Haem Biosynthesis and Antioxidant Enzymes in Circulating Cells of Acute Intermittent Porphyria Patients

Acute Hepatic Porphyria: Pathophysiological Basis of Neuromuscular Manifestations

Acute hepatic porphyria represents a rare, underdiagnosed group of inherited metabolic disorders due to hereditary defects of heme group biosynthesis pathway. Most patients have their definite diagnosis after several years of complex and disabling clinical manifestations and commonly after life-threatening acute neurovisceral episodes or severe motor handicap. Many key studies in the last two decades have been performed and led to the discovery of novel possible diagnostic and prognostic biomarkers and to the development of new therapeutic purposes, including small interfering RNA-based therapy, specifically driven to inhibit selectively delta-aminolevulinic acid synthase production and decrease the recurrence number of severe acute presentation for most patients. Several distinct mechanisms have been identified to contribute to the several neuromuscular signs and symptoms. This review article aims to present the current knowledge regarding the main pathophysiological mechanisms involved with the acute and chronic presentation of acute hepatic porphyria and to highlight the relevance of such content for clinical practice and in decision making about therapeutic options.

Acute intermittent porphyria (AIP) in a patient with celiac disease

We present the case of an 18 year old Caucasian with known celiac disease, who suffered a severe first attack of acute intermittent porphyria (AIP) with neuropsychiatric symptoms, severe tetraparesis and respiratory insufficiency. Treatment with heme arginate and high-dose intravenous glucose and rigorous rehabilitation resulted in a slow but almost complete recovery of her motor symptoms. To our knowledge this is the first case of acute intermittent porphyria triggered by malnutrition in the context of celiac disease. It is remarkable that the patient showed a favourable outcome despite the severity of her initial symptoms. This case shows the importance of early and systematic symptomatic treatment in patients with severe neurologic manifestation of AIP.

EBF1-Correlated Long Non-coding RNA Transcript Levels in 3rd Trimester Maternal Blood and Risk of Spontaneous Preterm Birth

Biomarkers associated with spontaneous preterm birth (sPTB) before labor onset could aid in prediction, triage, and stratification for testing interventions. In this study we examined maternal blood EBF1-correlated long non-coding RNAs (lncRNAs) in relation to sPTB. We retrieved all lncRNA transcripts from a public gene expression dataset (GSE59491) derived from maternal blood in trimesters 2 and 3 from a Canadian cohort with a matched set of sPTB (n = 51) and term births (n = 106). LncRNA transcripts differentially expressed (limma moderated t-tests) in sPTB vs. term were tested for correlations (Pearson) with EBF1 mRNA levels in the same blood samples. Using logistic regression, EBF1-correlated lncRNAs were divided into tertiles and assessed in relation to odds of sPTB. Two lncRNA transcripts in the 3rd trimester maternal blood were differentially expressed between sPTB and term births (all p < 0.001 and FDR < 0.250) and positively and negatively correlated with EBF1 mRNA levels. They were as follows: (1) LINC00094 r = 0.196 (95% CI: 0.039 to 0.344), p = 0.015, and BH adjusted p = 0.022 and (2) LINC00870 r = - 0.303 (95% CI: - 0.441 to - 0.152), p < 0.001, and BH adjusted p < 0.001. As compared with term births, sPTBs were more likely to be in the highest tertile of LINC00870 (odds ratio (OR) = 4.08 (95% CI 1.60, 10.40), p = 0.003) and the lowest tertile of LINC00094 (OR = 5.16 (95% CI 1.96, 13.61), p < 0.001). Two sPTB-associated EBF1-correlated lncRNAs (LINC00870 and LINC00094) had multiple potential enhancers containing EBF1 binding site(s). Our current findings, along with previous reports linking EBF1 and sPTB, motivate additional research on the EBF1 gene-related gene expression and regulation in relation to sPTB within other cohorts and within laboratory-based models.

Hemolysis-induced Lung Vascular Leakage Contributes to the Development of Pulmonary Hypertension

Although hemolytic anemia-associated pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH) are more common than the prevalence of idiopathic PAH alone, the role of hemolysis in the development of PAH is poorly characterized. We hypothesized that hemolysis independently contributes to PAH pathogenesis via endothelial barrier dysfunction with resulting perivascular edema and inflammation. Plasma samples from patients with and without PAH (both confirmed by right heart catheterization) were used to measure free hemoglobin (Hb) and its correlation with PAH severity. A sugen (50 mg/kg)/hypoxia (3 wk)/normoxia (2 wk) rat model was used to elucidate the role of free Hb/heme pathways in PAH. Human lung microvascular endothelial cells were used to study heme-mediated endothelial barrier effects. Our data indicate that patients with PAH have increased levels of free Hb in plasma that correlate with PAH severity. There is also a significant accumulation of free Hb and depletion of haptoglobin in the rat model. In rats, perivascular edema was observed at early time points concomitant with increased infiltration of inflammatory cells. Heme-induced endothelial permeability in human lung microvascular endothelial cells involved activation of the p38/HSP27 pathway. Indeed, the rat model also exhibited increased activation of p38/HSP27 during the initial phase of PH. Surprisingly, despite the increased levels of hemolysis and heme-mediated signaling, there was no heme oxygenase-1 activation. This can be explained by observed destabilization of HIF-1a during the first 2 weeks of PH regardless of hypoxic conditions. Our data suggest that hemolysis may play a significant role in PAH pathobiology.