Machine learning in predicting T-score in the Oxford classification system of IgA nephropathy.

Background: Immunoglobulin A nephropathy (IgAN) is one of the leading causes of end-stage kidney disease (ESKD). Many studies have shown the significance of pathological manifestations in predicting the outcome of patients with IgAN, especially T-score of Oxford classification. Evaluating prognosis may be hampered in patients without renal biopsy. Methods: A baseline dataset of 690 patients with IgAN and an independent follow-up dataset of 1,168 patients were used as training and testing sets to develop the pathology T-score prediction (T pre) model based on the stacking algorithm, respectively. The 5-year ESKD prediction models using clinical variables (base model), clinical variables and real pathological T-score (base model plus T bio), and clinical variables and T pre (base model plus T pre) were developed separately in 1,168 patients with regular follow-up to evaluate whether T pre could assist in predicting ESKD. In addition, an external validation set consisting of 355 patients was used to evaluate the performance of the 5-year ESKD prediction model using T pre. Results: The features selected by AUCRF for the T pre model included age, systolic arterial pressure, diastolic arterial pressure, proteinuria, eGFR, serum IgA, and uric acid. The AUC of the T pre was 0.82 (95% CI: 0.80-0.85) in an independent testing set. For the 5-year ESKD prediction model, the AUC of the base model was 0.86 (95% CI: 0.75-0.97). When the T bio was added to the base model, there was an increase in AUC [from 0.86 (95% CI: 0.75-0.97) to 0.92 (95% CI: 0.85-0.98); P = 0.03]. There was no difference in AUC between the base model plus T pre and the base model plus T bio [0.90 (95% CI: 0.82-0.99) vs. 0.92 (95% CI: 0.85-0.98), P = 0.52]. The AUC of the 5-year ESKD prediction model using T pre was 0.93 (95% CI: 0.87-0.99) in the external validation set. Conclusion: A pathology T-score prediction (T pre) model using routine clinical characteristics was constructed, which could predict the pathological severity and assist clinicians to predict the prognosis of IgAN patients lacking kidney pathology scores.

Intensive blood pressure control and the progression of IgA nephropathy: a cohort study using marginal structural models.

BACKGROUND: In chronic kidney disease, current guidelines recommend systolic blood pressure (SBP) below 120 mmHg. However, the renoprotective effect of intensive blood-pressure (BP) lowering on immunoglobulin A nephropathy (IgAN) remains undetermined. We aimed to determine the effect of intensive BP control on the progression of IgAN. METHODS: At Peking University First Hospital, 1530 patients with IgAN were enrolled. An examination of the relationship between baseline and time-updated BP and composite kidney outcomes, defined as development of end-stage kidney disease (ESKD) or a 30% decline in estimated glomerular filtration rate (eGFR), was conducted. Baseline and time-updated BPs were modeled using multivariate causal hazards models and marginal structural models (MSMs). RESULTS: In a median follow-up of 43.5 (interquartile range 27.2, 72.7) months, 367 (24.0%) patients experienced the composite kidney outcomes. No significant associations were found between baseline BP and the composite outcomes. Using MSMs with time-updated SBP for analysis, a U-shaped association was found. In reference to SBP 110-119 mmHg, hazard ratios (95% confidence intervals) for the SBP categories <110, 120-129, 130-139 and ≥140 mmHg were 1.48 (1.02-2.17), 1.13 (0.80-1.60), 2.21 (1.54-3.16) and 2.91 (1.94-4.35), respectively. The trend was more prominent in patients with proteinuria ≥1 g/day and eGFR ≥60 mL/min/1.73 m2. After analyzing time-updated diastolic BP, no similar trend was observed. CONCLUSIONS: In patients with IgAN, intensive BP control during the treatment period may retard the kidney disease progression, but the potential risk of hypotension still needs to be considered.

Clinicopathological and immunological features of new onset kidney disease: a rare event after SARS-CoV-2 vaccination.

