Shu-Feng Zhou

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.

Identification of apolipoprotein E Guangzhou (arginine 150 proline), a new variant associated with lipoprotein glomerulopathy

Background/Aims: Lipoprotein glomerulopathy (LPG) is a rare disease characterized by thrombus-like substances in markedly dilated glomerular capillaries and elevated plasma levels of apolipoprotein E (apoE). Previous studies have shown that genetic disorders of apoE may contribute to the pathogenesis of LPG, but LPG may not be caused by apoE gene mutations in Chinese patients. This study investigated the association of a new variant of apoE with LPG in a Chinese family. Methods: The apoE gene in a family with 4 LPG patients was sequenced. The polymerase chain reaction product of coding region of apoE exon 4 was cloned into pMD 18-T vector and then sequenced. Results: A novel point mutation in exon 4 of the apoE gene was identified in all 4 LPG patients and 1 asymptomatic family member. Sequence analysis confirmed a nucleotide G to C point mutation in exon 4 (base 308) of the apoE gene in all patients and the asymptomatic family member. This missense mutation denotes amino acid substitution of the proline residue for arginine residue at position 150 of apoE. Those patients were all heterozygotes with apoE Guangzhou. One of 2 grandsons was a heterozygous carrier of apoE Guangzhou, although he did not have proteinuria. Conclusion: The results of this study suggest that apoE (arginine 150 proline) is a novel apoE variant that etiologically related to LPG. This variant (apoE Guangzhou) may cause a marked molecular conformational change of the apoE and thus impair its binding ability to lipids.

Urinary proteins from patients with nephrotic syndrome alters the signalling proteins regulating epithelial-mesenchymal transition.

Aim:  Proteinuria plays an important role in the progression of tubulointerstitial fibrosis, but the mechanism for the differential renal damage induced by proteinuria is unknown. This study examined the effects of urinary proteins from patients with idiopathic minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) on several epithelial–mesenchymal transition (EMT)‐related marker proteins in cultured proximal tubular HK‐2 cells.

Human leukocyte antigen DRB1 alleles predict risk and disease progression of immunoglobulin A nephropathy in Han Chinese.

The role of human leukocyte antigen (HLA) class II polymorphisms in the pathogenesis and progression of primary immunoglobulin A nephropathy (pIgAN) is unclear. This study aimed to explore the relationship of HLA-DRB1 alleles with the susceptibility and disease progression of pIgAN in Han Chinese. A PCR-based genotyping technique was used to detect HLA-DRB1 alleles in 139 patients with pIgAN and 143 healthy subjects. A total of 37 HLA-DRB1 alleles were detected, of which 30 were found in pIgAN patients and 29 in healthy subjects. In pIgAN patients, the frequencies of HLA-DRB1*140501 (belonging to DR*14) were significantly increased, while the frequencies of HLA-DRB1*070101 (belonging to DR*7) were significantly reduced compared with the healthy individuals. Further stratification analysis revealed that the frequencies of HLA-DRB1*030101 in pIgAN patients with normal renal function were significantly higher than those in patients with renal dysfunction. These findings suggest that HLA-DRB1 polymorphisms are related to the occurrence and disease progression of pIgAN patients in Han Chinese, with HLA-DRB1*140501 being a susceptible allele and HLA-DRB1*070101 a resistant allele. HLA-DRB1*030101 may serve as a predictor of disease progression and renal damage of pIgAN in Han Chinese. Further studies are warranted to explore the immunological mechanisms for the genotype-disease phenotype relationship.

Role of NAD(P)H oxidase in transforming growth factor-β1-induced monocyte chemoattractant protein-1 and interleukin-6 expression in rat renal tubular epithelial cells

Aim:  This study investigated the role of NAD(P)H oxidase in transforming growth factor‐β1 (TGF‐β1)‐induced reactive oxygen species (ROS) generation, monocyte chemoattractant protein‐1 (MCP‐1), and interleukin‐6 (IL‐6) expression in rat renal tubular epithelial NRK‐52E cells.

Upregulation of Rat Renal Cortical Organic Anion Transporter (OAT1 and OAT3) Expression in Response to Ischemia/Reperfusion Injury

Background/Aims: Renal organic anion transporters (OAT1 and OAT3) localized in the basolateral membrane mediate the uptake of organic anions from the blood into proximal tubules. This study aimed to examine the effects of renal ischemia/reperfusion injury (IRI) on the expression of cortical renal OAT1 and OAT3 and the functional impact. Methods: Male rats underwent a right nephrectomy and clamping of the left renal pedicle for 50 min or sham operation, followed by reperfusion for 1, 2, 4 and 6 days. The expression of OAT1 and OAT3 was detected by RT-PCR, immunohistochemistry and Western blot analysis. Na+-K+-ATPase activity was also estimated. Results: The renal clearance of para-aminohippurate was significantly decreased on day 1 in IRI rats compared with sham-operated rats and returned to normal when the tubular injury recovered. There were significant increases in the mRNA and protein levels of OAT1 and OAT3 in renal cortex homogenates and basolateral membranes on day 1 after IRI, while on days 2 and 4 after IRI, the renal expression of OAT1 and OAT3 decreased gradually but was still significantly higher than that of the sham-operated rats. The Na+-K+-ATPase activity in renal cortex homogenates decreased significantly on day 1 after IRI but gradually increased on days 2, 4 and 6. Conclusions: Renal para-aminohippurate clearance was depressed in response to IRI; however, the expressions of renal cortex OAT1 and OAT3 were significantly elevated in the early stage of IRI which may have substantial impact on renal excretion of some drugs and toxic compounds.

