BATTERIES NOT INCLUDED

1. BATTERIES NOT INCLUDED A pain physician’s tour of mitochondrial diseases

2. Outline • Why Mitochondria? • Who are the Mitochondria? • Biochemistry • Genetics • Clinical syndromes • Management Strategies • Conclusion • Mitochondria in Pain?

5. Why Mitochondria? • Mitochondria involved in basic pain mechanisms • Nociception • Centralisation • Analgesic tolerance • Mitochondrial dysfunction underlies some clinically unexplained syndromes • Fibromyalgia, Chronic Fatigue Syndrome • Mitochondrial dysfunction in common disorders • Nerve and Muscle disease eg Diabetic Neuropathy • Depression • Neurodegenerative Disorders

6. Who are the Mitochondria ? • Mitochondria are the power supply for all cells • Mitochondrial disease can impact on many systems • Brain, Nerve and Muscle most energy dependent • Mitochondrial and Nuclear genetic control

7. The humble mitochondrion • Originally a symbiotic bacteria • Each mitochondria has multiple copies of its own DNA • Co dependence on nuclear derived genes and proteins • Key function is oxidative phosphorlyation: • Utilise O2 to produce ATP from ADP • Respiratory Chain: 5 complexes working sequentially

10. Mitochondrial Biochemistry • Complexes I to IV essentially strip electrons from hydrogen atoms (NADH/H2O), pumping protons into the INTERMEMBRANE SPACE • This creates a large pH gradient, passage of protons through complex V is coupled to generation of ATP • Process relies on ELECTRON TRANSFER CHAIN including various co-enzymes (Co Q10) • Generates reactive oxygen species which are mopped up by other pathways (ubiquinone, lysosomes)

14. Mitochondrial Genetics • 16,569 base pairs, closed loop of DNA • Multiple copies in the matrix • DNA encodes for 13 of 90 respiratory chain proteins • the rest are coded from nuclear DNA • Almost no noncoding areas, no introns – unstable • Mitochondrial DNA maternally inherited • Nuclear mutations follow Mendelian inheritance • Mutations accumulate over time, heteroplasmic • Tissue mosaicism

15. Mitochondrial DNA

16. Mitochondrial DNA • Almost no introns, no histones: unstable • No DNA repair enzymes • Mitochondria dependent upon DNA replication to continue functioning • Exposed to free radicals

17. Mitochondrial genetic disorders • Wide range of symptoms and syndromes • Fatal encephalopathy or acidosis in first weeks of life • Indolent muscle disorder such as ophthalmoplegia • BRAIN: seizures, myoclonus, infarcts, ataxia, dystonia • NERVE: deafness, blindness, peripheral neuropathy • MUSCLE: eye muscles, proximal muscles, weakness, exercise intolerance, cardiomyopathy • OTHER: Diabetes, Deafness, short stature, lactic acidosis, liver, pancreas, lipodystrophy

19. Mitochondrial genetic syndromesMitochondrial Mutations • Leber’s Hereditary Optic Neuropathy. Sequential, severe and irreversible visual loss in young males. LHON gene causes blindness in 50% m, 10% f pts • CPEO: slowly progressive opthalmoplegia. Onset>50 usually a mtDNA deletion, sometimes point mutation • CPEO plus: multiple DNA deletions can result in neuropathy, Parkinsonism, ataxia, retinopathy, cataract, deafness, hypogonadism, depression • Kearns Sayre Syndrome (KSS): single large mt DNA deletion. Retinopathy, CPEO, cardiac conduction block. Limb myopathy, ataxia. Onset < 20. Limited lifespan.

