Time-Varying Proteinuria and Progression of IgA Nephropathy: A Cohort Study.

RATIONALE & OBJECTIVE: Proteinuria is a surrogate end point for predicting long-term kidney outcomes in IgA nephropathy (IgAN) with levels<1g/day identified as a therapeutic target. However, this threshold has not been sufficiently studied. We quantified the associations of progression of IgAN with various levels of proteinuria. STUDY DESIGN: Observational cohort study. SETTING & PARTICIPANTS: 1,530 patients with IgAN and at least 12 months of follow-up at Peking University First Hospital. EXPOSURE: Proteinuria levels updated over time (time-varying proteinuria, TVP). OUTCOME: A composite kidney outcome of a 50% reduction in the estimated glomerular filtration rate or end-stage kidney disease. ANALYTICAL APPROACH: Marginal structural models. RESULTS: After a median follow-up period of 43.5 (IQR, 27.2-72.8) months, 254 patients (16.6%) developed the composite kidney outcome. A graded association was observed between TVP and composite kidney outcomes with higher risk among those with proteinuria of≥0.5g/day. Compared with TVP<0.3g/day, the HRs for proteinuria levels of 0.3 to<0.5g/day, 0.5 to<1.0g/day, 1.0 to<2.0g/day, and≥2.0g/day were 2.22 (95% CI, 0.88-5.58), 4.04 (95% CI, 1.93-8.46), 8.46 (95% CI, 3.80-18.83), and 38.00 (95% CI, 17.62-81.95), respectively. The trend was more pronounced in patients with baseline proteinuria of≥1.0g/day, among whom a higher risk was observed with TVP of 0.3 to<0.5g/day compared with TVP<0.3g/day (HR, 3.26 [95% CI, 1.07-9.92], P=0.04). However, in patients with baseline proteinuria levels of<1g/day, the risk of composite kidney outcome only began to increase when TVP was≥1.0g/day (HR, 3.25 [95% CI, 1.06-9.90]). LIMITATIONS: Single-center observational study, selection bias, and unmeasured confounders. CONCLUSIONS: This study showed that patients with IgAN and proteinuria levels of>0.5g/day, have an elevated risk of kidney failure especially among patients with proteinuria levels≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN. PLAIN-LANGUAGE SUMMARY: The presence of proteinuria has often been considered a surrogate end point and a possible therapeutic target in clinical trials in IgA nephropathy (IgAN). Some guidelines recommend a reduction in proteinuria to<1g/day as a treatment goal based on the results of previous longitudinal studies. However, these findings may have been biased because they did not properly adjust for time-dependent confounders. Using marginal structural models to appropriately account for these confounding influences, we observed that patients with IgAN and proteinuria levels≥0.5g/day have an elevated risk of kidney failure, especially among patients who had proteinuria levels of≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN.

Association between urinary C4d levels and disease progression in IgA nephropathy.

BACKGROUND: C4d mesangial deposition, a hallmark of lectin pathway activation in IgA nephropathy (IgAN), has been shown to be associated with risk of kidney failure. To date, the relationship between urinary C4d and renal outcome remain unelucidated. METHODS: A total of 508 patients with biopsy-proven IgAN were enrolled in this study, whose baseline urine samples at the time of biopsy were collected and the levels of urinary C4d were quantified by enzyme-linked immunosorbent assay. The time-averaged C4d (TA-C4d) and the change in proteinuria were measured in sequential urine samples obtained from IgAN patients. The kidney progression event was defined as a 50% estimated glomerular filtration rate (eGFR) decline or end-stage kidney disease (ESKD) or death. RESULTS: After a median follow-up of 36 months, 70 (13.8%) of the participants reached the kidney progression event. Higher levels of urinary C4d/creatinine were found to be associated with decreased eGFR, massive proteinuria, lower serum albumin levels, hypertension, and severe Oxford E and T scores. Upon adjusting for traditional risk factors (including demographics, eGFR, proteinuria, hypertension, Oxford pathologic score, and immunosuppressive therapy), elevated levels of urinary C4d/creatinine were independently associated with an increased risk of CKD progression (adjusted HR per standard deviation increment of log-transformed C4d/creatinine: 1.46; 95% CI: 1.04 to 2.06; P=0.030). In reference to the low C4d group, the risk of poor renal outcome increased for the high C4d group (adjusted HR: 1.93; 95% CI: 1.05 to 3.54; P=0.033). Additionally, a low baseline C4d level was independently assosicated with a favorable proteinuria response to immunosuppressive therapy at three months (adjusted relative risk: 2.20; 95% CI: 1.04-4.63, P=0.038). CONCLUSION: The urinary C4d, serving as a non-invasive biomarker, is associated with the progression of IgAN and holds the potential to predict proteinuria response in this disease.

