Therapeutic Effects of Tea Polyphenols on Renal Damage Induced by High Uric Acid

Background: Hyperuricemia (HUA) is a condition characterized by excessive uric acid production and/or inadequate uric acid excretion due to abnormal purine metabolism in the human body. Uric acid deposits resulting from HUA can lead to complications such as renal damage. Currently, drugs used to treat HUA lack specificity and often come with specific toxic side effects. Objective: This study aimed to investigate the renal protective effects of an optimized tea polyphenol formula and allopurinol in a rat model of hyperuricemia following renal resection. The goal was to explore the mechanisms underlying these effects. Methods: Initially, a blend was formulated based on the distinctive functions of catechins, thearubigins, tea polysaccharides, and theanine. Orthogonal experiments were then employed to select a rational combination. A 5/6 renal resection rat model was successfully established, and the animals were fed a 2% oxonic acid diet to induce hyperuricemia. Urinary protein content was measured using the biuret method, and serum levels of uric acid, creatinine, and urea nitrogen were determined biochemically. Kidney pathology was examined through HE staining and renal tubulointerstitial pathological scoring. The expression of α-SMA, CD34, PCNA, and TGF-β in renal tissue was detected using immunohistochemistry. Apoptosis of renal tubular epithelial cells was assessed using the TUNEL method. Results: Hyperuricemia markedly worsens renal damage in rats following nephrectomy, while tea polyphenols demonstrate the ability to reduce levels of blood uric acid, urea nitrogen, creatinine, and urinary protein. Additionally, tea polyphenols enhance smooth muscle proliferation in renal glomerular arterioles, prevent the loss of interstitial capillaries, alleviate apoptosis of renal tubular epithelial cells, promote their proliferation, and reduce interstitial fibrosis. A significant improvement in the severity of renal damage is observed in rats subjected to nephrectomy combined with hyperuricemia, and this effect surpasses that of allopurinol. Conclusion: Tea polyphenols could effectively alleviate renal damage in rats with nephrectomy combined with hyperuricemia. They demonstrate high cost-effectiveness and minimal side effects, positioning them as a promising new therapeutic option for hyperuricemia- induced renal damage.