Skin atrophy in cytoplasmic SOD-deficient mice and its complete recovery using a vitamin C derivative

The Antioxidant PAPLAL Protects against Allergic Contact Dermatitis in Experimental Models

PAPLAL, a mixture of platinum (nPt) and palladium (nPd) nanoparticles, is widely used as a topical agent because of its strong antioxidant activity. Allergic contact dermatitis (ACD) is one of the most common occupational skin diseases worldwide. However, the role of oxidative stress in ACD remains unclear. In the present study, we investigated the protective effects of topical PAPLAL treatment on 2,4-dinitrofluorobenzene (DNFB)-induced ACD. DNFB treatment increased 8-isoprostane content; upregulated Xdh, Nox2, and Nox4, pro-oxidant genes; and downregulated Sod1, an antioxidant gene, indicating oxidative damage in the ear skin. PAPLAL therapy significantly reduced ear thickness associated with the downregulation of inflammatory cytokine-related genes. PAPLAL also significantly increased the expression of the stress-response-related genes Ahr and Nrf2, as well as their target genes, but failed to alter the expression of redox-related genes. Furthermore, Sod1 loss worsened ACD pathologies in the ear. These results strongly suggest that PAPLAL protects against ACD through its antioxidant activity and activation of the AHR and NRF2 axes. The antioxidant PAPLAL can be used as a novel topical therapy for ACD that targets oxidative stress.

Focus on the Contribution of Oxidative Stress in Skin Aging

Skin aging is one of the most evident signs of human aging. Modification of the skin during the life span is characterized by fine lines and wrinkling, loss of elasticity and volume, laxity, rough-textured appearance, and pallor. In contrast, photoaged skin is associated with uneven pigmentation (age spot) and is markedly wrinkled. At the cellular and molecular level, it consists of multiple interconnected processes based on biochemical reactions, genetic programs, and occurrence of external stimulation. The principal cellular perturbation in the skin driving senescence is the alteration of oxidative balance. In chronological aging, reactive oxygen species (ROS) are produced mainly through cellular oxidative metabolism during adenosine triphosphate (ATP) generation from glucose and mitochondrial dysfunction, whereas in extrinsic aging, loss of redox equilibrium is caused by environmental factors, such as ultraviolet radiation, pollution, cigarette smoking, and inadequate nutrition. During the aging process, oxidative stress is attributed to both augmented ROS production and reduced levels of enzymatic and non-enzymatic protectors. Apart from the evident appearance of structural change, throughout aging, the skin gradually loses its natural functional characteristics and regenerative potential. With aging, the skin immune system also undergoes functional senescence manifested as a reduced ability to counteract infections and augmented frequency of autoimmune and neoplastic diseases. This review proposes an update on the role of oxidative stress in the appearance of the clinical manifestation of skin aging, as well as of the molecular mechanisms that underline this natural phenomenon sometimes accelerated by external factors.

Tissue engineering strategies to bioengineer the ageing skin phenotype in vitro

Human skin ageing is a complex and heterogeneous process, which is influenced by genetically determined intrinsic factors and accelerated by cumulative exposure to extrinsic stressors. In the current world ageing demographic, there is a requirement for a bioengineered ageing skin model, to further the understanding of the intricate molecular mechanisms of skin ageing, and provide a distinct and biologically relevant platform for testing actives and formulations. There have been many recent advances in the development of skin models that recapitulate aspects of the ageing phenotype in vitro. This review encompasses the features of skin ageing, the molecular mechanisms that drive the ageing phenotype, and tissue engineering strategies that have been utilised to bioengineer ageing skin in vitro.

Xanthine Oxidoreductase-Mediated Superoxide Production Is Not Involved in the Age-Related Pathologies in Sod1-Deficient Mice

Reactive oxygen species (ROS) metabolism is regulated by the oxygen-mediated enzyme reaction and antioxidant mechanism within cells under physiological conditions. Xanthine oxidoreductase (XOR) exhibits two inter-convertible forms (xanthine oxidase (XO) and xanthine dehydrogenase (XDH)), depending on the substrates. XO uses oxygen as a substrate and generates superoxide (O2•-) in the catalytic pathway of hypoxanthine. We previously showed that superoxide dismutase 1 (SOD1) loss induced various aging-like pathologies via oxidative damage due to the accumulation of O2•- in mice. However, the pathological contribution of XO-derived O2•- production to aging-like tissue damage induced by SOD1 loss remains unclear. To investigate the pathological significance of O2•- derived from XOR in Sod1-/- mice, we generated Sod1-null and XO-type- or XDH-type-knock-in (KI) double-mutant mice. Neither XO-type- nor XDH-type KI mutants altered aging-like phenotypes, such as anemia, fatty liver, muscle atrophy, and bone loss, in Sod1-/- mice. Furthermore, allopurinol, an XO inhibitor, or apocynin, a nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor, failed to improve aging-like tissue degeneration and ROS accumulation in Sod1-/- mice. These results showed that XOR-mediated O2•- production is relatively uninvolved in the age-related pathologies in Sod1-/- mice.

Vitamin C-squalene bioconjugate promotes epidermal thickening and collagen production in human skin

Vitamin C (Vit C) benefits to human skin physiology notably by stimulating the biosynthesis of collagen. The main cutaneous collagens are types I and III, which are less synthesized with aging. Vit C is one of the main promotors of collagen formation but it poorly bypasses the epidermis stratum corneum barrier. To address this challenge, we developed a lipophilic version of Vit C for improving skin diffusion and delivery. Vit C was covalently conjugated to squalene (SQ), a natural lipid of the skin, forming a novel Vit C-SQ derivative suitable for cream formulation. Its biological activity was investigated on human whole skin explants in an ex vivo model, through histology and protein and gene expression analyses. Results were compared to Vit C coupled to the reference lipophilic compound palmitic acid, (Vit C-Palmitate). It was observed that Vit C-SQ significantly increased epidermal thickness and preferentially favored collagen III production in human skin after application for 10 days. It also promoted glycosaminoglycans production in a higher extent comparatively to Vit C-Palmitate and free Vit C. Microdissection of the explants to separate dermis and epidermis allowed to measure higher transcriptional effects either in epidermis or in dermis. Among the formulations studied, the strongest effects were observed with Vit C-SQ.

