fredag den 22. marts 2019

Chitotriosidase in ME

The enzyme chitotriosidase is involved in immune response to chitin-containing pathogens.

Chitin is a polymer of N-acetylglucosamine. Chitin is the main component of the cell wall of fungi.

Chitotriosidase is encoded by the gene CHIT1 (1).

The CHIT1 gene promotor was hypomethylated in peripheral blood mononuclear cells (PBMC) from ME patients (2).

The CHIT1 gene (genic region: body) was differentially methylated in PBMC from ME patient subtypes (3).

Chitotriosidase is mainly expressed by blood and tissue macrophages. It is an important nonspecific marker of macrophage activation. Elevated chitotriosidase is related to several diseases, fx lysomal storage diseases, neurological diseases and respiratory diseases (1).

Glucosylceramidase beta (GBA) cleaves the beta-glucosidic linkage of glycosylceramide. Mutations in the gene GBA cause the lysomal storage disease Gaucher. Chitotriosidase activity is several hundred-fold elevated in plasma from Gaucher patients in which macrophages play an essential role in the clerance of the disease sphingolipid storage material (1).

GM2 ganglioside activator (GM2A) is a glycolipid transport protein. Mutations in the gene GM2A are involved in lysomal storage diseases.

The GM2A gene promotor was hypomethylated in PBMC from ME patients (2).

Is the dysregulated sphingolipid metabolism in ME patients involved in the hypomethylated CHIT1 and GM2A gene promotors?

References:
  1. Elmonem et al: Immunomodulatory effects of chitotriosidase enzyme. Hindawi 2016, ID2682680 https://www.ncbi.nlm.nih.gov/pubmed/26881065
  2. Trivedi et al: Identification of ME/CFS - associated DNA methylation patterns.
    Plos One 2018, 13, 7 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201066
  3. de Vega et al: Integration of DNA methylation & health scores identifies subtypes in ME/CFS. Epigenomics 2018, 10, 5 https://www.futuremedicine.com/doi/full/10.2217/epi-2017-015

fredag den 15. marts 2019

What does 1-pyrroline-5-carboxylate do to ME?

ME patients had increased plasma levels of 1-pyrroline-5-carboxylic acid (P5C) and arginine. Females had increased OH-proline (1).

P5C is found at a crossroad, which exchanges metabolites from:

  • proline degradation from collagen
  • proline synthesis
  • urea cycle
  • TCA cycle


Research in tumor growth has shown(quote from ref 2):

"The metabolism of the nonessential amino acid proline contributes to tumor metabolic reprogramming. Previously we showed that MYC increases proline biosynthesis (PB) from glutamine. Here we show MYC increases the expression of the enzymes in PB at both protein and mRNA levels. Blockade of PB decreases tumor cell growth and energy production. Addition of Δ1- pyrroline-5-carboxylate (P5C) or proline reverses the effects of P5C synthase knockdown but not P5C reductases knockdown. Importantly, the reversal effect of proline was blocked by concomitant proline dehydrogenase/oxidase (PRODH/POX) knockdown. These findings suggest that the important regulatory contribution of PB to tumor growth derives from metabolic cycling between proline and P5C rather than product proline or intermediate P5C. We further document the critical role of PB in maintaining pyridine nucleotide levels by connecting the proline cycle to glycolysis and to the oxidative arm of the pentose phosphate pathway. These findings establish a novel function of PB in tumorigenesis, linking the reprogramming of glucose, glutamine and pyridine nucleotides, and may provide a novel target for antitumor therapy."

From page 9: "The proline cycle transfers reducing and oxidizing potentials to maintain redox homeostasis between cytosol and mitochondria through interconversion of proline and P5C catalyzed by PRODH/POX and PYCRs, respectively. In mitochondria, PRODH/POX oxidizes proline to P5C and donates electrons through its flavine adenine dinucleotide into the electron transport chain (ETC) to generate ATP or reactive oxygen species (ROS) for apoptosis or cell growth depending on the metabolic context of tumor environment (10,19). P5C can be converted to proline intra-mitochondrially or in the cytosol by PYCRs using NADPH or NADH as cofactor. Therefore, the interconversion of P5C and proline results in the recycling of cellular NAD(P)H to NAD(P)+. During the 1970s and early 1980s, researchers in proline metabolism documented the metabolic interlock between proline cycle and the oxPPP through the cycling of NADPH and NADP+ in various cells and reconstituted cell systems (26–28). They showed that P5C is a potent stimulator of oxPPP in cultured fibroblasts (26). Together with these early studies, our current findings seen with PB knockdown, i.e. marked decrease in oxPPP activity and decreased levels of both total NAD and NADP, suggest the PYCR-catalyzed conversion of P5C to proline provides a metabolic linkage to oxidize NAD(P)H as well as to generate total NAD and NADP (Fig. 8)". (Ref 2 and references herein).


