Posted by The emergence and mutation of pathogenic viruses have been occurring at an unprecedented rate in recent decades. The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has developed into a global public health crisis due to extensive viral transmission. In situ RNA mapping has revealed angiotensin-converting enzyme 2 (ACE2) expression to be highest in the nose and lower in the lung, pointing to nasal susceptibility as a predominant route for infection and the cause of subsequent pulmonary effects. By blocking viral attachment and entry at the nasal airway using a cyclodextrin-based formulation, a preventative therapy can be developed to reduce viral infection at the site of entry. Here, we assess the safety and antiviral efficacy of cyclodextrin-based formulations. From these studies, hydroxypropyl beta-cyclodextrin (HPBCD) and hydroxypropyl gamma-cyclodextrin (HPGCD) were then further evaluated for antiviral effects using SARS-CoV-2 pseudotypes. Efficacy findings were confirmed with SARS-CoV-2 Delta variant infection of Calu-3 cells and using a K18-hACE2 murine model. Intranasal pre-treatment with HPBCD-based formulations reduced viral load and inflammatory signaling in the lung. In vitro efficacy studies were further conducted using lentiviruses, murine hepatitis virus (MHV), and influenza A virus subtype H1N1. These findings suggest HPBCD may be used as an agnostic barrier against transmissible pathogens, including but not limited to SARS-CoV-2.
HPBCD and HPGCD inhibit the SARS-CoV-2 pseudotype in a concentration-dependent manner. A549-ACE2 cells were pre-treated with CD formulations (A) HPBCD, (B) HPGCD, or (C) SBECD for 1 h. Cells were washed 3X with PBS before replacement with a complete cell culture medium. Cells were infected with the SARS-CoV-2 Wuhan (D614G mutant) pseudotype for 8 h. Twenty-four hpi cells were lysed for luciferase readout. The control is the no-treatment comparator. ** p < 0.01, *** p < 0.001, **** p < 0.0001.
Both HPBCD and HPGCD were able to reduce Wuhan D614G mutant SARS-CoV-2 pseudotype infection by greater than 50% at concentrations as low as 0.5% w/v. In contrast, SBECD exhibits variable efficacy across increasing concentrations, with 0.5% w/v significantly reducing intracellular pseudotype infection. Interestingly, higher concentrations > 5% w/v did not improve SBECD effectiveness.
Cyclodextrin sequestration of viral and cellular cholesterol. (A) Unsequestered viral-bound cholesterol was quantified after 2 h of treatment with either HPBCD or HPGCD and separation of the virus CD complex via a 50 kDa centrifugal filter unit. Detection of cholesterol was quantified using the Amplex Red reagent-based assay. Fluorescence was measured with a microplate reader using an excitation/emission of 560/590. (B) Unsequestered cell membrane-bound cholesterol was quantified after 2 h of treatment with 0–10% w/v HPBCD. (C) Cell membrane-bound cholesterol was quantified after 2 h of treatment with 0–10% w/v HPGCD. One-way ANOVA followed by Dunnett’s test for multiple comparisons to a common control group revealed treatment-based statistical significance (*** p < 0.001, **** p < 0.0001).
HPBCD and HPGCD were able to reduce membrane-bound cellular cholesterol. A greater than 50% reduction in cell membrane-bound cholesterol is observed with 2.5% HPBCD or HPGCD (p < 0.001). While HPBCD also reduces cellular cholesterol in a concentration-dependent manner, HGBCD had no detectable difference at greater than 2.5% w/v These results may suggest that HPGCD has a greater safety profile compared to HPBCD, as higher concentrations do not deplete cellular cholesterol further.
Lu, A.; Ebright, B.; Naik, A.; Tan, H.L.; Cohen, N.A.; Bouteiller, J.-M.C.; Lazzi, G.; Louie, S.G.; Humayun, M.S.; Asante, I. Hydroxypropyl-Beta Cyclodextrin Barrier Prevents Respiratory Viral Infections: A Preclinical Study. Int. J. Mol. Sci. 2024, 25, 2061. https://doi.org/10.3390/ijms25042061