Copper/Zinc Superoxide Dismutase in Human Skin: Current Knowledge

Superoxide dismutase is widespread in the human body, including skin and its appendages. Here, we focus on human skin copper/zinc superoxide dismutase, the enzyme that protects skin and its appendages against reactive oxygen species. Human skin copper/zinc superoxide dismutase resides in the cytoplasm of keratinocytes, where up to 90% of cellular reactive oxygen species is produced. Factors other than cell type, such as gender, age and diseased state influence its location in skin tissues. We review current knowledge of skin copper/zinc superoxide dismutase including recent studies in an attempt to contribute to solving the question of its remaining unexplained functions. The research described here may be applicable to pathologies associated with oxidative stress. However, recent studies on copper/zinc superoxide dismutase in yeast reveal that its predominant function may be in signaling pathways rather than in scavenging superoxide ions. If confirmed in the skin, novel approaches might be developed to unravel the enzyme's remaining mysteries.

Skin Health from the Inside Out

The skin is the main interface between the body and the environment, providing a biological barrier against an array of chemical and physical pollutants (e.g., ultraviolet light, ozone, etc.). Exposure of the skin to these outdoor stressors generates reactive oxygen species (ROS), which can overwhelm the skin's endogenous defense systems (e.g., catalase, vitamins C and E, etc.), resulting in premature skin aging due to the induction of DNA damage, mitochondrial damage, lipid peroxidation, activation of inflammatory signaling pathways, and formation of protein adducts. In this review, we discuss how topical application of antioxidants, including vitamins C and E, carotenoids, resveratrol, and pycnogenol, can be combined with dietary supplementation of these antioxidant compounds in addition to probiotics and essential minerals to protect against outdoor stressor-induced skin damage, including the damage associated with aging.

SOD1 deficiency alters gastrointestinal microbiota and metabolites in mice

Redox imbalance induces oxidative damage and causes age-related pathologies. Mice lacking the antioxidant enzyme SOD1 (Sod1^-/-) exhibit various aging-like phenotypes throughout the body and are used as aging model mice. Recent reports suggested that age-related changes in the intestinal environment are involved in various diseases. We investigated cecal microbiota profiles and gastrointestinal metabolites in wild-type (Sod1^+/+) and Sod1^-/- mice. Firmicutes and Bacteroidetes were dominant in Sod1^+/+ mice, and most of the detected bacterial species belong to these two phyla. Meanwhile, the Sod1^-/- mice had an altered Firmicutes and Bacteroidetes ratio compared to Sod1^+/+ mice. Among the identified genera, Paraprevotella, Prevotella, Ruminococcus, and Bacteroides were significantly increased, but Lactobacillus was significantly decreased in Sod1^-/- mice compared to Sod1^+/+ mice. The correlation analyses between cecal microbiota and liver metabolites showed that Bacteroides and Prevotella spp. were grouped into the same cluster, and Paraprevotella and Ruminococcus spp. were also grouped as another cluster. These four genera showed a positive and a negative correlation with increased and decreased liver metabolites in Sod1^-/- mice, respectively. In contrast, Lactobacillus spp. showed a negative correlation with increased liver metabolites and a positive correlation with decreased liver metabolites in Sod1^-/- mice. These results suggest that the redox imbalance induced by Sod1 loss alters gastrointestinal microflora and metabolites.

DNA damage in human skin and the capacities of natural compounds to modulate the bystander signalling

Human skin is a stratified organ frequently exposed to sun-generated ultraviolet radiation (UVR), which is considered one of the major factors responsible for DNA damage. Such damage can be direct, through interactions of DNA with UV photons, or indirect, mainly through enhanced production of reactive oxygen species that introduce oxidative changes to the DNA. Oxidative stress and DNA damage also associate with profound changes at the cellular and molecular level involving several cell cycle and signal transduction factors responsible for DNA repair or irreversible changes linked to ageing. Crucially, some of these factors constitute part of the signalling known for the induction of biological changes in non-irradiated, neighbouring cells and defined as the bystander effect. Network interactions with a number of natural compounds, based on their known activity towards these biomarkers in the skin, reveal the capacity to inhibit both the bystander signalling and cell cycle/DNA damage molecules while increasing expression of the anti-oxidant enzymes. Based on this information, we discuss the likely polypharmacology applications of the natural compounds and next-generation screening technologies in improving the anti-oxidant and DNA repair capacities of the skin.

Klotho Protein Protects Human Keratinocytes from UVB-Induced Damage Possibly by Reducing Expression and Nuclear Translocation of NF-κB

Background

UV-related skin disease such as actinic keratosis is a major concern in public health. In view of the cell injury induced by UVB, Klotho protein it is an ideal therapy to eliminate UVB-induced cell damages and the associated signaling pathways.

Material/Methods

To gain insights into the potential role of Klotho and the underlying molecular mechanism, we constructed a Klotho-overexpress HaCaT cell line and assessed the protection against UVB insults. The effects of exposure to UVB radiation on the human keratinocyte HaCaT cells, including cell growth, apoptosis, and changes of selected biomarkers, were measured by CCK-8, flow cytometry, Quantitative real-time PCR, and Western blot analysis.

Results

We found that enhanced NF-κB activity was accompanied by decreased expression of the anti-aging protein Klotho upon UVB stimulation, which was further confirmed with in vivo experiments. Overexpression of Klotho was able to considerably alleviate the UVB-induced damages to cells and reversed the UVB-caused biomarker changes to a great extent, which was comparable to the effects of administration of NF-κB inhibitor PDTC, suggesting the inhibition of nuclear translocation and DNA-binding activity of NF-κB. Furthermore, Klotho overexpression was proved to decrease the nuclear expression of NF-κB as much as the treatment with PDTC, which provides support for the direct regulation of NF-κB by Klotho.

Conclusions

Collectively, our work provides new insight into the potential role of Klotho in the context of UVB-induced injuries in human keratinocytes, as well as providing the basis for future study of new therapies against UV-related skin disease.

Potential protective effects of rhEGF against ultraviolet A irradiation-induced damages on human fibroblasts

Background

Ultraviolet A (UVA) rays reach the dermal skin layer and generate oxidative stress, DNA damage, and cell inflammation, which in turn lead to photo-aging and photo-carcinogenesis. While there have been many studies about the beneficial effects of topical epidermal growth factor (EGF) treatment in the healing of wounds, the effect of EGF on UVA-induced skin irritation remains unknown. To clarify the effects of EGF on UVA-induced skin damage, it was investigated whether EGF signaling can affect intracellular reactive oxygen species (ROS) and DNA damages in UVA-irradiated human dermal fibroblasts.

Materials and methods

Fibroblasts cultured with or without rhEGF were UVA-irradiated at 40 mJ/cm² twice per day for 5 days. After the irradiation, the intracellular ROS levels and expression of catalase and superoxide dismutase-1 (SOD-1) in the fibroblasts were ascertained. Further investigation to determine the effects of EGF on UVA-induced DNA damage, including a single cell gel electrophoresis assay and an enzyme-linked immunosorbent assay (ELISA), was carried out. Moreover, the NF-κB activity was ascertained in order to investigate the effects of EGF on UVA-irradiated fibroblasts.

