Prooxidant and antioxidant properties of human serum ultrafiltrates toward LDL: important role of uric acid

Patterson, Rebecca A.; Horsley, Elizabeth; Leake, David S.

doi:10.1194/jlr.m200407-jlr200

Cited by 131 publications

(93 citation statements)

References 41 publications

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“…21 Despite this, several studies have demonstrated that uric acid can be prooxidative and may generate free radicals. [22][23][24][25] The ability to activate p38 MAPK, NF-kB, and AP-1, as well as to increase MCP-1 expression, is consistent with an oxidantdriven pathway. 26,27 In conclusion, we have found that uric acid can induce inflammatory pathways in rat VSMCs in vitro, with activation of p38 MAPK, NF-B, and AP-1 and increased expression of COX-2 and MCP-1.…”

Section: Discussionmentioning

confidence: 71%

Uric Acid Stimulates Monocyte Chemoattractant Protein-1 Production in Vascular Smooth Muscle Cells Via Mitogen-Activated Protein Kinase and Cyclooxygenase-2

et al. 2003

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Abstract-Previous studies have reported that uric acid stimulates vascular smooth muscle cell (VSMC) proliferation in vitro. We hypothesized that uric acid may also have direct proinflammatory effects on VSMCs. Crystal-and endotoxin-free uric acid was found to increase VSMC monocyte chemoattractant protein-1 (MCP-1) expression in a time-and dose-dependent manner, peaking at 24 hours. Increased mRNA and protein expression occurred as early as 3 hours after uric acid incubation and was partially dependent on posttranscriptional modification of MCP-1 mRNA. In addition, uric acid activated the transcription factors nuclear factor-B and activator protein-1, as well as the MAPK signaling molecules ERK p44/42 and p38, and increased cyclooxygenase-2 (COX-2) mRNA expression. Inhibition of p38 (with SB 203580), ERK 44/42 (with UO126 or PD 98059), or COX-2 (with NS398) each significantly suppressed uric acid-induced MCP-1 expression at 24 hours, implicating these pathways in the response to uric acid. The ability of both N-acetyl-cysteine and diphenyleneionium (antioxidants) to inhibit uric acid-induced MCP-1 production suggested involvement of intracellular redox pathways. Uric acid regulates critical proinflammatory pathways in VSMCs, suggesting it may have a role in the vascular changes associated with hypertension and vascular disease.

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Section: Discussionmentioning

confidence: 71%

Uric Acid Stimulates Monocyte Chemoattractant Protein-1 Production in Vascular Smooth Muscle Cells Via Mitogen-Activated Protein Kinase and Cyclooxygenase-2

et al. 2003

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“…The association of low-normal serum urate levels with Parkinson's disease and multiple sclerosis has led to proposals that higher PUA protects neurons from toxic effects of peroxynitrite (7,(41)(42)(43). However, urate concentration in brain is much lower than in plasma (7,44,45); urate is a poor scavenger of peroxynitrite (46)(47)(48); and reactions of urate with free radicals have pro-as well as antioxidant consequences (46,47,49,50). Moreover, significantly raising serum urate concentration for 2 years was of no benefit in patients with relapsing-remitting multiple sclerosis (51).…”

Section: Discussionmentioning

confidence: 99%

Treating gout with pegloticase, a PEGylated urate oxidase, provides insight into the importance of uric acid as an antioxidant in vivo

Hershfield

Roberts²,

Ganson³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

121

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A high plasma urate concentration (PUA), related to loss of urate oxidase in evolution, is postulated to protect humans from oxidative injury. This hypothesis has broad clinical relevance, but support rests largely on in vitro data and epidemiologic associations. Pegloticase therapy generates H 2 O 2 while depleting urate, offering an in vivo test of the antioxidant hypothesis. We show that erythrocytes can efficiently eliminate H 2 O 2 derived from urate oxidation to prevent cell injury in vitro; during therapy, disulfide-linked peroxiredoxin 2 dimer did not accumulate in red blood cells, indicating that their peroxidase capacity was not exceeded. To assess oxidative stress, we monitored F2-Isoprostanes (F2-IsoPs) and protein carbonyls (PC), products of arachidonic acid and protein oxidation, in plasma of 26 refractory gout patients receiving up to five infusions of pegloticase at 3-wk intervals. At baseline, PUA was markedly elevated in all patients, and plasma F2-IsoP concentration was elevated in most. Pegloticase infusion rapidly lowered mean PUA to ≤1 mg/dL in all patients, and PUA remained low in 16 of 21 patients who completed treatment. F2-IsoP levels did not correlate with PUA and did not increase during 15 wk of sustained urate depletion. There also was no significant change in the levels of plasma PC. Because refractory gout is associated with high oxidative stress in spite of high PUA, and profoundly depleting uric acid did not increase lipid or protein oxidation, we conclude that urate is not a major factor controlling oxidative stress in vivo.

