• Gaspar J, Mathieu J, Alvarez PJJ. A Rapid Platform to Generate Lipofuscin and Screen Therapeutic Drugs for Efficacy in Lipofuscin Removal. Materials, Methods & Technologies, Volume 10, 2016. Read on external site. Categories: LysoSENS

    A Rapid Platform to Generate Lipofuscin and Screen Therapeutic Drugs for Efficacy in Lipofuscin Removal.

    Materials, Methods & Technologies, Volume 10, 2016.

    A Rapid Platform to Generate Lipofuscin and Screen Therapeutic Drugs for Efficacy in Lipofuscin Removal.

    Gaspar J, Mathieu J, Alvarez PJJ.

    Abstract

    Abstract:

    Lipofuscin is a brown-yellow, autofluorescent polymeric material that accumulates in a ceroid manner within postmitotic cells during aging. Lipofuscin accumulation impairs proteosome and lysosome pathways critical to cell health and homeostasis. Therefore, the ability to quickly generate lipofuscin in vitro, and identify drugs that mitigate the accumulation or clear lipofuscin would be of great benefit to aging research. Here, we present a platform to quickly create lipofuscin-loaded (but otherwise healthy) cells and screen drugs for efficacy in lipofuscin removal. The combination of leupeptin, iron (III) chloride and hydrogen peroxide generates significant amounts of lipofuscin within cells while eliminating the need for a 40% hyperoxic chamber. Alternative methods which load fibroblasts with "artificial" lipofuscin obtained via UV-peroxidation of mitochondrial fragments are much more labor-intensive. This method is faster (≤10 days) than most protocols to generate lipofuscin and assess its removal, which typically require 2 to 4 weeks or longer to complete.

  • Mathieu JM, Wang F, Segatori L, Alvarez PJ. Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase. Biotechnol Bioeng. 2012 Sep;109(9):2409-15. doi: 10.1002/bit.24506. PubMed: 22447444. Categories: LysoSENS

    Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase.

    Biotechnol Bioeng. 2012 Sep;109(9):2409-15. doi: 10.1002/bit.24506.

    Increased resistance to oxysterol cytotoxicity in fibroblasts transfected with a lysosomally targeted Chromobacterium oxidase.

    Mathieu JM, Wang F, Segatori L, Alvarez PJ.

    Abstract

    Abstract:

    7-Ketocholesterol (7KC) is a cytotoxic oxysterol that plays a role in many age-related degenerative diseases. 7KC formation and accumulation often occurs in the lysosome, which hinders enzymatic transformations that reduce its toxicity and increase the sensitivity to lysosomal membrane permeabilization. We assayed the potential to mitigate 7KC cytotoxicity and enhance cell viability by overexpressing 7KC-active enzymes in human fibroblasts. One of the enzymes tested, a cholesterol oxidase engineered for lysosomal targeting, significantly increased cell viability in the short term upon treatment with up to 50 µM 7KC relative to controls. These results suggest targeting the lysosome for optimal treatment of oxysterol-mediated cytotoxicity, and support the use of introducing novel catalytic function into the lysosome for therapeutic and research applications.

  • Wu Y, Zhou J, Fishkin N, Rittmann BE, Sparrow JR. Enzymatic degradation of A2E, a retinal pigment epithelial lipofuscin bisretinoid. J Am Chem Soc. 2011 Feb 2;133(4):849-57. doi: 10.1021/ja107195u. PubMed: 21166406. Categories: LysoSENS

    Enzymatic degradation of A2E, a retinal pigment epithelial lipofuscin bisretinoid.

    J Am Chem Soc. 2011 Feb 2;133(4):849-57. doi: 10.1021/ja107195u.

    Enzymatic degradation of A2E, a retinal pigment epithelial lipofuscin bisretinoid.

    Wu Y, Zhou J, Fishkin N, Rittmann BE, Sparrow JR.

    Abstract

    Abstract:

    Some forms of blinding macular disease are associated with excessive accumulation of bisretinoid lipofuscin in retinal pigment epithelial (RPE) cells of the eye. This material is refractory to lysosomal enzyme degradation. In addition to gene and drug-based therapies, treatments that reverse the accumulation of bisretinoid would be beneficial. Thus, we have examined the feasibility of degrading the bisretinoids by delivery of exogenous enzyme. As proof of principle we report that horseradish peroxidase (HRP) can cleave the RPE bisretinoid A2E. In both cell-free and cell-based assays, A2E levels were decreased in the presence of HRP. HRP-associated cleavage products were detected by ultraperformance liquid chromatography (UPLC) coupled to electrospray ionization mass spectrometry, and the structures of the aldehyde-bearing cleavage products were elucidated by 18O-labeling and 1H NMR spectroscopy and by recording UV−vis absorbance spectra. These findings indicate that RPE bisretinoids such as A2E can be degraded by appropriate enzyme activities.

  • Peto MV. Aluminium and iron in humans: bioaccumulation, pathology, and removal. Rejuvenation Res 2010 Oct;13(5):589-98. PubMed: 21142669. Categories: AmyloSENS, LysoSENS, OncoSENS

    Aluminium and iron in humans: bioaccumulation, pathology, and removal.

    Rejuvenation Res 2010 Oct;13(5):589-98.

    Aluminium and iron in humans: bioaccumulation, pathology, and removal.

    Peto MV.

