Effect of adiponectin on kidney crystal formation in metabolic syndrome model mice via inhibition of inflammation and apoptosis

Associations between the platelet/high-density lipoprotein cholesterol ratio and likelihood of nephrolithiasis: a cross-sectional analysis in United States adults

Aims

The primary objective of this study was to investigate the relationship between the platelet/high-density lipoprotein cholesterol ratio (PHR) and the prevalence of nephrolithiasis within the adult population of the United States.

Methods

The data used in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2018. The analysis included a non-pregnant population aged 20 years or older, providing proper PHR index and nephrolithiasis data. The research utilized subgroup analyses and weighted univariate and multivariable logistic regression to evaluate the independent association between the PHR and the susceptibility to nephrolithiasis.

Results

The study comprised 30,899 participants with an average PHR value of 19.30 ± 0.11. The overall prevalence rate of nephrolithiasis was estimated at 9.98% with an increase in the higher PHR tertiles (T1, 8.49%; T2, 10.11%; T3, 11.38%, P < 0.0001). An elevated PHR level was closely linked with a higher susceptibility to nephrolithiasis. Compared with patients in T1, and after adjusting for potential confounders in model 2, the corresponding odds ratio for nephrolithiasis in T3 was 1.48 (95% CI: 1.06 to 2.08), with a P-value = 0.02. The results of the interaction tests revealed a significant impact of chronic kidney disease on the relationship between PHR and nephrolithiasis. Furthermore, the restricted cubic spline analyses exhibited a positive, non-linear correlation between PHR and the risk of nephrolithiasis.

Conclusion

A convenient biomarker, the PHR, was independently associated with nephrolithiasis and could be a novel biomarker in predicting occurrence in clinical decision.

Association between circadian syndrome and the prevalence of kidney stones in overweight adults: a cross-sectional analysis of NHANES 2007-2018

OBJECTIVE

To explore the association between circadian syndrome (CircS) and the prevalence of kidney stones in overweight people.

MATERIALS AND METHODS

A cross-sectional analysis was conducted based on the NHANES 2007-2018. Overweight people aged ≥ 20 years were the target population. Three multivariable logistic regression models were built to examine the association between CircS and kidney stones. Subgroup analysis based on age, gender, and race were also employed. Interaction and stratification analysis was also conducted to identify whether some factors modify the association.

RESULT

A total of 4,603 overweight participants were included in the study. The multivariable logistic regression suggested that CircS was positively associated with the prevalence of kidney stones (OR = 1.422, 95% CI 1.057 to 1.912). The subgroup analysis showed that the association was more obvious in females (OR = 1.604, 95% CI 1.023 to 2.516) or in the population aged 35 to 49 years old (OR = 2.739, 95% CI 1.428 to 5.254). Additionally, the same trend was present when people were Mexican American (OR = 3.834, 95% CI 1.790 to 8.215) or other races (OR = 4.925, 95% CI 1.776 to 13.656). The interaction and stratification analysis showed that the results above were robust.

CONCLUSION

CircS was positively associated with the prevalence of kidney stones in overweight people, especially people as females, aged 35 to 49, and Mexican Americans.

Insights into risk factors for urolithiasis: a mendelian randomization study

BACKGROUND

Risk factors for urolithiasis have not been identified. Here, we aimed to identify potentially causal risk factors driving the risk of urolithiasis.

METHODS

Two sets of instrumental variables were used for analysis, derived from publicly available databases. Summary-level statistical data for urolithiasis were obtained from the MRC-IEU Consortium and UK biobank (Neale Lab). Mendelian randomization (MR) was conducted to identify causal risk of urolithiasis. Finally, the results of the two databases were combined and a meta-analysis was performed.

RESULTS

In the MRC-IEU consortium, the odds of urolithiasis increased per 1-SD increase of body mass index (BMI) (OR = 1.0016, 95% CI:1.0004-1.0029, p = 0.010), triglycerides (OR = 1.0016, 95% CI:1.0003-1.0029, p = 0.017), adiponectin (OR = 1.0027, 95% CI:1.0003-1.0050, p = 0.024), and body fat percentage (OR = 1.008, 95% CI:1.0001-1.0161, p = 0.047). In addition, alcohol intake also increased the incidence of urolithiasis (OR = 1.0030, 95% CI:1.0009-1.0051, p = 0.005). In the UK biobank, the odds of urolithiasis increased per 1-SD increase of waist circumference (OR = 1.0215, 95% CI:1.0061-1.0372, p = 0.008) and body fat percentage (OR = 1.0239, 95% CI:1.0043-1.0440, p = 0.020). Surprisingly, we found that the risk of urolithiasis decreased with increasing hip circumference (OR = 0.9954, 95% CI:0.9915-0.9992, p = 0.017). In a meta-analysis of MR results, higher BMI (OR = 1.0016, 95% CI:1.0004-1.0027, p = 0.009), waist circumference (OR = 1.0073, 95% CI:1.0020-1.0126, p = 0.007), adiponectin (OR = 1.0026, 95% CI:1.0008-1.0043, p = 0.004), triglycerides (OR = 1.0015, 95% CI:1.0004-1.0026, p = 0.008) and body fat percentage (OR = 1.0104, 95% CI:1.0030-1.0178, p = 0.006) increased the risk of urolithiasis. Furthermore, alcohol intake also increased the incidence of urolithiasis (OR = 1.0033, 95% CI:1.0012-1.0053, p = 0.002).

CONCLUSIONS

Our MR study found that higher BMI, triglycerides, waist circumference, adiponectin, body fat percentage, and alcohol intake increased the risk of urolithiasis.

Neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and lymphocyte-monocyte ratio (LMR) in predicting systemic inflammatory response syndrome (SIRS) and sepsis after percutaneous nephrolithotomy (PNL)

The objective of this prospective observational study was to assess the clinical significance of neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR) and lymphocyte–monocyte ratio (LMR) as potential biomarkers to identify post-PNL SIRS or sepsis. Demographic data and laboratory data including hemoglobin (Hb), total leucocyte count (TLC), serum creatinine, urine microscopy and culture were collected. The NLR, LMR and PLR were calculated by the mathematical division of their absolute values derived from routine complete blood counts from peripheral blood samples. Stone factors were assessed by non-contrast computerized tomography of kidneys, ureter and bladder (NCCT KUB) and included stone burden (Volume = L × W × D × π × 0.167), location and Hounsfield value and laterality. Intraoperative factors assessed were puncture site, tract size, tract number, operative time, the need for blood transfusion and stone clearance. Of 517 patients evaluated, 56 (10.8%) developed SIRS and 8 (1.5%) developed sepsis. Patients developing SIRS had significantly higher TLC (10.4 ± 3.5 vs 8.6 ± 2.6, OR 1.19, 95% CI 1.09–1.3, p = 0.000002), higher NLR (3.6 ± 2.4 vs 2.5 ± 1.04, OR 1.3, 95% CI = 1.09–1.5, p = 0.0000001), higher PLR (129.3 ± 53.8 vs 115.4 ± 68.9, OR 1.005, 95% CI 1.001–1.008, p = 0.005) and lower LMR (2.5 ± 1.7 vs 3.2 ± 1.8, OR 1.18, 95% CI 1.04–1.34, p = 0.006). Staghorn stones (12.8 vs 3.24%, OR 4.361, 95% CI 1.605–11.846, p = 0.008) and long operative times (59.6 ± 14.01 vs 55.2 ± 16.02, OR 1.01, 95% CI 1.00–1.03, p = 0.05) had significant association with postoperative SIRS. In conclusion, NLR, PLR and LMR can be useful independent, easily accessible and cost-effective predictors for early identification of post-PNL SIRS/sepsis.

Protective effect of LIF-huMSCs on the retina of diabetic model rats

AIM

To investigate the protective effect of human umbilical cord mesenchymal stem cells (hUCMSCs) modified by the LIF gene on the retinal function of diabetic model rats and preliminarily explore the possible mechanism.

METHODS

A stably transfected cell line of hUCMSCs overexpressing leukemia inhibitory factor (LIF) was constructed. Overexpression was verified by fluorescent quantitative polymerase chain reaction (qPCR). Forty-eight adult Sprague-Dawley rats were randomly divided into a normal control group (group A), streptozotocin-induced diabetic control group (group B), diabetic rats at 3mo injected with empty vector-transfected hUCMSCs (group C) or injected with LIF-hUCMSCs (group D). Four weeks after the intravitreal injection, analyses in all groups included retinal function using flash electroretinogram (F-ERG), retinal blood vessel examination of retinal flat mounts perfused with fluorescein isothiocyanate-dextran (FITC-dextran), and retinal structure examination of sections using hematoxylin and eosin staining. Expression levels of adiponectin (APN), high-sensitivity C-reactive protein (hs-CRP), and neurotrophin-4 (NT-4) in each group was detected using immunohistochemistry, PCR, Western blotting, and ELISA, respectively.

RESULTS

A stable transgenic cell line of LIF-hUCMSCs was constructed. F-ERG and FITC-dextran examinations revealed no abnormalities of retinal structure and function in group A, severe damage of the retinal blood vessels and function in group B, and improved retinal structure and function in group C and especially group D. qPCR, ELISA, and Western blot analyses revealed progressively higher APN and NT-4 expression levels in groups B, C, and D than in group A. hs-CRP expression was significantly higher in group B than in groups A, C, and D, and was significantly higher in group C than in group D (P<0.05).

CONCLUSION

LIF-hUCMSCs protect the retina of diabetic rats by upregulating APN and NT-4 expression and downregulating hs-CRP expression in the retina.

Epigenomic and transcriptional profiling identifies impaired glyoxylate detoxification in NAFLD as a risk factor for hyperoxaluria

Epigenetic modifications (e.g. DNA methylation) in NAFLD and their contribution to disease progression and extrahepatic complications are poorly explored. Here, we use an integrated epigenome and transcriptome analysis of mouse NAFLD hepatocytes and identify alterations in glyoxylate metabolism, a pathway relevant in kidney damage via oxalate release-a harmful waste product and kidney stone-promoting factor. Downregulation and hypermethylation of alanine-glyoxylate aminotransferase (Agxt), which detoxifies glyoxylate, preventing excessive oxalate accumulation, is accompanied by increased oxalate formation after metabolism of the precursor hydroxyproline. Viral-mediated Agxt transfer or inhibiting hydroxyproline catabolism rescues excessive oxalate release. In human steatotic hepatocytes, AGXT is also downregulated and hypermethylated, and in NAFLD adolescents, steatosis severity correlates with urinary oxalate excretion. Thus, this work identifies a reduced capacity of the steatotic liver to detoxify glyoxylate, triggering elevated oxalate, and provides a mechanistic explanation for the increased risk of kidney stones and chronic kidney disease in NAFLD patients.

Neutrophil-lymphocyte ratio acts as a novel diagnostic biomarker for kidney stone prevalence and number of stones passed

Background

This study evaluated the relationship between inflammatory biomarkers and the prevalence of kidney stones and number of stones passed.

Methods

We conducted a cross-sectional study of adult participants (≥20 years) in the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2014. We calculated key inflammatory biomarkers, such as the systemic immune-inflammation index (SII), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and monocyte-lymphocyte ratio (MLR). Multivariate logistic regression analysis was used to determine the effect of inflammatory biomarkers on the prevalence of kidney stones and number of stones passed.

Results

A total of 21,106 participants were included in the final study, and 1,864 patients reported a history of kidney stones (including 292 who had passed no stones, 1,462 who had passed stones 1-5 times, and 110 who had passed stones >5 times). The chi-square test showed that the NLR, MLR and SII were closely related to the occurrence of kidney stones and the number of stones passed. Multivariate logistic regression analysis showed that a high NLR (>1.72) was associated with an increased prevalence of kidney stones and number of stones passed (OR =1.18, 95% CI: 1.03-1.36, P=0.019).

Conclusions

A convenient biomarker, the NLR can be used as a good predictor for the diagnosis of kidney stones and number of stones passed; these findings are worthy of further research and application in clinical practice.

