C-phycocyanin confers protection against oxalate-mediated oxidative stress and mitochondrial dysfunctions in MDCK cells

E53, E96, D162, E247 and D322 in Ca2+-binding domains of annexin A2 are essential for regulating intracellular [Ca2+] and crystal adhesion to renal cells via ERK1/2 and JNK signaling pathways

Annexin A2 (ANXA2) is expressed inside the cytoplasm and on the surface of renal tubular epithelial cells (RTECs) and is documented as a calcium oxalate monohydrate (COM) crystal-binding protein. Nevertheless, its molecular mechanism involved in kidney stone disease (KSD) remains underinvestigated. Herein, we performed various molecular assays to unravel the roles of ANXA2 and core residues (E53, E96, D162, E247 and D322) in its Ca2+-binding domains in the stone formation mechanism, particularly at crystal-cell adhesion step and downstream signaling cascade. ANXA2 was up-regulated in apical membranes, not cytosol, of RTECs after COM crystal exposure. Neutralizing the surface expression of ANXA2 by a specific monoclonal antibody and silencing its expression by small interfering RNA (siRNA) significantly decreased COM crystal-cell adhesion. siRNA also suppressed the COM-induced up-regulation of phospho-ERK1/2 and phospho-JNK, but not that of phospho-p38. Overexpression of ANXA2 wild-type (WT), but not that of E53A, E96A, D162A, E247A and D322A mutants of its Ca2+-binding domains, significantly increased intracellular [Ca2+], COM-cell adhesion, and phospho-ERK1/2 level. Therefore, E53, E96, D162, E247 and D322 in the Ca2+-binding domains of annexin A2 are essential for regulating intracellular [Ca2+] and COM crystal-cell adhesion via ERK1/2 and JNK signaling pathways.

Cyanobacterial Phycocyanin-Based Electrochemical Biosensor for the Detection of the Free Radical Hydrogen Peroxide

Cyanobacteria are photosynthetic prokaryotes that inhabit extreme environments by modifying their photosensitive chemoreceptors called cyanobacteriochromes (CBCRs) which are linear tetrapyrrole-linked phycobilin molecules. These light-sensitive phycobilin from Spirulina platensis is recognized as a potential photoreceptor tool in optogenetics for monitoring cellular morphogenesis. We prepared and extracted highly fluorescent cyanobacterial phycocyanin (C-PC) by irradiating the culture with ambient red light. The crude phycocyanin was subjected to ion exchange chromatography, and its purity was monitored using UV-visible, fluorescence, and FT-IR spectroscopy methods. In the conventional method, red light-induced C-PC exhibited strong antioxidant activity against H2O2, with 88.7% in vitro scavenging activity without requiring any other preservatives. Interestingly, this red light-acclimated phycocyanin was applied as a biosensing material for the detection of the free radical hydrogen peroxide (H2O2) using the enzyme horseradish peroxidase (HRP) as a mediator. The modified C-PC-HRP glassy carbon electrode (GCE) can detect H2O2 from 0.1 to 1600 µM. The lowest possible detection limit of the electrode for H2O2 was 19 nM. This electrode was used to detect free radical H2O2 in blood serum samples. The microstructure of the lyophilized PC under SEM showed a flat crystal pattern, which enabled the immobilization of HRP on the electrode surface and electron transfer.

Nutraceutical Features of the Phycobiliprotein C-Phycocyanin: Evidence from Arthrospira platensis (Spirulina)

Arthrospira platensis, commonly known as Spirulina, is a photosynthetic filamentous cyanobacterium (blue-green microalga) that has been utilized as a food source since ancient times. More recently, it has gained significant popularity as a dietary supplement due to its rich content of micro- and macro-nutrients. Of particular interest is a water soluble phycobiliprotein derived from Spirulina known as phycocyanin C (C-PC), which stands out as the most abundant protein in this cyanobacterium. C-PC is a fluorescent protein, with its chromophore represented by the tetrapyrrole molecule phycocyanobilin B (PCB-B). While C-PC is commonly employed in food for its coloring properties, it also serves as the molecular basis for numerous nutraceutical features associated with Spirulina. Indeed, the comprehensive C-PC, and to some extent, the isolated PCB-B, has been linked to various health-promoting effects. These benefits encompass conditions triggered by oxidative stress, inflammation, and other pathological conditions. The present review focuses on the bio-pharmacological properties of these molecules, positioning them as promising agents for potential new applications in the expanding nutraceutical market.

Phycocyanin alleviates alcohol-induced testicular injury in male Wistar rats

OBJECTIVE

Given the noteworthy implications of alcohol consumption and its association with male infertility, there has been a notable focus on investigating natural alternatives to mitigate its adverse effects. Thus, this study was conducted to assess the potential protective effect of phycocyanin extract derived from the blue algae Arthrospira (Spirulina) platensis against ethanol-induced oxidative stress, disturbances in testicular morphology, and alterations in sperm production.

METHODS

Male rats were divided into four groups (five rats each): the control group received a saline solution, the ethanol exposed group (EtOH) was subjected to intraperitoneal injections of 10 mL/kg of ethanol solution at a concentration of 38% (v/v), the phycocyanin alone treated group (P) received oral administration of phycocyanin at a dosage of 50 mg/kg, and the phycocyanin-cotreated group (PE) was given oral phycocyanin followed by ethanol injections. All treatments were administered over a period of 14 days.

RESULTS

Our findings demonstrated that ethanol exposure induced reproductive toxicity, characterized by reduced sperm production and viability, alterations in testicular weight and morphology, increased lipid peroxidation levels, and elevated oxidative enzyme activity. In addition, the ethanol-intoxicated group showed perturbations in serum biochemical parameters. However, the simultaneous exposure to ethanol and phycocyanin exhibited a counteractive effect against ethanol toxicity.

CONCLUSION

The results showed that supplementation of phycocyanin prevented oxidative and testicular morphological damage-induced by ethanol and maintained normal sperm production, and viability.

