Differential expression of TLRs 2, 4, 9, iNOS and TNF-α and arginase activity in peripheral blood monocytes from glucantime unresponsive and responsive patients with anthroponotic cutaneous leishmaniasis caused by Leishmania tropica.

BACKGROUND: Detection of the mechanism of host/parasite interactions in unresponsive forms of anthroponotic cutaneous leishmaniasis (ACL) caused by Leishmania tropica is helpful for immunotherapy and vaccine development. In the present study, the gene expression of toll-like receptors (TLRs), TNF-α, iNOS and also arginase (ARG) activity in monocytes from Glucantime unresponsive in comparison to responsive patients infected with L. tropica was investigated. METHODS: In this case-control study, patients with unresponsive (n = 10) and responsive (n = 10) ACL were recruited. Gene expression of TLR2, TLR4, TLR9, TNF-α and iNOS was analyzed in L. tropica-exposed monocytes. The level of ARG activity in both isolated promastigotes and the lysates of monocytes was also determined. RESULTS: L. tropica-exposed monocytes represented higher expression of all three TLRs and TNF-α and lower expression of iNOS compared to unexposed ones in both groups of patients. Results revealed a significant down-regulation of TLR2 and TNF-α and up-regulation of TLR9 expression in unresponsive isolates in comparison to responsive ones. Besides, ARG level showed a significant increase in L. tropica-stimulated monocytes and cultured promastigotes from unresponsive isolates versus responsive ones. CONCLUSIONS: The decreased TLR2, TLR4, TNF-α and iNOS and the increased level of TLR9 expression in L. tropica-exposed monocytes from unresponsive isolates and also the increment in ARG activity in their promastigotes and monocytes, might possibly be involved in the severity of the disease and leading to Glucantime unresponsiveness.

Current knowledge of sand fly fauna (Diptera: Psychodidae) of northwestern Yemen and how it relates to leishmaniasis transmission.

This report presents the results of the first entomological survey of the sand fly fauna in northwestern Yemen. Sand flies were collected using sticky paper traps and CDC light traps from Hajjah governorate, a cutaneous leishmaniasis focus due to Leishmania tropica. Six Phlebotomus species: P. alexandri, P. arabicus. P. bergeroti, P. orientalis, P. papatasi, P. sergenti and ten Sergentomyia species: S. africana, S. antennata, S. christophersi, S. dolichopa, S. dreyfussi, S. fallax, S. multidens, S. taizi, S. tiberiadis, S. yusafi were identified. P. alexandri was the most predominant Phlebotomus species and P. papatasi was a scarce species. S. fallax was the principal Sergentomyia species and S. dolichopa was the least species encountered. The diversity of the sand fly fauna within and among three altitudinal ranges using Simpson index and Jaccard's diversity coefficient respectively were measured. High species diversity was found in all altitude ranges. There seemed to be more association between sand fly fauna in higher altitudes with fauna from moderate altitudes. Sand fly seasonal activity showed a mono-modal trend in the lowland and a confluent bimodal trend in the highlands. Leishmania DNA could not be detected from 150 Phlebotomus females using PCR-RFLP. A possible zoonotic cutaneous transmission cycle due to Leishmania tropica in northwestern Yemen would involve P. arabicus as the sand fly vector and the rock hyrax as the reservoir host. The vector competence for P. alexandri as a vector of visceral leishmaniasis in Hajjah governorate is discussed.

Breeding sites of Phlebotomus sergenti, the sand fly vector of cutaneous leishmaniasis in the Judean Desert.

