Activation of liver X receptor suppresses osteopontin expression and ameliorates nephrolithiasis

Inflammation-associated ectopic mineralization

Ectopic mineralization refers to the deposition of mineralized complexes in the extracellular matrix of soft tissues. Calcific aortic valve disease, vascular calcification, gallstones, kidney stones, and abnormal mineralization in arthritis are common examples of ectopic mineralization. They are debilitating diseases and exhibit excess mortality, disability, and morbidity, which impose on patients with limited social or financial resources. Recent recognition that inflammation plays an important role in ectopic mineralization has attracted the attention of scientists from different research fields. In the present review, we summarize the origin of inflammation in ectopic mineralization and different channels whereby inflammation drives the initiation and progression of ectopic mineralization. The current knowledge of inflammatory milieu in pathological mineralization is reviewed, including how immune cells, pro-inflammatory mediators, and osteogenic signaling pathways induce the osteogenic transition of connective tissue cells, providing nucleating sites and assembly of aberrant minerals. Advances in the understanding of the underlying mechanisms involved in inflammatory-mediated ectopic mineralization enable novel strategies to be developed that may lead to the resolution of these enervating conditions.

Calculus-related functional protein expression in ureteral calculus-adhered polyp: A preliminary study

To explore the expressions of calculus-related functional proteins in the ureteral calculus-adhered polyp tissues and investigate the role of these proteins in the formation of adhesions between the calculus and polyp.Patients with ureteral calculi and polyps who underwent ureteroscopic lithotripsy for the excision of polyps between January 2019 and June 2019 were enrolled. Polyps obtained from each patient were divided into 2 groups using a matched pairs design: observation group (polyps adhered to calculus) and control group (polyps not adhered to calculus). Histopathological examination of polyps was performed using hematoxylin and eosin staining. Polyp tissues were immunohistochemically stained to assess the expressions of calculus-related functional proteins, that is, annexin A1, calcium-binding protein S100A9 (S100A9), uromodulin, and osteopontin. Furthermore, quantitative analysis was performed using the H-score of tissue staining; Pearson correlation analysis was performed for proteins with high expression.Overall, 40 polyp specimens were collected from 20 patients with ureteral calculi combined with polyps (observation group, 20 specimens; control group, 20 specimens). Hematoxylin and eosin staining revealed obvious epithelial cell proliferation in polyps of both groups; crystals were observed in the epithelial cells of the polyp tissue in the observation group. The expression levels of annexin A1 and S100A9 in the observation group were significantly greater than those in the control group (P < .05). However, no obvious expression of osteopontin or uromodulin was observed in the polyp tissues of both groups. There was a strong correlation between the increased expressions of annexin A1 and S100A9 in the observation group (R = 0.741, P = .022).We documented increased expressions of annexin A1 and S100A9 in the ureteral calculus-adhered polyp tissues. Annexin A1 and S100A9 may play an essential role in the adhesion of calculus and polyp and the growth of calculi.

Osteogenic Differentiation of Renal Interstitial Fibroblasts Promoted by lncRNA MALAT1 May Partially Contribute to Randall's Plaque Formation

Background

The current belief is that Randall's plaques (RP) constitute a nidus for the formation of idiopathic calcium oxalate stones, but the upstream events in RP formation remain unclear. The present study aimed to investigate whether RP formation shares similarities with biomineralization and to illustrate the potential role played by the lncRNA MALAT1 in osteogenic differentiation of human renal interstitial fibroblasts (hRIFs).

Materials and Methods

Biomineralization and MALAT1 expression were assessed in RP, and hRIFs were isolated and induced under osteogenic conditions for further experiments. The transcription initiation and termination sites in MALAT1 were identified by 5' and 3' RACE. RNA immunoprecipitation assays and luciferase assays were used to validate the interactions among MALAT1, Runx2 and miRNAs.

Results

Upregulated expression of osteogenic markers and MALAT1 was observed in RP and hRIFs induced with osteogenic medium. Biomineralization in RP and calcium phosphate (CaP) deposits in induced hRIFs were further verified by electron microscopy. Furthermore, overexpression of MALAT1 promoted the osteogenic phenotype of hRIFs, while treatment with a miR-320a-5p mimic and knockdown of Runx2 significantly suppressed the osteogenic phenotype. Further analysis showed that MALAT1 functioned as a competing endogenous RNA to sponge miR-320a-5p, leading to upregulation of Runx2 and thus promoting osteogenic differentiation of hRIFs.

