Genética da leishmaniose cutânea em humanos: identificação de vias imunológicas que contribuem para a suscetibilidade à doença / Genetics of cutaneous leishmaniasis in humans: identification of immunological pathways that contribute to disease susceptibility

A leishmaniose cutânea (LC) é a forma clínica mais comum do complexo de doenças causadas por protozoários do gênero Leishmania. Interessantemente, alguns indivíduos infectados com espécies dermotrópicas do parasito não desenvolvem a LC, enquanto outros desenvolvem lesões crônicas. Os mecanismos envolvidos nesta variação permanecem amplamente desconhecidos, embora fatores genéticos do hospedeiro podem influenciar o risco de desenvolver a doença. No primeiro estudo apresentado nesta tese, foi mostrado que a sinalização IL-2/IL-2R desempenha um papel crucial na resposta imune contra espécies dermotrópicas de Leishmania. Os transcritos de vários genes da via de sinalização IL-2 são mais abundantes em úlceras cutâneas causadas por Leishmania braziliensis do que em amostras de pele normal de dadores não infectados. Um estudo de associação em famílias brasileiras (209 famílias nucleares) identificou dois polimorfismos no gene IL2RA associados à LC causada por L. braziliensis [rs10905669 (p = 3x10-4) e rs706778 (p = 3x10-4)]...

Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis and can be caused by several dermotropic Leishmania species. Interestingly, some infected individuals do not develop cutaneous lesions, while others are severely affected. The basis of this variation remains largely unknown, although host genetic factors seem to influence disease risk. In the first study presented in this thesis, it was shown that IL-2 plays a crucial role in human immunity against dermotropic Leishmania species. It was observed that the transcripts of several genes of the IL-2 pathway were more abundant in skin ulcers caused by Leishmania braziliensis than in normal skin samples. A primary association study on Brazilians (754 individuals from 209 families) identified two polymorphisms in the IL2RA gene associated with CL caused by L. braziliensis [rs10905669 (p = 3x10-4) and rs706778 (p = 3x10-4)]...

Toll-like receptor signal transduction

Toll-like receptors (TLRs) are the archetypal pattern recognition receptors in sensing exogenous pathogens. Activation of TLRs is a first line of defense of the immune system, leading to the activation and recruitment of neutrophils and macrophages to sites of infection and enhances antimicrobial activity. The TLR signaling through different intracellular molecules, such as MAP kinases and IkappaB kinases which are conserved signaling elements for many receptors, leads to a distinct set of proinflammatory gene expressions. However, how these pathways differentially and precisely control the transcription of identical genes remains largely unknown. Our review focuses on the details of up-to- date signaling molecules including negative regulators and their role in controlling innate immune response. We also stress the importance of developing systemic approaches for the global understanding of TLR signaling so that appropriate drug therapeutic targets can be identified for regulating inflammatory diseases.

Involvement of MAP Kinases in Apoptosis of Macrophage Treated with Trichomonas vaginalis

A primitive protozoan parasite Trichomonas vaginalis selectively activates the signal transduction pathways in macrophages (RAW264.7). This study evaluated the correlation of these signaling pathways and T. vaginalis-induced cell apoptosis. In macrophages infected with T. vaginalis, apoptosis was assessed on the basis of DNA fragmentation on agarose gel electrophoresis. Infection of macrophages with T. vaginalis induced tyrosine phosphorylation of several proteins. Infected cells with T. vaginalis were shown to associate with phosphorylation of the extracellular signal-regulated (ERK) 1/2 kinase, p38, c-Jun N-terminal kinase (JNK) mitogen-activated protein (MAP) kinases on Western blot analysis. The present finding also demonstrated a link between the ERK1/2, JNK and p38 apoptotic pathways that was modulated by T. vaginalis infection.