Antioxidants may contribute in the fight against ageing: an in vitro model

Signalling Pathways Involved in Microglial Activation in Alzheimer's Disease and Potential Neuroprotective Role of Phytoconstituents

Alzheimer's disease (AD) is a commonly reported neurodegenerative disorder associated with dementia and cognitive impairment. The pathophysiology of AD comprises Aβ, hyperphosphorylated tau protein formation, abrupt cholinergic cascade, oxidative stress, neuronal apoptosis, and neuroinflammation. Recent findings have established the profound role of immunological dysfunction and microglial activation in the pathogenesis of AD. Microglial activation is a multifactorial cascade encompassing various signalling molecules and pathways such as Nrf2/NLRP3/NF-kB/p38 MAPKs/ GSK-3β. Additionally, deposited Aβ or tau protein triggers microglial activation and accelerates its pathogenesis. Currently, the FDA-approved therapeutic regimens are based on the modulation of the cholinergic system, and recently, one more drug, aducanumab, has been approved by the FDA. On the one hand, these drugs only offer symptomatic relief and not a cure for AD. Additionally, no targetedbased microglial medicines are available for treating and managing AD. On the other hand, various natural products have been explored for the possible anti-Alzheimer effect via targeting microglial activation or different targets of microglial activation. Therefore, the present review focuses on exploring the mechanism and associated signalling related to microglial activation and a detailed description of various natural products that have previously been reported with anti-Alzheimer's effect via mitigation of microglial activation. Additionally, we have discussed the various patents and clinical trials related to managing and treating AD.

Potential of Olive Oil Mill Wastewater as a Source of Polyphenols for the Treatment of Skin Disorders: A Review

Current trends toward naturally occurring compounds of therapeutic interest have contributed to an increasing number of studies on olive oil phenolics in the treatment of diseases with oxidative and inflammatory origins. Recent focus has been on olive oil wastewater, which is richer in phenolic compounds than olive oil itself. In this review, we present findings demonstrating the potential use of olive mill wastewater in dermatology. Particular attention is given to compounds with proven benefits in topical pharmacology: caffeic and ferulic acids, tyrosol and hydroxytyrosol, verbascoside, and oleuropein. The review is divided into different sections: inflammatory skin diseases, microbial effects, wound healing in addition to the antimelanoma properties of olive mill waste phenolics, and their potential in sun protection agents. There is strong evidence to support further studies into the valorization of this abundant and sustainable source of phenolic compounds for use in dermatology and dermo-cosmetic preparations.

Can phytotherapy with polyphenols serve as a powerful approach for the prevention and therapy tool of novel coronavirus disease 2019 (COVID-19)?

Much more serious than the previous severe acute respiratory syndrome (SARS) coronavirus (CoV) outbreaks, the novel SARS-CoV-2 infection has spread speedily, affecting 213 countries and causing ∼17,300,000 cases and ∼672,000 (∼+1,500/day) deaths globally (as of July 31, 2020). The potentially fatal coronavirus disease (COVID-19), caused by air droplets and airborne as the main transmission modes, clearly induces a spectrum of respiratory clinical manifestations, but it also affects the immune, gastrointestinal, hematological, nervous, and renal systems. The dramatic scale of disorders and complications arises from the inadequacy of current treatments and absence of a vaccine and specific anti-COVID-19 drugs to suppress viral replication, inflammation, and additional pathogenic conditions. This highlights the importance of understanding the SARS-CoV-2 mechanisms of actions and the urgent need of prospecting for new or alternative treatment options. The main objective of the present review is to discuss the challenging issue relative to the clinical utility of plants-derived polyphenols in fighting viral infections. Not only is the strong capacity of polyphenols highlighted in magnifying health benefits, but the underlying mechanisms are also stressed. Finally, emphasis is placed on the potential ability of polyphenols to combat SARS-CoV-2 infection via the regulation of its molecular targets of human cellular binding and replication, as well as through the resulting host inflammation, oxidative stress, and signaling pathways.

Role of PGE-2 and Other Inflammatory Mediators in Skin Aging and Their Inhibition by Topical Natural Anti-Inflammatories

Human skin aging is due to two types of aging processes, “intrinsic” (chronological) aging and “extrinsic” (external factor mediated) aging. While inflammatory events, triggered mainly by sun exposure, but also by pollutants, smoking and stress, are the principle cause of rapid extrinsic aging, inflammation also plays a key role in intrinsic aging. Inflammatory events in the skin lead to a reduction in collagen gene activity but an increase in activity of the genes for matrix metalloproteinases. Inflammation also alters proliferation rates of cells in all skin layers, causes thinning of the epidermis, a flattening of the dermo-epidermal junction, an increase in irregular pigment production, and, finally, an increased incidence of skin cancer. While a large number of inflammatory mediators, including IL-1, TNF-alpha and PGE-2, are responsible for many of these damaging effects, this review will focus primarily on the role of PGE-2 in aging. Levels of this hormone-like mediator increase quickly when skin is exposed to ultraviolet radiation (UVR), causing changes in genes needed for normal skin structure and function. Further, PGE-2 levels in the skin gradually increase with age, regardless of whether or not the skin is protected from UVR, and this smoldering inflammation causes continuous damage to the dermal matrix. Finally, and perhaps most importantly, PGE-2 is strongly linked to skin cancer. This review will focus on: (1) the role of inflammation, and particularly the role of PGE-2, in accelerating skin aging, and (2) current research on natural compounds that inhibit PGE-2 production and how these can be developed into topical products to retard or even reverse the aging process, and to prevent skin cancer.

Aging in the Male Face: Intrinsic and Extrinsic Factors

BACKGROUND

Gender is one of the most significant factors that influence facial anatomy and behavior, both key factors in the aging process.

OBJECTIVE

To review male facial anatomy, physiology, and behavior and how it contributes to sexual dimorphism in facial aging.

METHODS

A MEDLINE search was performed for publications on gender differences in facial anatomy, aging, cutaneous physiology, and behavior.

RESULTS

There are differences in both intrinsic and extrinsic aging factors in men. Men have a thicker epidermis and dermis with more active cutaneous appendages including hair growth. Male skin has a reduced antioxidant capacity and increased ultraviolet-induced immunosuppression. The male face is larger and has a unique square shape with less subcutaneous soft tissue, especially at the medial cheek. Men are also more prone to smoking and exhibiting poor sun-protective behavior. The differences in intrinsic and extrinsic aging factors contribute to poor facial aging in men. Men develop more severe rhytides in a unique pattern, show increased periocular aging changes, and are more prone to hair loss.

CONCLUSION

This review provides insight into the factors contributing to accelerated male facial aging. Understanding gender differences in aging will help physicians tailor cosmetic treatments for men and minimize extrinsic aging factors.

The Use of Grape Seed Byproducts Rich in Flavonoids to Improve the Antioxidant Potential of Red Wines

The influence of adding seeds from grape pomace during Syrah wine fermentation in a warm climate has been studied. Seeds of Pedro Ximenez variety were rich in phenolic compounds, mainly flavonoids such as catechin and procyanidins. Changes in total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of red wines were observed. These changes depended on the vinification stage and the amount of seeds (SW: 450 g or DW: 900 g seeds/150 kg grapes) applied. In general, antioxidant activity was greater when a simple dose (SW) was considered. Results indicate that seeds rich in flavonoids could be used as wine additives, which could improve the antioxidant potential of red wines in a warm climate.

