Xueqing Yu

Modified Glomerular Filtration Rate Estimating Equation for Chinese Patients with Chronic Kidney Disease

The Modification of Diet in Renal Disease (MDRD) equations provide a rapid method of assessing GFR in patients with chronic kidney disease (CKD). However, previous research indicated that modification of these equations is necessary for application in Chinese patients with CKD. The objective of this study was to modify MDRD equations on the basis of the data from the Chinese CKD population and compare the diagnostic performance of the modified MDRD equations with that of the original MDRD equations across CKD stages in a multicenter, cross-sectional study of GFR estimation from plasma creatinine, demographic data, and clinical characteristics. A total of 684 adult patients with CKD, from nine geographic regions of China were selected. A random sample of 454 of these patients were included in the training sample set, and the remaining 230 patients were included in the testing sample set. With the use of the dual plasma sampling (99m)Tc-DTPA plasma clearance method as a reference for GFR measurement, the original MDRD equations were modified by two methods: First, by adding a racial factor for Chinese in the original MDRD equations, and, second, by applying multiple linear regression to the training sample and modifying the coefficient that is associated with each variable in the original MDRD equations and then validating in the testing sample and comparing it with the original MDRD equations. All modified MDRD equations showed significant performance improvement in bias, precision, and accuracy compared with the original MDRD equations, and the percentage of estimated GFR that did not deviate >30% from the reference GFR was >75%. The modified MDRD equations that were based on the Chinese patients with CKD offered significant advantages in different CKD stages and could be applied in clinical practice, at least in Chinese patients with CKD.

Prevalence of chronic kidney disease in China: a cross-sectional survey.

BACKGROUND The prevalence of chronic kidney disease is high in developing countries. However, no national survey of chronic kidney disease has been done incorporating both estimated glomerular filtration rate (eGFR) and albuminuria in a developing country with the economic diversity of China. We aimed to measure the prevalence of chronic kidney disease in China with such a survey. METHODS We did a cross-sectional survey of a nationally representative sample of Chinese adults. Chronic kidney disease was defined as eGFR less than 60 mL/min per 1·73 m(2) or the presence of albuminuria. Participants completed a lifestyle and medical history questionnaire and had their blood pressure measured, and blood and urine samples taken. Serum creatinine was measured and used to estimate glomerular filtration rate. Urinary albumin and creatinine were tested to assess albuminuria. The crude and adjusted prevalence of indicators of kidney damage were calculated and factors associated with the presence of chronic kidney disease analysed by logistic regression. FINDINGS 50,550 people were invited to participate, of whom 47,204 agreed. The adjusted prevalence of eGFR less than 60 mL/min per 1·73 m(2) was 1·7% (95% CI 1·5-1·9) and of albuminuria was 9·4% (8·9-10·0). The overall prevalence of chronic kidney disease was 10·8% (10·2-11·3); therefore the number of patients with chronic kidney disease in China is estimated to be about 119·5 million (112·9-125·0 million). In rural areas, economic development was independently associated with the presence of albuminuria. The prevalence of chronic kidney disease was high in north (16·9% [15·1-18·7]) and southwest (18·3% [16·4-20·4]) regions compared with other regions. Other factors independently associated with kidney damage were age, sex, hypertension, diabetes, history of cardiovascular disease, hyperuricaemia, area of residence, and economic status. INTERPRETATION Chronic kidney disease has become an important public health problem in China. Special attention should be paid to residents in economically improving rural areas and specific geographical regions in China. FUNDING The Ministry of Science and Technology (China); the Science and Technology Commission of Shanghai; the National Natural Science Foundation of China; the Department of Health, Jiangsu Province; the Sichuan Science and Technology Department; the Ministry of Education (China); the International Society of Nephrology Research Committee; and the China Health and Medical Development Foundation.

The aging kidney.