    Abstract

    Abstract:

    It is well known that exposure to various elements has a noticeable effect on human health. The effect of an element is determined by several characteristics, including its similarity to elements of biological necessity, metabolism, and degree of interaction with physiological processes. This review investigates the scientific literature of iron and aluminium to evaluate the extent to which these elements accumulate and cause pathology in humans. Iron was chosen for review because it is necessary for human life while seemingly having relationships with numerous pathological states such as heart disease, cancer, and impaired insulin sensitivity. Aluminium is reviewed because of its prevalence in daily life, observed interference with several biological processes, controversial relationship with Alzheimer disease, and lack of physiological role. Furthermore, because each of these metals has long been investigated for a possible relationship with various pathological states, a substantial volume of research is available regarding the effects of iron and aluminium in biological systems. For both aluminium and iron, this review focuses on: (1) Evaluating the evidence of toxicity, (2) considering the possibility of bioaccumulation, and (3) exploring methods of managing their accumulation.

  • Mathieu JM, Mohn WW, Eltis LD, LeBlanc JC, Stewart GR, Dresen C, Okamoto K, Alvarez PJ. 7-ketocholesterol catabolism by Rhodococcus jostii RHA1. Appl Environ Microbiol. 2010 Jan;76(1):352-5. doi: 10.1128/AEM.02538-09. PubMed: 19880645. Categories: LysoSENS

    7-ketocholesterol catabolism by Rhodococcus jostii RHA1.

    Appl Environ Microbiol. 2010 Jan;76(1):352-5. doi: 10.1128/AEM.02538-09.

    7-ketocholesterol catabolism by Rhodococcus jostii RHA1.

    Mathieu JM, Mohn WW, Eltis LD, LeBlanc JC, Stewart GR, Dresen C, Okamoto K, Alvarez PJ.

    Abstract

    Abstract:

    Oxysterols from steroid autooxidation have numerous harmful effects, but their biodegradation is poorly understood. Microarrays were used to study mineralization of the most common oxysterol, 7-ketocholesterol (7KC), by Rhodococcus jostii RHA1. Growth on 7KC versus growth on cholesterol resulted in 363 differentially expressed genes, including upregulation of two large gene clusters putatively encoding steroid catabolism. Despite this difference, 7KC degradation required key genes involved in cholesterol degradation, indicating a common catabolic route.

  • Schloendorn J, Webb T, Kemmish K, Hamalainen M, Jackemeyer D, Jiang L, Mathieu J, Rebo J, Sankman J, Sherman L, Tontson L, Qureshi A, Alvarez P, Rittmann B. Medical bioremediation: a concept moving toward reality. Rejuvenation Res. 2009 Dec;12(6):411-9. doi: 10.1089/rej.2009.0917. PubMed: 20041735. Categories: LysoSENS

    Medical bioremediation: a concept moving toward reality.

    Rejuvenation Res. 2009 Dec;12(6):411-9. doi: 10.1089/rej.2009.0917.

    Medical bioremediation: a concept moving toward reality.

    Schloendorn J, Webb T, Kemmish K, Hamalainen M, Jackemeyer D, Jiang L, Mathieu J, Rebo J, Sankman J, Sherman L, Tontson L, Qureshi A, Alvarez P, Rittmann B.

    Abstract

    Abstract:

    A major driver of aging is catabolic insufficiency, the inability of our bodies to break down certain substances that accumulate slowly throughout the life span. Even though substance buildup is harmless while we are young, by old age the accumulations can reach a toxic threshold and cause disease. This includes some of the most prevalent diseases in old age-atherosclerosis and macular degeneration. Atherosclerosis is associated with the buildup of cholesterol and its oxidized derivatives (particularly 7-ketocholesterol) in the artery wall. Age-related macular degeneration is associated with carotenoid lipofuscin, primarily the pyridinium bisretinoid A2E. Medical bioremediation is the concept of reversing the substance accumulations by using enzymes from foreign species to break down the substances into forms that relieve the disease-related effect. We report on an enzyme discovery project to survey the availability of microorganisms and enzymes with these abilities. We found that such microorganisms and enzymes exist. We identified numerous bacteria having the ability to transform cholesterol and 7-ketocholesterol. Most of these species initiate the breakdown by same reaction mechanism as cholesterol oxidase, and we have used this enzyme directly to reduce the toxicity of 7-ketocholesterol, the major toxic oxysterol, to cultured human cells. We also discovered that soil fungi, plants, and some bacteria possess peroxidase and carotenoid cleavage oxygenase enzymes that effectively destroy with varied degrees of efficiency and selectivity the carotenoid lipofuscin found in macular degeneration.

  • Mathieu JM, Schloendorn J, Rittmann BE, Alvarez PJ. Medical bioremediation of age-related diseases. Microb Cell Fact. 2009 Apr 9;8:21. doi: 10.1186/1475-2859-8-21. PubMed: 19358742. Categories: LysoSENS

    Medical bioremediation of age-related diseases.

    Microb Cell Fact. 2009 Apr 9;8:21. doi: 10.1186/1475-2859-8-21.

    Medical bioremediation of age-related diseases.

    Mathieu JM, Schloendorn J, Rittmann BE, Alvarez PJ.

    Abstract

    Abstract:

    Catabolic insufficiency in humans leads to the gradual accumulation of a number of pathogenic compounds associated with age-related diseases, including atherosclerosis, Alzheimer's disease, and macular degeneration. Removal of these compounds is a widely researched therapeutic option, but the use of antibodies and endogenous human enzymes has failed to produce effective treatments, and may pose risks to cellular homeostasis. Another alternative is "medical bioremediation," the use of microbial enzymes to augment missing catabolic functions. The microbial genetic diversity in most natural environments provides a resource that can be mined for enzymes capable of degrading just about any energy-rich organic compound. This review discusses targets for biodegradation, the identification of candidate microbial enzymes, and enzyme-delivery methods.