The onset of various kidney diseases has been reported after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. However, detailed clinical and pathological features are lacking. We screened and analyzed patients with newly diagnosed kidney diseases after inactivated SARS-CoV-2 vaccination in Peking University First Hospital from January 2021 to August 2021, and compared them with the reported cases in the literature. We obtained samples of blood, urine and renal biopsy tissues. Clinical and laboratory information, as well as light microscopy, immunostaining and ultrastructural observations, were described. The SARS-CoV-2 spike protein and nucleoprotein were stained using the immunofluorescence technique in the kidney biopsy samples. SARS-CoV-2 specific antibodies were tested using magnetic particle chemiluminescence immunoassay. The study group included 17 patients with a range of conditions including immune-complex-mediated kidney diseases (IgA nephropathy, membranous nephropathy and lupus nephritis), podocytopathy (minimal change disease and focal segmental glomerulosclerosis) and others (antineutrophil-cytoplasmic-antibody-associated vasculitis, anti-glomerular basement membrane nephritis, acute tubulointerstitial nephritis and thrombotic microangiopathy). Seven patients (41.18%) developed renal disease after the first dose and ten (58.82%) after the second dose. The kidney disease spectrum as well as clinicopathological features are similar across different types of SARS-CoV-2 vaccines. We found no definitive evidence of SARS-CoV-2 spike protein or nucleoprotein deposition in the kidney biopsy samples. Seropositive markers implicated abnormal immune responses in predisposed individuals. Treatment and follow-up (median = 86 days) showed that biopsy diagnosis informed treatment and prognosis in all patients. In conclusion, we observed various kidney diseases following SARS-CoV-2 vaccine administration, which show a high consistency across different types of SARS-CoV-2 vaccines. Our findings provide evidence against direct vaccine protein deposition as the major pathomechanism, but implicate abnormal immune responses in predisposed individuals. These findings expand our understanding of SARS-CoV-2 vaccine renal safety.

Long-term safety and efficacy of hydroxychloroquine in patients with IgA nephropathy: a single-center experience.

BACKGROUND: Hydroxychloroquine (HCQ) has been used as a supportive therapy for IgA nephropathy (IgAN). We aimed to determine the long-term efficacy and safety of HCQ therapy in patients with IgAN. METHODS: A total of 180 patients with IgAN who had received HCQ therapy for at least 1 year were enrolled in this study. The changes in proteinuria and the estimated glomerular filtration rate (eGFR) were analyzed during the follow-up period. RESULTS: The level of proteinuria decreased from 1.69 [1.24, 2.30] to 1.01 [0.59, 1.74] g/day (- 37.58 [- 57.52, 8.24] %, P < 0.001) at 12 months and to 1.00 [0.59, 1.60] g/day (- 55.30 [- 71.09, - 3.44] %, P < 0.001) at 24 months. There was no significant change in the eGFR of these patients at 12 months (65.82 ± 25.22 vs. 63.93 ± 25.96 ml/min/1.73 m2, P = 0.411); however, the eGFR decreased from 65.82 ± 25.22 to 62.15 ± 25.81 ml/min/1.73 m2 at 24 months (P = 0.003). The cumulative frequency of all patients with a 50% decrease in proteinuria was 72.78% at 12 months. Sixty (33.3%) patients changed to corticosteroid therapy during the follow-up period. No serious adverse effects were documented during HCQ treatment. CONCLUSIONS: HCQ effectively and safely reduces proteinuria in IgAN patients with different levels of eGFR, supporting the maintenance of stable kidney function in the long term.

The efficacy and safety of hydroxychloroquine in pregnant patients with IgA nephropathy: A retrospective cohort study.

AIM: Hydroxychloroquine (HCQ) is used to control proteinuria in IgA Nephropathy (IgAN) However, its efficacy and safety in pregnant IgAN patients remains unknown. This study aimed to verify the safety of HCQ in pregnant IgAN patients and compare renal function and pregnancy outcomes with those of patients not treated with HCQ. METHODS: We retrospectively reviewed medical records of all pregnant IgAN patients and singleton gestations at Peking University First Hospital from 2003-2021. Patients who did and did not receive HCQ treatment during pregnancy were compared. RESULTS: We found no significant pre- or post-pregnancy differences in proteinuria or renal function between the two groups. However, the HCQ (+) group had higher proteinuria at the time of kidney biopsy (2.04 [1.26, 2.56] g/d vs. 0.80 [0.44, 1.11] g/d, P < .001); the proteinuria level at HCQ therapy initiation was also higher than that at the beginning of pregnancy (1.87 [1.30, 2.59] g/d vs. 1.08 [0.75, 1.50] g/d, P = .001). Despite no difference in preterm birth, birth weight, preeclampsia or postpartum haemorrhage, the proportion of patients with a previous history of spontaneous abortion was higher in the HCQ (+) group than in the HCQ (-) group (48.0% vs. 20.6%, P = .010). The eGFR (regression coefficient, 0.981; 95%CI 0.964-0.998) was a predictive factor for obstetrical complications. CONCLUSION: HCQ is safe for IgAN treatment during pregnancy with effective reduction of proteinuria. HCQ might also be helpful in patients with a history of spontaneous abortion.

