Gastrin‐releasing peptide receptor gene silencing inhibits the development of the epithelial–mesenchymal transition and formation of a calcium oxalate crystal in renal tubular epithelial cells in mice with kidney stones via the PI3K/Akt signaling pathway

Machine learning and 4D-LFQ quantitative proteomic analysis explore the molecular mechanism of kidney stone formation

Background

Nephrolithiasis, a common and chronic urological condition, exerts significant pressure on both the general public and society as a whole. The precise mechanisms of nephrolith formation remain inadequately comprehended. Nevertheless, the utilization of proteomics methods has not been employed to examine the development of renal calculi in order to efficiently hinder and manage the creation and reappearance of nephrolith. Nowadays, with the rapid development of proteomics techniques, more efficient and more accurate proteomics technique is utilized to uncover the mechanisms underlying diseases. The objective of this study was to investigate the possible alterations of HK-2 cells when exposed to varying amounts of calcium oxalate (CaOx). The aim was to understand the precise development of stone formation and recurrence, in order to find effective preventive and treatment methods.

Methods

To provide a complete view of the proteins involved in the development of nephrolithiasis, we utilized an innovative proteomics method called 4D-LFQ proteomic quantitative techniques. HK-2 cells were selected as our experimental subjects. Three groups (n = 3) of HK-2 cells were treated with intervention solutions containing 0 (negative control, NC), 1 mM, and 2 mM CaOx, respectively. For the proteins that showed differential expression, various analyses were conducted including examination of Gene Ontology (GO), Clusters of Orthologous Groups of proteins (KOG), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, enrichment analysis of protein domains, and hierarchical clustering analysis. The STRING database was used to identify the interaction network of the chosen proteins. Candidate proteins were validated using parallel reaction monitoring (PRM) in the end.

Results

All three groups verified the repeatability of samples. According to the results of 4D-LFQ proteomic quantitative analysis, there were 120, 262, and 81 differentially expressed proteins (DEPs) in the 1 mM-VS-NC, 2 mM-VS-NC, and 2 mM-VS-1mM conditions, respectively. According to GO annotation, the functional enrichment analysis indicates that the differentially expressed proteins (DEPs) were notably enriched in promoting cell migration and the extracellular matrix, among other functions. Analysis of enrichment, based on the KEGG pathway, revealed significant enrichment of DEPs in complement and coagulation cascades, as well as in ECM-receptor (extracellular matrix-receptor) interaction and other related pathways. 14 DEPs of great interest were selected as candidate proteins, including FN1, TFRC, ITGA3, FBN1, HYOU1, SPP1, HSPA5, COL6A1, MANF, HIP1R, JUP, AXL, CTNNB1 and DSG2.The data from PRM demonstrated the variation trend of 14 DEPs was identical as 4D-LFQ proteomic quantitative analysis.

Conclusion

Proteomics studies of CaOx-induced HK-2 cells using 4D-LFQ proteomic quantitative analysis and PRM may help to provide crucial potential target proteins and signaling pathways for elucidating the mechanism of nephrolithiasis and better treating nephrolithiasis.

Genetic susceptibility of urolithiasis: comprehensive results from genome-wide analysis

BACKGROUND

The pathogenesis of urolithiasis is multi-factorial and genetic factors have been shown to play a significant role in the development of urolithiasis. We tried to apply genome-wide Mendelian randomization (MR) analysis and figure out reliable gene susceptibility of urolithiasis from the largest samples to date in two independent genome-wide association studies (GWAS) database of European ancestry.

METHODS

We extracted summary statistics of expression quantitative trait locus (eQTL) from eQTLGen consortium. Urolithiasis phenotype information was obtained from both FinnGen Biobank and UK Biobank. Multiple two-sample MR analysis with a Bonferroni-corrected P threshold (P < 2.5e-06) was conducted. The primary endpoint was the causal effect calculated by random-effect inverse variance weighted (IVW) method. Sensitivity analysis, volcano plots, scatter plots, and regional plots were also performed and visualized.

