Consecutive Liver and Bone Marrow Transplantation for Erythropoietic Protoporphyria: Case Report and Literature Review

BACKGROUND

Erythropoietic protoporphyria (EPP) is a rare inherited disease of heme biosynthesis resulting in the accumulation of protoporphyrin, characterized by liver failure in a minority of cases. Although liver transplant (LT) is the therapeutic strategy for advanced hepatic disease, it does not correct the primary defect, which leads to recurrence in liver graft. Thus, hematopoietic stem cell transplantation (HSCT) is an approach for treating EPP.

METHODS

We aim to describe the first sequential LT and HSCT for EPP performed in Latin America, besides reviewing the present-day literature.

RESULTS

The patient, a 13-year-old female with a history of photosensitivity, presented with symptoms of cholestatic and hepatopulmonary syndrome and was diagnosed with EPP. Liver biopsy demonstrated cirrhosis. She was submitted to a successful LT and showed improvement of respiratory symptoms. However, she had disease recurrence on the liver graft. She underwent a myeloablative HSCT using a matched unrelated donor, conditioning with BuCy (busulfan and cyclophosphamide), and GvHD (graft vs. host disease) prophylaxis with ATG (thymoglobulin), tacrolimus and methotrexate. Neutrophil engraftment occurred on D+18. She has presented mixed chimerism, but normalization of PP levels, being 300 days after HSCT, in good state of health and normal liver function.

CONCLUSIONS

Consecutive LT and HSCT for EPP is a procedure that has been described in 10 cases in the literature and, even though these patients are a highly diversified population, studies have shown favorable results. This concept of treatment should be considered in patients with established liver disease.

Protoporphyrin IX-induced phototoxicity: Mechanisms and therapeutics

Protoporphyrin IX (PPIX) is an intermediate in the heme biosynthesis pathway. Abnormal accumulation of PPIX due to certain pathological conditions such as erythropoietic protoporphyria and X-linked protoporphyria causes painful phototoxic reactions of the skin, which can significantly impact daily life. Endothelial cells in the skin have been proposed as the primary target for PPIX-induced phototoxicity through light-triggered generation of reactive oxygen species. Current approaches for the management of PPIX-induced phototoxicity include opaque clothing, sunscreens, phototherapy, blood therapy, antioxidants, bone marrow transplantation, and drugs that increase skin pigmentation. In this review, we discuss the present understanding of PPIX-induced phototoxicity including PPIX production and disposition, conditions that lead to PPIX accumulation, symptoms and individual differences, mechanisms, and therapeutics.

Updates on the diagnosis and management of the most common hereditary porphyrias: AIP and EPP

The porphyrias are a family of metabolic disorders caused by defects in the activity of one of the enzymes in the heme biosynthetic pathway. Acute intermittent porphyria (AIP), caused by autosomal dominant mutations in the gene encoding hydroxymethylbilane synthase, can lead to hepatocyte overaccumulation and systemic distribution of the proximal porphyrin precursors, 5-aminolevulinic acid (ALA) and porphobilinogen (PBG). ALA and PBG are toxic to neurons and extrahepatic tissue and cause the neurovisceral clinical manifestations of AIP. Management of AIP includes awareness and avoidance of triggering factors, infusions of hemin for severe acute attacks, and, if indicated for chronic suppressive therapy, maintenance treatment with hemin or givosiran, a small interfering RNA molecule that antagonizes ALA synthase 1 transcripts. Erythropoietic protoporphyria (EPP) is most commonly caused by autosomal recessive mutations in the gene encoding ferrochelatase (FECH), the heme pathway terminal enzyme. FECH deficiency leads to erythrocyte overaccumulation and high plasma levels of lipophilic protoporphyrins that photoactivate in the skin, causing burning pain and erythema. Protoporphyrins excreted in the bile can cause gallstones, cholestasis, fibrosis, and ultimately liver failure. Management of EPP includes skin protection and afamelanotide, an α-melanocyte stimulating hormone analog that increases melanin pigment and reduces photoactivation. Liver transplantation may be necessary for severe EPP-induced liver complications. Because AIP and EPP arise from defects in the heme biosynthetic pathway, hematologists are often consulted to evaluate and manage suspected or proven porphyrias. A working knowledge of these disorders increases our confidence and effectiveness as consultants and medical providers.

