Phenotypic and genotypic adaptations in Pseudomonas aeruginosa biofilms following long-term exposure to an alginate oligomer therapy

Chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) evolve to generate environmentally adapted biofilm communities, leading to increased patient morbidity and mortality. OligoG CF-5/20, a low-molecular-weight inhaled alginate oligomer therapy, is currently in phase IIb/III clinical trials in CF patients. Experimental evolution of P. aeruginosa in response to OligoG CF-5/20 was assessed using a bead biofilm model allowing continuous passage (45 days; ∼245 generations). Mutants isolated after OligoG CF-5/20 treatment typically had a reduced biofilm-forming ability and altered motility profile. Genotypically, OligoG CF-5/20 provided no selective pressure on genomic mutations within morphotypes. Chronic exposure to azithromycin, a commonly prescribed antibiotic in CF patients, with or without OligoG CF-5/20 in the biofilm evolution model also had no effect on rates of resistance acquisition. Interestingly, however, cross-resistance to other antibiotics (e.g., aztreonam) was reduced in the presence of OligoG CF-5/20. Collectively, these findings show no apparent adverse effects from long-term exposure to OligoG CF-5/20, instead resulting in both fewer colonies with multidrug resistance (MDR)-associated phenotypes and improved antibiotic susceptibility of P. aeruginosa

Mucin structural interactions with an alginate oligomer mucolytic in cystic fibrosis sputum

Cystic fibrosis (CF) is an autosomal recessive, life-limiting condition characterized by progressive lung disease, which is a major cause of morbidity and mortality for these patients. The inhalation therapy, OligoG CF-5/20, is a low molecular weight (mean Mn 3200 g/mol) alginate oligomer, with a high guluronic acid content (>85%). The ability of OligoG CF-5/20 to enhance the activity of antimicrobial/antibiotic therapies, modify the rheological properties of CF sputum and interact with mucin, has previously been shown. To further characterize the physicochemical interactions of OligoG CF-5/20 with CF sputum, Fourier-transform infrared (FTIR) spectroscopy was used to analyze ex vivo sputum samples from adolescent CF patients (n = 13) following treatment with 0.2% OligoG CF-5/20. FTIR analysis confirmed the interaction of OligoG CF-5/20 with mucin glycans in CF sputum, which showed a shift in wavenumber from 1078 cm−1 to 1070 cm-1 and subsequent loss of the 1053 cm−1 peak in the OligoG CF-5/20 treated samples. OligoG CF-5/20 interaction with key terminal moieties in mucin were also evident, with a significant change in sulphation at wavenumber 1116 cm−1, suggesting a link with sulphated Lewis x antigen. There were also significant shifts at wavenumber 1637 cm-1 indicative of β-sheet conformational changes in the mucin peptide caused by action of OligoG. The alterations in charge of glycan and mucin structures support previous observations wherein OligoG CF-5/20 modifies the viscoelastic properties of CF sputum. These findings suggest a possible mechanism of action for the rheological changes observed with this novel therapy

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570