unlinked genetic markers. Phylogenetic analysis and genetic distance indices resolved a single genotype of N. caninum Whole-genome sequencing of 7 isolates from 2 different continents identified high linkage disequilibrium, significant structural variation, but only limited polymorphism genome-wide, with only 5,766 biallelic single nucleotide polymorphisms (SNPs) total. Greater than half of these SNPs (â¼3,000) clustered into 6 distinct haploblocks and each block possessed limited allelic diversity (with only 4 to 6 haplotypes resolved at each cluster). Importantly, the alleles at each haploblock had independently segregated across the strains sequenced, supporting a unisexual expansion model that is mosaic at 6 genomic blocks. Integrating seroprevalence data from African cattle, our data support a global selective sweep of a highly inbred livestock pathogen that originated within European dairy stock and expanded transcontinentally via unisexual mating and vertical transmission very recently, likely the result of human activities, including recurrent migration, domestication, and breed development of bovid and canid hosts within similar proximities.
Assuntos
Genoma , Interações Hospedeiro-Parasita , Neospora/genética , Animais , Bovinos , Genótipo , Recombinação GenéticaRESUMO
Infection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex secreted on the parasite surface that functions to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-γ in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis.
Assuntos
Moléculas de Adesão Celular/imunologia , Células Dendríticas/imunologia , Imunidade Inata , Macrófagos/imunologia , Proteínas de Protozoários/imunologia , Ácidos Siálicos/imunologia , Receptor 2 Toll-Like/imunologia , Receptor 4 Toll-Like/imunologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Animais , Interleucina-12/imunologia , Camundongos , Camundongos Knockout , Receptor 2 Toll-Like/genética , Receptor 4 Toll-Like/genética , Toxoplasmose Animal/genéticaRESUMO
Phosphoinositide 3-kinase (PI3K) plays an integral role in lymphocyte function. Mutations in PIK3CD and PIK3R1, encoding the PI3K p110δ and p85α subunits, respectively, cause increased PI3K activity and result in immunodeficiency with immune dysregulation. We describe here the first cases of disseminated and congenital toxoplasmosis in a mother and child who share a pathogenic mutation in PIK3R1 and review the mechanisms underlying susceptibility to severe Toxoplasma gondii infection in activated PI3Kδ syndrome (APDS) and in other forms of primary immunodeficiency.
Assuntos
Classe I de Fosfatidilinositol 3-Quinases/genética , Classe Ia de Fosfatidilinositol 3-Quinase/genética , Síndromes de Imunodeficiência/imunologia , Mutação/genética , Toxoplasma/fisiologia , Toxoplasmose Congênita/imunologia , Adulto , Anticorpos Antiprotozoários/sangue , Criança , Feminino , Humanos , Imunidade Materno-Adquirida , Síndromes de Imunodeficiência/diagnóstico , Síndromes de Imunodeficiência/genética , Lactente , Linfadenopatia , Mães , Fenótipo , Toxoplasmose Congênita/diagnóstico , Toxoplasmose Congênita/genéticaRESUMO
Regulating complement is an important step in the establishment of infection by microbial pathogens. Toxoplasma gondii actively resists complement-mediated killing in non-immune human serum (NHS) by inactivating C3b, however the precise molecular basis is unknown. Here, a flow cytometry-based C3b binding assay demonstrated that Type II strains had significantly higher levels of surface-bound C3b than Type I strains. However, both strains efficiently inactivated C3b and were equally resistant to serum killing, suggesting that resistance is not strain-dependent. Toxoplasma activated both the lectin (LP) and alternative (AP) pathways, and the deposition of C3b was both strain and lectin-dependent. A flow cytometry-based lectin binding assay identified strain-specific differences in the level and heterogeneity of surface glycans detected. Specifically, increased lectin-binding by Type II strains correlated with higher levels of the LP recognition receptor mannose binding lectin (MBL). Western blot analyses demonstrated that Toxoplasma recruits both classical pathway (CP) and LP regulator C4b-binding proteins (C4BP) and AP regulator Factor H (FH) to the parasite surface to inactivate bound C3b-iC3b and C3dg and limit formation of the C5b-9 attack complex. Blocking FH and C4BP contributed to increased C5b-9 formation in vitro. However, parasite susceptibility in vitro was only impacted when FH was blocked, indicating that down regulation of the alternative pathway by FH may be more critical for parasite resistance. Infection of C3 deficient mice led to uncontrolled parasite growth, acute mortality, and reduced antibody production, indicating that both the presence of C3, and the ability of the parasite to inactivate C3, was protective. Taken together, our results establish that Toxoplasma regulation of the complement system renders mice resistant to acute infection by limiting parasite proliferation in vivo, but susceptible to chronic infection, with all mice developing transmissible cysts to maintain its life cycle.