The antioxidant l-Ergothioneine prevents cystine lithiasis in the Slc7a9-/- mouse model of cystinuria

The high recurrence rate of cystine lithiasis observed in cystinuria patients highlights the need for new therapeutic options to address this chronic disease. There is growing evidence of an antioxidant defect in cystinuria, which has led to test antioxidant molecules as new therapeutic approaches. In this study, the antioxidant l-Ergothioneine was evaluated, at two different doses, as a preventive and long-term treatment for cystinuria in the Slc7a9-/- mouse model. l-Ergothioneine treatments decreased the rate of stone formation by more than 60% and delayed its onset in those mice that still developed calculi. Although there were no differences in metabolic parameters or urinary cystine concentration between control and treated mice, cystine solubility was increased by 50% in the urines of treated mice. We also demonstrate that l-Ergothioneine needs to be internalized by its transporter OCTN1 (Slc22a4) to be effective, as when administrated to the double mutant Slc7a9-/-Slc22a4-/- mouse model, no effect on the lithiasis phenotype was observed. In kidneys, we detected a decrease in GSH levels and an impairment of maximal mitochondrial respiratory capacity in cystinuric mice that l-Ergothioneine treatment was able to restore. Thus, l-Ergothioneine administration prevented cystine lithiasis in the Slc7a9-/- mouse model by increasing urinary cystine solubility and recovered renal GSH metabolism and mitochondrial function. These results support the need for clinical trials to test l-Ergothioneine as a new treatment for cystinuria.

Proposal for pathogenesis-based treatment options to reduce calcium oxalate stone recurrence

Objective

Prevalence of kidney stone disease continues to increase globally with recurrence rates between 30% and 50% despite technological and scientific advances. Reduction in recurrence would improve patient outcomes and reduce cost and stone morbidities. Our objective was to review results of experimental studies performed to determine the efficacy of readily available compounds that can be used to prevent recurrence.

Methods

All relevant literature up to October 2020, listed in PubMed is reviewed.

Results

Clinical guidelines endorse the use of evidence-based medications, such as alkaline agents and thiazides, to reduce urinary mineral supersaturation and recurrence. However, there may be additional steps during stone pathogenesis where medications could moderate stone risk. Idiopathic calcium oxalate stones grow attached to Randall's plaques or plugs. Results of clinical and experimental studies suggest involvement of reactive oxygen species and oxidative stress in the formation of both the plaques and plugs. The renin-angiotensin-aldosterone system (RAAS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, mitochondria, and NOD-like receptor pyrin domain containing-3 (NLRP3) inflammasome have all been implicated at specific steps during stone pathogenesis in animal models.

Conclusion

In addition to supersaturation-reducing therapies, the use of anti-oxidants, free radical scavengers, and inhibitors of NADPH oxidase, NLRP3 inflammasome, and RAAS may prove beneficial for stone prevention. Compounds such as statins and angiotensin converting enzyme inhibitors are already in use as therapeutics for hypertension and cardio-vascular disease and have previously shown to reduce calcium oxalate nephrolithiasis in rats. Although clinical evidence for their use in stone prevention in humans is limited, experimental data support they be considered along with standard evidence-based medications and clinical expertise when patients are being counselled for stone prevention.

Exploring the Benefits of Phycocyanin: From Spirulina Cultivation to Its Widespread Applications

Large-scale production of microalgae and their bioactive compounds has steadily increased in response to global demand for natural compounds. Spirulina, in particular, has been used due to its high nutritional value, especially its high protein content. Promising biological functions have been associated with Spirulina extracts, mainly related to its high value added blue pigment, phycocyanin. Phycocyanin is used in several industries such as food, cosmetics, and pharmaceuticals, which increases its market value. Due to the worldwide interest and the need to replace synthetic compounds with natural ones, efforts have been made to optimize large-scale production processes and maintain phycocyanin stability, which is a highly unstable protein. The aim of this review is to update the scientific knowledge on phycocyanin applications and to describe the reported production, extraction, and purification methods, including the main physical and chemical parameters that may affect the purity, recovery, and stability of phycocyanin. By implementing different techniques such as complete cell disruption, extraction at temperatures below 45 °C and a pH of 5.5-6.0, purification through ammonium sulfate, and filtration and chromatography, both the purity and stability of phycocyanin have been significantly improved. Moreover, the use of saccharides, crosslinkers, or natural polymers as preservatives has contributed to the increased market value of phycocyanin.

Mechanisms of action of non-enzymatic antioxidants to control oxidative stress during in vitro follicle growth, oocyte maturation, and embryo development

In vitro follicle growth and oocyte maturation still has a series of limitations, since not all oocytes matured in vitro have the potential to develop in viable embryos. One of the factors associated with low oocyte quality is the generation of reactive oxygen species (ROS) during in vitro culture. Therefore, this review aims to discuss the role of non-enzymatic antioxidants in the control of oxidative stress during in vitro follicular growth, oocyte maturation and embryonic development. A wide variety of non-enzymatic antioxidants (melatonin, resveratrol, L-ascorbic acid, L-carnitine, N-acetyl-cysteine, cysteamine, quercetin, nobiletin, lycopene, acteoside, mogroside V, phycocyanin and laminarin) have been used to supplement culture media. Some of them, like N-acetyl-cysteine, cysteamine, nobiletin and quercetin act by increasing the levels of glutathione (GSH), while melatonin and resveratrol increase the expression of antioxidant enzymes and minimize oocyte oxidative stress. L-ascorbic acid reduces free radicals and reactive oxygen species. Lycopene positively regulates the expression of many antioxidant genes. Additionally, L-carnitine protects DNA against ROS-induced damage, while acteoside and laminarin reduces the expression of proapoptotic genes. Mogrosides increases mitochondrial function and reduces intracellular ROS levels, phycocyanin reduces lipid peroxidation, and lycopene neutralizes the adverse effects of ROS. Thus, it is very important to know their mechanisms of actions, because the combination of two or more antioxidants with different activities has great potential to improve in vitro culture systems.

Elucidation of Antiviral and Antioxidant Potential of C-Phycocyanin against HIV-1 Infection through In Silico and In Vitro Approaches

Antiretroviral therapy is the single existing therapy for patients infected with HIV; however, it has drawbacks in terms of toxicity and resistance. Thus, there is a continuous need to explore safe and efficacious anti-retroviral agents. C-Phycocyanin (C-PC) is a phycobiliprotein, which has been known for various biological properties; however, its effect on HIV-1 replication needs revelation. This study aimed to identify the inhibitory effects of C-PC on HIV-1 using in vitro and in silico approaches and to assess its role in the generation of mitochondrial reactive oxygen species (ROS) during HIV-1 infection. In vitro anti-HIV-1 activity of C-PC was assessed on TZM-bl cells through luciferase gene assay against four different clades of HIV-1 strains in a dose-dependent manner. Results were confirmed in PBMCs, using the HIV-1 p24 antigen assay. Strong associations between C-PC and HIV-1 proteins were observed through in silico molecular simulation-based interactions, and the in vitro mechanistic study confirmed its target by inhibition of reverse transcriptase and protease enzymes. Additionally, the generation of mitochondrial ROS was detected by the MitoSOX and DCF-DA probe through confocal microscopy. Furthermore, our results confirmed that C-PC treatment notably subdued the fluorescence in the presence of the virus, thus reduction of ROS and the activation of caspase-3/7 in HIV-1-infected cells. Overall, our study suggests C-PC as a potent and broad in vitro antiviral and antioxidant agent against HIV-1 infection.