Ultraviolet Radiation-Induced Skin Aging: The Role of DNA Damage and Oxidative Stress in Epidermal Stem Cell Damage Mediated Skin Aging

Skin is the largest human organ. Skin continually reconstructs itself to ensure its viability, integrity, and ability to provide protection for the body. Some areas of skin are continuously exposed to a variety of environmental stressors that can inflict direct and indirect damage to skin cell DNA. Skin homeostasis is maintained by mesenchymal stem cells in inner layer dermis and epidermal stem cells (ESCs) in the outer layer epidermis. Reduction of skin stem cell number and function has been linked to impaired skin homeostasis (e.g., skin premature aging and skin cancers). Skin stem cells, with self-renewal capability and multipotency, are frequently affected by environment. Ultraviolet radiation (UVR), a major cause of stem cell DNA damage, can contribute to depletion of stem cells (ESCs and mesenchymal stem cells) and damage of stem cell niche, eventually leading to photoinduced skin aging. In this review, we discuss the role of UV-induced DNA damage and oxidative stress in the skin stem cell aging in order to gain insights into the pathogenesis and develop a way to reduce photoaging of skin cells.

Stem cells and aberrant signaling of molecular systems in skin aging

The skin is the body's largest organ and it is able to self-repair throughout an individual's life. With advanced age, skin is prone to degenerate in response to damage. Although cosmetic surgery has been widely adopted to rejuvinate skin, we are far from a clear understanding of the mechanisms responsible for skin aging. Recently, adult skin-resident stem/progenitor cells, growth arrest, senescence or apoptotic death and dysfunction caused by alterations in key signaling genes, such as Ras/Raf/MEK/ERK, PI3K/Akt-kinases, Wnt, p21 and p53, have been shown to play a vital role in skin regeneration. Simultaneously, enhanced telomere attrition, hormone exhaustion, oxidative stress, genetic events and ultraviolet radiation exposure that result in severe DNA damage, genomic instability and epigenetic mutations also contribute to skin aging. Therefore, cell replacement and targeting of the molecular systems found in skin hold great promise for controlling or even curing skin aging.

Hydrogen peroxide generated by DUOX1 regulates the expression levels of specific differentiation markers in normal human keratinocytes

BACKGROUND

Recent studies have demonstrated that the production of reactive oxygen species (ROS) itself plays an indispensable role in the process of differentiation in various tissues. However, it is unclear whether ROS have an effect on the differentiation of keratinocytes essential for the development of the epidermal permeability barrier.

OBJECTIVE

The aim of the study is to determine a major H2O2-generating source by ionomycin in normal human keratinocytes (NHKs), and elucidate the physiological role of H2O2 generated by identified dual oxidase 1 (DUOX1) on differentiation markers of NHKs.

METHODS

To detect H2O2 level generated by ionomycin in NHKs, luminal-HRP assays are performed. To examine the effects of DUOX1 on differentiation markers of NHKs, analysis of Q-RT-PCR, siRNA knockdown, and Western blot analysis were performed.

RESULTS

We found that levels of H2O2 generated by ionomycin, a Ca(2+) signal inducer, showed Ca(2+) dependence manner. In addition, DPI, an inhibitor of NOXes, significantly reversed the ionomycin-induced H2O2 level, and inhibited the mRNA expression levels of keratin 1, keratin 10, and filaggrin compared with other ROS generating system inhibitors. Interestingly, we demonstrated that extracellular Ca(2+) markedly up-regulated mRNA expression levels of DUOX1 among NADPH oxidase (NOX) isoforms. Knockdown of DUOX1 by RNA interference (RNAi) in NHKs significantly antagonized an increase of ionomycin-induced H2O2 level, and specifically decreased the expressions of several keratinocyte differentiation markers such as keratin 1, transglutaminase 3, desmoglein 1, and aquaporin 9. In addition, we also found that formation of cornified envelope was significantly reduced in DUOX1-knockdown NHKs.

CONCLUSION

These results suggest that DUOX1 is the major H2O2-producing source in NHKs stimulated with Ca(2+), and plays a significant role in regulating the expression of specific markers necessary for the normal differentiation of keratinocytes.

The role of cytokines in skin aging

Cutaneous aging is one of the major noticeable menopausal complications that most women want to fight in their quest for an eternally youthful skin appearance. It may contribute to some maladies that occur in aging which, despite not being life-threatening, affect the well-being, psychological state and quality of life of aged women. Skin aging is mainly affected by three factors: chronological aging, decreased levels of estrogen after menopause, and environmental factors. Aged skin is characterized by a decrease in collagen content and skin thickness which result in dry, wrinkled skin that is easily bruised and takes a longer time to heal. Cytokines play a crucial role in the manifestation of these features of old skin. The pro-inflammatory cytokine tumor necrosis factor-alpha inhibits collagen synthesis and enhances collagen degradation by increasing the production of MMP-9. It also lowers the skin immunity and thus increases the risk of cutaneous infections in old age. Deranged levels of several interleukins and interferons also affect the aging process. The high level of CCN1 protein in aged skin gives dermal fibroblasts an 'age-associated secretory phenotype' that causes abnormal homeostasis of skin collagen and leads to the loss of the function and integrity of skin. Further research is required especially to establish the role of cytokines in the treatment of cutaneous aging.

Glutathione efflux and cell death

SIGNIFICANCE

Glutathione (GSH) depletion is a central signaling event that regulates the activation of cell death pathways. GSH depletion is often taken as a marker of oxidative stress and thus, as a consequence of its antioxidant properties scavenging reactive species of both oxygen and nitrogen (ROS/RNS).

RECENT ADVANCES

There is increasing evidence demonstrating that GSH loss is an active phenomenon regulating the redox signaling events modulating cell death activation and progression.

CRITICAL ISSUES

In this work, we review the role of GSH depletion by its efflux, as an important event regulating alterations in the cellular redox balance during cell death independent from oxidative stress and ROS/RNS formation. We discuss the mechanisms involved in GSH efflux during cell death progression and the redox signaling events by which GSH depletion regulates the activation of the cell death machinery.

FUTURE DIRECTIONS

The evidence summarized here clearly places GSH transport as a central mechanism mediating redox signaling during cell death progression. Future studies should be directed toward identifying the molecular identity of GSH transporters mediating GSH extrusion during cell death, and addressing the lack of sensitive approaches to quantify GSH efflux.

Effects of radical scavenger protein from broad beans on glutathione status in human lung fibroblasts

OBJECTIVE

Human diploid cells are more susceptible to oxidative stress at late passage than at early passage, presumably because of the decrease in cellular-reduced glutathione (GSH) concentration. Water-soluble protein (WSP) from broad beans scavenges free radicals. The effects of WSP on the glutathione system were examined in PDL 20 (early passage) and PDL 50 (late passage) human lung fibroblasts (TIG-1).

METHODS

To determine cytosolic glutathione peroxidase (GSH-Px) activities, glutathione reductase (GR) activities, oxidized glutathione (GSSG) concentrations, and GSSG/reduced glutathione (GSH) ratios, WSP and hydrocortisone (HC) treatments of TIG-1 cells (PDL 20→50 and PDL 50→75) were performed for 40 days. We also investigated the GSSG concentrations and GR activities in PDL 20 cells that were continuously treated with WSP until PDL 39 and 55.

