Sulfated Undaria pinnatifida polysaccharide inhibits the formation of kidney stones by inhibiting HK-2 cell damage and reducing the adhesion of nano‑calcium oxalate crystals

Carboxymethylated Desmodium styracifolium polysaccharide reduces the risk of calcium oxalate kidney stone formation by inhibiting crystal adhesion and promoting crystal endocytosis

The inhibition of cell surface crystal adhesion and an appropriate increase in crystal endocytosis contribute to the inhibition of kidney stone formation. In this study, we investigated the effects of different degrees of carboxymethylation on these processes. An injury model was established by treating human renal proximal tubular epithelial (HK-2) cells with 98.3 ± 8.1 nm calcium oxalate dihydrate (nanoCOD) crystals. The HK-2 cells were protected with carboxy (-COOH) Desmodium styracifolium polysaccharides at 1.17% (DSP0), 7.45% (CDSP1), 12.2% (CDSP2), and 17.7% (CDSP3). Changes in biochemical indexes and effects on nanoCOD adhesion and endocytosis were detected. The protection of HK-2 cells from nanoCOD-induced oxidative damage by carboxymethylated Desmodium styracifolium polysaccharides (CDSPs) is closely related to the protection of subcellular organelles, such as mitochondria. CDSPs can reduce crystal adhesion on the cell surface and maintain appropriate crystal endocytosis, thereby reducing the risk of kidney stone formation. CDSP2 with moderate -COOH content showed the strongest protective activity among the CDSPs.

Carboxymethylated Rhizoma alismatis polysaccharides reduces the risk of calcium oxalate stone formation by reducing cellular inflammation and oxidative stress

This study aims to elucidate the mechanism and potential of Rhizoma alismatis polysaccharides (RAPs) in preventing oxidative damage to human renal proximal tubule epithelial cells. The experimental approach involved incubating HK-2 cells with 100 nm calcium oxalate monohydrate for 24 h to establish a cellular injury model. Protection was provided by RAPs with varying carboxyl group contents: 3.57%, 7.79%, 10.84%, and 15.33%. The safeguarding effect of RAPs was evaluated by analyzing relevant cellular biochemical indicators. Findings demonstrate that RAPs exhibit notable antioxidative properties. They effectively diminish the release of reactive oxygen species, lactate dehydrogenase, and malondialdehyde, a lipid oxidation byproduct. Moreover, RAPs enhance superoxide dismutase activity and mitochondrial membrane potential while attenuating the permeability of the mitochondrial permeability transition pore. Additionally, RAPs significantly reduce levels of inflammatory factors, including NLRP3, TNF-α, IL-6, and NO. This reduction corresponds to the inhibition of overproduced pro-inflammatory mediator nitric oxide and the caspase 3 enzyme, leading to a reduction in cellular apoptosis. RAPs also display the ability to suppress the expression of the HK-2 cell surface adhesion molecule CD44. The observed results collectively underscore the substantial anti-inflammatory and anti-apoptotic potential of all four RAPs. Moreover, their capacity to modulate the expression of cell surface adhesion molecules highlights their potential in inhibiting the formation of kidney stones. Notably, RAP3, boasting the highest carboxyl group content, emerges as the most potent agent in this regard.

Carboxylated Pocoa polysaccharides inhibited oxidative damage and inflammation of HK-2 cells induced by calcium oxalate nanoparticles

The inhibitory effects of Chinese medicine Pocoa (PCPs) with different carboxyl group (-COOH) contents on oxidative damage and inflammatory response of renal epithelial cells and the influence of -COOH content in polysaccharides were investigated. HK-2 cell damage model was established by nanocalcium oxalate crystals (nanoCOM), and then PCPs with -COOH contents of 2.56% (PCP0), 7.48% (PCP1), 12.07% (PCP2), and 17.18% (PCP3) were used to protect the cells. PCPs could inhibit the damage of nanoCOM to HK-2 cells, increase cell viability, restore cytoskeleton and morphology, and improve lysosomal integrity. PCPs can reduce the oxidative stress response of nanoCOM to cells, inhibit the opening of mPTP and cell necrotic apoptosis, reduce the level of Ca2+ ions in cells, the production of ATP and MDA, and increase SOD expression. PCPs can also reduce the cellular inflammatory response caused by oxidative damage, and reduce the expression of nitric oxide (NO), inflammatory factors TNF-α, IL-6, IL-1β and MCP-1, as well as the content of inflammasome NLRP3. After protection, PCPs can inhibit the endocytosis of nanoCOM crystals by cells. With the increase in -COOH content in PCPs, its ability to inhibit nanoCOM cell damage, reduce oxidative stress, reduce inflammatory response, and inhibit crystal endocytosis increases, that is, PCP3 with the highest -COOH content, shows the best biological activity. Inhibiting cell damage and inflammation and reducing a large amount of endocytosis of crystals by cells are beneficial to inhibit the formation of kidney stones.

Sulfated Undaria pinnatifida Polysaccharide Promotes Endocytosis of Nano-Calcium Oxalate Dihydrate by Repairing Subcellular Organelles in HK-2 Cells

The clinical manifestation of primary hyperoxaluria includes hyperoxaluria and recurrent urinary calculi. In this study, an oxidative damage model was constructed based on oxalate damage to the human renal proximal tubular epithelial cells (HK-2), and a comparative study was carried out on four different sulfated levels of Undaria pinnatifida polysaccharides (UPP0, UPP1, UPP2, and UPP3 with sulfate group [-OSO₃^-] contents of 1.59%, 6.03%, 20.83%, and 36.39%, respectively) on the repair of oxidatively damaged HK-2 cells. The results showed that after repair by UPPs, cell viability was enhanced, healing ability was improved, the intracellular superoxide dismutase level and mitochondrial membrane potential were increased, malondialdehyde, reactive oxygen species, and intracellular Ca²⁺ levels were reduced, cellular autophagy was reduced; lysosomal integrity was improved, and cytoskeleton and cell morphology were restored. The ability of repaired cells to endocytose nano-calcium oxalate dihydrate crystals (nano-COD) was enhanced. The activity of UPPs was closely related to their -OSO₃^- content. A too high or too low -OSO₃^- content was not conducive to polysaccharide activity, and only UPP2 exhibited the best cell repair ability and strongest ability to promote the cell endocytosis of crystals. UPP2 may be used as a potential agent to inhibit CaOx crystal deposition caused by high oxalate concentration.