Effect of thiazolidine LPSF SF29 on the growth and morphology of Trypanosoma cruzi.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an endemic illness in Latin America. Efforts have been made by several groups to develop new effective and safe anti-T. cruzi drugs. In the present work, we show that thiazolidine LPSF SF29 inhibited growth of the epimastigote and amastigote forms and caused lysis in the trypomastigote form of T. cruzi, leading to death of the protozoan. Mitochondrial dysfunction was also observed. The thiazolidine induced ultrastructural alterations such as detachment of the flagellar membrane, intense mitochondrial swelling, formation of myelin-like figures and the appearance of autophagosomes. Taken together, these results suggest that this new thiazolidine is active against T. cruzi and constitutes a promising drug for the therapy of Chagas disease.

Blood and inflammatory cells of the lungfish Lepidosiren paradoxa.

A special interest exists concerning lungfish because they may possess characteristics of the common ancestor of land vertebrates. However, little is known about their blood and inflammatory cells; thus the fine structure, cytochemistry and differential cell counts of coelomic exudate and blood leucocytes were studied in Lepidosiren paradoxa. Blood smear analyses revealed erythrocytes, lymphocytes, monocytes, polymorphonuclear agranulocytes, thrombocytes and three different granulocytes. Blood monocytes and lymphocytes had typical vertebrate morphology. Thrombocytes had large vacuoles filled with a myelin rich structure. The polymorphonuclear agranulocyte had a nucleus morphologically similar to the human neutrophil with no apparent granules. Types I and II granulocytes had eosinophilic granules. Type I granulocytes had round or elongated granules heterogeneous in size, while type II had granules with an electron dense core. Type III granulocyte had many basophilic granules. The order of frequency was: type I granulocyte, followed by lymphocyte, type II granulocyte, monocyte, polymorphonuclear agranulocyte and type III granulocyte. Peroxidase localized mainly at the periphery of the granules from type II granulocytes, while no peroxidase expression was detected in type I granulocytes. Alkaline phosphatase was localized in the granules of type II granulocyte and acid phosphatase cytochemistry also labelled a few vacuoles of polymorphonuclear agranulocyte. About 85% of the coelomic inflammatory exudate cell population was type II granulocyte, 10% polymorphonuclear agranulocyte and 5% macrophages as judged by the nucleus and granule morphology. These results indicate that this lungfish utilises type II granulocytes as its main inflammatory granulocytes and that the polymorphonuclear agranulocyte may also be involved in the inflammatory response. The other two granulocytes appear similar to the mammalian eosinophil and basophil. In summary, this lungfish appears to possess the typical inflammatory granulocytes of teleosts, however, further functional studies are necessary to better understand the polymorphonuclear agranulocyte.

NAD(P)H-oxidase presence in Toxoplasma gondii tachyzoite vacuole during interaction with IFN-gamma-activated human endothelial cells.

Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells (HUVEC) where it resides in a parasitophorous vacuole (PV) preventing lysosomal fusion. To study the intracellular outcome of PV containing tachyzoites of T. gondii during interaction with IFN-gamma-activated HUVEC, a quantitative analysis of the T. gondii infection and multiplication was assayed. The quantification of PVs' fusion with lysosomes, ultrastructural examination of phagosome-lysosome fusion, and the localization of NAD(P)H-oxidase activity were also investigated. HUVEC activated with IFN-gamma inhibited T. gondii infection and multiplication by 67.5% and 91.0%, respectively. After 4 hr of infection, 10.2% of IFN-gamma-activated HUVEC exhibited phagosome-lysosome fusion assayed by fluorescence microscopy, which was also observed at the ultrastructural level. Furthermore, the enzyme NAD(P)H-oxidase present at the plasma membrane of activated HUVEC was internalized together with the parasite in 38.0% of the cells. In addition, colocalization of colloidal gold particles and reaction product of NAD(P)H-oxidase in the PV of some activated HUVEC was observed. These results suggest that NAD(P)H-oxidase may participate in a mechanism by which IFN-gamma-activated HUVEC inhibit T. gondii multiplication.

The microtubule analog protein, FtsZ, in the endosymbiont of trypanosomatid protozoa.

Blastocrithidia culicis and Crithidia deanei are trypanosomatids that harbor an endosymbiotic bacterium in their cytoplasm. In prokaryotes, numerous proteins are essential for cell division, such as FtsZ, which is encoded by filament-forming temperature-sensitive (fts) genes. FtsZ is the prokaryotic homolog of eukaryotic tubulin and is present in bacteria and archaea, and has also been identified in mitochondria and chloroplasts. FtsZ plays a key role in the initiation of cytokinesis. It self-assembles into the Z ring, which establishes the division plane during septation. In this study, immunoblotting analysis using a FtsZ polyclonal antibody, revealed a 40-kDa band characteristic of FtsZ in endosymbiont fractions and in whole trypanosomatid homogenates, but not in whole cell extracts of aposymbiotic strains. Confocal microscopy and ultrastructural analysis revealed a specific and dispersed labeling over the endosymbiont. Bars and ring-like structures, which are suggestive of the presence of Z-rings, were never observed, even during the division of the symbiont. This peculiar distribution of FtsZ may represent an arrangement of cytoskeleton protein intermediate between prokaryotic and eukaryotic cells. The endosymbiont ftsz gene was completely sequenced after amplification of DNA from symbiont-bearing trypanosomatids or from pure endosymbiont fractions, using PCR and specific primers. The sequences obtained from the endosymbionts from C. deanei and B. culicis were very similar, and were most closely related to bacteria from the genus Pseudomonas.

Enhancement of lipid bodies during differentiation of skeletal myofibroblasts of rat's fetus in vitro.

Fibroblasts in vitro can acquire myofibroblast phenotype by the development of several biochemical and morphological properties of smooth muscle cells, particularly the expression of alpha-smooth muscle actin. These cells play a major role in inflammatory responses and in wound repair through their production of growth factors, cytokines, and other soluble mediators. Lipid bodies (LB) are lipid-rich cytoplasmic inclusions and have been recognized as specialized intracellular domains involved in the formation of paracrine mediators of inflammation. The aim of the present study was to investigate the occurrence and distribution of LB during differentiation of rat fetus skeletal fibroblasts into myofibroblasts in vitro. Primary cultures of fibroblasts were obtained from skeletal muscles of 18-d-old Wistar strain rat fetus by enzymatic dissociation. At 1-7 d, the cells were stained with Nile red vital dye to identify LB and then observed under a Zeiss CLSM-310. Our results showed that there was an accentuated increase in the number of LB during the differentiation of skeletal fibroblasts into myofibroblasts and that these inclusions were scattered at the cytoplasm.