Cartilage destruction is partly induced by the internal proteolytic enzymes and apoptotic phenomenon of chondrocytes in relapsing polychondritis.
OBJECTIVE
We analyzed 9 cases by immunohistochemical studies in order to elucidate the mechanisms of cartilage destruction in relapsing polychondritis (RP), which often involves the external auricle and respiratory tract through immunological disorder.


METHODS
Cartilage tissues were obtained during surgical operations. Cell species in the granulation tissues, especially near the cartilage, were identified by cell-surface markers [CD3, CD4, CD8, CD20, CD45 (LCA), and CD68]. The proteolytic enzymes expressed in the cells in the perichondral granulation and in chondrocytes themselves were analyzed by immunohistochemical studies using anti-matrix metalloproteinase (MMP) -1, -3, -8, -9, and -13, and cathepsin D, K, L, and elastase antibodies. Apoptosis and nitric oxide (NO), an apoptosis-related factor, were also examined using ApopTag and antinitrotyrosine antibody, respectively.


RESULTS
Among cell species that infiltrated in perichondral granulation, LCA, CD68 (monocytes/macrophages), and CD4 cells were dominant in number; MMP-8, MMP-9, and elastase were expressed only in the perichondral granulation; whereas MMP-3 and cathepsin K and L were detected in both chondrocytes and granulations. Out of 9 cases examined, 6 revealed apoptotic cells in excess of 50% of chondrocytes. There was a strong correlation between the number of apoptotic cells and the number of MMP-3-positive (r = 0.83) and cathepsin K-positive cells (r = 0.92). Abundant NO-expressing cells were observed in the chondrocytes in degenerated cartilage, similar to apoptosis.


CONCLUSIONS
Cartilage destruction in polychondritis is induced not only by perichondral inflammation, but also by intrinsic factors expressed in chondrocytes themselves, including certain kinds of proteolytic enzymes and apoptosis.
Department of Pathology, School of Medicine, Iwate Medical University, Morioka, Iwate 020-8505, Japan.
Naohisa
N
Ouchi
Miwa
M
Uzuki
Akihisa
A
Kamataki
Yasuhiro
Y
Miura
Takashi
T
Sawai
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000502:physiology*; D002356:Cartilage / Q000166:cytology / Q000473:pathology*; D019902:Chondrocytes / Q000473:pathology*; D005260:Female; D006097:Granulation Tissue / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000378:metabolism*; D011081:Polychondritis, Relapsing / Q000201:enzymology* / Q000473:pathology* / Q000503:physiopathology
D010447:Peptide Hydrolases