Kidney Tissue Of Patients Research Articles

Correlation Between Serological Makers and Immunofluorescence Deposits i n Kidney Tissue of Patients with Lupus Nephritis

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease. Few biomarkers for SLE have been validated and widely accepted for the laboratory follow-up of inflammatory activity. In SLE patients, with lupus nephritis (LN), complement activation leads to fluctuation of serum C3 and C4 that are frequently used as clinicalm biomarker of disease activity in SLE. Patients and Methods: In this study the number of patients were 37, seven patients were excluded for incomplete data collection, 28 were females ,2 were males. The duration of the study is two years from 2015 to 2017. Patients were considered to have SLE and LN according to American College of Rheumatology (ACR) criteria, and International Society of Nephrology/ Renal Pathology Society (ISN/RPS). All patients were evaluated withm clinical presentation, laboratory investigations. Our patients underwent kidney biopsy according to standard procedure by Kerstin Amann, and their tissue specimens were studied in the laboratory with light microscope (LM) and immunofluorescence microscope reagents. The relationship between the serological markers and immunofluorescence deposits in kidney biopsy of all patients were studied using the statistical analysis of Pearson correlation and single table student's T test. A P value 0.05 was considered statistically significant. Results: The granular pattern of IF deposits was present in all LN patients, and in more than two third of patients these IF deposits presented in glomerular, tubular, and mesangium sites. While less than one third of patients had IF deposits in the mesangium only. There was no statistically significant correlation between serum ANA, anti-dsDNA, and IF deposits of different types. There was significant correlation between serum C3 and C4 hypocomplementemia and IgG immune deposits in kidney biopsy, and there was significant relationship between serum C3 hypocomplementemia and full house immunofluorescence (FHIF) deposits inm kidney biopsy.Conclusions:Immunofluorescence deposits is mainly granular pattern in LN patients. There was no significant association between serum ANA, anti-dsDNA, and immune deposits in kidney tissue. Immunofluorescence deposits of IgG type correlates significantly with serum C3 and C4 hypocomplemetemia, and these immune deposits in association with low complement levels correlates with LN flare. There was significant correlation between C3 hypocomplementemia and FHIF.

Down-regulation of the long non-coding RNA XIST ameliorates podocyte apoptosis in membranous nephropathy via the miR-217-TLR4 pathway.

What is the central question of this study? What is the role of the long non-coding RNA X-inactive specific transcript (XIST), which is up-regulated in injured podocytes and membranous nephropathy, in the pathogenesis of membranous nephropathy? What is the main finding and its importance? XIST was up-regulated in kidney tissue with membranous nephropathy and in injured podocytes. Down-regulation of XIST inhibited podocyte apoptosis. XIST negatively regulated miR-217, and miR-217 modulated Toll-like receptor 4. Inhibition of XIST suppressed podocyte apoptosis induced by angiotensin II via miR-217. Membranous nephropathy is often characterized by glomerular podocyte injury. Up-regulation of the long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) has been verified in membranous nephropathy and in injured podocytes. Here the role of XIST in podocyte injury and membranous nephropathy was explored. Quantitative real-time PCR and western blot were performed to detect the expression of XIST and miR-217, and Toll-like receptor 4 (TLR4) protein, respectively. Podocyte apoptosis was evaluated with flow cytometry. Interaction between XIST and miR-217 was analysed by RNA immunoprecipitation and RNA pull-down assay. A dual luciferase reporter assay was used to examine the interplay between miR-217 and TLR4. Up-regulation of the lncRNA XIST and angiotensin II (Ang II) and kidney and podocyte injury were indicated in kidney tissue of patients with membranous nephropathy. Increase of XIST and apoptosis were induced by Ang II in podocytes. Down-regulation of XIST reversed podocyte apoptosis induced by Ang II. MiR-217 was negatively regulated by XIST. MiR-217 controlled TLR4 by targeting its 3'-untranslated region. XIST modulated TLR4 through miR-217 and inhibition of XIST reduced podocyte apoptosis induced by Ang II via regulating miR-217. Down-regulation of XIST ameliorates podocyte apoptosis via the miR-217-TLR4 pathway, which may improve membranous nephropathy.

