Association of mRNA expression of iron metabolism-associated genes and progression of non-alcoholic steatohepatitis in rats

// Teruhisa Higuchi 1 , Mitsuhiko Moriyama 1 , Akiko Fukushima 1 , Hiroshi Matsumura 1 , Shunichi Matsuoka 1 , Tatsuo Kanda 1 , Masahiko Sugitani 2 , Akiko Tsunemi 3 , Takahiro Ueno 3 and Noboru Fukuda 3 1 Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nihon University School of Medicine, Itabashi-Ku, Tokyo 173-8610, Japan 2 Department of Pathology, Nihon University School of Medicine, Itabashi-Ku, Tokyo 173-8610, Japan 3 Division of Nephrology, Hypertension and Endocrinology, Department of Internal Medicine, Nihon University School of Medicine, Itabashi-Ku, Tokyo 173-8610, Japan Correspondence to: Tatsuo Kanda, email: kandat-cib@umin.ac.jp , kanda.tatsuo@nihon-u.ac.jp Mitsuhiko Moriyama, email: moriyama.mitsuhiko@nihon-u.ac.jp Keywords: iron; NASH; SHRSP5 rat; intestine; HAMP Received: May 18, 2017 Accepted: May 09, 2018 Published: May 25, 2018 ABSTRACT Background: Excess iron is associated with non-alcoholic steatohepatitis (NASH). Results: mRNA expression of duodenal cytochrome b, divalent metal transporter 1, ferroportin 1, hepcidin, hephaestin and transferrin receptor 1 in liver were higher in high fat, high cholesterol-containing diet (HFCD) group than in normal diet (ND) group. mRNA levels of divalent metal transporter 1 and transferrin receptor 1, which stimulate iron absorption and excretion, were enhanced in small intestine. Epithelial mucosa of small intestine in HFCD group was characterized by plasma cell and eosinophil infiltration and increased vacuoles. Iron absorption was enhanced in this NASH model in the context of chronic inflammation of small intestinal epithelial cells, consequences of intestinal epithelial cell impairment caused by HFCD. Iron is transported to hepatocytes via portal blood, and abnormalities in iron absorption and excretion occur in small intestine from changes in iron transporter expression, which also occurs in NASH liver. Knockdown of hepcidin antimicrobial peptide led to enhanced heavy chain of ferritin expression in human hepatocytes, indicating association between hepcidin production and iron storage in hepatocytes. Conclusions: Iron-related transporters in liver and lower/upper portions of small intestine play critical roles in NASH development. Methods: Expression of iron metabolism-related genes in liver and small intestine was analyzed in stroke-prone spontaneously hypertensive rats (SHR-SP), which develop NASH. Five-week-old SHR-SP fed ND or HFCD were examined. mRNA and protein levels of iron metabolism-related genes in liver and small intestine from 12- and 19-week-old rats were evaluated by real-time RT-PCR and immunohistochemistry or Western blot.