Assuntos
Proteína de Ligação ao Complemento C4b/imunologia , Fator H do Complemento/imunologia , Citotoxicidade Imunológica , Interações Hospedeiro-Parasita/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Toxoplasmose/parasitologia , Animais , Ativação do Complemento , Complemento C3/deficiência , Convertases de Complemento C3-C5 da Via Alternativa , Proteína de Ligação ao Complemento C4b/metabolismo , Fator H do Complemento/metabolismo , Humanos , Imunoglobulina G/imunologia , Camundongos , Toxoplasmose/metabolismoRESUMO
Background: Data on adult meningitis among patients infected with the human immunodeficiency virus (HIV) is scarce in western sub-Saharan Africa, including Ghana. Methods: HIV-infected adults with a provisional diagnosis of meningitis were consecutively enrolled, between August 2014 and January 2016. After patient data collection, cerebrospinal fluid (CSF) was obtained and evaluated for microbiological aetiologies, cell counts and biochemistry. Caregiver clinicians provided limited data for inpatients at the end-point of discharge or death. Results: Complete data sets from 84 patients were analysed (inpatients=63, outpatients=21). Median age was 40 years with 56% (47/84) being females. Only 30% (25/84) of the patients were on antiretroviral therapy (ART). CD4+ T-cell count was available for 81% (68/84) of patients and 61.9% (52/84) had counts below 150 cells/µL [median and interquartile range=56 (13.8-136)]. Microbiological aetiologies were detected in 60.7% (51/84) patients with the following distribution-Toxoplasmosis (25%), Epstein-Barr virus (28.6%), Cytomegalovirus and Cryptococcus (2.4%) each. Co-infection was identified in 20.7% (17/84) of the patients. Conclusion: Patients presenting with symptoms of meningitis had advanced HIV/AIDS, a quarter of whom had cerebral toxoplasmosis or infection with EBV. A high index of suspicion, laboratory exclusion of cryptococcal meningitis and prompt patient management with anti-toxoplasmosis empiric therapy may thus be required for optimal treatment.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/diagnóstico , Antifúngicos/uso terapêutico , Infecções por HIV/epidemiologia , Meningite Criptocócica/diagnóstico , Toxoplasmose Cerebral/diagnóstico , Infecções Oportunistas Relacionadas com a AIDS/tratamento farmacológico , Infecções Oportunistas Relacionadas com a AIDS/epidemiologia , Adulto , Contagem de Linfócito CD4 , Líquido Cefalorraquidiano/microbiologia , Estudos Transversais , Feminino , Gana/epidemiologia , Infecções por HIV/tratamento farmacológico , Infecções por HIV/microbiologia , Humanos , Masculino , Meningite Criptocócica/tratamento farmacológico , Meningite Criptocócica/epidemiologia , Análise de Sobrevida , Toxoplasmose Cerebral/tratamento farmacológico , Toxoplasmose Cerebral/epidemiologiaRESUMO
While conventional pathogenic protists have been extensively studied, there is an underappreciated constitutive protist microbiota that is an integral part of the vertebrate microbiome. The impact of these species on the host and their potential contributions to mucosal immune homeostasis remain poorly studied. Here, we show that the protozoan Tritrichomonas musculis activates the host epithelial inflammasome to induce IL-18 release. Epithelial-derived IL-18 promotes dendritic cell-driven Th1 and Th17 immunity and confers dramatic protection from mucosal bacterial infections. Along with its role as a "protistic" antibiotic, colonization with T. musculis exacerbates the development of T-cell-driven colitis and sporadic colorectal tumors. Our findings demonstrate a novel mutualistic host-protozoan interaction that increases mucosal host defenses at the cost of an increased risk of inflammatory disease.
