Cartilage intermediate layer protein 1 precursor (CILP-1) (Cartilage intermediate-layer protein) [Contains: Cartilage intermediate layer protein 1 C1; Cartilage intermediate layer protein 1 C2] [UNQ602/PRO1188]


Fibrotic-like changes in degenerate human intervertebral discs revealed by quantitative proteomic analysis.

Intervertebral disc degeneration (IDD) can lead to symptomatic conditions including sciatica and back pain. The purpose of this study is to understand the extracellular matrix (ECM) changes in disc biology through comparative proteomic analysis of degenerated and non-degenerated human intervertebral disc (IVD) tissues of different ages. Seven non-degenerated (11-46 years of age) and seven degenerated (16-53 years of age) annulus fibrosus (AF) and nucleus pulposus (NP) samples were used. Proteins were extracted using guanidine hydrochloride, separated from large proteoglycans (PGs) by caesium chloride (CsCl) density gradient ultracentrifugation, and identified using liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS). For quantitative comparison, proteins were labeled with iTRAQ reagents. Collagen fibrils in the NP were assessed using scanning electron microscopy (SEM). In the AF, quantitative analysis revealed increased levels of HTRA1, COMP and CILP in degeneration when compared with samples from older individuals. Fibronectin showed increment with age and degeneration. In the NP, more CILP and CILP2 were present in degenerated samples of younger individuals. Reduced protein solubility was observed in degenerated and older non-degenerated samples correlated with an accumulation of type I collagen in the insoluble fibers. Characterization of collagen fibrils in the NP revealed smaller mean fibril diameters and decreased porosity in the degenerated samples. Our study identified distinct matrix changes associated with aging and degeneration in the intervertebral discs (IVDs). The nature of the ECM changes, together with observed decreased in solubility and changes in fibril diameter is consistent with a fibrotic-like environment.

MeSH Terms

  • Adolescent
  • Adult
  • Aging
  • Child
  • Collagen
  • Fibrosis
  • Humans
  • Intervertebral Disc
  • Intervertebral Disc Degeneration
  • Microscopy, Electron, Scanning
  • Middle Aged
  • Nucleus Pulposus
  • Proteins
  • Proteomics
  • Solubility
  • Young Adult


  • Disc degeneration
  • Fibrosis
  • Intervertebral disc
  • Mass spectrometry
  • Proteome
  • Quantitative method

A novel cartilage protein (CILP) present in the mid-zone of human articular cartilage increases with age.

A novel, somewhat basic noncollagenous protein was purified from guanidine hydrochloride extracts of human articular cartilage using cesium chloride density gradient centrifugation, followed by ion-exchange chromatography at pH 5, and gel filtration on two serially coupled columns of Superose 6 and Superdex 200. The protein of 91.5 kDa contains a single polypeptide chain substituted with N-linked oligosaccharides. It appeared unique to cartilage as studied by enzyme-linked immunosorbent assay and immunoblots of various tissue extracts. Its concentration in articular cartilages showed some variability with age being lower in young individuals. It represents a chondrocyte product, since it is synthesized by articular chondrocytes in explant cultures. Interestingly, the distribution of the protein in the articular cartilage provides important information on the nature of chondrocytes at different compartments in the tissue. Thus, chondrocytes in the middle/deeper layers of the tissue in particular, appeared to have produced the protein and deposited it in the interterritorial matrix. The protein was neither seen in the superficial nor in the deepest regions of the articular cartilage. Based on its immunolocalization we have named this protein CILP (cartilage intermediate layer protein).

MeSH Terms

  • Adolescent
  • Adult
  • Aged
  • Aging
  • Amidohydrolases
  • Antibody Specificity
  • Cartilage, Articular
  • Child
  • Chondrocytes
  • Chromatography
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme-Linked Immunosorbent Assay
  • Extracellular Matrix Proteins
  • Femur
  • Glycoproteins
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Osteoarthritis
  • Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase
  • Precipitin Tests
  • Pyrophosphatases
  • Tissue Distribution