ABSTRACT
Renal fibrosis is a common pathological change from development to end-stage renal diseases in all progressive chronic kidney diseases. Renal fibrosis after kidney transplantation will severely affect the renal graft function. Macrophages are characterized with high heterogeneity and plasticity. During the process of kidney injury, macrophages are recruited, activated and polarized by local microenvironment, and participate in the process of renal tissue injury, repair and fibrosis through multiple mechanisms. Recent studies have shown that macrophages may transit into myofibroblasts and directly participate in the formation of renal fibrosis. This process is known as macrophage-myofibroblast transition. Nevertheless, the regulatory mechanism remains elusive. In this article, the role of macrophages in renal fibrosis, the characteristics of macrophage-myofibroblast transition and the possible regulatory mechanism were reviewed, aiming to provide reference for relevant research of renal fibrosis.
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Objective To investigate the role of hypoxia?inducible factor?2α(HIF?2α) in the expression of tight junction proteins and permeability alterations in rat glomerular endothelial cells (rGENCs) under hypoxia condition. Methods The expressions of the HIF?2α and tight junction proteins such as occludin and ZO?1 of rGENCs were examined after exposed to 5%oxygen at different treatment time periods (0 h, 12 h, 24 h and 48 h). Then lentiviral transfection was used to knock down HIF?2α expression in rGENCs. The cells were split into four groups, including i) control group where rGENCs were cultured under normal oxygen conditions, ii) hypoxia group, iii) negative control group where rGENCs were infected with a negative vector, iv) HIF?2α lentivirus transfection group. Group ii, iii and iv were kept in hypoxic chamber (5% O2, 5% CO2 and 90% N2) for 24 h. The expressions of occludin, ZO?1 and HIF?2α were assessed by Western blotting. The permeability of rGENCs was measured using trans?epithelium electrical resistant (TEER) by Millicell? ERS voltohmmeter. Results With the elongation of hypoxia time, the expression of HIF?2α was increased gradually, while the occludin expression was decreased, there was statistically significance difference in each group (all P0.05). And a dramatic decrease in TEER of hypoxia cells was detected as compare with control cells (P0.05). Conclusion Hypoxia may promote HIF?2α expression, which could increase the permeability of rGENCs by reducing the expression of occludin and ZO?1.
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Objective When the body is stimulated by hypoxia , the expression of heat shock protein 72 ( HSP72 ) is in-creased to produce anti-apoptosis effects .The aim of this paper is to study the effect of heat shock protein on apoptosis of cultured rat glomerulus endothelial cells ( GENC) under hypoxic environment . Methods Hypoxia was induced by cobalt chloride ( CoCl2 ) and GENC were divided into 5 groups ( normoxia group , hypoxia group , hypoxia+DMSO group , hypoxia+HSP72 inhibitor group , and hy-poxia+HSP72 agonist group ) according to the different intervention methods .The cell apoptosis was detected by flow cytometry and the expression of HSP72 was detected by Western blot . Results Compared with the normoxia group [(2.21 ±3.80)% and (0.23 ± 0.09)], the apoptosis rate and the expression of HSP72 were in-creased in the hypoxia group , hypoxia +DMSO group , hypoxia +HSP72 inhibitor group , and hypoxia +HSP72 agonist group [(24.54 ±3.59)% and (0.82 ±0.15), (29.25 ±1.63)% and (0.80 ±0.17), (36.07 ±1.19)%and (0.43 ±0.08), (18.10 ±2.59)%and (1.05 ±0.07)] (P0.05). Conclusion Hypoxia can induce the increased GENC apoptosis accompanied with the prolonged hypoxia .The increase or decrease of HSP 72 expression may lead to the decrease or increase of apoptosis , which is an important factor affecting the apoptosis of GENC under hypoxia .
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Objective To investigate the effect of advanced glycation end products (AGEs) on the disruption of tight junctions in rat glomerular endothelial cells (rGEnCs) and the role of renin-angiotensin system (RAS) in this pathological procedure.Methods Primary cultured rGEnCs were incubated with AGEs at concentrations of 20 mg/L,40 mg/L and 80 mg/L,for 6 h,12 h and 24 h respectively.The cells were treated with captopril (1 mmol/L) or valsartan (10 μ mol/L)to block RAS.The endothelial permeability was investigated by transendothelial electrical resistance and the flux of fluorescein isothiocyanate-conjugated bovine serum albumin.The expression of AGEs receptor (RAGE),tight junction proteins [occludin,claudin-5,junctional adhesion molecules A (JAM-A) and zona occludens-1 (ZO-1)]and RAS components [angiotensinogen,renin and angiotensin Ⅱ type 1 receptor (AT1)]were detected by Western blotting.Immunofluorescence was used to demonstrate the disruptions of the tight junction proteins.The activity of angiotensin converting enzyme (ACE) was evaluated by UV spectrophotometry.Angiotensin Ⅱ (Ang Ⅱ ) was measured by enzyme immunoassay.Results The monolayer permeability,the expression of RAGE,the activity of ACE,the concentration of Ang Ⅱ and the expression of AT1 of rGEnCs were increased after induced by AGEs.Meanwhile,AGEs decreased the expression of occludin,claudin5 and JAM-A and induced disruption of tight junction proteins.Pretreatment with anti-RAGE antibody (100 mg/L),captopril or valsartan could attenuate the detrimental effect of AGEs.Conclusion The changes of permeability induced by AGEs in glomerular endothelial cells are partly mediated by RAS through RAGE.
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Objective To investigate the change of aquaporin 2 (AQP2) mRNA and protein levels in renal collecting duct of SD rats after hypoxin caused by rising of the altitude to 4600 m. Methods Forty male SD rats were randomly divided into 4 groups (24 h, 48 h, 72 h and 1 week group), and 10 rats in Xining city were used as control group. All the 40 SD rats were transported to Kekexili Natural Reservation areas (4600 m) in Qinghai province. Rats of four experimental groups were sacrificed and renal tissue samples were harvested at different time point respectively, the control group rats were treated in Xining city (2260 m) as well. The concentration of plasma antidiuretic hormone (ADH) was measured by radioimmunity method. The expression of AQP2 mRNA and proteins was evaluated by real-time fluorescent quantitative-PCR, Western blot and immunofluorescence assay. Results The concentration of plasma ADH was decreased at 24 h and was only 28.5% of that of control group, reaching the lowest concentration at 48 h [(86.94±6.49) μg/L vs (302.5±310.48) μg/L], then it increased gradually and was similar to the control group at 7 d [(306.46±11.14) μg/L vs (302.53±10.48)μg/L, P＞ 0.05]. There were significant differences of the control group with 24 h, 48 h and 72 h groups, respectively[(302.53± 10.48) μg/L vs (142.46±10.57)μg/L, (86.94±6.49)μg/L, (169.65±11.15) μg/L respectively, P＜0.01]. The change of AQP2 gene expression level was consistent with the change of ADH. It was decreased at the begining when exposure to altitude and it reached its lowest level at 48 h. It was then returned to high level similarly to that of the control group at 7 d (0.09±0.01 vs 0.09± 0.008, P＞0.05 ). There were significant differences of the control group with 24 h, 48 h and 72 h group, respectively (0.09±0.008 vs 0.04±0.005, 0.03±0.002, 0.04±0.003 respectively, P＜0.01 ). Conclusions AQP2 expression in the renal collecting duct of SD rats is altered over the period exposed to altitude. It is decreased in the early hypoxia period, and is increased in later period. This change may be related to the intensity of hypoxia, which is mediated by a potential adaptation mechanisms against hypoxia caused by high altitude.