Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
J Neuroinflammation. 2011 Dec 2;8:169. doi: 10.1186/1742-2094-8-169.
Neuropeptide Y (NPY) is emerging as a modulator of communication between the brain and the immune system. However, in spite of increasing evidence that supports a role for NPY in the modulation of microglial cell responses to inflammatory conditions, there is no consistent information regarding the action of NPY on microglial phagocytic activity, a vital component of the inflammatory response in brain injury. Taking this into consideration, we sought to assess a potential new role for NPY as a modulator of phagocytosis by microglial cells.
The N9 murine microglial cell line was used to evaluate the role of NPY in phagocytosis. For that purpose, an IgG-opsonized latex bead assay was performed in the presence of lipopolysaccharide (LPS) and an interleukin-1β (IL-1β) challenge, and upon NPY treatment. A pharmacological approach using NPY receptor agonists and antagonists followed to uncover which NPY receptor was involved. Moreover, western blotting and immunocytochemical studies were performed to evaluate expression of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27), in an inflammatory context, upon NPY treatment.
Here, we show that NPY inhibits phagocytosis of opsonized latex beads and inhibits actin cytoskeleton reorganization triggered by LPS stimulation. Co-stimulation of microglia with LPS and adenosine triphosphate also resulted in increased phagocytosis, an effect inhibited by an interleukin-1 receptor antagonist, suggesting involvement of IL-1β signaling. Furthermore, direct application of LPS or IL-1β activated downstream signaling molecules, including p38 MAPK and HSP27, and these effects were inhibited by NPY. Moreover, we also observed that the inhibitory effect of NPY on phagocytosis was mediated via Y1 receptor activation.
Altogether, we have identified a novel role for NPY in the regulation of microglial phagocytic properties, in an inflammatory context.
神经肽 Y（NPY）作为大脑和免疫系统之间通讯的调节剂而崭露头角。然而，尽管越来越多的证据支持 NPY 在调节小胶质细胞对炎症状态的反应方面发挥作用，但对于 NPY 对小胶质细胞吞噬活性的作用，尚无一致的信息，而小胶质细胞吞噬活性是脑损伤中炎症反应的重要组成部分。考虑到这一点，我们试图评估 NPY 作为小胶质细胞吞噬作用调节剂的潜在新作用。
使用 N9 鼠小胶质细胞系评估 NPY 在吞噬作用中的作用。为此，在脂多糖（LPS）和白细胞介素-1β（IL-1β）挑战以及 NPY 处理的情况下，进行 IgG 调理的乳胶珠测定。采用 NPY 受体激动剂和拮抗剂的药理学方法，以揭示涉及哪种 NPY 受体。此外，在炎症环境中，进行 Western blot 和免疫细胞化学研究，以评估 NPY 处理后 p38 有丝分裂原激活的蛋白激酶（MAPK）和热休克蛋白 27（HSP27）的表达。
在这里，我们表明 NPY 抑制调理的乳胶珠的吞噬作用，并抑制 LPS 刺激引发的肌动蛋白细胞骨架重排。LPS 和三磷酸腺苷（ATP）共同刺激小胶质细胞也导致吞噬作用增加，这种作用被白细胞介素-1 受体拮抗剂抑制，表明涉及 IL-1β 信号转导。此外，直接应用 LPS 或 IL-1β 激活下游信号分子，包括 p38 MAPK 和 HSP27，而 NPY 抑制这些作用。此外，我们还观察到 NPY 对吞噬作用的抑制作用是通过 Y1 受体激活介导的。
总之，我们已经确定了 NPY 在调节炎症环境中小胶质细胞吞噬特性方面的新作用。
