Decreased IgA binding levels were accompanied by increased IgG sialylation in IgA nephropathy.

INTRODUCTION: IgA nephropathy (IgAN) is a kidney disorder characterized by the deposition of circulating immune complexes of IgG bound to galactose-deficient IgA1 (Gd-IgA1) in the mesangial glomeruli. However, limited research has been conducted on the levels of IgA binding in relation to the various sialylation profiles of IgG in IgAN. MATERIALS AND METHODS: Sialylated IgG (SA-IgG) and desialylated IgG (DSA-IgG) were isolated from IgAN patients. The IgG-IgA immune complex (IgG-IgA-IC) was detected using two customized commercial ELISA kits. Additionally, IgG was enzymatically digested with neuraminidase to produce DSA-IgG. Subsequently, the binding capacities of both intact IgG and the neuraminidase-digested DSA-IgG with Gd-IgA1 were determined using ELISA kits. RESULTS: Our research revealed that SA-IgG levels were negatively correlated with Gd-IgA1 (R = -0.16, p = 0.03) in IgAN patients. The optical density (OD) levels of IgG-IgA complexes in SA-IgG samples were significantly lower (0.58 ± 0.09) compared to those in DSA-IgG samples (0.78 ± 0.12) when using the Gd-IgA1 assay kit. These results were confirmed using an IgG assay kit, which showed that the SA-IgG groups had significantly lower IgA indices (0.31 ± 0.12) compared to the DSA-IgG groups (0.57 ± 0.19). Furthermore, we investigated the binding capacity of IgG with different sialic acid levels to Gd-IgA1. The results revealed that neuraminidase digestion of IgG increased its propensity to bind to Gd-IgA1. Additionally, we examined the binding capacity of both intact IgG and DSA-IgG to Gd-IgA1 at different mix ratios (IgG 1.5 µg and Gd-IgA1 1.5 µg, IgG 1.5 µg and Gd-IgA1 3 µg, IgG 3 µg and Gd-IgA1 1.5 µg). Interestingly, DSA-IgG demonstrated significantly higher binding capacity to Gd-IgA1 compared to intact IgG at all mix ratios tested. CONCLUSION: The preliminary findings from our present study indicate that the binding level of IgA in purified sialylated IgG is lower than that in desialylated IgG.

Prognosis of IgA Nephropathy with Stage 3b-5 CKD.

Objective To investigate whether immunosuppressive therapy is beneficial in IgA nephropathy (IgAN) patients with eGFR < 45ml/min/1.73m2. Methods This retrospective study involved 110 IgAN patients for whom clinical data was available; of these, 90 had complete follow-up data. Patients were grouped based on whether they received immunotherapy during follow-up, their renal function, proteinuria levels, and the percentage of crescentic glomeruli observed at the time of renal biopsy. Results The mean eGFR for the participants was 32.0 ± 10.2 ml/min/1.73 m². The average follow-up duration was 46.1 ± 37.9 months. The mean rate of decline in eGFR was 3.6 ml/min/1.73 m² per year. There were 43 (47.8%) composite kidney endpoint occurred in these patients. In the group that received immunotherapy, the incidence of kidney endpoint events was lower than in the untreated group (45.1% vs. 57.9%), but the difference was not statistically significant (P = 0.320). Among patients with stage CKD 3b, the incidence of endpoint events was lower than in those with stages CKD 4 and 5 (36.8% vs. 66.7%, P = 0.006). Conversely, the high proteinuria group saw a higher incidence of endpoint events compared to the low proteinuria group (51.9% vs. 23.1%), although this difference was not statistically significant (P = 0.054). Meanwhile, there was no significant difference in the incidence of endpoint events between the two crescent glomerular ratio groups (48.7% vs. 41.7%, P = 0.649). Kaplan-Meier survival analysis indicated that renal function level (P＜0.001) and proteinuria (P = 0.023) were associated with renal survival in IgAN patients. In contrast, the administration of immunosuppressive therapy (P = 0.288) and the prevalence of C lesions (P = 0.982) did not show a significant association with renal survival. Further, Cox regression analysis identified systolic blood pressure, fibrinogen, and CKD stage as risk factors for eGFR decline in IgAN patients (all P < 0.05). Conclusions IgAN patients with stage 3b-5 CKD exhibited a poor prognosis. It appears that in this specific cohort of IgAN patients, immunosuppressive therapy may not provide significant advantages over supportive care therapeutic regimens in terms of disease management.

Glomerular IgG deposition predicts kidney disease progression in IgA nephropathy.