RESULTS

GSSG concentrations decreased in WSP- and HC-treated PDL 50→75 cells. The GSSG/GSH ratios in PDL 50→75 cells became low after the treatments. Increases in GR activities were observed in treated PDL 50→75 cells. The decline in the GSSG concentration of PDL 50→75 cells correlated with the increase in GR activity. The GSSG levels in control cells were higher following cellular age, whereas the levels in treated cells were lower than those in the control. The studies on cellular age-related changes indicated that greater increases in GR activity were found in treated cells than in the control.

CONCLUSION

These results indicated that WSP influences the GSSG concentration that is associated with cellular aging, but the mechanism of GSSG reduction by WSP remains unknown. The enhancement of glutathione status following WSP treatment may be related to the delay in the cellular aging.

17β-estradiol protects human skin fibroblasts and keratinocytes against oxidative damage

BACKGROUND

Reactive oxygen species (ROS) cause severe damage to extracellular matrix and to molecular structure of DNA, proteins and lipids. Accumulation of these molecular changes apparently constitutes the basis of cell ageing. 17b-estradiol (E2) has a key role in skin ageing homeostasis as evidenced by the accelerated decline in skin appearance seen in the perimenopausal years. Oestrogens improve many aspects of the skin such as skin thickness, vascularization, collagen content and quality. Despite these clinical evidences, the effects of oestrogens on skin at the cellular level need further clarification.

MATERIALS AND METHODS

HaCaT and human fibroblasts were cultured under various conditions with E2 and H2 O2 ; then were subjected to immunofluorescence and western blot analysis. Lipoperoxidation was investigated using BODIPY.

RESULTS

In human fibroblasts oxidative stress decreases procollagen-I synthesis, while E2 significantly increases it. Fibroblasts and HaCaT cells viability in the presence of E2 demonstrates a notably increased resistance to H2 O2 effects. Furthermore E2 is able to counteract H2 O2 -mediated lipoperoxidation and DNA oxidative damage in skin cells.

DISCUSSION

In this study we highlight that the menopause-associated oestrogens decline is involved in reduced collagen production and that E2 could counteract the detrimental effects of oxidative stress on the dermal compartment during skin aging. Furthermore, our data show that physiological concentrations of oestrogens are able to interfere with ROS-mediated cell viability reduction and to protect human skin cells against oxidative damage to cellular membranes and nucleic acids structure.

CONCLUSION

Our experimental data show that the presence of 17β-estradiol may protect skin cells against oxidative damage and that the dramatic lowering of oestrogen levels during menopause, could render skin more susceptible to oxidative damage.

Hesperidin-mediated expression of Nrf2 and upregulation of antioxidant status in senescent rat heart

OBJECTIVES

Oxidative stress is recognized as a key element responsible for the development of age-related pathologies. A declining endogenous defence system during senescence dictates the need for supplementation with exogenous antioxidants through diet. Hesperidin is a naturally occurring flavonone present in citrus fruits and has been shown to have many biological properties, including antioxidant activity. We investigated whether hesperidin supplementation could be valuable in protecting cardiac tissue of aged rats against age-related increase in oxidative stress, as well as the mechanism by which it can boost the antioxidant status of the cell.

METHODS

The activity of antioxidant enzymes, mRNA expression of Nrf2, protein levels of superoxide dismutase and catalase were measured using standard protocols.

KEY FINDINGS

Hesperidin treatment effectively protected aged rat heart by increasing the activity of enzymic antioxidants. Hesperidin upregulated the protein levels of nuclear factor erythroid 2-related factor 2, which is responsible for maintaining the antioxidant status of the cell.

CONCLUSIONS

Hesperidin could be useful in protecting cardiomyocytes against age-related increase in oxidative stress mediated by Nrf2 upregulation.

Hormonal therapy of intrinsic aging

Intrinsic skin aging represents the biological clock of the skin cells per se and reflects the reduction processes that are common in internal organs. The reduced secretion of the pituitary, adrenal glands, and the gonads contributes to characteristic aging-associated body and skin phenotypes as well as behavior patterns. Our knowledge of whether there is a direct or indirect connection between hormonal deficiency and skin aging still remains limited. In females, serum levels of 17β-estradiol, dehydroepiandrosterone, progesterone, growth hormone (GH), and its downstream hormone insulin-like growth factor I (IGF-I) are significantly decreased with increasing age. In males, serum levels of GH and IGF-I decrease significantly, whereas it can decrease in late age in a part of the population. Hormones have been shown to influence skin morphology and functions, skin permeability, wound healing, sebaceous lipogenesis, and the metabolism of skin cells. Prevention of skin aging by estrogen/progesterone replacement therapy is effective if administered early after menopause and influences intrinsically aged skin only. Vitamin D substitution and antioxidant treatment may also be beneficial. Replacement therapy with androgens, GH, IGF-I, progesterone, melatonin, cortisol, and thyroid hormones still remains controversial.

MicroRNA-34a regulation of endothelial senescence

Endothelial senescence is thought to play a role in cardiovascular diseases such as atherosclerosis. We hypothesized that endothelial microRNAs (miRNAs) regulate endothelial survival and senescence. We found that miR-34a is highly expressed in primary endothelial cells. We observed that miR-34a expression increases in senescent human umbilical cord vein endothelial cells (HUVEC) and in heart and spleen of older mice. MiR-34a over-expression induces endothelial cell senescence and also suppresses cell proliferation by inhibiting cell cycle progression. Searching for how miR-34a affects senescence, we discovered that SIRT1 is a target of miR-34a. Over-expressing miR-34a inhibits SIRT1 protein expression, and knocking down miR-34a enhances SIRT1 expression. MiR-34a triggers endothelial senescence in part through SIRT1, since forced expression of SIRT1 blocks the ability of miR-34a to induce senescence. Our data suggest that miR-34a contributes to endothelial senescence through suppression of SIRT1.

Ginsenoside-Rd attenuates oxidative damage related to aging in senescence-accelerated mice

Among the various theories of the aging process, the free radical theory, which proposes that deleterious actions of free radicals are responsible for the functional deterioration associated with aging, has received widespread attention. The theory suggests that enhancement of the antioxidative defence system to attenuate free-radical-induced damage will counteract the aging process. We used senescence-accelerated mice (SAM) to investigate the relationship between aging and the antioxidative defence system and evaluated the effects of ginsenoside-Rd, the saponin from ginseng, by measuring antioxidative defence system parameters, including the glutathione (GSH)/glutathione disulfide (GSSG) redox status, antioxidative enzyme activity and level of lipid peroxidation. SAM at 11 months of age (old SAM) showed a significantly lower hepatic GSH/GSSG ratio, due to decreased GSH and increased GSSG levels, than SAM at 5 weeks of age (young SAM). However, the administration of ginsenoside-Rd at a dose of 1 or 5 mg kg−1 daily for 30 days to 10-month-old SAM significantly increased GSH, but decreased GSSG, resulting in elevation of the GSH/GSSG ratio. In addition, ginsenoside-Rd increased the activity of glutathione peroxidase (GSH-Px) and glutathione reductase that were both significantly lower in old SAM than in young SAM. This suggests that ginsenoside-Rd could play a crucial role in enhancing the defence system through regulation of the GSH/GSSG redox status. Moreover, decreases in the superoxide dismutase (SOD) and catalase activity in old SAM compared with young SAM were also revealed, indicating that the aging process resulted in suppression of the antioxidative defence system. However, ginsenoside-Rd did not affect SOD and catalase activity. As catalase is localized in peroxisome granules and GSH-Px is present in the cytoplasm and mitochondrial matrix, the site of ginsenoside-Rd action may be the cytoplasm and mitochondrial matrix. Furthermore, the serum and liver malondialdehyde levels, indicators of lipid peroxidation, were elevated with aging, while ginsenoside-Rd inhibited lipid peroxidation. This study indicates that the aging process leads to suppression of the antioxidative defence system and accumulation of lipid peroxidation products, while ginsenoside-Rd attenuates the oxidative damage, which may be responsible for the intervention of GSH/GSSG redox status.

