Nephrolithiasis: molecular mechanism of renal stone formation and the critical role played by modulators

Plants Used in Mexican Traditional Medicine for the Management of Urolithiasis: A Review of Preclinical Evidence, Bioactive Compounds, and Molecular Mechanisms

Urolithiasis (UL) involves the formation of stones in different parts of the urinary tract. UL is a health problem, and its prevalence has increased considerably in developing countries. Several regions use plants in traditional medicine as an alternative in the treatment or prevention of UL. Mexico has known about the role of traditional medicine in the management of urinary stones. Mexican traditional medicine uses plants such as Argemone mexicana L., Berberis trifoliata Hartw. ex Lindl., Costus mexicanus Liebm, Chenopodium album L., Ammi visnaga (L.) Lam., Eysenhardtia polystachya (Ortega) Sarg., Selaginella lepidophylla (Hook. & Grev.) Spring, and Taraxacum officinale L. These plants contain different bioactive compounds, including polyphenols, flavonoids, phytosterols, saponins, furanochromones, alkaloids, and terpenoids, which could be effective in preventing the process of stone formation. Evidence suggests that their beneficial effects might be associated with litholytic, antispasmodic, and diuretic activities, as well as an inhibitory effect on crystallization, nucleation, and aggregation of crystals. The molecular mechanisms involving these effects could be related to antioxidant, anti-inflammatory, and antimicrobial properties. Thus, the review aims to summarize the preclinical evidence, bioactive compounds, and molecular mechanisms of the plants used in Mexican traditional medicine for the management of UL.

Drug-Induced Acute Kidney Injury

Medications are a common cause of AKI especially for patients admitted to hospital wards and the intensive care unit. Although drug-related kidney injury occurs through different mechanisms, this review will focus on three specific types of tubulointerstitial injury. Direct acute tubular injury develops from several medications, which are toxic to various cellular functions. Their excretory pathways through the proximal tubules contribute further to AKI. Drug-induced AKI may also develop through induction of inflammation within the tubulointerstitium. Medications can elicit a T cell-mediated immune response that promotes the development of acute interstitial nephritis leading to AKI. Although less common, a third pathway to kidney injury results from the insolubility of drugs in the urine leading to their precipitation as crystals within distal tubular lumens, causing a crystalline-related AKI. Intratubular obstruction, direct tubular injury, and localized inflammation lead to AKI. Clinicians should be familiar with the pathogenesis and clinical-pathologic manifestations of these forms of kidney injury. Prevention and treatment of AKI relies on understanding the pathogenesis and judiciously using these agents in settings where AKI risk is high.

Characteristics and Types of Urolithiasis in the Eastern Region of Saudi Arabia: A Single-Center Retrospective Study

Introduction

Urolithiasis is one of the most common conditions encountered in clinical practice with the prevalence increasing globally in the last few decades. Urolithiasis has been found to be more common in areas with a hot climate, such as Saudi Arabia. The aim of this study was to determine the characteristics and the types of urolithiasis most frequently found in the Eastern Region of Saudi Arabia.

Methods

This was a single-center retrospective cohort study based on data extracted from an electronic hospital information system (BESTCare) of all patients diagnosed with urolithiasis at King Abdulaziz Hospital, a tertiary care center in Saudi Arabia's Eastern Region. From January 2013 to December 2016, all adult patients aged 18 and up who presented with urinary calculi (renal and ureter) were included in the study.

Results

A total of 235 patients were reviewed, with a mean age of 48.52 years. Renal calculi were more prevalent in males (74.5%). Calcium oxalate was the predominant type (76%), followed by uric acid calculi (18%) and cystine calculi (4.8%). A small proportion (1.2%) was calcium phosphate calculi. The most frequently associated comorbidity was hypertension (17.9%). The majority (78.5%) had a stone removal through a ureteroscopy and 8.2% by percutaneous nephrolithotomy (PCNL). The mean stone size was 12.2 ± 9.91 mm, with a mean stone Hounsfield unit (HU) of 789.9. The mean urinary PH at stone incident was 6.77, and the mean creatinine level was 92.4mmol.

Conclusion

This study showed that males were more affected by urolithiasis, compared to females in the Eastern Region. Furthermore, calcium oxalate was the predominant type. These findings are consistent with the literature and they highlighted the necessity for further studies in this area, to provide insight into the pathophysiology and incidence of renal calculi for improving patient care.

Ethnomedicinal Plants Used for Treatment of Urolithiasis in India: A Review

Background:

The kidney stone is the most commonly observed and painful disease of the urinary tract in human being. Numerous intrinsic and extrinsic factors are responsible for the formation of kidney stone, for instance, age, sex, heredity (intrinsic factors) and climate, dietary, geography, mineral composition, and water intake (extrinsic factors). The kidney stones are categorized into calcium, struvite or magnesium ammonium phosphate, uric acid or urate, cystine and other types of stones based on chemical composition and pathogenesis. Due to the multifactorial nature of kidney stone disease, the patient may need to rely on complex synthetic medication. However, in ancient Indian history, there are several pieces of evidence where natural resources such as plants were used to remediation this lethal disease.

Objective:

The present review attempts to provide exhaustive information of ethnomedicinal and ethnopharmacological information of medicinal plants used for kidney stone in India.

Result:

Hitherto, there are a total of 258 ethnomedicinal plants from 90 different families reported using for kidney stone application. The majority of the plant species are associated with three important families: Asteraceae, Amaranthaceae, and Fabaceae. Most of the plants are from Andhra Pradesh (43 plants), followed by East Bengal (38), Jammu & Kashmir (36), Uttarakhand (31), Panjab (27), Mizoram (23), Karnataka (20), Maharashtra (20) and Assam (18). The commonly used plant parts for the herbal preparation are roots (21.22 %) followed by leaves/leaf (20.15 %), and sometimes complete plant (17.77 %) is used. The most commonly used method for the formulation is decoction (46.41 %) followed by powder (18.66 %) and then extracts (15.78 %) of different aerial and non-aerial parts of the plant. To date, the in-vitro and in-vivo activities against the kidney stone assessed for more than sixty ethnomedicinal plants.

Conclusion:

The present review epitomizes the ethnomedicinal information of medicinal plants used for kidney stone and pharmacological evidence for anti-urolithiasis activity. Most reported medicinal plants are not yet scientifically explored and need immediate attention before we lose some important species due to excessive deforestation for farming and industrial needs.

Insights into the cytoprotective potential of Bergenia ligulata against oxalate-induced oxidative stress and epithelial-mesenchymal transition (EMT) via TGFβ1/p38MAPK pathway in human renal epithelial cells

Oxalate exposure to human renal epithelial cells triggers a vicious cycle of oxidative stress leading to cellular injury and deposition of calcium oxalate crystals on the injured cells. This results in further oxidative damage causing inflammation and loss of cell-cell adhesion factors, ultimately leading to irreparable kidney damage. However, these events can be attenuated or prevented by plants rich in antioxidants used in the traditional system of medicine for treatment of kidney stones. To delineate the mechanism by which Bergenia ligulata extract exerts its cytoprotective role in oxalate-induced injury we designed this study. Our results revealed that oxalate-injured HK2 cells cotreated with ethanolic extract of Bergenia ligulata displayed increased viability, reduced oxidative stress due to lowered production of intracellular reactive oxygen species (ROS) and decreased apoptosis. We also observed lowered markers of inflammation, along with increased expression of epithelial marker E-cadherin and decreased expression of mesenchymal markers Vimentin, F-actin, Transforming growth factor beta 1 (TGF-β1) and EMT-related proteins in renal tubular epithelial cells through immunocytochemistry, real-time PCR and western blotting. Our findings collectively suggest that by reducing oxidative stress, modulating crystal structure and preventing crystal-cell adhesion, B. ligulata inhibits the EMT pathway by downregulating the various mediators and thereby exerts its cytoprotective effect.

