OBJECTIVES: To clarify the causal relationship between the level of cytoplasmic unactivated mineralocorticoid receptor (MR) and the development of tubulointerstitial nephritis (TIN), and to evaluate the impact of MR on dyslipidemia, particularly secondary hyperlipemia, in patients with diabetic kidney disease. METHODS: We conducted a two-sample Mendelian randomization study using genome-wide association study (GWAS) summary data. Genetic variants associated with MR levels were selected as exposures, with TIN and lipid profiles [including low-density lipoprotein cholesterol (LDL-C), triglyceride, and high-density lipoprotein cholesterol] as outcomes. A two-step Mendelian randomization approach was used to assess TIN as a mediator, employing inverse variance weighted regression as the primary analysis, supplemented by Mendelian randomization-Egger, weighted median, and sensitivity analyses. RESULTS: Cytoplasmic unactivated MR level exhibited a significant causal association with a decreased risk of TIN (OR = 0.8598, 95% CI [0.7775-0.9508], P < 0.001). Although no significant causal relationship was identified between MR level and secondary hyperlipemia, a potential association of cytoplasmic unactivated MR level with lower LDL-C levels was observed (OR = 0.9901, 95% CI [0.9821-0.9983], P = 0.018). Additionally, TIN exhibited causal links with secondary hyperlipemia (OR = 1.0016, 95% CI [1.0002-1.0029], P = 0.020) and elevated LDL-C (OR = 1.0111, 95% CI [1.0024-1.0199], P = 0.012), particularly LDL-C in European males (OR = 1.0230, 95% CI [1.0103-1.0358], P < 0.001). Inverse Mendelian randomization analysis revealed causal relationships between TIN and genetically predicted triglyceride (OR = 0.7027, 95% CI [0.6189-0.7978], P < 0.001), high-density lipoprotein cholesterol (OR = 1.1247, 95% CI [1.0019-1.2626], P = 0.046), and LDL-C (OR = 0.8423, 95% CI [0.7220-0.9827], P = 0.029). Notably, TIN mediated 16.7% of the causal association between MR and LDL-C levels. CONCLUSIONS MR plays a critical role in the development of TIN and lipid metabolism, highlighting the potential of MR-antagonists in reducing renal damage and lipid metabolism-associated complications.
Humans ; Mendelian Randomization Analysis ; Nephritis, Interstitial/metabolism* ; Receptors, Mineralocorticoid/genetics* ; Lipid Metabolism/genetics* ; Genome-Wide Association Study ; Male ; Female ; Polymorphism, Single Nucleotide ; Dyslipidemias/metabolism*

BACKGROUND/AIMS: There has been controversy about the role of Toll-like receptor 2 (TLR2) in renal injury following ureteric obstruction. Although inhibition of the renin angiotensin system (RAS) reduces TLR2 expression in mice, the exact relationship between TLR2 and RAS is not known. The aim of this study was to determine whether the RAS modulates TLR2. METHODS: We used 8-week-old male wild type (WT) and TLR2-knockout (KO) mice on a C57Bl/6 background. Unilateral ureteral obstruction (UUO) was induced by complete ligation of the left ureter. Angiotensin (Ang) II (1,000 ng/kg/min) and the direct renin inhibitor aliskiren (25 mg/kg/day) were administrated to mice using an osmotic minipump. Molecular and histologic evaluations were performed. RESULTS: Ang II infusion increased mRNA expression of TLR2 in WT mouse kidneys (p < 0.05). The expression of renin mRNA in TLR2-KO UUO kidneys was significantly higher than that in WT UUO kidneys (p < 0.05). There were no differences in tissue injury score or mRNA expression of monocyte chemotactic protein 1 (MCP-1), osteopontin (OPN), or transforming growth factor beta (TGF-beta) between TLR2-KO UUO and WT UUO kidneys. However, aliskiren decreased the tissue injury score and mRNA expression of TLR2, MCP-1, OPN, and TGF-beta in WT UUO kidneys (p < 0.05). Aliskiren-treated TLR2-KO UUO kidneys showed less kidney injury than aliskiren-treated WT UUO kidneys. CONCLUSIONS: TLR2 deletion induced activation of the RAS in UUO kidneys. Moreover, inhibition of both RAS and TLR2 had an additive ameliorative effect on UUO injury of the kidney.
Amides/*pharmacology ; Angiotensin II/pharmacology ; Animals ; Disease Models, Animal ; Fibrosis ; Fumarates/*pharmacology ; Kidney/*drug effects/metabolism/pathology ; Male ; Mice, Inbred C57BL ; Mice, Knockout ; Nephritis, Interstitial/genetics/metabolism/pathology/*prevention & control ; RNA, Messenger/genetics/metabolism ; Renin/*antagonists & inhibitors/metabolism ; Renin-Angiotensin System/*drug effects ; Toll-Like Receptor 2/deficiency/drug effects/genetics/*metabolism ; Ureteral Obstruction/*drug therapy/genetics/metabolism/pathology

