Lipoteichoic Acid from Heyndrickxia coagulans HOM5301 Modulates the Immune Response of RAW 264.7 Macrophages

<i>Heyndrickxia coagulans</i> (formerly <i>Bacillus coagulans</i>) has been increasingly utilized as an immunomodulatory probiotics. Oral administration of <i>H. coagulans</i> HOM5301 significantly boosted both innate and adaptive immunity in mice, particularly by increasing the phagocytic capacity of monocytes/macrophages. Lipoteichoic acid (LTA), a major microbe-associated molecular pattern (MAMP) in Gram-positive bacteria, exhibits differential immunomodulatory effects due to its structural heterogeneity. We extracted, purified, and characterized LTA from <i>H. coagulans</i> HOM5301. The results showed that HOM5301 LTA consists of a glycerophosphate backbone. Its molecular weight is in the range of 10-16 kDa. HOM5301 LTA induced greater productions of nitric oxide, TNFα, and IL-6 in RAW 264.7 macrophages compared to <i>Staphylococcus aureus</i> LTA. Comparative transcriptome and proteome analyses identified the differentially expressed genes and proteins triggered by HOM5301 LTA. KEGG analyses revealed that HOM5301 LTA transcriptionally and translationally activated macrophages through two immune-related pathways: cytokine-cytokine receptor interaction and phagosome formation. Protein-protein interaction network analysis indicated that the pro-inflammatory response elicited by HOM5301 LTA was TLR2-dependent, possibly requiring the coreceptor CD14, and is mediated via the MAPK and NF-kappaB pathways. Our results demonstrate that LTA is an important MAMP of <i>H. coagulans</i> HOM5301 that boosts immune responses, suggesting that HOM5301 LTA may be a promising immunoadjuvant.