Quantitative phase analysis and microstructural characterization of urinary tract calculi with X-ray diffraction Rietveld analysis on a Caribbean island

In the twin-island state of Trinidad and Tobago, urinary stone analysis is not routinely performed. This study investigates, via powder X-ray diffraction, 52 urinary tract calculi collected from hospitals in Trinidad. Of these, 46 stones were analysed with Rietveld refinement for quantitative analysis and materials characterization. Refined unit-cell, microstructural and weight fraction parameters were obtained, with the last being used for stone classification. The results revealed seven distinct mineralogical phases of varying frequency: calcium oxalate monohydrate (COM, 58%), calcium oxalate dihydrate (COD, 23%), carbonated apatite (APA, 48%), brushite (BRU, 6%), struvite (STR, 42%), uric acid (UA, 23%) and ammonium acid urate (AAU, 19%). The average refined crystallite sizes were 1352 ± 90 Å (COM), 1921 ± 285 Å (COD), 83 ± 5 Å (APA), 1172 ± 9 Å (BRU), 1843 ± 138 Å (STR), 981 ± 87 Å (UA) and 292 ± 83 Å (AAU). Subsequently, 36.5% of stones were categorized as phosphates, 34.6% as oxalates, 13.5% as uric acid/urates and 15.4% as mixed compositions. The study findings highlight the importance of stone analysis as a necessary step towards disease management of local patients, and endorse the application of Rietveld refinement as a natural extension to diffraction-based kidney stone investigations.

Probiotics in the Prevention of the Calcium Oxalate Urolithiasis

Nephrolithiasis ranks third among urological diseases in terms of prevalence, making up about 15% of cases. The continued increase in the incidence of nephrolithiasis is most probably due to changes in eating habits (high protein, sodium, and sugar diets) and lifestyle (reduced physical activity) in all developed countries. Some 80% of all kidney stones cases are oxalate urolithiasis, which is also characterized by the highest risk of recurrence. Frequent relapses of nephrolithiasis contribute to severe complications and high treatment costs. Unfortunately, there is no known effective way to prevent urolithiasis at present. In cases of diet-related urolithiasis, dietary changes may prevent recurrence. However, in some patients, the condition is unrelated to diet; in such cases, there is evidence to support the use of stone-related medications. Interestingly, a growing body of evidence indicates the potential of the microbiome to reduce the risk of developing renal colic. Previous studies have primarily focused on the use of Oxalobacterformigenes in patients with urolithiasis. Unfortunately, this bacterium is not an ideal probiotic due to its antibiotic sensitivity and low pH. Therefore, subsequent studies sought to find bacteria which are capable of oxalate degradation, focusing on well-known probiotics including Lactobacillus and Bifidobacterium strains, Eubacterium lentum, Enterococcus faecalis, and Escherichia coli.

Identification of the pivotal role of SPP1 in kidney stone disease based on multiple bioinformatics analysis

Background

Kidney stone disease (KSD) is a multifactorial disease involving both environmental and genetic factors, whose pathogenesis remains unclear. This study aims to explore the hub genes related to stone formation that could serve as potential therapeutic targets.

Methods

Based on the GSE73680 dataset with 62 samples, differentially expressed genes (DEGs) between Randall’s plaque (RP) tissues and normal tissues were screened and weighted gene co-expression network analysis (WGCNA) was applied to identify key modules associated with KSD. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed to explore the biological functions. The protein–protein interaction (PPI) network was constructed to identify hub genes. Meanwhile, CIBERSORT and ssGSEA analysis were used to estimate the infiltration level of the immune cells. The correlations between hub genes and immune infiltration levels were also investigated. Finally, the top hub gene was selected for further GSEA analysis.

Results

A total of 116 DEGs, including 73 up-regulated and 43 down-regulated genes, were screened in the dataset. The red module was identified as the key module correlated with KSD. 53 genes were obtained for functional enrichment analysis by taking the intersection of DEGs and genes in the red module. GO analysis showed that these genes were mainly involved in extracellular matrix organization (ECM) and extracellular structure organization, and others. KEGG analysis revealed that the pathways of aldosterone-regulated sodium reabsorption, cell adhesion molecules, arachidonic acid (AA) metabolism, and ECM-receptor interaction were enriched. Through PPI network construction, 30 hub genes were identified. CIBERSORT analysis revealed a significantly increased proportion of M0 macrophages, while ssGSEA revealed no significant differences. Among these hub genes, SPP1, LCN2, MMP7, MUC1, SCNN1A, CLU, SLP1, LAMC2, and CYSLTR2 were positively correlated with macrophages infiltration. GSEA analysis found that positive regulation of JNK activity was enriched in RP tissues with high SPP1 expression, while negative regulation of IL-1β production was enriched in the low-SPP1 subgroup.

Conclusions

There are 30 hub genes associated with KSD, among which SPP1 is the top hub gene with the most extensive links with other hub genes. SPP1 might play a pivotal role in the pathogenesis of KSD, which is expected to become a potential therapeutic target, while its interaction with macrophages in KSD needs further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01157-4.

Calcium oxalate crystallization in synthetic urinary medium: the impact of resorcinares and calixarenes

The impact of macrocycles on calcium oxalate formation. Calcium oxalate is a major component of kidney stones, an ailment that affects many people globally.

Differential biomolecular recognition by synthetic vs. biologically-derived components in the stone-forming process using 3D microfluidics

Calcium phosphate (CaP) biomineralization is the hallmark of extra-skeletal tissue calcification and renal calcium stones. Although such a multistep process starts with CaP crystal formation, the mechanism is still poorly understood due to the complexity of the in vivo system and the lack of a suitable approach to simulate a truly in vivo-like environment. Although endogenous proteins and lipids are engaged with CaP crystals in such a biological process of stone formation, most in vitro studies use synthetic materials that can display differential bioreactivity and molecular recognition by the cellular component. Here, we used our in vitro microfluidic (MF) tubular structure, which is the first completely cylindrical platform, with renal tubular cellular microenvironments closest to the functional human kidney tubule, to understand the precise role of biological components in this process. We systematically evaluated the contribution of synthetic and biological components in the stone-forming process in the presence of dynamic microenvironmental cues that originated due to cellular pathophysiology, which are critical for the nucleation, aggregation, and growth of CaP crystals. Our results show that crystal aggregation and growth were enhanced by immunoglobulin G (IgG), which was further inhibited by etidronic acid due to the chelation of extracellular Ca²⁺. Interestingly, biogenic CaP crystals from mice urine, when applied with cell debris and non-specific protein (bovine serum albumin), exhibited a more discrete crystal growth pattern, compared to exposure to synthetic CaP crystals under similar conditions. Furthermore, proteins found on those calcium crystals from mice urine produced discriminatory effects on crystal-protein attachment. Specifically, such biogenic crystals exhibited enhanced affinity to the proteins inherent to those crystals. More importantly, a physiological comparison of crystal induction in renal tubular cells revealed that biogenic crystals are less effective at producing a sustained rise in cytosolic Ca²⁺ compared to synthetic crystals, suggesting a milder detrimental effect to downstream signaling. Finally, synthetic crystal-internalized cells induced more oxidative stress, inflammation, and cellular damage compared to the biogenic crystal-internalized cells. Together, these results suggest that the intrinsic nature of biogenically derived components are appropriate to generate the molecular recognition needed for spatiotemporal effects and are critical towards understanding the process of kidney stone formation.

The Crystalline Nephropathies

Crystalline nephropathies are a unique form of kidney disease characterized by the histologic finding of intrarenal crystal deposition. The intrinsic nature of some molecules and ions combined with a favorable tubular fluid physiology leads to crystal precipitation and deposition within the tubular lumens. Crystal deposition promotes kidney injury through tubular obstruction and both direct and indirect cytotoxicities. Further kidney injury develops from inflammation triggered by these crystals. From a clinical standpoint, the crystalline nephropathies are associated with abnormal urinalysis and urinary sediment findings, tubulopathies, acute kidney injury (AKI), and/or chronic kidney disease (CKD). Urine sediment examination is often helpful in alerting clinicians to the possibility of crystal-related kidney injury. The identification of crystals within the kidneys on biopsy by pathologists prompts clinicians to evaluate patients for medication-related kidney injury, dysproteinemia-related malignancies, and certain inherited disorders. This review will focus on the clinical and pathologic aspects of these 3 categories of crystalline nephropathies.

