Hyaluronic acid inhibits nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes in vitro.
OBJECTIVE
Nitric oxide is an important mediator in Osteoarthritis (OA), and causes apoptosis and dedifferentiation in articular chondrocytes. Protein kinase Calpha is involved in modulating apoptosis and dedifferentiation of articular chondrocytes induced by nitric oxide. Hyaluronic acid is widely used in the treatment of osteoarthritis and exerts significant chondroprotective effects. The exact mechanisms of its chondroprotective action are not yet fully elucidated. The present study was performed to investigate the effects and mechanisms of hyaluronic acid in NO-induced apoptosis and dedifferentiation of chondrocytes.


METHODS
The ratio of apoptotic cell and cell viability was surveyed by TUNEL, MTT assay and flow cytometry. The expression of aggrecan, type II collagen, and PKCalpha were determined by real-time PCR and Western blot. The expression changes of caspase-3 and bcl-2 was detected by Western blot. The mitochondrial membrane potential (DeltaPsim) was evaluated by Rhodamine-123 fluorescence.


RESULTS
HA reduces the TUNEL positive cell, nuclei fragment and the impairment of DeltaPsim. NO-induced chondrocyte dedifferentiation was blocked by HA, which restores expression of aggrecan and type II collagen of chondrocytes and cell viability. HA can block inhibition of PKC-alpha by NO.


CONCLUSIONS
Our results show that HA blocks NO-induced apoptosis and dedifferentiation of articular chondrocytes by modulation of DeltaPsim and PKCalpha.
Peng
Hao
H
Department of Orthopedics, Renmin Hospital of Wuhan University, Hubei, People's Republic of China.
Zhou
Jian-lin
JL
Liu
Shi-qing
SQ
Hu
Qiong-jie
QJ
Ming
Jiang-hua
JH
Qiu
Bo
B
D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002358:Cartilage, Articular / Q000166:cytology*; D054337:Cell Dedifferentiation / Q000187:drug effects*; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D024043:Collagen Type II / Q000378:metabolism; D006820:Hyaluronic Acid / Q000494:pharmacology*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010003:Osteoarthritis / Q000276:immunology / Q000473:pathology / Q000503:physiopathology; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D053674:Aggrecans; D024043:Collagen Type II; D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009569:Nitric Oxide; D006820:Hyaluronic Acid; D051571:Protein Kinase C-alpha