Fibronectin In Kidney Research Articles

Expression of LRG-1 in mice with hypertensive renal damage and its significance.

Long-term elevated blood pressure may lead to kidney damage, yet the pathogenesis of hypertensive kidney damage is still unclear. This study aims to explore the role and significance of leucine-rich alpha-2-glycoprotein-1 (LRG-1) in hypertensive renal damage through detecting the levels of LRG-1 in the serum and kidney of mice with hypertensive renal damage and its relationship with related indexes. C57BL/6 mice were used in this study and randomly divided into a control group, an angiotensin II (Ang II) group, and an Ang II+irbesartan group. The control group was gavaged with physiological saline. The Ang II group was pumped subcutaneously at a rate of 1.5 mg/(kg·d) for 28 days to establish the hypertensive renal damage model in mice, and then gavaged with equivalent physiological saline. The Ang II+irbesartan group used the same method to establish the hypertensive renal damage model, and then was gavaged with irbesartan. Immunohistochemistry and Western blotting were used to detect the expression of LRG-1 and fibrosis-related indicators (collagen I and fibronectin) in renal tissues. ELISA was used to evaluate the level of serum LRG-1 and inflammatory cytokines in mice. The urinary protein-creatinine ratio and renal function were determined, and correlation analysis was conducted. Compared with the control group, the levels of serum LRG-1, the expression of LRG-1 protein, collagen I, and fibronectin in kidney in the Ang II group were increased (all P<0.01). After treating with irbesartan, renal damage of hypertensive mice was alleviated, while the levels of LRG-1 in serum and kidney were decreased, and the expression of collagen I and fibronectin was down-regulated (all P<0.01). Correlation analysis showed that the level of serum LRG-1 was positively correlated with urinary protein-creatinine ratio, blood urea nitrogen, and blood creatinine level in hypertensive kidney damage mice. Serum level of LRG-1 was also positively correlated with serum inflammatory factors including TNF-α, IL-1β, and IL-6. Hypertensive renal damage mice display elevated expression of LRG-1 in serum and kidney, and irbesartan can reduce the expression of LRG-1 while alleviating renal damage. The level of serum LRG-1 is positively correlated with the degree of hypertensive renal damage, suggesting that it may participate in the occurrence and development of hypertensive renal damage.

Sacubitril/Valsartan contributes to improving the diabetic kidney disease and regulating the gut microbiota in mice.

Diabetic kidney disease (DKD), as a serious microvascular complication of diabetes, has limted treatment options. It is reported that the Sacubitril/Valsartan (Sac/Val) can improve kidney function, and the disordered gut microbiota and part of its metabolites are related to the development of DKD. Therefore, we aim to explore whether the effect of Sac/Val on DKD is associated with the gut microbiota and related plasma metabolic profiles. Male C57BL/6J mice were randomly divided into 3 groups: Con group (n = 5), DKD group (n = 6), and Sac/Val group (n = 6) . Sac/Val group was treated with Sac/Val solution. The intervention was given once every 2 days for 6 weeks. We measured the blood glucose and urine protein level of mice at different times. We then collected samples at the end of experiment for the 16s rRNA gene sequencing analysis and the untargeted plasma metabonomic analysis. We found that the plasma creatinine concentration of DKD-group mice was significantly higher than that of Con-group mice, whereas it was reduced after the Sac/Val treatment. Compared with DKD mice, Sac/Val treatment could decrease the expression of indicators related to EndMT and renal fibrosis like vimentin, collagen IV and fibronectin in kidney. According to the criteria of LDA ≥ 2.5 and p<0.05, LefSe analysis of gut microbiota identified 13 biomarkers in Con group, and 33 biomarkers in DKD group, mainly including Prevotella, Escherichia_Shigella and Christensenellaceae_R_7_group, etc. For the Sac/Val group, there were 21 biomarkers, such as Bacteroides, Rikenellaceae_RC9_gut_group, Parabacteroides, Lactobacillus, etc. Plasma metabolomics analysis identified a total of 648 metabolites, and 167 important differential metabolites were screened among groups. KEGG pathway of tryptophan metabolism: M and bile secretion: OS had the highest significance of enrichment. Sac/Val improves the renal function of DKD mice by inhibiting renal fibrosis. This drug can also regulate gut microbiota in DKD mice.