Results

As a result, it was revealed that recombinant human EGF (rhEGF) inhibited UVA- increased intracellular ROS in the fibroblasts and increased the expression of catalase and SOD-1. Moreover, in UVA-irradiated fibroblasts, the longest DNA-damaged tails were observed, but this phenomenon was not detected in cells cotreated with both UVA and rhEGF. Also, it was observed that DNA damage induction, including that of cyclobutene pyrimidine dimers, pyrimidine (6-4) pyrimidone photoproducts, and 8-hydroxy-2-deoxyguanosine, was caused by UVA irradiation. Similar to previous results, it was downregulated by rhEGF. Furthermore, rhEGF also inhibited NF-κB gene expression and the NF-κB p65 protein level in the nucleus induced by UVA irradiation.

Conclusion

These results suggest that EGF might be a useful material for preventing or improving photo-aging.

Syringaresinol Reverses Age-Related Skin Atrophy by Suppressing FoxO3a-Mediated Matrix Metalloproteinase-2 Activation in Copper/Zinc Superoxide Dismutase-Deficient Mice

Aging is characterized by accumulation of chronic and irreversible oxidative damage, chronic inflammation, and organ dysfunction. Superoxide dismutase (SOD) serves as a major enzyme for cellular superoxide radical metabolism and physiologically regulates cellular redox balance throughout the body. Copper/zinc superoxide dismutase-deficient (SOD1^-/-) mice showed diverse phenotypes associated with enhanced oxidative damage in whole organs. Here, we found that oral treatment with syringaresinol (also known as lirioresinol B), which is the active component in the berries of Korean ginseng (Panax ginseng C.A. Meyer), attenuated the age-related changes in Sod1^-/- skin. Interestingly, syringaresinol morphologically normalized skin atrophy in Sod1^-/- mice and promoted fibroblast outgrowth from Sod1^-/- skin in vitro. These protective effects were mediated by the suppression of matrix metalloproteinase-2 overproduction in Sod1^-/- skin, but not by increased collagen expression. Syringaresinol also decreased the oxidative damage and the phosphorylation of FoxO3a protein, which was a transcriptional factor of matrix metalloproteinase-2, in Sod1^-/- skin. These results strongly suggest that syringaresinol regulates the FoxO3-matrix metalloproteinase-2 axis in oxidative damaged skin and exhibits beneficial effects on age-related skin involution in Sod1^-/- mice.

Antioxidant treatment with vitamin C attenuated rotator cuff degeneration caused by oxidative stress in Sod1-deficient mice

Background

Rotator cuff degeneration is 1 of several factors that lead to rotator cuff tears; however, the mechanism of this degeneration remains unclear. We previously reported that deficiency of an antioxidant enzyme, superoxide dismutase 1 (Sod1), in mice induced degeneration in supraspinatus tendon entheses, a model that replicates human rotator cuff degeneration. In this study, we analyzed possible effects of vitamin C (VC), a major antioxidant, on the degenerative changes of supraspinatus entheses in Sod1^−/− mice.

Methods

We administered VC or vehicle, distilled water, for 8 weeks to Sod1^−/− and wild-type male mice beginning at 12 weeks of age (n = 5-8 per group). When mice were 20 weeks of age, we sectioned rotator cuff tissue samples and performed hematoxylin-eosin and toluidine blue staining for quantitative histologic evaluation.

Results

VC administration, compared with vehicle administration, attenuated the histologic changes, including a misaligned 4-layered structure, fragmented tidemark, and toluidine blue staining, in the supraspinatus entheses of Sod1^−/− mice. In the quantitative histologic evaluation, all parameters were significantly decreased in Sod1^−/− mice compared with wild-type mice, except for the number of nonchondrocytes.

Conclusion

We demonstrated that an antioxidant treatment, VC administration, attenuated the rotator cuff degeneration, similar to that observed in humans, that is caused by oxidative stress in Sod1^−/− mice. VC effects included improvements in quantitative histologic parameters and other histologic changes. These results suggest that VC treatment can prevent oxidative stress–induced degeneration of the rotator cuff.

Standardized Kaempferia parviflora Extract Inhibits Intrinsic Aging Process in Human Dermal Fibroblasts and Hairless Mice by Inhibiting Cellular Senescence and Mitochondrial Dysfunction

Intrinsic skin aging is a complex biological phenomenon mainly caused by cellular senescence and mitochondrial dysfunction. This study evaluated the inhibitory effect of Kaempferia parviflora Wall ex. Baker ethanol extract (KPE) on H₂O₂-stimulated cellular senescence and mitochondrial dysfunction both in vitro and in vivo. KPE significantly increased cell growth and suppressed senescence-associated β-galactosidase activation. KPE inhibited the expression of cell-cycle inhibitors (p53, p21, p16, and pRb) and stimulated the expression of cell-cycle activators (E2F1 and E2F2). H₂O₂-induced hyperactivation of the phosphatidylinositol 3-kinase/protein kinase B (AKT) signaling pathway was suppressed by KPE through regulated expression of forkhead box O3a (FoxO3a) and mammalian target of rapamycin (mTOR). KPE attenuated inflammatory mediators (interleukin-6 (IL-6), IL-8, nuclear factor kappa B (NF-κB), and cyclooxygenase-2 (COX-2)) and increased the mRNA expression of PGC-1α, ERRα, NRF1, and Tfam, which modulate mitochondrial biogenesis and function. Consequently, reduced ATP levels and increased ROS level were also reversed by KPE treatment. In hairless mice, KPE inhibited wrinkle formation, skin atrophy, and loss of elasticity by increasing the collagen and elastic fibers. The results indicate that KPE prevents intrinsic aging process in hairless mice by inhibiting cellular senescence and mitochondrial dysfunction, suggesting its potential as a natural antiaging agent.

Topical Application of Trisodium Ascorbyl 6-Palmitate 2-Phosphate Actively Supplies Ascorbate to Skin Cells in an Ascorbate Transporter-Independent Manner

Ascorbic acid (AA) possesses multiple beneficial functions, such as regulating collagen biosynthesis and redox balance in the skin. AA derivatives have been developed to overcome this compound’s high fragility and to assist with AA supplementation to the skin. However, how AA derivatives are transferred into cells and converted to AA in the skin remains unclear. In the present study, we showed that AA treatment failed to increase the cellular AA level in the presence of AA transporter inhibitors, indicating an AA transporter-dependent action. In contrast, torisodium ascorbyl 6-palmitate 2-phosphate (APPS) treatment significantly enhanced the cellular AA level in skin cells despite the presence of inhibitors. In ex vivo experiments, APPS treatment also increased the AA content in a human epidermis model. Interestingly, APPS was readily metabolized and converted to AA in keratinocyte lysates via an intrinsic mechanism. Furthermore, APPS markedly repressed the intracellular superoxide generation and promoted viability associated with an enhanced AA level in Sod1-deficient skin cells. These findings indicate that APPS effectively restores the AA level and normalizes the redox balance in skin cells in an AA transporter-independent manner. Topical treatment of APPS is a beneficial strategy for supplying AA and improving the physiology of damaged skin.