21. Mitochondrial SyndromesMitochondrial Mutations • MELAS: Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke like events. Metabolic infarcts cross normal vascular territories. Headache, nausea, vomiting, seizures, hemiparesis, hemianopia or cortical blindness. Defect in mt transfer RNA 3243 A>G • MERRF: Myoclonic Epilepsy with ragged red fibres. Stimulus sensitive Myoclonus, seizures, ataxia, myopathy, cardiomyopathy. Onset in childhood. mtDNA mutation

22. MELAS infarction

23. Ragged Red Fibre

24. Mitochondrial SyndromesNuclear Mutations • MNGIE: mitochondrial neurogastrointestinal encephalomyopathy. CPEO, myopathy, neuropathy, intestinal pseudo obstruction. Laparotomies, malnutrition. May have a leucoencephalopathy. Nuclear DNA mut. thymidine phosphorylase • Leigh Syndrome: childhood onset symmetrical necrosis of brainstem and basal ganglia. Nystagmus, ataxia, dystonia, respiratory disease, pneumonia. Severe, progressive, fatal. Final common pathway of severe defects, many nuc DNA, some mtDNA

26. Mitochondrial Dysfunction • Genetic syndromes are striking but rare • Increasing recognition of involvement of mitochondria in more common diseases, especially nerve and muscle disease

27. Mitochondrial Dysfunction • Neuropathy • HAART neuropathy • Chemotherapy neuropathy: paclitaxel, Cis-Plat, Vinca • Diabetic distal symmetric polyneuropathy • Myopathy • Statinmyopathy • Fibromyalgia • CNS disorders • Parkinson’s, Huntington’s, Friedreich’s, Migraine, Depression • Cardiovascular Disorders • Role in Endothelial function. CoQ10 levels predict mortality

28. HAART toxicity • Reverse transcriptase inhibitors are nucleoside analogues. • Inhibit mitochondrial as well as viral DNA synthesis • Also inhibit adenylate kinase, ADP/ATP translocator • R-T side effects include myopathy, neuropathy, lactic acidosis, fatty liver, pancreatitis, nephrotoxicity. Fatalities reported with Ribavirin (Hep C) plus didanosine • HIV lipodystrophy closely resembles a mitochonrial disorder

29. HAART Neuropathy • Occurs in up to two thirds of patients on RTIs • zalcatibine>didanosine>stavudine>lamivudine>zidovudine>abacavir • Neuropathic pain, ascending numbness • Poorly responsive to conventional agents • Forces a change in therapy, compromising efficacy • Inhibition of mitochondrial DNA synthesis results in energy deficiency in peripheral nerve tissues • Reduced epidermal nerve fibre density, sweat gland innervation.

30. Chemotherapy Neuropathy • Paclitaxel, Doclitaxel, Platinum, Vinca Alkaloids • Inhibit mitochondrial DNA and RNA synthesis • Neuropathy frequent, limits dose and effectiveness • Potential for treatment with metabolic support

31. Diabetic Neuropathy • Mitochondrial dysfunction a key player in Type 2 DM • Glucose binds to Hexokinase, located on outer mitochondrial membrane • Glucose phosphorylation voltage dependent • Glucose -6-P, ADP production stimulate oxidative phos • G6P regulates mitochondrial function at several points • NADH donation to complex I • FADH to complex II • ADP to Complex V • In muscle, ATP turnover stimulates glycolysis, G6P • Excess glucose levels PLUS reduced O2 tension lead to an increase in free radical production0.

32. Acetyl L Carnitine • Maintains supply of acetyl-Co A • Contributes to phospholipid synthesis • Activates growth factor receptors • Promotes regeneration, neuroprotective • Analgesic properties • Acute pain (cholinergic) • Chronic pain (glutaminergic) • Increases ACTH and beta endorphin levels

33. Acetyl L Carnitine • Improves pain scores, NCS in diabetic neuropathy: • 333 pts, ACL 2g/d. Pain reduced by 40%, NCV better • 1364 pts Vibration sense up, Pain down, histological + • Neuroprotective in Laboratory models of antiretroviral and chemotherapy induced neuropathy • Clinically effective in HAART neuropathy • 21 HIV patients on RTIs: ALC 1.5 grams bd • improved neuropathic pain in 76% of pts • skin and sweat gland nerve fibre density inc by 100%