Interaction between GALNT12 and C1GALT1 Associates with Galactose-Deficient IgA1 and IgA Nephropathy.

BACKGROUND: Galactose-deficient IgA1 plays a key role in the pathogenesis of IgA nephropathy, the most common primary GN worldwide. Although serum levels of galactose-deficient IgA1 have a strong genetic component, the genetic link between this molecule and IgA nephropathy has not yet been clearly established. METHODS: To identify novel loci associated with galactose-deficient IgA1, we performed a quantitative genome-wide association study for serum galactose-deficient IgA1 levels, on the basis of two different genome-wide association study panels conducted in 1127 patients with IgA nephropathy. To test genetic associations with susceptibility to IgA nephropathy, we also enrolled 2352 patients with biopsy-diagnosed IgA nephropathy and 2632 healthy controls. Peripheral blood samples from 59 patients and 27 healthy controls were also collected for gene expression analysis. RESULTS: We discovered two loci, in C1GALT1 and GALNT12, that achieved genome-wide significance, explaining about 3.7% and 3.4% of variance in serum galactose-deficient IgA1 levels, respectively. We confirmed the previously reported association of C1GALT1 with serum galactose-deficient IgA1 levels, but with a different lead single-nucleotide polymorphism (rs10238682; ß=0.26, P=1.20×10-9); the locus we identified at GALNT12 (rs7856182; ß=0.73, P=2.38×10-9) was novel. Of more interest, we found that GALNT12 exhibits genetic interactions with C1GALT1 in both galactose-deficient IgA1 levels (P=1.40×10-2) and disease risk (P=6.55×10-3). GALNT12 mRNA expression in patients with IgA nephropathy was significantly lower compared with healthy controls. CONCLUSIONS: Our data identify GALNT12 as a novel gene associated with galactose-deficient IgA1 and suggest novel genetic interactions. These findings support a key role of genetically conferred dysregulation of galactose-deficient IgA1 in the development of IgA nephropathy.

Interstitial eosinophilic infiltration in diabetic nephropathy is indicative of poor prognosis, with no therapy benefit from steroid.

BACKGROUND: Studies suggested that eosinophils in diabetes might be associated with severity of diabetic nephropathy (DN). In a retrospective study of 102 Chinese patients with biopsy-proven DN, we aimed to evaluate relationships of both blood and renal eosinophils (Eos) to the severity of DN and check whether Eos can serve as an indicator of prognosis as well as the therapeutic effect of steroids. METHODS: One hundred and two patients diagnosed with DN were enrolled. Demographical and clinical data and histopathological scores were associated. Interstitial eosinophilic aggregates (IEA) were defined as the presence of ≥10 Eos in at least one high-power field. End-stage renal disease was defined as the end point. RESULTS: We observed that log2 (blood eosinophil counts) correlated with neutrophil counts, proteinuria, and tubulointerstitial inflammatory cell infiltration. IEA was observed in 33.3% of the DN patients and was associated with decreased estimated glomerular filtration rate, higher proteinuria, hematuria, higher HbA1c, increased blood eosinophil counts, tubular injury, tubulointerstitial chronicity, and interstitial inflammation. IEA was associated with worse renal prognosis (hazard ratio [HR] 2.424, P = 0.008). Consistently, urine eosinophil cationic protein (ECP) (ng/mgCr) was associated with renal injury and poor renal prognosis (HR 1.173, P = 0.020). Patients with IEA were more likely to be treated with steroid/immunosuppressants (47.1% vs 14.7%, P = 0.001) but did not show renal benefit. CONCLUSIONS: It suggested that both blood and renal infiltrated eosinophils were prevalent in DN and associated with severity of DN. IEA in renal pathology showed better fit in correlation with renal prognosis. Treatment with steroid/immunosuppressants showed no significant improvement regarding renal prognosis.