A different perspective on the filtration barrier after kidney stone formation: An immunohistochemical and biochemical study

The aim of this study is to investigate whether the filtration barrier is affected by experimental kidney stone formation. Thirty-two rats divided into 4 equally groups (n = 8) at random. Group I control; Group II 1% ethylene glycol; Group III 1% Ethylene glycol + 0.25% Ammonium chloride; Group IV 1% Ethylene glycol + 0.5% Ammonium chloride group. Tissues applied hematoxylin-eosin, periodic-acid-Schiff, Pizzolato's staining. Immunohistochemically stained with integrin α3β1, type IV collagen, laminin, nephrin, CD2-associated protein (CD2AP) and podocin to show the filtration barrier structure. The TUNEL method was used for apoptosis. The amount of calcium, magnesium, creatinine and uric acid in urine and blood samples, also urine microprotein determined. Stones were formed in all experimental groups. Urine calcium, creatinine, uric acid levels decreased, magnesium levels were not changed. No statistically significant change was observed in blood serum results and TUNEL analysis. Immunohistochemical results showed an increase in nephrin, podocin, CD2AP, laminin and a decrease in integrin α3β1 and type IV collagen. Consequently, there is an increase in the expression densities of the proteins incorporated in the structure to prevent loss of functionality in the cellular part supporting the structure against a weakening of the basement membrane structure in the glomerular structure in which urine is filtered.

Identification of Differentially Expressed Genes Associated with Extracellular Matrix Degradation and Inflammatory Regulation in Calcific Tendinopathy Using RNA Sequencing

Calcific tendinopathy (CT), developed due to calcium hydroxyapatite deposition in the rotator cuff tendon, mostly affects women in their 40 s and 50 s and causes severe shoulder pain. However, the molecular basis of its pathogenesis and appropriate treatment methods are largely unknown. In this study, we identified 202 differentially expressed genes (DEGs) between calcific and adjacent normal tendon tissues of rotator cuff using RNA sequencing-based transcriptome analysis. The DEGs were highly enriched in extracellular matrix (ECM) degradation and inflammation-related processes. Further, matrix metalloproteinase 9 (MMP9) and matrix metalloproteinase 13 (MMP13), two of the enzymes associated with ECM degradation, were found to be highly upregulated 25.85- and 19.40-fold, respectively, in the calcific tendon tissues compared to the adjacent normal tendon tissues. Histopathological analyses indicated collagen degradation and macrophage infiltration at the sites of calcific deposit in the rotator cuff tendon. Our study acts as a foundation that may help in better understanding of the pathogenesis associated with CT, and thus in better management of the disease.

Hydroxycitric Acid Inhibits Renal Calcium Oxalate Deposition by Reducing Oxidative Stress and Inflammation

Objective:

The study aimed to evaluate the preventive effects of hydroxycitric acid（HCA） for stone formation in the glyoxylate-induced mouse model.

Materials and methods:

Male C57BL/6J mice were divided into a control group, glyoxylate(GOX) 100 mg/kg group, a GOX+HCA 100 mg/kg group, and a GOX+HCA 200 mg/kg group. Blood samples and kidney samples were collected on the eighth day of the experiment. We used Pizzolato staining and a polarized light microscope to examine crystal formation and evaluated oxidative stress via the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the expression of monocyte chemotactic protein-1(MCP-1), nuclear factor-kappa B (NF κ B), interleukin-1 β (IL-1 β) and interleukin-6 (IL-6) messenger RNA (mRNA). The expression of osteopontin (OPN) and a cluster of differentiation-44(CD44) were detected by immunohistochemistry and qRT-PCR. In addition, periodic acid Schiff (PAS) staining and TUNEL assay were used to evaluate renal tubular injury and apoptosis.

Results:

HCA treatment could reduce markers of renal impairment (Blood Urea Nitrogen and serum creatinine). There was significantly less calcium oxalate crystal deposition in mice treated with HCA. Calcium oxalate crystals induced the production of reactive oxygen species and reduced the activity of antioxidant defense enzymes. HCA attenuated oxidative stress induced by calcium oxalate crystallization. HCA had inhibitory effects on calcium oxalate-induced inflammatory cytokines, such as MCP-1, IL- 1 β, and IL-6. In addition, HCA alleviated tubular injury and apoptosis caused by calcium oxalate crystals.

Conclusion:

HCA inhibits renal injury and calcium oxalate crystal deposition in the glyoxylate-induced mouse model through antioxidation and anti-inflammation.

Statins significantly alter urinary stone-related urine biochemistry in calcium kidney stone patients with dyslipidemia

OBJECTIVE

To investigate whether the use of statins would alter 24-h urine biochemistry in male patients with calcium kidney stones.

METHODS

We prospectively recruited 78 male patients with calcium kidney stones between May 2017 and December 2017, and 30 male controls with matching sex and age, but without kidney stones. All patients were classified into higher- and lower-risk groups of atherosclerotic cardiovascular disease according to the American College of Cardiology/American Heart Association guidelines. Atorvastatin 20 mg per day was prescribed for 12 weeks to the higher risk patients. For kidney stone group, 24-h urine collections were carried out before and after statin therapy.

RESULTS

A total of 78 patients and 30 controls were included. Higher-risk patients had significantly higher urine uric acid and calcium levels than lower-risk patients. After atorvastatin treatment for 12 weeks, urine citrate significantly increased (P < 0.001) accompanied with increased urine pH (P < 0.001), whereas urine uric acid significantly decreased after treatment. Although urine oxalate significantly increased after treatment (P = 0.037), we did not find any significant difference in urine calcium, ion activity product of calcium oxalate and ion activity product of calcium phosphate.

CONCLUSION

These findings suggest that atorvastatin administration might increase urinary citrate and decrease urinary uric acid in patients with calcium kidney stones and dyslipidemia.