Figure 8

Figure 8. Proposed scheme of interactions of proline biosynthesis with glucose and glutamine metabolism. Proline biosynthesis from glutamine in cancer cells promotes cell growth through interacting with glycolysis and oxidative arm of pentose phosphate pathway. P5C, Δ1 -pyrroline-5-carboxylate; GSA, glutamic-gamma-semialdehyde; GLS, glutaminase; GS, glutaminesynthase; P5CS, pyrroline-5- carboxylatesynthase; P5CDH, pyrroline-5-carboxylatedehydrogenase; PRODH/POX, proline dehydrogenase/ oxidase; PYCR1/2, pyrroline-5-carboxylatereductase1, and 2; PYCRL, pyrroline-5-carboxylatereductase L. oxPPP, oxidative arm of pentose phosphate pathway. Ref: Liu, W. et al. Proline biosynthesis augments tumor cell growth and aerobic glycolysis: involvement of pyridine nucleotides. Sci. Rep. 5, 17206; doi: 10.1038/srep17206 (2015).

Is P5C used to control redox (NADP/NADPH) in ME?

Is P5C used to stimulate phosphoribosyl pyrophosphate and purine nucleotide production in ME (as shown in ref 3)?

Is P5C used as an intermediate to replenish the TCA cycle in ME?


References:

1) Naviaux RK, Naviaux JC, Li K, Bright AT, Alaynick WA, Wang L, Baxter A, Nathan N et al (2016) Metabolic features of chronic fatigue syndrome. Proc Natl Acad Sci U S A 113:E5472–E5480. https://doi.org/10.1073/pnas.1607571113 

2) Liu, W. et al. Proline biosynthesis augments tumor cell growth and aerobic glycolysis: involvement of pyridine nucleotides. Sci. Rep. 5, 17206; doi: 10.1038/srep17206 (2015).
https://www.nature.com/articles/srep17206.pdf

3) J Biol Chem. 1988 Sep 15;263(26):13083-9. Stimulation of phosphoribosyl pyrophosphate and purine nucleotide production by pyrroline 5-carboxylate in human erythrocytes.
Yeh GC1, Phang JM. https://www.ncbi.nlm.nih.gov/pubmed/2458343

torsdag den 14. marts 2019

Fatty acid oxidation, CPS1 and urea cycle in ME

When beta-oxidation of fatty acids is blocked, there is an increase in omega-oxidation, which produces dicarboxylic acids (adipic, suberic and sebacic acid). Elevated levels in plasma or urine of dicarboxylic acids are indicative of dysregulated fatty acid oxidation. Inadequate level of carnitine can lead to elevated levels of dicarboxylic acids. This is fx. observed in enteric dysfunction (1),

Some ME patients have changed plasma levels in different studies compared to normal controls of the following metabolites:
  • increased sebacic acid and pristanic acid (2)
  • increased adipoylcarnitine (3, 4), and increased methyladipoylcarnitine (3)
  • decreased carnitine (5)
3- methyladipic acid is formed upon omega-oxidation of phytanic acid. Pristanic acid is formed of phytanic acid (6).

In certain long-chain fatty acid oxidation defects, fatty acylation of an active site residue of carbamoylphosphate synthetase 1 (CPS1) directly affects the urea cycle detoxification capacity (7).

In valproic acid induced toxicity CPS1 may be inhibited of omega-oxidation metabolites (8).

Some ME patients have dysregulated urea cycle (9).

Yamano et al hypothesized that the increase in the ratio ornithine / citrulline in plasma from ME patients may reflect either CPS1 or ornithine transcarbamoylase (OCT) dysfunction (10).

In OTC deficiency carbamoyl phosphate cannot replenish the urea cycle. The carbamoyl phosphate instead goes into the uridine monophosphate (UMP)- synthetic pathway. This means that orotic acid levels in the blood will increase. I have not found increased levels of orotate in any of the ME metabolism studies.

N-acetylglutamic acid is an essential cofactor for activation of  CPS1. Some ME patients have increased N-acetylglutamic acid plasma level, thus the cofactor is present (3).

Is CPS1 activated or not in ME? Are omega-oxidation metabolites involved?


SIRT5 Deacetylates carbamoyl phosphate synthetase 1 and regulates the urea cycle

SIRT5 deacetylates CPS1 and upregulates its activity. During fasting, NAD in liver mitochondria increases, thereby triggering SIRT5 deacetylation of CPS1 and adaptation to the increase in amino acid catabolism (11). 


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Figure from Takashi Nakagawa and Leonard Guarente, AGING, June 2009, Vol. 1 No. 6 ref 12. 

Is a dysregulated NAD/NADH ratio involved in CPS1 dysfunction in ME?