Objective: We aimed to explore the relationship between the presence and intensity of glomerular IgG deposition and the occurrence of kidney progression events in IgA nephropathy (IgAN). Methods: This retrospective study encompassed a total of 1207 patients with IgAN spanning the period from 2010 to 2022, and complete follow-up data were accessible for 736 patients. The IgG intensity was categorized as follows: low-level, defined as IgG (±) and IgG (+), and high-level, defined as IgG (++) and IgG (+++). Results: We found that the IgG-positive deposited group (N = 113, 9.36%) had significantly higher levels of ESR, TC, LDL, uric acid, proteinuria, and blood glucose, and lower serum albumin level compared to the IgG-negative deposited group (N = 1094, 90.64%). In terms of pathology, the IgG-positive deposited group had a significantly higher percentage of T2 score compared to the IgG-negative deposited group (p = 0.002). At the end of the follow-up period, the IgG-positive deposited group had a higher eGFR decline (-5.7 ± 4.37 ml/year) compared to the IgG-negative deposited group (-4 ± 2.52 ml/year), however, there was not a statistically significant difference between the two groups (p = 0.096). We observed that the high-IgG group had significantly higher level of TG compared to the low-IgG group (p = 0.042). Further analysis revealed that the group of patients with high level of IgG deposition in the kidney experienced a higher incidence of composite kidney outcomes compared to the group with low level of IgG deposition (p = 0.009). Logistic regression analyses showed that high level IgG deposition was an independent risk factor for kidney progression of IgAN (HR 13.419; 95% CI 2.690-66.943, P = 0.029). Further analyses for a solid conclusion using Cox regression that we found high level IgG deposition (HR 115.277; 95% CI 2.299-5.779E3, P = 0.017), eGFR (HR 0.932; 95% CI 0.870-0.999, P = 0.047), and urine protein excretion (HR 1.001; 95% CI 1.000-1.002, P = 0.015) were independent risk factor for kidney progression of IgAN. Conclusions: The intensity of IgG deposition has been found to be associated with the progression of IgAN. Future prospective studies should provide more robust evidence on the impact of IgG deposition on kidney outcomes in patients with IgAN.

Clinical and pathological findings of IgA nephropathy following SARS-CoV-2 infection.

The features of IgA nephropathy (IgAN) after SARS-CoV-2 infection have not been well characterized. In this study, we compared the clinical and pathological characteristics of patients with IgAN who had experienced SARS-CoV-2 infection to those who had not. We conducted a retrospective study that enrolled 38 patients with biopsy-proven IgAN following SARS-CoV-2 infection with 4 months (post-SARS-CoV-2 infection group) and 1154 patients with IgAN prior to the pandemic (pre-SARS-CoV-2 infection group). Among the SARS-CoV-2 group cases, 61% were females. The average duration from SARS-CoV-2 infection to renal biopsy was 78.6 days. Prior to SARS-CoV-2 infection, the patients had different presentations of nephropathy. One patient had isolated hematuria, two had isolated proteinuria, twenty presented with both hematuria and proteinuria, and one patient had elevated serum creatinine. Additionally, there were eight cases with uncertain nephropathy history, and six cases did not have a history of nephropathy. Following SARS-CoV-2 infection, five patients experienced gross hematuria, one case exhibited creatinine elevation, and five cases showed an increase in proteinuria. The group of patients infected with SARS-CoV-2 after the COVID-19 pandemic exhibited older age, higher hypertension ratio and lower eGFR values compared to the pre-SARS-CoV-2 infection group. As for pathological parameters, a higher proportion of patients in the post-SARS-CoV-2 infection group exhibited a higher percentage of sclerotic glomeruli and glomerular ischemic sclerosis. There were no significant differences observed between the two groups in terms of therapy involving steroids, immunosuppressants, or RAS inhibitors. IgA nephropathy patients who were infected with SARS-CoV-2 were generally older and experienced more severe kidney damage compared to those without SARS-CoV-2 infection.

The effect of fibrinoid necrosis on the clinical features and outcomes of primary IgA nephropathy.

BACKGROUND: To explore the clinicopathologic features and outcomes of IgAN patients who presented with fibrinoid necrosis (FN) lesions or not and the effect of immunosuppressive (IS) treatment in IgAN patients with FN lesions as well. METHODS: This was a retrospective cohort study with 665 patients diagnosed with primary IgAN from January 2010 to December 2020 in Tianjin Medical University General Hospital and having detailed baseline and follow-up characteristics. Patients were divided into two groups depending on the appearance of FN lesions. Patients with FN lesions were recruited into Group FN1, while patients who were not found FN lesions in their renal biopsy specimens were recruited into Group FN0. Compare the differences between Group FN0 and Group FN1 in baseline clinicopathologic features, treatment solutions and follow-up data as well. To evaluate the impact of different fractions of FN lesions on baseline characteristics and prognosis of IgAN, we subdivided patients in Group FN1 into 3 groups depending on the FN lesions distribution, Mild Group: 0 < FN% < 1/16; Moderate Group: 1/16 < FN% < 1/10; Severe Group: FN% > 1/10. Furthermore, we compared the differences in baseline clinicopathologic features, treatment solutions and follow-up data among these three groups. Kidney endpoint event was defined as patients went into end-stage kidney disease (ESKD), which estimated glomerular filtration rate (eGFR) < 15 ml/min/1.73 m^2, regularly chronic dialysis over 6 months or received renal transplantation surgery. The kidney composite endpoint was defined by a ≥ 30% reduction in eGFR, double Scr increase than on-set, ESKD, chronic dialysis over 6 months or renal transplantation. Compare the survival from a composite endpoint rate in different groups by Kaplan-Meier survival curve. The univariate and multivariate Cox models were used to establish the basic model for renal outcomes in patients with FN lesions. RESULTS: (1) A total of 230 patients (34.59%) were found FN lesions in all participants. Patients with FN lesions suffered more severe hematuria than those without. On the hand of pathological characteristic, patients with FN lesions showed higher proportions of M1, E1, C1/C2 and T1/T2 lesions compared with those without FN lesions. (2) The 1-year, 3-year, and 5-year survival of the composite endpoint were lower in the FN1 group than FN0 group. (3) After adjusting for clinicopathological variables, the presence of FN lesions was a significantly independent risk factor for composite endpoint. By using multivariate Cox regression analyses, we also found when the fraction of FN lesions exceeded 10%, the risk of progression into composite endpoint increased 3.927 times. CONCLUSION: Fibrinoid necrosis of capillary loops is an independent risk factor of poor renal outcomes. More effective treatment should be considered for those who had FN lesions.

