Phagocytosis of Leptospira by leukocytes from mice with different susceptibility to leptospirosis and possible role of chemokines.

BACKGROUND: Leptospirosis is a widespread zoonosis caused by pathogenic prokaryotic microbes of the genus Leptospira. Although there are several reports in the literature, host-pathogen interaction is still poorly understood. The role of chemokine expression is important on the chemotaxis, activation and regulation of immune cells. Recent studies have shown that their expression profiles play an important role on the severity of leptospirosis outcome. We evaluated the phagocytosis of Leptospira by spleens cells from C3H/HeJ, C3H/HePas and BALB/c mouse strains, respectively susceptible, intermediate and resistant to leptospirosis, and by RAW 264.7 macrophages. Besides, we evaluated the effects of CCL2 treatment on the phagocytosis. The cells were incubated with or without CCL2 chemokine, and infected with virulent L. interrogans sv Copenhageni. Cells and culture supernatants were collected for subsequent analysis. RESULTS: The number of leptospires was higher in BALB/c cells, CCL2 pre-treated or only infected groups, when compared to C3H/HeJ and C3H/HePas cells. Indeed, CCL2 activation did not interfere in the phagocytosis of Leptospira. Expression of chemokines CXCL5 and CCL8 levels were significantly inhibited in infected BALB/c cells when compared to the non-infected control. CONCLUSIONS: Higher ability to phagocytosis and early modulation of some chemokines correlated with the resistance to leptospirosis disease. Exposure to CCL2 did not interfere on phagocytosis of Leptospira in our experimental conditions, but acted in the modulation of chemokines expression during Leptospira infection.

Phagocytosis of Leptospira by leukocytes from mice with different susceptibility to leptospirosis and possible role of chemokines

Background: Leptospirosis is a widespread zoonosis caused by pathogenic prokaryotic microbes of the genus Leptospira. Although there are several reports in the literature, host-pathogen interaction is still poorly understood. The role of chemokine expression is important on the chemotaxis, activation and regulation of immune cells. Recent studies have shown that their expression profiles play an important role on the severity of leptospirosis outcome. We evaluated the phagocytosis of Leptospira by spleens cells from C3H/HeJ, C3H/HePas and BALB/c mouse strains, respectively susceptible, intermediate and resistant to leptospirosis, and by RAW 264.7 macrophages. Besides, we evaluated the effects of CCL2 treatment on the phagocytosis. The cells were incubated with or without CCL2 chemokine, and infected with virulent L. interrogans sv Copenhageni. Cells and culture supernatants were collected for subsequent analysis. Results: The number of leptospires was higher in BALB/c cells, CCL2 pre-treated or only infected groups, when compared to C3H/HeJ and C3H/HePas cells. Indeed, CCL2 activation did not interfere in the phagocytosis of Leptospira. Expression of chemokines CXCL5 and CCL8 levels were significantly inhibited in infected BALB/c cells when compared to the non-infected control. Conclusions: Higher ability to phagocytosis and early modulation of some chemokines correlated with the resistance to leptospirosis disease. Exposure to CCL2 did not interfere on phagocytosis of Leptospira in our experimental conditions, but acted in the modulation of chemokines expression during Leptospira infection.

Decoding resistant hypertension signalling pathways.

Resistant hypertension (RH) is a clinical condition in which the hypertensive patient has become resistant to drug therapy and is often associated with increased cardiovascular morbidity and mortality. Several signalling pathways have been studied and related to the development and progression of RH: modulation of sympathetic activity by leptin and aldosterone, primary aldosteronism, arterial stiffness, endothelial dysfunction and variations in the renin-angiotensin-aldosterone system (RAAS). miRNAs comprise a family of small non-coding RNAs that participate in the regulation of gene expression at post-transcriptional level. miRNAs are involved in the development of both cardiovascular damage and hypertension. Little is known of the molecular mechanisms that lead to development and progression of this condition. This review aims to cover the potential roles of miRNAs in the mechanisms associated with the development and consequences of RH, and explore the current state of the art of diagnostic and therapeutic tools based on miRNA approaches.

