Institute for Anatomy and Cell Biology, Justus Liebig University, Giessen, Germany.
Laboratory of Experimental Surgery, Department of General and Thoracic Surgery, Justus Liebig University, Giessen, Germany.
PLoS One. 2016 Oct 13;11(10):e0163483. doi: 10.1371/journal.pone.0163483. eCollection 2016.
Members of the calcitonin peptide family-calcitonin gene-related peptide (CGRP), adrenomedullin (AM), and adrenomedullin2/intermedin (IMD)-exert modulatory effects upon monocytes and macrophages of various extrapulmonary origins. Utilizing the rat alveolar macrophage (AMφ) cell line NR8383, we here set out to determine to which extent these three peptides and their receptors are differentially regulated in AMφ and what specific effects they have on AMφ key functions. LPS treatment differentially up-regulated expression of the peptides and receptors. Among the three peptides, IMD mRNA content was lowest both in primary rat AMφ and NR8383 cells, whereas IMD peptide dominated in basal and LPS-stimulated secretion from NR8383 cells. Fcγ receptor-mediated phagocytosis and TNF-α production were inhibited by AM, IMD, and CGRP, whereas pro-IL-1β mRNA was slightly down-regulated exclusively by CGRP. Neither of these peptides affected IL-6 or IL-10 production. None increased intracellular calcium concentration, but AM significantly inhibited store-operated calcium entry. In conclusion, the rat AMφ cell line NR8383 is both a source and a target of the calcitonin peptide family members AM, IMD, and CGRP. Despite sharing proteins of the receptor complexes, AM, IMD, and CGRP each showed a characteristic pattern of effects and regulation, suggesting that these closely related peptides are not just redundant members of one common signaling pathway but act in concert by addressing parallel signaling cascades. Since peptide and receptor expression are up-regulated by LPS, these signaling pathways might act as inhibitory feedback mechanisms in pulmonary bacterial infection.
降钙素肽家族成员——降钙素基因相关肽（CGRP）、肾上腺髓质素（AM）和肾上腺髓质素 2/中间素（IMD）——对各种肺外来源的单核细胞和巨噬细胞发挥调节作用。利用大鼠肺泡巨噬细胞（AMφ）细胞系 NR8383，我们旨在确定这三种肽及其受体在 AMφ 中的表达差异程度，以及它们对 AMφ 关键功能的具体影响。LPS 处理可差异地上调这些肽和受体的表达。在这三种肽中，IMD mRNA 含量在原代大鼠 AMφ 和 NR8383 细胞中均最低，而 IMD 肽在 NR8383 细胞的基础和 LPS 刺激分泌中占主导地位。Fcγ 受体介导的吞噬作用和 TNF-α 产生受 AM、IMD 和 CGRP 抑制，而 CGRP 则可轻微下调 pro-IL-1β mRNA。这些肽均不影响 IL-6 或 IL-10 的产生。没有一种肽增加细胞内钙浓度，但 AM 可显著抑制钙库操纵的钙内流。总之，大鼠 AMφ 细胞系 NR8383 既是降钙素肽家族成员 AM、IMD 和 CGRP 的来源，也是其靶细胞。尽管它们共享受体复合物的蛋白，但 AM、IMD 和 CGRP 各自表现出特征性的作用和调节模式，这表明这些密切相关的肽不仅是同一共同信号通路的冗余成员，而且通过针对平行信号级联发挥协同作用。由于肽和受体表达受 LPS 上调，这些信号通路可能在肺部细菌感染中作为抑制性反馈机制发挥作用。
