Myeloid cell reprogramming drives enhanced defense against Streptococcus pneumoniae lung infection following exposure to commensal Prevotella.

Pre-exposure to Prevotella melaninogenica reprograms myeloid cells to enhance Streptococcus pneumoniae clearance in mice.

• Why it matters: Understanding how commensal microbes influence lung immune responses could reveal new strategies to reduce pneumonia mortality, which remains a significant health concern.
• What they did: Single-cell RNA sequencing was used to analyze immune signatures in mice pre-exposed to P. melaninogenica, revealing a shift from interferon-dominant to antibacterial myeloid transcriptional profiles.
• The result: This reprogramming increased macrophage and neutrophil phagocytosis of S. pneumoniae, with TNF signaling via TNFR2 and CCR2-dependent monocyte-derived macrophages being essential for improved pathogen clearance.