Delayed diagnosis of acromegaly in a patient with focal segmental Glomerulosclerosis: a rare case report and literature review.

BACKGROUND: Experimental studies have demonstrated that hypersecretion of growth hormone (GH) is associated with development of glomerular sclerosis. However, clinical case of such condition is very rare. Here we presented a case of focal segmental glomerulosclerosis (FSGS) associated with acromegaly. CASE PRESENTATION: A 63-year-old man was diagnosed as nephrotic syndrome with minimal change disease for 2 years. Prednisone 1 mg/kg/day for 9 months led to no response. After admission, the second kidney biopsy indicated FSGS (NOS variant). On admission, his acromegalic features were noticed and he complained with a 20-year history of soft tissue swelling of hands and feet. Serum GH and insulin-like growth factor 1 (IGF-1) concentrations were both elevated significantly. An oral glucose tolerance test showed inadequate suppression of serum GH. The presence of a pituitary macroadenoma with a diameter of 1.4 cm by MRI confirmed the diagnosis of acromegaly. Then, the tumor was subtotally removed by trans-sphenoidal surgery. Partial remission of proteinuria was achieved 3 months after surgery and maintained during follow-up, with gradual reduce of corticosteroid. CONCLUSIONS: This rare case suggested that the hypersecretion of GH may participate, at least in part, in FSGS development and progression. Early diagnosis and treatment of acromegaly is beneficial.

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.

Characteristics of patients with coexisting IgA nephropathy and membranous nephropathy.

BACKGROUND: Coexistence of IgA nephropathy (IgAN) and membranous nephropathy (MN) in the same patient is rare. Few studies have reported the clinical and pathological features of patients with combined IgAN and MN (IgAN-MN). METHODS: The clinico-pathological features, levels of galactose-deficient IgA1 (Gd-IgA1) and autoantibodies against M-type transmembrane phospholipase A2 receptor (anti-PLA2R) in sera were compared among IgAN-MN, IgAN, and MN patients. RESULTS: Twenty-six patients with biopsy-proven IgAN-MN were enrolled. The mean age at biopsy was 43.6 ± 15.9 years, and 65.4% were male. Proteinuria and estimated glomerular filtration rate (eGFR) levels in patients with IgAN-MN were similar to that of MN patients. Compared with the IgAN patients, IgAN-MN patients showed a higher median proteinuria level (4.3 vs. 1.2 g/day, p < .001), and a higher mean eGFR level (101.8 ± 25.4 vs. 78.6 ± 26.9 mL/min/1.73 m2, p < .001). IgAN-MN patients presented with milder pathological lesions than IgAN patients according to the Oxford Classification. IgAN-MN patients had comparable serum levels of Gd-IgA1 with those of IgAN patients (353.4 ± 95.5 vs. 347.0 ± 109.6 U/mL, p = .801). Percentage of IgAN-MN patients with detectable serum levels of anti-PLA2R was lower than that of MN patients (38.5% vs. 68.6%, p = .011). CONCLUSIONS: IgAN-MN patients display similar clinical features to MN patients and milder pathological lesions than IgAN patients. IgAN-MN patients have similar levels of Gd-IgA1 to those of IgAN patients, and a lower proportion of anti-PLA2R than MN patients.

Measures of Urinary Protein and Albumin in the Prediction of Progression of IgA Nephropathy.

