YKL-39, a human cartilage-related protein, induces arthritis in mice

Clin Exp Rheumatol. 2002 May-Jun;20(3):343-50.


Objective: To determine whether YKL-39, a recently cloned secretory protein of articular chondrocytes, is arthritogenic in mice.

Methods: Recombinant YKL-39 (rYKL-39) was expressed and purified from E. coli. To induce arthritis in mice, rYKL-39 (1, 10 or 50 g in Freund's incomplete adjuvant) was injected into the right footpad of mice from four different strains (BALB/c, DBA/1J, C57BL/6 and ICR). The mice received a second immunization with rYKL-39 by intradermal injection into the root of the tail 10 days after the first immunization. Severity of arthritis was assessed by scoring each paw on a scale from 0 to 4. Sixty days after thefirst immunization, the mice were sacrificed and the joints were examined by immunohistochemistry and radiography. The anti-YKL-39 and anti type II-collagen (CII) antibody titres were also assayed using ELISA.

Results: Immunization with YKL-39 induced arthritis in all strains of mice tested, among which BALB/c was most susceptible. Histological examination showed synovial proliferation and irregularity of the cartilage surface in YKL-39-injected BALB/c mice. Moreover radiographic analysis revealed pathological changes in these mice. The YKL-39-immunised mice produced not only anti-YKL-39 antibody but also antibody against type II collagen, suggesting a spreading of autoimmunity after YKL-39.

Conclusions: YKL-39, a cartilage-related protein, is found to induce arthritis accompanied by pathologic changes in bone and cartilage. A better understanding of the immune response against cartilage-related components including YKL-39 may help to elucidate the pathological processes of arthritic disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipokines
  • Animals
  • Antibodies / blood
  • Antibody Specificity
  • Arthritis, Experimental / diagnostic imaging
  • Arthritis, Experimental / immunology*
  • Arthritis, Experimental / pathology
  • Cartilage
  • Cell Division / drug effects
  • Cell Division / immunology
  • Chitinase-3-Like Protein 1
  • Collagen Type II / immunology
  • Disease Models, Animal
  • Female
  • Gene Expression
  • Glycoproteins / genetics
  • Glycoproteins / immunology*
  • Glycoproteins / pharmacology
  • Humans
  • Injections, Intradermal
  • Lectins
  • Leukocytes, Mononuclear / cytology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Inbred DBA
  • Mice, Inbred ICR
  • Radiography
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Recombinant Proteins / pharmacology


  • Adipokines
  • Antibodies
  • CHI3L1 protein, human
  • Chitinase-3-Like Protein 1
  • Collagen Type II
  • Glycoproteins
  • Lectins
  • Recombinant Proteins