Modulation of Calcium Oxalate Crystal Growth and Protection from Oxidatively Damaged Renal Epithelial Cells of Corn Silk Polysaccharides with Different Molecular Weights

Corn Silk Polysaccharide Reduces the Risk of Kidney Stone Formation by Reducing Oxidative Stress and Inhibiting COM Crystal Adhesion and Aggregation

The aim of this study is to explore the inhibition of nanocalcium oxalate monohydrate (nano-COM) crystal adhesion and aggregation on the HK-2 cell surface after the protection of corn silk polysaccharides (CSPs) and the effect of carboxyl group (-COOH) content and polysaccharide concentration.

METHOD

HK-2 cells were damaged by 100 nm COM crystals to build an injury model. The cells were protected by CSPs with -COOH contents of 3.92% (CSP0) and 16.38% (CCSP3), respectively. The changes in the biochemical indexes of HK-2 cells and the difference in adhesion amount and aggregation degree of nano-COM on the cell surface before and after CSP protection were detected.

RESULTS

CSP0 and CCSP3 protection can obviously inhibit HK-2 cell damage caused by nano-COM crystals, restore cytoskeleton morphology, reduce intracellular ROS level, inhibit phosphoserine eversion, restore the polarity of the mitochondrial membrane potential, normalize the cell cycle process, and reduce the expression of adhesion molecules, OPN, Annexin A1, HSP90, HAS3, and CD44 on the cell surface. Finally, the adhesion and aggregation of nano-COM crystals on the cell surface were effectively inhibited. The carboxymethylated CSP3 exhibited a higher protective effect on cells than the original CSP0, and cell viability was further improved with the increase in polysaccharide concentration.

CONCLUSIONS

CSPs can protect HK-2 cells from calcium oxalate crystal damage and effectively reduce the adhesion and aggregation of nano-COM crystals on the cell surface, which is conducive to inhibiting the formation of calcium oxalate kidney stones.

Herreria stellata

Calcium oxalate (CaOx) is known to grow on organic matrices and is often associated with the formation of kidney stones. Therefore, it is crucial to understand the nucleation and growth mechanisms. This study investigates the role of electrospun polycaprolactone (PCL)-loaded zarzaparrilla (ZP) (Herreria stellata) in the electrocrystallization (EC) of CaOx. Electrospinning (ES) was used to prepare PCL meshes with random (R) and aligned (A) fiber orientations. CaOx particles were grown directly on conductive tin indium oxide (ITO) glass modified with electrospun ZP-loaded PCL meshes by EC. The CaOx crystals after EC were measured by chronopotentiometry (CP), optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), which showed that the ZP additive and PCL fiber orientations are key factors for CaOx nucleation.

Corn Silk Polysaccharides with Different Carboxyl Contents Reduce the Oxidative Damage of Renal Epithelial Cells by Inhibiting Endocytosis of Nano-calcium Oxalate Crystals

OBJECTIVE

Renal epithelial cell injury and cell-crystal interaction are closely related to kidney stone formation.

METHODS

This study aims to explore the inhibition of endocytosis of nano-sized calcium oxalate monohydrate (nano-COM) crystals and the cell protection of corn silk polysaccharides (CCSPs) with different carboxyl contents (3.92, 7.75, 12.90, and 16.38%). The nano-COM crystals protected or unprotected by CCSPs were co-cultured with human renal proximal tubular epithelial cells (HK-2), and then the changes in the endocytosis of nano-COM and cell biochemical indicators were detected.

RESULTS

CCSPs could inhibit the endocytosis of nano-COM by HK-2 cells and reduce the accumulation of nano-COM in the cells. Under the protection of CCSPs, cell morphology is restored, intracellular superoxide dismutase levels are increased, lipid peroxidation product malondialdehyde release is decreased, and mitochondrial membrane potential and lysosomal integrity are increased. The release of Ca²⁺ ions in the cell, the level of cell autophagy, and the rate of cell apoptosis and necrosis are also reduced. CCSPs with higher carboxyl content have better cell protection abilities.

CONCLUSION

CCSPs could inhibit the endocytosis of nano-COM crystals and reduce cell oxidative damage. CCSP3, with the highest carboxyl content, shows the best biological activity.

