Systemic inflammation in acute intermittent porphyria: a case-control study

Update on heme biosynthesis, tissue-specific regulation, heme transport, relation to iron metabolism and cellular energy

Heme is a primordial macrocycle upon which most aerobic life on Earth depends. It is essential to the survival and health of nearly all cells, functioning as a prosthetic group for oxygen-carrying proteins and enzymes involved in oxidation/reduction and electron transport reactions. Heme is essential for the function of numerous hemoproteins and has numerous other roles in the biochemistry of life. In mammals, heme is synthesised from glycine, succinyl-CoA, and ferrous iron in a series of eight steps. The first and normally rate-controlling step is catalysed by 5-aminolevulinate synthase (ALAS), which has two forms: ALAS1 is the housekeeping form with highly variable expression, depending upon the supply of the end-product heme, which acts to repress its activity; ALAS2 is the erythroid form, which is regulated chiefly by the adequacy of iron for erythroid haemoglobin synthesis. Abnormalities in the several enzymes of the heme synthetic pathway, most of which are inherited partial enzyme deficiencies, give rise to rare diseases called porphyrias. The existence and role of heme importers and exporters in mammals have been debated. Recent evidence established the presence of heme transporters. Such transporters are important for the transfer of heme from mitochondria, where the penultimate and ultimate steps of heme synthesis occur, and for the transfer of heme from cytoplasm to other cellular organelles. Several chaperones of heme and iron are known and important for cell health. Heme and iron, although promoters of oxidative stress and potentially toxic, are essential cofactors for cellular energy production and oxygenation.

A case report of acute intermittent porphyria leading to severe disability

Acute intermittent porphyria (AIP) is a rare inherited metabolic disorder resulting from increased production of porphyrins and their precursors, δ-aminolevulinic acid (ALA) and porphobilinogen (PBG), due to deficiencies in the enzymatic activity of the heme synthesis pathway. The disease is typically characterized by a triad of abdominal pain, neurologic impairment symptoms, and psychiatric abnormalities. However, only a small percentage of patients present with this classic triad of symptoms. Our female patient, aged 23, was admitted to the hospital with a 4-year history of abnormal mood episodes and weakness in the limbs for over 1 week. She had a previous medical history of intestinal obstruction. After admission, a cranial MRI revealed reversible posterior leukoencephalopathy imaging manifestations, and the patient exhibited weakness of the extremities, respiratory failure, seizures, and severely reduced serum sodium concentration. The diagnosis of AIP was ultimately confirmed by a positive urine PBG-sunlight test and analysis of HMBS gene variants. The absence of typical triadic signs in acute attacks of AIP can make early recognition of the disease challenging. We present a case with multiple typical clinical manifestations of AIP in the hope of aiding clinicians in fully recognizing acute intermittent porphyria.

Potential Biomarkers for the Earlier Diagnosis of Kidney and Liver Damage in Acute Intermittent Porphyria

Acute intermittent porphyria (AIP) is an inherited metabolic disorder associated with complications including kidney failure and hepatocellular carcinoma, probably caused by elevations in the porphyrin precursors porphobilinogen (PBG) and delta-aminolevulinic acid (ALA). This study explored differences in modern biomarkers for renal and hepatic damage between AIP patients and controls. Urine PBG testing, kidney injury panels, and liver injury panels, including both routine and modern biomarkers, were performed on plasma and urine samples from AIP cases and matched controls (50 and 48 matched pairs, respectively). Regarding the participants' plasma, the AIP cases had elevated kidney injury marker-1 (KIM-1, p = 0.0002), fatty acid-binding protein-1 (FABP-1, p = 0.04), and α-glutathione S-transferase (α-GST, p = 0.001) compared to the matched controls. The AIP cases with high PBG had increased FABP-1 levels in their plasma and urine compared to those with low PBG. In the AIP cases, KIM-1 correlated positively with PBG, CXCL10, CCL2, and TCC, and the liver marker α-GST correlated positively with IL-13, CCL2, and CCL4 (all p < 0.05). In conclusion, KIM-1, FABP-1, and α-GST could represent potential early indicators of renal and hepatic damage in AIP, demonstrating associations with porphyrin precursors and inflammatory markers.

Acute intermittent porphyria complicated with acute pancreatitis: A case report and literature review

RATIONALE

Acute intermittent porphyria (AIP) is a rare genetic disorder that affects porphyrin metabolism in the blood. The disease causes defects in specific enzymes in the body, which in turn leads to the accumulation of porphyrin metabolites. Patients may experience abdominal pain, neurological symptoms, muscle pain, and nausea, but it does not directly cause pancreatitis.

