Akkermansia muciniphila attenuates Brucella infection: TLR4−associated inflammatory regulation and gut microbiota remodeling

Abstract

Akkermansia muciniphila ( A. muciniphila ) is a promising next-generation probiotic with well-established beneficial effects on metabolic disorders, inflammatory diseases, and host immunity. However, whether A. muciniphila protects against Brucella infection remains unknown. Here, we investigated the prophylactic effects of pre-exposure administration of A. muciniphila against Brucella infection using both in vitro and in vivo models. In RAW264.7 macrophages, pre-exposure treatment with A. muciniphila differentially regulated cytokine responses following Brucella infection by suppressing IL-1β and IL-18 expression while enhancing TNF-α, IFN-γ, and IL-10 expression, indicating balanced immunomodulation rather than generalized immune suppression. Consistent with these findings, oral administration of A. muciniphila significantly reduced splenic bacterial burdens and alleviated histopathological lesions in infected mice. Moreover, A. muciniphila partially reshaped infection-associated gut microbiota dysbiosis by enriching beneficial bacterial taxa, including Limosilactobacillus in vivo . A. muciniphila reduced splenic TLR4 and IL-1β mRNA expression, whereas in Brucella -infected macrophages it reduced TLR4 and p65 protein expression, suggesting involvement of TLR4-associated inflammatory signaling. This study provides the first proof-of-concept evidence that pre-exposure administration of A. muciniphila attenuates Brucella infection. The protective effects were associated with balanced modulation of host immune responses, reduced bacterial burden, partial shift towards gut microbiota homeostasis, and reduced TLR4 expression. These findings support the potential of A. muciniphila as a probiotic-based strategy for pre-exposure prophylaxis against brucellosis and provide a foundation for future studies investigating gut-derived systemic immunomodulation in host defense against intracellular bacterial pathogens.