The Skin Secretome in the Antiviral Response against Arboviruses. – S2ARA

Arboviruses are emerging single-stranded positive-sense RNA viruses transmitted to, and pathogenic for, humans by blood-sucking arthropods, predominantly mosquitoes. The flaviviruses Dengue virus (DENV), West Nile virus (WNV), Zikavirus (ZIKV) and the alphavirus Chikungunyavirus (CHIKV) are responsible for millions of infections worldwide with a wide range of clinical manifestations from mild flu-like illness to severe neurological manifestations such as encephalitis, Guillain-Barré syndrome or abnormalities of intra-uterine fetal cerebral development.There is to date no antiviral to combat CHIKV, DENV, WNV and ZIKV infections. In humans, infection begins with inoculation of the virus into the dermis and the epidermis by the mosquito during the blood meal. Several types of resident skin cells such as epidermal keratinocytes, dermal fibroblasts and endothelial cells of the blood capillaries of the dermis have been shown to be permissive for arbovirus replication. These skin cells can detect arbovirus replication through pattern recognition receptors (PRR) and subsequently rapidly elicits an innate immune response to fight the viral infection. The skin is thus both the entry point, the first replication site and the first line of defense of the host against these viruses. However, our knowledge of the antiviral response by resident, non-immune, skin cells against arboviral infections is still very limited. In this project, we hypothesize that resident non-immune skin cells can produce peptide molecules, such as interferon-stimulated genes (ISG) and antimicrobial peptides (AMP), which may have antiviral activity that may in turn be exploited to prevent or cure arbovirus infection at the virus entry point in the body. The overall aim of this project is to study and then to exploit the skin antiviral response during arbovirus infection. The specific project objectives are (i) identify, by whole-transcriptome expression profiling, antiviral candidates, made of early cellular proteins induced or late cellular proteins repressed, in four human resident skin cell types (primary Keratinocytes, sebocyte cell line, primary dermal fibroblasts and dermal microvascular endothelial cells) inoculated with CHIKV, DENV, WNV and ZIKV or stimulated with a synthetic double-stranded RNA, (ii) test their anti-arboviral activity against the same four arboviruses and (iii) unravel the cell signaling pathways that regulate their expression. Extensive characterization of the effector molecules and their precise role in the early antiviral response will furnish greater insights into the host-arbovirus interactions, why these viruses can establish an infection and how it will be possible to tilt the balance in favor of the host at their first point of entry and initial replication site, well before systemic spread occurs to the target organs, such as the central nervous system, the liver or the fetus and before the adaptive immune response kicks in. By performing this study with multiple arboviruses, we will determine commonalities of the response to diverse viral genotypes. New antiviral strategies will be also devised, through the design of novel therapeutic analogs against infection or evaluation of agonists capable of specifically stimulating the antiviral response, that will serve to raise our preparedness for newly emerging arboviruses.