NADPH oxidase-dependent formation of reactive oxygen species contributes to angiotensin II-induced epithelial-mesenchymal transition in rat peritoneal mesothelial cells

The objective of the present study was to investigate the role of NADPH oxidase-dependent formation of reactive oxygen species (ROS) in the angiotensin II (Ang II)-induced epithelial-mesenchymal transition (EMT) and in the accumulation of extracellular matrix (ECM) in rat peritoneal mesothelial cells (RPMCs). Primary cultured RPMCs were incubated with serum-free media for 24 h in order to arrest and synchronize cell growth. The cells were treated with Ang II (10⁻⁷ M) up to 48 h. Cells were pretreated with an Ang II type I receptor antagonist (losartan, 10⁻⁵ M), or an inhibitor of NADPH, oxidase diphenyleneiodonium (DPI) (10⁻⁵ M), for 1 h before addition of Ang II. The dichlorofluorescein (DCF)-sensitive cellular ROS were measured by fluorometric assay and confocal microscopy. RT-PCR was employed to detect the mRNA expression for the NADPH oxidase subunit p47phox, plasminogen activator inhibitor-1 (PAI-1), α-smooth muscle actin (α-SMA) and E-cadherin. PAI-1, α-SMA and p47phox protein expression were examined by Western blot analysis. Ang II significantly induced the production of intracellular ROS. DPI and losartan inhibited Ang II-induced ROS generation by 86.8% and 77.4% (p<0.05), respectively. Ang II significantly stimulated NADPH oxidase subunit p47phox mRNA and protein expression in RPMCs. Both losartan and DPI inhibited Ang II-induced up-regulation of p47phox mRNA by 37.3% and 67.8% (p<0.05), respectively. Ang II also stimulated α-SMA mRNA and protein expression and down-regulated E-cadherin mRNA expression in RPMCs. This effect was suppressed by both losartan and DPI. Ang II significantly up-regulated PAI-1 mRNA and protein expression and these were significantly suppressed by both losartan and DPI. In conclusion, NADPH oxidase-dependent formation of ROS mediates Ang II dependent EMT and accumulation of ECM in rat peritoneal mesothelial cells. NADPH oxidase may represent a potential therapeutic target in the management of peritoneal fibrosis.

Suppression of tumor necrosis factor receptor associated factor (TRAF)-2 attenuates the proinflammatory and proliferative effect of aggregated IgG on rat renal mesangial cells

Immune-complex (IC) mediated glomerulonephritis (GN) is a common cause of chronic kidney disease associated with increased levels of tumor necrosis factor (TNF)-alpha in renal cells. TNF-alpha signaling pathways involve complicated interactions between multiple proteins including TNF-receptor-associated factor (TRAF)-2. We have previously found markedly up-regulated expression of TRAF-2 in renal tissues from IC mediated lupus nephritis patients. Here we investigated the effect of TRAF-2 on inflammatory response in rat mesangial cells (MCs). The results showed that treatment with soluble aggregated IgG (AIgG) resulted in a time- and dose-dependent increase in the expression of interleukin (IL)-1beta and IL-6. Significant cell proliferation was also observed after the treatment with soluble AIgG. Knockdown TRAF-2 by siRNA significantly suppressed soluble AIgG induced up-regulation of TRAF-2, IL-1beta, and IL-6. Meanwhile the cell proliferation was inhibited and apoptotic cells were increased. It was concluded that TRAF-2 could induce the proinflammatory and proliferative effects of soluble AIgG on rat MCs. Thus, TRAF-2 may represent a future target for therapy of IC mediated GN.

Differential chemokine expression in tubular cells in response to urinary proteins from patients with nephrotic syndrome.

BACKGROUND AND AIM Comparison of urine proteins in idiopathic minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) patients has been previously conducted, but the relationship between the severity of tubular injury and the composition of urine proteins in various kidney diseases is unknown. This study aimed to investigate the chemokine expression in human tubular cells in response to urine proteins from patients with nephrotic syndrome. METHODS Urine proteins collected from patients with MCD or FSGS were extracted by ultrafiltration and coincubated with HK-2 cells. The expression of the RANTES and MIF genes and the activation of p38 and extracellular regulated kinase were determined. RESULTS The urine proteins from both MCD and FSGS patients contained a primary band of proteins with Mr of approximately 62 kDa. The major cytokines present in urine proteins from MCD and FSGS patients were IL-6 and IL-8, while IL-1beta, IL-10, IL-12p70 and TNF-alpha were only detectable. We observed time- and dose-dependent increases in RANTES and MIF expression with urine protein treatment in HK-2 cells. The urine proteins from FSGS patients induced a higher expression of these two chemokines in HK-2 cells compared to the urine proteins from MCD patients. ERK and p38 were activated by urine proteins from either MCD or FSGS patients. Pretreatment with SB203580 or PD98059 abolished the increase in RANTES and MIF expression induced by urine proteins from FSGS patients, while only SB203580 suppressed the high expression induced by urine proteins from MCD patients. CONCLUSION These findings indicate that the urine proteins from MCD and FSGS patients induce a differential expression of RANTES and MIF in tubular cells through distinct activation of MAPK-related signaling pathways.