mTOR in Alzheimer disease and its earlier stages: Links to oxidative damage in the progression of this dementing disorder.

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly population and has worldwide impact. The etiology of the disease is complex and results from the confluence of multiple mechanisms ultimately leading to neuronal loss and cognitive decline. Among risk factors, aging is the most relevant and accounts for several pathogenic events that contribute to disease-specific toxic mechanisms. Accumulating evidence linked the alterations of the mammalian target of rapamycin (mTOR), a serine/threonine protein kinase playing a key role in the regulation of protein synthesis and degradation, to age-dependent cognitive decline and pathogenesis of AD. To date, growing studies demonstrated that aberrant mTOR signaling in the brain affects several pathways involved in energy metabolism, cell growth, mitochondrial function and proteostasis. Recent advances associated alterations of the mTOR pathway with the increased oxidative stress. Disruption of all these events strongly contribute to age-related cognitive decline including AD. The current review discusses the main regulatory roles of mTOR signaling network in the brain, focusing on its role in autophagy, oxidative stress and energy metabolism. Collectively, experimental data suggest that targeting mTOR in the CNS can be a valuable strategy to prevent/slow the progression of AD.

Developmental Expression and Dysregulation of miR-146a and miR-155 in Down's Syndrome and Mouse Models of Down's Syndrome and Alzheimer's Disease.

BACKGROUND: miR-146a and miR-155 are key regulators of the innate immune response. We hypothesized that an inflammation-mediated dysregulation of these miRNAs may occur in patients with Down syndrome (DS) and Alzheimer's disease (AD). METHODS: The miRNA expression patterns were investigated by in situ hybridization in developing hippocampus from controls, patients with DS and in adults with AD pathology (DS and sporadic AD; sAD). Quantitative real-time PCR was employed to evaluate the miRNA levels in the hippocampus of sAD and in mouse models of DS and AD. Both miRNAs were expressed in prenatal human hippocampus. In DS we detected increased miR-146a expression in reactive astrocytes. Increased expression of miR-146a was found in the hippocampus of sAD and negatively correlated with its target IRAK-1. APP/PS1 mice showed a significant increase in the expression of both miRNAs at 11-13 months of age as compared to WT and mice at 3 months. A negative correlation between miR-146a levels and its target TRAF6 was observed in both Ts65Dn and APP/PS1 mice. CONCLUSION: These findings suggest a possible involvement of miR-146a and miR-155 in brain development and neurodegeneration. In particular, we provide evidence of a dysregulation of these two immunomodulatory miRNAs in AD with a potential therapeutical implication, deserving further investigation.

Oxidative stress, protein modification and Alzheimer disease.

Alzheimer disease (AD) is a progressive neurodegenerative disease that affects the elderly population with complex etiology. Many hypotheses have been proposed to explain different causes of AD, but the exact mechanisms remain unclear. In this review, we focus attention on the oxidative-stress hypothesis of neurodegeneration and we discuss redox proteomics approaches to analyze post-mortem human brain from AD brain. Collectively, these studies have provided valuable insights into the molecular mechanisms involved both in the pathogenesis and progression of AD, demonstrating the impairment of numerous cellular processes such as energy production, cellular structure, signal transduction, synaptic function, mitochondrial function, cell cycle progression, and degradative systems. Each of these cellular functions normally contributes to maintain healthy neuronal homeostasis, so the deregulation of one or more of these functions could contribute to the pathology and clinical presentation of AD. In particular, we discuss the evidence demonstrating the oxidation/dysfunction of a number of enzymes specifically involved in energy metabolism that support the view that reduced glucose metabolism and loss of ATP are crucial events triggering neurodegeneration and progression of AD.

Aberrant protein phosphorylation in Alzheimer disease brain disturbs pro-survival and cell death pathways.

Protein phosphorylation of serine, threonine, and tyrosine residues is one of the most prevalent post-translational modifications fundamental in mediating diverse cellular functions in living cells. Aberrant protein phosphorylation is currently recognized as a critical step in the pathogenesis and progression of Alzheimer disease (AD). Changes in the pattern of protein phosphorylation of different brain regions are suggested to promote AD transition from a presymptomatic to a symptomatic state in response to accumulating amyloid ß-peptide (Aß). Several experimental approaches have been utilized to profile alteration of protein phosphorylation in the brain, including proteomics. Among central pathways regulated by kinases/phosphatases those involved in the activation/inhibition of both pro survival and cell death pathways play a central role in AD pathology. We discuss in detail how aberrant phosphorylation could contribute to dysregulate p53 activity and insulin-mediated signaling. Taken together these results highlight that targeted therapeutic intervention, which can restore phosphorylation homeostasis, either acting on kinases and phosphatases, conceivably may prove to be beneficial to prevent or slow the development and progression of AD.