Genetic Variants of the COL4A3 , COL4A4 , and COL4A5 Genes Contribute to Thinned Glomerular Basement Membrane Lesions in Sporadic IgA Nephropathy Patients.

BACKGROUND: Thinned glomerular basement membrane (tGBM) lesions are not uncommon in IgA nephropathy (IgAN). Type IV collagen-built of α 3, α 4, and α 5 chains, encoded by COL4A3 / COL4A4 / COL4A5 genes-is the major component of glomerular basement membrane (GBM). In recent years, mutations in type IV collagen-encoding genes were also reported in patients with a histologic diagnosis of FSGS. Pathogenic COL4A3 / COL4A4 / COL4A5 variants were recently identified in familial cases of IgAN, but the contribution of these variants to sporadic IgAN is still unclear. METHODS: We compared 161 patients with sporadic IgAN with tGBM lesions (IgAN-tGBM) to matched patients with IgAN without tGBM lesions and matched patients with thin basement membrane nephropathy (TBMN). Variants of COL4A3 / COL4A4 / COL4A5 genes were screened and evaluated after whole-exome sequencing. GBM thickness was measured, and levels of circulating galactose-deficient IgA1 (Gd-IgA1) were assessed by ELISA. RESULTS: The patients with IgAN-tGBM manifested milder disease than did patients with IgAN without tGBM but had more severe features than the patients with TBMN. Exome sequence analysis of the 122 patients with IgAN-tGBM identified 37 diagnostic variants of the COL4A3 / COL4A4 / COL4A5 genes among 38 patients (31.1%). Furthermore, patients with IgAN-tGBM who had diagnostic variants had higher proportions of GBM thickness <250 nm and milder glomerular injury, whereas patients with IgAN-tGBM who did not have diagnostic variants showed more characteristic features of IgAN, including higher intensity of glomerular IgA deposits and elevated Gd-IgA1 levels. These findings suggest different mechanisms in patients with versus without diagnostic variants of these collagen genes. CONCLUSIONS: COL4A3 / COL4A4 / COL4A5 variant detection is essential in evaluating patients with sporadic IgAN with tGBM lesions.

MTMR3 risk alleles enhance Toll Like Receptor 9-induced IgA immunity in IgA nephropathy.

Multiple genome-wide association studies (GWASs) have reproducibly identified the MTMR3/HORMAD2/LIF/OSM locus to be associated with IgA nephropathy (IgAN). However, the causal variant(s), implicated gene(s), and altered mechanisms remain poorly understood. Here, we performed fine-mapping analyses based on GWAS datasets encompassing 2762 IgAN cases and 5803 control individuals, and identified rs4823074 as the candidate causal variant that intersects the MTMR3 promoter in B-lymphoblastoid cells. Mendelian randomization studies suggested the risk allele may modulate disease susceptibility by affecting serum IgA levels through increased MTMR3 expression. Consistently, elevated MTMR3 expression in peripheral blood mononuclear cells was observed in patients with IgAN. Further mechanistic studies in vitro demonstrated that MTMR3 increased IgA production dependent upon its phosphatidylinositol 3-phosphate binding domain. Moreover, our study provided the in vivo functional evidence that Mtmr3-/- mice exhibited defective Toll Like Receptor 9-induced IgA production, glomerular IgA deposition, as well as mesangial cell proliferation. RNA-seq and pathway analyses showed that MTMR3 deficiency resulted in an impaired intestinal immune network for IgA production. Thus, our results support the role of MTMR3 in IgAN pathogenesis by enhancing Toll Like Receptor 9-induced IgA immunity.

