Elena Copreni

Neutrophil recruitment and airway epithelial cell involvement in chronic cystic fibrosis lung disease

The pathological hallmark of cystic fibrosis (CF) chronic inflammatory response is the massive neutrophil influx into the airways. This dysregulated neutrophil emigration may be caused by the abnormal secretion of chemoattractants by respiratory epithelial cells and polarised lymphocyte T-helper response. Neutrophils from CF patients have a different response to inflammatory mediators than neutrophils from normal subjects, indicating that they are primed in vivo before entering the CF airways. CF neutrophils secrete more myeloperoxidase and elastase, mobilise less opsonin receptors and release less L-selectin than non-CF neutrophils. Moreover, they show altered cytokine production and a dysregulated chemotaxis response. Laboratory studies now suggest that CFTR is involved in regulating some neutrophil functions and indicate that altered properties of CF neutrophils may depend on genetic factors. Current gene therapy approaches are targeted to the respiratory epithelium, but many hurdles oppose an efficient and efficacious CFTR gene transfer. The possibility of CFTR gene therapy-based approach targeting CF neutrophils at the hematopoietic stem cell level is discussed.

Serum albumin enhances polyethylenimine-mediated gene delivery to human respiratory epithelial cells.

The interaction of polyethylenimine (PEI) polyplexes with proteins in cystic fibrosis (CF) airway secretions poses a significant hurdle to this nonviral delivery system. The aim of this study was to evaluate whether albumin may increase the efficiency of PEI complexes in mediating gene transfer into respiratory epithelial cells in the presence of CF mucus.

Involvement of glycosaminoglycans in vesicular stomatitis virus G glycoprotein pseudotyped lentiviral vector-mediated gene transfer into airway epithelial cells

The involvement of surface molecules in HIV‐1‐derived lentivirus (LV)‐mediated transduction of airway epithelial cells has not been studied so far. The present study aimed to evaluate the role of glycosaminoglycans (GAGs) in gene transfer mediated by a third generation vesicular stomatitis virus G glycoprotein (VSV‐G) pseudotyped LV vector in an in vitro model of polarized airway epithelial cells.

Magnetically guided lentiviral‐mediated transduction of airway epithelial cells

Lentiviral (LV) vectors are able to only slowly and inefficiently transduce nondividing cells such as those of the airway epithelium. To address this issue, we have exploited the magnetofection technique in in vitro models of airway epithelium.

Role of biophysical parameters on ex vivo and in vivo gene transfer to the airway epithelium by polyethylenimine/albumin complexes

Efficient gene transfer to the airways by nonviral vectors is a function of different parameters, among which the size and the charge of the transfecting particles. The aim of this study was to determine the transfection efficiency of polyethylenimine (PEI)/albumin polyplexes in ex vivo and in vivo models of respiratory epithelium and to correlate it with biophysical characteristics of the particles. Complexes were obtained by adding different amounts of human serum albumin (HSA) to PEI polyplexes preformed in saline. The presence of HSA caused the formation of bigger and more negative polyplexes and increased PEI transfection efficiency in primary respiratory epithelial cells by 4-6-fold. For in vivo administration to the lung, PEI polyplexes were formed in water and optimized with respect to the N/ P ratio. PEI/pC-Luc complexes gave the highest luciferase expression at N/ P 15 when administered through the trachea. At this N/ P ratio, the size and the surface charge of albumin-containing polyplexes were not different as compared with plain PEI polyplexes. Formulation of PEI polyplexes in the presence of HSA or murine serum albumin (MSA) resulted in a 2-fold increase in luciferase expression. In mice treated with PEI or PEI/MSA polyplexes containing the nuclear beta-gal gene, X-gal staining revealed that transfected cells localized at the bronchiolar epithelium and that PEI/MSA transfected four times as many cells as PEI ( p < 0.05). Finally, double administration of PEI/MSA polyplexes resulted in a further enhancement of transfection of the lung. Our data show that serum albumin enhances PEI-mediated gene transfer to airway epithelial cells in vivo, likely facilitating the uptake of polyplexes, and indicate that this formulation would fulfill the requirement of repeated administration, as necessary in chronic lung diseases like cystic fibrosis.