Fatty acid-binding protein 4 downregulation drives calcification in the development of kidney stone disease

Nephrolithiasis is a significant source of morbidity, and its incidence has increased significantly over the last decades. This rise has been attributed to concurrent increasing rates of obesity, associated with a 3-time risk of developing NL. To date, the mechanism by which obesity is linked to stone formation has not been elucidated. We aimed to utilize a transcriptomics approach to discover the missing link between these two epidemic diseases. We investigated gene expression profiling of nephrolithiasis patients by two RNA-sequencing approaches: comparison between renal papilla tissue with and without the presence of calcified Randall's plaques (RP), and comparison between the papilla, medulla, and cortex regions from within a single recurrent stone forming kidney. Results were overlaid between differently expressed genes found in the patient cohort and in the severely lithogenic kidney to identify common genes. Overlay of these two RNA-sequencing datasets demonstrated there is impairment of lipid metabolism in renal papilla tissue containing RP linked to downregulation of fatty acid binding protein (FABP) 4. Immunohistochemistry of human kidney specimens and microarray analysis of renal tissue from a nephrolithiasis mouse model confirmed that FABP4 downregulation is associated with renal stone formation. In a FABP4 knockout mouse model, FABP4 deficiency resulted in development of both renal and urinary crystals. Our study revealed that FABP4 plays an important, previously unrecognized role in kidney stone formation, providing a feasible mechanism to explain the link between nephrolithiasis and metabolic syndrome.

Active Phagocytosis and Diachronic Processing of Calcium Oxalate Monohydrate Crystals in an in vitro Macrophage Model

BACKGROUND

We previously discovered that renal macrophages (Mφs) phagocytose renal calcium oxalate monohydrate (COM) crystals. This study investigated the processing of engulfed crystals using in vitro models.

METHODS

J774.1 mouse Mφs were exposed to COM crystals and observed for 24 h using polarized light microscopy with/without cytochalasin B (CB), an inhibitor of phagocytosis, to confirm active crystal phagocytosis. LysoTracker and immunohistochemical staining using transmission electron microscopy for lysosomal-associated membrane protein 1 were used to confirm engulfed COM crystal uptake into lysosomes. Diachronic tracking of specific Mφs was performed to capture the entire course of engulfed COM crystal processing using polarized light microscopy. Follow-up studies of fluorescent COM (f-COM) crystals using imaging cytometry were performed in the presence and absence of nigericin to dissipate the pH gradient in acidic organelles.

RESULTS

Phagocytosis rates increased with COM density and were significantly lower in cells treated with CB (p < 0.01). We observed that engulfed crystals colocalized within lysosomes of the Mφs; moreover, diachronic observation indicated that the engulfed COM crystals were subdivided during Mφ division and eliminated by the 7th day of culture. Additionally, imaging cytometry showed that the fluorescence level of f-COM crystals in the nigericin (-) group after 48 h was significantly lower than that in the nigericin (+) group.

CONCLUSIONS

This study confirmed active phagocytosis and lysosomal processing of engulfed COM crystals by Mφs. This discovery is expected to contribute to the development of future drugs that enhance the COM crystal phagocytic ability of Mφs.

Brown adipocytes and β3-stimulant-induced brown-like adipocytes contribute to the prevention of renal crystal formation

According to recent studies, kidney stones are associated with metabolic syndrome. We focused on brown adipocytes and β₃-stimulant-induced brown-like adipocytes to investigate how these adipocytes influence kidney stone disease. For the interscapular brown adipose tissue (iBAT) removal experiment, mice were subjected to either iBAT removal or sham operation (X-BAT group or sham group), and, after 3 wk, renal crystal deposition was induced by intra-abdominal injection of glyoxylate (GOX) for 6 days. For the β₃-stimulant experiment, mice were administered intra-abdominal injections of the β₃-stimulant (β₃-group) or saline (control group) for 6 days. Thereafter, renal crystal deposition was induced by intra-abdominal injection of GOX for 6 days. iBAT removal decreased the expression of Sod1 and increased that of chemokine (C-C motif) ligand 2 (Ccl2), EGF module-containing mucin-like receptor 1 (Emr1), and tumor necrosis factor (Tnf) in the kidneys. Renal crystal deposition was 2.06-fold higher in the X-BAT group than in the sham group. The β₃-stimulant caused differentiation of white adipocytes into brown-like adipocytes. In the kidneys of the β₃-group, the expression of Ccl2 and Emr1 decreased and that of Sod1 increased. Renal crystal deposition was 0.17-fold lower in the β₃-group than in the control group. In summary, iBAT removal promoted kidney inflammation and renal crystal formation. β₃-Stimulant-induced brown-like adipocytes reduced inflammation and improved antioxidant action in the kidneys, which suppressed renal crystal formation. This is the first report on the therapeutic role of brown and brown-like adipocytes for kidney stone formation.

Metformin prevents nephrolithiasis formation by inhibiting the expression of OPN and MCP-1 in vitro and in vivo

Treatment targeting osteopontin (OPN) and monocyte chemoattractant protein 1 (MCP-1) has been recognized as a novel approach in renal crystal formation. The present study was designed to investigate the suppressive effects of metformin on nephrolithiasis formation and its potential mechanism. The cytotoxicity of metformin on MDCK and HK-2 cells was determined using a Cell Counting Kit-8 assay in vitro. Subsequently, the mRNA transcription and protein expression levels of MCP-1 and OPN were detected by reverse transcription-quantitative-polymerase chain reaction analysis, western blot analysis and ELISA. Male Sprague-Dawley rats were divided into a control group, ethylene glycol (EG) group and EG + metformin group. The expression levels of MCP-1 and OPN and crystal formations were evaluated in renal tissues following an 8-week treatment period. In vitro, metformin significantly inhibited the production of MCP-1 and OPN induced by oxalate at the mRNA and protein expression levels. In vivo, increased expression levels of MCP-1 and OPN were detected in the EG group compared with the controls, and this upregulation was reversed in the EG + metformin group. Renal crystal deposition in the EG + metformin group was markedly decreased compared with that in the EG group. Therefore, the results of the study suggest that metformin suppressed urinary crystal deposit formation, possibly by mediating the expression of inflammatory mediators OPN and MCP-1.

