title: Production of biologically active human interleukin-4 in transgenic tobacco and potato.
abstract: Interleukin-4 (IL-4) is a pleiotropic cytokine that plays a key regulatory role in the immune system. Recombinant human IL-4 (rhIL-4) offers great potential for the treatment of cancer, viral and autoimmune diseases. Unfortunately, the high production cost of IL-4 associated with conventional expression systems has, until now, limited broader clinical testing, particularly with regard to the more convenient and safer oral delivery of IL-4 as opposed to parenteral injection in patients. In this study, we investigated the feasibility of transgenic plants for the cost-effective production of rhIL-4. IL-4 expression vectors with different modifications under the control of a constitutive cauliflower mosaic virus 35S (CaMV 35S) promoter were introduced into tobacco by Agrobacterium-mediated transformation. Transgenic tobaccos expressing various levels of rhIL-4 protein were generated. Higher expression was achieved through IL-4 retention in the endoplasmic reticulum (ER), with the maximal accumulation being approximately 0.1% of total soluble protein (TSP) in the leaves. No improvement in expression was further achieved by replacing the native signal peptide of IL-4 with the plant signal peptide. The best rhIL-4-expressing vector shown in tobacco was selected and further transferred into potato plants. The analysis of transgenic tubers also revealed various levels of rhIL-4, with the highest being 0.08% of TSP. Sensitive in vitro T-cell proliferation assays showed that plant-derived rhIL-4 retained full biological activity. These results suggest that plants can be used to produce biologically active rhIL-4 and probably many other mammalian proteins of medical significance. Moreover, the production of plants expressing rhIL-4 will enable the testing of plant rhIL-4 by oral delivery for the treatment of clinical diseases.
authors.affiliation: Transplantation Immunology Group, Lawson Health Research Institute, London, ON, Canada, N6A 4G5. sma@uwo.ca
authors.forename: Shengwu
authors.initials: S
authors.lastname: Ma
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.forename: Antonelle
authors.initials: A
authors.lastname: Davis
authors.forename: Ziqin
authors.initials: Z
authors.lastname: Yin
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Mi
authors.forename: Rima
authors.initials: R
authors.lastname: Menassa
authors.forename: James E
authors.initials: JE
authors.lastname: Brandle
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Jevnikar