Understanding formation processes of calcareous nephrolithiasis in renal interstitium and tubule lumen.

Kidney stone, one of the oldest known diseases, has plagued humans for centuries, consistently imposing a heavy burden on patients and healthcare systems worldwide due to their high incidence and recurrence rates. Advancements in endoscopy, imaging, genetics, molecular biology and bioinformatics have led to a deeper and more comprehensive understanding of the mechanism behind nephrolithiasis. Kidney stone formation is a complex, multi-step and long-term process involving the transformation of stone-forming salts from free ions into asymptomatic or symptomatic stones influenced by physical, chemical and biological factors. Among the various types of kidney stones observed in clinical practice, calcareous nephrolithiasis is currently the most common and exhibits the most intricate formation mechanism. Extensive research suggests that calcareous nephrolithiasis primarily originates from interstitial subepithelial calcified plaques and/or calcified blockages in the openings of collecting ducts. These calcified plaques and blockages eventually come into contact with urine in the renal pelvis, serving as a nidus for crystal formation and subsequent stone growth. Both pathways of stone formation share similar mechanisms, such as the drive of abnormal urine composition, involvement of oxidative stress and inflammation, and an imbalance of stone inhibitors and promoters. However, they also possess unique characteristics. Hence, this review aims to provide detailed description and present recent discoveries regarding the formation processes of calcareous nephrolithiasis from two distinct birthplaces: renal interstitium and tubule lumen.

FKBP5 deficiency attenuates calcium oxalate kidney stone formation by suppressing cell-crystal adhesion, apoptosis and macrophage M1 polarization via inhibition of NF-κB signaling.

Surgical crushing of stones alone has not addressed the increasing prevalence of kidney stones. A promising strategy is to tackle the kidney damage and crystal aggregation inherent in kidney stones with the appropriate therapeutic target. FKBP prolyl isomerase 5 (FKBP5) is a potential predictor of kidney injury, but its status in calcium oxalate (CaOx) kidney stones is not clear. This study attempted to elucidate the role and mechanism of FKBP5 in CaOx kidney stones. Lentivirus and adeno-associated virus were used to control FKBP5 expression in a CaOx kidney stone model. Transcriptomic sequencing and immunological assays were used to analyze the mechanism of FKBP5 deficiency in CaOx kidney stones. The results showed that FKBP5 deficiency reduced renal tubular epithelial cells (RTEC) apoptosis and promoted cell proliferation by downregulating BOK expression. It also attenuated cell-crystal adhesion by downregulating the expression of CDH4. In addition, it inhibited M1 polarization and chemotaxis of macrophages by suppressing CXCL10 expression in RTEC. Moreover, the above therapeutic effects were exerted by inhibiting the activation of NF-κB signaling. Finally, in vivo experiments showed that FKBP5 deficiency attenuated stone aggregation and kidney injury in mice. In conclusion, this study reveals that FKBP5 deficiency attenuates cell-crystal adhesion, reduces apoptosis, promotes cell proliferation, and inhibits macrophage M1 polarization and chemotaxis by inhibiting NF-κB signaling. This provides a potential therapeutic target for CaOx kidney stones.

Melatonin exerts a protective effect in ameliorating nephrolithiasis via targeting AMPK/PINK1-Parkin mediated mitophagy and inhibiting ferroptosis in vivo and in vitro.

Hyperoxaluria-induced damage to renal tubular epithelial cells (RTECs) is considered the most significant contributor to kidney stone formation. However, the precise regulatory mechanism underlying this damage, particularly its association with mitophagy dysfunction, remains unclear. Additionally, effective preventive medications for kidney stones are lacking. Melatonin, a hormone secreted by the pituitary gland that primarily regulates circadian rhythm, has been found to modulate mitophagy in recent research. Therefore, this investigation aims to examine the impact of melatonin on mitophagy and cellular impairment in the formation of kidney stone. The results of this study reveal that melatonin can alleviate the formation of kidney stones and reduce oxalate-induced renal injuries. In the RTECs of kidney stone model, mitophagy was found to be impaired, leading to increased oxidative stress, inflammation, and ferroptosis both in vivo and in vitro. Melatonin was shown to have a restorative potential in enhancing PINK1-Parkin-regulated mitophagy through AMPK phosphorylation, reducing excessive ROS release and inhibiting oxidative stress, inflammation and ferroptosis. Further experiments demonstrated that the protective effect of melatonin was diminished by PINK1 knockdown and AMPK pathway blockade. This study is the first to reveal the interplay between mitophagy and ferroptosis in kidney stone models and establish the protective role of melatonin in restoring mitophagy to inhibit ferroptosis.

