Traditional medicines have reportedly treated SARS-CoV-2 infection. Substantial evidence shows that fish oil supplements promote human immune function, suggesting they may lessen susceptibility to SARS-CoV-2 infection and suppress viral replication by inducing interferon. Fish oil was subjected to partition chromatography and separated into two compounds (EP01 and DH01). Isolated compounds were purified and characterized using UV, FTIR, NMR, and mass spectrometry to confirm their identity. Molecular docking was studied on the SARS CoV-2 variants of concern; SARS CoV-2 WT (PDB: 6VXX), SARS CoV-2 Alpha variant (PDB: 7LWS), SARS CoV-2 Delta variant (PDB: 7TOU), SARS CoV-2 Gamma variant (PDB: 7V78), SARS CoV-2 Kappa variant (PDB: 7VX9), and SARS CoV-2 Omicron variant (PDB: 7QO7) and TMPRSS2 (PDB: 7Y0E). Further selected protein-ligand complexes were subjected to 100 ns MD simulations to predict their biological potential in the SARS-CoV-2 treatment. In-vitro biological studies were carried out to support in-silico findings. Isolated compounds EP01 and DH01 were identified as 5-Tridecyltetrahydro-2H-pyran-2-one and 5-Heptadecyltetrahydro-2H-pyran-2-one, respectively. The compound EP01 significantly reduced (93.24 %) the viral RNA copy number with an IC50 of ~8.661 μM. EP01 proved to be a potent antiviral by in-vitro method against the SARS-CoV-2 clinical isolate, making it a promising antiviral candidate, with a single dose capable of preventing viral replication.

A multistep priming process involving furin and endosomal cathepsin B and L (CatB/L) has been described for the Orthoebolavirus zairense (EBOV) glycoprotein GP. Inhibition or knockdown of either furin or endosomal cathepsins, however, did not prevent virus multiplication in cell cultures. Moreover, an EBOV mutant lacking the furin cleavage motif (RRTRR→AGTAA) was able to replicate and cause fatal disease in nonhuman primates, indicating that furin cleavage may be dispensable for virus infectivity. Here, by using protease inhibitors and EBOV GP-carrying recombinant vesicular stomatitis virus (VSV) and transcription and replication-competent virus-like particles (trVLPs) we found that processing of EBOV GP is mediated by different proteases in different cell lines depending on the protease repertoire available. Endosomal cathepsins were essential for EBOV GP entry in Huh-7 but not in Vero cells, in which trypsin-like proteases and stably expressed trypsin-like transmembrane serine protease 2 (TMPRSS2) supported wild-type EBOV GP and EBOV GP_AGTAA mutant entry. Furthermore, we show that the EBOV GP_AGTAA mutant is cleaved into fusion-competent GP2 by TMPRSS2 and by CatL at a so far unknown site. Fluorescence microscopy co-localization studies indicate that EBOV GP cleavage by TMPRSS2 may occur in the TGN prior to virus release or in the late endosome at the stage of virus entry into a new cell. Our data show that EBOV GP must be proteolytically activated to support virus entry but has even greater flexibility in terms of proteases and the precise cleavage site than previously assumed.

The entry of coronaviruses is initiated by spike recognition of host cellular receptors, involving proteinaceous and/or glycan receptors. Recently, TMPRSS2 was identified as the proteinaceous receptor for HCoV-HKU1 alongside sialoglycan as a glycan receptor. However, the underlying mechanisms for viral entry remain unknown. Here, we investigated the HCoV-HKU1C spike in the inactive, glycan-activated, and functionally anchored states, revealing that sialoglycan binding induces a conformational change of the NTD and promotes the neighboring RBD of the spike to open for TMPRSS2 recognition, exhibiting a synergistic mechanism for the entry of HCoV-HKU1. The RBD of HCoV-HKU1 features an insertion subdomain that recognizes TMPRSS2 through three previously undiscovered interfaces. Furthermore, structural investigation of HCoV-HKU1A in combination with mutagenesis and binding assays confirms a conserved receptor recognition pattern adopted by HCoV-HKU1. These studies advance our understanding of the complex viral-host interactions during entry, laying the groundwork for developing new therapeutics against coronavirus-associated diseases.

