Released palmitic acid-mediated TLR4/NF-κB activation enhances the virulence of Bordetella pertussis MT28 lineage.

Whooping cough has resurged globally despite high vaccination coverage. In China, a macrolide-resistant (MR) Bordetella pertussis lineage carrying the high-virulence ptxP3 allele, termed ptxP3 MR-MT28 (MT28), has been increasingly reported as a predominant circulating lineage, although the factors underlying its expansion remain unclear. By integrating epidemiological surveillance with genomic, phenotypic, and in vitro and in vivo infection analyses of representative clinical isolates, we demonstrate that MT28 strains exhibit enhanced colonization capacity and heightened inflammatory potential. Transcriptomic analysis revealed upregulation of key virulence-associated genes (ptxA, fhaB, tcfA and bvgA), providing a molecular basis for these phenotypes. Furthermore, lipid-targeted metabolomics and LC-MS identified B. pertussis-derived palmitic acid (PA) as a pro-inflammatory mediator that amplifies MT28-associated inflammation responses via TLR4/NF-κB signaling. These findings provide mechanistic insights into the pathogenic features of the MT28 lineage and reveal a previously unrecognized lipid-driven inflammatory pathway in B. pertussis infection.