Renal matrix Gla protein expression increases progressively with CKD and predicts renal outcome

BackgroundMatrix Gla Protein (MGP) is a potent inhibitor of ectopic calcification and modulates bone morphogenesis. Little is known about MGP expression or function in kidney. MethodsWe investigated renal MGP expression in Sprague-Dawley rats after 5/6 nephrectomy (5/6 Nx) and in human kidney biopsies in the Nephrotic Syndrome Study Network (NEPTUNE) cohort. We analyzed associations between glomerular (n = 182) and tubulointerstitial (TI) (n = 219) MGP mRNA levels and the disease activity/histologic features in NEPTUNE patients. Additionally, uncarboxylated and carboxylated MGP (ucMGP and cMGP, respectively) were localized by immunohistochemistry and quantitated in kidney tissues of patients at different stages of CKD (n = 18). ResultsRenal MGP expression was increased in rats after 5/6 Nx. In NEPTUNE data, baseline estimated glomerular filtration rate (eGFR) negatively correlated with glomerular and TI MGP expression (p <0.001). TI MGP expression strongly correlated with interstitial fibrosis, tubular atrophy, acute tubular injury, and interstitial inflammation, independent of eGFR. Kaplan-Meier analysis and multivariable Cox regression showed that higher levels of TI MGP expression were associated with an increased risk for the composite of 40% decline in eGFR and end-stage renal disease (ESRD) (HR, 3.31; 95% CI, 1.31 to 6.32; p =0.02). Glomerular and tubulointerstitial cells demonstrated nuclear and cytoplasmic cMGP and ucMGP staining, and eGFR inversely correlated with quantified glomerular cMGP staining (p <0.05). ConclusionsOur data demonstrate that renal MGP expression is increased in human and experimental CKD, and is associated with renal outcome. Additional studies are needed to determine its mechanism of action.

Expression of phospholipase A2 receptor and IgG4 in patients with membranous nephropathy.

ObjectivesThe aims of this study were to detect the expression of M phospholipase A2 receptor (PLA2R) in the kidney tissue of patients with idiopathic membranous nephropathy (IMN), secondary membranous nephropathy (SMN), and the nonmembranous nephropathy (non-MN), to evaluate the value of PLA2R in the kidney tissue and serum anti-PLA2R antibody in the diagnosis of membranous nephropathy (MN), and to explore the relationship between PLA2R of the kidney tissue or serum anti-PLA2R antibody and clinical features of MN.MethodsThe kidney tissue was collected by kidney biopsy. Immunofluorescence assay was used to detect the level of PLA2R and IgG4 antigen in kidney tissue. Furthermore, the level of the PLA2R was detected using the enzyme-linked immunosorbent assay (ELISA). The positive and negative rates of PLA2R and IgG4 in different diseases and the sensitivity and specificity, were calculated using the statistical method. The specificity and coincidence rate of PLA2R or anti-PLA2R used in the differential diagnosis of IMN and SMN were evaluated.ResultsThe expression intensities of anti-PLA2R antibody and IgG4 were significantly higher in patients with IMN than in patients with SMN but are not non-MN. There was no significant difference in anti-PLA2R antibody and IgG4 in patients with SMN and non-MN. The coincidence rate of serum anti-PLA2R antibody and PLA2R in kidney tissue was 100%.ConclusionThe expression of PLA2R and IgG4 antibody had great significance in the pathological diagnosis of MN. The detection of the serum anti-PLA2R antibody had great diagnostic value in diagnosing MN.

Anti-Double-Stranded DNA IgG Participates in Renal Fibrosis through Suppressing the Suppressor of Cytokine Signaling 1 Signals.

