ABSTRACT
Objective:To investigate the impact of matrix metalloproteinase 13 (MMP13) and low-density lipoprotein receptor-related protein 1 (LRP1) on autophagy of articular chondrocytes in patients with Kashin-Beck disease (KBD).Methods:Human articular cartilage samples obtained from 4 KBD patients and 4 control subjects were collected from Shaanxi Institute for Endemic Disease Prevention and Control, and the expression levels of MMP13 and LRP1 in cartilage tissue were determined using immunohistochemistry (IHC). Chondrocytes were extracted and cultured in vitro, the mRNA and protein expression levels of LRP1 and the autophagy related genes [Beclin 1 (BECN1), microtubule associated protein 1 light chain 3 (LC3)], cartilage injury related genes [MMP13, caspase-3 (CASP3)], chondrocyte differentiation related genes [collagen type Ⅱ alpha 1 chain (COL2A1), and SRY-box transcription factor 9 (SOX9)] were detected by real-time fluorescence quantitative PCR (qRT-PCR) and Western blot (WB), respectively. Chondrocytes from 3 KBD patients were extracted, and MMP13 gene silencing experiment was performed by RNA interference (RNAi) technology, the mRNA and protein expression levels of the above genes were detected by qRT-PCR and WB, respectively. In addition, the antagonist receptor associated protein (RAP) of LRP1 was used to block the LRP1 of human normal chondrocytes (C28/I2 cells), and qRT-PCR and WB were used to detect the mRNA and protein expression levels of LRP1, chondrocyte autophagy, differentiation and cartilage injury related genes, respectively. Results:The IHC results showed that the expression levels of MMP13 (1.67 ± 0.21, 0.59 ± 0.15, 0.51 ± 0.12) in the surface, middle, and deep layers of cartilage tissue of KBD patients were significantly higher than those of control subjects (0.25 ± 0.03, 0.26 ± 0.04, 0.06 ± 0.01), and the differences were statistically significant ( t = - 11.38, P < 0.001; t = - 3.82, - 6.26, P = 0.019, 0.003). The expression levels of LRP1 (0.10 ± 0.02, 0.03 ± 0.01, 0.17 ± 0.03) were significantly lower than those of control subjects (1.63 ± 0.40, 0.44 ± 0.12, 0.34 ± 0.08), and the differences were statistically significant ( t = 6.61, 5.61, 3.64, P = 0.003, 0.005, 0.022). The mRNA and protein expression levels of MMP13, CASP3, SOX9 in chondrocytes of KBD patients were significantly higher than those of control subjects, and the differences were statistically significant ( P < 0.05). The mRNA expression levels of LRP1, LC3, COL2A1 were significantly lower than those of control subjects, and the differences were statistically significant ( P < 0.05). After silencing the MMP13 gene in chondrocytes of KBD patients, there were no significant differences in the mRNA and protein expression levels of LRP1, BECN1, LC3, CASP3, COL2A1, and SOX9 ( P > 0.05). After blocking LRP1 with RAP, the protein expression levels of LRP1, BECN1, LC3, MMP13, COL2A1 and SOX9 in chondrocytes were significantly lower than those in control group ( P < 0.05). Conclusions:There is no direct correlation between MMP13 and abnormal autophagy of articular chondrocytes in KBD patients. After blocking LRP1, the expression of the autophagy related genes BECN1 and LC3 in chondrocytes is decreased.
