Fig. 4. Histology of the Cutibacterium acnes-induced lesions.

Mice were euthanized on day 10. a–c sham-injected control group,at magnification of ($\times$4, $\times$10, $\times$20, A-C accordingly). The skin is within normal range and therefore not scored. d Nodular inflammation (arrow) involving the dermis and subcutaneous tissue at $\times$4 magnification in the infected-untreated group scored 2. e Nodular infiltrates with an area of necrosis with cellular infiltration (arrowhead) at $\times$10 magnification in the infected-untreated group. f ×20 magnification of the infected-untreated group. g Nodular inflammation (arrow) involving only the subcutaneous tissue below the panniculus carnosus at $\times$4 magnification in the treated group scored 1. h A nodular cellular infiltration (arrowhead), numerous vacuolated cytoplasm mixed with a minimal number of neutrophils at $\times$10 magnification of the treated group. i ×20 magnification of the treated group This experiment was done twice. j Affected lesion area was measured, and scored; for further details, see Fig. 7 and Supplemental Fig. S4, p-value of the infected-untreated group in comparison to phage-treated group = 0.11, 0.03, 0.04, <0.001 for Area, Histological Score, Combined Histological Score, and Combined Histological and Clinical Score accordingly. n = 4 mice. Data are presented as mean ± standard deviation (SD). Student’s t test two-tailed unpaired was used, *p-value < 0.05, and **p-value < 0.001. Source data are provided as a Source Data file.