PATIENT CONCERNS

The patient is a young woman, 23 years old, who was admitted to our hospital with intermittent abdominal pain for 2 days, the pain was not fixed, episodic, with no obvious trigger, and 1 day before admission, the patient started to experience nausea and vomiting, with gastric contents as the vomitus, and similar symptoms had occurred many times in the past. Blood amylase 600 U/L, blood sodium 120.6 mmol/L, blood routine, and coagulation function results were normal; abdominal CT showed pancreatic swelling with unclear surrounding fat interstitial, acute pancreatitis was considered. The patient's urine was dark red, and the results of the qualitative urine porphyrin test were positive.

DIAGNOSES

AIP complicated with acute pancreatitis.

INTERVENTION

Relief of symptoms, control of pain, correction of electrolyte disturbances, and high-carbohydrate therapy.

OUTCOMES

The patient was discharged with complete symptomatic relief after 10 days of high-carbohydrate therapy.

LESSONS

AIP complicated with acute pancreatitis is very rare. Treatment of AIPs aims to control acute attacks and prevent potential triggers.

Control of porphyria cutanea tarda with anti-IL-17 secukinumab in a person with psoriasis living with HIV

A 65-year-old woman successfully treated for human immunodeficiency virus (HIV) and Hepatitis C virus was diagnosed with porphyria cutanea tarda (PCT) and treated by phlebotomies. She developed extensive psoriatic skin lesions resistant to topical treatments and methotrexate. She then received the anti-interleukin-17 (IL-17) secukinumab (Cosentyx) which improved her psoriatic skin lesions. Unexpectedly, her PCT skin lesions healed, allowing phlebotomy discontinuation over 2 years. Without lesions, the patient decided to discontinue secukinumab, leading to the recurrence of psoriatic and PCT skin lesions, which were controlled upon therapeutical rechallenge. No AIDS-related manifestations or infections developed, her CD4 count remained elevated and her HIV viral load was controlled under antiretroviral therapy. Both skin conditions and consequently the patient's quality of life have improved with secukinumab, allowing exposure to sunlight and phlebotomy discontinuation for >4 years. Likely, the IL-17 pathway is involved in the clinical manifestations of PCT, opening new avenues for therapeutical interventions.

Transcriptome profile analysis reveals putative molecular mechanisms of 5-aminolevulinic acid toxicity

5-aminolevulinic acid (5-ALA) is the first precursor of the heme biosynthesis pathway, accumulated in acute intermittent porphyria (AIP), an inherited metabolic disease characterized by porphobilinogen deaminase deficiency. An increased incidence of hepatocellular carcinoma (HCC) has been reported as a long-term manifestation in symptomatic AIP patients. 5-ALA is an α-aminoketone prone to oxidation, yielding reactive oxygen species and 4,5-dioxovaleric acid. A high concentration of 5-ALA presents deleterious pro-oxidant potential. It can induce apoptosis, DNA damage, mitochondrial dysfunction, and altered expression of carcinogenesis-related proteins. Several hypotheses of the increased risk of HCC rely on the harmful effect of elevated 5-ALA in the liver of AIP patients, which could promote a pro-carcinogenic environment. We investigated the global transcriptional changes and perturbed molecular pathways in HepG2 cells following exposure to 5-ALA 25 mM for 2 h and 24 h using DNA microarray. Distinct transcriptome profiles were observed. 5-ALA '25 mM-2h' upregulated 10 genes associated with oxidative stress response and carcinogenesis. Enrichment analysis of differentially expressed genes by KEGG, Reactome, MetaCore™, and Gene Ontology, showed that 5-ALA '25 mM-24h' enriched pathways involved in drug detoxification, oxidative stress, DNA damage, cell death/survival, cell cycle, and mitochondria dysfunction corroborating the pro-oxidant properties of 5-ALA. Furthermore, our results disclosed other possible processes such as senescence, immune responses, endoplasmic reticulum stress, and also some putative effectors, such as sequestosome, osteopontin, and lon peptidase 1. This study provided additional knowledge about molecular mechanisms of 5-ALA toxicity which is essential to a deeper understanding of AIP and HCC pathophysiology. Furthermore, our findings can contribute to improving the efficacy of current therapies and the development of novel biomarkers and targets for diagnosis, prognosis, and therapeutic strategies for AHP/AIP and associated HCC.

