Modulating the innate immune response by combinatorial engineering of endotoxin

Abstract

Despite its highly inflammatory nature, LPS is a molecule with remarkable therapeutic potential. Lipid A is a glycolipid that serves as the hydrophobic anchor of LPS and constitutes a potent ligand of the Toll-like receptor (TLR)4/myeloid differentiation factor 2 receptor of the innate immune system. A less toxic mixture of monophosphorylated lipid A species (MPL) recently became the first new Food and Drug Administration-approved adjuvant in over 70 y. Whereas wild-type Escherichia coli LPS provokes strong inflammatory MyD88 (myeloid differentiation primary response gene 88)-mediated TLR4 signaling, MPL preferentially induces less inflammatory TRIF (TIR-domain-containing adaptor-inducing IFN-β)-mediated responses. Here, we developed a system for combinatorial structural diversification of E. coli lipid A, yielding a spectrum of bioactive variants that display distinct TLR4 agonist activities and cytokine induction. Mice immunized with engineered lipid A/antigen emulsions exhibited robust IgG titers, indicating the efficacy of these molecules as adjuvants. This approach demonstrates how combinatorial engineering of lipid A can be exploited to generate a spectrum of immunostimulatory molecules for vaccine and therapeutics development.

Lipopolysaccharide Engineering in Neisseria meningitidis

“…Consequently, a high efficiency of conversion of the wild-type hexaacyl to the 3-O-deacyl pentaacyl LPS form was achieved by the heterologous expression of the PagL enzyme. Because lipid A-modifying enzymes like PagL and PagP often only converse a fraction of the total LPS, they may increase LPS heterogeneity; in addition, some modifications may trigger secondary alterations that further complicate the final composi- tion (10,30). This can be a complicating factor when analyzing the biological effect of the introduced modifications, as the mixtures may have different properties compared with their individual constituents.…”

The Vps/VacJ ABC Transporter Is Required for Intercellular Spread of Shigella flexneri

“…Bacteria were grown in the presence of 2.5 Ci/ml 32 P i to an OD 650 of ϳ1.0 in LB broth. Both lipid A and phospholipids were extracted according to the method of Bligh and Dyer (40) and spotted onto a Silica Gel 60 thin-layer chromatography (TLC) plate as previously described (41,42). Phospholipids (50,000 counts/sample) were separated by TLC using a chloroformmethanol-acetic acid (65:25:10, vol/vol) solvent system.…”

Microbial strain-level population structure and genetic diversity from metagenomes

“…Strain-level variants within microbial species are crucial in determining their functional capacities within the human microbiome, including interaction with host tissues (Bron et al 2012), modulation of immune homeostasis (Needham et al 2013), and xenobiotic metabolism (Spanogiannopoulos et al 2016). Pathogenic potential is also strain-specific in many species, including Escherichia coli, which is prevalent in the healthy human gut despite some strains causing life-threatening infections (Bielaszewska et al 2011;Loman et al 2013) or mucosal necrosis in premature infants .…”