Anti-Aging Effects of R-Phycocyanin from Porphyra haitanensis on HUVEC Cells and Drosophila melanogaster

Aging has become a global public health challenge. Many studies have revealed that the excessive generation of ROS and oxidative stress could be the major causative factors contributing to aging. In this study, R-phycocyanin (R-PC) was isolated from Porphyra haitanensis, and its anti-aging ability was explored by natural aging Drosophila melanogaster and H₂O₂-induced HUVEC cells as the aging model. Results showed that R-PC α and β subunits expressed have antioxidant activity and can inhibit the generation of radicals, exhibiting a protective effect against H₂O₂-induced apoptotic HUVEC cells death. R-PC prevented the H₂O₂-induced HUVEC cell cycle phase arrest by regulating cell cycle-related protein. Furthermore, R-PC prevented the H₂O₂-induced HUVEC cell cycle phase arrest by regulating cell-cycle-related protein expression. In vivo study also indicated that R-PC significantly increased the survival time and alleviated the oxidative stress of Drosophila melanogaster. Moreover, R-PC notably decreased levels of ROS in natural aging flies and inhibited lipid peroxidation by enhancing the expressions of the endogenous stress marker genes (SOD1, SOD2, CAT of Drosophila melanogaster). Taken together, a study on the antioxidation extract from Porphyra haitanensis, such as R-PC, may open a new window for the prevention of anti-aging.

Therapeutical and Nutraceutical Roles of Cyanobacterial Tetrapyrrole Chromophore: Recent Advances and Future Implications

Cyanobacteria have attracted the attention of researchers because of their promising role as primary and secondary metabolites in functional food and drug design. Due to an ever-increasing awareness of health and the use of natural products to avoid the onset of many chronic and lifestyle metabolic diseases, the global demand for the use of natural drugs and food additives has increased in the last few decades. There are several reports about the highly valuable cyanobacterial products such as carotenoids, vitamins, minerals, polysaccharides, and phycobiliproteins showing antioxidant, anti-cancerous, anti-inflammatory, hypoglycemic, and antimicrobial properties. Recently, it has been shown that allophycocyanin increases longevity and reduces the paralysis effect at least in Caenorhabditis elegans. Additionally, other pigments such as phycoerythrin and phycocyanin show antioxidative properties. Because of their high solubility in water and zero side effects, some of the cyanobacterial tetrapyrrole derivatives, i.e., pigments, facilitate an innovative and alternative way for the beverage and food industries in place of synthetic coloring agents at the commercial level. Thus, not only are the tetrapyrrole derivatives essential constituents for the synthesis of most of the basic physiological biomolecules, such as hemoglobin, chlorophyll, and cobalamin, but also have the potential to be used for the synthesis of synthetic compounds used in the pharmaceutical and nutraceutical industries. In the present review, we focused on the different aspects of tetrapyrrole rings in the drug design and food industries and addressed its remaining limitations to be used as natural nutrient supplements and therapeutic agents.

Inhibition of EZH2 ameliorates hyperoxaluria-induced kidney injury through the JNK/FoxO3a pathway

AIMS

Enhancer of zeste homolog 2 (EZH2), a histone H3 lysine 27 methyltransferase, has been shown to play a role in kidney diseases. However, its role in hyperoxaluria-induced renal tubular epithelial cells (TECs) injury remains unclear.

MATERIALS AND METHODS

A hyperoxaluria rat model was established by providing 0.5% ammonium chloride and drinking water containing 1% ethylene glycol. TECs were exposed to oxalate stress. The 3-DZNeP, a selective EZH2 inhibitor, was administered in vivo and in vitro. Cell viability, ROS production, and apoptosis ratio were evaluated. Crystal deposition was detected by Von Kossa staining and kidney tissue injury was detected by HE staining and TUNEL. EZH2, H3K27me3, cleaved-caspase3, IL-6, and MCP-1 were examined by western blot or immunohistochemistry.

KEY FINDINGS

Inhibition of EZH2 by 3-DZNeP significantly attenuated hyperoxaluria-induced oxidative and inflammatory injury and CaOx crystal deposition in vivo. Similarly, inhibition of EZH2 using 3-DZNeP or shRNA restored cell viability, suppressed LDH release and the production of intracellular ROS in vitro. Furthermore, the MAPK signaling pathway and FoxO3a levels were activated or elevated in TECs exposed to oxalate. EZH2 inhibition using 3-DZNeP blocked these effects. CC90003 (ERK inhibitor) or SB203580 (p38 inhibitor) did not significantly affect the expression of FoxO3a in TECs treated with 3-DZNeP and oxalate; only SP600125 (JNK inhibitor) significantly decreased FoxO3a expression.

SIGNIFICANCE

EZH2 inhibition protects against oxalate-induced TECs injury and reduces CaOx crystal deposition in the kidney may by modulating the JNK/FoxO3a pathway; EZH2 may be a promising therapeutic target in TECs injury.

Exploration of sea anemone-inspired high-performance biomaterials with enhanced antioxidant activity

Antioxidant biomaterials have attracted much attention in various biomedical fields because of their effective inhibition and elimination of reactive oxygen species (ROS) in pathological tissues. However, the difficulty in ensuring biocompatibility, biodegradability and bioavailability of antioxidant materials has limited their further development. Novel bioavailable antioxidant materials that are derived from natural resources are urgently needed. Here, an integrated multi-omics method was applied to fabricate antioxidant biomaterials. A key cysteine-rich thrombospondin-1 type I repeat-like (TSRL) protein was efficiently discovered from among 1262 adhesive components and then used to create a recombinant protein with a yield of 500 mg L^-1. The biocompatible TSRL protein was able to self-assemble into either a water-resistant coating through Ca²⁺-mediated coordination or redox-responsive hydrogels with tunable physical properties. The TSRL-based hydrogels showed stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging rates than glutathione (GSH) and ascorbic acid (Aa) and protected cells against external oxidative stress significantly more effectively. When topically applied to mice skin, TSRL alleviated epidermal hyperplasia and suppressed the degradation of collagen and elastic fibers caused by ultraviolet radiation B (UVB) irradiation, confirming that it enhanced antioxidant activity in vivo. This is the first study to successfully characterize natural antioxidant biomaterials created from marine invertebrate adhesives, and the findings indicate the excellent prospects of these biomaterials for great applications in tissue regeneration and cosmeceuticals.

