Sex-related differences in the intratubular renin-angiotensin system in two-kidney, one-clip hypertensive rats.

The intratubular renin-angiotensin system (RAS) is thought to play an essential role in hypertensive renal disease, but information regarding sex-related differences in this system is limited. The present study investigated sex differences in the intratubular RAS in two-kidney, one-clip (2K1C) rats. A 2.5-mm clip was placed on the left renal artery of Sprague-Dawley rats, and rats were euthanized 3 or 5 wk after the operation. Systolic blood pressure increased in 2K1C rats in both sexes but was significantly higher in male rats than in female rats, and an antihypertensive effect was not observed in 2K1C ovariectomized (OVX) female rats. Compared with male 2K1C rats, intratubular angiotensin-converting enzyme (ACE) and ANG II were repressed, and intratubular ACE2, angiotensin (1-7), and Mas receptor were increased in both kidneys in female 2K1C rats 5 wk after surgery. Comparison with male and female rats and intratubular mRNA levels of ACE and ANG II type 1 receptor were augmented in OVX female rats, regardless of the clipping surgery 3 wk postoperation. ANG II type 2 receptor was upregulated in female rats with or without OVX; thus, the ANG II type 1-to-type 2 receptor ratio was higher in male rats than in female rats. In conclusion, female rats were protected from hypertensive renal and cardiac injury after renal artery clipping. An increase in the intratubular nonclassic RAS [ACE2/angiotensin (1-7)/Mas receptor] and a decrease in the ANG II type 1-to-type 2 receptor ratio could limit the adverse effects of the classic RAS during renovascular hypertension in female rats, and estrogen is suggested to play a primary role in the regulation of intratubular RAS components.

Combination therapy of low-dose cyclosporine and steroid in adults with IgA nephropathy
.

BACKGROUND: A few clinical trials in IgA nephropathy (IgAN) have shown that cyclosporine A (CyA) had therapeutic efficacy in reducing proteinuria. MATERIALS AND METHODS: This is a retrospective study, and all cases were selected based on kidney biopsy-proven IgAN. We reviewed the data of IgAN patients in the glomerulonephritis registry at Kyung Hee University Medical center and collected data on 86 patients with urinary protein/Cr ratio (PCR; g/g) > 0.5 and estimated GFR (eGFR) of > 50 mL/min/1.73m2 who were treated with combination therapy of low-dose CyA plus low-dose steroid (C+P; n = 37) and high-dose steroid single therapy (P; n = 49). RESULTS: In the C+P group, the mean duration of therapy was 14.5 ± 13.1 months, and the mean duration of follow-up 66.2 ± 36.3 months. In the C+P group, the urine PCR levels significantly declined after treatment (< 0.05). After 6 months of treatment, 12 (32%) patients were in complete remission and 7 (19%) in partial remission in the C+P group, compared with 21 (42%) and 11 (22%) in the P group, respectively. Urine PCR levels were also significantly reduced in 12 patients in the C+P group who had initial urine PCR between 0.5 and 1.0. The degree of hematuria was significantly reduced after treatment in the C+P group. These effects of C+P therapy on proteinuria and hematuria were very comparable to high-dose P therapy. After 2 years, a decline in renal function, > 25% decrease in eGFR from baseline levels, developed in 3 (8.1%) in the C+P group, compared with 4 (8.2%) in the P group. The rate of decline in renal function during follow-up was -0.14 ± 0.40 mL/min/1.73m2/month in the C+P group compared with -0.12 ± 0.22 mL/min/1.73m2/month in the P group. There were no changes of mean eGFR during the first 24 months, but the eGFR significantly decreased at last follow-up in both groups. When patients in the C+P group were divided into progressive (n = 9) and nonprogressive (n = 28) groups, a significant reduction in the amount of proteinuria after treatment was observed in the nonprogressive group, in contrast to the progressive group. In the C+P group, there were no severe adverse effects, especially no acute renal impairment, requiring discontinuation of CyA in this study. The incidence of infection was much lower in the C+P group than that in the P group. The limitation is that CyA acts to nonspecifically reduce proteinuria, so it requires long-term follow-up off CyA therapy for more than 2 years to determine. CONCLUSION: Our retrospective uncontrolled study provides only weak evidence that combination therapy of low-dose C+P could be an alternative to high-dose P therapy and be safe in adult IgAN patients with relatively normal renal function and proteinuria of > 0.5 g/g. Development of safe and effective therapy is still a major challenge requiring well-controlled prospective studies with this or other combination therapies.