Glycine and CPS1


Glycine and CPS1 are connected through the one-carbon pool by the folate pathway and the urea cycle.

Higher CPS1 expression is associated with less glycine in the blood, and vice versa.

Glycine is a major biochemical mechanism to eliminate ammonia. Glycine conjugating with benzoic acid leads to hippuric acid, which is abundantly found in urine samples.

Variations in CPS1 quantity and thus the glycine pool may also influence one-carbon metabolism and the bioavailability of betaine (13).

Is glycine used to eliminate ammonia in ME patients?


Another route of excretion of excess nitrogen


Phenylacetylglutamine and 4-hydroxyphenyl acetylglutamine provide another route of excretion of excess nitrogen from the body. Phenylacetate in the blood (some from the host and some from gut fermentation) conjugates with glutamine to phenylacetylglutamine, which is excreted in the urine (1).

4-hydroxyphenylacetate is derived from fermentation af tyrosine by the gut microbiome (1).

Children with enteric dysfunction had elevated serum levels of phenylacetate, 4-hydroxyphenylacetate and phenylacetylglutamine (1).

4-hydroxyphenylacetate and derivates were increased in plasma from ME patients (2).

Alpha-N-phenylacetyl-L-glutamine was increased in plasma from ME patients (5).


Figure of urea cycle and ammonia excretion pathways (14):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3977640/figure/F1/


What is going on with nitrogen excretion and CPS1 in ME?


References

1) Semba et al. Environmental Enteric Dysfunction is Associated with Carnitine Deficiency and Altered Fatty Acid Oxidation. EBioMedicine. 2017 Mar;17:57-66. doi: 10.1016/j.ebiom.2017.01.026. Epub 2017 Jan 18.
https://www.ncbi.nlm.nih.gov/pubmed/28122695

2) Germain et al: Metabolic profiling of a ME/CFS discovery cohort reveals disturbances in fatty acid and lipid metabolism. Mol. BioSyst. 2017, 13, 371 https://pubs.rsc.org/en/Content/ArticleLanding/2017/MB/C6MB00600K#!divAbstract

3) Germain et al: Prospective Biomarkers from Plasma Metabolomics of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Implicate Redox Imbalance in Disease Symptomatology. Metabolites. 2018 Dec 6;8(4). pii: E90. doi: 10.3390/metabo8040090.
https://www.ncbi.nlm.nih.gov/pubmed/30563204

4) Naviaux RK, Naviaux JC, Li K, Bright AT, Alaynick WA, Wang L, Baxter A, Nathan N et al (2016) Metabolic features of chronic fatigue syndrome. Proc Natl Acad Sci U S A 113:E5472–E5480. https://doi.org/10.1073/pnas.1607571113 

5) Nagy-Szakal et al: Insights into ME/CFS phenotypes through comprehensive metabolomics. Nat. Sci. Rep, 2018, 8. https://www.nature.com/articles/s41598-018-28477-9

6) Wanders et al: Fatty acid omega-oxidation as a rescue pathway for fatty acid oxidation disorders in humans. FEBS J. 2011 Jan;278(2):182-94. doi: 10.1111/j.1742-4658.2010.07947.x. Epub 2010 Dec 13. https://www.ncbi.nlm.nih.gov/pubmed/21156023

7) Guuerrero et al: Laboratory diagnostic approaches in metabolic disorders. Ann Transl Med. 2018 Dec;6(24):470. doi: 10.21037/atm.2018.11.05. https://www.ncbi.nlm.nih.gov/pubmed/30740401

8) Lheureux et al: Science review: carnitine in the treatment of valproic acid-induced toxicity - what is the evidence? Crit Care. 2005 Oct 5;9(5):431-40. Epub 2005 Jun 10.
https://www.ncbi.nlm.nih.gov/pubmed/16277730

9) Yamano et al: Index markers of chronic fatigue syndrome with dysfunction of TCA and urea cycles. Sci Rep. 2016 Oct 11;6:34990. doi: 10.1038/srep34990. https://www.ncbi.nlm.nih.gov/pubmed/27725700

10) Monro and Puri: A Molecular Neurobiological Approach to Understanding the Aetiology of Chronic Fatigue Syndrome (Myalgic Encephalomyelitis or Systemic Exertion Intolerance Disease) with Treatment Implications
Mol Neurobiol. 2018 Sep;55(9):7377-7388. doi: 10.1007/s12035-018-0928-9. Epub 2018 Feb 6.
https://www.ncbi.nlm.nih.gov/pubmed/29411266

11) Nakagawa et al: SIRT5 Deacetylates carbamoyl phosphate synthetase 1 and regulates the urea cycle. Cell. 2009 May 1;137(3):560-70. doi: 10.1016/j.cell.2009.02.026. https://www.ncbi.nlm.nih.gov/pubmed/19410549

