[Hyperuricemia in Down's syndrome (etiology, significance, and possibilities of its modification)].
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BACKGROUND: Uric acid (UA) is the terminal product of purine metabolism. Elevated serum uric acid (SUA) levels, resulting from excessive synthesis or impaired excretion, are link to chronic inflammatory stress and increased risks of colorectal, breast, and prostate cancers. Hyperuricemia triggers a cascade of proinflammatory and oxidative responses, establishing a microenvironment conducive to tumorigenesis. AIM OF REVIEW: This review synthesizes evidence on how hyperuricemia drive inflammation and cancer transformation from global foundational research and clinical practice, elucidate UA metabolism as potential therapeutic strategy for inflammation-associated malignancies. KEY SCIENTIFIC CONCEPTS OF REVIEW: Hyperuricemia-induced oxidative stress, DNA damage and genomic instability, while simultaneously activating proinflammatory signaling pathways. These interconnected pathways establish a persistent, proinflammatory microenvironment that fosters the transition from inflammation to cancer. Therapeutic strategies targeting UA metabolism (including pharmacologic interventions and dietary modifications) may mitigate chronic low-grade inflammation and reduce the cancer risk associated with hyperuricemia. Dysregulated UA metabolism emerges as a critical modulator linking chronic inflammation with oncogenesis.
OBJECTIVE: This study aimed to identify candidate therapeutic targets of oolong tea polyphenols (TP) against hyperuricemia (HUA) using network pharmacology and bioinformatics, and to validate the predicted molecular mechanism through in vivo experimentation. METHODS: Drug and disease targets were retrieved from public databases, and overlapping targets were identified by Venn diagram analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on the shared targets, and a protein-protein interaction (PPI) network was constructed to identify hub genes. For in vivo validation, an HUA mouse model was established by 15 days of oral potassium oxonate (PO) administration. Model mice then received TP by gavage at low (0.5 g⋅kg-1⋅d-1), medium (1 g⋅kg-1⋅d-1), or high (2 g⋅kg-1⋅d-1) doses for an additional 15 days. Serum biochemical markers, histopathological changes, and pathway-related protein expression were assessed by enzyme-linked immunosorbent assay (ELISA), hematoxylin and eosin (HE) staining, and western blot analysis, respectively. RESULTS: Network pharmacology analysis identified 59 overlapping targets between TP and HUA; GO and KEGG enrichment analyses revealed that these targets were primarily associated with hormone metabolism and the PI3K-AKT signaling pathway. In the animal experiment, TP dose-dependently reduced serum uric acid (SUA) levels in hyperuricemic mice. At the molecular level, low and medium doses of TP suppressed phosphorylation of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR), whereas the high dose paradoxically activated this pathway and concomitantly elevated interleukin-1β levels. These findings indicate that TP modulates uric acid metabolism through a non-monotonic, dose-dependent mechanism. CONCLUSION: By combining network pharmacology with animal experiments, this study identified the PI3K/AKT/mTOR signaling pathway as a likely mediator of the anti-hyperuricemic action of oolong tea polyphenols (TP). A medium dose of TP achieved the most balanced outcome, attenuating inflammation and preserving hepatic and renal architecture; the high dose, by contrast, paradoxically elevated interleukin-1β (IL-1β) and overactivated PI3K/AKT/mTOR signaling, underscoring the importance of dose calibration. These data suggest that a medium dose of TP may represent a feasible dietary strategy against hyperuricemia. Further work-including monomer identification, direct target validation, and clinical evaluation-is warranted to confirm and extend these preclinical findings.
Hypersensitivity reactions to allopurinol, a drug commonly used in the treatment of hyperuricemia, are being reported with increasing frequency. Of thirty-eight patients reviewed herein (including seven from our hospital and thirty-one from a review of the literature), ten deaths (26%) were related to complications of allopurinol hypersensitivity. Preexisting renal disease was present in 97% of patients, and, in the majority of these, the dosage of allopurinol was not reduced despite instructions contained in the package insert for this drug. At least 78% of patients were taking a thiazide diuretic prior to starting allopurinol therapy. Over 60% of patients had received allopurinol for asymptomatic hyperuricemia. Hallmarks of this hypersensitivity syndrome include a prolonged illness initially manifested by fever, a prominent cutaneous reaction, eosinophilia, hepatic abnormalities, and acute renal failure. Other involvement such as gastrointestinal bleeding is common. The mechanism of the hypersensitivity reaction is not clear, but it may represent an immune complex disease prolonged by the persistence of a currently undefined antigen. Treatment with systemic corticosteroids, often for several months, is usually necessary for the gradual resolution of this potentially fatal syndrome.
