Kawaguchi H, Nemoto K, Raisz L G, Harrison J R, Voznesensky O S, Alander C B, Pilbeam C C
Department of Medicine, University of Connecticut Health Center, Farmington, U.S.A.
J Bone Miner Res. 1996 Mar;11(3):358-66. doi: 10.1002/jbmr.5650110309.
We have shown previously that prostaglandin (PG) production in 7-day-old neonatal mouse calvarial cultures is regulated largely by changes in prostaglandin G/H synthase-2 (PGHS-2) expression and to a lesser extent by changes in arachidonic acid (AA) release. In this study, we examined the effects of interleukin-4 (IL-4), and its interactions with other cytokines and with parathyroid hormone (PTH), on mRNA levels of PGHS-2, PGHS-1, and cytosolic phospholipase A2 (cPLA2) and on medium protaglandin E2 (PGE2) levels in calvarial cultures. IL-1 and tumor necrosis factor-alpha (TNF-alpha), both at 1-100 ng/ml, and PTH at 0.1-10 nM increased PGHS-2 and cPLA2 mRNA and medium PGE2 levels dose-dependently after 4 h of treatment. IL-6 and IL-11 at 1-100 ng/ml did not affect mRNA or PGE2 levels. IL-4 at 1-100 ng/ml decreased PGHS-2 and cPLA2 mRNA and PGE2 levels in control as well as IL-1, TNF-alpha, and PTH-stimulated cultures. The inhibition of PGHS-2 and cPLA2 mRNA expression by IL-4 (10 ng/ml) was present at 1 h, reached a maximum at 4 h, and persisted for 24 h. The effects were maintained in the presence of cycloheximide. IL-4 also decreased PGHS-2 protein levels in control and IL-1-stimulated cultures. PGHS-1 mRNA levels were not stimulated by any of the factors studied nor inhibited by IL-4. IL-4 partially inhibited control and PTH-stimulated 45Ca release from prelabeled mouse calvariae at 4 days. However, neither the inhibition of resorption by IL-4 nor the stimulation by IL-1 and PTH were altered by indomethacin (1 microM). We conclude that (1) IL-1, TNF-alpha, and PTH, but not IL-6 nor IL-11, can increase the expression of PGHS-2, cPLA2, and PGE2 production in cultured mouse calvariae; (2) IL-4 inhibits PGE2 production in both control and stimulated calvarial cultures by inhibiting PGHS-2 and cPLA2; and (3) IL-4 has an inhibitory effect on bone resorption which is independent of PG production.
我们先前已经表明，7日龄新生小鼠颅骨培养物中前列腺素（PG）的产生主要受前列腺素G/H合酶-2（PGHS-2）表达变化的调节，其次受花生四烯酸（AA）释放变化的调节。在本研究中，我们检测了白细胞介素-4（IL-4）及其与其他细胞因子和甲状旁腺激素（PTH）的相互作用对颅骨培养物中PGHS-2、PGHS-1和胞质磷脂酶A2（cPLA2）的mRNA水平以及培养基中前列腺素E2（PGE2）水平的影响。1-100 ng/ml的IL-1和肿瘤坏死因子-α（TNF-α）以及0.1-10 nM的PTH在处理4小时后剂量依赖性地增加了PGHS-2和cPLA2的mRNA以及培养基中PGE2的水平。1-100 ng/ml的IL-6和IL-11不影响mRNA或PGE2水平。1-100 ng/ml的IL-4在对照以及IL-1、TNF-α和PTH刺激的培养物中降低了PGHS-2和cPLA2的mRNA以及PGE2水平。IL-4（10 ng/ml）对PGHS-2和cPLA2 mRNA表达的抑制在1小时时出现，4小时时达到最大值，并持续24小时。在存在放线菌酮的情况下，这些作用得以维持。IL-4还降低了对照和IL-1刺激的培养物中PGHS-2的蛋白水平。PGHS-1的mRNA水平未受到所研究的任何因素的刺激，也未被IL-4抑制。IL-4在4天时部分抑制了对照和PTH刺激的预标记小鼠颅骨中45Ca的释放。然而，吲哚美辛（1 microM）并未改变IL-4对吸收的抑制作用以及IL-1和PTH的刺激作用。我们得出结论：（1）IL-1、TNF-α和PTH而非IL-6和IL-11可增加培养的小鼠颅骨中PGHS-2、cPLA2的表达以及PGE2的产生；（2）IL-4通过抑制PGHS-2和cPLA2在对照和刺激的颅骨培养物中均抑制PGE2的产生；（3）IL-4对骨吸收具有抑制作用，且该作用与PG的产生无关。
