BACKGROUND: Renal osteodystrophy (ROD) is a skeletal pathology associated with chronic kidney disease-mineral and bone disorder (CKD-MBD) that is characterized by aberrant bone mineralization and remodeling. ROD increases the risk of fracture and mortality in CKD patients. The underlying mechanisms of ROD remain elusive, partially due to the absence of an appropriate animal model. To address this gap, we established a stable mouse model of ROD using an optimized adenine-enriched diet and conducted exploratory analyses through ribonucleic acid sequencing (RNA-seq). METHODS: Eight-week-old male C57BL/6J mice were randomly allocated into three groups: control group ( n = 5), adenine and high-phosphate (HP) diet group ( n = 20), and the optimized adenine-containing diet group ( n = 20) for 12 weeks. We assessed the skeletal characteristics of model mice through blood biochemistry, microcomputed tomography (micro-CT), and bone histomorphometry. RNA-seq was utilized to profile gene expression changes of ROD. We elucidated the functions of differentially expressed genes (DEGs) using gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and gene set enrichment analysis (GSEA). DEGs were validated via quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: By the fifth week, adenine followed by an HP diet induced rapid weight loss and high mortality rates in the mouse group, precluding further model development. Mice with optimized adenine diet-induced ROD displayed significant abnormalities in serum creatinine and blood urea nitrogen levels, accompanied by pronounced hyperparathyroidism and hyperphosphatemia. The femur bone mineral density (BMD) of the model mice was lower than that of control mice, with substantial bone loss and cortical porosity. ROD mice exhibited substantial bone turnover with an increase in osteoblast and osteoclast markers. Transcriptomic profiling revealed 1907 genes with upregulated expression and 723 genes with downregulated expression in the femurs of ROD mice relative to those of control mice. Pathway analyses indicated significant enrichment of upregulated genes in the sphingolipid metabolism pathway. The significant upregulation of alkaline ceramidase 1 ( Acer1 ), alkaline ceramidase 2 ( Acer2 ), prosaposin-like 1 ( Psapl1 ), adenosine A1 receptor ( Adora1 ), and sphingosine-1-phosphate receptor 5 ( S1pr5 ) were successfully validated in mouse femurs by qRT-PCR. CONCLUSIONS Optimized adenine diet mouse model may be a valuable proxy for studying ROD. RNA-seq analysis revealed that the sphingolipid metabolism pathway is likely a key player in ROD pathogenesis, thereby providing new avenues for therapeutic intervention.
Animals ; Mice ; Chronic Kidney Disease-Mineral and Bone Disorder/genetics* ; Male ; Disease Models, Animal ; Mice, Inbred C57BL ; Sphingolipids/metabolism* ; Transcriptome/genetics* ; Signal Transduction/genetics* ; X-Ray Microtomography ; Adenine

Objective:To explore the correlation between serum nidogen-2 (NID-2) and thoracic aortic calcification in patients with chronic kidney disease (CKD), and construct a risk prediction model based on NID-2 to evaluate its value in predicting the risk of the severe thoracic aortic calcification and cardiovascular and cerebrovascular events in CKD patients.Methods:It was a prospective cohort study. Patients with CKD at stage 3 to 5D in the Zhongda Hospital Affiliated to Southeast University from January 2022 to January 2023 were enrolled. Syngo.via software was used to evaluate the volume of thoracic aortic calcification, and enzyme-linked immunosorbent assay was employed to determine the level of serum NID-2. According to the volume of thoracic aortic calcification, the patients were divided into three groups: no calcification group, mild calcification group and severe calcification group. The top 25% of the patients were defined as no or mild calcification group, and the latter 75% were defined as severe calcification group. The follow-up period was one year. During the follow-up period, cardiovascular and cerebrovascular events, as well as all-cause death among the enrolled patients were recorded. Logistic regression analysis was used to screen the influencing factors of thoracic aortic calcification. Based on the results of logistic regression analysis, a nomogram prediction model was constructed. The receiver operating characteristic curve (ROC curve), calibration curve, and decision curve were employed to evaluate the discrimination, calibration and clinical practicality of the nomogram model.Results:A total of 132 patients were included, with 91 males (68.94%) and age of (56.51±16.37) years. There were 60 CKD 3-5 stage patients (non-dialysis, 45.45%) and 72 CKD 5D patients (dialysis, 54.55%). Serum ND-2 levels differed significantly among healthy individuals, dialysis patients and non-dialysis patients ( H=70.651, P<0.001). There was no statistically significant difference in serum NID-2 level between the