BACKGROUNDIt was reported that combination of mycophenolate mofetil (MMF) and enalapril could reduce proteinuria, improve renal function, and down-regulate diabetes-induced macrophage recruitment and expression of monocyte chemotactic protein 1 (MCP-1) and transforming growth factor beta (TGF-beta) in diabetic renal tissue. But there are no compelling data available for the combination of MMF and angiotensin converting enzyme inhibitor (ACEI) for suppressing tubulointerstitial fibrosis in chronic kidney diseases. The present study was to disclose the effect of MMF combined with benazapril on delaying tubulointerstitial fibrosis and its possible mechanisms in 5/6 nephrectomized rats.

METHODSFifty male SD rats underwent 5/6 nephrectomy (5/6 NX) were randomized into the following groups: NX (5/6 nephrectomized rats, distilled water, n = 10), MMF (MMF 20 mg x kg(-1) x d(-1), p.o., n = 10), Ben (benazepril 10 mg x kg(-1) x d(-1), p.o., n = 10), MMF/Ben (MMF 20 mg x kg(-1) x d(-1), p.o., and benazapril 10 mg x kg(-1) x d(-1), p.o., n = 10). They were monitored for proteinuria and systolic blood pressure every two weeks. After 8 weeks of treatment, serum creatinine and blood urea nitrogen were assayed and pathological damage to the kidney were evaluated. Renal expression and serum levels of platelet-derived growth factor-BB (PDGF-BB), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metaloproteinase-1 (TIMP-1) were detected by immunohistochemistry and ELISA methods.

RESULTSAfter 8 weeks of treatment, 24-hour proteinuria, serum creatinine and blood urea nitrogen were significantly lower in treated groups compared with the untreated rats. MMF and benazepril combination therapy had a greater effect than either drug alone. MMF alone had no effect on systolic blood pressure, but benazapril and MMF/benazapril could significantly reduce blood pressure. Rats that underwent 5/6 nephrectomy had greater tubulointerstitial inflammatory cell infiltration and collagen accumulation than sham-operated rats; all treatments, especially MMF/benazepril, ameliorated these effects. Tubules in 5/6 nephrectomized rats expressed higher levels of PDGF-BB and TIMP-1 and lower MMP-9 compared with sham-operated rats. MMF and benazepril similarly reversed these phenomenons and combination therapy almost completely restored the expression of these cytokines in renal tissue and their plasma concentration.

CONCLUSIONSMMF, especially combined with benazepril, can reduce proteinuria, improve renal function, ameliorate tubulointerstitial fibrosis in 5/6 nephrectomized rats. These effects might be, in part, associated with down-regulation of PDGF-BB and TIMP-1, and MMP-9 up-regulation in renal tissues.

Animals ; Benzazepines ; therapeutic use ; Enzyme-Linked Immunosorbent Assay ; Immunohistochemistry ; Immunosuppressive Agents ; therapeutic use ; Male ; Matrix Metalloproteinase 9 ; metabolism ; Mycophenolic Acid ; analogs & derivatives ; therapeutic use ; Nephrectomy ; Nephritis, Interstitial ; drug therapy ; metabolism ; pathology ; Platelet-Derived Growth Factor ; metabolism ; Proto-Oncogene Proteins c-sis ; Rats ; Rats, Sprague-Dawley ; Tissue Inhibitor of Metalloproteinase-1 ; metabolism

