Biology subjects

O'Donoghue, A.

Publications and source records attributed to O'Donoghue, A..

3 recordsLinked to original sources

bioRxiv2020

Potent in vitro anti-SARS-CoV-2 activity by gallinamide A and analogues via inhibition of cathepsin L

The emergence of SARS-CoV-2 in late 2019, and the subsequent COVID-19 pandemic, has led to substantial mortality, together with mass global disruption. There is an urgent need for novel antiviral drugs for therapeutic or prophylactic application. Cathepsin L is a key host cysteine protease utilized by coronaviruses for cell entry and is recognized as a promising drug target. The marine natural product, gallinamide A and several synthetic analogues, were identified as potent inhibitors of cathepsin L activity with IC50 values in the picomolar range. Lead molecules possessed selectivity over cathepsin B and other related human cathepsin proteases and did not exhibit inhibitory activity against viral proteases Mpro and PLpro. We demonstrate that gallinamide A and two lead analogues potently inhibit SARS-CoV-2 infection in vitro, with EC50 values in the nanomolar range, thus further highlighting the potential of cathepsin L as a COVID-19 antiviral drug target.

biochemistry↗

bioRxiv2020

A cysteine protease inhibitor blocks SARS-CoV-2 infection of human and monkey cells

K777 is a di-peptide analog that contains an electrophilic vinyl-sulfone moiety and is a potent, covalent inactivator of cathepsins. Vero E6, HeLa/ACE2, Caco-2, A549/ACE2, and Calu-3, cells were exposed to SARS-CoV-2, and then treated with K777. K777 reduced viral infectivity with EC50 values of inhibition of viral infection of: 74 nM for Vero E6, <80 nM for A549/ACE2, and 4 nM for HeLa/ACE2 cells. In contrast, Calu-3 and Caco-2 cells had EC50 values in the low micromolar range. No toxicity of K777 was observed for any of the host cells at 10-100 M inhibitor. K777 did not inhibit activity of the papain-like cysteine protease and 3CL cysteine protease, encoded by SARS-CoV-2 at concentrations of [≤] 100 M. These results suggested that K777 exerts its potent anti-viral activity by inactivation of mammalian cysteine proteases which are essential to viral infectivity. Using a propargyl derivative of K777 as an activity-based probe, K777 selectively targeted cathepsin B and cathepsin L in Vero E6 cells. However only cathepsin L cleaved the SARS-CoV-2 spike protein and K777 blocked this proteolysis. The site of spike protein cleavage by cathepsin L was in the S1 domain of SARS-CoV-2, differing from the cleavage site observed in the SARS CoV-1 spike protein. These data support the hypothesis that the antiviral activity of K777 is mediated through inhibition of the activity of host cathepsin L and subsequent loss of viral spike protein processing. SIGNIFICANCEThe virus causing COVID-19 is highly infectious and has resulted in a global pandemic. We confirm that a cysteine protease inhibitor, approved by the FDA as a clinical-stage compound, inhibits SARS-CoV-2 infection of several human and monkey cell lines with notable(nanomolar) efficacy. The mechanism of action of this inhibitor is identified as a specific inhibition of host cell cathepsin L. This in turn inhibits host cell processing of the coronaviral spike protein, a step required for cell entry. Neither of the coronaviral proteases are inhibited, and the cleavage site of spike protein processing is different from that reported in other coronaviruses. Hypotheses to explain the differential activity of the inhibitor with different cell types are discussed.

biochemistry↗

bioRxiv2020

Role of Inflammasome-independent Activation of IL-1β by the Pseudomonas aeruginosa Protease LasB

Pulmonary damage by Pseudomonas aeruginosa during cystic fibrosis lung infection and ventilator-associated pneumonia is mediated both by pathogen virulence factors and host inflammation. Impaired immune function due to tissue damage and inflammation, coupled with pathogen multidrug resistance, complicates management of these deep-seated infections. Therefore, preservation of lung function and effective immune clearance may be enhanced by selectively controlling inflammation. Pathological inflammation during P. aeruginosa pneumonia is driven by interleukin-1{beta} (IL-1{beta}). This proinflammatory cytokine is canonically regulated by caspase-family inflammasome proteases, but we report that plasticity in IL-1{beta} proteolytic activation allows for its direct maturation by the pseudomonal protease LasB. LasB promotes IL-1{beta} activation, neutrophilic inflammation, and destruction of lung architecture characteristic of severe P. aeruginosa pulmonary infection. Discovery of this IL-1{beta} regulatory mechanism provides a distinct target for anti-inflammatory therapeutics, such that matrix metalloprotease inhibitors blocking LasB limit inflammation and pathology during P. aeruginosa pulmonary infections. HighlightsO_LIIL-1{beta} drives pathology during pulmonary infection by Pseudomonas aeruginosa. C_LIO_LIThe Pseudomonas protease LasB cleaves and activates IL-1{beta} independent of canonical and noncanonical inflammasomes C_LIO_LIMetalloprotease inhibitors active against LasB limit inflammation and bacterial growth C_LI Research in ContextInflammation is highly damaging during lung infections by the opportunistic pathogen Pseudomonas aeruginosa. Sun et al. demonstrate that the Pseudomonas LasB protease directly activates IL-1{beta} in an inflammasome-independent manner. Inhibition of IL-1{beta} conversion by LasB protects against neutrophilic inflammation and destruction of the lung. Adjunctive therapeutics that limit pathological inflammation induced by infection would be beneficial for the treatment of pulmonary infections when used with conventional antibiotics.

microbiology↗