Cross-Talk between Human Dendritic Cell Subsets Influences Expression of RNA Sensors and Inhibits Picornavirus Infection

Abstract

Dendritic cells (DCs) are professional antigen-presenting cells that provide a link between innate and adaptive immunity. Multiple DC subsets exist and their activation by microorganisms occurs through binding of conserved pathogen-derived structures to so-called pattern recognition receptors (PRRs). In this study we analyzed the expression of PRRs responding to viral RNA in human monocyte-derived DCs (moDCs) under steady-state or pro-inflammatory conditions. We found that mRNA and protein levels for most PRRs were increased under pro-inflammatory conditions, with the most pronounced increases in the RIG-like helicase (RLH) family. Additionally, freshly isolated human plasmacytoid DCs (pDCs) displayed significantly higher levels of TLR7, RIG-I, MDA5 and PKR as compared to myeloid DCs and moDCs. Finally, we demonstrate for the first time that cross-talk between TLR-matured or virus-stimulated pDCs and moDCs leads to a type I interferon-dependent antiviral state in moDCs. This antiviral state was characterized by enhanced RLH expression and protection against picornavirus infection. These findings might represent a novel mechanism by which pDCs can preserve the function and viability of myeloid DCs that are attracted to a site with ongoing infection, thereby optimizing the antiviral immune response.

Targeting Uptake Receptors on Human Plasmacytoid Dendritic Cells Triggers Antigen Cross-Presentation and Robust Type I IFN Secretion

“…*p , 0.05, ***p , 0.0001. associated side effects (44)(45)(46). We believe that exploiting NPs that target such Ag uptake receptors that are expressed by both pDCs and myeloid DCs has great potential, as they interact synergistically, thereby increasing Ag-specific immune responses induced by these cells (47)(48)(49)(50). Furthermore, we believe that nanocarriers, such as the PLGA particles described in this study, pose a powerful and versatile tool, as they can be decorated with different Abs for targeting of different cell populations.…”

Generating the optimal mRNA for therapy: HPLC purification eliminates immune activation and improves translation of nucleoside-modified, protein-encoding mRNA

“…Monocyte-derived DCs that express these and all other known RNA sensors (24) were used to measure residual immune activation present in modified nucleoside-containing RNA. A series of RNAs with coding sequences for mammalian and reporter proteins flanked by different 5′- and 3′-UTRs were analyzed.…”

Increased Erythropoiesis in Mice Injected With Submicrogram Quantities of Pseudouridine-containing mRNA Encoding Erythropoietin

“…DCs efficiently translate exogenously delivered mRNA and express all known RNA sensors, such as TLR3, TLR7, TLR8, RIG-I, MDA-5, and PKR. 17 All the features that are known to improve translation were incorporated into the transcripts. The mRNAs were HPLC purified and contained the 5′-UTR derived from the tobacco etch virus 5′ leader RNA, 3′-UTR of Xenopus β-globin mRNA, an enzymatically-generated cap1 structure, and a plasmid-encoded 51 nt-long poly(A) tail, which was extended to ~200 nt-long using poly(A) polymerase.…”