The human coronavirus HKU1 spike (S) glycoprotein engages host cell surface sialoglycans and transmembrane protease serine 2 (TMPRSS2) to initiate infection. The molecular basis of HKU1 binding to TMPRSS2 and determinants of host receptor tropism remain elusive. We designed an active human TMPRSS2 construct enabling high-yield recombinant production in human cells of this key therapeutic target. We determined a cryo-electron microscopy structure of the HKU1 RBD bound to human TMPRSS2, providing a blueprint of the interactions supporting viral entry and explaining the specificity for TMPRSS2 among orthologous proteases. We identified TMPRSS2 orthologs from five mammalian orders promoting HKU1 S-mediated entry into cells along with key residues governing host receptor usage. Our data show that the TMPRSS2 binding motif is a site of vulnerability to neutralizing antibodies and suggest that HKU1 uses S conformational masking and glycan shielding to balance immune evasion and receptor engagement.

The pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health concern. Cell entry of SARS-CoV-2 depends on viral spike (S) proteins binding to cellular receptors (ACE2) and their subsequent priming by host cell proteases (TMPRSS2). Assessing effects of viral-induced host response factors and determining which cells are used by SARS-CoV-2 for entry might provide insights into viral transmission, add clarity to the virus\' pathogenesis, and possibly reveal therapeutic targets. Mast cells (MCs) are ubiquitously expressed tissue cells that act as immune sentinels given their ability to react specifically to pathogens at environmental interfaces, such as in the lung. Several lines of evidence suggest a critical role for MCs in SARS-CoV-2 infections based on patients\' mediator profiles, especially the \"cytokine storm\" responsible for most morbidity and mortality. In this pilot study, we demonstrated that human lung MCs (n = 3 donors) are a source of renin and that they upregulate the membrane receptor for SARS-CoV-2 (ACE2) as well as the protease required for cellular entry (TMPRSS2) under certain conditions. We hypothesized that infection of human MCs with SARS-CoV-2 may be a heretofore-unrecognized mechanism of viral pathogenesis, and further studies are required to assess this question.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic. Known as COVID-19, it has affected billions of people worldwide, claiming millions of lives and posing a continuing threat to humanity. This is considered one of the most extensive pandemics ever recorded in human history, causing significant losses to both life and economies globally. However, the available evidence is currently insufficient to establish the effectiveness and safety of antiviral drugs or vaccines. The entry of the virus into host cells involves binding to angiotensin-converting enzyme 2 (ACE2), a cell surface receptor, via its spike protein. Meanwhile, transmembrane protease serine 2 (TMPRSS2), a host surface protease, cleaves and activates the virus\'s S protein, thus promoting viral infection. Plant protease inhibitors play a crucial role in protecting plants against insects and/or microorganisms. The major storage proteins in sweet potato roots include sweet potato trypsin inhibitor (SWTI), which accounts for approximately 60% of the total water-soluble protein and has been found to possess a variety of health-promoting properties, including antioxidant, anti-inflammatory, ACE-inhibitory, and anticancer functions. Our study found that SWTI caused a significant reduction in the expression of the ACE2 and TMPRSS2 proteins, without any adverse effects on cells. Therefore, our findings suggest that the ACE2 and TMPRSS2 axis can be targeted via SWTI to potentially inhibit SARS-CoV-2 infection.

BACKGROUND: TMPRSS2, a key molecule for SARS-CoV-2 invading human host cells, has an association with cancer. However, its association with lung cancer remains insufficiently unexplored.
METHODS: In five bulk transcriptomics datasets, one single-cell RNA sequencing (scRNA-seq) dataset and one proteomics dataset for lung adenocarcinoma (LUAD), we explored associations between TMPRSS2 expression and immune signatures, tumor progression phenotypes, genomic features, and clinical prognosis in LUAD by the bioinformatics approach. Furthermore, we performed experimental validation of the bioinformatics findings.
RESULTS: TMPRSS2 expression levels correlated negatively with the enrichment levels of both immune-stimulatory and immune-inhibitory signatures, while they correlated positively with the ratios of immune-stimulatory/immune-inhibitory signatures. It indicated that TMPRSS2 levels had a stronger negative correlation with immune-inhibitory than with immune-stimulatory signatures. TMPRSS2 downregulation correlated with increased proliferation, stemness, genomic instability, tumor progression, and worse survival in LUAD. We further validated that TMPRSS2 was downregulated with tumor progression in the LUAD cohort we collected from Jiangsu Cancer Hospital, China. In vitro and in vivo experiments verified the association of TMPRSS2 deficiency with increased tumor cell proliferation and invasion and antitumor immunity in LUAD. Moreover, in vivo experiments demonstrated that TMPRSS2-knockdown tumors were more sensitive to BMS-1, an inhibitor of PD-1/PD-L1.
CONCLUSIONS: TMPRSS2 is a tumor suppressor, while its downregulation is a positive biomarker of immunotherapy in LUAD. Our data provide a potential link between lung cancer and pneumonia caused by SARS-CoV-2 infection.

