Therapeutic Strategies against Leishmania and Trypanosoma.

Human African trypanosomiasis (also known as sleeping sickness, with Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense as etiological agents), American trypanosomiasis (also known as Chagas disease, with Trypanosoma cruzi as the etiological agent), and leishmaniasis (including cutaneous, mucocutaneous, and visceral forms, with multiple species belonging to the Leishmania genus as etiological agents) are recognized as neglected tropical diseases (NTDs) [...].

Trichosporon asahii secretes a 30-kDa aspartic peptidase.

Trichosporon asahii is a fungal opportunistic pathogen that causes superficial and deep-seated infections presenting high mortality. Very little is known about the virulence attributes produced by this fungus. Herein, aspartic peptidase production was identified in Brazilian clinical isolates of T. asahii by different methodologies. Initially, T. asahii strain 250 (from skin lesion) was inoculated in both liquid and solid culture media containing bovine serum albumin (BSA) as the sole nitrogenous source. A translucent halo around the fungal colony was observed from the 5th day of culture. The cell-free culture supernatant revealed that soluble BSA was hydrolyzed along the growth, generating low molecular mass polypeptides as observed by electrophoresis. Subsequently, the secretions from four clinical strains of T. asahii were analyzed by BSA-SDS-PAGE and a single proteolytic band of 30-kDa was detected under acidic pH at 37°C. The secreted aspartic peptidase of T. asahii efficiently cleaved the cathepsin D peptide substrate, but not the substrates with specificity to HIV-1 peptidase and rennin. The capability to cleave either cathepsin D substrate in a fluorogenic assay or BSA immobilized within a gel matrix varied according to the T. asahii isolate. T. asahii extracellular peptidase activity was strongly inhibited by pepstatin A and HIV peptidase inhibitors, classifying it as an aspartic-type peptidase. Human serum albumin, mucin, non-immune immunoglobulin G and gelatin induced, in different levels, the secretion of this aspartic peptidase. With these results, T. asahii must be included in the list of many human fungal opportunistic pathogens able to secrete an aspartic-type peptidase.

The Widespread Anti-Protozoal Action of HIV Aspartic Peptidase Inhibitors: Focus on Plasmodium spp., Leishmania spp. and Trypanosoma cruzi.

The introduction of the HIV aspartic peptidase inhibitors (HIV-PIs) has revolutionized the medical arena, since they have drastically reduced the number and the severity of opportunistic infections, including the protozoal diseases that afflict the HIV-infected individuals worldwide. HIV-PIs rapidly and profoundly diminish the viral load, which is paralleled by increase in the CD4+ T lymphocyte counts and stimulation of the survival and activation of neutrophil, monocyte and endothelial cells, culminating in a vigorous reduction in the number of deaths due to the AIDS, in the number of new cases of AIDS and in the number of hospitalization days. Many research groups around the globe are trying to decipher both the in vitro and in vivo antiprotozoal mechanisms behind the use of HIVPIs. These studies have been supported by the urgent need to discover novel active compounds able to treat incurable parasitoses, including three major neglected diseases: malaria, leishmaniasis and Chagas' disease. The present review summarizes the recent advances on the effects of HIV-PIs against Plasmodium spp., Leishmania spp. and Trypanosoma cruzi.

Virulence attributes in Brazilian clinical isolates of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic human pathogen responsible for causing a huge variety of acute and chronic infections with significant levels of morbidity and mortality. Its success as a pathogen comes from its genetic/metabolic plasticity, intrinsic/acquired antimicrobial resistance, capacity to form biofilm and expression of numerous virulence factors. Herein, we have analyzed the genetic variability, antimicrobial susceptibility as well as the production of metallo-ß-lactamases (MBLs) and virulence attributes (elastase, pyocyanin and biofilm) in 96 strains of P. aeruginosa isolated from different anatomical sites of patients attended at Brazilian hospitals. Our results revealed a great genetic variability, in which 86 distinct RAPD types (89.6% of polymorphisms) were detected. Regarding the susceptibility profile, 48 strains (50%) were resistant to the antimicrobials, as follows: 22.92% to the three tested antibiotics, 12.5% to both imipenem and meropenem, 11.46% to ceftazidime only, 2.08% to imipenem only and 1.04% to both ceftazidime and meropenem. Out of the 34 clinical strains of P. aeruginosa resistant to both imipenem and meropenem, 25 (73.53%) were MBL producers by phenotypic method while 12 (35.29%) were PCR positive for the MBL gene SPM-1. All P. aeruginosa strains produced pyocyanin, elastase and biofilm, although in different levels. Some associations were demonstrated among the susceptibility and/or production of these virulence traits with the anatomical site of strain isolation. For instance, almost all strains isolated from urine (85.71%) were resistant to the three antibiotics, while the vast majority of strains isolated from rectum (95%) and mouth (66.67%) were susceptible to all tested antibiotics. Urine isolates produced the highest pyocyanin concentration (20.15±5.65 µg/ml), while strains isolated from pleural secretion and mouth produced elevated elastase activity (1441.43±303.08 FAU) and biofilm formation (OD590 0.676±0.32), respectively. Also, MBL-positive strains produced robust biofilm compared to MBL-negative strains. Collectively, the production of site-dependent virulence factors can be highlighted as potential therapeutic targets for the treatment of infections caused by heterogeneous and resistant strains of P. aeruginosa.