Nutrigenomic Studies on the Ameliorative Effect of Enzyme-Digested Phycocyanin in Alzheimer's Disease Model Mice

Alzheimer’s disease (AD) is the most common form of dementia, and the cognitive impairments associated with this degenerative disease seriously affect daily life. Nutraceuticals for the prevention or delay of AD are urgently needed. It has been increasingly observed that phycocyanin (PC) exerts neuroprotective effects. AD model mice intracerebroventricularly injected with amyloid beta-peptide 25–35 (Aβ_25–35) at 10 nmol/head displayed significant cognitive impairment in the spontaneous alternation test. Cognitive impairment was significantly ameliorated in mice treated with 750 mg/kg of enzyme-digested (ED) PC by daily oral administration for 22 consecutive days. Application of DNA microarray data on hippocampal gene expression to nutrigenomics studies revealed that oral EDPC counteracted the aberrant expression of 35 genes, including Prnp, Cct4, Vegfd (Figf), Map9 (Mtap9), Pik3cg, Zfand5, Endog, and Hbq1a. These results suggest that oral administration of EDPC ameliorated cognitive impairment in AD model mice by maintaining and/or restoring normal gene expression patterns in the hippocampus.

Phycocyanin content and nutritional profile of Arthrospira platensis from Mexico: efficient extraction process and stability evaluation of phycocyanin

Phycocyanin is a blue natural food colorant with multiple health benefits. Here we propose an efficient phycocyanin extraction method from Arthrospira platensis from Mexico. Three extraction methods were applied to optimize the extraction process, using water and buffer as solvents, with three pH values at two agitation times. The highest phycocyanin, 54.65 mg/g, was extracted from dry biomass with water as a solvent using an ultrasonication bar. The optimum condition of extraction was determined to be 1:50 biomass/solvent ratio for dry biomass, with the freeze/thaw method for 20 min repeated twice, and then agitated at 120 rpm for 24 h. The phycocyanin content was 48.88 mg/g biomass, with a purity of 0.47. For scalable phycocyanin productivity, the sonication method is recommended as there is no statistical difference. The phycocyanin stability was best at - 20 °C storage temperature at pH 7 for 35 days. Partial purification with ammonium sulfate was found to be suitable as a fractional precipitation method, first at 0-20% and then 20-65%, to get purity nearly 1. Total protein was found to be 55.52%, and total amino acids after phycocyanin extraction was 33%. The maximum phycocyanin yield using water as a solvent was the most interesting result regardless of the method used for extraction.

Potential Therapeutic Applications of C-Phycocyanin

BACKGROUND

Cancer and other disorders such as inflammation, autoimmune diseases and diabetes are the major health problems observed all over the world. Therefore, identifying a therapeutic target molecule for the treatment of these diseases is urgently needed to benefit public health. C-Phycocyanin (C-PC) is an important light yielding pigment intermittently systematized in the cyanobacterial species along with other algal species. It has numerous applications in the field of biotechnology and drug industry and also possesses antioxidant, anticancer, antiinflammatory, enhanced immune function, including liver and kidney protection properties. The molecular mechanism of action of C-PC for its anticancer activity could be the blockage of cell cycle progression, inducing apoptosis and autophagy in cancer cells.

OBJECTIVES

The current review summarizes an update on therapeutic applications of C-PC, its mechanism of action and mainly focuses on the recent development in the field of C-PC as a drug that exhibits beneficial effects against various human diseases including cancer and inflammation.

CONCLUSION

The data from various studies suggest the therapeutic applications of C-PC such as anti-cancer activity, anti-inflammation, anti-angiogenic activity and healing capacity of certain autoimmune disorders. Mechanism of action of C-PC for its anticancer activity is the blockage of cell cycle progression, inducing apoptosis and autophagy in cancer cells. The future perspective of C-PC is to identify and define the molecular mechanism of its anti-cancer, anti-inflammatory and antioxidant activities, which would shed light on our knowledge on therapeutic applications of C-PC and may contribute significant benefits to global public health.

C-phycocyanin from Limnothrix Species KNUA002 Alleviates Cisplatin-Induced Ototoxicity by Blocking the Mitochondrial Apoptotic Pathway in Auditory Cells

Ototoxicity, or adverse pharmacological effects on the inner ear or auditory nerve, is a common side effect of cisplatin, a platinum-based drug widely used in anticancer chemotherapy. Although the incidence of ototoxicity is high among patients that receive cisplatin therapy, there is currently no effective treatment for it. The generation of excessive reactive oxygen species (ROS) is considered to be the major cause of cisplatin-induced ototoxicity. C-phycocyanin (C-PC), a blue phycobiliprotein found in cyanobacteria and red algae, has antioxidant and anticancer activities in different experimental models in vitro and in vivo. Thus, we tested the ability of C-PC from Limnothrix sp. KNUA002 to protect auditory cells from cisplatin-induced ototoxicity in vitro. Pretreatment with C-PC from Limnothrix sp. KNUA002 inhibited apoptosis and protected mitochondrial function by preventing ROS accumulation in cisplatin-treated House Ear Institute-Organ of Corti 1 (HEI-OC1) cells, a mouse auditory cell line. Cisplatin increased the expression of Bax and reduced the expression of Bcl-2, which activate and inhibit, respectively, the mitochondrial apoptotic pathway in response to oxidative stress. Pretreatment with C-PC prior to cisplatin treatment caused the Bax and Bcl-2 levels to stay close to the levels in untreated control cells. Our results suggest that C-PC from Limnothrix sp. KNUA002 protects cells against cisplatin-induced cytotoxicity by inhibiting the mitochondrial apoptotic pathway.

