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 PG lipopolysaccharide (LPS) on proinflammatory cytokine synthesis activation by the TLR2 and TLR4 agonists LPS, lipoteichoic acid (LTA), and Pam3CSK4 (a synthetic bacterial lipopeptide) in human whole blood cells. 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 PG LPS are proposed. PG LPS can serve as a prototype for drugs against both gram-negative and gram-positive bacteria.