Nucleation kinetics of calcium oxalate monohydrate as a function of pH, magnesium, and osteopontin concentration quantified with droplet microfluidics

A droplet-based microfluidic platform is presented to study the nucleation kinetics of calcium oxalate monohydrate (COM), the most common constituent of kidney stones, while carefully monitoring the pseudo-polymorphic transitions. The precipitation kinetics of COM is studied as a function of supersaturation and pH as well as in the presence of inhibitors of stone formation, magnesium ions (Mg2+), and osteopontin (OPN). We rationalize the trends observed in the measured nucleation rates leveraging a solution chemistry model validated using isothermal solubility measurements. In equimolar calcium and oxalate ion concentrations with different buffer solutions, dramatically slower kinetics is observed at pH 6.0 compared to pHs 3.6 and 8.6. The addition of both Mg2+ and OPN to the solution slows down kinetics appreciably. Interestingly, complete nucleation inhibition is observed at significantly lower OPN, namely, 3.2 × 10-8 M, than Mg2+ concentrations, 0.875 × 10-4 M. The observed inhibition effect of OPN emphasizes the often-overlooked role of macromolecules on COM nucleation due to their low concentration presence in urine. Moreover, analysis of growth rates calculated from observed lag times suggests that inhibition in the presence of Mg2+ cannot be explained solely on altered supersaturation. The presented study highlights the potential of microfluidics in overcoming a major challenge in nephrolithiasis research, the overwhelming physiochemical complexity of urine.

On the protein content of kidney stones: an explorative study

OBJECTIVES

Kidney stone formation is complex; urinary protein inhibitors play a major role in natural defense against stone formation. Using attenuated total-reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy of kidney stones, proteins are usually not quantified and often reported as 'organic matrix', for which there is little attention: treatment of urolithiasis is based on the nature of the major organic/inorganic stone compound. Literature no longer regards urinary proteins as innocent bystander, but highlights the role of proteins as urolithiasis modulators. We explored the potential significance of the protein content of kidney stones.

METHODS

800 stones were analyzed using ATR-FTIR spectroscopy; spectra were corrected for protein content. The ratio of the amide I peak (1655 cm^-1) divided by the maximum peak was calculated. A subgroup of stones (n = 43) was weighed; protein concentration was assayed. Kidney stone composition was taken into account when calculating protein concentration. Electrophoresis was implemented to investigate the protein bands. Multiple regression analysis was carried out to study the influence of various demographic variables (age, gender, stone type) on protein concentration.

RESULTS

Protein concentration showed a marked variation according to the stone composition. High relative protein content (>0.4% stone mass) was found in mixed calcium apatite/calcium oxalate dihydrate stones, mixed calcium oxalate dihydrate/calcium oxalate monohydrate/calcium apatite stones, and mixed calcium oxalate monohydrate/brushite stones, whereas lower protein percentages were found in cystine, urate, and calcium oxalate monohydrate stones. Protein concentration was dependent of the patient's age.

CONCLUSION

ATR-FTIR is a practical way for assessing protein concentration in kidney stones.

LIST OF ABBREVIATIONS

A: absorbance; as, asymmetric vibrations; ATR-FTIR, attenuated total-reflectance Fourier-transform infrared; β, standardized regression coefficient; CAP, calcium apatite; COD, calcium oxalate dihydrate; COM, calcium oxalate monohydrate; CV, coefficient of variation; δ, bending vibrations; ELISA, enzyme-linked immunosorbent assay; IQR, interquartile range; IR, infrared; LOD, limit of detection; LOQ, limit of quantification; MIR, mid-infrared; N or n, amount; r, correlation; r², coefficient of determination; s, symmetric vibrations; SD, standard deviation; SE, standard error; THP, Tamm-Horsfall protein; UA, uric acid; V, stretching vibrations; VIF: variance inflation factor; ZnSe, zinc selenide.

Oxalate Activates Autophagy to Induce Ferroptosis of Renal Tubular Epithelial Cells and Participates in the Formation of Kidney Stones

Renal tubular epithelial cell damage is the basis for the formation of kidney stones. Oxalate can induce human proximal tubular (HK-2) cells to undergo autophagy and ferroptosis. The present study was aimed at investigating whether the ferroptosis of HK-2 cells induced by oxalate is caused by the excessive activation of autophagy. We treated HK-2 cells with 2 mmol/L of oxalate to establish a kidney stone model. First, we tested the degree of oxidative damage and the level of autophagy and ferroptosis in the control group and the oxalate intervention group. We then knocked down and overexpressed the BECN1 gene and knocked down the NCOA4 gene in HK-2 cells, followed by redetection of the above indicators. We confirmed that oxalate could induce autophagy and ferroptosis in HK-2 cells. Moreover, after oxalate treatment, overexpression of the BENC1 gene increased cell oxidative damage and ferroptosis. In addition, knockdown of NCOA4 reversed the effect of oxalate-induced ferroptosis in HK-2 cells. Our results show that the effects of oxalate on the ferroptosis of HK-2 cells are caused by the activation of autophagy, and knockdown of the NCOA4 could ameliorate this effect.

Sirt1 inhibits kidney stones formation by attenuating calcium oxalate-induced cell injury

Cell injury is a necessary and critical event during CaOx kidney stone formation. Sirt1 exerts a number of pleiotropic effects, protecting against renal cell injury. This study aims to explore the relationship between Sirt1 and CaOx kidney stone formation and the underlying mechanism. Sirt1 expression in renal tissues or HK-2 cells was detected by Western blot, immunohistochemistry and immunofluorescence. Apoptosis in renal tissues was examined by TUNEL staining. Renal pathological changes and the crystals deposition were detected by hematoxylin-eosin and Von Kossa staining. Crystal-cell adhesion and cell injury in HK-2 cells were assessed by atomic absorption spectrometry and flow cytometry, respectively. Sirt1 expression in nephrolithiasis patients was downregulated and the level of apoptosis was increased. Further study found that Sirt1 expression was decreased in both in vivo and in vitro models. Interestingly, the levels of cell injury were elevated in vivo and in vitro models. Suppressing Sirt1 expression promoted COM-induced crystal-cell adhesion and exacerbated cell injury. In contrast, increasing the expression of Sirt1 by lentivirus transfection in vitro and resveratrol administration in vivo, alleviated crystal deposition and cell damage. Our findings suggest that Sirt1 could inhibit kidney stone formation, at least in part, through attenuating CaOx -induced cell injury.

Multicolor imaging of calcium-binding proteins in human kidney stones for elucidating the effects of proteins on crystal growth

The pathogenesis of kidney stone formation includes multi-step processes involving complex interactions between mineral components and protein matrix. Calcium-binding proteins in kidney stones have great influences on the stone formation. The spatial distributions of these proteins in kidney stones are essential for evaluating the in vivo effects of proteins on the stone formation, although the actual distribution of these proteins is still unclear. We reveal micro-scale distributions of three different proteins, namely osteopontin (OPN), renal prothrombin fragment 1 (RPTF-1), and calgranulin A (Cal-A), in human kidney stones retaining original mineral phases and textures: calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD). OPN and RPTF-1 were distributed inside of both COM and COD crystals, whereas Cal-A was distributed outside of crystals. OPN and RPTF-1 showed homogeneous distributions in COM crystals with mosaic texture, and periodically distributions parallel to specific crystal faces in COD crystals. The unique distributions of these proteins enable us to interpret the different in vivo effects of each protein on CaOx crystal growth based on their physico-chemical properties and the complex physical environment changes of each protein. This method will further allow us to elucidate in vivo effects of different proteins on kidney stone formation.

Lowe syndrome patient cells display mTOR- and RhoGTPase-dependent phenotypes alleviated by rapamycin and statins

Lowe syndrome (LS) is an X-linked developmental disease characterized by cognitive deficiencies, bilateral congenital cataracts and renal dysfunction. Unfortunately, this disease leads to the early death of affected children often due to kidney failure. Although this condition was first described in the early 1950s and the affected gene (OCRL1) was identified in the early 1990s, its pathophysiological mechanism is not fully understood and there is no LS-specific cure available to patients. Here we report two important signaling pathways affected in LS patient cells. While RhoGTPase signaling abnormalities led to adhesion and spreading defects as compared to normal controls, PI3K/mTOR hyperactivation interfered with primary cilia assembly (scenario also observed in other ciliopathies with compromised kidney function). Importantly, we identified two FDA-approved drugs able to ameliorate these phenotypes. Specifically, statins mitigated adhesion and spreading abnormalities while rapamycin facilitated ciliogenesis in LS patient cells. However, no single drug was able to alleviate both phenotypes. Based on these and other observations, we speculate that Ocrl1 has dual, independent functions supporting proper RhoGTPase and PI3K/mTOR signaling. Therefore, this study suggest that Ocrl1-deficiency leads to signaling defects likely to require combinatorial drug treatment to suppress patient phenotypes and symptoms.