  • Mathieu J, Schloendorn J, Rittmann BE, Alvarez PJ. Microbial degradation of 7-ketocholesterol. Biodegradation. 2008;19(6):807-13. PubMed: 18344006. Categories: LysoSENS

    Microbial degradation of 7-ketocholesterol.

    Biodegradation. 2008;19(6):807-13.

    Microbial degradation of 7-ketocholesterol.

    Mathieu J, Schloendorn J, Rittmann BE, Alvarez PJ.

    Abstract

    Abstract:

    7-Ketocholesterol (7KC) is an oxidized derivative of cholesterol suspected to be involved in the pathogenesis of atherosclerosis and possibly Alzheimer's disease. While some oxysterols are important biological mediators, 7KC is generally cytotoxic and interferes with cellular homeostasis. Despite recent interest in preventing the accumulation of 7KC in a variety of matrices to avoid adverse biological effects, its microbial degradation has not been previously addressed in the peer-reviewed literature. Thus, the rate and extent of biodegradation of this oxysterol was investigated to bridge this gap. A wide variety of bacteria isolated from soil or activated sludge, including Proteobacterium Y-134, Sphingomonas sp. JEM-1, Nocardia nova, Rhodococcus sp. RHA1, and Pseduomonas aeruginosa, utilized 7KC as a sole carbon and energy source, resulting in its mineralization. Nocardia nova, which is known to produce biosurfactants, was the fastest degrader. This study supports the notion that microbial catabolic enzymes could be exploited to control 7KC levels in potential biotechnological applications for agricultural, environmental, or medical use.

  • de Grey ADNJ. Alzheimer's, atherosclerosis, and aggregates: a role for bacterial degradation. Nutr Rev. 2007 Dec;65(12 Pt 2):S221-7. PubMed: 18240553. Categories: LysoSENS

    Alzheimer's, atherosclerosis, and aggregates: a role for bacterial degradation.

    Nutr Rev. 2007 Dec;65(12 Pt 2):S221-7.

    Alzheimer's, atherosclerosis, and aggregates: a role for bacterial degradation.

    de Grey ADNJ.

    Abstract

    Abstract:

    Several of the most prevalent and severe age-related diseases, notably Alzheimer's disease and atherosclerosis, feature the accumulation of non-degradable aggregates within the lysosomes of disease-affected cells. At an early point in disease progression, the breakdown of lysosomal contents by the resident catabolic enzymes stops working properly. A return of lysosomal enzymatic activity to pre-disease levels may restore aggregate elimination. In this review, a method of bioremediation-derived lysosomal enzyme enhancement is proposed, featuring the cellular introduction of microbial-isolated enzymes, or xenoenzymes. The benefits and challenges of using xenoenzymes to break down aggregates are discussed. As the size of our elderly population grows, the incidence of age-related diseases will increase, necessitating the exploration of radical, but potentially powerful, therapeutic strategies.

  • Rittmann BE, Schloendorn J. Engineering away lysosomal junk: medical bioremediation. Rejuvenation Res 2007;10(3):359-365. PubMed: 17708688. Categories: LysoSENS

    Engineering away lysosomal junk: medical bioremediation.

    Rejuvenation Res 2007;10(3):359-365.

    Engineering away lysosomal junk: medical bioremediation.

    Rittmann BE, Schloendorn J.

    Abstract

    Abstract:

    Atherosclerosis, macular degeneration, and neurodegenerative diseases such as Alzheimer's disease, are associated with the intracellular accumulation of substances that impair cellular function and viability. Reversing this accumulation may be a valuable therapy, but the accumulating substances resist normal cellular catabolism. On the other hand, these substances are naturally degraded in the soil and water by microorganisms. Thus, we propose the concept of "medical bioremediation," which derives from the successful field of in situ environmental bioremediation of petroleum hydrocarbons. In environmental bioremediation, communities of microorganisms mineralize hydrophobic organics using a series of enzymes. In medical bioremediation, we hope to utilize one or several microbial enzymes to degrade the intracellular accumulators enough that they can be cleared from the affected cells. Here, we present preliminary, but promising results for the bacterial biodegradation of 7-ketocholesterol, the main accumulator of foam cells associated with atherosclerosis. In particular, we report on the isolation of several Nocardia strains able to biodegrade 7-ketocholesterol and as an ester of 7-ketocholoesterol. We also outline key intermediates in the biodegradation pathway, a key step towards identifying the key enzymes that may lead to a therapy.

  • de Grey ADNJ. Rejuvenating neurons and glia with microbial enzymes. In: Interaction Between Neurons and Glia in Aging and Disease (J.O. Malva et al., eds.), Springer, 2007, pp. 503-510. Categories: LysoSENS

    Rejuvenating neurons and glia with microbial enzymes.

    In: Interaction Between Neurons and Glia in Aging and Disease (J.O. Malva et al., eds.), Springer, 2007, pp. 503-510.

    Rejuvenating neurons and glia with microbial enzymes.

    de Grey ADNJ.