The TMPRSS2 protease plays a key role in the entry of the SARS-CoV-2 into cells. The TMPRSS2 gene is highly polymorphic in humans, and some polymorphisms may affect the susceptibility to COVID-19 or disease severity. rs75603675 (c.23G > T) is a missense variant that causes the replacement of glycine with valine at position 8 (p.G8V) in the TMPRSS2 isoform 1. According to GnomAD v4.0.0 database, the allele frequency of the rs75603675 on a global scale is 38.10 %, and range from 0.92 % in East Asian to 40.77 % in non-Finnish European (NFE) population. We analyzed the occurrence of the rs75603675 in two cohorts of patients, the first with severe/critical COVID-19 enrolled in a French hospital (42 patients), and the second with predominantly asymptomatic/pauci-symptomatic/mild COVID-19 enrolled in an Italian hospital (69 patients). We found that the TMPRSS2-c.23T minor allele frequency was similar in the two cohorts, 46.43 % and 46.38 %, respectively, and higher than the frequency in the NFE population (40.77 %). Chi-square test provided significant results (p < 0.05) when the genotype data (TMPRSS2-c.23T/c.23T homozygotes + TMPRSS2-c.23G/c.23T heterozygotes vs. TMPRSS2-c.23G/c.23G homozygotes) of the two patient groups were pooled and compared to the expected data for the NFE population, suggesting a possible pathogenetic mechanism of the p.G8V substitution. We explored the possible effects of the p.G8V substitution and found that the N-terminal region of the TMPRSS2 isoform 1 contains a signal for clathrin/AP-2-dependent endocytosis. In silico analysis predicted that the p.G8V substitution may increase the accessibility to the endocytic signal, which could help SARS-CoV-2 enter cells.

UNASSIGNED: Pre-existing liver disease is a risk factor for the worse prognosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to evaluate whether chronic hepatitis B (CHB) and hepatocellular carcinoma (HCC) affect the expression of viral receptor angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in the liver.
UNASSIGNED: Twelve pairs of matched liver tissues of HCC and para-carcinoma were collected from the First Affiliated Hospital of Zhejiang University School of Medicine. And 20 liver biopsies from CHB patients were collected from Peking University People\'s Hospital. The expression of ACE2 and TMRPSS2 were detected using immunofluorescence staining, western blot, and RT-qPCR. The effects of hepatitis B virus (HBV) replication or interferon on ACE2 and TMPRSS2 expression were tested in hepatic cell lines.
UNASSIGNED: The mRNA expression of TMPRSS2 in HCC tissues was six-fold higher than that of para-carcinoma tissues (P = 0.002), whereas that of ACE2 was not statistically different between HCC and para-carcinoma tissues. Hepatocellular ACE2 expression was detected in 35% (7/20) of CHB patients and mostly distributed in the inflammatory areas. However, there was no difference in TMPRSS2 expression between areas with or without inflammation. IFN-α2b slightly induced ACE2 expression (2.4-fold, P = 0.033) in HepG2 cells but not in Huh-7, QSG-7701, and L-02 cells. IFN-α2b did not affect TMPRSS2 expression in these cell lines. In addition, HBV replication did not alter ACE2 expression in HepAD38 cells.
UNASSIGNED: Although HBV replication does not directly affect the expression of ACE2 and TMPRSS2, intrahepatic inflammation and carcinogenesis may increase their expression in some patients, which, in turn, may facilitate SARS-CoV-2 infection in hepatocytes.

Mast cells have a detrimental impact on coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Sambou Bamboo salt™ (BS) suppresses mast cell-mediated inflammatory response and enhances immunity. In this study, we investigated the regulatory effects of BS on expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane protease/serine subfamily member 2 (TMPRSS2) in human mast cell line (HMC)-1 cells. BS resulted in significant reductions in expression levels of ACE2 and TMPRSS2 in activated HMC-1 cells. Levels of tryptase were reduced by BS. In addition, BS blocked activation of activator protein 1 (AP-1), c-Jun NH2-terminal kinases (JNK), p38, and phosphatidylinositide-3-kinase (PI3K) in activated HMC-1 cells. Therefore, these results show that BS reduces levels of ACE2, TMPRSS2, and tryptase by inhibiting AP-1/JNK/p38/PI3K signaling pathways in mast cells. These findings can serve as valuable foundational data for the development of therapeutic agents aimed at preventing SARS-CoV-2 infection.