Renal aging, by itself, is associated with alterations in renal morphology and a decline in renal function, which is accelerated and/or accentuated by diseases such as diabetes mellitus and hypertension. The aging-related renal insufficiency has important implications with regards to body homeostasis, drug toxicity, and renal transplantation. An understanding of renal aging and its distinction from renal insufficiency secondary to diseases is essential for individualized care of the elderly. Toward this end, investigations are underway to elucidate the molecular mechanisms of renal aging. This review summarizes the structural and functional changes of the aging kidney and highlights the advances made in our understanding of the renal aging process.

A genome-wide association study in Han Chinese identifies multiple susceptibility loci for IgA nephropathy

We performed a two-stage genome-wide association study of IgA nephropathy (IgAN) in Han Chinese, with 1,434 affected individuals (cases) and 4,270 controls in the discovery phase and follow-up of the top 61 SNPs in an additional 2,703 cases and 3,464 controls. We identified associations at 17p13 (rs3803800, P = 9.40 × 10−11, OR = 1.21; rs4227, P = 4.31 × 10−10, OR = 1.23) and 8p23 (rs2738048, P = 3.18 × 10−14, OR = 0.79) that implicated the genes encoding tumor necrosis factor (TNFSF13) and α-defensin (DEFA) as susceptibility genes. In addition, we found multiple associations in the major histocompatibility complex (MHC) region (rs660895, P = 4.13 × 10−20, OR = 1.34; rs1794275, P = 3.43 × 10−13, OR = 1.30; rs2523946, P = 1.74 × 10−11, OR = 1.21) and confirmed a previously reported association at 22q12 (rs12537, P = 1.17 × 10−11, OR = 0.78). We also found that rs660895 was associated with clinical subtypes of IgAN (P = 0.003), proteinuria (P = 0.025) and IgA levels (P = 0.047). Our findings show that IgAN is associated with variants near genes involved in innate immunity and inflammation.

Short-term Outcomes of Induction Therapy With Tacrolimus Versus Cyclophosphamide for Active Lupus Nephritis: A Multicenter Randomized Clinical Trial

BACKGROUND Intravenous cyclophosphamide with prednisone is an effective treatment for lupus nephritis, but with significant toxicities. We compared the efficacy and safety of tacrolimus versus intravenous cyclophosphamide as induction therapy. STUDY DESIGN Multicenter noninferiority randomized controlled trial. SETTING & PARTICIPANTS 81 patients with biopsy-proven lupus nephritis from 9 nephrology centers in China from 2006-2008. INTERVENTION Prednisone and either tacrolimus (n = 42) or intravenous cyclophosphamide (n = 39) for 6 months. Tacrolimus was started at 0.05 mg/kg/d and titrated to achieve a trough blood concentration of 5-10 ng/mL. Intravenous cyclophosphamide was initiated at 750 mg/m² of body surface area, then adjusted to 500-1,000 mg/m² every 4 weeks for a total of 6 pulse treatments. OUTCOMES & MEASUREMENTS The primary outcome was complete remission (proteinuria with protein excretion <0.3 g/24 h, serum albumin ≥3.5 g/dL, normal urinary sediment, and normal or stable serum creatinine level) at 6 months. Response (complete or partial remission), clinical parameters, and adverse effects were secondary end points. RESULTS After the 6-month induction therapy, the tacrolimus group achieved higher cumulative probabilities of complete remission and response (52.4% vs 38.5% and 90.5% vs 82.1%, respectively) than the intravenous cyclophosphamide group, but differences were not statistically significant (log-rank test, P = 0.2 and P = 0.7, respectively). Proteinuria [corrected] was significantly decreased in tacrolimus- versus intravenous cyclophosphamide-treated patients after the first month of treatment, even with adjustment for baseline proteinuria (protein excretion, 1.76 vs 2.40 g/d; P = 0.02 for the log-transformed analysis). [corrected] After treatment, serum creatinine levels and estimated glomerular filtration rates were not significantly different between treatment groups. Adverse effects, such as leukopenia and gastrointestinal symptoms, were less frequent in the tacrolimus group. LIMITATIONS Nonblinded, small sample size, and short duration of follow-up. CONCLUSIONS In conjunction with prednisone, induction therapy with tacrolimus is at least as efficacious as intravenous cyclophosphamide and prednisone in producing complete remission of lupus nephritis and has a more favorable safety profile.