Potential urine proteomics biomarkers for primary nephrotic syndrome.

BACKGROUND: Nephrotic syndrome (NS) is a nonspecific kidney disorder, commonly caused by minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and membranous nephropathy (MN). Here we analyzed urinary protein profiles, aiming to discover disease-specific biomarkers of these three common diseases in NS. METHODS: Sixteen urine samples were collected from patients with biopsy-proven NS and healthy controls. After removal of high-abundance proteins, the urinary protein profile was analyzed by LC-MS/MS to generate a discovery set. For validation, ELISA was used to analyze the selected proteins in 61 urine samples. RESULTS: The discovery set included 228 urine proteins, of which 22 proteins were differently expressed in MCD, MN, and FSGS. Among these, C9, CD14, and SERPINA1 were validated by ELISA. All three proteins were elevated in MCD, MN, and FSGS groups compared with in IgA nephropathy and healthy controls. When a regression model was applied, receiver operating characteristic analysis clearly discriminated MCD from the other causative diseases in NS. CONCLUSIONS: We developed a disease-specific protein panel that discriminated between three main causes of NS. Through this pilot study, we suggest that urine proteomics could be a non-invasive and clinically available tool to discriminate MCD from MN and FSGS.

Sequential activation of the intrarenal renin-angiotensin system in the progression of hypertensive nephropathy in Goldblatt rats.

The intrarenal renin-angiotensin system (RAS) has an important role in generating and maintaining hypertension in two-kidney, one-clip (2K1C) rats. This study evaluated how various intrarenal RAS components contributed to hypertension not only in the maintenance period (5w; 5 wk after operation) but also earlier (2w; 2 wk after operation). We inserted a 2.5-mm clip into the left renal artery of Sprague-Dawley rats and euthanized them at 2w and 5w following the operation. Systolic blood pressure increased within 1 wk after the operation, and left ventricular hypertrophy occurred in 2K1C rats. At 2w, juxtaglomerular apparatus (JGA) and collecting duct (CD) renin increased in clipped kidney (CK) of 2K1C rats. The tubular angiotensin I-converting enzyme (ACE) was not changed, but peritubular ACE2 decreased in nonclipped kidney (NCK) and CK of 2K1C rats. At 5w, ACE and CD renin were enhanced, and ACE2 was still lessened in both kidneys of 2K1C rats. However, plasma renin activity (PRA) was not different from that in sham rats. In proximal tubules of CK, the ANG II type 1 receptor (AT1R) was not suppressed, but the Mas receptor (MasR) was reduced; thus the AT1R/MasR ratio was elevated. Although hypoxic change in CK could not be excluded, the JGA renin of CK and CD renin in both kidneys was highly expressed independent of time. Peritubular ACE2 changed in the earlier period, and uninhibited AT1R in proximal tubules of CK was presented in the maintenance period. In 2K1C rats, attenuated ACE2 seems to contribute to initiating hypertension while upregulated ACE in combination with unsuppressed AT1R may have a key role in maintaining hypertension.

Hyperuricemia-induced NLRP3 activation of macrophages contributes to the progression of diabetic nephropathy.