no or mild calcification group and the severe calcification group in dialysis patients ( Z=350.00, P=0.426). The serum NID-2 level in the severe calcification group was significantly higher than that in the no or mild calcification group in non-dialysis patients ( Z=242.00, P=0.019). In non-dialysis patients, there was a statistically significant correlation between serum NID-2 level and volume of thoracic aortic calcification ( r=0.40, P<0.001). In dialysis patients, there was no statistically significant correlation between serum NID-2 level and volume of each segment of thoracic aortic calcification (all P>0.05). The univariate logistic regression analysis showed that, age, hemoglobin, serum albumin, estimated glomerular filtration rate, NID-2, hypertension, type 2 diabetes mellitus and cerebral infarction were correlated factors of thoracic aortic calcification in non-dialysis patients (all P<0.05). Multivariate logistic regression analysis showed that age ( OR=1.22, 95% CI 1.08-1.50, P=0.010) was an independent correlated factor of thoracic aortic calcification in non-dialysis patients. The above related variables of univariate logistic regression analysis were incorporated into a nomogram to construct a predictive model for severe vascular calcification in non-dialysis patients, yielding an AUC of 0.94 (95% CI 0.89-0.99) in ROC curve, with a sensitivity of 83% and a specificity of 95%. A nomogram model based on above variables for predicting cardiovascular and cerebrovascular events in non-dialysis patients demonstrated an AUC of 0.95 (95% CI 0.90-1.00) in ROC curve, with a sensitivity of 95% and a specificity of 87%. Conclusions:In non-dialysis patients, serum NID-2 level in the severe calcification group is significantly higher than that in the no or mild calcification group. The serum NID-2 is a related factor of thoracic aortic calcification and cardiovascular and cerebrovascular events in non-dialysis patients. The nomogram prediction model constructed by combining NID-2 with age, hemoglobin, serum albumin, estimated glomerular filtration rate, hypertension, type 2 diabetes mellitus and cerebral infarction has a high predictive value for the risk of thoracic aortic calcification as well as cardiovascular and cerebrovascular events in non-dialysis patients.

Objective:To explore the correlation between serum nidogen-2 (NID-2) and thoracic aortic calcification in patients with chronic kidney disease (CKD), and construct a risk prediction model based on NID-2 to evaluate its value in predicting the risk of the severe thoracic aortic calcification and cardiovascular and cerebrovascular events in CKD patients.Methods:It was a prospective cohort study. Patients with CKD at stage 3 to 5D in the Zhongda Hospital Affiliated to Southeast University from January 2022 to January 2023 were enrolled. Syngo.via software was used to evaluate the volume of thoracic aortic calcification, and enzyme-linked immunosorbent assay was employed to determine the level of serum NID-2. According to the volume of thoracic aortic calcification, the patients were divided into three groups: no calcification group, mild calcification group and severe calcification group. The top 25% of the patients were defined as no or mild calcification group, and the latter 75% were defined as severe calcification group. The follow-up period was one year. During the follow-up period, cardiovascular and cerebrovascular events, as well as all-cause death among the enrolled patients were recorded. Logistic regression analysis was used to screen the influencing factors of thoracic aortic calcification. Based on the results of logistic regression analysis, a nomogram prediction model was constructed. The receiver operating characteristic curve (ROC curve), calibration curve, and decision curve were employed to evaluate the discrimination, calibration and clinical practicality of the nomogram model.Results:A total of 132 patients were included, with 91 males (68.94%) and age of (56.51±16.37) years. There were 60 CKD 3-5 stage patients (non-dialysis, 45.45%) and 72 CKD 5D patients (dialysis, 54.55%). Serum ND-2 levels differed significantly among healthy individuals, dialysis patients and non-dialysis patients ( H=70.651, P<0.001). There was no statistically significant difference in serum NID-2 level between the no or mild calcification group and the severe calcification group in dialysis patients ( Z=350.00, P=0.426). The serum NID-2 level in the severe calcification group was significantly higher than that in the no or mild calcification group in non-dialysis patients ( Z=242.00, P=0.019). In non-dialysis patients, there was a statistically significant correlation between serum NID-2 level and volume of thoracic aortic calcification ( r=0.40, P<0.001). In dialysis patients, there was no statistically significant correlation between serum NID-2 level and volume of each segment of thoracic aortic calcification (all P>0.05). The