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-specific T cells 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. Generalised 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 viral loads ≥10,000 CMV DNA copies/mL were given ganciclovir. In this group, the frequency of CD4+ and CD8+ T cells producing IFN-γ and the CD8+CD57+GB+ T cell population increased at 12-24 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+GB+ 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