The essential role of the transporter ABCG2 in the pathophysiology of erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is an inherited disease caused by loss-of-function mutations of ferrochelatase, an enzyme in the heme biosynthesis pathway that converts protoporphyrin IX (PPIX) into heme. PPIX accumulation in patients with EPP leads to phototoxicity and hepatotoxicity, and there is no cure. Here, we demonstrated that the PPIX efflux transporter ABCG2 (also called BCRP) determines EPP-associated phototoxicity and hepatotoxicity. We found that ABCG2 deficiency decreases PPIX distribution to the skin and therefore prevents EPP-associated phototoxicity. We also found that ABCG2 deficiency protects against EPP-associated hepatotoxicity by modulating PPIX distribution, metabolism, and excretion. In summary, our work has uncovered an essential role of ABCG2 in the pathophysiology of EPP, which suggests the potential for novel strategies in the development of therapy for EPP.

Diagnosis of erythropoietic protoporphyria with severe liver injury: A case report

BACKGROUND

Porphyria is a rare disease with complex classification. Erythropoietic protoporphyria (EPP) is an autosomal recessively inherited disease, and most are caused by mutations in the FECH gene. EPP combined with liver injury is even rarer.

CASE SUMMARY

This paper reports a case of EPP which was admitted to the hospital with abnormal liver function and diagnosed by repeated questioning of medical history, screening of common causes of severe liver injury, and second generation sequencing of the whole exon genome. We also summarize the clinical characteristics of EPP with liver injury, and put forward some suggestions on EPP to provide a reference for the diagnosis of such rare disease.

CONCLUSION

A new mutation locus (c.32_35dupCCCT) which may be related to the disease was found by detecting the FECH gene in the pedigree of this case.

Digital PCR (dPCR) analysis reveals that the homozygous c.315-48T>C variant in the FECH gene might cause erythropoietic protoporphyria (EPP)

Alterations in the ferrochelatase gene (FECH) are the basis of the phenotypic expressions in erythropoietic protoporphyria. The phenotype is due to the presence of a mutation in the FECH gene associated in trans to the c.315-48 T > C variant in the intron 3. The latter is able to increase the physiological quota of alternative splicing events in the intron 3. Other two variants in the FECH gene (c.1-252A > G and c.68-23C > T) have been found to be associated to the intron 3 variant in some populations and together, they constitute a haplotype (ACT/GTC), but eventually, their role in the alternative splicing event has never been elucidated. The absolute number of the aberrantly spliced FECH mRNA molecules and the absolute expression of the FECH gene were evaluated by digital PCR technique in a comprehensive cohort. The number of splicing events that rose in the presence of the c.315-48 T > C variant, both in the heterozygous and homozygous condition was reported for the first time. Also, the percentage of the inserted FECH mRNA increased, even doubled in the T/C cases, compared to T/T cases. The constant presence of variants in the promoter and intron 2 did not influence or modulate the aberrant splicing. The results of FECH gene expression suggested that the homozygosity for the c.315-48 T > C variant could be considered pathological. Thus, this study identified the homozygotes for the c.315-48 T > C variant as pathological. By extension, when the samples were categorised according to the haplotypes, the GTC haplotype in homozygosis was pathological.

[A patient diagnosed herself with erythropoietic protoporphyria after googling photosensitivity]

Erythropoietic protoporphyria (EPP) is rare genetic disease caused by decreased activity of the eighth enzyme in the haem synthesis. Patients are photosensitive, getting stinging and burning sensations in the skin after sun exposure. Delayed diagnosis of these patients is not seldom because of the rarity in combination with not always visible skin symptoms. This is a case report of a 43-year-old woman who diagnosed herself with EPP after googling photosensitivity. Genetic testing revealed a formerly undescribed mutation, c. 1096-3C>G in combination with the polymorphism, c.333-48T>C.