Suppressor of cytokine signaling 1 (SOCS1) participates in renal fibrosis by downregulating Janus kinase 2 (JAK2)/signal transducer and activator of transcription 1 (STAT1)-mediated cytokine signaling. Recently, it was found that anti-double-stranded DNA (dsDNA) IgG induces the synthesis of profibrotic cytokines by renal cells. To explore the potential effect of anti-dsDNA IgG on SOCS1-mediated renal fibrosis, kidney tissues were collected from patients with lupus nephritis (LN) as well as MRL/lpr lupus-prone mice. The SOCS1 expression was evaluated in tissue samples. In addition, SCID mice were injected with anti-dsDNA IgG, followed by evaluation of SOCS1 levels. Renal resident cells were cultured in vitro, receiving the stimulation of anti-dsDNA IgG and then the measurement of SOCS1, JAK2, STAT1α, and profibrotic cytokines. Moreover, the binding of anti-dsDNA IgG to SOCS1 kinase inhibitory region (KIR) peptide was analyzed by surface plasmon resonance. We found that SOCS1 expression was inhibited, but JAK2/STAT1 activation was prominent in the kidney tissues of patients with LN, MRL/lpr mice, or anti-dsDNA IgG-injected SCID mice. The cultured renal cells also showed SOCS1 downregulation, JAK2/STAT1 activation, and profibrotic cytokine promotion upon anti-dsDNA IgG stimulation. Surprisingly, anti-dsDNA IgG showed high affinity to KIR peptide and competed with JAK2 loop for KIR. Additionally, a DNA-mimicking peptide (ALW) blocked the binding of anti-dsDNA IgG to KIR, and even partially abrogated the activation of JAK2/STAT1α signals and the expression of profibrotic cytokines in SCID mice. In conclusion, anti-dsDNA IgG downregulates SOCS1 expression, activates JAK2/STAT1 signals, and contributes to renal fibrosis; its peptide blockade may restore the SOCS1 inhibitory effect on the production of profibrotic cytokine, and finally ameliorate renal fibrosis in LN.

Association of BAFF with PI3K/Akt/mTOR signaling in lupus nephritis.

Systemic lupus erythematosus is a connective tissue disease characterized by autoimmune inflammation, which leads to specific and nonspecific immune disorders with the formation of various autoantibodies by activated B cells. B-cell-activating factor (BAFF) is secreted by macrophages and activated T cells, and is responsible for the proliferation, maturation and differentiation of B cells. However, the mechanism of BAFF involvement in lupus nephritis (LN) remains unclear. The aim of the present study was to investigate the association between BAFF and phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling in order to elucidate the pathogenesis of LN. In the present study, 18 patients with LN and 20 controls were included. The clinical data were analyzed and plasma levels of BAFF were measured using an ELISA. The mRNA and protein levels of BAFF, phosphorylated (p)-PI3K, p-Akt and p-mTOR in kidney tissues were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. Plasma BAFF levels were significantly increased in patients with LN compared with the controls (P<0.001). mRNA and protein levels of BAFF, p-PI3K, p-Akt and p-mTOR in kidney tissue were significantly increased in patients with LN compared with the controls (all P<0.001). mRNA and protein levels of BAFF in the kidney tissues of patients with LN were positively correlated with the levels of p-PI3K, p-Akt and p-mTOR. The results of the present study revealed a correlation between BAFF and the PI3K/Akt/mTOR signaling pathway, and it is hypothesized that they are involved in the pathogenesis of LN.

Association of podocyte autophagosome numbers with idiopathic membranous nephropathy and secondary membranous nephropathy.

This study was to investigate the relation between the number of autophagosomes in podocytes and the syndromes of idiopathic membranous nephropathy (IMN) and secondary membranous nephropathy (sMN). The pathological changes in the kidney tissues of patients were detected with the hematoxylin and eosin staining, the periodic acid-Schiff reagent treatment, the Masson's trichrome staining and the immunofluorescence detection (IF). Meanwhile, the autophagosomes in podocyte were analyzed by transmission electron microscopy and the IF assay pointing to LC3-II, an autophagic marker. Clinical data, including age, sex, edema, serum creatinine, estimated glomerular filtration rate, hematuria, urine protein excretion and serum albumin, were collected from in-patient medical records. Finally, the association of podocyte autophagosome numbers with idiopathic membranous nephropathy and secondary membranous nephropathy was studied. Fewer autophagosomes were observed in podocytes of nephropathy group compared with the control group. Moreover, there was a significant difference in the autophagosome number between the two types of MN and each kind of nephropathy demonstrated distinct characteristics. Although the reduced autophagosome number in the IMN cases was not related to sex, this trend was exacerbated along with the progression from pathological stage I to II. In contrast, fewer autophagosomes were observed in class II and V LN patients compared with the controls, while greater numbers were detected in class III and IV LN patients. The results indicated that the autophagy participated in the podocyte injury in IMN and sMN and the number of autophagosomes in podocytes was related to the pathological classification.

