👤 Sachiyo Kamimura

The onset and progression mechanisms of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) are being studied. We developed and analyzed a new mouse model of obesity by combining maternal Id-like molecule (Maid) and melanocortin-4 receptor (Mc4r) gene deletions. Four mice, each at 12 and 28 weeks of age, were analyzed for each genotype: Maid gene knockout, Mc4r gene knockout, combined Mc4r and Maid gene knockout, and Mc4r gene knockout with a high-fat diet. Mice with a combined deficiency of Mc4r and Maid gene showed significantly more severe obesity compared to all other genotypes, but no liver fibrosis or a decline in metabolic status were observed. In visceral white adipose tissue, Maid and Mc4r gene knockout mice had fewer CD11c-positive cells and lower mRNA expression of both inflammatory and anti-inflammatory cytokines. Furthermore, Maid and Mc4r gene knockout mice showed lower expression of adipocytokines in visceral white adipose tissue and uncoupling protein-1 in scapular brown adipose tissue. The expression of adipocytokines and uncoupling protein-1 is regulated by sympathetic nerve signaling that contribute severe obesity in Maid and Mc4r gene knockout mice. These mechanisms contribute hyperobesity in Maid and Mc4r gene knockout mice. Show less

Serotonin (5-HT) is one of the key bioamines of nonalcoholic fatty liver disease (NAFLD). Its mechanism of action in autonomic neural signal pathways remains unexplained; hence, we evaluated the involvement of 5-HT and related signaling pathways via autonomic nerves in NAFLD. Diet-induced NAFLD animal models were developed using wild-type and melanocortin 4 receptor (MC4R) knockout (MC4RKO) mice, and the effects of the autonomic neural axis on NAFLD physiology, 5-HT and its receptors (HTRs), and lipid metabolism-related genes were assessed by applying hepatic nerve blockade. Hepatic neural blockade retarded the progression of NAFLD by reducing 5-HT in the small intestine, hepatic HTR2A and hepatic lipogenic gene expression, and treatment with an HTR2A antagonist reproduced these effects. The effects were milder in MC4RKO mice, and brain 5-HT and HTR2C expression did not correlate with peripheral neural blockade. Our study demonstrates that the autonomic liver-gut neural axis is involved in the etiology of diet-induced NAFLD and that 5-HT and HTR2A are key factors, implying that the modulation of the axis and use of HTR2A antagonists are potentially novel therapeutic strategies for NAFLD treatment. This article has an associated First Person interview with the first author of the paper. Show less

Melanocortin 4 receptor gene-knockout (MC4R-KO) mice are known to develop obesity with a high-fat diet. Meanwhile, daisaikoto, one of Kampo medicines, is a drug that is expected to have therapeutic effects on obesity. Here, we report the efficacy of daisaikoto in MC4R-KO mice. Eight-week-old MC4R-KO male mice (n = 12) were divided into three groups as follows: the SD group, which is fed with a standard diet; the HFD group, fed a high-fat diet; and the DSK group, fed with a high-fat diet containing 10% of daisaikoto. After the four-week observation period, mice in each group were sacrificed and samples were collected. The body weights at 12 weeks were significantly higher in the HFD group than in the other groups, indicating that daisaikoto significantly reduced body weight gain and fat deposition of the liver. The metabolome analysis indicated that degradation of triglycerides and fatty acid oxidation in the liver were enhanced by daisaikoto administration. In MC4R-KO mice, the cytoplasm and uncoupling protein 1 expression of brown adipose tissue was decreased; however, it was reversed in the DSK group. In conclusion, daisaikoto has potentially improved fatty liver and obesity, making it a useful therapeutic agent for obesity and fatty liver. Show less