Curative bone marrow transplantation in erythropoietic protoporphyria after reversal of severe cholestasis

We report the case of a middle-age patient presenting with severe progressive protoporphyric cholestasis. To halt further progression of liver disease, medical treatment was given aimed at different mechanisms possibly causing cholestasis in erythropoietic protoporphyria. Within eighty days, liver biochemistry completely normalized and liver histology markedly improved. Bone marrow transplantation was performed to prevent relapse of cholestatic liver disease by correcting the main site of protoporphyrin overproduction. Thirty-three months after cholestatic presentation and ten months after bone marrow transplantation, liver and porphyrin biochemistry remains normal. The patient is in excellent condition and photosensitivity is absent. The theoretical role of each treatment used to successfully reverse cholestasis and the role of bone marrow transplantation in erythropoietic protoporphyria are discussed. Medical treatment can resolve hepatic abnormalities in protoporphyric cholestasis. Bone marrow transplantation achieves phenotypic reversal and may offer protection from future protoporphyric liver disease.

Transient erythropoietic protoporphyria associated with chronic hepatitis and cirrhosis in a cohort of German shepherd dogs

Over the course of one year, slight jaundice and ascites suggestive of chronic liver disease occurred in 17 German shepherd dogs from one breeding colony. Blood analyses, performed twice with a six-month interval, revealed elevated serum activities of liver enzymes in 13 dogs. In addition, four young adult German shepherd dogs that showed severe ascites, slight jaundice and increased serum liver enzyme activities were referred for further evaluation. Because of their poor prognosis these four dogs were euthanased. There were no signs of photosensitivity. Postmortem examinations revealed macronodular darkened livers, which were characterised histopathologically by cirrhosis associated with aggregates of brown pigments showing a striking orange birefringence in polarised light. Ultrastructurally, the crystalline pigments were typical of protoporphyrins. High-performance liquid chromatographic analysis of liver samples revealed very high levels of protoporphyrins (mean 9550 nmol/g wet liver, reference value 0.41 nmol/g wet liver) and low activities of ferrochelatase (mean 0.274 mmol/mg protein/hour, reference value 0.684 nmol/mg protein/hour). Twenty-six months after the onset of the hepatopathies, the clinical condition of the 13 surviving dogs had improved and their serum liver enzyme activities were normal. The clinical histories and pedigree analyses were not in concordance with an inherited form of protoporphyria. There was no known history of exposure to toxic substances or drugs. The findings are in accordance with a transient erythropoietic protoporphyria associated with hepatic complications, presumably caused by exposure to a porphyrinogenic, ferrochelatase-inhibitory substance of unknown origin.

Distribution of protoporphyrin in female broiler chickens affected with protoporphyria

One hundred thirty-seven broiler chickens at a poultry meat processing plant had dark green to black livers. Thirty-one chickens of these were collected at random and examined pathologically and biochemically. All of thirty-one chickens were female. The chickens showed mild retarded growth and a remarkable atrophy of the gallbladders. Microscopically, the livers showed dark brown pigments in the Kupffer cells, hepatocytes, and portal triads. These pigments showed birefringence with a Maltese-cross pattern under polarized light. Hyperplasia of the cholangioles, fibrosis, and infiltration of inflammatory cells were present in the portal triads. All the examined samples showed the same dark brown pigments in alveolar walls of the lungs. A high concentration of protoporphyrin was detected in affected livers, marrow, and feces (489, 104, and 116 microg/g wet wt., respectively) by biochemical assay.

Liver transplantation for erythropoietic protoporphyria liver disease

In erythropoietic protoporphyria (EPP), there is excessive production of protoporphyrin, primarily in the bone marrow, resulting in increased biliary excretion of this heme precursor. Some patients will develop progressive liver disease that may ultimately require liver transplantation. However, excessive production of protoporphyrin by the bone marrow continues after transplantation, which may cause recurrent disease in the allograft. This study was performed to define post-transplant survival, the risk of recurrent disease, and specific management issues in patients transplanted for EPP liver disease. The patients studied consisted of twelve males and eight females, with an average age of 31 (range, 13-56) years at the time of transplantation. The estimated maximum MELD score prior to transplant was 21 (range, 15-29). Unique complications in the perioperative period were light induced tissue damage in four patients and neuropathy in six, requiring prolonged mechanical ventilation in four. Patient and graft survival rates were 85% at 1 year, 69% at 5 years, and 47% at 10 years. Recurrent EPP liver disease occurred in 11 of 17 patients (65%) who survived more than 2 months. Three patients were retransplanted at 1.8, 12.6, and 14.5 years after the initial transplant for recurrent EPP liver disease. In conclusion, the 5-year patient survival rate in patients transplanted for EPP liver disease is good, but the recurrence of EPP liver disease appears to diminish long term graft and patient survival.