Acute Intermittent Porphyria Attack Triggered by COVID-19 Infection

A 45-year-old male patient who was diagnosed with acute intermittent porphyria (AIP) four years ago and had his last episode two years prior presented to our clinic with an AIP attack complicated with rhabdomyolysis triggered by coronavirus disease 2019 (COVID-19) infection. Although there are well-known factors that might trigger an AIP attack, some studies also showed an association of COVID-19 with porphyria. These studies suggest that the accumulation of by-products in the heme synthesis pathway during COVID-19 infection may cause attacks mimicking acute intermittent porphyria. In respect to that, in the early phases of the pandemic, hypotheses emerged arguing the treatment of severe COVID-19 infections with hemin as the treatment of an AIP attack. In our instance, after a two-year period during which there had not been an episode, there was no evident cause other than COVID-19 infection. We believe that patients with porphyria are particularly prone to exacerbations during a COVID-19 infection and should be monitored carefully.

Pathogenesis of acute encephalopathy in acute hepatic porphyria

Acute encephalopathy (AE) can be a manifestation of an acute porphyric attack. Clinical data were studied in 32 patients during AE with or without polyneuropathy (PNP) together with 12 subjects with PNP but no AE, and 17 with dysautonomia solely. Brain neuroimaging was done in 20 attacks during AE, and PEPT2 polymorphisms were studied in 56 subjects, 24 with AE. AE manifested as a triad of seizures, confusion and/or blurred vision. Symptoms lasting 1-5 days manifested 3-19 days from the onset of an attack. 55% of these patients had acute PNP independent of AE. Posterior reversible encephalopathy syndrome (PRES) was detected in 42% of the attacks. These patients were severely affected and hyponatremic (88%). Reversible segmental vasoconstriction was rare. There was no statistical difference in hypertension or urinary excretion of porphyrin precursors among the patients with or without AE. In 94% of the attacks with AE, liver transaminases were elevated significantly (1.5 to fivefold, P = 0.034) compared to a normal level in 87% of the attacks with dysautonomia, or in 25% of patients with PNP solely. PEPT2*2/2 haplotype was less common among patients with AE than without (8.3% vs. 25.8%, P = 0.159) and in patients with PNP than without (9.5% vs. 22.9%, P = 0.207), suggesting a minor role, if any, in acute neurotoxicity. In contrast, PEPT2*2/2 haplotype was commoner among patients with chronic kidney disease (P = 0.192). Acute endothelial dysfunction in porphyric encephalopathy could be explained by a combination of abrupt hypertension, SIADH, and acute metabolic and inflammatory factors of hepatic origin.

Understanding Carbohydrate Metabolism and Insulin Resistance in Acute Intermittent Porphyria

Porphobilinogen deaminase (PBGD) haploinsufficiency (acute intermittent porphyria, AIP) is characterized by neurovisceral attacks associated with high production, accumulation and urinary excretion of heme precursors, δ-aminolevulinic acid (ALA) and porphobilinogen (PBG). The estimated clinical penetrance for AIP is extremely low (<1%), therefore it is likely that other factors may play an important role in the predisposition to developing attacks. Fasting is a known triggering factor. Given the increased prevalence of insulin resistance in patients and the large urinary loss of succinyl-CoA to produce ALA and PBG, we explore the impact of reduced availability of energy metabolites in the severity of AIP pathophysiology. Classic studies found clinical improvement in patients affected by AIP associated with the administration of glucose and concomitant insulin secretion, or after hyperinsulinemia associated with diabetes. Molecular studies have confirmed that glucose and insulin administration induces a repressive effect on hepatic ALA Synthase, the first and regulatory step of the heme pathway. More recently, the insulin-mimicking α-lipoic acid has been shown to improve glucose metabolism and mitochondrial dysfunction in a hepatocyte cell line transfected with interfering RNA targeting PBGD. In AIP mice, preventive treatment with an experimental fusion protein of insulin and apolipoprotein A-I improved the disease by promoting fat mobilization in adipose tissue, increasing the metabolite bioavailability for the TCA cycle and inducing mitochondrial biogenesis in the liver. In this review, we analyze the possible mechanisms underlying abnormal hepatocellular carbohydrate homeostasis in AIP.

