Molecular and cellular response profiles induced by the TLR4 agonist-based adjuvant Glucopyranosyl Lipid A

PLoS One. 2012;7(12):e51618. doi: 10.1371/journal.pone.0051618. Epub 2012 Dec 28.

Abstract

Background: Toll-like receptor (TLR)4 agonists are known potent immunostimulatory compounds. These compounds can be formulated as part of novel adjuvants to enhance vaccine medicated immune responses. However, the contribution of the formulation to the innate in vivo activity of TLR4 agonist compounds is not well understood.

Methodology and principal findings: We evaluated synthetic TLR4 agonist Glucopyranosyl Lipid A (GLA) for its effects on molecular and cellular innate immune responses in the murine model. Microarray techniques were used to compare the responses to GLA in an aqueous formulation or in an oil-in-water Stable Emulsion formulation (GLA-SE) versus either SE alone or the mineral salt aluminum hydroxide (alum) at the muscle injection site over multiple timepoints. In contrast to the minimal gene upregulation induced by SE and alum, both GLA and GLA-SE triggered MyD88- and TRIF-dependent gene expression. Genes for chemokines, cytokine receptors, signaling molecules, complement, and antigen presentation were also strongly upregulated by GLA and GLA-SE. These included chemokines for T(H)1-type T cells (CXCL9 and CXCL10) and mononuclear leukocytes (CCL2, CCL3) among others. GLA-SE induced stronger and more sustained gene upregulation than GLA in the muscle; GLA-SE induced genes were also detected in local draining lymph nodes and at lower levels in peripheral blood. Both GLA and GLA-SE resulted in increased cellular trafficking to the draining lymph nodes and upregulated MHC molecules and ICAM1 on local dendritic cells. GLA and GLA-SE transiently upregulated circulating MCP-1, TNFα, IFNγ and IP-10 in blood.

Conclusions/significance: While GLA and GLA-SE activate a large number of shared innate genes and proteins, GLA-SE induces a quantitatively and qualitatively stronger response than GLA, SE or alum. The genes and proteins upregulated could be used to facilitate selection of appropriate adjuvant doses in vaccine formulations.

MeSH terms

  • Adjuvants, Immunologic / pharmacology*
  • Aluminum Hydroxide / chemistry*
  • Animals
  • Biomarkers / metabolism*
  • Cells, Cultured
  • Dendritic Cells / cytology
  • Dendritic Cells / drug effects
  • Dendritic Cells / metabolism
  • Emulsions
  • Female
  • Flow Cytometry
  • Gene Expression Profiling
  • Gene Expression Regulation / drug effects*
  • Leukocytes, Mononuclear / cytology
  • Leukocytes, Mononuclear / drug effects
  • Leukocytes, Mononuclear / metabolism
  • Lipid A / chemistry
  • Lipid A / pharmacology*
  • Mice
  • Mice, Inbred BALB C
  • Muscles / cytology
  • Muscles / drug effects
  • Muscles / metabolism
  • Oils / chemistry
  • Oligonucleotide Array Sequence Analysis
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes / cytology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism
  • Toll-Like Receptor 4 / agonists*
  • Water / chemistry*

Substances

  • Adjuvants, Immunologic
  • Biomarkers
  • Emulsions
  • Lipid A
  • Oils
  • RNA, Messenger
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Water
  • Aluminum Hydroxide

Grant support

These authors have no support or funding to report.