An overview of global research landscape in etiology of urolithiasis based on bibliometric analysis.

The high incidence, recurrence and treatment costs of urolithiasis have a serious impact on patients and society. For a long time, countless scholars have been working tirelessly on studies related to the etiology of urolithiasis. A comprehensive understanding of the current status will be beneficial to the development of this field. We collected all literature about the etiology of urolithiasis from 1990 to 2022 using the Web of Science (WoS) database. VOSviewer, Bibliometrix and CiteSpace software were used to quantitatively analyze and visualize the data as well. The query identified 3177 articles for final analysis, of which related to the etiology of urolithiasis. The annual number of publications related to urolithiasis research has steadily increased during the latest decade. United States (1106) and China (449) contributed the most publications. University of Chicago (92) and Indiana University (86) have the highest number of publications. Urolithiasis and Journal of Urology have published the most articles in the field. Coe FL is the most productive author (63 articles), whose articles have obtained the most citations in all (4141 times). The keyword, such as hypercalciuria, hyperoxaluria, citrate, oxidative stress, inflammation, Randall's plaque, are the most attractive targets for the researchers. Our review provides a global landscape of studies related to the etiology of urolithiasis, which can serve as a reference for future studies in this field.

Clinical features and prognostic factors in patients diagnosed with lymphovascular invasion of testicular germ-cell tumors: Analysis based on the SEER database.

Background: Lymphovascular invasion (LVI) is a high-risk factor for testicular germ-cell tumors (TGCT), but a prognostic model for TGCT-LVI patients is lacking. This study aimed to develop a nomogram for predicting the overall survival (OS) of TGCT-LVI patients. Methods: A complete cohort of 3288 eligible TGCG-LVI patients (training cohort, 2300 cases; validation cohort, 988 cases) were obtained from the Surveillance, Epidemiology, and End Results database. Variables screened by multivariate Cox regression analysis were used to construct a nomogram, which was subsequently evaluated using the consistency index (C-index), time-dependent receiver operating characteristic curve (ROC), and calibration plots. The advantages and disadvantages of the American Joint Committee on Cancer (AJCC) staging system and the nomogram were assessed by integrated discrimination improvement (IDI) and net reclassification improvement (NRI). Decision-analysis curve (DCA) was used to measure the net clinical benefit of the nomogram versus the AJCC staging system. Finally, Kaplan-Meier curves were used to evaluate the ability to identify different risk groups between the traditional AJCC staging system and the new risk-stratification system built on the nomogram. Results: Nine variables were screened by multivariate Cox regression analysis to construct the nomogram. The C-index (training cohort, 0.821; validation cohort, 0.819) and time-dependent ROC of 3-, 5-, and 9-year OS between the two cohorts suggested that the nomogram had good discriminatory ability. Calibration curves showed good consistency of the nomogram. The NRI values of 3-, 5-, and 9-year OS were 0.308, 0.274, and 0.295, respectively, and the corresponding values for the validation cohort were 0.093, 0.093, and 0.099, respectively (P<0.01). Additionally, the nomogram had more net clinical benefit as shown by the DCA curves, and the new risk-stratification system provided better differentiation than the AJCC staging system. Conclusions: A prognostic nomogram and new risk-stratification system were developed and validated to assist clinicians in assessing TGCT-LVI patients.

Protective efficacy of Schizandrin B on ameliorating nephrolithiasis via regulating GSK3ß/Nrf2 signaling-mediated ferroptosis in vivo and in vitro.

Schizandrin B (SchB) protects against oxidative, inflammatory, and ferroptotic injury. Oxidative stress and inflammation are indispensably involved in nephrolithiasis and ferroptosis also plays an important role in stone formation. It is unclear whether SchB can ameliorate nephrolithiasis; its underlying mechanism is also unknown. First, we employed bioinformatics to investigate the mechanisms of nephrolithiasis. To evaluate the efficacy of SchB, HK-2 cell models of oxalate-induced damage, Erastin-induced ferroptosis, and the Sprague Dawley rat model of Ethylene Glycol-induced nephrolithiasis were established. Then, Nrf2 siRNA and GSK3ß overexpression plasmids were transfected into HK-2 cells to elucidate the role of SchB in regulating oxidative stress-mediated ferroptosis. In our study, oxidative stress and inflammation were strongly associated with nephrolithiasis. Administration of SchB attenuated the cell viability, dysfunctional mitochondria, oxidative stress and inflammatory response in vitro and alleviated renal injury and crystal deposition in vivo. SchB treatment also reduced the levels of cellular Fe2+ accumulation, lipid peroxidation and MDA, and regulated ferroptosis-related proteins, including XCT, GPX4, FTH1 and CD71, in Erastin-induced or oxalate-induced HK-2 cells. Mechanistically, SchB facilitated Nrf2 nuclear translocation, and silencing Nrf2 or overexpressing GSK3ß worsened oxalate-induced oxidative injury and abolished the beneficial effect of SchB against ferroptosis in vitro. To summarize, SchB could alleviate nephrolithiasis by positively regulating GSK3ß/Nrf2 signaling-mediated ferroptosis.