Lentiviral small hairpin RNA delivery reduces apical sodium channel activity in differentiated human airway epithelial cells

Epithelial sodium channel (ENaC) hyperactivity has been implicated in the pathogenesis of cystic fibrosis (CF) by dysregulation of fluid and electrolytes in the airways. In the present study, we show proof‐of‐principle for ENaC inhibition by lentiviral‐mediated RNA interference.

Late generation lentiviral vectors: Evaluation of inflammatory potential in human airway epithelial cells

Lentiviruses (LVs) are considered one of the most promising tools for gene transfer, however, their potential to induce pro-inflammatory cytokines on delivery into the respiratory tissue remains to be established. Here we tested a third-generation vesicular stomatitis virus (VSV)-G pseudotyped LV vector in the two respiratory epithelial cell lines A549 and CFT1-C2. We observed that the VSV-G LV vector does not induce (a) activation of the nuclear factor (NF)-kappaB, which intervenes in transcription of pro-inflammatory genes; (b) expression of ICAM-1; and (c) transcription of a panel of cytokines, with the exception of a mild and transient (24h) increase of IFN-gamma mRNA. In contrast, an adenovirus-derived vector strongly activated NF-kappaB and different transcripts such as those of ICAM-1, IL-8, RANTES, IP-10, TNF-alpha, IL-6, IL-1 beta. In conclusion, this third-generation VSV-G pseudotyped LV vector does not elicit major pro-inflammatory signals in human airway epithelial cells and appears to be better suited for gene delivery strategies.

New Genetic and Pharmacological Treatments for Cystic Fibrosis

Cystic Fibrosis (CF) is a still life-treathening disease, although therapies have augmented the life span of CF individuals. Isolation of the CF gene, named CFTR (CF Transmembrane Conductance Regulator), led to the discovery that it encodes for a protein kinase A-regulated chloride channel, expressed by epithelial cells mainly in mucosal tissues. Mutated or absent CFTR brings about altered muco-ciliary clearance, by a yet disputed mechanism (likely involving over- function of the epithelial sodium channel (ENaC)), and ultimately to colonization and infection of the airways by a few opportunistic bacteria species, including Pseudomonas aeruginosa (P.a.). An exuberant and persistent acute inflammatory reaction is commonly observed in the lung from CF patients, representing a key pathogenetic event of lung damage and respiratory insufficiency. Lung disease is the chief cause of morbidity and mortality in CF patients and current therapies are aimed at controlling the respiratory symptoms by antibiotic and anti-inflammatory treatments. Major improvements in the strategy to fight pulmonary P.a. infection are based on treatment of first colonization with P.a., of chronic infection and of multidrug resistant bacteria. Controlling inflammation is a challenging, however crucial, task in CF therapy. Since classical steroidal and non-steroidal anti-inflammatory drugs are endowed with serious side-effects, alternative anti- inflammatory strategies are being developed, including drugs which modulate cytokine expression, nitric oxide production and the oxidation unbalance in the CF airways. Soon after gene identification, gene transfer vectors to replace the defective gene were developed and underwent a number of human trials which have not yet produced a viable clinical gene therapy strategy. Novel gene therapy vectors and strategies for delivering them more efficiently and safely to the lung are being studied. In the last few years various in vitro studies have demonstrated the possibility of pharmacological intervention to correct the primary defect in CF. This may be obtained by directly addressing the CFTR protein (by means of so-called correctors and potentiators) or by modulating the activity of other types of ion transport in epithelial cells (such as with Moli1901 or denufosol). Novel interventions aimed to improve the mucociliary clearance, including hypertonic saline, mannitol and ENaC inhibitors, will be finally discussed.