Increased mitochondrial respiratory chain enzyme activities correlate with minor extent of liver damage in mice suffering from erythropoietic protoporphyria

Mitochondrial dysfunction might play a role in the pathogenesis of liver damage in erythropoietic protoporphyria (EPP). Changes in mitochondrial respiratory chain activities were evaluated in the Fech(m1pas)/Fech(m1pas) mouse model for EPP. Mice from different strains congenic for the same ferrochelatase germline mutation manifest variable degrees of hepatobiliary injury. Protoporphyric animals bred into the C57BL/6J background showed a higher degree of hepatomegaly and liver damage as well as higher protoporphyrin (PP) accumulation than those bred into the SJL/J and BALB/cJ backgrounds. Whereas mitochondrial respiratory chain activities remained unchanged in the liver of protoporphyric mice C57BL/6J, they were increased in protoporphyric mice from both SJL/J and BALB/cJ backgrounds, when compared to wild-type animals. Mitochondrial respiratory chain activities were increased in Hep G2 cell line after accumulation of PP following addition of aminolevulinic acid. As a direct effect of these elevated mitochondrial activities, in both hepatic cells from mutant mouse strains and Hep G2 cells, adenosine 5'-triphosphate (ATP) levels significantly increased as the intracellular PP concentration was reduced. These results indicate that PP modifies intracellular ATP requirements as well as hepatic mitochondrial respiratory chain enzymatic activities and further suggest that an increase of these activities may provide a certain degree of protection against liver damage in protoporphyric mice.

Heme-regulated eIF2alpha kinase modifies the phenotypic severity of murine models of erythropoietic protoporphyria and beta-thalassemia

Heme-regulated eIF2alpha kinase (HRI) controls protein synthesis by phosphorylating the alpha-subunit of eukaryotic translational initiation factor 2 (eIF2alpha). In heme deficiency, HRI is essential for translational regulation of alpha- and beta-globins and for the survival of erythroid progenitors. HRI is also activated by a number of cytoplasmic stresses other than heme deficiency, including oxidative stress and heat shock. However, to date, HRI has not been implicated in the pathogenesis of any known human disease or mouse phenotype. Here we report the essential role of HRI in 2 mouse models of human rbc disorders, namely erythropoietic protoporphyria (EPP) and beta-thalassemia. In both cases, lack of HRI adversely modifies the phenotype: HRI deficiency exacerbates EPP and renders beta-thalassemia embryonically lethal. This study establishes the protective function of HRI in inherited rbc diseases in mice and suggests that HRI may be a significant modifier of many rbc disorders in humans. Our findings also demonstrate that translational regulation could play a critical role in the clinical manifestation of rbc diseases.

Hepatic gene expression in protoporphyic Fech mice is associated with cholestatic injury but not a marked depletion of the heme regulatory pool

BALB/c Fech(m1Pas) mice have a mutated ferrochelatase gene resulting in protoporphyria that models the hepatic injury occurring sporadically in human erythropoietic protoporphyria. We used this mouse model to study the development of the injury and to compare the dysfunction of heme synthesis with hepatic gene expression of liver metabolism, oxidative stress, and cellular injury/inflammation. From an early age expression of total cytochrome P450 and many of its isoforms was significantly lower than in wild-type mice. However, despite massive accumulation of protoporphyrin in the liver, expression of the main genes controlling heme synthesis and catabolism (Alas1 and Hmox1, respectively) were only modestly affected even in the presence of the cytochrome P450-inducing CAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene. In contrast, in BALB/c mice exhibiting griseofulvin-induced hepatic protoporphyria with induction and destruction of cytochrome P450, both Alas1 and Hmox1 genes were markedly up-regulated. Other expression profiles in BALB/c Fech(m1Pas) mice identified roles for oxidative mechanisms in liver injury while modulated gene expression of hepatocyte transport proteins and cholesterol and bile acid synthesis illustrated the development of cholestasis. Subsequent inflammation and cirrhosis were also shown by the up-regulation of cytokine, cell cycling, and procollagen genes. Thus, gene expression profiles studied in Fech(m1Pas) mice may provide candidates for human polymorphisms that explain the sporadic hepatic consequences of erythropoietic protoporphyria.