Optimisation de la domiciliation des cellules CD34+ de sang de cordon ombilical: élucider les mécanismes en cause dépendant du CXCR4.

Le sang provenant d’un cordon ombilical (SCO) représente une bonne source de cellules souches hématopoïétiques (CSH) pour des transplantations. Cependant, le nombre de cellules souches contenues dans ce sang est souvent insuffisant pour greffer un adulte. Le mécanisme intervenant dans la domiciliation de ces cellules au sein de la moelle osseuse (MO) est encore mal compris. On sait que l’interaction entre la chimiokine SDF-1 et le récepteur CXCR4, présent sur les cellules CD34+ de SCO, mène à la migration de ces cellules en direction de la MO. Nous pensons que l’augmentation de la proportion de cellules qui réussit à se greffer pourra pallier au problème du nombre. Les produits de dégradation, C3a et le C3desarg,, issus du système du complément, sont connus pour favoriser la réponse de cellules exprimant CXCR4 vers SDF-1. Nous avons analysé l’effet du C3adesarg, molécule non anaphylatoxique, sur la migration cellulaire vers SDF-1, de même que sur la prise de greffe des cellules CD34+ issues de SCO suite à une transplantation sur des souris NOD/SCIDyC-. Nos expériences ont démontré que le C3a ainsi que le C3adesarg augmentaient tous les deux la réponse des cellules CD34+ vers SDF-1. Toutefois, nous n’avons pas pu démontrer que ces molécules liaient directement le récepteur CXCR4. Par contre, le composé C3adesarg favorise la prise de greffe des cellules CD34+ de SCO. Il serait donc un bon candidat pour poursuivre une optimisation de ses propriétés. Nous avons également constaté que suite à une transplantation chez la souris, les cellules CD34+ de SCO subissent une hausse d’expression transitoire de leur CXCR4 environ quatre jours après la greffe. Cette hausse d’expression coïncide avec la multiplication des cellules CD34+ dans la MO. Nous avons également confirmé qu’une cellule CD34+ avec une forte expression de CXCR4 était dans un état prolifératif. Nos données suggèrent que l’interaction directe avec les cellules stromales soit responsable de cette hausse d’expression de CXCR4.

Pycnoscelus surinamensis (Linnaeus, 1758) (Blaberoidea: Blaberidae), a cockroach with a possible association with the ant Brachymyrmex cordemoyi Forel, 1895 (Hymenoptera: Formicidae) and which may be exhibiting a domiciliation trend.

In the present paper, we report on the occurrence of the cockroach Pycnoscelus surinamensis (Linnaeus, 1758) in Brachymyrmex cordemoyi Forel, 1895 nests, indicating a possible symbiosis between these two species. Also, the finding of intradomicile P. surinamensis nymphs may indicate this species is extending its habitat to human habitations, i.e. changing its ecological category from peridomestic to domestic.

Rural Triatoma rubrovaria from Southern Brazil harbors Trypanosoma cruzi of lineage IIc

Triatoma infestans, the main vector of Chagas disease, has nearly been eliminated from Brazil. Nevertheless, other triatominae species are involved in the domiciliation process, including Triatoma rubrovaria in Rio Grande do Sul State (RS). Previous studies showed that 1.6% of the T rubrovaria specimens collected at the rural district of Quarai, RS, were naturally infected by Trypanosoma cruzi. In this study, five T. cruzi isolates obtained from infected triatomines were characterized molecularly and biologically. Genotyping of the T cruzi isolates showed that they belong to lineage IIc of T cruzi (TCIIc). Biological characterization showed miotropism and myositis during acute and chronic phases of infection, respectively. Virulence and mortality rates were variable among isolates. To our knowledge, this study corresponds to the first characterization of T cruzi isolates from T rubrovaria and the first description of TCIIc in the sylvatic cycle of T cruzi from the southern region of Brazil.

Dispersion capacity of Triatoma sherlocki, Triatoma juazeirensis and laboratory-bred hybrids

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Prevalência de anticorpos anti-vírus da hepatite A em escolares no município de Porto Velho, Rondônia

A avaliação da prevalência de anticorpos contra o vírus da Hepatite A foi realizada no período de setembro a dezembro de 2000, em 185 escolares de níveis sócio-econômicos distintos, na faixa etária entre seis e quinze anos, em duas escolas no município de Porto Velho, Rondônia, utilizando teste imunoenzimático comercial (DiaSorin) para detecção de anticorpos anti-VHA Totais e IgM. Foram avaliados 90 escolares de nível sócio-econômico médio e alto, procedentes de Escola Privada, e 95 de baixo nível sócio-econômico, de Escola Pública. Dos 90 escolares da Escola Privada, 45 (50%) apresentaram positividade ao teste para detecção de anticorpos anti-VHA Totais e deste, 4 (8,9%) foram soropositivos ao anti-VHA IgM, enquanto na Escola Pública, dos 95 estudantes, 90 (94,7%) apresentaram anticorpos anti-VHA Totais e destes, apenas 1 (1,1%) apresentou anticorpos anti-VHA IgM (p< 0,05). As faixas etárias entre 12 e 14 anos na Escola Privada, e 8 e 10 anos na Escola Pública, apresentaram maior prevalência de anticorpos anti-VHA. Não houve diferença significativa de prevalência de anti-VHA entre os sexos, nos dois grupos estudados (p>0,05). Fatores como renda familiar, destino dos dejetos domiciliares e qualidade de água consumida também foram estudados e relacionados à prevalência de anti-VHA, apresentando diferenças significativas entre os grupos. Os resultados deste estudo mostraram que a HVA é endêmica na região, e que, medidas como melhoria nas condições sanitárias do município são necessárias para diminuir a propagação do VHA na população.

A novel association between Rhodnius neglectus and the Livistona australis palm tree in an urban center foreshadowing the risk of Chagas disease transmission by vectorial invasions in Monte Alto City, Sao Paulo, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mosquitoes in degraded and preserved areas of the Atlantic Forest and potential for vector-borne disease risk in the municipality of Sao Paulo, Brazil

In order to assess the epidemiological potential of the Culicidae species in remaining areas of the Brazilian Atlantic Forest, specimens of this family were collected in wild and anthropic environments. A total of 9,403 adult mosquitoes was collected from May, 2009 to June, 2010. The most prevalent among species collected in the wild environment were Anopheles (Kerteszia) cruzii, the Melanoconion section of Culex (Melanoconion), and Aedes serratus, while the most common in the anthropic site were Coquillettidia chrysonotum/albifera, Culex (Culex) Coronator group, and An. (Ker.) cruzii. Mosquito richness was similar between environments, although the abundance of individuals from different species varied. When comparing diversity patterns between environments, anthropic sites exhibited higher richness and evenness, suggesting that environmental stress increased the number of favorable niches for culicids, promoting diversity. Increased abundance of opportunistic species in the anthropic environment enhances contact with culicids that transmit vector-borne diseases.