Dual modulatory effects of diosmin on calcium oxalate kidney stone formation processes: Crystallization, growth, aggregation, crystal-cell adhesion, internalization into renal tubular cells, and invasion through extracellular matrix

Diosmin is a natural flavone glycoside (bioflavonoid) found in fruits and plants with several pharmacological activities. It has been widely used as a dietary supplement or therapeutic agent in various diseases/disorders. Although recommended, evidence of its protective mechanisms against kidney stone disease (nephrolithiasis/urolithiasis), especially calcium oxalate (CaOx) monohydrate (COM) that is the most common type, remained unclear. In this study, we thus systematically evaluated the effects of diosmin (at 2.5-160 nM) on various stages of kidney stone formation processes, including COM crystallization, crystal growth, aggregation, crystal-cell adhesion, internalization into renal tubular cells and invasion through extracellular matrix (ECM). The results showed that diosmin had dose-dependent modulatory effects on all the mentioned COM kidney stone processes. Diosmin significantly increased COM crystal number and mass during crystallization, but reduced crystal size and growth. While diosmin promoted crystal aggregation, it inhibited crystal-cell adhesion and internalization into renal tubular cells. Finally, diosmin promoted crystal invasion through the ECM. Our data provide evidence demonstrating both inhibiting and promoting effects of diosmin on COM kidney stone formation processes. Based on these dual modulatory activities of diosmin, its anti-urolithiasis role is doubtful and cautions should be made for its use in kidney stone disease.

Recent advances on the mechanisms of kidney stone formation (Review)

Kidney stone disease is one of the oldest diseases known to medicine; however, the mechanisms of stone formation and development remain largely unclear. Over the past decades, a variety of theories and strategies have been developed and utilized in the surgical management of kidney stones, as a result of recent technological advances. Observations from the authors and other research groups suggest that there are five entirely different main mechanisms for kidney stone formation. Urinary supersaturation and crystallization are the driving force for intrarenal crystal precipitation. Randall's plaques are recognized as the origin of calcium oxalate stone formation. Sex hormones may be key players in the development of nephrolithiasis and may thus be potential targets for new drugs to suppress kidney stone formation. The microbiome, including urease-producing bacteria, nanobacteria and intestinal microbiota, is likely to have a profound effect on urological health, both positive and negative, owing to its metabolic output and other contributions. Lastly, the immune response, and particularly macrophage differentiation, play crucial roles in renal calcium oxalate crystal formation. In the present study, the current knowledge for each of these five aspects of kidney stone formation is reviewed. This knowledge may be used to explore novel research opportunities and improve the understanding of the initiation and development of kidney stones for urologists, nephrologists and primary care.

Kaempferol alleviates calcium oxalate crystal-induced renal injury and crystal deposition via regulation of the AR/NOX2 signaling pathway

BACKGROUND

Calcium oxalate (CaOx) crystal deposition and crystal-induced renal tubular epithelial cell injury have been found to fundamentally contribute to the formation of CaOx nephrolithiasis.

PURPOSE

In the current work, we aim to study the role and mechanism of kaempferol in CaOx crystal kidney deposition and crystal-induced renal injury.

STUDY DESIGN

Mice models and HK-2 cells were used to investigate the effect of kaempferol in CaOx crystal-induced renal injury and crystal deposition in the kidney and its underlying mechanism by a series of experiments.

METHODS

CaOx crystal deposition in mice renal tubulars and tubular damage were evaluated. And crystal adhesion to HK-2 cells, as well as cellular injury were identified. Furthermore, the effect of kaempferol on the expression of androgen receptor (AR) in renal tubular epithelial cells was assessed. The interaction between AR and nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), and the intrinsic molecular mechanism of how AR regulated NOX2 in HK-2 cells were dissected. Additionally, several different assays were applied to analyze the expression levels of various related genes in this study.

RESULTS

It was revealed that kaempferol reduced CaOx crystal deposition in renal tubulars and crystal adhesion to HK-2 cells. Meanwhile, the results of in vivo and in vitro experiments corroborated that crystal-associated cellular injury, oxidative stress, inflammation and over-expression of OPN and CD44 in the kidney were ameliorated by kaempferol. Moreover, kaempferol functioned on inhibiting the expression of AR in renal tubular epithelial cells, and AR was able to up-regulate the expression of NOX2 at the transcriptional level by directly binding to the promoter of NOX2. Kaempferol decreased crystal deposition and crystal-induced renal oxidative and inflammatory injury by the down-regulation of AR/NOX2 signaling pathway.

CONCLUSION

Taken together, our study findings suggest that kaempferol has a suppressive effect on renal AR expression, which can attenuate CaOx crystal deposition and crystal-induced kidney injury through repressing oxidative stress and inflammation in the kidney by modulating the AR/NOX2 signaling pathway. It demonstrates that kaempferol may have preventive and therapeutic potential for CaOx nephrolithiasis.

Evaluations of the curative efficacy of G. fruticosus solvent extracts in experimentally induced nephrolithiatic Wistar male rats

BACKGROUND

In Ethiopian folk medicine, there is a claim that medicinal plants can treat urolithiasis although there is insufficient scientific evidence. The objective of this study was to evaluate the curative efficacy of Gomphocarpus fruticosus extracts in experimentally induced nephrolithiatic rats.

METHODS

Urolithiasis was induced in male Wistar rats by feeding ethylene glycol in drinking water for 28 days. The curative effects were evaluated after oral administrations of 200 mg/kg of the extracts from 15 to 28 days. Urine samples were collected 1 day before sacrificing the rats. Blood, liver and kidney samples were gathered under anaesthetic condition at day 28. Crystals in the urine were also analyzed by light microscopy.

RESULTS

G. fruticosus EtOAc extract reduced significantly the level of sodium (P < 0.001), whereas it was significantly elevated the levels of magnesium and citrate (P < 0.01) compared to lithiatic control. G. fruticosus BuOH extract lowered the levels of potassium (P < 0.01), calcium and phosphate in urolithiatic rats. It was also observed that G. fruticosus EtOAc extract decreased the level of oxalate in the urine (P < 0.001), whereas it was increased the levels of magnesium (P < 0.05) and citrate (P < 0.01) in serum analysis after exposure to BuOH extract. In the kidneys, CaOx crystal deposits were reduced significantly by G. fruticosus EtOAc extract (P < 0.01).

CONCLUSION

It has been noted that G. fruticosus EtOAc extract was potent in treating urolithiasis. However, further study is required to assess the efficacy of the active compounds against urolithiasis.

Calcium-sensing receptor promotes calcium oxalate crystal adhesion and renal injury in Wistar rats by promoting ROS production and subsequent regulation of PS ectropion, OPN, KIM-1, and ERK expression

OBJECTIVES

To explore the mechanism of calcium-sensing receptors (CaSRs) during the development of nephrolithiasis.

MATERIALS AND METHODS

Wistar rats were treated with ethylene glycol to induce calcium oxalate crystallization, and gadolinium chloride (GdCl₃, an agonist of CaSR) and NPS 2390 (an antagonist of CaSR) were added. Oxidative stress (OS) and calcium oxalate crystals in the kidney were observed. CaSR expression and the expression of extracellular signal-regulated protein kinase (ERK), OPN, and KIM-1 were determined by western blotting. In addition, renal tubular epithelial cells were isolated from the kidney to observe phosphatidylserine (PS) ectropion using flow cytometric analysis. Various biochemical parameters were assessed in serum and urine at the end of the experiment.

RESULTS

Calcium oxalate increased OS, crystal adhesion, PS ectropion, and the expression of CaSR and ERK, OPN, and KIM-1 in vivo. In addition, lower levels of urine citrate as well as increased serum creatinine and urea levels were observed after treatment with calcium oxalate (p < .05). Compared with calcium oxalate treatment alone, the above deleterious changes were further significantly confirmed by GdCl₃ but were reversed by NPS-2390. However, urine calcium excretion was decreased after ethylene glycol treatment but was significantly reduced by NPS 2390 and increased by GdCl₃ (p < .05).

