[Clinical Significance of Thrombospondin Type 1 Domain-Containing 7A and Neural Epidermal Growth Factor-Like 1 Protein in M-Type Phospholipase A2 Receptor-Negative Membranous Nephropathy].

Objective To investigate the clinical significance of thrombospondin type 1 domain-containing 7A (THSD7A) and neural epidermal growth factor-like 1 protein (NELL1) in phospholipase A2 receptor (PLA2R)-negative membranous nephropathy (MN). Methods A total of 116 PLA2R-negative MN patients treated in Hangzhou TCM Hospital Affiliated to Zhejiang Chinese Medical University from 2014 to 2021 were enrolled in this study.Immunohistochemistry was employed to detect THSD7A and NELL1 in the renal tissue.The pathological characteristics,treatment,and prognosis were compared between positive and negative groups. Results The 116 PLA2R-negative MN patients included 23 THSD7A-positive patients and 9 NELL1-positive patients.One patient was tested positive for both proteins.The THSD7A-positive group showed higher positive rate of IgG4 (P=0.010),more obvious glomerular basement membrane (GBM) thickening (P=0.034),and higher proportion of stage Ⅱ MN and lower proportion of stage I MN (P=0.002) than the THSD7A-negative group.The NELL1-positive group had lower positive rates of C1q and IgG2 (P=0.029,P=0.001),less obvious GBM thickening (P<0.001),more extensive inflammatory cell infiltration (P=0.033),lower proportion of deposits on multi-locations (P=0.001),and lower proportion of atypical MN (P=0.010) than the NELL1-negative group.One patient with THSD7A-positive MN was diagnosed with colon cancer,while none of the NELL1-positive patients had malignancy.Survival analysis suggested that THSD7A-positive MN had worse composite remission (either complete remission or partial remission) of nephrotic syndrome than the negative group (P=0.016),whereas NELL1-positive MN exhibited better composite remission of nephrotic syndrome than the negative group (P=0.015).The MN patients only positive for NELL1 showed better composite remission of nephrotic syndrome than the MN patients only positive for THSD7A (P<0.001). Conclusions THSD7A- and NELL1-positive MN is more likely to be primary MN,and there is no significant malignancy indication.However,it might have a predictive value for the prognosis of MN.

Renal Interstitial Inflammation Predicts Nephropathy Progression in IgA Nephropathy: A Two-Center Cohort Study.

INTRODUCTION: Renal interstitial inflammation often presents in immunoglobulin A nephropathy (IgAN), but its predictive role in kidney disease progression remains controversial. METHODS: This retrospective two-center cohort study included 1,420 adult IgAN patients between January 2003 and May 2018 followed for a median of approximately 7 years at two Chinese hospitals. The predictor was renal interstitial inflammation within the total cortical interstitium (none/mild [0-25%], moderate [26-50%], or severe [>50%]). For the further propensity score matching analyses, the participants with moderate and severe level of interstitial inflammation were pooled to match those with none/mild level of interstitial inflammation. The outcomes included the rate of kidney function decline, and the composite kidney endpoint event defined as a >40% reduction in the estimated glomerular filtration rate, end-stage kidney disease. Linear regression and Cox proportional hazards regression analyses were used to examine the association between interstitial inflammation and the outcomes. The predictive performance of the model also assessed using multivariate logistic regression analyses with the receiver operating characteristic curve analysis. Reclassification was assessed using the continuous net reclassification improvement and integrated discrimination improvement adapted for censoring for the assessment of the model with or without interstitial inflammation. RESULTS: For the check of reproducibility, the kappa statistic was 0.71, and intraclass correlation coefficient was 0.77. After adjustment for relating covariates, a higher level of interstitial inflammation was associated with a faster rate of kidney function decline (eGFR slope [mL/min/1.73 m2] of 1.34 [95% CI: -2.56 to 5.23], 3.50 [95% CI: -0.40 to 7.40], and 7.52 [95% CI: 3.02 to 12.01]) in the patients with none/mild, moderate, and severe interstitial inflammation, respectively, in the multivariable linear regression models and with an increased risk of kidney disease progression (HR for moderate vs. none/mild, 1.85; 95% CI: 1.10-3.13; HR for severe vs. none/mild, 2.95; 95% CI: 1.52-5.73) in the multivariable Cox proportional hazards models. Analyses in the propensity score-matched cohort, subgroups, and the sensitive analyses yielded consistent results. The receiver operating curves indicated a higher area under the curve of 0.83 in the model with interstitial inflammation compared with 0.81 in that without interstitial inflammation. In addition, incorporating interstitial inflammation into the International IgAN Risk Prediction Tool improved the diagnostic power of the algorithm to predict risk of progression. CONCLUSION: Interstitial inflammation is a reproducible pathologic parameter that may be adopted as a predictor for kidney disease progression in patients with IgAN.