IL-1ß-secreting nucleotide-binding oligomerization domain protein 3 (NLRP3) inflammasomes play a pivotal role in triggering innate immune responses in metabolic disease. We investigated the role of soluble uric acid in NLRP3 inflammasome activation in macrophages to demonstrate the effect of systemic hyperuricemia on progressive kidney damage in type 2 diabetes. THP-1 cells, human acute monocytic leukemia cells, were cultured to obtain macrophages, and HK-2 cells, human renal proximal tubule cells, were cultured and stimulated with uric acid. In vivo, we designed four rat groups as follows: 1) Long-Evans Tokushima Otsuka (LETO); 2) Otsuka Long-Evans Tokushima Fatty (OLETF); 3) OLETF+high-fructose diet (HFD) for 16 wk; and 4) OLETF+HFD+allopurinol (10 mg/dl administered in the drinking water). Soluble uric acid stimulated NLRP3 inflammasomes to produce IL-1ß in macrophages. Uric acid-induced MitoSOX mediates NLRP3 activation and IL-1ß secretion. IL-1ß from macrophages activates NF-κB in cocultured proximal tubular cells. In vivo, intrarenal IL-1ß expression and macrophage infiltration increased in HFD-fed OLETF rats. Lowering the serum uric acid level resulted in improving the albuminuria, tubular injury, macrophage infiltration, and renal IL-1ß (60% of HFD-fed OLETF) independently of glycemic control. Direct activation of proximal tubular cells by uric acid resulted in (C-X-C motif) ligand 12 and high mobility group box-1 release and accelerated macrophage recruitment and the M1 phenotype. Taken together, these data support direct roles of hyperuricemia in activating NLRP3 inflammasomes in macrophages, promoting chemokine signaling in the proximal tubule and contributing to the progression of diabetic nephropathy through cross talk between macrophages and proximal tubular cells.

Platelet reactivity after receiving clopidogrel compared with ticagrelor in patients with kidney failure treated with hemodialysis: a randomized crossover study.

BACKGROUND: Patients with kidney failure treated with maintenance hemodialysis (HD) are poor responders to clopidogrel. More beneficial platelet-inhibiting strategies in HD patients therefore are required. STUDY DESIGN: Single-center, prospective, randomized, crossover study. SETTING & PARTICIPANTS: 25 HD patients in Seoul, Korea. INTERVENTION: Patients were randomly assigned to receive clopidogrel (300mg loading, 75mg once daily for maintenance dose) or ticagrelor (180mg loading, 90mg twice daily for maintenance dose) for 14 days, and after a 14-day washout period, crossover treatment for another 14 days. All patients received aspirin (100mg/d). OUTCOMES & MEASUREMENTS: Platelet function was evaluated predosing and at 1, 5, and 48 hours and 14 days after the first loading dose. During the offset phase, platelet function was assessed at 1 hour and 2, 4, and 14 days after the last dose by light transmittance aggregometry and the VerifyNow P2Y12 assay, and patients were genotyped for the CYP2C19*2 allele. Maximal extent of aggregation, inhibition of platelet aggregation (IPA), P2Y12 reaction units (PRUs), and percentage of inhibition were evaluated. We performed per-protocol analysis, excluding patients who did not complete the protocol. RESULTS: 9 patients did not complete the protocol (7 patients due to adverse events; 2, nonadherence). Higher IPA occurred with ticagrelor than with clopidogrel at 1, 5, and 48 hours and 14 days after loading. By 5 hours after loading, a greater proportion of patients in the ticagrelor group than in the clopidogrel group achieved IPA>50% (75% vs 12%, respectively; P<0.05) and IPA>70% (44% vs 0%, respectively; P<0.05). Rates (slope) of onset and offset of the antiplatelet effect were faster in patients receiving ticagrelor than for those receiving clopidogrel (P<0.05). Regardless of CYP2C19*2 allele, the ticagrelor group had significantly lower PRUs at all times than the clopidogrel group. LIMITATIONS: Single-center study with a small number of patients, not a double-blind study, and not intention-to-treat analysis. CONCLUSIONS: Ticagrelor may result in more rapid and greater platelet inhibition than clopidogrel in patients with kidney failure receiving HD.

Anti-Phospholipase A2 Receptor Antibody as Prognostic Indicator in Idiopathic Membranous Nephropathy.

