Vol. 218, No. 8 | https://doi.org/10.1084/jem.20210040 | June 16, 2021
In the original legend of Fig. 5, the descriptions for panels A, B, and C were mislabeled, and the related citations in the text used the wrong panel letters. In the original article, panel A described panel C, panel B described panel A, and panel C described panel B. In addition, the Fig. 5 B key was erroneously labeled. The orange and blue bars have been corrected to read "APOElo" and "APOEhi," respectively. The original and corrected Fig. 5 and its legend are shown here, as are the corrected citations in the Results section and the Fig. 3 legend, which are shown in bold and underlined. The conclusions of the article remain unchanged.
The Fig. 5 legend and citation errors appear in print and in PDFs downloaded before July 31, 2025. The Fig. 5 B key errors appear in print and in PDFs downloaded before August 6, 2025.
Results
Myeloid analysis reveals temporal changes in macrophage and microglial subtypes (fifth paragraph)
To validate the presence of chemotaxis-inducing and inflammatory macrophage subtypes in vivo, we performed immunohistochemistry using antibodies against CD63 and APOE to spatially validate our results (Fig. 5 C). While CD11b+ myeloid cells were present at all time points, CD11b+/CD63+ cells started to appear by 3 dpi. By 7 dpi, many CD11b+/CD63+ cells that were either APOElo (chemotaxis-inducing) or APOEhi (inflammatory) were present at the lesion core. Since graded expression based on fluorescence intensity is difficult to quantify using immunohistochemistry, we used flow cytometry to quantify the relative proportion of these two macrophage subtypes. After separating monocytes/macrophages from other leukocytes including microglia (see Materials and methods), we isolated macrophages based on CD63hi expression (Fig. 5 A). Further separation on APOE and CD11b expression revealed two distinct clusters that were consistent with chemotaxis-inducing (CD63hi/CD11bmed/APOElo) and inflammatory (CD63hi/CD11bhi/APOEhi) subtypes (Fig. 5 A). Similar to our sequencing data, the CD63− myeloid cells were the predominant population at 1 dpi, and decreased by 7 dpi, whereas inflammatory macrophages (APOEhi) were the most represented macrophage subtype at 7 dpi (Fig. 5 B). Therefore, both immunohistochemistry and flow cytometry data support the molecular identification of chemotaxis-inducing and inflammatory subtypes and their temporal progression after SCI in vivo. In summary, analysis of myeloid cells reveals novel subtypes of microglia and macrophages during SCI progression.