BACKGROUND AND OBJECTIVES: Proteinuria is an independent predictor for IgA nephropathy (IgAN) progression. Urine albumin-to-creatinine ratio (ACR), protein-to-creatinine ratio, and 24-hour urine protein excretion (UPE) are widely used for proteinuria evaluation in clinical practice. Here, we evaluated the association of these measurements with clinical and histologic findings of IgAN and explored which was the best predictor of IgAN prognosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Patients with IgAN were followed up for ≥12 months, were diagnosed between 2003 and 2012, and had urine samples available (438 patients). Spot urine ACR, protein-to-creatinine ratio, and 24-hour UPE at the time of renal biopsy were measured on a Hitachi Automatic Biochemical Analyzer 7180 (Hitachi, Yokohama, Japan). RESULTS: In our patients, ACR, protein-to-creatinine ratio, and 24-hour UPE were highly correlated (correlation coefficients: 0.71-0.87). They showed good relationships with acknowledged markers reflecting IgAN severity, including eGFR, hypertension, and the biopsy parameter (Oxford severity of tubular atrophy/interstitial fibrosis parameter). However, only ACR presented with positive association with the Oxford segmental glomerulosclerosis/adhesion parameter and extracapillary proliferation lesions. The follow-up time was 37.0 (22.0-58.0) months, with the last follow-up on April 18, 2014. In total, 124 patients reached the composite end point (30% eGFR decline, ESRD, or death). In univariate survival analysis, ACR consistently had better performance than protein-to-creatinine ratio and 24-hour UPE as represented by higher area under the curve using time-dependent survival analysis. When adjusted for well known risk factors for IgAN progression, ACR was most significantly associated with the composite end point (hazard ratio, 1.56 per 1-SD change of standard normalized square root-transformed ACR; 95% confidence interval, 1.29 to 1.89; P<0.001). Compared with protein-to-creatinine ratio and 24-hour UPE, addition of ACR to traditional risk factors resulted in more improvement in the predictive ability of IgAN progression (c statistic: ACR=0.70; protein-to-creatinine ratio =0.68; 24-hour UPE =0.69; Akaike information criterion: ACR=1217.85; protein-to-creatinine ratio =1229.28; 24-hour UPE =1234.96; P<0.001). CONCLUSIONS: In IgAN, ACR, protein-to-creatinine ratio, and 24-hour UPE had comparable association with severe clinical and histologic findings. Compared with protein-to-creatinine ratio and 24-hour UPE, ACR showed slightly better performance in predicting IgAN progression.

Increased APRIL Expression Induces IgA1 Aberrant Glycosylation in IgA Nephropathy.

Aberrant glycosylated IgA1 molecules, mainly galactose-deficient IgA1 (Gd-IgA1), are important causal factors in IgA nephropathy; however, the underlying mechanism for the production of aberrantly glycosylated IgA1 is unknown. A recent genome-wide association study identified a novel IgAN susceptibility gene, TNFSF13, which encoded a proliferation-inducing ligand (APRIL) that promotes lymphocyte proliferation and IgA class switching. We aimed to explore the mechanism of APRIL's involvement in IgAN. We enrolled 166 patients with IgAN and 77 healthy controls and detected the plasma APRIL levels by the ELISA method, identified the mRNA expression of APRIL and its receptors by relative quantitative PCR, and confirmed by in vitro experiment. We identified increased plasma APRIL levels in IgAN, which was further proved by upregulated mRNA expression in B-lymphocytes from 27 IgAN patients. Analysis of the clinical characteristics of patients with IgAN showed that higher plasma APRIL level was associated with more severe clinical presentations (high proteinuria and low eGFR). The plasma APRIL level was positively correlated with Gd-IgA1 levels. Furthermore, exogenous APRIL could induce more production of Gd-IgA1 in cultured lymphocytes from patients with IgAN, compared with that from healthy controls. And, the relative higher expression of receptors of APRIL, that is, BCMA and TACI, in B-lymphocytes from IgAN patients were observed. Our findings implied that in patients with IgAN, increased APRIL is accompanied elevated expression of its receptors in B-lymphocytes, which induces overproduction of Gd-IgA1, ultimately contributing to the pathogenesis of IgAN.

Elevated soluble VEGF receptor sFlt-1 correlates with endothelial injury in IgA nephropathy.