RESULTS

After multiple MR tests between 19942 eQTLs and urolithiasis phenotype from both cohorts, 30 common eQTLs with consistent effect size direction were found to be causally associated with urolithiasis risk. Finally only one gene (LMAN2) was simultaneously identified among all top significant eQTLs from both FinnGen Biobank (beta = 0.6758, se = 0.0327, P = 6.775e-95) and UK Biobank (beta = 0.0044, se = 0.0009, P = 2.417e-06). We also found that LMAN2 was with the largest beta effect size on urolithiasis phenotype from the two cohorts.

CONCLUSION

We for the first time implemented genome-wide MR analysis to investigate the genetic susceptibility of urolithiasis in general population of European ancestry. Our results provided novel insights into common genetic variants of urinary stone disease, which was of great help to subsequent researches.

Genetic and pharmacological inhibition of GRPR protects against acute kidney injury via attenuating renal inflammation and necroptosis

Gastrin-releasing peptide (GRP) binds to its receptor (GRP receptor [GRPR]) to regulate multiple biological processes, but the function of GRP/GRPR axis in acute kidney injury (AKI) remains unknown. In the present study, GRPR is highly expressed by tubular epithelial cells (TECs) in patients or mice with AKI, while histone deacetylase 8 may lead to the transcriptional activation of GRPR. Functionally, we uncovered that GRPR was pathogenic in AKI, as genetic deletion of GRPR was able to protect mice from cisplatin- and ischemia-induced AKI. This was further confirmed by specifically deleting the GRPR gene from TECs in GRPRFlox/Flox//KspCre mice. Mechanistically, we uncovered that GRPR was able to interact with Toll-like receptor 4 to activate STAT1 that bound the promoter of MLKL and CCL2 to induce TEC necroptosis, necroinflammation, and macrophages recruitment. This was further confirmed by overexpressing STAT1 to restore renal injury in GRPRFlox/Flox/KspCre mice. Concurrently, STAT1 induced GRP synthesis to enforce the GRP/GRPR/STAT1 positive feedback loop. Importantly, targeting GRPR by lentivirus-packaged small hairpin RNA or by treatment with a novel GRPR antagonist RH-1402 was able to inhibit cisplatin-induced AKI. In conclusion, GRPR is pathogenic in AKI and mediates AKI via the STAT1-dependent mechanism. Thus, targeting GRPR may be a novel therapeutic strategy for AKI.

Novel insight on GRP/GRPR axis in diseases

The gastrin-releasing peptide receptor (GRPR), a member of the G protein-coupled receptors (GPCRs), binds to ligands such as gastrin-releasing peptide (GRP) and plays a variety of biological roles. GRP/GRPR signalling is involved in the pathophysiological processes of many diseases, including inflammatory diseases, cardiovascular diseases, neurological diseases, and various cancers. In the immune system, the unique function of GRP/GRPR in neutrophil chemotaxis suggests that GRPR can be directly stimulated through GRP-mediated neutrophils to activate selective signalling pathways, such as PI3K, PKC, and MAPK, and participate in the occurrence and development of inflammation-related diseases. In the cardiovascular system, GRP increases intercellular adhesion molecule 1 (ICAM-1) and induces vascular cell adhesion molecule-1 (VCAM-1). GRP activates ERK1/2, MAPK, and AKT, leading to cardiovascular diseases, including myocardial infarction. Central nervous system signal transduction mediated by the GRP/GRPR axis plays a vital role in emotional responses, social interaction, and memory. The GRP/GRPR axis is elevated in various cancers, including lung, cervical, colorectal, renal cell, and head and neck squamous cell carcinomas. GRP is a mitogen in a variety of tumour cell lines. Its precursor, pro-gastrin-releasing peptide (ProGRP), may play an important role as an emerging tumour marker in early tumour diagnosis. GPCRs serve as therapeutic targets for drug development, but their function in each disease remains unclear, and their involvement in disease progression has not been well explored or summarised. This review lays out the above mentioned pathophysiological processes based on previous research conclusions. The GRP/GRPR axis may be a potential target for treating multiple diseases, and the study of this signalling axis is particularly important.

