ABSTRACT
Objective:To evaluate the effect of proprotein convertase subtilisin/kexin type 9 (PCSK9) on lipid homeostasis and cellular injury of podocytes, and to clarify its mechanism.Methods:Twelve-week old C57BL/6 wild-type mice ( n=10) and PCSK9 knockout ( PCSK9 KO) mice ( n=10) were selected as the animal models. The renal tissues were taken after perfusion through heart. Mouse podocytes were transfected with PCSK9 siRNA to downregulate PCSK9 expression. BODIPY 493/503 staining was performed for evaluating lipid accumulation, and standard transmission electron microscopy (TEM) was used to observe the foot process of podocytes, the shape of mitochondria and lipid droplet in podocytes. TUNEL staining was carried out to evaluate cell apoptosis in glomerulus. The parameters about mitochondria function (key enzymes such as PGC-1α, CPT-1 and Acox-1) and apoptosis were quantified through qPCR and western blotting. Results:The lipid accumulation in glomerulus of PCSK9 KO mice were more serious than controls. The expression of PGC-1α protein and PGC-1α, CPT-1 and Acox-1 mRNA in PCSK9 KO mouse kidney tissues were decreased than controls (all P<0.05), and mitochondria swelling and cristae disappearance in podocytes of PCSK9 KO mice were observed. In PCSK9 KO group, the foot process of podocytes partially fused and disappeared, and the apoptosis index increased compared with the control group ( P<0.05). In vitro, compared with the control group, the lipid accumulation was more significant, transcription level of key enzymes related to mitochondrial function was decreased, mitochondrial structure was damaged and the apoptosis index was increased in cultured podocyte PCSK9 siRNA group (all P<0.05). Conclusions:PCSK9 is involved in the lipid homeostasis of podocytes. The decrease of PCSK9 results in the increase of intracellular lipid accumulation, accompanied by the mitochondrial structure damage and disfunction of podocytes, and leads to cell apoptosis.
ABSTRACT
Objectives To evaluate the role of PCSK9 (proprotein convertase subtilisin kexin type 9) on the lipid accumulation and kidney injury of C57BL/6 mice. Methods The 24 h urine of 12 weeks old wide type C57BL/6 mice and PCSK9 knockout (KO) mice were collected through a metabolic cage, followed by perfusion and sacrifice. Urinary microalbumin?to?creatinine ratio (UACr), total cholesterol and triglyceride in kidney tissues were measured by ELISA. BODIPY 493/503 staining and standard transmission electron microscopy (TEM) of kidney tissues was performed for evaluating lipid accumulation and podocyte foot effacement in the kidney. Kidney tissues were also evaluated by PAS stain and TUNNEL stain. PCSK9, podocin and nephrin were quantified through real?time PCR, and the Bcl?2, Bax and cleaved caspase 3 were evaluated by Western blotting. Results Total cholesterol and triglyceride contents were higher in the kidneys of PCSK9 KO mice than controls (P<0.05). The level of lipid accumulation in glomeruli and tubules through BODIPY 493/503 stain, and the amount of lipid drop in TEM were more serious in PCSK9 KO mice. UACr and podocyte foot process effacement were increased, and the transcription of podocin and nephrin were decreased in the kidneys of PCSK9 KO mice (all P<0.05). The expression of Bcl?2 was decreased, and Bax and cleavedcaspase 3 were increased in the kidney samples of PCSK9 KO mice. Conclusion PCSK9 might be reversely involved in lipid homeostasis and accumulation, resulting in injury and apoptosis in the kidneys of C57BL/6 mice.