Assuntos
Colite/imunologia , Colite/parasitologia , Interações Hospedeiro-Parasita , Inflamassomos/imunologia , Mucosa Intestinal/parasitologia , Microbiota/imunologia , Tricomoníase/imunologia , Trichomonas/imunologia , Animais , Colite/microbiologia , Dientamoeba/imunologia , Imunidade nas Mucosas , Interleucina-18/imunologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Simbiose , Células Th1/imunologia , Células Th17/imunologiaRESUMO
Our previous study demonstrated that CD8(+) T cells remove cysts of Toxoplasma gondii from the brain through perforin-mediated mechanisms. We here show that a transfer of CD8(+) immune T cells primed with a type II or a type III strain of T. gondii both efficiently removed cysts of a type II strain from infected SCID mice, although the former tended to be slightly more efficient than the latter. Similarly, a transfer of type II-primed CD8(+) T cells removed cysts of a type III strain. Therefore, CD8(+) T cells are capable of removing T. gondii cysts by recognizing epitopes commonly expressed in types II and III strains or cross-reactive between these two genotypes.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Reações Cruzadas , Epitopos de Linfócito T/imunologia , Toxoplasma/imunologia , Toxoplasmose Cerebral/imunologia , Transferência Adotiva , Animais , Encéfalo/imunologia , Encéfalo/patologia , Modelos Animais de Doenças , Feminino , Camundongos SCID , Toxoplasma/classificação , Toxoplasmose Cerebral/patologiaRESUMO
BACKGROUND: Oral infection of C57BL/6J mice with the protozoan parasite Toxoplasma gondii leads to a lethal inflammatory ileitis. PRINCIPAL FINDINGS: Mice lacking the purinergic receptor P2X7R are acutely susceptible to toxoplasmic ileitis, losing significantly more weight than C57BL/6J mice and exhibiting much greater intestinal inflammatory pathology in response to infection with only 10 cysts of T. gondii. This susceptibility is not dependent on the ability of P2X7R-deficient mice to control the parasite, which they accomplish just as efficiently as C57BL/6J mice. Rather, susceptibility is associated with elevated ileal concentrations of pro-inflammatory cytokines, reactive nitrogen intermediates and altered regulation of elements of NFκB activation in P2X7R-deficient mice. CONCLUSIONS: Our data support the thesis that P2X7R, a well-documented activator of pro-inflammatory cytokine production, also plays an important role in the regulation of intestinal inflammation.