12) Nakagawa T1, Guarente L. Urea cycle regulation by mitochondrial sirtuin, SIRT5. Aging (Albany NY). 2009 Jun 29;1(6):578-81. https://www.ncbi.nlm.nih.gov/pubmed/20157539

13) Matone et al. Network Analysis of Metabolite GWAS Hits: Implication of CPS1 and the Urea Cycle in Weight Maintenance. PLoS One. 2016 Mar 3;11(3):e0150495. doi: 10.1371/journal.pone.0150495. eCollection 2016. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0150495

14) Miesel et al: Sodium benzoate for treatment of hepatic encephalopathy. Gastroenterol Hepatol (N Y). 2013 Apr;9(4):219-27. https://www.ncbi.nlm.nih.gov/pubmed/24711766

mandag den 11. marts 2019

Polyamines, 5'-methylthioadenosine and symmetrical dimethylarginine in ME

The polyamines (putrescine, spermidine and spermine) are involved in replication, transcription, translation, and stabilization of macro-molecular complexes. They may also play a role in autoimmunity (1).

Decarboxylated S-adenosylmethionine (dcSAM) and ornithine generates putrescine and subsequently spermine and spermidine. In these reactions, dcSAM is converted to 5′-methylthioadenosine (MTA). Accumulation of MTA inhibits the enzyme protein arginine N-methyltrasferase 5 (PRMT5), which uses SAM as a methyl donor to synthesize symmetrical dimethylarginine (sDMA) from arginine. In the methionine cycle, MTA is cleaved to 5-methylthioribose-1-phosphate (MTR) and adenine by the enzyme methylthioadenosine phosphorylase (MTAP). MTAP deficient cells are more reliant on de novo purine synthesis to generate AMP, since they are unable to cleave MTA to salvage adenine (2).
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Figure 8 . The Methione Cycle from reference 2, Luengo et al: Targeting Metabolism for Cancer Theraphy. Methionine is an essential amino acid that can be used for methylation reactions, cysteine synthesis, and polyamine generation. Methionine is converted to S-adenosylmethionine (SAM) by methionine adenosyltransferase (MAT) (2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5744685/figure/F8/?report=objectonly


Some ME patients have changed plasma/serum levels in different studies compared to normal controls of the following metabolites:

  • increased arginine (only males) and decreased adenosine (= adenine + ribose) (only females) (3)
  • increased ornithine (4)
  • increased spermidine and N-acetylputrescinium (5)
  • increased MTA (6)
  • decreased SDMA (only females) (7)

Some ME patients have single nucleotide polymorphism (SNP) in the gene MTAP (8).

MTA was identified as part of a biomarker panel in critically ill patients with malnutrition (9).

PRMT5 is involved in B-cell differentiation (10).

PRMT5 has a role in the regulation of Circadian Per1 gene (11).

Some ME patients have upregulated expression of PER1 in the immune cells (12).




References:

1) Brooks: Increased Polyamines Alter Chromatin and Stabilize Autoantigens in Autoimmune Diseases. Front Immunol. 2013; 4: 91. https://www.ncbi.nlm.nih.gov/pubmed/23616785

2) Luengo et al. Targeting Metabolism for Cancer Therapy.Cell Chem Biol. 2017 Sep 21;24(9):1161-1180. doi: 10.1016/j.chembiol.2017.08.028. https://www.ncbi.nlm.nih.gov/pubmed/?term=28938091

3) Naviaux RK, Naviaux JC, Li K, Bright AT, Alaynick WA, Wang L, Baxter A, Nathan N et al (2016) Metabolic features of chronic fatigue syndrome. Proc Natl Acad Sci U S A 113:E5472–E5480. https://doi.org/10.1073/pnas.1607571113

4) Yamano et al: Index markers of chronic fatigue syndrome with dysfunction of TCA and urea cycles. Sci Rep. 2016 Oct 11;6:34990. doi: 10.1038/srep34990. https://www.ncbi.nlm.nih.gov/pubmed/27725700

5) Germain et al: Metabolic profiling of a ME/CFS discovery cohort reveals disturbances in fatty acid and lipid metabolism. Mol. BioSyst. 2017, 13, 371 https://pubs.rsc.org/en/Content/ArticleLanding/2017/MB/C6MB00600K#!divAbstract

6) Nagy-Szakal et al: Insights into ME/CFS phenotypes through comprehensive metabolomics. Nat. Sci. Rep, 2018, 8. https://www.nature.com/articles/s41598-018-28477-9

7) Fluge et al: Metabolic profiling indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy / chronic fatigue syndrome. JCI Insight. 2016; 1(21):e89376. Doi 10.1172/jci.insight.89276

