Endosomal processing limits gene transfer to polarized airway epithelia by adeno-associated virus.
Level 5 - mechanism / opinion, no new human data
Preclinical in vitro human cell culture and in vivo animal (mouse) experimental study
PubMed 10841516 · doi:10.1172/JCI8317
What was done
Researchers investigated the mechanisms limiting recombinant adeno-associated virus type 2 (rAAV-2) gene transfer across the apical surface of differentiated human airway epithelia. They evaluated viral internalization, intracellular trafficking, capsid ubiquitination, and the effect of tripeptide proteasome inhibitors and ubiquitin ligase inhibitors on transduction efficiency in vitro and in vivo in mouse models (evaluating lung, liver, skeletal muscle, and cardiac muscle).
What was found
Differentiated human airway epithelia internalized rAAV-2 efficiently from the apical membrane despite lacking known AAV-2 receptors. Transduction failure was linked to post-internalization endosomal processing, nuclear trafficking barriers, and viral capsid ubiquitination. Tripeptide proteasome inhibitors increased persistent apical rAAV gene delivery in vitro by >200-fold, matching basolateral transduction levels. In vivo co-administration of proteasome inhibitors in mice increased lung epithelial gene transfer from undetectable levels to a mean of 10.4 ± 1.6% in large bronchioles, and increased liver transduction 10-fold, with no enhancement seen in skeletal or cardiac muscle.
Why it matters
These findings identify intracellular ubiquitination and endosomal processing—rather than viral entry—as the primary barrier to apical rAAV-2 infection in airway epithelia. Modulating the proteasome pathway represents a potential strategy to improve vector efficiency for respiratory gene therapy, including cystic fibrosis.
Limits
The abstract does not state the sample sizes (n) for cell culture replicates or animal cohorts. Findings are limited to preclinical in vitro and murine models, and safety, toxicity, or feasibility of co-administering proteasome inhibitors for gene therapy in humans were not evaluated.
Cited by
- supports Adeno-associated virus (AAV) does not transfect well through the nasal mucosa.