Assuntos
Suscetibilidade a Doenças , Ileíte/genética , Ileíte/parasitologia , Receptores Purinérgicos P2X7/deficiência , Toxoplasma , Toxoplasmose Animal/genética , Toxoplasmose Animal/parasitologia , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Ileíte/metabolismo , Ileíte/patologia , Mediadores da Inflamação/metabolismo , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , Camundongos Knockout , NF-kappa B/metabolismo , Espécies Reativas de Nitrogênio/metabolismo , Toxoplasmose Animal/metabolismoRESUMO
UNLABELLED: Sarcocystis neurona is a member of the coccidia, a clade of single-celled parasites of medical and veterinary importance including Eimeria, Sarcocystis, Neospora, and Toxoplasma. Unlike Eimeria, a single-host enteric pathogen, Sarcocystis, Neospora, and Toxoplasma are two-host parasites that infect and produce infectious tissue cysts in a wide range of intermediate hosts. As a genus, Sarcocystis is one of the most successful protozoan parasites; all vertebrates, including birds, reptiles, fish, and mammals are hosts to at least one Sarcocystis species. Here we sequenced Sarcocystis neurona, the causal agent of fatal equine protozoal myeloencephalitis. The S. neurona genome is 127 Mbp, more than twice the size of other sequenced coccidian genomes. Comparative analyses identified conservation of the invasion machinery among the coccidia. However, many dense-granule and rhoptry kinase genes, responsible for altering host effector pathways in Toxoplasma and Neospora, are absent from S. neurona. Further, S. neurona has a divergent repertoire of SRS proteins, previously implicated in tissue cyst formation in Toxoplasma. Systems-based analyses identified a series of metabolic innovations, including the ability to exploit alternative sources of energy. Finally, we present an S. neurona model detailing conserved molecular innovations that promote the transition from a purely enteric lifestyle (Eimeria) to a heteroxenous parasite capable of infecting a wide range of intermediate hosts. IMPORTANCE: Sarcocystis neurona is a member of the coccidia, a clade of single-celled apicomplexan parasites responsible for major economic and health care burdens worldwide. A cousin of Plasmodium, Cryptosporidium, Theileria, and Eimeria, Sarcocystis is one of the most successful parasite genera; it is capable of infecting all vertebrates (fish, reptiles, birds, and mammals-including humans). The past decade has witnessed an increasing number of human outbreaks of clinical significance associated with acute sarcocystosis. Among Sarcocystis species, S. neurona has a wide host range and causes fatal encephalitis in horses, marine mammals, and several other mammals. To provide insights into the transition from a purely enteric parasite (e.g., Eimeria) to one that forms tissue cysts (Toxoplasma), we present the first genome sequence of S. neurona. Comparisons with other coccidian genomes highlight the molecular innovations that drive its distinct life cycle strategies.
Assuntos
Genoma de Protozoário , Sarcocystis/crescimento & desenvolvimento , Sarcocystis/genética , Sarcocistose/parasitologia , Sarcocistose/veterinária , Animais , Humanos , Estágios do Ciclo de Vida , Filogenia , Proteínas de Protozoários/genética , Sarcocystis/classificação , Sarcocystis/metabolismoRESUMO
PURPOSE: To determine the cytokine levels in aqueous humor (AH) of Colombian patients with active ocular toxoplasmosis (OT), and to correlate them with their clinical characteristics. METHODS: 27 Cytokines/chemokines were assayed in 15 AH samples (nine patients with diagnosis of OT biologically-confirmed and six controls that underwent cataract surgery). Correlations were assessed between cytokine/chemokine levels, type of inflammatory response (Th1, Th2, Th17, Treg), and clinical characteristics. RESULTS: Th2 predominant response was related to more severe clinical features. The presence of VEGF and IL-5 was related to higher number of recurrences. Growth factors (VEGF, FGF, PDGF-ß), were related to higher number of lesions. Patients infected by type-I/III strains had a particular intraocular cytokine-pattern. CONCLUSIONS: Th2 response was related to more severe clinical characteristics in patients infected by Type I/III strains. IL-5 and VEGF were associated with recurrences. We correlate for the first time, specific cytokine-patterns with clinical characteristics and with the infecting Toxoplasma strain.