Mechanism of ROS scavenging and antioxidant signalling by redox metallic and fullerene nanomaterials: Potential implications in ROS associated degenerative disorders

BACKGROUND

The balance between oxidation and anti-oxidation is believed to be critical in maintaining healthy biological systems. However, our endogenous antioxidant defense systems are incomplete without exogenous antioxidants and, therefore, there is a continuous demand for exogenous antioxidants to prevent stress and ageing associated disorders. Nanotechnology has yielded enormous variety of nanomaterials (NMs) of which metallic and carbonic (mainly fullerenes) NMs, with redox property, have been found to be strong scavengers of ROS and antioxidants in preclinical in vitro and in vivo models.

SCOPE OF REVIEW

Redox activity of metal based NMs and membrane translocation time of fullerene NMs seem to be the major determinants in ROS scavenging potential exhibited by these NMs. A comprehensive knowledge about the effects of ROS scavenging NMs in cellular antioxidant signalling is largely lacking. This review compiles the mechanisms of ROS scavenging as well as antioxidant signalling of the aforementioned metallic and fullerene NMs.

MAJOR CONCLUSIONS

Direct interaction between NMs and proteins does greatly affect the corona/adsorption formation dynamics but such interaction does not provide the explanation behind diverse biological outcomes induced by NMs. Indirect interaction, however, that could occur via NMs uptake and dissolution, NMs ROS induction and ROS scavenging property, and NMs membrane translocation time seem to work as a central mode of interaction.

GENERAL SIGNIFICANCE

The usage of potential antioxidant NMs in biological systems would greatly impact the field of nanomedicine. ROS scavenging NMs hold great promise in the future treatment of ROS related degenerative disorders.

Involvement of senescence marker protein-30 in glucose metabolism disorder and non-alcoholic fatty liver disease

Senescence marker protein-30 (SMP30) was found to decrease in the liver, kidneys and lungs of mice during aging. SMP30 is a pleiotropic protein that acts to protect cells from apoptosis by enhancing plasma membrane Ca(2+) -pump activity and is bona fide gluconolactonase (EC 3.1.1.17) that participates in the penultimate step of the vitamin C biosynthetic pathway. For the past several years, we have obtained strong evidence showing the close relationship between SMP30, glucose metabolism disorder and non-alchoholic fatty liver disease in experiments with SMP30 knockout mice. Emerging proof links the following abnormalities: (i) the reduction of SMP30 by aging and/or excessive dietary fat or genetic deficiency causes a loss of Ca(2+) pumping activity, which impairs acute insulin release in pancreatic β-cells, initiates inflammatory responses with oxidative stress and endoplasmic reticulum stress in non-alchoholic steatohepatitis, exacerbates renal tubule damage, and introduces tubulointerstitial inflammation and fibrosis in diabetic nephropathy; (ii) vitamin C insufficiency also impairs acute insulin secretion in pancreatic β-cells by a mechanism distinct from that of the SMP30 deficiency; and (iii) the increased oxidative stress by concomitant deficiencies of SMP30, superoxide dismutase 1 and vitamin C similarly causes hepatic steatosis. Here, we review recent advances in our understanding of SMP30 in glucose metabolism disorder and non-alchoholic fatty liver disease.

Topical application of superoxide dismutase mediated by HIV-TAT peptide attenuates UVB-induced damages in human skin

The purpose of this study was to evaluate whether topical application of superoxide dismutase with cell penetrating peptide (HIV-TAT) could protect against skin damage induced by UVB irradiation in humans. The permeability through stratum corneum of large proteins linked to TAT peptide was firstly confirmed by confocal microscopy and tape stripping. Ten healthy volunteers with either Fitzpatrick skin type II or III were recruited in this clinical study. TAT-SOD (300units/cm(2)) and vehicle cream were applied on two symmetric areas of both inner upper arms 1h prior to UVB irradiation. After one hour of pretreatment, subjects received 10 incremental doses of UVB on pretreated areas. 24h later, erythema, blood flow and apoptotic cells were measured. Pretreatment with TAT-SOD 1h prior to UVB radiation promoted a mean minimal erythema dose (MED) increase of 36.6±18.4% (p=0.013<0.05. n=10) compared to vehicle control. The median blood flow values of all subjects following 2 and 3-MED of UVB were 107.8±51.0units and 239.5±88.0units respectively, which account for 26% and 25% decrease with respect to vehicle groups. These data suggest that TAT-SOD significantly suppresses UVB induced erythema formation and blood flow rise. Furthermore, pretreatment with TAT-SOD 1h prior to 2-MED of UVB irradiation reduced the apoptotic sunburn cell formation by 47.6±8.6% (p<0.0001) in all subjects. Evaluating results generated from all measurements, we conclude that topical application of TAT-SOD significantly attenuates UVB-induced skin damage in man. These biological effects of TAT-SOD are probably mediated via its free radical scavenging properties, clearly differentiating it from other physical sunscreen agents.

Mechanical overloading causes mitochondrial superoxide and SOD2 imbalance in chondrocytes resulting in cartilage degeneration

Mechanical stress and aging are major risk factors of cartilage degeneration. Human studies have previously reported that oxidative damage increased, while SOD2 protein was reciprocally downregulated in osteoarthritic degenerated cartilage. However, it remains unclear whether mitochondrial superoxide imbalance in chondrocytes causes cartilage degeneration. We herein demonstrate that mechanical loading promoted mitochondrial superoxide generation and selective Sod2 downregulation in chondrocytes in vivo and that mitochondrial superoxide inducer also downregulated Sod2 expression in chondrocytes in vitro. A genetically manipulated model revealed that Sod2 deficiency in chondrocytes also resulted in mitochondrial superoxide overproduction and dysfunction, thus leading to cartilage degeneration. Intra-articular injection of a permeable antioxidant effectively suppressed the mechanical loading-induced mitochondrial superoxide generation and cartilage degeneration in mice. Our findings demonstrate that mitochondrial superoxide plays a pivotal role in the development and progression of osteoarthritis, and the mitochondrial superoxide balance may therefore be a promising target for the treatment of cartilage degeneration.