Network pharmacology and experimental validation to elucidate the pharmacological mechanisms of Bushen Huashi decoction against kidney stones

INTRODUCTION

Kidney stone disease (KS) is a complicated disease with an increasing global incidence. It was shown that Bushen Huashi decoction (BSHS) is a classic Chinese medicine formula that has therapeutic benefits for patients with KS. However, its pharmacological profile and mechanism of action are yet to be elucidated.

METHODS

The present study used a network pharmacology approach to characterize the mechanism by which BSHS affects KS. Compounds were retrieved from corresponding databases, and active compounds were selected based on their oral bioavailability (≥30) and drug-likeness index (≥0.18). BSHS potential proteins were obtained from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, whereas KS potential genes were obtained from GeneCards and OMIM, TTD, and DisGeNET. Gene ontology and pathway enrichment analysis were used to determine potential pathways associated with genes. The ingredients of BSHS extract were identified by the ultra-high-performance liquid chromatography coupled with quadrupole orbitrap mass spectrometry (UHPLC-Q/Orbitrap MS). The network pharmacology analyses predicted the potential underlying action mechanisms of BSHS on KS, which were further validated experimentally in the rat model of calcium oxalate kidney stones.

RESULTS

Our study found that BSHS reduced renal crystal deposition and improved renal function in ethylene glycol(EG)+ammonium chloride(AC)-induced rats, and also reversed oxidative stress levels and inhibited renal tubular epithelial cell apoptosis in rats. BSHS upregulated protein and mRNA expression of E2, ESR1, ESR2, BCL2, NRF2, and HO-1 in EG+AC-induced rat kidney while downregulating BAX protein and mRNA expression, consistent with the network pharmacology results.

DISCUSSION

This study provides evidence that BSHS plays a critical role in anti-KS via regulation of E2/ESR1/2, NRF2/HO-1, and BCL2/BAX signaling pathways, indicating that BSHS is a candidate herbal drug for further investigation in treating KS.

Isolation, identification, and characterization of corn-derived antioxidant peptides from corn fermented milk by Limosilactobacillus fermentum

Dairy-derived peptides and corn-derived peptides have been identified as essential ingredients for health promotion in the food industry. The hydrolysis based on lactic acid bacteria (LAB) protease system is one of the most popular methods to prepare bioactive peptides. The objectives of this paper are to develop antioxidant fermented milk and to obtain natural antioxidant peptides. In our study, LAB with antioxidant capacity were screened in vitro, and the corn fermented milk with antioxidant capacity was achieved by the traditional fermentation method. Fermented milk was purified by ultrafiltration and molecular sieve, and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our findings demonstrate that Limosilactobacillus fermentum L15 had a scavenging capacity of more than 80% of DPPH radicals, Trolox equivalent antioxidant capacity (TEAC) of 0.348 ± 0.005 mmol/L. Meanwhile, the peptide content of corn fermented milk prepared with L. fermentum L15 was 0.914 ± 0.009 mg/mL and TAEC of 0.781 ± 0.020 mmol/L. Particularly important, IGGIGTVPVGR and LTTVTPGSR isolated and extracted from fermented milk were found to have antioxidant capacity for the first time. The synthetic peptides IGGIGTVPVGR and LTTVTPGSR demonstrated a scavenging capacity of 70.07 ± 2.71% and 70.07 ± 2.77% for DPPH radicals and an antioxidant capacity of 0.62 ± 0.01 mmol/L and 0.64 ± 0.02 mmol/L Trolox equivalent, respectively. This research provides ideas and basis for the development and utilization of functional dairy products.

Carboxymethylation of Desmodium styracifolium Polysaccharide and Its Repair Effect on Damaged HK-2 Cells

Objective

Desmodium styracifolium is the best traditional medicine for treating kidney calculi in China. This study is aimed at increasing the carboxyl (-COOH) content of D. styracifolium polysaccharide (DSP0) and further increasing its antistone activity.

Methods

DSP0 was carboxymethylated with chloroacetic acid at varying degrees. Then, oxalate-damaged HK-2 cells were repaired with modified polysaccharide, and the changes in biochemical indices before and after repair were detected.

