EFFECT OF MELATONIN SUPPLEMENTATION ON PLASMA LIPID HYDROPEROXIDES, HOMOCYSTEINE CONCENTRATION AND CHRONIC
FATIGUE SYNDROME IN MULTIPLE SCLEROSIS PATIENTS TREATED WITH INTERFERONS-BETA
Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease that damages myelin and axons. Its prevalence is estimated at about 2.5 million people worldwide (1). MS is the main cause of neurological disability in young adults. Apart from physical dysfunction, cognitive functions impairment, depression and chronic fatigue syndrome in MS patients are often observed (2-10). Chronic fatigue syndrome occurs in about 80 – 90% of MS patients (1, 8, 9, 11, 12). It can be present at any stage of the disease and it affects many aspects of life, such as social functioning, employment, driving safety, physical independence, rehabilitation gains, disease management, treatment adherence, mood, and finally, reduced quality of life (8, 9, 13). Definition of chronic fatigue syndrome consists of exhibiting persistent fatigue which is substantially unrelieved by rest, and accompanied by other symptoms such as circadian rhythm sleep disorders and cognitive dysfunction for a minimum of 6 months (14). The pathogenesis of chronic fatigue remains incompletely understood. Fatigue could be evaluated by Modified Fatigue Impact Scale (MFIS) (15-17). Sleep disturbances could be the cause or result of depression in MS subjects, and both might also be associated with fatigue in these patients. It was also found that fatigue and daytime sleepiness are frequent in MS patients. Moreover, it was reported that anxiety and pain are the most common causes of initial insomnia, and nocturia is the most common cause of middle insomnia (11).
MS prevalence is higher in geographic regions with less sunlight exposure. Melatonin and vitamin D participate in the effects of sunlight in healthy individuals, and both could play a role in MS pathophysiology (18, 19). Melatonin (N-acetyl-5-methoxytryptamine) is a natural hormone mainly produced in the mammalian pineal gland during the dark phase. Maximal peak of melatonin’s release is observed at darkness and minimum at lightness (20). However, in MS patients, increased serum proinflammatory cytokines and impaired immune cells circulating may disrupt circadian clock through decreased melatonin’s production in dark phase (20, 21). With its lipophilic and hydrophilic character, melatonin freely crosses the blood-brain barrier and enters all cells (22). Melatonin and its metabolites have been demonstrated to possess multiple functions, including antioxidative, immunomodulatory, and anti-inflammatory (23, 24). The important role of melatonin as a modulator of sleep is well documented. Melatonin treatment can also entrain the circardian clock (25).
Lack of sunlight in the high altitudes cause melatonin level increase and triggering immune system. Produced during the night melatonin releases into retinal ganglion cells and stimulates Th17 cells and increase circulating levels of IL-17. It could be related with MS worsening (26). But, on the other hand this conflicts the other found result that melatonin can be neuroprotective and antinflamatory. Many papers proved that melatonin play a role in MS as an antioxidant, lipid metabolism regulator also, takes part in neurogenesis, immunomodulation and neuroprotection (23-25, 27-29) Interesting paper published by Farez et al. showed that melatonin shifts the immune response toward an anti-inflammatory state and lulling Th17 cells to sleep. It may explain the seasonal variability of multiple sclerosis disease activity (30). Moreover, positive melatonin effect on frequent MS clinical symptoms like fatigue, mood disorder, fluctuation of symptoms and clinical neurological state improvement was observed (27, 31, 32).
Recent studies have suggested that oxidative stress can play a crucial role in the pathogenic traits of MS. Processes responsible for generation of reactive oxygen species (ROS) and lipid peroxidation, hallmarks of oxidative stress, have been studied in attempt to develop therapies that can diminish or stop central nervous system (CNS) damage (33). When generation of ROS exceeds the ability of the endogenous antioxidant system to remove them, the oxidative stress in the brain occurs, subsequently leading to cellular damage.
Pathophysiology of chronic fatigue syndrome is completely unknown. Some previous papers documented that myalgic encephalomyelitis/chronic fatigue syndrome is characterized by activation of immune, inflammatory, oxidative and nitrosative stress mechanisms (34, 35). It was proved that lipid peroxidation is elevated in females with chronic fatigue syndrome (36). Moreover, myalgic encephalomyelitis/chronic fatigue syndrome is characterized by increased oxidative stress through plasma peroxide concentrations elevation (37).
Homocysteine is a sulfur-containing amino acid that is generated from an essential amino acid methionine. Elevated levels of homocysteine unrelated to immune activation, oxidative stress, or a deficiency in vitamin B6, B12, or folate were observed in patients with MS. On the other hand, unchanged homocysteine levels in MS patients compared to controls were also reported (38). Homocysteine causes production of free radicals and hydrogen peroxide, which could conceivably lead to increased plasma lipid hydroperoxides levels (39). Mental fatigue loading in humans leads to a decrease in blood levels of branched-chain amino acids inter alia homocysteine precursor - methionine (40).
