The synergistic effects of combining TLR ligand based adjuvants on the cytokine response are dependent upon p38/JNK signalling

Abstract

Toll like receptor (TLR) ligands are important adjuvant candidates, causing antigen presenting cells to release inflammatory mediators, leading to the recruitment and activation of other leukocytes. The aim of this study was to define the response of human blood derived dendritic cells and macrophages to three TLR ligands acting singly or in combination, Poly I:C (TLR3), GLA (TLR4) and R848 (TLR7/8). Combinations of TLR agonists have been shown to have a synergistic effect on individual cytokines, here we look at the global inflammatory response measuring both cytokines and chemokines. Using a custom Luminex assay we saw dose responses in several mediators including CCL3 (MIP1α), IL-1α, IL-1β, IL-12, CXCL10 (IP-10) and IL-6, all of which were significantly increased by the combination of R848 and GLA, even when low dose GLA was added. The synergistic effect was inhibited by specific MAP kinase inhibitors blocking the kinases p38 and JNK but not MEK1. Combining TLR adjuvants also had a synergistic effect on cytokine responses in human mucosal tissue explants. From this we conclude that the combination of R848 and GLA potentiates the inflammatory profile of antigen presenting cells. Since the pattern of inflammatory mediators released can alter the quality and quantity of the adaptive immune response to vaccination, this study informs vaccine adjuvant design.

HMGN1 and R848 Synergistically Activate Dendritic Cells Using Multiple Signaling Pathways

“…These signaling pathways lead to the activation of many transcriptional factors (e.g., NF-κB, CREB, AP-1, IRF3, and IRF7), which, upon translocating to the nucleus, promote the transcription of genes characteristic of DC maturation/activation, including genes for cytokines (e.g., IL-12, IL-1β, and TNF-α), co-stimulatory molecules (CD80, CD83, and CD86), and MHC molecules (MHC class I and II). Furthermore, various transcription factors cooperate to synergistically upregulate the expression of genes characteristic of DCs activation, for example IL-12 upregulation requires both NF-κB and IRF (30, 45–47). Since N1 activates DCs predominantly by stimulating surface TLR4 and using both MyD88 and TRIF pathways (4), while R848 activates endosomal TLR7/8 using MyD88, but not the TRIF, pathway (14), it is likely that TLR4 stimulants can thus enhance the effects of TLR7/8 stimulants via the TRIF pathway.…”

Adjuvant composition and delivery route shape immune response quality and protective efficacy of a recombinant vaccine for Entamoeba histolytica

“…Recent work has indicated promising potential for TLR4/TLR7-8 adjuvant formulations. 19 , 26 – 28 TLR7-8 ligands have particular relevance for vaccines designed for infants. 29 Nevertheless, the increased complexity of such an approach requires demonstration of added benefit of each TLR ligand to justify further development.…”

Synergistic Activation of Toll-Like and NOD Receptors by Complementary Antigens as Facilitators of Autoimmune Disease: Review, Model and Novel Predictions

“…Many synergisms have been documented within the innate immune system. These synergisms include TLR2 with TLR3, TLR2 with TLR4, TLR2 with TLR6, TLR 3 with TLRs 7 and 8, TLR 4 with TLR7, and TLR 4 with TLR 8 and 9 [ 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 ]. For example, TLR2 and 4 synergize in rheumatoid arthritis-derived synoviocytes [ 119 , 120 ], rheumatoid arthritis [ 120 ], sarcoidosis [ 121 ], systemic lupus erythematosus, systemic sclerosis, Sjogren’s syndrome, psoriasis, multiple sclerosis and autoimmune diabetes [ 120 ].…”