Transplant immunosuppression enhances efficiency of adenoviral-mediated gene retransfection: inhibition of interferon-gamma and immunoglobin G.
BACKGROUND
Transplant immunosuppression regimen facilitates successful adenovirus-mediated gene transfection and retransfection in the rat lung. Herein, we investigated the effect of this strategy on circulating cytokines and antiadenoviral immunoglobin G antibody.


METHODS
Male Lewis rats were transfected with 1 x 10(9) pfu/mL of E1-deleted Ad5CMVLacZ vector transtracheally. Rats were randomly assigned to receive daily intraperitoneal triple immunosuppression regimen consisting of cyclosporine (15 mg/kg per day), azathioprine (6 mg/kg per day), and methylprednisolone (2.5 mg/kg per day), or normal saline solution. Retransfection was performed 35 days later to all nonimmunosuppressed animals, whereas immunosuppressed rats were further randomized to receive retransfection or phosphate-buffered saline. Animals were sacrificed on days 1, 2, 7, 35, 42, and 49 after the initial transfection. Beta-galactosidase activity was measured on lung homogenates. Interferon-gamma, tumor necrosis factor-alpha, and antiadenoviral immunoglobin G were measured from the serum.


RESULTS
Enhanced and prolonged transgene expression was observed in immunosuppressed animals, especially after retransfection. Concentrations of serum tumor necrosis factor-alpha in both groups were less than 12 pg/mL throughout the study. A significant increase in serum interferon-gamma levels was observed in nonimmunosuppressed animals after retransfection; this was not seen in the immunosuppressed animals. Serum antiadenoviral immunoglobin G titers in both groups were sharply elevated on day 1, and declined to basal levels by day 7, reflecting a preexisting level of humoral immunity to adenovirus. The titer in nonimmunosuppressed rats was significantly increased after retransfection, but remained at very low level in immunosuppressed animals.


CONCLUSIONS
Inhibition of interferon-gamma and antiadenoviral immunoglobin G production by triple immunosuppressants may be part of the mechanisms that lead to enhanced and prolonged transgene expression after retransfection.
Suga
Michiharu
M
University Health Network, Toronto General Hospital Research Institute, Department of Surgery, University of Toronto, Ontario, Canada.
Gladdy
Rebecca
R
Xing
Zhou
Z
Keshavjee
Shaf H
SH
Liu
Mingyao
M
D000256:Adenoviridae / Q000276:immunology; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D001379:Azathioprine / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004359:Drug Therapy, Combination; D015870:Gene Expression / Q000187:drug effects; D005822:Genetic Vectors; D007074:Immunoglobulin G / Q000097:blood*; D007165:Immunosuppression Therapy; D007166:Immunosuppressive Agents / Q000008:administration & dosage* / Q000494:pharmacology; D007371:Interferon-gamma / Q000097:blood*; D007763:Lac Operon; D008297:Male; D008775:Methylprednisolone / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew; D019233:Retreatment; D014162:Transfection; D019076:Transgenes; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007166:Immunosuppressive Agents; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D016572:Cyclosporine; D001616:beta-Galactosidase; D001379:Azathioprine; D008775:Methylprednisolone