Inflammation accelerates lipid dysregulation mediated cardiac fibrosis through enhancing myocardial endothelial-to-mesenchymal transition / 中华心血管病杂志

<p><b>OBJECTIVE</b>Dyslipidemia and chronic inflammation are risk factors of cardiac fibrosis. This study was aimed to investigate their possible synergetic effects and underlying mechanisms on progression of cardiac fibrosis in apolipoprotein E knockout (ApoE -/-) mice.</p><p><b>METHODS</b>Twenty-four ApoE-/- mice were divided into normal chow diet (control), high fat diet (HFD group), and HFD plus subcutaneously injection of 10% casein (inflammation group) for 8 weeks. Lipid profile and serum amyloid A (SAA) were examined by clinical biochemical assays and Enzyme-Linked Immunosorbent Assay, respectively. Hematoxylin-eosin staining (HE) and Masson staining were used to evaluate the myocardial accumulation of lipid and collagen. Collagen I protein expression was detected by immunohistochemical staining. Endothelial-to-mesenchymal transition related protein expressions were determined by Western blot.</p><p><b>RESULTS</b>Serum SAA level was significantly higher in inflammation group [(127.42 ± 26.99) ng/ml] than in control [(15.40 ± 7.62) ng/ml] and HFD [(8.17 ± 0.72) ng/ml] group (all P < 0.01).However serum levels of triglyceride, total cholesterol, and low density lipoprotein (LDL) cholesterol were significantly higher in HFD group than in inflammation and control groups[TG (7.53 ± 2.05) mmol/L vs. (3.43 ± 0.79) mmol/L; TC (27.80 ± 3.99) mmol/L vs. (14.94 ± 1.92) mmol/L;LDL-C (11.56 ± 2.56) mmol/L vs. (9.46 ± 1.31) mmol/L, all P < 0.05) . Foam cell formation in cardiac vessels, myocardial collagen deposit, protein expressions of collagen I, CD31, and alpha-smooth muscle actin (α-SMA) were all significantly higher in inflammation group than in HFD group (all P < 0.05) suggesting that inflammation contributes to the phenotype endothelial-to-mesenchymal transition in heart.</p><p><b>CONCLUSION</b>Inflammation exacerbates dyslipidemia mediated cardiac fibrosis in ApoE-/- mice partly through enhancing myocardial endothelial-to-mesenchymal transition.</p>

Inhibition of integrin-linked kinase by angiotensin II receptor antagonist, irbesartan attenuates podocyte injury in diabetic rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Integrin-linked kinase (ILK) dysregulation is involved in the progression of diabetic nephropathy (DN). The aim of this study was to investigate the effects of angiotensin II receptor blocker (ARB), irbesartan, on ILK expression and podocyte injury in DN.</p><p><b>METHODS</b>DN was induced by the combined feeding of high-sucrose, high-fat diet and intra-peritoneal injection of low dose of streptozotocin (35 mg/kg) in spontaneously hypertensive rats. Diabetic rats were treated with irbesartan (50 mg×kg(-1)×d(-1)) by gavage for 8 weeks. The renal morphologic changes and podocyte injury were investigated by light and electron microscopy, and the ILK expression was evaluated by real-time RT-PCR and Western blotting analysis.</p><p><b>RESULTS</b>Diabetic rats exhibited with the similar clinical feature of type 2 DN. Morphologically, they were characterized by expansion of mesangial matrix, loss of podocyte and podocyte injury. Impressively, compared to controls, the ILK expression in diabetic rats were upregulated, which were positively correlated with both podocyte injury and albuminuria. Irbesartan significantly prevented ILK overexpression, along with the amelioration of podocyte injury and albuminuria.</p><p><b>CONCLUSIONS</b>ILK plays an important role in mediating podocyte injury in DN; irbesartan inhibits ILK upregulation and attenuates podocyte injury, which might offer a new insight into the role of ARB in preventing DN progression.</p>

