Tubulointerstitial Fibrosis Score Research Articles

Abstract P3190: Renal Tubular Mitochondrial Akt1 Modulates Cardiorenal Metabolic Syndrome

Metabolic syndrome-induced cardiomyopathy is a significant risk factor for cardiovascular diseases (CVDs). The proximal tubular cells of the kidney play a crucial role in regulating glucose and lipid metabolism. Mitochondrial dysfunction in these cells has been linked to the development of metabolic syndrome-induced cardiac dysfunction. AKT1, a serine/threonine protein kinase, regulates mitochondrial function. In this study, we investigated the effects of renal proximal tubular mitochondrial AKT1 on metabolic syndrome-induced cardiomyopathy in transgenic mice. We generated transgenic mouse lines, KMioxCAKT, with inducible overexpression of mitochondrial AKT1, specifically in renal proximal tubular cells. One line was induced with tamoxifen, while the other was with corn oil. Both lines were fed a high-fat diet (HFD) for 16 weeks to provoke metabolic syndrome. For renal function, although serum BUN ( p= 0.728 ) and creatinine ( p=0.622 ) were not changed, the proteinuria ( p=0.031 ) and the urine KIM-1 ( p=0.012 ) were decreased in tamoxifen-induced KMioxCAKT. The glomerulosclerosis index ( p =0.027), tubulointerstitial fibrosis score ( p =0.032), tubular dilatation score ( p =0.032), tubular vacuolation score ( p =0.031), and tubular casts ( p =0.018) of renal histology were amended in tamoxifen-induced KMioxCAKT. The fasting glucose level ( p =0.015); the 15 to 120 minutes glucose levels ( p =0.020); the fasting insulin level ( p=0.037 ), and insulin resistance measured by Homeostatic Model Assessment for Insulin Resistance ( p=0.005 ) were reduced in metabolic syndrome with augmentation of renal tubular mitochondrial AKT1. In addition, tamoxifen-induced KMioxCAKT mice had significantly attenuated cardiac hypertrophy in the heart compared to corn oil-induced KMioxCAKT. Our results suggest that enhancing renal proximal tubular mitochondrial AKT1 could ameliorate the cardiorenal metabolic syndrome.

Sex-specific effects of metformin and liraglutide on renal pathology and expression of connexin 45 and pannexin 1 following long-term high-fat high-sugar diet

The comparative effects of the two commonly used antidiabetic drugs metformin and liraglutide on renal pathology and expression of connexin 45 (Cx45) and pannexin 1 (Panx1) in adult obese rats fed high-fat high-sugar diet (HFHSD) were studied. Considering recent data on the profound influence of sex on metformin and liraglutide effects, we compared the effects of both drugs between male and female animals. 44-week-old Sprague-Dawley rats were separated into 4 groups that were fed: standard diet, HFHSD, HFHSD treated with metformin (s.c., 50 mg/kg/day) and HFHSD treated with liraglutide (s.c., 0.3 mg/kg/day). Treatment with metformin or liraglutide lasted for 14 weeks. Histology and immunohistochemistry were performed to quantify renal pathological changes and Cx45 and Panx1 expression. HFHSD caused thickening of the Bowman’s capsule (BC). Both metformin and liraglutide failed to ameliorate the BC thickening; metformin even worsened it. Effects on the tubulointerstitial fibrosis score, BC thickness and Cx45 and Panx1 expression were sex-dependent. We found a 50% increase in mitochondria in proximal tubules of metformin- and liraglutide-treated HFHSD-fed rats, but these effects were not dependent on the sex. This is a first study showing that the effects of metformin and liraglutide on kidney pathology in rats fed HFHSD are mostly sex-dependent and that these effects are not necessarily beneficial. Both drugs changed the Cx45 and Panx 1 expression; hence their effects could be related to amelioration of disruptions in intercellular communication.

Early Renoprotective Effect of Ruxolitinib in a Rat Model of Diabetic Nephropathy.