Urotensin II Induces ER Stress and EMT and Increase Extracellular Matrix Production in Renal Tubular Epithelial Cell in Early Diabetic Mice

Background/Aims: Urotensin II (UII) and its receptor are highly expressed in the kidney tissue of patients with diabetic nephropathy (DN). The aim of this study is to examine the roles of UII in the induction of endoplasmic reticulum stress (ER stress) and Epithelial-mesenchymal transition (EMT) in DN in vivo and in vitro. Methods: Kidney tissues were collected from patients with DN. C57BL/6 mice and mice with UII receptor knock out were injected with two consecutive doses of streptozotocin to induce diabetes and were sacrificed at 3^th week for in vivo study. HK-2 cells in vitro were cultured and treated with UII. Markers of ER stress and EMT, fibronectin and type IV collagen were detected by immunohistochemistry, real time PCR and western blot. Results: We found that the expressions of protein of UII, GRP78, CHOP, ALPHA-SMA, fibronectin and type IV collagen were upregulated while E-cadherin protein was downregulated as shown by immunohistochemistry or western blot analysis in kidney of diabetic mice in comparison to normal control; moreover expressions of GRP78, CHOP, ALPHA-SMA, fibronectin and type IV collagen were inhibited while E-caherin expression was enhanced in kidney in diabetic mice with UII receptor knock out in comparison to C57BL/6 diabetic mice. In HK-2 cells, UII induced upregulation of GRP78, CHOP, ALPHA-SMA, fibroblast-specifc protein 1(FSP-1), fibronectin and type collagen and downregulation of E-cadherin. UII receptor antagonist can block UII-induced ER stress and EMT; moreover, 4-PBA can inhibit the mRNA expression of ALPHA-SMA and FSP1 induced by UII in HK-2 cells. Conclusions: We are the first to verify UII induces ER stress and EMT and increase extracellular matrix production in renal tubular epithelial cell in early diabetic mice. Moreover, UII may induce renal tubular epithelial EMT via triggering ER stress pathway in vitro, which might be the new pathogenic pathway for the development of renal fibrosis in DN.

Expression pattern of aquaporins in patients with primary nephrotic syndrome with edema.

The association between the expression of aquaporins (AQPs) in kidney tissues and the occurrence of edema in nephrotic syndrome (NS) remains unclear. The current study aimed to investigate this association. A total of 54 patients with primary glomerular disease, diagnosed by renal biopsy, were divided into three groups: Control, NS without edema and NS with edema. The expression of AQP1, AQP2, AQP3 and AQP4 in kidney tissues from these patients was assessed using immunohistochemistry, and urinary AQP concentrations were quantified by ELISA. Comparison of the three groups was conducted using one way analysis of variance, independent samples t-test or the Chi-square test. AQP1 was strongly expressed in the proximal tubules. The proportion of the AQP1-positive area in kidney tissues from patients with NS with edema was significantly reduced, in comparison with the other two groups. By contrast, the proportion of the AQP2-positive area in the NS with edema group was significantly higher than that of the other two groups; significant differences were also observed between the control and NS without edema groups for this parameter. Urinary AQP2 concentrations in patients with NS (with and without edema) were significantly higher than that of the control group, and exhibited a significant positive correlation with kidney tissue AQP2 concentrations. The present study demonstrated the abnormal expression pattern of AQP1-AQP4 in the kidney tissues of patients with NS, providing a basis for an improved understanding of the role of AQP in the pathogenesis of NS.

MiR-135a promotes renal fibrosis in diabetic nephropathy by regulating TRPC1.

