Manganese (Mn) is an environmental contaminant and its overexposure contributes to the pathophysiological processes of numerous disorders of the central nervous system in humans with mechanisms of action not completely understood. Activation of astrocytes and the subsequent release of neurotoxic factors have been implicated to contribute to neurodegeneration. Here, we assessed the molecular basis of the effects of Mn on modulation of matrix metalloproteinases-2 (MMP-2) and -9 (MMP-9) in rat astrocyte cultures. Primary cultures of rat astrocytes were exposed to different doses of MnCl2. Culture supernatants and cell lysates were used for the detection of MMP-2 and MMP-9 levels and mRNA expression, respectively. The exposure of astrocytes to MnCl2 induced the levels and expression of MMP-9 in a dose-dependent manner. The addition of resveratrol (RSV) inhibited both levels and expression of MMP-9 in astrocytes, whereas N-acetylcysteine (NAC) and quercetin (QRC) were ineffective in inhibiting MMP-9. As a possible mechanism of Mn-induced MMP-9, we determined intracellular redox state in Mn-treated astrocytes by assessing superoxide dismutase (SOD) activity and intracellular reactive oxygen species (ROS) and found a significant increase of ROS and a decrease of SOD activity. RSV, NAC, and QRC restored the redox state. The study of the mitogen-activated protein kinase signaling pathway demonstrated that MMP-9 transcription is mainly regulated by extracellular-regulated protein kinases (ERK). Pretreatment with RSV significantly reduced ERK activation suggesting that its ability to counteract MMP-9 overexpression is due not only to a general redox balance phenomenon but also to the modulation of ERK signaling pathway.

We investigated whether polyphenols modulate the expression and activity of the enzymes gelatinases A (MMP-2) and B (MMP-9), involved in the pathogenesis of multiple sclerosis (MS). LPS-activated primary rat astrocytes were treated with the flavonoids quercetin (QRC) and cathechins [green tea extract (GTE)] and the non-flavonoids resveratrol (RSV) and tyrosol/hydroxytyrosol (Oliplus). As assessed by zymography and RT-PCR, RSV and Oliplus, but not QRC and GTE, dose-dependently inhibited the LPS-induced levels and mRNA expression of MMP-2 and MMP-9. By contrast, in cell-free systems direct inhibition of gelatinase activity in MS sera was determined by QRC and GTE, but not by RSV. Oliplus was only partially effective. Our results indicate that the flavonoids and non-flavonoids tested exert their inhibitory effect on MMPs, displaying different mechanisms of action, possibly related to their structure. Therefore, their combined use may represent a powerful tool for the down-regulation of MMPs in the course of MS.

Aflatoxin B1 (AFB1) is the most harmful mycotoxin that occurs as natural contaminant of agricultural commodities, particularly maize. Practical solutions for detoxification of contaminated staples and reduction of agricultural wastes are scarce. We investigated the capability of the white-rot and edible fungus Plerotus eryngii (king oyster mushroom) to degrade AFB1 both in vitro and in a laboratory-scale mushroom cultivation, using a substrate similar to that routinely used in mushroom farms. In malt extract broth, degradation of AFB1 (500 ng/mL) by nine isolates of P. eryngii ranged from 81 to 99% after 10 days growth, and reached 100% for all isolates after 30 days. The growth of P. eryngii on solid medium (malt extract-agar, MEA) was significantly reduced at concentrations of AFB1 500 ng/mL or higher. However, the addition of 5% wheat straw to the culture medium increased the tolerance of P. eryngii to AFB1 and no inhibition was observed at a AFB1 content of 500 ng/mL; degradation of AFB1 in MEA supplemented with 5% wheat straw and 2.5% (w/v) maize flour was 71–94% after 30 days of growth. Further, AFB1 degradation by P. eryngii strain ITEM 13681 was tested in a laboratory-scale mushroom cultivation. The mushroom growth medium contained 25% (w/w) of maize spiked with AFB1 to the final content of 128 μg/kg. Pleurotus eryngii degraded up to 86% of the AFB1 in 28 days, with no significant reduction of either biological efficiency or mushroom yield. Neither the biomass produced on the mushroom substrate nor the mature basidiocarps contained detectable levels of AFB1 or its metabolite aflatoxicol, thus ruling out the translocation of these toxins through the fungal thallus. These findings make a contribution towards the development of a novel technology for remediation of AFB1- contaminated corn through the exploitation of the degradative capability of P. eryngii and its bioconversion into high nutritional value material intended for feed production.

BackgroundMatrix metalloproteinases (MMPs) released by glial cells are important mediators of neuroinflammation and neurologic damage in HIV infection. The use of antiretroviral drugs able to combat the detrimental effect of chronic inflammation and target the exaggerated MMP activity might represent an attractive therapeutic challenge. Recent studies suggest that CCR5 antagonist maraviroc (MVC) exerts immunomodulant and anti-inflammatory activity beyond its anti-HIV properties. We investigated the in vitro effect of MVC on the activity of MMPs in astrocyte and microglia cultures.Methodology/Principal FindingsPrimary cultures of rat astrocytes and microglia were activated by exposure to phorbol myristate acetate (PMA) or lypopolysaccharide (LPS) and treated in vitro with MVC. Culture supernatants were subjected to gelatin zymography and quantitative determination of MMP-9 and MMP-2 was done by computerized scanning densitometry. MMP-9 levels were significantly elevated in culture supernatants from both LPS- and PMA-activated astrocytes and microglia in comparison to controls. The treatment with MVC significantly inhibited in a dose-dependent manner the levels and expression of MMP-9 in PMA-activated astrocytes (p<0,05) and, to a lesser extent, in PMA-activated microglia. By contrast, levels of MMP-2 did not significantly change, although a tendency to decrease was seen in PMA-activated astrocytes after treatment with MVC. The inhibition of levels and expression of MMP-9 in PMA-activated glial cells did not depend on cytotoxic effects of MVC. No inhibition of MMP-9 and MMP-2 were found in both LPS-activated astrocytes and microglia.ConclusionsThe present in vitro study suggests that CCR5 antagonist compounds, through their ability to inhibit MMP-9 expression and levels, might have a great potential for the treatment of HIV-associated neurologic damage.