Redox control of viral carcinogenesis: The human papillomavirus paradigm.

BACKGROUND: Cervical cancer is the second most common neoplastic disease among women worldwide. The initiating event of such cancer is the infection with certain types of human papillomavirus (HPV), a very common condition in the general population. However, the majority of HPV infections is subclinical and transitory and is resolved spontaneously. Intriguingly, viral oncogene expression, although necessary, is not per se sufficient to promote cervical cancer and other factors are involved in the progression of infected cells to the full neoplastic phenotype. In this perspective it has been suggested that the redox balance and the oxidative stress (OS) may represent interesting and under-explored candidates as promoting factors in HPV-initiated carcinogenesis. SCOPE OF THE REVIEW: The current review discusses the possible interplay between the viral mechanisms modulating cell homeostasis and redox sensitive mechanisms. Experimental data and indirect evidences are presented on the activity of viral dependent functions on i) the regulation of enzymes and compounds involved in OS; ii) the protection from oxidation of detoxifying/antiapoptotic enzymes and redox-sensitive transcription factors; iii) the suppression of apoptosis; and iv) the modulation of host microRNAs regulating genes associated with antioxidant defense. MAJOR CONCLUSIONS: The resulting tangled scenario suggests that viral hosting cells adapt their metabolisms in order to support their growth and survival in the increasingly oxidant micro-environment associated with HPV tumor initiation and progression. GENERAL SIGNIFICANCE: HPV can modulate the host cell redox homeostasis in order to favor infection and possibly tumor transformation. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Decreased expression and increased oxidation of plasma haptoglobin in Alzheimer disease: Insights from redox proteomics.

Alzheimer disease (AD) is one of the most disabling disorders of the elderly and the number of people worldwide facing dementia is expected to dramatically increase in the near future. Thus, one of the major concerns of modern society is to identify putative biomarkers that serve as a valuable early diagnostic tool to identify a subset of patients with increased risk to develop AD. An ideal biomarker should be present in blood before dementia is clinically confirmed, have high sensitivity and specificity, and be reproducible. Proteomics platforms offer a powerful strategy to reach these goals and recently have been demonstrated to be promising approaches. However, the high variability of technologies and studied populations has led to contrasting results. To increase specificity, we analyzed both protein expression profiles and oxidative modifications (carbonylation) of plasma proteins in mild cognitive impairment (MCI) and AD subjects compared with age-matched controls. Most of the proteins found to have differential levels in MCI and AD confirmed results already obtained in other cohort studies. Interestingly, we applied for the first time in MCI a redox proteomics approach to specifically identify oxidized proteins. Among them, haptoglobin, one of the most abundantly secreted glycoproteins with chaperone function, was found to be either increasingly downregulated or increasingly oxidized in AD and MCI compared with controls. We also demonstrated that in vitro oxidation of haptoglobin affects the formation of amyloid-ß fibrils, thus suggesting that oxidized haptoglobin is not able to act as an extracellular chaperone to prevent or slow formation of amyloid-ß aggregates. Another chaperone protein, α2-macroglobulin, was found to be selectively oxidized in AD patients compared with controls. Our findings suggest that alterations in proteins acting as extracellular chaperones may contribute to exacerbating amyloid-ß toxicity in the peripheral system and may be considered a putative marker of disease progression.

Antioxidants in cervical cancer: chemopreventive and chemotherapeutic effects of polyphenols.