CONCLUSIONS

The results suggest that CaSR might play significant roles in the induction of nephrolithiasis in rats by regulating reactive oxygen species (ROS) and PS ectropion and the composition of urine, OPN, KIM-1, and ERK expression.

Theaflavin protects against oxalate calcium-induced kidney oxidative stress injury via upregulation of SIRT1

Renal tubular cell injury induced by calcium oxalate (CaOx) is a critical initial stage of kidney stone formation. Theaflavin (TF) has been known for its strong antioxidative capacity; however, the effect and molecular mechanism of TF against oxidative stress and injury caused by CaOx crystal exposure in kidneys remains unknown. To explore the potential function of TF on renal crystal deposition and its underlying mechanisms, experiments were conducted using a CaOx nephrocalcinosis mouse model established by glyoxylate intraperitoneal injection, and HK-2 cells were subjected to calcium oxalate monohydrate (COM) crystals, with or without the treatment of TF. We discovered that TF treatment remarkably protected against CaOx-induced kidney oxidative stress injury and reduced crystal deposition. Additionally, miR-128-3p expression was decreased and negatively correlated with SIRT1 level in mouse CaOx nephrocalcinosis model following TF treatment. Moreover, TF suppressed miR-128-3p expression and further abolished its inhibition on SIRT1 to attenuate oxidative stress in vitro. Mechanistically, TF interacted with miR-128-3p and suppressed its expression. In addition, miR-128-3p inhibited SIRT1 expression by directly binding its 3'-untranslated region (UTR). Furthermore, miR-128-3p activation partially reversed the acceerative effect of TF on SIRT1 expression. Taken together, TF exhibits a strong nephroprotective ability to suppress CaOx-induced kidney damage through the recovery of the antioxidant defense system regulated by miR-128-3p/SIRT1 axis. These findings provide novel insights for the prevention and treatment of renal calculus.

Resveratrol Attenuates Oxalate-Induced Renal Oxidative Injury and Calcium Oxalate Crystal Deposition by Regulating TFEB-Induced Autophagy Pathway

The oxidative injury of renal tubular epithelial cells caused by inflammation and oxidative stress induced by hyperoxaluria is an important factor in the kidney calcium oxalate (CaOx) stone formation. Resveratrol (RSV) has been reported to reduce oxidative injury to renal tubular epithelial cells, and autophagy is critical for the protective effect of resveratrol. However, the protective mechanism of RSV in oxalate-induced oxidative injury of renal tubular cells and the role of autophagy in this process are still unclear. In our study, glyoxylic acid monohydrate-induced rats were treated with or without resveratrol, and it was detected that the overexpression of oxidant species, CaOx crystal deposition, apoptosis level, inflammatory cytokines and osteoblastic-associated protein expression were reversed by resveratrol. Additionally, Resveratrol pretreatment significantly reversed oxalate -induced decline in cell viability, cell damage, oxidant species overexpression, and osteogenic transformation in normal rat kidney epithelial-like (NRK-52E) cells. Furthermore, we found that RSV pretreatment promoted intracellular LC3II upregulation, p62 downregulation, and autophagosome formation, whereas 3-methyladenine treatment reduced this effect. Moreover, RSV induced the expression of transcription factor EB (TFEB) in the nucleus of NRK-52E cells in a concentration-dependent manner. After transfection of NRK-52E cells with TFEB siRNA, we showed that the RSV-induced increase in TFEB expression and autophagosome formation were inhibited. Simultaneously, RSV-induced NRK-52E cells protection was partially reversed. These results suggested that RSV regulates oxalate-induced renal inflammation, oxidative injury, and CaOx crystal deposition in vitro and in vivo through the activation of a TFEB-induced autophagy.

Antiurolithic efficacy of a phenolic rich ethyl acetate fraction of the aerial parts of Aerva lanata (Linn) Juss. ex Schult. in ethylene glycol induced urolithic rats

OBJECTIVES

The study was carried out to evaluate the in vivo antiurolithic efficaciousness of an ethyl acetate fraction of Aerva lanata (EAFAL) derived from the hydromethanolic extract of its aerial parts (HMEAL).

METHODS

In vivo pharmacological potency of EAFAL was assessed by ethylene glycol (EG) induced urolithiasis model in male Wistar albino rats. Urine samples of the animals were analysed for physical parameters, stone promoters, inhibitors along with an evaluation of the biochemical parameters of serum and kidneys. Histopathological investigation of the kidneys was done. The fraction was further subjected to LC-MS and HPLC for its phytochemical evaluation.

KEY FINDINGS

EAFAL demonstrated a significant antiurolithic effect by a restoration of the balance between urinary promoters and inhibitors along with an amelioration of the urinary pH. The abnormally elevated levels of serum nitrogenous substances, calcium, albumin, globulin, total protein along with altered renal calcium, oxalate and uric acid were also alleviated significantly followed by an improvement of the histopathological aberrancies. Phytochemical analysis showed evidence of phenolic components and flavonoids.

CONCLUSIONS

The current findings prove the beneficial role of phenolic and flavonoid rich EAFAL in ameliorating urolithiasis induced abnormalities of urine, serum and kidneys.

Towards an understanding of the chemo-mechanical influences on kidney stone failure via the material point method

This paper explores the use of the meshfree computational mechanics method, the Material Point Method (MPM), to model the composition and damage of typical renal calculi, or kidney stones. Kidney stones are difficult entities to model due to their complex structure and failure behavior. Better understanding of how these stones behave when they are broken apart is a vital piece of knowledge to medical professionals whose aim is to remove these stone by breaking them within a patient’s body. While the properties of individual stones are varied, the common elements and proportions are used to generate synthetic stones that are then placed in a digital experiment to observe their failure patterns. First a more traditional engineering model of a Brazil test is used to create a tensile fracture within the center of these stones to observe the effect of stone consistency on failure behavior. Next a novel application of MPM is applied which relies on an ultrasonic wave being carried by surrounding fluid to model the ultrasonic treatment of stones commonly used by medical practitioners. This numerical modeling of Extracorporeal Shock Wave Lithotripsy (ESWL) reveals how these different stones failure in a more real-world situation and could be used to guide further research in this field for safer and more effective treatments.

Calcium oxalate kidney stones, where is the organic matter?: A synchrotron based infrared microspectroscopy study

Kidney stones are collections of microcrystals formed inside the kidneys, which affect 6% to 12% of the population worldwide, with an increasing recurrence (50%-72%) after the first episode. The most abundant type is calcium oxalate (66%), described as monohydrated (COM) and dihydrated (COD). An issue in their chemistry is the transformation process of the metastable specie (COD) into the stable one, which is chemically, and in appearance, monohydrated. Since the origin of these species is different, it is important to differentiate between the transformation stage (and what stabilize COD) to understand the physiopathology and prevent the patients' recurrence. This work focuses on the organic matter distribution along these nephroliths by synchrotron radiation-based infrared microspectroscopy. Differences in the asymmetric stretching of the aliphatic hydrocarbons suggest that lipids may participate in the stabilization of COD and as inhibitors of COM formation/development; however, the presence of proteins in the nucleus could indicate a promoting role.

Investigation of potential anti-urolithiatic activity from different types of Musa pseudo-stem extracts in inhibition of calcium oxalate crystallization

Background

The banana or scientifically referred to as Musa sp., is one of the most popular fruits all over the world. Almost all parts of a banana tree, including the fruits, stem juice, and flowers are commonly used as traditional medicine for treating diarrhoea (unripe), menorrhagia, diabetes, dysentery, and antiulcerogenic, hypoglycemic, antilithic, hypolipidemic conditions, plus antioxidant actions, inflammation, pains and even snakebites. The study carried out was to evaluate in vitro anti-urolithiatic activity from different types of Musa pseudo-stems.

Methods

Observing anti-urolithiathic activity via in vitro nucleation and aggregation assay using a spectrophotometer followed by microscopic observation. A total of 12 methanolic extracts were tested to determine the potential extracts in anti-urolithiasis activities. Cystone was used as a positive control.