Resveratrol Derivative-Rich Melinjo Seed Extract Attenuates Skin Atrophy in Sod1-Deficient Mice

The oxidative damages induced by a redox imbalance cause age-related changes in cells and tissues. Superoxide dismutase (SOD) enzymes play a pivotal role in the antioxidant system and they also catalyze superoxide radicals. Since the loss of cytoplasmic SOD (SOD1) resulted in aging-like phenotypes in several types of murine tissue, SOD1 is essential for the maintenance of tissue homeostasis. Melinjo (Gnetum gnemon Linn) seed extract (MSE) contains trans-resveratrol (RSV) and resveratrol derivatives, including gnetin C, gnemonoside A, and gnemonoside D. MSE intake also exerts no adverse events in human study. In the present studies, we investigated protective effects of MSE on age-related skin pathologies in mice. Orally MSE and RSV treatment reversed the skin thinning associated with increased oxidative damage in the Sod1^−/− mice. Furthermore, MSE and RSV normalized gene expression of Col1a1 and p53 and upregulated gene expression of Sirt1 in skin tissues. In vitro experiments revealed that RSV significantly promoted the viability of Sod1^−/− fibroblasts. These finding demonstrated that RSV in MSE stably suppressed an intrinsic superoxide generation in vivo and in vitro leading to protecting skin damages. RSV derivative-rich MSE may be a powerful food of treatment for age-related skin diseases caused by oxidative damages.

Oxidative stress in aging human skin

Oxidative stress in skin plays a major role in the aging process. This is true for intrinsic aging and even more for extrinsic aging. Although the results are quite different in dermis and epidermis, extrinsic aging is driven to a large extent by oxidative stress caused by UV irradiation. In this review the overall effects of oxidative stress are discussed as well as the sources of ROS including the mitochondrial ETC, peroxisomal and ER localized proteins, the Fenton reaction, and such enzymes as cyclooxygenases, lipoxygenases, xanthine oxidases, and NADPH oxidases. Furthermore, the defense mechanisms against oxidative stress ranging from enzymes like superoxide dismutases, catalases, peroxiredoxins, and GSH peroxidases to organic compounds such as L-ascorbate, α-tocopherol, beta-carotene, uric acid, CoQ10, and glutathione are described in more detail. In addition the oxidative stress induced modifications caused to proteins, lipids and DNA are discussed. Finally age-related changes of the skin are also a topic of this review. They include a disruption of the epidermal calcium gradient in old skin with an accompanying change in the composition of the cornified envelope. This modified cornified envelope also leads to an altered anti-oxidative capacity and a reduced barrier function of the epidermis.

Conformation-specific antibodies to target amyloid β oligomers and their application to immunotherapy for Alzheimer's disease

Amyloid β-protein (Aβ) oligomers, intermediates of Aβ aggregation, cause cognitive impairment and synaptotoxicity in the pathogenesis of Alzheimer's disease (AD). Immunotherapy using anti-Aβ antibody is one of the most promising approaches for AD treatment. However, most clinical trials using conventional sequence-specific antibodies have proceeded with difficulty. This is probably due to the unintended removal of the non-pathological monomer and fibrils of Aβ as well as the pathological oligomers by these antibodies that recognize Aβ sequence, which is not involved in synaptotoxicity. Several efforts have been made recently to develop conformation-specific antibodies that target the tertiary structure of Aβ oligomers. Here, we review the recent findings of Aβ oligomers and anti-Aβ antibodies including our own, and discuss their potential as therapeutic and diagnostic tools.

Palladium and platinum nanoparticles attenuate aging-like skin atrophy via antioxidant activity in mice

Cu-Zn superoxide dismutase (Sod1) loss causes a redox imbalance as it leads to excess superoxide generation, which results in the appearance of various aging-related phenotypes, including skin atrophy. Noble metal nanoparticles, such as palladium (Pd) and platinum (Pt) nanoparticles, are considered to function as antioxidants due to their strong catalytic activity. In Japan, a mixture of Pd and Pt nanoparticles called PAPLAL has been used to treat chronic diseases over the past 60 years. In the present study, we investigated the protective effects of PAPLAL against aging-related skin pathologies in mice. Transdermal PAPLAL treatment reversed skin thinning associated with increased lipid peroxidation in Sod1^−/− mice. Furthermore, PAPLAL normalized the gene expression levels of Col1a1, Mmp2, Has2, Tnf-α, Il-6, and p53 in the skin of the Sod1^−/− mice. Pt nanoparticles exhibited marked SOD and catalase activity, while Pd nanoparticles only displayed weak SOD and catalase activity in vitro. Although the SOD and catalase activity of the Pt nanoparticles significantly declined after they had been oxidized in air, a mixture of Pd and Pt nanoparticles continued to exhibit SOD and catalase activity after oxidation. Importantly, a mixture of Pd and Pt nanoparticles with a molar ratio of 3 or 4 to 1 continued to exhibit SOD and catalase activity after oxidation, indicating that Pd nanoparticles prevent the oxidative deterioration of Pt nanoparticles. These findings indicate that PAPLAL stably suppresses intrinsic superoxide generation both in vivo and in vitro via SOD and catalase activity. PAPLAL is a potentially powerful tool for the treatment of aging-related skin diseases caused by oxidative damage.

Superoxide dismutase 1 loss disturbs intracellular redox signaling, resulting in global age-related pathological changes

Aging is characterized by increased oxidative stress, chronic inflammation, and organ dysfunction, which occur in a progressive and irreversible manner. Superoxide dismutase (SOD) serves as a major antioxidant and neutralizes superoxide radicals throughout the body. In vivo studies have demonstrated that copper/zinc superoxide dismutase-deficient (Sod1(-/-)) mice show various aging-like pathologies, accompanied by augmentation of oxidative damage in organs. We found that antioxidant treatment significantly attenuated the age-related tissue changes and oxidative damage-associated p53 upregulation in Sod1(-/-) mice. This review will focus on various age-related pathologies caused by the loss of Sod1 and will discuss the molecular mechanisms underlying the pathogenesis in Sod1(-/-) mice.

Oxidative stress induced age dependent meibomian gland dysfunction in Cu, Zn-superoxide dismutase-1 (Sod1) knockout mice

Purpose

The purpose of our study was to investigate alterations in the meibomian gland (MG) in Cu, Zn-Superoxide Dismutase-1 knockout (Sod1^−/−) mouse.

Methods

Tear function tests [Break up time (BUT) and cotton thread] and ocular vital staining test were performed on Sod1^−/− male mice (n = 24) aged 10 and 50 weeks, and age and sex matched wild–type (+/+) mice (n = 25). Tear and serum samples were collected at sacrifice for inflammatory cytokine assays. MG specimens underwent Hematoxylin and Eosin staining, Mallory staining for fibrosis, Oil Red O lipid staining, TUNEL staining, immunohistochemistry stainings for 4HNE, 8-OHdG and CD45. Transmission electron microscopic examination (TEM) was also performed.

