Application of CNTF or FGF-2 increases the number of M2-like macrophages after optic nerve injury in adult Rana pipiens
Application of CNTF or FGF-2 increases the number of M2-like macrophages after optic nerve injury in adult Rana pipiens
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DOI：
10.1371/journal.pone.0209733
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发表时间：
2019-05-02
期刊：
影响因子：
3.7
通讯作者：
Blagburn, Jonathan M.
中科院分区：
文献类型：
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作者：
Blanco, Rosa E.;Vega-Melendez, Giam S.;Blagburn, Jonathan M.
我们先前已经证明，在青蛙的视神经损伤处单独应用生长因子睫状神经营养因子(CNTF)或成纤维细胞生长因子-2(FGF-2)，可以增加再生的视网膜神经节细胞轴突的数量和延长率。在这里，我们研究这些因素对侵入再生区的巨噬细胞的数量和类型的影响。在PBS处理的对照神经中，损伤后1周，在远端100微米处可见大量巨噬细胞；2周后，巨噬细胞数量减半。在损伤时使用CNTF一次，巨噬细胞数量在1周时增加三倍，而与对照组相比，这一增加保持在2周。应用成纤维细胞生长因子-2在1周时同样有效，但在2周时巨噬细胞数量已降至对照水平。用泛巨噬细胞标志物ED1和M2样巨噬细胞标志物Arg-1进行免疫染色显示，在所有处理中，假定的M2表型的比例保持在大约80%。1周龄的巨噬细胞的电子显微镜显示，所有处理的巨噬细胞都有很强的吞噬活性，有许多含有轴突碎片和膜碎片的空泡。在PBS或成纤维细胞生长因子-2治疗2周后，剩下的巨噬细胞吞噬活性降低，主要含有脂包涵体。CNTF治疗2周后，许多数量较多的巨噬细胞仍在吞噬轴突碎片，尽管它们也含有脂质包裹物。我们的结论是，应用生长因子后巨噬细胞内流的增加有利于再生轴突，这可能是因为更广泛地去除了退化的远端轴突，但也可能是由于促进生长的物质的分泌。
We have previously shown that a single application of the growth factors ciliary neurotrophic factor (CNTF) or fibroblast growth factor 2 (FGF-2) to the crushed optic nerve of the frog, Rana pipiens, increases the numbers and elongation rate of regenerating retinal ganglion cell axons. Here we investigate the effects of these factors on the numbers and types of macrophages that invade the regeneration zone. In control PBS-treated nerves, many macrophages are present 100 mu m distal to the crush site at 1 week after injury; their numbers halve by 2 weeks. A single application of CNTF at the time of injury triples the numbers of macrophages at 1 week, with this increase compared to control being maintained at 2 weeks. Application of FGF-2 is equally effective at 1 week, but the macrophage numbers have fallen to control levels at 2 weeks. Immunostaining with a pan-macrophage marker, ED1, and a marker for M2-like macrophages, Arg-1, showed that the proportion of the putative M2 phenotype remained at approximately 80% with all treatments. Electron microscopy of the macrophages at 1 week shows strong phagocytic activity with all treatments, with many vacuoles containing axon fragments and membrane debris. At 2 weeks with PBS or FGF-2 treatment the remaining macrophages are less phagocytically active, containing mainly lipid inclusions. With CNTF treatment, at 2 weeks many of the more numerous macrophages are still phagocytosing axonal debris, although they also contain lipid inclusions. We conclude that the increase in macrophage influx seen after growth factor application is beneficial for the regenerating axons, probably due to more extensive removal of degenerating distal axons, but also perhaps to secretion of growth-promoting substances.