OBJECTIVE: To observe the expression of plasma thrombospondin-1(TSP-1) at different time in protein-overload rats and to analyze the relationship between plasma TSP-1 expression and renal interstitial fibrosis. METHODS: Forty-five male Sprague-Dawley rats were randomly divided into a bovine serum albumin (BSA) group and a control group after uninephrectomization. Rats with protein overload nephropathy induced by intraperitoneally injected BSA were used as a model (control group received saline). At the 1st, 5th, and 9th weekend, the level of 24 h proteinuria and renal function was assessed. Pathological changes were observed by electron and fluorescent microscopy. The expression of plasma TSP-1 was detected by Western blot. The relationship between plasma TSP-1 and tubulointerstitial lesions (TIL) score was analyzed. RESULTS: Twenty-four hour proteinuria and blood urea nitrogen (BUN) significantly increased in protein-overload rats compared with those in the control group. While protein-overload rats developed more severe fibrosis in the tubular and interstitium. Glomerulosclerosis index and TIL score were upregulated compared with those in the control group. The expression of TSP-1 increased significantly at the 5th and 9th weekend. The expression of TSP-1 was positively correlated with TIL score (r=0.836, P<0.01). CONCLUSION Plasma TSP-1 expression is positively correlated with renal interstitial fibrosis in protein-overload rats. Plasma TSP-1 may be used for an important biomarker of renal interstitial fibrosis.
Animals ; Fibrosis ; metabolism ; pathology ; Glomerulosclerosis, Focal Segmental ; pathology ; Kidney ; metabolism ; pathology ; Male ; Nephrectomy ; Nephritis, Interstitial ; etiology ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley ; Thrombospondin 1 ; blood

Total saponins of Panax notoginseng (PNS) have been shown to ameliorate renal interstitial fibrosis. Ginsenoside Rg1, a panaxatriol saponin, is one of the major active molecules from PNS. The present study was undertaken to investigate the effect of ginsenoside Rg1 on renal fibrosis in rats with unilateral ureteral obstruction (UUO). The rats were randomly divided into 3 groups: sham-operation (n=15), UUO (n=15) and UUO with ginsenoside Rg1 treatment (n=15, 50 mg per kg body weight, intraperitoneally (i.p.) injected). The rats were sacrificed on Days 7 and 14 after the surgery. Histological examination demonstrated that ginsenoside Rg1 significantly inhibited interstitial fibrosis including tubular injury as well as collagen deposition. alpha-smooth muscle actin (alpha-SMA) and E-cadherin are two markers of tubular epithelial-myofibroblast transition (TEMT). Interestingly, ginsenoside Rg1 notably decreased alpha-SMA expression and simultaneously enhanced E-cadherin expression. The messenger RNA (mRNA) of transforming growth factor-beta1 (TGF-beta1), a key mediator to regulate TEMT, in the obstructed kidney increased dramatically, but was found to decrease significantly after administration of ginsenoside Rg1. Further study showed that ginsenoside Rg1 considerably decreased the levels of both active TGF-beta1 and phosphorylated Smad2 (pSmad2). Moreover, ginsenoside Rg1 substantially suppressed the expression of thrombospondin-1 (TSP-1), a cytokine which can promote the transcription of TGF-beta1 mRNA and the activation of latent TGF-beta1. These results suggest that ginsenoside Rg1 inhibits renal interstitial fibrosis in rats with UUO. The mechanism might be partly related to the blocking of TEMT via suppressing the expression of TSP-1.
Actins ; biosynthesis ; Animals ; Cadherins ; biosynthesis ; Collagen Type I ; genetics ; metabolism ; Fibronectins ; genetics ; metabolism ; Ginsenosides ; pharmacology ; Immunohistochemistry ; Male ; Nephritis, Interstitial ; drug therapy ; genetics ; metabolism ; pathology ; Panax notoginseng ; chemistry ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Smad2 Protein ; biosynthesis ; Thrombospondin 1 ; biosynthesis ; genetics ; Transforming Growth Factor beta1 ; biosynthesis ; genetics ; Ureteral Obstruction ; metabolism ; pathology

OBJECTIVETo study the effect of Kurarinone on renal tubular epithelial cell-mesenchyma (ECM) trans-differentiation in rats with renal interstitial fibrosis and to explore its possible mechanisms.