The contribution of aberrantly expressed microRNAs (miRNAs) to diabetic nephropathy in vivo is poorly understood. Integrated comparative miRNA array profiling was used to examine the expression of serum miRNAs in patients with diabetic nephropathy. The abundance of miRNA-135a (miR-135a) was measured by real-time quantitative PCR in the serum and kidney tissues of patients with diabetic nephropathy. The luciferase assay combined with mutation and immunoblotting was used to screen and verify the bioinformatically predicted miRNAs. Ca(2+) entry or intracellular Ca(2+) ([Ca(2+)]i) was performed by imaging Fura-2/AM-loaded cells using a fluorescence microscopy system. The role of miR-135a in vivo was explored with locked nucleic acid antisense oligonucleotides. MiR-135a was markedly upregulated in serum and renal tissue from patients with diabetic nephropathy, as well from db/db mice, and this was associated with the development of microalbuminuria and renal fibrosis. Furthermore, we identified transient receptor potential cation channel, subfamily C, member 1 (TRPC1) as a target of miR-135a during renal injury. We demonstrated that overexpression of TRPC1 was able to reverse the pathological effects of miR-135a on promoting proliferation of mesangial cells and increasing synthesis of extracellular matrix proteins. Moreover, miR-135a attenuated store depletion-induced Ca(2+) entry into cells by regulating TRPC1. Importantly, knockdown of miR-135a in diabetic kidneys restored levels of TRPC1 and reduced synthesis of fibronectin and collagen I in vivo. Suppressing TRPC1 levels to prevent Ca(2+) entry into cells may be a mechanism whereby miR-135a promotes renal fibrosis in diabetic kidney injury. These findings suggest an important role for miR-135a in renal fibrosis and inhibition of miR-135a might be an effective therapy for diabetic nephropathy.

Expression of TNFRSF6B in kidneys is a novel predictor for progression of chronic kidney disease

TNFRSF6B overexpression in tumors is a novel predictor for poor prognosis in various cancers; however, whether TNFRSF6B could be expressed in kidney tissues of patients with chronic kidney disease is unknown. Current established risk factors cannot fully predict the progression of chronic kidney disease, and, therefore, it is mandatory to develop a newer marker for predicting disease progression. We conducted a prospective cohort study comprised 167 patients with chronic kidney disease undergoing renal biopsy at a tertiary hospital with median follow-up of 30.5 months. Computer-assisted quantitative immunohistochemical staining analysis of TNFRSF6B in kidney tissues, the expression of α-smooth muscle actin and percentage of fibrosis in renal interstitium, estimated glomerular filtration rate, and urinary protein excretion rate were investigated. Study endpoint was a doubling of serum creatinine and/or end-stage renal failure requiring renal replacement therapy. We found that TNFRSF6B was predominantly expressed in the tubular epithelial cells of renal cortex. The higher the expression of TNFRSF6B, the more the expression of α-smooth muscle actin and fibrosis in interstitium (P<0.001). Forty patients reaching endpoint had lower baseline estimated glomerular filtration rate and higher expression of TNFRSF6B in renal tubular epithelial cells. Multivariate Cox regression analysis showed that high expression of TNFRSF6B independently predicted the risk toward the renal endpoint with a hazard ratio of 3.46 (95% confidence interval (CI) 1.76–6.80, P<0.001) by adjusting for clinical and pathologic variables. While added to a model of estimated glomerular filtration rate, proteinuria and other conventional risk factors, TNFRSF6B further significantly improved the model predictability for progression of chronic kidney disease (area under the curve, 0.82). In conclusion, TNFRSF6B is associated with renal fibrosis and high expression of TNFRSF6B is a novel biomarker for predicting the progression of chronic kidney disease.

Role of expression of endothelin-1 and angiotensin-II and hypoxia-inducible factor-1α in the kidney tissues of patients with Diabetic Nephropathy

