Oral FGF21 delivery to limit its action to the liver
Plant Cultivation, Plant Nutrition, Agricultural Technology
Final Report Abstract
Worldwide 0.4 billion people are affected by the non-alcoholic steatohepatitis (NASH), which increase the morbidity and mortality with no approved medications. The fibroblast growth factor 21 (FGF21) is an multiorgan regulator, playing an important role in glucose and lipid homeostasis. In mouse studies, FGF21 enhanced the insulin sensitivity while attenuated the fat accumulation and thus induced weight loss, and clinical studies with FGF21 analogues confirmed these effects in humans. The liver is the main target of FGF21, however, the hepatic metabolic actions of FGF21 are still unknown. Moreover, the long persistence of FGF21 analogues led to adverse effects such as reduction of bone mass. These effects might be reduced, if FGF21 can exclusively delivered to the liver for which orally administrated plant seeds can be used. Animal studies showed that plant material protected the therapeutic protein from the conditions in the stomach but released the it when the plant material was digested in the intestine. The released protein was then taken up by the portal vein, which goes directly to the liver. Hence, the main objectives of this project were (i) clarification of the hepatic effects of FGF21 and (ii) establishing the oral delivery of FGF21 via edible tobacco seeds. (i) Investigation of direct hepatic effects of FGF21 using primary hepatocytes from FGF21-/- mice showed that the loss of FGF21 sensitizes hepatocytes to oxidative stress, which apparently induces an increased glucose fuelled de novo lipogenesis. This is in line with the increased hepatic lipid content in aged FGF21-/- mice, and supports our concept of using oral application of FGF21 for liver specific FGF21 effects targeting NAFLD and NASH. (ii) The production of a FGF21-transferrin (FGF-Tf) fusion protein in stably transformed edible tobacco seeds was successfully established. However, the accumulation level was below the required amount to achieve a viable FGF21 concentration in the liver due to a substantial degradation of FGF21-Tf. Therefore, we designed alternative fusion proteins and tested them via transient transformation of tobacco leaves, and the final nTf338-FGF21-PLUS showed almost no degradation products. Purified nTf338-FGF21-PLUS from tobacco leaves was gavaged to FGF21-/- mice where it was transferred from the intestine to the portal vein and acutely affected hepatic mRNA expression. Hence, the medication of NASH via oral delivery of nTf338-FGF21-PLUS containing plants seems possible.
Publications
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Targeted delivery of FGF21 to the liver in planta bioencapsulation. International Conference of the German Society for Plant Sciences 2019 [Botaniker-Tagung 2019]
Hou H.W. et al.
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Tobacco SL632 as an expression platform using FGF21 and GFP as model proteins. 9th Fraunhofer IME PhD Seminar 2019
Hou HW et al.
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Effects of liver-targeted FGF21 signaling on hepatic energy metabolism & cellular homeostasis. Joint PhD seminar DIfE/Institute of Nutritional Science (IEW) of the University of Potsdam, 11/2020
Gahner, N. et al.
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Transient expression of FGF21-Tf seems to be affected be the stability of the linker region. 10th Fraunhofer IME PhD Seminar 2020
Hou HW et al.
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Comparing seed-based stable and leaf-based transient expression for the production of the FGF21-Transferrin fusion protein. 11th Fraunhofer IME PhD Seminar 2021
Hou HW et al.
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Seed-and leaf-based expression of FGF21-transferrin fusion proteins for oral delivery and treatment of non-alcoholic steatohepatitis. Frontiers in Plant Science, 13.
Hou, Hsuan-Wu; Bishop, Christopher A.; Huckauf, Jana; Broer, Inge; Klaus, Susanne; Nausch, Henrik & Buyel, Johannes F.