BACKGROUND: Endothelial injury, which may present clinically as hypertension, proteinuria and increased von Willebrand Factor (vWF) level, is a common manifestation in IgA nephropathy (IgAN). However, causal factors for endothelial injury in IgAN are not completely understood. An imbalance of vascular endothelial growth factor/Soluble fms-like tyrosine kinase-1 (VEGF/sFlt-1) has been observed in many diseases with endothelial dysfunction, including pre-eclampsia and diabetic retinopathy, but whether it contributes to endothelial injury in IgAN requires further exploration. METHODS: Initially, 96 IgAN patients and 22 healthy volunteers were enrolled as a discovery cohort. VEGF/sFlt-1, sFlt-1 and VEGF levels were compared between patients with IgAN and healthy volunteers to explore the underlying factors that contribute to endothelial injury in IgAN. The identified contributor (sFlt-1) was further confirmed in a replication cohort, which included 109 IgAN patients and 30 healthy volunteers. Correlations of sFlt-1 with hypertension, proteinuria, Oxford-E score and plasma vWF were further evaluated in the combined 205 patients with IgAN. RESULTS: VEGF/sFlt-1 levels were significantly lower in IgAN patients than healthy volunteers (0.33±0.27 vs. 0.43±0.22, p = 0.02) in the discovery cohort. Within the ratio, plasma sFlt-1 levels were significantly elevated (101.18±25.19 vs. 79.73±18.85 pg/ml, p<0.001), but plasma VEGF levels showed no significant differences. Elevated sFlt-1 levels in the replication cohort were confirmed in IgAN patients (93.40±39.78 vs. 71.92±15.78 pg/ml, p<0.001). Plasma sFlt-1 levels in IgAN patients correlated with proteinuria (severe (>3.5 g/d) vs. moderate (1-3.5 g/d) vs. mild (<1 g/d) proteinuria: 115.95±39.09 vs. 99.89±28.55 vs. 83.24±33.92 pg/ml; severe vs. mild: p<0.001, moderate vs. mild p = 0.001, severe vs. moderate: p = 0.014), hypertension (with vs. without hypertension: 107.87±31.94 vs. 87.32±32.76 pg/ml, p = 0.015) and vWF levels (r = 0.161, p = 0.021). CONCLUSIONS: The present study found elevated sFlt-1 in IgAN patients and further identified its correlation with proteinuria, hypertension and vWF levels. These results suggested that elevated sFlt-1 contributes to endothelial injury in IgAN.

FCGR2B and FCRLB gene polymorphisms associated with IgA nephropathy.

BACKGROUND: IgA nephropathy (IgAN) is a complex syndrome characterized by deposition of IgA and IgA containing immune complexes (ICs) composed of IgG and complement C3 proteins in the mesangial area of glomeruli. The low-affinity receptors for the Fc region of IgG (FcγRs) are involved in autoantibody/immune complex-induced organ injury as well as ICs clearance. The aim of the study was to associate multiple polymorphisms within FCGR gene locus with IgAN in a large Chinese cohort. PATIENTS AND METHODS: 60 single nucleotide polymorphisms (SNPs) spanning a 400 kb range within FCGR gene locus were analyzed in 2100 DNA samples from patients with biopsy proven IgAN and healthy age- and sex-matched controls from the same population in Chinese. RESULTS: Among the 60 SNPs investigated, 15 gene polymorphisms within FCGR gene locus (25%) were associated with susceptibility to IgAN. The most significantly associated SNPs within individual genes were FCGR2B rs12118043 (p = 8.74*10(-3), OR 0.76, 95% CI 0.62-0.93), and FCRLB rs4657093 (p = 2.28*10(-3), OR 0.77, 95% CI 0.65-0.91). Both conditional analysis and linkage disequilibrium analysis suggested they were independent signals associated with IgAN. Associations between FCGR2B rs12118043 and proteinuria (p = 3.65×10(-2)) as well as gross hematuria (p = 4.53×10(-2)), between FCRLB rs4657093 and levels of serum creatinine (p = 2.67×10(-2)) as well as eGFR (p = 5.41*10(-3)) were also observed. Electronic cis-expression quantative trait loci analysis supported their possible functional significance, with protective genotypes correlating lower gene expressions. CONCLUSION: Our data from genetic associations and expression associations revealed potentially pathogenic roles of Fc receptor gene polymorphisms in IgAN.

Tacrolimus improves the proteinuria remission in patients with refractory IgA nephropathy.