Inhibiting inflammation and modulating oxidative stress in oxalate-induced nephrolithiasis with the Nrf2 activator dimethyl fumarate

Hyperoxaluria induces oxidative stress, and inflammation causes renal epithelial cell injury in nephrolithiasis, suggesting that reduced oxalate toxicity may be beneficial. This study aimed to investigate whether nuclear factor (erythroid-derived 2)-like 2 (Nrf2, also called Nfe2l2) induced by dimethyl fumarate (DMF) could protect renal epithelial cells against oxalate-mediated injury both in vivo and in vitro. Glyoxylic acid monohydrate was intraperitoneally injected into Sprague-Dawley rats with or without intragastric administration of DMF. We showed that calcium oxalate crystallisation, accompanied by overexpression of oxidant species and inflammatory cytokines and apoptosis in the rat kidney, was partially reversed by treatment with DMF. Furthermore, oxalate induced a reduction in cell viability, cell damage, oxidant species overexpression, mitochondrial dysfunction, and apoptosis in normal rat kidney epithelial-like (NRK-52E) cells, which were reversed by DMF. Pretreatment of NRK-52E cells with DMF significantly increased Nrf2 levels in the nucleus, with subsequent inhibition of the expression of the nicotinamide adenine dinucleotide phosphate subunits Nox4 and P22, canonical inflammation, and osteogenesis-associated differentiation of target genes in the cytoplasm. This effect was partially inhibited by transfection with Nrf2 siRNA and strengthened by transfection with Kelch-like ECH-associated protein 1 siRNA. These results suggest that DMF exerts beneficial effects in nephrolithiasis by inhibiting inflammation and modulating oxidative stress via regulation of Nrf2.

Opportunities for future therapeutic interventions for hyperoxaluria: targeting oxidative stress

INTRODUCTION

Oxalate is a toxic byproduct of metabolism and is normally produced in quantities easily removed from the body. However, under specific circumstances oxalate production is increased resulting in deposition of calcium oxalate (CaOx) crystals in the kidneys as well as other organs causing inflammation and injury. Excessive buildup of crystal deposits in the kidneys causes eventual loss of renal function requiring renal transplantation. Areas covered: Cellular exposure to CaOx crystals induces the production of reactive oxygen species (ROS) with the involvement of renin-angiotensin aldosterone system (RAAS), mitochondria, and NADPH oxidase. Inflammasomes are activated and pro-inflammatory cytokines, such as IL-1β and IL-18 are produced. We reviewed results of experimental and clinical studies of crystal renal epithelial cell interactions with emphasis on cellular injury and ROS production. Expert opinion: Treatment should depend upon the level of hyperoxaluria and whether it is associated with CaOx crystal deposition. Persistent low grade or intermittent hyperoxaluria can be treated with antioxidants, free radical scavengers. Hyperoxaluria associated with CaOx crystal deposition will require administration of angiotensin II receptor blockers, and NADPH oxidase or NLRP3 inflammasome inhibitors. DASH-style diet will be beneficial in both cases.

Repair activity and crystal adhesion inhibition of polysaccharides with different molecular weights from red algae Porphyra yezoensis against oxalate-induced oxidative damage in renal epithelial cells

Porphyra yezoensis polysaccharide repaired oxalate-injured renal epithelial cells and decreased COM crystal adhesion on the cell surface.

Neurotoxic effect of oxaliplatin: Comparison with its oxalate-free analogue cis-[PtII(1R,2R-DACH)(3-acetoxy-1,1-cyclobutanedicarboxylato)] (LLC-1402) in mice

Studies suggest that oxalate is involved in the development oxaliplatin-induced peripheral sensory neuropathy (OPSN). This study aimed to compare the neurotoxic effects of oxaliplatin with its oxalate-free cytotoxic analogue cis-[Pt^II(1R,2R-DACH)(3-acetoxy-1,1-cyclobutanedicarboxylato)] (LLC-1402) in mice. Oxaliplatin and LLC-1402 were intravenously injected in male Swiss mice with a total of nine injections. Oxalate was intraperitoneally injected in other animals. The development of OPSN was evaluated using mechanical and thermal sensitivity tests. Dorsal root ganglia of the mice were removed to evaluate c-Fos, ATF3 and iNOS expression and a sample of blood was collected for leukocyte count and hepatic and renal biochemical function tests. Oxaliplatin and LLC-1402 decreased the mechanical and thermal nociceptive threshold, whilst oxalate lead to a partial and later increase in the mechanical sensitivity (P<0.05). c-Fos, ATF3 and iNOS expressions were increased in neuronal cells during and after the end of the injections in animals treated with oxaliplatin and LLC-1402 (P<0.05), even though oxaliplatin lead to an earlier increase. Only c-Fos expression was elevated during the period of injections in the oxalate group (P<0.05), but this expression reduced after the end of the treatment. c-Fos expression was also shown in glial satellite cells only in the oxaliplatin-treated animals. Oxaliplatin and LLC-1402 reduced leukocyte count (P<0.05), but did not change renal and liver functions. In conclusion, oxalate may contribute to an earlier development of peripheral sensory neuropathy. However, the antitumor cytotoxic mechanism of oxaliplatin seems to be the main responsible by its neurotoxic effect.

C-Phycocyanin protects against mitochondrial dysfunction and oxidative stress in parthenogenetic porcine embryos

C-Phycocyanin (CP) is a biliprotein enriched in blue-green algae that is known to possess antioxidant, anti-apoptosis, anti-inflammatory, and radical-scavenging properties in somatic cells. However, the protective effect of CP on porcine embryo developmental competence in vitro remains unclear. In the present study, we investigated the effect of CP on the development of early porcine embryos as well as its underlying mechanisms. Different concentrations of CP (2, 5, 8, 10 μg/mL) were added to porcine zygote medium 5 during in vitro culture. The results showed that 5 μg/mL CP significantly increased blastocyst formation and hatching rate. Blastocyst formation and quality were significantly increased in the 50 μM H₂O₂ treatment group following 5 μg/mL CP addition. CP prevented the H₂O₂-induced compromise of mitochondrial membrane potential, release of cytochrome c from the mitochondria, and reactive oxygen species generation. Furthermore, apoptosis, DNA damage level, and autophagy in the blastocysts were attenuated by supplementation of CP in the H₂O₂-induced oxidative injury group compared to in controls. These results suggest that CP has beneficial effects on the development of porcine parthenotes by attenuating mitochondrial dysfunction and oxidative stress.