Phlebotomine sand flies transmit Leishmania, phlebo-viruses and Bartonella to humans. A prominent gap in our knowledge of sand fly biology remains the ecology of their immature stages. Sand flies, unlike mosquitoes do not breed in water and only small numbers of larvae have been recovered from diverse habitats that provide stable temperatures, high humidity and decaying organic matter. We describe studies designed to identify and characterize sand fly breeding habitats in a Judean Desert focus of cutaneous leishmaniasis. To detect breeding habitats we constructed emergence traps comprising sand fly-proof netting covering defined areas or cave openings. Large size horizontal sticky traps within the confined spaces were used to trap the sand flies. Newly eclosed male sand flies were identified based on their un-rotated genitalia. Cumulative results show that Phlebotomus sergenti the vector of Leishmania tropica rests and breeds inside caves that are also home to rock hyraxes (the reservoir hosts of L. tropica) and several rodent species. Emerging sand flies were also trapped outside covered caves, probably arriving from other caves or from smaller, concealed cracks in the rocky ledges close by. Man-made support walls constructed with large boulders were also identified as breeding habitats for Ph. sergenti albeit less important than caves. Soil samples obtained from caves and burrows were rich in organic matter and salt content. In this study we developed and put into practice a generalized experimental scheme for identifying sand fly breeding habitats and for assessing the quantities of flies that emerge from them. An improved understanding of sand fly larval ecology should facilitate the implementation of effective control strategies of sand fly vectors of Leishmania.

Transbilayer translocation of membrane phosphatidylserine and its role in macrophage invasion in Leishmania promastigotes.

Infectivity of Leishmania promastigotes has been shown to be growth cycle-dependent and restricted to the stationary phase. By using annexin V-FITC binding and procoagulant activity measurement assays, we show here that the promastigotes in the stationary phase contain significantly higher amounts of phosphatidylserine (PS) on their surface as compared to the log phase promastigotes. We also demonstrate that the infectivity of the promastigotes is determined by the presence of PS on their surface. In addition, by using NBD-labelled phospholipids, we show that the promastigote plasma membrane contains ATP-dependent out-to-in and ATP-independent in-to-out PS translocases which regulate the PS localisation in two-halves of the membrane bilayer, and that the greater amounts of external PS observed in the stationary phase promastigotes is perhaps due to the slower ATP-dependent out-to-in PS movements in these cells, as compared to the log phase promastigotes.

Aspectos clínicos comparativos da leishmaniose tegumentar na Regiåo Amazônica e Regiåo Centro-Oeste / A comparative study of cutaneous leishmaniasis from the Amazon and Central West regions of Brazil

Foram estudados 245 casos de Leishmaniose Tegumentar, sendo 149 da Regiåo Amazônica e 96 da Regiåo Centro-Oeste. De cada caso foram analisadas 30 variáveis clínicas. Na Regiåo Amazônica há incidência significativamente maior da LT no grupo etário de 15 a 25 anos. Na Regiåo Centro-Oeste, a incidência maior é em casados. Quanto à profissåo, na Regiåo Centro-Oeste há incidência maior em agricultores e dométicas, em relaçåo a idênticas profissÆes da Regiåo Amazônica; nessa regiåo, as profissÆes de estudante, de militar e de trabalhador braçal, comparativamente com as mesmas profissÆes da Regiåo Centro-Oeste, têm maior significaçåo. Há incidência signifivamente maior de lesÆes sistematizadas (múltiplas) no caso da Regiåo Amazônica que da Regiåo Centro-Oeste, e o único caso de forma foi observado naquela regiåo. Há predominância significativamente maior do tempo de evoluçåo das lesÆes, inferior a 60 dias na Regiåo Amazônica, quando comparado com igual período da Regiåo Centro-Oeste. Nesta regiåo, o período de maior predominância é aquele superior a 240 dias. Há incidência significativamente maior de lesÆes ulceradas e em atividade na Regiåo Amazônica, quando comparadas com as lesÆes observadas na Regiåo Centro-Oeste. O inverso sucede com o comprometimento das mucosas e a presença de lesÆes cutâneas verrucosas que incidem mais na Regiåo Centro-Oeste. As leishmânides såo mais freqüentes na Regiåo Amazônica. É provável que essas diferenças observadas, entre as duas regiÆes, sejam devidas a diferentes espécies ou subespécies de parasitos envolvidos