Results

Corneal vital staining scores in the Sod1^−/− mice were significantly higher compared with the wild type mice throughout the follow-up. Tear and serum IL-6 and TNF-α levels also showed significant elevations in the 10 to 50 week Sod1^−/− mice. Oil Red O staining showed an accumulation of large lipid droplets in the Sod1^−/− mice at 50 weeks. Immunohistochemistry revealed both increased TUNEL and oxidative stress marker stainings of the MG acinar epithelium in the Sod1^−/− mice compared to the wild type mice. Immunohistochemistry staining for CD45 showed increasing inflammatory cell infiltrates from 10 to 50 weeks in the Sod1^−/− mice compared to the wild type mice. TEM revealed prominent mitochondrial changes in 50 week Sod1^−/− mice.

Conclusions

Our results suggest that reactive oxygen species might play a vital role in the pathogensis of meibomian gland dysfunction. The Sod1^−/− mouse appears to be a promising model for the study of reactive oxygen species associated MG alterations.

Collagen peptide and vitamin C additively attenuate age-related skin atrophy in Sod1-deficient mice

Age-related skin thinning is correlated with a decrease in the content of collagen in the skin. Accumulating evidence suggests that collagen peptide (CP) and vitamin C (VC) transcriptionally upregulate type I collagen in vivo. However, the additive effects of CP and VC on age-related skin changes remain unclear. We herein demonstrate that CP and a VC derivative additively corrected age-related skin thinning via reduced oxidative damage in superoxide dismutase 1 (Sod1)-deficient mice. Co-treatment with these compounds significantly normalized the altered gene expression of Col1a1, Has2, and Ci1, a proton-coupled oligopeptide transporter, in Sod1(-/-) skin. The in vitro analyses further revealed that collagen oligopeptide, a digestive product of ingested CP, significantly promoted the bioactivity of the VC derivative with respect to the migration and proliferation of Sod1(-/-) fibroblasts. These findings suggest that combined treatment with CP and VC is effective in cases of age-related skin pathology.

Senescence marker protein-30/superoxide dismutase 1 double knockout mice exhibit increased oxidative stress and hepatic steatosis

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We generated SMP30/SOD1-double knockout (DKO) mice for oxidative stress research.

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SMP30/SOD1-DKO mice showed low levels of ascorbic acid and premature death.

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SMP30/SOD1-DKO mice exhibited high levels of oxidative stress and liver injury.

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SMP30/SOD1-DKO mice manifest hepatic steatosis due to decreased levels of Apolipoprotein B.

Superoxide dismutase 1 (SOD1) is an antioxidant enzyme that converts superoxide anion radicals into hydrogen peroxide and molecular oxygen. The senescence marker protein-30 (SMP30) is a gluconolactonase that functions as an antioxidant protein in mammals due to its involvement in ascorbic acid (AA) biosynthesis. SMP30 also participates in Ca²⁺ efflux by activating the calmodulin-dependent Ca²⁺-pump. To reveal the role of oxidative stress in lipid metabolism defects occurring in non-alcoholic fatty liver disease pathogenesis, we generated SMP30/SOD1-double knockout (SMP30/SOD1-DKO) mice and investigated their survival curves, plasma and hepatic lipid profiles, amounts of hepatic oxidative stress, and hepatic protein levels expressed by genes related to lipid metabolism. While SMP30/SOD1-DKO pups had no growth retardation by 14 days of age, they did have low plasma and hepatic AA levels. Thereafter, 39% and 53% of male and female pups died by 15–24 and 89 days of age, respectively. Compared to wild type, SMP30-KO and SOD1-KO mice, by 14 days SMP30/SOD1-DKO mice exhibited: (1) higher plasma levels of triglyceride and aspartate aminotransferase; (2) severe accumulation of hepatic triglyceride and total cholesterol; (3) higher levels of superoxide anion radicals and thiobarbituric acid reactive substances in livers; and (4) decreased mRNA and protein levels of Apolipoprotein B (ApoB) in livers – ApoB is an essential component of VLDL secretion. These results suggest that high levels of oxidative stress due to concomitant deficiency of SMP30 and/or AA, and SOD1 cause abnormal plasma lipid metabolism, hepatic lipid accumulation and premature death resulting from impaired VLDL secretion.

Contribution of oxidative stress to the degeneration of rotator cuff entheses

BACKGROUND

Rotator cuff degeneration is one of the multiple factors that lead to rotator cuff tears; however, the precise mechanism of such degeneration still remains unclear. In this study, we investigated the supraspinatus tendon enthesis to clarify the link between rotator cuff degeneration and oxidative stress in antioxidant enzyme superoxide dismutase 1 (Sod1)-deficient mice (Sod1(-/-)).

METHODS

The supraspinatus tendon and humeral head were isolated and fixed to prepare histologic sections from wild-type and Sod1(-/-) male mice at 20 weeks of age. Hematoxylin-eosin staining was performed to assess the histomorphologic structure. To investigate the collagen fibers, we examined spatially aligned collagen fibers using a polarizing microscope and assessed the amount of collagen using immunohistochemical staining. To analyze the tissue elasticity, we measured the tissue acoustic properties using scanning acoustic microscopy.

RESULTS

The Sod1(-/-) mice showed histologic changes, such as a misaligned 4-layered structure and fragmented tidemark, in the enthesis. Sod1 loss also decreased the amount of brightly diffracted light and type I collagen, indicating collagen downregulation. The scanning acoustic microscopy analysis showed that the speed and attenuation of sound were increased in the nonmineralized fibrocartilage of the Sod1(-/-) mice, suggesting decreased mechanical properties in the supraspinatus enthesis.

CONCLUSION

Sod1 deficiency-induced degeneration is associated with impaired elasticity in the supraspinatus tendon enthesis, recapitulating human rotator cuff degeneration. These results suggest that intracellular oxidative stress contributes to the degeneration of rotator cuff entheses.

Cytoplasmic reactive oxygen species and SOD1 regulate bone mass during mechanical unloading

Oxidative stress contributes to the pathogenesis of age-related diseases as well as bone fragility. Our previous study demonstrated that copper/zinc superoxide dismutase (Sod1)-deficient mice exhibit the induction of intracellular reactive oxygen species (ROS) and bone fragility resulting from low-turnover bone loss and impaired collagen cross-linking (Nojiri et al. J Bone Miner Res. 2011;26:2682-94). Mechanical stress also plays an important role in the maintenance of homeostasis in bone tissue. However, the molecular links between oxidative and mechanical stresses in bone tissue have not been fully elucidated. We herein report that mechanical unloading significantly increased intracellular ROS production and the specific upregulation of Sod1 in bone tissue in a tail-suspension experiment. We also reveal that Sod1 loss exacerbated bone loss via reduced osteoblastic abilities during mechanical unloading. Interestingly, we found that the administration of an antioxidant, vitamin C, significantly attenuated bone loss during unloading. These results indicate that mechanical unloading, in part, regulates bone mass via intracellular ROS generation and the Sod1 expression, suggesting that activating Sod1 may be a preventive strategy for ameliorating mechanical unloading-induced bone loss.

Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives

Topically applied antioxidants exert their benefits by offering protection from damaging free radicals and over-the-counter cosmeceuticals incorporating antioxidants are among the most popular anti-aging products available. One potent antioxidant of particular note, vitamin C, has been extensively utilized because it possesses a variety of other cutaneous benefits including photoprotection from UV A & B, neocollagenesis, inhibition of melanogenesis and improvement of a variety of inflammatory skin disorders. However, the instability of this water-soluble vitamin, together with difficulties associated with its topical delivery, has presented issues for the formulation chemist. This article reviews the scientific data and clinical studies that underpin the stability, percutaneous absorption, and cutaneous effects of vitamin C together with its commonly utilized, commercially available derivatives.

Sod1 loss induces intrinsic superoxide accumulation leading to p53-mediated growth arrest and apoptosis

Oxidative damages induced by a redox imbalance cause age-related changes in cells and tissues. Superoxide dismutase (SOD) enzymes play a major role in the antioxidant system and they also catalyze superoxide radicals (O2·-). Since the loss of cytoplasmic SOD (SOD1) resulted in aging-like phenotypes in several types of mouse tissue, SOD1 is essential for the maintenance of tissue homeostasis. To clarify the cellular function of SOD1, we investigated the cellular phenotypes of Sod1-deficient fibroblasts. We demonstrated that Sod1 deficiency impaired proliferation and induced apoptosis associated with O2·- accumulation in the cytoplasm and mitochondria in fibroblasts. Sod1 loss also decreased the mitochondrial membrane potential and led to DNA damage-mediated p53 activation. Antioxidant treatments effectively improved the cellular phenotypes through suppression of both intracellular O2·- accumulation and p53 activation in Sod1-deficient fibroblasts. In vivo experiments revealed that transdermal treatment with a vitamin C derivative significantly reversed the skin thinning commonly associated with the upregulated p53 action in the skin. Our findings revealed that intrinsic O2·- accumulation promoted p53-mediated growth arrest and apoptosis as well as mitochondrial disfunction in the fibroblasts.

Cytoplasmic superoxide radical: a possible contributing factor to intracellular Aβ oligomerization in Alzheimer disease

Soluble amyloid β (Aβ) oligomers cause memory loss and synaptic dysfunction in Alzheimer disease (AD). Despite intensive studies on Aβ assembly in vitro and in vivo, the localization and cellular mechanism of Aβ oligomerization are not fully understood. Previously, we demonstrated that cytoplasmic superoxide radicals contribute to drusen deposition, a hallmark of age-related macular degeneration as well as other geriatric diseases (fatty liver, skin thinning, and osteoporosis). Using a transgenic mouse model of AD, we recently clarified the role of cytoplasmic oxidative stress in cognitive impairment and oligomer formation. Moreover, we also found that these phenomena were associated with neuroinflammation, tau phosphorylation, and synaptic loss. Notably, studies using human brains support the involvement of cytoplasmic superoxide radicals in AD pathology. In this addendum to Murakami et al. (JBC 2011), we discuss and comment on intracellular Aβ oligomer formation and the possible therapeutic effects of intracellular redox state modulators.

Stimulation of the amyloidogenic pathway by cytoplasmic superoxide radicals in an Alzheimer's disease mouse model

Oxidative stress is involved in the pathogenesis of neurodegeneration. Amyloid β (Aβ) oligomer as an intermediate of aggregates causes memory loss in Alzheimer's disease (AD). We have suggested that oxidative stress plays an important role in Aβ oligomerization and cognitive impairment using a human amyloid precursor protein (hAPP) transgenic AD mice lacking cytoplasmic superoxide dismutase (hAPP/Sod1-/-). Recently, clinical trials revealed inhibitors of Aβ production from hAPP as promising therapeutics, but the relationship between oxidative stress and Aβ metabolism remains unclear. Here we found that Sod1 deficiency enhanced β-cleavage of hAPP, suggesting that it increased Aβ production in hAPP/Sod1-/- mice. In contrast, Aβ degradation did not decrease in hAPP/Sod1-/- as compared with hAPP/Sod1+/+ mice. Furthermore, we successfully detected in situ superoxide radicals associated with increased protein carbonylation in hAPP/Sod1-/-. These results suggest that cytoplasmic oxidative stress is involved in Aβ production as well as aggregation during AD progression.

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.

Molecular cloning, characterization and predicted structure of a putative copper-zinc SOD from the camel, Camelus dromedarius

Superoxide dismutase (SOD) is the first line of defense against oxidative stress induced by endogenous and/or exogenous factors and thus helps in maintaining the cellular integrity. Its activity is related to many diseases; so, it is of importance to study the structure and expression of SOD gene in an animal naturally exposed most of its life to the direct sunlight as a cause of oxidative stress. Arabian camel (one humped camel, Camelus dromedarius) is adapted to the widely varying desert climatic conditions that extremely changes during daily life in the Arabian Gulf. Studying the cSOD1 in C. dromedarius could help understand the impact of exposure to direct sunlight and desert life on the health status of such mammal. The full coding region of a putative CuZnSOD gene of C. dromedarius (cSOD1) was amplified by reverse transcription PCR and cloned for the first time (gene bank accession number for nucleotides and amino acids are JF758876 and AEF32527, respectively). The cDNA sequencing revealed an open reading frame of 459 nucleotides encoding a protein of 153 amino acids which is equal to the coding region of SOD1 gene and protein from many organisms. The calculated molecular weight and isoelectric point of cSOD1 was 15.7 kDa and 6.2, respectively. The level of expression of cSOD1 in different camel tissues (liver, kidney, spleen, lung and testis) was examined using Real Time-PCR. The highest level of cSOD1 transcript was found in the camel liver (represented as 100%) followed by testis (45%), kidney (13%), lung (11%) and spleen (10%), using 18S ribosomal subunit as endogenous control. The deduced amino acid sequence exhibited high similarity with Cebus apella (90%), Sus scrofa (88%), Cavia porcellus (88%), Mus musculus (88%), Macaca mulatta (87%), Pan troglodytes (87%), Homo sapiens (87%), Canis familiaris (86%), Bos taurus (86%), Pongo abelii (85%) and Equus caballus (82%). Phylogenetic analysis revealed that cSOD1 is grouped together with S. scrofa. The predicted 3D structure of cSOD1 showed high similarity with the human and bovine CuZnSOD homologues. The Root-mean-square deviation (rmsd) between cSOD1/hSOD1 and cSOD1/bSOD1 superimposed structure pairs were 0.557 and 0.425 A. The Q-score of cSOD1-hSOD1 and cSOD1-bSOD1 were 0.948 and 0.961, respectively.