    Abstract

    Abstract:

    All the major neurodegenerative diseases are characterised by the accumulation of proteinaceous aggregates within neurons. The commonest such condition, Alzheimer’s disease, also features extracellular proteinaceous aggregates (amyloid). The role of these aggregates in the etiology and progression of cognitive impairment is still unclear, but their absence in young adults suggests that their removal would at any rate not be harmful. However, no method for removing the intracellular aggregates in question has yet been developed. Moreover, the engulfment of amyloid by microglia as a result of immunisation may result in loss of microglial function if the amyloid then resists lysosomal digestion. A novel approach to eliminating intracellular aggregates in the brain (and elsewhere) was proposed by the present author in 2002 and has recently attracted enthusiastic support from all relevant specialities, which are unusually disparate. This approach is to isolate bacterial or fungal strains with the capacity to metabolise the recalcitrant aggregates, following which the genes encoding the enzymes responsible would be identified and modified for expression in mammalian cells and targeting to the appropriate subcellular compartment. Delivery could be either of the genes themselves, using somatic gene therapy, or of the enzymes they encode, which would be injected either directly into the brain or into the circulation in conjunction with agents to deliver them across the blood-brain barrier. Ambitious though this approach undoubtedly is, its potential for both the prevention and the treatment of the entire range of neurodegenerative diseases so far exceeds any alternative presently being explored that the case for pursuing it is strong.

  • de Grey ADNJ. Appropriating microbial catabolism: a proposal to treat and prevent neurodegeneration. Neurobiol Aging 2006;27(4):589-595. PubMed: 16207503. Categories: LysoSENS

    Appropriating microbial catabolism: a proposal to treat and prevent neurodegeneration.

    Neurobiol Aging 2006;27(4):589-595.

    Appropriating microbial catabolism: a proposal to treat and prevent neurodegeneration.

    de Grey ADNJ.

    Abstract

    Abstract:

    Intraneuronal, largely proteinaceous aggregates accumulate in all major neurodegenerative disorders. Lysosomal degradation of proteinaceous and other material declines early in such diseases. This suggests that intraneuronal aggregates consist of material which is normally broken down in the lysosome and thus accumulates when lysosomal degradation fails. This is plausible even though those aggregates are generally non-lysosomal, because lysosomal uptake may be affected. Thus, restoring lysosomal function might eliminate them--and without increasing the concentration of the soluble monomers or oligomers of which they are formed. This approach is therefore unlikely to be harmful and may well be beneficial. How might lysosomes be rejuvenated? Since lysosomal dysfunction is likely to be caused by intralysosomal material that is resistant to lysosomal degradation, normal function might be recovered by augmenting that function to cause the toxin to be degraded. Here, I describe how such augmentation might be achieved with microbial enzymes. Soil microbes display astonishing catabolic diversity, something exploited for decades in the bioremediation industry. Environments enriched in human remains impose selective pressure on the microbial population to evolve the ability to degrade any recalcitrant, energy-rich human material. Thus, microbes may exist that can degrade these lysosomal toxins. If so, it should be possible to isolate the genes responsible and modify them for therapeutic activity in the mammalian lysosome.

  • de Grey ADNJ, Alvarez PJJ, Brady RO, Cuervo AM, Jerome WG, McCarty PL, Nixon RA, Rittmann BE, Sparrow JR. Medical bioremediation: prospects for the application of microbial catabolic diversity to aging and several major age-related diseases. Ageing Res Rev. 2005 Aug;4(3):315-38. PubMed: 16040282. Categories: LysoSENS

    Medical bioremediation: prospects for the application of microbial catabolic diversity to aging and several major age-related diseases.

    Ageing Res Rev. 2005 Aug;4(3):315-38.

    Medical bioremediation: prospects for the application of microbial catabolic diversity to aging and several major age-related diseases.

    de Grey ADNJ, Alvarez PJJ, Brady RO, Cuervo AM, Jerome WG, McCarty PL, Nixon RA, Rittmann BE, Sparrow JR.

    Abstract

    Abstract:

    Several major diseases of old age, including atherosclerosis, macular degeneration and neurodegenerative diseases are associated with the intracellular accumulation of substances that impair cellular function and viability. Moreover, the accumulation of lipofuscin, a substance that may have similarly deleterious effects, is one of the most universal markers of aging in postmitotic cells. Reversing this accumulation may thus be valuable, but has proven challenging, doubtless because substances resistant to cellular catabolism are inherently hard to degrade. We suggest a radically new approach: augmenting humans' natural catabolic machinery with microbial enzymes. Many recalcitrant organic molecules are naturally degraded in the soil. Since the soil in certain environments - graveyards, for example - is enriched in human remains but does not accumulate these substances, it presumably harbours microbes that degrade them. The enzymes responsible could be identified and engineered to metabolise these substances in vivo. Here, we survey a range of such substances, their putative roles in age-related diseases and the possible benefits of their removal. We discuss how microbes capable of degrading them can be isolated, characterised and their relevant enzymes engineered for this purpose and ways to avoid potential side-effects.

  • de Grey ADNJ. Lysosomal enhancement with microbial hydrolases: a novel strategy for removing protein aggregates. In: New Trends in Alzheimer and Parkinson Disorders: ADPD 2005 (A. Fisher et al., eds.), Medimond, 2005, pp. 51-54. Categories: LysoSENS

    Lysosomal enhancement with microbial hydrolases: a novel strategy for removing protein aggregates.

    In: New Trends in Alzheimer and Parkinson Disorders: ADPD 2005 (A. Fisher et al., eds.), Medimond, 2005, pp. 51-54.

    Lysosomal enhancement with microbial hydrolases: a novel strategy for removing protein aggregates.

    de Grey ADNJ.

    Abstract

    Abstract:

    All neurodegenerative diseases are associated with the intracellular accumulation of substances that impair cellular function and viability. Reversing this accumulation may thus be valuable, but has proven challenging, doubtless because substances resistant to cellular catabolism are inherently hard to degrade. I suggest a radically new approach: augmenting humans’ natural catabolic machinery with microbial enzymes. Many highly recalcitrant organic molecules are naturally degraded in the soil. Since the soil in certain environments – graveyards, for example – is enriched in human remains but does not accumulate these substances, it presumably harbours microbes that degrade them. The enzymes responsible could be identified and engineered to metabolise these substances in vivo.