Protective mechanism of quercetin and rutin using glutathione metabolism on HO-induced oxidative stress in HepG2 cells

The levels of cellular glutathione (GSH) and reactive oxygen species (ROS) simultaneously determined by fluorometric measurement, may provide important information on pro-oxidative and antioxidative balance. The dual effect of quercetin antioxidant and pro-oxidant activity was proposed from different studies. Our study demonstrated that quercetin acted as an antioxidant in HepG2 cells when cells were treated with 10 and 100 micromol/L quercetin for 30 min, but quercetin acted as a pro-oxidant when cells were incubated at 100 micromol/L quercetin for longer periods (12 and 24 h). Quercetin is capable of reducing H(2)O(2)-induced oxidative stress of HepG2 cells through different mechanisms, such as detoxification of H(2)O(2,) inhibition of ROS generation, and removal of generated ROS. We find that quercetin can block ROS generation through Fenton reaction to produce hydroxyl radicals by chelating with transition metal ions such as Cu(2+). Evidence that quercetin might exert an antioxidant effect by changing generated ROS into less reactive ROS suggests that when quercetin reacts with ROS, it becomes oxidized, which is less harmful but still reactive, and the oxidized quercetin interacts with thiol compounds as reduced GSH to return to the parent compound quercetin. In contrast, the prolonged treatment of quercetin in high concentrations (100 micromol/L) shows that quercetin may act as a pro-oxidant rather than as an antioxidant, resulting in cell death (apoptosis).

Balance and Posture in the Elderly: An Analysis of a Sensorimotor Rehabilitation Protocol

Regular training programs are a concrete means to prevent and/or reduce functional decline due to aging. A multisensory training approach seems to obtain better results in the elderly with regard to both balance and quality of life. Forty subjects (age 65±10 years, height 165±4 cm, weight 73.0±4.6 kg) were randomized into two groups (GrHu and GrCl). Participants in the GrHu group received 3 months of balance and postural training, 3 sessions per week, with the use of a multisensory training approach. Those in the GrCl group received 3 months of training with a classical rehabilitation protocol that included isotonic training for the lower limbs and spine. With regard to walking, there was an improvement in step symmetry for participants in the GrHu group compared to baseline (0.93±0.09 vs. 0.84±0.1; p<0.05). Further, all subjects in the GrHu group showed a significant reduction in the energy used during a 4-min walk. Analysis of stabilometry data also showed a significant improvement in balance for those in the GrHu group, which was independent of age or gender. The multisensory training approach yields an improvement of balance in the elderly, which reduces the risk of falls. The observed improvement is significantly greater than that seen with the classical training program.

Alpha-lipoic acid inhibits tumor necrosis factor-induced remodeling and weakening of human fetal membranes

Untimely rupture of the fetal membranes (FMs) is a major precipitant of preterm birth. Although the mechanism of FM weakening leading to rupture is not completely understood, proinflammatory cytokines, including tumor necrosis factor (TNF) and interleukin 1 beta (IL1B), have been shown to weaken FMs concomitant with the induction of reactive oxygen species, collagen remodeling, and prostaglandin release. We hypothesized that alpha-lipoic acid, a dietary antioxidant, may block the effect of inflammatory mediators and thereby inhibit FM weakening. Full-thickness FM fragments were incubated with control media or TNF, with or without alpha-lipoic acid pretreatment. Fetal membrane rupture strength and the release of matrix metalloproteinase 9 (MMP9) and prostaglandin E(2) (PGE(2)) from the full-thickness FM fragments were determined. The two constituent cell populations in amnion, the mechanically strongest FM component, were similarly examined. Amnion epithelial and mesenchymal cells were treated with TNF or IL1B, with or without alpha-lipoic acid pretreatment. MMP9 and PGE(2) were analyzed by ELISA, Western blot, and zymography. TNF decreased FM rupture strength 50% while increasing MMP9 and PGE(2) release. Lipoic acid inhibited these TNF-induced effects. Lipoic acid pretreatment also inhibited TNF- and IL1B-induced increases in MMP9 protein activity and release in amnion epithelial cells, as well as PGE(2) increases in both amnion epithelial and mesenchymal cells. In summary, lipoic acid pretreatment inhibited TNF-induced weakening of FM and cytokine-induced MMP9 and PGE(2) in both intact FM and amnion cells. We speculate that dietary supplementation with alpha-lipoic acid might prove clinically useful in prevention of preterm premature rupture of fetal membranes.

Quercetin: potentials in the prevention and therapy of disease

PURPOSE OF REVIEW

Quercetin is discussed since several decades as a multipotent bioflavonoid with great potential for the prevention and treatment of disease. In the current review, we present the most recent findings on quercetin with regard to the pharmacology, the in-vitro and in-vivo effects in different cell systems and animal models, and the clinical effects in humans.

RECENT FINDINGS

Quercetin bioavailability has been underestimated in the past and can be improved by food matrix components or particular delivery forms. Among the biological effects of particular relevance, the antihypertensive effects of quercetin in humans and the improvement of endothelial function should be emphasized. Together with its antithrombotic and anti-inflammatory effects, the latter mainly mediated through the inhibition of cytokines and nitric oxide, quercetin is a candidate for preventing obesity-related diseases. Most exiting are the findings that quercetin enhances physical power by yet unclear mechanisms. The anti-infectious and immunomodulatory activities of quercetin might be related to this effect.

SUMMARY

Quercetin is a most promising compound for disease prevention and therapy; however, many of the effects still need confirmation by human intervention trials.