BACKGROUND: Tacrolimus has been reported to be effective in refractory nephrotic syndrome, such as focal segmental glomerulosclerosis and membranous nephropathy. Some IgA nephropathy (IgAN) patients with massive proteinuria showed resistance to steroids and/or cytotoxic immunosuppressants based on the supportive therapy with renin- angiotensin system blockade. The efficacy and safety of tacrolimus in such refractory IgAN patients are extremely ambiguous, and the mechanism of tacrolimus improving proteinuria remission needs to be investigated. METHODS: 14 refractory IgAN patients were enrolled. The patients received tacrolimus (0.05-0.1 mg/kg/day) and prednisone (0.5 mg/kg/day) for at least 6 months. Synaptopodin and calcineurin expression were detected in renal tissues of patients who received re-biopsy. A puromycin aminonucleoside (PAN)-induced human podocyte injury model was applied to investigate the possible role of tacrolimus in proteinuria remission. RESULTS: Of the 14 patients enrolled, 3 were withdrawn because serum creatinine increased over 30% baseline. In 11 patients treated with tacrolimus over 6 months, 9 showed complete or partial remission and 7 achieved remission within 1 month. In renal tissues, the expression of calcineurin increased while synaptopodin decreased and recovered partially after tacrolimus therapy. In an in vitro study, F-actin disrupted in human podocytes after stimulation of PAN, while calcineurin increased and synaptopodin decreased. After co-treatment with tacrolimus the reorganization of F-actin and the expression of calcineurin and synaptopodin recovered. CONCLUSIONS: Tacrolimus showed a rapid proteinuria remission in refractory IgAN patients. The possible mechanism of tacrolimus to proteinuria remission might be podocyte cytoskeleton stabilization through inhibition of calcineurin expression.

Gene-gene interaction of BLK, TNFSF4, TRAF1, TNFAIP3, and REL in systemic lupus erythematosus.

OBJECTIVE: Although the number of convincingly established genetic associations with systemic lupus erythematosus (SLE) has increased sharply over the last few years, refinement of these associations is required, and their potential roles in gene-gene interactions need to be further investigated. Recent genome-wide association studies (GWAS) in SLE have produced renewed interest in B cell/T cell responses and the NF-κB signaling pathway. The aim of this study was to search for possible gene-gene interactions based on identified single-nucleotide polymorphisms (SNPs), in using an approach based on the role of signaling pathways. METHODS: The SNPs in BLK, TNFSF4, TRAF1, TNFAIP3, and REL were replicated in order to evaluate genetic associations with SLE. TaqMan genotyping was conducted in 804 Chinese patients with SLE and 722 matched control subjects. A multiple logistic regression model was used to estimate the multiplicative interaction effect of the SNPs, and additive interactions were analyzed by 2×2 factorial designs. Data from a previously published GWAS conducted by the International Consortium on the Genetics of Systemic Lupus Erythematosus were derived for comparison and validation. RESULTS: Single-marker analysis validated the association of BLK rs2736340 (P=4.25×10(-6)) as well as TNFSF4 rs2205960 (P=2.82×10(-5)) and TNFAIP3 rs5029939 (P=1.92×10(-3)) with SLE susceptibility in Chinese. Multiplicative interaction analysis indicated that BLK had an interactive effect with TNFSF4 in Chinese patients with SLE (P=6.57×10(-4)). Additive interaction analysis revealed interactions between TRAF1 and TNFAIP3 in both Chinese (P=2.18×10(-3)) and Caucasians (P=2.86×10(-4)). In addition, multiple tendencies toward interactions were observed, and an additive effect was observed as the number of risk genotypes increased. CONCLUSION: The results of this study provide evidence of the possible gene-gene interactions of BLK, TNFSF4, TRAF1, TNFAIP3, and REL in SLE, which may represent a synergic effect of T cells and B cells through the NF-κB pathway in determining immunologic aberration.

Abnormal expression and dysfunction of novel SGLT2 mutations identified in familial renal glucosuria patients.