ABSTRACT
Objective To investigate the effects of 12-lipoxygenase (12-LO) and angiotensin Ⅱ (Ang Ⅱ) on the CIP/KIP family of cyclin-dependent kinase inhibitors (CKIs) p21,p27 and p57 related to cell hypertrophy.Methods Mesangial cells were treated with high glucose for 24 hours and 48 hours respectively.12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] and Ang Ⅱ were infused to rats by osmotic mini-pump for 1 week and 2 weeks respectively.Rats fed high fat diet were received low dose streptozotocin (STZ) to make type 2 diabetes (DN).The rats were divided into normal control group,DN group,DN+Ang Ⅱ type 1 receptor blocker (ARB) group or 12-LO inhibitor (CDC) group.DN+ARB rats were treated by losartan for 6 weeks,and DN+CDC rats were treated for 8 weeks.Urine albumin and protein expressions of p21,p27 and p57 were detected by ELISA and Western blotting respectively.Glomeruli injury and expressions of p21 and p27 were detected by PAS staining and immunohistochemistry respectively.Results High glucose increased p21 and p27 protein expression in mesangial cells significantly compared with the relative control (all P ＜ 0.05),but had no effect on p57.Ang Ⅱ increased p27 protein expression in gloneruli significantly (P ＜ 0.05),but had no effect on p21 and p57 protein expression.12(S)-HETE increased both p21 and p27 protein expression in glomeruli significantly (all P ＜ 0.05),but had no effect on p57 protein expression.Blood glucose,kidney/body weight,urinary protein,and glomerular p21 and p27 protein expressions were increased in DN group (all P ＜ 0.05) compared with those in control group,with little change of p57 protein expression (P ＜ 0.05).Moreover,glomerular hypertrophy and extra cellular matrix accumulation were observed in DN group.However,urine protein,kidney/body weight,renal injury,but not blood glucose,were decreased in DN+ARB group and DN+CDC group compared with DN group respectively (P＜ 0.05).Further DN+CDC rats had decreased both p21 and p27 protein expressions in glomeruli,but DN+ ARB rats only had decreased p27 protein expression (all P ＜ 0.05).Conclusions 12-LO may induce both p21 and p27 protein expression in DN glomeruli,but Ang Ⅱ may induce only p27 expression.
ABSTRACT
Objective To investigate the mechanism of chronic intermittent hypoxia (CIH)-induced renal injury and the protection of metallothionein (MT).Methods 8-10 weeks old male MT-1 transgenic (MT-TG) mice (n=12) and the wide type (WT) mice (n=12) were randomly divided into two groups respectively,Air mimic control(Ctrl) group (n=6) and CIH group (n=6).The period of chronic intermittent hypoxia was continued for 8 weeks.The CIH paradigm consisted of 20.9％ O2 and 8％ O2 fraction of inspiration O2 (FiO2) alternation cycles (30 episodes per hour) with 20 seconds at the nadir FiO2 for 12 hours/day during daylight.The nadir hemoglobin oxygen saturations mainly ranged from 60％ to 70％.Urine,blood,kidney were collected at the end of study respectively.Histopathology,Western blotting and colorimetric method for related target were performed respectively.Results In WT mice,renal fibrosis,the expression of connective tissue growth factor (CTGF),type-1 plasminogen activator inhibitor (PAI-1),hypoxia-inducible factor 1α (HIF-1α),transforming growth factor β1 (TGF-β1),phosphorylated Smad2 and the MDA content were significantly increased by CIH (P ＜ 0.01).In WT mice,the expression of MT detected by using Western blotting was significantly decreased by CIH (P ＜ 0.01).However,in MT-TG mice,above-mentioned indicators showed no significant difference between CIH and Ctrl group.Conclusions Oxidative stresses is the main mechanism of CIH-induced renal injury.The possible molecular mechanism of CIH-induced renal injury is that CIH increases the expression of HIF-1α in kidney tissue,then activate the TGF-β1-Smad2 signaling pathway and lead to the renal fibrosis.The protection of MT on CIH-induced renal injury may be via its antioxidant effect.
