Jericó Daniel, Córdoba Karol M, Jiang Lei, Schmitt Caroline, Morán María, Sampedro Ana, Alegre Manuel, Collantes María, Santamaría Eva, Alegre Estíbaliz, Culerier Corinne, de Mendoza Ander Estella-Hermoso, Oyarzabal Julen, Martín Miguel A, Peñuelas Iván, Ávila Matías A, Gouya Laurent, Martini Paolo G V, Fontanellas Antonio
Hepatology Program, Centre for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain.
Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain.
Mol Ther Nucleic Acids. 2021 May 19;25:207-219. doi: 10.1016/j.omtn.2021.05.010. eCollection 2021 Sep 3.
Variegate porphyria (VP) results from haploinsufficiency of protoporphyrinogen oxidase (PPOX), the seventh enzyme in the heme synthesis pathway. There is no VP model that recapitulates the clinical manifestations of acute attacks. Combined administrations of 2-allyl-2-isopropylacetamide and rifampicin in rabbits halved hepatic PPOX activity, resulting in increased accumulation of a potentially neurotoxic heme precursor, lipid peroxidation, inflammation, and hepatocyte cytoplasmic stress. Rabbits also showed hypertension, motor impairment, reduced activity of critical mitochondrial hemoprotein functions, and altered glucose homeostasis. Hemin treatment only resulted in a slight drop in heme precursor accumulation but further increased hepatic heme catabolism, inflammation, and cytoplasmic stress. Hemin replenishment did protect against hypertension, but it failed to restore action potentials in the sciatic nerve or glucose homeostasis. Systemic porphobilinogen deaminase (PBGD) mRNA administration increased hepatic PBGD activity, the third enzyme of the pathway, and rapidly normalized serum and urine porphyrin precursor levels. All features studied were improved, including those related to critical hemoprotein functions. In conclusion, the VP model recapitulates the biochemical characteristics and some clinical manifestations associated with severe acute attacks in humans. Systemic PBGD mRNA provided successful protection against the acute attack, indicating that PBGD, and not PPOX, was the critical enzyme for hepatic heme synthesis in VP rabbits.
混合型卟啉病(VP)是由于血红素合成途径中的第七种酶——原卟啉原氧化酶(PPOX)单倍剂量不足所致。目前尚无能够重现急性发作临床表现的VP模型。在兔体内联合给予2-烯丙基-2-异丙基乙酰胺和利福平,可使肝脏PPOX活性减半,导致潜在神经毒性血红素前体的积累增加、脂质过氧化、炎症以及肝细胞胞质应激。兔还表现出高血压、运动功能障碍、关键线粒体血红蛋白功能活性降低以及葡萄糖稳态改变。血红素治疗仅使血红素前体积累略有下降,但进一步增加了肝脏血红素分解代谢、炎症和胞质应激。补充血红素确实可预防高血压,但未能恢复坐骨神经动作电位或葡萄糖稳态。全身性给予胆色素原脱氨酶(PBGD)mRNA可增加该途径第三种酶——肝脏PBGD的活性,并迅速使血清和尿液卟啉前体水平恢复正常。所研究的所有特征均得到改善,包括与关键血红蛋白功能相关的特征。总之,该VP模型重现了与人类严重急性发作相关的生化特征和一些临床表现。全身性PBGD mRNA成功预防了急性发作,表明在VP兔中,PBGD而非PPOX是肝脏血红素合成的关键酶。