The objective of this study was to detect the expression of Angiotensin-II (Ang-II), Hypoxia-inducible factor-1α (HIF-1α) and Endothelin-1 (ET-1) in the kidneys of patients with diabetic nephropathy (DN) and to investigate their relationship with renal interstitial fibrosis (RIF). A total of 47 paraffin specimens of patients with DN and six controls were enrolled in this study, and all were diagnosed by histopathology. We studied the expressions of Ang-II, HIF-1α and ET-1 by immuno-histochemical staining and the level of RIF by Masson staining. The following results were found: (a) RIF existed in the kidneys of patients with DN, (b) the expressions of Ang-II, HIF-1α and ET-1 were lower in the control group but increased significantly in the DN group, (c) the expression of Ang-II, HIF-1α and ET-1 in tubular epithelial cells directly correlated with RIF (r s = 0.659, 0.633, 0.716, P <0.01) and (d) the expression of Ang-II, ET-1 and HIF-1α in the kidneys of patients with DN positively correlated with serum creatinine (Scr) levels (r s = 0.391, 0.594, 0.531, P <0.01) but they did not correlate with the 24-h urinary protein, blood glucose and serum albumin levels. These results provide new insights suggesting that over-expression of Ang-II, HIF-1α and ET-1 promote the progression of RIF in DN. Thus, targeting reduction in the expression of Ang-II, HIF-1α and ET-1 can delay RIF in DN. Further studies are needed to validate this observation.

Expression and identification of splicing isoforms VitK epoxide reductase gene in the kidney of patients with calcium oxalate urolithiasis

Objective To analyze vitamin K epoxide reductase complex subunit 1 (VKORC1) in the kidney tissues of patients with calcium oxalate urolithiasis. Methods Twenty-one specimens of kidney tissues were harvested from urolithic patients. VKORC1 in the kidney was amplified by the reverse transcription-polymerase chain reaction (RT-PCR), the PCR products were purified, and the VKORC1 gene splicing isoforms were analyzed by direct sequencing and clone sequencing. Results VKORC1 was successfully amplified in the kidney tissues of patients with calcium oxalate urolithiasis and two splice isoforms were obtained. 3% agarose gel electrophoresis showed two bands: about 500 bp ( VI ) , about 400 bp ( V2). After sequencing, there were 110 bp differences in bases, and the remaining sequences were identical. Conclusion In the kidney tissues of patients with calcium oxalate urolithiasis fine VKORC1 splicing isoforms. Key words: Calcium oxalate urolithiasis; Kidney; Vitamin K

Retinoic acid-inducible gene-I (RIG-I) is induced by IFN- in human mesangial cells in culture: possible involvement of RIG-I in the inflammation in lupus nephritis

Interferon-gamma is a potent Th1-type cytokine and a key molecule in the pathogenesis of autoimmune diseases including lupus nephritis. Retinoic acid-inducible gene-I is a putative RNA helicase that plays an important role in immune and inflammatory reactions. We previously demonstrated the increased expression of the retinoic acid-inducible gene-I protein in the kidney tissue of patients with lupus nephritis, and the presence of a significant amount of retinoic acid-inducible gene-I mRNA in the urinary sediment of patients with this inflammatory renal disease. In the present study, interferon-gamma was found to induce the expression of retinoic acid-inducible gene-I in human mesangial cells in culture. Knockdown of retinoic acid-inducible gene-I inhibited the interferon-gamma-induced upregulation of interferon regulatory factor 7, a transcriptional factor involved in immune and inflammatory reactions. These findings suggest that retinoic acid-inducible gene-I produced by mesangial cells may be involved in the pathogenesis of lupus nephritis.

Caspase-4 may play a role in loss of proximal tubules and renal injury in nephropathic cystinosis

Nephropathic cystinosis is characterized clinically by generalized proximal renal tubular dysfunction, renal Fanconi Syndrome and progressive renal failure. Glomerular-proximal tubule disconnection has been noted in renal biopsies from patients with nephropathic cystinosis. In vitro studies performed in cystinotic fibroblasts and renal proximal tubular cells support a role for apoptosis of the glomerulotubular junction, and we have further extended these studies to human native cystinotic kidney specimens. We performed semi-quantitative analysis of tubular density in kidney biopsies from patients with nephropathic cystinosis and demonstrated a significant reduction (p=0.0003) in the number of proximal tubules in the kidney tissue of patients with cystinosis compared to normal kidneys and kidneys with other causes of renal injury; this reduction appears to be associated with the over-expression of caspase-4. This study provides the first quantitative evidence of a loss of proximal tubules in nephropathic cystinosis and suggests a possible role of caspase-4 in the apoptotic loss of proximal tubular cells. Further work is needed to elucidate if this injury mechanism may be causative for the progression of renal functional decline in nephropathic cystinosis.

