Palmitic acid-mediated TLR4/NF-κB activation drives the pathogenicity of hypervirulent Bordetella pertussis MT28 lineage

Whooping cough resurged globally despite the widespread vaccination. A macrolide-resistant (MR) lineage carrying the high-virulence ptxP3 allele, ptxP3 MR-MT28 (MT28), has imposed a substantial burden on pertussis epidemics, while the underlying factors driving its prevalence remain unclear. Thus, we performed an epidemiological surveillance and bacterial genomic, phenotypic, in vitro and in vivo pathogenicity analyses. We found MT28 lineage exhibits enhanced abilities of colonization and pro-inflammatory. Transcriptomic analysis revealed significant upregulation of key virulence genes (ptxA, fhaB, tcfA and bvgA), suggesting a molecular basis for its transmission and pathogenicity. Further, lipid-targeted metabolomics and liquid chromatography-mass spectrometry (LC-MS) identified B. pertussis-derived palmitic acid (PA) as a crucial pro-inflammatory mediator that promotes MT28 pathogenicity via the TLR4/NF-κB signaling pathway. These findings elucidate the mechanisms underlying the prevalence and increased pathogenicity of the MT28 lineage, and propose a novel pathogenic mechanism of B. pertussis involving PA-mediated activation of the TLR4/NF-κB inflammatory signaling pathway.