The skin as a mirror of the aging process in the human organism--state of the art and results of the aging research in the German National Genome Research Network 2 (NGFN-2)

As our society is growing older, the consequences of aging have begun to gain particular attention. Improvement of quality of life at old age and prevention of age-associated diseases have become the main focus of the aging research. The process of aging in humans is complex and underlies multiple influences, with the probable involvement of heritable and various environmental factors. In particular, hormones are decisively involved in the generation of aging. Over time, important circulating hormones decline due to a reduced secretion of the pituitary, the adrenal glands and the gonads or due to an intercurrent disease. Among them, serum levels of growth factors and sexual steroids show significant aging-associated changes. Within the scope of the Explorative Project 'Genetic aetiology of human longevity' supported by the German National Genome Research Network 2 (NGFN-2) an in vitro model of human hormonal aging has been developed. Human SZ95 sebocytes were maintained under a hormone-substituted environment consisting of growth factors and sexual steroids in concentrations corresponding to those circulating in 20- and in 60-year-old women. Eight hundred and ninety-nine genes showed a differential expression in SZ95 sebocytes maintained under the 20- and 60-year-old hormone mixture, respectively. Among them genes were regulated which are involved in biological processes which are all hallmarks of aging. The most significantly altered signaling pathway identified was that of the transforming growth factor-beta (TGF-beta). A disturbed function of this cascade has been associated with tumorigenesis, i.e. in pancreatic, prostate, intestine, breast, and uterine cancer. Interestingly, genes expressed in signaling pathways operative in age-associated diseases such as Huntington's disease (HD), dentatorubral-pallidoluysian atrophy (DRPLA), and amyotrophic lateral sclerosis (ALS) were also identified. These data demonstrate that skin and its appendages may represent an adequate model for aging research. Hormones interact in a complex fashion, and aging may be partly attributed to the changes in their circulating blood levels. Furthermore, a disturbed hormone status may partially act towards the manifestation of neurodegenerative diseases. Thus, these results could be a basis for an integrated and interdisciplinary approach to the analysis of the aging process.

William J. Cunliffe Scientific Awards. Characteristics and pathomechanisms of endogenously aged skin

The skin, being in direct contact with several environmental factors (e.g. UV irradiation), does not only undergo endogenous aging, which has to do with the 'biological clock' of the skin cells per se, but also exogenous aging. While exogenous skin aging has been extensively studied, the pathomechanisms of endogenous skin aging remain far less clear. Endogenous skin aging reflects reduction processes, which are common in internal organs. These processes include cellular senescence and decreased proliferative capacity, decrease in cellular DNA repair capacity and chromosomal abnormalities, loss of telomeres, point mutations of extranuclear mtDNA, oxidative stress and gene mutations. As a consequence, aged skin in nonexposed areas shows typical characteristics including fine wrinkles, dryness, sallowness and loss of elasticity. Recent data have illustrated that lack of hormones occurring with age may also contribute to the aging phenotype. Improvement of epidermal skin moisture, elasticity and skin thickness, enhanced production of surface lipids, reduction of wrinkle depth, restoration of collagen fibers and increase of the collagen III/I ratio have been reported after hormone replacement therapy or local estrogen treatment in postmenopausal women. Furthermore, an in vitro model of endogenous skin aging consisting of human SZ95 sebocytes which were incubated under a hormone-substituted environment illustrated that hormones at age- and sex-specific levels were able to alter the development of cells by regulating their transcriptome. In conclusion, among other factors the hormone environment plays a distinct role in the generation of aged skin.

Identification of major phenolic compounds of Chinese water chestnut and their antioxidant activity

Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (-)-gallocatechin gallate, (-)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions.

Oxidative stress induces premature senescence by stimulating caveolin-1 gene transcription through p38 mitogen-activated protein kinase/Sp1-mediated activation of two GC-rich promoter elements

Cellular senescence is believed to represent a natural tumor suppressor mechanism. We have previously shown that up-regulation of caveolin-1 was required for oxidative stress-induced premature senescence in fibroblasts. However, the molecular mechanisms underlying caveolin-1 up-regulation in senescent cells remain unknown. Here, we show that subcytotoxic oxidative stress generated by hydrogen peroxide application promotes premature senescence and stimulates the activity of a (-1,296) caveolin-1 promoter reporter gene construct in fibroblasts. Functional deletion analysis mapped the oxidative stress response elements of the mouse caveolin-1 promoter to the sequences -244/-222 and -124/-101. The hydrogen peroxide-mediated activation of both Cav-1 (-244/-222) and Cav-1 (-124/-101) was prevented by the antioxidant quercetin. Combination of electrophoretic mobility shift studies, chromatin immunoprecipitation analysis, Sp1 overexpression experiments, as well as promoter mutagenesis identifies enhanced Sp1 binding to two GC-boxes at -238/-231 and -118/-106 as the core mechanism of oxidative stress-triggered caveolin-1 transactivation. In addition, signaling studies show p38 mitogen-activated protein kinase (MAPK) as the upstream regulator of Sp1-mediated activation of the caveolin-1 promoter following oxidative stress. Inhibition of p38 MAPK prevents the oxidant-induced Sp1-mediated up-regulation of caveolin-1 protein expression and development of premature senescence. Finally, we show that oxidative stress induces p38-mediated up-regulation of caveolin-1 and premature senescence in normal human mammary epithelial cells but not in MCF-7 breast cancer cells, which do not express caveolin-1 and undergo apoptosis. This study delineates for the first time the molecular mechanisms that modulate caveolin-1 gene transcription upon oxidative stress and brings new insights into the redox control of cellular senescence in both normal and cancer cells.

Improvement of leukocyte functions in prematurely aging mice after five weeks of diet supplementation with polyphenol-rich cereals

OBJECTIVE

We investigated the beneficial effects of diet supplementation with two types of cereals naturally rich in polyphenolic compounds on several functions of peritoneal leukocytes from prematurely aging mice (PAM).

METHODS

Two-hundred sixty healthy mice, 8 wk of age, were recruited and their behavioral responses were tested in a simple T-maze to identify PAM. Then the mice were fed a diet supplemented with 20% (wt/wt) of two different cereal fractions, named B (wheat germ) and C (buckwheat flour), rich in polyphenols (gallic acid, catechin, p-hydroxybenzoic acid, vanillic acid, p-coumaric acid, sinapic acid, ferulic acid, quercetin, and rutin), or a standard diet (controls) for 5 wk. Several parameters of innate (adherence to tissues, chemotaxis, phagocytosis, microbicidal capacity, and natural killer activity) and acquired immune (lymphoproliferation and interleukin-2 release) responses were measured.

RESULTS

The PAM control group showed worse immune functions (P < 0.001 to 0.05) compared with the non-PAM control group. The PAM group that received cereal B showed increases in phagocytosis (P < 0.01), microbicidal activity (P < 0.001 to 0.01), natural killer activity (P < 0.001) and lymphoproliferation in response to lipopolysaccharide (P < 0.01) and interleukin-2 release (P < 0.001), and the PAM group that received cereal C showed a similar pattern, with increases in macrophage chemotaxis (P < 0.01), phagocytosis (P < 0.01), microbicidal activity (P < 0.001 to 0.01), natural killer activity (P < 0.01), lymphoproliferative response to concanavalin A and lipopolysaccharide (P < 0.001), and interleukin-2 release (P < 0.001).

CONCLUSIONS

Dietary supplementation with polyphenol-rich cereals appears to have a protective effect on immune cell functions in mice with premature senescence. Thus, regular intake of these compounds could delay normal aging and improve quality of life.