univariate logistic regression analysis showed that, age, hemoglobin, serum albumin, estimated glomerular filtration rate, NID-2, hypertension, type 2 diabetes mellitus and cerebral infarction were correlated factors of thoracic aortic calcification in non-dialysis patients (all P<0.05). Multivariate logistic regression analysis showed that age ( OR=1.22, 95% CI 1.08-1.50, P=0.010) was an independent correlated factor of thoracic aortic calcification in non-dialysis patients. The above related variables of univariate logistic regression analysis were incorporated into a nomogram to construct a predictive model for severe vascular calcification in non-dialysis patients, yielding an AUC of 0.94 (95% CI 0.89-0.99) in ROC curve, with a sensitivity of 83% and a specificity of 95%. A nomogram model based on above variables for predicting cardiovascular and cerebrovascular events in non-dialysis patients demonstrated an AUC of 0.95 (95% CI 0.90-1.00) in ROC curve, with a sensitivity of 95% and a specificity of 87%. Conclusions:In non-dialysis patients, serum NID-2 level in the severe calcification group is significantly higher than that in the no or mild calcification group. The serum NID-2 is a related factor of thoracic aortic calcification and cardiovascular and cerebrovascular events in non-dialysis patients. The nomogram prediction model constructed by combining NID-2 with age, hemoglobin, serum albumin, estimated glomerular filtration rate, hypertension, type 2 diabetes mellitus and cerebral infarction has a high predictive value for the risk of thoracic aortic calcification as well as cardiovascular and cerebrovascular events in non-dialysis patients.

Objective:To identify the risk factors, and develop and validate a risk prediction model for abnormal bone mass in end-stage renal disease (ESRD) patients.Methods:It was a retrospective cross-sectional study. The clinical and laboratory data of ESRD patients who were hospitalized in the Department of Nephrology, Zhongda Hospital Affiliated to Southeast University from January 2022 to May 2023 were collected retrospectively. The patients were randomly divided into training and validation cohorts at a ratio of 7∶3. They were further divided into normal and abnormal bone mass groups according to the T value measured by dual-energy X-ray absorptiometry (DXA). Then, backward stepwise regression and least absolute shrinkage and selection operator (LASSO) were respectively used to develop the risk prediction model for abnormal bone mass in ESRD patients. Akaike information criterion (AIC), bayesian information criterion (BIC), and accuracy were used to evaluate the performance of these two models, after which the preferable model was selected. Moreover, the receiver operating characteristic (ROC) curve, calibration curve, Hosmer-Lemeshow test, and decision curve analyses (DCA) were applied to evaluate the diagnostic performance of the preferable model. Finally, a dynamic nomogram for individual assessment was constructed based on the preferable model.Results:A total of 254 ESRD patients were enrolled, including 160 (63.0%) males, 161 (63.4%) hemodialysis patients, and 202 (79.5%) patients with abnormal bone mass. There was no significant difference in the prevalence of abnormal bone mass between training group ( n=178) and validation group ( n=76) (79.2% vs. 80.3%, χ2=0.036, P=0.849). The final variables and variable parameters included in the LASSO and stepwise regression models were the same, which were five variables: age, body mass index, hypertension, diabetes, and osteocalcin. Both models also had the same AIC, BIC, and accuracy in the training group, which were 113.45, 132.54, and 0.837, respectively. Therefore, the LASSO model and the stepwise regression model performed consistently in this study and could be considered as the same model, hereafter referred to as the Model. The Model's area under the ROC curve in the training and validation groups was 0.923 (95% CI 0.884-0.963) and 0.809 (95% CI 0.675-0.943), respectively. The optimal cutoff for the training group was 0.858, with a sensitivity of 0.801, a specificity of 0.973 and an accuracy of 0.837; when this cutoff value was taken, the validation group's sensitivity was 0.689, specificity was 0.800, and accuracy was 0.711. The Model demonstrated excellent performance in the calibration curve, Hosmer-Lemeshow test ( P>0.05), and DCA. Finally, based on the five predictors of the Model, a dynamic nomogram was created for clinicians to enter baseline clinical parameters for early identification of high-risk patients with abnormal bone mass. Conclusions:A dynamic nomogram for abnormal bone mass in ESRD patients is constructed with good predictive performance based on the prediction model, which can be used as a practical approach for the personalized early screening and auxiliary diagnosis of the potential risk factors and assist physicians in making a personalized diagnosis for patients.

