Three-Month Results of Brolucizumab Intravitreal Therapy in Patients with Wet Age-Related Macular Degeneration

The purpose of the study was to evaluate changes in best corrected visual acuity, central retinal thickness, area and flow in the neovascular membrane and to compare therapeutic outcomes from baseline in patients who received three doses of Beovu (brolucizumab) at three-month follow-up. Material and methods: A prospective observational study conducted at the Prof. K. Gibiński University Clinical Center of the Medical University of Silesia in Katowice. Eight patients with exudative form of age-related macular degeneration (AMD) were observed. Results: The mean best corrected visual acuity (BCVA) outcome increased with each subsequent visit. The mean central retinal thickness (CRT) result also improved (decreased) with each subsequent visit, except for the last measurement. A statistically significant change in neovascular membrane area was observed after the first injection. In further treatment, the membrane area underwent changes that were not statistically significant. A statistically significant change in neovascular membrane flow was demonstrated after the first and second injections. Discussion: Our study confirmed the efficacy of brolucizumab in the treatment of patients with exudative AMD in terms of improvements in best corrected visual acuity (BCVA), central retinal thickness (CRT), neovascular membrane area, and neovascular membrane flow area.

Rapid propagation of membrane tension at a presynaptic terminal

Many cellular activities, such as cell migration1, cell division, signaling, infection, phagocytosis and exo-endocytosis, generate membrane tension gradients that in turn regulate them. Moreover, membrane flows, which are driven by tension gradients, can limit exo-endocytosis coupling in space and time, as net membrane flow from exocytic to endocytic sites is required to maintain membrane homeostasis. However, there is controversy over how rapidly plasma membrane flows can relax tension gradients; contrary to the common view, recent work showed membrane tension does not equilibrate in several cell types. Here we show membrane tension can propagate rapidly or slowly, spanning orders of magnitude in speed, depending on cell type. In a neuronal terminal specialized for rapid synaptic vesicle turnover and where exo-endocytosis events occur at distinct loci, membrane tension equilibrates within seconds. By contrast, membrane tension does not propagate in neuroendocrine adrenal chromaffin cells secreting catecholamines. Thus, slow membrane flow and tension equilibration may confine exo- and exocytosis to the same loci. Stimulation of exocytosis causes a rapid, global decrease in the synaptic terminal membrane tension, which recovers slowly due to endocytosis. Our results demonstrate membrane tension propagates rapidly at neuronal terminals and varies during synaptic activity, likely contributing to exo-endocytosis coupling.

The Surface Protein Fructose-1, 6 Bisphosphate Aldolase of Klebsiella pneumoniae Serotype K1: Role of Interaction with Neutrophils

Hypermucoviscosity phenotypic Klebsiella pneumoniae (HV-Kp) serotype K1 is the predominant pathogen of a pyogenic liver abscess, an emerging infectious disease that often complicates septic metastatic syndrome in diabetic patients with poor sugar control. HV-Kpisolates were more resistant to neutrophil phagocytosis than non-HV-Kpisolates because of different pathogen-associated molecular patterns. The protein expression of HV-Kp after interaction with neutrophils is unclear. We studied KP-M1 (HV phenotype; serotype K1), DT-X (an acapsularmutant strain of KP-M1), and E. coli (ATCC 25922) with the model of Kp-infected neutrophils, using a comparative proteomic approach. One the identified protein, namely fructose-1, 6-bisphosphate aldolase (FBA), was found to be distributed in the KP-M1 after infecting neutrophils. Cell fractionation experiments showed that FBA is localized both to the cytoplasm and the outer membrane. Flow cytometry demonstrated that outer membrane-localized FBA was surface-accessible to FBA-specific antibody. The fba gene expression was enhanced in high glucose concentrations, which leads to increasing bacterial resistance to neutrophils phagocytosis and killing. The KP-M1 after FBA inhibitors and FBA-specific antibody treatment showed a significant reduction in bacterial resistance to neutrophils phagocytosis and killing, respectively, compared to KP-M1 without treatment. FBA is a highly conserved surface-exposed protein that is required for optimal interaction of HV-Kp to neutrophils.

Macropinocytosis-mediated membrane recycling drives neural crest migration by delivering F-actin to the lamellipodium

Individual cell migration requires front-to-back polarity manifested by lamellipodial extension. At present, it remains debated whether and how membrane motility mediates this cell morphological change. To gain insights into these processes, we perform live imaging and molecular perturbation of migrating chick neural crest cells in vivo. Our results reveal an endocytic loop formed by circular membrane flow and anterograde movement of lipid vesicles, resulting in cell polarization and locomotion. Rather than clathrin-mediated endocytosis, macropinosomes encapsulate F-actin in the cell body, forming vesicles that translocate via microtubules to deliver actin to the anterior. In addition to previously proposed local conversion of actin monomers to polymers, we demonstrate a surprising role for shuttling of F-actin across cells for lamellipodial expansion. Thus, the membrane and cytoskeleton act in concert in distinct subcellular compartments to drive forward cell migration.