Oxidative stress, a well-known cause of stress-induced premature senescence (SIPS), is increased in patients with calcium oxalate (CaOx) kidney stones (KS). Oxalate and calcium oxalate monohydrate (COM) induce oxidative stress in renal tubular cells, but to our knowledge, their effect on SIPS has not yet been examined. Here, we examined whether oxalate, COM, or urine from patients with CaOx KS could induce SIPS and telomere shortening in human kidney (HK)-2 cells, a proximal tubular renal cell line. Urine from age- and sex-matched individuals without stones was used as a control. In sublethal amounts, H2O2, oxalate, COM, and urine from those with KS evoked oxidative stress in HK-2 cells, indicated by increased protein carbonyl content and decreased total antioxidant capacity, but urine from those without stones did not. The proportion of senescent HK-2 cells, as indicated by SA-βgal staining, increased after treatment with H2O2, oxalate, COM, and urine from those with KS. Expression of p16 was higher in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS than it was in cells treated with urine from those without stones and untreated controls. p16 was upregulated in the SA-βgal positive cells. Relative telomere length was shorter in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS than that in cells treated with urine from those without stones and untreated controls. Transcript expression of shelterin components (TRF1, TRF2 and POT1) was decreased in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS, in which case the expression was highest. Urine from those without KS did not significantly alter TRF1, TRF2, and POT1 mRNA expression in HK-2 cells relative to untreated controls. In conclusion, oxalate, COM, and urine from patients with CaOx KS induced SIPS and telomere shortening in renal tubular cells. SIPS induced by a lithogenic milieu may result from upregulation of p16 and downregulation of shelterin components, specifically POT1, and might contribute, at least in part, to the development of CaOx KS.

Low fluid intake, low urinary citrate excretion, and high oxidative stress are main causative factors of calcium oxalate (CaOx) nephrolithiasis. HydroZitLa contains citrate and natural antioxidants and is developed to correct these three factors simultaneously. Antioxidants theoretically can prolong the lifespan of organisms. In this study, we preclinically investigated the antilithogenic, lifespan-extending and anti-aging effects of HydroZitLa in HK-2 cells, male Wistar rats, and Caenorhabditis elegans. HydroZitLa significantly inhibited CaOx crystal aggregation in vitro and reduced oxidative stress in HK-2 cells challenged with lithogenic factors. For experimental nephrolithiasis, rats were divided into four groups: ethylene glycol (EG), EG + HydroZitLa, EG + Uralyt-U, and untreated control. CaOx deposits in kidneys of EG + HydroZitLa and EG + Uralyt-U rats were significantly lower than those of EG rats. Intrarenal expression of 4-hydroxynonenal in EG + HydroZitLa rats was significantly lower than that of EG rats. The urinary oxalate levels of EG + HydroZitLa and EG + Uralyt-U rats were significantly lower than those of EG rats. The urinary citrate levels of EG + HydroZitLa and EG + Uralyt-U rats were restored to the level in normal control rats. In C. elegans, HydroZitLa supplementation significantly extended the median lifespan of nematodes up to 34% without altering feeding ability. Lipofuscin accumulation in HydroZitLa-supplemented nematodes was significantly lower than that of non-supplemented control. Additionally, HydroZitLa inhibited telomere shortening, p16 upregulation, and premature senescence in HK-2 cells exposed to lithogenic stressors. Conclusions, HydroZitLa inhibited oxidative stress and CaOx formation both in vitro and in vivo. HydroZitLa extended the lifespan and delayed the onset of aging in C. elegans and human kidney cells. This preclinical evidence suggests that HydroZitLa is beneficial for inhibiting CaOx stone formation, promoting longevity, and slowing down aging.

