Promotion of the articular cartilage proteoglycan degradation by T-2 toxin and selenium protective effect.
OBJECTIVE
To identify the relationship between T-2 toxin and Kashin-Beck disease (KBD), the effects of T-2 toxin on aggrecan metabolism in human chondrocytes and cartilage were investigated in vitro.


METHODS
Chondrocytes were isolated from human articular cartilage and cultured in vitro. Hyaluronic acid (HA), soluble CD44 (sCD44), IL-1beta and TNF-alpha levels in supernatants were measured by enzyme-linked immunosorbent assay (ELISA). CD44 content in chondrocyte membrane was determined by flow cytometry (FCM). CD44, hyaluronic acid synthetase-2 (HAS-2) and aggrecanases mRNA levels in chondrocytes were determined using reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemical method was used to investigate expressions of BC-13, 3-B-3(-) and 2-B-6 epitopes in the cartilage reconstructed in vitro.


RESULTS
T-2 toxin inhibited CD44, HAS-2, and aggrecan mRNA expressions, but promoted aggrecanase-2 mRNA expression. Meanwhile, CD44 expression was found to be the lowest in the chondrocytes cultured with T-2 toxin and the highest in control plus selenium group. In addition, ELISA results indicated that there were higher sCD44, IL-1beta and TNF-alpha levels in T-2 toxin group. Similarly, higher HA levels were also observed in T-2 toxin group using radioimmunoprecipitation assay (RIPA). Furthermore, using monoclonal antibodies BC-13, 3-B-3 and 2-B-6, strong positive immunostaining was found in the reconstructed cartilage cultured with T-2 toxin, whereas no positive staining or very weak staining was observed in the cartilage cultured without T-2 toxin. Selenium could partly inhibit the effects of T-2 toxin above.


CONCLUSIONS
T-2 toxin could inhibit aggrecan synthesis, promote aggrecanases and pro-inflammatory cytokines production, and consequently induce aggrecan degradation in chondrocytes. These will perturb metabolism balance between aggrecan synthesis and degradation in cartilage, inducing aggrecan loss in the end, which may be the initiation of the cartilage degradation.
Li
Si-Yuan
SY
Institute of Endemic Diseases, College of Medicine, Xi'an Jiaotong University; Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Key Laboratory of Microelement and Endemic Disease, Xi'an 710061, China.
Cao
Jun-Ling
JL
Shi
Zhong-Li
ZL
Chen
Jing-Hong
JH
Zhang
Zeng-Tie
ZT
Hughes
Clare E
CE
Caterson
Bruce
B
D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D005434:Flow Cytometry; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000032:analysis; D011509:Proteoglycans / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012643:Selenium / Q000494:pharmacology*; D013605:T-2 Toxin / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D018960:Hyaluronan Receptors; D053583:Interleukin-1beta; D011509:Proteoglycans; D014409:Tumor Necrosis Factor-alpha; D004247:DNA; D012643:Selenium; D013605:T-2 Toxin