SOD1 (copper/zinc superoxide dismutase) deficiency drives amyloid β protein oligomerization and memory loss in mouse model of Alzheimer disease

Oxidative stress is closely linked to the pathogenesis of neurodegeneration. Soluble amyloid β (Aβ) oligomers cause cognitive impairment and synaptic dysfunction in Alzheimer disease (AD). However, the relationship between oligomers, oxidative stress, and their localization during disease progression is uncertain. Our previous study demonstrated that mice deficient in cytoplasmic copper/zinc superoxide dismutase (CuZn-SOD, SOD1) have features of drusen formation, a hallmark of age-related macular degeneration (Imamura, Y., Noda, S., Hashizume, K., Shinoda, K., Yamaguchi, M., Uchiyama, S., Shimizu, T., Mizushima, Y., Shirasawa, T., and Tsubota, K. (2006) Proc. Natl. Acad. Sci. U.S.A. 103, 11282-11287). Amyloid assembly has been implicated as a common mechanism of plaque and drusen formation. Here, we show that Sod1 deficiency in an amyloid precursor protein-overexpressing mouse model (AD mouse, Tg2576) accelerated Aβ oligomerization and memory impairment as compared with control AD mouse and that these phenomena were basically mediated by oxidative damage. The increased plaque and neuronal inflammation were accompanied by the generation of N(ε)-carboxymethyl lysine in advanced glycation end products, a rapid marker of oxidative damage, induced by Sod1 gene-dependent reduction. The Sod1 deletion also caused Tau phosphorylation and the lower levels of synaptophysin. Furthermore, the levels of SOD1 were significantly decreased in human AD patients rather than non-AD age-matched individuals, but mitochondrial SOD (Mn-SOD, SOD2) and extracellular SOD (CuZn-SOD, SOD3) were not. These findings suggest that cytoplasmic superoxide radical plays a critical role in the pathogenesis of AD. Activation of Sod1 may be a therapeutic strategy for the inhibition of AD progression.

Cytoplasmic superoxide causes bone fragility owing to low-turnover osteoporosis and impaired collagen cross-linking

The aging process correlates with the accumulation of cellular and tissue damage caused by oxidative stress. Although previous studies have suggested that oxidative stress plays a pathologic role in the development of bone fragility, little direct evidence has been found. In order to investigate the pathologic significance of oxidative stress in bones, we analyzed the bone tissue of mice deficient in cytoplasmic copper/zinc superoxide dismutase (CuZn-SOD, encoded by the Sod1 gene; Sod1(-/-)). In this study, we showed for the first time that in vivo cytoplasmic superoxide caused a distinct weakness in bone stiffness and decreased BMD, aging-like changes in collagen cross-linking, and transcriptional alterations in the genes associated with osteogenesis. We also showed that the surface areas of osteoblasts and osteoclasts were decreased significantly in the lumbar vertebrae of Sod1(-/-) mice, indicating the occurrence of low-turnover osteopenia. In vitro experiments demonstrated that intracellular oxidative stress induced cell death and reduced the proliferation in primary osteoblasts but not in osteoclasts, indicating that impaired osteoblast viability caused the decrease in osteoblast number and suppressed RANKL/M-CSF osteoclastogenic signaling in bone. Furthermore, treatment with an antioxidant, vitamin C, effectively improved bone fragility and osteoblastic survival. These results imply that intracellular redox imbalance caused by SOD1 deficiency plays a pivotal role in the development and progression of bone fragility both in vivo and in vitro. We herein present a valuable model for investigating the effects of oxidative stress on bone fragility in order to develop suitable therapeutic interventions.

Formation of the 42-mer Amyloid β Radical and the Therapeutic Role of Superoxide Dismutase in Alzheimer's Disease

Oxidative stress is closely involved in age-related diseases and ageing itself. There is evidence of the leading contribution of oxidative damage to neurodegenerative disease, in contrast to other diseases where oxidative stress plays a secondary role. The 42-mer amyloid β (Aβ42) peptide is thought to be a culprit in the pathogenesis of Alzheimer's disease (AD). Aβ42 aggregates form the oligomeric assembly and show neurotoxicity, causing synaptic dysfunction. Aβ42 also induces tissue oxidation (DNA/RNA, proteins, and lipids) through trace metals (Cu, Zn, and Fe), which can be protected by antioxidant enzymes, vitamin C, and vitamin E. Superoxide dismutase catalyzes the conversion of toxic superoxide radical to less reactive hydrogen peroxide, contributing to protection from AD. Here we review the involvement of oxidative stress in AD progression induced from an imbalance between the radical formation of Aβ42 itself together with unique turn structure at positions Glu22 and Asp23 and several defense systems.

The protective effects of long-term oral administration of marine collagen hydrolysate from chum salmon on collagen matrix homeostasis in the chronological aged skin of Sprague-Dawley male rats

To investigate the long-term effects of marine collagen hydrolysate (MCH) from Chum Salmon skin on the aberrant collagen matrix homeostasis in chronological aged skin, Sprague-Dawley male rats of 4-wk-old were orally administrated with MCH at the diet concentrations of 2.25% and 4.5% for 24 mo. Histological and biochemical analysis revealed that MCH had the potential to inhibit the collagen loss and collagen fragmentation in chronological aged skin. Based on immunohistochemistry and western blot analysis, collagen type I and III protein expression levels in MCH-treated groups significantly increased as compared with the aged control group. Furthermore, quantitative real-time polymerase chain reaction and western blot analysis showed MCH was able to increase the expressions of procollagen type I and III mRNA (COL1A2 and COL3A1) through activating Smad signaling pathway with up-regulated TGF-βRII (TβRII) expression level. Meanwhile, MCH was shown to inhibit the age-related increased collagen degradation through attenuating MMP-1 expression and increasing tissue inhibitor of metalloproteinases-1 expression in a dose-dependent manner. Moreover, MCH could alleviate the oxidative stress in chronological aged skin, which was revealed from the data of superoxide dismutase activity and the thiobarbituric acid reactive substances level in skin homogenates. Therefore, MCH was demonstrated to have the protective effects on chronological skin aging due to the influence on collagen matrix homeostasis. And the antioxidative property of MCH might play an important role in the process.