Knee osteoarthritis (KOA) is a highly prevalent musculoskeletal disorder characterized by degeneration of cartilage and abnormal remodeling of subchondral bone (SCB). Teriparatide (PTH (1–34)) is an effective anabolic drug for osteoporosis (OP) and regulates osteoprotegerin (OPG)/receptor activator of nuclear factor ligand (RANKL)/RANK signaling, which also has a therapeutic effect on KOA by ameliorating cartilage degradation and inhibiting aberrant remodeling of SCB. However, the mechanisms of PTH (1–34) in treating KOA are still uncertain and remain to be explored. Therefore, we compared the effect of PTH (1–34) on the post-traumatic KOA mouse model to explore the potential therapeutic effect and mechanisms.
MethodsIn vivo study, eight-week-old male mice including wild-type (WT) (n = 54) and OPG−/− (n = 54) were investigated and compared. Post-traumatic KOA model was created by destabilization of medial meniscus (DMM). WT mice were randomly assigned into three groups: the sham group (WT-sham; n = 18), the DMM group (WT-DMM; n = 18), and the PTH (1–34)-treated group (WT-DMM + PTH (1–34); n = 18). Similarly, the OPG−/− mice were randomly allocated into three groups as well. The designed mice were executed at the 4th, 8th, and 12th weeks to evaluate KOA progression. To further explore the chondro-protective of PTH (1–34), the ATDC5 chondrocytes were stimulated with different concentrations of PTH (1–34) in vitro.
ResultsCompared with the WT-sham mice, significant wear of cartilage in terms of reduced cartilage thickness and glycosaminoglycan (GAG) loss was detected in the WT-DMM mice. PTH (1–34) exhibited cartilage-protective by alleviating wear, retaining the thickness and GAG contents. Moreover, the deterioration of the SCB was alleviated and the expression of PTH1R/OPG/RANKL/RANK were found to increase after PTH (1–34) treatment. Among the OPG−/− mice, the cartilage of the DMM mice displayed typical KOA change with higher OARSI score and thinner cartilage. The damage of the cartilage was alleviated but the abnormal remodeling of SCB didn't show any response to the PTH (1–34) treatment. Compared with the WT-DMM mice, the OPG−/−-DMM mice caught more aggressive KOA with thinner cartilage, sever cartilage damage, and more abnormal remodeling of SCB. Moreover, both the damaged cartilage from the WT-DMM mice and the OPG−/−-DMM mice were alleviated but only the deterioration of SCB in WT-DMM mice was alleviated after the administration of PTH (1–34). In vitro study, PTH (1–34) could promote the viability of chondrocytes, enhance the synthesis of extracellular matrix (ECM) (AGC, COLII, and SOX9) at the mRNA and protein level, but inhibit the secretion of inflammatory cytokines (TNF-α and IL-6).
ConclusionBoth wear of the cartilage was alleviated and aberrant remodeling of the SCB was inhibited in the WT mice, but only the cartilage-protective effect was observed in the OPG−/− mice. PTH (1–34) exhibited chondro-protective effect by decelerating cartilage degeneration in vivo as well as by promoting the proliferation and enhancing ECM synthesis of chondrocytes in vitro. The current investigation implied that the rescue of the disturbed SCB is dependent on the regulation of OPG while the chondro-protective effect is independent of modulation of OPG, which provides proof for the treatment of KOA.
The translational potential of this articleSystemic administration of PTH (1-34) could exert a therapeutic effect on both cartilage and SCB in different mechanisms to alleviate KOA progression, which might be a novel therapy for KOA.
KeywordsTeriparatide (PTH (1–34))
Knee osteoarthritis
Cartilage
Subchondral bone
Osteoprotegerin (OPG)
AbbreviationsOPG−/−osteoprotegerin-knockout
DMMdestabilization of medical meniscus
ARRIVEAnimal Research: Reporting of In Vivo Experiments
PCRpolymerase chain reaction
S.Isubcutaneous injection
HPLCHigh Performance Liquid Chromatography
Micro-CTmicrocomputer tomography
Tb.Thtrabecular thickness
BV/TVbone volume fraction
EDTAethylene diamine tetra acetic acid
SOFGSafranin O-fast green
OARSIOsteoarthritis Research Society International
PBSphosphate buffer solution
DMEMDulbecco's Modified Eagle's Medium
EdU5-ethynyl-2′-deoxyuridine
CLSMconfocal laser scanning microscope
GAPDHglyceraldehyde-3-phosphate dehydrogenase
TNF-αtumor necrosis factor-α
ELISAenzyme-linked immunosorbent assay
RT-qPCRquantitative reverse transcription polymerase chain reaction
NCBINational Center for Biotechnology Information
SOX9SRY-Box Transcription Factor 9
MMP13Matrix Metallopeptidase 13
ADAMTS5ADAM Metallopeptidase with Thrombospondin Type 1 Motif 5
ANOVAone-way analysis of variance
© 2022 Peking University Shenzhen Hospital. Published by Elsevier B.V. on behalf of Chinese Speaking Orthopaedic Society.
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