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“…Clinical studies have revealed higher or unchanged protein carbonyls in patients with high urate, including refractory gout patients (30)(31)(32). Furthermore, urate has the capacity to act as a prooxidant under some circumstances (33)(34)(35).…”

Section: Discussionmentioning

confidence: 99%

Disrupted and transgenic urate oxidase alter urate and dopaminergic neurodegeneration

Chen

Burdett

Desjardins

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

112

121

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Urate is the end product of purine metabolism in humans, owing to the evolutionary disruption of the gene encoding urate oxidase (UOx). Elevated urate can cause gout and urolithiasis and is associated with cardiovascular and other diseases. However, urate also possesses antioxidant and neuroprotective properties. Recent convergence of epidemiological and clinical data has identified urate as a predictor of both reduced risk and favorable progression of Parkinson's disease (PD). In rodents, functional UOx catalyzes urate oxidation to allantoin. We found that UOx KO mice with a constitutive mutation of the gene have increased concentrations of brain urate. By contrast, UOx transgenic (Tg) mice overexpressing the enzyme have reduced brain urate concentrations. Effects of the complementary UOx manipulations were assessed in a mouse intrastriatal 6-hydroxydopamine (6-OHDA) model of hemiparkinsonism. UOx KO mice exhibit attenuated toxic effects of 6-OHDA on nigral dopaminergic cell counts, striatal dopamine content, and rotational behavior. Conversely, Tg overexpression of UOx exacerbates these morphological, neurochemical, and functional lesions of the dopaminergic nigrostriatal pathway. Together our data support a neuroprotective role of endogenous urate in dopaminergic neurons and strengthen the rationale for developing urate-elevating strategies as potential disease-modifying therapy for PD.U rate, the anionic component of uric acid, predominates at physiological pH. As an apparent consequence of mutations in the urate oxidase (UOx) gene during primate evolution, urate constitutes the enzymatic end product of purine metabolism in humans (1). There remains controversy over how the loss of UOx activity and the resultant high urate concentrations in hominoids may have been beneficial and whether it still is. On one hand, urate is considered a pathogenic factor in gout, urolithiasis, and nephropathy, and hyperuricemia is associated with other medical conditions, such as hypertension, cardiovascular disease, and metabolic syndrome (2). On the other hand, the loss of UOx activity through multiple independent mutations in hominoids presumably conferred evolutionary advantages. Urate possesses potent antioxidant properties. High urate levels may have provided an antioxidant defense against aging and cancer, thereby contributing to a prolonged hominoid life span (3). In addition, increased urate may mediate blood pressure homeostasis in low-salt environments. Furthermore, higher urate has been suggested to enhance human intelligence or motivational behaviors or promote neuronal integrity and function (4).Recently a series of population and clinical epidemiology studies have lent support to a potential neuroprotective effect of urate (5,6). These studies demonstrated a robust inverse link between urate levels and both the risk and clinical progression of Parkinson's disease (PD), one of the most common neurodegenerative diseases. Given the putative role of oxidative stress in the pathogenesis of PD (7), these studies have i...

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Prooxidant and antioxidant properties of human serum ultrafiltrates toward LDL: important role of uric acid

Cited by 131 publications

References 41 publications

Uric Acid Stimulates Monocyte Chemoattractant Protein-1 Production in Vascular Smooth Muscle Cells Via Mitogen-Activated Protein Kinase and Cyclooxygenase-2

Uric Acid Stimulates Monocyte Chemoattractant Protein-1 Production in Vascular Smooth Muscle Cells Via Mitogen-Activated Protein Kinase and Cyclooxygenase-2

Treating gout with pegloticase, a PEGylated urate oxidase, provides insight into the importance of uric acid as an antioxidant in vivo

Disrupted and transgenic urate oxidase alter urate and dopaminergic neurodegeneration

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