Efficacy and safety of belimumab therapy for patients with lupus nephritis: A meta-analysis and a propensity score-matched case-control study.

OBJECTIVE: In this study, we performed a meta-analysis and a propensity score-matched case-control study to evaluate the efficacy and safety of belimumab in patients with lupus nephritis (LN). METHODS: We analyzed the data from three randomized controlled trials (RCTs) to assess the effects of belimumab treatment on renal improvement and adverse effects. Our study included a total of six LN patients who received belimumab treatment and an additional six LN patients who received standard therapy. All participants were followed up for a duration exceeding 96 weeks to evaluate the outcomes of the treatments. RESULTS: Our meta-analysis incorporated data from three articles involving a total of 666 patients. The results of the analysis revealed that a higher proportion of patients who received belimumab treatment experienced renal improvement compared to those in the control group. The patients in belimumab group had a higher renal complete response rate and proteinuria improvement rate compared to the control group. However, belimumab treatment did not increase the renal partial response rate compared to the control group. The belimumab group also exhibited a higher proportion of patients who achieved normalization of antidouble-stranded DNA, as well as normalization of low C3 and C4 levels. In our case-control study, significant improvement in proteinuria was demonstrated with belimumab at Week 48 (p = 0.037) and at all subsequent time points (all p < 0.05). Over the course of 96 weeks, belimumab treatment was associated with renal function stabilization and an increase in C3 and C4 levels. Moreover, the use of belimumab resulted in a reduction in glucocorticoid dosage at Week 24 (p = 0.02). Additionally, patients receiving belimumab treatment had a lower risk of severe treatment-emergent adverse events, and no other significant adverse effects were observed between the two groups. CONCLUSIONS: In patients with LN, the utilization of belimumab therapy has demonstrated notable improvements in renal response rates. Additionally, it has shown a decreased likelihood of serious treatment-related adverse events and a diminished need for glucocorticoid dosage when compared to the active control group.

Effect of hematuria on the kidney disease progression in IgA nephropathy patients with mild proteinuria and well-preserved renal function.

OBJECTIVE: To investigate whether hematuria is a risk factor in IgA nephropathy (IgAN) patients with mild proteinuria and well-preserved renal function. METHODS: This retrospective study included a total of 63 IgAN patients, with complete clinical data available for 50 patients. Hematuria assessment was conducted using two methods: 1) an automated method using a urine particle analyzer, and 2) a manual method performed by a skilled examiner to examine microscopic urine sediment. RESULTS: The results of hematuria measurement using both automated and manual methods showed a strong linear correlation (r = 0.78, P < 0.001). In IgAN patients, those with high urinary red blood cell count (U-RBCs) exhibited higher serum IgA levels compared to patients with low U-RBCs. Additionally, patients with crescent formation had higher levels of proteinuria compared to those without crescents. Patients who received immunosuppressive treatment displayed higher levels of systolic blood pressure (SBP) and mean arterial pressure (MAP), as well as lower levels of serum hemoglobin and albumin. They also had a higher prevalence of T1 lesions compared to patients who did not undergo immunosuppression. Furthermore, among patients with crescent formation, those who received immunosuppressive agents exhibited higher levels of SBP, diastolic blood pressure (DBP), MAP, and U-RBCs, as well as lower levels of albumin and proteinuria at the time of renal biopsy. No composite kidney endpoint events were observed in these groups of patients. The U-RBCs level was not identified as a risk factor influencing the decline of estimated glomerular filtration rate (eGFR) in IgAN. CONCLUSIONS: The presence of hematuria at the time of biopsy was not found to be associated with kidney disease progression in IgAN patients who had mild proteinuria and well-preserved renal function. This suggests that it is possible that these patients may not derive significant benefits from immunosuppressive therapy.

Deciphering prognostic value of CD22 and its contribution to suppression of proinflammatory cytokines production in patients with IgA nephropathy.

BACKGROUND: CD22, mainly expressed in mature B cells, could negatively regulate the function of B cells by binding to sialic acid-positive IgG (SA-IgG). Soluble CD22 (sCD22) is generated by the cleavage of the extracellular domain of CD22 on the membrane surface. However, the role of CD22 in IgA nephropathy (IgAN) remains unknown. METHODS: A total of 170 IgAN patients with a mean follow-up of 18 months were included in this study. The sCD22, TGF-ß, IL-6 and TNF-α were detected using commercial ELISA kits. SA-IgG were purified to stimulate peripheral blood mononuclear cells (PBMCs) from IgAN patients. RESULTS: The plasma levels of sCD22 were lower in IgAN patients in comparison with healthy control. Furthermore, CD22 mRNA levels in PBMCs from patients with IgAN were significantly lower than those of healthy controls. The plasma levels of sCD22 were positively correlated to the mRNA levels of CD22. We found that patients with higher sCD22 levels had a lower level of serum creatinine and a higher level of eGFR on the time of renal biopsy and a higher remission rate of proteinuria and a lower risk of kidney events at the end of follow-up. The logistic regression analysis showed sCD22 was associated with an increased odd of proteinuria remission after being adjusted for eGFR, proteinuria, and SBP. After adjusting for confounding variables, sCD22 was a borderline significant predictor of less kidney composite endpoint. In addition, the sCD22 levels were positively associated with SA-IgG in plasma. The experimental results in vitro showed that addition of SA-IgG enhanced the release of sCD22 in cell supernatant and the phosphorylation of CD22 in PBMCs, further inhibiting the production of IL-6, TNF-α, and TGF-ß in cell supernatant in a dose-dependent manner. Pretreatment with CD22-antibody significantly increased the expression of cytokines in PBMCs. CONCLUSIONS: This is the first study to demonstrate that lower plasma soluble CD22 in IgAN patients and high soluble CD22 levels are associated with an increased odd of proteinuria remission and a decreased odd of kidney endpoint. The interaction between CD22 and SA-IgG can inhibit proliferation and inflammation release in PBMCs from IgAN patients.