Association between blood lipid profile and urolithiasis: A systematic review and meta-analysis of observational studies

The objective of this study was to pool individual studies regarding the association of blood lipid profiles with urolithiasis to carry out a systematic review and meta-analysis. We searched MEDLINE, PubMed, Embase and Cochrane Library to identify the relevant studies up to November 2017. Studies that met all inclusion criteria were chosen, and a pooled analysis of the odds ratio between urolithiasis and dyslipidemia traits was calculated. A total of 11 observational studies (seven cross-sectional, three cohort, one case-control) with a total of 282 479 participants were examined. The overall pooled analysis of eight studies showed that high triglyceride was associated with increased estimated risk of urolithiasis (odds ratio 1.287, 95% CI 1.073-1.544; P = 0.007). Estimates of the total effect size were consistent in the sensitivity analysis. No evidence of publication bias was detected. The overall pooled analysis of nine studies showed low high-density lipoprotein was weakly associated with increased estimated risk of urolithiasis (odds ratio 1.171, 95% CI 1.010-1.358; P = 0.032). The sensitivity analysis showed conflicting results. No evidence of publication bias was detected. Three studies on the association between any dyslipidemia traits and urolithiasis showed a significant association (odds ratio 1.309, 95% CI 1.202-1.425; P < 0.001). The present meta-analysis showed that patients with higher triglyceride and lower high-density lipoprotein had an increased estimated risk of urolithiasis. A triglyceride-urolithiasis association was found to be more coherent and consistent compared with the high-density lipoprotein-urolithiasis association. Although somewhat contradictory results have been found, the meta-analysis is encouraging for evaluating urolithiasis as a systemic disorder. Further well-designed prospective randomized controlled or cohort studies are necessary to better elucidate the causal association of dyslipidemia and urolithiasis.

The effects of HAP and macrophage cells to the expression of inflammatory factors and apoptosis in HK-2 cells of vitro co-cultured system

This study developed an in vitro system by co-culturing HK-2 cells with different concentration of hydroxyapatite (HAP) and/or macrophage cells to simulate the internal environment of urolithiasis as far as possible, investigating the regulatory effects of macrophage cells on HAP-induced expression of relative inflammatory factors of HK-2 cells. The control group (H group) was only comprised of HK-2 cells. Experimental groups included co-culturing HK-2 cells and macrophage cells (H + M group), co-culturing HK-2 cells and HAP (H + A group), co-culturing macrophage cells and HAP (M + A group), and co-culturing HK-2 cells and macrophage cells with HAP (H + M + A group). In the H + A, M + A, and H + M + A group, we set the concentration of HAP as 5 μg/cm² (A1) and 10 μg/cm² (A2). After co-culturing for 2, 4, and 6 h, we detected the expression of CCL-2 in the liquid by ELISA. We tested the expression of LDH and ROS to evaluate the damage of HK-2 cells. We assessed the apoptosis of HK-2 cells using DAPI staining assay, flow cytometry, and the rate of BAX/BCL-2. Western Blotting detected OPN, Fetuin-A, BAX, and BCL-2 of HK-2 cells. The expression of CCL-2 in the medium of H + A1 and H + A2 group increased significantly compared with the control (P < 0.05); CCL-2 of M + A1 and M + A2 group was higher than the H + A1 and H + A2 group (P < 0.05). The expression of CCL-2 in H + M + A1 and H + M + A2 group was also higher than M + A1 and M + A2 group (P < 0.05). Compared with control, the expression of OPN, LDH release, the ratio of BAX/BCL-2, and the generation of ROS in HK-2 cells increased in a dose- and time-dependent manner. Compared with the control, the expression of Fetuin-A decreased in various degrees at different incubation periods. Especially when co-culturing for 6 h, Fetuin-A decreased most seriously in the H + M + A1 group. (1) The HAP can induce the HK-2 cells oxidative stress and inflammatory damage and apoptosis, when adding the macrophages to co-culture, macrophage cells can aggravate the damage and apoptosis of the HK-2 cells. (2) After the stimulation of HAP, the expression of OPN in HK-2 cells increased in a time- and dose-dependent manner; macrophage cells can aggravate the increase of OPN in HK-2 cells. (3) In the HAP and HK-2 cells co-cultured system, the low-level Fetuin-A of HK-2 cells may be related to the excessive consumption of Fetuin-A in the process of HAP-induced renal tubular epithelial cell excessive oxidative stress, inflammatory injury, and cell apoptosis. When adding macrophage cells to co-culture, Fetuin-A decreased even more seriously, it reminds us that macrophage cells can slightly regulate the expression of Fetuin-A in the HK-2 cells.

Association Between Adiponectin and Insulin Resistance in Diabetic Urolithiasis

OBJECTIVES

The prevalence of urolithiasis is increasing worldwide. Diabetes mellitus (DM) is characterized by insulin resistance, which increases the risk of kidney stone formation. Adiponectin is an insulin-sensitizing and anti-inflammatory cytokine, which is known to improve glucose tolerance and insulin resistance in humans. The association of insulin and adiponectin with kidney stones is not clear. Hence, the present study aim to assess the serum levels of adiponectin and insulin resistance in DM patients with urolithiasis in comparison to those without.

METHODS

This study involved two groups, group A consisted of 30 patients with DM and urolithiasis, and group B consisted of 30 patients with DM but without urolithiasis (control group). Biochemical parameters studied were serum adiponectin, insulin, glucose, urea, creatinine, and 24 hours urinary calcium and phosphate.

RESULTS

The serum adiponectin level was significantly increased in the diabetic urolithiasis cases (group A) compared to the control group (group B). The levels of 24 hours urine calcium and phosphorus were also significantly increased in group A. There was no significant difference in serum insulin and homeostasis model assessment of insulin resistance between the two groups. A negative correlation was seen between serum adiponectin and insulin among the cases (r = -0.368 and p = 0.045).

CONCLUSIONS

We found that serum adiponectin levels are increased in patients with DM and urolithiasis.