8) Smith et al: Convergent genomic studies identify association of GRIK2 and NPAS2 with chronic fatigue syndrome. Neuropsychobiology. 2011;64(4):183-94. doi: 10.1159/000326692. Epub 2011 Sep 9.  https://www.ncbi.nlm.nih.gov/pubmed/21912186

9) Mogensen et al: Metabolites Associated With Malnutrition in the Intensive Care Unit Are Also Associated With 28-Day Mortality. JPEN J Parenter Enteral Nutr. 2017 Feb;41(2):188-197. doi: 10.1177/0148607116656164. Epub 2016 Jul 19.
https://www.ncbi.nlm.nih.gov/pubmed/?term=27406941

10) Mei et al: PRMT5-mediated H4R3sme2 Confers Cell Differentiation in Pediatric B-cell Precursor Acute Lymphoblastic Leukemia. Clin Cancer Res. 2019 Jan 11. doi: 10.1158/1078-0432.CCR-18-2342. https://www.ncbi.nlm.nih.gov/pubmed/?term=30635341

11) Na et al: Role of type II protein arginine methyltransferase 5 in the regulation of Circadian Per1 gene. PLoS One. 2012;7(10):e48152. doi: 10.1371/journal.pone.0048152. Epub 2012 Oct 25. https://www.ncbi.nlm.nih.gov/pubmed/23133559

12) Sweetman et al: Changes in the transcriptome of circulating immune cells of a New Zealand cohort with myalgic encephalomyelitis/chronic fatigue syndrome. Sweetman et al: Int J Immunopathol Pharmacol. 2019 Jan-Dec;33:2058738418820402. doi: 10.1177/2058738418820402.
https://www.ncbi.nlm.nih.gov/pubmed/30791746

tirsdag den 26. februar 2019

ME minder om medfødt metabolisk defekt

Vores mad indeholder kulhydrater, protein og fedt, som vi ved fordøjelse nedbryder til henholdsvis glukose, aminosyrer og fedtsyrer. Disse bestanddele anvender kroppen som byggesten og brændstof. Dette kaldes stofskifte eller metabolisme. Der findes forskellige former for stofskiftesygdomme og dysreguleret metabolisme.

Hver sygdom har sin forklaring. Manglende evne til at omsætte glukose, som det ses ved diabetes type 1, skyldes autoimmunitet. Manglende evne til at nedbryde fedtsyrer kan skyldes medfødt defekt i enzymer, cofaktorer eller andre proteiner, der er involveret i fedtsyreforbrændingen.

En lang række studier har påvist dysreguleret metabolisme hos ME-patienter (1, 2, 3, 4 og 5).

Den bagvedliggende årsag er endnu ikke klarlagt, men der tegner sig et mønster, der kan sammenlignes med medfødte defekter i metabolisme (engelsk: inborn errors of metabolism).

For at anskueliggøre dette følger nu tre eksempler på medfødte metaboliske defekter.

1. eksempel på medfødt metabolisk defekt: CPT2 mangel

På figuren nedenfor ses det, at CPT1, CPT2, acyl-CoA og carnitine tilsammen udgør et system, der kan sluse langkædede fedtsyrer ind i mitokondrierne til nedbrydning (6):

Acyl-CoA from cytosol to the mitochondrial matrix.svg
Figur fra wikipedia: Carnitine palmitoyltransferase II deficiency (6).

Mennesker med medfødt defekt i CPT2 genet har problemer med at nedbryde langkædede fedtsyrer.

Patienterne har motionsintolerance og kan opleve muskelsvaghed og smerter. Patienterne har ophobet langkædede fedtsyrer i blodet, har lavt niveau af carnitine og højere niveau af acylcarnitiner. Herudover har de højt niveau af serum kreatinkinase og kan have myoglobin i urinen (6, 7).


FAKTA om FEDTSYRER
Fedtsyrer er lange kæder af kulstofatomer. Kulstof hedder også carbon og forkortes C. Fedtsyrer inddeles efter længden på deres kulstofkæde:
Kortkædede fedtsyrer         = under 6 C
Mellemkædede fedtsyrer     = 6 - 12 C
Langkædede fedtsyrer          = 13-21 C
Meget langkædede fedtsyrer = 22 eller flere C

2.eksempel på medfødt metabolisk defekt: Carnitine transport defekt

Carnitine er nødvendig for at transportere de langkædede fedtsyrer ind i mitokondrierne. Carnitine fås gennem kosten, og kroppen kan også selv danne det. Herudover bliver carnitine tilbageholdt i nyrerene ved hjælp af et carnitine transport molekyle, OCTN2. Mennesker med medfødt defekt i OCTN2 genet mister carnitine i urinen og har derfor lavt niveau af carnitine i blodet (8).

