An approach to the treatment of Type 1 diabetes is to convert non-β-cells, such as liver cells, into insulin-producing cells. The human liver cell line, Huh7, has been engineered to express human insulin and islet glucokinase (Melligen cells). These cells store and secrete insulin to glucose in the physiological range and can reverse diabetes after transplantation in NOD/scid mice. Melligen cells also maintain viability and normal glucose responsiveness following 10 days exposure to a pro-inflammatory cytokine cocktail (CC), composed of IFN-γ (384ng/mL), TNF-α (10ng/mL) and IL-1β (2ng/mL). Microarray analyses were used to examine the profile of global gene expression levels in Melligen cells exposed to CC for 24h.
Modified expression levels were observed for 148 genes following CC treatment. Unlike pancreatic β-cells, genes associated with glucose metabolism were not affected. A significant proportion of the genes whose expression profile was up regulated upon CC treatment, mainly represented genes inducible by CC. Quantitative-RT-PCR analysis was performed on five genes whose expression was significantly up regulated greater than twofold. The anti-apoptotic gene BIRC3 and the antioxidant gene SOD2 were significantly (P<0.05) up regulated 11.5±2.4 and 4.5±0.4-fold (n=8) respectively, indicating a protective response against cytokine-induced apoptosis. Genes induced by CC such as CASP1 (IL pathway), IRF1 and STAT1 (IF pathway) were up regulated 2.0±0.4, 5.4±1.3 and 2.3±0.3-fold respectively. By comparison the CASP1 inhibitor CARD1 was also up regulated 2.8-fold in the microarray analysis. Thus, CC treatment does affect Melligen cells with up regulation of pathways associated with CC activation, but they are protected from the defects in glucose metabolism and apoptosis expressed by β-cells, as seen in other studies utilising insulin-secreting hepatocytes, reacting to the autoimmune attack more as hepatocytes than β-cells.