Results

Three modified polysaccharides with 7.45% (CDSP1), 12.2% (CDSP2), and 17.7% (CDSP3) -COOH are obtained. Compared with DSP0 (-COOH content = 1.17%), CDSPs have stronger antioxidant activity in vitro and can improve the vitality of damaged HK-2 cells. CDSPs repair the cell morphology and cytoskeleton, increase the cell healing ability, reduce reactive oxygen species and nitric oxide levels, increase mitochondrial membrane potential, limit autophagy level to a low level, reduce the eversion of phosphatidylserine in the cell membrane, weaken the inhibition of oxalate on DNA synthesis, restore cell cycle to normal state, promote cell proliferation, and reduce apoptosis/necrosis.

Conclusion

The carboxymethylation modification of DSP0 can improve its antioxidant activity and enhance its ability to repair damaged HK-2 cells. Among them, CDSP2 with medium -COOH content has the highest activity of repairing cells, whereas CDSP3 with the highest -COOH content has the highest antioxidant activity. This difference may be related to the active environment of polysaccharide and conformation of the polysaccharide and cell signal pathway. This result suggests that Desmodium styracifolium polysaccharide with increased -COOH content may have improved potential treatment and prevention of kidney calculi.

Relationship between hepatitis C and kidney stone in US females: Results from the National Health and Nutrition Examination Survey in 2007–2018

Background

The main objective of this study is to explore the effects of hepatitis C (HCV) on the prevalence rate of kidney stones in US women.

Method

Dates for HCV infection and kidney stones were collected from National Health and Nutrition Examination Survey (NHANES) database, a cross-sectional study. The analysis samples included adults aged ≥20 years and women from six consecutive cycles of the NHANES 2007–2018. The association between HCV infection and kidney stones was performed by using logistic regression models. Subgroup analyses were conducted to find sensitive crowds.

Results

A total of 13,262 participants were enrolled, including 201 infected with HCV. After adjustment for potential confounders, we revealed a positive relationship between HCV and kidney stones (OR = 1.70, 95%CI:1.13–2.56). The crowds' statistically significant difference was characterized by other races (OR = 8.17, 95%CI:1.62–41.22) and BMI within 25–29.9 kg/m2 (OR = 2.45, 95%CI:1.24–4.83).

Conclusions

HCV infection may affect the prevalence of urolithiasis in US women, even the causal relationship remains unclear, the relation deserves special attention. We considered such a study an ideal way to begin exploring the effects of HCV on kidney stones.

Chemical Composition and Anti-Urolithiatic Activity of Extracts from Argania spinosa (L.) Skeels Press-Cake and Acacia senegal (L.) Willd

Ethnobotanical studies have reported the traditional medicinal uses of Acacia senegal (L.) Willd. and Argania spinosa (L.) Skeels against kidney stone formation and other chronic kidney diseases. The present work is undertaken to study the litholytic activity and the inhibiting activity of calcium oxalate crystallization by bioactive compounds identified in Argania spinosa (L.) Skeels press-cake (residue of Argan oil) and in Acacia senegal (L.) Willd. The litholytic activity was studied in vitro on cystine and uric acid stones using a porous bag and an Erlenmeyer glass. The study of the inhibiting activity of calcium oxalate crystallization, was based on temporal measurements of the optical density, registered at a 620 nm wavelength for 30 min using an ultraviolet−visible spectrophotometer. The silylation method was performed to identify phytochemicals, followed by gas chromatography coupled with mass spectrophotometry (GC/MS) analysis. The results show significant litholytic activity of Argania Spinosa press-cake hydro-ethanolic extract on uric acid and cystine stones, respectively, with dissolution rates (DR) of 86.38% and 60.42% versus 3.23% and 9.48% for the hydro-ethanolic extract of Acacia senegal exudate. Furthermore, the percentages of nucleation inhibition are 83.78% and 43.77% (p ˂ 0.05) for Argania spinosa and Acacia senegal, respectively. The results point to the detection of 17 phytochemicals in Argania spinosa press-cake extract, the majority of which are phenolic acids and have potent anti-urolithiatic action.