Phenotypical properties associated with virulence from clinical isolates belonging to the Candida parapsilosis complex.

The production of virulence attributes in three reference strains and 11 clinical isolates primarily identified as Candida parapsilosis was evaluated. Morphological and phenotypical tests were not able to discriminate among the three species of the C. parapsilosis complex; consequently, molecular methods were applied to solve this task. After employing polymerase chain reaction-based methods, nine clinical strains were identified as C. parapsilosis sensu stricto and two as C. orthopsilosis. Protease, catalase, and hemolysin were produced by all 14 strains, while 92.9% and 78.6% of strains secreted, respectively, esterase and phytase. No phospholipase producers were detected. Mannose/glucose, N-acetylglucosamine, and sialic acid residues were detected at the surface of all strains, respectively, in high, medium, and low levels. All strains presented elevated surface hydrophobicity and similar ability to form biofilm. However, the adhesion to inert substrates and mammalian cells was extremely diverse, showing typical intrastrain variations. Overall, the strains showed (1) predilection to adhere to plastic over glass and the number of pseudohyphae was more prominent than yeasts and (2) the interaction process was slightly enhanced in macrophages than fibroblasts, with the majority of fungal cells detected inside them. Positive/negative correlations were demonstrated among the production of these virulence traits in C. parapsilosis complex.

Multiple effects of pepstatin A on Trypanosoma cruzi epimastigote forms.

Herein, we have aimed to explore the effects of pepstatin A, a powerful aspartic protease inhibitor, on Trypanosoma cruzi, the etiologic agent of Chagas' disease. Pepstatin A arrested the proliferation of epimastigotes of T. cruzi (clone Dm28c, TcI lineage), in both dose- and time-dependent manner. The IC(50) value was calculated to be 36.2 µM after 96 h of parasite-drug contact. The parasite treatment with pepstatin A resulted in significant morphological alterations, including parasites becoming round in shape, reduction (≈25%) of the parasite size, and parasites presenting parts or the whole flagellum detached from the cell body. Cell lysis was not observed, resulting in a trypanostatic effect. The treatment of different T. cruzi strains, belonging to distinct phylogenetic lineages, with pepstatin A at 36.2 µM resulted in growth inhibition as follows: 28% to Y (TcII), 45% to CL Brener (TcII), 45.4% to 4167 (Z3), and 26.4% to 3663 (Z3) strains. The hydrolysis of a cathepsin D fluorogenic substrate (7-methoxycoumarin-4-acetyl-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys(DNP)-D: -Arg-amide) by T. cruzi epimastigote extract was inhibited (≈65%) by pepstatin A at 10 µM, suggesting that an aspartic protease may be the intracellular target of this inhibitor. Curiously, pepstatin A induced an increase of 54% and 98%, respectively, in the surface expression of gp63- and calpain-related molecules in epimastigotes, but not in the cruzipain level, as well as stimulated the epimastigote-to-trypomastigote differentiation in a dose-dependent manner. However, approximately 45% of the trypomastigotes had their flagellum detached from the cell body. These results contribute to understand the possible role of aspartic proteases in the physiology of T. cruzi cells, adding new in vitro insights into the possibility of exploiting aspartic protease as promising targets to treat Chagas' disease.

Proteomic analysis of two Trypanosoma cruzi zymodeme 3 strains.

Two Trypanosoma cruzi Z3 strains, designated as 3663 and 4167, were previously isolated from insect vectors captured in the Brazilian Amazon region. These strains exhibited different infection patterns in Vero, C6/36, RAW 264.7 and HEp-2 cell lineages, in which 3663 trypomastigote form was much less infective than 4167 ones. A proteomic approach was applied to investigate the differences in the global patterns of protein expression in these two Z3 strains. Two-dimensional (2D) protein maps were generated and certain spots were identified by mass spectrometry (MS). Our analyses revealed a significant difference in the expression profile of different proteins between strains 3663 and 4167. Among them, cruzipain, an important regulator of infectivity. This data was corroborated by flow cytometry analysis using anti-cruzipain antibody. This difference could contribute to the infectivity profiles observed for each strain by in vitro assay using different cell lines.