BACKGROUND: Anti-phospholipase A2 receptor antibody (PLA2R-Ab) is useful in diagnosing idiopathic membranous nephropathy (IMN). We investigated the clinical relevance of PLA2R-Ab enzyme-linked immunosorbent assay (ELISA) in patients with IMN. METHODS: We measured PLA2R-Ab with an ELISA kit from the serum of 160 patients with IMN (n = 93), secondary MN (n = 14) and other glomerulonephritis (n = 41) as well as healthy controls (n = 12) at the time of renal biopsy and investigated the correlation of titers of PLA2R-Ab with clinical parameters. RESULTS: PLA2R-Ab was positive in 41 of 93 patients (44.1%) with IMN. No samples from the patients with secondary MN and other glomerulonephritis or healthy controls were positive with the ELISA test. The PLA2R-Ab-positive patients showed severe disease activity and a low remission rate. The PLA2R-Ab titer positively correlated with proteinuria and was negatively associated with renal function and serum albumin. The patients with a high titer of PLA2R-Ab had significantly decreased remission rates. The cumulative probabilities of remission was significantly lower in patients with PLA2R-Ab (p = 0.01) and even so in patients with a high titer of PLA2R-Ab (p = 0.04). When we compared the ELISA titers with Western blot (WB) data of 43 patients who had been enrolled in our previous study, 18 and 30 patients were positive on ELISA (41.9%) and WB (69.8%), respectively. WB and ELISA had a concordance rate of 72.1% and were positively correlated (r = 0.590, p < 0.001). CONCLUSION: The presence, as well as a high titer, of PLA2R-Ab on ELISA was associated with poor prognosis of IMN. Assessment of PLA2R-Ab with ELISA is an easy and reliable tool for the diagnosis and guidance of therapeutic plans.

Febuxostat ameliorates diabetic renal injury in a streptozotocin-induced diabetic rat model.

BACKGROUND: Oxidative stress and inflammation are known to play central roles in the development of diabetic nephropathy (DN). Febuxostat is a novel non-purine xanthine oxidase (XO)-specific inhibitor developed to treat hyperuricemia. In this study, we investigated whether febuxostat could ameliorate DN via renoprotective mechanisms such as alleviation of oxidative stress and anti-inflammatory actions. METHODS: Male Sprague-Dawley rats were divided into three groups: a normal group, a diabetes group (DM group), and a febuxostat-treated diabetes group (DM+Fx group). We administered 5 mg/kg of febuxostat to experimental rats for 7 weeks and evaluated clinical and biochemical parameters and XO and xanthine dehydrogenase (XDH) activity in hepatic tissue. The degree of oxidative stress and extent of inflammation were evaluated from urine samples and renal tissue collected from each group. RESULTS: Diabetic rats (DM and DM+Fx groups) had higher blood glucose and kidney weight relative to body weight than normal rats. Albuminuria was significantly reduced in febuxostat-treated diabetic rats compared with untreated diabetic rats. Quantitative analysis showed that hepatic XO and XDH activities were higher in the DM groups, but decreased after treatment with febuxostat. Urinary 8-OHdG concentrations and renal cortical nitrotyrosine also indicated reduced oxidative stress in the DM+Fx group relative to the DM group. The number of ED-1-stained cells in the glomerulus and tubule of diabetic renal tissue decreased in febuxostat-treated diabetic rats relative to that of non-treated diabetic rats. Diabetic rats also expressed higher transcript levels of inflammatory genes (E-selectin and VCAM-1), an inflammation-induced enzyme (COX-2), and inflammatory mediators (ED-1 and NF-κB) than control rats; expression of these genes was significantly reduced by treatment with febuxostat. CONCLUSIONS: Febuxostat prevents diabetic renal injury such as albuminuria. This renoprotective effect appears to be due to attenuation of the inflammatory and oxidative effects of diabetes-induced renal damage through inhibition of XO and XDH activities.

Association studies of cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene polymorphisms with acute rejection in kidney transplantation recipients.

