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Abnormal human chondrocyte morphology is related to increased levels of cell‐associated IL‐1β and disruption to pericellular collagen type VI
Author(s) -
Murray Dianne H.,
Bush Peter G.,
Brenkel Ivan J.,
Hall Andrew C.
Publication year - 2010
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.21155
Subject(s) - chondrocyte , chemistry , cartilage , osteoarthritis , type ii collagen , confocal , pathology , cytoplasm , confocal microscopy , cell type , cell , morphology (biology) , anatomy , microbiology and biotechnology , biology , medicine , biochemistry , genetics , alternative medicine , geometry , mathematics
Early osteoarthritis (OA) is poorly understood, but abnormal chondrocyte morphology might be important. We studied IL‐1β and pericellular collagen type VI in morphologically normal and abnormal chondrocytes. In situ chondrocytes within explants from nondegenerate (grade 0/1) areas of human tibial plateaus ( n = 21) were fluorescently labeled and visualized [2‐photon laser scanning microscopy (2PLSM)]. Normal chondrocytes exhibited a “smooth” membrane surface, whereas abnormal cells were defined as demonstrating ≥1 cytoplasmic process. Abnormal chondrocytes were further classified by number and average length of cytoplasmic processes/cell. IL‐1β or collagen type VI associated with single chondrocytes were visualized by fluorescence immuno‐histochemistry and confocal laser scanning microscopy (CLSM). Fluorescence was quantified as the number of positive voxels (i.e., 3D pixels with fluorescence above baseline)/cell. IL‐1β‐associated fluorescence increased between normal and all abnormal cells in the superficial (99.7 ± 29.8 [11 (72)] vs. 784 ± 382 [15 (132)]; p = 0.04, positive voxels/cell) and deep zones (66.5 ± 29.4 [9 (64)] vs. 795 ± 224 [9 (56)]; p = 0.006). There was a correlation ( r 2 = 0.988) between the number of processes/cell (0–5) and IL‐1β, and an increase particularly with short processes (≤5 µm; p = 0.022). Collagen type VI coverage and thickness decreased ( p < 0.001 and p = 0.005, respectively) with development of processes. Abnormal chondrocytes in macroscopically nondegenerate cartilage demonstrated a marked increase in IL‐1β and loss of pericellular type VI collagen, changes that could lead to cartilage degeneration. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1507–1514, 2010