STUDY DESIGN: Experimental study on age-related changes in expression of tissue inhibitor of metalloproteinases-3 (TIMP-3) associated with transition from notochordal nucleus pulposus (NP) to fibrocartilaginous NP in rabbit intervertebral disc (IVD). OBJECTIVES: To identify roles of notochordal NP in extracellular matrix (ECM) metabolism of IVD. SUMMARY OF BACKGROUND DATA: One of most interesting properties of TIMP-3 is to inhibit aggrecanases in addition to matrix metalloproteinases. Balance of aggrecanase/TIMP-3 is critical to maintain homeostasis of ECM metabolism. METHODS: Four-week-old and 160-week-old male Japanese white rabbits were used. Age-related changes in IVDs were evaluated histologically using previously established grading system. Immunohistochemistry of TIMP-3 and semiquantitative reverse transcriptase-polymerase reaction (RT-PCR) of TIMP-3, a disintegrin and metalloproteinases with thrombospondin motifs (ADAMTS) 4, 5, and transforming growth factor-beta1 (TGF-beta1), were conducted. RESULTS: Semiquantitative assessment of histologic changes indicated that 4-week-old rabbit was equivalent to fetus to 2-year-old human and 160-week-old rabbit was equivalent to 11- to 30-year-old human, particularly 11- to 16-year-old, which corresponds to transition period from notochordal to fibrocartilaginous NP. Immunohistochemistry revealed that TIMP-3 was positive in 4-week-old rabbit only. Semiquantitative RT-PCR revealed that levels of expressions of TGF-beta1 and TIMP-3 mRNAs in 4-week-old were significantly higher than those in 160-week-old rabbits. There was no significant difference in expression of ADAMTS4 mRNA. ADAMTS5 mRNA was not detected or extremely low in both groups. Expression of TIMP-3 mRNA in NP was upregulated by TGF-beta1 but was not affected by IL-1beta. On the contrary, expression of ADAMTS4 mRNA was not upregulated by TGF-beta1 but was upregulated by IL-1beta. CONCLUSIONS: Levels of expression of TIMP-3 in notochordal NP were significantly lower in 160-week-old rabbits than those in 4-week-old rabbits. Decrease in expression of TIMP-3, possibly mediated in part by TGF-beta1, may cause imbalance of ADAMTS4/TIMP-3 ratio at transition period from notochordal to fibrocartilaginous NP.
STUDY DESIGN: Experimental study on age-related changes in expression of tissue inhibitor of metalloproteinases-3 (TIMP-3) associated with transition from notochordal nucleus pulposus (NP) to fibrocartilaginous NP in rabbit intervertebral disc (IVD). OBJECTIVES: To identify roles of notochordal NP in extracellular matrix (ECM) metabolism of IVD. SUMMARY OF BACKGROUND DATA: One of most interesting properties of TIMP-3 is to inhibit aggrecanases in addition to matrix metalloproteinases. Balance of aggrecanase/TIMP-3 is critical to maintain homeostasis of ECM metabolism. METHODS: Four-week-old and 160-week-old male Japanese white rabbits were used. Age-related changes in IVDs were evaluated histologically using previously established grading system. Immunohistochemistry of TIMP-3 and semiquantitative reverse transcriptase-polymerase reaction (RT-PCR) of TIMP-3, a disintegrin and metalloproteinases with thrombospondin motifs (ADAMTS) 4, 5, and transforming growth factor-beta1 (TGF-beta1), were conducted. RESULTS: Semiquantitative assessment of histologic changes indicated that 4-week-old rabbit was equivalent to fetus to 2-year-old human and 160-week-old rabbit was equivalent to 11- to 30-year-old human, particularly 11- to 16-year-old, which corresponds to transition period from notochordal to fibrocartilaginous NP. Immunohistochemistry revealed that TIMP-3 was positive in 4-week-old rabbit only. Semiquantitative RT-PCR revealed that levels of expressions of TGF-beta1 and TIMP-3 mRNAs in 4-week-old were significantly higher than those in 160-week-old rabbits. There was no significant difference in expression of ADAMTS4 mRNA. ADAMTS5 mRNA was not detected or extremely low in both groups. Expression of TIMP-3 mRNA in NP was upregulated by TGF-beta1 but was not affected by IL-1beta. On the contrary, expression of ADAMTS4 mRNA was not upregulated by TGF-beta1 but was upregulated by IL-1beta. CONCLUSIONS: Levels of expression of TIMP-3 in notochordal NP were significantly lower in 160-week-old rabbits than those in 4-week-old rabbits. Decrease in expression of TIMP-3, possibly mediated in part by TGF-beta1, may cause imbalance of ADAMTS4/TIMP-3 ratio at transition period from notochordal to fibrocartilaginous NP.
Authors: Christopher J Panebianco; Arpit Dave; Daniel Charytonowicz; Robert Sebra; James C Iatridis Journal: FASEB J Date: 2021-11 Impact factor: 5.834