RESUMO
Gender inequality in STEM fields remains pervasive and undermines the ability for talented individuals to excel. Despite advances, women still encounter obstacles in pursuing academic careers and reaching leadership positions. This commentary discusses the "scissor-shaped curve" and examines effective strategies to fix it, including data-driven initiatives that we have implemented at our university.
Assuntos
Academia , Equidade de Gênero , Humanos , Feminino , Liderança , UniversidadesRESUMO
Host resistance to Leishmania major is highly dependent on the development of a Th1 immune response. The TLR adaptator myeloid differentiation protein 88 (MyD88) has been implicated in the Th1 immune response associated with the resistant phenotype observed in C57BL/6 mice after infection with L. major. To investigate whether the MyD88 pathway is differentially used by distinct substrains of parasites, MyD88(-/-) C57BL/6 mice were infected with two substrains of L. major, namely L. major LV39 and L. major IR75. MyD88(-/-) mice were susceptible to both substrains of L. major, although with different kinetics of infection. The mechanisms involved during the immune response associated with susceptibility of MyD88(-/-) mice to L. major is however, parasite substrain-dependent. Susceptibility of MyD88(-/-) mice infected with L. major IR75 is a consequence of Th2 immune-deviation, whereas susceptibility of MyD88(-/-) mice to infection with L. major LV39 resulted from an impaired Th1 response. Depletion of regulatory T cells (Treg) partially restored IFN-gamma secretion and the Th1 immune response in MyD88(-/-) mice infected with L. major LV39, demonstrating a role of Treg activity in the development of an impaired Th1 response in these mice.
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Leishmaniose Cutânea/imunologia , Fator 88 de Diferenciação Mieloide/imunologia , Transdução de Sinais/imunologia , Subpopulações de Linfócitos T/imunologia , Animais , Citocinas/biossíntese , Suscetibilidade a Doenças/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Leishmania major/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
The gene encoding type I signal peptidase (Lmjsp) has been cloned from Leishmania major. Lmjsp encodes a protein of 180 amino residues with a predicted molecular mass of 20.5 kDa. Comparison of the protein sequence with those of known type I signal peptidases indicates homology in five conserved domains A-E which are known to be important, or essential, for catalytic activity. Southern blot hybridisation analysis indicates that there is a single copy of the Lmjsp gene. A recombinant SPase protein and a synthetic peptide of the L. major signal peptidase were used to examine the presence of specific antibodies in sera from either recovered or active individuals of both cutaneous and visceral leishmaniasis. This evaluation demonstrated that sera from cutaneous and visceral forms of leishmaniasis are highly reactive to both the recombinant and synthetic signal peptidase antigens. Therefore, the Leishmania signal peptidase, albeit localised intracellularly, is a significant target of the Leishmania specific immune response and highlights its potential use for serodiagnosis of cutaneous and visceral leishmaniasis.
Assuntos
Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Leishmaniose Visceral/imunologia , Proteínas de Membrana/imunologia , Serina Endopeptidases/imunologia , Adolescente , Sequência de Aminoácidos , Animais , Anticorpos Antiprotozoários/sangue , Domínio Catalítico , Criança , Pré-Escolar , Clonagem Molecular , DNA de Protozoário/química , DNA de Protozoário/isolamento & purificação , Dosagem de Genes , Genes de Protozoários , Humanos , Lactente , Leishmania major/genética , Leishmania major/metabolismo , Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/parasitologia , Leishmaniose Visceral/diagnóstico , Leishmaniose Visceral/parasitologia , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Dados de Sequência Molecular , Peso Molecular , Fases de Leitura Aberta , Estrutura Terciária de Proteína , Alinhamento de Sequência , Análise de Sequência de DNA , Serina Endopeptidases/biossíntese , Serina Endopeptidases/genéticaRESUMO
Histone H1 in the parasitic protozoan Leishmania is a developmentally regulated protein encoded by two genes, HIS-1.1 and HIS-1.2. These genes are separated by approximately 20 kb of sequence and are located on the same DNA strand of chromosome 27. When Northern blots of parasite RNA were probed with HIS-1 strand-specific riboprobes, we detected sense and antisense transcripts that were polyadenylated and developmentally regulated. When the HIS-1.2 coding region was replaced with the coding region of the neomycin phosphotransferase gene, antisense transcription of this gene was unaffected, indicating that the regulatory elements controlling antisense transcription were located outside of the HIS-1.2 gene, and that transcription in Leishmania can occur from both DNA strands even in the presence of transcription of a selectable marker in the complementary strand. A search for other antisense transcripts within the HIS-1 locus identified an additional transcript (SC-1) within the intervening HIS-1 sequence, downstream of adenine and thymine-rich sequences. These results show that gene expression in Leishmania is not only regulated polycistronically from the sense strand of genomic DNA, but that the complementary strand of DNA also contains sequences that could drive expression of open reading frames from the antisense strand of DNA. These findings suggest that the parasite has evolved in such a way as to maximise the transcription of its genome, a mechanism that might be important for it to maintain virulence.