Diabetic kidney disease (DKD) is still one of the unresolved major complications of diabetes mellitus, which leads ultimately to end-stage renal disease in both type 1 and type 2 diabetes patients. Available drugs that suppress the renin–angiotensin system have partially minimized the disease impact. Yet, there is an unmet need for new therapeutic interventions to protect the kidneys of diabetic patients. In DN, glomerular sclerosis and tubulointerstitial fibrosis are mediated through several pathways, of which JAK/STAT is a key one. The current study explored the potential renoprotective effect of the JAK1/JAK2 inhibitor ruxolitinib (at doses of 0.44, 2.2, and 4.4 mg·kg−1) compared to that of enalapril at a dose of 10 mg·kg−1, in a rat model of streptozotocin-induced diabetes mellitus over 8 weeks. The effect of ruxolitinib was assessed by determining urinary albumin/creatinine ratio, serum level of cystatin, and levels of TGF-β1, NF-κB, and TNF-α in renal tissue homogenates by biochemical assays, the glomerular sclerosis and tubulointerstitial fibrosis scores by histological analysis, and fibronectin, TGF-β1, and Vimentin levels by immunohistochemical staining with the respective antibodies. Our results revealed a significant early favorable effect of a two-week ruxolitinib treatment on the renal function, supported by a decline in the proinflammatory biomarkers of DKD. This pre-clinical study suggests that the renoprotective effect of ruxolitinib in the long term should be investigated in animals, as this drug may prove to be a potential option for the treatment of diabetic kidney disease.

Jian-Pi-Yi-Shen Formula Ameliorates Oxidative Stress, Inflammation, and Apoptosis by Activating the Nrf2 Signaling in 5/6 Nephrectomized Rats

Chronic kidney disease (CKD) is an increasing global public health problem, with high morbidity and mortality. Jian-Pi-Yi-Shen (JPYS) formula is a representative traditional Chinese medicine formula in the treatment of CKD, which is widely used in clinical practice in China. However, the underlying mechanism has not been well elucidated. In the present study, we measured the markers of apoptosis, inflammation, oxidative stress, and nuclear factor erythroid 2–related factor 2 (Nrf2) signaling to investigate the effects of JPYS formula on renal function and fibrosis and its molecular mechanism in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The results demonstrated that the JPYS formula exerted a significant preventive effect on renal dysfunction and fibrosis, based on analysis of correlative parameters such as urinary protein, SCr, BUN, glomerular sclerosis index, and tubulointerstitial fibrosis score and renal histopathology and ultrastructural pathology of CKD rats. JPYS formula also induced downregulation of gene expression associated with fibrosis, such as TGF-β and type I, III, and IV collagen. Moreover, the JPYS formula showed a significant protective effect in suppressing cell apoptosis according to the results of apoptotic indexes, including increased gene expression of Bcl-2, decreased gene expression of Bax, caspase 3, caspase 9, and the number of TUNEL-positive cells. JPYS formula also ameliorated the activation of the NF-κB-mediated inflammatory pathway, as manifested by the downregulation of gene expression of TNF-α, IL-1β, IκBα, NF-κB p65, MCP-1, CXCL1, COX-2, and iNOS in the kidney. Our evidence also suggested that the JPYS formula ameliorates oxidative stress by promoting antioxidant function according to antioxidant index indicators as an indicator of GSH, SOD, CAT, and GPx and abating excessive accumulation of the reactive oxygen species biomarkers, including ROS, TBARS, 8-oxo-dG, and MDA. The data also suggested that the JPYS formula reversed the downregulation of HO-1 and Nrf2 level and upregulation of Keap1 expression. Together, our data highlighted that the JPYS formula relieved renal oxidative injury mediated by activation of Nrf2 signaling by inhibiting inflammation and apoptosis in CKD rats.

Elafibranor Inhibits Chronic Kidney Disease Progression in NASH Mice.

