Detection of matrix metallopeptidase-9-like proteins in Trypanosoma cruzi.

In this study, the cell-associated and extracellular peptidases of Trypanosoma cruzi grown in modified Roitman's complex (MRC) medium were analyzed by measuring peptidase activity in gelatin-containing zymograms. Our results showed that the cell-associated peptidases as well as peptidases extracellularly released by T. cruzi displayed two distinct proteolytic classes: cysteine and metallopeptidase activities. The major cysteine peptidase, cruzipain, synthesized by T. cruzi cells was detected in cellular parasite content, as a 50kDa reactive polypeptide, after probing with anti-cruzipain antibody. In addition, metallo-type peptidases belonging to the matrix metallopeptidase-9 (MMP-9) family were revealed, after Western blotting, as a 97kDa protein band in cellular extract and an 85kDa polypeptide in both cellular and secreted parasite extracts. The MMP-9-like activity present in cells and spent culture medium was immunoprecipitated by an anti-MMP-9 polyclonal antibody. The surface location of MMP-9-like proteins in T. cruzi was also evidenced by means of flow cytometry analysis. Furthermore, doxycycline that has direct MMP-9 inhibiting properties in vitro, inhibited MMP-9-like activities in gel zymography, immunoprecipitation and flow cytometry analyses. This is the first report of the presence of MMP-9-like molecules in T. cruzi. The presence of a matrix extracellular-degrading enzyme may play a role in the T. cruzi-host cell interaction, making this enzyme a potential target for future drug development against this pathogenic trypanosomatid.

Osteoblasts and bone marrow mesenchymal stromal cells control hematopoietic stem cell migration and proliferation in 3D in vitro model.

BACKGROUND: Migration, proliferation, and differentiation of hematopoietic stem cells (HSCs) are dependent upon a complex three-dimensional (3D) bone marrow microenvironment. Although osteoblasts control the HSC pool, the subendosteal niche is complex and its cellular composition and the role of each cell population in HSC fate have not been established. In vivo models are complex and involve subtle species-specific differences, while bidimensional cultures do not reflect the 3D tissue organization. The aim of this study was to investigate in vitro the role of human bone marrow-derived mesenchymal stromal cells (BMSC) and active osteoblasts in control of migration, lodgment, and proliferation of HSCs. METHODOLOGY/PRINCIPAL FINDINGS: A complex mixed multicellular spheroid in vitro model was developed with human BMSC, undifferentiated or induced for one week into osteoblasts. A clear limit between the two stromal cells was established, and deposition of extracellular matrix proteins fibronectin, collagens I and IV, laminin, and osteopontin was similar to the observed in vivo. Noninduced BMSC cultured as spheroid expressed higher levels of mRNA for the chemokine CXCL12, and the growth factors Wnt5a and Kit ligand. Cord blood and bone marrow CD34(+) cells moved in and out the spheroids, and some lodged at the interface of the two stromal cells. Myeloid colony-forming cells were maintained after seven days of coculture with mixed spheroids, and the frequency of cycling CD34(+) cells was decreased. CONCLUSIONS/SIGNIFICANCE: Undifferentiated and one-week osteo-induced BMSC self-assembled in a 3D spheroid and formed a microenvironment that is informative for hematopoietic progenitor cells, allowing their lodgment and controlling their proliferation.

Analysis of Peptidases in Non-Infected and Trypanosoma cruzi-Infected Mouse Embryo Hepatocyte Cells.

