AAV5-mediated gene transfer to the parotid glands of non-human primates.

Salivary glands are potentially useful target sites for multiple clinical applications of gene transfer. Previously, we have shown that serotype 2 adeno-associated viral (AAV2) vectors lead to stable gene transfer in the parotid glands of rhesus macaques. As AAV5 vectors result in considerably greater transgene expression in murine salivary glands than do AAV2 vectors, herein we have examined the use of AAV5 vectors in macaques at two different doses (n = 3 per group; 10(10) or 3 x 10(11) particles per gland). AAV5 vector delivery, as with AAV2 vectors, led to no untoward clinical, hematological or serum chemistry responses in macaques. The extent of AAV5-mediated expression of rhesus erythropoietin (RhEpo) was dose-dependent and similar to that seen with an AAV2 vector. However, unlike results with the AAV2 vector, AAV5 vector-mediated RhEpo expression was transient. Maximal expression peaked at day 56, was reduced by approximately 80% on day 84 and thereafter remained near background levels until day 182 (end of experiment). Quantitative PCR studies of high-dose vector biodistribution at this last time point showed much lower AAV5 copy numbers in the targeted parotid gland (approximately 1.7%) than found with the same AAV2 vector dose. Molecular analysis of the conformation of vector DNA indicated a markedly lower level of concatamerization for the AAV5 vector compared with that of a similar AAV2 vector. In addition, cellular immunological studies suggest that host response differences may occur with AAV2 and AAV5 vector delivery at this mucosal site. The aggregate data indicate that results with AAV5 vectors in murine salivary glands apparently do not extend to macaque glands.

Transient TWEAK overexpression leads to a general salivary epithelial cell proliferation.

OBJECTIVES: Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a multifunctional cytokine that has pro-apoptotic, pro-angiogenic and pro-inflammatory effects. In liver, TWEAK leads to proliferation of progenitor oval cells, but not of mature hepatocytes. This study evaluated the hypothesis that TWEAK overexpression in salivary glands would lead to the proliferation of a salivary progenitor cell. METHODS: A recombinant, serotype 5 adenoviral vector encoding human TWEAK, AdhTWEAK, was constructed, initially tested in vitro, and then administered to male Balb/c mice via cannulation of Wharton's duct. TWEAK expression in vivo was monitored as protein secreted into saliva and serum by enzyme-linked immunosorbent assays. Salivary cell proliferation was monitored by proliferating cell nuclear antigen staining and apoptosis was monitored using TUNEL staining. RESULTS: AdhTWEAK administration led to a dose-dependent, transient TWEAK protein expression, detected primarily in saliva. Salivary epithelial cell proliferation was generalized, peaking on approximately days 2 and 3. TWEAK expression had no detectable effect on apoptosis of salivary epithelial cells. CONCLUSION: Transient overexpression of TWEAK in murine salivary glands leads to a general proliferation of epithelial cells vs a selective stimulation of a salivary progenitor cell.

NOD mouse model for Sjögren's syndrome: lack of longitudinal stability.

OBJECTIVES: The non-obese diabetic (NOD) mouse is not only a widely used model for diabetes mellitus type I, but also for the chronic autoimmune disease Sjögren's syndrome (SS), mainly affecting salivary and lacrimal glands. We studied the efficacy of local recombinant serotype 2 adeno-associated viral (rAAV2) vector transfer of immunomodulatory transgenes to alter the SS-like disease in NOD mice. Data collected over a 2-year period indicated a changing SS phenotype in these mice and this phenomenon was investigated. METHODS: 10(10) particles rAAV2LacZ/gland were delivered to both submandibular glands (SMGs) of NOD/LtJ mice at 8 weeks (before sialadenitis onset) of age. Salivary flow rates were determined at 8 weeks and time of killing. Blood glucose levels and body weights were measured weekly. After killing, saliva and SMGs were harvested. Analyses of salivary output, inflammatory infiltrates (focus score), SMG cytokine profile, body weight, and diabetes mellitus status were performed. Data from six different experimental studies over 2 years were analyzed and compared. RESULTS: Salivary flow rate, focus score, and SMG cytokines interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12(p70), tumor necrosis factor-alpha and IFNgamma showed changes over time. There were no differences for body weight, diabetes mellitus prevalence, or blood glucose level of non-diabetic mice. CONCLUSION: This retrospective report is the first to describe longitudinal variability in the NOD mouse as a model for SS. We advise other investigators to continuously monitor the SS phenotype parameters and include appropriate controls when studying this disease in NOD mice.

Effect of human vasoactive intestinal peptide gene transfer in a murine model of Sjogren's syndrome.

BACKGROUND: Sjögren's syndrome (SS), an autoimmune exocrinopathy mainly affecting lachrymal and salivary glands, results in ocular and oral dryness (keratoconjunctivitis sicca and xerostomia). The aetiology and pathogenesis are largely unknown; currently, only palliative treatment is available. OBJECTIVE: To determine whether gene transfer of vasoactive intestinal peptide (VIP), based on its immunomodulatory properties, might be useful in the management of SS. METHODS: A recombinant serotype 2 adeno-associated virus encoding the human VIP transgene (rAAV2hVIP) was constructed and its efficacy tested in the female non-obese diabetic (NOD) mouse model for SS after retrograde instillation in submandibular glands (SMGs). 10(10) particles/gland of rAAV2hVIP or rAAV2LacZ (encoding beta-galactosidase; control vector) were administered at 8 weeks of age (before sialadenitis onset). Salivary flow rates were determined before vector delivery and at time of death (16 weeks). After death, saliva, serum, and SMGs were harvested. Salivary output, inflammatory infiltrates (focus scores), VIP protein expression, cytokine profile, and serum anti-VIP antibodies were analysed. RESULTS: rAAV2hVIP significantly improved the salivary flow, increased SMG and serum expression of VIP, and reduced SMG cytokines interleukin (IL) 2, IL10, IL12 (p70), and tumour necrosis factor alpha, and serum RANTES, compared with the control vector. No difference in focus scores or apoptotic rates was found; neutralising antibodies were not detected. CONCLUSIONS: Local delivery of rAAV2hVIP can have disease modifying and immunosuppressive effects in SMGs of the NOD mouse model of SS. The new strategy of employing VIP prophylactically may be useful for both understanding and managing the salivary component of SS.

Rapamycin control of transgene expression from a single AAV vector in mouse salivary glands.

Salivary glands (SGs) appear to be a useful target site for gene therapeutics. The ability to control transgene expression is essential for clinical application. Previously, in a proof-of-concept study, we have shown that the rapamycin-inducible transcriptional regulation system can regulate protein expression after adenoviral-mediated gene transfer to SGs. To evaluate the potential ability to utilize this regulatory system for long-term control of transgene expression in this tissue, we employed a 'third generation', single adenoassociated serotype 2 viral (AAV2) vector encoding human erythropoietin (hEPO) under the control of a rapamycin-inducible promoter. The vector, rAAV-TF2.3-hEPO (10(10) particles/animal), was delivered to mouse SGs. No detectable increase in serum hEPO or hematocrit levels was observed in the absence of rapamycin administration. However, rapamycin induced elevation of serum hEPO levels, as well as concomitant hematocrit changes, that were dose-dependent, completely reversible, and relatively stable over the course of this study (6 months), with no appreciable change in rapamycin responsiveness. Our results suggest that the rapamycin transcriptional regulation system delivered in a single AAV2 vector to SGs may be valuable for systemic protein replacement applications.