Impact of SARS-CoV-2 infection on the recovery of peripheral blood mononuclear cells by density gradient.

SARS-CoV-2 virus infection is responsible for coronavirus disease (COVID-19), which is characterised by a hyperinflammatory response that plays a major role in determining the respiratory and immune-mediated complications of this condition. While isolating peripheral blood mononuclear cells (PBMCs) from whole blood of COVID-19 patients by density gradient centrifugation, we noticed some changes in the floating properties and in the sedimentation of the cells on density medium. Investigating this further, we found that in early phase COVID-19 patients, characterised by reduced circulating lymphocytes and monocytes, the PBMC fraction contained surprisingly high levels of neutrophils. Furthermore, the neutrophil population exhibited alterations in the cell size and in the internal complexity, consistent with the presence of low density neutrophils (LDNs) and immature forms, which may explain the shift seen in the floating abilities and that may be predictive of the severity of the disease. The percentage of this subset of neutrophils found in the PBMC band was rather spread (35.4 ± 27.2%, with a median 28.8% and IQR 11.6-56.1, Welch's t-test early phase COVID-19 versus blood donor healthy controls P < 0.0001). Results confirm the presence of an increased number of LDNs in patients with early stage COVID-19, which correlates with disease severity and may be recovered by centrifugation on a density gradient together with PBMCs.

Specific Immunity to Cytomegalovirus in Pediatric Cardiac Transplantation.

BACKGROUND: Cytomegalovirus (CMV) infection is implicated in endothelial dysfunction and graft damage after pediatric heart transplantation. CMV-specific immune responses are thought to be necessary for CMV viral control but there is little data in pediatric heart transplantation. METHODS: We studied 28 consecutive pediatric heart transplant recipients for 1 year posttransplant. CMV T-cell expressing IFN-γ, TNF-α, and IL-2 in response to ex vivo stimulation with CMV lysates or peptides were measured. Circulating cytokines were measured in plasma. Generalized Additive Models were applied to the data to model changes of cell population dynamics over time. RESULTS: CMV-specific T cell-mediated responses were impaired in the first 8 weeks posttransplant. During this period, 25% of patients had CMV viremia, of which those with VLs of 10 000 or more CMV deoxyribonucleic acid copies/mL were given ganciclovir. In this group, the frequency of CD4+ and CD8+ T cells producing IFN-γ and the CD8+CD57+ granzyme B+ T-cell population increased at 12 to 24 weeks and remained elevated for the duration of the study. CONCLUSIONS: We have shown that CMV viremia is associated with CMV-specific immune responses and increased CD8+CD57+ granzyme B+ cells at 1 year posttransplant; however, early responses were not predictive of impending CMV viremia. It remains to be seen if the early CMV immune response detected is associated with endothelial and allograft damage, in light of previous studies demonstrating increased vasculopathy in pediatric patients with CMV viremia.

Delivery of ENaC siRNA to epithelial cells mediated by a targeted nanocomplex: a therapeutic strategy for cystic fibrosis.

The inhibition of ENaC may have therapeutic potential in CF airways by reducing sodium hyperabsorption, restoring lung epithelial surface fluid levels, airway hydration and mucociliary function. The challenge has been to deliver siRNA to the lung with sufficient efficacy for a sustained therapeutic effect. We have developed a self-assembling nanocomplex formulation for siRNA delivery to the airways that consists of a liposome (DOTMA/DOPE; L), an epithelial targeting peptide (P) and siRNA (R). LPR formulations were assessed for their ability to silence expression of the transcript of the gene encoding the α-subunit of the sodium channel ENaC in cell lines and primary epithelial cells, in submerged cultures or grown in air-liquid interface conditions. LPRs, containing 50 nM or 100 nM siRNA, showed high levels of silencing, particularly in primary airway epithelial cells. When nebulised these nanocomplexes still retained their biophysical properties and transfection efficiencies. The silencing ability was determined at protein level by confocal microscopy and western blotting. In vivo data demonstrated that these nanoparticles had the ability to silence expression of the α-ENaC subunit gene. In conclusion, these findings show that LPRs can modulate the activity of ENaC and this approach might be promising as co-adjuvant therapy for cystic fibrosis.

Improved intracellular delivery of peptide- and lipid-nanoplexes by natural glycosides.

Targeted nanocarriers undergo endocytosis upon binding to their membrane receptors and are transported into cellular compartments such as late endosomes and lysosomes. In gene delivery the genetic material has to escape from the cellular compartments into the cytosol. The process of endosomal escape is one of the most critical steps for successful gene delivery. For this reason synthetic lipids with fusogenic properties such as 2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) are integrated into the nanocarriers. In this study we show that a natural, plant derived glycoside (SO1861) from Saponaria officinalis L. greatly improves the efficacy of lipid based as well as non-lipid based targeted nanoplexes consisting of a targeted K16 peptide with a nucleic acid binding domain and plasmid-DNA, minicircle-DNA or small interfering RNA (siRNA). By confocal live cell imaging and single cell analyses, we demonstrate that SO1861 augments the escape of the genetic cargo out of the intracellular compartments into the cytosol. Co-localisation experiments with fluorescence labelled dextran and transferrin indicate that SO1861 induces the release of the genetic cargo out of endosomes and lysosomes. However, the transduction efficacy of a lentivirus based gene delivery system was not augmented. In order to design receptor-targeted nanoplexes (LPD) with improved functional properties, SO1861 was integrated into the lipid matrix of the LPD. The SO1861 sensitized LPD (LPDS) were characterized by dynamic light scattering and transmission electron microscopy. Compared to their LPD counterparts the LPDS-nanoplexes showed a greatly improved gene delivery. As shown by differential scanning calorimetry SO1861 can be easily integrated into the lipid bilayer of glycerophospholipid model membranes. This underlines the great potential of SO1861 as a new transfection multiplier for non-viral gene delivery systems.