Cervical cancer lesions are a major threat to the health of women, representing the second most common cancer worldwide. The unanimously recognized etiological factor in the causation of cervical cancer is the infection with human papilloma virus (HPV). HPV infection, although necessary, is not per se sufficient to induce cancer. Other factors have to be involved in the progression of infected cells to the full neoplastic phenotype. Oxidative stress represents an interesting and under-explored candidate as a promoting factor in HPV-initiated carcinogenesis. Oxidative stress is known to perturb the cellular redox status thus leading to alteration of gene expression responses through the activation of several redox-sensitive transcription factors. This signaling cascade affects both cell growth and cell death. The ability of naturally occurring antioxidants to modulate cellular signal transduction pathways, through the activation/repression of multiple redox-sensitive transcription factors, has been claimed for their potential therapeutic use as chemopreventive agents. Among these compounds, polyphenols have been found to be promising agents toward cervical cancer. In addition to acting as antioxidants, polyphenols display a wide variety of biological function including induction of apoptosis, growth arrest, inhibition of DNA synthesis and modulation of signal transduction pathways. They can interfere with each stage of carcinogenesis initiation, promotion and progression to prevent cancer development. The present review discusses current knowledge of the major molecular pathways, which are involved in HPV-driven cancerogenesis, and the ability of polyphenols to modulate these pathways. By acting at specific steps of viral transformation cascade, polyphenols have been demonstrated to selectively inhibit tumor cell growth and may be a promising therapeutic tool for treatment of cervical cancer. In addition, recent results obtained in clinical trials using polyphenols are also discussed. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Oxidative damage in rat brain during aging: interplay between energy and metabolic key target proteins.

Aging is characterized by a gradual and continuous loss of physiological functions and responses particularly marked in the central nervous system. Reactive oxygen species (ROS) can react with all major biological macromolecules such as carbohydrates, nucleic acids, lipids, and proteins. Since proteins are the major components of biological systems and regulate multiple cellular pathways, oxidative damage of key proteins are considered to be the principal molecular mechanisms leading to age-related deficits. Recent evidences support the notion that a decrease of energy metabolism in the brain contribute to neuronal loss and cognitive decline associated with aging. In the present study we identified selective protein targets which are oxidized in aged rats compared with adult rats. Most of the oxidatively modified proteins we found in the present study are key proteins involved in energy metabolism and ATP production. Oxidative modification of these proteins was associated with decreased enzyme activities. In addition, we also found decreased levels of thiol reducing system. Our study demonstrated that oxidative damage to specific proteins impairs energy metabolism and ATP production thus contributing to shift neuronal cells towards a more oxidized environment which ultimately might compromise multiple neuronal functions. These results further confirm that increased protein oxidation coupled with decreased reducing systems are characteristic hallmarks of aging and aging-related degenerative processes.

Redox proteomics in aging rat brain: involvement of mitochondrial reduced glutathione status and mitochondrial protein oxidation in the aging process.

Increasing evidence supports the notion that increased oxidative stress is a fundamental cause in the aging process and in neurodegenerative diseases. As a result, a decline in cognitive function is generally associated with brain aging. Reactive oxygen species (ROS) are highly reactive intermediates, which can modify proteins, nucleic acids, and polyunsaturated fatty acids, leading to neuronal damage. Because proteins are major components of biological systems and play key roles in a variety of cellular functions, oxidative damage to proteins represents a primary event observed in aging and age-related neurodegenerative disorders. In the present study, with a redox proteomics approach, we identified mitochondrial oxidatively modified proteins as a function of brain aging, specifically in those brain regions, such as cortex and hippocampus, that are commonly affected by the aging process. In all brain regions examined, many of the identified proteins were energy-related, such as pyruvate kinase, ATP synthase, aldolase, creatine kinase, and α-enolase. These alterations were associated with significant changes in both cytosolic and mitochondrial redox status in all brain regions analyzed. Our finding is in line with current literature postulating that free radical damage and decreased energy production are characteristic hallmarks of the aging process. In additon, our results further contribute to identifying common pathological pathways involved both in aging and in neurodegenerative disease development.

Protective effect of ferulic acid ethyl ester against oxidative stress mediated by UVB irradiation in human epidermal melanocytes.

UV solar radiation is the major environmental risk factor for malignant melanoma. A great effort is currently posed on the search of new compounds able to prevent or reduce UV-mediated cell damage. Ferulic acid is a natural compound recently included in the formulation of solar protecting dermatological products. The purpose of the present work was to assess whether its ethyl ester derivative, FAEE, could protect skin melanocytes from UV-induced oxidative stress and cell damage. Experiments on human melanocytes irradiated with UVB showed that FAEE treatment reduced the generation of ROS, with a net decrease of protein oxidation. FAEE treatment was accompanied by an induction of HSP70 and heme oxygenase, by a marked suppression of PARP activation and a significant suppression of apoptosis. Moreover FAEE prevented iNOS induction, thus suppressing the secondary generation of NO-derived oxidizing agents. FAEE may represent a potentially effective pharmacological approach to reduce UV radiation-induced skin damage.