[Clinical Significance of IgG4 Level in Predicting the Activity and Outcome of Phospholipase A2 Receptor-associated Membranous Nephropathy].

Objective To investigate the feasibility of IgG4 as a biomarker of the activity and outcome of phospholipase A2 receptor (PLA2R)-associated membranous nephropathy (PLA2R-MN). Methods Serum and urine samples were collected from 56 patients with PLA2R-MN,13 patients with secondary membranous nephropathy (SMN),and 10 patients with primary IgA nephropathy (IgAN) when kidney biopsy was performed in the Department of Nephrology,Hangzhou Hospital of Traditional Chinese Medicine from April 2017 to January 2018.Sandwich enzyme-linked immunosorbent assay was employed to measure the serum and urinary IgG4 levels. Results The PLA2R-MN group had higher median serum IgG4/IgG ratio than the SMN group (P=0.009) and the IgAN group (P<0.001) and higher median urinary IgG4/creatinine ratio than the SMN group (P=0.008).In the patients with PLA2R-MN,the median serum IgG4/IgG ratio and urinary IgG4/creatinine ratio were significantly higher in the renal insufficiency group than in the normal renal function group (P=0.049,P=0.015).Moreover,the median serum IgG4/IgG ratio was higher in those with a serum albumin level<30 g/L than in those with a serum albumin level ≥30 g/L (P=0.005).Fifty-three patients with PLA2R-MN were followed up for at least 1 year,and the serum IgG4/IgG ratios of the patients in remission were lower than those of the patients without remission (P=0.005).The median serum IgG4/IgG ratio of 23 patients in remission decreased from 5.82% (4.54%,10.20%)(at initial enrollment) to 2.91% (2.11%,5.37%)(after 1-year follow up) in remission patients (P<0.001).The receiver operating characteristic curve showed that the patients with a serum IgG4/IgG ratio<10.24% had a higher possibility of remission (P=0.005). Conclusion Serum and urinary IgG4 levels may be an indicator of the activity in PLA2R-MN patients and thus may be a predictive biomarker of the outcomes.

The Association of Low Hemoglobin Levels with IgA Nephropathy Progression: A Two-Center Cohort Study of 1,828 Cases.

AIM: To investigate the relationship between hemoglobin levels and the progression of IgA nephropathy (IgAN). METHODS: In a two-center cohort of 1,828 cases with biopsy-proven IgAN, we examined the association of hemoglobin levels with the primary outcome of a composite of all-cause mortality or kidney failure defined as a 40% decline in eGFR, or ESKD (defined as eGFR <15 mL/min/1.73 m2 or need for kidney replacement therapy including hemodialysis, peritoneal dialysis, or kidney transplantation), or the outcome of kidney failure, assessed using Cox and logistic regression models, respectively, with adjustment for confounders. RESULTS: At baseline, mean age, eGFR, and hemoglobin levels were 33.75 ± 11.03 years, 99.70 ± 30.40 mL/min/1.73 m2, and 123.47 ± 18.36 g/L, respectively. During a median of approximately 7-year follow-up, 183 cases reached the composite outcome. After adjustment for demographic and IgAN-specific covariates and treatments, a lower quartile of hemoglobin was nonlinearly associated with an increased risk of the primary outcome or kidney failure in the Cox proportional hazards models (primary outcome: HR for quartile 3 vs. 4, 1.37; 95% CI, 0.83-2.25; HR for quartile 2 vs. 4, 1.18; 95% CI, 0.68-2.07; HR for quartile 1 vs. 4, 1.91; 95% CI, 1.15-3.17; kidney failure: HR for quartile 3 vs. 4, 1.39; 95% CI, 0.84-2.31; HR for quartile 2 vs. 4, 1.20; 95% CI, 0.68-2.11; HR for quartile 1 vs. 4, 1.83; 95% CI, 1.09-3.07) in the fully adjusted model. Then, hemoglobin levels were transformed to a binary variable for fitting the model according to the criteria for anemia of 110 g/L in the women and 120 g/L in men in China. The participants in the anemia group had an increased risk of developing outcomes compared with the nonanemia group in both genders (primary outcome: male: HR, 1.64; 95% CI, 1.01-2.68; female: HR, 1.68; 95% CI, 1.02-2.76; kidney failure: male: HR, 1.60; 95% CI, 0.97-2.64; female: HR, 1.58; 95% CI, 0.95-2.61) in the fully adjusted model. CONCLUSIONS: A low level of hemoglobin was nonlinearly associated with IgAN progression. The anemic IgAN patients presented a higher risk of developing poor outcomes compared with the nonanemic patients.

The protective effect of Phellinus linteus decoction on podocyte injury in the kidney of FSGS rats.

