A PEG-lipid-free COVID-19 mRNA vaccine triggers robust immune responses in mice.

COVID-19 mRNA vaccines represent a completely new category of vaccines and play a crucial role in controlling the COVID-19 pandemic. In this study, we have developed a PEG-lipid-free two-component mRNA vaccine (PFTCmvac) by formulating mRNA encoding the receptor binding domain (RBD) of SARS-CoV-2 into lipid-like nanoassemblies. Without using polyethylene glycol (PEG)-lipids, the self-assembled PFTCmvac forms thermostable nanoassemblies and exhibits a dose-dependent cellular uptake and membrane disruption, eventually leading to high-level protein expression in both mammalian cells and mice. Vaccination with PFTCmvac elicits strong humoral and cellular responses in mice, without evidence of significant adverse reactions. In addition, the vaccine platform does not trigger complement activation in human serum, even at a high serum concentration. Collectively, the PEG-lipid-free two-component nanoassemblies provide an alternative delivery technology for COVID-19 mRNA vaccines and opportunities for the rapid production of new mRNA vaccines against emerging infectious diseases.

Tubuloside B, isolated from Cistanche tubulosa, a promising agent against M1 macrophage activation via synergistically targeting Mob1 and ERK1/2.

Targeting macrophage M1 polarization is a promising strategy with fewer detrimental effects in COVID-19 curation. Phenylethanoid glycosides (PhGs) of Cistanche tubulosa are a botanical drug to possess various anti-inflammation-related functions, such as immunomodulating, hepatoprotective or neuroprotective functions, whereas their anti-inflammatory activity is rarely understood. A search into their anti-inflammatory characteristics led to the isolation of 49 PhGs along with 15 new PhGs. Their inhibitory effects against M1 polarization induced by LPS plus IFN-γ were explored in RAW264.7 macrophages. Of these PhGs, tubuloside B (Tub B) exerted substantial NO scavenging effect both in chemical- and cell-based assays, and it inhibited massive production of cytokines and chemokines. Tub B decreased ERK1/2 phosphorylation via direct binding and inhibited the MAPK signaling pathway. Tub B also directly binded to Mob1 protein, thereby increased the stability and level of Mob1 protein by inhibiting ubiquitinated degradation. Mob1 was pivotal for the anti-inflammatory activity of Tub B, and it acted independently of the canonical Hippo-YAP pathway. Moreover, ERK1/2 and Mob1 also had a synergic effect on modulating the inflammatory response. Finally, these effects of Tub B were verified in mice with LPS-induced systemic inflammatory response syndrome. Taken together, these results indicated that Tub B acted as a promising agent against M1 macrophage activation by synergistically targeting ERK1/2 and Mob1, and that it may potentially be a drug candidate to prevent/treat inflammatory diseases, especially in COVID-19.

The "LLQY" Motif on SARS-CoV-2 Spike Protein Affects S Incorporation into Virus Particles.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) glycoprotein mediates viral entry and membrane fusion. Its cleavage at S1/S2 and S2' sites during the biosynthesis in virus producer cells and viral entry are critical for viral infection and transmission. In contrast, the biological significance of the junction region between both cleavage sites for S protein synthesis and function is less understood. By analyzing the conservation and structure of S protein, we found that intrachain contacts formed by the conserved tyrosine (Y) residue 756 (Y756) with three α-helices contribute to the spike's conformational stability. When Y756 is mutated to an amino acid residue that can provide hydrogen bonds, S protein could be expressed as a cleaved form, but not vice versa. Also, the L753 mutation linked to the Y756 hydrogen bond prevents the S protein from being cleaved. Y756 and L753 mutations alter S protein subcellular localization. Importantly, Y756 and L753 mutations are demonstrated to reduce the infectivity of the SARS-CoV-2 pseudoviruses by interfering with the incorporation of S protein into pseudovirus particles and causing the pseudoviruses to lose their sensitivity to neutralizing antibodies. Furthermore, both mutations affect the assembly and production of SARS-CoV-2 virus-like particles in cell culture. Together, our findings reveal for the first time a critical role for the conserved L753-LQ-Y756 motif between S1/S2 and S2' cleavage sites in S protein synthesis and processing as well as virus assembly and infection. IMPORTANCE The continuous emergence of SARS-CoV-2 variants such as the delta or lambda lineage caused the continuation of the COVID-19 epidemic and challenged the effectiveness of the existing vaccines. Logically, the spike (S) protein mutation has attracted much concern. However, the key amino acids in S protein for its structure and function are still not very clear. In this study, we discovered for the first time that the conserved residues Y756 and L753 at the junction between the S1/S2 and S2' sites are very important, like the S2' cleavage site R815, for the synthesis and processing of S protein such as protease cleavage, and that the mutations severely interfered with the incorporation of S protein into pseudotyped virus particles and SARS-CoV-2 virus-like particles. Consequently, we delineate the novel potential target for the design of broad-spectrum antiviral drugs in the future, especially in the emergence of SARS-CoV-2 variants.

