Kumon Y, Suehiro T, Hashimoto K, Nakatani K, Sipe J D
2nd Department of Internal Medicine, Kochi Medical School, Japan.
J Rheumatol. 1999 Apr;26(4):785-90.
Serum amyloid A (SAA) protein, a bioactive protein produced during inflammation, is present in synovial fluid (SF) of patients with rheumatoid arthritis (RA). Based on our recent finding that SF SAA concentration exceeded the serum counterpart in some patients with RA, we examined the local steady state concentration of SAA mRNA isoforms in synovia and in synovial cells cultured from patients with RA and osteoarthritis (OA).
Total cellular RNA from synovial membranes of patients with RA or OA and from cultured synovial cells of patients with RA was analyzed by reverse transcription polymerase chain reaction and Northern blot.
Acute phase SAA (A-SAA) mRNA isoforms were detected only in RA synovia, but not in OA synovia; however, the constitutive SAA (C-SAA) mRNA isoform was detected in similar abundance in both OA and RA synovia. There was evidence of C-SAA, but not A-SAA mRNA in cultured synovial cells at quiescence. After stimulation with both 1 mM dexamethasone and 10 ng/ml interleukin 1beta (IL-1beta), the quantity of steady state A-SAA muRNA in cultured synovial cells was markedly increased.
Both A-SAA and C-SAA mRNA are detectable in RA synovia, while only C-SAA mRNA is detectable in OA and in quiescent cultured synovial cells. The steady state A-SAA mRNA isoform in cultured synovial cells was markedly increased in the presence of dexamethasone plus IL-1beta. The local synthesis of A-SAA may contribute, at least in part, to the concentration of A-SAA protein in SF and may contribute to the altered molecular and cellular physiology in RA joints.
血清淀粉样蛋白A（SAA）是一种在炎症过程中产生的生物活性蛋白，存在于类风湿关节炎（RA）患者的滑液（SF）中。基于我们最近的发现，即部分RA患者的滑液SAA浓度超过血清浓度，我们检测了RA和骨关节炎（OA）患者滑膜及培养的滑膜细胞中SAA mRNA亚型的局部稳态浓度。
采用逆转录聚合酶链反应和Northern印迹法分析RA或OA患者滑膜组织以及RA患者培养的滑膜细胞中的总细胞RNA。
急性期SAA（A-SAA）mRNA亚型仅在RA滑膜中检测到，而在OA滑膜中未检测到；然而，组成型SAA（C-SAA）mRNA亚型在OA和RA滑膜中的表达量相似。静止期培养的滑膜细胞中有C-SAA mRNA的表达，但没有A-SAA mRNA的表达。在用1 mM地塞米松和10 ng/ml白细胞介素1β（IL-1β）刺激后，培养的滑膜细胞中稳态A-SAA muRNA的量显著增加。
RA滑膜中可检测到A-SAA和C-SAA mRNA，而OA和静止期培养的滑膜细胞中仅可检测到C-SAA mRNA。在地塞米松加IL-1β存在的情况下，培养的滑膜细胞中稳态A-SAA mRNA亚型显著增加。A-SAA的局部合成可能至少部分导致了SF中A-SAA蛋白的浓度升高，并可能导致RA关节分子和细胞生理学的改变。