Adhesin activity of Leptospira interrogans lipoprotein identified by in vivo and in vitro shotgun phage display.

Leptospira interrogans causes leptospirosis, one of the most common zoonotic diseases in the world. This pathogenic spirochete is able to bind to extracellular matrix, to express virulent factors and to cause host death. Until now, there is no effective human vaccine for the disease. Shotgun phage display genomic libraries of L. interrogans were constructed and used for in vivo biopanning in hamsters and screened for ligands able to bind to LLC-PK1 epithelial cells. In both panning procedures, clones coding for the putative lipoprotein LIC12976 were identified and, in order to confirm its adhesin activity, a recombinant protein was produced in Escherichia coli and showed to interact with A31 fibroblasts, LLC-PK1 and Vero epithelial cells in vitro. Moreover, rLIC12976 was shown to bind to laminin, indicating an adhesin function. This protein was also detected in extracts of L. interrogans from different serovars and it was found to be conserved among pathogenic leptospires. Further, the protein was tested as vaccine candidate and immunization of hamsters with LIC12976 did not confer protection against a lethal challenge with the homologous L. interrogans serovar Copenhageni. Nevertheless, LIC12976 seems to act as an adhesin, and may be important for the host-pathogen interaction, so that its study can contribute to the understanding of the virulence mechanisms in pathogenic leptospires.

Identificação de adesinas de Leptospira interrogans por shotgun phage display / Identification of Leptospira interrogans adhesins by shotgun phage display

Em Leptospira interrogans algumas proteínas com capacidade de ligação aos componentes de matriz extracelular foram identificadas e, em sua maioria, são fatores de virulência. Phage display é considerada uma técnica poderosa na identificação de novos ligantes, inclusive de moléculas adesinas, importantes no primeiro estágio de infecção do hospedeiro. A técnica de shotgun phage display foi utilizada visando à obtenção de ligantes à células de mamíferos. Quatro bibliotecas, por inserção de fragmentos aleatórios obtidos por sonicação do DNA de L. interrogans nos fagomídeos pG8SAET (BBT1 e BBT2) e pG3DSS (BBT5 e BBT6), foram construídas. As bibliotecas BBT1 e BBT5 contém insertos maiores e as BBT2 e BBT6 contém insertos menores, com tamanhos médios de 1500 pb e 350 pb, respectivamente. Após ensaio de panning da BBT5 contra células de mamíferos e soro fetal bovino, as sequências de clones selecionados foram analisadas quanto a orientação correta e se a fusão estava em fase com a proteína pIII. As proteínas codificadas pelos genes LIC11719, LIC10769, LIC13143 e LIC12976 foram selecionadas com estas características. Os genes que codificam a LIC12976, LIC10768, LIC10769 e LIC13418, tiveram sua conservação avaliada em diferentes sorovares da espécie patogênica L. interrogans e no sorovar Patoc da espécie de vida livre L. biflexa. As proteínas LIC12976 (selecionada pela técnica de phage display) e LIC13418 (selecionada por ferramentas de bioinformática) tiveram suas sequências amplificadas por PCR, clonadas em pGEM T easy, subclonadas em vetor de expressão pAE e expressas na fração celular correspondente ao corpúsculo de inclusão em E. coli BL21 (DE3) Star pLysS e E. coli BL21 SI, respectivamente. Após renaturação e purificação destas proteínas por cromatografia de afinidade a metal bivalente, um grupo de cinco animais BALB/c fêmeas foi imunizado. Ambas as proteínas se mostraram imunogênicas com títulos dos soros policlonais 1:256000 e 1:512000, respectivamente. Em ensaio de Western Blot os soros foram específicos no reconhecimento das proteínas recombinantes e as proteínas nativas foram verificadas em extratos de sorovares patogênicos de L. interrogans. Em ensaios de adesão, as proteínas recombinantes aderiram às células A31, LLC-PK1 e Vero e especificamente à laminina. Em ensaios de interferência em células usando laminina houve um aumento da adesão das proteínas recombinantes, o que pode ser explicado pela ligação da laminina às células e uma maior ligação das LICs estudadas. Em ensaio de localização celular usando imunofluorescência e microscopia eletrônica, foi observado que ambas as proteínas se encontram na superfície da L. interrogans. No experimento de desafio animal, a LIC12976 e a LIC13418 não se mostraram protetoras. Este trabalho contribuiu para a identificação das novas adesinas LIC13418 e LIC12976 que podem participar da virulência de leptospiras patogênicas envolvendo a primeira etapa da infecção na interação patógeno-hospedeiro

