BACKGROUND AND AIMS The acute porphyrias are characterized by defects in heme synthesis, particularly in the liver. In some affected patients, there occurs a critical deficiency in a regulatory heme pool within hepatocytes that leads to up-regulation of 5-aminolevulinic acid [ALA] synthase-1, which is the first and normally rate-controlling enzyme in the pathway. In earlier work, we described defects in mitochondrial functions in cultured skin fibroblasts from patients with acute intermittent porphyria [AIP]. Others described defects in livers of murine models of AIP. Here, we explored mitochondrial energetics in peripheral blood mononuclear cells [PBMCs] and platelets in persons with AIP and hereditary coproporphyria [HCP]. Our hypotheses were that there are deficits in bioenergetic capacity in acute porphyrias and that subjects with more severe acute porphyria have more pronounced reductions in mitochondrial oxygen consumption rates [OCR]. METHODS We studied 17 subjects with acute hepatic porphyrias, 14 with classical AIP, one with severe AIP due to homozygous deficiency of hydroxymethylbilane synthase [HMBS], 2 with HCP, and 5 non-porphyric controls. We collected peripheral blood, isolated PBMCs, which we assayed either immediately or after frozen storage [80C] for up to 14 days. Using Seahorse XF-24-3, we measured OCR in the presence of glucose + pyruvate under basal condition, and after additions of oligomycin, carbonylcyanide p-trifluoromethoxyphenylhydrazone [FCCP], and antimycin+rotenone. RESULTS Most subjects [13/17, 76%] were female. Subjects with moderate/severe symptoms associated with acute porphyria had significantly lower basal and maximal-OCR than those with no/mild symptoms who were the same as controls. We observed significant inverse correlation between urinary porphobilinogen [PBG] excretion and OCR. The subject with homozygous AIP had a much lower-OCR than his asymptomatic parents. SUMMARY/CONCLUSIONS Results support the hypothesis that active acute hepatic porphyria is characterized by a deficiency in mitochondrial function that is detectable in PBMCs, suggesting that limitations in electron transport and ATP production exist in such individuals.

中文翻译：

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急性卟啉症患者线粒体生物能学的初步研究。

背景和目的急性卟啉症的特征在于血红素合成中的缺陷，特别是在肝脏中。在一些受影响的患者中，肝细胞内血红素库的严重缺陷会导致5-氨基乙酰丙酸[ALA]合酶-1的上调，这是该途径中的第一种且通常是速率控制酶。在较早的工作中，我们描述了急性间歇性卟啉症[AIP]患者培养的皮肤成纤维细胞中线粒体功能的缺陷。其他人则描述了AIP鼠模型肝脏的缺陷。在这里，我们探索了AIP和遗传性卟啉病[HCP]患者外周血单核细胞[PBMC]和血小板中的线粒体能量。我们的假设是，急性卟啉症的生物能能力存在缺陷，而急性卟啉症的受试者的线粒体耗氧率[OCR]降低更为明显。方法我们研究了17例急性肝卟啉症患者，14例经典AIP患者，1例由于羟甲基胆烷合酶[HMBS]纯合性缺乏而导致严重AIP患者，2例HCP患者和5例非卟啉对照。我们收集了外周血，分离出的PBMC，我们立即进行了分析或将其冷冻保存[80C] 14天后进行了分析。使用Seahorse XF-24-3，我们在基础条件下，在葡萄糖+丙酮酸存在下，以及加入寡霉素，羰基氰化物对-三氟甲氧基苯基hydr [FCCP]和抗霉素+鱼藤酮后，测量了OCR。结果大多数受试者[13 / 17，76％]为女性。与急性卟啉症相关的中度/重度症状的受试者的基础和最大OCR显着低于无/轻度症状的受试者（与对照组相同）。我们观察到尿中胆红素原[PBG]的排泄与OCR之间存在显着的负相关。具有纯合AIP的受试者的OCR比无症状父母的OCR低得多。总结/结论结果支持以下假设：活动性急性肝卟啉症的特征在于线粒体功能的缺陷，在PBMC中可检测到，这表明此类个体存在电子转运和ATP产生的局限性。我们观察到尿中胆红素原[PBG]的排泄与OCR之间存在显着的负相关。具有纯合AIP的受试者的OCR比无症状父母的OCR低得多。总结/结论结果支持以下假设：活动性急性肝卟啉症的特征在于线粒体功能的缺陷，在PBMC中可检测到，这表明此类个体存在电子转运和ATP产生的局限性。我们观察到尿中胆红素原[PBG]的排泄与OCR之间存在显着的负相关。具有纯合AIP的受试者的OCR比无症状父母的OCR低得多。总结/结论结果支持以下假设：活动性急性肝卟啉症的特征在于线粒体功能的缺陷，在PBMC中可检测到，这表明此类个体存在电子转运和ATP产生的局限性。