Postbiotics From Ligilactobacillus salivarius Enhance Mitochondrial Robustness Via TLR2 Signaling in Intestinal Macrophages.

Postbiotics, defined as preparations of inanimate microorganisms and/or their components, have attracted increasing attention because of their stability and functional benefits. Although lactic acid bacteria (LAB) modulate immune responses and oxidative stress, their direct effects on host mitochondrial homeostasis remain poorly understood. In this study, we investigated whether postbiotics derived from Ligilactobacillus salivarius enhance mitochondrial robustness in porcine intestinal macrophages (IPIMs). To establish a model of disrupted mitochondrial redox homeostasis, mitochondrial dysfunction was induced using the mitochondrial complex III inhibitor Antimycin A (AMA). High-dose AMA induced mitochondrial reactive oxygen species (mtROS) accumulation and suppressed the expression of antioxidant genes, including SOD2. Pre-stimulation with heat-killed L. salivarius suppressed AMA-induced mtROS production in selected representative strains, with the most effective strains enhancing SOD2 expression. These mtROS-suppressive strains selectively activated Toll like receptor (TLR)1/2 and TLR2/6 signaling, whereas non-protective strains failed to induce TLR responsiveness. Pharmacological inhibition of TLR2 abolished mtROS suppression and SOD2 induction, confirming TLR2 dependency. Furthermore, Seahorse extracellular flux analysis revealed that postbiotics enhanced mitochondrial respiration, including maximal respiration and spare respiratory capacity, via TLR2 signaling. Collectively, our findings demonstrate that postbiotics function as immunometabolic modulators that reinforce mitochondrial redox homeostasis and respiratory capacity via TLR2 signaling, highlighting a novel mechanism by which microbial components contribute to intestinal immune cell homeostasis.