发布: 2017年11月20日第7卷第22期 DOI: 10.21769/BioProtoc.2608 浏览次数: 14906
评审: Xi FengKarthik KrishnamurthyAnonymous reviewer(s)
Abstract
Microglia and macrophage cells are the primary producers of cytokines in response to neuroinflammatory processes. But these cytokines are also produced by other glial cells, endothelial cells, and neurons. It is essential to identify the cells that produce these cytokines to target their different levels of activation. We used dual RNAscope® fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) techniques to visualize the mRNA expression pattern of pro- and anti-inflammatory cytokines in microglia/macrophages cells. Using these methods, we can associate one mRNA to specific cell types when combining with different cellular markers by immunofluorescence. Results from RNAscope® probes IL-1β, TNFα, TGFβ, IL-10 or Arg1, showed colocalization with antibodies for microglia/macrophage cells. These target probes showed adequate sensitivity and specificity to detect mRNA expression. New FISH detection techniques combined with immunohistochemical techniques will help to jointly determine the protein and mRNA localization, as well as provide reliable quantification of the mRNA expression levels.
Keywords: in situ hybridization (原位杂交)Background
The mRNA in situ hybridization technique is a useful tool that allows the specific and selective labeling of RNA sequences in brain slices in a cell-dependent manner (Grabinski et al., 2015). Furthermore, the use of antibodies against these specific cytokines can produce variable results due to the detection limits of the technique. Namely, because these cytokines are expressed in low abundance, the detection limit becomes the limiting factor for the use of antibodies. Lastly, fluorescence in situ hybridization (FISH) combined with immunohistochemistry (ISH) allows the examination of cytokine mRNA profiles in distinct cells with high selectivity and specificity, thus allowing us to identify the precise cellular source of cytokine production following TBI. This protocol describes how the combination of FISH and immunofluorescence imaging can bridge the gap between mRNA and protein analysis. We can identify the target mRNA being produced by microglia/macrophage cells. Analysis of both RNA and protein expression in the same tissue allows differentiating between cell specific production of microglia/macrophage cells and other cell types. There are limited studies on the effects of sex on inflammation profile following traumatic brain injury (TBI). In our recent publication (Villapol et al., 2017), we used RNAscope® technology combined with immunofluorescence to determine pro-inflammatory (e.g., IL1β and TNFα) and anti-inflammatory (e.g., TGFβ and Arg1) cytokine mRNA expression profiles in microglia/macrophages in the injured brains of male and female mice. Our data demonstrate that a mixed pattern of both pro-inflammatory and anti-inflammatory cytokine expression occurred in microglia/macrophages in the first week after TBI. Also, we have previously shown that IL-10 levels are significantly increased in microglia/macrophages in the injured cortex of NOX2-/- mice (Barrett et al., 2017).
In summary, the use of FISH improves specificity and sensitivity when examining cytokine mRNAs in distinct cells, confirmed by antibody co-immunostaining for microglia/macrophages. This method allows us to identify the cellular source of cytokine production following brain injury with much-improved confidence.
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版权信息
© 2017 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Lanfranco, M. F., Loane, D. J., Mocchetti, I., Burns, M. P. and Villapol, S. (2017). Combination of Fluorescent in situ Hybridization (FISH) and Immunofluorescence Imaging for Detection of Cytokine Expression in Microglia/Macrophage Cells. Bio-protocol 7(22): e2608. DOI: 10.21769/BioProtoc.2608.
分类
神经科学 > 神经系统疾病 > 动物模型
神经科学 > 细胞机理 > 胞内信号传导
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