Zinc, oxidative stress, genetic background and immunosenescence: implications for healthy ageing

The relevance of zinc for proper functioning of the entire immune system is already well documented. However, the identification of individuals who really need zinc supplementation is still debated in view of the fact that excessive zinc may also be toxic. The risk of developing zinc deficiency in people from industrialized countries is relatively low, except for elderly subjects where zinc intake may be suboptimal and inflammation is chronic. Thus, the role of zinc on the immune system and on the health of European elderly people is becoming of paramount importance, considering also that the elderly population is rapidly increasing. In particular, the factors contributing to and the biochemical markers of zinc deficiency in the elderly are still remain to be established. Epidemiological, functional, and genetic studies aimed at formulating a rationale for the promotion of healthy ageing through zinc supplementation was the subject of an International Conference held in Madrid from 11-13 February 2006 (3rd ZincAge Meeting) at the CNIO Institute (local organizer: Maria Blasco, partner of ZincAge).

Protein kinase C modulates the pulmonary inflammatory response in acute pancreatitis

The present study aims at evaluating the role of protein kinase C (PKC) in the development of acute lung injury, production of inflammatory mediators and expression of adhesion molecules on leukocytes after induction of acute pancreatitis (AP). AP was induced by the intraductal infusion of 5% sodium taurodeoxycholate in the rat. The animals had the PKC inhibitor polymyxin B administered intraperitoneally 30min prior to induction of AP. Levels of protein content, protease activity, cytokines and chemokines in bronchoalveolar lavage fluid (BALF) were assessed 1 and 6h after AP induction. Adhesion molecule expression on leukocytes were measured by flowcytometry. Pretreatment with polymyxin B prevented against acute pancreatitis-induced lung injury and the otherwise occurring increases in TNF-alpha, IL-1beta, MCP-1 and IL-10, as well as against the decreases in IL-2, IFNgamma and TIMP-1, decreased protease activity and down-regulation of CD31, CD54 and CD62L on recruited neutrophils and macrophages in BALF. The results indicate that the leukocyte response in acute pancreatitis vary depending on leukocyte subpopulation. It seems that activation of the PKC signalling pathway may play an important role in pancreatitis-associated lung injury.

Photoprotection by topical application of Achyrocline satureioides ('Marcela')

It has been demonstrated that the use of topical antioxidants can contribute to controling the free radicals excess produced by ultraviolet (UV) irradiation of the skin, being beneficial for processes such as photo aging and eventually cancer. Some plant extracts, particularly because of their polyphenolic constituents, can be beneficial for skin photo damage. Plant extracts of Achyrocline satureioides (AS) and Epilobium parviflorum (EP), potent antioxidant medicinal plants, were mixed with a cosmetic base and applied to the back skin of rabbits. Afterwards the skin was exposed to 1 h of UV irradiation from a known source. The production of the hydroxyl (OH.) radical was assessed in the skin after UV by measuring 2,3-dyhydroxybenzoic acid (2,3-DHBA), produced by the hydroxylation of sodium salicylate, previously injected intracutaneously (i.c.) in the irradiated areas. The UV provoked a marked increase in 2,3-DHBA that was significantly decreased by the AS cosmetic preparation. The EP extract did not show any effect on 2,3-DHBA production. It is concluded that the cosmetic preparation containing the AS extract is able to scavenge OH. production likely to be due to the presence of high concentrations of flavonoid aglycones such as quercetin, luteolin and 3-O-methylquercetin.

Oxidation of serum low-density lipoprotein (LDL) and antioxidant status in young and elderly humans

The incidence of atherosclerosis increases with age, as do various indices of free-radical mediated damage, e.g., lipid peroxidation. Because lipid peroxidation plays a prominent role in lipoprotein oxidation, likely a prelude to atherosclerosis, we compared the susceptibility of lipoproteins to oxidation in young (19-30 years) and elderly (59-86 years) groups. Although we found no significant differences in serum malondialdehyde (MDA) or oxidized LDL antibodies (OLAB) between young and elderly lipoproteins, MDA was directly related to OLAB regardless of age (r = 0.322, p = 0.005) and there was a trend for lower OLAB levels (30.5%, p = 0.079) in the elderly compared to the young population. Overall, serum antioxidant status was either similar or greater in the elderly group compared to the young group, likely reflecting antioxidant supplementation by the elderly group. OLAB was inversely related to Vitamin C (r = -0.310, p = 0.008) and Vitamin E intake (r = -0.277, p = 0.018) from foods and supplements. Serum levels of Vitamin C and Vitamin E were significantly higher (18.5%, p = 0.021 and 58.1 %, p < 0.001, respectively) in the elderly group compared to the young group and the ratio of Vitamin E to Vitamin C was significantly higher (30.4%, p = 0.042) in the serum of the elderly group. Oxidation of serum LDL and antioxidant status were not affected by age; however, the ratio of serum Vitamin E to Vitamin C was higher in the elderly group which may affect Vitamin E recycling.

Aging reduces responsiveness to BSO- and heat stress-induced perturbations of glutathione and antioxidant enzymes

Aging alters cellular responses to both heat and oxidative stress. Thiol-mediated metabolism of reactive oxygen species (ROS) is believed to be important in aging. To begin to determine the role of thiols in aging and heat stress, we depleted liver glutathione (GSH) by administering l-buthionine sulfoximine (BSO) in young (6 mo) and old (24 mo) Fisher 344 rats before heat stress. Animals were given BSO (4 mmol/kg ip) or saline (1 ml ip) 2 h before heat stress and subsequently heated to a core temperature of 41°C over a 90-min period. Liver tissue was collected before and 0, 30, and 60 min after heat stress. BSO inhibited glutamate cysteine ligase (GCL, the rate-limiting enzyme in GSH synthesis) catalytic activity and resulted in a decline in liver GSH and GSSG that was more pronounced in young compared with old animals. Catalase activity did not change between groups until 60 min after heat stress in young BSO-treated rats. Young animals experienced a substantial and persistent reduction in Cu,Zn-SOD activity with BSO treatment. Mn-SOD activity increased with BSO but declined after heat stress. The differences in thiol depletion observed between young and old animals with BSO treatment may be indicative of age-related differences in GSH compartmentalization that could have an impact on maintenance of redox homeostasis and antioxidant balance immediately after a physiologically relevant stress. The significant changes in antioxidant enzyme activity after GSH depletion suggest that thiol status can influence the regulation of other antioxidant enzymes.

Thiol supplementation in aged animals alters antioxidant enzyme activity after heat stress

Declines in oxidative and thermal stress tolerance are well documented in aging systems. It is thought that these alterations are due in part to reductions in antioxidant defenses. Although intracellular thiols are major redox buffers, their role in maintaining redox homeostasis is not completely understood, particularly during aging, where the reliance on antioxidant enzymes and proteins may be altered. To determine whether thiol supplementation improved the antioxidant enzyme profile of aged animals after heat stress, young and old Fischer 344 rats were treated with N-acetylcysteine (NAC; 4 mmol/kg ip) 2 h before heat stress. Liver tissue was collected before and 0, 30, and 60 min after heat stress. Aging was associated with a significant decline in tissue cysteine and glutathione (GSH) levels. There was also an age-related decrease in copper-zinc superoxide dismutase activity. Heat stress did not alter liver GSH, glutathione disulfide, or antioxidant enzyme activity. With NAC treatment, old animals took up more cysteine than young animals as reflected in an increase in liver GSH and a corresponding decrease in glutamate cysteine ligase activity. Catalase activity increased after NAC treatment in both age groups. Copper-zinc superoxide dismutase activity did not change with heat stress or drug treatment, whereas manganese superoxide dismutase activity was increased in old animals only. These data indicate that GSH synthesis is substrate limited in old animals. Furthermore, aged animals were characterized by large fluctuations in antioxidant enzyme balance after NAC treatment, suggesting a lack of fine control over these enzymes that may leave aged animals susceptible to subsequent stress.