ABSTRACT
Objective To assess the efficacy and safety of lanthanum carbonate in treatment of hyperphosphatemia in end-stage renal disease (ESRD).Methods Randomized controlled trails of lanthanum carbonate in treatment of hyperphosphatemia in ESRD patients were searched in the database of MEDLINE,Cochrane Central Register of Controlled Trials,EMBASE,CNKI,Wanfang database.Data extracted from the literatures were analyzed with the Cochrane Collaboration's RevMan 5.1 software.Results Lanthanum carbonate group was similar with calcium carbonate group in treating hyperphosphatemia[RR =1.00,95 ％ CI (0.92-1.09),P =0.97],and more effective than placebo [RR=4.69,95％ CI (2.63-8.39),P＜ 0.01] (intervention dose≤ 1500 mg) and [RR =18.92,95％ CI (7.42-48.22),P ＜ 0.01] (intervention dose ＞ 1500 mg).In comparison with calcium carbonate group,the incidence of hypercalcinemia of lanthanum carbonate group was lower [RR =0.06,95 ％ CI (0.01-0.72),P =0.03],while the incidence of nausea [RR =1.80,95 ％ CI(0.70-4.64),P =0.22],vomiting [RR =3.94,95％ CI (0.45-34.38),P=0.22] and constipation [RR=0.82,95％ CI (0.49-1.37),P=0.45] were similar.The incidence of nausea and vomiting of lanthanum carbonate group were similar with placebo,with lower incidence of constipation [RR =0.19,95 ％ CI (0.06-0.59),P ＜ 0.01].Conclusions The efficacy of lanthanum carbonate in treating hyperphosphatemia is similar with calcium carbonate.The incidence of hypercalcinemia of lanthanum carbonate is lower than that of calcium carbonate,and the incidence of gastrointestinal adverse effect such as nausea,vomiting and constipation are similar with calcium carbonate.
ABSTRACT
Objective To investigate the effect of angiotensin Ⅱ (Ang Ⅱ) type 1 receptor blocker (ARB) on 12-lipoxygenase (12-LO) activity and P-cadherin expression in type 2 diabetic rat glomeruli.Methods Podocytes were stimulated by 107 mol/L Ang Ⅱ for 24 hours.12(S)-HETE (1mg· kg 1 · d-1) and Ang Ⅱ (400 ng· kg-1· min-1) were infused to rats by osmotic mini-pump for 1 week and 2 weeks respectively.Rats fed with high fat diet received low dose streptozotocin (STZ) to make type 2 diabetes and divided into 2 groups:low dose STZ (DN group),low dose STZ + ARB treatment (Losartan group).Rats fed with regular chow were used as control group.All the rats were sacrificed after 6 weeks.Urine,blood,kidney cortical tissue and isolated glomeruli by sieving method were collected at the end of study respectively.ELISA,RT-PCR and Western blotting for related target were performed respectively.Results Ang Ⅱ increased 12(S)-HETE levels in podocytes and glomeruli (all P ＜ 0.01).Ang Ⅱ levels in the glomeruli were significantly increased by 12(S)-HETE stimulation (P ＜0.01).Blood glucose,kidney/body weight and 24 hour urinary protein were increased in DN group compared with that in control group (all P ＜ 0.01).However,urine protein,Kidney/body weight were decreased in Losartan group compared with DN group (all P ＜ 0.05).Increment of 12(S)-HETE content and decrement of P-cadherin expression were observed in DN glomeruli compared with that in control group(all P ＜ 0.01).These abnormalities were prevented by administration of the losartan (all P ＜ 0.05).Conclusions Ang Ⅱ can down-regulate glomerular P-cadherin expression via activation of 12-LO.ARB can ameliorate the progression of DN via up-regulation of glomerular P-cadherin through inhibition of 12-LO activation in type 2 DN rats.