Cellular and extracellular peptidase profiles from non-infected and Trypanosoma cruzi-infected hepatocyte cell cultures were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) containing different copolymerized proteins as substrates. A 100 kDa metallopeptidase activity was detected in the cellular extracts and in the culture supernatant fluids of both systems, had the ability to exclusively degrade gelatin. However, non-infected hepatocytes produced an additional extracellular metallopeptidase of 85 kDa. In the non-infected and in the infected hepatocytes, a cysteine peptidase migrating in gelatin-SDS-PAGE at 60 kDa presented the broadest specificity, since it was also able to hydrolyze casein and hemoglobin. The 100 kDa component was only detected at alkaline pH and predominantly expressed in non-infected hepatocytes. Conversely, the 60 kDa cysteine peptidase was only observed in acidic condition and its production was robustly augmented in T. cruzi-infected cells, probably due to the cysteine peptidase synthesized by the parasites, as corroborated by immunoblotting assay using anti-cruzipain antibody. Collectively, these results suggest that peptidases may be involved in the interaction process between T. cruzi and hepatocytes in vitro.

Reduced activity of matrix metalloproteinase-9 in trypanosoma cruzi-infected mouse embryo hepatocyte cell.

In this work, we are reporting differences in the proteolytic profile of Trypanosoma cruzi-infected and non-infected primary cultures of mouse embryo hepatocyte cells. In gelatin-SDS-PAGE, ours results showed the presence of a 100kDa metalloproteinase in the supernatant and in the cells of both systems and an 85kDa extracellular metalloproteinase found only in the non-infected hepatocyte cultures. An enzymatic assay using gelatin as substrate showed a decrease of 74 and 70% in metalloproteinase activity in the culture supernatant and in the cell hepatocyte system infected with T. cruzi, respectively. Western blotting analysis using anti-matrix metalloproteinase-9 (MMP-9) antibody recognized the 100 and 85kDa protein bands, indicating that hepatocyte metalloproteinases correspond to the latent and active forms of the gelatinase MMP-9, respectively. The localization of MMP-9 was established by immunocytochemistry analysis in the cytoplasm of the non-infected and infected hepatocyte cells. In normal and infected hepatocyte cells, cysteine-proteinases migrating in gelatin-SDS-PAGE at 60kDa were detected and should correspond to lysosomal cysteine-proteinases of T. cruzi (cruzipain) and hepatocytes. In T. cruzi-infected hepatocytes an increase of approximately 50% in this enzymatic activity was observed, possibly due to parasite's cruzipain.

Ultrastructural features of the midgut epithelium of females Lutzomyia intermedia (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae)

A morphological study of the midgut of Lutzomyia intermedia, the primary vector of cutaneous leishmaniasis, in southeast Brazil, was conducted by light, scanning and transmission electron microscopy. The midgut is formed by a layer of epithelium of columnar cells on a non-cellular basal lamina, under which there is a musculature, which consists of circular and longitudinal muscular fibers. A tracheolar network is observed surrounding and penetrating in the musculature. Females were examined 12, 24, 48, 72 h and 5 days following a blood meal and were analyzed comparatively by transmission electron microscopy with starved females. In starved females, the epithelium of both the anterior and posterior sections of the midgut present whorl shaped rough endoplasmic reticulum. The posterior section does not present well-developed cellular structures such as mitochondria. Observations performed at 12, 24, 48 and 72 h after the blood meal showed morphological changes in the cellular structures in this section, and the presence of the peritrophic matrix up to 48 h after the blood meal. Digestion is almost complete and a few residues are detected in the lumen 72 h after blood feeding. Finally, on the 5th day after the blood meal all cellular structures present the original feature resembling that seen in starved sand flies. Morphometric data confirmed the morphological observations. Mitochondria, nuclei and microvilli of midgut epithelial cells are different in starved and blood fed females. The mitochondria present a similar profile in the epithelium of both the anterior and posterior section of the midgut, with higher dimension in starved females. The cell microvilli in the posterior section of the midgut of starved females are twice the size of those that had taken a blood meal. We concluded that there are changes in the midgut cellular structures of L. intermedia during the digestion of blood, which are in agreement with those described for other hematophagous diptera

Extracellular serine-proteinases isolated from Streptomyces alboniger: Partial characterization and effect of aprotinin on cellular structure