Discontinuation of Renin-Angiotensin System Inhibitors and Clinical Outcomes in Chronic Kidney Disease: A Systemic Review and Meta-Analysis.

BACKGROUND: Discontinuation of renin-angiotensin system (RAS) inhibitors is common in patients with chronic kidney disease (CKD), and the potential danger has been reported in several studies. However, a comprehensive analysis has not been conducted. OBJECTIVES: This study sought to evaluate the effects of discontinuation of RAS inhibitors in CKD. METHOD: Relevant studies up to November 30, 2022, were identified in the PubMed, Embase, Web of Science, and Cochrane Library databases. Efficacy outcomes included the composite of all-cause mortality, cardiovascular events, and end-stage kidney disease (ESKD). Results were combined using a random-effects or fixed-effects model, and sensitivity analysis used the leave-one-out method. RESULTS: Six observational studies and one randomized clinical trial including 244,979 patients met the inclusion criteria. Pooled data demonstrated that discontinuation of RAS inhibitors was associated with an increased risk of all-cause mortality (HR 1.42, 95% CI 1.23-1.63), cardiovascular event risk (HR 1.25, 95% CI 1.17-1.22), and ESKD (HR 1.23, 95% CI 1.02-1.49). In sensitivity analyses, the risk for ESKD was reduced. Subgroup analysis showed that the risk of mortality was more pronounced in patients with eGFR above 30 mL/min/m2 and in patients with hyperkalemia-related discontinuation. In contrast, patients with eGFR below 30 mL/min/m2 were at great risk of cardiovascular events. CONCLUSIONS: The discontinuation of RAS inhibitors in patients with CKD was associated with a significantly increased risk of all-cause mortality and cardiovascular events. These data suggest that RAS inhibitors should be continued in CKD if the clinical situation allows.

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.

Comparison between hydroxychloroquine and systemic corticosteroids in IgA nephropathy: a two-year follow-up study.

BACKGROUND: Hydroxychloroquine (HCQ) is recommended as a treatment for IgA nephropathy (IgAN) to control proteinuria. The long-term effects of HCQ compared to systemic corticosteroid therapy remain unclear. METHODS: We conducted a retrospective case‒control study at Peking University First Hospital. Thirty-nine patients with IgAN who received HCQ for at least 24 months without corticosteroids (CSs) or other immunosuppressive agents were included. Thirty-nine matched patients who received systemic CS therapy were selected using propensity score matching. Clinical data over a 24-month period were compared. RESULTS: In the HCQ group, the level of proteinuria decreased from 1.72 [1.44, 2.35] to 0.97 [0.51, 1.37] g/d (-50.5 [-74.0, -3.4] %, P < 0.001) at 24 months. A significant decline in proteinuria was also found in the CS group, but no significant differences were found between the HCQ group and CS group in the levels of proteinuria (0.97 [0.51, 1.37] vs. 0.53 [0.25, 1.81] g/d, P = 0.707) and change rates (-50.5% [-74.0%, -3.4%] vs. -63.7% [-78.5%, -24.2%], P = 0.385) at 24 months. In addition, the decline rates of eGFR between the HCQ and CS groups were comparable (-7.9% [-16.1%, 5.8%] vs. -6.6% [-14.9%, 5.3%], P = 0.758). More adverse events were observed in the CS group. CONCLUSIONS: Long-term use of HCQ can maintain stable renal function with minimal side effects. In patients who cannot tolerate corticosteroids, HCQ might be an effective and safe supportive therapy for IgAN.

Particulate matter of air pollution may increase risk of kidney failure in IgA nephropathy.