Mechanism of miRNA-141-3p in Calcium Oxalate-Induced Renal Tubular Epithelial Cell Injury via NLRP3-Mediated Pyroptosis

BACKGROUND/AIMS

Renal calculi represent a prevalent disorder associated with mineral deposition in renal calyces and the pelvis. Aberrant microRNA (miRNA) expression is implicated in renal injury. This study investigated the mechanism of miR-141-3p in calcium oxalate (CaOx) crystal-induced renal tubular epithelial cell (RTEC) injury.

METHODS

Human RTECs HK-2 cells were treated with CaOx crystals to induce RTEC injury. Cell viability was evaluated using Cell Counting Kit-8 assay, and apoptosis was measured using flow cytometry. The contents of lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), interleukin (IL)-1β, and IL-18 were measured using enzyme-linked immunosorbent assay kits. The expressions of NLRP3, cleaved caspase-1, and GSDMD-N were detected using Western blot. miR-141-3p and NLRP3 expressions were determined using reverse transcription quantitative polymerase chain reaction. The binding of miR-141-3p and NLRP3 was validated using a dual-luciferase assay. The role of NLRP3 in the protection of miR-141-3p on RTEC injury was verified using functional rescue experiments.

RESULTS

CaOx crystals induced RTEC injury, manifested as attenuated cell viability, enhanced apoptosis, elevated intracellular LDH and MDA levels, and decreased SOD level. Pyroptosis of RTECs was enhanced by CaOx crystal induction, evidenced by elevated expressions of cleaved caspase-1, GSDMD-N, IL-1β, and IL-18. miR-141-3p expression was reduced in CaOx crystal-induced RTECs. miR-141-3p overexpression alleviated CaOx crystal-induced RTEC injury and suppressed pyroptosis of RTECs. miR-141-3p bound to NLRP3 and thereby repressed NLRP3 expression. NLRP3 overexpression reversed the protective effect of miR-141-3p overexpression on RTECs.

CONCLUSION

miR-141-3p repressed NLRP3-mediated pyroptosis by suppressing NLRP3 expression, thus protecting CaOx crystal-induced RTEC injury.

Construction and Analysis of Immune Infiltration-Related ceRNA Network for Kidney Stones

Purpose: Kidney stones is a common medical issue that mediates kidney injury and even kidney function loss. However, the exact pathogenesis still remains unclear. This study aimed to explore the potential competing endogenous RNA (ceRNA)-related pathogenesis of kidney stones and identify the corresponding immune infiltration signature. Methods: One mRNA and one long non-coding RNA (lncRNA) microarray dataset was obtained from the GEO database. Subsequently, we compared differentially expressed mRNAs (DE-mRNAs) and lncRNAs between Randall's plaques in patients with calcium oxalate (CaOx) stones and controls with normal papillary tissues. lncRNA-targeted miRNAs and miRNA-mRNA pairs were predicted using the online databases. lncRNA-related DE-mRNAs were identified using the Venn method, and GO and KEGG enrichment analyses were subsequently performed. The immune-related lncRNA-miRNA-mRNA ceRNA network was developed. The CIBERSORT algorithm was used to estimate the rate of immune cell infiltration in Randall's plaques. The ceRNA network and immune infiltration were validated in the glyoxylate-induced hyperoxaluric mouse model and oxalate-treated HK-2 cells. Results: We identified 2,340 DE-mRNAs and 929 DE-lncRNAs between Randall's plaques in patients with CaOx stones and controls with normal papillary tissues. lncRNA-related DE-mRNAs were significantly enriched in extracellular matrix organization and collagen-containing extracellular matrix, which were associated with kidney interstitial fibrosis. The immune-related ceRNA network included 10 lncRNAs, 23 miRNAs, and 20 mRNAs. Moreover, we found that M2 macrophages and resting mast cells were differentially expressed between Randall's plaques and normal tissues. Throughout kidney stone development, kidney tubular injury, crystal deposition, collagen fiber deposition, TGF-β expression, infiltration of M1 macrophages, and activation of mast cells were more frequent in glyoxylate-induced hyperoxaluric mice compared with control mice. Nevertheless, M2 macrophage infiltration increased in early stages (day 6) and decreased as kidney stones progressed (day 12). Furthermore, treatment with 0.25 and 0.5 mM of oxalate for 48 h significantly upregulated NEAT1, PVT1, CCL7, and ROBO2 expression levels and downregulated hsa-miR-23b-3p, hsa-miR-429, and hsa-miR-139-5p expression levels in the HK-2 cell line in a dose-dependent manner. Conclusion: We found that significant expressions of ceRNAs (NEAT1, PVT1, hsa-miR-23b-3p, hsa-miR-429, hsa-miR-139-5p, CCL7, and ROBO2) and infiltrating immune cells (macrophages and mast cells) may be involved in kidney stone pathogenesis. These findings provide novel potential therapeutic targets for kidney stones.