Identification of new pharmacological approaches to inhibit the excessive fat intake-induced steatohepatitis and chronic kidney disease (CKD) is important. High-fat diet (HFD)-induced steatohepatitis and CKD share common pathogenesis involving peroxisome proliferator-activated receptor (PPAR)-α and -δ. Elafibranor, a dual PPARα/δ agonist, can ameliorate the HFD-induced steatohepatitis. Nonetheless, the effects of HFD-induced CKD had not yet explored. This study investigated the effects of elafibranor (elaf) on the progression of HFD-induced CKD in mice. In vivo and in vitro renal effects were evaluated in HFD-elaf mice receiving 12 weeks of elafibranor (from 13th to 24th week of HFD feeding) treatment. In elafibranor-treated HFD mice, increased insulin sensitivity, reduced obesity and body fat mass, decreased severity of steatohepatitis, increased renal expression of PPARα, PPARδ, SIRT1, and autophagy (Beclin-1 and LC3-II) as well as glomerular/renal tubular barrier markers [synaptopodin (podocyte marker), zona occludin-1, and cubulin], reduced renal oxidative stress and caspase-3, and less urinary 8-isoprostanes excretion were observed. Aforementioned benefits of elafibranor were associated with low renal tubular injury and tubulointerstitial fibrosis scores, less albuminuria, low urinary albumin-to-creatinine ratio, and preserved glomerular filtration rate. Acute incubation of podocytes and HK-2 cells with elafibranor or recombinant SIRT1 reversed the HFD-sera-induced oxidative stress, autophagy dysfunction, cell apoptosis, barrier marker loss, albumin endocytosis, and reuptake reduction. Besides hepatoprotective and metabolic beneficial effects, current study showed that elafibranor inhibited the progression of HFD-induced CKD through activation of renal PPARα, PPARδ, SIRT1, autophagy, reduction of oxidative stress, and apoptosis in mice with steatohepatitis.

DCR2, a Cellular Senescent Molecule, Is a Novel Marker for Assessing Tubulointerstitial Fibrosis in Patients with Immunoglobulin A Nephropathy

Background/Aims: Stress-induced cell senescence, which contributes to cell cycle arrest and is independent of age, plays an important role in chronic kidney disease (CKD) progression. DcR2, as a senescent marker, exclusively expressed in senescent tubular epithelia. The objective of this study was to examine whether urinary DcR2 (uDcR2) could be a potential biomarker for tubulointerstitial fibrosis (TIF) in patients with immunoglobulin A nephropathy (IgAN). Methods: This study included 210 IgAN patients and 80 healthy volunteers, with uDcR2 levels measured using enzyme-linked immunosorbent assay. We examined the relationship among uDcR2/Cr levels, renal function, and pathological parameters, using regression analysis to identify risk factors for TIF and the area under the curve (AUC) approach to predict TIF. Renal DcR2 expression was quantified by immunohistochemistry. Co-expression of DcR2 with fibrotic markers (α-smooth muscle actin [α-SMA], collagen III) was analyzed by confocal microscopy. Results: Levels of uDcR2/Cr were significantly higher in IgAN patients and in those with more severe TIF, compared with healthy controls. Serum DcR2 levels were similar across groups. The proportion of IgAN patients with stages 1–2 CKD and T0 was highest among those with uDcR2/Cr <130 ng/g. In contrast, the majority of those with uDcR2/Cr >201 ng/g had stages 4–5 CKD and T2. Levels of uDcR2/Cr were positively associated with urinary albumin to creatinine ratio (ACR), urinary N-acetyl-β-D-glucosaminidase (uNAG)/Cr, and TIF scores and negatively associated with estimated glomerular filtration rate (eGFR). uDcR2/Cr, uNAG, ACR, and eGFR were independent predictors for TIF, with AUC of 0.907 for uDcR2/Cr. This AUC value was higher than that observed for eGFR, uNAG/Cr, or ACR. The sensitivity and specificity of uDcR2/Cr in predicting TIF were 87.0 and 80.5%, respectively. Moreover, uDcR2/Cr levels were positively associated with the percentage of renal DcR2 expression. Renal DcR2 co-localized with α-SMA and collagen III in the kidneys of IgAN patients. Conclusions: Levels of uDcR2/Cr were closely associated with the severity of TIF and renal function parameters. uDcR2/Cr represents a potential biomarker for predicting TIF in IgAN patients.

Renal expression of trefoil factor 3 mRNA in association with tubulointerstitial fibrosis in IgA nephropathy.

ABSTRACTAimTrefoil factor 3 (TFF3) is a small peptide that is involved in mucosal protection. TFF3 is widely expressed in multiple tissues including kidney tissue. Previous studies have reported that the levels of urinary TFF3 are significantly increased in patients with chronic kidney disease. The aim of this study is to detect the TFF3 mRNA in kidney and elucidate the relationship between renal TFF3 mRNA and tubulointerstitial fibrosis in IgA nephropathy (IgAN).MethodsWe investigated the renal mRNA expression of TFF3 by real‐time PCR analysis in biopsy specimens from patients with IgAN, other glomerulonephritis (OGN) and minor glomerular abnormalities (MGA). We also determined the renal localization of TFF3 and the levels of urinary TFF3 by immunostaining and ELISA, respectively.ResultsThe renal TFF3 mRNA expression was significantly associated with the urinary TFF3 secretion and the tubulointerstitial fibrosis score in the IgAN group alone. Immunostaining of the renal specimen of IgAN patients revealed that TFF3 is located in the renal tubular epithelial cells. The locations were almost the same as those that showed uromodulin positivity; specifically, the thick ascending limb (TAL) of the loop of Henle and the early portion of the distal tubule. The urinary TFF3 levels were positively correlated with the levels of urinary biomarkers of tubulointerstitial injury in such patients.ConclusionRenal TFF3 mRNA is associated with renal tubulointerstitial fibrosis in IgAN patients. The TFF3 located in the renal tubular epithelial cells may play a role in the progression of tubulointerstitial fibrosis in IgAN patients.