IgA nephropathy (IgAN) is characterized by deposition of galactose-deficient IgA1 (Gd-IgA1) in glomerular mesangium associated with mucosal immune disorders. Since environmental pollution has been associated with the progression of chronic kidney disease in the general population, we specifically investigated the influence of exposure to fine particulate matter less than 2.5 µm in diameter (PM2.5) on IgAN progression. Patients with biopsy-proven primary IgAN were recruited from seven Chinese kidney centers. PM2.5 exposure from 1998 to 2016 was derived from satellite aerosol optical depth data and a total of 1,979 patients with IgAN, including 994 males were enrolled. The PM2.5 exposure levels for patients from different provinces varied but, in general, the PM2.5 exposure levels among patients from the north were higher than those among patients from the south. The severity of PM2.5 exposure in different regions was correlated with regional kidney failure burden. In addition, each 10 µg/m3 increase in annual average concentration of PM2.5 exposure before study entry (Hazard Ratio, 1.14; 95% confidence interval, 1.06-1.22) or time-varying PM2.5 exposure after study entry (1.10; 1.01-1.18) were associated with increased kidney failure risk after adjustment for age, gender, estimated glomerular filtration rate, urine protein, uric acid, hemoglobin, mean arterial pressure, Oxford classification, glucocorticoid and renin-angiotensin system blocker therapy. The associations were robust when the time period, risk factors of cardiovascular diseases or city size were further adjusted on the basis of the above model. Thus, our results suggest that PM2.5 is an independent risk factor for kidney failure in patients with IgAN, but these findings will require validation in more diverse populations and other geographic regions.

The level of urinary C4d is associated with disease progression in IgA nephropathy with glomerular crescentic lesions: a cohort study.

BACKGROUND: Positive glomerular C4d staining, representative of lectin pathway activation, has been proven to be associated with unfavorable outcomes in immunoglobulin A nephropathy (IgAN). Our previous study suggested that urinary C4d correlated positively with an increase in crescents while the relationship between urinary C4d and disease severity and progression remains unelucidated. METHODS: In this study we enrolled 168 patients diagnosed with IgAN with varying proportions of crescent formation at the time of biopsy. An independent cohort of 107 IgAN patients was enrolled for validation. Kidney biopsy specimens were stained using immunohistochemistry. Urinary C4d levels at renal biopsy were measured by enzyme-linked immunosorbent assay. The primary endpoint was end-stage kidney disease (ESKD). RESULTS: Higher urinary C4d/creatinine levels were associated with a lower estimated glomerular filtration rate (eGFR); massive proteinuria; hypertension and severe Oxford M, E, T and C scores. After a median follow-up of 19 months (interquartile range 9-27), 53 (31.5%) participants reached ESKD. High urinary C4d/creatinine levels were independently and significantly associated with a risk of developing ESKD [hazard ratio per standard deviation increment of log-transformed C4d/creatinine 7.623 (95% confidence interval 4.117-14.113)]. CONCLUSIONS: The urinary C4d/creatinine level is a potential useful biomarker that was associated with disease severity and progression in patients with IgAN and crescents.

Rapidly progressive IgA nephropathy: clinicopathological characteristics and outcomes assessed according to the revised definition of the KDIGO 2021 Guideline.

BACKGROUND: Rapidly progressive immunoglobulin A nephropathy (RPIgAN) is a severe clinical phenotype of IgAN associated with a poor outcome. The recently published Kidney Disease: Improving Global Outcomes (KDIGO) 2021 Guideline for the Management of Glomerular Diseases has proposed a new definition for RPIgAN that is based simply on a ≥50% decline in the estimated glomerular filtration rate (eGFR) over ≤3 months. METHODS: In 1677 IgAN patients followed at a single centre in China, we evaluated the utility of this new definition to identify the highest-risk IgAN patients who might be suitable for combination immunosuppressive therapy. RESULTS: The proportion of a ≥50% decline in eGFR over ≤3 months was 5.2%. The majority of these patients had reversible causes, with only 2.3% (39/1677) meeting the KDIGO 2021 criteria for RPIgAN. These patients had a significantly higher risk for end-stage kidney disease (ESKD) than non-RPIgAN patients (logrank P < 0.001). RPIgAN was an independent risk factor for ESKD [hazard ratio 3.99 (95% confidence interval 2.25-7.09); P <0.001]. A minority of the RPIgAN patients (25.6%) had ≥50% crescents. There was no significant difference in the risk for ESKD between patients in the RPIgAN group with ≥50% crescents and ˂50% crescents (logrank P = 0.27). Patients with RPIgAN and ≥50% crescents had a higher risk for ESKD than patients with non-RPIgAN and ≥50% crescents (logrank P = 0.04). CONCLUSIONS: These data support the validity of the KDIGO 2021 definition but require independent validation in other non-Chinese cohorts.