Conclusion

Ectopic calcification and MALAT1 partially contributed to the formation of RP, in which MALAT1 might promote Runx2 expression to regulate osteogenic differentiation of hRIFs by sponging miRNA-320a-5p. The current study sheds new light on the lncRNA-directed mechanism of RP formation via a process driven by osteogenic-like cells.

Comparison of single-use and reusable flexible ureteroscope for renal stone management: a pooled analysis of 772 patients

Flexible ureteroscopy is a common therapy for patients with renal calculi. In recent years, the prevalence of single-use flexible ureteroscope (FURS) use has been on the rise. Thus, several trials have been conducted to compare the efficacy between single-use and reusable FURS. The aim of this meta-analysis was to systematically assess the effectiveness and safety of single-use vs. reusable FURS in treating renal stones. PubMed, Web of Science, Cochrane Library and EMBASE were researched to identify relevant studies up to September 2019. Article selection was performed through the search strategy based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The Newcastle-Ottawa Scale was applied to assess the methodological quality of non-randomized controlled trials, and the methodological quality of randomized controlled trials was evaluated using the Jadad scale. A total of five studies with 772 patients were included in the meta-analysis, including two randomized controlled trials, two single-centre prospective studies, and one prospective case-control trial. The pooled results showed that single-use FURS was associated with a higher stone-free rate (SFR) (OR: 1.50; 95% CI, 1.06–2.12; P=0.02) than reusable FURS. A significant difference was noted in operative time, and single-use FURS was associated with a longer operative duration (MD: 7.39 min; 95% CI, 1.75–13.03; P=0.01). No significant difference was noted in perioperative complications (OR: 0.97; 95% CI, 0.56–1.70; P=0.92). Subgroup analysis showed no significant difference in urinary tract infection (OR: 0.80; 95% CI, 0.44–1.46; P=0.46), stent migration (OR: 0.56; 95% CI, 0.19–1.65; P=0.30) or acute kidney injury (OR: 0.76; 95% CI, 0.16–3.57; P=0.73). Single-use FURS is an effective and safe alternative to reusable FURS for the management of renal stones.

Idiopathic Osteoporosis and Nephrolithiasis: Two Sides of the Same Coin?

Idiopathic osteoporosis and nephrolithiasis are formidable health problems showing a progressive increase in their incidence and prevalence in the last decades. These temporal trends were observed in both pediatric and adult populations worldwide. Epidemiological and experimental studies indicate that both disorders show several common pathogenic environmental and genetic factors. In this review, we analyzed the clinical characteristics common to the two disorders and the state-of-the-art knowledge regarding the genetic predisposition and the environmental factors recognized as triggers in adult and pediatric ages. As a result of this work, we propose to consider idiopathic nephrolithiasis and osteoporosis as two possible expressions of a unique clinical syndrome. Accordingly, the clinical approach to both disorders should be modified in order to program an efficient primary and secondary prevention strategy.

Long non-coding RNA H19 promotes osteogenic differentiation of renal interstitial fibroblasts through Wnt-β-catenin pathway

Randall's plaque (RP) serves as a nidus on which idiopathic calcium oxalate stones form. Renal interstitial mineralization may be the cause underlying RP, and recent studies demonstrated the similarities between the interstitial mineralization and ectopic calcification. The present study aimed to investigate whether human renal interstitial fibroblasts (hRIFs) could form calcification under osteogenic conditions, and whether long non-coding RNA H19 participated in regulating osteogenic differentiation of hRIFs through Wnt-β-catenin pathway. HRIFs were isolated and induced for osteogenic differentiation under osteogenic conditions. Runx2, OCN, alkaline phosphatase (ALP) activity, and the mineralized nodule formation were used to assess the osteogenic phenotype. Molecule expressions were determined by qRT-PCR, immunofluorescence staining, and western blot. The mineralized nodules were assessed by Alizarin red staining. Compared to the normal renal papillary tissue, Runx2, OCN, and H19 were significantly upregulated in RP. After hRIFs were induced with osteogenic medium, osteogenic markers (Runx2, OCN and ALP), β-catenin and H19 were significantly upregulated, and the mineralized nodules are formed. Additionally, overexpression of H19 promoted the osteogenic phenotype of hRIFs and increased the expression of β-catenin, whereas knock-down of H19 or XAV939 (inhibitor of Wnt-β-catenin signaling pathway) significantly repressed the osteogenic phenotype of hRIFs and decreased the β-catenin. Moreover, XAV939 was shown to abolish the osteogenic differentiation of hRIFs promoted by H19. The study demonstrated that ectopic calcification partly participated in the formation of RP, and H19 promoted osteogenic differentiation of hRIFs by activating Wnt-β-catenin pathway, which shed new light on the molecular mechanism of the RP formation.