Molecular analysis of oxalate-induced endoplasmic reticulum stress mediated apoptosis in the pathogenesis of kidney stone disease

Oxalate, a non-essential end product of metabolism, causes hyperoxaluria and eventually calcium oxalate (CaOx) stone disease. Kidney cells exposed to oxalate stress results in generation of reactive oxygen species (ROS) and progression of stone formation. Perturbations in endoplasmic reticulum (ER) result in accumulation of misfolded proteins and Ca²⁺ ions homeostasis imbalance and serve as a common pathway for various diseases, including kidney disorders. ER stress induces up-regulation of pro-survival protein glucose-regulated protein 78 (GRP78) and pro-apoptotic signaling protein C/EBP homologous protein (CHOP). Since the association of oxalate toxicity and ER stress on renal cell damage is uncertain, the present study is an attempt to elucidate the interaction of GRP78 with oxalate by computational analysis and study the role of ER stress in oxalate-mediated apoptosis in vitro and in vivo. Molecular docking results showed that GRP78-oxalate/CaOx interaction takes place. Oxalate stress significantly up-regulated expression of ER stress markers GRP78 and CHOP both in vitro and in vivo. Exposure of oxalate increased ROS generation and altered antioxidant enzyme activities. N-Acetyl cysteine treatment significantly ameliorated oxalate-mediated oxidative stress and moderately attenuated ER stress marker expression. The result indicates oxalate toxicity initiated oxidative stress-induced ER stress and also activating ER stress mediated apoptosis directly. In addition, the up-regulation of transforming growth factor β-₁ revealed oxalate may induce kidney fibrosis through ER stress-mediated mechanisms. The present study provide insights into the pathogenic role of oxidative and ER stress by oxalate exposure in the formation of calcium oxalate stone.

The Inhibitory Effect of C-phycocyanin Containing Protein Extract (C-PC Extract) on Human Matrix Metalloproteinases (MMP-2 and MMP-9) in Hepatocellular Cancer Cell Line (HepG2)

Spirulina platensis :have been studied for several biological activities. In the current study C-phycocyanin containing protein extract (C-PC extract) of Spirulina platensis have been studied for its effect on human matrix metalloproteinases (MMP-1, MMP-2 and MMP-9) and tissue inhibitors of MMPs (TIMP-1 and TIMP-2). In the present study, breast cancer cell line (MDA-MB 231) and hepatocellular cancer cell line (HepG2) were examined for inhibition of MMPs at different levels of expression after C-PC extract treatment. Herein, we have demonstrated that C-PC extract significantly reduced activity of MMP-2 by 55.13% and MMP-9 by 57.9% in HepG2 cells at 15 μg concentration. Additionally, the treatment has reduced mRNA expression of MMP-2 and MMP-9 at 20 μg concentration by 1.65-folds and 1.66-folds respectively. The C-PC extract treatment have also downregulated a mRNA expression of TIMP-2 by 1.12 folds at 20 μg concentration in HepG2 cells. Together, these results indicate that C-PC, extract successfully inhibited MMP-2 and -9 at different levels of expression and TIMP-2 at a mRNA expression level; however, extract did not have any effect on MMP-1 expressed in MDA-MB231 and TIMP-1 expressed in HepG2 cells as well as the exact mechanism of inhibition of MMP-2, MMP-9 and TIMP-2 remained unclear.

The chemical disruption of human metabolism

BACKGROUND

Recent evidence highlights the reality of unprecedented human exposure to toxic chemical agents found throughout our environment - in our food and water supply, in the air we breathe, in the products we apply to our skin, in the medical and dental materials placed into our bodies, and even within the confines of the womb. With biomonitoring confirming the widespread bioaccumulation of myriad toxicants among population groups, expanding research continues to explore the pathobiological impact of these agents on human metabolism.

METHODS

This review was prepared by assessing available medical and scientific literature from Medline as well as by reviewing several books, toxicology journals, government publications, and conference proceedings. The format of a traditional integrated review was chosen.

RESULTS

Toxicant exposure and accrual has been linked to numerous biochemical and pathophysiological mechanisms of harm. Some toxicants effect metabolic disruption via multiple mechanisms.

CONCLUSIONS

As a primary causative determinant of chronic disease, toxicant exposures induce metabolic disruption in myriad ways, which consequently result in varied clinical manifestations, which are then categorized by health providers into innumerable diagnoses. Chemical disruption of human metabolism has become an etiological determinant of much illness throughout the lifecycle, from neurodevelopmental abnormalities in-utero to dementia in the elderly.

Expression of heterologous oxalate decarboxylase in HEK293 cells confers protection against oxalate induced oxidative stress as a therapeutic approach for calcium oxalate stone disease

Oxalates stimulate alterations in renal epithelial cells and thereby induce calcium oxalate (CaOx) stone formation. Bacillus subtilis YvrK gene encodes for oxalate decarboxylase (OxdC) which degrades oxalate to formate and CO₂. The present work is aimed to clone the oxdC gene in a mammalian expression vector pcDNA and transfect into Human Embryonic Kidney 293 (HEK293) cells and evaluate the oxdC expression, cell survival rate and oxalate degrading efficiency. The results indicate cell survival rate of HEK293/pcDNAOXDC cells pre-incubated with oxalate was enhanced by 28%. HEK293/pcDNAOXDC cells expressing OxdC treated with oxalate, significantly restored antioxidant activity, mitochondrial membrane potential and intracellular reactive oxygen species (ROS) generation compared with HEK293/pcDNA. Apoptotic marker caspase 3 downregulation illustrates HEK293/pcDNAOXDC cells were able to survive under oxalate-mediated oxidative stress. The findings suggest HEK293 cells expressing oxdC capable of degrading oxalate protect cells from oxidative damage and thus serve as a therapeutic option for prevention of CaOx stone disease.

Protective effects of aucubin on osteoarthritic chondrocyte model induced by hydrogen peroxide and mechanical stimulus

Background

During the onset of osteoarthritis (OA), certain biochemical events have been shown to accelerate cartilage degradation, including the dysregulation of cartilage ECM anabolism, abnormal generation of reactive oxygen species (ROS) and overproduction of proteolytic enzymes and inflammatory cytokines. The potency of aucubin in protecting cellular components against oxidative stress, inflammation and apoptosis effects are well documented, which makes it a potential candidate for OA treatment. In this study, we aimed to evaluate the protective benefits of aucubin against OA using H₂O₂ and compression induced OA-like chondrocyte models.

Methods

The effects of aucubin were studied in porcine chondrocytes after 1 mM H₂O₂ stimulation for 30 min or sustained compression for 24 h. Effects of aucubin on cell proliferation and cytotoxicity of chondrocytes were measured with WST-1 and LDH assays. ROS production was evaluated by the Total ROS/Superoxide Detection Kit. Caspase-3 activity was evaluated by the CaspACE assay system. The levels of apoptosis were evaluated by the Annexin V-FITC apoptosis detection kit. OA-related gene expression was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Total DNA quantification was evaluated by the DNeasy Blood and Tissue kit. Sulfated-glycosaminoglycans (sGAGs) production and content were evaluated by DMMB assay and Alcian blue staining.