The aim of the study was to determine the effect of melatonin supplementation - a substance regulating circadian rhythms, including sleep, on chronic fatigue syndrome in multiple sclerosis patients. Moreover, the aim of this work was to evaluate plasma lipid hydroxyperoxides (LHP) and homocysteine concentrations as a potential biochemical fatigue biomarkers.
MATERIAL AND METHODS
Into a case-control prospective study 102 MS patients and 20 healthy subjects matched for age and sex, observed in 2014 in the Department of Neurology in Zabrze, Medical University of Silesia, Poland were enrolled. The following studied groups were created:
- C group (control group): 20 healthy controls observed in our Department due to undiagnosed headaches. Controls were matched for age and sex with the study group.
- RRMS pretreated group: 21 patients with de novo diagnosed, according to the McDonald criteria (41), relapsing-remitting form of MS (RRMS), immunomodifying pretreated, without any immunomodifying MS treatment.
- RRMS INF-beta group: 52 patients with RRMS, diagnosed according to the McDonald criteria (41). All of them received interferons beta-1a applied once per week as an intramuscular injection (Avonex) or interferon beta-1b (Betaferon), injected subcutaneously every other day.
- SP/PP MS mitoxantrone group: 17 patients with secondarily progressive (SP) or primary progressive (PP) form of MS, diagnosed according to the McDonald criteria (41). All of them received 5 doses of mitoxantrone i.v. (12 mg/m2/dose) administered quarterly.
- RRMS relapse group: 12 RRMS patients diagnosed according to the McDonald criteria (41) receiving INF-beta as immunomodifying MS treatment during relapse period, before conventional relapse steroid-therapy.
At least 3 months before the study patients did not use any vitamins, diet supplements, antioxidative substances, hormonal treatment and sleeping pills two weeks prior to the study.
The study was approved by the local Ethics Committee of the Medical University of Silesia (KNW/0022/KB1/130/12).
Informed consent was obtained from all individual participants included in the study. After obtaining informed consent, demographic data, and Kurtzke’s Expanded Disability Status Scale (EDSS) (42), MRI examinations were performed in all MS patients at the beginning of the study, in accordance with standard clinical protocols. Neurological examination was performed by a qualified neurologist using the EDSS before the therapy and after its completion. Then, all MS patients were supplemented orally with melatonin, 5 mg per day, over a period of 90 days. Neurological examination (conducted by a qualified neurologist using the EDSS) and biochemical assays were performed before and after the melatonin supplementation.
The blood samples were collected between 6.00 and 7.00 a.m., centrifuged and frozen until laboratory measurements.
Plasma lipid hydroxyperoxides LHP concentration was measured according to Sodergren (43) using ferrous oxidation in xylenol orange assay coupled with triphenylphosphine. Results were expressed as µmol/L.
Plasma homocysteine concentration was estimated according to enzyme immunoassay for the determination of homocysteine in serum or plasma. The peroxidase activity was measured after addition of substrate and the absorbance was inversely related to the concentration of homocysteine in the sample (Axis-Shield Homocysteine EIA, UK). Results were expressed as µmol/L.
Fatigue was assessed by the Polish validated version of the Modified Fatigue Impact Scale (MFIS) (15). The MFIS is a self-reported questionnaire, assessing the level of symptomatic fatigue in the MS study groups. It consists of 21-item questionnaire tasks describing the effects of fatigue within physical (9-items), psychosocial (2-items) and cognitive (10-items) domains over a period of last month. Patients rated the 21 items on a 5-point Likert-type scale, ranging from never (0 points) to almost always (4 points). The overall score ranges from 0 to 84, and the higher the scores are, the higher the levels of fatigue are indicated. The MFIS evaluates the impact of fatigue on three dimensions of quality of life: physical, cognitive and psychosocial. Previous studies have reported that a total score of 38 demarcates fatigued from non-fatigued individuals (16, 17).
Head magnetic resonance imaging (MRI) was performed in all MS patients at the beginning of the study. The 1,5T scanner imaging (General Electric HDx USA) and standard head protocol for MS patients (multiple planes, slice thickness 5 mm, contrast media: Gadovist (Gd)) and additional postcontrast 3DT1 sequences (1 mm slice thickness) was used. Supratentorial, infratentorial and number of enhancing T1 plaques were evaluated.
The results were expressed as means ± S.E.M. The Kolmogorov-Smirnov test was used for normal data distribution. Comparisons between groups were performed using the Mann-Whitney U-test and Wilcoxon test. Differences between means were considered statistically significant at P < 0.05. Correlations were calculated using Spearman’s test. Results were statistically analyzed using STATISTICA v. 8.0 (StatSoft, Poland).
Demographic and clinical characteristics of studied subjects were presented in Table 1.