BACKGROUND: This study aimed to investigate the effect of the Phellinus linteus (Mesima) decoction on podocyte injury in a rat model of focal and segmental glomerulosclerosis (FSGS) and evaluate the potential mechanisms. METHODS: FSGS resembling primary FSGS in humans was established in rats by uninephrectomy and the repeated injection of doxorubicin. The FSGS rats were randomly divided into the model group, low-dose group of P. linteus decoction (PLD-LD), medium-dose group of P. linteus decoction (PLD-MD), and high-dose group of P. linteus decoction (PLD-HD). Blood and urine analysis were performed after 12 weeks and the molecular indicators of renal function and the renal pathological changes were examined. RESULTS: FSGS developed within 12 weeks in the test group and showed progressive proteinuria and segmental glomerular scarring. Urinary protein, serum creatinine, urea nitrogen, triglycerides and cholesterol were significantly reduced following the 12-week intervention with P.linteus decoction, especially in the PLD-LD group. Renal nephrin and podocin were markedly increased. Moreover, the pathological damage in the renal tissue was alleviated by the PLD-LD intervention. CONCLUSION: The P. linteus decoction alleviated the podocyte injury in the FSGS rat model, thus minimizing the progression of glomerular sclerosis and improving renal function.

Uric Acid as a Predictor of Immunoglobulin A Nephropathy Progression: A Cohort Study of 1965 Cases.

BACKGROUND: The role of serum uric acid (SUA) level in the progression of Immunoglobulin A nephropathy (IgAN) remains controversial. METHODS: In a cohort of 1,965 cases with biopsy-proven IgAN, we examined the associations of SUA concentration with the primary outcome of a composite of all-cause mortality or kidney failure (defined as a reduction of estimated glomerular filtration rate [eGFR] by 40% from baseline, requirements for dialysis and transplantation), or the outcome of kidney failure alone, assessed using Cox and logistic regression models, respectively, with adjustment for confounders. RESULTS: At baseline, the mean age was 33.37 ± 11.07 years, eGFR was 101.30 ± 30.49 mL/min/1.73 m2, and mean uric acid level was 5.32 ± 1.76 mg/dL. During a median of 7-year follow-up, 317 cases reached the composite outcome of all-cause mortality (5 deaths) or kidney failure (36 cases of dialysis, 5 cases of renal transplantation, and 271 cases with reduction of eGFR by 40% from baseline). After adjustment for demographic and IgAN specific covariates and treatments, a higher quartile of uric acid was linearly associated with an increased risk of the primary outcome (highest versus lowest quartile, hazard ratio [HR] 2.39; 95% CI 1.52-3.75) and kidney failure (highest versus lowest quartile, HR 2.55; 95% CI 1.62-4.01) in the Cox proportional hazards regression models. In the continuous analysis, a 1 mg/dL greater uric acid level was associated with 16% increased risk of primary outcome (HR 1.16, 95% CI 1.07-1.25) and 17% increased risk of kidney failure (HR 1.17, 95% CI 1.08-1.27), respectively, in the fully adjusted model. The multivariate -logistic regression analyses for the sensitive analyses drew consistent results. In the subgroup analyses, significant interactions were detected that patients with mean arterial pressure (MAP) < 90 mm Hg or mesangial hypercellularity had a higher association of SUA with the incidence of the primary outcome than those with MAP ≥90 mm Hg or those without mesangial hypercellularity respectively. Hyperuricemia was not significantly associated with the risk of developing the primary outcome in elder patients (≥32 years old), patients with eGFR < 90 mL/min or with tubular atrophy/interstitial fibrosis. CONCLUSIONS: SUA level may be positively associated with the progression of IgAN. It was noticeable that the association of hyperuricemia with IgAN progression was less significant in patients with elder age, lower eGFR, or tubular atrophy/interstitial fibrosis, which may be due to some more confounders in association with the IgA progression in these patients. Future prospective studies are warranted to confirm these findings and to investigate the underlying mechanisms.