Recent studies have shown that single-nucleotide polymorphisms (SNPs) are associated with allograft rejection in kidney transplantation recipients. We evaluated the possible association between SNPs of the cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene, and acute rejection (AR) among renal transplant patients in a Korean population. We conducted a case-control association study in 63 AR and 284 non-AR kidney transplant recipients. The SNPs of CYP2E1 were genotyped by direct sequencing. Recipient sex (p = 0.023) and the use of tacrolimus (p = 0.017) were significantly different between the two groups. The use of mycophenolate mofetil (MMF) and antibody induction therapy was significantly lower in the AR group. Multiple logistic regression models (codominant, dominant, recessive, and log-additive models) adjusted by sex and type of immunosuppressive regimens were applied to determine the odds ratios (ORs), 95% confidence intervals (CIs), and p-values. The rs2515641 of CYP2E1 showed significant differences between the AR patient group and non-AR group (p = 0.003, OR = 2.55, 95% CI = 1.37-4.75 in the codominant 1 model; p = 0.002, OR = 2.61, 95% CI = 1.43-4.77 in the dominant model; p = 0.0035, OR = 2.13, 95% CI = 1.29-3.50 in the log-additive model). The allele of the rs2515641 SNP also showed a significant association (p = 0.004, OR = 1.99, 95% CI = 1.24-3.21). This study suggests that the CYP2E1 polymorphism may be related to the development of AR in Korean kidney transplantation recipients.

Impact of reduced vancomycin MIC on clinical outcomes of methicillin-resistant Staphylococcus aureus bacteremia.

Vancomycin has been a key antibiotic agent for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. However, little is known about the relationship between vancomycin MIC values at the higher end of the susceptibility range and clinical outcomes. The aim of this study was to determine the impact of MRSA bacteremia on clinical outcomes in patients with a vancomycin MIC near the upper limit of the susceptible range. Patients with MRSA bacteremia were divided into a high-vancomycin-MIC group (2 µg/ml) and a low-vancomycin-MIC group (≤1.0 µg/ml). We examined the relationship between MIC, genotype, primary source of bacteremia, and mortality. Ninety-four patients with MRSA bacteremia, including 31 with a high vancomycin MIC and 63 with a low MIC were analyzed. There was no significant difference between the presence of agr dysfunction and SCCmec type between the two groups. A higher vancomycin MIC was not found to be associated with mortality. In contrast, high-risk bloodstream infection sources (hazard ratio [HR], 4.63; 95% confidence interval [CI] = 1.24 to 17.33) and bacterial eradication after treatment (HR, 0.06; 95% CI = 0.02 to 0.17), irrespective of vancomycin MIC, were predictors of all-cause 30-day mortality. Our study suggests that a high-risk source of bacteremia is likely to be associated with unfavorable clinical outcomes, but a high vancomycin MIC in a susceptible range, as well as genotype characteristics, are not associated with mortality.

Association between a TGFBR2 gene polymorphism (rs2228048, Asn389Asn) and acute rejection in Korean kidney transplantation recipients.

Transforming growth factor-ß (TGF-ß) signaling transduction initiates TGF-ß activation, resulting in activation of TGF-ß receptor II (TGFBR2). Any quantitative and qualitative changes in TGFBR2 are expected to affect the TGF-ß signaling pathway, which occupies a central position with respect to the regulation of cell growth, differentiation, apoptosis, immune reaction, angiogenesis and extracellular matrix formation. Recent studies have shown that TGF-ß1 gene polymorphisms may confer susceptibility to early acute and chronic allograft rejection in kidney transplantation recipients. In this study, we assessed whether polymorphisms of the TGFBR2 gene were associated with susceptibility to kidney transplantation rejection. A total of 347 renal allograft recipients transplanted at three centers in Korea were analyzed. Three SNPs (rs764522, rs3087465, rs2228048) of the TGFBR2 gene were genotyped from genomic DNA with direct sequencing. Multiple logistic regression models (codominant, dominant, recessive, and log-additive) were performed to evaluate odds ratios (ORs), 95% confidence intervals (CIs), and p-values. A total of 63 patients (18%) developed acute rejection (AR). There were no significant differences in age, sex, number of HLA mismatches, cause of renal failure, or immunosuppressant regimen between the AR and non-AR group. The synonymous SNP rs2228048 was significantly associated with AR (p = 0.020 in recessive model, and p = 0.036 in log-additive model. The allele frequencies of rs2228048 were different between the AR and non-AR group (p = 0.026). These results suggest that the synonymous TGFBR2 gene SNP rs2228048 may be associated with the development of AR in Korean kidney transplantation recipients. Authors Yeong-Hoon Kim and Tae Hee Kim contributed equally to this work and are considered co-first authors.