Circulating platelets supply ST6Gal-1 in patients with IgA nephropathy.

BACKGROUND: Our previous study showed ST6 ß-galactoside α2,6-sialyltransferase 1 (ST6Gal-1) levels in plasma were associated with a slower progression of IgA nephropathy (IgAN). Platelets are the crucial regulator of cell surface glycosylation events in circulation by supplying glycosyltransferases. METHODS: A total of 180 patients with IgAN were included in this study. ST6Gal-1 levels were analyzed before and after activation of platelets by flow cytometry. RESULTS: We found that IgAN patients in the higher platelet counts group exhibited higher levels of ST6Gal-1 compared with the lower platelet counts group. There was a positive correlation between platelet counts and ST6Gal-1 levels in plasma. Patients with higher platelet counts had higher levels of IgA, serum C3, serum C4 and proteinuria, higher percentages of platelet crits, S1 and T1/2, lower levels of platelet distribution width and the mean platelet volume, as well as a lower percentage of platelet large cell ratio compared with those patients with lower platelet counts. No differences were found in terms of the eGFR decline and composite kidney endpoints between two groups. Furthermore, we investigated whether platelets were activated and released ST6Gal-1 in patients with IgAN. The expression of CD62P in platelets in patients with IgAN was higher than those of healthy controls. There were no obvious changes in ST6Gal-1 levels between the rest and the activated platelets within 1 to 2-hour, however, the difference in ST6Gal-1 levels became more pronounced after 4-hour of incubation. CONCLUSIONS: In conclusion, human circulating platelets contain ST6Gal-1, which may be released by the activation of platelets in IgAN.

What is the context? Our previous study showed ST6 ß-galactoside α2,6-sialyltransferase 1 (ST6Gal-1) levels in plasma were associated with a slower progression of IgA nephropathy (IgAN).Platelets are the crucial regulator of cell surface glycosylation events in circulation by supplying glycosyltransferases.Whether elevated ST6Gal-1 in plasma is partly from platelets in IgAN has not been fully elucidated.What is new? A total of 180 patients with IgAN were included in this study.We found that IgAN patients in the higher platelet counts group exhibited higher levels of ST6Gal-1 compared with the lower platelet counts group.Patients with higher platelet counts had higher levels of IgA, serum C3, serum C4 and proteinuria, higher percentages of platelet crits, S1 and T1/2, lower levels of platelet distribution width and the mean platelet volume, as well as a lower percentage of platelet large cell ratio.There were no differences in terms of the eGFR decline and composite kidney endpoints between two groups.Furthermore, we explored whether platelets were activated and released ST6Gal-1 in patients with IgAN. The expression of CD62P in platelets in patients with IgAN was higher than that of healthy controls.There were no obvious changes in ST6Gal-1 levels between the rest and the activated platelets within 1 to 2-hour, however, the difference in ST6Gal-1 levels became more pronounced after 4-hour of incubation.What is the impact?Human circulating platelets contain ST6Gal-1, which can be released upon platelets activation. These findings suggest ST6Gal-1 is dynamically controlled by platelet activation to remodel cell surface glycans and alter cell behavior.

Elevated activating Fc gamma receptors levels correlated with susceptibility and severity of IgA nephropathy.

Background: It is still uncertain if a dysregulated expression of activating Fc gamma receptors (FcγRs) is associated with the development of immunoglobulin A nephropathy (IgAN). Methods: RNA sequencing was used to determine the mRNA levels of type I FcγRs, which were then verified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Commercial ELISA kits were used to detect plasma soluble FcγRIIIb (sFcγRIIIb). Results: We first examined the expression of FcγRs genes in 17 patients with IgAN and six healthy controls. The expression of FcγRIa, FcγRIb, FcγRIIa, FcγRIIc, FcγRIIIa, and FcγRIIIb was shown to be higher in IgAN patients. Even without statistical significance, there was a downward trend in FcγRIIb mRNA levels in IgAN. We observed that the expression levels of activating FcγR mRNAs were consistently higher in an independent set of 20 IgAN patients and 20 healthy controls, confirming the RNA-seq results. FcγRIIIb was the IgG receptor with the greatest difference in expression between the two groups (log2 fold-change = 1.82). We observed a much higher percent of FcγRIIIb positive cells in IgAN by flow cytometry. Next, we measured plasma sFcRIIIb levels in 50 patients with IgAN and 50 healthy controls. The findings revealed that the mean sFcγRIIIb level in plasma in participants with IgAN was much higher than that of healthy controls. Increased sFcγRIIIb levels were associated with a substantial increase in body mass index (BMI), lipid levels, serum creatinine level, and a larger percentage of sclerosis compared with lower sFcRIIIb levels. Patients in the group with higher sFcγRIIIb levels were more likely to get glucocorticoid treatment. Conclusion: The results demonstrated that the mRNA levels of the activating Fc receptor of IgG were significantly increased in IgAN. Patients with higher plasma sFcγRIIIb levels may have had more severe illness than those with lower levels.