Pain in acute hepatic porphyrias: Updates on pathophysiology and management

Acute hepatic porphyrias (AHPs) typically present with recurrent acute attacks of severe abdominal pain and acute autonomic dysfunction. While chronic symptoms were historically overlooked in the literature, recent studies have reported increased prevalence of chronic, mainly neuropathic, pain between the attacks. Here we characterize acute and chronic pain as prominent manifestations of the AHPs and discuss their pathophysiology and updated management. In addition to the severe abdominal pain, patients could experience low back pain, limb pain, and headache during acute attacks. Chronic pain between the attacks is typically neuropathic and reported mainly by patients who undergo recurrent attacks. While the acute abdominal pain during attacks is likely mediated by autonomic neuropathy, chronic pain likely represents delayed recovery of the acute neuropathy with ongoing small fiber neuropathy in addition to peripheral and/or central sensitization. δ-aminolaevulinic acid (ALA) plays a major role in acute and chronic pain via its neurotoxic effect, especially where the blood-nerve barrier is less restrictive or absent i.e., the autonomic ganglia, nerve roots, and free nerve endings. For earlier diagnosis, we recommend testing a spot urine porphobilinogen (PBG) analysis in any patient with recurrent severe acute abdominal pain with no obvious explanation, especially if associated with neuropathic pain, hyponatremia, autonomic dysfunction, or encephalopathy. Of note, it is mandatory to exclude AHPs in any acute painful neuropathy. Between the attacks, diagnostic testing for AHPs should be considered for patients with a past medical history of acute/subacute neuropathy, frequent emergency room visits with abdominal pain, and behavioral changes. Pain during the attacks should be treated with opiates combined with hemin infusions. Symptomatic treatment of chronic pain should start with gabapentinoids and certain antidepressants before opiates. Givosiran reduces levels of ALA and PBG and likely has long-term benefits for chronic pain, especially if started early during the course of the disease.

Case Report: Variegate porphyria disclosed by post-gastric bypass complications and causing predominant painful sensorimotor axonal peripheral neuropathy

Background and aims: Porphyrias constitute a group of rare genetic diseases due to various, mostly autosomal dominant mutations, causing enzymatic deficiency in heme biosynthesis. As a result, neurotoxic porphyrin precursors and light-sensitive porphyrins accumulate, while dysfunction in their targets determines the disease symptoms. Variegate porphyria (VP), one of the acute hepatic porphyrias, is caused by a protoporphyrinogen oxidase (PPOX) mutation. During acute attacks, among other factors, triggered by drugs, stressors, or fasting, an increase in urinary and fecal porphobilinogen (PBG), aminolevulinic acid (ALA), and porphyrins occurs, damaging the autonomous, peripheral, or central nervous system. The disease remains often latent or displays minimal symptoms usually overlooked, exposing undiagnosed patients to potentially serious complications in the presence of the aforementioned triggers.

Case report: This 46-year-old woman presented, some days after a bariatric surgery, with severe flaccid tetraparesis and neuropathic pain, initially misdiagnosed as a functional neurological disorder. The severe axonal sensorimotor polyneuropathy led to further investigations, disclosing high urinary porphobilinogen, ALA, and porphyrin levels due to a new PPOX mutation. Retrospectively, it appeared that the patient had had typical VP symptoms (abdominal pain, fragile skin, and dark urine episodes) for years prior to the surgery. Treated with carbohydrate load, neurorehabilitation, and analgesics, she slowly recovered to full mobility, with partial autonomy in her daily life activities, although fatigue and severe pain persisted, preventing her from returning to work.

Conclusion: This case documents gastric bypass surgery as a trigger of severe VP invalidating neurological symptoms and illustrates how the delayed diagnosis and post-interventional complications could have been prevented by screening for porphyria cardinal symptoms prior to the intervention. Likewise, this cost-effective screening should be performed before any treatment influencing the diet, which would dramatically improve the porphyria diagnosis rate and outcome.

