de Mello Vanessa D, Matte Ashok, Perfilyev Alexander, Männistö Ville, Rönn Tina, Nilsson Emma, Käkelä Pirjo, Ling Charlotte, Pihlajamäki Jussi
a Institute of Public Health and Clinical Nutrition, Clinical Nutrition, University of Eastern Finland , Kuopio , Finland.
b Epigenetics and Diabetes Unit, Department of Clinical Sciences , Lund University Diabetes Centre , Malmö , Sweden.
Epigenetics. 2017 Apr 3;12(4):287-295. doi: 10.1080/15592294.2017.1294305. Epub 2017 Feb 23.
Both genetic and lifestyle factors contribute to the risk of non-alcoholic steatohepatitis (NASH). Additionally, epigenetic modifications may also play a key role in the pathogenesis of NASH. We therefore investigated liver DNA methylation, as a marker for epigenetic alterations, in individuals with simple steatosis and NASH, and further tested if these alterations were associated with clinical phenotypes. Liver biopsies obtained from 95 obese individuals (age: 49.5 ± 7.7 years, BMI: 43 ± 5.7 kg/m, type 2 diabetes [T2D]: 35) as a wedge biopsy during a Roux-en-Y gastric bypass operation were investigated. Thirty-four individuals had a normal liver phenotype, 35 had simple steatosis, and 26 had NASH. Genome-wide DNA methylation pattern was analyzed using the Infinium HumanMethylation450 BeadChip. mRNA expression was analyzed from 42 individuals using the HumanHT-12 Expression BeadChip. We identified 1,292 CpG sites representing 677 unique genes differentially methylated in liver of individuals with NASH (q < 0.001), independently of T2D, age, sex, and BMI. Focusing on the top-ranking 30 and another 37 CpG sites mapped to genes enriched in pathways of metabolism (q = 0.0036) and cancer (q = 0.0001) all together, 59 NASH-associated CpG sites correlated with fasting insulin levels independently of age, fasting glucose, or T2D. From these, we identified 30 correlations between DNA methylation and mRNA expression, for example LDHB (r = -0.45, P = 0.003). We demonstrated that NASH, more than simple steatosis, associates with differential DNA methylation in the human liver. These epigenetic alterations in NASH are linked with insulin metabolism.
遗传因素和生活方式因素均会增加非酒精性脂肪性肝炎（NASH）的发病风险。此外，表观遗传修饰可能在NASH的发病机制中也起着关键作用。因此，我们研究了单纯性脂肪变性和NASH患者肝脏中的DNA甲基化情况，以此作为表观遗传改变的标志物，并进一步检测这些改变是否与临床表型相关。研究对象为95名肥胖个体（年龄：49.5±7.7岁，体重指数：43±5.7kg/m²，2型糖尿病患者35例），在Roux-en-Y胃旁路手术中通过楔形活检获取肝脏组织样本。34名个体肝脏表型正常，35名有单纯性脂肪变性，26名有NASH。使用Infinium HumanMethylation450 BeadChip分析全基因组DNA甲基化模式。使用HumanHT-12 Expression BeadChip分析42名个体的mRNA表达情况。我们鉴定出1292个代表677个独特基因的CpG位点，这些位点在NASH患者肝脏中存在差异甲基化（假发现率<0.001），与2型糖尿病、年龄、性别和体重指数无关。聚焦排名前30以及另外37个映射到代谢途径（假发现率=0.0036）和癌症途径（假发现率=0.0001）中富集基因的CpG位点，共59个与NASH相关的CpG位点与空腹胰岛素水平相关，与年龄、空腹血糖或2型糖尿病无关。从中我们鉴定出30个DNA甲基化与mRNA表达之间的相关性，例如LDHB（r=-0.45，P=0.003）。我们证明，与单纯性脂肪变性相比，NASH与人类肝脏中差异DNA甲基化有关。NASH中的这些表观遗传改变与胰岛素代谢相关。