Assuntos
DNA Antissenso/análise , DNA Complementar/análise , Histonas/genética , Leishmania major/genética , Leishmaniose Cutânea/transmissão , Animais , Northern Blotting/métodos , Humanos , Reação em Cadeia da Polimerase/métodos , Transcrição Gênica , VirulênciaRESUMO
Infections with Leishmania parasites of the Leishmania Viannia subgenus give rise to both localized cutaneous (CL), and metastatic leishmaniasis. Metastasizing disease forms including disseminated (DCL) and mutocutaneous (MCL) leishmaniasis result from parasitic dissemination and lesion formation at sites distal to infection and have increased inflammatory responses. The presence of Leishmania RNA virus (LRV) in L. guyanensis parasites contributes to the exacerbation of disease and impacts inflammatory responses via activation of TLR3 by the viral dsRNA. In this study we investigated other innate immune response adaptor protein modulators and demonstrated that both MyD88 and TLR9 played a crucial role in the development of Th1-dependent healing responses against L. guyanensis parasites regardless of their LRV status. The absence of MyD88- or TLR9-dependent signaling pathways resulted in increased Th2 associated cytokines (IL-4 and IL-13), which was correlated with low transcript levels of IL-12p40. The reliance of IL-12 was further confirmed in IL12AB-/- mice, which were completely susceptible to infection. Protection to L. guyanensis infection driven by MyD88- and TLR9-dependent immune responses arises independently to those induced due to high LRV burden within the parasites.
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Imunidade Inata , Leishmania guyanensis/virologia , Fator 88 de Diferenciação Mieloide/metabolismo , Vírus de RNA/fisiologia , Receptor Toll-Like 9/metabolismo , Animais , Suscetibilidade a Doenças , Subunidade p35 da Interleucina-12/deficiência , Subunidade p35 da Interleucina-12/genética , Subunidade p35 da Interleucina-12/metabolismo , Subunidade p40 da Interleucina-12/deficiência , Subunidade p40 da Interleucina-12/genética , Subunidade p40 da Interleucina-12/metabolismo , Interleucina-13/metabolismo , Interleucina-4/metabolismo , Leishmania guyanensis/fisiologia , Leishmaniose Mucocutânea/imunologia , Leishmaniose Mucocutânea/patologia , Leishmaniose Mucocutânea/veterinária , Linfonodos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/deficiência , Fator 88 de Diferenciação Mieloide/genética , Transdução de Sinais , Células Th1/imunologia , Células Th1/metabolismo , Células Th2/imunologia , Células Th2/metabolismo , Receptor Toll-Like 9/deficiência , Receptor Toll-Like 9/genéticaRESUMO
Mucocutaneous leishmaniasis is caused by infections with intracellular parasites of the Leishmania Viannia subgenus, including Leishmania guyanensis. The pathology develops after parasite dissemination to nasopharyngeal tissues, where destructive metastatic lesions form with chronic inflammation. Currently, the mechanisms involved in lesion development are poorly understood. Here we show that metastasizing parasites have a high Leishmania RNA virus-1 (LRV1) burden that is recognized by the host Toll-like receptor 3 (TLR3) to induce proinflammatory cytokines and chemokines. Paradoxically, these TLR3-mediated immune responses rendered mice more susceptible to infection, and the animals developed an increased footpad swelling and parasitemia. Thus, LRV1 in the metastasizing parasites subverted the host immune response to Leishmania and promoted parasite persistence.