34. ALC for Diabetic Neuropathy

35. Muscle Disease • Statin Myopathy • Statins inhibit CoQ10 synthesis • Mitochondrial dysfunction. Ragged red fibres. Myalgia • Co Q10 supplements reduce pain AND improve function by 40% (no improvement with Vit E) • Am J Cardiol 2007;99(10):1409 • Fibromyalgia • Several lines of evidence indicating CoQ10 deficiency in fibromyalgia, chronic fatigue/ME

38. More Disorders • Depression • CoQ10 levels lower in depressed pts p<0.0002 • Lower again in patients with CFS or treatment resistant depression • Link to cardiovascular mortality • Cardiovascular Disease • Efficacy of statins predicted by CoQ10 levels • CoQ10 levels an independent predictor of survival • CoQ10 improves CHF: increased LVEF, Cardiac OP

39. Coenzyme Q10

40. Coenzyme Q10 • Q is for Quinone, 10 is the number of isoprene units • Complex synthesis, Quinone group from tyrosine, isoprene side chains from acetyl CoA (Cholesterol) • Statins reduce CoQ10 levels by 40% • Oil soluble, poor oral absorption • Found in heart, liver, nuts, soy or grapeseed oil. • Average intake 3-6mg/d, supplement at 150-300mg/d • Can lower BP by 17mmHg. Reduces insulin resistance • Studies in aging, dementia, PAIN….

42. Mitochondrial Mechanisms in Pain • Capsaicin induced hyperalgesia • Reactive Oxygen species (ROS) from mitochondria • Superoxide Dismutase SOD2 • Mechanical Hyperalgesia • ROS scavengers powerful antinociceptives • Mitochondrial Complex I or complex III inhibitors induce long lasting hyperalgesia • Morphine Antinociceptive tolerance • Inactivation of mitoSOD leads to excess peroxynitrite • Nitrative and Oxidative stress results in sensitisation • Effect reversed by peroxynitrite scavengers

43. Mitochondria and hyperalgesia

44. Making the Diagnosis • Well developed syndromes present no difficulty • Pointers to possible mitochondrial disorder: • Myopathy, Neuropathy, Deafness, Diabetes, • Cardiomyopathy or conduction defect. • Stroke, migraine, seizure, dementia • Serum Lactate, lactate/ pyruvate ratio. CK rise. Changes on ncs/EMG. CNS imaging. • Muscle Biopsy • Gomoritrichrome stain demonstrates accumulation of abnormal mitochondria – Ragged Red Fibre

45. Ragged Red Fibre

46. Diagnosis • Muscle Biopsy: other techniques • Cytochrome C (COX) and Succinate DH staining • Specific enzymatic analysis. Tricky: sample handling, differing lab evaluations. Age related changes. Looking for reduced biochemical activity of various complexes. • Genetic Analysis • Specific tests for specific syndromes: MELAS, MERRF, LHON, adult Leigh syndrome. • Deletion analysis for CPEO, KSS, myopathies

47. ManagementSupportive • Diabetes – due to energy failure not insulin resistance. OHAs, minimal insulin. NO metformin!! • Seizures – AVOID valproate as it inhibits function. Levetiracetam, Lamotrigene, Clonazepam • Respiratory and Bulbar weakness. Noninvasive ventilation, PEG tubes etc. • Cardiac – KSS and others may require Pacemaker. Be alert for WPW and SVT.

48. ManagementPharmacology • Coenzyme Q10 • Acetyl Carnitine • Limited efficacy: Riboflavin, alpha lipoic acid, Vitamin A,D,E,K • Trials: benzafibrate, reservatrol, PCC1 alpha. L-arginine for MELAS • Metabolic agents: bicarbonate, dichloroacetate • MNGIE- stem cell transplantation

49. ManagementResistance Training • Mitochondrial genetic material is heteroplasmic, and dynamic. Mitochondria have a social life! • Proportions of mutant and wild type DNA are not stable. • Resistance training can apply selection pressure in favour of more functional DNA. • Population of “satellite cells” in muscle with high proportions of wild type DNA. • Exercise physiologist supervised protocols available.

50. Resistance Training