Peters-Golden M, McNish R W, Brieland J K, Fantone J C
Department of Internal Medicine, University of Michigan, Ann Arbor.
J Immunol. 1990 Jun 1;144(11):4320-6.
Alveolar macrophages (AM) differ from other macrophage (m phi) populations in their profile of eicosanoids synthesized from arachidonic acid (AA)3. Little information is available regarding possible differences in the regulation of AA metabolism among various m phi populations. In our study, we compared the ability of cultured resident rat AM and peritoneal m phi (PM) to release and metabolize AA in response to exogenous activators of protein kinase C (PKC). When stimulated with PMA, prelabeled PM released free [3H]AA in a dose-dependent manner over the concentration range 1 to 100 nM. As assessed by HPLC, PMA-stimulated PM metabolized AA to a variety of predominantly cyclooxygenase products. The dose-dependent synthesis of PGE2 by unlabeled PM stimulated with PMA was confirmed using RIA. The ability of PMA to trigger AA release and metabolism in PM was a function of its capacity to activate PKC, as indicated by the following: 1) an additional activator of PKC, oleoyl acetylglycerol, also triggered PM AA metabolism, whereas phorbol didecanoate, which lacks the ability to activate PKC, did not; 2) two structurally unrelated inhibitors of PKC activation (staurosporine and sphinganine) both abrogated PMA induced AA release in PM; and 3) pretreatment for 18 h with high dose PMA (used to deplete cellular PKC), but not phorbol didecanoate, rendered PM refractory to subsequent PMA stimulation of AA release. In contrast to PM, AM cultured in identical fashion failed to release or metabolize AA in response to either PMA or oleoyl acetylglycerol. PM and AM were also compared for their ability to release extracellular superoxide anion in response to PMA; once again, PM exhibited significantly greater release than did AM. Inasmuch as this unresponsiveness to activation of PKC distinguishes AM from other m phi populations, we conclude that it is a unique consequence of m phi differentiation in the lung. Moreover, because both AA metabolism and the respiratory burst are affected, this refractoriness appears to reflect a defect at some proximal level in PKC-mediated signaling.
肺泡巨噬细胞（AM）在由花生四烯酸（AA）合成类花生酸的过程中，与其他巨噬细胞（m phi）群体存在差异。关于不同m phi群体中AA代谢调节的可能差异，目前所知甚少。在我们的研究中，我们比较了培养的大鼠驻留AM和腹腔巨噬细胞（PM）对外源性蛋白激酶C（PKC）激活剂的反应中释放和代谢AA的能力。用佛波酯（PMA）刺激时，预先标记的PM在1至100 nM的浓度范围内以剂量依赖的方式释放游离的[3H]AA。通过高效液相色谱（HPLC）评估，PMA刺激的PM将AA代谢为多种主要的环氧化酶产物。使用放射免疫分析（RIA）证实了用PMA刺激未标记的PM时PGE2的剂量依赖性合成。PMA触发PM中AA释放和代谢的能力是其激活PKC能力的函数，如下所示：1）PKC的另一种激活剂油酰乙酰甘油也触发了PM的AA代谢，而缺乏激活PKC能力的佛波二癸酸酯则没有；2）两种结构不相关的PKC激活抑制剂（星形孢菌素和鞘氨醇）都消除了PMA诱导的PM中AA的释放；3）用高剂量PMA（用于耗尽细胞内PKC）预处理18小时，但不是佛波二癸酸酯，使PM对随后PMA刺激的AA释放产生抗性。与PM相反，以相同方式培养的AM对PMA或油酰乙酰甘油均无反应，无法释放或代谢AA。还比较了PM和AM对PMA反应释放细胞外超氧阴离子的能力；同样，PM的释放明显大于AM。由于这种对PKC激活的无反应性将AM与其他m phi群体区分开来，我们得出结论，这是肺中m phi分化的独特结果。此外，由于AA代谢和呼吸爆发均受到影响，这种抗性似乎反映了PKC介导信号传导在某些近端水平上的缺陷。