Results

The results manifested an inhibition of nucleation activity (0.11 ± 2.32% to 55.39 ± 1.01%) and an aggregation activity (4.34 ± 0.68% to 58.78 ± 1.81%) at 360 min of incubation time. The highest inhibition percentage in nucleation assay was obtained by the Musa acuminate x balbiciana Colla cv “Awak Legor” methanolic pseudo-stem extract (2D) which was 55.39 ± 1.01%at 60 min of incubation time compared to the cystone at 30.87 ± 0.74%. On the other hand,the Musa acuminate x balbiciana Colla cv “Awak Legor” methanolic bagasse extract (3D) had the highest inhibition percentage in the aggregation assay incubated at 360 min which was obtained at 58.78 ± 1.8%; 5.53% higher than the cystone (53.25%).The microscopic image showed a great reduction in the calcium oxalate (CaOx) crystals formation and the size of crystals in 2D and 3D extracts, respectively, as compared to negative control.

Conclusions

The results obtained from this study suggest that the extracts are potential sources of alternative medicine for kidney stones disease.

Mineralogy of microbially induced calcium carbonate precipitates formed using single cell drop-based microfluidics

Microbe-mineral interactions are ubiquitous and can facilitate major biogeochemical reactions that drive dynamic Earth processes such as rock formation. One example is microbially induced calcium carbonate precipitation (MICP) in which microbial activity leads to the formation of calcium carbonate precipitates. A majority of MICP studies have been conducted at the mesoscale but fundamental questions persist regarding the mechanisms of cell encapsulation and mineral polymorphism. Here, we are the first to investigate and characterize precipitates on the microscale formed by MICP starting from single ureolytic E. coli MJK2 cells in 25 µm diameter drops. Mineral precipitation was observed over time and cells surrounded by calcium carbonate precipitates were observed under hydrated conditions. Using Raman microspectroscopy, amorphous calcium carbonate (ACC) was observed first in the drops, followed by vaterite formation. ACC and vaterite remained stable for up to 4 days, possibly due to the presence of organics. The vaterite precipitates exhibited a dense interior structure with a grainy exterior when examined using electron microscopy. Autofluorescence of these precipitates was observed possibly indicating the development of a calcite phase. The developed approach provides an avenue for future investigations surrounding fundamental processes such as precipitate nucleation on bacteria, microbe-mineral interactions, and polymorph transitions.

Human kidney stone matrix proteins alleviate hyperoxaluria induced renal stress by targeting cell-crystal interactions

Increased levels of urinary oxalate also known as hyperoxaluria, increase the likelihood of kidney stone formation through enhanced calcium oxalate (CaOx) crystallization. The management of lithiatic renal pathology requires investigations at the initial macromolecular stages. Hence, the current study was designed to unravel the protein make-up of human kidney stones and its impact on renal cells' altered proteome, induced as the consequence of CaOx injury. CaOx kidney stones were collected from patients; stones were pooled for entire cohort, followed by protein extraction. Immunocytochemistry, RT-PCR and flow-cytometric analysis revealed the promising antilithiatic activity of kidney stone matrix proteins. The iTRAQ analysis of renal cells showed up-regulation of 12 proteins and down-regulation of 41 proteins due to CaOx insult, however, this differential expression was normalized in the presence of kidney stone matrix proteins. Protein network analysis revealed involvement of up-regulated proteins in apoptosis, calcium-binding, inflammatory and stress response pathways. Moreover, seven novel antilithiatic proteins were identified from human kidney stones' matrix: Tenascin-X-isoform2, CCDC-144A, LIM domain kinase-1, Serine/Arginine receptor matrix protein-2, mitochondrial peptide methionine sulfoxide reductase, volume-regulated anion channel subunit-LRRC8A and BMPR2. In silico analysis concluded that these proteins exert antilithiatic potential through crystal binding, thereby inhibiting the crystal-cell interaction, a pre-requisite to initiate inflammatory response. Thus, the outcomes of this study provide insights into the molecular events of CaOx induced renal toxicity and subsequent progression into nephrolithiasis.

Comprehensive study of altered proteomic landscape in proximal renal tubular epithelial cells in response to calcium oxalate monohydrate crystals

Background

Calcium oxalate monohydrate (COM), the major crystalline composition of most kidney stones, induces inflammatory infiltration and injures in renal tubular cells. However, the mechanism of COM-induced toxic effects in renal tubular cells remain ambiguous. The present study aimed to investigate the potential changes in proteomic landscape of proximal renal tubular cells in response to the stimulation of COM crystals.

Methods

Clinical kidney stone samples were collected and characterized by a stone component analyzer. Three COM-enriched samples were applied to treat human proximal tubular epithelial cells HK-2. The proteomic landscape of COM-crystal treated HK-2 cells was screened by TMT-labeled quantitative proteomics analysis. The differentially expressed proteins (DEPs) were identified by pair-wise analysis. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of DEPs were performed. Protein interaction networks were identified by STRING database.

Results

The data of TMT-labeled quantitative proteomic analysis showed that a total of 1141 proteins were differentially expressed in HK-2 cells, of which 699 were up-regulated and 442 were down-regulated. Functional characterization by KEGG, along with GO enrichments, suggests that the DEPs are mainly involved in cellular components and cellular processes, including regulation of actin cytoskeleton, tight junction and focal adhesion. 3 high-degree hub nodes, CFL1, ACTN and MYH9 were identified by STRING analysis.

Conclusion

These results suggested that calcium oxalate crystal has a significant effect on protein expression profile in human proximal renal tubular epithelial cells.

Hypomagnesuria is Associated With Nephrolithiasis in Patients With Asymptomatic Primary Hyperparathyroidism

CONTEXT

The pathogenesis of nephrolithiasis in primary hyperparathyroidism (PHPT) remains to be elucidated. The latest guidelines suggest parathyroidectomy in patients with asymptomatic PHPT with hypercalciuria (> 400 mg/d) and increased stone risk profile.

OBJECTIVE

The objective of this work is to evaluate the association of urinary stone risk factors and nephrolithiasis in patients with asymptomatic sporadic PHPT and its clinical relevance.

DESIGN

A total of 157 consecutive patients with sporadic asymptomatic PHPT were evaluated by measurement of serum and 24-hour urinary parameters and kidney ultrasound.

RESULTS

Urinary parameters were tested in the univariate analysis as continuous and categorical variables. Only hypercalciuria and hypomagnesuria were significantly associated with nephrolithiasis in the univariate and multivariate analysis adjusted for age, sex, body mass index, estimated glomerular filtration rate, parathyroid hormone, 25-hydroxyvitamin D, serum calcium, and urine volume (odds ratio, OR 2.14 [1.10-4.56]; P = .04; OR 3.06 [1.26-7.43]; P = .013, respectively). Hypomagnesuria remained associated with nephrolithiasis in the multivariate analysis (OR 6.09 [1.57-23.5], P = .009) even when the analysis was limited to patients without concomitant hypercalciuria. The urinary calcium/magnesium (Ca/Mg) ratio was also associated with nephrolithiasis (univariate OR 1.62 [1.27-2.08]; P = .001 and multivariate analysis OR 1.74 [1.25-2.42], P = .001). Hypomagnesuria and urinary Ca/Mg ratio had a better, but rather low, positive predictive value compared with hypercalciuria.

CONCLUSIONS

Hypomagnesuria and urinary Ca/Mg ratio are each associated with silent nephrolithiasis and have potential clinical utility as risk factors, besides hypercalciuria, for kidney stones in asymptomatic PHPT patients. The other urinary indices that have been commonly thought to be associated with kidney stones in PHPT are not supported by our results.

Design of drug-like hepsin inhibitors against prostate cancer and kidney stones

Hepsin, a transmembrane serine protease abundant in renal endothelial cells, is a promising therapeutic target against several cancers, particularly prostate cancer. It is involved in the release and polymerization of uromodulin in the urine, which plays a role in kidney stone formation. In this work, we design new potential hepsin inhibitors for high activity, improved specificity towards hepsin, and promising ADMET properties. The ligands were developed in silico through a novel hierarchical pipeline. This pipeline explicitly accounts for off-target binding to the related serine proteases matriptase and HGFA (human hepatocyte growth factor activator). We completed the pipeline incorporating ADMET properties of the candidate inhibitors into custom multi-objective optimization functions. The ligands designed show excellent prospects for targeting hepsin via the blood stream and the urine and thus enable key experimental studies. The computational pipeline proposed is remarkably cost-efficient and can be easily adapted for designing inhibitors against new drug targets.