Low fluid intake, low urinary citrate excretion, and high oxidative stress are main causative factors of calcium oxalate (CaOx) nephrolithiasis. HydroZitLa contains citrate and natural antioxidants and is developed to correct these three factors simultaneously. Antioxidants theoretically can prolong the lifespan of organisms. In this study, we preclinically investigated the antilithogenic, lifespan-extending and anti-aging effects of HydroZitLa in HK-2 cells, male Wistar rats, and Caenorhabditis elegans. HydroZitLa significantly inhibited CaOx crystal aggregation in vitro and reduced oxidative stress in HK-2 cells challenged with lithogenic factors. For experimental nephrolithiasis, rats were divided into four groups: ethylene glycol (EG), EG+HydroZitLa, EG+Uralyt-U, and untreated control. CaOx deposits in kidneys of EG+HydroZitLa and EG+Uralyt-U rats were significantly lower than those of EG rats. Intrarenal expression of 4-hydroxynonenal in EG+HydroZitLa rats was significantly lower than that of EG rats. The urinary oxalate levels of EG+HydroZitLa and EG+Uralyt-U rats were significantly lower than those of EG rats. The urinary citrate levels of EG+HydroZitLa and EG+Uralyt-U rats were restored to the level in normal control rats. In C. elegans, HydroZitLa supplementation significantly extended the median lifespan of nematodes up to 34% without altering feeding ability. Lipofuscin accumulation in HydroZitLa-supplemented nematodes was significantly lower than that of non-supplemented control. Additionally, HydroZitLa inhibited telomere shortening, p16 upregulation, and premature senescence in HK-2 cells exposed to lithogenic stressors. Conclusions, HydroZitLa inhibited oxidative stress and CaOx formation both in vitro and in vivo. HydroZitLa extended the lifespan and delayed the onset of aging in C. elegans and human kidney cells. This preclinical evidence suggests that HydroZitLa is beneficial for inhibiting CaOx stone formation, promoting longevity, and slowing down aging.

Kidney stone disease is a common urologic problem worldwide, especially in the tropics such as Thailand. It is known as a multifactorial condition, and aging increases the risk of stone development. The major type of stones is calcium oxalate (CaOx), and its formation is driven by increased urinary oxalate excretion and calcium oxalate monohydrate (COM) crystallization. Both oxalate and COM are known to induce reactive oxygen species (ROS) production and cause oxidative stress. Furthermore, patients with CaOx stone have increased extent of oxidative stress. In this study, we investigated the induction of cellular senescence and telomere shortening through oxidative stress by oxalate, COM and urine obtained from CaOx kidney stone (KS) patients (n=5) in HK-2 cells. Five urine samples from the age- and sex-matched non-stone (NS) subjects were used as urine control. HK-2 cells were treated with H2O2 (representative of ROS), oxalate, COM and urine samples (10% v/v) for 72 h. The result shown that the number of senescent (SA-βgal positive) cells were significantly higher in H2O2-, oxalate-, COM- and KS urine-treated conditions than that of the NS urine-treated and untreated conditions. Oxidative stress, indicated by increased protein carbinyl level and decreased total antioxidant capacity, was significantly increased in cells treated with H2O2, oxalate, COM and KS urine relative to the untreated control and NS urine. The expression of p16 protein was clearly increased in the H2O2-, oxalate-, COM- and KS urine-treated cells compared with the untreated control and NS urine-treated cells. In contrast, relative telomere length was significantly decreased in the H2O2-, oxalate-, COM- and KS urine-treated cells compared with the untreated control and NS urine-treated cells. Expression of TRF1, TRF2 and POT1 mRNAs was significantly lower in cells treated with H2O2, oxalate, COM and KS urine than that of the untreated control and NS urine. In conclusion, this is the first study showing that oxalate, COM and KS urine induce cellular senescence and telomere shortening in renal proximal tubular cells. This senescent induction is mediated through oxidative stress and associated with upregulation of p16 and downregulation of shelterin complex genes. Our findings suggest that oxidative stress-mediated senescence and telomere shortening in renal proximal tubular cells induced by lithogenic factors, particularly oxalate and COM, may contribute to the development of CaOx kidney stone disease.