Kashin-Beck disease (KBD) is a chronic, endemic osteochondropathy principally occurring in children. We investigated apoptotic chondrocyte death and the expression of Bcl-2, Bax, Fas, and inducible nitric oxide synthase (iNOS) in articular cartilage from patients with KBD in order to determine the pathogenesis of chondronecrosis in KBD.
Samples of articular cartilage were divided into 2 groups: control children (15 samples from 15 cases), and children with KBD (15 samples from 15 cases). KBD patients were diagnosed according to "Pathological Criteria to Diagnose KBD in China." Chondrocyte apoptosis was detected by TUNEL staining, and Bcl-2, Bax, Fas, and iNOS-positive articular chondrocytes were stained by immunohistochemistry. Articular cartilage was classified in 3 zones, and positive findings were counted by light microscopy for cytoplasmic staining by polyclonal antibodies of Bcl-2, Bax, Fas, and iNOS and apoptotic chondrocytes by TUNEL.
The percentage of positive apoptotic chondrocytes stained by TUNEL in the middle zone of articular cartilage from the KBD patient group (33.60% +/- 2.71%) was higher than that of controls (1.33% +/- 0.41%; p < 0.01). The percentages of chondrocytes staining for Bcl-2, Bax, Fas, and iNOS in KBD patients were significantly higher than in controls (p < 0.01); the remarkable difference in Bcl-2, Bax, Fas, and iNOS expression among the upper, middle, and deep cartilage zones was also seen in KBD articular cartilage (p < 0.01); and staining for Bcl-2, Bax, Fas, and iNOS in KBD patients was prominent in the upper zone (41.93% +/- 12.26%, 45.60% +/- 15.78%, 53.60% +/- 16.49%, 45.47% +/- 14.02%, respectively) and the middle zone (14.93% +/- 3.50%, 13.87% +/- 4.32%, 23.27% +/- 4.83%, 21.67% +/- 6.82%) of articular cartilage.
The apoptotic chondrocytes and Bcl-2, Bax, Fas, and iNOS-positive chondrocytes were significantly more numerous in patients with KBD than in controls.