Oral Hydrogen-Rich Water Alleviates Oxalate-Induced Kidney Injury by Suppressing Oxidative Stress, Inflammation, and Fibrosis

Objective: To explore the theraputic effects and potential mechanisms of hydrogen-rich water (HRW) against oxalate-induced kidney injury.

Methods: The mouse model of Calcium oxalate (CaOx) crystallization was established by feeding a soluble oxalate diet. Crystal deposition, tubular injury, fibrosis and reactive oxygen species (ROS) production in kidneys were examined by histology. Serum indexes of renal injury, inflammation and oxidative stress were detected by commercial kits. RNA sequencing (RNA-seq) was performed to screen potential pathways and the expressions of key molecules in these pathways were determined by western blotting and immunohistochemistry.

Results: Crystal deposition, tubular injury, fibrosis and increased ROS production in kidneys of mice induced by oxalate diet were improved with HRW administration. The indexes of renal injury, inflammation and oxidative stress in serum of mice were upregulated by oxalate diet, which were reduced by HRW. A total of 3,566 differential genes were screened by RNA-seq and these genes were analyzed by pathway enrichment and PI3K/AKT, NF-κB, and TGF-β pathways were selected for further verification. The expressions of molecules related to PI3K-AKT pathway (PI3K, AKT, and p-AKT), NF-κB pathway (NF-κB p65, p- NF-κB p65, NLRP3, and IL-1β) and TGF-β pathway (TGF-β, TGF-βRI, TGF-βRII, p-Smad2, and p-Smad3) in renal tissues were increased by oxalate diet, which were reduced by HRW administration.

Conclusion: HRW may alleviate oxalate-induced kidney injury with its anti-oxidative, anti-inflammatory and anti-fibrotic effects via inhibiting PI3K/AKT, NF-κB, and TGF-β pathways.

Vitexin exerts protective effects against calcium oxalate crystal-induced kidney pyroptosis in vivo and in vitro

BACKGROUND

Nephrolithiasis is a common urinary disease with a high recurrence rate of secondary stone formation. Several mechanisms are involved in the onset and recurrence of nephrolithiasis, e.g., oxidative stress, inflammation, apoptosis, and epithelial-mesenchymal transition (EMT). Vitexin, a flavonoid monomer derived from medicinal plants that exert many biological effects including anti-inflammatory and anticancer effects, has not been investigated in nephrolithiasis studies. Moreover, pyroptosis, a form of programmed cell death resulting from inflammasome-associated caspase activation, has not been studied in mice with nephrolithiasis.

PURPOSE

We aimed to investigate the protective effect and underlying mechanisms of vitexin in nephrolithiasis, and the related role of pyroptosis in vivo and in vitro.