Concentrations of secreted protein acidic and rich in cysteine in serum and urine and its expression in kidney tissues of patients with IgA nephropathy

Objective:To investigate the concentrations of secreted protein acidic and rich in cysteine(SPARC)in the serum and urine of patients with IgA nephropathy and its expression in the kidney tissues.Methods:The concentrations of SPARC, tumor necrosis factor-α(TNF-α),interleukin 1β(IL-1β),and interleukin 6(IL-6)in the serum and urine were measured with enzyme-linked immunosorbent assay(ELISA).The contents of'SPARC protein in the culture medium of human mesangial cell (HMC)and human renal tubular epithelial cell(HKC),which had been treated with IL-6,were determined by ELISA.The ex- pression and distribution of SPARC in IgA nephropathy and normal kidney tissues were observed by immunohistochemistry as- say.Results:The concentrations of SPARC in serum and urine of IgA nephropathy patients were higher than those of the normal control subjects([2.43±1.22]μg/ml vs[0.69±0.21]μg/ml,[7.73±2.81]μg/ml vs[1.17±1.03]μg/ml,P0.01).The serum levels of TNF-α,IL-1βand IL-6 in IgA nephropathy group were significantly higher than those in the control group(P0.05);the urinary levels of TNF-αand IL-6 in IgA nephropathy group were also higher than those in the controls(P0.01). SPARC protein secreted by HKC was higher than that by HMC(P0.01).SPARC was weakly positive in normal distal cortical tubules.SPARC protein expression in tubular epithelial cells of IgA nephropathy patients was obviously higher than that of the normal controls.Condusion:The secretion of SPARC by renal tubular epithelial cells is increased in patients with IgA nephropa- thy,which results in elevation of serum SPARC and may have a protective feedback inhibitory effect on HMC proliferation.

Upregulation and function of GADD45γ in unilateral ureteral obstruction

We performed differential display analysis to determine transcriptional activity in the rat kidney, following unilateral ureteral obstruction and found a 12-fold increase in the expression of Growth Arrest and DNA Damage-45gamma (GADD45gamma), a stress-responsive molecule that interacts with cell-cycle proteins. GADD45gamma was strongly expressed in as little as 6 h following ureteric obstruction in the renal tubules, and was also found in kidney tissue of patients with chronic glomerulonephritis. Adenovirus-mediated expression of GADD45gamma in cultured renal tubular cells activated p38 along with a significant upregulation of C-C and C-X3-C chemokine ligands and fibrosis-related factors such as several matrix metalloproteinases, transforming growth factor-beta1, decorin, and bone morphogenetic protein 2. Silencing of GADD45gamma expression significantly blunted the upregulation of these inflammatory and fibrogenic mediators and monocyte infiltration in the ureteral obstructed rat kidney. Our study shows that GADD45gamma is quickly upregulated in the kidney with an obstructed ureter, enhancing the production of factors regulating the pathogenesis of kidney disease.

Detection and analysis of HBV antigen protein in kidney tissue and HBV DNA in serum and kidney tissue of patients with HBsAg+ IgA nephropathy.

To explore the relationship between hepatitis B virus (HBV) infection and development of IgA nephropathy. HBsAg and HBcAg protein in renal biopsy specimens of 32 cases was detected on frozen sections and HBV DNA was detected in paraffin section of renal biopsies and in serum of 42 HBsAg positive cases. The positive rate of HBAg in renal biopsies of IgA nephropathy was 59.1%, and 63.6% in non-IgA nephropathy, there was no significant difference between them. In 42 cases biopsies of renal tissues, only five were HBV-DNA positive (11.9%). The five cases were HBsAg, HBcAb and HBeAg positive, the pathological diagnosis of two cases were mesangial proliferative glomerulonephritis; one had minimal change of glomerulonephritis; and one had basement membrane change; and only one had IgA nephropathy. At the same time, in 42 HBsAg+ cases the serum specimens were detected; 12 cases were positive for HBsAg, HBcAg and HBeAg, in whom serum HBV-DNA was positive, but only 5 were positive for HBV-DNA in renal biopsy tissue, and HBV-DNA was negative in other 30 blood serum and tissue specimens. The difference in expression of HBsAg, HBcAb and HBeAg protein between IgA nephropathy and non-IgA nephropathy tissue from renal biopsy was not significant. There is no direct relationship between HBV infection and IgA nephropathy.