Angiotensinogen polymorphisms and post-transplantation diabetes mellitus in Korean renal transplant subjects.

BACKGROUND: Post-transplant diabetes mellitus (PTDM) is a common and serious metabolic complication. Genetic polymorphisms of angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) genes have been reported to be related to diabetes mellitus and insulin sensitivity; however, the role of these genes in the development of PTDM is not known. For this purpose, we investigated the association of ACE and AGT genetic polymorphisms with PTDM. METHODS: A total of 302 subjects without previously diagnosed diabetes who had received kidney transplants were included. One ACE single nucleotide polymorphism (SNP) (rs4291) and two AGT SNPs (rs 699 and rs 4762) were genotyped from genomic DNA with direct sequencing. RESULTS: PTDM developed in 49 (16.2%) of 302 subjects. Subjects in the PTDM were older than those in the non-PTDM. There was a significant difference between the two groups in tacrolimus use (p=0.03). Of the three SNPs, the rs4762 of the AGT gene was significantly associated with the development of PTDM in the dominant models (p = 0.03) after adjusting for age and tacrolimus usage. CONCLUSIONS: AGT gene rs4762 polymorphisms may serve as genetic markers for the development of PTDM. The exact molecular mechanisms still need to be clarified.

Association of C1q deposition with renal outcomes in IgA nephropathy.

BACKGROUND/AIMS: IgA nephropathy (IgAN) is characterized by a highly variable clinical course. It has been reported that histopathologic lesions are risk factors for the progression of IgAN. The aim of this study was to investigate the relationships between co-deposition of C1q, clinicopathological features, and renal outcomes in patients with IgAN. METHODS: This retrospective cohort study included 221 patients with primary IgAN who underwent renal biopsy at the Kyung Hee University Medical Center from January 1996 to December 2008. Patients were divided in two groups: C1qpositive and C1q-negative. Using propensity scores to minimize confounding factors, we selected 36 matched C1q-negative patients from among the 203 unmatched C1q-negative patients and compared them with the 18 C1q-positive patients. We evaluated baseline characteristics and the severity of histologic lesions. We expressed the average rate of monthly renal function decline as the slope of eGFR (ΔGFR/M). RESULTS: 18 patients with IgAN showed mesangial deposition of C1q (8.1%). The C1q-positive patients had higher mean systolic blood pressure values and more impaired renal function than the unmatched C1q-negative patients. However, this association was not seen when the C1qpositive patients were compared with the matched C1q-negative patients. The slope of eGFR (ΔeGFR/M) declined steeply in the C1q-positive group. The incidence of severe cases of tubulointerstitial inflammation (TII) and fibrosis (TIF) was also greater in the C1q-positive group than the unmatched C1qnegative group, while only the incidence of severe TIF was significantly greater in the C1q-positive group than the matched C1qnegative group. Biopsies from C1q-positive patients showed more intense IgA staining as well as positive rates of IgG and IgM staining than those of unmatched C1q-negative patients. However, compared with the matched C1q-negative group, only the IgG positive rate was significantly higher in the C1q-positive patients. Multiple regression analysis of C1q-positive and matched C1q-negative patients revealed that C1q deposition was a critical determinant of a poorer renal prognosis. CONCLUSIONS: Mesangial C1q deposition in the glomerulus is associated with a poor renal outcome and severe pathologic features in patients with IgAN. The deposition of C1q in IgAN could therefore serve as an indicator of a poor renal prognosis.

Aberrant recruitment and activation of T cells in diabetic nephropathy.

