Oxalate disrupts monocyte and macrophage cellular function via Interleukin-10 and mitochondrial reactive oxygen species (ROS) signaling

Single-Cell RNA Sequencing Analysis Reveals the Role of Macrophage-Mediated CD44-AKT-CCL2 Pathways in Renal Tubule Injury during Calcium Oxalate Crystal Formation

Oxalate-induced crystalline kidney injury is a common form of crystal nephropathy. The accumulation of calcium oxalate (CaOx) crystal could lead to renal epithelium injury and inflammation. The underlying cellular events in kidney after CaOx crystal formation are largely unknown. This study was aimed to gain a better understanding of mouse kidney function in the development of renal CaOx formation. The study utilized a mouse CaOx model to analyze the cellular response at 5 time points using single-cell RNA sequencing and investigate the interaction of different cells during renal CaOx crystal formation. Additionally, the study investigated the communication between these cells and macrophages, as well as the role of chemokines in recruiting infiltrating macrophages. RNA velocity analysis uncovered an alternative differentiation pathway for injured and S1 proximal tubule cells, which mainly communicate with macrophages through the SPP1-CD44 pair, along with the expression of proinflammatory factors and stone matrix genes during renal CaOx crystal formation. Furthermore, resident Fn1 macrophages were found to express chemokines, such as CCL2, which recruited infiltrating macrophages. The CCL2 secretion was mediated by the CD44-AKT pathway. Blocking CCL2 decreased the expression of injury markers in the kidney, including CLU, LCN2, and KIM-1, and inhibited CaOx crystal deposition. The study identified potential cell types and target genes involved in renal tubule injury in oxalate-related crystal nephropathy. The findings shed light on the cellular processes that contribute to the formation and damage caused by CaOx crystals within the kidney, which could lead to the development of potential cell types and target genes for treating this condition.

NINJ1-mediated macrophage plasma membrane rupture and neutrophil extracellular trap formation contribute to oxalate nephropathy

BACKGROUND

Oxalate nephropathy is characterized by calcium oxalate crystals deposition, which triggers necrosis of renal tubular epithelial cells and initiates an inflammatory cascade characterized by neutrophil and macrophage activation within the renal microenvironment. Despite the close association of immune cells with acute oxalate nephropathy, the underlying mechanisms still remain unclear. Nerve injury-induced protein 1 (NINJ1) plays an essential role in the induction of plasma membrane rupture (PMR), leading to damage-associated molecular patterns (DAMPs) release and triggering inflammation. We hypothesize that NINJ1-mediated high mobility group box 1 (HMGB1) release from macrophage PMR and neutrophil extracellular traps (NETs) formation synergistically contribute to the progression of acute oxalate nephropathy.

METHODS

Using a murine model of acute oxalate nephropathy, myeloid cell-specific deletion of Ninj1 mice (Ninj1fl/flvavcre) and their wild-type littermate control mice (Ninj1wt/wtvavcre) were administered intraperitoneal injection of 100 mg/kg sodium oxalate followed by drinking water with 3% sodium oxalate. Evaluation was conducted on tubular injury and inflammatory cell infiltration. In vitro studies involved isolation and culture of renal proximal tubular epithelial cells, bone marrow-derived macrophages and neutrophils to investigate NETs formation and HMGB1 release.

RESULTS

Targeted deletion of Ninj1 in myeloid cells significantly mitigated oxalate-induced acute kidney injury by suppressing both HMGB1 release and NETs formation in vivo. In vitro investigations demonstrated that HMGB1 release from macrophage PMR and NETs formation in neutrophils mediated by NINJ1 oligomerization, which consequently coordinated to enhance renal tubular epithelial cell death.

CONCLUSIONS

Our findings elucidate the pivotal role of NINJ1-dependent macrophage PMR and NETs formation in the progression of acute oxalate nephropathy, providing novel insights for its prevention and therapeutic targets.