Assuntos
Citocinas/metabolismo , Olho/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Toxoplasmose Ocular/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Humor Aquoso/metabolismo , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Estudos ProspectivosRESUMO
Toxoplasma gondii is an intracellular parasite that infects a wide range of warm-blooded species. Rats vary in their susceptibility to this parasite. The Toxo1 locus conferring Toxoplasma resistance in rats was previously mapped to a region of chromosome 10 containing Nlrp1. This gene encodes an inflammasome sensor controlling macrophage sensitivity to anthrax lethal toxin (LT) induced rapid cell death (pyroptosis). We show here that rat strain differences in Toxoplasma infected macrophage sensitivity to pyroptosis, IL-1ß/IL-18 processing, and inhibition of parasite proliferation are perfectly correlated with NLRP1 sequence, while inversely correlated with sensitivity to anthrax LT-induced cell death. Using recombinant inbred rats, SNP analyses and whole transcriptome gene expression studies, we narrowed the candidate genes for control of Toxoplasma-mediated rat macrophage pyroptosis to four genes, one of which was Nlrp1. Knockdown of Nlrp1 in pyroptosis-sensitive macrophages resulted in higher parasite replication and protection from cell death. Reciprocally, overexpression of the NLRP1 variant from Toxoplasma-sensitive macrophages in pyroptosis-resistant cells led to sensitization of these resistant macrophages. Our findings reveal Toxoplasma as a novel activator of the NLRP1 inflammasome in rat macrophages.
Assuntos
Inflamassomos/imunologia , Macrófagos/parasitologia , Proteínas do Tecido Nervoso/imunologia , Toxoplasmose/imunologia , Animais , Western Blotting , Modelos Animais de Doenças , Técnicas de Silenciamento de Genes , Predisposição Genética para Doença/genética , Inflamassomos/genética , Macrófagos/imunologia , Proteínas do Tecido Nervoso/genética , Análise de Sequência com Séries de Oligonucleotídeos , Polimorfismo de Nucleotídeo Único , Ratos , Ratos Endogâmicos , Toxoplasmose/genética , TranscriptomaRESUMO
BACKGROUND/AIMS: To determine if patients with inactive chorioretinitis lesions who experience chronic toxoplasmic uveitis test PCR positive for Toxoplasma in their ocular fluids. METHODS: Two patients undergoing long-term anti-toxoplasmic treatment developed chronic uveitis and vitritis. They underwent therapeutic and diagnostic pars plana vitrectomy. Patient specimens were tested for toxoplasmosis by real-time PCR and nested PCR. Patient specimens were also tested for the presence of Toxoplasma antibodies that recognise allelic peptide motifs to determine parasite serotype. RESULTS: Patients tested positive for Toxoplasma by real-time PCR at the B1 gene in the vitreous and aqueous humours of patient 1, but only the vitreous of patient 2. Patients were not parasitemic by real-time PCR in plasma and blood. During surgery, only old hyperpigmented toxoplasmic scars were observed; there was no sign of active retinitis. Multilocus PCR-DNA sequence genotyping at B1, NTS2 and SAG1 loci established that two different non-archetypal Toxoplasma strains had infected patients 1 and 2. A peptide-based serotyping ELISA confirmed the molecular findings. CONCLUSIONS: No active lesions were observed, but both patients possessed sufficient parasite DNA in their vitreous to permit genotyping. Several hypotheses to explain the persistence of the vitritis and anterior uveitis in the absence of active retinitis are discussed.