Dental and Periodontal Health in Acute Intermittent Porphyria

In the inherited metabolic disorder acute intermittent porphyria (AIP), high sugar intake prevents porphyric attacks due to the glucose effect and the following high insulin levels that may lower AIP disease activity. Insulin resistance is a known risk factor for periodontitis and sugar changes diabetogenic hormones and affects dental health. We hypothesized differences in homeostasis model assessment (HOMA) scores for insulin resistance in AIP cases vs. controls and in those with periodontitis. Our aim was to systematically study dental health in AIP as poor dental health was previously only described in case reports. Further, we aimed to examine if poor dental health and kidney failure might worsen AIP as chronic inflammation and kidney failure might increase disease activity. In 47 AIP cases and 47 matched controls, X-rays and physical examination of clinical attachment loss (CAL), probing pocket depth (PPD), and decayed missing filled teeth (DMFT) were performed. Dietary intake was evaluated through a diet logbook. Plasma cytokines and diabetogenic hormones were measured using multiplex technology and urine porphobilinogen and kidney and liver function by routine methods. An excel spreadsheet from the University of Oxford was used to estimate HOMA scores; beta cell function, HOMA%B (%B), insulin sensitivity, HOMA%S (%S), and insulin resistance HOMA-IR (IR), based on glucose and plasma (P) C-peptide. The Wilcoxon matched-pairs signed rank test, the Mann−Whitney U-test, and Spearman’s non-parametric correlation were used. Insulin (p = 0.007) and C-peptide (p = 0.006) were higher in the AIP cases with periodontitis versus those without. In AIP patients, the liver fibrosis index 4 correlated with DMFT (p < 0.001) and CAL ≥4 mm (p = 0.006); the estimated glomerular filtration rate correlated with DMFT (p < 0.001) and CAL ≥4 mm (p = 0.02). CAL ≥4 mm was correlated with chemokine ligand 11 and interleukin (IL)-13 (p = 0.04 for both), and PPD >5 mm was correlated with plasminogen activator inhibitor-1 (p = 0.003) and complement component 3 (p = 0.02). In conclusion, dental health in AIP cases was correlated with insulin resistance, inflammatory markers, and biomarkers of kidney and liver function, demonstrating that organ damage in the kidney and liver are associated with poorer dental health.

Therapy Follows Diagnosis: Old and New Approaches for the Treatment of Acute Porphyrias, What We Know and What We Should Know

Heme, iron protoporphyrin IX, is one of life's most central molecules. Hence, availability of the enzymatic machinery necessary for its synthesis is crucial for every cell. Consequently, inborn errors of porphyrin metabolism that compromise normal synthesis, namely the family of porphyrias, undermine normal cellular metabolism given that heme has functions in catalytic centers, signal transduction and functional regulation and its synthesis is fully integrated into the center of intermediary metabolism. Very often, diagnosis of porphyrias is difficult and therefore delayed. Therapy can be as complicated. Over the last 50 years, several strategies have been developed: because of its integration with other parts of intermediary metabolism, the infusion of glucose (glucose effect) was one of the first attempts to counterbalance the dysregulation of porphyrin synthesis in porphyrias. Since heme synthesis is impaired, infusional replacement of heme was the next important therapeutic step. Recently, siRNA technology has been introduced in order to downregulate 5-ALA-synthase 1, which contributes to the patho-physiology of these diseases. Moreover, other novel therapies using enzyme protein replacement, mRNA techniques or proteostasis regulators are being developed.

Considerations and recommendations for assessment of plasma protein binding and drug-drug interactions for siRNA therapeutics

At the time of writing, although siRNA therapeutics are approved for human use, no official regulatory guidance specific to this modality is available. In the absence of guidance, preclinical development for siRNA followed a hybrid of the small molecule and biologics guidance documents. However, siRNA differs significantly from small molecules and protein-based biologics in its physicochemical, absorption, distribution, metabolism and excretion properties, and its mechanism of action. Consequently, certain reports typically included in filing packages for small molecule or biologics may benefit from adaption, or even omission, from an siRNA filing. In this white paper, members of the 'siRNA working group' in the IQ Consortium compile a list of reports included in approved siRNA filing packages and discuss the relevance of two in vitro reports-the plasma protein binding evaluation and the drug-drug interaction risk assessment-to support siRNA regulatory filings. Publicly available siRNA approval packages and the literature were systematically reviewed to examine the role of siRNA plasma protein binding and drug-drug interactions in understanding pharmacokinetic/pharmacodynamic relationships, safety and translation. The findings are summarized into two decision trees to help guide industry decide when in vitro siRNA plasma protein binding and drug-drug interaction studies are warranted.

