TLR5 expression marks brain boarder associated macrophage

Bacterial meningitis poses a significant threat to prenatal and newborn babies, resulting in a high number of infant deaths worldwide. Infants, with their underdeveloped adaptive immunity, rely on brain macrophages to defend against pathogenic infections. However, the precise characteristics and functions of brain macrophages during the neonatal period remain incompletely understood, necessitating further investigation. Our research initially explores the expression of cell surface Toll-like receptors on brain macrophages in neonatal mice. By utilizing flow cytometry, RNA-seq and immune fluorescence staining, we have uncovered that TLR5 specifically expressed on BAMs but not microglia. Furthermore, our study reveals that priming TLR5 with its ligands enhances the survival rate of neonatal mice when confronted with bacterial meningitis, possibly through recruiting innate immune cells such as monocytes and neutrophils. Overall design: TLR5+ or TLR5- P0 mouse brain CD45+CD11b+Ly6c- macrophages are sorted. Total RNA was extracted using Trizol (Invitrogen). Total amounts and integrity of RNA were assessed using the RNA Nano 6000 Assay Kit of the Bioanalyzer 2100 system (Agilent Technologies, CA, USA). The library and sequencing were conducted by Novogene (Beijing, China) using illumina NovaSeq 6000.