Results

The results showed that the ROS scavenge effects of aucubin appeared after 1 h of pretreatment. Aucubin could reduce the caspase-3 activity induced by H₂O₂, and reduced the apoptosis cell population in flowcytometry. In RT-qPCR results, aucubin could maintain ACAN and COL2A1 gene expressions, and prevent IL6 and MMP13 gene up-regulation induced by H₂O₂ and compression stimulations. In the DMMB assay and Alcian blue staining, aucubin could maintain the sGAG content and protect chondrocytes against compressive stress, but not oxidative stress from H₂O₂.

Conclusions

These results indicated that aucubin has protective effects in an osteoarthritic chondrocyte model induced by H₂O₂ and mechanical stimulus.

MitoTEMPO Prevents Oxalate Induced Injury in NRK-52E Cells via Inhibiting Mitochondrial Dysfunction and Modulating Oxidative Stress

As one of the major risks for urolithiasis, hyperoxaluria can be caused by genetic defect or dietary intake. And high oxalate induced renal epithelial cells injury is related to oxidative stress and mitochondrial dysfunction. Here, we investigated whether MitoTEMPO, a mitochondria-targeted antioxidant, could protect against oxalate mediated injury in NRK-52E cells via inhibiting mitochondrial dysfunction and modulating oxidative stress. MitoSOX Red was used to determine mitochondrial ROS (mtROS) production. Mitochondrial membrane potential (Δψm) and quantification of ATP synthesis were measured to evaluate mitochondrial function. The protein expression of Nox4, Nox2, and p22 was also detected to explore the effect of oxalate and MitoTEMPO on NADPH oxidase. Our results revealed that pretreatment with MitoTEMPO significantly inhibited oxalate induced lactate dehydrogenase (LDH) and malondialdehyde (MDA) release and decreased oxalate induced mtROS generation. Further, MitoTEMPO pretreatment restored disruption of Δψm and decreased ATP synthesis mediated by oxalate. In addition, MitoTEMPO altered the protein expression of Nox4 and p22 and decreased the protein expression of IL-6 and osteopontin (OPN) induced by oxalate. We concluded that MitoTEMPO may be a new candidate to protect against oxalate induced kidney injury as well as urolithiasis.

Genome-Wide Gene Expression Profiling of Randall's Plaques in Calcium Oxalate Stone Formers

Randall plaques (RPs) can contribute to the formation of idiopathic calcium oxalate (CaOx) kidney stones; however, genes related to RP formation have not been identified. We previously reported the potential therapeutic role of osteopontin (OPN) and macrophages in CaOx kidney stone formation, discovered using genome-recombined mice and genome-wide analyses. Here, to characterize the genetic pathogenesis of RPs, we used microarrays and immunohistology to compare gene expression among renal papillary RP and non-RP tissues of 23 CaOx stone formers (SFs) (age- and sex-matched) and normal papillary tissue of seven controls. Transmission electron microscopy showed OPN and collagen expression inside and around RPs, respectively. Cluster analysis revealed that the papillary gene expression of CaOx SFs differed significantly from that of controls. Disease and function analysis of gene expression revealed activation of cellular hyperpolarization, reproductive development, and molecular transport in papillary tissue from RPs and non-RP regions of CaOx SFs. Compared with non-RP tissue, RP tissue showed upregulation (˃2-fold) of LCN2, IL11, PTGS1, GPX3, and MMD and downregulation (0.5-fold) of SLC12A1 and NALCN (P<0.01). In network and toxicity analyses, these genes associated with activated mitogen-activated protein kinase, the Akt/phosphatidylinositol 3-kinase pathway, and proinflammatory cytokines that cause renal injury and oxidative stress. Additionally, expression of proinflammatory cytokines, numbers of immune cells, and cellular apoptosis increased in RP tissue. This study establishes an association between genes related to renal dysfunction, proinflammation, oxidative stress, and ion transport and RP development in CaOx SFs.

Repair Effect of Seaweed Polysaccharides with Different Contents of Sulfate Group and Molecular Weights on Damaged HK-2 Cells

The structure⁻activity relationships and repair mechanism of six low-molecular-weight seaweed polysaccharides (SPSs) on oxalate-induced damaged human kidney proximal tubular epithelial cells (HK-2) were investigated. These SPSs included Laminaria japonica polysaccharide, degraded Porphyra yezoensis polysaccharide, degraded Gracilaria lemaneiformis polysaccharide, degraded Sargassum fusiforme polysaccharide, Eucheuma gelatinae polysaccharide, and degraded Undaria pinnatifida polysaccharide. These SPSs have a narrow difference of molecular weight (from 1968 to 4020 Da) after degradation by controlling H₂O₂ concentration. The sulfate group (⁻SO₃H) content of the six SPSs was 21.7%, 17.9%, 13.3%, 8.2%, 7.0%, and 5.5%, respectively, and the ⁻COOH contents varied between 1.0% to 1.7%. After degradation, no significant difference was observed in the contents of characteristic ⁻SO₃H and ⁻COOH groups of polysaccharides. The repair effect of polysaccharides was determined using cell-viability test by CCK-8 assay and cell-morphology test by hematoxylin-eosin staining. The results revealed that these SPSs within 0.1⁻100 μg/mL did not express cytotoxicity in HK-2 cells, and each polysaccharide had a repair effect on oxalate-induced damaged HK-2 cells. Simultaneously, the content of polysaccharide ⁻SO₃H was positively correlated with repair ability. Furthermore, the low-molecular-weight degraded polysaccharides showed better repair activity on damaged HK-2 cells than their undegraded counterpart. Our results can provide reference for inhibiting the formation of kidney stones and for developing original anti-stone polysaccharide drugs.

Medical Application of Spirulina platensis Derived C-Phycocyanin

Along with the development of marine biological pharmaceutical research, high-effective and low-toxic drugs and functional foods isolated from marine organisms have become a new field of pharmacy and bromatology. The pharmacological actions, such as anti-inflammation, antioxidation, antitumor, immunological enhancement, and hepatorenal protection of C-phycocyanin (C-PC) from Spirulina platensis, have been reported, and C-PC has important value of development and utilization either as drug or as functional food. There are many researches about the various pharmacological actions and mechanisms of C-PC, but related reports are only to some extent integrated deeply and accurately enough, which put some limitations to the further application of C-PC in medicine. Particularly, with the improvement of living standards and attention to health issues, C-PC being a functional food is preferred by more and more people. C-PC is easy to get, safe, and nontoxic; thus, it has a great potential of research and development as a drug or functional food. Here, the separation and purification, physicochemical properties, physiological and pharmacological activities, safety, and some applications are reviewed to provide relevant basis for the development of natural medicine and applied products.