Up-regulation in the kidney and its genetic polymorphism of MUC20, a regulator of Met signaling cascade, in patients with IgA nephropathy

MUC20, a novel mucin protein highly expressed in kidney, was isolated as an up-regulated gene in renal tissues of patients with IgA nephropathy (IgAN) ( J Biol Chem 279:1968, 2004). Functional analyses of MUC20 have demonstrated its role as a negative regulator of hepatocyte growth factor (HGF)-induced Grb2-Ras pathway. The C-terminus of MUC20 associates with the multifunctional docking site of Met, preventing Grb2 recruitment to Met and thus attenuating HGF-induced proliferation and matrix metalloproteinase expression ( Mol Cell Biol 24:7456, 2004). In addition, it has been suggested that the oligomerization of MUC20, caused by its overproduction or some other unknown factor(s), which leads to this association with Met. Interestingly, in human MUC20, the repeat numbers of the extracellular tandem domain, which may have an influence on the oligomerization, showed a divergence, with two to six repeat types in several human cell lines. In this study, to clarify the role of MUC20 in human kidney diseases, we analyzed the expression of MUC20 in kidney tissues of patients with IgAN by in situ hybridization. We also investigated the possible association of the tandem repeat polymorphism of MUC20 with renal survival in 236 patients with histologically proven IgAN. In normal kidneys, the expression of MUC20 was confined to the distal tubules, where Met was colocalized by immunohsitochemistry. In addition, glomerular podocytes and the parietal epithelial cells lining Bowman's capsule demonstrated positive expression of MUC20. In renal tissues of IgAN, up-regulation of MUC20 expression in proximal tubules, as well as in distal tubules, was observed. By Kaplan-Meier analysis, the prognosis of IgAN patients with five or six of tandem repeat of MUC20 ( N = 130) was significantly better than those without ( N = 106, log-rank, χ 2 = 10.51) ( P = 0.0012). The tandem repeat polymorphism of MUC20 was an independent risk factor for the progression of renal dysfunction even after adjusting for other clinical risk factors, including hypertension, urinary protein excretion of more than 1.0 g/day, and no administration of renin angiotensin system inhibitors. This study supports the role of MUC20 in regulating the Met signaling cascade, which is implicated not only in renal development and maintenance of kidney functions but also in tubular repair and regeneration under pathological conditions in human glomerulonephritis. The tandem repeat polymorphism in MUC20, which may directly affect its oligomerization and binding to Met, is associated with the renal prognosis of IgAN. Factors that regulate the function of MUC20 may be useful therapeutic agents for progression of renal injury.

Polyomavirus Nephropathy in Native Kidneys of Non‐Renal Transplant Recipients

Chronic renal dysfunction is common in non-renal solid organ (SOT) and hematopoietic stem cell transplant (HSCT) recipients and is commonly attributed to calcineurin inhibitor toxicity, often without renal histopathologic evaluation. Polyomavirus nephropathy (PVN) is an important cause of allograft dysfunction in kidney transplant recipients but has rarely been reported in native kidneys of non-renal transplant recipients. We report the clinical, pathologic and virologic features of PVN in native kidneys of two allograft recipients. In both, severe renal dysfunction was accompanied by histopathologic evidence of PVN, including characteristic viral inclusions by routine stains, immunohistochemistry and electron microscopy. High levels of BK virus (BKV) DNA were detected in kidney tissue of patients using BKV-specific polymerase chain reaction (PCR). In 1 patient, high levels of BKV DNA were detected in plasma and urine, and administration of low-dose cidofovir was associated with clearance of BK viremia. These results extend the populations in which PVN has been documented in native kidneys to include heart and stem cell transplant recipients, and suggest that cidofovir has activity against BKV in vivo. Studies to define the incidence and potential contribution of PVN to chronic renal dysfunction commonly attributed to calcineurin inhibitor toxicity in non-renal transplant recipients are warranted.