Regional differences in the rise in blood levels of antigenic keratan sulfate and hyaluronan after chymopapain induced knee joint injury.
OBJECTIVE
Results from several recent studies suggest that the levels of antigenic keratan sulfate (agKS) and hyaluronan (HA) in serum provide useful information about changes taking place in injured or diseased synovial joints. To improve our understanding of the significance of such changes, we investigated the points of entry of these molecules into the blood circulation and their subsequent clearance after experimentally induced injury to rabbit knee joint.


METHODS
Chymopapain was injected into knee joints of 8 young adult rabbits to induce aggrecan degradation in articular cartilage within the injected joint. Levels of agKS and HA in serum from various blood vessels were measured before and 5 h after the injury. The statistical significance of injury related changes and differences among the different vessels were evaluated.


RESULTS
After the injury, the level of agKS rose most significantly in the popliteal vein draining the injected knee joint and dropped rapidly by the time the blood reached the femoral vein. The level of agKS was similar, although lower, in other blood vessels but, in each case, it was significantly higher than before the injection. The level of HA showed a different pattern of changes after injection. While highest in the popliteal vein draining the injected knee, HA was markedly elevated in the cranial vena cava, close to the entry of lymph into the circulation, and was 50% lower in the hepatic than in the portal vein.


CONCLUSIONS
(1) Measurement of agKS and HA in a blood vessel draining or close to an injured/diseased knee joint may provide more specific information about degradative changes taking place in that joint than measurement of levels of these markers in other blood vessels; (2) some HA molecules but no measurable amounts of agKS enter the blood circulation via the lymphatic system: and (3) HA but not agKS is very rapidly cleared from the blood by the liver.
Rayan
V
V
Department of Anatomy, Rush Medical College at Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA.
Thonar
E J
EJ
Chen
L M
LM
Lenz
M E
ME
Williams
J M
JM
D000818:Animals; D002917:Chymopapain; D006820:Hyaluronic Acid / Q000097:blood*; D007632:Keratan Sulfate / Q000097:blood*; D007718:Knee Injuries / Q000097:blood* / Q000139:chemically induced; D008297:Male; D011817:Rabbits; D013582:Synovial Fluid / Q000187:drug effects / Q000378:metabolism
D006820:Hyaluronic Acid; D007632:Keratan Sulfate; D002917:Chymopapain