Gasdermin D deficiency aggravates nephrocalcinosis-related chronic kidney disease with rendering macrophages vulnerable to necroptosis

Several forms of regulated necrosis contribute to the pathogenesis of crystal nephropathy, however, the role of pyroptosis, an inflammatory form of cell death involving the formation of gasdermin-D pores in internal and external cell membranes, in this condition remains unknown. Our transcriptional and histological analyses suggest that Gsdmd in tubulointerstitital cells may contribute to the pathogenesis of chronic oxalate nephropathy. However, genetic deletion of Gsdmd exacerbated oxalate nephropathy in mice in association with enhanced CaOx crystal deposition and accelerated tubular epithelial cell injury. Pharmacological inhibition of necroptosis reversed this effect. Indeed, Gsdmd-/- bone marrow-derived macrophages were more prone to undergo necroptosis when stimulated with CaOx crystals compared to their wildtype counterparts. We conclude that gasdermin D suppresses the necroptosis pathway, which determines the outcome of oxalate nephropathy-related nephrocalcinosis.

Based on network pharmacology, the mechanism of Dioscin in alleviating renal tubular epithelial cell injury induced by calcium oxalate crystals was explored

The commencement of kidney stone formation involves a crucial initial phase characterized by injury to renal tubular cells caused by calcium oxalate (CaOx). Dioscin (Dio) has been acknowledged for its potent anti-inflammation and anti-apoptotic properties; nevertheless, the impact and underlying Investigation into the molecular basis underlying the action of Dioscin in mitigating inflammation and apoptotic induced by exposure to calcium oxalate crystals in renal tissues remain unexplored. To comprehend the precise mechanism of Dioscin in the treatment of crystalline nephropathy, we conducted experiments utilizing a murine model of CaOx crystal deposition, induced by intraperitoneal administration of glyoxylate. An in vitro model was constructed using HK-2 cells exposed to calcium oxalate monohydrate (COM). To evaluate the effect of Dioscin on calcium oxalate crystal deposition by ROS assay, Western blotting, immunohistochemistry, Periodic Acid-Schiff staining (PAS) staining, hematoxylin-eosin (H&E) staining. Using network pharmacology and molecular docking methods, we explored the molecular mechanism of Dioscin in the treatment of CaOx-induced renal tubular epithelial cell injury. Subsequently, we conducted experiments to verify our findings. We observed a significant protective effect of Dioscin treatment against kidney oxidative stress and inflammation induced by CaOx. Then we predicted through network pharmacology that Dioscin exerts its anti-apoptotic effect through the NF-kappa B signaling pathway. Then we verified in vitro and in vivo that administration of Dioscin can alleviate the elevation of TLR4 and activation of the NF-kappa B signaling pathway induced by calcium oxalate, as well as attenuate renal apoptosis. Instead, the beneficial impact of this protection of Dioscin was reversed after overexpression of the TLR4. Dioscin has the potential to alleviate the activation of the NF-kappa B signaling pathway through TLR4, thereby exerting anti-inflammatory and anti-apoptotic effects. This study provides new ideas for the prevention and treatment of kidney stones.

Mitochondrial malfunction-initiated Leydig cell premature senescence partially participates in 1-nitropyrene-evoked downregulation of steroidogenic synthases in testes

Serum testosterone (T) in males has been declining during the past decades. The previous reports found that 1-nitropyrene (1-NP) exposure suppressed testicular T synthesis. The purpose of the current study was to further explore whether premature senescence participates in 1-NP-triggered reduction of testicular T synthesis. Adult male mice were orally exposed to 1-NP (0, 100, and 500 μg/kg) daily for 14 days. Serum and testicular T contents were diminished in 1-NP-administered mice. Mitochondria-located steroidogenic synthases, including StAR, CYP11A1, and 3βHSD1, were downregulated in 1-NP-administered mouse testes and MLTC-1 cells. Mechanistically, 1-NP exposure increased acetylation modification of mitochondrial steroidogenic synthases by inhibiting the enzymatic activity of SIRT3, an NAD+-dependent deacetylase. Supplementing NAD + precursor and Sirt3 overexpression relieved 1-NP-triggered reduction of steroidogenic synthase levels in mouse testes and MLTC-1 cells. By contrast, Sirt3 silencing aggravated 1-NP-evoked acetylation and reduction of steroidogenic synthase levels in MLTC-1 cells. Further experiments demonstrated that 1-NP exposure caused mitochondrial malfunction and premature senescence in mouse testes and MLTC-1 cells. Supplementation with mitochondria-directed antioxidant mitoquinone (MitoQ) prevented 1-NP-evoked Leydig cell premature senescence and downregulation of testicular steroidogenic synthases. These results suggest that mitochondrial malfunction-initiated Leydig cell premature senescence may partially participate in 1-NP-evoked reduction of steroidogenic synthase levels in testes.