Genus Lonicera: New drug discovery from traditional usage to modern chemical and pharmacological research.

BACKGROUND: Lonicera Linn. belonging to the family Caprifoliaceae, the largest genus in the plant family, includes about more than 200 species, which are mainly distributed in northern Africa, North America, Europe and Asia. Some species of this genus have been usually used in traditional Chinese medicine as well as functional foods, cosmetics and other applications, such as L. japonica Thunb. Bioactive components and pharmacological activities of the genus Lonicera plants have received an increasing interest from the scientific community. Thus, a comprehensive and systematic review on their traditional usage in China, chemical components, and their pharmacological properties of their whole plants, bioactive extracts, and bioactive isolates including partial structure-activity relationships from the genus is indispensable. METHODS: Information on genus Lonicera of this systematic electronic literature search was gathered via the published articles, patents, clinical trials website (https://clinicaltrials.gov/) and several online bibliographic databases (PubMed, Sci Finder, Research Gate, Science Direct, CNKI, Web of Science and Google Scholar). The following keywords were used for the online search: Lonicera, phytochemical composition, Lonicerae japonica, Lonicera review articles, bioactivities of Lonicera, anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, anti-diabetic, and clinical trials. This review paper consists of a total of 225 papers covering the Lonicera genus from 1800 to 2021, including research articles, reviews, patents, and book chapters. RESULTS: In this review (1800s-2021), about 420 components from the genus of Lonicera Linn. including 87 flavonoids, 222 terpenoids, 51 organic acids, and other compounds, together with their pharmacological activities including anti-inflammatory, antiviral, antimicrobial, anticancer, hepatoprotective, antioxidant, neuroprotective, antidiabetic, anti-allergic, immunomodulatory effects, and toxicity were summarized. CONCLUSION: The relationship is discussed among their traditional usage, their pharmacological properties, and their chemical components, which indicate the genus Lonicera have a large prospect in terms of new drug exploitation, especially in COVID-19 treatment.

Secreted Expression of mRNA-Encoded Truncated ACE2 Variants for SARS-CoV-2 via Lipid-Like Nanoassemblies.

The transfer of foreign synthetic messenger RNA (mRNA) into cells is essential for mRNA-based protein-replacement therapies. Prophylactic mRNA COVID-19 vaccines commonly utilize nanotechnology to deliver mRNA encoding SARS-CoV-2 vaccine antigens, thereby triggering the body's immune response and preventing infections. In this study, a new combinatorial library of symmetric lipid-like compounds is constructed, and among which a lead compound is selected to prepare lipid-like nanoassemblies (LLNs) for intracellular delivery of mRNA. After multiround optimization, the mRNA formulated into core-shell-structured LLNs exhibits more than three orders of magnitude higher resistance to serum than the unprotected mRNA, and leads to sustained and high-level protein expression in mammalian cells. A single intravenous injection of LLNs into mice achieves over 95% mRNA translation in the spleen, without causing significant hematological and histological changes. Delivery of in-vitro-transcribed mRNA that encodes high-affinity truncated ACE2 variants (tACE2v mRNA) through LLNs induces elevated expression and secretion of tACE2v decoys, which is able to effectively block the binding of the receptor-binding domain of the SARS-CoV-2 to the human ACE2 receptor. The robust neutralization activity in vitro suggests that intracellular delivery of mRNA encoding ACE2 receptor mimics via LLNs may represent a potential intervention strategy for COVID-19.