Cytotoxic effect of formaldehyde with free radicals via increment of cellular reactive oxygen species

It is well known that formaldehyde (HCHO) and reactive oxygen species (ROS), such as free radicals, are cytotoxic as well as potentially carcinogenic. Although the individual effects of these reactants on cells have been investigated, the cytotoxicity exerted by the coexistence of HCHO and reactive radicals is poorly understood. The present study using Jurkat cells demonstrated that the coexistence of HCHO with water-soluble radical initiator, 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH) dramatically decreased cell viability, and that under such conditions scant cell death was observable induced by either of the reactants alone. Based on the results of phosphatidylserine exposure and caspase activation, this observed cell death, in fact, was apparently necrotic rather than apoptotic. To understand the mechanisms of the cell toxicity of HCHO and AIPH, we assessed two kinds of oxidative stress markers such as cellular glutathione (GSH) content and cellular ROS, and the DNA-protein cross-links, which formed as the result of HCHO treatment. A marked decrease in total cellular GSH was observed not only in the case of the coexistence conditions but also with AIPH alone. Dichlorodihydrofluorescein (DCF) assay revealed that cellular ROS were synergistically increased before cell death. The formation of DNA-protein cross-links was observed in the presence of HCHO and AIPH, and the extent was similar to HCHO alone. Co-incubation with semicarbazide, which inactivates HCHO, prevented this cell death induced by a combination of HCHO and AIPH. Semicarbazide also exhibited an inhibitory effect on the synergistic increment of cellular ROS and the formation of DNA-protein cross-links. These results suggest that the free radicals from AIPH induced GSH reduction, while HCHO resulted in the formation of DNA-protein cross-links, eventuating in a synergistic, incremental increase of cellular ROS and cell death brought about by this combination.

Soy isoflavone phyto-pharmaceuticals in interleukin-6 affections. Multi-purpose nutraceuticals at the crossroad of hormone replacement, anti-cancer and anti-inflammatory therapy

Interleukin-6 is a pleiotropic cytokine which plays a crucial role in immune physiology and is tightly controlled by hormonal feedback mechanisms. After menopause or andropause, loss of the normally inhibiting sex steroids (estrogen, testosterone) results in elevated IL6 levels that are further progressively increasing with age. Interestingly, excessive IL6 production promotes tumorigenesis (breast, prostate, lung, colon, ovarian), and accounts for several disease-associated pathologies and phenotypical changes of advanced age, such as osteoporosis, rheumatoid arthritis, multiple myeloma, neurodegenerative diseases and frailty. In this respect, pharmacological modulation of IL6 gene expression levels may have therapeutical benefit in preventing cancer progression, ageing discomforts and restoring immune homeostasis. Although "plant extracts" are used in folk medicine within living memory, it is only since the 20th century that numerous scientific investigations have been performed to discover potential health-protective food compounds or "nutraceuticals" which might prevent cancer and ageing diseases. About 2000 years ago, Hippocrates already highlighted "Let food be your medicine and medicine be your food". Various nutrients in the diet play a crucial role in maintaining an "optimal" immune response, such that deficient or excessive intakes can have negative consequences on the organism's immune status and susceptibility to a variety of pathologies. Over the last few decades, various immune-modulating nutrients have been identified, which interfere with IL6 gene expression. Currently, a broad range of phyto-pharmaceuticals with a claimed hormonal activity, called "phyto-estrogens", is recommended for prevention of various diseases related to a disturbed hormonal balance (i.e. menopausal ailments and/or prostate/breast cancer). In this respect, there is a renewed interest in soy isoflavones (genistein, daidzein, biochanin) as potential superior alternatives to the synthetic selective estrogen receptor modulators (SERMs), which are currently applied in hormone replacement therapy (HRT). As phyto-chemicals integrate hormonal ligand activities and interference with signaling cascades, therapeutic use may not be restricted to hormonal ailments only, but may have applications in cancer chemoprevention and/or NF-kappaB-related inflammatory disorders as well.

Free radical toxicity and antioxidants in Guillain–Barre syndrome, a preliminary study

BACKGROUND

The generation of reactive oxygen species (ROS) has been implicated in the pathogenesis of a vast array of disease processes including some neurological disorders.

METHOD

Ten patients with Guillain-Barre syndrome (GBS) and 10 age and sex-matched controls were included in this study. The erythrocyte glutathione (GSH), superoxide dismutase (SOD) and malondialdehyde (MDA) levels, as well as plasma antioxidant vitamins C and E and serum glutathione-S-transferase (GST) levels were estimated spectrophotometrically.

RESULTS

The plasma vitamin E and the serum total glutathione-S-transferase levels were markedly increased in both pre- and post-treated cases of GBS when compared to controls. The erythrocyte glutathione and malondialdehyde levels were significantly reduced in GBS cases when compared to normals. However, plasma vitamin C and erythrocyte superoxide dismutase were not altered when compared to controls.

CONCLUSION

Free radical toxicity may have an influence in patients suffering from GBS.

Age-related changes of serum lipoprotein oxidation in rats

Oxidation of low-density lipoprotein (LDL) may be a prelude to atherogenesis and directly age related. To assess whether there may be relationship between age and plasma lipoprotein (LP) oxidation, we studied copper-mediated LP oxidation isolated from the blood of 2 months, 7 months, and 15 months old rats. We determined whether the susceptibility of LP to oxidation might be related to vitamin C levels in serum, vitamin E levels in LP, or the total antioxidant capacity (TAC) of serum or LP. Serum vitamin C content was inversely related to age, malondialdehyde (MDA) propagation rate, and maximum change of MDA concentrations. However, there were no significant relationships between age and serum TAC, LP TAC, serum vitamin E, or the ratio of LP vitamin E to serum vitamin C content. The lag phase of MDA formation was significantly decreased with age and the ratio of LP vitamin E content to serum vitamin C content, increased with age. Maximum change of MDA concentration was positively correlated with the ratio of LP vitamin E contents to serum vitamin C concentration. Thus, as the rat ages, vitamin C status decreases with an increased LP susceptibility to oxidation. It is tempting to speculate that enhanced LP oxidation in older rats may reflect a reduced amount of recycling of LDL vitamin E by serum vitamin C.

Oxidation of protein in human low-density lipoprotein exposed to peroxyl radicals facilitates uptake by monocytes; protection by antioxidants in vitro

Generation of neoepitopes on apolipoprotein B within oxidised low-density lipoprotein (LDL) is important in the unregulated uptake of LDL by monocytic scavenger receptors (CD36, SR-AI, LOX-1). Freshly isolated LDL was oxidised by peroxyl radicals generated from the thermal decomposition of an aqueous azo-compound. We describe that formation of carbonyl groups on the protein component is early as protein oxidation was seen after 90min. This is associated with an increased propensity for LDL uptake by U937 monocytes. Three classes of antioxidants (quercetin, dehydroepiandrosterone (DHEA) and ascorbic acid) have been examined for their capacity to inhibit AAPH-induced protein oxidation, (protein carbonyls, Δ electrophoretic mobility and LDL uptake by U937 monocytes). CD36 expression was assessed by flow cytometry and was seen to be unaltered by oxidised LDL uptake. All three classes were effective antioxidants, quercetin (P<0.01), ascorbic acid (P<0.01), DHEA (P<0.05). As LDL protein is the control point for LDL metabolism, the degree of oxidation and protection by antioxidants is likely to be of great importance for (patho)-physiological uptake of LDL by monocytes.

