Ismael Pretto Sauter

Lipoteichoic acid from Staphylococcus aureus increases matrix metalloproteinase 9 expression in RAW 264.7 macrophages: modulation by A2A and A2B adenosine receptors.

Peptidoglycan (PEG) and lipoteichoic acid (LTA) are the main constituents of Gram-positive bacteria cell wall and are described to modulate immune functions. Increased levels of matrix metalloproteinases (MMPs) were described in endotoxemia, suggesting that they participate to tecidual damage, multiple organs failure and vascular disfunction. Staphylococcus aureus PEG is described to increase MMPs 2 and 9 levels in plasma from rat and MMP 9 secretion by human neutrophils, however, the effect of LTA on MMPs is unknown. In this work, was evaluated the modulation of MMPs 2 and 9 expression and secretion in RAW 264.7 macrophages by LTA from S. aureus. The role of A2A and A2B adenosine receptors was also investigated. LTA increased MMP 9 expression and secretion at 12h of treatment. The modulation of MMP 9 secretion was dose dependent, with maximal effect above 1microg/ml. The inhibitor of mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway (U0126, 10microM) prevented LTA stimulation of MMP 9 secretion; however, the inhibitors of p38 (SB203580, 10microM) and Jun N-terminal kinase (JNK; SP600125, 10microM) presented any effect. A2A and A2B adenosine receptors pharmacological blockade or gene knockdown resulted in exacerbated MMP 9 secretion, while an adenosine receptors agonist inhibited LTA-stimulated MMP 9 secretion. These results suggest that LTA increased MMP 9 secretion in macrophages could be involved in complications associated to S. aureus infections. Moreover, LTA modulation of MMP 9 is dependent on MEK/ERK pathway and is regulated by A2A and A2B adenosine receptors.

High glucose increases RAW 264.7 macrophages activation by lipoteichoic acid from Staphylococcus aureus

BACKGROUND Type 2 diabetes mellitus is associated with an increased risk of cardiovascular diseases and accelerated atherosclerosis, which has been associated to hyperglycemia and chronic inflammation. Activated macrophages are described to participate in atherosclerosis due to foam cell formation and pro-inflammatory mediators production. Bacterial infections are described to accelerate atherosclerosis, moreover, gram-positive and negative bacterial DNA was described in atherosclerotic plaques. METHODS We studied the glucose modulation of RAW 264.7 macrophages activation by the gram-positive bacterial antigen lipoteichoic acid (LTA), evaluating nitrite production, tumor necrosis factor alpha secretion and matrix metalloproteinase 9 activity. RESULTS High glucose increased macrophages activation by LTA, evidenced by exacerbated nitric oxide and tumor necrosis factor alpha production, as well matrix metalloproteinase 9 secretion. CONCLUSIONS These effects could contribute to atherosclerotic risk parameters, like atherome plaque instability, and participate in chronic inflammation present in type 2 diabetes.

Amoebicidal activity of phytosynthesized silver nanoparticles and their in vitro cytotoxicity to human cells

Acanthamoeba causes infections in humans and other animals and it is important to develop treatment therapies. Jatropha curcas, Jatropha gossypifolia and Euphorbia milii plant extracts synthesized stable silver nanoparticles (AgNPs) that were relatively stable. Amoebicidal activity of J. gossypifolia, J. curcas and E. milii leaf extracts showed little effect on viability of Acanthamoeba castellanii trophozoites. Plant-synthesized AgNPs showed higher amoebicidal activity. AgNPs synthesized by J. gossypifolia extract were able to kill 74-27% of the trophozoites at concentrations of 25-1.56 μg mL(-1) . AgNPs were nontoxic at minimum inhibitory concentration with peripheral blood mononuclear cells. These results suggest biologically synthesized nanoparticles as an alternative candidate for treatment of Acanthamoeba infections.

Active metabolites produced by Penicillium chrysogenum IFL1 growing on agro-industrial residues

Microbial extracts continue to be a productive source of new molecules with biotechnological importance. Fungi of the genus Penicillium are known to produce biologically active secondary metabolites. The goal of this work is verify the production of antimicrobial metabolites by Penicillium chrysogenum IFL1 using agro-industrial residues. P. chrysogenum IFL1 produced active metabolites growing on the agro-industrial residues, grape waste and cheese whey. The 7-day cultures showed antimicrobial activities against bacteria, fungi and amoebae. The filtrate of the cheese whey culture inhibited the growth of the bacteria Staphylococcus aureus, Bacillus cereus and Pseudomonas aeruginosa, the fungus Fusarium oxysporum and the amoeba Acanthamoeba polyphaga. Due to the greater antimicrobial activity of the cheese whey culture, a footprinting profile was carried out using the ESI-MS and ESI-MS/MS techniques. The presence of penicillin G and other metabolites that have antimicrobial activity such as penicillin V and rugulosin can be suggested. P. chrysogenum IFL1 was able to produce a wide variety of antimicrobial compounds on agro-industrial residues, which makes the process ecologically friendly.

Susceptibility of Aedes aegypti (Diptera: Culicidae) to Acanthamoeba polyphaga (Sarcomastigophora: Acanthamoebidae)

To date there is no report on mosquitoes infected with free-living amoebae. For this reason, the aim of this study was to verify if Aedes aegypti could be susceptible to Acanthamoeba polyphaga under laboratory conditions, so trophozoites were offered as a unique food resource for larvae of first instar. The results show that those amoebae are able to infect and colonize the mosquito gut and could be re-isolated of all stages of the mosquito (larvae, pupae, and adults).