Endothelial injury by circulating IgA1 complex through the activation of mesangial cells in IgA nephropathy.

BACKGROUND: IgA nephropathy (IgAN) commonly entails arteriolar microangiopathic (MA) lesions of the kidneys. The most significant reason for MA lesions is endothelial injury, although the mechanism of injury to the vascular endothelium is not clear. MATERIALS AND METHODS: 59 patients with IgAN and 19 healthy controls were included for measuring the blood von Willebrand factor (vWF), soluble vascular cell adhesion molecule-1 (sVCAM1), and heparin-binding EGF-like growth factor (HB-EGF) by ELISA. Circulating IgA1 (cIgA1) was isolated from 12 patients with primary IgAN and 10 healthy controls. Then, the supernatant of growth-arrested human mesangial cells (HMCs) in a medium with cIgA1 was used to prepare the cIgA1-human mesangial cell medium (cIgA1-HMCM). Human umbilical vein endothelial cells (HUVECs) were grown in this medium along with or without Panax notoginseng saponins (PNS). ELISA was employed for the quantification of IL-6, CXCL1 and HB-EGF levels in cIgA1-HMCM, vWF, sVCAM1, and HB-EGF in the HUVEC medium. RESULTS: The concentration of vWF, sVCAM-1, and HB-EGF was higher in the patients than in the healthy participants. The expressions of IL-6 and CXCL1 in HMCM were significantly higher in cIgA1 from patients with IgAN (IgAN-cIgA1) than from healthy controls. Levels of vWF, sVCAM-1, and HB-EGF induced by conditioned HMCM treated with IgAN-cIgA1 (IgAN-HMCM) were conspicuously more than those induced in healthy controls-HMCM (HC-HMCM). After culturing HUVECs in IgAN-HMCM and PNS, the vWF, sVCAM-1 and HB-EGF were remarkably low in the supernatants of cells grown in IgAN-HMCM+PNS compared to those grown in IgAN-HMCM only. CONCLUSION: Activation of mesangial cells in vitro may occur by cIgA1 and, thus, cause endothelial cell injury via inflammation factors.

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.

FAM49B promotes breast cancer proliferation, metastasis, and chemoresistance by stabilizing ELAVL1 protein and regulating downstream Rab10/TLR4 pathway.

BACKGROUND: Breast cancer (BC) is one of the most common cancers and the leading cause of death in women. Previous studies have demonstrated that FAM49B is implicated in several tumor progression, however, the role and mechanism of FAM49B in BC remain to be explored. Therefore, in this study, we aimed to systematically study the role of FAM49B in the proliferation, metastasis, apoptosis, and chemoresistance of BC, as well as the corresponding molecular mechanisms and downstream target. METHODS: The ONCOMINE databases and Kaplan-Meier plotter databases were analyzed to find FAM49B and its prognostic values in BC. FAM49B expression in BC and adjacent non-tumor tissues was detected by western blot and IHC. Kaplan-Meier analysis was used to identify the prognosis of BC patients. After FAM49B knockdown in MCF-7 and MDA-MB-231 cells, a combination of co-immunoprecipitation, MTT, migration, and apoptosis assays, nude mouse xenograft tumor model, in addition to microarray detection and data analysis was used for further mechanistic studies. RESULTS: In BC, the results showed that the expression level of FAM49B was significantly higher than that in normal breast tissue, and highly expression of FAM49B was significantly positively correlated with tumor volume, histological grade, lymph node metastasis rate, and poor prognosis. Knockdown of FAM49B inhibited the proliferation and migration of BC cells in vitro and in vivo. Microarray analysis revealed that the Toll-like receptor signaling pathway was inhibited upon FAM49B knockdown. In addition, the gene interaction network and downstream protein validation of FAM49B revealed that FAM49B positively regulates BC cell proliferation and migration by promoting the Rab10/TLR4 pathway. Furthermore, endogenous FAM49B interacted with ELAVL1 and positively regulated Rab10 and TLR4 expression by stabilizing ELAVL1. Moreover, mechanistic studies indicated that the lack of FAM49B expression in BC cells conferred more sensitivity to anthracycline and increased cell apoptosis by downregulating the ELAVL1/Rab10/TLR4/NF-κB signaling pathway. CONCLUSION: These results demonstrate that FAM49B functions as an oncogene in BC progression, and may provide a promising target for clinical diagnosis and therapy of BC.

