Nephron Experimental Nephrology最新文献

Background: Kidney failure is a debilitating disorder with limited treatment options. The kidney-protective effects of stem cells have been vastly investigated and promising results have been achieved with various sources of stem cells. However, in spite of beneficial effects on other disease models, the renoprotective potential of human cord blood-derived unrestricted somatic stem cells (USSC) has not been examined so far.

Methods: In the present study, acute kidney failure was induced in female nude mice and the effect of USSC transplantation on kidney function and structure was assessed. Furthermore, the expression of some cytokine genes was examined by real-time PCR. Homing of the transplanted cells into kidneys was assessed by flow cytometry, immunohistochemistry, and real-time PCR.

Results: USSC-conditioned medium did not attenuate the in vitro nephrotoxic effects of cisplatin. Transplantation of USSC to nude mice did not protect kidney function and was associated with worsened kidney structural damage. USSC transplantation was also associated with a decline in the renal expression of VEGF-A gene. In spite of these effects, the transplanted cells could not be detected in the kidneys by any of the exploited methods and they were mainly entrapped in the lungs.

Conclusion: These data indicate that USSC are not suitable for cell therapy in the setting of acute kidney injury. Also, this study shows that these stem cells are able to affect damaged kidneys even if they are not homed there.

Background: The therapeutic use of the antineoplastic drug cisplatin (DDP) in the elderly is limited by its nephrotoxic effects. The aim of this study was to examine the effect of short-term calorie restriction (CR) on DDP-induced nephrotoxicity in aged rats.

Methods: A group of 25-month-old male Sprague-Dawley rats were divided into two groups: ad libitum (AL) and CR, which were fed 60% of the food consumed by AL rats for 8 weeks. The two groups were each further randomly divided into two subgroups: OAL control, OAL+DDP, OCR control, and OCR+DDP. A single dose of DDP (6 mg/kg) was injected intraperitoneally. Functional and structural changes of the kidneys were evaluated quantitatively by biochemical, histopathological, and morphometric analyses.

Results: At the end of the 8 weeks, rats in the OCR group lost 14.8% more body mass than rats in the OAL group. Pretreatment with CR had several effects: (1) it reduced the levels of blood urea nitrogen and serum creatinine, (2) it reduced the magnitude of the renal tubular epithelial damage, and (3) it significantly reduced the incidence of activated caspase-3 and TUNEL-positive cells in kidneys injured by DDP. However, SIRT1 had the opposite trend after DDP application between the two groups.

Conclusions: Short-term CR exhibits a renoprotective effect in experimental DDP-induced renal injury, the mechanism of which may involve CR antiapoptotic effects and promotion of SIRT1.

Background/aims: Inflammation is an unavoidable milieu for renal tubular cells during the development of renal tubulointerstitial fibrosis. It has been demonstrated that chemokines including monocyte chemoattractant protein-1 (MCP-1) and IL-8 are related to tubulointerstitial lesions. 15d-PGJ2 may modulate renal tubulointerstitial fibrosis progression via anti-inflammatory effects. However, no information is known about the effects of 15d-PGJ2 on chemokine expression in human proximal renal tubular cells (HPTECs) under inflammation.

Methods: In the present study, HPTECs (HK-2 cells) were stimulated with lipopolysaccharide (LPS) only, or preincubated with 15d-PGJ2. IL-8 and MCP-1 expressions were determined by real-time PCR and ELISA. Nuclear factor-κB (NF-κB) location was detected by immunofluorescence analysis. The p-IKK, p-IκBα and p65/p50 were analyzed by immunoblotting. To investigate the mechanism of inhibitory effects of 15d-PGJ2, the PPAR-γ gene was effectively silenced in HK-2 cells using specific siRNA.

Results: The results showed that application of LPS significantly increased IL-8 and MCP-1 production. Phosphorylation of IκBα, IKK and nucleus translocation of NF-κB significantly increased in LPS-stimulated HK-2 cells. 15d-PGJ2 downregulated LPS-induced IL-8 and MCP-1 production. Interestingly, in PPAR-γ-deficient HK-2 cells, 15d-PGJ2 was still capable of inhibiting chemokines expression and attenuating phosphorylation of IκBα and nucleus translocation of NF-κB.

Conclusion: Collectively, these results suggest that 15d-PGJ2 exerts anti-inflammatory actions on HK-2 cells by attenuating chemokines expression. 15d-PGJ2 inhibits chemokines expression via a PPAR-γ-independent way, which is related to block NF-κB pathway. Since NF-κB is an important regulator of the response of HPTECs to injury, PPAR-γ agonists may represent a key pharmacological target for ameliorating inflammation-associated tubulointerstitial fibrosis.

Background: Tubular atrophy and interstitial fibrosis are well-recognized sequelae of chronic proteinuria; however, little is known regarding the molecular pathways activated within tubulointerstitium in chronic proteinuric nephropathies.