Identification of Novel Human Serum Albumin (SA) Inhibitors from Scoparia Dulsis for Urolithiasis

Background::

Urolithiasis is the process of forming stones in the kidney, bladder, and/or urinary tract. It has been reported that kidney stones are the third most common disorder among urinary diseases. At present, surgical procedures and Extracorporeal Shock Wave Lithotripsy (ESWL) are commonly employed for the treatment of Urolithiasis. The major drawback of these procedures is the recurrence of stones.

Methods:

This study aimed to identify potential natural inhibitors against human Serum Albumin (SA) from the plant Scoparia Dulsis for Urolithiasis. As protein-ligand interactions play a key role in structure- based drug design, this study screened 26 compounds from Scoparia Dulsis and investigated their binding affinity against SA by using molecular docking. The three dimensional (3D) structure of SA was retrieved from Protein Data Bank (PDB) and docked with PubChem structures of 26 compounds using PyRX docking tool through Autodock Vina. Moreover, a 3D similarity search on the PubChem database was performed to find the analogs of best scored compound and docking studies were performed. Drug-likeness studies were made using Swiss ADME and Lipinski’s rule of five was performed for the compounds to evaluate their anti-urolithiatic activity.

Results:

The results showed that citrusin c (Eugenyl beta-D-glucopyranoside) exhibited best binding energy of -8.1 kcal/mol with SA followed by aphidicolin, apigenin, luteolin and scutellarein. Two compounds (PubChem CID 46186820, PubChem CID 21579141) analogous to citrusin c were selected based on the lowest binding energy.

Conclusion:

This study, therefore, reveals that these compounds could be promising candidates for further evaluation for Urolithiasis prevention or management.

Regulation on Calcium Oxalate Crystallization and Protection on HK-2 Cells of Tea Polysaccharides with Different Molecular Weights

The regulation on calcium oxalate (CaOx) crystallization and protective effect on human proximal tubular epithelial cells (HK-2) of four green tea polysaccharides (TPSs) with molecular weights of 10.88 (TPS0), 8.16 (TPS1), 4.82 (TPS2), and 2.3 kDa (TPS3) were comparatively studied. XRD, Fourier transform infrared spectroscopy, and scanning electron microscopy results revealed that TPS1, TPS2, and TPS3 can increase the percentage of the dihydrate crystalline phase in CaOx crystals and reduce the size of CaOx monohydrate crystals. TPSs increased the absolute value of the zeta potential of CaOx crystal and inhibited crystal nucleation and aggregation. The nucleation inhibition rates of TPS1, TPS2, and TPS3 to CaOx crystallization were 56.67%, 75.52%, and 52.92%, respectively, and their aggregation inhibition rates were 22.34%, 47.59%, and 21.59%, respectively. TPS preprotection can alleviate the oxidative damage of HK-2 cells caused by oxalate, increase cell viability, protect cell morphology, and reduce lactate dehydrogenase release and reactive oxygen species levels. The degraded TSPs, especially TPS2 with moderate molecular weight, may be used as a green drug to inhibit stone formation.

Relationship of endoscopic lesions of the renal papilla with type of renal stone and 24 h urine analysis

Background

Our purpose was to study the relationship of the 3 different types of endoscopic calcifications of the renal papilla (Randall’s plaque, intratubular calcification, papillary crater) with the type of stone and urine analysis.

Methods

This prospective study examined 41 patients (age range: 18 to 80 years) who received retrograde intrarenal surgery (RIRS) for renal lithiasis (mean stone size: 15.3 ± 7.2 mm). The renal papilla injuries were endoscopically classified as Randall’s plaque, intratubular calcification, or papillary crater. Calculi were classified as uric acid, calcium oxalate monohydrate (COM; papillary and cavity), calcium oxalate dihydrate (COD), or calcium phosphate (CP). A 24 h urine analysis of calcium, oxalate, citrate, phosphate, and pH was performed in all patients. The relationship of each type of papillary injury with type of stone and urine chemistry was determined. Fisher’s exact test and Student’s t-test were used to determine the significance of relationships, and a p value below 0.05 was considered significant.

Results

The most common injury was tubular calcification (78%), followed by Randall’s plaque (58%), and papillary crater (39%). There was no significant relationship of Randall’s plaque with type of stone. However, endoscopic intratubular calcification (p = 0.025) and papillary crater (p = 0.041) were more common in patients with COD and CP stones. There were also significant relationships of papillary crater with hypercalciuria (p = 0.036) and hyperoxaluria (p = 0.024), and of Randall’s plaque with hypocitraturia (p = 0.005).

Conclusions

There are certain specific relationships between the different types of papillary calcifications that were endoscopically detected with stone chemistry and urine analysis. COD and CP stones were associated with endoscopic tubular calcifications and papillary craters. Hypercalciuria was associated with tubular calcification, and hypocitraturia was associated with Randall’s plaque.

Oxidative stress and endoplasmic stress in calcium oxalate stone disease: the chicken or the egg?

Crystal modulators play a significant role in the formation of calcium oxalate stone disease. When renal cells are subjected to oxalate stress, the loss in cell integrity leads to exposure of multiple proteins that assist and/or inhibit crystal attachment and retention. Contact between oxalate and calcium oxalate with urothelium proves fatal to cells as a result of reactive oxygen species generation and onset of oxidative stress. Hence, as a therapeutic strategy it was hypothesised that supplementation of antioxidants would suffice. On the contrary to popular belief, the detection of oxalate induced endoplasmic reticulum mediated apoptosis proved the ineffectiveness of antioxidant therapy alone. Thus, the inadequacy of antioxidant supplementation in oxalate stress invoked the presence of an alternative pathway for the induction of kidney fibrosis in hyperoxaluric rats. In addition to settling this query, the link between oxidative stress and ER stress is not well understood, especially in urolithiasis.

A diagnostician's field guide to crystalline nephropathies

The kidney's role in filtration of blood and production of urine occurs via a combination of size and charge filtration at the glomerular basement membrane and resorption and excretion of molecules through a complex tubular system embedded within an ion gradient. This delicate system provides the kidney with a unique propensity for substrate saturation and crystal nucleation within the nephron. While crystalline nephropathies may seem exotic to the uninitiated, they are comprised of easily recognizable morphologies and generally lack complicated classification schemas. Additionally, unlike many intrinsic kidney diseases, crystalline nephropathies are often associated with systemic conditions that, upon further investigation, may elucidate critically important information. This review focuses on practical, diagnostically relevant and high yield information that can be utilized by diagnosticians. Our hope is to equip the reader who reviews renal tissue with a practical toolkit that they feel empowered to use when faced with crystal formation in a kidney biopsy, pre-implantation biopsy, or nephrectomy specimen. Short Abstract The kidney's role in filtration of blood and production of urine provides a unique propensity for substrate saturation and crystal nucleation within the nephron. While crystalline nephropathies may seem exotic to the uninitiated, they are comprised of easily recognizable morphologies and generally lack complicated classification. Additionally, crystalline nephropathies are often associated with systemic conditions that, upon further investigation, may elucidate critically important information.

Effect of moonseed vine (Triclisia gilletii Staner) on ethane-1,2-diol-induced urolithiasis and its renotoxicity in Wistar albino rats

Background

Moonseed vine (Triclisia gilletii Staner) in the family Menispermaceae is a robust creeper of up to 10 cm diameter, of the lowland dense rain forest. In Ondo State, located in the South Western part of Nigeria, the plant which is usually called Peshe is used for the management of renal-related ailments. The present study was undertaken to explore the efficacy of Triclisia gilletii, a folkloric therapy in the management of renal-related ailment.

Results

Phenols, steroids, saponins, and flavonoids are present in the TGME with a total antioxidant capacity of (30.36 ± 1.90 (mg GAE/g extract), LD50 greater than 5000 mg/kg b.w., and in vitro anti-nucleation activity (iC50 = 7.09 mg/mL). Calcium oxalate stone formation as a result of oxalate from ethane-1,2-diol was evident by hypocalcemia, and further electrolyte imbalance and decreased glomerular filtration rate. The enhanced oxidative milieu in hyperoxaluria was evident by increased MDA and PC and decreased enzymatic and non-enzymatic antioxidants as well as renal membrane enzymes activities. The renal histopathological study further emphasized oxalate-induced damage and the ameliorative potential of TGME.