Evaluation of Metabolic Changes in Acute Intermittent Porphyria Patients by Targeted Metabolomics

Acute intermittent porphyria (AIP) is an inherited rare hepatic disorder due to mutations within the hydroxymethylbilane gene. AIP patients with active disease overproduce aminolevulinic acid (ALA) and porphobilinogen (PBG) in the liver which are exported inducing severe neurological attacks. Different hepatic metabolic abnormalities have been described to be associated with this condition. The goal of this research was to explore the metabolome of symptomatic AIP patients by state-of-the art liquid chromatography-tandem mass spectrometry (LC-MS/MS). A case versus control study including 18 symptomatic AIP patients and 33 healthy controls was performed. Plasmatic levels of 51 metabolites and 16 ratios belonging to four metabolic pathways were determined. The results showed that the AIP patients presented significant changes in the two main areas of the metabolome under study: (a) the tryptophan/kynurenine pathway with an increase of tryptophan in plasma together with increase of the kynurenine/tryptophan ratio; and (b) changes in the tricarboxylic acid cycle (TCA) including increase of succinic acid and decrease of the fumaric acid/succinic acid ratio. We performed a complementary in vitro study adding ALA to hepatocytes media that showed some of the effects on the TCA cycle were parallel to those observed in vivo. Our study confirms in plasma previous results obtained in urine showing that AIP patients present a moderate increase of the kynurenine/tryptophan ratio possibly associated with inflammation. In addition, it also reports changes in the mitochondrial TCA cycle that, despite requiring further research, could be associated with an energy misbalance due to sustained overproduction of heme-precursors in the liver.

Neuro-immune-metabolism: The tripod system of homeostasis

Homeostatic regulation of cellular and molecular processes is essential for the efficient physiological functioning of body organs. It requires an intricate balance of several networks throughout the body, most notable being the nervous, immune and metabolic systems. Several studies have reported the interactions between neuro-immune, immune-metabolic and neuro-metabolic pathways. Current review aims to integrate the information and show that neuro, immune and metabolic systems form the triumvirate of homeostasis. It focuses on the cellular and molecular interactions occurring in the extremities and intestine, which are innervated by the peripheral nervous system and for the intestine in particular the enteric nervous system. While the interdependence of neuro-immune-metabolic pathways provides a fallback mechanism in case of disruption of homeostasis, in chronic pathologies of continued disequilibrium, the collapse of one system spreads to the other interacting networks as well. Current review illustrates this domino-effect using diabetes as the main example. Together, this review attempts to provide a holistic picture of the integrated network of neuro-immune-metabolism and attempts to broaden the outlook when devising a scientific study or a treatment strategy.

α-Lipoic Acid Improves Hepatic Metabolic Dysfunctions in Acute Intermittent Porphyria: A Proof-of-Concept Study

BACKGROUND

Acute intermittent porphyria (AIP) is caused by the haploinsufficiency of porphobilinogen deaminase (PBGD) enzymatic activity. Acute attacks occur in response to fasting, and alterations in glucose metabolism, insulin resistance, and mitochondrial turnover may be involved in AIP pathophysiology. Therefore, we investigated the metabolic pathways in PBGD-silenced hepatocytes and assessed the efficacy of an insulin mimic, α-lipoic acid (α-LA), as a potential therapeutic strategy.

METHODS

HepG2 cells were transfected with siRNA-targeting PBGD (siPBGD). Cells were cultured with low glucose concentration to mimic fasting and exposed to α-LA alone or with glucose.

RESULTS

At baseline, siPBGD cells showed a lower expression of genes involved in glycolysis and mitochondrial dynamics along with reduced total ATP levels. Fasting further unbalanced glycolysis by inducing ATP shortage in siPBGD cells and activated DRP1, which mediates mitochondrial separation. Consistently, siPBGD cells in the fasted state showed the lowest protein levels of Complex IV, which belongs to the oxidative phosphorylation (OXPHOS) machinery. α-LA upregulated glycolysis and prompted ATP synthesis and triglyceride secretion, thus possibly providing energy fuels to siPBGD cells by improving glucose utilization. Finally, siPBGD exposed to α-LA plus glucose raised mitochondrial dynamics, OXPHOS activity, and energy production.

CONCLUSIONS

α-LA-based therapy may ameliorate glucose metabolism and mitochondrial dysfunctions in siPBGD hepatocytes.