Role of p62 in the suppression of inflammatory cytokine production by adiponectin in macrophages: Involvement of autophagy and p21/Nrf2 axis

Adiponectin possesses potent anti-inflammatory properties. p62, an adaptor protein composed of multi-functional domain, is known to play a role in controlling inflammatory responses. In the present study, we examined the role of p62 in suppressing inflammatory cytokines produced by globular adiponectin (gAcrp) and the potential underlying mechanisms in macrophages. We demonstrated that gAcrp significantly increased p62 expression. Knockdown of p62 abrogated the suppressive effects of gAcrp on LPS-stimulated TNF-α and IL-1β expression and TRAF6/p38 MAPK pathway, indicating that p62 signaling is critical for suppressing inflammatory cytokines production by gAcrp. We next examined the role of p62 in gAcrp-induced autophagy activation, because autophagy has been shown to play a pivotal role in suppressing TNF-α. Herein, we observed that gene silencing of p62 prevented gAcrp-induced increases in autophagy-related genes and autophagosome formation. In addition, we found that Nrf2 knockdown prevented gAcrp-induced p62 expression, and p21 knockdown prevented Nrf2 induction, suggesting the role of p21/Nrf2 axis in gAcrp-induced p62 expression. Taken together, these findings imply that p62 signaling plays a crucial role in suppressing inflammatory cytokine production by globular adiponectin in macrophages, at least in part, through autophagy induction. Furthermore, the p21/Nrf2 signaling cascade contributes to p62 induction by globular adiponectin.

M1/M2-macrophage phenotypes regulate renal calcium oxalate crystal development

In our previous report, M2-macrophage (Mφs) deficient mice showed increased renal calcium oxalate (CaOx) crystal formation; however, the role of Mφs-related-cytokines and chemokines that affect kidney stone formation remains unknown. Here, we investigated the role of M1/M2s in crystal development by using in vitro and in vivo approaches. The crystal phagocytic rate of bone marrow-derived M2Mφs was higher than that of bone marrow-derived Mφs and M1Mφs and increased on co-culture with renal tubular cells (RTCs). However, the amount of crystal attachment on RTCs reduced on co-culture with M2Mφs. In six hyperoxaluric C57BL/6J mice, M1Mφ transfusion and induction by LPS and IFN-γ facilitated renal crystal formation, whereas M2Mφ transfusion and induction by IL-4 and IL-13 suppressed renal crystal formation compared with the control. These M2Mφ treatments reduced the expression of crystal-related genes, such as osteopontin and CD44, whereas M1Mφ treatment increased the expression of pro-inflammatory and adhesion-related genes such as IL-6, inducible NOS, TNF-α, C3, and VCAM-1. The expression of M2Mφ-related genes was lower whereas that of M1Mφ-related genes was higher in papillary tissue of CaOx stone formers. Overall, our results suggest that renal crystal development is facilitated by M1Mφs, but suppressed by M2Mφs.

Analysis of altered microRNA expression profiles in the kidney tissues of ethylene glycol-induced hyperoxaluric rats

Calcium oxalate stones account for >80% of urinary stones, however the mechanisms underlying their formation remains to be elucidated. Hyperoxaluria serves an important role in the pathophysiological process of stone formation. In the present study, differences in the miRNA expression profiles between experimental hyperoxaluric rats and normal rats were analyzed, in order to identify target genes and signaling pathways involved in the pathogenesis of hyperoxaluria. Ethylene glycol and ammonium chloride was fed to male hyperoxaluric rats (EXP) and normal age-matched male rats (CON). The oxalate concentration in the urine of each experimental rat was collected every 24 h and measured on day 14. Three rats exhibiting the highest concentrations were selected for microarray analysis. Microarray analysis was performed to evaluate differences in the expression of microRNA (miRNA) in the kidney tissues from EXP and CON groups, and miRNAs that exhibited a >2-fold or a <0.5-fold alteration in expression between these groups were screened for differential expression patterns according to the threshold P-values. Reverse transcription-quantitative polymerase chain reaction analysis was employed to confirm the microarray results. In order to predict the potential role of miRNAs in pathophysiological processes, gene ontology (GO), pathway and target prediction analyses were conducted. A total of 28 miRNAs were observed to be differentially expressed (>2-fold change) between EXP and CON groups. Among these miRNAs, 20 were upregulated and 8 were downregulated. GO and pathway analyses revealed that the insulin resistance and phosphatidylinositol-bisphosphonate 3-kinase/AKT serine threonine kinase signaling pathways were potentially associated with miRNA regulation in this setting. In conclusion, the results of the present study identified differentially expressed miRNAs in hyperoxaluric rats, and provided a novel perspective for the role of miRNAs in the formation of calcium oxalate stones.

Differential Roles of Peroxisome Proliferator-Activated Receptor-α and Receptor-γ on Renal Crystal Formation in Hyperoxaluric Rodents

Peroxisome proliferator-activated receptors (PPARs) and related inflammatory and oxidative molecule expression were investigated in a hyperoxaluric rodent model to evaluate the in vivo efficacy of PPAR agonists in preventing renal crystal formation. PPAR expression was examined in a mouse hyperoxaluria kidney stone model induced by daily intra-abdominal glyoxylate injection. Therapeutic effects of the PPARα agonist fenofibrate and PPARγ agonist pioglitazone were also assessed in a 1% ethylene glycol-induced rat model of hyperoxaluria. Crystal formation, inflammation, cell injury, apoptosis, and oxidative stress were compared to those of vehicle-treated controls. Quantitative reverse transcription-polymerase chain reaction revealed that PPARα and PPARγ expression decrease and increase, respectively, during crystal formation in hyperoxaluric kidneys. In addition, PPARα localized to the cytoplasm of both proximal and distal tubular cells, whereas PPARγ accumulated in the nucleus of proximal tubular cells. Furthermore, renal crystal formation was significantly less prevalent in pioglitazone-treated rats but higher in the fenofibrate-treated and fenofibrate/pioglitazone-cotreated groups compared to controls, thus indicating that pioglitazone, but not fenofibrate, markedly decreased cell inflammation, oxidative stress, and apoptosis. Collectively, the results demonstrated that PPARγ suppressed renal crystal formation via its antioxidative and anti-inflammatory effects; however, the renotoxicity of PPARα may elicit the opposite effect.