The difference between patients with nephrotic syndrome and nephrotic-range proteinuria in IgA nephropathy: a propensity score matched cohort study.

OBJECTIVE: To date, nephrotic syndrome (NS) has not been well characterized in patients with IgA nephropathy (IgAN). Whether decline in serum albumin is an ominous sign in IgAN patients with massive proteinuria remains unknown. In this study, we evaluated clinical and pathological features of IgAN with NS and compared the differences for these features and long-term outcomes between patients with nephrotic syndrome and nephrotic-range proteinuria. METHODS: A retrospective study was conducted, enrolling 1013 patients with biopsy-proven IgAN. The primary endpoint was the composite of a doubling of the base-line serum creatinine, 50% reduction in eGFR, ESKD (eGFR < 15 ml/min per 1.73 m2) or death. RESULTS: A total of 59 patients were presented with NS (5.8%). The patients with NS showed lower levels of hemoglobin, albumin and higher levels of serum creatinine, serum uric acid and urinary protein than patients without NS. As for pathological parameters, more patients with NS showed a higher prevalence of E1 lesions, T1/2 and C1/2 lesions. Furthermore, we used the propensity score matching method to select 57 patients with nephrotic-range proteinuria and normal serum albumin (NR group) who were comparable to 59 patients with NS. Patients with NS had lower levels of hemoglobin, albumin and IgG and higher levels of TC, LDL, FIB and D-dimer as well as more severe E1 and C1/2 lesions than those in NR group. The S1 lesion was more severe in the NR group than that in the NS group. There was no significant difference in long-term outcome between the two groups. In addition, we found that serum albumin level or the presence of hypoalbuminemia was not a risk factor affecting long-term outcome in patients with massive proteinuria. CONCLUSIONS: A prevalence of 5.8% of NS was presented in IgAN adult patients in our study. IgAN with NS patients had low levels of hemoglobin, albumin, high levels of serum creatinine, serum uric acid, urinary protein and more acute lesions. The prognosis of NS in patients with IgAN was not inferior to that of patients with nephrotic range proteinuria and normal serum albumin.

Sialylation of IgG inhibits the formation of galactose-deficient IgA1-containing immune complexes and protects mesangial cells from injury in IgA nephropathy.

BACKGROUND: The addition of sialic acid alters IgG from a pro-inflammatory state to an anti-inflammatory state. However, there is a lack of research on the changes of IgG sialylation in IgA nephropathy (IgAN). METHODS: This study included a total of 184 IgAN patients. The sialylated IgG (SA-IgG), IgG-galactose-deficient IgA1 complex (IgG-Gd-IgA1-IC), IL-6, TNF-α, and TGF-ß were detected using commercial ELISA kits. SA-IgG, non-sialylated IgG (NSA-IgG), sialylated IgG-IgA1 complex (SA-IgG-IgA1), and non-sialylated IgG-IgA1 complex (NSA-IgG-IgA1) were purified from IgAN patients and healthy controls (HCs). RESULTS: The mean SA-IgG levels in plasma and B lymphocytes in IgAN patients were significantly higher than those of healthy controls. A positive correlation was found between SA-IgG levels in plasma and B lymphocytes. In vitro, the results showed that the release of IgG-Gd-IgA1-IC was significantly decreased in peripheral blood mononuclear cells (PBMCs) cultured with SA-IgG from both IgAN patients and healthy controls. The proliferation ability and the release of IL-6, TNF-α, and TGF-ß in human mesangial cells (HMCs) were measured after stimulating with SA-IgG-IgA1-IC and NSA-IgG-IgA1-IC. The mesangial cell proliferation levels induced by NSA-IgG-IgA1-IC derived from IgAN patients were significantly higher than those caused by SA-IgG-IgA1-IC derived from IgAN patients and healthy controls. Compared with NSA-IgG-IgA1 from healthy controls, IgAN-NSA-IgG-IgA1 could significantly upregulate the expression of IL-6 and TNF-α in mesangial cells. The data showed that there weren't any significant differences in the levels of IL-6, TNF-α, and TGF-ß when treated with IgAN-SA-IgG-IgA1 and HC-NSA-IgG-IgA1. CONCLUSIONS: The present study demonstrated that the sialylation of IgG increased in patients with IgA nephropathy. It exerted an inhibitory effect on the formation of Gd-IgA1-containing immune complexes in PBMCs and the proliferation and inflammation activation in mesangial cells.

Plasma ST6GAL1 regulates IgG sialylation to control IgA nephropathy progression.