Multiple roles of haem in cystathionine β-synthase activity: implications for hemin and other therapies of acute hepatic porphyria

The role of haem in the activity of cystathionine β-synthase (CBS) is reviewed and a hypothesis postulating multiple effects of haem on enzyme activity under conditions of haem excess or deficiency is proposed, with implications for some therapies of acute hepatic porphyrias. CBS utilises both haem and pyridoxal 5′-phosphate (PLP) as cofactors. Although haem does not participate directly in the catalytic process, it is vital for PLP binding to the enzyme and potentially also for CBS stability. Haem deficiency can therefore undermine CBS activity by impairing PLP binding and facilitating CBS degradation. Excess haem can also impair CBS activity by inhibiting it via CO resulting from haem induction of haem oxygenase 1 (HO 1), and by induction of a functional vitamin B₆ deficiency following activation of hepatic tryptophan 2,3-dioxygenase (TDO) and subsequent utilisation of PLP by enhanced kynurenine aminotransferase (KAT) and kynureninase (Kynase) activities. CBS inhibition results in accumulation of the cardiovascular risk factor homocysteine (Hcy) and evidence is emerging for plasma Hcy elevation in patients with acute hepatic porphyrias. Decreased CBS activity may also induce a proinflammatory state, inhibit expression of haem oxygenase and activate the extrahepatic kynurenine pathway (KP) thereby further contributing to the Hcy elevation. The hypothesis predicts likely changes in CBS activity and plasma Hcy levels in untreated hepatic porphyria patients and in those receiving hemin or certain gene-based therapies. In the present review, these aspects are discussed, means of testing the hypothesis in preclinical experimental settings and porphyric patients are suggested and potential nutritional and other therapies are proposed.

Catamenial Acute Intermittent Porphyria Managed with GnRH Analogues and Estrogen and Progesterone Add-back Therapy

BACKGROUND

Catamenial precipitation of attacks of acute intermittent porphyria (AIP) is commonly treated with gonadotropin-releasing hormone analogues (GnRHas). However, this leads to various adverse effects that might necessitate "add-back" therapy with estrogen. The literature on the efficacy and safety of such therapy is scarce.

CASE

A 15-year-old girl presented to us with recurrent catamenial attacks of AIP. GnRHa therapy led to near-complete amelioration of the episodes but her bone density worsened as an adverse effect. To circumvent this, low-dose estrogen was added to her regimen as an "add-back" therapy, which was later coupled with cyclical progesterone. She continues to do well using this regimen, with no new episodes.

SUMMARY AND CONCLUSION

GnRHa therapy with estrogen "add-back" is an attractive option for treating catamenial AIP episodes.

Nutrients and Porphyria: An Intriguing Crosstalk

Porphyria refers to a group of fascinating diseases from a metabolic and nutritional standpoint as it provides an example of how metabolic manipulation can be used for therapeutic purposes. It is characterized by defects in heme synthesis, particularly in the erythrocytes and liver. Specific enzymes involved in heme biosynthesis directly depend on adequate levels of vitamins and minerals in the tissues. Moreover, micronutrients that are required for producing succinyl CoA and other intermediates in the Krebs (TCA) cycle are indirectly necessary for heme metabolism. This review summarizes articles that describe the nutritional status, supplements intake, and dietary practices of patients affected by porphyria, paying special attention to the therapeutic use of nutrients that may help or hinder this group of diseases.

Porphyria-induced posterior reversible encephalopathy syndrome and central nervous system dysfunction

BACKGROUND AND AIM

An association between neuropsychiatric manifestations and neuroimaging suggestive of posterior reversible encephalopathy syndrome (PRES) during porphyric attacks has been described in numerous case reports. We aimed to systematically review clinical-radiological features and likely pathogenic mechanisms of PRES in patients with acute hepatic porphyrias (AHP) and porphyric attacks.

METHODS

PubMed, Scopus, Ovid MEDLINE, and Google Scholar were searched (July 30, 2019). We included articles describing patients with convincing evidence of an AHP, confirmed porphyric attacks, and PRES in neuroimaging.

RESULTS

Forty-three out of 269 articles were included, which reported on 46 patients. Thirty-nine (84.8%) patients were women. The median age was 24 ± 13.8 years. 52.2% had unspecified AHP, 41.3% acute intermittent porphyria, 4.3% hereditary coproporphyria, and 2.2% variegate porphyria. 70.2% had systemic arterial hypertension. Seizures, mental changes, arterial hypertension, and hyponatremia occurred more frequently than expected for porphyric attacks (p < .001). Seizures and hyponatremia were also more frequent than expected for PRES. The most common distributions of brain lesions were occipital (81.4%), parietal (65.1%), frontal (60.5%), subcortical (40%), and cortical (32.5%). Cerebral vasoconstriction was demonstrated in 41.7% of the patients who underwent angiography. 19.6% of the patients had ischemic lesions, and 4.3% developed long-term sequelae (cognitive decline and focal neurological deficits).

CONCLUSIONS

Brain edema, vasoconstriction, and ischemia in the context of PRES likely account for central nervous symptoms in some porphyric attacks.

