CD4 and infection: Taking together, these data from all the heatmaps in Figure 2, Figure 3 and Figure 4 indicated that: (1) in the gingiva, the proportions of MFs, MNPs, and CD11B+DCs were significantly rising; (2) in the colon, the proportions of MFs, MNPs, pDCs, ILC3s, abT cells, CD4+T cells, and Tregs were significantly changed; (3) in the spleen, similarly, the proportions of MFs, pDCs, ILC3s, abT cells, CD4+T cells, CD8+T cells, DN cells, and Tregs showed significant changes after mono-infection of three key periodontal bacteria, compared with those of the GF group.