BACKGROUND: Our previous study revealed that plasma levels of a-2,6-sialyltransferase 1 (ST6GAL1) were increased in patients with IgA nephropathy (IgAN). ST6GAL1 catalyzes terminal sialylation of IgG to shift the antibody effector function to the anti-inflammatory pattern. However, the role of plasma ST6GAL1 in the progression of IgAN and underlying mechanisms are still unknown. METHODS: A total of 180 IgAN patients were included. The kidney outcomes were defined as the eGFR decline or proteinuria remission. Peripheral blood mononuclear cells (PBMCs) were either stimulated with purified sialylated IgG (SA-IgG) or with non-sialylated IgG (NSA-IgG) from IgAN patients to detect the levels of interleukin (IL)-6 and tumor necrosis factor-α (TNF-α) in supernatant. RESULTS: Compared with the lower ST6GAL1 (reference), the risk of eGFR decline decreased for the higher ST6GAL1 group after adjustment for baseline eGFR, systolic blood pressure (SBP), and proteinuria. The results showed that patients with higher ST6GAL1 levels had a higher rate of proteinuria remission. ST6GAL1, expressed as a continuous variable, was a protective factor for eGFR decline and proteinuria remission. An in vitro study showed that the administration of recombinant ST6GAL1 (rST6GAL1) decreased the levels of IL-6 and TNF-α in PBMCs. Furthermore, the administration of rST6GAL1 resulted in the enrichment of SA-IgG in a concentration-dependent manner. In addition, as compared to control, purified SA-IgG-treated PBMCs showed a significant decrease in the expression of IL-6 and TNF-α. CONCLUSION: Our study indicated that elevated ST6GAL1 was associated with a slower progression of IgAN, which may play a protective effect by increasing IgG sialylation to inhibit the production of proinflammatory cytokines in PBMCs.

Sodium-glucose cotransporter 2 inhibitors benefit to kidney and cardiovascular outcomes for patients with type 2 diabetes mellitus and chronic kidney disease 3b-4: A systematic review and meta-analysis of randomized clinical trials.

BACKGROUND: A systematic review and meta-analysis was performed to assess the kidney and cardiovascular (CV) outcomes of sodium-glucose cotransporter 2 (SGLT2) inhibitors in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) stage 3b-4. METHOD: We conducted a systematic review and meta-analysis of randomized, placebo-controlled trials (RCTs). Medline, Embase, and the Cochrane Central were searched for available trials up to Jan 18, 2021. RESULTS: From identifying 1892 citations, we included nine studies into quantitative analyses with a total of 6521 participants. In the patients with T2DM and CKD stage 3b-4, SGLT2 inhibitors significantly decreased the risk of the primary kidney outcome (HR 0.65, 95% CI 0.55-0.76) and slowed the decline in eGFR slope with a difference between treatment and control of 0.46 ml/min/1.73 m2 per year (95% CI 0.37-0.55). SGLT2 inhibitors also reduced the risk of the major adverse cardiovascular events (MACE) (HR 0.75, 95% CI 0.60-0.93). CONCLUSIONS: SGLT2 inhibitors can reduce the risk of kidney disease and MACE outcomes for patients with T2DM and CKD stage 3b-4, which may be the most beneficial effects observed in the included trials.

Effects and Safety of a Novel Oral Potassium-Lowering Drug-Sodium Zirconium Cyclosilicate for the Treatment of Hyperkalemia: a Systematic Review and Meta-Analysis.

BACKGROUND: Oral sodium zirconium cyclosilicate (SZC) is a novel potassium binder capable of achieving a rapid reduction of serum potassium (sK+) and maintaining a long-term normokalemia. We undertook a meta-analysis to summarize and evaluate the effects surrounding SZC in patients with hyperkalemia. METHOD: We searched data sources from MEDLINE (from 1950 to Sep 2020), EMBASE (from 1970 to Sep 2020), and the Cochrane Library database (from 1950 to Sep 2020) for eligible studies. All randomized controlled trials (RCTs) regarding comparison of therapeutic effects of SZC in hyperkalemia participants were included. RESULTS: Seven studies, including 1697 patients with hyperkalemia, were analyzed. SZC significantly reduced mean sK+ (-0.42 mmol/L; 95% CI: -0.63 to -0.20 mmol/L, p = 0.0001) compared with placebo, with a significantly greater proportion of patients with normokalemia (RR 3.48, 95% CI 1.49 to 8.11, p = 0.004). Subgroup analyses showed that the longer durations of SZC treatment, the greater magnitudes of potassium reduction when compared with those of placebo (p between subgroups = 0.01) at correction phase. Besides, it also demonstrated sK+ tended to decrease more in patients who got longer treatment or larger dosage of SZC at maintenance phase; however, the difference did not reach statistical significance. Additionally, the drug was equally effective in studies with larger than 50% of patients with chronic kidney disease (CKD) or diabetes or patients using renin-angiotensin aldosterone system inhibitor (RAAS) inhibitors (all p < 0.05). The risk of edema (4.30, 1.17 to 15.84; p = 0.03) in SZC group was higher than those of placebo group. No statistically significant differences in the risks of other adverse events were observed between the two groups. CONCLUSIONS: SZC effectively decreased the sK+ level in patients with hyperkalemia within 48 h and had benefits in the long-term control of serum potassium in patients who continued to receive SZC with a favorable safety profile from available data.

The soluble VEGF receptor sFlt-1 contributes to endothelial dysfunction in IgA nephropathy.

