Immune stimulatory
pathogen associated molecular patterns (
PAMPs) are major drivers of
infection pathology.
Infections with Gram-negative bacteria or negatively polar and single stranded
RNA influenza virus are prominent causes of morbidity and mortality.
Toll-like receptor (TLR) 4 is a major host sensor for both of the two
infections. In order to inhibit TLR4 driven immune activation we recently developed synthetic tetra-acylated
lipid A mimetics based on a conformationally restricted βGlcN(1↔1)αGlcN
disaccharide scaffold (DA-compounds) that antagonized ectopically overexpressed human and murine TLR4/MD-2 complexes. Here we comparatively analyzed human peripheral blood mononuclear cell (hPBMC) and murine bone marrow derived macrophage (mBM) activation upon 30 min of preincubation in vitro with six variably acylated DA-compounds. 16 h subsequent to consequent LPS challenge, we sampled culture supernatants for
cytokine and NO concentration analysis. Four compounds significantly inhibited release of both TNF and
IL-6 by hPBMCs upon LPS challenge. In contrast, three compounds effectively inhibited mBM production of MIP-2 and KC, and even five of them inhibited
IL-6 and NO production. LPS driven like other TLR
ligand driven mBM TNF release was largely unimpaired. The inhibitory effect was specific in that Clo75 driven
cytokine release by both hPBMCs and mBMs was unimpaired by the compounds analyzed. Our results indicate
biological species specificity of LPS antagonism by variably tetraacylated
lipid A mimetics and validate three out of six DA-antagonists as promising candidates for development of therapeutically applicable anti-inflammatory compounds.