Lifestyle factors including diet and biochemical biomarkers in acute intermittent porphyria: Results from a case-control study in northern Norway

BACKGROUND

Lifestyle factors, including a low intake of carbohydrates, dieting, alcohol consumption, cigarette smoking and stress are some of the possible triggers of attacks in acute intermittent porphyria (AIP). The influence of lifestyle factors, including energy intake, diet and alcohol consumption on the biochemical disease activity in AIP and biochemical nutritional markers were examined.

METHODS

A case-control study with 50 AIP cases and 50 controls matched for age, sex and place of residence was performed. Dietary intake was registered using a food diary in 46 matched pairs. Symptoms, alcohol intake, stress and other triggering factors of the last AIP attack were recorded on questionnaires. Porphyrin precursors, liver and kidney function markers, vitamins, diabetogenic hormones and other nutritional biomarkers were analyzed by routine methods. The Wilcoxon matched-pairs signed rank test was used to compare the cases vs. controls. The Spearman's rank correlation coefficient was used on the cases.

RESULTS

Increasing total energy intake was negatively correlated with the biochemical disease activity. The intake of carbohydrates was lower than recommended, i.e., 40 and 39% of total energy intake in the AIP cases and controls, respectively. The plasma resistin level was significantly higher (p = .03) in the symptomatic than asymptomatic cases. Plasma insulin was lower in those with high porphobilinogen levels. The intake of sugar and candies were higher in the AIP cases with low U-delta aminolevulinic acid (ALA) levels (p = .04). Attacks were triggered by psychological stress (62%), physical strain (38%), food items (24%) and alcohol (32%) in the 34 symptomatic cases. Alcohol was used regularly by 88% of the cases (3.2 g ethanol/day) and 90% of the controls (6.3 g/day), but the intake was significantly lower in symptomatic than in asymptomatic cases (p = .045).

CONCLUSION

A high intake of energy, sugar and candies and a higher insulin level were associated with a lower biochemical disease activity. The resistin level was higher in the symptomatic than the asymptomatic cases. AIP patients drink alcohol regularly, but the intake was significantly lower in the symptomatic cases.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01617642.

Feasibility of cellular bioenergetics as a biomarker in porphyria patients

Porphyria is a group of metabolic disorders due to altered enzyme activities within the heme biosynthetic pathway. It is a systemic disease with multiple potential contributions to mitochondrial dysfunction and oxidative stress. Recently, it has become possible to measure mitochondrial function from cells isolated from peripheral blood (cellular bioenergetics) using the XF96 analyzer (Seahorse Bioscience). Mitochondrial respiration in these cells is measured with the addition of activators and inhibitors of respiration. The output is measured as the O₂ consumption rate (OCR) at basal conditions, ATP linked, proton leak, maximal, reserve capacity, non-mitochondrial, and oxidative burst. We performed cellular bioenergetics on 22 porphyria (12 porphyria cutanea tarda (PCT), seven acute hepatic porphyria (AHP), and three erythropoietic protoporphyria (EPP)) patients and 18 age and gender matched healthy controls. Of porphyria cases, eight were active (2 PCT, 1 EPP, and 5 AHP) and 14 in biochemical remission. The OCR were decreased in patients compared to healthy controls. The bioenergetic profile was significantly lower when measuring proton leak and the non-mitochondrial associated OCR in the eight active porphyria patients when compared to 18 healthy controls. In conclusion, we demonstrate that the bioenergetic profile and mitochondrial activities assessed in porphyria patients and is different than in healthy control individuals. Further, our novel preliminary findings suggest the existence of a mitochondrial dysfunction in porphyria and this may be used as potential non-invasive biomarker for disease activity. This needs to be assessed with a systematic examination in a larger patient cohort. Studies are also suggested to examine mitochondrial metabolism as basis to understand mechanisms of these findings and deriving mitochondrial based therapies for porphyria.

Acute Intermittent Porphyria: A Rare Cause of Acute Disseminated Encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease of the central nervous system (CNS) with no distinct etiology but implications include infections and commonly administered vaccinations. In this case report, we present the case of ADEM in a young female who was subsequently diagnosed with acute intermittent porphyria (AIP) that was the instigator of the initial CNS assault. Our case highlights the peculiar presentation of ADEM which can present as a diagnostic challenge and brings forth AIP as a new and previously unknown affiliate of this rare CNS disease. We also discuss the pathophysiology, diagnostic criteria, and subsequent treatment options for this rare clinical entity.