Cellular infiltrate in cutaneous leishmaniasis lesions and therapeutic outcome

Abstract Background: The treatment of cutaneous leishmaniasis is a challenge. A better understanding of the in situ mechanisms involved in the evolution and cure of the disease is essential for the development of new therapies. Objective: Correlate histopathological and immunological characteristics of cutaneous leishmaniasis lesions with clinical outcome after different treatment regimens. Methods: The authors analyzed cellular infiltration and immunohistochemistry staining for CD4, CD8 and IL-17 in biopsy samples from 33 patients with cutaneous leishmaniasis before treatment. All patients were recruited in a randomized clinical trial at Corte de Pedra (Bahia-Brazil) and assigned to receive Glucantime®, Glucantime® + Oral Tamoxifen or Glucantime® + Topical Tamoxifen. Patients were followed for 2 to 6 months to define disease outcome. Results: A similar expression of CD4, CD8 and IL-17 was observed in lesion samples regardless of clinical outcome. In general, a higher amount of CD8 cells were observed compared with CD4 cells. An important observation was that all patients whose cellular infiltrate did not contain plasma cells were cured after treatment. Study limitations: Isolated quantification of TCD8 and IL-17 using immunohistochemistry is insufficient to analyze the role of these molecules in the immunopathogenesis of cutaneous leishmaniasis. In addition, the expansion of the immunohistochemistry panel would allow a more complete analysis of the immune response in situ. Conclusions: The absence of plasma cells in cutaneous leishmaniasis lesions was related to a favorable therapeutic outcome.

Specificity of a ribosomal DNA derived oligonucleotide probe in the diagnosis of cutaneous or mucocutaneous leishmaniasis

Detection of parasites in clinical lesions is essential for a conclusive diagnosis of cutaneous or mucocutaneous leishmaniasis. Biopsies of experimentally infected animals were used to test a ribosomal DNA (rDNA) derived oligonucleotide (S3) as a diagnostic tool for leishmaniasis, Leishmania amazonensis were detected by that probe in dot blot assays containing RNA from experimentally induced BALB/c footpad lesions. RNA from a macrophage rich lesion induced by BCG infection yielded negative results. Specificity of S3 in differential diagnosis was also experimentally evidenced by the negative hybridization with nucleic acids of other infectious agents causing cutaneous lesions such Fonsecaea pedrosoi, Cladosporium carrionii, Phialophora verrucosa, Sporotrix schenkii, Histoplasma capsulatum and Paracoccidioides brasiliensis. In addition, comparison of S3 and 18S rDNA sequences of Mycobacterium tuberculosis, atypical mycobacteria, M. leprae and Treponema pallidum revealed a low degree of similarity. These data indicated that S3 can identify Leishmania species ande exclude the presence of other pathogens, which lead to misdiagnosis, in hybridization tests.

Molecular biology applied to parasitology: the ribosomal cistron as a tool in taxonomic and phylogenetic studies and as model for gene expression analysis

The singular sequence organization of ribosomal RNA encoding genes, consisting in the presence of highly conserved segments immersed in neutral evolving sequences, allowed its utilization as a tool for taxonomic and phylogenetic studies. In this communication a review of some contributions to related studies on Trypanosomatidae family organisms is presented. The desription of restriction maps for these genes led to the consequent description of probes useful for proper identification of the parasites. Better conditions for detection of parasites in samples from patients or from insect host vectors in endemic areas were established. On the other side, studies on basic concerns such as the regulation of gene expression, led to the determination of the promoter region for RNA Pol I of Trypanosoma cruzi. Sequence comparison with other trypanosomatid promoters did not show any consensus. However, the presence of elements in both promoter region and sequences upstream to the promoter indicated a possible transcription regulatory role for these elements. Transfection experiments showed that no enhancer activity is present.