Assuntos
Quimiocinas/metabolismo , Citocinas/metabolismo , Leishmania guyanensis/patogenicidade , Leishmania guyanensis/virologia , Leishmaniose Mucocutânea/imunologia , Leishmaniavirus/imunologia , Receptor 3 Toll-Like/imunologia , Animais , Mediadores da Inflamação/metabolismo , Leishmaniose Mucocutânea/parasitologia , Leishmaniavirus/fisiologia , Macrófagos/imunologia , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Parasitemia , Fagossomos/parasitologia , RNA de Cadeia Dupla/imunologia , RNA Viral/imunologia , Receptores Toll-Like/imunologiaRESUMO
BACKGROUND: DC are activated by pathogen-associated molecular patterns (PAMPs), and this is pivotal for the induction of adaptive immune responses. Thereafter, the clearance of activated DC is crucial to prevent immune pathology. While PAMPs are of major interest for vaccine science due to their adjuvant potential, it is unclear whether and how PAMPs may affect DC viability. We aimed to elucidate the possible apoptotic mechanisms that control activated DC lifespan in response to PAMPs, particularly in vivo. METHODOLOGY/PRINCIPAL FINDINGS: We report that polyinosinic:polycytidylic acid (PolyIC, synthetic analogue of dsRNA) induces dramatic apoptosis of mouse splenic conventional DC (cDC) in vivo, predominantly affecting the CD8α subset, as shown by flow cytometry-based analysis of splenic DC subsets. Importantly, while Bim deficiency conferred only minor protection, cDC depletion was prevented in mice lacking Bim plus one of three other BH3-only proteins, either Puma, Noxa or Bid. Furthermore, we show that Type I Interferon (IFN) is necessary and sufficient for DC death both in vitro and in vivo, and that TLR3 and MAVS co-operate in IFNß production in vivo to induce DC death in response to PolyIC. CONCLUSIONS/SIGNIFICANCE: These results demonstrate for the first time in vivo that apoptosis restricts DC lifespan following activation by PolyIC, particularly affecting the CD8α cDC subset. Such DC apoptosis is mediated by the overlapping action of pro-apoptotic BH3-only proteins, including but not solely involving Bim, and is driven by Type I IFN. While Type I IFNs are important anti-viral factors, CD8α cDC are major cross-presenting cells and critical inducers of CTL. We discuss such paradoxical finding on DC death with PolyIC/Type I IFN. These results could contribute to understand immunosuppression associated with chronic infection, and to the optimization of DC-based therapies and the clinical use of PAMPs and Type I IFNs.
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Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/efeitos dos fármacos , Células Dendríticas/citologia , Células Dendríticas/efeitos dos fármacos , Interferon Tipo I/farmacologia , Poli I-C/farmacologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Antígenos CD8/metabolismo , Contagem de Células , Células Dendríticas/metabolismo , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Interferon Tipo I/biossíntese , Interferon beta/biossíntese , Interferon beta/farmacologia , Leishmania/fisiologia , Ligantes , Masculino , Camundongos , Baço/imunologia , Receptor 3 Toll-Like/metabolismoRESUMO
We investigated the functional role of the Leishmania histone H1 and demonstrate for the first time that addition of histone H1 has a strong effect on microccocal digestion, chromatin condensation of parasite nuclei and that its overexpression can modulate parasite infectivity in vivo.
