ABSTRACT
The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is a global concern and necessitates efficient drug antagonists. Angiotensin-converting enzyme-2 (ACE2) is the main receptor of SARS-CoV-2 spike 1 (S1), which mediates viral invasion into host cells. Herein, we designed and prepared short peptide inhibitors containing 4-6 critical residues of ACE2 that contribute to the interaction with SARS-CoV-2 S1. Among the candidates, a peptide termed GK-7 (GKGDFRI), which was designed by extracting residues ranging from Gly353 to Ile359 in the ligand-binding domain of ACE2, exhibited the highest binding affinity (25.1 nM) with the SARS-CoV-2 spike receptor-binding domain (RBD). GK-7 bound to the RBD and decreased SARS-CoV-2 S1 attachment to A549 human alveolar epithelial cells. Owing to spike blockade, GK-7 inhibited SARS-CoV-2 spike pseudovirion infection in a dose-dependent manner, with a half-maximal inhibitory concentration of 2.96 µg/mL. Inspiringly, pulmonary delivery of GK-7 by intranasal administration did not result in toxicity in mice. This study revealed an easy-to-produce peptide inhibitor for SARS-CoV-2 spike blockade, thus providing a promising candidate for COVID-19 treatment.
Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , COVID-19 Drug Treatment , Peptides/pharmacology , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/metabolism , Animals , COVID-19/metabolism , COVID-19/virology , Cell Line , Humans , Male , Mice , Mice, Inbred BALB C , Molecular Docking Simulation , Peptides/chemistry , Protein Binding , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolismABSTRACT
OBJECTIVE: To study the clinicopathologic features, immunohistochemical findings, diagnosis and differential diagnosis of atypical teratoid/rhabdoid tumors (AT/RT) of central nervous system in childhood. METHODS: The clinicopathologic data, morphologic features and immunophenotypes were reviewed in 6 cases of AT/RT. EnVision method was applied. Antibodies include cytokeratin (CK), epithelial membrane antigen (EMA), vimentin, smooth muscle actin (SMA), muscle specific actin (MSA), glial fibrinary acid protein (GFAP), desmin, placental alkaline phosphatase (PLAP) and INI1. RESULTS: Five of the six cases of AT/RT occurred in infancy and early childhood. Histologically, the predominant component was rhabdoid cells. Cytoplasmic inclusions were present in all cases. Primitive neuroectodermal tumor (PNET) component was also identified in 5 of the 6 cases studied. Immunohistochemically, the tumor cells were positive for cytokeratin, epithelial membrane antigen and vimentin. The staining for INI1, desmin and PLAP was negative. Smooth muscle actin was expressed in 2 cases and glial fibrillary acidic protein in 5 cases. The proliferative index as demonstrated by Ki-67 staining was high. CONCLUSIONS: AT/RT is not a particularly uncommon malignancy in childhood. The histologic hallmark is the presence of rhabdoid cells with cytoplasmic inclusions. The tumor cells are positive for cytokeratin, epithelial membrane antigen and vimentin, and negative for INI1. Differential diagnosis includes PNET, medulloblastoma and medullomyoblastoma.