METHODSThe rat model of renal interstitial fibrosis was established by unilateral ureteral obstruction (UUO). Sprague-Dawley male rats were randomly divided into 3 groups, the sham-operated group, the UUO group and the Kurarinone treated group (KTG). Rats in the KTG were intraperitoneally injected with Kurarinone 100 mg/kg daily after modeling. Five rats of each group were killed respectively at day 7, 14 and 21 after UUO. The serum levels of blood urea nitrogen (BUN), serum creatinine (SCr), total protein (TP) and albumin (ALB), 24-h urinary protein excretion in rats were measured. Pathological changes of renal tissue were observed by PAS and Masson stain. The expression of transforming growth factor beta1 (TGF-beta1), Smad3, alpha-smooth muscle actin (alpha-SMA) and collagen I (Col I) in kidney were determined with immunohistochemistry. And the expressions of TGF-beta1 and alpha-SMA mRNA in renal tissue were determined using reverse transcription polymerase chain reaction (RT-PCR).

RESULTSThe expression of TGF-beta1, Smad3, alpha-SMA and Col I in the KTG was significantly decreased as compared with that in the UUO group respectively, and the degree of tubular damage and renal interstitial fibrosis was also ameliorated more obviously in the KTG. The TGF-beta1 and alpha-SMA mRNA expressions in KTG were significantly lower than those in the UUO group determined at the corresponding time points (P < 0.05).

CONCLUSIONKurarinone could down-regulate the expression of TGF-beta1 and Col I, inhibit EC-M trans-differentiation, suppress the activation and proliferation of myofibroblast. The probable pathway may be by way of down-regulating Smad3 expression to interfere its induction on intercellular signal transduction and consequently ameliorate renal interstitial fibrosis.

Animals ; Cell Transdifferentiation ; drug effects ; Collagen Type I ; biosynthesis ; genetics ; Epithelial Cells ; drug effects ; metabolism ; pathology ; Fibrosis ; Flavonoids ; pharmacology ; Immunohistochemistry ; Kidney ; drug effects ; metabolism ; pathology ; Kidney Tubules ; drug effects ; metabolism ; pathology ; Male ; Mesoderm ; drug effects ; metabolism ; pathology ; Nephritis, Interstitial ; physiopathology ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Transforming Growth Factor beta1 ; biosynthesis ; genetics

OBJECTIVETo review the mechanisms of epithelial to mesenchymal transition (EMT) and its role in the progression of tubulointerstitial fibrosis.

DATA SOURCESThe data used in this review were obtained mainly from the studies of EMT reported from 2000-2006.

STUDY SELECTIONRelevant articles on studies of EMT in tubulointerstitial fibrosis were selected. Data were mainly extracted from the 45 articles listed in the reference section of this review.

RESULTSThe process of EMT has gained wide recognition as candidate mechanism in progression of chronic fibrotic disorders. New markers were identified and facilitate the observation of EMT. EMT is regulated by many factors through activation of kinase-dependent signaling cascades. Recent findings suggest that EMT is a reversible process, which can be controlled by factors for their epithelial inducing activities.

CONCLUSIONRemarkable progresses of EMT research have been made recently. Preventing or reversing EMT is a promising strategy against renal fibrosis.

Animals ; Connective Tissue Growth Factor ; Disease Progression ; Epithelium ; metabolism ; pathology ; Fibrosis ; Humans ; Immediate-Early Proteins ; metabolism ; Intercellular Signaling Peptides and Proteins ; metabolism ; Mesoderm ; metabolism ; pathology ; Nephritis, Interstitial ; metabolism ; pathology ; Transforming Growth Factors ; metabolism

OBJECTIVETo study the effect and mechanism of Kangxianling (KXL, a TCM herbal compound) on renal interstitial fibrosis induced by unilateral ureteral obstruction (UUO).