Objective To investigate whether elevated parathyroid hormone (PTH) levels could induce endothelial - to - mesenchymal transition (EndMT) and adipocyte transition in endothelial cells (ECs), and to determine the possible underlying mechanism. Methods (1) A rat model of secondary hyperparathyroidism and chronic kidney disease (CKD) was established. The adiposity in bone marrow was detected by oil red O staining. Immunofluorescence staining was performed to detect the expression and localization of cluster of differentiation 31 (CD31) and fibroblast-specific protein 1 (FSP1). (2) The human umbilical vein ECs were cultured in vitro. Western blotting was performed to detect protein expressions of EndMT-related markers CD31, FSP1 and α-smooth muscle actin (α-SMA) in interference groups with different PTH concentrations (0, 10-11, 10-9, 10-7 mol/L PTH for 48 h) and times (0, 12, 24, 48 h, 10-7 mol/L PTH), as well as the expression of β-catenin in interference groups with different PTH concentrations. The localizations of CD31, FSP1 and β - catenin were observed by cell immunofluorescence. Protein expressions of adipocytes markers peroxisome proliferator - activated receptor-γ (PPAR-γ) and CCAAT/enhancer binding protein-α (C/EBP-α) by Western blotting and the degree of adipogenesis by oil red O staining were detected after transformed ECs were cultured in adipogenic culture medium for one week. Small interfering RNA (siRNA) was performed to silenceβ - catenin expression. ECs were divided into control siRNA group, β - catenin siRNA group, PTH +control siRNA group and PTH+β-catenin siRNA group. Protein expressions of CD31, FSP1 and PPAR-γby Western blotting and the degree of adipogenesis by oil red O staining were determined. Results (1) In vivo, compared with the control, CKD rats had increased adipocytes in bone marrow (P＜0.05), and the co-expression of CD31 and FSP1 in bone marrow ECs. (2) In vitro, PTH significantly inhibited the expression of endothelial marker CD31 and increased the expressions of mesenchymal markers FSP1 and α-SMA in concentration-and time-dependent manners. These indexes in 10-7 mol/L PTH group and 0 mol/L PTH group, in 48 h group and 0 h group showed statistical differences (all P＜0.05). In PTH group ECs with 10-7 mol/L PTH for 48 h showed FSP1 accumulation in the cytoplasm and reduced expressions of CD31, and ECs had higher expressions of PPAR-γ and C/EBP-α as well as the degree of adipogenesis than those in control group (all P＜0.05). Furthermore, PTH enhanced the nuclearβ-catenin protein levels in ECs in concentration-dependent. The expressions of β-catenin in 10-7 mol/L PTH group and 0 mol/L PTH group showed statistical differences (P＜0.05). β - catenin expressed in the cytoplasm in control group, while it enter into the nucleus in PTH group. Compared with those in PTH+control siRNA group, the expressions of CD31 and PPAR-γ as well as the degree of adipogenesis decreased in PTH+β-catenin siRNA group (all P＜0.05), while the expression of FSP1 increased (P＜0.05). Conclusions PTH induces ECs - to - adipocytes transition by the canonical Wnt/β - catenin signaling pathway, which might account for bone loss in CKD. Silenced β - catenin expression can inhibit PTH-induced EndMT and adipogenesis.

Objective To explore the effect of irbesartan on cardiac endothelial-mesenchymal transition (EndMT) in diabetic rats.Methods The model of diabetic rat was induced by intraperitoneal injection with streptozotocin (STZ,35 mg/kg) in spontaneous hypertensive rats (SHR).Diabetic rats were divided into diabetic group and the Irbesartan treated group.The pathological changes were investigated by fluorescence microscope and electron microscope.The EndMT was studied in human aortic endothelial cells (HAEC) exposure to high glucose.The concentration of angiotensin Ⅱ in the supernatant was detected by radioimmunoassay.Immunofluorescence staining was performed to detect the co-localization of CD31 and FSP1.Results The significant myocardial fibrosis was presented in the diabetic group.Endothelial protrusions were prominent feature in myocardial microvascular of diabetic rat compared with the control group rats.Double staining of HAEC showed co-localization of CD31 and FSP1,which was decreased by the treatment of Irbesartan (P ＜ 0.05).When HAEC was exposed to high glucose,it showed some cells acquired spindle-shaped morphology and lost CD31 staining,and FSP1 and α-SMA protein expression levels were markedly upregulated,which attenuated by the treatment of Irbesartan.Conclusion Irbesartan might prevent diabetes from myocardial fibrosis via inhibition of EndMT in diabetic rats.