Extraction Optimization, Structural Characterization, and Anti-Hepatoma Activity of Acidic Polysaccharides From Scutellaria barbata D. Don

The Chinese medicinal herb Scutellaria barbata D. Don has antitumour effects and is used to treat liver cancer in the clinic. S. barbata polysaccharide (SBP), one of the main active components extracted from S. barbata D. Don, exhibits antitumour activity. However, there is still a lack of research on the extraction optimization, structural characterization, and anti-hepatoma activity of acidic polysaccharides from S. barbata D. Don. In this study, the optimal extraction conditions for SBP were determined by response surface methodology (RSM): the material-liquid ratio was 1:25, the extraction time was 2 h, and the extraction temperature was 90°C. Under these conditions, the average extraction efficiency was 3.85 ± 0.13%. Two water-soluble polysaccharides were isolated from S. barbata D. Don, namely, SBP-1A and SBP-2A, these homogeneous acidic polysaccharide components with average molecular weights of 1.15 × 10⁵ Da and 1.4 × 10⁵ Da, respectively, were obtained at high purity. The results showed that the monosaccharide constituents of the two components were fucose, galactosamine hydrochloride, rhamnose, arabinose, glucosamine hydrochloride, galactose, glucose, xylose, and mannose; the molar ratio of these constituents in SBP-1A was 0.6:0.3:0.6:30.6:3.3:38.4:16.1:8:1.4, and that in SBP-2A was 0.6:0.5:0.8:36.3:4.4:42.7:9.2:3.6:0.7. In addition, SBP-1A and SBP-2A contained uronic acid and β-glucan, and the residue on the polysaccharide was mainly pyranose. The in vitro results showed that the anti-hepatoma activity of SBP-2A was better than that of SBP-1A and SBP. In addition, SBP-2A significantly enhanced HepG2 cell death, as cell viability was decreased, and SBP-2A induced HepG2 cell apoptosis and blocked the G1 phase. This phenomenon was coupled with the upregulated expression of P53 and Bax/Bcl-2 ratio, as well as the downregulated expression of the cell cycle-regulating protein cyclinD1, CDK4, and Bcl-2 in this study. Further analysis showed that 50 mg/kg SBP-2A inhibited the tumour growth in H22 tumour-bearing mice, with an average inhibition rate of 40.33%. Taken together, SBP-2A, isolated and purified from S. barbata showed good antitumour activity in vivo and in vitro, and SBP-2A may be a candidate drug for further evaluation in cancer prevention. This study provides insight for further research on the molecular mechanism of the anti-hepatoma activity of S. barbata polysaccharide.

Association between body fat distribution and kidney stones: Evidence from a US population

OBJECTIVES

We aimed to evaluate the relationship between the proportion of Android to Gynoid ratio and the incidence of kidney stones among US adults.

METHODS

Participants aged 20-59 years from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) database were selected to assess the association between Android to Gynoid ratio and kidney stone prevalence using logistic regression analysis, subgroup analysis and calculation of dose-response curves.

RESULTS

This study ultimately included 10858 participants, of whom 859 self-reported a history of kidney stones. And after adjusting for all confounders, an increased Android to Gynoid ratio was associated with an increased prevalence of kidney stones (OR=2.75, 95% CI:1.62-4.88). And subgroup analysis showed an increased prevalence of kidney stones in women (OR=3.55, 95% CI: 1.54-8.22), non-diabetic (OR=2.59, 95% CI: 1.45-4.60), 60 > age ≥ 40 years (OR=3.51, 95% CI: 1.83-6.71), Mexican-American (OR=4.35, 95% CI: 1.40- 13.53) and white (OR=3.86, 95% CI: 1.82-8.18) groups, there was a significant positive association between A/G ratio and kidney stones. In contrast, in the hypertensive subgroup, the A/G ratio was associated with kidney stones in all groups.

CONCLUSIONS

Higher Android to Gynoid ratio is associated with a high prevalence of kidney stone disease.