Assuntos
Anticorpos Antiprotozoários/sangue , Retinite/parasitologia , Toxoplasma/isolamento & purificação , Toxoplasmose Ocular/parasitologia , Uveíte/parasitologia , Corpo Vítreo/parasitologia , Anti-Infecciosos/uso terapêutico , Antiprotozoários/uso terapêutico , Doença Crônica , DNA de Protozoário , Ensaio de Imunoadsorção Enzimática , Feminino , Técnicas de Genotipagem , Glucocorticoides/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Prednisona/uso terapêutico , Reação em Cadeia da Polimerase em Tempo Real , Retinite/tratamento farmacológico , Retinite/imunologia , Sorotipagem , Toxoplasma/genética , Toxoplasma/imunologia , Toxoplasmose Ocular/tratamento farmacológico , Toxoplasmose Ocular/imunologia , Combinação Trimetoprima e Sulfametoxazol , Uveíte/tratamento farmacológico , Uveíte/imunologia , VitrectomiaRESUMO
UNLABELLED: Induction of immunity that limits Toxoplasma gondii infection in mice is critically dependent on the activation of the innate immune response. In this study, we investigated the role of cytoplasmic nucleotide-binding domain and leucine-rich repeat containing a pyrin domain (NLRP) inflammasome sensors during acute toxoplasmosis in mice. We show that in vitro Toxoplasma infection of murine bone marrow-derived macrophages activates the NLRP3 inflammasome, resulting in the rapid production and cleavage of interleukin-1ß (IL-1ß), with no measurable cleavage of IL-18 and no pyroptosis. Paradoxically, Toxoplasma-infected mice produced large quantities of IL-18 but had no measurable IL-1ß in their serum. Infection of mice deficient in NLRP3, caspase-1/11, IL-1R, or the inflammasome adaptor protein ASC led to decreased levels of circulating IL-18, increased parasite replication, and death. Interestingly, mice deficient in NLRP1 also displayed increased parasite loads and acute mortality. Using mice deficient in IL-18 and IL-18R, we show that this cytokine plays an important role in limiting parasite replication to promote murine survival. Our findings reveal T. gondii as a novel activator of the NLRP1 and NLRP3 inflammasomes in vivo and establish a role for these sensors in host resistance to toxoplasmosis. IMPORTANCE: Inflammasomes are multiprotein complexes that are a major component of the innate immune system. They contain "sensor" proteins that are responsible for detecting various microbial and environmental danger signals and function by activating caspase-1, an enzyme that mediates cleavage and release of the proinflammatory cytokines interleukin-1ß (IL-1ß) and IL-18. Toxoplasma gondii is a highly successful protozoan parasite capable of infecting a wide range of host species that have variable levels of resistance. We report here that T. gondii is a novel activator of the NLRP1 and NLRP3 inflammasomes in vivo and establish a role for these sensors in host resistance to toxoplasmosis. Using mice deficient in IL-18 and IL-18R, we show that the IL-18 cytokine plays a pivotal role by limiting parasite replication to promote murine survival.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/imunologia , Proteínas Reguladoras de Apoptose/imunologia , Proteínas de Transporte/imunologia , Resistência à Doença , Inflamassomos/imunologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Proteínas Adaptadoras de Transdução de Sinal/deficiência , Animais , Proteínas Reguladoras de Apoptose/deficiência , Proteínas de Transporte/genética , Feminino , Macrófagos/imunologia , Macrófagos/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR , Carga Parasitária , Análise de SobrevidaRESUMO
In a cross sectional study, 19 French and 23 Colombian cases of confirmed active ocular toxoplasmosis (OT) were evaluated. The objective was to compare clinical, parasitological and immunological responses and relate them to the infecting strains. A complete ocular examination was performed in each patient. The infecting strain was characterized by genotyping when intraocular Toxoplasma DNA was detectable, as well as by peptide-specific serotyping for each patient. To characterize the immune response, we assessed Toxoplasma protein recognition patterns by intraocular antibodies and the intraocular profile of cytokines, chemokines and growth factors. Significant differences were found for size of active lesions, unilateral macular involvement, unilateral visual impairment, vitreous inflammation, synechiae, and vasculitis, with higher values observed throughout for Colombian patients. Multilocus PCR-DNA sequence genotyping was only successful in three Colombian patients revealing one type I and two atypical strains. The Colombian OT patients possessed heterogeneous atypical serotypes whereas the French were uniformly reactive to type II strain peptides. The protein patterns recognized by intraocular antibodies and the cytokine patterns were strikingly different between the two populations. Intraocular IFN-γ and IL-17 expression was lower, while higher levels of IL-13 and IL-6 were detected in aqueous humor of Colombian patients. Our results are consistent with the hypothesis that South American strains may cause more severe OT due to an inhibition of the protective effect of IFN-γ.