Bone marrow mesenchymal stem cells attenuate the progression of focal segmental glomerulosclerosis in rat models.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) is the most common glomerular etiology of end-stage kidney disease (ESKD). Increasing evidence has indicated the reparative potential of mesenchymal stem cells (MSCs) in damaged diseased kidneys. However, the effect of bone marrow mesenchymal stem cells (BMSCs) on the FSGS progression remains unclear. This study aimed to investigate the protective effects of BMSCs on FSGS progression. METHODS: A rat model of FSGS was generated via unilateral nephrectomy plus adriamycin injection. Rat BMSCs were isolated and characterized on the basis of their differentiative potential towards adipocytes and osteoblasts and via flow cytometry analysis. Thereafter, rat BMSCs were transplanted into FSGS recipients through the caudal vein. After 8 weeks, 24-h proteinuria, serum creatinine, and urea nitrogen levels were determined. Renal morphology was assessed using a light and transmission electron microscope. MMP9 and TIMP-1 positive cells were detected via immunohistochemical analysis. Expression levels of proinflammatory cytokines IL-6 and TNF-α were examined via RT-PCR. RESULTS: The isolated adherent cells from the bone marrow of rats were phenotypically and functionally equivalent to typical MSCs. Clinical examination revealed that BMSC transplantation reduced the 24-h urinary protein excretion, and serum creatinine and urea nitrogen levels. Renal morphology was ameliorated in BMSCs-transplanted rats. Mechanistically, BMSC transplantation significantly downregulated TIMP-1 and upregulated MMP9, thereby increasing the renal MMP9/TIMP-1 ratio. Moreover, BMSC transplantation also downregulated IL-6 and TNF-α. CONCLUSIONS: BMSC transplantation can attenuate FSGS progression in a rat model of FSGS, thereby providing a theoretical foundation for the application of autologous BMSCs in clinical FSGS therapy.

Clinical characteristics of IgA nephropathy associated with low complement 4 levels.

OBJECTIVE: C4 deficiency is the most commonly inherited immune disorder in human. The present study investigated the characteristics of the IgAN patients with low serum C4 levels. METHODS: We performed a prospective observational study. Clinical as well as histopathologic parameters were assessed. A Kaplan-Meier survival analysis was performed concerning the primary outcome defined as the serum creatinine increased 1.5-fold from baseline. The prognostic significances of clinical and histopathologic parameters were determined using Cox proportional hazards models. RESULTS: Five-hundred twelve biopsy proven IgAN cases were available for analysis with a median follow-up of 38.4 months. Ninety-nine cases (19.34%) presented with low C4 levels (LowC4 group) and the other 413 cases did not (NlowC4 group). At the time of renal biopsy, renal injury was lighter in the LowC4 group compared with the NlowC4 group. Renal C4 deposition was significantly decreased while IgM deposition was increased in the LowC4 group. A correlation analysis shows that lower C4 levels were associated with better renal presentations at biopsy. However, the risk of developing the primary outcome was significantly greater in those with low C4 levels. Specifically, during the follow-up period, the risk of developing primary outcome was nearly ten folds higher in those with low C4, compared to those without low C4. CONCLUSION: There is a high prevalence of low C4 levels in IgAN patients. These patients with low C4 levels exhibited better renal presentations at the time of renal biopsy, whereas might be associated with a poor prognosis.

Network Pharmacology, Molecular Docking, and Experimental Verification to Reveal the Mitophagy-Associated Mechanism of Tangshen Formula in the Treatment of Diabetic Nephropathy.

Purpose: This study investigated the mechanism of TSF in treating DN through network pharmacology, molecular docking, and experimental validation. Methods: To identify critical active ingredients, targets, and DN genes in TSF, multiple databases were utilized for screening purposes. The drug-compound-target network was constructed using Cytoscape 3.9.1 software for network topological analysis. The protein interaction relationship was analyzed using the String database platform. Metascape database conducted enrichment analysis on the key targets using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. The renoprotective effect was evaluated using a mouse model of diabetic nephropathy (db/db mice) that occurred spontaneously. Validation of the associated targets and pathways was performed using Western Blot (WB), Polymerase Chain Reaction (PCR), and Immunohistochemical methods (IHC). Results: The network analysis showed that the TSF pathway network targeted 24 important targets and 149 significant pathways. TSF might have an impact by focusing on essential objectives such as TP53, PTEN, AKT1, BCL2, BCL2L1, PINK-1, PARKIN, LC3B, and NFE2L2, along with various growth-inducing routes. Our findings demonstrated that TSF effectively repaired the structure of mitochondria in db/db mice. TSF greatly enhanced the mRNA levels of PINK-1. WB and IHC findings indicated that TSF had a notable impact on activating the PINK-1/PARKIN signaling pathway in db/db mice, significantly increasing LC3 and NRF2 expression. Conclusion: Our results indicate that TSF effectively addresses DN by activating the PINK-1/PARKIN signaling pathway and enhancing Mitochondrion structure in experimental diabetic nephropathy.

Heterozygous Gnaq deficiency enhances Ifi202b/IFI16 and NF-κB activation in endothelial cells and exacerbates lupus nephritis pathology.