Anisotropic Wettability of Bioinspired Surface Characterized by Friction Force.

Bioinspired surfaces with special wettabilities attract increasing attention due to their extensive applications in many fields. However, the characterizations of surface wettability by contact angle (CA) and sliding angle (SA) have clear drawbacks. Here, by using an array of triangular micropillars (ATM) prepared by soft lithography, the merits of measuring the friction force of a water droplet on ATM over measurements of CA and SA in characterizing the surface wettability are demonstrated. The CA and SA measurements show ignorable differences in the wettabilities of ATM in opposite directions (1.13%) and that with different periodic parameters under the elongation ranging from 0 to 70%. In contrast, the friction measurement reveals a difference of > 10% in opposite directions. Moreover, the friction force shows a strong dependence on the periodic parameters which is regulated by mechanical stretching. Increasing the elongation from 0 to 50% increases the static and kinetic friction force up to 23.0% and 22.9%, respectively. Moreover, the stick-slip pattern during kinetic friction can reveal the periodic features of the measured surface. The friction force measurement is a sensitive technique that could find applications in the characterization of surface wettabilities.

Oxalate induces the ossification of RTECs by activating the JAK2/STAT3 signaling pathway and participates in the formation of kidney stones.

BACKGROUND: The ossification of renal tubular epithelial cells (RTECs) plays an important initial role in the formation of kidney stones, but its specific mechanism is still unclear. The JAK2/STAT3 signaling pathway is important for bone cell differentiation. Accordingly, we explored the role and mechanism of the JAK2/STAT3 signaling pathway in the ossification of RTECs. METHODS: We used oxalate or ethylene glycol to construct kidney stone models in vitro and in vivo, and investigated the expression of osteogenic-specific genes, osteogenesis ability, and JAK2/STAT3 signaling in the kidney stone models by western blotting, qRT-PCR, immunofluorescence, and immunohistochemistry. Then, genetic engineering or drugs were used to inhibit the expression or activation of JAK2, and the expression of osteogenic-specific genes and the osteogenic ability of the RTECs were determined again. RESULTS: In the in vitro and in vivo kidney stone models, the expression of osteogenic specific genes in the RTECs was significantly upregulated, the osteogenic capacity was significantly increased, and the expression of p-JAK2 (phospho-JAK2) and p-STAT3 (phospho-STAT3) was significantly increased. When the expression or activation of JAK2 was inhibited, the ossification of RTECs and the formation of kidney stones was reversed. CONCLUSIONS: During the formation of kidney stones, RTECs undergo obvious ossification, and the JAK2/STAT3 signaling pathway plays a key positive regulatory role in this process.

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.

Role of ferroptosis induced by a high concentration of calcium oxalate in the formation and development of urolithiasis.

Ferroptosis is an iron­dependent lipid peroxidation process. Although the involvement of ferroptosis in kidney diseases has recently been reported, the association between ferroptosis and urolithiasis remains unclear. The present study examined the effects of ferroptosis on calcium oxalate (CaOx) crystal­induced renal tubular epithelial cell injury in vivo and in vitro. First, renal tubular epithelial cells were exposed to various concentrations of CaOx. By measuring cell viability, Fe2+ levels, lipid peroxidation levels and the levels of ferroptosis­related proteins, it was identified that the relative expression of the ferroptosis agonist proteins, p53, long­chain acyl­CoA synthetases (ACSL4), transferrin (TF) and transferrin receptor (TRC), increased, while the relative expression of the ferroptosis inhibitory proteins, solute carrier family 7 member 11 (SLC7A11, XCT) and glutathione peroxidase 4 (GPX4), decreased significantly. Furthermore, the levels of Fe2+ and lipid peroxidation gradually increased, while cell viability significantly decreased. From these results, it was noted that the extent of CaOx­induced ferroptosis activation and cell injury was dependent on the CaOx concentration. To further investigate the association between ferroptosis and renal tubular epithelial cell injury, the ferroptosis agonist, erastin, and the ferroptosis inhibitor, ferrostatin­1, were used to regulate the degree of ferroptosis at the same CaOx concentration in in vivo and in vitro experiments. CaOx­induced ferroptosis and damage to renal tubular epithelial cells and renal tissue were investigated. Finally, it was identified that through the regulation of ferroptosis levels, renal tubular epithelial cell injury increased significantly when the ferroptosis level increased, and vice versa. On the whole, the present results indicated that ferroptosis is essential for renal tubular epithelial cell injury induced by CaOx crystals. This finding is highly significant and promotes the further investigation of the association between ferroptosis and urolithiasis.