Assuntos
Olho/patologia , Interferon gama/análise , Interleucina-13/análise , Interleucina-17/análise , Interleucina-6/análise , Toxoplasma/isolamento & purificação , Toxoplasmose Ocular/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , DNA de Protozoário/genética , Olho/imunologia , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Tipagem de Sequências Multilocus , Reação em Cadeia da Polimerase , Toxoplasma/classificação , Toxoplasma/genética , Toxoplasmose Ocular/imunologia , Adulto JovemRESUMO
Routine fecal examination revealed novel coccidian oocysts in asymptomatic California sea lions (Zalophus californianus) in a rehabilitation facility. Coccidian oocysts were observed in fecal samples collected from 15 of 410 California sea lions admitted to The Marine Mammal Center between April 2007 and October 2009. Phylogenetic analysis using the full ITS-1 region, partial small subunit 18S rDNA sequence, and the Apicomplexa rpoB region identified 2 distinct sequence clades, referred to as Coccidia A and Coccidia B, and placed them in the Sarcocystidae, grouped with the tissue-cyst-forming coccidia. Both sequence clades resolved as individual taxa at ITS-1 and rpoB and were most closely related to Neospora caninum. Coccidia A was identified in 11 and Coccidia B in 4 of 12 sea lion oocyst samples successfully sequenced (3 of those sea lions were co-infected with both parasites). Shedding of Coccidia A oocysts was not associated with age class, sex, or stranding location, but yearlings represented the majority of shedders (8/15). This is the first study to use molecular phylogenetics to identify and describe coccidian parasites shed by a marine mammal.
Assuntos
Coccídios/classificação , Coccidiose/veterinária , Leões-Marinhos/parasitologia , Animais , California/epidemiologia , Coccídios/genética , Coccídios/isolamento & purificação , Coccidiose/epidemiologia , Coccidiose/parasitologia , DNA de Protozoário/química , DNA Ribossômico/química , DNA Espaçador Ribossômico/química , Fezes/parasitologia , Feminino , Masculino , Dados de Sequência Molecular , Filogenia , Prevalência , Proteínas de Protozoários/genética , RNA Ribossômico 18S/genética , Fatores de Risco , Estações do Ano , Alinhamento de Sequência/veterináriaRESUMO
In 1995, one of the largest outbreaks of human toxoplasmosis occurred in the Pacific Northwest region of North America. Genetic typing identified a novel Toxoplasma gondii strain linked to the outbreak, in which a wide spectrum of human disease was observed. For this globally-distributed, water-borne zoonosis, strain type is one variable influencing disease, but the inability of strain type to consistently explain variations in disease severity suggests that parasite genotype alone does not determine the outcome of infection. We investigated polyparasitism (infection with multiple parasite species) as a modulator of disease severity by examining the association of concomitant infection of T. gondii and the related parasite Sarcocystis neurona with protozoal disease in wild marine mammals from the Pacific Northwest. These hosts ostensibly serve as sentinels for the detection of terrestrial parasites implicated in water-borne epidemics of humans and wildlife in this endemic region. Marine mammals (151 stranded and 10 healthy individuals) sampled over 6 years were assessed for protozoal infection using multi-locus PCR-DNA sequencing directly from host tissues. Genetic analyses uncovered a high prevalence and diversity of protozoa, with 147/161 (91%) of our sampled population infected. From 2004 to 2009, the relative frequency of S. neurona infections increased dramatically, surpassing that of T. gondii. The majority of T. gondii infections were by genotypes bearing Type I lineage alleles, though strain genotype was not associated with disease severity. Significantly, polyparasitism with S. neurona and T. gondii was common (42%) and was associated with higher mortality and more severe protozoal encephalitis. Our finding of widespread polyparasitism among marine mammals indicates pervasive contamination of waterways by zoonotic agents. Furthermore, the significant association of concomitant infection with mortality and protozoal encephalitis identifies polyparasitism as an important factor contributing to disease severity in marine mammals.