METHODS

Mouse models of nephrolithiasis were established via intraperitoneal injection of glyoxylate, and cell models of tubular epithelial cells and macrophages were established using calcium oxalate monohydrate (COM). Crystal deposition and kidney tissue injury were evaluated by hematoxylin and eosin, and von Kossa staining. Renal oxidative stress indexes including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), were analyzed. The renal expression of interleukin-1 beta (IL-1β), gasdermin D (GSDMD), osteopontin (OPN), CD44, and monocyte chemotactic protein 1 (MCP-1), and EMT-related proteins in renal tubular epithelial cells was assessed. Cell viability and the apoptosis ratio were evaluated.

RESULTS

In vivo, vitexin alleviated crystal deposition and kidney tissue injury, and decreased the level of MDA, and increased the levels of SOD, GSH, and CAT. Vitexin also reduced the levels of the pyroptosis-related proteins GSDMD, NLRP3, cleaved caspase-1, and mature IL-1β, which were elevated in mice with nephrolithiasis, and repressed apoptosis and the expression of OPN and CD44. Moreover, vitexin mitigated F4/80-positive macrophage infiltration and MCP-1 expression in the kidneys. Furthermore, an in vitro study showed that vitexin increased the viability of HK-2 cells and THP-1-derived macrophages, which was impaired by treatment with COM crystals, decreased the medium lactate dehydrogenase (LDH) level, and inhibited the expression of pyroptosis-related proteins in HK-2 cells and macrophages. Vitexin repressed EMT of HK-2 cells, with increased expression of pan-cytokeratin (Pan-ck) and decreased expression of Vimentin and alpha-smooth muscle actin (α-SMA), and downregulated the Wnt/β-catenin pathway. Moreover, vitexin suppressed tumor necrosis factor-α (TNF-α) and IL-1β mRNA expression, which was upregulated by COM in macrophages.

CONCLUSION

Vitexin exerts protective effects against nephrolithiasis by inhibiting pyroptosis activation, apoptosis, EMT, and macrophage infiltration. In addition, GSDMD-related pyroptosis mediates nephrolithiasis.

Fu-Fang-Jin-Qian-Cao herbal granules protect against the calcium oxalate-induced renal EMT by inhibiting the TGF-β/smad pathway

CONTEXT

Nephrolithiasis is a major public health problem worldwide and Fu-Fang-Jin-Qian-Cao granules (FFJQC) is a traditional Chinese herbal formula that is used to treat nephrolithiasis. The main component of nephrolithiasis is calcium oxalate (CaOx) and the epithelial-mesenchymal transition (EMT) shown to play a crucial role in CaOx-induced kidney injury. However, the mechanism underlying the therapeutic effect of FFJQC on the CaOx-induced renal EMT is unknown.

OBJECTIVE

This study explores the therapeutic benefits and mechanism of FFJQC in oxalate-induced kidney injury.

MATERIALS AND METHODS

60 male C57BL/6 mice were used in this experiment and divided into 6 groups. A mouse kidney stone model was created by intraperitoneal injection of glyoxylate at a dose of 100 mg/kg for 6 days. The standardized FFJQC was used to treat mouse crystal kidney injury by gavage at 1.35 and 2.7 g/kg, respectively. Western blotting and immunostaining for E-cadherin, cytokeratin 18 (CK18), vimentin, smooth muscle α-actin (α-SMA) and transforming growth factor β (TGF-β)/Smad pathway were conducted on renal tissues.

RESULTS

Following CaOx-induced kidney injury, the levels of E-cadherin and CK18 in kidney decreased, while vimentin and α-SMA levels increased. The FFJQC treatment increased the levels of E-cadherin and CK18 and decreased vimentin and α-SMA levels in varying degrees. What's more, the FFJQC reduced the expression of CaOx-induced fibrosis marker collagen II.

CONCLUSION

FFJQC alleviated the CaOx-induced renal EMT and fibrosis by regulating TGF-β/smad pathway. Therefore, the FFJQC is an important traditional Chinese medicine for the treatment of CaOx-induced renal injury and fibrosis.