  • Nixon RA, Wegiel J, Kumar A, Yu WH, Peterhoff C, Cataldo A, Cuervo AM. Extensive involvement of autophagy in Alzheimer disease: an immuno-electron microscopy study. J Neuropathol Exp Neurol 2005;64(2):113-122. PubMed: 15751225. Categories: AmyloSENS, LysoSENS

    Extensive involvement of autophagy in Alzheimer disease: an immuno-electron microscopy study.

    J Neuropathol Exp Neurol 2005;64(2):113-122.

    Extensive involvement of autophagy in Alzheimer disease: an immuno-electron microscopy study.

    Nixon RA, Wegiel J, Kumar A, Yu WH, Peterhoff C, Cataldo A, Cuervo AM.

    Abstract

    Abstract:

    The accumulation of lysosomes and their hydrolases within neurons is a well-established neuropathologic feature of Alzheimer disease (AD). Here we show that lysosomal pathology in AD brain involves extensive alterations of macroautophagy, an inducible pathway for the turnover of intracellular constituents, including organelles. Using immunogold labeling with compartmental markers and electron microscopy on neocortical biopsies from AD brain, we unequivocally identified autophagosomes and other prelysosomal autophagic vacuoles (AVs), which were morphologically and biochemically similar to AVs highly purified from mouse liver. AVs were uncommon in brains devoid of AD pathology but were abundant in AD brains particularly, within neuritic processes, including synaptic terminals. In dystrophic neurites, autophagosomes, multivesicular bodies, multilamellar bodies, and cathepsin-containing autophagolysosomes were the predominant organelles and accumulated in large numbers. These compartments were distinguishable from lysosomes and lysosomal dense bodies, previously shown also to be abundant in dystrophic neurites. Autophagy was evident in the perikarya of affected neurons, particularly in those with neurofibrillary pathology where it was associated with a relative depletion of mitochondria and other organelles. These observations provide the first evidence that macroautophagy is extensively involved in the neurodegenerative/regenerative process in AD. The striking accumulations of immature AV forms in dystrophic neurites suggest that the transport of AVs and their maturation to lysosomes may be impaired, thereby impeding the suspected neuroprotective functions of autophagy.

  • Butler D, Brown QB, Chin DJ, Batey L, Karim S, Mutneja MS, Karanian DA, Bahr BA. Degradative pathways responding to age-related protein accumulation involve autophagy and lysosomal enzyme activation. Rejuvenation Res 2005;8(4):227-237. PubMed: 16313222. Categories: LysoSENS

    Degradative pathways responding to age-related protein accumulation involve autophagy and lysosomal enzyme activation.

    Rejuvenation Res 2005;8(4):227-237.

    Degradative pathways responding to age-related protein accumulation involve autophagy and lysosomal enzyme activation.

    Butler D, Brown QB, Chin DJ, Batey L, Karim S, Mutneja MS, Karanian DA, Bahr BA.

    Abstract

    Abstract:

    Protein oligomerization and aggregation are key events in age-related neurodegenerative disorders, causing neuronal disturbances including microtubule destabilization, transport failure and loss of synaptic integrity that precede cell death. The abnormal buildup of proteins can overload digestive systems and this, in turn, activates lysosomes in different disease states and stimulates the inducible class of lysosomal protein degradation, macroautophagy. These responses were studied in a hippocampal slice model well known for amyloidogenic species, tau aggregates, and ubiquitinated proteins in response to chloroquine-mediated disruption of degradative processes. Chloroquine was found to cause a pronounced appearance of prelysosomal autophagic vacuoles in pyramidal neurons. The vacuoles and dense bodies were concentrated in the basal pole of neurons and in dystrophic neurites. In hippocampal slice cultures treated with Abeta(142), ultrastructural changes were also induced. Autophagic responses may be an attempt to compensate for protein accumulation, however, they were not sufficient to prevent axonopathy indicated by swellings, transport deficits, and reduced expression of synaptic components. Additional chloroquine effects included activation of cathepsin D and other lysosomal hydrolases. Abeta(142) produced similar lysosomal activation, and the effects of Abeta(142) and chloroquine were not additive, suggesting a common mechanism. Activated levels of cathepsin D were enhanced with the lysosomal modulator Z-Phe-Ala-diazomethylketone (PADK). PADK-mediated lysosomal enhancement corresponded with the restoration of synaptic markers, in association with stabilization of microtubules and transport capability. To show that PADK can modulate the lysosomal system in vivo, IP injections were administered over a 5-day period, resulting in a dose-dependent increase in lysosomal hydrolases. The findings indicate that degradative responses can be modulated to promote synaptic maintenance.

  • Du H, Schiavi S, Wan N, Levine M, Witte DP, Grabowski GA. Reduction of atherosclerotic plaques by lysosomal acid lipase supplementation. Arterioscler Thromb Vasc Biol 2004;24(1):147-154. PubMed: 14615393. Categories: LysoSENS

    Reduction of atherosclerotic plaques by lysosomal acid lipase supplementation.

    Arterioscler Thromb Vasc Biol 2004;24(1):147-154.

    Reduction of atherosclerotic plaques by lysosomal acid lipase supplementation.

    Du H, Schiavi S, Wan N, Levine M, Witte DP, Grabowski GA.

