Activation of the Kynurenine Pathway and Production of Inflammatory Cytokines by Astrocytes and Microglia Infected With Neospora caninum.

In the central nervous system, astrocytes and microglia contribute to homeostasis, regulating the immune response to infectious agents. Neospora caninum is an obligate intracellular protozoan that infects different animal species and it is encysted in their nervous tissue while triggering an immune response modulated by glia. This study aimed to evaluate the infection of primary cultures of rat glial cells by N. caninum through the catabolites of tryptophan, the expression of inflammatory mediators and the integrity of neural tissue. Infection with this coccidium resulted in morphological and functional changes, particularly astrogliosis and microgliosis, and increased the expression of the inflammatory mediators TNF, IL1ß, IL-10, and arginase, as well as mRNA for CCL5 and CCL2, molecules involved in the CNS chemotaxis. The infection with N. caninum in glial cells also triggered the activation of the tryptophan pathway, characterized by increased kynurenine 2,3 monooxygenase (KMO) mRNA expression, and by the production of the excitotoxin quinolinic acid (QUIN). Moreover, glia-neuron co-cultures, when exposed to the secretome derived from N. caninum infected glial cells, presented greater neurons distribution and formation of neurite extensions, associated to morphological changes in astrocytes compatible with neuro-preservation. Considering that the tryptophan catabolism is associated to immune response, these findings suggest that glial activation in N. caninum infection should be responsible for modulating the inflammatory status in an attempt to restore the nervous system homeostasis, since excessive inflammatory response can cause irreversible damage to tissue preservation.

In vitro acaricide activity of Ocotea aciphylla (Nees) Mez. (Lauraceae) extracts and identification of the compounds from the active fractions.

The in vitro acaricide activity of hexane, ethyl acetate and ethanol extracts of Ocotea aciphylla leaves was investigated by means of an immersion tests using Rhipicephalus (Boophilus) microplus engorged females and larvae. All extracts were shown effective against the different stages of the parasite, and the ethanol extract (50mg/mL concentration) was the most active (more than 90% efficacy in both assays). The ethanolic extract was fractionated using column chromatography with silica gel as stationary phase to furnish several fractions that were tested against larvae of R. (B.) microplus. Three fractions showed high acaricidal activity (50mg/mL), causing between 84.2% and 100% mortality of the larvae. The anticholinesterase effect of these fractions was determined spectrophotometrically using a microtiter assay. The chemical investigation of the active fractions led to the characterization of terpenoids (cadalene 1 and squalene 2), a phenylpropanoid (dillapiole 3) and a phenolic mixture containing five proanthocyanidins (4-8) and a flavonoid(vitexin-2"-O-rhamnoside 9). Our findings suggest that the O. aciphylla has potent acaricidal activity in vitro against R. (B.) microplus, and that different secondary metabolites are responsible for this effect.