Objective To explore whether high glucose (HG)-induced endothelial-to-mesenchymal transition (EndMT) could be transitioned into mesenchymal stem cells (MSCs) and further differentiated into chondrocytes.Methods Human aortic endothelial cells (HAECs) were divided into three groups:normal glucose (NG,5.5 mmol/L glucose) group,HG (30 mmol/L glucose) group,and mannitol (5.5 mmol/L glucose + 24.5 mmol/L mannitol) group,and were cultured for 48 h.Immunofluorescence staining was performed to detect the co-expression of CD31 (endothelial markers),and fibroblast-specific protein 1 (FSP1,fibroblast markers).The expression of CD31 and FSP1 mRNA and protein was detected by real-time PCR and Western blotting.When endothelial-derived MSCs were grown in MSC medium for one week,the expression of the MSCs markers CD44,CD10 and the chondrocyte marker SOX9 was detected by Western blotting and RT-PCR.Chondrocyte expression was detected by alcian blue staining.Calcium deposit was analyzed by alizarin red staining.Pathological changes were investigated using electron microscopy.Results The expression of FSP1 mRNA and protein was significantly increased,but the expression of CD31 mRNA and protein was decreased (P ＜0.01),and the cells undergoing EndMT also significantly expressed CD10,CD44 and SOX9 in the HG group compared with those in normal glucose group (P ＜ 0.01).The incubation of HAECs exposed to HG resulted in a fibroblast-like phenotype,wherein increased microfilamentation and a roughened endoplasmic reticulum structure were observed in the cytoplasm.Double staining of the HAECs indicated a co-localization of CD31 and FSP1.After one week culture for chondrocyte medium,the expression of MSCs marker STRO-1 was significantly increased by immunofluorescence staining.Additionally,aleian blue staining in the HG group was positive compared to the NG group.Consistent with the elevation of SOX9 expression,calcium deposit also enhanced in the HG group.Conclusion HG can induce endothelial cells transdifferentiation into chondrocyte-like cells via the EndMT.

Objective To develop a model of type 2 diabetes with early renal injury on spontaneously hypertensive rats (SHR). Methods The 6-week old SHR were fed with the diets enriched with sucrose (20%, W/W), lard (10%, W/W), cholesterol (2.5%, W/W) and chleolate (1%, W/W) to induce insulin resistance. Hyperglycemia was developed by intraperitoneal injection of streptozotocin (STZ, 35 mg/kg). Wistar-Kyoto rats (WKY) were used as normal controls. Rats with plasma glucose (PGL) ≥ 16.7 mmol/L were diagnosed as diabetes. Eight weeks after the induction of diabetes, plasma triglyceride (TG), cholesterol (CHO), glucose, systolic pressure(SP), 24-h urine protein excretion (Upro) were examined in all the rats, and the homeostasis model assessment of insulin resistance (HOMA-IR) was analyzed. Renal pathological changes were studied by immunohistochemical staining and electron microscope. Results After 2 weeks on the high sucrose and fat diets, the model rats exhibited significant increase in basal PGL, TG and CHO levels as compared to control rats (P<0.05, respectively). The insulin resistance was developed in model rats demonstrated by the higher HOMA-IR (5.03±0.38 vs 2.61±0.34, P<0.05). At the end of the experiment, model rats were associated with hypertension. Upro level was significantly increased in model rats compared with that in controls [(57.58±16.54) mg/24 h vs (5.35±1.90) mg/24 h, P<0.01]. The kidney hypertrophy index (KWI) was significantly increased in the model rats compared to controls (P <0.05). Moreover, the diabetic model rats showed glomerular hypertrophy, foot process effacement, micro villous transformation, glomerular basement membrane (GBM) thickening. Conclusion A rat model is successfully established, which presents typical features of human type 2 diabetes and can be served as an ideal model to study the diabetic nephropathy.