CCN2 suppresses catabolic effects of interleukin-1β through α5β1 and αVβ3 integrins in nucleus pulposus cells: implications in intervertebral disc degeneration.
The objective of the study was to examine the regulation of CCN2 by inflammatory cytokines, IL-1β, and TNF-α and to determine whether CCN2 modulates IL-1β-dependent catabolic gene expression in nucleus pulposus (NP) cells. IL-1β and TNF-α suppress CCN2 mRNA and protein expression in an NF-κB-dependent but MAPK-independent manner. The conserved κB sites located at -93/-86 and -546/-537 bp in the CCN2 promoter mediated this suppression. On the other hand, treatment of NP cells with IL-1β in combination with CCN2 suppressed the inductive effect of IL-1β on catabolic genes, including MMP-3, ADAMTS-5, syndecan 4, and prolyl hydroxylase 3. Likewise, silencing of CCN2 in human NP cells resulted in elevated basal expression of several catabolic genes and inflammatory cytokines like IL-6, IL-4, and IL-12 as measured by gene expression and cytokine protein array, respectively. Interestingly, the suppressive effect of CCN2 on IL-1β was independent of modulation of NF-κB signaling. Using disintegrins, echistatin, and VLO4, peptide inhibitors to αvβ3 and α5β1 integrins, we showed that CCN2 binding to both integrins was required for the inhibition of IL-1β-induced catabolic gene expression. It is noteworthy that analysis of human tissues showed a trend of altered expression of these integrins during degeneration. Taken together, these results suggest that CCN2 and inflammatory cytokines form a functional negative feedback loop in NP cells that may be important in the pathogenesis of disc disease.
From the Department of Orthopaedic Surgery and Graduate Program in Cell and Developmental Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Cassie M
CM
Tran
Zachary R
ZR
Schoepflin
Dessislava Z
DZ
Markova
Christopher K
CK
Kepler
D Greg
DG
Anderson
Irving M
IM
Shapiro
Makarand V
MV
Risbud
D000818:Animals; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D057809:HEK293 Cells; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism*; D055959:Intervertebral Disc Degeneration / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
C526317:CCN2 protein, human; D039081:Integrin alpha5beta1; D039302:Integrin alphaVbeta3; D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D055513:Connective Tissue Growth Factor
Cartilage Biology; Chondrocytes; Cytokine; Extracellular Matrix Proteins; Integrins