TLR4 antagonist FP7 inhibits LPS-induced cytokine production and glycolytic reprogramming in dendritic cells, and protects mice from lethal influenza infection

Laure Perrin-Cocon,Kari Ann Shirey,Mira C Patel,Jorge C Blanco,Stefanie N Vogel,Vincent Lotteau,Stefania E Sestito,Anne Aublin-Gex,Francesco Peri,Patrice André

doi:10.1038/srep40791

Abstract

Dysregulated Toll-like receptor (TLR)-4 activation is involved in acute systemic sepsis, chronic inflammatory diseases, such as atherosclerosis and diabetes, and in viral infections, such as influenza infection. Thus, therapeutic control of the TLR4 signalling pathway is of major interest. Here we tested the activity of the small-molecule synthetic TLR4 antagonist, FP7, in vitro on human monocytes and monocyte-derived dendritic cells (DCs) and in vivo during influenza virus infection of mice. Our results indicate that FP7 antagonized the secretion of proinflammatory cytokines (IL-6, IL-8, and MIP-1β) by monocytes and DCs (IC50 < 1 μM) and prevented DC maturation upon TLR4 activation by ultrapure lipopolysaccharide (LPS). FP7 selectively blocked TLR4 stimulation, but not TLR1/2, TLR2/6, or TLR3 activation. TLR4 stimulation of human DCs resulted in increased glycolytic activity that was also antagonized by FP7. FP7 protected mice from influenza virus-induced lethality and reduced both proinflammatory cytokine gene expression in the lungs and acute lung injury (ALI). Therefore, FP7 can antagonize TLR4 activation in vitro and protect mice from severe influenza infection, most likely by reducing TLR4-dependent cytokine storm mediated by damage-associated molecular patterns (DAMPs) like HMGB1.

Highlights

Among the first receptors activated during host-pathogen interactions are members of the Toll-like Receptor (TLR) family, which can detect microbial products and induce innate and adaptive immune responses[1]
The co-receptor CD14 has been shown to be essential for initiating endocytosis of (TLR4.myeloid differentiation factor 2 (MD-2).LPS)[2] heterodimers and the subsequent activation of TRAM-TRIF pathway leading to the production of type I IFN5
Both monocytes and monocyte-derived dendritic cells (DCs) express TLR4 and stimulation of TLR4 by LPS induces the secretion of proinflammatory cytokines, the nature of the cytokine response varies according to the cell type (Fig. 2)

Summary

Introduction

Among the first receptors activated during host-pathogen interactions are members of the Toll-like Receptor (TLR) family, which can detect microbial products and induce innate and adaptive immune responses[1]. The co-receptor CD14 has been shown to be essential for initiating endocytosis of (TLR4.MD-2.LPS)[2] heterodimers and the subsequent activation of TRAM-TRIF pathway leading to the production of type I IFN5. Metabolic reprogramming has emerged as a key checkpoint for the activation of innate immune cells such as murine MΦs and DCs26, for which TLR4 activation results in the preferential use of glycolysis, rather than mitochondrial catabolic pathways[27,28,29,30]. This process recalls the Warburg effect observed in tumour cells[31]. Despite the potent anti-sepsis activity of Eritoran in animal models, and despite its excellent safety profile in humans, it failed in a Phase III randomized controlled trial for all cause sepsis[37]

Methods

Results

Conclusion