The role of the helper lipid on the DNA transfection efficiency of lipopolyplex formulations.

Multifunctional, lipopolyplex formulations comprising a mixture of cationic liposomes and cationic, receptor-targeting peptides have potential use in gene therapy applications. Lipopolyplex formulations described here are typically far more efficient transfection agents than binary lipoplex or polyplex formulations. It has been shown previously that the peptide component mediates both DNA packaging and targeting of the nanoparticle while in this report we investigate the contribution of the lipid component. We hypothesised that the lipid components synergise with the peptides in the transfection process by promoting endosomal escape after lipid bilayer fusion. Lipopolyplexes were prepared with cationic liposomes comprising DOTAP with either neutral lipid DOPE or DOPC. DOPE promotes fusogenic, inverted hexagonal lipid structures while DOPC promotes more stable laminar structures. Lipopolyplexes containing DOPE showed substantially higher transfection efficiency than those formulated with DOPC, both in vitro and in vivo. DOPE-containing lipopolyplexes showed rapid endosomal trafficking and nuclear accumulation of DNA while DOPC-containing formulations remained within the late endo-lysosomal compartments. These findings are consistent with previous finding for the role of DOPE in lipoplexes and support the hypothesis regarding the function of the lipid components in lipopolyplexes. These findings will help to inform future lipopolyplex design, strategies and clinical development processes.

Airway deposition of nebulized gene delivery nanocomplexes monitored by radioimaging agents.

Receptor-targeted nanocomplexes are nonviral vectors developed for gene delivery to the airway epithelium for the treatment of pulmonary disease associated with cystic fibrosis. The present study aimed to optimize the delivery of the nanocomplex by nebulization, and to monitor the in vivo deposition of radiolabeled vector in the airways of a large animal model by γ-camera scintigraphy. Large White weaner pigs were nebulized with nanocomplexes mixed with technetium-99m radiopharmaceuticals. The aerosol deposition scans suggested that the nebulized radiovectors were deposited mainly in the trachea-main bronchi and in the midregion of the lungs. The plasmid biodistribution, assessed by real-time PCR, correlated with the scintigraphy images. The highest plasmid copy numbers were found in the bronchial areas and in the tissues proximal to the main bronchi bifurcation. Immunohistochemistry detected transgene expression in the tracheal and bronchial ciliated epithelium. Histological analysis of lung tissue showed no evidence of inflammation, and no increase in inflammatory cytokines or inflammatory cells was detected in the bronchoalveolar lavage. The deposition of nebulized nanocomplexes coassociated with technetium-99m can be monitored by nuclear medicine techniques. The use of a noninvasive strategy to follow the delivery of the vector could improve the clinical management of patients undergoing cystic fibrosis gene therapy.

Nebulisation of receptor-targeted nanocomplexes for gene delivery to the airway epithelium.

BACKGROUND: Gene therapy mediated by synthetic vectors may provide opportunities for new treatments for cystic fibrosis (CF) via aerosolisation. Vectors for CF must transfect the airway epithelium efficiently and not cause inflammation so they are suitable for repeated dosing. The inhaled aerosol should be deposited in the airways since the cystic fibrosis transmembrane conductance regulator gene (CFTR) is expressed predominantly in the epithelium of the submucosal glands and in the surface airway epithelium. The aim of this project was to develop an optimised aerosol delivery approach applicable to treatment of CF lung disease by gene therapy. METHODOLOGY: The vector suspension investigated in this study comprises receptor-targeting peptides, cationic liposomes and plasmid DNA that self-assemble by electrostatic interactions to form a receptor-targeted nanocomplex (RTN) of approximately 150 nm with a cationic surface charge of +50 mV. The aerodynamic properties of aerosolised nanocomplexes produced with three different nebulisers were compared by determining aerosol deposition in the different stages of a Next Generation Pharmaceutical Impactor (NGI). We also investigated the yield of intact plasmid DNA by agarose gel electrophoresis and densitometry, and transfection efficacies in vitro and in vivo. RESULTS: RTNs nebulised with the AeroEclipse II BAN were the most effective, compared to other nebulisers tested, for gene delivery both in vitro and in vivo. The biophysical properties of the nanocomplexes were unchanged after nebulisation while the deposition of RTNs suggested a range of aerosol aerodynamic sizes between 5.5 µm-1.4 µm cut off (NGI stages 3-6) compatible with deposition in the central and lower airways. CONCLUSIONS: RTNs showed their ability at delivering genes via nebulisation, thus suggesting their potential applications for therapeutic interventions of cystic fibrosis and other respiratory disorders.