    Abstract

    Abstract:

    OBJECTIVE: Proof of principle is presented for targeted enzyme supplementation by using lysosomal acid lipase to decrease aortic and coronary wall lipid accumulation in a mouse model of atherosclerosis. METHODS AND RESULTS: Mice with LDL receptor deficiency were placed on an atherogenic diet and developed predictable aortic and coronary atheroma. alpha-Mannosyl-terminated human lysosomal acid lipase (phLAL) was produced in Pichia pastoris, purified, and administered intravenously to such mice with either early or late lesions. phLAL injections reduced plasma, hepatic, and splenic cholesteryl esters and triglycerides in affected mice. phLAL was detected in hepatic Kupffer cells and in atheromatous foam cells. Repeated enzyme injections were well tolerated, with no obvious adverse effects. In addition, the coronary and aortic atheromatous lesions were (1) eliminated in their early stages and (2) quantitatively and qualitatively reduced in their advanced stages. CONCLUSIONS: These results support the potential utility of lysosomal acid lipase supplementation for the treatment of atherosclerosis, a leading cause of mortality and morbidity in Westernized nations.

  • Porta EA. Pigments in aging: an overview. Ann N Y Acad Sci 2002;959:57-65. PubMed: 11976186. Categories: LysoSENS

    Pigments in aging: an overview.

    Ann N Y Acad Sci 2002;959:57-65.

    Pigments in aging: an overview.

    Porta EA.

    Abstract

    Abstract:

    Although during the normal aging process there are numerous pigmentary changes, the best recognized are those of melanin and lipofuscin. Melanin may increase (e.g., age spots, senile lentigo, or melanosis coli) or decrease (e.g., graying of hair or ocular melanin) with age, while lipofuscin (also called age pigment) always increases with age. In fact, the time-dependent accumulation of lipofuscin in lysosomes of postmitotic cells and some stable cells is the most consistent and phylogenetically constant morphologic change of aging. This pigment displays a typical autofluorescence (Ex: approximately 440; Em: approximately 600 nm), sudanophilia, argyrophilia, PAS positiveness, and acid fastness. Advances on its biogenesis, composition, evolution, and lysosomal degradation have been hampered by the persistent confusion between lipofuscin and the large family of ceroid pigments found in a variety of pathological conditions, as evidenced by the frequent use of the hybrid term lipofuscin/ceroid by investigators mainly working with in vitro systems of disputable relevance to in vivo lipofuscinogenesis. While lipofuscin and ceroid pigments may share some of their physicochemical properties at one moment or another in their evolutions, these pigments have different tissue distribution, rates of accumulation, origin of their precursors, and lectin binding affinities. Although it is widely believed that lipofuscin is a marker of oxidative stress, and that it can be, therefore, modified by antioxidants and prooxidants, these assumptions are mainly based on in vitro experiments and are not generally supported by in vivo studies. Another common misconception is the belief that lipofuscin can be extracted from tissues by lipid solvents and measured spectrofluorometrically. These and other disturbing problems are reviewed and discussed in this presentation.

  • Katz ML. Potential reversibility of lipofuscin accumulation. Arch Gerontol Geriatr 2002;34(3):311-317. PubMed: 14764332. Categories: LysoSENS

    Potential reversibility of lipofuscin accumulation.

    Arch Gerontol Geriatr 2002;34(3):311-317.

    Potential reversibility of lipofuscin accumulation.

    Katz ML.

    Abstract

    Abstract:

    It is well established that the lipofuscin content of many post-mitotic cell types increases progressively during normal senescence. This age-related accumulation of lipofuscin may occur either: (1) because lipofuscin, once formed, is never degraded or eliminated from cells; or (2) because, despite turnover of this pigment, the rate of lipofuscin formation exceeds the rate at which it is eliminated. Little research has been performed to distinguish between these possibilities. Several studies suggest that lipofuscin may be turned over. However, definitive demonstrations that such turnover does occur under normal circumstances are lacking. It is possible to specifically halt new lipofuscin formation in the retinal pigment epithelium (RPE) of animals at an age when significant amounts of lipofuscin have accumulated in these cells. By monitoring the RPE for possible decreases in lipofuscin content after new pigment formation has been halted, it should be possible to determine whether previously formed lipofuscin can be eliminated from the RPE.

  • Brunk UT, Terman A. The mitochondrial-lysosomal axis theory of aging: accumulation of damaged mitochondria as a result of imperfect autophagocytosis. Eur J Biochem 2002;269(8):1996-2002. PubMed: 11985575. Categories: LysoSENS, MitoSENS

    The mitochondrial-lysosomal axis theory of aging: accumulation of damaged mitochondria as a result of imperfect autophagocytosis.

    Eur J Biochem 2002;269(8):1996-2002.

    The mitochondrial-lysosomal axis theory of aging: accumulation of damaged mitochondria as a result of imperfect autophagocytosis.

    Brunk UT, Terman A.

    Abstract

    Abstract:

    Cellular manifestations of aging are most pronounced in postmitotic cells, such as neurons and cardiac myocytes. Alterations of these cells, which are responsible for essential functions of brain and heart, are particularly important contributors to the overall aging process. Mitochondria and lysosomes of postmitotic cells suffer the most remarkable age-related alterations of all cellular organelles. Many mitochondria undergo enlargement and structural disorganization, while lysosomes, which are normally responsible for mitochondrial turnover, gradually accumulate an undegradable, polymeric, autofluorescent material called lipofuscin, or age pigment. We believe that these changes occur not only due to continuous oxidative stress (causing oxidation of mitochondrial constituents and autophagocytosed material), but also because of the inherent inability of cells to completely remove oxidatively damaged structures (biological 'garbage'). A possible factor limiting the effectiveness of mitochondial turnover is the enlargement of mitochondria which may reflect their impaired fission. Non-autophagocytosed mitochondria undergo further oxidative damage, resulting in decreasing energy production and increasing generation of reactive oxygen species. Damaged, enlarged and functionally disabled mitochondria gradually displace normal ones, which cannot replicate indefinitely because of limited cell volume. Although lipofuscin-loaded lysosomes continue to receive newly synthesized lysosomal enzymes, the pigment is undegradable. Therefore, advanced lipofuscin accumulation may greatly diminish lysosomal degradative capacity by preventing lysosomal enzymes from targeting to functional autophagosomes, further limiting mitochondrial recycling. This interrelated mitochondrial and lysosomal damage irreversibly leads to functional decay and death of postmitotic cells.

