RESUMEN
Objective:To explore the level of tibial growth plate chondrocyte mitophagy in young rats with chronic renal failure (CRF) and its effect on chondrocyte apoptosis.Methods:Male 4-week-old Sprague-Dawley rats were randomly divided into two groups according to random number table method: normal control group ( n=20, intragastric administration with distilled water) and CRF group ( n=20, given adenine suspension 150 mg·kg -1·d -1). All the young rats were sacrificed after continuous gavage for 6 weeks. The length of tibia was measured on X ray film, the width of tibia growth plate was measured and compared on histological section, and the apoptosis rate of chondrocytes in growth plate was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay. The growth plate chondrocytes of two groups were isolated and cultured to the third generation in vitro, and the apoptosis rate of chondrocytes was detected by TUNEL assay. The co-localization of mitochondria and autophagy lysosomes in chondrocytes was observed by double fluorescence staining. Western blotting was used to detect the level of mitochondrial marker protein translocate of the outer mitochondrial membrane-20 (Tom-20) and autophagy marker light chain-3 protein (LC-3). The mitophagy of growth plate chondrocytes was observed by transmission electron microscope. Results:Compared with the normal control group, the tibia length of CRF group was shorter [(27.32±5.81) mm vs (35.43±3.61) mm, t=5.226, P<0.001], and the relative width of growth plate in histological section was narrower (0.56±0.19 vs 1.00±0.21, t=6.744, P<0.001). The apoptosis rate of chondrocytes in growth plate in CRF group was higher than that in the normal control group (17.2%±4.8% vs 5.1%±3.4%, t=6.505, P<0.001). The apoptosis rate of chondrocytes cultured in vitro in CRF group was higher than that in the normal control group (11.8%±6.2% vs 3.1%±1.2%, t=4.357, P<0.001). The result of double influorescence staining showed that there was co-localization between mitochondria and autophagy lysosomes in CRF group. Western blotting results showed that the levels of LC-3 protein ( t=8.944, P<0.001) and Tom-20 protein ( t=6.708, P<0.001) in CRF group were lower than those in the normal control group. Conclusion:The level of tibial growth plate chondrocyte mitophagy in young rats with CRF increases, which will lead to a decrease in the number of mitochondria, an increase in the apoptosis and a decrease in the number of chondrocytes, and eventually lead to dysplasia of tibia.
RESUMEN
Objective:To investigate the role and mechanism of Nod-like receptor protein 3 (NLRP3) in chronic kidney disease (CKD)-related neointimal hyperplasia (NH) of vessels.Methods:Wild type C57BL/6J male mice were randomly divided into normal control group ( n=6) and experimental group ( n=18), by removal of 5/6 kidney and ligation of left common carotid artery to establish a NH model. After established successfully, the mice in NH experimental group were randomly divided into NH model group, NLRP3 inhibitor group, and drug control group ( n=6/group). C57BL/6J male mice with NLRP3 gene knockout group did not do any treatment after the establishment of NH model. After 3 weeks of feeding, the blood and vascular tissue samples of mice were collected. The pathological changes of vascular tissue samples in mice were observed by hematoxylin-eosin staining. The expressions and localization of NLRP3-related protein were observed by immunofluorescence staining. The expression of NLRP3 mRNA in vascular tissue was detected by quantitative real-time PCR. The activity of caspase-1 in vascular tissue was measured by colorimetric method. Human aortic smooth muscle cells (HASMCs) were treated with 10% uremic serum to simulate the body's internal environment during the uremic phase. NLRP3 small interfering RNA (siRNA) was transfected or NLRP3 inhibitor glibenclamide was added to the cell cultures. The expression of NLRP3 mRNA in HASMCs was detected by quantitative real-time PCR. The activity of caspase-1 in HASMCs was detected by colorimetric method. Results:Compared with the control group, the levels of serum creatinine and blood urea nitrogen were significantly increased in the NH model group (both P<0.01). The vascular histopathology showed that vascular intima thickened, vascular smooth muscle cells proliferated and hypertrophied, nuclei were deeply stained, and cells arranged disorderly and migrated to vascular intima in the experimental group. Quantitative analysis showed that the ratio of neointima to lumen increased significantly in the NH model group than that in control group ( P<0.01). Compared with the control group, the immunofluorescence staining of vascular tissue showed that the expressions of NLRP3, caspase-1, IL-18, IL-1β and proliferating cell nuclear antigen (PCNA) protein in the NH model group increased (all P<0.01), while the expression of α-SMA decreased ( P<0.01). NLRP3 was mainly located in vascular smooth muscle cells (VSMCs). VSMCs showed a synthetic phenotype. Compared with the NH model group, the expression of NLRP3, caspase-1, IL-18, IL-1β and PCNA protein in the NLRP3 inhibitor group and NLRP3 gene knockout group decreased (all P<0.01), the expression of α-SMA increased ( P<0.01), and the pathological changes of blood vessels alleviated. Compared with healthy serum group, the expression of NLRP3, IL-18, and IL-1β and bromodeoxyuridine (BrdU) uptake in uremic serum-stimulated group were increased (all P<0.01). After transfection of NLRP3 siRNA and addition of glibenclamide, the expression of NLRP3, IL-18, and IL-1β in VSMCs in uremic serum-stimulated group decreased, and BrdU intake decreased (all P<0.01). Conclusions:NLRP3 inflammatory bodies play an important role in promoting CKD-related neointimal hyperplasia of vessels, and glibenclamide can effectively reduce neointimal hyperplasia.