BACKGROUND/AIMS: Recent evidence has shown that an inflammatory process is involved in the development and progression of diabetic nephropathy. This study examined the impact of activated intrarenal lymphocytes in this inflammatory process. METHODS: We studied T cell recruitment in mice with streptozotocin (STZ)-induced diabetes by flow cytometry and immunohistochemistry. The kidney biopsy specimens from patients with type 2 diabetes mellitus and diabetic nephropathy were evaluated by immunohistochemistry. RESULTS: In flow cytometry, intrarenal CD3+ T cells were significantly increased in proteinuric mice at 20 weeks after STZ injection. However, the population of T cells and B cells in diabetic spleen was not different from that of control mice. Immunohistochemistry also showed a marked infiltration of interstitial CD4+, CD8+ T cells in diabetic kidney. Interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) mRNA expression was significantly increased in diabetic mouse kidney compared with controls. Interestingly, flow cytometry analysis of kidney-derived mononuclear cells from diabetic mice showed significantly increased production of IFN-γ and TNF-α by CD3+ T cells. Type 2 diabetic patients also showed a marked increase in CD4+, CD8+ and CD20+ cells in interstitium, and the number of CD4+ and CD20+ cells correlated with the amount of proteinuria. CONCLUSION: Our results clearly showed that aberrant intrarenal infiltration and the activation of T cells in interstitium are the underlying immunopathological mechanisms of diabetic kidney injury.

Gene polymorphisms of interleukin-17 and interleukin-17 receptor are associated with end-stage kidney disease.

BACKGROUND: Inflammation could be a causal factor in progression of chronic kidney disease. To date, there is convincing experimental and clinical evidence to support the notion that interleukin (IL)-17-producing T cells contribute to kidney injury in renal diseases. However, the genetic relationship between end-stage renal disease (ESRD) and the T-helper 17 pathway has never been studied. In this study, we hypothesized that polymorphisms of IL-17 or their receptors may be associated with ESRD. METHODS: A total of 290 nondiabetic ESRD patients and 289 normal controls were included. We analyzed 13 single nucleotide polymorphisms located within the four genes of IL17A, IL17E, IL17RA and IL17RB. RESULTS: The ESRD patients had a significantly higher allele frequency compared to control subjects for the IL17E rs10137082*C and IL17RA rs4819554*A alleles. Genotyping analysis demonstrated that 2 SNPs among 13 were significantly associated with ESRD after adjusting for age and sex, which were shown by IL17E rs10137082 (odds ratio (OR) 1.48 in codominant 1, OR 1.54 in dominant, OR 1.47 in log-additive) and IL17RA rs4819554 (OR 1.46 in codominant 1, OR 1.79 in codominant 2, OR 1.54 in dominant, OR 1.39 in log-additive). CONCLUSIONS: Two polymorphisms within the IL17E and IL17RA genes are associated with ESRD independent of age and sex. This is the first finding to suggest that genetic variations of IL17 genes affect the risk of development of ESRD.

Reducing serum uric acid attenuates TGF-ß1-induced profibrogenic progression in type 2 diabetic nephropathy.

BACKGROUND: The pivotal role of transforming growth factor-ß1 (TGF-ß1)-induced tubulointerstitial fibrosis in the progression of chronic kidney disease is an active topic of research. Recent evidence indicates that hyperuricemia is associated with increased TGF-ß1 and progressive tubulointerstitial injury. We examined the hypothesis that lowering serum uric acid attenuates TGF-ß1-induced profibrogenic tubular change in type 2 diabetic nephropathy. METHODS: KK-A(y)/Ta mice, an animal model of type 2 diabetes, were provided access to either regular drinking water or drinking water containing 10 mg/dl of allopurinol. Normal rat kidney epithelial cells were cultured and stimulated with 5 mM uric acid with or without allopurinol. RESULTS: Type 2 diabetic mice that received allopurinol exhibited smaller increases in urinary albumin:creatinine ratio than diabetic control mice, as well as attenuated TGF-ß1 and Smad pathway-induced profibrogenic tubular changes in diabetic kidneys. Allopurinol attenuated TGF-ß1-induced Smad pathway activation in tubular cells. These findings were related to increases in E-cadherin, and decreases in vimentin and α-smooth muscle actin. Uric acid-induced upregulation of TGF-ß1 depends on mitogen-activated protein kinase signaling. CONCLUSIONS: This is the first study to demonstrate that reducing serum uric acid has preventive effects against to profibrogenic progression in type 2 diabetic kidney disease. These findings suggest that lowering serum uric acid may be an effective therapeutic intervention to prevent the progression of type 2 diabetic kidney disease.

