Chemerin, a pro-inflammatory adipokine, regulates chondrocyte proliferation and metabolism by increasing production of nitric oxide / 中国组织工程研究

ABSTRACT

BACKGROUND: The key pathological characteristics of osteoarthritis are manifested in the degeneration of the cartilage caused by inflammation, and chondrocytes are the only cells in cartilage tissues. Studies have shown that Chemerin can stimulate the migration of leukocytes to the inflammation site and increase the inflammation signal of chondrocytes, suggesting that Chemerin can play a role in arthritis. Our previous research indicated that the serum Chemerin level in patients with osteoarthritis was significantly increased, and the Chemerin level in the synovial fluid was related to the severity of osteoarthritis based on the Kellgren-Lawrence classification. Chemerin may be used as an inflammatory factor in osteoarthritis. OBJECTIVE: To investigate the effect of Chemerin on the proliferation and metabolism of chondrocytes. METHODS: The chondrocytes from neonatal mice were isolated by collagenase type II digestion, and then cultured. Cell growth curves were established and the range of concentrations of Chemerin that exhibited toxicity to normal chondrocytes was screened using an MTT assay. Subsequently, 10 μg/L interleukin-1β was used to stimulate the chondrocytes in order to establish an in vitro model of osteoarthritis induction. After the chondrocytes had been cultured in the presence of the drug for 2 days, cell morphology, proliferation and metabolism were evaluated by hematoxylin-eosin staining and diacetate fluorescein/ propidium iodide staining. In addition, the expression of inducible nitric oxide polymerase was analyzed by measuring the secretion of nitric oxide. Furthermore, qRT-PCR was used to quantify mRNA expression of proteoglycan, type II collagen α1, matrix metalloprotease-13 and nitric oxide synthase 2. RESULTS AND CONCLUSION: The chondrocytes cultured in vitro exhibited healthy activity and morphology. Furthermore, chemerin (50 μg/L) and interleukin-1β (10 μg/L) were able to reduce the synthesis of extracellular matrix, enhance the secretion of nitric oxide and increase chondrocyte apoptosis. More importantly, the qRT-PCR results indicated that Chemerin and interleukin-1β caused similar effects, by which the expression of cartilage-specific genes was downregulated and catabolism-related genes upregulated. As a pro-inflammatory factor, Chemerin can increase the generation of nitric oxide in chondrocytes, regulate cell metabolism, stimulate cell apoptosis and act synergistically with interleukin-1β.