Role of Sirolimus in renal tubular apoptosis in response to unilateral ureteral obstruction.

Renal tubule cell apoptosis plays a pivotal role in the progression of chronic renal diseases. The previous study indicates that Sirolimus is effective on unilateral ureteral obstruction (UUO)-induced renal fibrosis. However, the role of Sirolimus in renal tubular apoptosis induced by UUO has not yet been addressed. The aim of this study was to determine the role of Sirolimus in renal tubular apoptosis induced by UUO. Male Sprague-Dawley rats were divided into three groups, sham-operated rats, and after which unilateral ureteral obstruction (UUO) was performed: non-treated and sirolimus-treated (1mg/kg). After 4, 7 and 14 d, animals were sacrificed and blood, kidney tissue samples were collected for analyses. Histologic changes and interstitial collagen were determined microscopically following HE and Masson's trichrome staining. The expression of PCNA was investigated using immunohistochemistry and the expression of Bcl-2, Bax, caspase-9, and caspase-3 were investigated using Western blot in each group. Tubular apoptotic cell deaths were assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay. Sirolimus administration resulted in a significant reduction in tubulointerstitial fibrosis scores. After UUO, there was an increase in tubular and interstitial apoptosis in untreated controls as compared to Sirolimus treatment rats (P<0.05). In addition, the expression of PCNA, Bcl-2, Bax, caspase-9, and caspase-3 in obstructed kidney was characterized by immunohistochemistry and Western blot analyses demonstrating that sirolimus treatment significantly reduced PCNA, Bax, caspase-9 and cleaved caspase-3 expression compared to those observed in controls (P<0.05), whereas, Bcl-2 in the obstructed kidney were decreased in untreated controls compared to Sirolimus treatment rats subjected to the same time course of obstruction (P<0.05). We demonstrated a marked renoprotective effect of sirolimus by inhibition of UUO-induced renal tubular apoptosis in vivo.

Feature selection and classification of urinary mRNA microarray data by iterative random forest to diagnose renal fibrosis: a two-stage study

Renal fibrosis is a common pathological pathway of progressive chronic kidney disease (CKD). However, kidney function parameters are suboptimal for detecting early fibrosis, and therefore, novel biomarkers are urgently needed. We designed a 2-stage study and constructed a targeted microarray to detect urinary mRNAs of CKD patients with renal biopsy and healthy participants. We analysed the microarray data by an iterative random forest method to select candidate biomarkers and produce a more accurate classifier of renal fibrosis. Seventy-six and 49 participants were enrolled into stage I and stage II studies, respectively. By the iterative random forest method, we identified a four-mRNA signature in urinary sediment, including TGFβ1, MMP9, TIMP2, and vimentin, as important features of tubulointerstitial fibrosis (TIF). All four mRNAs significantly correlated with TIF scores and discriminated TIF with high sensitivity, which was further validated in the stage-II study. The combined classifiers showed excellent sensitivity and outperformed serum creatinine and estimated glomerular filtration rate measurements in diagnosing TIF. Another four mRNAs significantly correlated with glomerulosclerosis. These findings showed that urinary mRNAs can serve as sensitive biomarkers of renal fibrosis, and the random forest classifier containing urinary mRNAs showed favourable performance in diagnosing early renal fibrosis.