Lupus nephritis (LN), a severe complication of systemic lupus erythematosus (SLE), exhibits significant heterogeneity. Recent evidence suggests that non-immune factors contribute to end-organ damage, challenging the traditional view of LN solely arising from immune dysregulation. To investigate this, we employed autoimmune-prone Gnaq +/- mice receiving intraperitoneal pristane injections. Bone marrow transfer (BMT) distinguished the roles of immune versus non-immune cells. We observed that: (1) BMT from wild-type (WT) mice to Gnaq +/- recipients resulted in severe proteinuria and diffuse proliferative nephritis after pristane exposure; (2) GNAQ knockdown increased the expression of IFI16/Ifi202b and activated the NF-κB pathway in endothelial cells; and (3) increased IFI16 expression in human kidney biopsies correlated with proliferative LN. Taken together, these findings suggest that GNAQ acts as an inflammatory regulator in kidney endothelial cells via the IFI16/NF-κB pathway, potentially linking it to the development of LN in humans.

MAPK1 Mediates MAM Disruption and Mitochondrial Dysfunction in Diabetic Kidney Disease via the PACS-2-Dependent Mechanism.

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD). Mitochondrial dysfunction in renal tubules, occurring early in the disease, is linked to the development of DKD, although the underlying pathways remain unclear. Here, we examine diabetic human and mouse kidneys, and HK-2 cells exposed to high glucose, to show that high glucose disrupts mitochondria-associated endoplasmic reticulum membrane (MAM) and causes mitochondrial fragmentation. We find that high glucose conditions increase mitogen-activated protein kinase 1(MAPK1), a member of the MAP kinase signal transduction pathway, which in turn lowers the level of phosphofurin acidic cluster sorting protein 2 (PACS-2), a key component of MAM that tethers mitochondria to the ER. MAPK1-induced disruption of MAM leads to mitochondrial fragmentation but this can be rescued in HK-2 cells by increasing PACS-2 levels. Functional studies in diabetic mice show that inhibition of MAPK1 increases PACS-2 and protects against the loss of MAM and the mitochondrial fragmentation. Taken together, these results identify the MAPK1-PACS-2 axis as a key pathway to therapeutically target as well as provide new insights into the pathogenesis of DKD.

Mitofusin2 expression is associated with podocyte injury in IgA nephropathy.

BACKGROUND: Podocyte injury is associated with IgA nephropathy (IgAN) prognosis. Mitochondrial dysfunction is a major contributor to podocyte injury and death. Mitofusin2 (Mfn2) plays an important role in regulating the morphology and function of mitochondria. This study aimed to investigate the potential of Mfn2 as a biomarker to evaluate the degree of podocyte injury. METHODS: This single-center, retrospective study enrolled 114 patients with biopsy-proven IgAN. Immunofluorescence and TUNEL staining were applied, and clinical and pathological features were compared between patients with different patterns of Mfn2 expression. RESULTS: In IgAN, Mfn2 is mainly expressed in podocytes and significantly associated with nephrin, TUNEL, and Parkin staining. Among the 114 IgAN patients, 28 (24.56%) did not exhibit Mfn2 expression in podocytes. The patients in the Mfn2-negative group had lower serum albumin (34.43 ± 4.64 g/L vs. 36.48 ± 3 .52 g/L, P = 0.015) and estimated glomerular filtration rate (eGFR) (76.59 ± 35.38 mL/min vs. 92.13 ± 25.35 mL/min, P = 0.013), higher 24 h proteinuria (2.48 ± 2.72 g/d vs. 1.27 ± 1.31 g/d, P = 0.002), serum creatinine (Scr) (107.39 ± 57.97 µmol/L vs. 84.70 ± 34.95 µmol/L, P = 0.015), blood urea nitrogen (BUN) (7.36 ± 4.45 mmol/L vs. 5.68 ± 2.14 mmol/L, P = 0.008), and higher S/T scores (92.86% vs. 70.93% and 42.85% vs. 15.12%, respectively, P < 0.05). In the Mfn2-negative group, the mitochondria were punctate and round ridges disappeared, and a lower length-to-width ratio and much higher M/A ratio were observed. Correlation analysis showed that the intensity of Mfn2 was negatively correlated with Scr (r = - 0.232, P = 0.013), 24 h proteinuria (r = - 0.541, P = 0.001), and the degree of podocyte effacement (r = - 0.323, P = 0.001), and positively correlated with eGFR (r = 0.213, P = 0.025). Logistic regression analysis showed that the Mfn2-negative group had a higher risk of severe podocyte effacement (≥ 50%) (OR = 3.061, P = 0.019). CONCLUSION: Mfn2 was negatively correlated with proteinuria and renal function. A lack of Mfn2 in podocytes indicates severe podocyte injury and a high degree of podocyte effacement.

Celastrol attenuates diabetic nephropathy by upregulating SIRT1-mediated inhibition of EZH2related wnt/ß-catenin signaling.

