ABSTRACT
OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation on the levels of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) protein in the lumbar intervertebral disc tissue and serum in prolapsed lumbar intervertebral disc degeneration (PLIDD) rats, so as to explore its mechanism underlying improvement of intervertebral disc degeneration (IDD). METHODS: A total of 48 Sprague-Dawley rats were divided into sham operation (n＝12), model (n＝18) and EA (n＝18) groups. The PLIDD model was established by puncturing the lumbar discs (L4-L5, L5-L6) with a gauge-22 syringe needle. After modeling, EA stimulation was applied to "Pangguangshu"(BL28), "Zusanli"(ST36) and "Zhijian"for 20 min, 6 times per week for 4 weeks. The lumbar intervertebral disc tissue and blood samples were collected at the 4th, 6th and 8th week after modeling, respectively. The expression of ADAMTS-4 in the lumbar intervertebral disc tissue was detected by immunohistochemistry and Western blot (WB), separately. The content of ADAMTS-4 in the serum was detected by ELISA. RESULTS: Both immunohistochemical stain and WB showed that the expression levels of lumbar ADAMTS-4 at the 4th, 6th and 8th week were significantly up-regulated in the model group relevant to the sham operation group (P<0.01). Following EA treatment, the expression levels of ADAMTS-4 on day 14 and 28 were notably lower in the EA group than in the model group (P<0.05). The serum ADAMTS-4 contents were significantly increased in the model group than in the sham operation group at the 3 time-points (P<0.05, P<0.01), and considerably decreased in the EA group than in the model group on day 28 after EA intervention(P<0.05)．. CONCLUSION: EA can down-regulate the ADAMTS-4 expression of lumbar intervertebral disc tissue in PLIDD rats, which may contribute to its effect in relieving lumbar intervertebral disc degeneration.
ABSTRACT
Intervertebral disc degeneration (IVDD) is characterized by the excessive degradation of extracellular matrix (ECM), which underlies many spine-related disorders. Matrix metalloproteinases (MMPs) and a disintegrin metalloproteinases with thrombospondin motifs (ADAMTSs) are believed to be the major proteolytic enzymes responsible for ECM degradation. This review summarizes the current literatures on gene expression and regulation of MMPs, ADAMTSs, and tissue inhibitors of metalloproteinases (TIMPs) in IVDD. Reports have showen that specific MMPs (MMP-1, -2, -3, -7, -8, -10, and -13) and ADAMTS (ADAMTS-1, -4, and -15) are upregulated in human degenerated intervertebral discs. Tissue inhibitor of metalloproteinase-3 is downregulated and TIMP-1 is upregulated in human degenerated intervertebral discs relative to nondegenerated intervertebral discs. Regulation of the MMP and ADAMTS expression is affected by many factors including mechanical, inflammatory, oxidative stress, and so on. Genetic predisposition also plays an important role in expression of MMP-1, -2, -3, and -9. Upregulation of MMP and ADAMTS expression is implicated in ECM destruction, which can lead to the development of IVDD. Future IVDD therapeutics may target specific MMPs and ADAMTSs which is essential in the pathological proteolysis of ECM.
ABSTRACT
Objective To observe the inhibiting activities of fibronectin (FN) and citrullinated fibronectin (cFN) on disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4),and to explore the extracellular regulative mechanisms of ADAMTS-4.Methods FN was incubated with peptidylarginine deaminase type 4 (PADI4).Western blotting analysis was used to verify the citrullination of FN.The binding activity of FN and cFN to ADAMTS-4 were investigated by enzyme-linked immunosorbent assay (ELISA).The proteolytic ability of ADAMTS-4 after binding to FN and cFN were measured with the aggrecanase activity assay kit.One-way ANOVA,LSD-t test and t-test were used for statistical analysis.Results The immunosignal of citrulline was detected in FN after incubated with PADI4,but not in the absence of PADI4.A higher absorbance at 405 nm was detected when the full-length ADAMTS-4 protein was incubated with FN (2.182±0.042) than cFN (0.624±0.033; t=50.522,P＜0.01).Additionally,the recombinant ADAMTS-4 protein with a truncation at the C-terminus displayed low absorbance at 405 nm when the enzyme was incubated with both FN(0.971±0.024) and cFN(0.934±0.012; t=2.388,P＞0.05).Large amounts of ARGxx peptide were detected with full-length ADAMTS-4 in aggrecanase activity assay [(0.908±0.088) nmol/L],but significantly less when in the presence of FN and ADAMTS-4 [(0.573±0.000) nmol/L,P＜0.05].The production of this peptide was more when full-length ADAMTS-4 was incubated with cFN [(0.830±0.020) nmol/L,P＜0.05] than with FN.The reaction containing the truncated ADAMTS-4 without FN or cFN yielded the highest concentration of ARGxx peptide [(36.420±3.673) nmol/L],peptide production was not significantly altered when FN [(41.099±0.101) nmol/L] or eFN [(41.064±0.083) nmol/L] were added to the reaction.Conclusion FN could bind to ADAMTS-4 and inhibit its proteolytic activity.After citrullinated by PADI4,the binding activity of cFN is weakened and less inhibition to ADAMTS-4.