Tacrolimus restores podocyte injury and stabilizes the expression of Cabin1 in 5/6 nephrectomized rats

Podocyte injury is a vital factor, which induces massive proteinuria. Studies have shown that tacrolimus (TAC) protected podocyte via stabilizing cytoskeleton. Our latest study indicates that calcineurin binding protein 1 (Cabin1) undergoes nuclear translocation during podocytes injury. Whether TAC targets on Cabin1 during podocyte injury is still not clear. This study establishes non-immunological proteinuric model. To observe the effect of the treatment of TAC on Cabin1 expression in 5/6 nephrectomized rats. Sprague–Dawley rats were injected with TAC (0.2 mg/kg/day) for 4–8 weeks after 5/6 nephrectomy. Then, rats were sacrificed in the eighth week after operation, renal tissues were processed for morphological studies under light and electrical microscope. Cabin1 expression and distribution were detected by western blot and indirect immunofluorescence staining. In 5/6 nephrectomized rats, urinary protein excretion reached 90.2 ± 30.1 mg/24 h, glomerular sclerosis index and tubulointerstitial fibrosis score were significantly increased, and widespread of podocyte foot processes fusion was found. Moreover, Cabin1 protein expression was markedly increased, and its distribution became much more obviously in podocytes nuclei. In TAC treated rats, urinary protein excretion significantly decreased (44.9 ± 22.5 mg/24 h), glomerular sclerosis and tubulointerstitial fibrosis were alleviated, and podocyte foot processes fusion was inhibited. Furthermore, TAC alleviated the increased protein expression and abnormal distribution of Cabin1. In conclusion, TAC restores podocyte injury and stabilizes the expression of Cabin1. Cabin1 may become a new target to demonstrate the mechanism of TAC in podocyte injury.

Effects of oral carbonic adsorbent (AST-120) on kidney of early-stage chronic kidney disease rats

Aim: to investigate the therapeutic effects of oral carbonic adsorbent on rats with early-stage renal failure. Methods: The early-stage renal failure model was established with three-fourth subtotal nephrectomy Wistar rats. Four weeks after the subtotal nephrectomy, the rats were randomly divided into four groups: (1) adsorbent diet (AD) rats; (2) low protein diet (LPD) group; (3) low protein and AD rats; and (4) normal diet rats as control (ctrl) group. Sham operation group is set as well. The therapeutic effects of adsorbent were examined after 15 weeks treatment. Results: The level of 24 hours urinary protein excretion, serum creatinine (Scr), index of glomerulosclerosis (GSI) and tubulointerstitial fibrosis score (TIFS) of rats with adsorbent or LPD treatment are significantly lower than ctrl group rats. The combination of adsorbent and LPD lowered level of 24 hours urinary protein excretion, Scr, index of GSI and TIFS compared with LPD or adsorbent treatment alone. Conclusion: Both AST-120 and LPD treatment lowered the Scr and blood urea nitrogen level as well as ameliorated the proteinuria and glomerular and tubulointerstitial damage of rats with early stage renal failure. The combined treatment of oral carbonic adsorbent and LPD showed greater therapeutic effects.

Inhibition of the tubular epithelial-to-mesenchymal transition in vivo and in vitro by the Uremic Clearance Granule (尿毒清颗粒)

To investigate the effect of the Uremic Clearance Granule (UCG, ), a Chinese patent medicine, on tubular epithelial-to-mesenchymal transition (EMT) in a unilateral ureteral obstruction (UUO) model in vivo and transforming growth factor (TGF)-β1 induced EMT of HK-2 cells in vitro. In vivo study, 50 Sprague Dawley rats were divided into three groups: a sham operation group (n=10), a UUO group (n=20), and a UUO with UCG treatment group (n=20). The UCG was given at a dose of 4.5 g/kg body weight per day by gavage after surgery. In vitro study, HK-2 cells were cultured in 10% fetal bovine serum (FBS), 10% healthy rat serum, 10% FBS and TGF-β1 (10 ng/mL), 10% healthy rat serum and TGF-β1, or 10% rat serum containing the uremic clearance granule and TGF-β1. The expression of the epithelial marker E-cadherin and the mesenchymal markers vimentin and α-smooth muscle actin (α-SMA) in kidney tissues and HK-2 cells were investigated by Western blot analysis and immunofluorescence staining. The rats of the UUO group showed obvious tubulointerstitial fibrosis, compared with the sham operation group rats. Tubulointerstitial fibrosis score was reduced by 17.5%±1.1% at day 7 and by 20.0%±1.2% at day 14 in the UCG-treated group, compared with the UUO group. The UCG could maintained expression of E-cadherin and suppressed expression of vimentin and α-SMA in kidney tissues of UUO rats at days 7 and 14, as determined by Western blot analysis and immunofluorescence staining. Rat serum containing the UCG partially inhibited TGF-β1-induced fibroblast phenotype of HK-2 cells and maintained the epithelial morphology of HK-2 cells in vitro. This occurred partially through a reduction of vimentin expression and an increase of E-cadherin expression. These results suggest that the UCG prevents tubular EMT and may be a promising agent for treating tubulointerstitial fibrosis.