ABSTRACT
Objective:To investigate the effect of 12(S)-HETE on the p27~(kip1) expression in mesangial cells and glomeruli.Methods:Mesangial cells were exposed to 12(S)-HETE.12(S)-HETE was infused to rats by osmotic mini-pump.Total protein content measurement for cell hypertrophy,RT-PCR for mRNA expression and Western blot for protein expression were performed respectively.Results:12(S)-HETE stimulation induced mesangial cell hypertrophy and p27~(kip1) protein expression,but not p27~(kip1) mRNA expression.Furthermore,p27~(kip1) mRNA and protein expression in the glomeruli were significantly increased by 12(S)-HETE stimulation using osmotic mini-pump.Conclusion:12(S)-HETE plays an important role in the pathogenesis of glomerular cell hypertrophy and senescence through upregulation of p27~(kip1) expression.
ABSTRACT
Objective To investigate the effect of 12-lipoxygenase(12-LO) on the p27Kip1 expression in diabetic glomeruli. Methods Mesangial cells were exposed to 12-LO product 12 (S)-HETE (10-7 mmol/L) with or without p38 MAPK (p38) inhibitor (SB203580, 1 μmol/L) for 24 hours. Rats fed with high fat diet received low dose streptozotoein (ST-Z, 35 mg/kg, IP injection) to develop type 2 diabetes and were divided into 2 groups: low dose STZ, low dose STZ+12-LO inhibitor cinnamyl-3,4-dihydroxy-α-cynanocinnamate (CDC, 8 mg/kg) treatment. Rats fed with regular chow were divided into two groups: controls, CDC treatment. The rats received injection of CDC or vehicle subcutaneously in the hind leg. CDC or vehicle injection was performed three times weekly on alternate days. All the rats were sacrificed after 4 weeks, Wild type and 12-LO knockout C57BL/6 mice were divided into 4 groups: wild type control, 12-LO knockout, STZ-induced wild type type 1 diabetes and STZ-induced 12-LO knockout type 1 diabetes. All the mice were sacrificed after 16 weeks. Urine, blood, kidney cortical tissue and isolated glomeruli by sieving method were collected at the end of study respectively. Western blot and immunohistochemistry for target protein were performed respectively. Results Inhibition of p38 activation could significantly reduce p27Kip1 expression induced by 12 (S)-HETE in mesangial cells (P<0.01). Increased glomerular volume, microalbuminuria, elevated glomeluli p38 activation, p27Kip1 expresssion in type 2 diabetic glomeruli was decreased after CDC treatment (P<0.01). Compared with wild type diabetic mice, glomerular p38 activation, p27Kip1 exprcsssion and extracellular matrix accumulation in the 12-LO knockout diabetic mice were significantly decreased (P <0.01, respectively). Conclusions 12-LO induces p27kipl expression via p38 pathway in diabetic glomeruli.
ABSTRACT
Objective To observe therapeutic effect and safety of tacrolimus on idiopathic membranous nephropathy(IMN)with nephrotic syndrome in different courses of treatment.Methods Twenty patients with nephritic syndrome caused by idiopathic membranous nephropathy were divided into short-term(10 cases)and long-term(10 cases)groups randomly.Short-term group and long-term group were treated with tacrolimus and prednisone for 6 months and 24 months repectively,then obersve treatment effect,concentration changes of tacrolimus,recurrence and side effects in 2 groups.Results Five patients obtained complete remission after 6 months of treatment in the short-term group;4 patients obtained partial remission;1 patient had no response.Average concentration of tacrolimus remained 5～7 ?g/L in the period of treatment,and 6 cases recurred.Six patients obtained complete remission and 3 patients obtained partial remission after 24 months of treatment in the long-term group;1 patient had no response.Concentration of tacrolimus in the long-term group remained same as the short-term group at 5～8 ?g/L at 6 months,3.38～4.36 ?g/L at 12 months;no case recurred after treatment,the rate of which was significantly lower than the short-term group.Conclusion Short-term and long-term treatment of tacrolimus can relieve IMN evidently;low concentration of tacrolimus in the long-term group can alleviate the state of illness persistently with low recurrence rate.