3. eksempel på medfødt metabolisk defekt: FAD mangel:

Flavin adenine dinucleotide (FAD) er en cofaktor, som er nødvendig for at en lang række af metaboliske enzymer kan fungere. Genet FLAD1 koder enzymet FAD synthase, som sørger for at danne FAD. Medfødte defekter i genet FLAD1 kan føre til multiple acyl-CoA dehydrogenase mangel. Undersøgelse af patienterne viser individuelt forskellige forhøjede niveauer af acylcarnitiner og organiske syrer. Muskelbiopsi viser mitokondriedysfunktion og lipidophobning. Patienterne kan have synke- og talebesvær (10).

Ophobning af fedtsyrer, der ikke forbrændes

Ophobning af langkædede fedtsyrer og acyl-carnitiner kan have en detergent-lignende virkning på membraner og herved påvirke ion-kanaler og elektriske signaler i cellen. Det kan medfører hjerterytmeforstyrrelse hos patienter med disse medfødte defekter i fedtsyreoxidationen (8, 9).


CPT1, CPT2, acyl-carnitine, carnitine og FAD hos ME patienter

En undersøgelse af plasma fra 49 ME-patienter viste, at de i forhold til raske kontrolpersoner havde lavere niveauer af følgende acylcarnitiner: C8:1, C14, C16:1, C18, C18:1, C18:2. Acylcarnitinerne C12DC og C18:1-OH var forhøjede. Som forklaring nævner forskerne bag forsøget, at der kan være nedsat CPT1 aktivitet og at CPT2 muligvis også kan være påvirket hos patienterne (1).

En undersøgelse af plasma fra 17 kvindelige ME-patienter viste forhøjede niveauer af palmitate C16, margarate C17, stearate C18, DHA (22:6 (n-3)), pristanin syre og af sebacin syre (2). Sebacin syre anvendes som indikator for flere forskellige medfødte defekter i fedtsyreoxidationen (9).

Et metabolisme-studie af 45 ME-patienter (22 mænd og 23 kvinder) viste, at kvinderne havde øget plasmaniveau af adipoylcarnitine, som kan være indikation på nedsat mitokondriel oxidation af langkædede fedtsyrer. Både mænd og kvinder havde nedsat plasmaniveau af FAD, som er en nødvendig cofaktor i fedtsyreoxidationen (3).

Plasmaniveauet af adipolylcarnitine var også øget i en undersøgelse af 32 kvindelige ME-patienter. Herudover var hydroxy butyrul carnitine, 3-hydroxy butyrul carnitine, pimeloylcarnitine/C7-DC, C14:1 og C18:1 ligeledes øget, mens niveauet af 3,4 methyleneheptanoyl carnitine var lavere (4).

Gamma-butyrobetaine er byggesten til carnitine og kaldes derfor også ”pre-carnitine”. Både betaine, gamma-butyrobetaine, carnitine og choline, som alle indgår i carnitine-choline stivejen, var nedregulerede i en undersøgelse af plasma fra 50 ME-patienter (41 kvinder og 9 mænd). Plasmaniveauet af acylcarnitine C9:1 og C11:1 var også lavere hos ME patienterne end hos de raske kontrolpersoner (5).

Germain et al har i deres sidste metabolisme studiet udført en computeranalyse, hvor de sammenligner flere ME-metabolisme studier. Analysen viser en top-10 over de sygdomme, som mest ligner ME ud fra ME-pateinters metaboliske profil. Bemærk at det er flere medfødte metaboliske sygdomme på listen (4).




Sammenfattende må det konkluderes, at fedtsyreforbrændingen er påvirket hos ME-patienter, og at man med fordel kan anvende forskning og analysemetoder fra området ”inborn errors af metabolism” for at blive klogere på ME-sygdomsmekanismen.

Spørgsmål som ME patienter har brug for at få svar på:

Er det påviste lave plasma niveau af carnitine hos ME paitenterne i forskningsresultaterne klinisk relevant? Kan nogle ME patienter have behov for carnitine kosttilskud?

Læs også:

FAM13A, fatty acid oxidation and ME
http://followmeindenmark.blogspot.com/2018/08/fam13a-fatty-acid-oxidation-and-me.html

ME, nedsat PDH-funktion og behandlingsmulighed
https://followmeindenmark.blogspot.com/2017/11/me-nedsat-pdh-funktion-og.html



REFERENCER

1) Reuter and Evans: Long-chain acylcarnitine deficiency in patients with CFS. Potential involvement of altered carnitine palmitoyltransferase-I-activity. J. Int. Med. 2011, 270.

