Reproductive toxicity assessment of cellulose nanofibers, citric acid, and branched polyethylenimine in sea urchins: Eco-design of nanostructured cellulose sponge framework (Part B).

In the framework of a safe-by-design approach, we previously assessed the eco-safety of nanostructured cellulose sponge (CNS) leachate on sea urchin reproduction. It impaired gamete quality, gamete fertilization competence, and embryo development possibly due to the leaching of chemical additives used during the CNS synthesis process. To extend this observation and identify the component(s) that contribute to CNS ecotoxicity, in the present study, we individually screened the cytotoxic effects on sea urchin Arbacia lixula and Paracentrotus lividus gametes and embryos of the three main constituents of CNS, namely cellulose nanofibers, citric acid, and branched polyethylenimine. The study aimed to minimize any potential safety risk of these components and to obtain an eco-safe CNS. Among the three CNS constituents, branched polyethylenimine resulted in the most toxic agent. Indeed, it affected the physiology and fertilization competence of male and female gametes as well as embryo development in both sea urchin species. These results are consistent with those previously reported for CNS leachate. Moreover, the characterisation of CNS leachate confirmed the presence of detectable branched polyethylenimine in the conditioned seawater even though in a very limited amount. Altogether, these data indicate that the presence of branched polyethylenimine is a cause-effect associated with a significant risk in CNS formulations due to its leaching upon contact with seawater. Nevertheless, the suggested safety protocol consisting of consecutive leaching treatments and conditioning of CNS in seawater can successfully ameliorate the CNS ecotoxicity while maintaining the efficacy of its sorbent properties supporting potential environmental applications.

Silver Nanoparticles Supported onto TEMPO-Oxidized Cellulose Nanofibers for Promoting Cd2+ Cation Adsorption.

Nanocellulose constitutes a sustainable and biobased solution both as an efficient sorbent material for water treatment and as support for other inorganic nanomaterials with sorbent properties. Herein, we report the synthesis of a nanocomposite by deposition of in situ-generated silver nanoparticles (AgNPs) onto TEMPO-oxidized cellulose nanofibers (TOCNFs). Following an in-depth analytical investigation, we unveil for the first time the key role of AgNPs in enhancing the adsorption efficiency of TOCNF toward Cd2+ ions, chosen as model heavy metal contaminants. The obtained nanocomposite shows a value of Cd2+ sorption capacity at equilibrium from 150 mg L-1 ion aqueous solutions of ∼116 mg g-1 against the value of 78 mg g-1 measured for TOCNF alone. A combination of field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS) analyses suggests that Cd2+ ions are mainly adsorbed in the neighborhood of AgNPs. However, XPS characterization allows us to conclude that the role of AgNPs relies on increasing the exposure of carboxylic groups with respect to the original TOCNF, suggesting that these groups are still responsible for absorption. In fact, X-ray absorption spectroscopy (XAS) analysis of the Cd-K edge excludes a direct interaction between Ag0 and Cd2+, supporting the XPS results and confirming the coordination of the latter with carboxyl groups.

Global siRNA Screen Reveals Critical Human Host Factors of SARS-CoV-2 Multicycle Replication.

Defining the subset of cellular factors governing SARS-CoV-2 replication can provide critical insights into viral pathogenesis and identify targets for host-directed antiviral therapies. While a number of genetic screens have previously reported SARS-CoV-2 host dependency factors, these approaches relied on utilizing pooled genome-scale CRISPR libraries, which are biased towards the discovery of host proteins impacting early stages of viral replication. To identify host factors involved throughout the SARS-CoV-2 infectious cycle, we conducted an arrayed genome-scale siRNA screen. Resulting data were integrated with published datasets to reveal pathways supported by orthogonal datasets, including transcriptional regulation, epigenetic modifications, and MAPK signalling. The identified proviral host factors were mapped into the SARS-CoV-2 infectious cycle, including 27 proteins that were determined to impact assembly and release. Additionally, a subset of proteins were tested across other coronaviruses revealing 17 potential pan-coronavirus targets. Further studies illuminated a role for the heparan sulfate proteoglycan perlecan in SARS-CoV-2 viral entry, and found that inhibition of the non-canonical NF-kB pathway through targeting of BIRC2 restricts SARS-CoV-2 replication both in vitro and in vivo. These studies provide critical insight into the landscape of virus-host interactions driving SARS-CoV-2 replication as well as valuable targets for host-directed antivirals.

Discovery of CMX990: A Potent SARS-CoV-2 3CL Protease Inhibitor Bearing a Novel Warhead.

There remains a need to develop novel SARS-CoV-2 therapeutic options that improve upon existing therapies by an increased robustness of response, fewer safety liabilities, and global-ready accessibility. Functionally critical viral main protease (Mpro, 3CLpro) of SARS-CoV-2 is an attractive target due to its homology within the coronaviral family, and lack thereof toward human proteases. In this disclosure, we outline the advent of a novel SARS-CoV-2 3CLpro inhibitor, CMX990, bearing an unprecedented trifluoromethoxymethyl ketone warhead. Compared with the marketed drug nirmatrelvir (combination with ritonavir = Paxlovid), CMX990 has distinctly differentiated potency (∼5× more potent in primary cells) and human in vitro clearance (>4× better microsomal clearance and >10× better hepatocyte clearance), with good in vitro-to-in vivo correlation. Based on its compelling preclinical profile and projected once or twice a day dosing supporting unboosted oral therapy in humans, CMX990 advanced to a Phase 1 clinical trial as an oral drug candidate for SARS-CoV-2.

The Therapeutic Monoclonal Antibody Bamlanivimab Does Not Enhance SARS-CoV-2 Infection by FcR-Mediated Mechanisms.

As part of the non-clinical safety package characterizing bamlanivimab (SARS-CoV-2 neutralizing monoclonal antibody), the risk profile for antibody-dependent enhancement of infection (ADE) was evaluated in vitro and in an African green monkey (AGM) model of COVID-19. In vitro ADE assays in primary human macrophage, Raji, or THP-1 cells were used to evaluate enhancement of viral infection. Bamlanivimab binding to C1q, FcR, and cell-based effector activity was also assessed. In AGMs, the impact of bamlanivimab pretreatment on viral loads and clinical and histological pathology was assessed to evaluate enhanced SARS-CoV-2 replication or pathology. Bamlanivimab did not increase viral replication in vitro, despite a demonstrated effector function. In vivo, no significant differences were found among the AGM groups for weight, temperature, or food intake. Treatment with bamlanivimab reduced viral loads in nasal and oral swabs and BAL fluid relative to control groups. Viral antigen was not detected in lung tissue from animals treated with the highest dose of bamlanivimab. Bamlanivimab did not induce ADE of SARS-CoV-2 infection in vitro or in an AGM model of infection at any dose evaluated. The findings suggest that high-affinity monoclonal antibodies pose a low risk of mediating ADE in patients and support their safety profile as a treatment of COVID-19 disease.