Proteinuria is an independent risk factor for the progression of diabetic nephropathy (DN) and an imbalance in podocyte function aggravates proteinuria. Celastrol is the primary active ingredient of T. wilfordii, effective in treating DN renal injury; however, the mechanisms underlying its effect are unclear. We explored how celastrol prevents DN podocyte damage using in vivo and in vitro experiments. We randomly divided 24 male C57BLKS/J mice into three groups: db/m (n = 8), db/db (n = 8), and celastrol groups (db/db + celastrol, 1 mg/kg/d, gavage administration, n = 8). In vivo experiments lasted 12 weeks and intervention lasted ten weeks. Serum samples and kidney tissues were collected for biochemical tests, pathological staining, transmission electron microscopy, fluorescencequantitation polymerase chain reaction, and western blotting analysis. In vitro experiments to elaborate the mechanism of celastrol protection were performed on high glucose (HG)-induced podocyte injury. Celastrol reduced blood glucose levels and renal function index in db/db mice, attenuated renal histomorphological injury and glomerular podocyte foot injuries, and induced significant anti-inflammatory effects. Celastrol upregulated silent information regulator 2 related enzyme 1(SIRT1) expression and downregulated enhancer of zeste homolog (EZH2), inhibiting the wnt/ß-catenin pathway-related molecules, such as wnt1, wnt7a, and ß-catenin. SIRT1 repressed the promoter activity of EZH2, and was co-immunoprecipitated with EZH2 in mouse podocyte cells (MPC5). SIRT1 knockdown aggravated the protective effects of celastrol on MPC5 cells. Celastrol protected podocyte injury via SIRT1/EZH2, which participates in the wnt/ß-catenin pathway. Overall, celastrol-mediated SIRT1 upregulation inhibited the EZH2-related wnt/ß-catenin signaling pathway to attenuate DN and podocyte injury, providing a theoretical basis for celastrol clinical application.

Clinical significance of exostosin 1 in confirmed and suspected lupus membranous nephropathy.

OBJECTIVE: This study aimed to investigate the clinical significance of exostosin 1 (EXT1) in confirmed and suspected lupus membranous nephropathy (LMN). METHODS: EXT1 was detected in 67 renal tissues of M-type phospholipase A2 receptor (PLA2R)-negative and ANA-positive membranous nephropathy by immunohistochemistry, and cases were divided into confirmed LMN and suspected LMN. The clinicopathological data were compared among the above groups, as well as EXT1-positive group and EXT1-negative group. RESULTS: Twenty-two cases (73.3%) of confirmed LMN and six cases (16.2%) of suspected LMN exhibited EXT1 expression on the glomerular basement membrane and/or mesangium area, showing a significant difference (p<0.001). Concurrently, lupus nephritis (LN) of pure class V demonstrated a lower frequency of EXT1 positivity compared with mixed class V LN in the confirmed LMN group (31.8% vs 68.2%, p=0.007). EXT1-positive patients in the confirmed and suspected LMN group showed significant differences in some clinicopathological data comparing with EXT1-negative patients (p<0.05). Follow-up data revealed that a greater proportion of patients in the EXT1-positive group achieved complete remission post-treatment (p<0.05). Cox regression analysis showed that EXT1 positivity was significantly correlated with complete remission across the entire study cohort (HR 5.647; 95% CI, 1.323 to 12.048; p=0.019). Kaplan-Meier analysis indicated that the EXT1-positive group had a higher rate of accumulated nephrotic remission compared with the EXT1-negative group in the whole study cohort (p=0.028). CONCLUSIONS: The EXT1-positive group exhibited a higher active index and a more favourable renal outcome than the EXT1-negative group. It would be better to recognise suspected LMN with EXT1 positivity as a potential autoimmune disease and maintain close follow-up due to its similarities with confirmed LMN.

The significance of galactose-deficient immunoglobulin A1 staining in kidney diseases with IgA deposition.

BACKGROUND: This study investigated the significance of galactose-deficient immunoglobulin A1 staining in kidney diseases with IgA deposition. METHODS: A total of 120 patients with IgA-dominant deposition in kidney tissues were enrolled and divided into four groups: primary IgA nephropathy (PIgAN), secondary IgA nephropathy (SIgAN), monotypic IgA nephropathy (MIgAN), and IgA variant monoclonal gammopathy of renal significance (IgA-MGRS). KM55 (the antibody of galactose-deficient immunoglobulin A1), IgA subtypes, and complement pathway factors (properdin, C4d, and C1q) were detected through immunofluorescence or immunohistochemistry analysis. RESULTS: KM55 and IgA double staining showed colocalization within glomeruli in all cases except for IgA-MGRS, which showed negative or weak staining of KM55 but strong staining of IgA. The PIgAN group showed the highest intensity of KM55 and KM55/IgA ratio, while these values in the IgA-MGRS group were the lowest (P < 0.01). A KM55/IgA quantified ratio of 0.78 was the optimal cut-off value to distinguish PIgAN from SIgAN, whereas a cut-off value of 0.21 was optimal to distinguish between MIgAN and IgA-MGRS. The clinicopathological characteristics showed significant differences as the groups were divided by diseases with optimal cut-off values, and these differences corresponded to the pathogenesis of each disease entity. CONCLUSIONS: PIgAN, SIgAN, and MIgAN are caused by the deposition of abnormally glycosylated IgA1 whereas IgA-MGRS is not. The KM55/IgA quantified ratio is valuable in distinguishing PIgAN from SIgAN, as well as MIgAN from IgA-MGRS.

