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