Effects of multiple fluid intake on Urolithiasis by mendelian randomization study

Urolithiasis, a common and recurrent condition, imposes a significant global health burden. This study investigates the causal relationship between various types of fluid intake and urolithiasis using univariable and multivariable Mendelian randomization (MR) approaches. Genetic data for urolithiasis were obtained from the FinnGen Consortium (n = 400,681), while genetic measures for nine fluid types were sourced from meta-analyses of genome-wide association studies (GWAS). The analysis revealed that genetically predicted coffee intake (OR: 0.571, 95% confidence interval (CI): 0.341-0.958, p = 0.034) and ground coffee intake (OR: 0.219, 95% CI: 0.005-0.923, p = 0.038) were protective factors for upper urinary calculi. Additionally, a standard deviation (SD) increase in tea intake was associated with a 53% reduction in risk (OR: 0.473, 95% CI: 0.320-0.700, p < 0.001). Conversely, milk intake (OR: 1.072, 95% CI: 1.018-1.130) and alcohol intakefrequency (OR: 1.304, 95% CI: 1.083-1.570, p = 0.005) increased the risk of upper urinary calculi. These findings highlight the association of tea with reduced risk of urolithiasis, instead for milk and alcohol intake, in formulating prevention strategies for urolithiasis.

New insight into oxidative stress and inflammatory responses to kidney stones: Potential therapeutic strategies with natural active ingredients

Kidney stones, a prevalent urological disorder, are closely associated with oxidative stress (OS) and the inflammatory response. Recent research in the field of kidney stone treatment has indicated the potential of natural active ingredients to modulate OS targets and the inflammatory response in kidney stones. Oxidative stress can occur through various pathways, increasing the risk of stone formation, while the inflammatory response generated during kidney stone formation further exacerbates OS, forming a detrimental cycle. Both antioxidant systems related to OS and inflammatory mediators associated with inflammation play roles in the pathogenesis of kidney stones. Natural active ingredients, abundant in resources and possessing antioxidative and anti-inflammatory properties, have the ability to decrease the risk of stone formation and improve prognosis by reducing OS and suppressing pro-inflammatory cytokine expression or pathways. Currently, numerous developed natural active ingredients have been clinically applied and demonstrated satisfactory therapeutic efficacy. This review aims to provide novel insights into OS and inflammation targets in kidney stones as well as summarize research progress on potential therapeutic strategies involving natural active ingredients. Future studies should delve deeper into exploring efficacy and mechanisms of action of diverse natural active ingredients, proposing innovative treatment strategies for kidney stones, and continuously uncovering their potential applications.

Hydroxyproline increases inflammation and Uropathogenic E. coli (UPEC) infection in female rats

Calcium oxalate (CaOx) kidney stones may be associated with urinary tract infections (UTIs). However, the mechanisms for this association are not well-established. The objective of this study was to investigate the effect of oxalate on immunity and UTI development in vivo. Female Sprague-Dawley rats were fed a control diet for 3 days before continuing this diet or starting a 5% Hydroxy-L-proline diet (HLP; oxalate precursor) for 7 days. Rats were subsequently infected transurethrally with Uropathogenic E. coli (UPEC, a bacterium that causes UTI) and sacrificed 3 days later. Urine, blood, kidney, and bladder samples were collected. Urinary oxalate levels, renal CaOx crystal deposition, inflammatory markers, and the bacterial load were assessed using ion chromatography-mass spectrometry, immunohistochemistry, qRT-PCR, western blotting, enzyme-linked immunosorbent assays, or colony forming unit assays. Animals fed HLP and infected with UPEC had a significant increase in urinary oxalate levels, renal CaOx deposition, pro-inflammatory macrophages, pro-inflammatory cytokines, and bacterial loads compared to animals fed the control diet with UPEC infection. In addition, HLP-fed animals had significantly reduced anti-inflammatory renal macrophages and anti-inflammatory cytokine levels in their plasma, urine, and kidneys. These findings suggest that oxalate may play a novel role in the propagation of UTI development.