Endothelial injury is a common manifestation in IgA nephropathy (IgAN). After the previous identification of the upregulated soluble fms-like tyrosine kinase-1 (sFlt-1) correlated with endothelial injury in IgAN, in the present study, we further explored the role of sFlt-1 in endothelial injury in IgAN. We enrolled 72 patients with IgAN and detected the sFlt-1 levels. The polymeric IgA1 (pIgA1) complexes were isolated from the pooled plasma samples of another 10 patients with IgAN. Apoptosis proteins were detected in cultured human umbilical vein endothelial cells (HUVECs) with the stimulation of recombinant sFlt-1 or the caspase-9 inhibitor Z-LEHD-FMK. We identified there were positive correlations between sFlt-1 and IgA-IgG complex as well as vWF levels in patients with IgAN. The sFlt-1 levels in HUVECs were significantly upregulated by pIgA1 complex derived from IgAN patients in a concentration-dependent manner. The proliferation ability of HUVECs was damaged when stimulated with sFlt-1 protein in a time- and dose- dependent manner. And the apoptosis rate was up-regulated significantly as the stimulation concentrations of sFlt-1 increased. We found sFlt-1 challenge could significantly increase the expression of vWF. In addition, sFlt-1 increased the levels of caspase-9, caspase-3, Bax and mitochondrial membrane potential; facilitated the release of cytochrome C from mitochondria to cytoplasma. In contrast, Z-LEHD-FMK attenuated high sFlt-1-induced HUVECs apoptosis. In conclusion, our study demonstrated that sFlt-1 expression was up-regulated by the challenge of pIgA1 complex derived from patients with IgAN. Furthermore, increased sFlt-1 facilitated human umbilical vein endothelial cells apoptosis via the mitochondrial-dependent pathway.

ST6Gal1 is up-regulated and associated with aberrant IgA1 glycosylation in IgA nephropathy: An integrated analysis of the transcriptome.

Galactose-deficient IgA1 (Gd-IgA1) plays a crucial role in the development of Immunoglobulin A nephropathy (IgAN), however, the underlying pathogenic mechanisms driving Gd-IgA1 production in B cells are not well understood. In this study, RNA-seq analysis identified 337 down-regulated and 405 up-regulated genes in B cells from 17 patients with IgAN and 6 healthy controls. Among them, ST6Gal1, which was associated with IgAN in a previous genome-wide association study (GWAS), was up-regulated in IgAN and significantly positive correlated with elevated Gd-IgA1. In addition, we identified increased plasma ST6Gal1 levels in 100 patients with IgAN, which were associated with higher levels of proteinuria, plasma IgA, Gd-IgA1 levels, greater degrees of systemic complement activation including C3a, Bb, C4d, MAC and a lower proportion classified as C2 grade (crescent proportion ≥25%). Interesting, in vitro, recombinant ST6Gal1 (rST6Gal1) exposure reduced the production of Gd-IgA1 in cultured peripheral blood mononuclear cells from IgAN patients. rST6Gal1 stimuli also increased expression of C1GALT1, which were well-known proportional to the decrease in galactose deficiency of IgA1. In conclusions, we identified increased plasma ST6Gal1 levels and the association of ST6Gal1 with disease severity of IgAN. Additionally, rST6Gal1 administration in vitro increased expression of C1GALT1 and reduced the production of Gd-IgA1.

ACE Inhibitor Benefit to Kidney and Cardiovascular Outcomes for Patients with Non-Dialysis Chronic Kidney Disease Stages 3-5: A Network Meta-Analysis of Randomised Clinical Trials.

BACKGROUND: The advantages of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) in reducing risk of cardiovascular events (CVEs) and delaying end-stage kidney disease (ESKD) in patients with chronic kidney disease (CKD) is well-known. However, the efficacy and safety of these agents in non-dialysis CKD stages 3-5 patients are still a controversial issue. METHODS: Two investigators (Yaru Zhang and Dandan He) independently searched and identified relevant studies from MEDLINE (from 1950 to October 2018), EMBASE (from 1970 to October 2018), and the Cochrane Library database. Randomised clinical trials in non-dialysis CKD3-5 patients treated with renin-angiotensin system (RAS) inhibitors were included. We used standard criteria (Cochrane risk of bias tool) to assess the inherent risk of bias of trials. We calculated the odds ratio (OR) and 95% confidence interval (CI) for each outcome by random-effects model. A 2-sided p value < 0.05 was considered statistically significant, and all statistical analyses were performed using STATA, version 15.0. This network meta-analysis was undertaken by the frequency model. RESULTS: Forty-four randomised clinical trials with 42,319 patients were included in our network meta-analysis. ACEIs monotherapy significantly decreased the odds of kidney events (OR 0.54, 95% CI 0.41-0.73), cardiovascular events (OR 0.73, 95% CI 0.64-0.84), cardiovascular death (OR 0.73, 95% CI 0.63-0.86) and all-cause death (OR 0.77, 95% CI 0.66-0.91) when compared to placebo. According to the cumulative ranking area (SUCRA), ACEI monotherapy had the highest probabilities of their protective effects on outcomes of kidney events (SUCRA 93.3%), cardiovascular events (SUCRA 77.2%), cardiovascular death (SUCRA 86%), and all-cause death (SUCRA 94.1%), even if there were no significant differences between ACEIs and other antihypertensive drugs, including calcium channel blockers (CCBs), ß-blockers and diuretics on above outcomes except for kidney events. ARB monotherapy and combination therapy of an ACEI plus an ARB showed no more advantage than CCBs, ß-blockers and diuretics in all primary outcomes. In the subgroup of non-dialysis diabetic kidney disease patients, no drugs, including ACEIs or ARBs, significantly lowered the odds of cardiovascular events and all-cause death. However, ACEIs were still better than other antihypertensive drugs including ARBs in all-cause death but not ARBs in cardiovascular events according to the SUCRA. Only ARBs had significant differences in preventing the occurrence of kidney events compared with placebo (OR 0.82, 95% CI 0.72-0.95). Both ACEI/ARB monotherapy and combination therapy had higher odds of hyperkalaemia. ACEIs had 3.81 times higher odds than CCBs (95% CI 1.58-9.20), ARBs had 2.08-5.10 times higher odds than placebo and CCBs and combination therapy of an ACEI and an ARB had 4.80-24.5 times higher odds than all other treatments. Compared with placebo, CCBs and ß blockers, ACEI therapy significantly increased the odds of cough (OR 2.90, 95% CI 1.76-4.77; OR 8.21, 95% CI 3.13-21.54 and OR 1.80, 95% CI 1.08-3.00). There were no statistical differences in hypotension among all comparisons except ACEIs versus placebo. CONCLUSIONS: Although ACEIs increased the odds of hyperkalaemia, cough and hypotension, they were still superior to ARBs and other antihypertensive drugs and had the highest benefits for the prevention of kidney events, cardiovascular outcomes, cardiovascular death and all-cause mortality in non-dialysis CKD3-5 patients. In patients with advanced diabetic kidney disease, ACEIs were superior to ARBs in lowering risk of all-cause death but not in kidney events and cardiovascular events.

