Aspirin modulates LPS-induced nitric oxide release in rat glial cells

Nitric oxide and prostaglandins are among the numerous substances released by activated glial cells. The aim of this study was to evaluate the effect of high-level aspirin on iNOS expression in cultured rat glial cells treated with lipopolysaccharide (LPS) as pathological stimulator. Using Western Blotting, we verified that aspirin enhanced LPS-induced iNOS expression and the presence of 15-deoxy-Delta(12,14)-prostaglandin (15d-PGJ(2)) suppressed this aspirin effect. However, the exposure of LPS-treated glial cells to aspirin resulted in a decrease of NO production. These results suggest that aspirin interferes with the cross-talk of prostaglandins and NO, blocking the endogenous negative control exerted by COX products on iNOS expression. On the other side, aspirin seems to act directly on iNOS reducing its activity, even if it does not completely block NO release by LPS-stimulated glial cells. Then aspirin could maintain homeostatic functions of NO, while it prevents toxic effects, corresponding to high NO concentrations. (c) 2005 Elsevier Ireland Ltd. All rights reserved

Effect of polyphenolic compounds on the proteolytic activities of constitutive and immuno-proteasomes

The effect of several polyphenols on the 20S proteasomes, both the constitutive and the LMP proteasomes, isolated from bovine tissues, has been investigated. Polyphenolic compounds show many biological activities such as antiviral, antibacterial, antifungal, anti-inflammatory, antimutagenic, and antiallergic activities. However, the molecular mechanism underlying these effects has not been identified. It is well established that polyphenols possess inhibitory activities on several enzymes and among them the 20S proteasome. In the present work, the ChT-L, BrAAP, PGPH, and T-L activities of the isolated constitutive and immuno-proteasomes were assayed in order to get an overall information on the polyphenols binding to the complexes. The effects of the polyphenols on the proteasomal activities were analyzed, taking into account the different subunits composition of the two complexes. Furthermore the same activities were measured on whole extracts from cancer cells exposed to EGCG and gallic acid, evaluating, also, their antioxidant action under oxidative stress. EGCG and gallic acid are able to affect the 20S proteasomes functionality, depending on the complex subunit composition and, in cell extracts, they behave both as antioxidants and proteasome effectors

20S proteasome mediated degradation of DHFR: implications in neurodegenerative disorders

The 20S proteasome is responsible for the degradation of protein substrates implicated in the onset and progression of neurodegenerative disorders, such as a-synuclein and tau protein. Here we show that the 20S proteasome isolated from bovine brain directly hydrolyzes, in vitro, the dihydrofolate reductase (DHFR), demonstrated to be involved in the pathogenesis of neurodegenerative diseases. Furthermore, the DHFR susceptibility to proteolysis is enhanced by oxidative conditions induced by peroxynitrite, mimicking the oxidative environment typical of these disorders. The results obtained suggest that the folate metabolism may be impaired by an increased degradation of DHFR, mediated by the 20S proteasome

Probiotics Supplementation Attenuates Inflammation and Oxidative Stress Induced by Chronic Sleep Restriction

Background: Insufficient sleep is a serious public health problem in modern society. It leads to increased risk of chronic diseases, and it has been frequently associated with cellular oxidative damage and widespread low-grade inflammation. Probiotics have been attracting increasing interest recently for their antioxidant and anti-inflammatory properties. Here, we tested the ability of probiotics to contrast oxidative stress and inflammation induced by sleep loss. Methods: We administered a multi-strain probiotic formulation (SLAB51) or water to normal sleeping mice and to mice exposed to 7 days of chronic sleep restriction (CSR). We quantified protein, lipid, and DNA oxidation as well as levels of gut-brain axis hormones and pro and anti-inflammatory cytokines in the brain and plasma. Furthermore, we carried out an evaluation of microglia morphology and density in the mouse cerebral cortex. Results: We found that CSR induced oxidative stress and inflammation and altered gut-brain axis hormones. SLAB51 oral administration boosted the antioxidant capacity of the brain, thus limiting the oxidative damage provoked by loss of sleep. Moreover, it positively regulated gut-brain axis hormones and reduced peripheral and brain inflammation induced by CSR. Conclusions: Probiotic supplementation can be a possible strategy to counteract oxidative stress and inflammation promoted by sleep loss

Natural polyphenols as proteasome modulators and their role as anti-cancer compounds

The purpose of this review is to discuss the effect of natural antioxidantcompounds as modulators of the 20S proteasome, a multi-enzymatic multicatalytic complex present in the cytoplasm and nucleus of eukaryotic cells and involved in several cellular activities such as cell-cycle progression, proliferation and the degradation of oxidized and damaged proteins. From this perspective, proteasome inhibition is a promising approach to anticancer therapy and such natural antioxidant effectors can be considered as potential relevant adjuvants and pharmacological models in the study of new drugs

Peroxynitrite-mediated oxidation of the C85S/C152E mutant of dihydrofolate reductase from Escherichia coli: functional and structural effects

Peroxynitrite is a potent reactive oxygen species that is believed to mediate deleterious protein modifications in a wide variety of neurodegenerative disorders. In this study, we have analysed the effects of oxidative damage induced by peroxynitrite on a cysteine-free mutant of dihydrofolate reductase (SE-DHFR), from a functional and a structural point of view. The peroxynitrite-mediated oxidation results in the inhibition, concentration-dependent, of the catalytic activity. This effect is strongly influenced by the HCO(3)(-)/CO(2) buffering system, that we observed to significantly affect the yield of protein oxidation by modulating the peroxynitrite-induced modification of aromatic residues. Because of this effect, in presence of bicarbonate system, we have observed a protection of enzymatic activity of SE-DHFR with regard to peroxynitrite. The thermodynamic stability of the oxidized protein has been studied in comparison with the non-oxidized protein by differential scanning calorimetry. The thermodynamic parameters obtained showed a decrease of stability of SE-DHFR upon oxidation, evaluated in terms of Gibbs free energy of about 1.25 kcal/mol at 25 degrees C, with respect to the non-oxidized protein. Together, these data indicate that structural and functional alterations induced by peroxynitrite may play a direct role in compromising DHFR function in multiple pathological conditions