The number of patients with non-alcoholic steatohepatitis (NASH) and inflammatory bowel disease (IBD) is increasing. This study elucidates the effect of both NASH and IBD on hepatocellular carcinoma (HCC) using a mouse model combining NASH and IBD. The melanocortin 4 receptor-deficient (Mc4r-KO) mice were divided into four groups with or without a high-fat diet (HFD) and with or without dextran sulfate sodium (DSS) to induce colitis, and the differences in liver damage and occurrence of HCC were analyzed. In the HFD + DSS group, the body weight, liver weight/body weight ratio, and serum levels of albumin and alanine aminotransferase were significantly lower than those in the HFD group. We further found that steatosis was significantly lower and lobular inflammation was significantly higher in the HFD + DSS group than those in the HFD group, and that individual steatosis and lobular inflammation state in the HFD + DSS mice varied. We detected HCC only in the HFD + DSS group, and mice with severe steatosis and mild colitis were found to be at high risk of HCC. Presently, the prediction of HCC is very difficult. In some cases, severe colitis reverses the fat accumulation due to appetite loss. Our findings clearly showed that severe steatohepatitis and mild colitis are simultaneously essential for the occurrence of HCC in patients with NASH and IBD. Show less

We here report a 2-year-old female with relapsed acute myeloid leukemia (AML) with MLL gene rearrangement in the bone marrow and central nervous system. The 3'-RACE (Rapid Amplification of cDNA Ends) method identified the MLLT10 gene as a fusion partner of the MLL gene. The patient was complicated with hemophagocytic lymphohistiocytosis (HLH) and invasive aspergillosis (IPA) after re-induction treatment with FLAG-IDA following etoposide, cytarabine, and mitoxantrone. Although treatment with systemic anti-fungal drugs was effective for IPA, HLH did not improve. We considered tumor-associated HLH to be initiated from leukemic stem cells (LSCs) in the bone marrow niche because reverse transcription-polymerase chain reaction (RT-PCR) analysis of a bone marrow biopsy sample was positive for MLL-MLLT10. Gemtuzumab ozogamicin and sorafenib had no major effect on acquiring complete remission, and the patient died of progressive AML with an exacerbation of HLH and aspergillosis. LSCs are known to be resistant to conventional chemotherapy due to their quiescence in the cell cycle. Novel therapeutic concepts are important to eradicate LSCs in order to cure AML patients. Show less

Prognosis of heart failure with preserved ejection fraction (HFpEF) remains poor because of unknown pathophysiology and unestablished therapeutic strategy. This study aimed to identify a potential therapeutic intervention for HFpEF through metabolomics-based analysis. Metabolomics with capillary electrophoresis time-of-flight mass spectrometry was performed using plasma of Dahl salt-sensitive rats fed high-salt diet, a model of hypertensive HFpEF, and showed decreased free-carnitine levels. Reassessment with enzymatic cycling method revealed the decreased plasma and left-ventricular free-carnitine levels in the HFpEF model. Urinary free-carnitine excretion was increased, and the expression of organic cation/carnitine transporter 2, which transports free-carnitine into cells, was down-regulated in the left ventricle (LV) and kidney in the HFpEF model. L-Carnitine was administered to the hypertensive HFpEF model. L-Carnitine treatment restored left-ventricular free-carnitine levels, attenuated left-ventricular fibrosis and stiffening, prevented pulmonary congestion, and improved survival in the HFpEF model independent of the antihypertensive effects, accompanied with increased expression of fatty acid desaturase (FADS) 1/2, rate-limiting enzymes in forming arachidonic acid, and enhanced production of arachidonic acid, a precursor of prostacyclin, and prostacyclin in the LV. In cultured cardiac fibroblasts, L-carnitine attenuated the angiotensin II-induced collagen production with increased FADS1/2 expression and enhanced production of arachidonic acid and prostacyclin. L-Carnitine-induced increase of arachidonic acid was canceled by knock-down of FADS1 or FADS2 in cultured cardiac fibroblasts. Serum free-carnitine levels were decreased in HFpEF patients. L-carnitine supplementation attenuates cardiac fibrosis by increasing prostacyclin production through arachidonic acid pathway, and may be a promising therapeutic option for HFpEF. Show less