Requirement of scavenger receptors for activation of the IRF-3/IFN-β/STAT-1 pathway in TLR4-mediated production of NO by LPS-activated macrophages.

Production of nitric oxide (NO) by LPS-activated macrophages is due to a complex cellular signaling initiated by TLR4 that leads to the transcription of IFN-β, which activates IRF-1 and STAT-1, as well as to the activation of NF-κB, required for iNOS transcription. High concentrations of LPS can also be uptaken by scavenger receptors (SRs), which, in concert with TLR4, leads to inflammatory responses. The mechanisms by which TLR4 and SRs interact, and the pathways activated by this interaction in macrophages are not elucidated.

spores induce autophagy and downregulate inflammatory mediators in human peripheral blood-derived macrophages.

spp. are usually considered safe and normally used as biocontrol and biofertilization. Safety for human health is evaluated by several tests that detect various effects such as allergenicity, toxicity, infectivity, and pathogenicity.

How to get away with murder: The multiple strategies employed by pathogenic protozoa to avoid complement killing.

Parasitic protozoa are eukaryotic unicellular organisms that depend on a variety of living organisms and can develop intra- and extracellularly inside their hosts. In humans, these parasites cause diseases with a significant impact on public health, such as malaria, toxoplasmosis, Chagas disease, leishmaniasis and amebiasis. The ability of a parasite in establishing a successful infection depends on a series of intricate evolutionarily selected adaptations, which include the development of molecular and cellular strategies to evade the host immune system effector mechanisms.

Measuring Intracellular Vesicle Density and Dispersion Using Fluorescence Microscopy and ImageJ/FIJI.

Cell signalling, cell secretion, and plasma membrane repair are processes that critically rely on intracellular vesicles, important components of the endocytic and secretory pathways. More specifically, the strategic distribution of intracellular vesicles is important for diverse cellular processes. The method presented here is a simple, affordable, and efficient tool to analyze the distribution of intracellular vesicles such as lysosomes, endosomes, Golgi vesicles or secretory granules under different experimental conditions.

Cell invasion by intracellular parasites - the many roads to infection.

Intracellular parasites from the genera , , , and from the phylum Microsporidia are, respectively, the causative agents of toxoplasmosis, malaria, Chagas disease, leishmaniasis and microsporidiosis, illnesses that kill millions of people around the globe. Crossing the host cell plasma membrane (PM) is an obstacle these parasites must overcome to establish themselves intracellularly and so cause diseases. The mechanisms of cell invasion are quite diverse and include (1) formation of moving junctions that drive parasites into host cells, as for the protozoans and spp.

hijacks host cell lysosomes involved in plasma membrane repair to induce invasion in fibroblasts.

Intracellular parasites of the genus are the causative agents of leishmaniasis. The disease is transmitted by the bite of a sand fly vector, which inoculates the parasite into the skin of mammalian hosts, including humans. During chronic infection the parasite lives and replicates inside phagocytic cells, notably the macrophages.

Distinct Macrophage Fates after in vitro Infection with Different Species of Leishmania: Induction of Apoptosis by Leishmania (Leishmania) amazonensis, but Not by Leishmania (Viannia) guyanensis.

Leishmania is an intracellular parasite in vertebrate hosts, including man. During infection, amastigotes replicate inside macrophages and are transmitted to healthy cells, leading to amplification of the infection. Although transfer of amastigotes from infected to healthy cells is a crucial step that may shape the outcome of the infection, it is not fully understood.

In vitro metacyclogenesis of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis clinical field isolates, as evaluated by morphology, complement resistance, and infectivity to human macrophages.

This study was designed to assess in vitro metacyclogenesis of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis clinical field isolates obtained from patient lesions (L. braziliensis IMG3 and PPS6m; L. amazonensis MAB6).

A defective TLR4 signaling for IFN-β expression is responsible for the innately lower ability of BALB/c macrophages to produce NO in response to LPS as compared to C57BL/6.

C57BL/6 mice macrophages innately produce higher levels of NO than BALB/c cells when stimulated with LPS. Here, we investigated the molecular events that account for this intrinsic differential production of NO. We found that the lower production of NO in BALB/c is not due to a subtraction of L-arginine by arginase, and correlates with a lower iNOS accumulation, which is independent of its degradation rate.

Identification of secreted virulence factors of Chromobacterium violaceum.

Chromobacterium violaceum, a component of tropical soil microbiota, is an opportunistic pathogenic bacterium that can infect humans and other animals. In addition to identifying a large number of genes that demonstrate the vast biotechnological potential of this bacterium, genome sequencing revealed several virulence factors, including different cytolysins, which can be related to its pathogenicity. Here we confirmed these predictions from genomic analyses by identifying, through mass spectrometry, proteins present in the culture supernatant of C.

Activation of Leishmania spp. leishporin: evidence that dissociation of an inhibitor not only improves its lipid-binding efficiency but also endows it with the ability to form pores.

We have previously shown that various species of Leishmania produce a lytic activity, which, in Leishmania amazonensis, is mediated by a pore-forming cytolysin, called leishporin. It is toxic for macrophages in vitro and optimally active at pH 5.0 to 5.

Reactive oxygen species and nitric oxide in cutaneous leishmaniasis.

Cutaneous leishmaniasis affects millions of people around the world. Several species of Leishmania infect mouse strains, and murine models closely reproduce the cutaneous lesions caused by the parasite in humans. Mouse models have enabled studies on the pathogenesis and effector mechanisms of host resistance to infection.

Membrane binding requirements for the cytolytic activity of Leishmania amazonensis leishporin.

To lyse cells, some pore-forming proteins need to bind to receptors on their targets. Studying the binding requirements of Leishmania amazonensis leishporin, we have shown that protease-treated erythrocytes are as sensitive to leishporin-mediated lysis as untreated cells, indicating that protein receptors are dispensable. Similarly, carbohydrate receptors do not seem to be needed, since several sugars do not inhibit leishporin-mediated hemolysis.

Identification to the species level of Lactobacillus isolated in probiotic prospecting studies of human, animal or food origin by 16S-23S rRNA restriction profiling.

Background: The accurate identification of Lactobacillus and other co-isolated bacteria during microbial ecological studies of ecosystems such as the human or animal intestinal tracts and food products is a hard task by phenotypic methods requiring additional tests such as protein and/or lipids profiling.

Results: Bacteria isolated in different probiotic prospecting studies, using de Man, Rogosa and Sharpe medium (MRS), were typed at species level by PCR amplification of 16S-23S rRNA intergenic spacers using universal primers that anneal within 16S and 23S genes, followed by restriction digestion analyses of PCR products. The set of enzymes chosen differentiates most species of Lactobacillus genus and also co-isolated bacteria such as Enterococcus, Streptococcus, Weissella, Staphylococcus, and Escherichia species.