The three general types of renal pathology associated with hyperuricemia are reviewed. Factors influencing urate solubility are discussed, as well as the effect of uricosuric drugs on renal urate handling, with particular emphasis upon their efficacy in competing with urate for protein binding sites. In addition, a new experimental model of hyperuricemic nephropathy is described which could yield valuable data concerning the complex relationships between hyperuricemia, urate deposition and renal function.
Elevated uric acid serum levels are a frequent finding in psoriasis and, despite some reports to the contrary, it is generally believed that an association does exist between hyperuricemia and psoriasis. It seems a convincing idea that the rapid epidermal turnover in psoriasis might lead to an increased purine breakdown and may thus influence the uric acid serum levels. Consequently, a relationship might well be expected between hyperuricemia and the extent of psoriatic skin involvement. The present study was undertaken in order to prove or disprove such an assumption and to investigate the influence of oral photochemotherapy on the serum uric acid levels in psoriatic subjects.
Although genome-wide association studies have identified thousands of disease-associated loci, the mechanistic understanding and drug target discovery remain challenging, particularly for complex diseases. The multi-signal architecture of complex diseases complicates the interpretation of genetic contributions. To address this challenge, we develop an approach comprising locus-specific stratification (LSS) and gene regulatory prioritization score (GRPS), which uniquely considers multi-signals during fine-mapping and target gene identification. LSS significantly enhances the interpretability of genetic risk associated with complex diseases. For loci associated with serum urate levels, the method identifies candidate causal genes in 34.43% of loci, surpassing the performance of other methods by 5.47% to 25.14%. GRPS considers the regulatory network of LSS-variants comprehensively and successfully nominates under-explored drug targets for hyperuricemia with high confidence such as SLC17A4, which is further validated using epigenetic activation and phenotypic assays. This study introduces an approach to efficiently and comprehensively address the multi-signal challenges in complex diseases.
A patient with acute lymphoblastic leukemia with a large tumor burden is presented. Following successful chemotherapy, the patient experienced a cardiac arrest presumably due to hyperkalemia in association with hyperuricemia. The implication of these findings for patients with responsive hematological malignancies is discussed.
Work is continuing in the attempt to increase knowledge of the regulation of the rate of purine synthesis in man by means of an analysis of biochemical alterations leading to purine overproduction among patients with gout. The authors are now assessing the frequency of kinetic mutations in enzymes whose alterations already have been associated with increased purine synthesis. Efforts in this regard have been rewarded by the identification of a new form of alteration leading to partial deficiency of HGPRT and a kinetic variant of PRPP synthetase with increased affinity for ribose-5-phosphate. In order to identify new forms of enzyme abnormalities associated with excessive purine synthesis, the value of a proposed classification scheme requiring measurement of PRPP and ribose-5-phosphate concentration and generation is being assessed in cultured fibroblasts. It is hoped that the results of these measurements will lead to the identification of additional kinetic variants of presently known enzyme abnormalities and will help to identify new classes of mutants in the regulation of human purine metabolism. The excessive purine synthesis that underlies the hyperuricemia of a substantial number of patients with gouty arthritis reflects alterations in the normal mechanism regulating the rate of purine nucleotide synthesis. The study of such purine "overproducers" has provided insight into the nature of this regulatory mechanism and has underscored the diversity of specific genetic and biochemical aberrations affecting it. Despite these advances, however, less than 10% of all patients with gout and excessive purine production can presently be accounted for by known enzyme abnormalities (1). Recognition that current knowledge of the regulation of the rate of purine nucleotide synthesis in man is incomplete has provided the authors impetus leading to the studies described here, which are preceded by a brief review of background.
Hepatic metabolism of ethanol to acetaldehyde by the alcohol dehydrogenase (ADH) pathway is associated with the generation of reducing equivalents as NADH. Conversely, reducing equivalents are consumed when ethanol oxidation is catalyzed by the NADPH dependent microsomal ethanol oxidizing system (MEOS). Since the major fraction of ethanol metabolism proceeds via ADH and since the oxidation of acetaldehyde also generates NADH, an excess of reducing equivalents is produced. This explains a variety of effects following acute ethanol administration, including hyperlactacidemia, hyperuricemia, enhanced lipogenesis and depressed lipid oxidation. To the extent that ethanol is oxidized by the alternate MEOS pathway, it slows the metabolism of other microsomal substrates. Following chronic ethanol consumption, adaptive microsomal changes prevail, which include enhanced ethanol and drug metabolism, and increased lipoprotein production. Eventually, injury develops with alterations of the rough endoplasmic reticulum and structural and functional abnormalities of the mitochondria.