512-P: Sexual Differences in Progression of Diabetic Nephropathy in over 26 Type 1 Diabetic Mice

As a transgenic type 1 diabetic model, OVE26 mice develop diabetic nephropathy (DN) with the feature close to advanced DN in human, which makes it a valuable rodent model to study DN. Nevertheless, sexual differences in renal lesions, especially dynamic progression with different ages, remain undefined in OVE26 mice. To explore these issues, male and female OVE26 and wild type nondiabetic FVB mice at 4-, 12-, 24 - and 36-weeks old were used (N=6). Urine albumin-to-creatinine ratio (UACR) was detected to evaluate renal function. Renal histopathology and immunochemical and Western blotting protein expression of inflammation, tubular epithelial-myofibroblast transdifferentiation and fibrosis markers were examined. In FVB mice, blood glucose, triglyceride, UACR and podocytes numbers were constant during aging and comparable in male and female. Age-dependent slightly increase of glomerular mesangial matrix, inflammatory cells infiltration and renal fibrosis were observed in FVB mice. Compared with the age- and sex- matched FVB mice, male OVE26 mice developed hyperglycemia, mesangial matrix accumulation and increased trend of triglyceride at 4-week-old and albuminuria, glomerular enlargement, and upregulations of TGF-β1, α-SMA at 12 weeks old. Significant loss of podocytes, tubular dilation, collagen accumulation, increased trend of macrophage and T lymphocytes infiltrations, and increased protein levels of TNF-α, ICAM and fibronectin in kidney were observed in 24-week old male OVE26 mice. Compared with age-matched male OVE26 mice, female OVE26 mice had significant hypertriglyceridemia, worse renal function and kidney lesions at older age, including higher UACR and sustained loss of podocytes at age of 24 weeks; more inflammatory cells infiltration and renal fibrosis at age of 36 weeks. Our findings suggest the sexual difference in the progression of DN in OVE26 mice to provide evidence for researchers to properly select the age and sex of OVE26 mice in the future type 1 DN study. Disclosure W. Wang: None. L. Cai: None.

Zingerone attenuates diabetic nephropathy through inhibition of nicotinamide adenine dinucleotide phosphate oxidase 4

Diabetes affects a large proportion of population wide across the world and kidney is a main target organ of diabetic complications. Zingerone is a stable active component derived from dry ginger rhizome. We investigated the effect of zingerone on diabetic nephropathy and explored the possible mechanisms. We showed that zingerone decreased the levels of serum insulin, C-peptide and glycosylated hemoglobin A1c. The levels of blood urea nitrogen (BUN), serum creatinine, urinary albumin content and albumin/creatinine ratio (ACR) were reduced by zingerone. Moreover, zingerone attenuated the pathological injuries of kidneys, reduced the surface area of Bowman’s capsule, Bowman’s space, glomerular tuft, and decreased the expression of collagen IV and fibronectin in kidneys in db/db mice. The high levels of triglyceride and cholesterol, and high expression of TNFɑ and IL-6 were decreased by zingerone. Furthermore, zingerone decreased the level of MDA and increased the content of glutathione (GSH). NADPH oxidase 4 (NOX4) expression was significantly increased in kidneys of db/db mice and in HK-2 cells after exposure to high glucose. Zingerone significantly decreased the expression of NOX4 in vivo and in vitro. Upregualtion of NOX4 significantly inhibited zingerone-induced protective effects against the cytotoxicity of high glucose. Downregulation of NOX4 was responsible for zingerone-exhibited pharmacological activities and reduction of diabetic nephropathy. Overall, zingerone is a promising therapeutic treatment to attenuate diabetic nephropathy.

