Porphyrins II

1. Porphyrins II David Hart Dec 13, 2006

2. HEME CH3-

3. Bonkovsky ASH Education Book December 2005

4. Hentze, Muckenthaler & Andrews Cell, Vol 117, 285-297, April 30, 2004 Hepcidin

5. Lecture Outline • Heme function • Heme synthesis and regulation • Iron metabolism • Porphyrias • Heme degradation

6. Disorders of Heme Synthesis • X-linked Sideroblastic Anemia • Lead Poisoning • Iron Deficiency Anemia • The Porphyrias

7. Porphyrias • Inherited defects in heme synthesis • Accumulation and excretion of porphyrins • Pattern depends on which enzyme affected • Decreased heme synthesis derepresses hepatic ALAS • Most are Autosomal Dominant • Erythropoietic, Hepatic or Mixed • Acute and Chronic • Acute: Neurovisceral attacks • Porphyrin accumulation: Photosensitivity • Formation of reactive oxygen species • Damage tissues, Release lysosomal enzymes

8. Fuseli Three Witches Tate Gillray 1791 Weird Sisters Tate

9. X-linked Sideroblastic Anemia Lead Poisoning ALA-D Porphyria Very Rare Recessive Porphyria

10. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase PBG and ALA (Neurotoxic) Accumulate in Urine PBG in Urine: Diagnostic Screen Neurovisceral Attacks No Photosensitivity with AIP

11. Acute PorphyriasClinically indistinguishable (Locus Heterogeneity)PBG in Urine: Diagnostic Screen • Agents which induce cytochrome P450 • Drugs, Alcohol, Hormones • Precipitated by fasting, treated with glucose • After puberty; more in women • Begin with minor behavioral changes • Proceeds to autonomic and sensomotoric neuropathy; Convulsions • Pain: Back, Extremities, Abdomen • Hypertension and Tachycardia • Arrhythmias; cardiac arrest

12. X-linked Sideroblastic Anemia Lead Poisoning ALA-D Porphyria Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic RECESSIVE Porphyrin accumulation: Photosensitivity Porphyrins are Fluorescent compounds Formation of reactive oxygen species, Activate Complement

13. Dr. Meyer-Betz 1912 Clin Med 2005:5

14. CEP GM Murphy, Dermatologic Therapy, March2003

15. CEP NEJM 9/7/2006

17. mccaskey4.home.mindspring.com

18. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic

19. Porphyria Cutanea Tarda (PCT) • Most common Porphyria • 80% sporadic • Hepatic and Erythropoietic • Photosensitivity • Uroporphyrin accumulates in Urine • Red-Brown in natural light • Clinical expression in 4th - 5th decade • Decrease in UROD activity by Iron-dependent mechanism • Alcohol, viruses, drugs, hormones • HFE Hemochromatosis • Venesection, Chloroquine

20. Autosomal Dominant PCT (Hepatoerythropoietic Porphyria) • Hepatic UROD activity < 50% during symptoms • Additional decrease from reversible inactivation • C282Y HFE causes earlier onset

21. PCT; www.Utah.edu

22. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic Acute Hepatic Photosensitivity (Unlike AIP)

23. Normal Liver medlib.med.utah.edu

24. Granular, Dark Reddish Brown Surface of Liver in Hemochromatosis www.med.niigata-u.ac.j

25. Hepatic Porphyria Lecha, Herrero, Ozalla, Dermatologic Therapy, March2003

26. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic Acute Hepatic Acute Hepatic Photosensitivity

27. Hair Analysis Lancet July 2005

28. Lancet July 23-29, 2005 • King George III (1738-1820) • Likely diagnosis of Variegate Porphyria • Proposed 1969 based on family tree • Lock of hair showed high lead • Widespread use in his era • Extremely high levels of arsenic • Likely secondary to medications

29. Lancet July 2005 Color of Urine “Alicante Wine”

30. Introduction of Fe2+ into PPIX Occurs spontaneously, but Enhanced by FERROCHELATASE An enzyme which is inhibited by LEAD http://www.aw-bc.com/mathews/GH/HEME.GIF

31. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic Acute Hepatic Acute Hepatic Erythropoietic http://www.photodermatologie.de Photosensitivity

32. Erythropoietic Protoporphyria • Presentation in early childhood • Burning, stinging pain with sunlight • Subsequent skin changes • Expression requires low-expression allele in trans • 10% of population of France and UK • IVS3-48 alternative splice acceptor • With AD mutation FECH 35% of normal • Homozygosity does not cause disease • Beta carotene: free radical scavenger

33. www.immunochemistry.com

34. EPP GM Murphy, Dermatologic Therapy, March 2003

35. EPP GM Murphy, Dermatologic Therapy, March2003

36. www.goa-world.ne

37. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic Acute Hepatic Acute Hepatic No Photosensitivity With Lead Erythropoietic Lead Poisoning Photosensitivity

38. X-linked Sideroblastic Anemia ALA-D Porphyria Lead Poisoning Acute Hepatic Hydroxymethylbilane Synthase Erythropoietic Chronic Acute Hepatic “Free” Erythrocyte PPIX accumulates in Lead Poisoning and Iron Deficiency Acute Hepatic Erythropoietic Iron Deficiency http://www.photodermatologie.de Photosensitivity

39. Porphyrias: Genetics / Epigenetics • 5 out of 7 are Low-penetrance Autosomal Dominant • Most mutations are restricted to one family • Rare Homozygotes very severe • No dominant negative mutants described • 50% residual activity is normally sufficient

40. Molecular basis of “low penetrance” • Genotype/phenotype correlations • Increased demand • Fasting (low Glucose) • Cell, August 26, 2005 • Low expression allele in trans • Iron / HFE hemochromatosis can directly inhibit enzymes • Other epigenetic phenomena

41. Treatment • Medical Support during acute attacks • Treatment for pain and vomiting • Glucose infusion until Hemin available • Intravenous Hemin • Decreases synthesis of ALAS • Avoid Sunlight • -carotene, a free-radical scavenger • Chronic transfusion for Erythropoietic

42. Degradation of Heme • At end of their 120 day lifespan, red blood cells are taken up and degraded by the reticuloendothelial (RE) system (liver and spleen) • 85% heme for degradation from RBC • 15% immature RBC, cytochromes from extraerythroid tissues

43. CH=CH2 CH3 HEME -CH=CH2 H3C- N HN Fe2+ NH N -CH3 H3C- CH2 CH2 COOH CH2 CH2 COOH

44. Heme Oxygenase is Inducible by a variety of agents MACROPHAGE takes up HEME CH=CH2 CH3 -CH=CH2 H3C- N HN Inhibited by Tin Protoporphyrin Fe2+ NH N -CH3 H3C- CH2 CH2 COOH CH2 CH2 COOH

45. MACROPHAGE Heme Oxygenase Step 1 NADPH O2 CH=CH2 CH3 OH -CH=CH2 H3C- N HN Fe3+ NH N -CH3 H3C- CH2 CH2 COOH CH2 CH2 COOH

46. MACROPHAGE Heme Oxygenase Step 2 Fe3+ CO Released CH=CH2 CH3 O O -CH=CH2 H3C- N HN BILIVERDIN NH N -CH3 H3C- HO also has Cytoprotective effects CH2 CH2 COOH CH2 CH2 COOH

47. J Cell Mol Med 2006

48. M M P P M M V V N H N N H N H CH CH CH O O BILIVERDIN

49. M M P P M M V V N H N N H N H CH CH CH O O BILIVERDIN BILIVERDIN REDUCTASE + NADPH M M P P M M V V N H N H N H N H CH CH2 CH O O BILIRUBIN