Moon James K, Lawrence Kendall M, Hunt Mallory L, Davey Marcus G, Flake Alan W, Licht Daniel J, Chen Jonathan M, Kilbaugh Todd J, Gaynor J William, Beiting Daniel P
Department of Surgery, The Center for Fetal Research, Children's Hospital of Philadelphia, Philadelphia, Pa.
Department of General Surgery, Mount Sinai Hospital, New York, NY.
JTCVS Open. 2022 May 5;10:342-349. doi: 10.1016/j.xjon.2022.04.040. eCollection 2022 Jun.
The molecular pathways underlying hypoxemia-induced alterations in neurodevelopment of infants with congenital heart disease have not been delineated. We used transcriptome analysis to investigate differential gene expression induced by hypoxemia in an ovine artificial-womb model.
Mid-gestation fetal sheep (median [interquartile range] 109 [107-112] days' gestation) were cannulated via the umbilical vessels, attached to a pumpless, low-resistance oxygenator circuit, and incubated in a sterile, fluid environment for 22 [21-23] days. Fetuses were maintained with an oxygen delivery of 20-25 mL/kg/min (normoxemia, n = 3) or 14-16 mL/kg/min (hypoxemia, n = 4). Transcriptional profiling by RNA sequencing was carried out on left frontal brains and hypoxemia-regulated genes were identified by differential gene expression analysis.
A total of 228 genes whose expression was up or down regulated by ≥1.5-fold (false discovery rate ≤0.05) were identified. The majority of these genes were induced in hypoxemic animals compared to normoxemic controls, and functional enrichment analysis identified respiratory electron transport as a pathway strongly upregulated in the brain during chronic hypoxemia. Further examination of hypoxemia-induced genes showed robust induction of all 7 subunits of the mitochondrial NADH:ubiquinone oxidoreductase (complex I). Other hypoxemia-induced genes included cytochrome B, a component of complex III, and ATP6, ATP8, both of which are components of complex V.
Chronic fetal hypoxemia leads to upregulation of multiple mitochondrial respiratory complex genes critical for energy production and reactive oxygen species generation, including complex I. These data provide valuable insight into potential pathways involved in chronic hypoxemia-induced neuropathology and offers potential therapeutic targets for fetal neuroprotection in fetuses with congenital heart defects.
先天性心脏病婴儿低氧血症所致神经发育改变的分子途径尚未明确。我们采用转录组分析方法，在绵羊人工子宫模型中研究低氧血症诱导的基因表达差异。
妊娠中期胎羊（妊娠时间中位数[四分位间距]为109[107 - 112]天）通过脐血管插管，连接到无泵、低阻力氧合器回路，并在无菌液体环境中孵育22[21 - 23]天。胎儿维持氧输送量为20 - 25 mL/kg/min（正常氧血症，n = 3）或14 - 16 mL/kg/min（低氧血症，n = 4）。对左侧额叶脑组织进行RNA测序转录谱分析，并通过差异基因表达分析鉴定低氧血症调节基因。
共鉴定出228个基因，其表达上调或下调≥1.5倍（错误发现率≤0.05）。与正常氧血症对照组相比，这些基因大多数在低氧血症动物中被诱导表达，功能富集分析确定呼吸电子传递是慢性低氧血症期间大脑中强烈上调的一条途径。对低氧血症诱导基因的进一步检查显示，线粒体NADH：泛醌氧化还原酶（复合体I）的所有7个亚基均有强烈诱导表达。其他低氧血症诱导基因包括复合体III的一个组分细胞色素B，以及复合体V的组分ATP6和ATP8。
慢性胎儿低氧血症导致多个对能量产生和活性氧生成至关重要的线粒体呼吸复合体基因上调，包括复合体I。这些数据为慢性低氧血症诱导的神经病理学潜在途径提供了有价值的见解，并为先天性心脏缺陷胎儿的胎儿神经保护提供了潜在的治疗靶点。