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Cromatina/metabolismo , Histonas/fisiologia , Leishmania major/fisiologia , Leishmaniose Cutânea/parasitologia , Animais , Linhagem Celular , Expressão Gênica , Histonas/genética , Leishmania major/química , Leishmania major/patogenicidade , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Transdução de Sinais , Transfecção , VirulênciaRESUMO
Mucocutaneous leishmaniasis (MCL) in South and Central America is characterized by the dissemination (metastasis) of Leishmania Viannia subgenus parasites from a cutaneous lesion to nasopharyngeal tissues. Little is known about the pathogenesis of MCL, especially with regard to the virulence of the parasites and the process of metastatic dissemination. We previously examined the functional relationship between cytoplasmic peroxiredoxin and metastatic phenotype using highly, infrequently, and nonmetastatic clones isolated from an L. (V.) guyanensis strain previously shown to be highly metastatic in golden hamsters. Distinct forms of cytoplasmic peroxiredoxin were identified and found to be associated with the metastatic phenotype. We report here that peroxidase activity in the presence of hydrogen peroxide and infectivity differs between metastatic and nonmetastatic L. (V.) guyanensis clones. After hydrogen peroxide treatment or heat shock, peroxiredoxin was detected preferentially as dimers in metastatic L. (V.) guyanensis clones and in L. (V.) panamensis strains from patients with MCL, compared with nonmetastatic parasites. These data provide evidence that resistance to the first microbicidal response of the host cell by Leishmania promastigotes is linked to peroxiredoxin conformation and may be relevant to intracellular survival and persistence, which are prerequisites for the development of metastatic disease.
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Resistência a Medicamentos/genética , Leishmania/genética , Leishmania/patogenicidade , Leishmaniose Mucocutânea/parasitologia , Sequência de Aminoácidos , Animais , Cricetinae , DNA/análise , Leishmaniose Mucocutânea/patologia , Mesocricetus , Dados de Sequência Molecular , NADP/farmacologia , Estresse Oxidativo , Peroxidases/genética , Peroxirredoxinas , Reação em Cadeia da Polimerase , Espécies Reativas de Oxigênio/farmacologia , Alinhamento de Sequência , Índice de Gravidade de DoençaRESUMO
Infection with Leishmania major parasites results in the development of cutaneous ulcerative lesions on the skin. We investigated the protective potential of a single, recombinant histone H1 antigen against cutaneous leishmaniasis in an outbred population of vervet monkeys, using Montanide adjuvant. Protection was assessed by challenging the animals with a mixture of vector sand fly salivary-gland lysate and a low dose of in vitro-derived parasites, thus more closely mimicking natural infection induced by L. major. The course of infection in immunized monkeys was compared with that of animals that had healed from a primary infection and were immune. The monkeys immunized with recombinant histone H1 showed a reduced development of lesion size, compared with controls. Our study therefore illustrates the potential use of histone H1 as a vaccine candidate against cutaneous leishmaniasis in humans.
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Adjuvantes Imunológicos , Chlorocebus aethiops , Modelos Animais de Doenças , Histonas/imunologia , Leishmaniose Cutânea/prevenção & controle , Vacinas Protozoárias/imunologia , Animais , Animais não Endogâmicos , Anticorpos Antiprotozoários/sangue , Histonas/administração & dosagem , Histonas/genética , Humanos , Hipersensibilidade Tardia , Leishmania major/patogenicidade , Leishmaniose Cutânea/parasitologia , Vacinas Protozoárias/administração & dosagem , Psychodidae/parasitologia , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , VacinaçãoRESUMO
Several different sample preparation methods for two-dimensional electrophoresis (2-DE) analysis of Leishmania parasites were compared. From this work, we were able to identify a solubilization method using Nonidet P-40 as detergent, which was simple to follow, and which produced 2-DE gels of high resolution and reproducibility.
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Eletroforese em Gel Bidimensional/métodos , Leishmania/química , Proteoma/química , Proteínas de Protozoários/análise , Animais , Leishmania/genética , Peso MolecularRESUMO
In this study, the mature domains of type I (CPB) and type II (CPA) cysteine proteinases (CPs) of Leishmania infantum were expressed and their immunogenic properties defined using sera from active and recovered cases of human visceral leishmaniasis and sera from infected dogs. Immunoblotting and ELISA analysis indicated that a freeze/thaw extract of parasite antigens showed similar and intensive recognition in both active cases of human and dog sera but lower recognition in recovered human individuals. The total IgG of actively infected human sera was higher than in recovered cases when rCPs were used as antigen. In contrast to dog sera, both active and recovered human cases have higher recognition toward rCPB than rCPA. Furthermore, the asymptomatic dogs in contrast to the symptomatic cases exhibited specific lymphocyte proliferation to both crude antigens and rCPs.