Pachyonychia congenita (PC) is a rare keratinizing disorder characterized by painful palmoplantar keratoderma for which there is no standard current treatment. PC is caused by dominant mutations in keratin (K) K6A, K6B, K6C, K16, or K17 genes involved in stress, wound healing, and epidermal barrier formation. Mechanisms leading to pain and painful palmoplantar keratoderma in PC remain elusive. In this study, we show overexpression of EGFR ligands epiregulin and TGF-α as well as HER1‒EGFR and HER2 in the upper spinous layers of PC lesions. EGFR activation was confirmed by upregulated MAPK/ERK and mTOR signaling. Abnormal late terminal keratinization was associated with elevated TGM1 activity. In addition, the calcium ion permeable channel TRPV3 was significantly increased in PC-lesional skin, suggesting a predominant role of the TRPV3/EGFR signaling complex in PC. We hypothesized that this complex contributes to promoting TGM1 activity and induces the expression and shedding of EGFR ligands. To counteract this biological cascade, we treated three patients with PC with oral erlotinib for 6‒8 months. The treatment was well-tolerated and led to an early, drastic, and sustained reduction of neuropathic pain with a major improvement of QOL. Our study provides evidence that targeted pharmacological inhibition of EGFR is an effective strategy in PC.

Arboviruses like chikungunya and Ross River (RRV) are responsible for massive outbreaks of viral polyarthritis. There is no effective treatment or vaccine available against these viruses that induce prolonged and disabling arthritis. To explore the physiopathological mechanisms of alphaviral arthritis, we engineered a recombinant RRV expressing a NanoLuc reporter (RRV-NLuc), which exhibited high stability, near native replication kinetics and allowed real time monitoring of viral spread in an albino mouse strain. During the acute phase of the disease, we observed a high bioluminescent signal reflecting viral replication and dissemination in the infected mice. Using Bindarit, an anti-inflammatory drug that inhibits monocyte recruitment, we observed a reduction in viral dissemination demonstrating the important role of monocytes in the propagation of the virus and the adaptation of this model to the in vivo evaluation of treatment strategies. After resolution of the acute symptoms, we observed an increase in the bioluminescent signal in mice subjected to an immunosuppressive treatment 30 days post infection, thus showing active in vivo replication of remnant virus. We show here that this novel reporter virus is suitable to study the alphaviral disease up to the chronic phase, opening new perspectives for the evaluation of therapeutic interventions.

Neurotropic flavivirus Japanese encephalitis virus (JEV) and West Nile virus (WNV) are amongst the leading causes of encephalitis. Using label-free quantitative proteomics, we identified proteins differentially expressed upon JEV (gp-3, RP9) or WNV (IS98) infection of human neuroblastoma cells. Data are available via ProteomeXchange with identifier PXD016805. Both viruses were associated with the up-regulation of immune response (IFIT1/3/5, ISG15, OAS, STAT1, IRF9) and the down-regulation of SSBP2 and PAM, involved in gene expression and in neuropeptide amidation respectively. Proteins associated to membranes, involved in extracellular matrix organization and collagen metabolism represented major clusters down-regulated by JEV and WNV. Moreover, transcription regulation and mRNA processing clusters were also heavily regulated by both viruses. The proteome of neuroblastoma cells infected by JEV or WNV was significantly modulated in the presence of mosquito saliva, but distinct patterns were associated to each virus. Mosquito saliva favored modulation of proteins associated with gene regulation in JEV infected neuroblastoma cells while modulation of proteins associated with protein maturation, signal transduction and ion transporters was found in WNV infected neuroblastoma cells.

Non-replicative herpes simplex virus type 1 (nrHSV-1) vectors are promising delivery vehicles for gene therapy due to their large DNA payload capacity and ability to infect a broad range of cell types. However, the genomic deletions made to generate such nrHSV-1 vectors can result in undersized genomes that trigger genomic instability—including rearrangements and size extensions—compromising their therapeutic potential. This study investigates the stabilization of undersized nrHSV-1 vectors through the insertion of stuffer DNA segments. We assess genomic stability, productivity, toxicity, and transgene expression in vitro and in vivo. Our findings demonstrate that nrHSV-1 can accommodate variations in genome size up to 5–6% and highlight the importance of maintaining a genome size close to that of the wild-type HSV-1 for enhanced genomic stability and sustained transgene expression without adverse effects. This strategy offers a promising approach for optimizing nrHSV-1 vectors for clinical applications.

En raison de leur potentiel élevé de transmission, de leur vitesse de dissémination qui peut être fulgurante et des maladies parfois sévères qu’ils induisent, les Flavivirus sont considérablement préoccupants. Le virus West Nile (WNV) est actuellement l'un des arbovirus (arthropod-borne virus)le plus répandu dans le monde et sa forte capacité de (ré)émergence pose un problème de santé publique important. Ce virus est responsable de nombreux cas de maladies neurologiques sévères, parfois mortelles, notamment chez l’Homme et les chevaux. Aucun traitement ou vaccin humain anti-WNV n’est actuellement disponible sur le marché. Le(s) rôle(s) de la protéine de membrane (M) des Flavivirus est/sont encore peu caractérisé(s). Cette glycoprotéine est ancrée dans la membrane virale et joue un rôle structural important dans les processus de fusion et de maturation des particules virales. De plus, la protéine M a récemment été associée à la pathogénèse induite par les virus de l’encéphalite japonaise et du Zika (de Wispelaere et al., 2016; Yuanet al., 2017), suggérant que cette protéine contient des déterminants viraux essentiels à la virulence. Afin d’étudier les mécanismes sous-jacents, nous avons substitué le résidu isoleucine localisé en position 36de l’ectodomaine de la protéine M par une phénylalanine (M-I36F), et démontré que cette mutation provoque un encombrement allostérique qui affecte directement la structure de la protéine M.L’introduction d’une seconde mutation (substitution de l’alanine en position 43 par une glycine, résidu ne possédant pas de chaine latérale) dans la même protéine nous a permis de stabiliser la mutation MI36F. Si la mutation M-I36F seule ou associée à la mutation M-A43G n’affecte pas les étapes précoces (entrée,traduction, réplication) du cycle viral, elle est cependant à l’origine d’une modification de la morphologie des particules virales chez l’hôte mammifère. De plus, notre étude suggère que la sécrétion des particules de WNV néo-formées hors du réticulum endoplasmique, une étape encore peu caractérisée du cycle viral, dépend directement de leur morphologie. Enfin, cette étude nous a permis de mettre au point un modèle d’atténuation du WNV rationnellement dessiné, qui a été testé in vivo dans un modèle murin décrit d’encéphalite induite par le WNV. La protection complète induite par le virus double mutant, que nous observons lors d’une épreuve létale avec le virus sauvage, fait de ce virus mutant un potentiel candidat vaccin. Cette étude fait l’objet d’un dépôt de brevet.