[Assessment of biological activities of exopolysaccharides with different relative molecular masses extracted from Rhizopus nigricans]

OBJECTIVE

To evaluate the antioxidant, anti-tumor and immunomodulatory activities of exopolysaccharides with different molecular masses isolated from Rhizopus nigricans.

METHODS

Three polysaccharides with different molecular masses, namely RPS-1, RPS-2 and RPS-3, were separated from the fermentation broth of Rhizopus nigricans by fractional ethanol precipitation, and their capacity for scavenging DPPH, ABTS, and hydroxyl radicals was assessed. Cell counting kit-8 was used to analyze the changes in the viability of MFC, A549 and RAW 264.7 cells following treatments with the 3 polysaccharides; The level of nitric oxide in the supernatant of RAW 264.7 cells was detected using a nitric oxide detection kit, and the apoptosis rate of A549 cells was analyzed with flow cytometry.

RESULTS

All the 3 polysaccharides had good antioxidant activities, and among them RPS-1 with a medium molecular mass exhibited the strongest scavenging capacity for DPPH and ABTS radicals (P < 0.05) while RPS-3 with the lowest molecular mass had the best scavenging activity for hydroxyl radicals (P < 0.01). All the 3 polysaccharides were capable of inhibiting the proliferation of MFC cells and A549 cells, activating the macrophages RAW 264.7 cells, and inducing apoptosis of A549 cells. RPS-2 with the highest molecular mass showed the strongest inhibitory effects against MFC and A549 cells (P > 0.05), and RPS-2 had the strongest activity for inducing apoptosis in A549 cells (P < 0.05). Compared with the other two polysaccharides, RPS-2 more strongly promoted the proliferation of RAW 264.7 cells and enhanced NO release from the cells (P < 0.05).

CONCLUSION

The 3 polysaccharides all have antioxidant, anti-tumor and immunomodulatory activities, and among them RPS-1 and RPS-3 have better antioxidant activities, and RPS-2 has stronger anti-tumor and immunomodulatory activities.

Antioxidant activity of sulfated Porphyra yezoensis polysaccharides and their regulating effect on calcium oxalate crystal growth

The nucleation, growth and aggregation of calcium oxalate (CaOx) crystals and the oxidative damage of renal tubular epithelial cells are the key factors to induce kidney stones. In this study, degraded Porphyra yezoensis polysaccharide (PYP0) with 14.14% sulfate group (-OSO₃^-) content was modified via the sulfur trioxide-pyridine method to obtain three kinds of sulfated P. yezoensis polysaccharides (PYPs), namely, PYPS1, PYPS2, and PYPS3, with -OSO₃^- group contents of 17.11%, 20.28%, and 27.14% respectively. Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR analyses showed that the -OSO₃^- groups replaced the hydroxyl groups at the C2, C4, and C6 positions on (1 → 3)-linked β-D-galactose, the basic structural skeleton unit of PYP0. The antioxidant activity of the PYPSs increased after sulfation, and their scavenging capacity for OH and DPPH free radicals was enhanced with the increase in their -OSO₃^- group content. Calcium oxalate (CaOx) crystal growth experiments showed that sulfated PYPs promoted the conversion of the thermodynamically stable and sharp CaOx monohydrate (COM) crystals into the thermodynamically unstable and round CaOx dihydrate crystals. With the increase in the -OSO₃^- group content of the polysaccharides, the concentration of soluble Ca²⁺ ions in the supernatant increased and the amount of CaOx precipitate decreased. PYPs were nontoxic to human kidney proximal tubular epithelial cells (HK-2) and could protect HK-2 from oxidative damage caused by nano-COM and reduce the level of reactive oxygen species in cells. PYPS3, which had the highest degree of sulfation, had the best protective capability. The results of this work showed that sulfation improved the biological activity of PYPs. This study could provide inspiration for the development of new drugs for the prevention and treatment of kidney stones.