METHODSEighteen male SD rats were randomly divided into 3 groups, 6 in each group, the sham operated group, the model group, and the KXL group. Renal interstitial fibrosis model was established in rats by UUO. After rats were raised for additional 14 days, their body weight, serum levels of creatinine (SCr) and blood urea nitrogen (BUN) were analyzed. Then rats were sacrificed, their renal pathology examined by HE staining and PASM staining; expressions of transforming growth factor-beta1 (TGF-beta1), hepatocyte growth factor (HGF) mRNA, and a-smooth muscle actin (alpha-SMA), TGF-beta1 receptor I (TbetaR I), TGF-beta1 receptor II (TbetaR II) and hepatocyte growth factor receptor (C-Met) protein in kidney tissue were determined by RT-PCR and Western blotting respectively.

RESULTSSCr and BUN in the model group were significantly higher than those in the sham operated group (P <0.05). Expressions of TGF-beta1 mRNA and a-SMA, TbetaR I , TbetaR II and C-Met protein in kidney tissue in the model group significantly up-regulated and mRNA expression of HGF significantly down-regulated, and obvious hyperplasia of the base member of glomeruli was seen. After intervention with KXL, BUN content significantly lowered, alpha-SMA, TbetaR I and TbetaR II protein expression decreased and HGF mRNA expression up-regulated significantly in the treated group, with slight pathological changes only shown as mild hyperplasia of the base member of glomeruli and renal tubules.

CONCLUSIONKXL could inhibit the protein expressions of a-SMA, TbetaR I , TbetaR II and increase the mRNA expression of HGF, which is a protective factor against renal fibrosis. Therefore, it is effective in alleviating the renal interstitial fibrosis and improving the renal function in UUO rats.

Animals ; Blotting, Western ; Drugs, Chinese Herbal ; therapeutic use ; Fibrosis ; prevention & control ; Hepatocyte Growth Factor ; biosynthesis ; genetics ; Kidney ; drug effects ; metabolism ; pathology ; Male ; Nephritis, Interstitial ; etiology ; pathology ; prevention & control ; Nephrosclerosis ; pathology ; prevention & control ; Phytotherapy ; RNA, Messenger ; biosynthesis ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Ureteral Obstruction ; complications

OBJECTIVETo investigate the effects of prostaglandin E1 (PGE1) on the progression of aristolochic acid nephropathy (AAN).

METHODSTwenty-four patients diagnosed as AAN with serum creatinine (Scr) between 1.5 mg/dL and 4 mg/dL during September 2001 to August 2003 were randomly divided into 2 groups. All patients had ingested long dan xie gan wan containing aristolochic acid (0.219 mg/g) for at least 3 months. Twelve patients were injected with Alprostadil (10 microg/d for 10 days in one month, summing up to 6 months). Except for PGE1, the other therapy was same in both groups. Renal function was assessed using reciprocal serum creatinine levels (1/Scr).

RESULTSThe level of Scr an d serum hemoglobin (Hgb) was similar in both groups prior to therapy. During follow-up, 1/Scr levels in PGE1 group were significantly higher than control group (P < 0.01), and Hgb levels in PGE1 group were significantly increased compared with control (P < 0.05).

CONCLUSIONPGE1 can slow the progression of renal failure and increase Hgb level of AAN patient.

Adult ; Alprostadil ; therapeutic use ; Aristolochic Acids ; adverse effects ; Creatinine ; blood ; Female ; Follow-Up Studies ; Hemoglobins ; metabolism ; Humans ; Kidney ; pathology ; Male ; Middle Aged ; Nephritis, Interstitial ; chemically induced ; drug therapy ; pathology

Methylmalonic acidemia (MMA) is a heterogeneous inborn error of propionate metabolism and its management frequently includes a low-protein diet to minimize precursors of methylmalonic acid and reduce its concentration in body tissues. In the long- term follow-up, renal dysfunction in these patients has been increasingly recognized. Tubulointerstitial nephritis is the most frequent renal complications and has been reported in the small number of renal biopsy specimens from young children previously by others. We report a case of a 18-year-old girl with MMA and renal dysfunction in whom renal biopsy demonstrated chronic tubulointerstitial nephritis.
Adolescent ; Biopsy ; Child ; Diet, Protein-Restricted ; Diethylpropion ; Female ; Follow-Up Studies ; Humans ; Metabolism ; Methylmalonic Acid ; Nephritis, Interstitial*