Telmisartan inhibits oxalate and calcium oxalate crystal-induced epithelial-mesenchymal transformation via PPAR-γ-AKT/STAT3/p38 MAPK-Snail pathway

AIMS

Telmisartan (TLM), a highly selective angiotensin II type 1 receptor blocker (ARB) and partial PPAR-γ agonist, has versatile beneficial effects against oxidative stress, apoptosis, inflammatory responses and epithelial-mesenchymal transition (EMT). However, its underlying mechanism of inhibiting oxalate and calcium oxalate (CaOx) crystal-induced EMT by activating the PPAR-γ pathway remains unclear.

MAIN METHODS

CCK-8 assays were used to evaluate the effects of TLM on cell viability. In addition, intracellular reactive oxygen species (ROS) levels were measured by the cell-permeable fluorogenic probe 2,7-dichlorofluorescein diacetate (DCFH-DA). Wound-healing and Transwell assays were used to evaluate the migration ability of HK2 cells exposed to oxalate. Moreover, immunofluorescence, immunohistochemistry and western blotting were used to examine the expression of E-cadherin, N-cadherin, vimentin and α-SMA and explore the underlying molecular mechanisms in HK2 cells and a stone-forming rat model.

KEY FINDINGS

Our results showed that TLM treatment could protect HK2 cells from oxalate-induced cytotoxicity and oxidative stress injury. Additionally, TLM prevented EMT induction by oxalate and CaOx crystals via the PPAR-γ-AKT/STAT3/p38 MAPK-Snail pathway in vitro and in vivo. However, knockdown of PPAR-γ with small interfering RNA or the PPAR-γ-specific antagonist GW9662 abrogated these protective effects of TLM.

SIGNIFICANCE

As a PPAR-γ agonist, TLM can ameliorate oxalate and CaOx crystal-induced EMT by exerting an antioxidant effect through the PPAR-γ-AKT/STAT3/p38 MAPK-Snail signaling pathway. Therefore, TLM can block EMT progression and could be a potential therapeutic agent for preventing and treating calcium oxalate urolithiasis formation and recurrence.

LncRNA-miRNA-mRNA expression variation profile in the urine of calcium oxalate stone patients

Background

To explore long-non-coding RNA (lncRNA), microRNA (miRNA) and messenger RNA (mRNA) expression profiles and their biological functions in the urine samples in calcium oxalate (CaOx) patients.

Methods

Five CaOx kidney stone patients were recruited in CaOx stone group and six healthy people were included as control group, whose midstream morning urine was collected before the patients were given any medicine on admission. After total RNA was extracted from urine, microarray of miRNA, mRNA and lncRNA were applied to explore their expression variation. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to reveal the gene functions of the dysregulated lncRNA-associated competing endogenous RNA (ceRNA) network. Quantitative real-time PCR were performed on HK-2 cells treated with sodium oxalate (NaOx) to further screen out the differentially expression profiles of these RNAs.

Results

A total of nine miRNAs, 883 mRNAs and 1002 lncRNAs were differentially expressed in urine of CaOx patients compared with normal population. GO analysis revealed that most of mRNAs from ceRNA network were enriched in terms of respiratory burst, regulation of mitophagy, and protein kinase regulator activity. KEGG pathway analysis of these genes related to ceRNA network highlight their critical role in pentose phosphate pathway, glyoxylate and dicarboxylate metabolism, and Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling pathway. Five miRNAs (miR-6796-3p, miR-30d-5p, miR-3192–3p, miR-518b and miR-6776-3p), four mRNAs (NT5E, CDH4, CLEC14A, CCNL1) and six lncRNAs (lnc-TIGD1L2–3, lnc-KIN-1, lnc-FAM72B-4, lnc-EVI5L-1, lnc-SERPINI1–2, lnc-MB-6) from the HK-2 cells induced by NaOx were consistent with the expression changes of microarray results.

Conclusion

The differential expressed miRNAs, mRNAs and lncRNAs may be associated with numerous variations of the signaling pathways or regulation of metabolism and kinase activity, providing potential biomarkers for early diagnosis of urolithiasis and new basis for further research of urolithiasis mechanism.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0502-y) contains supplementary material, which is available to authorized users.