Les faux positifs, biologiques, des TNE
JB Corcuff,
Lab. Hormonologie et marqueurs tumoraux
Introduction
Biomarqueurs « classiques » : molécules sécrétées ou métabolites utilisées dans le diagnostic ou le suivi de pathologies
Leur utilité repose sur des critères cliniques de courbes ROC (sens., spé., VPP, VPN)
Quelle spécificité pour les biomarqueurs des TNE ?
Donc, le problème :
Faux positifs « physio(patho)logiques »
Faux positifs « analytiques » (immunodosage, e-χ & LCMSMS)
Dosages : immunodosages
Technique par défaut d’anticorps (compétitif)
Technique par défaut d’anticorps (sandwich)
Dosages : immunodosages
Surévaluation (ou sous évaluation) : expl d’un dosage par excès d’Ac
Réactions croisées et autres
(Fragments, IRC, Mdt…)
Ac hétérophiles et autres
(immun°anti animal, PR, lupus…)
www.candor-bioscience.de/fileadmin/user_upload/lw4-2005-interferenzen.pdf
Dosages : électrochimie ou LC/MSMS
Chromatographie puis
Détecteur électrochimique ou
Spectromètre de masse
Dosages : électrochimie ou LC/MSMS
Madhavaram & Woollard 2013
Interférence par
régime « indien »
Trousse commerciale
Sérotonine/5HIAA Faux positifs « physiologiques »
Sérotonine (circulante plaquettaire)
90% C. enterochromaffines, 10% neurones 5HIAA hépatique, élimination rénale
Effet Lumière du jour ?
Corcuff et al.Endoc. Connections 2016
Sérotonine/5HIAA Faux positifs « physiologiques »
Xiaet al. 2017
Cancer colon
Hayneset al.2017
Mort subite nourisson
Acta Physiologica Sinica, February 25, 2013, 65(1): 33–38 36
postload plasma N1-methylnicotinamide was signifi- cantly higher than the baseline value (Fig. 2B).
2.2 Nicotinamide loading decreased plasma betaine level
Accompanied with the increased urinary excretion of 2-Py, there was a significant decrease in the plasma level of betaine 5 h after nicotinamide load (Fig. 3A).
The plasma choline concentration also showed a de- crease trend, but there was no statistically significant difference compared with baseline value (P > 0.05, Fig.
3B). These results indicate that excess nicotinamide de- creases the methyl-group pool size.
2.3 Nicotinamide loading increased plasma sero- tonin and histamine levels
We then examined the effect of nicotinamide load on plasma serotonin and histamine levels. The result showed that the 5-hour postload plasma serotonin level was significantly higher than the value before nicoti- namide load (P < 0.05, Fig. 4A). Similarly, the level of plasma histamine was also significa nt ly increased (Fig.
4B). This study demonstrated that excess nicotinamide may play a causal role in increased plasma serotonin and histamine levels.
methylated derivatives[7], suggest that excessive nicotinamide could inhibit the degradation of monoamine neurotransmitters presumably due to methyl-group pool depletion.
In humans, nicotinamide is degraded mainly via methylation to produce methylated metabolites, N1- methyl nicotinamide and 2-Py[6]. Evidently, excess nic- otinamide can increase the consumption of labile methyl groups. Betaine serves as a methyl donor in a reaction converting homocysteine to methionine, whereas cho- line can be converted to betaine in the liver and kid- ney[9]. Therefore, the levels of plasma choline and be- taine are indicators of the size of methyl-group pool of the body. The present findings that nicotinamide load had a more profound influe nce on plasma betaine than choline suggest that betaine is a more effective methyl donor than choline.
Niacin is usually classifie d
as a B vitamin. However, strictly speaking, it is not a vitamin because it can be synthesized from tryptophan. As shown in Fig. 1, tryptophan is degraded through tryptophan-kynurenine- niacin and tryptophan-serotonin pathways. These two pathways function together to regulate tryptophan homeostasis. For example, an increase in nicotinamide intake can lead to an increase in urinary excretion of 5-hydroxyindoleacetic acid, a metabolite of serotonin[10], suggesting an increase in tryptophan degradation through tryptophan-serotonin pathway (i.e., an increase in serotonin synthesis). Moreover, nicotinamide may affect methylation-mediated serotonin degradation by competing for methyl groups. Therefore, high nicotinamide intake may increase serotonin levels by a mechanism of increased synthesis and decreased degradation.