Causal associations between 45 dietary intake habits and urolithiasis: insights from genetic studies

Background

Different dietary habits can have varying effects on human health and metabolism, and these can be intervened and regulated. Kidney stones, as a disease caused by multiple factors, are largely attributed to diet and metabolism, but the potential causal relationship with dietary intake habits remains unclear. Therefore, this study aims to link the predicted dietary intake based on 45 genetic factors with urolithiasis and explore the potential causal relationship.

Methods

We extracted complete genome-wide association studies (GWASs) data on 45 dietary intake traits from the UK Biobank study. Data on kidney stones were obtained from the FinnGen database. In both univariable and multivariable Mendelian randomization analyses, we used inverse variance weighted (IVW) as the primary method to calculate P values, odds ratios (ORs), and 95% confidence intervals (CIs). We examined result heterogeneity using Cochran's Q test. We also carefully investigated potential sources of horizontal pleiotropy using the Mendelian randomization (MR)-PRESSO and MR-Egger methods, and conducted linkage disequilibrium score regression (LDSC) analysis on the corrected P values.

Results

Through univariable analysis, we identified 11 dietary habits that potentially causally associate with kidney stones among the 45 examined traits, including 9 protective factors and 2 risk factors. Based on the corrected results with false discovery rate (FDR) and sensitivity analysis, we found one relatively robust evidence. We controlled for common stone risk factors, such as body mass index and smoking, as confounders in multivariable analysis, and no significant results were observed after controlling for these confounders. Based on the LDSC analysis, most of the evidence supports significant genetic correlations with urolithiasis among the 11 traits with potential causal associations.

Conclusions

This study confirms the impact of certain dietary factors on the development of kidney stones. Our findings contribute to providing evidence for dietary adjustments in daily life or dietary guidance specifically targeting kidney stone patients.

The immune factors have complex causal regulation effects on kidney stone disease: a mendelian randomization study

PURPOSE

Previous studies have reported the potential impact of immune cells on kidney stone disease (KSD), but definitive causal relationships have yet to be established. The purpose of this paper is to elucidate the potential causal association between immune cells and KSD by Mendelian randomization (MR) analysis.

METHODS

In our study, a thorough two-sample Mendelian randomization (MR) analysis was performed by us to determine the potential causal relationship between immune cell traits and kidney stone disease. We included a total of four immune traits (median fluorescence intensity (MFI), relative cellular (RC), absolute cellular (AC), and morphological parameters (MP)), which are publicly available data. GWAS summary data related to KSD (9713 cases and 366,693 controls) were obtained from the FinnGen consortium. The primary MR analysis method was Inverse variance weighted. Cochran's Q test, MR Egger, and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) were used to assess the stability of the results.

RESULTS

After FDR correction, the CD8 on HLA DR + CD8br (OR = 0.95, 95% CI = 0.93-0.98, p-value = 7.20 × 10- 4, q-value = 0.088) was determined to be distinctly associated with KSD, and we also found other 25 suggestive associations between immune cells and KSD, of which 13 associations were suggested as protective factors and 12 associations were suggested as risk factors. There was no horizontal pleiotropy or significant heterogeneity in our MR analysis, as determined by the p-value results of our Cochrane Q-test, MR Egger's intercept test, and MR-PRESSO, which were all > 0.05.

CONCLUSIONS

Our study has explored the potential causal connection between immune cells and KSD by Mendelian randomization analysis, thus providing some insights for future clinical studies.

Association between monocyte to high-density lipoprotein cholesterol ratio and kidney stone: insights from NHANES

Purpose

The ratio of monocyte to high-density lipoprotein cholesterol (MHR) has surfaced as a novel biomarker indicative of inflammation and oxidative stress. The aim of our study was to evaluate the association between MHR and the risk of kidney stones.

Methods

This study analyzed data from individuals aged 20-79 who participated in the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. The MHR was assessed as the exposure variable, while a self-reported history of kidney stones was used as the outcome variable. The independent relationship between MHR and the risk of kidney stones was thoroughly evaluated.

Results

This study included 28,878 participants, and as the quartile range of the MHR increased, the proportion of kidney stones also rose progressively (7.20% to 8.89% to 10.88% to 12.05%, P<0.001). After adjusting for confounding factors, MHR was independently associated with an increased risk of kidney stones (OR=1.31, 95%CI=1.11-1.54, P=0.001), also independent of some common inflammatory indices. Subgroup analysis suggested that the relationship between MHR and kidney stones was more pronounced in female and individuals aged 20-49. Further restricted cubic spline (RCS) analysis indicated a nonlinear relationship between MHR and the risk of kidney stones.