2) Germain et al: Metabolic profiling of a ME/CFS discovery cohort reveals disturbances in fatty acid and lipid metabolism. Mol. BioSyst. 2017, 13, 371 https://pubs.rsc.org/en/Content/ArticleLanding/2017/MB/C6MB00600K#!divAbstract

3) Naviaux RK, Naviaux JC, Li K, Bright AT, Alaynick WA, Wang L, Baxter A, Nathan N et al (2016) Metabolic features of chronic fatigue syndrome. Proc Natl Acad Sci U S A 113:E5472–E5480. https://doi.org/10.1073/pnas.1607571113

4) Germain et al: Prospective Biomarkers from Plasma Metabolomics of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Implicate Redox Imbalance in Disease Symptomatology. Metabolites. 2018 Dec 6;8(4). pii: E90. doi: 10.3390/metabo8040090.
https://www.ncbi.nlm.nih.gov/pubmed/30563204

5) Nagy-Szakal et al: Insights into ME/CFS phenotypes through comprehensive metabolomics. Nat. Sci. Rep, 2018, 8. https://www.nature.com/articles/s41598-018-28477-9

6) Wikipedia Carnitine palmitoyltransferase II deficiency

7) Meritt II et al: Fatty acid oxidation disorders. Ann Transl Med. 2018 Dec;6(24):473. doi: 10.21037/atm.2018.10.57. https://www.ncbi.nlm.nih.gov/pubmed/30740404

8) Longoet al: Carnitine transport and fatty acid oxidation https://www.ncbi.nlm.nih.gov/pubmed/26828774

9) Ingrid Tein: Disorders of fatty acid Oxidation. Handbook of clinical Neurology, chapter 170. 2013 https://www.sciencedirect.com/science/article/pii/B9780444595652000356

10) Rikke Olsen et al: Riboflavin-Responsive and -Non-responsive Mutations in FAD Synthase Cause Multiple Acyl-CoA Dehydrogenase and Combined Respiratory-Chain Deficiency. Am J Hum Genet. 2016 Jun 2;98(6):1130-1145. doi: 10.1016/j.ajhg.2016.04.006. https://www.ncbi.nlm.nih.gov/pubmed/27259049






fredag den 28. december 2018

Flippase, floppase and scramblase

The cell membrane is composed of cholesterol and phospholipids arranged in a lipid bilayer (outer and inner monolayer).

There is a asymmetric phospholipid distribution in the bilayer. Three families of proteins are responsible for the translocation of phospholipids between the two monolayers (1):

  • Flippases move phospholipids from the outer to the inner monolayer.
  • Floppases do the opposite operation.
  • Scramblases move phospholipids in both directions.

ATP10A and ATP11A

Flippase ATP10A flips phosphatidylcholine at the plasmamembrane. This activity drives membrane curvature (2).

Flippase ATP11A has flippase activity toward phosphatidylserine and phosphatidylethanolamine (3).

The gene ATP10A has changed DNA methylation pattern in peripheral blood mononuclear cells (PBMC) from ME patients (4, 5, 6).

The gene ATP11A has changed DNA methylation pattern in PBMC from ME patients (4, 5).

PLSCR1 and PLSCR3

Phospholipid scramblase 1 (PLSCR1) is also known as erythrocyte phospholipid scramblase.

Use link to see figure (7):
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992676/figure/F7/

PLSCR1 aggravates anaphylactic reactions by increasing FcεRI-dependent mast cell degranulation. (8).

PLSCR3 may be involved in translocation of cardiolipin from the inner to the outer mitochondrial membrane (1).

PLSCR1 gene expression in whole blood was related to ME/CFS in adolescents (9, 10).

The gene PLSCR3 was hypomethylated in PBMC from ME patients (6). And PLSCR3 was differntially methylated in PBMC from ME patient subtypes (5).

CRIM1 and PLSCRs

CRIM1 interacts with PLSCRs (11):




CRIM1: Cysteine rich transmembrane BMP regulator 1 (chordin-like); May play a role in CNS development by interacting with growth factors implicated in motor neuron differentiation and survival. May play a role in capillary formation and maintenance during angiogenesis. Modulates BMP activity by affecting its processing and delivery to the cell surface (11).

PLSCR1: Phospholipid scramblase 1; May mediate accelerated ATP-independent bidirectional transbilayer migration of phospholipids upon binding calcium ions that results in a loss of phospholipid asymmetry in the plasma membrane. May play a central role in the initiation of fibrin clot formation, in the activation of mast cells and in the recognition of apoptotic and injured cells by the reticuloendothelial system (11).

Phospholipid scramblase 2; May mediate accelerated ATP-independent bidirectional transbilayer migration of phospholipids upon binding calcium ions that results in a loss of phospholipid asymmetry in the plasma membrane. May play a central role in the initiation of fibrin clot formation, in the activation of mast cells and in the recognition of apoptotic and injured cells by the reticuloendothelial system (11).

