Development and Characterization of Synthetic Glucopyranosyl Lipid Adjuvant System as a Vaccine Adjuvant

Abstract

Innate immune responses to vaccine adjuvants based on lipopolysaccharide (LPS), a component of Gram-negative bacterial cell walls, are driven by Toll-like receptor (TLR) 4 and adaptor proteins including MyD88 and TRIF, leading to the production of inflammatory cytokines, type I interferons, and chemokines. We report here on the characterization of a synthetic hexaacylated lipid A derivative, denoted as glucopyranosyl lipid adjuvant (GLA). We assessed the effects of GLA on murine and human dendritic cells (DC) by combining microarray, mRNA and protein multiplex assays and flow cytometry analyses. We demonstrate that GLA has multifunctional immunomodulatory activity similar to naturally-derived monophosphory lipid A (MPL) on murine DC, including the production of inflammatory cytokines, chemokines, DC maturation and antigen-presenting functions. In contrast, hexaacylated GLA was overall more potent on a molar basis than heterogeneous MPL when tested on human DC and peripheral blood mononuclear cells (PBMC). When administered in vivo, GLA enhanced the immunogenicity of co-administered recombinant antigens, producing strong cell-mediated immunity and a qualitative TH1 response. We conclude that the GLA adjuvant stimulates and directs innate and adaptive immune responses by inducing DC maturation and the concomitant release of pro-inflammatory cytokines and chemokines associated with immune cell trafficking, activities which have important implications for the development of future vaccine adjuvants.

Selection of Adjuvants for Enhanced Vaccine Potency

“…Administration of the full length recombinant Toxoplasma GRA2 or GRA6 protein antigen in combination with MPL adjuvant led to a Th1 response in mice [303]. Similar Th1 effects were also observed with vaccine Fluzone [304] or recombinant antigens [305], both adjuvanted with synthesized hesaacylated lipid A derivatives in mice and Leishmania sterol 24-c-methyltransferase antigen with MPL-SE [306]. In contract, subcutaneous immunization of MPL-adjuvanted ovalbumin or glutaraldehyde-modified ragweed pollen extract enhanced IgG1 titer (barely increased IgG2a) in mice [307].…”

“…Three such analogues, synthesized by different substitutions at 3-O-position of the reducing sugar, were all found as effective as the natural compound in inducing antigen specific T-cell proliferation and interferon- production with a liposome vaccine [319]. A hexaacylated lipid A derivative was recently found to be more potent than MPL on DC maturation and expression of cytokines/chemokines [305]. The exploration of MPL derivatives or other glycolipids would continue in the development of future vaccines.…”

Distinct TLR adjuvants differentially stimulate systemic and local innate immune responses in nonhuman primates

“…1,3 TLR ligands (TLR-Ls) represent an emerging new class of molecules with great potential as vaccine adjuvants. [3][4][5]8,10 Several TLR-dependent compounds are in advanced preclinical and clinical trials (eg, cytosine-phosphate-guanine oligodeoxynucleotide [CpG-ODN], 10 poly I-C/L-C, 10 and glucopyranosyl lipid adjuvant 14 ) and some have already been licensed for clinical use as adjuvants (eg, MPL-AS04 13 ) or therapeutics (eg, imidazoquilines 15 ). TLRs sense a wide range of pathogen-associated molecular patterns from bacteria, viruses, and parasites (reviewed in Kawai and Akira 16 and in Takeuchi and Akira 17 ).…”

“…TLRs sense a wide range of pathogen-associated molecular patterns from bacteria, viruses, and parasites (reviewed in Kawai and Akira 16 and in Takeuchi and Akira 17 ). The nontoxic derivatives of LPS-MPL 18 or glucopyranosyl lipid adjuvant 14 are detected by TLR4. TLR7 and TLR8 sense viral ssRNAs or small synthetic molecule compounds (eg, R-837 or R-848).…”

Adjuvant solution for pandemic influenza vaccine production

“…Glucopyranosyl lipid adjuvant (GLA) is a formulated form of the synthetic TLR4 agonist PHAD (Avanti Polar Lipids), which is analogous to the detoxified LPS derivative monophosphoryl lipid A (MPL), a component of the human papillomavirus vaccine Cervarix (9). Experimental vaccines containing GLA demonstrate enhanced immunogenicity in a variety of disease models (8), and in the context of influenza, GLA formulated in a stable emulsion (GLA-SE) improved Fluzone-dependent antibody titers in mice and nonhuman primates, relative to an emulsion alone (10)(11)(12)(13). Given the critical importance of immunological priming for pandemic vaccine preparedness, we set out to test whether adjuvanting a recombinant H5 antigen with GLA-SE would broaden protective immunity against H5N1.…”