Prevalence and risk factors associated with chronic kidney disease in an adult population from southern China.

BACKGROUND Population-based studies evaluating the prevalence of kidney damage in different communities have been limited in developing countries. We conducted a population-based screening study in the southern Chinese city of Guangzhou that aimed to identify the prevalence and associated risk factors of chronic kidney disease (CKD) in southern Chinese populations. METHODS We interviewed 6311 residents (>20 years) from six districts of Guangzhou from July 2006 to June 2007 and tested for haematuria, albuminuria and reduced renal function. Associations between age, gender, smoking, diabetes mellitus, hypertension, hyperuricaemia and kidney damage were examined. RESULTS There were 6311 subjects enrolled in this study. After adjustment for age and gender, the prevalence of albuminuria, haematuria and reduced estimated glomerular filtration rate (eGFR) was 6.6% [95% confidence interval (CI): 5.5-7.6%], 3.8% (95% CI: 3.4%, 4.3%) and 3.2% (95% CI: 2.4%, 3.3%), respectively. Approximately 12.1% (95% CI: 11.3%, 12.9%) of the sample population had at least one indicator of kidney damage. Age, diabetes mellitus, hypertension, central obesity, hyperlipidaemia and use of nephrotoxic medications were independently associated with albuminuria; hyperuricaemia, age, gender, hypertension and use of nephrotoxic medications were independently associated with reduced eGFR, and female gender was independently associated with haematuria. CONCLUSIONS In the general adult population from southern China, 12.1% has either proteinuria, haematuria and/or reduced eGFR, indicating the presence of kidney damage, with an awareness of only 9.6%. The high prevalence and low awareness of CKD in this population suggest an urgent need for CKD prevention programmes in China.

HSP72 attenuates renal tubular cell apoptosis and interstitial fibrosis in obstructive nephropathy

Although heat shock protein 72 kDa (HSP72) protects tubular epithelium from a variety of acute insults, its role in chronic renal injury and fibrosis is poorly characterized. In this study, we tested the hypothesis that HSP72 reduces apoptosis and epithelial-to-mesenchymal transition (EMT), important contributors to tubular cell injury in vitro and in vivo. In rats, orally administered geranylgeranylacetone (GGA), an agent that selectively induces HSP72, markedly reduced both apoptosis and cell proliferation in tubular epithelium and decreased both interstitial fibroblast accumulation and collagen I deposition after unilateral ureteric obstruction, a model of chronic renal tubulointerstitial fibrosis and dysfunction. In cultured renal NRK52E cells, exposure to TGF-beta1 induced EMT and apoptosis, major causes of renal fibrosis and tubular atrophy, respectively. Exposure to a pan-caspase inhibitor (ZVAD-FMK) prevented TGF-beta1-induced apoptosis but did not reduce EMT. In contrast, selective HSP72 expression in vitro inhibited EMT caused by TGF-beta1 as indicated by preserving the E-cadherin expression level and alpha-smooth muscle actin induction. Small interfering RNA directed against HSP72 blocked the cytoprotective effects of HSP72 overexpression on EMT in TGF-beta1-exposed cells. Taken together, our data indicate that HSP72 ameliorates renal tubulointerstitial fibrosis in obstructive nephropathy by inhibiting both renal tubular epithelial cell apoptosis and EMT.