Effectiveness of Lactobacillus-containing vaginal tablets in the treatment of symptomatic bacterial vaginosis.

The purpose of this study was to determine the effectiveness of Lactobacillus-containing vaginal tablets in the treatment of bacterial vaginosis (BV) and in the restoration of a healthy vaginal flora. Thirty-nine women with BV were enrolled in a double-blind, placebo-controlled clinical trial. Patients received either one Lactobacillus-containing tablet or placebo daily for 7 days. Clinical criteria, vaginal Gram stain scores and symptoms were compared with those at the initial visit and those at completion of therapy and 2 weeks later. After completion of therapy, all of the patients in the Lactobacillus-treated group (n = 18) were free of BV, showing a normal (83%) or intermediate (17%) vaginal flora, as compared with only two patients free of BV with intermediate flora (12%) from among the 16 placebo-treated women (p <0.001). Two weeks after completion of therapy, treatment was successful (score <7) in 61% of Lactobacillus-treated patients as compared with 19% of those in the placebo group (p <0.05). In the treatment group, the total number of symptomatic patients and the intensity of their symptoms, in particular vaginal malodour, were significantly reduced at both follow-up visits. The data indicate that intravaginal administration of exogenous selected strains of lactobacilli can restore a normal vaginal microbiota and be used in treating bacterial vaginosis.

In vivo protection by the xanthate tricyclodecan-9-yl-xanthogenate against amyloid beta-peptide (1-42)-induced oxidative stress.

Considerable evidence supports the role of oxidative stress in the pathogenesis of Alzheimer's disease. One hallmark of Alzheimer's disease is the accumulation of amyloid beta-peptide, which invokes a cascade of oxidative damage to neurons that can eventually result in neuronal death. Amyloid beta-peptide is the main component of senile plaques and generates free radicals ultimately leading to neuronal damage of membrane lipids, proteins and nucleic acids. Therefore, interest in the protective role of different antioxidant compounds has been growing for treatment of Alzheimer's disease and other oxidative stress-related disorders. Among different antioxidant drugs, much interest has been devoted to "thiol-delivering" compounds. Tricyclodecan-9-yl-xanthogenate is an inhibitor of phosphatidylcholine specific phospholipase C, and recent studies reported its ability to act as a glutathione-mimetic compound. In the present study, we investigate the in vivo ability of tricyclodecan-9-yl-xanthogenate to protect synaptosomes against amyloid beta-peptide-induced oxidative stress. Gerbils were injected i.p. with tricyclodecan-9-yl-xanthogenate or with saline solution, and synaptosomes were isolated from the brain. Synaptosomal preparations isolated from tricyclodecan-9-yl-xanthogenate injected gerbils and treated ex vivo with amyloid beta-peptide (1-42) showed a significant decrease of oxidative stress parameters: reactive oxygen species levels, protein oxidation (protein carbonyl and 3-nitrotyrosine levels) and lipid peroxidation (4-hydroxy-2-nonenal levels). Our results are consistent with the hypothesis that modulation of free radicals generated by amyloid beta-peptide might represent an efficient therapeutic strategy for treatment of Alzheimer's disease and other oxidative-stress related disorders. Based on the above data, we suggest that tricyclodecan-9-yl-xanthogenate is a potent antioxidant and could be of importance for the treatment of Alzheimer's disease and other oxidative stress-related disorders.

Microecology, bacterial vaginosis and probiotics: perspectives for bacteriotherapy.

Probiotics enriched in lactobacilli have been proposed as an effective and alternative tool to antibiotics for the treatment of bacterial vaginosis. The protective role of H(2)O(2)-producing lactobacilli has been strongly emphasized, but no clear-cut correlation appears to link the metabolic characteristics of administered lactobacilli with the clinical impact of probiotic therapy. On account of our review of basic mechanisms involved in bacterial vaginosis, we suggest that lactobacilli with an elevated arginine deiminase activity could have a greater therapeutic potential than strains producing only H(2)O(2). Preliminary results from our laboratory have demonstrated that treatment with probiotics containing arginine deiminase-positive lactobacilli improves clinical symptoms and is paralleled by a significant decline of polyamine levels in vaginal microenvironment. This is of outstanding interest due to the central role of polyamines in the pathogenesis of bacterial vaginosis. We should critically rethink, against this perspective, the use of probiotics for the treatment of affected women.