Fig. 6: S. pyogenes is extracellular within lymph nodes and evades killing by CD169+ macrophages.
From: Extracellular bacterial lymphatic metastasis drives Streptococcus pyogenes systemic infection
a–c Immunofluorescence staining of cryosections from the draining inguinal lymph nodes of FVB/n mice 3 h after intramuscular injection into the hindlimb with 108 CFU of hypervirulent S. pyogenes H1565 (green); CD169 (blue) and brightfield shown in grey; Overview of the subcapsular sinus (SCS) and medullary sinuses (MS) (a); Maximum intensity projection (b) and orthogonal views of a 15 µm confocal z-stack (c). Scale bars: 50 µm (a); 10 µm (b, c). Imaging data are representative of five independent experiments. See also Supplementary Movie 8. d–f Recovery of S. pyogenes H1565 from the hindlimb infection site (d), draining lymph nodes (e), and systemic organs (f) of FVB/n mice injected subcutaneously in the tail and leg with either clodronate liposomes (red triangles), saline liposomes (blue squares), or a saline sham (grey circles) 96 h prior to a 3-h intramuscular infection with 108 CFU. Symbols represent individual mice, n = 5 per group, lines indicate geometric means. ns, p > 0.5: one-way ANOVA followed by Tukey’s multiple comparisons post-tests were performed on log10-transformed data. g, h Percentage of intracellular S. pyogenes 0.5, 3, or 24 h after intramuscular infection with 108 CFU of S. pyogenes H1565; gentamicin protection assays on ipsilateral inguinal nodes (g) or spleens (h) of infected FVB/n mice at each time point. Each red circle represents an individual mouse, n = 5 per group, black lines indicate geometric means. See also Supplementary Fig. 6. CFU are per ml of blood, per leg, or per organ.