ABSTRACT
Objective:To investigate the role of a disintegrin and metalloprotease 12 (ADAM12) gene in chondrocyte injury in patients with Kashin-Beck disease (KBD) and its impact on genes related to insulin-like growth factor binding protein (IGFBP).Methods:Articular cartilage samples were obtained from 5 patients with KBD and 5 control subjects admitted to Honghui Hospital Affiliated to Xi'an Jiaotong University. Chondrocytes were extracted and cultured in vitro. Quantitative real-time PCR (qRT-PCR) and Western blotting were used to detect the expression levels of ADAM12 mRNA and protein in chondrocytes of patients with KBD and control subjects, respectively. Subsequently, ADAM12 gene overexpression was performed using lentivirus in chondrocytes of patients with KBD. MTT assay was used to detect changes in cell viability after ADAM12 gene overexpression, and qRT-PCR was used to detect the mRNA expression levels of chondrocyte differentiation related genes SRY-box transcription factor 9 (SOX9) and type Ⅱ collagen (COLⅡ), apoptosis-related gene B-cell lymphoma/leukaemia-2-associated X protein (BAX), and anabolic related genes IGFBP3 and IGFBP5. Results:The expression levels of ADAM12 mRNA and protein in chondrocytes of patients with KBD (0.57 ± 0.05, 0.81 ± 0.07) were significantly lower than those of control subjects (1.00 ± 0.00, 1.00 ± 0.00), and the differences were statistically significant ( t = - 24.50, - 3.61, P < 0.05). The results of MTT assay showed that the cell viability of chondrocytes in ADAM12 overexpression group (1.09 ± 0.05) was higher than that in empty vector control group (1.00 ± 0.08), and the difference was statistically significant ( t = 4.12, P = 0.031). The results of qRT-PCR showed that compared with empty vector control group, the mRNA expression levels of IGFBP3 (2.35 ± 0.79 vs 0.96 ± 0.25), IGFBP5 (2.13 ± 0.30 vs 0.98 ± 0.34), SOX9 (2.92 ± 0.51 vs 0.94 ± 0.36) and COLⅡ (6.45 ± 2.81 vs 0.87 ± 0.19) in ADAM12 overexpression group were significantly increased, and the differences were statistically significant ( t = 3.19, 5.16, 6.27, 4.10, P < 0.05); while the expression level of BAX mRNA (0.31 ± 0.06 vs 1.02 ± 0.22) was significantly decreased, and the difference was statistically significant ( t = - 11.16, P < 0.001). Conclusion:The ADAM12 gene may have a role in inhibiting apoptosis and promoting differentiation in chondrocyte injury in patients with KBD, and its overexpression can increase expression of IGFBP3 and IGFBP5.
ABSTRACT
Objective:To explore if there is premature senescence of chondrocytes in patients with Kashin-Beck disease (KBD) and osteoarthritis.Methods:Five knee cartilage samples of KBD, osteoarthritis and control groups were collected, respectively, from the Second Affiliated Hospital of Xi'an Jiaotong University. DNA was then extracted from cartilage samples and DNA methylation was analyzed by Illumina Infinium HumanMethylation450 BeadChip. At the same time, based on genome-wide methylation data, the online DNA methylation aging clock calculator (https://dnamage.genetics.ucla.edu/home) was used to calculate the DNA methylation age (DNAm age) of samples, and the results were compared with their actual ages.Results:In the comparison between KBD group and control group, 1 212 differentially methylated CpG sites were found, including 497 hypermethylated CpG sites and 715 hypomethylated CpG sites, corresponding to 264 hypermethylated genes and 368 hypomethylated genes, respectively. In the comparison between osteoarthritis group and control group, 656 differentially methylated CpG sites were found, including 343 hypermethylated CpG sites and 313 hypomethylated CpG sites, corresponding to 177 hypermethylated genes and 174 hypomethylated genes, respectively. In the above comparison, 367 overlapped CpG sites (corresponding to 182 genes) were found, which were differentially methylated in both KBD and control groups and osteoarthritis and control groups. The results of DNA methylation aging clock showed that the average age acceleration differences between DNAm age and actual age of KBD, osteoarthritis and control groups were 2.549, 0.017, and - 5.364 years, respectively, the DNAm ages of KBD and osteoarthritis groups were greater than the actual ages.Conclusion:The chondrocytes show premature senescence in both KBD and osteoarthritis.