Chatham W W, Swaim R, Frohsin H, Heck L W, Miller E J, Blackburn W D
Research Service, Department of Veterans Affairs, Birmingham, AL 35233.
Arthritis Rheum. 1993 Jan;36(1):51-8. doi: 10.1002/art.1780360109.
To determine whether surface-adherent immunoglobulins are capable of mediating synovial fluid (SF) neutrophil degradation of proteoglycan and collagen in intact, normal human articular cartilage, and to define the respective roles of neutrophil serine proteases and metalloproteases in degrading these cartilage constituents.
Pellet explants of normal human articular cartilage pretreated with bovine serum albumin (BSA) or IgG were incubated with polymorphonuclear cells suspended in SF (PMN-SF), or with supernatants derived from neutrophils stimulated with surface-associated IgG. Proteoglycan degradation was measured by assaying release of 35S-proteoglycan fragments from cartilage explants prelabeled with 35S-sulfate. Collagen degradation was measured by assaying hydroxyproline content in the PMN-SF preparations or neutrophil supernatants following their incubation with unlabeled explants.
Significant release of both 35S fragments and hydroxyproline was noted following incubation of PMN-SF with IgG-treated pellets, compared with pellets treated with BSA. IgG preparations derived from pooled normal serum or rheumatoid arthritis SF were equally efficacious in mediating PMN degradation of cartilage collagens. Explant release of 35S fragments during incubation with PMN supernatant was completely inhibited when serine proteases were inactivated by diisopropyl fluorophosphate (DFP); however, release of 35S fragments was enhanced when metalloprotease activity was present in the supernatant. Release of hydroxyproline during incubation of explants with PMN supernatant was comparable in the presence of DFP or EDTA, but was markedly enhanced when both serine and metalloprotease activity were present in the supernatant.
Neutrophils in SF are capable of degrading both proteoglycans and collagens in intact human articular cartilage. Degradation of these cartilage constituents is facilitated by immunoglobulins adherent to the cartilage surface and by the synergistic action of PMN serine and metalloproteases released during activation of neutrophils with surface-associated immunoglobulin.
确定表面黏附的免疫球蛋白是否能够介导完整的正常人关节软骨中滑液（SF）中性粒细胞对蛋白聚糖和胶原蛋白的降解，并明确中性粒细胞丝氨酸蛋白酶和金属蛋白酶在降解这些软骨成分中各自的作用。
用牛血清白蛋白（BSA）或免疫球蛋白G（IgG）预处理的正常人关节软骨颗粒外植体，与悬浮于滑液中的多形核细胞（PMN-SF），或与由表面相关IgG刺激的中性粒细胞上清液一起孵育。通过检测预先用35S-硫酸盐标记的软骨外植体中35S-蛋白聚糖片段的释放来测定蛋白聚糖的降解。通过检测PMN-SF制剂或中性粒细胞上清液与未标记外植体孵育后的羟脯氨酸含量来测定胶原蛋白的降解。
与用BSA处理的颗粒相比，PMN-SF与IgG处理的颗粒孵育后，35S片段和羟脯氨酸均有显著释放。来自混合正常血清或类风湿性关节炎滑液的IgG制剂在介导PMN对软骨胶原蛋白的降解方面同样有效。当丝氨酸蛋白酶被氟磷酸二异丙酯（DFP）灭活时，外植体在与PMN上清液孵育期间35S片段的释放完全受到抑制；然而，当上清液中存在金属蛋白酶活性时，35S片段的释放会增强。在外植体与PMN上清液孵育期间，羟脯氨酸的释放在存在DFP或乙二胺四乙酸（EDTA）时相当，但当上清液中同时存在丝氨酸和金属蛋白酶活性时，羟脯氨酸的释放会显著增强。
滑液中的中性粒细胞能够降解完整人关节软骨中的蛋白聚糖和胶原蛋白。这些软骨成分的降解是由附着在软骨表面的免疫球蛋白以及中性粒细胞与表面相关免疫球蛋白激活过程中释放的PMN丝氨酸和金属蛋白酶的协同作用所促进的。