Serotonin and histamine act not only as neurotrans- mitters, but also function as important signaling molecules in the skin, gastrointestinal tract and immune system[11,12] on the one hand, and on the other hand, neuropsychiatric disorders, such as autism[13] and schizophrenia[14], are often associated with immune abnormalities, besides disturbed monoamine-neuro- transmitter metabolism[1,2]. The find i ng that nicotinamide load increases the plasma levels of both serotonin and histamine, suggests that excess nicotinamide load could affect both the nervous system and the immune system.
Although not proved, high nicotinamide intake, which is very common nowadays due to mandatory vitamin fortific
a
t ion [15], may play a role in the association between abnormal metabolism of monoamine neuro-transmitters and immune abnormalities in neuropsychiatric disorders.
Fig. 4. Plasma serotonin (A) and histamine (B) levels before and 5 h after nicotinamide load. Means ± SEM, n = 9. *P < 0.05 vs before nicotinamide load (–1 h).
3 DI SCUSSI ON
This study found that nicotinamide load reduced the methyl-group pool associated with increases in plasma serotonin and histamine levels. The present findings, together with earlier results showing that nicotinamide load increased plasma norepinephrine but decreased its
Nicotinamide (vit B3)
Tian et al. 2013
Sérotonine/5HIAA Faux positifs « analytiques »
* Faux positifs par apport alimentaire
Sérotonine : kiwi, ananas (jus), noix (+++ classique & pécan, +cajou macadamia) châtaigne amande, ± tomate prune avocat
Tryptophane : idem supra & graines, haricots, fromage (pas d’effet sur sérotonine cérébrale, transporteur multi AA)
* Faux positifs par apport « Compléments » alimentaires tryptophane ++++
« Supplément » vitaminique B3 ?
* Probablement pas d’effet notable des médicaments y compris inhibiteur de recapture de la sérotonine
Corcuff et al.Endoc. Connections 2016
Métanéphrines Faux positifs « physiologiques »
Tyrosine
DOPA
Dopamine
Norepinephrine
Epinephrine Tyrosine
hydroxylase
Dopamine β-hydroxylase L-DOPA
decarboxylase
PNMT
Methoxy
tyramine HVA
VMA
Catechol-O-methyl-transferase
Sulfo-transferase Met-
norepinephrine
Met- epinephrine
Métabolites d’hormones de stress +++ réa, chirurgie, choc…
++ apnées sommeil, IRC
+ position, anxiété, double file…
Valeurs de références,
délicates..
Métanéphrines Faux positifs « physiologiques »
Oncotarget 15652
www.oncotarget.com
the run (2685.5 pmol/L; range, 1432–5563 pmol/L vs 488.5 pmol/L; range, 158–798 pmol/L; p < 0.0001).
Unlike MN, the plasma concentration of NMN measured at 6 and 24 h after the run remained significantly higher than the pre-run concentration (715 pmol/L; range, 362–
1704 pmol/L; p < 0.0001 and 652.5 pmol/L, range, 359–
993 pmol/L; p = 0.0031). Moreover, the concentration of NMN measured 24 hours after the run was lower than that measured 6 hours after the run (p = 0.0026).
The delta values of both MN and NMN did not significantly correlate with any anthropometric baseline characteristic or laboratory data. Nevertheless, a statically significant correlation was found between NMN variation and VO2max (r = 0.663, p = 0.005). Interestingly, the pre- run values of NMN were found to be inversely correlated with NMN delta values (Figure 2).
In univariate analysis, running performance was found to be significantly associated with sex (r = 0.418, p
= 0.025), age (0.300, p = 0.049), capillary blood lactate (r
= –0.590, p = 0.001), pre-run NMN values (r = 0.451, p
= 0.021) and NMN delta values (r = –0.418, p = 0.033).
These two last associations are shown in Figure 3. In multivariate analysis, where running time was entered
as a dependent variable and the parameters significantly associated with running performance in univariate analysis were entered as independent variables, all parameters were confirmed to be significant predictors of running performance (Table 2). Due to the correlation between delta and pre-run NMN values, the former was not entered in the multivariable model. The combination of gender, sex, age, blood lactate and delta values of NMN predicted 82.2% (95% CI, 73.8–90.6%; p < 0.001) of variance in running performance.
