Expression of caspase-1 in synovial membrane-like interface tissue around loosened hip prostheses.
Caspase-1 expression in synovial membrane-like interface tissue (SMLIT) around loosened hip prostheses and osteoarthritic synovial samples was studied. Caspase-1 mRNA was found in SMLIT and synovial tissue. There is no difference in the copy numbers of caspase-1 mRNA between these samples. Both precursor and active forms of caspase-1 proteins appeared in these samples, but the number of positive cells was higher in SMLIT than in synovial tissue. Double labeling revealed that most caspase-1-positive cells were macrophages and fibroblasts. In the lining-like layers and deep stroma of SMLIT, many cells were double positive for active caspase-1 and interleukin-1 beta (IL-1beta). In contrast, the number of active caspase-1/IL-18 double-positive cells was very low. We conclude that caspase-1 synthesis is increased in SMLIT. Caspase-1 can be involved in implant loosening by processing IL-1beta precursor into its mature form, which is a potent osteoclast-activating factor and a major proinflammatory mediator.
ORTON Research Institute, the Orthopaedic Hospital of the Invalid Foundation, Helsinki, Finland.
T F
TF
Li
J
J
Mandelin
M V J
MV
Hukkanen
M
M
Liljeström
S
S
Santavirta
J
J
Westerlund
T
T
Paavilainen
Y T
YT
Konttinen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D015153:Blotting, Western; D020170:Caspase 1 / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D018628:Gene Dosage; D006622:Hip Prosthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007375:Interleukin-1 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications; D011475:Prosthesis Failure; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000201:enzymology*
D007375:Interleukin-1; D012333:RNA, Messenger; D020170:Caspase 1