6-Shogaol ameliorates diabetic nephropathy through anti-inflammatory, hyperlipidemic, anti-oxidative activity in db/db mice

The prevalence of type 2 diabetes mellitus has been increasing worldwide and more than two thirds of the patients may develop diabetic nephropathy (DN). However, the efficiency of existing approaches on DN progression is limited. 6-Shogaol (6-SG), a major dehydrated derivative of gingerols, possesses various biological properties. The present study was designed to evaluate the possible effects of 6-SG on DN in db/db mice and to investigate the mechanisms. We revealed that 6-SG reduced the levels of fasting blood glucose, serum insulin, C-peptide, glycosylated hemoglobin A1c, and systolic blood pressure. 6-SG decreased the levels of blood urea nitrogen (BUN), serum creatinine, urinary albumin content and albumin/creatinine ratio (ACR), ameliorated the pathological injuries of kidneys, reduced the surface area of Bowman’s capsule, Bowman’s space, glomerular tuft, and decreased the expression of collagen IV and fibronectin in kidneys of db/db mice. The high levels of systemic and renal triglyceride and cholesterol were decreased by 6-SG. Moreover, 6-SG exhibited anti-inflammatory effects, as reflected by reduction of tumor necrosis factor ɑ (TNFɑ), monocyte chemotactic protein-1 (MCP-1), and IL-6 levels in circulation and kidneys, and decrease of NF-κB expression. Furthermore, 6-SG also inhibited oxidative stress and restored the expression of NF-E2-related factor 2 (Nrf2) in kidneys of db/db mice. In conclusion, we have demonstrated that 6-SG exhibits anti-diabetic and renal protective effects against DN, in which effect the anti-inflammatory, hyperlipidemic, anti-oxidative activities may be involved. Overall, 6-SG could be a promising therapeutic treatment to ameliorate diabetes and the development of DN.

Resveratrol ameliorates diabetic nephropathy in rats through negative regulation of the p38 MAPK/TGF-β1 pathway.

Resveratrol (RSV) has been shown to have a renoprotective effect against diabetic nephropathy, but the underlying mechanisms of this have not been fully elucidated. The aim of the current study was to explore the mechanisms responsible for the therapeutic effects of RSV in rat mesangial cells in vitro and in a rat model of diabetic nephropathy. The viability of CRL-2573 rat mesangial cells and their expression levels of p38, phosphorylated (p)-p38, transforming growth factor beta 1 (TGF-β1) and fibronectin were assessed in response to treatment with high glucose, with or without RSV. Diabetic nephropathy was also induced in Sprague-Dawley rats by streptozotocin treatment. At 8 weeks, basic biochemical parameters and histopathological abnormalities as well as the expression of p38, p-p38, TGF-β1 and fibronectin in rat kidneys were compared between control diabetic rats and those treated with 20 mg/kg RSV daily for 4 weeks. In the mesangial cell line, RSV inhibited high glucose-induced increases in cell viability and fibronectin expression by significantly reducing p38 mitogen-activated protein kinase (MAPK) activation and TGF-β1 expression (P<0.05). In diabetic rats, RSV significantly decreased blood glucose, serum creatinine and urinary albumin levels, as well as the kidney weight and ratio of kidney weight/body weight compared with the control group (P<0.05). Moreover, RSV ameliorated renal histological changes and downregulated the expression of p-p38, TGF-β1 and fibronectin in the kidneys of diabetic rats. These data suggested that RSV protected renal tissue from diabetes-induced injury and that this activity may be via inhibition of the p38 MAPK/TGF-β1 signaling pathway.

Podocyte-specific chemokine (C-C motif) receptor 2 overexpression mediates diabetic renal injury in mice

Inflammation is a central pathophysiologic mechanism that contributes to diabetes mellitus and diabetic nephropathy. Recently, we showed that macrophages directly contribute to diabetic renal injury and that pharmacological blockade or genetic deficiency of chemokine (C-C motif) receptor 2 (CCR2) confers kidney protection in diabetic nephropathy. However, the direct role of CCR2 in kidney-derived cells such as podocytes in diabetic nephropathy remains unclear. To study this, we developed a transgenic mouse model expressing CCR2 specifically in podocytes (Tg[NPHS2-Ccr2]) on a nephropathy-prone (DBA/2J) and CCR2-deficient (Ccr2-/-) background with heterozygous Ccr2+/- littermate controls. Diabetes was induced by streptozotocin. As expected, absence of CCR2 conferred kidney protection after nine weeks of diabetes. In contrast, transgenic CCR2 overexpression in the podocytes of Ccr2-/- mice resulted in significantly increased albuminuria, blood urea nitrogen, histopathologic changes, kidney fibronectin and type 1 collagen expression, podocyte loss, and glomerular apoptosis after nine weeks of streptozotocin-induced diabetes. Interestingly, there was no concurrent increase in kidney macrophage recruitment or inflammatory cytokine levels in the mice. These findings support a direct role for CCR2 expression in podocytes to mediate diabetic renal injury, independent of monocyte/macrophage recruitment. Thus, targeting the CCR2 signaling cascade in podocytes could be a novel therapeutic approach for treatment of diabetic nephropathy.