PLSCR3: Phospholipid scramblase 3; May mediate accelerated ATP-independent bidirectional transbilayer migration of phospholipids upon binding calcium ions that results in a loss of phospholipid asymmetry in the plasma membrane. May play a central role in the initiation of fibrin clot formation, in the activation of mast cells and in the recognition of apoptotic and injured cells by the reticuloendothelial system. Seems to play a role in apoptosis, through translocation of cardiolipin from the inner to the outer mitochondrial membrane (11).

The gene CRIM1 has changed DNA methylation pattern in PBMC from ME patients (4, 5, 6), and in CD4+ T-cells from ME patients (12).

New research:

Phospholipid scramblase 1 interacts with influenza A virus NP, impairing its nuclear import and thereby suppressing virus replication https://www.ncbi.nlm.nih.gov/pubmed/29352288

References

  1. Wikipedia: Phospholipid scramblase
  2. PMID: 29599178
  3. PMID: 26567335
  4. de Vega et al: Epigenetic modifications and glucocorticoid sensitivity in ME/CFS. BMC Medical Genomics, 2017, 10, 11 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5324230/
  5. de Vega et al: Integration of DNA methylation & health scores identifies subtypes in ME/CFS. Epigenomics 2018, 10, 5 https://www.futuremedicine.com/doi/full/10.2217/epi-2017-015
  6. Trivedi et al: Identification of ME/CFS - associated DNA methylation patterns.
    Plos One 2018, 13, 7 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201066
  7. Huisjes et al: Sqeezing for life - Properties of Red Blood Cell Deformability. Front Physiol. 2018 Jun 1;9:656. doi: 10.3389/fphys.2018.00656. eCollection 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992676/
  8. PMID: 28282470 https://www.ncbi.nlm.nih.gov/pubmed/?term=28282470
  9. Nguyen et al: Whole blood gene expression in adolescent CFS: an exploratory crosssectional study suggesting altered B cell differentiation and survival. J Transl Med. 2017,15,102.  https://www.ncbi.nlm.nih.gov/pubmed/28494812
  10. Nguyen et al: Associations between clinical symptoms, plasma norepinephrine and deregulated immune gene networks in subgroups of adolescent with CFS. Brain, Behavior and immunity.
  11.  https://www.genecards.org/  CRIM1
  12. Brenu et al: Methylation profile of CD4+ T cells in CFS/ME. J. Clin Cell Immunol 5, 228https://www.omicsonline.org/open-access/methylation-profile-of-cd-t-cells-in-chronic-fatigue-syndromemyalgic-encephalomyelitis-2155-9899.1000228.php?aid=27598

fredag den 30. november 2018

Bile acid transporter SLCO3A1 and ME

Bile acid transporters maintain bile acid homeostasis.

Solute Carrier Organic Anion Transporter Family Member 3A1 (SLCO3A1) Is a Bile Acid Efflux Transporter in Cholestasis (1).

SLCO3A1 is up-regulated as an adaptive response to cholestasis (1).

Genome-wide association analysis identified a single nucleotide polymorphism (SNP) in SLCO3A1 in ME patients (2).

Epigenetic analysis identified that the gene SLCO3A1 (5'UTR) was hypomethylated in peripheral blood mononuclear cells (PBMC) from ME patients. (3).

Metabolomic analysis on plasma from ME patients identified lower levels of (4):

  • glycocholate
  • glycochenodeoxycholate
  • glycolithocholate
  • lithocholate
  • sulfoglycolithocholate
  • taurine

How is SLCO3A1 involved in ME?

Interestingly, bile acids activated receptors regulate innate immunity (5).

References

1) Pan et al. Solute Carrier Organic Anion Transporter Family Member 3A1 Is a Bile Acid Efflux Transporter in Cholestasis. Gastroenterology. 2018 Nov;155(5):1578-1592.e16. doi: 10.1053/j.gastro.2018.07.031. Epub 2018 Jul 29. https://www.ncbi.nlm.nih.gov/pubmed/30063921

2) Schlauch et al: Genome-wide association analysis identifies genetic variations in subjects with ME/CFS. 2016.doi.10.1038/tp.2015.208

3) Trivedi et al: Identification of ME/CFS - associated DNA methylation patterns.
Plos One 2018, 13, 7 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201066

4) Germain et al: Metabolic profiling of a ME/CFS discovery cohort reveals disturbances in fatty acid and lipid metabolism. Mol. BioSyst. 2017, 13, 371 https://pubs.rsc.org/en/Content/ArticleLanding/2017/MB/C6MB00600K#!divAbstract

5) Fiorucci et al. Bile Acids Activated Receptors Regulate Innate Immunity. Front Immunol. 2018 Aug 13;9:1853. doi: 10.3389/fimmu.2018.01853. eCollection 2018.
https://www.ncbi.nlm.nih.gov/pubmed/30150987