The effects of endurance exercise and vitamin E on oxidative stress in the elderly

To examine the effects of exercise and vitamin E supplementation on oxidative stress in older adults, 59 participants, age 76.3 +/- 4.2 years, were randomly assigned to 1 of 4 groups: an exercise group taking placebos (EGP) or vitamin E (EGE) or a sedentary group taking placebos (SGP) or vitamin E (SGE). Measures included weight, VO2max, blood pressure (BP), and serum concentrations of vitamin E and lipid hydroperoxide (LOOH). At the end of the 16-week trial, the EGP and EGE had significant increases in VO2max and significant decreases in resting BP, weight, and LOOH concentrations (P < 0.05). The SGE had significant decreases in LOOH and BP (P < 0.05). There were no significant changes in the SGP (P > 0.05). The results suggest that endurance exercise in combination with vitamin E reduces oxidative stress, improves aerobic fitness, and reduces BP and weight in older adults. Even sedentary participants who take vitamin E may reduce oxidative stress and lower BP.

Protein kinase C modulates pulmonary endothelial permeability: a paradigm for acute lung injury

The intracellular serine/threonine kinase protein kinase C (PKC) has an important role in the genesis of pulmonary edema. This review discusses the PKC-mediated mechanisms that participate in the pulmonary endothelial response to agents involved in lung injury characteristic of the respiratory distress syndrome. Thus the paradigms of PKC-induced lung injury are discussed within the context of pulmonary transvascular fluid exchange. We focus on the signal transduction pathways that are modulated by PKC and their effect on lung endothelial permeability. Specifically, alpha-thrombin, tumor necrosis factor (TNF)-alpha, and reactive oxygen species are discussed because of their well-established roles in both human and experimental lung injury. We conclude that PKC, most likely PKC-alpha, is a primary supporter for lung endothelial injury in response to alpha-thrombin, TNF-alpha, and reactive oxygen species.

Endothelial cells maintain a reduced redox environment even as mitochondrial function declines

Human umbilical vein endothelial cells (HUVECs) are an endothelial model of replicative senescence. Oxidative stress, possibly due to dysfunctional mitochondria, is believed to play a key role in replicative senescence and atherosclerosis, an age-related vascular disease. In this study, we determined the effect of cell division on genomic instability, mitochondrial function, and redox status in HUVECs that were able to replicate for approximately 60 cumulative population doublings (CPD). After 20 CPD, the nuclear genome deteriorated and the protein content of the cell population increased. This indicated an increase in cell size, which was accompanied by an increase in oxygen consumption, ATP production, and mitochondrial genome copy number and approximately 10% increase in mitochondrial mass. The antioxidant capacity increased, as seen by an increase in reduced glutathione, glutathione peroxidase, GSSG reductase, and glucose-6-phosphate dehydrogenase. However, by CPD 52, the latter two enzymes decreased, as well as the ratio of mitochondrial-to-nuclear genome copies, the mitochondrial mass, and the oxygen consumption per milligram of protein. Our results signify that HUVECs maintain a highly reducing (GSH) environment as they replicate despite genomic instability and loss of mitochondrial function.

Superoxide dismutase, catalase and glutathione peroxidase activities in the liver of young and old mice: linear regression and correlation

Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GP) were determined in the liver of 15 young (3-5 months) and 15 old (23-26 months) female CBA mice. Although, the activities of all three enzymes decreased in aging, only the SOD decline was statistically significant (P<0.01). The pair wise correlation analysis exhibited an almost identical positive correlation between SOD and CAT in the liver of both young and old mice (r=0.57), whereas the correlative links between the enzymatic pairs of SOD-GP and CAT-GP were increased in aging. Close to zero in the young group (r=-0.08), the coefficient of correlation between SOD and GP became highly significant in the group of old mice (r=0.66; P<0.01). When the coefficients of pair wise and partial correlation were compared, practically no differences were found for the young mice, whereas all three partial coefficients were decreased in the group of old animals. Estimation of the linear regression between the enzymatic pairs revealed higher coefficients of regression and lower intercepts in the group of old mice. The results imply stronger correlative links between the antioxidant enzymes in the liver of old mice, compared with the same indices in the liver of young animals.

Expression of caveolin-1 induces premature cellular senescence in primary cultures of murine fibroblasts

Caveolae are vesicular invaginations of the plasma membrane. Caveolin-1 is the principal structural component of caveolae in vivo. Several lines of evidence are consistent with the idea that caveolin-1 functions as a "transformation suppressor" protein. In fact, caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). We have previously demonstrated that overexpression of caveolin-1 arrests mouse embryonic fibroblasts in the G(0)/G(1) phase of the cell cycle through activation of a p53/p21-dependent pathway, indicating a role of caveolin-1 in mediating growth arrest. However, it remains unknown whether overexpression of caveolin-1 promotes cellular senescence in vivo. Here, we demonstrate that mouse embryonic fibroblasts transgenically overexpressing caveolin-1 show: 1) a reduced proliferative lifespan; 2) senescence-like cell morphology; and 3) a senescence-associated increase in beta-galactosidase activity. These results indicate for the first time that the expression of caveolin-1 in vivo is sufficient to promote and maintain the senescent phenotype. Subcytotoxic oxidative stress is known to induce premature senescence in diploid fibroblasts. Interestingly, we show that subcytotoxic level of hydrogen peroxide induces premature senescence in NIH 3T3 cells and increases endogenous caveolin-1 expression. Importantly, quercetin and vitamin E, two antioxidant agents, successfully prevent the premature senescent phenotype and the up-regulation of caveolin-1 induced by hydrogen peroxide. Also, we demonstrate that hydrogen peroxide alone, but not in combination with quercetin, stimulates the caveolin-1 promoter activity. Interestingly, premature senescence induced by hydrogen peroxide is greatly reduced in NIH 3T3 cells harboring antisense caveolin-1. Importantly, induction of premature senescence is recovered when caveolin-1 levels are restored. Taken together, these results clearly indicate a central role for caveolin-1 in promoting cellular senescence and they suggest the hypothesis that premature senescence may represent a tumor suppressor function mediated by caveolin-1 in vivo.

Facilitated feeding in disabled elderly

Nutrition and health are major concerns to older individuals. Whereas illness associated with overnutrition has been well characterized, poor health associated with undernutrition has received less attention. Malnutrition continues to plague the elderly in developed and underdeveloped countries alike, and is becoming of more concern as global demographic changes predict increasing proportions of elderly in all societies. Nutrition influences many chronic disease processes affecting older individuals. In addition, changes in physiology, metabolism, and function accompanying aging result in altered nutritional requirements. The enhancement and maintenance of health and function are now more possible with the new knowledge of nutritional needs in old age. Designing nutritional therapy to treat malnutrition associated with illness in older patients requires an understanding of the aging processes, a careful setting of treatment goals, and multidisciplinary collaboration.