Arginase inhibition mediates renal tissue protection in diabetic nephropathy by a nitric oxide synthase 3-dependent mechanism

Recently we showed that pharmacological blockade or genetic deficiency of arginase-2 confers kidney protection in diabetic mouse models. Here we tested whether the protective effect of arginase inhibition is nitric oxide synthase-3 (eNOS)-dependent in diabetic nephropathy. Experiments were conducted in eNOS knockout and their wild type littermate mice using multiple low doses of vehicle or streptozotocin and treated with continuous subcutaneous infusion of vehicle or the arginase inhibitor S-(2-Boronoethyl)-L-cysteine by an osmotic pump. Inhibition of arginases for 6 weeks in diabetic wild type mice significantly attenuated albuminuria, the increase in plasma creatinine and blood urea nitrogen, histopathological changes, kidney fibronectin and TNF-α expression, kidney macrophage recruitment, and oxidative stress compared to vehicle-treated diabetic wild type mice. Arginase inhibition in diabetic eNOS knockout mice failed to affect any of these parameters but reduced kidney macrophage recruitment and kidney TNF-α expression compared to vehicle-treated diabetic eNOS knockout mice. Furthermore, diabetic wild type and eNOS knockout mice exhibited increased kidney arginase-2 protein, arginase activity and ornithine levels. Thus, arginase inhibition mediates renal tissue protection in diabetic nephropathy by an eNOS-dependent mechanism and has an eNOS-independent effect on kidney macrophage recruitment.

Angelica Acutiloba Root Alleviates Advanced Glycation End‐Product‐Mediated Renal Injury in Streptozotocin‐Diabetic Rats

Angelica acutiloba root, a Japanese species of Dong quai being cultivated in Hualien County in eastern Taiwan, is used primarily for gynecological disorders in women. Increasing evidence indicates that advanced glycation end-products (AGEs) contribute to the pathogenesis of diabetic nephropathy. We investigated whether A. acutiloba root is beneficial in the amelioration of AGE-mediated renal injury in a diabetic rat model. Streptozotocin (STZ)-diabetic rats were treated orally with A. acutiloba root extract (AARE) [50, 100, 200 mg/(kg × day)] for 8 wk. Changes in renal function-related parameters in plasma and urine were analyzed at the end of the study. Kidneys were isolated for enzyme immunoassay, pathology histology, immunohistochemistry, and Western blot analyses. Polyphenolic compounds and flavonoids were abundant in AARE. AARE [200 mg/(kg × day)] partially decreased the high plasma glucose level in diabetic rats. Diabetic-dependent alterations in urinary albumin, 24-h urinary albumin excretion rate, creatinine clearance, and glomerular mesangial matrix expansion were ameliorated by AARE treatment. The increased expression of nuclear factor-κB, transforming growth factor-β(1), and the progressive accumulation of fibronectin in kidney of diabetic rats were attenuated by AARE treatment. AARE treatment ameliorated the elevated levels of advanced glycation end products (AGEs) and mitochondrial thiobarbituric acid-reactive substance, as well as the elevated levels of Nε-(carboxymethyl)lysine and receptors for AGEs in kidneys of diabetic rats. The results show that A. acutiloba root has an anti-diabetic property that involves antihyperglycemia accompanied by amelioration of glycation-mediated renal damage.

