Heparan sulfate proteoglycans (HSPG) are composed of unbranched, negatively charged heparan sulfate (HS) polysaccharides attached to a variety of cell surface or extracellular matrix proteins. Widely expressed, they mediate many biological activities, including angiogenesis, blood coagulation, developmental processes, and cell homeostasis. HSPG are highly sulfated and broadly used by a range of pathogens, especially viruses, to attach to the cell surface.

Enterovirus 71 (EV71) causes hand, foot and mouth disease, a mild and self-limited illness that is sometimes associated with severe neurological complications. EV71 neurotropic determinants remain ill-defined to date. We previously identified a mutation in the VP1 capsid protein (L97R) that was acquired over the course of a disseminated infection in an immunocompromised host. The mutation was absent in the respiratory tract but was present in the gut (as a mixed population) and in blood and cerebrospinal fluid (as a dominant species). In this study, we demonstrated that this mutation does not alter the dependence of EV71 on the human scavenger receptor class B2 (SCARB2), while it enables the virus to bind to the heparan sulfate (HS) attachment receptor and modifies viral tropism in cell lines and in respiratory, intestinal and neural tissues. Variants with VP197L or VP197R were able to replicate to high levels in intestinal and neural tissues and, to a lesser extent, in respiratory tissues, but their preferred entry site (from the luminal or basal tissue side) differed in respiratory and intestinal tissues and correlated with HS expression levels. These data account for the viral populations sequenced from the patient’s respiratory and intestinal samples and suggest that improved dissemination, resulting from an acquired ability to bind HS, rather than specific neurotropism determinants, enabled the virus to reach and infect the central nervous system. Finally, we showed that iota-carrageenan, a highly sulfated polysaccharide, efficiently blocks the replication of HS-dependent variants in cells and 2D neural cultures. Overall, the results of this study emphasize the importance of HS binding in EV71 pathogenesis and open new avenues for the development of antiviral molecules that may prevent this virus’s dissemination.

Respiratory viral infections cause mild to severe diseases, such as common cold, bronchiolitis and pneumonia and are associated with substantial burden for society. To test new molecules for shortening, alleviating the diseases or to develop new therapies, relevant human in vitro models are mandatory. MucilAir™, a human standardized air-liquid interface 3D airway epithelial culture holds in vitro specific mechanisms to counter invaders comparable to the in vivo situation, such as mucus production, mucociliary clearance, and secretion of defensive molecules. The objective of this study was to test the relevance of such a model for the discovery and validation of antiviral drugs. Fully differentiated 3D nasal epithelium cultures were inoculated with picornaviruses, a coronavirus and influenza A viruses in the absence or in the presence of reference antiviral drugs. Results showed that, rupintrivir efficiently inhibits the replication of respiratory picornaviruses in a dose dependent manner and prevents the impairment of the mucociliary clearance. Similarly, oseltamivir reduced the replication of influenza A viruses in a dose dependent manner and prevented the impairment of the epithelial barrier function and cytotoxicity until 4 days of infection. In addition we found that Rhinovirus B14, C15 and influenza A(H1N1) induce significant increase of β Defensins 2 and Cathelicidin release with different time course. These results reveal that a large panel of epithelial functions is modified upon viral infection and validate MucilAir™ as a pertinent tool for pre-clinical antiviral drug testing.

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PURPOSE: Tumor cell heterogeneity and microenvironment represent major hindering factors in the clinical setting toward achieving the desired selectivity and specificity to malignant tissues for molecularly targeted cancer therapeutics. In this study, the cellular and molecular evaluation of several delocalized lipophilic cation (DLC)-functionalized carborane compounds as innovative anticancer agents is presented. METHODS:The anticancer potential assessment of the DLC-carboranes was performed in established normal (MRC-5, Vero), cancer (U-87 MG, HSC-3) and primary glioblastoma cancer stem (EGFR pos , EGFR neg ) cultures. Moreover, the molecular mechanism of action underlying their pharmacological response is also analyzed. RESULTS:The pharmacological anticancer profile of DLC-functionalized carboranes is characterized by: a) a marked in vitro selectivity, due to lower concentration range needed (ca. 10 fold) to exert their cell growth-arrest effect on U-87 MG and HSC-3, as compared with that on MRC-5, Vero; b) a similar selective growth inhibition behavior towards EGFR pos and EGFR neg cultures (>10 fold difference in potency) without, however, the activation of apoptosis in cultures; c) notably, in marked contrast to cancer cells, normal cells are capable of recapitulating their full proliferation potential following exposure to DLC-carboranes; and, d) such pharmacological effects of DLC-carboranes has been unveiled to be elicited at the molecular level through activation of the p53/p21 axis. CONCLUSIONS:Overall, the data presented in this work indicates the potential of the DLC-functionalized carboranes to act as new selective anticancer therapeutics that 3 may be used autonomously or in therapies involving radiation with thermal neutrons.Importantly, such bifunctional capacity may be beneficial in cancer therapy.