Mass spectrometry-based screening identifies circulating immunoglobulinA-α1-microglobulin complex as potential biomarker in immunoglobulin A nephropathy.

BACKGROUND: Immunoglobulin A nephropathy (IgAN) is characterized by predominant IgA deposition in the glomerular mesangium. Previous studies have proved that renal-deposited IgA in IgAN came from circulating IgA1-containing complexes (CICs). METHODS: To explore the composition of CICs in IgAN, we isolated CICs from IgAN patients and healthy controls and then quantitatively analyzed them by mass spectrometry. Meanwhile, the isolated CICs were used to treat human mesangial cells to monitor mesangial cell injury. Using the protein content and injury effects, the key constituent in CICs was identified. Then the circulating levels of identified key constituent-IgA complex were detected in an independent population by an in-house-developed enzyme-linked immunosorbent assay. RESULTS: By comparing the proteins of CICs between IgAN patients and controls, we found that 14 proteins showed significantly different levels. Among them, α1-microglobulin content in CICs was associated with not only in vitro mesangial cell proliferation and monocyte chemoattractant protein 1 secretion, but also in vivo estimated glomerular filtration rate (eGFR) levels and tubulointerstitial lesions in IgAN patients. Moreover, we found α1-microglobulin was prone to bind aberrant glycosylated IgA1. Additionally, elevated circulating IgA-α1-microglobulin complex levels were detected in an independent IgAN population and IgA-α1-microglobulin complex levels were correlated with hypertension, eGFR levels and Oxford T- scores in these IgAN patients. CONCLUSIONS: Our results suggest that the IgA-α1-microglobulin complex is an important constituent in CICs and that circulating IgA-α1-microglobulin complex detection might serve as a potential noninvasive biomarker detection method for IgAN.

Associations of ABO blood type and galactose-deficient immunoglobulin A1 with adverse outcomes in patients with IgA nephropathy.

BACKGROUND: Both ABO blood group antigens and pathogenic immunoglobulin A1 (IgA1) in patients with IgA nephropathy (IgAN) are influenced by modifications of N-acetylgalactosamine and galactose. The purpose of this study was to assess whether ABO blood type is associated with galactose-deficient IgA1 (Gd-IgA1) in the progression of kidney disease in patients with IgAN. METHODS: We enrolled 1313 IgAN patients with a median of 44 months follow-up and measured the plasma Gd-IgA1 levels. Multivariate Cox regression models were used to estimate the association between all variables and adverse outcomes. Using the propensity score matching method, 718 IgAN patients with blood type either A or B were selected, and their data were used to assess the association of blood type and Gd-IgA1/serum complement 3 (sC3) with outcomes. RESULTS: We found that the risk of adverse outcomes was significantly higher in patients with blood type A than in those with type B (hazard ratio = 1.82, 95% confidence interval 1.23-2.71; P = 0.003) after multivariate adjustment. The Gd-IgA1 levels showed trends similar to the multivariate-adjusted event-free curves for the blood types. However, this higher risk of adverse outcomes in type A than in type B patients was no longer significant after the addition of Gd-IgA1/sC3 to the model. CONCLUSIONS: IgAN patients with blood type A had a higher risk of adverse outcomes than those with type B, and this risk was associated with Gd-IgA1/sC3. Thus, the ABO blood type may provide a reference for the prognostic factors for individuals with IgAN.