Celastrol attenuates renal injury in 5/6 nephrectomized rats via inhibiting epithelial-mesenchymal transition and transforming growth factor-ß1/Smad3 pathway.

Renal injury is an important factor in the development of chronic kidney diseases that pathologically manifested as renal fibrosis and podocyte damage. In the disease state, renal fibroblasts lead to high expression levels of α-smooth muscle actin (α-SMA), while podocytes undergo epithelial-mesenchymal transition, leading to proteinuria. Celastrol, a bioactive compound in the medicinal plant Tripterygium wilfordii, was found to delay the progression of early diabetic nephropathy and attenuate renal fibrosis in mice with unilateral ureteral obstruction. However, its effect on the renal system in 5/6 nephrectomized (Nx) rats remains unknown. The aim of this study was to explore the protective effects of celastrol and its underlying mechanisms in 5/6 Nx rats. We found that 24 h proteinuria and levels of blood urea nitrogen, serum creatinine, triglycerides, serum P, renal index and cholesterol significantly increased (P < 0.05), while that of serum albumin decreased significantly in 5/6 Nx rats. After intervention with celastrol, 24 h proteinuria and levels of blood urea nitrogen, serum creatinine, triglycerides, serum P, renal index, and cholesterol significantly decreased, while that of serum albumin significantly increased. Renal tissue pathological staining and transmission electron microscopy showed that celastrol ameliorated kidney injury and glomerular podocyte foot injury and induced significant anti-inflammatory effects. Quantitative polymerase chain reaction (PCR) and western blotting results revealed that nephrin and NEPH1 expression levels were upregulated, whereas α-SMA and Col4a1 expression levels were downregulated in the celastrol group. Celastrol inhibited the expression of transforming growth factor (TGF)-ß1/Smad3 signaling pathway-related molecules such as TGF-ß1 and P-Smad3. In summary, celastrol contributes to renal protection by inhibiting the epithelial-mesenchymal transdifferentiation and TGF-ß1/Smad3 pathways.

IgG subclass deposition in diabetic nephropathy.

PURPOSE: This study aimed to analyze the distribution of IgG subclass in diabetic nephropathy (DN) and its association with clinicopathological features. METHODS: This is a single-center retrospective study enrolling 108 patients with biopsy-proven DN. Immunofluorescence and immunohistochemistry staining were applied, and clinicopathological features and renal outcomes were compared between patients with different patterns or categories of IgG subclass deposition. RESULTS: Both IgG and its subclasses colocalized with collagen IV α5 on glomerular basement membrane (GBM) and some of tubular basement membrane (TBM). IgG1 and the Mixed type were two predominant types of deposition, no matter on GBM or TBM, and IgG1 showed a much higher deposition rate on GBM than that on TBM (P = 0.004). IgG subclass deposit on multi-location was more associated with a shorter duration of nephropathy and severer tubular interstitial injury (P < 0.05). The mixed type of IgG subclass deposit on GBM was merely associated with higher levels of proteinuria, whereas the deposition on TBM was more associated with higher levels of proteinuria, lower levels of albumin, more KIM-1 positive area, and thicker TBM (P < 0.05). Survival analysis revealed that none of the pattern or the category of IgG subclass deposit was a risk factor or a renal outcome indicator. CONCLUSIONS: IgG subclass was selectively deposited along GBM and/or TBM in DN, and the mixed type of IgG subclass deposition on TBM had more clinical significance than the isotype and that on GBM. IgG subclass deposition is merely a manifestation or a consequence rather than a cause in DN.

BMSC-derived exosomes protect against kidney injury through regulating klotho in 5/6 nephrectomy rats.