Proinflammatory and Metabolic Changes Facilitate Renal Crystal Deposition in an Obese Mouse Model of Metabolic Syndrome

PURPOSE

To clarify metabolic syndrome induced stone formation mechanisms we investigated the metabolic and immunohistochemical characteristics associated with renal crystal deposition using a model of mice with metabolic syndrome administered a high fat diet and ethylene glycol.

MATERIALS AND METHODS

Ob/Ob mice with Leptin gene deficiencies and metabolic syndrome related characteristics were compared with wild heterozygous lean mice. Four study groups were fed standard food and water (control group), a high fat diet and normal water (high fat diet group), 1% ethylene glycol and standard food (ethylene glycol group) or a high fat diet and 1% ethylene glycol (high fat diet plus ethylene glycol group). Blood, urine and kidney samples were taken after 14 days.

RESULTS

Ob/Ob mice in the high fat diet plus ethylene glycol group showed diffuse renal crystal depositions. Lean and Ob/Ob mice in the high fat diet plus ethylene glycol group showed significant excretion of urinary calcium oxalate crystals. Ob/Ob mice had significant hypercalciuria, hyperphosphaturia and hyperlipidemia, massive lipid fragments in tubular lumina and fat droplets in renal tubular cells. Ob/Ob mice in the high fat diet plus ethylene glycol group had markedly increased expression of osteopontin, monocyte chemoattractant protein-1, interleukin-6 and tumor necrosis factor-α. In Ob/Ob mice the number of proinflammatory macrophages was considerably elevated.

CONCLUSIONS

We induced renal crystal deposition in mice with metabolic syndrome using a high fat diet and ethylene glycol. Increases in luminal mineral and lipid density, and proinflammatory adipocytokines and macrophages facilitated renal crystal formation in mice with metabolic syndrome.

Vorinostat protects against calcium oxalate-induced kidney injury in mice

The present study aimed to examine the effect of the histone deacetylase inhibitor, vorinostat (SAHA), on renal function in a calcium oxalate crystal mouse model, and to investigate the mechanism underlying the renoprotective effect of SAHA. Calcium oxalate crystal formation was induced in 8 week-old male C57BL/6 mice by administering 100 mg/kg glyoxylate for 7 days. A total of 24 male C57BL/6 mice were randomly divided into a control group and the following experimental groups: 50 mg/kg normal saline + 100 mg/kg glyoxylate; 50 mg/kg dimethyl sulfoxide (DMSO) + 100 mg/kg glyoxylate; and 50 mg/kg SAHA + 100 mg/kg glyoxylate. The mice in each of the experimental groups were injected with the saline, DMSO or SAHA into their abdominal cavities 6 h prior to the glyoxylate injection. The mice were sacrificed after 7 days, following which blood and urine samples were collected. The kidneys were harvested to analyze the levels of calcium concentrations and the levels of malondialdehyde (MDA), superoxide dismutase and glutathione reductase. Immunohistochemical staining and semi-quantitative analyses were performed to detect the expression levels of osteopontin (OPN) and CD44. Renal tubular cell apoptosis was detectedusing a TUNEL assay. The concentrations of calcium and malondialdehyde were significantly decreased in the SAHA group, and calcium oxalate crystals in the kidney tissue and the expression levels of OPN and CD44 in the SAHA group were lower, compared with the other experimental groups. SAHA significantly reduced the urinary excretion of KIM-1 and renal tubular cell apoptosis. In conclusion, SAHA reduced calcium oxalate crystal deposition and protected against kidney injury.

Xanthine oxidase activity is associated with risk factors for cardiovascular disease and inflammatory and oxidative status markers in metabolic syndrome: effects of a single exercise session

Objective. The main goal of the present study was to investigate the xanthine oxidase (XO) activity in metabolic syndrome in subjects submitted to a single exercise session. We also investigated parameters of oxidative and inflammatory status. Materials/Methods. A case-control study (9 healthy and 8 MS volunteers) was performed to measure XO, superoxide dismutase (SOD), glutathione peroxidase activities, lipid peroxidation, high-sensitivity C-reactive protein (hsCRP) content, glucose levels, and lipid profile. Body mass indices, abdominal circumference, systolic and diastolic blood pressure, and TG levels were also determined. The exercise session consisted of 3 minutes of stretching, 3 minutes of warm-up, 30 minutes at a constant dynamic workload at a moderate intensity, and 3 minutes at a low speed. The blood samples were collected before and 15 minutes after the exercise session. Results. Serum XO activity was higher in MS group compared to control group. SOD activity was lower in MS subjects. XO activity was correlated with SOD, abdominal circumference, body mass indices, and hsCRP. The single exercise session reduced the SOD activity in the control group. Conclusions. Our data support the association between oxidative stress and risk factors for cardiovascular diseases and suggest XO is present in the pathogenesis of metabolic syndrome.

Colony-stimulating factor-1 signaling suppresses renal crystal formation

We recently reported evidence suggesting that migrating macrophages (Mϕs) eliminate renal crystals in hyperoxaluric mice. Mϕs can be inflammatory (M1) or anti-inflammatory (M2), and colony-stimulating factor-1 (CSF-1) mediates polarization to the M2Mϕ phenotype. M2Mϕs promote renal tissue repair and regeneration, but it is not clear whether these cells are involved in suppressing renal crystal formation. We investigated the role of M2Mϕs in renal crystal formation during hyperoxaluria using CSF-1-deficient mice, which lack M2Mϕs. Compared with wild-type mice, CSF-1-deficient mice had significantly higher amounts of renal calcium oxalate crystal deposition. Treatment with recombinant human CSF-1 increased the expression of M2-related genes and markedly decreased the number of renal crystals in both CSF-1-deficient and wild-type mice. Flow cytometry of sorted renal Mϕs showed that CSF-1 deficiency resulted in a smaller population of CD11b(+)F4/80(+)CD163(+)CD206(hi) cells, which represent M2-like Mϕs. Additionally, transfusion of M2Mϕs into CSF-1-deficient mice suppressed renal crystal deposition. In vitro phagocytosis assays with calcium oxalate monohydrate crystals showed a higher rate of crystal phagocytosis by M2-polarized Mϕs than M1-polarized Mϕs or renal tubular cells. Gene array profiling showed that CSF-1 deficiency resulted in disordered M2- and stone-related gene expressions. Collectively, our results provide compelling evidence for a suppressive role of CSF-1 signaling in renal crystal formation.