DI SCUSSI ON
The biology of sympatho-adrenergic activation in response to exercise has been a matter of debate for almost 30 years. Available evidence suggests that acute exercise may be effective in significantly increasing blood catecholamine concentrations in healthy subjects, and that this increase may be dependent on exercise intensity [25, 26]. Moreover, it is more probable that it is related to increased secretion than to an impaired clearance or a decreased elimination [27]. Nevertheless, reliable studies aimed to assess the association between competitive
Figure 1: M N and NM N values at different time point before and after the half-marathon run.a *Significnt difference with respect to pre-run values.
Table 1: Demographical, anthropometric and ergonomic data
M edian (range)
Age (years) 47 (30–63)
Gender (M/F) 15/11
BMI (Kg/m2) 22.8 (18.5–27.8)
VO2max (mL/kg/min) 49.5 (40.6–58.0)
Running performance (min) 112 (91–149)
VO2max, maximal oxygen uptake
Pamporakiet al.2014
Daneseet al.2018
Eisenhoferet al.2013
Saison
Café Age
Effort
Deubstein et al.2010
Métanéphrines Faux positifs « analytiques »
• Faux positifs par apport alimentaire de catécholamines (surtout DA)
- faux pos. méthyldopamine (paragangliomes) & HVA (neuroblastomes) - faux pos. VMA (vanilline & VMA, neuroblastomes)
Aliments : surtout bananes & plantains.
* Interférence analytique possible avec molécules de structure proche ou réactif à l’oxydo-réduction (urapidil, méthenamine, paracétamol, méthyldopa, methoxy-hydroxybenzylamine, methylenedioxy-methamphetamine, …)
Probablement peu d’effets indirects des médicaments
y compris inhibiteurs de recapture
Corcuff et al.Endoc. Connections 2016 Osingaet al.2016
Gastrine Faux positifs « physiologiques »
1
erHormone gastro-intestinale dosée (ZE/gastrinome, ulcère, K estomac) Multiples formes (± sulfatation) ; Gastrine 17 ≈ 85%
Bioactivités identiques, ½ vies différentes, immuno-reconnaissance variable
•
Gastrine Faux positifs « physiologiques »
Goldman et al. 2009
Atrophie gastrique Hypoacidité gastrique Traitements
• Inhibiteur pompe proton
• Anti histaminiques, transitoire
• Autres…?
Perrachiet al. 2005
Lim et al. 2013
Pantoprazole x 2-3
(141-1840 ; N<110 ng/L Massironiet al. 2013 )
Gastrine Faux positifs « analytiques »
Rehfeldet al., 1981, 2011, 2012
La sulfatation peut varier de 10 à 80%
La sulfatation peut faire varier l’immunoréactivité par 100
Dosage des mêmes sérums avec de multiples trousses : ici valeurs < 100 avec trousse de « ref »
Calcitonine Faux positifs « physiologiques »
Calcitoninémie
Sexe, âge, exercice physique Hyperplasie cellules C
Cancer thyroïdien papillaire & folliculaire Thyroïdite de Hashimoto
Tumeurs neuroendocrines IRC
Sepsis (vrai calcitonine ?) Béta-bloquants, IPP, GC
Bastistaet al.2013 ; Toledo et al.2009
Calcitonine Faux positifs « physiologiques »
* Faux positifs par Ac hétérophiles (Case reports)
Tommasi et al., JEI 2001 ; Censi et al., CCLM 2016 ; Papapetrou et al., JEI 2006 ; Bories et al., CCLM 2016
* Réactions croisées avec macrocalcitonine (IgG) ou procalcitonine (pb des infections graves ?)
Alves et al., JCEM 2016 ; Uhrova et al., Scand J Clin Lab Invest. 2011
VIP Faux positifs « physiologiques »
VIP modérément élevé dans les diarrhées des SIDA (Manfredi et al. 1993) Mastocytoses
Maintzet al. 2011
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 09 August 2016. at 10:43 For personal use only. No other uses without permission. . All rights reserved.
Holst et al. 1989
Stim° ovarienne Migraines
Cernuda-Morollónet al. 2014
Pas vraiment une hormone, plutôt un neurotransmetteur
Chromogranine Faux positifs « physiologiques »
Corti et al.Eur J Physiol 2018
Eissaet al. Biochemical Pharmacology 2018
CgA : formation, adressage & fusion des granules de sécrétion (Ca
2+)
Peptides dérivés : angiogenèse,
pro- ou anti-inflammatoires, métabolisme…
(Modif° post-traductionelles)
Clivages variables :
p.e. ratio pro/anti angiogènes accru dans myélome
