Dynamics of lipid analogs in the E. coli outer membrane

While there have been many studies on the diffusion of membrane lipids in eukaryotic cells, which have given insight into the structure and organization of these membranes, little is known to date of their mobility in bacterial membranes, specifically the Gram negative bacteria, Escherichia coli. The E. coli outer envelope consists of inner and outer lipid membranes that are separated by a periplasmic space containing the cell wall. The outer membrane is unique in that it is thinner than mammalian plasma membranes and consists of a phospholipid inner leaflet with a predominantly lipopolysaccharide (LPS) outer leaflet. Here we look at the diffusion of the fluorescent lipid analogs DiI, FAST DiO, and TopFluor-PC in the outer membrane of liveE. coli cells using single molecule imaging/tracking techniques. Lipid analog dynamics are compared in several cells – E. coli with no O antigen (wild type),E. coli with no core oligosaccharids (ΔrfaC), and a mammalian cell line (KB) – at several sampling rates. Lipid analogs deviate from free diffusion at time scales smaller than 30 fps for FAST DiO and smaller than 260 fps for TopFluor-PC. The diffusion of lipid analogs differs according to the charge of the headgroup and fatty acid composition. These differences give evidence for predictions that LPS plays a role in membrane structure and organization and may imply lipid phase separation in E. coli

Speed and Cumulative Responses According to Body Regions in Patients with Moderate-to-Severe Plaque Psoriasis Treated with Ixekizumab (Interleukin-17A Antagonist) versus Guselkumab (Interleukin-23p19 Inhibitor)

Abstract Introduction When assessing the effect of a therapy for psoriasis (PsO), it is important to consider speed of response and cumulative response. However, responses among biologics may differ by body regions. This post hoc analysis compares speed of response and cumulative response for ixekizumab (IXE), an interleukin-17A antagonist, and guselkumab (GUS), an interleukin-23p19 inhibitor, in different body regions of patients with moderate-to-severe plaque PsO participating in the IXORA-R study, up to week 24. Methods The IXORA-R design has been previously described. Patients received the respective on-label dosing of IXE or GUS. The median time to first Psoriasis Area and Severity Index (PASI) 50, 75, 90, and 100 response (50%, 75%, 90%, and 100% improvement from baseline, respectively) and the cumulative days with clear skin for PASI 50, 75, 90, and 100 responses were assessed in four body regions: head, trunk, upper extremities, and lower extremities. Results A total of 1027 patients were enrolled and received IXE (N = 520) or GUS (N = 507). Median time to first PASI 50, 75, 90, and 100 response was shortest in the head region, followed by the remaining body regions in both IXE and GUS cohorts. In each body region, IXE was significantly faster than GUS (p < 0.001) in achieving PASI 50, 75, 90, and 100. Through 24 weeks, the number of days with clear skin for PASI 90 and 100 was greater in the head region, followed by trunk, upper extremities, and lastly lower extremities in both IXE and GUS cohorts. In each body region, through 24 weeks, patients on IXE experienced a significantly higher number of days with clear skin for PASI 50, 75, 90, and 100 than patients on GUS (p < 0.01). Conclusions As compared to GUS, IXE provided a faster skin clearance and more days with clear skin in all body regions of patients with moderate-to-severe plaque PsO through 24 weeks. Trial Registration Number https://www.clinicaltrials.gov/ : NCT03573323 (IXORA-R)

Long-term Efficacy and Safety of Up to 108 Weeks of Ixekizumab in Pediatric Patients With Moderate to Severe Plaque Psoriasis

About 1% of children and adolescents worldwide are affected by plaque psoriasis.To evaluate the long-term efficacy and safety of ixekizumab for pediatric patients with moderate to severe psoriasis.This multicenter randomized clinical trial (IXORA-PEDS) evaluated pediatric patients with plaque psoriasis. Participants were aged 6 years to younger than 18 years; had moderate to severe psoriasis, which was defined as Psoriasis Area and Severity Index (PASI) of 12 or higher, static Physician's Global Assessment (sPGA) score of 3 or higher, and psoriasis-affected body surface area of 10% or greater at screening and baseline; were candidates for phototherapy or systemic therapy; or had psoriasis that was not adequately controlled by topical therapies. Data analysis, which followed the intention-to-treat principle, was conducted from May to October 2021.Pediatric patients were randomized 2:1 to receive either a weight-based dose of ixekizumab every 4 weeks or placebo. After a 12-week placebo-controlled period, patients entered a 48-week, open-label ixekizumab maintenance period (weeks 12-60), followed by an extension period that lasted through 108 weeks. A substudy evaluated the randomized withdrawal of ixekizumab after week 60.Efficacy outcomes at week 108 included the percentage of patients achieving 75% (PASI 75), 90% (PASI 90), or 100% (PASI 100) improvement from baseline; an sPGA score of 0 or 1 or score of 0; and improvement of 4 points or higher from baseline in the Itch Numeric Rating Scale. Safety outcomes included assessments of adverse events (AEs), including treatment-emergent AEs, serious AEs, and AEs of special interest, as well as improvement from baseline in a range of challenging body areas. Missing data for categorical outcomes were imputed using modified nonresponder imputation.A total of 171 patients (mean [SD] age, 13.5 [3.04] years; 99 female children [57.9%]) were randomized to either ixekizumab (n = 115) or placebo (n = 56). Of 166 patients who entered the maintenance period, 139 (83.7%) completed week 108 of the trial. Primary and gated secondary end points were sustained through week 108, with patients achieving PASI 75 (91.7% [n = 86]), PASI 90 (79.0% [n = 74]), PASI 100 (55.1% [n = 52]), sPGA 0 or 1 (78.3% [n = 74]), and sPGA 0 (52.4% [n = 49]). Fifty-five patients (78.5%) reported an Itch Numeric Rating Scale improvement of 4 points or higher. In patients who received ixekizumab, at week 108, clearance of nail psoriasis was reported in 68.1% (n = 28), clearance of palmoplantar psoriasis was reported in 90.0% (n = 10), clearance of scalp psoriasis was reported in 76.2% (n = 83), and clearance of genital psoriasis was reported in 87.5% (n = 24). There were no new safety findings during weeks 48 to 108 of the trial, including no new cases of inflammatory bowel disease or candida infection.Results of this study showed improvements across patient-reported outcomes and objective measures of complete skin clearance of psoriasis among pediatric patients who received ixekizumab, and these response rates were sustained through week 108 of the trial. Safety of ixekizumab was consistent with previously reported findings in this population and the known safety profile of this treatment.ClinicalTrials.gov Identifier: NCT03073200