In Leptospira interrogans, proteins capable to bind to extracellular matrix components have been identified and most of them are important virulence factors. Phage display is a powerful technique to identify new ligands, including adhesin molecules that are important in the first stage of host infection. A shotgun phage display technique was used in order to obtain cell ligands. Four libraries were constructed by inserting random fragments obtained by sonication of L. interrogans DNA into phagemids pG8SAET (BBT1 and BBT2) and pG3DSS (BBT5 and BBT6). The libraries BBT1 and BBT5 contain larger inserts and BBT2 and BBT6 contain smaller inserts, with 1500 bp and 350 bp average sizes, respectively. After panning of BBT5 against mammalian cells and bovine fetal serum, the sequences of selected clones were analyzed for correct orientation and fusion with pIII protein. The proteins encoded by genes LIC11719, LIC10769, LIC13143 and LIC12976 were selected. The genes LIC12976, LIC10768, LIC10769 and LIC13418 were evaluated for their conservation in different pathogenic serovars of L. interrogans and free-living L. biflexa serovar Patoc. Proteins LIC12976 (selected by phage display technique) and also LIC13418 that was selected by bioinformatic tools, were amplified by PCR, cloned into pGEM T easy, subcloned into expression vector pAE and expressed in cellular fraction corresponding to the inclusion body in E. coli BL21 (DE3) Star pLysS and E. coli BL21 SI, respectively. After protein renaturation protocol and purification by affinity chromatography, a group of five BALB/c mice was immunized with the purified proteins. Both proteins were shown to be immunogenic with 1:256000 and 1:512000 polyclonal sera titers, respectively. In Western blot the sera were specific to recognize recombinant proteins and native proteins were detected in pathogenic L. interrogans serovars extracts. In binding assays, recombinant proteins bind to A31, LLC-PK1 and Vero cells and specifically to laminin. In interference cell assay using laminin there was an increase of recombinant protein bindings, which can be explained by the laminin binding to cells and further binding of the recombinant LICs. In cellular localization assay using immunofluorescence and electron microscopy, it was observed that both are surface proteins of L. interrogans. In the animal challenge, the LIC12976 and LIC13418 were not protective. As a whole, this work contributed to the identification of LIC12976 and LIC13418 as new adhesins and they can participate in the virulence of pathogenic Leptospira in the first stage of host pathogen interaction.

Leptospira interrogans shotgun phage display identified LigB as a heparin-binding protein.

LigB is an adhesin from pathogenic Leptospira that is able to bind to extracellular matrix and is considered a virulence factor. A shotgun phage display genomic library was constructed and used for panning against Heparan Sulfate Proteoglycan (HSPG). A phage clone encoding part of LigB protein was selected in panning experiments and showed specific binding to heparin. To validate the selected clone, fragments of LigB were produced as recombinant proteins and showed affinity to heparin and to mammalian cells. Heparin was also able to reduce the binding of rLB-Ct to mammalian cells. Our data suggests that the glycosaminoglycan moiety of the HSPG is responsible for its binding and could mediate the attachment of the recombinant protein rLB-Ct. Thus, heparin may act as a receptor for Leptospira to colonize and to invade the host tissue.