Persistent Hematuria and Kidney Disease Progression in IgA Nephropathy: A Cohort Study.

RATIONALE & OBJECTIVE: Hematuria is the most typical presentation of immunoglobulin A nephropathy (IgAN); however, its role in disease progression is still controversial. This study aimed to evaluate the association of hematuria and progression of IgAN. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: A cohort of 1,333 patients with IgAN treated at a Chinese referral hospital with a median follow-up of 45 months. PREDICTORS: Microhematuria was evaluated in fresh urine using a fully automated urine particle analyzer (automated method) and urine sediment examination by a skilled examiner (manual method). Hematuria was characterized as a time-varying attribute; namely, average hematuria level was calculated for every 6-month period for each patient during follow-up. Remission was defined as average red blood cell count ≤5/high-power field (manual method) or ≤28 red blood cells/µL (automated method) during the first 6 months of follow-up. OUTCOMES: Composite event of 50% decline in estimated glomerular filtration rate or development of kidney failure. ANALYTICAL APPROACH: Multivariable cause-specific hazards models to analyze the relationship between hematuria and the composite kidney disease progression event. RESULTS: Time-varying hematuria during follow-up was an independent risk factor for the composite kidney disease progression event (HR, 1.46; 95% CI, 1.13-1.87; P = 0.003). Hematuria remission during the 6 months after diagnosis was associated with a significantly lower rate of the composite kidney disease progression event (HR, 0.41; 95% CI, 0.28-0.61; P < 0.001). A significant interaction was detected between remission of proteinuria and remission of hematuria during the first 6 months (P < 0.001). The association between remission of hematuria and kidney disease progression was detectable (HR, 0.46; 95% CI, 0.32-0.68) within the subpopulation with persistent proteinuria (protein excretion > 1.0 g/d during the first 6 months), but not among patients whose proteinuria had remitted (HR, 0.64; 95% CI, 0.31-1.29; P = 0.2). The 2 techniques for hematuria evaluation were strongly and significantly linearly correlated (r = 0.948; P < 0.001), and results using these 2 methods were consistent. LIMITATIONS: A single-center retrospective study. Proportional hazards regression incorporating time-varying covariates may create time-varying confounding. The predictive value of reductions in hematuria was not directly evaluated. CONCLUSIONS: Level of hematuria was independently associated with kidney disease progression, whereas hematuria remission was associated with improved kidney outcomes in IgAN among patients with persistent proteinuria. Additionally, to monitor IgAN progression, automated methods to evaluate hematuria hold promise as a replacement for manual evaluation of urinary sediment.

Plasma galactose-deficient immunoglobulin A1 and loss of kidney function in patients with immunoglobulin A vasculitis nephritis.

BACKGROUND: Immunoglobulin A (IgA) vasculitis nephritis (IgAV-N) is the most common secondary IgA nephropathy (IgAN). Many studies have demonstrated that galactose-deficient IgA1 (Gd-IgA1) in the IgA1 hinge region is associated with the development and also progression of primary IgAN. In this study, we aimed to evaluate the roles of Gd-IgA1 in kidney disease progression in a large Chinese cohort of IgAV-N patients. METHODS: This cohort study enrolled 112 patients with IgAV-N, 15 patients with IgA vasculitis (IgAV) without kidney involvement and 108 patients with IgAN. Plasma IgA1 and Gd-IgA1 levels at kidney biopsy were measured by enzyme-linked immunosorbent assay. The primary endpoint was a 30% decline in estimated glomerular filtration rate or end-stage renal disease or death. RESULTS: The levels of Gd-IgA1 in IgAV-N and IgAN patients were higher than in healthy controls (mean ± SD, 302.86 ± 54.93 U/mL versus 303.16 ± 59.43 U/mL versus 281.30 ± 43.74 U/mL, respectively; P = 0.047), as well as compared with those with IgAV without kidney involvement (272.65 ± 53.14 U/mL; P = 0.036). After adjusting clinical data, higher levels of Gd-IgA1 were found to be independently associated with a greater risk for kidney failure [hazard ratio (HR) = 1.703 per 1 SD, 95% confidence interval (CI) 1.233-2.352; P = 0.001]. Compared with the first Gd-IgA1 quartile group (as reference), the fourth Gd-IgA1 quartile group retained a predictive value for poor renal outcome (HR = 3.740, 95% CI 1.204-11.619; P = 0.023). CONCLUSIONS: These data indicate that Gd-IgA1 levels were similarly elevated in adult patients with IgAN and those with IgAV-N. Moreover, increased Gd-IgA1 levels were associated with both the development and progression of IgAV-N, as observed in IgAN.