Uric acid increases fibronectin synthesis through upregulation of lysyl oxidase expression in rat renal tubular epithelial cells

Urate is produced as the major end product of purine metabolism. In the last decade, the incidence of hyperuricemia increased markedly, and similar trends in the epidemiology of metabolic syndrome have been observed. Hyperuricemia is associated with renal disease, and recent studies have reported that mild hyperuricemia results in hypertension, intrarenal vascular disease, and renal injury. This has led to the hypothesis that uric acid may contribute to renal fibrosis and progressive renal disease. Our purpose was to investigate the relationship between uric acid and renal tubular injury. We applied the method of intraperitoneal injection of uric acid to generate the hyperuricemic mouse model. Compared with the saline injection group, the expression of lysyl oxidase (LOX) and fibronectin in kidneys was increased significantly in hyperuricemic groups. In vitro, uric acid significantly induced NRK-52E cells to express the ECM marker fibronectin, as well as LOX, which plays a pivotal role in ECM maturation, in a time- and dose-dependent manner. Upregulation of the urate transporter URAT1, which is located in the apical membrane of proximal tubules, sensitized the uric acid-induced fibronectin and LOX induction, while both knocking down URAT1 expression in tubular epithelial cells by RNA interference and inhibiting URAT1 function pharmacologically attenuated LOX and fibronectin expression. Furthermore, knockdown of LOX expression by a small interfering RNA strategy led to a decrease in fibronectin abundance induced by uric acid treatment. In addition, evidence of a uric acid-induced activation of the NF-kappaB signaling cascade was observed. Our findings highlight a need for carefully reevaluating our previous view on the pathological roles of hyperuricemia in the kidney and nephropathy induced by uric acid in clinical practice.

The amelioration of streptozotocin diabetes-induced renal damage by Wu-Ling-San (Hoelen Five Herb Formula), a traditional Chinese prescription

Ethnopharmacological relevance Wu-Ling-San (Hoelen Five Herb Formula) is a Chinese prescription used to promote water metabolism. Aim of the study The present study was undertaken to characterize the effects of Wu-Ling-San on diabetic nephropathy. Materials and methods Streptozotocin (STZ)-diabetic rats were orally administrated with Wu-Ling-San (0.5, 1.5, 2.5 g/(kg day)) once a day for 10 weeks. Changes in the renal function related parameters in plasma and urine were analyzed at the end of 10-week administration. Kidney was isolated for pathology histology, immunohistochemistry staining and Western blot analyses. Results Wu-Ling-San (2.5 g/(kg day)) partially decreased the high plasma glucose level in diabetic rats. Diabetic-dependent alterations in urinary albumin, 24-h urinary albumin excretion rate, creatinine clearance, and glomerular mesangial matrix expansion were ameliorated by Wu-Ling-San. The increased expression of nuclear factor-kB as well as transforming growth factor-β 1 and the progressive accumulation of fibronectin in kidney of diabetic rats were attenuated by Wu-Ling-San. Not only the elevated levels of advanced glycation end products (AGEs) and mitochondrial thiobarbituric acid-reactive substance, but also the higher levels of N ɛ-(carboxymethyl)lysine and receptor for AGEs in kidney of diabetic rats were ameliorated by Wu-Ling-San. Conclusions : Wu-Ling-San posses an anti-diabetic property with plasma glucose lowering action accompanied with amelioration of glycation-mediated renal damage.