  • de Grey ADNJ. Bioremediation meets biomedicine: therapeutic translation of microbial catabolism to the lysosome. Trends Biotechnol 2002;20(11):452-455. PubMed: 12413818. Categories: LysoSENS

    Bioremediation meets biomedicine: therapeutic translation of microbial catabolism to the lysosome.

    Trends Biotechnol 2002;20(11):452-455.

    Bioremediation meets biomedicine: therapeutic translation of microbial catabolism to the lysosome.

    de Grey ADNJ.

    Abstract

    Abstract:

    Lysosomal degradation of damaged macromolecules is imperfect: many cell types accumulate lysosomal aggregates with age. Some such deposits are known, or are strongly suspected, to cause age-related disorders such as atherosclerosis and neurodegeration. It is possible that they also influence the rate of aging in general. Lysosomal degradation involves extensive cooperation between the participating enzymes: each generates a substrate for others until breakdown of the target material to recyclable units (such as amino acids) is complete. Hence, the age-related accumulation of lysosomal aggregates might be markedly retarded, or even reversed, by introducing just a few bacterial or fungal enzymes -'xenohydrolases' - that can degrade molecules that our natural machinery cannot. This article examines the feasibility and biomedical potential of such lysosomal enhancement as an approach to retarding or treating age-related physiological decline and disease.

  • Terman A, Sandberg S. Proteasome inhibition enhances lipofuscin formation. Ann N Y Acad Sci 2002;973:309-312. PubMed: 12485885. Categories: LysoSENS

    Proteasome inhibition enhances lipofuscin formation.

    Ann N Y Acad Sci 2002;973:309-312.

    Proteasome inhibition enhances lipofuscin formation.

    Terman A, Sandberg S.

    Abstract

    Abstract:

    Lipofuscin, a hallmark of aged nondividing cells, is an undegradable autofluorescent intralysosomal substance composed essentially of oxidized, cross-linked proteins. To test whether impaired activity of proteasomes-which, along with lysosomes, belong to major cellular proteolytic systems-may contribute to lipofuscinogenesis, we exposed growth-arrested human fibroblasts to subapoptotic doses (2 and 5 nM) of a highly specific proteasome inhibitor, MG-262. This resulted in accelerated lipofuscin accumulation (especially when MG-262 exposure was combined with mild hyperoxia-i.e., cultivation at 40% ambient oxygen versus 8% for controls); and enhanced immunostaining for ubiquitin, reflecting accumulation of modified cytosolic proteins subjected for degradation, and cathepsin L, reflecting enlargement of the lysosomal compartment. These data suggest that insufficient proteasomal function may contribute to lipofuscinogenesis by a compensatory increase in the amount of proteins that are difrected for lysosomal degradation. The findings may be helpful for the understanding of cellular aging as well as diseases associated with intralysosomal accumulation of undegradable material.

  • Thomas SR, Stocker R. Molecular action of vitamin E in lipoprotein oxidation: implications for atherosclerosis. Free Radic Biol Med 2000;28(12):1795-1805. PubMed: 10946221. Categories: LysoSENS

    Molecular action of vitamin E in lipoprotein oxidation: implications for atherosclerosis.

    Free Radic Biol Med 2000;28(12):1795-1805.

    Molecular action of vitamin E in lipoprotein oxidation: implications for atherosclerosis.

    Thomas SR, Stocker R.

    Abstract

    Abstract:

    The oxidation theory of atherosclerosis proposes that the oxidative modification of low-density lipoproteins (LDL) plays a central role in the disease. Although a direct causative role of LDL oxidation for atherogenesis has not been established, oxidized lipoproteins are detected in atherosclerotic lesions, and in vitro oxidized LDL exhibits putative pro-atherogenic activities. alpha-Tocopherol (alpha-TOH; vitamin E), the major lipid-soluble antioxidant present in lipoproteins, is thought to be antiatherogenic. However, results of vitamin E interventions on atherosclerosis in experimental animals and cardiovascular disease in humans have been inconclusive. Also, recent mechanistic studies demonstrate that the role of alpha-TOH during the early stages of lipoprotein lipid peroxidation is complex and that the vitamin does not act as a chain-breaking antioxidant. In the absence of co-antioxidants, compounds capable of reducing the alpha-TOH radical and exporting the radical from the lipoprotein particle, alpha-TOH exhibits anti- or pro-oxidant activity for lipoprotein lipids depending on the degree of radical flux and reactivity of the oxidant. The model of tocopherol-mediated peroxidation (TMP) explains the complex molecular action of alpha-TOH during lipoprotein lipid peroxidation and antioxidation. This article outlines the salient features of TMP, comments on whether TMP is relevant for in vivo lipoprotein lipid oxidation, and discusses how co-antioxidants may be required to attenuate lipoprotein lipid oxidation in vivo and perhaps atherosclerosis.

  • Lusis AJ. Atherosclerosis. Nature 2000;407(6801):233-241. PubMed: 11001066. Categories: LysoSENS

    Atherosclerosis.