Angiotensin II blockade upregulates the expression of Klotho, the anti-ageing gene, in an experimental model of chronic cyclosporine nephropathy

The Klotho gene plays a role in suppressing ageing-related disorders. It is suggested that activation of renin-angiotensin system (RAS) or oxidative stress suppresses Klotho in the kidney. This study evaluated the association between Klotho expression and RAS in cyclosporine (CsA)-induced renal injury. Chronic CsA nephropathy was induced by administering CsA (30 mg/kg) to mice on a low-salt diet (LSD) for 4 weeks. A normal-salt diet (NSD) was used as the control. Reverse transcription-polymerase chain reaction, western blot and immunohistochemistry were performed for Klotho and intrarenal RAS activity was measured using immunohistochemistry for angiotensinogen and renin. Oxidative stress was measured with urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG). CsA treatment decreased Klotho mRNA and protein in mouse kidney in a dose-dependent and time-dependent manner, but a concurrent treatment with losartan, an angiotensin II type 1 (AT1) receptor blocker, reversed the decrease in Klotho expression with histological improvement. This finding was more marked in the LSD than the NSD. Klotho expression was correlated with angiotensinogen and renin expression, tubulointerstitial fibrosis score and urinary 8-OHdG excretion. Angiotensin II may play a pivotal role in regulating Klotho expression in CsA-induced renal injury. AT1 receptor blocker may inhibit the ageing process by decreasing oxidative stress caused by CsA.

Tranilast Attenuates Chronic Cyclosporine Nephrotoxicity in Rats

Our aim was to explore the effects of the anti-allergic and antifibrotic agent tranilast on chronic cyclosporine (CsA) nephrotoxicity in rats. Methods Eighteen Sprague-Dawley rats were randomized to be given the following daily treatments by gavage for 4 weeks: (1) controls, olive oil; (2) CsA group, CsA 25 mg/kg; (3) CsA plus tranilast group, CsA 25 mg/kg and tranilast 400 mg/kg. We examined the body weights and the effects of tranilast on histopathology, macrophage (Mϕ) infiltration, and expression of osteopontin (OPN). Results The administration of tranilast improved body weight gain by CsA-treated rats (232 ± 24 vs 203 ± 6 g; P < .05). This treatment reduced the expression of OPN protein and infiltration of macrophages (9.14 ± 2.7 vs 22.44 ± 5.68 ED-1 positive cells per high power field, P < .05). Furthermore compared with the CsA alone group, it ameliorated tubulointerstitial fibrosis scores (1.18 ± 0.08 vs 2.57 ± 0.21, P < .05). Conclusion Tranilast attenuated tubulointerstitial fibrosis through decreased expression of OPN protein and macrophage infiltration, showing renal protective effects in rats with chronic CsA nephrotoxicity.

Expression of transforming growth factor-β–inducible gene-h3 in normal and cyclosporine-treated rat kidney

Up-regulation of transforming growth factor-β (TGF-β) is known to play an important role in the tubulointerstitial injury of chronic cyclosporin A (CsA) nephropathy, but the expression of the TGF-β–inducible gene-h3 (βig-h3) is undetermined. In this study we examined βig-h3 expression and its relationship to tubulointerstitial injury in a rat model of chronic CsA nephropathy. Sprague-Dawley rats kept on a low-salt diet (0.05% sodium) were treated daily for 4 weeks with subcutaneous injections of vehicle (olive oil, 1 mL/kg) or CsA (15 mg/kg). The expression of βig-h3 messenger RNA (mRNA) and protein was evaluated with the use of in situ hybridization, immunohistochemical methods, and immunoblotting. We also compared renal function, histologic findings (tubulointerstitial fibrosis), and expression of TGF-β1 among treatment groups. In vehicle-treated kidney, βig-h3 mRNA and protein were constitutively expressed in the outer medulla and cortex, which was confined to the terminal portion of afferent arterioles, the S3 segment of the proximal tubules, and distal convoluted tubules. CsA treatment significantly up-regulated βig-h3 expression in the interstitium, especially in expanded and fibrotic areas. Quantitative analysis revealed that CsA induced a significant (twofold) increase in βig-h3 mRNA and protein, and this increase was correlated with up-regulation of TGF-β1 expression ( r = .943, P < .001) and the tubulointerstitial fibrosis score ( r = .746, P = .05). Our observations indicate that an increase in βig-h3 expression, along with TGF-β1 up-regulation, is closely associated with tubulointerstitial fibrosis in a rat model of chronic CsA nephropathy.