A paracrine mechanism involving renal tubular cells, adipocytes and macrophages promotes kidney stone formation in a simulated metabolic syndrome environment

PURPOSE

We developed an in vitro system composed of renal tubular cells, adipocytes and macrophages to simulate metabolic syndrome conditions. We investigated the molecular communication mechanism of these cells and their involvement in kidney stone formation.

MATERIALS AND METHODS

Mouse renal tubular cells (M-1) were cocultured with adipocytes (3T3-L1) and/or macrophages (RAW264.7). Calcium oxalate monohydrate crystals were exposed to M-1 cells after 48-hour coculture and the number of calcium oxalate monohydrate crystals adherent to the cells was quantified. The expression of cocultured medium and M-1 cell inflammatory factors was analyzed by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively.

RESULTS

The inflammatory markers MCP-1, OPN and TNF-α were markedly up-regulated in cocultured M-1 cells. OPN expression increased in M-1 cells cocultured with RAW264.7 cells while MCP-1 and TNF-α were over expressed in M-1 cells cocultured with 3T3-L1 cells. Coculturing M-1 cells simultaneously with 3T3-L1 and RAW264.7 cells resulted in a significant increase in calcium oxalate monohydrate crystal adherence to M-1 cells.

CONCLUSIONS

Inflammatory cytokine changes were induced by coculturing renal tubular cells with adipocytes and/or macrophages without direct contact, indicating that crosstalk between adipocytes/macrophages and renal tubular cells was mediated by soluble factors. The susceptibility to urolithiasis of patients with metabolic syndrome might be due to aggravated inflammation of renal tubular cells triggered by a paracrine mechanism involving these 3 cell types.

Novel osmotin attenuates glutamate-induced synaptic dysfunction and neurodegeneration via the JNK/PI3K/Akt pathway in postnatal rat brain

The glutamate-induced excitotoxicity pathway has been reported in several neurodegenerative diseases. Molecules that inhibit the release of glutamate or cause the overactivation of glutamate receptors can minimize neuronal cell death in these diseases. Osmotin, a homolog of mammalian adiponectin, is a plant protein from Nicotiana tabacum that was examined for the first time in the present study to determine its protective effects against glutamate-induced synaptic dysfunction and neurodegeneration in the rat brain at postnatal day 7. The results indicated that glutamate treatment induced excitotoxicity by overactivating glutamate receptors, causing synaptic dysfunction and neuronal apoptosis after 4 h in the cortex and hippocampus of the postnatal brain. In contrast, post-treatment with osmotin significantly reversed glutamate receptor activation, synaptic deficit and neuronal apoptosis by stimulating the JNK/PI3K/Akt intracellular signaling pathway. Moreover, osmotin treatment abrogated glutamate-induced DNA damage and apoptotic cell death and restored the localization and distribution of p53, p-Akt and caspase-3 in the hippocampus of the postnatal brain. Finally, osmotin inhibited glutamate-induced PI3K-dependent ROS production in vitro and reversed the cell viability decrease, cytotoxicity and caspase-3/7 activation induced by glutamate. Taken together, these results suggest that osmotin might be a novel neuroprotective agent in excitotoxic diseases.

Effects of fenofibrate on adiponectin expression in retinas of streptozotocin-induced diabetic rats

Adiponectin has been associated with increased risks of microvascular complications in diabetes; however, its role in the development of diabetic retinopathy (DR) is unknown. Fenofibrate is a lipid-lowering agent that has been shown to be capable of preventing DR progression. We investigated the expression of adiponectin and its receptors in DR and evaluated the effects of fenofibrate on their expression. The mRNA and protein levels of adiponectin and its receptors were elevated in retinas of streptozotocin-induced diabetic rats and were suppressed following fenofibrate treatment. Immunofluorescence staining demonstrated that adiponectin and adipoR1 were expressed in cells located within blood vessels, the retinal ganglion, and the inner nuclear layer. AdipoR1 was strongly expressed whereas adipoR2 was only weekly expressed in vascular endothelial cells. The in vitro experiments showed that adiponectin expression was induced by high glucose concentrations in RGC-5 and RAW264.7 cells and was suppressed following fenofibrate treatment. AdipoR1 and adipoR2 levels in RGC-5 cells were elevated in high glucose concentrations and suppressed by fenofibrate. Our results demonstrated that adiponectin may be a proinflammatory mediator in diabetic retinas and fenofibrate appears to modulate the expression of adiponectin and its receptors in diabetic retinas, effectively reducing DR progression.

Biomolecular mechanism of urinary stone formation involving osteopontin

Urinary stones consist of two phases-an inorganic (mineral) phase and an organic (matrix) phase. Studies on the organic components of kidney stones have been undertaken later than those on the inorganic components. After osteopontin was identified as one of the matrix components, the biomolecular mechanism of urinary stone formation became clearer. It also triggered the development of new preventive treatments. Osteopontin expression is sporadically observed in normal distal tubular cells and is markedly increased in stone-forming kidneys. Calcium oxalate crystals adhering to renal tubular cells are incorporated into cells by the involvement of osteopontin. Stimulation of crystal-cell adhesion impairs the opening of mitochondrial permeability transition pores (mPTP) in tubular cells and produces oxidative stress, apoptosis, and osteopontin expression. Macrophages phagocytose and digest a small amount of crystals, but many crystals aggregate into a mass containing osteopontin and epithelial cell debris and are excreted into the renal tubular lumen, becoming nuclei of urinary stones. This biomolecular mechanism is similar to atherosclerotic calcification. Based on these findings, new preventive treatments have been developed. Dietary control such as low-cholesterol intake and the ingestion of antioxidative foods and vegetables have successfully reduced the 5-year recurrence rate. Osteopontin antibodies and cyclosporine A, which blocks the opening of mPTP, have markedly inhibited the expression of osteopontin and urinary stone formation in animal models.