Effects of ACE Inhibitors and Angiotensin Receptor Blockers in Normotensive Patients with Diabetic Kidney Disease.

The role of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) in reducing the progression of albuminuria and risk of cardiovascular events in hypertensive patients with diabetic kidney disease (DKD) is well-documented. However, the efficacy and safety of these agents in normotensive patients with DKD are still controversial. MEDLINE, Embase, and Cochrane Library were searched for relevant random controlled trials. The odd risk (OR) reductions were calculated with a random-effects model. Decrease in albuminuria, changes in eGFR, major cardiovascular events, and drug-related adverse events were analyzed. Thirteen RCTs including 1282 patients were retrieved. Compared with placebo or other active agent groups, ACEIs or ARBs significantly decreased albuminuria (MD -80.28 mg/d, 95% CI -104.79 mg/d to -55.77 mg/d), and the efficacy is independent of changes in blood pressure and systolic blood pressure at baseline. The result of subanalysis showed the declining of albuminuria was more significantly in normotensive DKD patients with 2DM (p=0.005). No significant differences were found with regard to the declining of evaluated glomerular filtration rate (eGFR) (MD -0.29 ml/min/1.73 m2, 95% CI -2.99 to 2.41 ml/min/1.73 m2). There were no significant differences in the side effect of the drugs such as hypotension and hyperkalemia. This meta-analysis demonstrated that ACEIs or ARBs can decrease albuminuria to varying degree in normotensive patients with DKD, and better response occurred in patients with 2DM.

C1GALT1 expression is associated with galactosylation of IgA1 in peripheral B lymphocyte in immunoglobulin a nephropathy.

BACKGROUND: More and more studies demonstrated that genetic variation at C1GALT1 influences Gd-IgA1 level in IgAN. However, whether the expression of ß1, 3-galactosyltransferase (ß1, 3Gal-T) was influenced may provide insights into how Gd-IgA1 levels are controlled in IgAN. METHODS: Thirty IgAN patients diagnosed in Tianjin Medical University General Hospital from April to September 2018 and 30 healthy volunteers whose age and gender matched with patients were enrolled in this study. Total Gd-IgA1 levels in plasma were determined by ELISA and C1GALT1 levels were determined by RT-PCR. Four databases (PubMed, EMBASE, CNKI, WanFang Medical Network) were searched to identify eligible studies that evaluated a difference in the expression of C1GALT1 in IgAN patients compared with total controls (non-IgAN and health controls). The C1GALT1C1 expression levels, which was indispensable to ß1, 3Gal-T of IgA1, was also been compared. RESULTS: Gd-IgA1 levels were remarkable higher in IgAN patients compared with healthy control. The expression levels of C1GALT1 gene were remarkably down-regulated in IgAN patients compared with healthy control. And the mRNA level of C1GALT1 was inversely correlated to Gd-IgA1 levels. In meta-analysis, six articles including 316 participants that analyzed the expression of ß1, 3Gal-T were met inclusion criteria. There was no significant difference in the expression of C1GALT1 between IgAN patients compared with controls. And we found patients with IgAN had lower levels of C1GALT1 gene expression in the B cells compared to controls. The C1GALT1C1 levels in the IgAN patients were not different from the levels in the control group, which were unchanged no matter according to different ethnic population, different control group and different cell source. Two studies including 46 persons compared enzymatic activity of ß1, 3Gal-T in B cells, and the result showed the ß1, 3Gal-T activity was decreased in B cells. CONCLUSIONS: We found expression levels of C1GALT1 were remarkably downregulated in IgAN patients and negatively correlated with higher levels of Gd-IgA1. Subsequent meta-analysis validated the low expression and activity of ß1, 3Gal-T in B cells in patients with IgAN. However, there was no apparent disparity in the aspect of C1GALT1C1 expression between IgAN and control groups.