Methods: To investigate the molecular mechanisms of proteinuria-associated tubulointerstitial (TI) disease, doxorubicin nephropathy was induced in rats. Progression of disease was monitored with weekly urinary biomarker assays. Because histopathology revealed multifocal TI injury, immunodirected laser capture microdissection was used to identify and isolate injured proximal tubules, as indicated by kidney injury molecule-1 immunolabeling. Adjacent interstitial cells were harvested separately. Gene expression microarray, manual annotation of gene lists, and Gene Set Enrichment Analysis were performed. A subset of the regulated transcripts was validated by quantitative PCR and immunohistochemistry.

Results: Severe proteinuria preceded tubular injury biomarkers by 1 week. Histology revealed multifocal, mild TI damage at 3 weeks, which progressed in severity at 5 weeks. Affymetrix microarray analysis revealed tissue-specific regulation of gene expression. Manual annotation of gene lists, gene set enrichment analysis, and urinary biomarker assays revealed similarities to pathways activated in direct TI injuries. This suggests commonalities amongst the molecular mechanisms of TI injury secondary to proteinuria, ischemia-reperfusion, and nephrotoxicity. © 2013 S. Karger AG, Basel.

Background/aims: Tenc1 (also known as tensin2) is an integrin-associated focal adhesion molecule that is broadly expressed in mouse tissues including the liver, muscle, heart and kidney. A mouse strain carrying mutated Tenc1, the ICR-derived glomerulonephritis (ICGN) strain, develops severe nephrotic syndrome.

Methods: To elucidate the function of Tenc1 in the kidney, Tenc1(ICGN) was introduced into 2 genetic backgrounds, i.e. DBA/2J (D2) and C57BL/6J (B6), strains that are respectively susceptible and resistant to chronic kidney disease.

Results: Biochemical and histological analysis revealed that homozygous Tenc1(ICGN) mice develop nephrotic syndrome on the D2 background (D2GN) but not on the B6 background (B6GN). Initially, abnormal assembly and maturation of glomerular basement membrane (GBM) were observed, and subsequently effacement of podocyte foot processes was noted in the kidneys of D2GN but not B6GN mice. These defects are likely to be involved in the integrin signaling pathway.

Conclusion: This study suggests that Tenc1 contributes to the maintenance of GBM structures and that the genetic background influences the severity of nephrotic syndrome.

Background/aims: Recent study suggests that activation of parietal epithelial cells (PECs) contributes to pathogenesis of glomerulosclerosis and the activation marker CD44 increases in evolving glomerulosclerosis. Here we examined the pathogenic roles of CD44+ epithelial cells in mouse adriamycin nephropathy (ADRN), a representative rodent model for idiopathic focal segmental glomerulosclerosis (FSGS). We also evaluated whether the prevalence of CD44+ PECs reflects different levels of podocyte injuries.

Methods: As a model of FSGS with different degrees of podocyte injury, ADRN models in mice of different ages were utilized. Immunohistochemistry and immunofluorescence were used to determine roles of CD44 expression.

Results: By immunohistochemistry, CD44 expression became positive in claudin-1+ PECs and an increase in CD44+ PECs was associated with reduced expression of synaptopodin and podocin in diseased glomeruli. Furthermore, immunofluorescence staining demonstrated co-expression with osteopontin, a CD44 ligand that plays a significant role in the progression of glomerulosclerosis, thereby suggesting interactions between these molecules. Analysis of the number of WT-1+ podocytes and the levels of electron microscopic foot process effacement revealed a milder degree of podocyte injury in younger ADRN models compared to older ones. Comparative immunohistochemical analysis indicated that the prevalence of CD44+ PECs consistently reflects different degrees of podocyte injury within each different-aged ADRN model.

Conclusion: CD44+ PECs play significant roles in progressive glomerulosclerosis and the prevalence of the cells reflects different degrees of podocyte injury in ADRN.

Background: ICR-derived glomerulonephritis (ICGN) strain is a novel inbred strain of mice with a hereditary nephrotic syndrome. Deletion mutation of tensin 2 (Tns2), a focal adhesion molecule, has been suggested to be responsible for nephrotic syndrome in ICGN mice; however, the existence of other associative factors has been suggested.

Methods and results: To identify additional associative factors and to better understand the onset mechanism of nephrotic syndrome in ICGN mice, we conducted a comprehensive gene expression analysis using DNA microarray. Immune-related pathways were markedly altered in ICGN mice kidney as compared with ICR mice. Furthermore, the gene expression level of complement component 1, s subcomponent (C1s), whose human homologue has been reported to associate with lupus nephritis, was markedly low in ICGN mouse kidney. Real-time quantitative reverse transcription-polymerase chain reaction confirmed a low expression level of C1s in ICGN mouse liver where the C1s protein is mainly synthesized. A high serum level of anti-dsDNA antibody and deposits of immune complexes were also detected in ICGN mice by enzyme-linked immunosorbent assay and immunohistochemical analyses, respectively.

Conclusion: Our results suggest that the immune system, especially the complement system, is associated with nephrotic syndrome in ICGN mice. We identified a low expression level of C1s gene as an additional associative factor for nephrotic syndrome in ICGN mice. Further studies are needed to elucidate the role of the complement system in the onset of nephrotic syndrome in ICGN mice.