Conclusion

Our results indicate a positive correlation between MHR and an increased risk of kidney stones in US adults, underscoring the need for further large-scale prospective cohort studies to validate these findings.

Cell death‑related molecules and targets in the progression of urolithiasis (Review)

Urolithiasis is a high‑incidence disease caused by calcium oxalate (mainly), uric acid, calcium phosphate, struvite, apatite, cystine and other stones. The development of kidney stones is closely related to renal tubule cell damage and crystal adhesion and aggregation. Cell death, comprising the core steps of cell damage, can be classified into various types (i.e., apoptosis, ferroptosis, necroptosis and pyroptosis). Different crystal types, concentrations, morphologies and sizes cause tubular cell damage via the regulation of different forms of cell death. Oxidative stress caused by high oxalate or crystal concentrations is considered to be a precursor to a variety of types of cell death. In addition, complex crosstalk exists among numerous signaling pathways and their key molecules in various types of cell death. Urolithiasis is considered a metabolic disorder, and tricarboxylic acid cycle‑related molecules, such as citrate and succinate, are closely related to cell death and the inhibition of stone development. However, a literature review of the associations between kidney stone development, metabolism and various types of cell death is currently lacking, at least to the best of our knowledge. Thus, the present review summarizes the major advances in the understanding of regulated cell death and urolithiasis progression.

Mechanism of Porphyra Yezoensis Polysaccharides in Inhibiting Hyperoxalate-Induced Renal Injury and Crystal Deposition

Oxidative damage to the kidneys is a primary factor in the occurrence of kidney stones. This study explores the inhibitory effect of Porphyra yezoensis polysaccharides (PYP) on oxalate-induced renal injury by detecting levels of oxidative damage, expression of adhesion molecules, and damage to intracellular organelles and revealed the molecular mechanism by molecular biology methods. Additionally, we validated the role of PYP in vivo using a crystallization model of hyperoxalate-induced rats. PYP effectively scavenged the overproduction of reactive oxygen species (ROS) in HK-2 cells, inhibited the adhesion of calcium oxalate (CaOx) crystals on the cell surface, unblocked the cell cycle, restored the depolarization of the mitochondrial membrane potential, and inhibited cell death. PYP upregulated the expression of antioxidant proteins, including Nrf2, HO-1, SOD, and CAT, while decreasing the expression of Keap-1, thereby activating the Keap1/Nrf2 signaling pathway. PYP inhibited CaOx deposition in renal tubules in the rat crystallization model, significantly reduced high oxalate-induced renal injury, decreased the levels of the cell surface adhesion proteins, improved renal function in rats, and ultimately inhibited the formation of kidney stones. Therefore, PYP, which has crystallization inhibition and antioxidant properties, may be a therapeutic option for the treatment of kidney stones.

Quercetin inhibits calcium oxalate crystallization and growth but promotes crystal aggregation and invasion

Recent evidence has shown an association between kidney stone pathogenesis and oxidative stress. Many anti-oxidants have been studied with an aim for stone prevention. Quercetin, a natural flavonol, is one among those eminent anti-oxidants with satisfactory anti-inflammatory property to cope with renal tissue injury in kidney stone disease. Nevertheless, its direct effect (if any) on calcium oxalate (CaOx) crystals and the stone formation mechanism had not been previously explored. This study has addressed the ability of quercetin at various concentrations (2.5, 5, 10, 20, 40, 80 and 160 μM) to directly modulate CaOx crystallization, growth, aggregation, adhesion on kidney cells, and invasion through the matrix. The data have shown that quercetin significantly inhibits CaOx crystallization and crystal growth but promotes crystal aggregation in concentration-dependent manner. However, quercetin at all these concentrations do not affect CaOx adhesion on kidney cells. For the invasion, quercetin at all concentrations constantly promotes CaOx invasion through the matrix without concentration-dependent pattern. These discoveries have demonstrated for the first time that quercetin has direct but dual modulatory effects on CaOx crystals. While quercetin inhibits CaOx crystallization and growth, on the other hand, it promotes CaOx crystal aggregation and invasion through the matrix. These data highlight the role for quercetin in direct modulation of the CaOx crystals that may intervene the stone pathogenesis.