Identificação de adesinas de Leptospira interrogans por shotgun phage display / Identification of Leptospira interrogans adhesins by shotgun phage display

Em Leptospira interrogans algumas proteínas com capacidade de ligação aos componentes de matriz extracelular foram identificadas e, em sua maioria, são fatores de virulência. Phage display é considerada uma técnica poderosa na identificação de novos ligantes, inclusive de moléculas adesinas, importantes no primeiro estágio de infecção do hospedeiro. A técnica de shotgun phage display foi utilizada visando à obtenção de ligantes à células de mamíferos. Quatro bibliotecas, por inserção de fragmentos aleatórios obtidos por sonicação do DNA de L. interrogans nos fagomídeos pG8SAET (BBT1 e BBT2) e pG3DSS (BBT5 e BBT6), foram construídas. As bibliotecas BBT1 e BBT5 contém insertos maiores e as BBT2 e BBT6 contém insertos menores, com tamanhos médios de 1500 pb e 350 pb, respectivamente. Após ensaio de panning da BBT5 contra células de mamíferos e soro fetal bovino, as sequências de clones selecionados foram analisadas quanto a orientação correta e se a fusão estava em fase com a proteína pIII. As proteínas codificadas pelos genes LIC11719, LIC10769, LIC13143 e LIC12976 foram selecionadas com estas características. Os genes que codificam a LIC12976, LIC10768, LIC10769 e LIC13418, tiveram sua conservação avaliada em diferentes sorovares da espécie patogênica L. interrogans e no sorovar Patoc da espécie de vida livre L. biflexa. As proteínas LIC12976 (selecionada pela técnica de phage display) e LIC13418 (selecionada por ferramentas de bioinformática) tiveram suas sequências amplificadas por PCR, clonadas em pGEM T easy, subclonadas em vetor de expressão pAE e expressas na fração celular correspondente ao corpúsculo de inclusão em E. coli BL21 (DE3) Star pLysS e E. coli BL21 SI, respectivamente. Após renaturação e purificação destas proteínas por cromatografia de afinidade a metal bivalente, um grupo de cinco animais BALB/c fêmeas foi imunizado. Ambas as proteínas se mostraram imunogênicas com títulos dos soros policlonais 1:256000 e 1:512000, respectivamente...

In Leptospira interrogans, proteins capable to bind to extracellular matrix components have been identified and most of them are important virulence factors. Phage display is a powerful technique to identify new ligands, including adhesin molecules that are important in the first stage of host infection. A shotgun phage display technique was used in order to obtain cell ligands. Four libraries were constructed by inserting random fragments obtained by sonication of L. interrogans DNA into phagemids pG8SAET (BBT1 and BBT2) and pG3DSS (BBT5 and BBT6). The libraries BBT1 and BBT5 contain larger inserts and BBT2 and BBT6 contain smaller inserts, with 1500 bp and 350 bp average sizes, respectively. After panning of BBT5 against mammalian cells and bovine fetal serum, the sequences of selected clones were analyzed for correct orientation and fusion with pIII protein. The proteins encoded by genes LIC11719, LIC10769, LIC13143 and LIC12976 were selected. The genes LIC12976, LIC10768, LIC10769 and LIC13418 were evaluated for their conservation in different pathogenic serovars of L. interrogans and free-living L. biflexa serovar Patoc. Proteins LIC12976 (selected by phage display technique) and also LIC13418 that was selected by bioinformatic tools, were amplified by PCR, cloned into pGEM T easy, subcloned into expression vector pAE and expressed in cellular fraction corresponding to the inclusion body in E. coli BL21 (DE3) Star pLysS and E. coli BL21 SI, respectively. After protein renaturation protocol and purification by affinity chromatography, a group of five BALB/c mice was immunized with the purified proteins. Both proteins were shown to be immunogenic with 1:256000 and 1:512000 polyclonal sera titers, respectively. In Western blot the sera were specific to recognize recombinant proteins and native proteins were detected in pathogenic L. interrogans serovars extracts...

Mycovirus in Pseudocercospora griseola, the causal agent of angular leaf spot in common bean.