Conclusion

The abnormal biochemical, redox electrolyte, membrane integrity, and histological alterations were attenuated by TGME which affirms its usage as nephroprotectant.

Aggregation of poorly crystalline and amorphous components of infectious urinary stones is mediated by bacterial lipopolysaccharide

Poorly crystalline and amorphous precipitate (PCaAP) is one of the components of the so-called infectious urinary stones, which are the result of the activity of urease-producing microorganisms, mainly from the Proteus species, in particular Proteus mirabilis. The main component of this kind of stones is crystalline struvite (MgNH4PO4∙6H2O). Bacteria can build into the structure of the urinary stone and, in this way, they are one of the components of the urinary stone. From these three components - PCaAP, struvite and Proteus mirabilis - PCaAP exhibits the greatest ability to aggregate. The present study focuses on the aggregation of PCaAP. In particular, an influence of lipopolysaccharide (LPS) isolated from Proteus mirabilis on aggregation of PCaAP is presented. An aggregation of PCaAP is characterized by cross-sectional area of aggregates and zeta potential. The results demonstrate that, in artificial urine, the influence of freely suspended LPS on aggregation of PCaAP depends on the concentrations of LPS. Small concentrations of freely suspended LPS enhance the aggregation of PCaAP compared to the control test. For high concentrations of freely suspended LPS the formation of aggregates of PCaAP is inhibited. LPS, which is not freely suspended, but covers polystyrene latex beads, has no such properties. The investigations provide evidence for the importance of biological regulation in the PCaAP aggregation process.

Current insights into the mechanisms and management of infection stones

Infection stones are complex aggregates of crystals amalgamated in an organic matrix that are strictly associated with urinary tract infections. The management of patients who form infection stones is challenging owing to the complexity of the calculi and high recurrence rates. The formation of infection stones is a multifactorial process that can be driven by urine chemistry, the urine microenvironment, the presence of modulator substances in urine, associations with bacteria, and the development of biofilms. Despite decades of investigation, the mechanisms of infection stone formation are still poorly understood. A mechanistic understanding of the formation and growth of infection stones - including the role of organics in the stone matrix, microorganisms, and biofilms in stone formation and their effect on stone characteristics - and the medical implications of these insights might be crucial for the development of improved treatments. Tools and approaches used in various disciplines (for example, engineering, chemistry, mineralogy, and microbiology) can be applied to further understand the microorganism-mineral interactions that lead to infection stone formation. Thus, the use of integrated multidisciplinary approaches is imperative to improve the diagnosis, prevention, and treatment of infection stones.

Pathological Mineralization: The Potential of Mineralomics

Pathological mineralization has been reported countless times in the literature and is a well-known phenomenon in the medical field for its connections to a wide range of diseases, including cancer, cardiovascular, and neurodegenerative diseases. The minerals involved in calcification, however, have not been directly studied as extensively as the organic components of each of the pathologies. These have been studied in isolation and, for most of them, physicochemical properties are hitherto not fully known. In a parallel development, materials science methods such as electron microscopy, spectroscopy, thermal analysis, and others have been used in biology mainly for the study of hard tissues and biomaterials and have only recently been incorporated in the study of other biological systems. This review connects a range of soft tissue diseases, including breast cancer, age-related macular degeneration, aortic valve stenosis, kidney stone diseases, and Fahr’s syndrome, all of which have been associated with mineralization processes. Furthermore, it describes how physicochemical material characterization methods have been used to provide new information on such pathologies. Here, we focus on diseases that are associated with calcium-composed minerals to discuss how understanding the properties of these minerals can provide new insights on their origins, considering that different conditions and biological features are required for each type of mineral to be formed. We show that mineralomics, or the study of the properties and roles of minerals, can provide information which will help to improve prevention methods against pathological mineral build-up, which in the cases of most of the diseases mentioned in this review, will ultimately lead to new prevention or treatment methods for the diseases. Importantly, this review aims to highlight that chemical composition alone cannot fully support conclusions drawn on the nature of these minerals.

Proteomics of Crystal-Cell Interactions: A Model for Kidney Stone Research

Nephrolithiasis/urolithiasis (i.e., kidney stone disease) remains a global public health problem with increasing incidence/prevalence. The most common chemical composition of kidney stones is calcium oxalate that initiates stone formation by crystallization, crystal growth, crystal aggregation, crystal–cell adhesion, and crystal invasion through extracellular matrix in renal interstitium. Among these processes, crystal–cell interactions (defined as “the phenomena in which the cell is altered by any means of effects from the crystal that adheres onto cellular surface or is internalized into the cell, accompanying with changes of the crystal, e.g., growth, adhesive capability, degradation, etc., induced by the cell”) are very important for crystal retention in the kidney. During the past 12 years, proteomics has been extensively applied to kidney stone research aiming for better understanding of the pathogenic mechanisms of kidney stone formation. This article provides an overview of the current knowledge in this field and summarizes the data obtained from all the studies that applied proteomics to the investigations of crystal–cell interactions that subsequently led to functional studies to address the significant impact or functional roles of the expression proteomics data in the pathogenesis of kidney stone disease.

miRNA-34a inhibits cell adhesion by targeting CD44 in human renal epithelial cells: implications for renal stone disease

Nephrolithiasis is a very common disease in which cell-crystal adhesion is an essential mechanism for kidney stone formation. This study has explored the anti-adhesion function of the microRNA, miR-34a, by targeting CD44, a cell surface receptor, in human renal epithelial (HK-2) cells. The expression of CD44 was monitored by qPCR and western blot. A luciferase assay validated the target of miR-34a in CD44 3' UTR. Immunofluorescence staining under confocal microscopy was used to detect the cell-crystal adhesion effects in vitro. Pizzolato staining was performed to examine the adhesion role of miR-34a in vivo. In HK-2 cells, miR-34a was down-regulated and CD44 was up-regulated when exposed to calcium oxalate monohydrate crystals. Moreover, miR-34a negatively regulated the expression of CD44. According to the luciferase report assay, miR-34a direct targeted a binding site in the CD44 3'UTR. In vitro experiments, miR-34a overexpression inhibited CD44 expression and cell-crystals adhesion; whereas CD44 overexpression showed reversed results. Furthermore, miR-34a suppressed cell-crystals adhesion and stone formation in vivo. These findings indicate that miR-34a targets CD44 in HK-2 cells and inhibits cell-crystal adhesion both in vitro and in vivo. Based on these results, miR-34a may be a potential therapeutic target for renal stone disease.

Calcium citrate: from biochemistry and physiology to clinical applications

Adequate daily calcium intake should normally be achieved by dietary sources. Since low calcium diets are quite common in subjects that do not reach the recommended intake and particularly those at risk of fractures, calcium supplements may become necessary. Different forms of calcium salts are available, but products containing calcium citrate and calcium carbonate complexes are the most frequently used. Although only limited evidence on the efficacy and long-term safety of calcium citrate is available, these supplements may represent a valuable product for the management of different chronic pathological conditions. The aim of this review was to evaluate the current and potential clinical applications of calcium citrate. In particular, we focused on the use of calcium citrate supplementation in subjects with osteoporosis or in bariatric patients. Other pathological conditions that could benefit calcium citrate supplementation may include achloridria, chronic hypoparathyroidism and hypocitraturic subjects with moderate/high risk of nephrolithiasis. Indeed, citrate salts are widely used in the treatment of nephrolithiasis, since they have shown an inhibitory effect on kidney stone formation and recurrence.

A Short Review on the Relationships Between Nephrolithiasis and Myocardial Infarction

The interaction between organs is a crucial part of modern medicine. As a very prerequisite to manage a disease, practitioners should have a full awareness of the related organs. Kidney and heart are two vital organs that are closely interconnected in various fields. These two organs have a lot of common risk factors for making a person unhealthy; therefore, if you prevent the disease in one of them, the other's morbidity might be alleviated as well. Among them, nephrolithiasis and myocardial infarction (MI) have more risk factors in common, and both could be fatal. Also, these two diseases are important regarding the prevalence, incidence, and burden of disease. Some studies confirm the relationship between MI and nephrolithiasis; however, further researches are needed to discover the exact direction of their relationship. The present review aims to explain the mechanism of MI and nephrolithiasis; clarify the relationship between these two disease based on physiological, pathological, and clinical studies; and propose some solutions for the prevention and treatment of such diseases.