Long-term treatment with ramipril attenuates renal osteopontin expression in diabetic rats

Osteopontin (OPN) mediates progressive renal injury in various renal diseases by attracting macrophages, and its expression is regulated by the renin-angiotensin system (RAS). We studied the association between OPN expression and tubulointerstitial injury, and investigated the effect of ramipril on OPN expression in an animal model of non-insulin-dependent diabetes mellitus (NIDDM): Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Control (Long-Evans Tokushima Otsuka, LETO) and diabetic (OLETF) rats were treated with ramipril (3 mg/kg in drinking water) or vehicle for nine months, starting at 20 weeks of age. Systolic blood pressure, body weight, urinary protein excretion and oral glucose tolerance tests (OGTT) were monitored periodically. Renal function, histology (glomerulosclerosis, tubulointerstitial fibrosis, and ED-1-positive cells as a measure of macrophage infiltration), and expressions of OPN and transforming growth factor-beta1 (TGF-beta1) were evaluated at the end of the study. Compared with the LETO rats, OLETF rats showed declines in creatinine clearance rate, increases in urinary protein excretion and systolic blood pressure, and development of glomerulosclerosis, tubulointerstitial fibrosis, and inflammatory cell infiltration (all P < 0.05). Blocking angiotensin II with ramipril significantly improved all of these parameters (all P < 0.01). At the molecular level, expressions of OPN and TGF-beta1 were up-regulated in the OLETF rats, and were markedly suppressed following ramipril treatment. The sites of strong OPN mRNA and protein expressions were localized to areas of renal injury. Of note, the expression of OPN mRNA was strongly correlated with the number of ED-1-positive cells (r = 0.560, P = 0.01) and the tubulointerstitial fibrosis score (r = 0.500, P < 0.05). Up-regulation of OPN expression may play a role in tubulointerstitial injury associated with diabetic nephropathy, and blockade of the RAS by ramipril may confer renoprotection by decreasing OPN expression in non-insulin-dependent diabetic nephropathy.

Colchicine Suppresses Osteopontin Expression and Inflammatory Cell Infiltration in Chronic Cyclosporine Nephrotoxicity

Background: Colchicine (Col) is beneficial to renal injury because of its anti-inflammatory effect, but its mechanism has yet to be elucidated. The present study was designed to evaluate the inhibitory effects of colchicine on osteopontin (OPN) expression and the macrophage accumulation in chronic cyclosporine (CsA) nephrotoxicity in rats. Methods: Male adult Sprague-Dawley rats on a low salt diet (LSD, 0.05% sodium) were treated daily with Col (30 µg/kg), CsA (15 mg/kg), and both CsA and colchicine or vehicle (olive oil 1 ml/kg) for 4 weeks. The effects of colchicine on chronic CsA nephrotoxicity were evaluated by examining renal function, histopathology, and ED-1 positive cells. The expressions of OPN mRNA and protein were estimated respectively by Northern blot and immunohistochemistry. Results: Compared with vehicle-treated rats, CsA-treated rats showed an increase in serum creatinine, a decline in creatinine clearance rate, and tubulointerstitial fibrosis (all p < 0.01). Concomitant administration of colchicine reversed all of the above parameters (all p < 0.01). Of note, the upregulated expression of osteopontin mRNA and protein seen in CsA-treated rats was significantly decreased after colchicine treatment. Furthermore, the expression of osteopontin mRNA was strongly correlated with the number of ED-1 positive cells (r = 0.712, p < 0.001) and the tubulointerstitial fibrosis score (r = 0.586, p = 0.007). Conclusion: Colchicine is capable of abrogating the upregulation of chemotactic OPN expression and macrophage influx, and this is associated with improved renal tubulointerstitial fibrosis in chronic CsA nephrotoxicity.