Real-time monitoring of the effects of telmisartan on angiotensin II-induced mechanical changes in live mesangial cells using atomic force microscopy.

BACKGROUND/AIMS: Recent studies have shown that angiotensin II (Ang II) type 1 receptor blockers (ARB) may provide renal protection independent of their blood pressure-lowering effect. However, evidence for this comes from indirect methods, such as genetic or protein expression studies. In this study, we hypothesized that telmisartan, a specific ARB, applied to Ang II-stimulated mesangial cell (MC) would exert a renoprotective effect via modulation of MCs' mechanical properties. METHODS: We investigated the effect of telmisartan on Ang II-induced changes in MCs utilizing real-time atomic force microscopy (AFM) imaging and force-distance curve measurements. RESULTS: Real-time AFM images of live MCs demonstrated that cells contracted towards the center after Ang II exposure, and telmisartan treatment abolished this change. Cellular spring constants showed that telmisartan prevented Ang II-induced MC stiffening (Ang II: 0.109 ± 0.019 N/m, Ang II + telmisartan: 0.051 ± 0.016 N/m, p < 0.005). Telmisartan-treated MCs had a significantly lower adhesion force than those of the control group (control: 0.49 ± 0.22 nN, telmisartan: 0.22 ± 0.06 nN, Ang II: 0.40 ± 0.25 nN, Ang II + telmisartan: 0.27 ± 0.14 nN, p < 0.005). These results demonstrate that the dynamic contraction and mechanical properties of Ang II-stimulated MCs are restored by telmisartan. CONCLUSIONS: We report for the first time the use of AFM force-distance curves on live MCs to directly monitor changes in surface adhesion and stiffness of cells after treatment with telmisartan in real time.

Relationship between glomerulomegaly and clinicopathologic findings in IgA nephropathy.

BACKGROUND: Large glomeruli are a common finding in the early stages of progressive renal disease. We studied the relationship between glomerular surface area (GSA) and clinicopathologic features of IgA nephropathy (IgAN), including renal outcome, to better understand the role of GSA in IgAN. METHODS: We analyzed renal biopsy specimens and clinical information from 34 patients with IgAN. Mean and maximal GSA were determined using a computed imaging analyzer. RESULTS: Mean GSA was 16,811 ± 4,671 µ2 in IgAN patients (n = 34). When we analyzed various clinical parameters of IgAN patients, there were significant correlations between mean or maximal GSA and age, body mass index (BMI), systolic and diastolic blood pressure, estimated glomerular filtration rate (eGFR), and pathologic findings including H.S. Lee' grades, interstitial fibrosis, and tubular atrophy. GSA did not show any relationship with the degree of hematuria and proteinuria. By multivariate regression analysis of age, BMI, blood pressure, H.S. Lee' grades, and eGFR as independent variables, mean GSA was associated with H.S Lee' grades and initial eGFR. The results for maximal GSA were the same as those for mean GSA. When we divided IgAN patients according to their mean levels of GSA, the group with larger GSA had higher blood pressure and H.S. Lee' grades and lower initial and final eGFR. More patients in the larger GSA group showed the decline in eGFR of more than 15 ml/min/1.73 m2 during the followup period compared with the smaller group. CONCLUSION: These results suggest that glomerular size, estimated by measuring GSA, is related to pathologic findings and renal function in IgAN. However, further investigation is required to determine if GSA can be used as a prognostic indicator of IgAN.