Hempel S L, Monick M M, Hunninghake G W
Department of Veterans Affairs Medical Center, Iowa City, Iowa 52242.
J Clin Invest. 1994 Jan;93(1):391-6. doi: 10.1172/JCI116971.
We and others have previously demonstrated that human alveolar macrophages produce more PGE2 in response to lipopolysaccharide (LPS) than do blood monocytes. We hypothesized that this observation was due to a greater increase in prostaglandin H synthase-2 (PGHS-2) enzyme mass in the macrophage compared to the monocyte. To evaluate this hypothesis, alveolar macrophages and blood monocytes were obtained from healthy nonsmoking volunteers. The cells were cultured in the presence of 0 to 10 micrograms/ml LPS. LPS induced the synthesis of large amounts of a new 75-kD protein in human alveolar macrophages, and a lesser amount in monocytes. Synthesis of this protein required more than 6 h and peaked in 24 to 48 h; the protein reacted with an anti-PGHS-2 antibody prepared against mouse PGHS-2. Associated with synthesis of the protein was a marked increase in LPS-stimulated and arachidonic acid-stimulated synthesis of PGE2 by alveolar macrophages compared to monocytes. Cells not exposed to LPS contained only PGHS-1 and synthesized very little PGE2 during culture or in response to exogenous arachidonic acid. An LPS-induced mRNA, which hybridized to a human cDNA probe for PGHS-2 mRNA, was produced in parallel with production of this new protein and was produced in much greater amounts by alveolar macrophages compared to blood monocytes. This mRNA was not detectable in cells not exposed to LPS. In contrast, both types of cells contain mRNA, which hybridizes to a cDNA probe for PGHS-1. This mRNA did not increase in response to LPS. LPS also had no effect on PGHS-1 protein. These data demonstrate that PGE2 synthesis in human alveolar macrophages and blood monocytes correlates to the mass of PGHS-2 in the cell. We conclude that the greater ability of the macrophage to synthesize PGE2 in response to LPS is due to greater synthesis of PGHS-2 by the macrophage.
我们和其他研究人员之前已经证明，与血液单核细胞相比，人类肺泡巨噬细胞对脂多糖（LPS）产生的前列腺素E2（PGE2）更多。我们推测，这一现象是由于与单核细胞相比，巨噬细胞中前列腺素H合成酶-2（PGHS-2）的酶量增加幅度更大。为了验证这一推测，我们从健康的非吸烟志愿者身上获取了肺泡巨噬细胞和血液单核细胞。将这些细胞在0至10微克/毫升的LPS存在下进行培养。LPS在人类肺泡巨噬细胞中诱导合成了大量新的75-kD蛋白，在单核细胞中诱导合成的量较少。这种蛋白的合成需要超过6小时，并在24至48小时达到峰值；该蛋白与针对小鼠PGHS-2制备的抗PGHS-2抗体发生反应。与该蛋白的合成相关的是，与单核细胞相比，肺泡巨噬细胞在LPS刺激和花生四烯酸刺激下PGE2的合成显著增加。未暴露于LPS的细胞仅含有PGHS-1，在培养过程中或对外源花生四烯酸的反应中合成的PGE2很少。一种与人类PGHS-2 mRNA cDNA探针杂交的LPS诱导mRNA，与这种新蛋白的产生同时出现，并且与血液单核细胞相比，在肺泡巨噬细胞中产生的量要多得多。在未暴露于LPS的细胞中检测不到这种mRNA。相反，两种类型的细胞都含有与PGHS-1 cDNA探针杂交的mRNA。这种mRNA不会因LPS而增加。LPS对PGHS-1蛋白也没有影响。这些数据表明，人类肺泡巨噬细胞和血液单核细胞中PGE2的合成与细胞中PGHS-2的量相关。我们得出结论，巨噬细胞对LPS合成PGE2的能力更强是由于巨噬细胞中PGHS-2的合成更多。
