Accumulation of Toxic Advanced Glycation End-Products Induces Cytotoxicity and Inflammation in Hepatocyte-Like Cells Differentiated from Human Induced Pluripotent Stem Cells

Abstract

Nonalcoholic steatohepatitis (NASH), the aggressive form of the most common chronic liver disease nonalcoholic fatty liver disease, is characterized by inflammation and damage in the liver. Although hepatocyte injury and cell death have been identified as cardinal pathological features of NASH, its pathogenesis has not yet been elucidated in detail. Immortalized cell lines and primary cultured cells have been used as in vitro models of NASH. However, these cells have several disadvantages, such as specialized characteristics by immortalization or limited growth potential. To overcome these difficulties and develop a strategy to analyze the pathology of NASH, we employed hepatocyte-like cells differentiated from human induced pluripotent stem cells (hiPSC-HLCs) as an in vitro model of NASH to clarify the intracellular effects of glyceraldehyde-derived advanced glycation end-products (AGEs), also named toxic AGEs (TAGE). The viability of hiPSC-HLCs decreased with the accumulation of TAGE in the cells, which was consistent with previous findings on human hepatocellular carcinoma cells and human primary cultured hepatocytes. In addition, the TAGE accumulation up-regulated the expression of inflammation-related genes (interleukin 6, interleukin 8, and monocyte chemoattractant protein-1) in hiPSC-HLCs. These results indicated that the accumulation of TAGE induced hiPSC-HLC cytotoxicity and inflammation, which are features of the pathology of NASH. Therefore, we suggest the use of hiPSC-HLCs as an important strategy for analyses of the pathology of NASH. Key words advanced glycation end-product (AGE); toxic AGE (TAGE); nonalcoholic steatohepatitis; human induced pluripotent stem cell (hiPSC); hepatocyte-like cell differentiated from hiPSC (hiPSC-HLC)

Effects of Toxic AGEs (TAGE) on Human Health

“…However, they have several disadvantages, such as specialized characteristics by immortalization or limited growth potential. A decrease was noted in the viability of hepatocyte-like cells (HLCs), which differentiated from human induced pluripotent stem cells (hiPSCs) (hiPSC-HLCs), as TAGE accumulated in cells, which was consistent with previous findings on HCC cells and primary cultured hepatocytes [33]. In addition, the accumulation of TAGE up-regulated the expression of inflammationrelated genes (i.e., interleukin (IL)-6, IL-8, and monocyte chemoattractant protein (MCP)-1) in hiPSC-HLCs.…”

“…Furthermore, we indicated the inhibition of autophagy by intracellular TAGE [ 37 ]. Although previous studies demonstrated that intracellular TAGE were cytotoxic in cell lines of various organs [ 30 , 31 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 42 ], our findings showed time-dependent decreases in the expression levels of LC3-II/LC3-I in cardiomyocytes treated with GA [ 37 ]. TAGE-modified proteins in cardiomyocytes have yet to be identified; however, TAGE have been suggested to alter the proteins involved in the regulation of autophagy-related pathways, such as those contributing to the generation of LC3-II.…”

“…The effects of AGEs have been attributed to their extracellular binding to RAGE or their accumulation in numerous tissues; however, further studies are warranted to elucidate the impact of intracellular TAGE. In vitro intracellular TAGE molecules have been shown to exert cytotoxic effects in hepatocytes [ 30 , 31 , 33 ], myoblasts [ 34 ], β-cells [ 35 ], osteoblasts [ 36 ], cardiomyocytes [ 37 ], cardiac fibroblasts [ 38 ], neuroblastoma cells [ 39 ], and pancreatic ductal cells [ 42 ]. These molecules are intermediates of the abnormal metabolism of glucose and fructose in the presence of excess GA.…”

“…In this review, the content that overlaps with the previous paper has been simplified, and novel findings have been added. In our recent study, the intracellular generation/accumulation of TAGE was detected in many cell types [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. Elevated levels of TAGE damage cells, which results in the leakage of TAGE into the circulation and to the surrounding cells; the damage induced promotes the onset and progression of lifestyle-related diseases (LSRD) [ 9 , 10 , 11 ].…”

Anti-glycation and anti-inflammatory activities of anthocyanins from purple vegetables

“…The gradual accumulation of AGEs in body tissues has cytotoxic effects on tissues and cells, driving chronic diseases. 2 Recent studies have shown that methyl-glyoxal (MGO), a potent precursor for AGEs, is generated as a nonenzymatic breakdown product of a triosephosphate intermediate in the glycolytic process and has been linked to dicarbonyl stress, which leads to the development of AGEs and cellular dysfunction. 3 Amyloid fibrillation induced by excessive non-enzymatic glycation with the accumulation of AGEs is fundamental to the development of many neurodegenerative and cardiovascular complications.…”