Pseudocercospora griseola (Sacc.) Crous & Braun is a widespread fungal phytopathogen that is responsible for angular leaf spot in the common bean (Phaseolus vulgaris L.). A number of fungal phytopathogens have been shown to harbour mycoviruses, and this possibility was investigated in populations of Pseudocercospora griseola. The total nucleic acid extracts of 61 fungal isolates were subjected to agarose gel electrophoresis. Small fragments (800-4800 bp) could be identified in 42 of the samples. The presence of dsRNA in isolate Ig838 was confirmed by treatment of total nucleic acid with DNase, RNase A, and nuclease S1. Transmission electron microscopy revealed the presence of viral-like particles 40 nm in diameter in the mycelia of 2 fungal isolates, namely 29-3 and Ig838. The transmission of dsRNA by means of conidia was 100% for isolate 29-3, but there was loss of 1-6 fragments of dsRNA in monosporic colonies of isolate Ig848. Cycloheximide treatment failed to inhibit the mycovirus in isolate 29-3, but proved efficient in the elimination of the 2.2, 2.0, 1.8, 1.2 and 1.0 kb fragments in 2 colonies of isolate Ig848. The occurrence of a mycovirus in Pseudocercospora griseola was demonstrated for the first time in the present study.

Conhecimento da população de Viçosa, MG, sobre as formas de transmissão da aids / The knowledge of the population of Viçosa, MG, about the ways of AIDS transmission

A aids é um dos mais graves problemas de saúde pública atuais e uma importante forma de prevenção reside no conhecimento, por parte da população, das formas de transmissão da doença. Com o objetivo de avaliar o grau de conhecimento da população da cidade de Viçosa em relação às formas de transmissão da aids, foram aplicados 376 questionários, com onze perguntas de múltipla escolha sobre as formas de transmissão da aids, bem como sexo, idade e escolaridade dos entrevistados. Os dados mostraram que as formas de transmissão enfatizadas pelas campanhas de saúde estão bem assimiladas, enquanto situações do cotidiano que não oferecem risco apresentaram elevado número de respostas incorretas. As diferenças encontradas entre os sexos não foram significativas. Quando os dados foram estratificados por idade e escolaridade, foram encontradas diferenças significativas para algumas perguntas em que as pessoas com mais de 55 anos e de menor escolaridade apresentaram maior número de respostas incorretas. Pode-se concluir que a população viçosense conhece as principais formas de transmissão da aids, mas uma parte desconhece a ausência de risco de algumas atividades cotidianas. Esses dados podem ser usados para a elaboração de campanhas de esclarecimento visando à redução do preconceito.

AIDS is a major public health problem reaching all social strata. Knowing about the ways of transmission is a way of preventing the disease. For evaluating the level of knowledge of the population of the city of Viçosa about AIDS transmission, a questionnaire about the ways of transmission of the disease based on studies made in Europe was applied to 376 individuals. The questionnaire consisted of eleven multiple-choice questions about the ways of AIDS transmission, sex, age and educational level of the interviewees. The results showed that the ways of transmission emphasized in health campaigns are well assimilated, while the questions about everyday situations that offer no risk received a high number of incorrect answers. The differences were not significant when data were stratified by sex. The same data stratified by age or educational level showed significant differences for some questions; people aged over 55 and with a lower educational level had a significantly higher number of incorrect answers. It can be concluded that the population of Viçosa knows the main ways of AIDS transmission, but a part of the population does not know that some everyday situations do not pose risk of transmission. These data can be useful for the preparation of elucidative campaigns for reducing prejudice.

[The knowledge of the population of Viçosa, MG, about the ways of AIDS transmission]. / Conhecimento da população de Viçosa, MG, sobre as formas de transmissão da aids.

AIDS is a major public health problem reaching all social strata. Knowing about the ways of transmission is a way of preventing the disease. For evaluating the level of knowledge of the population of the city of Viçosa about AIDS transmission, a questionnaire about the ways of transmission of the disease based on studies made in Europe was applied to 376 individuals. The questionnaire consisted of eleven multiple-choice questions about the ways of AIDS transmission, sex, age and educational level of the interviewees. The results showed that the ways of transmission emphasized in health campaigns are well assimilated, while the questions about everyday situations that offer no risk received a high number of incorrect answers. The differences were not significant when data were stratified by sex. The same data stratified by age or educational level showed significant differences for some questions; people aged over 55 and with a lower educational level had a significantly higher number of incorrect answers. It can be concluded that the population of Viçosa knows the main ways of AIDS transmission, but a part of the population does not know that some everyday situations do not pose risk of transmission. These data can be useful for the preparation of elucidative campaigns for reducing prejudice.