Melatonin inhibits oxalate-induced endoplasmic reticulum stress and apoptosis in HK-2 cells by activating the AMPK pathway.

Background: Deposition of various crystal and organic substances in the kidney can lead to kidney stone formation. Melatonin is an effective endogenous antioxidant that can prevent crystalluria and kidney damage due to crystal formation and aggregation. In this study, we investigated the mechanism by which melatonin inhibits endoplasmic reticulum (ER) stress and apoptosis. Methods: We treated HK-2 cells with oxalate to establish an in vitro kidney stone model, and treated these cells with different concentrations of melatonin (0, 5, 10, 20 µmol/L) and the AMP-activated protein kinase (AMPK) inhibitor Compound C. We measured levels of stress response markers including reactive oxygen species (ROS), lactate dehydrogenase (LDH), glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), and factors in the stress response pathway, such as ATF6, GRP78, DDIT3, PERK, p-PERK, IRE1, p-IRE1, XBP1s, AMPK, and p-AMPK, using real time-PCR, western blot, and immunofluorescence analyzes. We measured mitochondrial membrane potential and caspases-3 activity using the CCK8, enzyme-linked immunosorbent, and flow cytometry assays to assess HK-2 cell viability and apoptosis. Results: Melatonin improved the total antioxidant capacity (T-AOC) of the HK-2 cells, as evidenced by the dose-dependent reduction in apoptosis, ROS levels, and protein expression of ATF6, GRP78, DDIT3, p-PERK, p-IRE1, XBP1s, caspase-12, cleaved caspase-3 and cleaved caspase-9. Addition of the AMPK inhibitor, Compound C, partially reversed the protective effect of melatonin. Conclusion: Our study revealed that the protective effects of melatonin on oxalate-induced ER stress and apoptosis is partly dependent on AMPK activation in HK-2 cells. These findings provide insight into the prevention and treatment of kidney stones.

Effect of STK17A on the sensitivity of ovarian cancer cells to paclitaxel and carboplatin.

Ovarian cancer is the main cause of cancer mortality in gynecological tumors around the world. Drug resistance to a variety of chemotherapeutics continue to be one of the main causes of treatment failure. In a previous study, it was demonstrated that STK17A, a proapoptotic gene, was significantly downregulated in acquired resistance phenotypes of colon cancer cells that are resistant to oxaliplatin and 5-fluorouracil. Therefore in the present study, the association between STK17A expression and ovarian cancer with initial drug resistance was investigated and the influence of STK17 on ovarian cancer cell proliferation and doubling time. In the present study, ovarian cancer cell lines that express low levels of STK17A were established by targeting STK17A with specific siRNA. In addition, up-regulation of STK17A was established in ovarian cells by pCDNA3flu/STK17A. The sensitivity of the transfected cells and controls to paclitaxel, carboplatin was examined by MTT assay, and the levels of proliferation and apoptosis were analyzed by flow cytometry. In the cells that were transfected with siRNA resulting in reduced expression of STK17A, the 50% inhibitory concentration (IC50) of the chemotherapy drugs paclitaxel and carboplatin was increased compared with control cells (P<0.05). By contrast, in the cells that overexpressed STK17A following treatment with pCDNA3flu/STK17A, the IC50 of the chemotherapy drugs reduced in each case, and was significantly lower compared with the control (P<0.05). There was a variable susceptibility to carboplatin and paclitaxel resulting from altering the levels of STK17A expression in ovarian cancer cell lines. The growth of STK17A/siRNA transfected cells was promoted compared with that of the control cells and accordingly their cell doubling time was shortened.