고려홍삼의 당뇨병성 신장병증 개선 효과

자연발생적 고혈압 흰쥐에 STZ로 당뇨를 유발한 고혈압-당뇨 질환모델에서 고려홍삼 조사포닌분획과 비사포닌 분획간의 신장보호 활성을 비교해 보았다. STA 65mg/kg용량을 투여한 후 3일에 네 그룹으로 나누어 본 실험에 임하였다. 신장비대에 대한 저해 활성을 비교해 보았을 때 GTS와 GNS 각각 12, 13% 억제 활성을 나타내었고 두 군간에는 유의적인 차이를 보이지 않았다. 한편 요 중 요소질소의 배설은 GNS 투여군에서는 69% 증가(p＜0.05)한 반면 GTS 투여군은 31%만이 증가하였다. 혈중 포도당, 콩 콜레스테롤 및 중성지방의 경우는 고혈압-당뇨 대조군과 비교시 홍삼투여군 두군 모두에서 유의한 차이를 발견할 수 없었다. 반면 oxidative stress를 저해하는 효소인 SOD 활성에 있어서는 GNS투여군에서 대조군에 비해 17%유의하게 상승하는 활성을 보여주었다. 신장비대의 지표인 TGG-<TEX>$\beta$</TEX>1, fibronectin그리고 upstream의 MEPK인 p-38, ERK 등의 발현을 그룹간 비교해 본 결과 모든 지표에서 비사포닌 분획이 사포닌 분획에 비해 우수한 억제활성을 나타내었다. TGF-<TEX>$\beta$</TEX>1의 mRNA 및 단백질의 발현을 살펴보았을 때 GNS 투여군은 각각 33%, 91% 억제활성을 나타낸 반면 GTS 투여군은 각각 5%, 65% 억제활성을 나타내었다. Fibronectin 단백질의 발현에서도 GNS 투여군은 87% 억제 활성을 나타낸 반면 GTS 투여군은 28% 저해활성을 나타내었다. 본 실험의 결과를 종합해보면 고려홍삼의 신장보호 활성은 사포닌 분획보다는 비사포닌 분획에 함유된 성분에 의해 일어나는 효과가 아닌가 추측된다. The renoprotective effects of Korean Red Ginseng were examined in STZ-induced diabetic spontaneously hypertensive rats (SHR). After 3 day administration of streptozotocin (STZ), animals were divided into four groups : Group 1, hypertensive rats (H); Group 2, hypertensive rats with diabetes (HD); Group 3, hypertensive rats with diabetes administered with 100 mg/kg of ginseng total saponin(GTS); Group 4, hypertensive rats with diabetes administered with 600 mg/kg of ginseng non-saponin (GNS). After 2 weeks oral administraions of GTS and GNS, body weight, kidney weight, plasma glucose, urinary albumin excretion, serum creatinine, urea nitrogen and blood pressure were examined. After 3,7 and 21 day of STZ administration, expressions of TGF-<TEX>${\beta}$</TEX>1 and fibronectin in kidney were analyzed by immunoblotting and/or immunohistochemistry. GTS and GNS treatments slightly decreased blood pressure when compared to H and HD groups. Also, GTS and GNS treatments ameliorated kidney hypertrophy without affecting plasma glucose levels. Meanwhile, GNS treatment increased Cu/Zn-SOD activity in kidney and generally showed more efficient renoprotective effects than GTS. We suggest that the renoprotective effects of ginseng partially result from downregulations of TGF-<TEX>${\beta}$</TEX>1, fibronectin expressions and anti-oxidative activity of ginseng non-saponin.

Cellular origin of fibronectin in interspecies hybrid kidneys.

The cellular origin of fibronectin in the kidney was studied in three experimental models. Immunohistochemical techniques that use cross-reacting or species-specific antibodies against mouse or chicken fibronectin were employed. In the first model studied, initially avascular mouse kidneys cultured on avian chorioallantoic membranes differentiate into epithelial kidney tubules and become vascularized by chorioallantoic vessels. Subsequently, hybrid glomeruli composed of mouse podocytes and avian endothelial-mesangial cells form. In immunohistochemical studies, cross-reacting antibodies to fibronectin stained vascular walls, tubular basement membranes, interstitium, and glomeruli of mouse kidney grafts. The species-specific antibodies reacting only with mouse fibronectin stained interstitial areas and tubular basement membranes, but showed no reaction with hybrid glomeruli and avian vascular walls. In contrast, species-specific antibodies against chicken fibronectin stained both the interstitial areas and the vascular walls as well as the endothelial-mesangial areas of the hybrid glomeruli, but did not stain the mouse-derived epithelial structures of the kidneys. In the second model, embryonic kidneys cultured under avascular conditions in vitro develop glomerular tufts, which are devoid of endothelial cells. These explants showed fluorescence staining for fibronectin only in tubular basement membranes and in interstitium. The avascular, purely epithelial glomerular bodies remained unstained. Finally, in outgrowths of separated embryonic glomeruli, the cross-reacting fibronectin antibodies revealed two populations of cells: one devoid of fibronectin and another expressing fibronectin in strong fibrillar and granular patterns. These results favor the idea that the main endogenous cellular sources for fibronectin in the embryonic kidney are the interstitial and vascular cells. All experiments presented here suggest that fibronectin is not synthesized by glomerular epithelial cells in vivo.