    Nature 2000;407(6801):233-241.

    Atherosclerosis.

    Lusis AJ.

    Abstract

    Abstract:

    Atherosclerosis, a disease of the large arteries, is the primary cause of heart disease and stroke. In westernized societies, it is the underlying cause of about 50% of all deaths. Epidemiological studies have revealed several important environmental and genetic risk factors associated with atherosclerosis. Progress in defining the cellular and molecular interactions involved, however, has been hindered by the disease's aetiological complexity. Over the past decade, the availability of new investigative tools, including genetically modified mouse models of disease, has resulted in a clearer understanding of the molecular mechanisms that connect altered cholesterol metabolism and other risk factors to the development of atherosclerotic plaque. It is now clear that atherosclerosis is not simply an inevitable degenerative consequence of ageing, but rather a chronic inflammatory condition that can be converted into an acute clinical event by plaque rupture and thrombosis.

  • Andrews LD, Brizzee KR. Lipofuscin in retinal pigment epithelium of rhesus monkey: lack of diminution with centrophenoxine treatment. Neurobiol Aging 1986;7(2):107-113. PubMed: 3083280. Categories: LysoSENS

    Lipofuscin in retinal pigment epithelium of rhesus monkey: lack of diminution with centrophenoxine treatment.

    Neurobiol Aging 1986;7(2):107-113.

    Lipofuscin in retinal pigment epithelium of rhesus monkey: lack of diminution with centrophenoxine treatment.

    Andrews LD, Brizzee KR.

    Abstract

    Abstract:

    An experiment was performed to test the ability of Centrophenoxine to reduce the amount of lipofuscin (age pigment) in the retinal pigment epithelium (RPE) of aged rhesus monkeys. Centrophenoxine is reputed to have this action in neurons of lower mammals. Quantitative electron microscopic analysis was performed on sections from the perifovea of ten rhesus monkeys, all approximately 20 years of age. Four of the animals received 80 mg/kg Centrophenoxine (IM injection) daily for 12 weeks. No significant difference between the treated and control groups could be demonstrated statistically (Mann-Whitney U-test) either in the fraction of RPE cell cytoplasm occupied by lipofuscin granules or in the average size of the granules.

  • Dowson JH. Quantitative studies of the effects of aging, meclofenoxate, and dihydroergotoxine on intraneuronal lipopigment accumulation in the rat. Exp Gerontol 1985;20(6):333-340. PubMed: 3938737. Categories: LysoSENS

    Quantitative studies of the effects of aging, meclofenoxate, and dihydroergotoxine on intraneuronal lipopigment accumulation in the rat.

    Exp Gerontol 1985;20(6):333-340.

    Quantitative studies of the effects of aging, meclofenoxate, and dihydroergotoxine on intraneuronal lipopigment accumulation in the rat.

    Dowson JH.

    Abstract

    Abstract:

    Intraneuronal lipopigment accumulation is associated with ageing and certain diseases, and there are many claims that this can be influenced by drugs, particularly meclofenoxate (centrophenoxine). The various unsubstantiated or conflicting reports of the effects of this drug in animal studies indicate the need for methods for the demonstration of lipopigment accumulation in adequately defined, easily-identified, and relatively homogeneous neuronal populations; this study has validated two such methods by demonstrating significant differences between groups of rats at different ages in respect of measured lipopigment autofluorescence intensity from the most heavily pigmented regions of a subpopulation of Purkinje cells, and of the area overlying intraneuronal lipopigment in a region of the hippocampus. These methods were then used to investigate the effects of daily (5 days per week) intraperitoneal injections of meclofenoxate or dihydroergotoxine, over a period of 12 weeks, before sacrifice at 13.5 months. No significant effects of meclofenoxate were detected, but dihydroergotoxine administration was associated with a significant increase in mean area overlying intraneuronal lipopigment in the CA3a region of the hippocampus. The results do not confirm that meclofenoxate can induce a reduction in intraneuronal lipopigment, but suggest that chronic dihydroergotoxine administration was associated with an increase in intraneuronal volume of lipopigment in the cell bodies of CA3a hippocampal neurones.

  • Katz ML, Robison WG Jr. Lipofuscin response to the "aging-reversal" drug centrophenoxine in rat retinal pigment epithelium and frontal cortex. J Gerontol 1983;38(5):525-531. PubMed: 6411800. Categories: LysoSENS

    Lipofuscin response to the "aging-reversal" drug centrophenoxine in rat retinal pigment epithelium and frontal cortex.

    J Gerontol 1983;38(5):525-531.

    Lipofuscin response to the "aging-reversal" drug centrophenoxine in rat retinal pigment epithelium and frontal cortex.

    Katz ML, Robison WG Jr.

    Abstract

    Abstract:

    The effects of centrophenoxine on the lipofuscin contents of the retinal pigment epithelium (RPE) and frontal cortex of the brain were examined in senescent female Fischer rats. Rats (106 weeks old) were injected daily for 11 weeks with centrophenoxine (80 to 120 mg/kg body weight) or saline, and then sacrificed along with untreated 28- and 46-week-old controls. The number of lipofuscin granules seen in the RPE by light microscopy increased by 70% between 28 and 117 weeks of age in control animals. There was a concomitant age-related increase in lipofuscin specific fluorescence in the RPE. Centrophenoxine treatment neither reduced the amount of lipofuscin, nor altered the ultrastructural appearance of lipofuscin granules in the RPE. Between 28 and 117 weeks of age, there was an almost nine-fold increase in the lipofuscin content of the frontal cortex of control animals; centrophenoxine treatment failed to reverse this pigment accumulation.