Variation in complement factor H affects complement activation in immunoglobulin A vasculitis with nephritis.

BACKGROUND: Immunoglobulin A (IgA) vasculitis with nephritis (IgAVN) and IgA nephropathy (IgAN) are widely considered as related diseases. Considerable evidences support the notion of involvement of complement activation in both IgAVN and IgAN. Our previous studies identified a genetic variant in complement factor H (CFH), rs6677604, as an IgAN-susceptible variant by genome-wide association study, and further confirmed its linkage to CFHR3-1Δ and proved its influence on complement activation and thereby on IgAN susceptibility. AIM: To explore the role of rs6677604 in complement activation of IgAVN. METHODS: In this study, we enrolled 632 patients with IgAVN, 1178 patients with IgAN and 902 healthy controls. The genotype of rs6677604 was measured by TaqMan allele discrimination assays or was extracted from genome-wide association study data. RESULTS: The frequency of the rs6677604-A allele was significantly higher in IgAVN than in IgAN. However, no significant differences were observed between IgAVN and the controls. Higher complement factor H (FH) levels were observed in IgAVN than IgAN, and positive correlation between circulating FH and C3 levels was present in IgAVN. In both IgAVN and IgAN, rs6677604-A was associated with less intensity of glomerular C3 deposits. In agreement with the higher frequency of rs6677604-A in IgAVN, the glomerular C3 deposits of patients with IgAVN were less intense than those in IgAN. CONCLUSION: Our findings suggest that genetic variation in CFH (rs6677604) is involved in the phenotype of complement activation in both IgAVN and IgAN. Moreover, rs6677604 might contribute to the difference of complement activation intensity between IgAVN and IgAN.

Effect of hydroxychloroquine in patients with IgA nephropathy with insufficient responses to immunosuppressive therapy: a retrospective case-control study.

BACKGROUND: Hydroxychloroquine (HCQ) is a well-known immunomodulator that was recently used in immunoglobulin A (IgA) nephropathy (IgAN) due to its antiproteinuric effects. We investigated the effects of HCQ in patients with IgAN whose proteinuria remained above 1 g/d after conventional immunosuppressive (IS) therapy. METHODS: This study was a retrospective case-control study. Twenty-six patients with IgAN who received HCQ and had insufficient responses to IS therapy (corticosteroid (CS) therapy with/without IS agents) were included. Twenty-six matched historical controls who received conventional IS therapy were selected using propensity score matching. The clinical data from 6 months were compared. RESULTS: Proteinuria at baseline was comparable between the "IS therapy plus HCQ" and "conventional IS therapy" groups (2.35 [interquartile range (IQR), 1.47, 2.98] vs. 2.35 [IQR, 1.54, 2.98] g/d, p = 0.920). A significant reduction in proteinuria was noted in IgAN patients with HCQ treatment (2.35 [IQR, 1.47, 2.98] vs. 1.10 [IQR, 0.85, 1.61] g/d, p = 0.002). The percent reduction in proteinuria at 6 months was similar between the two groups (- 39.81% [- 66.26, - 12.37] vs. -31.99% [- 67.08, - 9.14], p = 0.968). The cumulative frequency of patients with a 50% reduction in proteinuria during the study was also comparable between the two groups (53.8% vs. 57.7%, p = 0.780). No serious adverse events (SAEs) were observed during the study. CONCLUSIONS: Use of HCQ achieved has similar reduction in proteinuria compared to conventional IS therapy in patients with IgAN who had insufficient responses to IS therapy.