Carboxymethylation of Corn Silk Polysaccharide and Its Inhibition on Adhesion of Nanocalcium Oxalate Crystals to Damaged Renal Epithelial Cells

The purpose of this study was to explore the repair effect of carboxymethyl-modified corn silk polysaccharide (CSP) on oxidatively damaged renal epithelial cells and the difference in adhesion between cells and calcium oxalate crystals. The CSP was degraded and modified through carboxymethylation. An oxidatively damaged cell model was constructed by oxalate damage to human kidney proximal tubular epithelial (HK-2) cells. Then, the damaged cells were repaired by modified polysaccharides, and the changes in biochemical indexes and adhesion ability between cells and crystals before and after repair were detected. Four modified polysaccharides with carboxyl group (-COOH) contents of 3.92% (CSP0), 7.75% (CCSP1), 12.90% (CCSP2), and 16.38% (CCSP3) were obtained. Compared with CSP0, CCSPs had stronger antioxidant activity, could repair damaged HK-2 cells, and could reduce phosphorylated serine eversion on the cell membrane, the expression of osteopontin (OPN) and Annexin A1, and crystal adhesion. However, its effect on the expression of hyaluronic acid synthase was not substantial. The carboxymethyl modification of the CSP can improve its ability to repair cells and inhibit crystal adhesion and aggregation. A high carboxymethylation degree results in strong polysaccharide activity. CCSPs are expected to reduce the risk of kidney stone formation and recurrence.

Inhibition of Calcium Oxalate Formation and Antioxidant Activity of Carboxymethylated Poria cocos Polysaccharides

Three carboxymethylated Poria cocos polysaccharides (PCP-C1, PCP-C2, and PCP-C3) with -COOH contents of 6.13%, 10.24%, and 16.22%, respectively, were obtained by carboxymethylation of the original polysaccharide (PCP-C0), which has a molecular weight of 4 kDa and a carboxyl (-COOH) content of 2.54%. The structure of the PCP-Cs was characterized by FT-IR, ¹H NMR, and ¹³C NMR spectra. The four PCP-Cs exhibited antioxidant activity, and their ability to scavenge radicals (hydroxyl and DPPH) and chelate ferrous ions was positively correlated with the degree of carboxymethylation. As the content of -COOH groups in the PCP-Cs increases, their ability to regulate the growth of calcium oxalate (CaOx) crystals was enhanced, thus inhibiting the growth of calcium oxalate monohydrate (COM) crystals and inducing the formation of more calcium oxalate dihydrate (COD) crystals. The formed CaOx crystal was more round and blunt, the absolute value of the Zeta potential on the crystal surface increased, and the aggregation between crystals was inhibited. Thermogravimetric analysis curves showed that the proportions of PCP-C0, PCP-C1, PCP-C2, and PCP-C3 incorporated into the crystal were 20.52%, 15.60%, 10.65%, and 9.78%, respectively, in the presence of 0.4 g/L PCP-Cs. PCP-C protection resisted oxidative damages of human kidney proximal tubular epithelial cells (HK-2) caused by oxalate, resulting in increased cell viability and superoxide dismutase activity and decreased reactive oxygen species levels, malondialdehyde content, and 8-hydroxy-deoxyguanosine expression. Hence, PCP-Cs, especially PCP-C3, can inhibit the formation of CaOx crystals and may have the potential to be an alternative antistone drug.

Effects of Selenized Astragalus Polysaccharide on the Adhesion and Endocytosis of Nanocalcium Oxalate Dihydrate after the Repair of Damaged HK-2 Cells

An oxidative damage model of human proximal renal epithelial cells (HK-2) was established using oxalate damage. The repair effects of Astragalus polysaccharide (APS) and selenized APS (Se-APS) on damaged HK-2 cells were investigated. Differences in the adhesion and endocytosis of HK-2 cells to calcium oxalate dihydrate crystals with a size of approximately 100 nm before and after APS and Se-APS repair were also explored. The results showed that after being repaired by APS and Se-APS, HK-2 cells exhibited increased cell viability, restored cell morphology, reduced reactive oxygen species level, increased mitochondrial membrane potential, reduced phosphatidylserine eversion, and osteopontin expression. Moreover, the amount of adherent crystals on the cell surface decreased, but the amount of endocytic crystals increased. At the same concentration, Se-APS exhibited better repair effects on the damaged HK-2 cells than APS. All these findings revealed that Se-APS may be a potential drug candidate for inhibiting the formation of kidney stones.