Abstract
The inhibition of tumor necrosis factor (TNF) through the use of either antibodies or soluble receptors is a highly effective strategy for the clinical control of chronic inflammatory conditions such as rheumatoid arthritis. Different viruses have similarly exploited this concept by expressing a set of specifically tailored secreted TNF decoy receptors to block host inflammatory responses. Poxviruses have been shown to encode at least two distinct molecules, termed Cytokine response modifier D (CrmD) and CrmB, in which a TNF inhibitor is combined with a chemokine inhibitor on the same molecule. The ectromelia virus CrmD protein was found to be a critical determinant of virulence in vivo, being able to control local inflammation to allow further viral spread and the establishment of a lethal infection. Strikingly, both the TNF and the chemokine inhibitory domains are required for the full activity of CrmD, suggesting a model in which inhibition of TNF is supported by the concomitant blockade of a reduced set of chemokines. Inspired by this model, we reasoned that a similar strategy could be applied to modify the clinically used human TNF receptor (etanercept), producing a generation of novel, more effective therapeutic agents. Here we show the analysis of a set of fusion proteins derived from etanercept by addition of a viral chemokine-binding protein. A bifunctional inhibitor capable of binding to and blocking the activity of TNF as well as a set of chemokines is generated that is active in the prevention of arthritis in a murine disease model.
Highlights
In an ongoing evolutionary arms race, viruses have contributed to shape the innate and adaptive immune system of their vertebrate hosts through the development of effective countermeasures directed against it
In variola virus (VARV) Cytokine response modifier B (CrmB), the smallpox virus-encoded chemokine receptor (SECRET) domain including residues T194 to L348 was found to bind to the same set of chemokines as the complete VARV CrmB protein and could be fused to another two viral TNF receptors (vTNFRs) (CrmC and CrmE), conferring chemokine-binding ability upon them while preserving their tumor necrosis factor (TNF)-binding capability [17]
With the aim of conferring chemokine inhibitory activity to the soluble hTNFR2–Fc receptor, we first generated a collection of hTNFR2–Fc receptors in which we inserted SECRET
Summary
In an ongoing evolutionary arms race, viruses have contributed to shape the innate and adaptive immune system of their vertebrate hosts through the development of effective countermeasures directed against it. Different viruses deploy sets of proteins targeted at distinct host response pathways depending on their target tissue as well as their replication strategies [1,2,3]. Common elements frequently targeted by various viruses and employing different strategies include the antiviral interferon. IFN response, the inflammatory response or the antigen presentation pathways [2]. A relevant strategy found mostly in different families of large dsDNA viruses such as herpesviruses and poxviruses is the use of viral secreted proteins targeting cytokines, the soluble mediators of the immune response [4].
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