Endobronchial transfection of naked viral interleukin-10 gene in rat lung allotransplantation

Background. Recent studies suggest that viral interleukin-10 (VIL-10) suppr esses alloimmune response in transplantation. Tissue mRNA expression of ind ucible nitric oxide synthase (iNOS) and exhaled nitric oxide (NO) levels ha ve been observed to increase in lung allograft rejection. The aims of this study were to examine the feasibility of vIL-10 gene transfer into rat lung allografts and to investigate its effect on subsequent allograft rejection . Methods. Male Lewis rats (RT1I) underwent left lung transplantation with al lografts from Brown Norway rats (RT1n). The donor rats were endobronchially transfected 2 minutes before harvest with 400 mug (group I, n = 5), 600 mu g (group II, n = 5), or 800 mug (group III, n = 5) of naked pCMVievIL-10. G roup IV (n = 5) animals, serving as control, received 400 mug of naked pCF1 -CAT. All recipients were sacrificed on postoperative day 5. Transgene expr ession of vIL-10 was assessed by both reverse transcriptase-polymerase chai n reaction and immunohistochemistry. Allograft gas exchange, exhaled NO lev el, histologic rejection score, and mRNA expression of graft cyokines were also assessed. Results. Transgene expression of lung graft VIL-10 was detected by both rev erse transcriptase-polymerase chain reaction and immunohistochemistry. The iNOS mRNA expression in groups I, II, and III was significantly lower than that of group IV (p < 0.05, analysis of variance). Exhaled NO levels in gro ups I, II, and III were significantly lower than in group IV (p < 0.01, ana lysis of variance). There was no significant difference between groups with respect to gas exchange, peak airway pressure, or histologic rejection sco re. Conclusions. It appears that endobronchial transfection of naked vIL-10 pla smid in a rat lung allotransplant model is feasible and suppresses lung iNO S mRNA expression and exhaled NO levels. An association between iNOS upregu lation and high exhaled NO levels in lung allograft resection was also note d. (C) 2001 by The Society of Thoracic Surgeons.