Streptomyces alboniger ATCC 12461 grown in brain heart infusion (BHI) medium produced two extracellular serine-proteinases, denoted SP I and SP II, which were purified by ammonium sulfate precipitation and aprotinin-agarose affinity chromatography. SP I was purified 88,9-fold and SP II 66,7- fold, with 33.4 percent and 10.4 percent yield, respectively. The optimum pH for the proteinases activity, using a-N-p-tosyl-L-arginine-methyl ester (TAME) as substrate, was 9-10 and the optimum temperature was 37ºC. The proteolytic activity of SP I and SP II was inhibited by aprotinin and SP I was partially inhibited by leupeptin, both serine-proteinase inhibitors. S. alboniger growth in BHI-liquid medium decreased when 5 mg/ml, 10 mg/ml of aprotinin was used, being completely inhibited with 20 mg/ml and 40 mg/ml. At the ultrastructural level, aprotinin-treated S. alboniger cells showed swelling of the bacterial body and condensation of the genetic material, probably related to the inhibition of its growth

Detection of extracellular proteases from microorganisms on agar plates

We present herein an improved assay for detecting the presence of extracellular proteases from microorganisms on agar plates. Using different substrates (gelatin, BSA, hemoglobin) incorporated into the agar and varying the culture medium composition, we were able to detect proteolytic activities from Pseudomonas aeruginosa, Micrococcus luteus and Serratia marcescens as well as the influence that components displayed in the expression of these enzymes. For all microorganisms tested we found that in agar-BHI or yeast extract medium containing gelatin the sensitivity od proteinase detection was considerably greater than in BSA-agar or hemoglobin-agar. However, when BSA or hemoglobin were added to the culture medium, there was an increase in growth along with a marked reduction in the amount of proteinase production. In the case of M. luteus the incorporation of glycerol in BHI or yeast extract gelatin-agar induced proyease liberation. Our results that the technique described here is of value for detecting extracellular proteases directly in the culture medium, by means of a qualitative assay, simple, inexpensive, straight forward method to assess the presence of the proteolytic activity of a given microorganism colony with great freedom in substrate selection.

Sialoglycoconjugates in Trypanosoma cruzi-host cell interaction: possible biological model - a review

A number of glycoconjugates, including glycolipids and glycoproteins, participate in the process of host-cell invasion by Trypanosoma cruzi and one of the most important carbohydrates involved on this interaction is sialic acid. It is known that parasite trans-sialidase participates with sialic acid in a coordinated fashion in the initial stages of invasion. Given the importance of these sialogycoconjugates, this review sets out various possible biological models for the interaction between the parasite and mammalian cells that possess a sialylated receptor/ligand system

Trypanosoma cruzi recognition by macrophages and muscle cells: perspectives after a 15-year study

Macrophages and muscle cells are the main targets for invasion of Trypanosoma cruzi. Ultrastructural studies of this phenomenon in vitro showed that invasion occurs by endocytosis, with attachment and internalization being mediated by different components capable of recognizing epi-or trypomastigotes (TRY). A parasitophorus vacuole was formed in both cell types, thereafter fusing with lysosomes. Then, the mechanism of T. cruzi invasion of host cells (HC) is essentially similar (during a primary infection in the abscence of a specific immune response), regardless of wether the target cell is a professional or a non-professional phagocytic cell. Using sugars, lectins, glycosidases, proteinases and proteinase inhibitors, we observed that the relative balance between exposed sialic acid and galactose/N-acetyl galactosamine (GAL) residues on the TRY surface, determines the parasite's capacity to invade HC, and that lectin-mediated phagocytosis with GAL specificity is important for internalization of T. cruzi into macrophages. On the other hand, GAL on the surface to heart muscle cells participate on TRY adhesion. TRY need to process proteolytically both the HC and their own surface, to expose the necessary ligands and receptors that allow binding to, and internalization in the host cell. The diverse range of molecular mechanisms which the parasite could use to invade the host cell may correspond to differences in the available "receptors"on the surface of each specific cell type. Acute phase components, with lectin or proteinase inhibitory activities (a-macroglobulins), may also be involved in T. cruzi-host cell interaction