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Our understanding of the role of disease-causing variants in CFTR has culminated in two new variant-specific CFTR modulator therapies approved by the US FDA. These modulators target defects in CFTR biogenesis and in channel gating. Clinical trials are directed to improving the efficacy of these first-generation molecules. However, other CFTR variants that lead to nonsense-mediated decay, aberrant splicing, and reduced gene expression are refractory to CFTR modulators and will require new therapeutic approaches. To this end, new CF animal models are yielding key insights into tissue-specific disease mechanisms, such as impaired mucociliary clearance and pancreatic dysfunction. Although infection and inflammation remain challenging to treat, progress in targeting CFTR directly will result in individuals with CF living longer. To maximize life span, earlier interventions, soon after diagnosis, are needed. Finally, the advances in precision medicine for CF may benefit more common disorders such as COPD and pancreatitis where CFTR dysfunction contributes to pathophysiology.

Human cystic fibrosis transmembrane conductance regulator (CFTR) was expressed in transgenic mice under the control of transcriptional elements derived from the human surfactant protein C (SP-C) gene. The hCFTR mRNA was expressed in lungs and testes: in the lung, we found hCFTR mRNA in bronchiolar and alveolar epithelial cells, and CFTR protein in respiratory epithelial cells. While the level of expression of hCFTR mRNA varied, hCFTR mRNA and protein were detected in pulmonary epithelial cells of several lines. Lung weight, morphology, somatic growth and reproductive capacity were not altered by expression hCFTR in lung and testes of the transgenics. Our findings suggest that hCFTR can be safely transferred to lung epithelial cells for CF therapy.

Human bocavirus virus-1 (HBoV1), a newly discovered autonomous parvovirus with a 5,500 nt genome, efficiently infects human-polarized airway epithelia (HAE) from the apical membrane. We hypothesized that the larger genome and high airway tropism of HBoV1 would be ideal for creating a viral vector for lung gene therapy. To this end, we successfully generated recombinant HBoV1 (rHBoV1) from an open reading frames-disrupted rHBoV1 genome that efficiently transduces HAE from the apical surface. We next evaluated whether HBoV1 capsids could package oversized rAAV2 genomes. These studies created a rAAV2/HBoV1 chimeric virus (5.5 kb genome) capable of apically transducing HAE at 5.6- and 70-fold greater efficiency than rAAV1 or rAAV2 (4.7-kb genomes), respectively. Molecular studies demonstrated that viral uptake from the apical surface was significantly greater for rAAV2/HBoV1 than for rAAV2 or rAAV1, and that polarization of airway epithelial cells was required for HBoV1 capsid-mediated gene transfer. Furthermore, rAAV2/HBoV1-CFTR virus containing the full-length cystic fibrosis transmembrane conductance regulator (CFTR) gene coding sequence and the strong CBA promoter efficiently corrected CFTR-dependent chloride transport in cystic fibrosis (CF) HAE. In summary, using the combined advantages of AAV and HBoV1, we have developed a novel and promising viral vector for CF lung gene therapy and also potentially HBoV1 vaccine development.

The immune response to tumors is thought to be inactivated, but the subsets of cells that ingest tumor to present to incoming immune cells have remained enigmatic. We generated a genetically encoded fluorescent mouse model of breast cancer to track antigen flow from tumors into immune cells, and defined a subset of tumorAPC (tAPC) that ingest tumor debris in the steady-state, act as a major repository of tumor-derived antigens, and present these antigens to tumor-reactive T cells. Using intravital live-imaging we show that this population represents a unique spatial subset of slow-moving marginating myeloid cells that interact closely with the tumor margin. We further show that these cells nucleate clusters of tumor-specific T cells, but appear to ‘anergize’ them. This study highlights a major route of immunosuppression in the tumor microenvironment and suggests immunotherapies based on modulating the function of tAPC.

To evaluate the efficiency, cell specificity, stability, and toxicity of recombinant adeno-associated virus (rAAV)-mediated retinal transduction in vivo in the adult immunocompetent mouse. To assess the usefulness of green fluorescent protein (GFP) for real-time, noninvasive monitoring of retinal transgene expression in vivo.Assessment of ocular GFP expression was performed in cohorts of mice for 11 weeks after subretinal injection of a recombinant adeno-associated virus carrying the complementary DNA (cDNA) for GFP. Examinations were performed in vivo by direct observation of fluorescence by ophthalmoscopy, using excitation-barrier filters. Histologic analyses of retinal tissue were used to identify transduced cells and to assess inflammation.Retinal GFP expression can be monitored in vivo using real-time, noninvasive imaging. Recombinant AAV efficiently transduces a variety of cells of the neural retina and of the retinal pigment epithelium (RPE). Transgene expression was not observed until 1 week after infection. The number of GFP-expressing cells increased over 3 weeks, and expressing photoreceptors and RPE, cells persisted at least through 11 weeks (the termination of the experiment). There was no clinical or histologic evidence of inflammatory response.Retinal gene transfer mediated by rAAV is stable and efficient and is associated with no clinically or histologically detectable toxicity or immune reaction. Green fluorescent protein allows noninvasive assessment of the extent and location of retinal transgene expression as a function of time and promises to be useful alone and as a tag for other transgenes delivered experimentally or therapeutically to the retina.

Ornithine-delta-aminotransferase (OAT) is a nuclear-encoded, mitochondrial matrix enzyme which, in rat, is expressed as basal levels in most tissues but is induced in liver by high dietary protein and in kidney by estrogen and thyroxine administration. In man, the hereditary deficiency of OAT results in ornithine accumulation and the blinding disease gyrate atrophy of the choroid and retina. We cloned near full length rat and human liver OAT cDNAs and demonstrated OAT expression in a variety of tissues from each species. We mapped the human OAT structural gene to chromosome 10, cloned 40 kilobase pairs of genomic DNA containing the complete OAT structural gene, and determined its organization. It is 21 kilobase pairs in length, and contains 11 exons. Exon 2 has been absent from all cDNAs studied and was detected by homology to X-linked processed OAT pseudogenes. The 5'-flanking region of the OAT gene has features of housekeeping genes (GC enrichment and three Sp1 binding consensus sequences) and tissue-specific, inducible genes (TATA box-like element and two CCAAT boxes). A 22-base pair region of partial dyad symmetry containing homology to estrogen responsive elements overlaps the OAT transcription site. Another 5' sequence, GTATCCTGCCCTC, is homologous to sequences in the promoter regions of the genes of three urea cycle enzymes.