Familial renal glucosuria (FRG) is characterized by persistent glucosuria despite normal serum glucose and in the absence of overt tubular dysfunction. Mutation of sodium/glucose co-transporter 2 (SGLT2) has been identified and was recently reported to be involved in FRG. However, the functional and pathological consequences of such mutations remain unknown. In the current study, we collected four families with FRG. Sequencing of the SGLT2 coding region, intronic segments and cDNA revealed three missense mutations (294C>A: F98L; 1388T>G: L463R; 1435C>G: R479G) and two splice mutations (IVS 1-16 C>A: Del exon3; IVS 11+1 G>C: Del exon11). The probands were either heterozygous or compound heterozygous for SGLT2 mutations, and had glucosuria quantified at 6-27 g/day. Human 293 cells were transfected with the plasmid constructs to study the expression and function of SGLT2 mutants in vitro. Confocal microscopy using green fluorescent protein (GFP) revealed that the mutation results in a loss of punctate membrane pattern typical of the wild-type SGLT2 except in the 294C>A mutant. All mutants had significantly lower transport capacity in comparison to the wild-type control (26.49-71.48%). Renal biopsy in one consenting proband revealed significantly lower SGLT2 expression in the apical side of the proximal convoluted tubule in comparison to both healthy and disease controls (minimal change disease and diabetic nephropathy). The current study provides functional clues regarding the SGLT2 molecule from genotype to phenotype in FRG families.

Association of TLR9 gene polymorphisms with lupus nephritis in a Chinese Han population.

OBJECTIVES: Although increasing data have supported the possible role of TLR-9 in the pathogenesis of lupus nephritis (LN), the effect of TLR-9 on the lupus phenotype remains controversial. The aim of this study was to associate common variants in the TLR9 gene with susceptibility to lupus nephritis in the Chinese population to further ascertain whether it is a susceptible locus for SLE, especially its likely role in LN from a comparatively large population. METHODS: Two previously reported SLE associated single nucleotide polymorphism (rs352139, rs352140) were investigated in a case-control study comprised of 315 patients with biopsy proven lupus nephritis and 338 matched healthy controls. Single nucleotide polymorphisms (SNPs) were typed by TaqMan allele discrimination assays. RESULTS: Both rs352139 (p=0.040, OR: 0.713, 95%CI: 0.516-0.985) and rs352140 (p=0.048, OR: 0.723, 95%CI: 0.525-0.997) were associated with LN in dominant model. A trend for an association between genotypes and the disease activity indexes was observed. However, no significance was achieved. CONCLUSIONS: The present study suggested that TLR9 gene have a role in establishing an autoimmune background and pathogenesis in human LN.

[Clinicopathologic characteristics and outcomes of IgA nephropathy in elder patients].

OBJECTIVE: To investigate the clinical, pathological characteristics and outcomes of IgA nephropathy in the elderly. METHODS: Seventy patients over age 60 with IgA nephropathy were studied and compared with 82 patients under 60 years in the clinical and pathological features as well as the outcomes. RESULTS: Compared with non-elderly group, elder group patients had higher blood pressure [systolic pressure (142.0+/-20.4) mmHg vs (124.2+/-16.9) mmHg (1mmHg=0.133 kPa), diastolic pressure (83.1+/-11.8) mmHg vs (78.9+/-12.3) mmHg], serum creatinine [(172.7+/-125.8) micromol/L vs (94.4+/-42.5) micromol/L], serum cholesterol[(5.7+/-1.6) mmol/L vs (5.1+/-1.6) mmol/L], 24 hj urinary protein excretion rate [(3.4+/-2.9) g/d vs (1.8+/-2.0) g/d], and the incidence of CKD stages 3-5(64.0% vs 14.6%)(P<0.05). No significant differences were seen in the disease courses, rate of gross hematuria, serum triglyceride and serum IgA level between two groups(P>0.05).Renal pathological investigation showed the chronic lesions were dominated in elder group. There was significant difference in portion of glomerular sclerosis [(19.7+/-20.1)% vs (13.4+/-17.8)%], renal tubule atrophy (>1 score,34.2% vs 25.6%), interstitial fibrosis (>1,score 34.2% vs 18.2%), and arteriolosclerosis (>2 score,20.0% vs 8.5%) between two groups (P<0.05). However, there were no significant difference in proportion of mesangial proliferation, crescent and interstitial inflammatory cell infiltration (P>0.05). After a mean post-biopsy follow-up of (34.6+/-33.3) months, the 3-year and the 5-year renal survival rates for elder group were 74.6% and 62.2%, respectively, which were lower than those of non-elder group (100% and 92.9%, P=0.002). CONCLUSION: Elder patients with IgA nephropathy were more likely to suffer from hypertension, hyperlipidemia, renal insufficiency and chronic pathologic lesions, which might be the risk factors for the patient's unfavorable prognosis.