Faculty Bibliography

BACKGROUND:Graft-versus-host-disease (GVHD) after liver transplantation (LT) is a deadly complication with very limited data on risk factors, diagnosis and management. We report a case series and a comprehensive review of the literature. METHODS:Data were systematically extracted from reports of GVHD after LT, and from the United Network for Organ Sharing database. Group comparisons were performed. RESULTS:One hundred fifty-six adult patients with GVHD after LT have been reported. Median time to GVHD onset was 28 days. Clinical features were skin rash (92%), pancytopenia (78%), and diarrhea (65%). Six-month mortality with GVHD after LT was 73%. Sepsis was the most common cause of death (60%). Enterobacter bacteremia, invasive aspergillosis, and disseminated Candida infections were frequently reported. Recipient age over 50 years is a risk factor for GVHD after LT. Hepatocellular carcinoma was overrepresented, whereas chronic hepatitis C was underrepresented, in reported United States GVHD cases relative to all United Network for Organ Sharing database LT cases. Mortality rate with treatment of GVHD after LT was 84% with high-dose steroids alone, 75% to 100% with regimens using dose increases of calcineurin inhibitors, and 55% with IL-2 antagonists. Mortality was 25% in small case series using the CD2-blocker alefacept or TNF-α antagonists. CONCLUSIONS:Age older than 50 years and hepatocellular carcinoma appear to be risk factors for GVHD. Hepatitis C may be protective. High-dose steroids and calcineurin inhibitors are ineffective in the treatment of GVHD after LT. CD2-blockers and TNF-α antagonists appear promising. We propose a diagnostic algorithm to assist clinicians in managing adults with GVHD after LT.

The packaging capacity of recombinant adeno-associated viral (rAAV) vectors limits the size of the promoter that can be used to express the 4.43-kb cystic fibrosis transmembrane conductance regulator (CFTR) cDNA. To circumvent this limitation, we screened a set of 100-mer synthetic enhancer elements, composed of ten 10-bp repeats, for their ability to augment CFTR transgene expression from a short 83-bp synthetic promoter in the context of an rAAV vector designed for use in the cystic fibrosis (CF) ferret model. Our initial studies assessing transcriptional activity in monolayer (nonpolarized) cultures of human airway cell lines and primary ferret airway cells revealed that three of these synthetic enhancers (F1, F5, and F10) significantly promoted transcription of a luciferase transgene in the context of plasmid transfection. Further analysis in polarized cultures of human and ferret airway epithelia at an air-liquid interface (ALI), as well as in the ferret airway in vivo, demonstrated that the F5 enhancer produced the highest level of transgene expression in the context of an AAV vector. Furthermore, we demonstrated that increasing the size of the viral genome from 4.94 to 5.04 kb did not significantly affect particle yield of the vectors, but dramatically reduced the functionality of rAAV-CFTR vectors because of small terminal deletions that extended into the CFTR expression cassette of the 5.04-kb oversized genome. Because rAAV-CFTR vectors greater than 5 kb in size are dramatically impaired with respect to vector efficacy, we used a shortened ferret CFTR minigene with a 159-bp deletion in the R domain to construct an rAAV vector (AV2/2.F5tg83-fCFTRΔR). This vector yielded an ∼17-fold increase in expression of CFTR and significantly improved Cl(-) currents in CF ALI cultures. Our study has identified a small enhancer/promoter combination that may have broad usefulness for rAAV-mediated CF gene therapy to the airway.

Large animal models of genetic diseases are rapidly becoming integral to biomedical research as technologies to manipulate the mammalian genome improve. The creation of cystic fibrosis (CF) ferrets and pigs is an example of such progress in animal modeling, with the disease phenotypes in the ferret and pig models more reflective of human CF disease than mouse models. The ferret and pig CF models also provide unique opportunities to develop and assess the effectiveness of gene and cell therapies to treat affected organs. In this review, we examine the organ disease phenotypes in these new CF models and the opportunities to test gene therapies at various stages of disease progression in affected organs. We then discuss the progress in developing recombinant replication-defective adenoviral, adeno-associated viral, and lentiviral vectors to target genes to the lung and pancreas in ferrets and pigs, the two most affected organs in CF. Through this review, we hope to convey the potential of these new animal models for developing CF gene and cell therapies.