Clinical Outcome of Hyperuricemia in IgA Nephropathy: A Retrospective Cohort Study and Randomized Controlled Trial

Background: Hyperuricemia is an independent risk factor for renal progression in IgA nephropathy (IgAN). However, no study has evaluated the effect of allopurinol on the clinical outcome in hyperuricemic IgAN. Methods: First,a retrospective cohort study of 353 IgAN patients was conducted to explore the relationship between uric acid (UA) and the progression of renal disease over a mean period of 5 years. Then, 40 hyperuricemic IgAN patients were randomized to receive allopurinol (100–300 mg/day) or usual therapy for 6 months. The study outcomes were renal disease progression and/or blood pressure. Results: Hyperuricemia independently predicted renal survival at 1, 3, and 5 years after adjustment for different baseline estimated glomerular filtration rates. In the randomized controlled trial, allopurinol did not significantly alter renal progression or proteinuria. The antihypertensive drug dosage was reduced in 7 of 9 cases with hypertension in the allopurinol group compared to 0 of 9 cases in the control group (p < 0.01). UA levels correlated with mean arterial pressure in normotensive patients (r = 0.388, p < 0.001). Conclusion: Hyperuricemia predicts the progression of IgAN independently of baseline estimated glomerular filtration rate. Allopurinol may improve the control of blood pressure. Further studies are required to explore the effects of lowering UA on renal protection in IgAN.

Evaluation of the Chronic Kidney Disease Epidemiology Collaboration equation for estimating glomerular filtration rate in the Chinese population

BACKGROUND Previous studies have indicated that the performance of glomerular filtration rate (GFR) estimation equations vary according to the races of the target population. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has not been validated in the Chinese population including patients with chronic kidney disease (CKD) and healthy controls. METHODS A total of 977 adult persons (682 patients with CKD and 295 healthy volunteers) from nine renal institutes of university hospitals located in nine geographic regions of China were enrolled in the study. A diagnostic test study comparing the CKD-EPI two-level and four-level race equation, the Modification of Diet in Renal Disease (MDRD) Study equation and the modified MDRD equation for Chinese (the Chinese equation). The (99m)Tc- diethylenetriamine pentaacetic acid dual plasma clearance was used as a reference method for measuring GFR. RESULTS The mean age of participants was 48.3 ± 16.0 years and 479 (49.0%) were male. The CKD-EPI two-level race equation and the Chinese equation performed better than the MDRD Study equation and CKD-EPI four-level race equation, with less bias (median difference between estimated GFR and reference GFR, 0.2 and 0.3 versus -2.4 and 3.0 mL/min/1.73 m(2)), improved precision (interquartile range of the difference, 20.5 and 20.8 versus 23.4 and 20.5 mL/min/1.73 m(2)) and greater accuracy (percentage of estimated GFR within 30% of reference GFR, 73.4 and 73.0% versus 69.8 and 70.1%). CONCLUSIONS The CKD-EPI two-level race equation and the Chinese equation performed similarly in the Chinese population, and both performed better than the MDRD Study equation and the CKD-EPI four-level race equation.

Identification of Novel Long Noncoding RNAs Associated with TGF-β/Smad3-Mediated Renal Inflammation and Fibrosis by RNA Sequencing

We have previously shown that transforming growth factor-β/Smad3-dependent miRNAs play a critical role in renal inflammation and fibrosis. However, off-target effects of miRNAs limit their therapeutic application. Recently, emerging roles of long noncoding RNAs (lncRNAs) in diseases have been recognized. In this study, we used high-throughput RNA sequencing to identify the Smad3-dependent lncRNAs related to renal inflammation and fibrosis in Smad3 knockout mouse models of unilateral ureteral obstructive nephropathy and immunologically induced anti-glomerular basement membrane glomerulonephritis. Compared with wild-type mice, 151 lncRNAs in the unilateral ureteral obstructive nephropathy kidney and 413 lncRNAs in kidneys with anti-glomerular basement membrane glomerulonephritis were significantly altered in Smad3 knockout mice. Among them, 21 common lncRNAs were up-regulated in wild-type, but down-regulated in Smad3 knockout, kidneys in both disease models in which progressive renal inflammation and fibrosis were abolished when the Smad3 gene was deleted or suppressed. Real-time PCR confirmed these findings and revealed the functional link between Smad3-dependent lncRNAs np_5318/np_17856 and progressive kidney injury. Results demonstrate that the identification and characterization of functional lncRNAs associated with kidney disease may represent a promising research direction into renal disorder and may lead to the development of new lncRNA therapies for kidney diseases.