Effects of alanine:glyoxylate aminotransferase variants and pyridoxine sensitivity on oxalate metabolism in a cell-based cytotoxicity assay

The hereditary kidney stone disease primary hyperoxaluria type 1 (PH1) is caused by a functional deficiency of the liver-specific, peroxisomal, pyridoxal-phosphate-dependent enzyme, alanine:glyoxylate aminotransferase (AGT). One third of PH1 patients, particularly those expressing the p.[(Pro11Leu; Gly170Arg; Ile340Met)] mutant allele, respond clinically to pharmacological doses of pyridoxine. To gain further insight into the metabolic effects of AGT dysfunction in PH1 and the effect of pyridoxine, we established an "indirect" glycolate cytotoxicity assay using CHO cells expressing glycolate oxidase (GO) and various normal and mutant forms of AGT. In cells expressing GO the great majority of glycolate was converted to oxalate and glyoxylate, with the latter causing the greater decrease in cell survival. Co-expression of normal AGTs and some, but not all, mutant AGT variants partially counteracted this cytotoxicity and led to decreased synthesis of oxalate and glyoxylate. Increasing the extracellular pyridoxine up to 0.3μM led to an increased metabolic effectiveness of normal AGTs and the AGT-Gly170Arg variant. The increased survival seen with AGT-Gly170Arg was paralleled by a 40% decrease in oxalate and glyoxylate levels. These data support the suggestion that the effectiveness of pharmacological doses of pyridoxine results from an improved metabolic effectiveness of AGT; that is the increased rate of transamination of glyoxylate to glycine. The indirect glycolate toxicity assay used in the present study has potential to be used in cell-based drug screening protocols to identify chemotherapeutics that might enhance or decrease the activity and metabolic effectiveness of AGT and GO, respectively, and be useful in the treatment of PH1.

Attrition of Hepatic Damage Inflicted by Angiotensin II with α-Tocopherol and β-Carotene in Experimental Apolipoprotein E Knock-out Mice

Angiotensin II is one of the key regulatory peptides implicated in the pathogenesis of liver disease. The mechanisms underlying the salubrious role of α-tocopherol and β-carotene on liver pathology have not been comprehensively assessed. Here, we investigated the mechanisms underlying the role of Angiotensin II on hepatic damage and if α-tocopherol and β-carotene supplementation attenuates hepatic damage. Hepatic damage was induced in Apoe(-/-)mice by infusion of Angiotensin II followed by oral administration with α-tocopherol and β-carotene-enriched diet for 60 days. Investigations showed fibrosis, kupffer cell hyperplasia, hepatocyte degeneration and hepatic cell apoptosis; sinusoidal dilatation along with haemorrhages; evidence of fluid accumulation; increased ROS level and increased AST and ALT activities. In addition, tPA and uPA were down-regulated due to 42-fold up-regulation of PAI-1. MMP-2, MMP-9, MMP-12, and M-CSF were down-regulated in Angiotensin II-treated animals. Notably, α-tocopherol and β-carotene treatment controlled ROS, fibrosis, hepatocyte degeneration, kupffer cell hyperplasia, hepatocyte apoptosis, sinusoidal dilatation and fluid accumulation in the liver sinusoids, and liver enzyme levels. In addition, PAI-1, tPA and uPA expressions were markedly controlled by β-carotene treatment. Thus, Angiotensin II markedly influenced hepatic damage possibly by restraining fibrinolytic system. We concluded that α-tocopherol and β-carotene treatment has salubrious role in repairing hepatic pathology.

C-phycocyanin prevents cisplatin-induced mitochondrial dysfunction and oxidative stress

The potential of C-phycocyanin (C-PC) to prevent cisplatin (CP)-induced kidney mitochondrial dysfunction was determined in CD-1 male mice. The CP-induced mitochondrial dysfunction was characterized by ultrastructural abnormalities and by decrease in the following parameters in isolated kidney mitochondria: adenosine diphosphate (ADP)-induced oxygen consumption (state 3), respiratory control ratio, ADP/oxygen (ADP/O) ratio, adenosine triphosphate synthesis, membrane potential, calcium retention, glutathione (GSH) content, and activity of respiratory complex I, aconitase, catalase, and GSH peroxidase. These mitochondria also showed increase in hydrogen peroxide production, malondialdehyde, and 3-nitrotyrosine protein adducts content. The above-described changes, as well as CP-induced nephrotoxicity, were attenuated in mice pretreated with a single injection of C-PC. Our data suggest that the attenuation of mitochondrial abnormalities is involved in the protective effect of C-PC against CP-induced nephrotoxicity. This is the first demonstration that C-PC pretreatment prevents CP-induced mitochondrial dysfunction in mice.

High-fat diet- and angiotensin II-induced aneurysm concurrently elicits splenic hypertrophy

BACKGROUND

Angiotensin II (Ang II) and high-fat diet are implicated in causing pathological changes in the vascular endothelium, brain, kidney and liver. The association of aneurysm leading to histopathological changes in the splenic compartment remains elusive. Further, the salubrious credentials of antioxidants, especially α-tocopherol and β-carotene in the resolution of splenic pathology have not been investigated.

METHODS

Four-month-old Apoe(-/-) mice were used in the induction of aneurysm by infusing Ang II, and subsequently were orally administered with α-tocopherol and β-carotene-enriched diet for 60 days.

RESULTS

We observed splenomegaly in Ang II-infused aneurysm and high-fat diet-supplemented mice as compared to normal mice. These observations were further confirmed through histopathological investigations, demonstrating splenic follicular hypertrophy. We observed a remarkable decrease in the size of spleen in α-tocopherol and β-carotene-treated Apoe(-/-) mice as compared with Ang II-treated animals. Furthermore, no marked changes in the histopathological splenic sections were seen in the β-carotene-treated group. However, hyperplasia and proliferation of immature lymphocytes in the follicles were observed in the α-tocopherol-treated animals. We found that CD4+ T-cell levels were increased in the high-fat diet group relative to the control group and were decreased in the β-carotene-treated animals.

CONCLUSIONS

Our study provides evidence that Ang II infusion and high-fat supplementation induces abdominal aortic aneurysm that has pathological implications to the spleen. The use of β-carotene but not α-tocopherol as an antioxidant markedly ameliorates the pathological changes in spleen.