Targeting ROS production through inhibition of NADPH oxidases.

NADPH oxidases (NOXs) are transmembrane enzymes that are devoted to the production of reactive oxygen species (ROS). In cancers, dysregulation of NOX enzymes affects ROS production, leading to redox unbalance and tumor progression. Consequently, NOXs are a drug target for cancer therapeutics, although current therapies have off-target effects: there is a need for isoenzyme-selective inhibitors. Here, we describe fully validated human NOX inhibitors, obtained from an in silico screen, targeting the active site of Cylindrospermum stagnale NOX5 (csNOX5). The hits are validated by in vitro and in cellulo enzymatic and binding assays, and their binding modes to the dehydrogenase domain of csNOX5 studied via high-resolution crystal structures. A high-throughput screen in a panel of cancer cells shows activity in selected cancer cell lines and synergistic effects with KRAS modulators. Our work lays the foundation for the development of inhibitor-based methods for controlling the tightly regulated and highly localized ROS sources.

Carrier protein mediated cargo sensing in quorum signal synthases.

Acyl-homoserine lactone synthases make specific AHL quorum sensing signals to aid virulence in Gram-negative bacteria. Here, we use solution NMR spectroscopy to demonstrate that the carrier protein-enzyme interface accurately reveals substrate recognition mechanisms in two quorum signal synthases.

Perceived Risk and Associated Shielding Behaviors in Patients With Rheumatoid Arthritis During the Coronavirus 2019 Pandemic.

OBJECTIVE: To investigate the perceived risk of coronavirus disease 2019 (COVID-19) infection and outcomes as well as shielding practices among patients with rheumatoid arthritis (RA) during the COVID-19 pandemic. METHODS: We surveyed participants with RA in a large health care system between July 16 and November 8, 2020. Participants reported RA treatment, COVID-19 risk perception, and shielding practices (eg, masks, social distancing, and quarantining). We examined the association of demographic and disease-specific factors with risk perception and the association of risk perception with shielding practices. RESULTS: Of 494 participants, 195 (40%), 169 (34%), and 130 (26%) strongly agreed, agreed, or were uncertain/disagreed that their RA put them at higher risk for COVID-19 or poor outcomes, respectively. Younger age (odds ratio [OR]: 0.98), having a comorbidity (OR: 1.60), and biologic disease-modifying antirheumatic drug (bDMARD) use (OR: 1.75) were independently associated with a higher perceived risk. Among those who strongly agreed, agreed, or were uncertain/disagreed that they had greater risk, 165 (85%), 118 (70%), and 69 (53%), respectively, practiced all three shielding measures (P < 0.0001). Those who strongly agreed or agreed that they were at higher risk were more likely to use all three shielding practices (OR: 4.16 and 1.97, respectively). bDMARD use and glucocorticoid use were associated with using all three shielding measures (OR: 1.99 and 1.81, respectively). CONCLUSION: Perception of COVID-19 risk among patients with RA varies substantially. Factors associated with perceived risk are different from those found to be associated with worse outcomes in observational studies. Greater perceived risk is associated with more strict shielding, which has implications for patient education and mental health.