Rhodobacter capsulatus PG Lipopolysaccharide As a Potential Blocker of Toll-like Receptor 2 and 4 Activation

TLR2 and TLR4 play a key role in the development of an inflammation in response to a bacterial infection. We studied the effect of Rhodobacter capsulatus PG lipopolysaccharide (LPS) on proinflammatory cytokine synthesis activation by the TLR2 and TLR4 agonists E. coli LPS, Streptococcus pyogenes lipoteichoic acid (LTA), and Pam3CSK4 (a synthetic bacterial lipopeptide) in human whole blood cells. Rhodobacter capsulatus PG LPS was shown to exhibit antagonistic properties against the studied TLR4 and TLR2 agonists, blocking the synthesis of the cytokines TNF-α, IL-6, and IL-8. Possible mechanisms behind the suppressing effect of Rhodobacter capsulatus PG LPS are proposed. Rhodobacter capsulatus PG LPS can serve as a prototype for drugs against both gram-negative and gram-positive bacteria.