AIM: The aim of this study was to investigate the renoprotective effects of exosomes derived from rat bone marrow mesenchymal stem cells (rBMSCs) in a rat model of 5/6 nephrectomy (Nx)-induced chronic kidney disease (CKD). METHODS: A rat model of 5/6 Nx-induced CKD was established using conventional method. rBMSC-derived exosomes were isolated using ultracentrifugation and characterized. The exosomes were injected into 5/6 Nx rats through the caudal vein. After 12 weeks, 24 h proteinuria, serum creatinine (SCr), and blood urea nitrogen (BUN) levels were evaluated, and renal pathology was analyzed by H&E and Masson staining, and transmission electron microscopy. The expression of klotho was analyzed and the activity of the klotho promoter was evaluated using a luciferase reporter assay. RESULTS: The isolated exosomes showed typical morphological features. Exosomes transplantation reduced 24 h urinary protein excretion, and SCr and BUN levels in 5/6 Nx-induced CKD rats. Furthermore, renal pathology was improved in the exosome-treated 5/6 Nx rats. Mechanistically, the exosomes significantly upregulated the activity of klotho promoter and its expression. CONCLUSIONS: Transplantation of rBMSC-derived exosomes may protect against kidney injury, probably by regulating klotho activity and expression. Our results provide a theoretical basis for the application of rBMSC-derived exosomes in CKD therapy.

Tetrandrine alleviates podocyte injury via calcium-dependent calpain-1 signaling blockade.

BACKGROUND: Podocytes have become a crucial target for interventions in proteinuric kidney diseases. Many studies have reported that overexpression of transient receptor potential cation channel protein 6 (TRPC6) in podocyte injury upregulates intracellular Ca2+ influx and stimulates Ca2+-dependent protease calpain-1 signaling. The traditional Chinese drug, tetrandrine, a nonselective Ca2+ channel blocker, has long been used to treat chronic kidney disease. This research aimed to explore the possible mechanisms underlying the anti-proteinuric properties of tetrandrine. METHODS: We investigated the involvement of tetrandrine in Ca2+ dependent calpain-1 signaling in mouse podocytes and adriamycin-induced nephropathy rats. Cyclosporine A (CsA) and U73122 were used as positive controls. Cell viability, cytotoxicity, Ca2+ concentration, calpain activity, and mRNA and protein expression levels of calpain-1 signaling pathways were examined. The clinical and pathological changes were measured. RESULTS: Tetrandrine decreased intracellular Ca2+ influx in cultured TRPC6-overexpressing podocytes. In both in vitro and in vivo studies, the administration of tetrandrine downregulated calpain activity and the expression of calpain-1 and restored the expression of downstream Talin-1 and nephrin. Compared to CsA, tetrandrine treatment exhibited superior inhibitory effects on calpain activity and calpain-1 expression. CONCLUSIONS: Tetrandrine has therapeutic potential in podocyte damage by blocking Ca2+-dependent activation of the calpain-1 signaling pathway. Tetrandrine reduced proteinuria, improved renal function, and alleviate renal pathological damage.

Clinicopathological characteristics of patients with paraproteinemia and renal damage.

BACKGROUND: This study aimed to analyze the clinicopathological characteristics of patients with paraproteinemia and renal damage. METHODS: Ninety-six patients from 2014 to 2018 with paraproteinemia and renal damage were enrolled and the clinical data, renal pathology, treatment and prognosis data were collected. RESULTS: A total of 96 patients (54 male and 42 female), accounting for 2.7% of all renal biopsies, were enrolled in this study. Among them, 42 were monoclonal gammopathy of renal significance (MGRS), 21 were renal monotypic immunoglobulin alone (renal monoIg), and 19 were monoclonal gammopathy of undetermined significance (MGUS). Individuals with multiple myeloma (MM) accounted for the fewest number of patients (n = 14). In the MGRS group, the main diseases were amyloidosis (n = 25) and cryoglobulinemic glomerulonephritis (n = 7), while in the MM group, the main diseases were cast nephropathy (n = 9) and light chain deposit disease (n = 3). In the MGUS group, it was mainly IgA nephropathy (IgAN, n = 10) and idiopathic membranous nephropathy (n = 5); while in the renal monoIg group, most of the cases were IgAN (n = 19). Chemotherapy was mainly administered to patients in the MM group, while immunosuppression therapy was mostly administered to patients in the renal monoIg group. Most patients with renal monoIg exhibited a major response, followed by the patients with MGUS and MGRS, while most of the patients with MM had a partial response but none had a major response. Approximately more than half (57.1%) of the patients with MM progressed to end-stage renal disease (ESRD), followed by MGRS (33.3%); however, the mortality rate was low in both the MGRS and MM groups. The survival analysis reviewed that serum creatinine, hemoglobin levels, and the serum κ/λ ratio were independent risk factors for ESRD in patients with MGRS. CONCLUSIONS: The clinicopathological changes in patients with MGRS were between those in patients with MM and MGUS. The treatment for MGRS and MM was more intensive, and the overall mortality rate was low. Both MGUS and renal monoIg alone exhibited slighter clinicopathological features than MGRS and MM, and the treatment was focused mostly on primary renal diseases.