Connective tissue growth factor is associated with the early renal hypertrophy in uninephrectomized diabetic rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Renal hypertrophy has been regarded as the early feature of diabetic nephropathy (DN), which may eventually lead to proteinuria and renal fibrosis. However, the exact mechanism of renal hypertrophy is still unclear. The aim of this study was to investigate the possible association of connective tissue growth factor (CTGF) with renal hypertrophy in uninephrectomized diabetic rats.</p><p><b>METHODS</b>Seventy-two Sprague-Dawley (SD) rats were randomly divided into two groups: control group (group C, n = 32) and diabetic nephropathy (group DN, n = 40). Each group was re-divided into 4 subgroups according to the experimental period. The rats were sacrificed at 1, 2, 4, and 8 weeks respectively after induction of diabetes. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) after rats had received uninephrectomy. Blood glucose (BG), body weight (BW), 24-h urinary albumin excretion (24hUalb), kidney weight (KW), KW/BW, glomerular tuft area (AG), glomerular tuft volume (VG), proximal tubular area (AT) at each time point, the width of glomerular basement membrane (GBM) and tubular basement membrane (TBM) at week 8 were measured when the rats were sacrificed. Renal expression of CTGF and p27kip1 were detected by immunohistochemical staining. The relationship between CTGF expression and increasing of VG and AT was analyzed.</p><p><b>RESULTS</b>There was a significant increase of 24hUalb, KW, and KW/BW from week 1 onward in diabetic rats compared to those in group C (P < 0.05, respectively), diabetic rats also had a significant increase of AG, VG, and AT from week 1 onward. It was also shown that diabetic rats had a thickening of GBM [(245.7 +/- 103.0) nm vs (121.8 +/- 19.1) nm, P < 0.01] and TBM [(767.7 +/- 331.1) nm vs (293.0 +/- 110.5) nm, P < 0.01] at week 8. There was a weak expression for CTGF and p27kip1 in normal glomeruli and tubuli, while a significant increasing expression of CTGF and p27kip1 was found in glomeruli and tubuli in diabetic kidney from week 1 onward (P < 0.05, respectively), and the extent of CTGF expression was positively correlated with AG (r = 0.92, P < 0.05), VG (r = 0.86, P < 0.05), AT (r = 0.94, P < 0.01) and positively correlated with the expression of p27kip1 (r = 0.96, P < 0.01).</p><p><b>CONCLUSION</b>The expression of CTGF increases in diabetic rat kidney at the early stage, which might be an important mediator of renal hypertrophy through arresting cell cycling.</p>

Effect of irbesartan on angiotensin II-induced hypertrophy of human proximal tubular cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Intrarenal activation of the renin angiotensin system (RAS) plays an important role in mediating renal fibrosis. Both angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II (AngII) receptor antagonists have been shown to exert a protective role against diabetic and non-diabetic nephropathy. However, the exact mechanism of how blocking local RAS prevents renal fibrosis is unclear. The present study was to investigate the influence of a new AngII receptor antagonist, irbesartan (Irb), on AngII-induced hypertrophy in human proximal tubular cell line (HK-2).</p><p><b>METHODS</b>The cell line, HK-2, was grown in Dulbeccos's Modified Eagle's Medium containing 10% heat-inactivated fetal calf serum. After rested in serum-free medium for 24 hours, the effects of Irb on AngII (10(-7) mol/L)-induced [(3)H]-leucine incorporation, total protein content (measured by the Coomassie brilliant blue G250 method), and change in cell size (determined by scanning electron microscopy) were observed. The influence of Irb on the cell cycle was analyzed by fluorescence activated cell sorter (FACS) flow cytometry.</p><p><b>RESULTS</b>AngII induced cell hypertrophy in a time and dose dependent manner. Stimulation of cells with AngII for 48 hours resulted in a increase in [(3)H]-leucine incorporation [0 hour: (5584 +/- 1016) cpm/10(5) cells vs 48 hours: (10741 +/- 802) cpm/10(5) cells, P < 0.05], which was significantly attenuated by treatment with Irb. AngII significantly increased the total protein content in HK-2 cells [control: (0.169 +/- 0.011) mg/10(5) cells vs AngII group: (0.202 +/- 0.010) mg/10(5) cells, P < 0.05], which was also markedly inhibited by cotreatment with Irb (P < 0.01). Scanning electron microscopy showed that AngII induced an increase in average physical cell size, which was significantly inhibited by Irb [control: (11.92 +/- 1.62) microm; AngII group: (20.63 +/- 3.83) micro m; AngII + Irb group: (13.59 +/- 3.15) micro m; P < 0.01 vs control, respectively]. Furthermore, flow cytometry revealed that AngII arrested cells in the G(0)-G(1) phase, which was significantly reversed by treatment with Irb [G(0)-G(1) cells in AngII group: (76.09 +/- 1.82)%, in AngII + Irb group: (67.00 +/- 2.52)%, P < 0.05].</p><p><b>CONCLUSION</b>Irb can inhibit AngII-induced hypertrophy in HK-2 cells.</p>