Results from our study show that LHP concentrations were significantly higher in all studied MS groups vs. controls (6.72 ± 3.26, P = 0.002; 11.6 ± 3.84; P = 0.006, 9.71 ± 3.49, P = 0.000003 versus 1.7 ± 1.9 µmol/L, in RRMS pretreated, RRMS INF-beta and SP/PP MS Mitoxantrone groups, respectively). In all MS patient groups melatonin application resulted in significant decrease in plasma LHP concentrations (Fig. 1). In RRMS relapse group plasma LHP concentrations were inconsistent and difficult to interpret (data not shown).
|Fig. 1. Plasma lipid hydroxyperoxides (LHP) concentration (µmol/L) in control group (C), immunomodifying pretreated relapsing-remitting MS group (RRMS pretreated), interferons beta treated relapsing-remitting MS group (RRMS INF-beta), mitoxantrone treated secondary progressive/primary progressive MS group (SP/PP MS Mitoxantrone) before and after three months of melatonin treatment (+ Mel). Data presented as mean ± S.D.; * P < 0.05 vs. control group; # P < 0.05 vs. before Mel; •P < 0.05 vs. RRMS pretreated.|
Plasma homocysteine concentration was similar in healthy people, RRMS pretreated, RRMS INF-beta and SP/PP MS Mitoxantrone groups (10.01 ± 1.55, 9.96 ± 2.76, 10.35 ± 3.23, 9.26 ± 2.12 µmol/L, P > 0.05, respectively). However, in the RRMS relapse group plasma levels of homocysteine were significantly higher compared to the RRMS pretreated group (12.03 ± 2.05 versus 9.96 ± 2.73 µmol/L, P = 0.02) and statistically higher compared to the control group (12.03 ± 2.05 versus 10.01 ± 1.55 µmol/L, P = 0.02) (Fig. 2). There were no significant differences in plasma homocysteine concentration in the studied groups before and after melatonin application.
|Fig. 2. Plasma homocysteine concentration (µmol/L) in control group (C), immunomodifying pretreated relapsing-remitting MS group (RRMS pretreated), interferons beta treated relapsing-remitting MS group (RRMS INF-beta), mitoxantrone treated secondary progressive/primary progressive MS group (SP/PP MS Mitoxantrone) before and after three months of melatonin treatment (+ Mel) and during relapse in relapsing-remitting MS group (RRMS relapse). Data presented as mean ± S.D.; * P < 0.05 vs. control group; •P < 0.05 vs. RRMS pretreated.|
The degree of fatigue presented as MFIS score was significantly lower in RRMS pretreated group compared to RRMS INF-beta and SP/PP MS mitoxantrone treated patients (27.30 ± 12.31 versus 36.87 ± 15.94 and 49.77 ± 13.42 points, respectively). No statistical changes were found in the studied groups after melatonin treatment (Fig. 3). MFIS score was not evaluated during relapses in RRMS relapse group from obvious reasons.
|Fig. 3. Modified Fatigue Impact Scale (MFIS) score in immunomodifying pretreated relapsing-remitting MS group (RRMS pretreated), interferons beta treated relapsing-remitting MS group (RRMS INF-beta), mitoxantrone treated secondary progressive/primary progressive MS group (SP/PP MS Mitoxantrone) before and after three months of melatonin treatment (+ Mel). Data presented as mean ± S.D.; •P < 0.05 vs. RRMS pretreated; # P < 0.05 vs. RRMS INF-beta.|
We found no correlations between serum LHP concentration, plasma homocysteine level, MFIS score, MRI changes and EDSS.
Results from our study suggest that all MS patient both immunomodifying untreated and receiving interferons beta or mitoxantrone have significantly higher plasma lipid hydroxyperoxides levels compared to healthy subjects. Similarly, our previous papers documented that lipid peroxidation marker malodialdehyde concentration in serum and the cerebrospinal fluid are significantly higher in MS patients, in both de novo diagnosed RRMS and in the worsening MS form than in the controls (44, 45). Moreover, other studies reported a significant increase in lipid peroxidation products in the plasma, brain and cerebrospinal fluid in MS patients (46, 47). It is known that oxidative stress products, including lipid peroxidation products are neurotoxic, have proinflammatory properties, and could be involved in demyelination and axonal injury in MS (46). In our present study melatonin supplementation caused a significant decrease in plasma lipid hydroxyperoxides levels in all MS patients, arguing for melatonin’s strong antioxidative properties and its beneficial, protective effects in MS subjects. Antioxidative properties of melatonin are well-documented. This indolamine could act indirectly by stimulating antioxidative enzymes, enhancing the activities of other antioxidants, and directly inactivating reactive oxidant species (23, 44, 45). Increase in plasma LHP levels in immunomodifying drugs - interferons and mitoxantrone results from oxidative stress mechanisms presence in this disease what could be confirmed by LHP increase in RRMS pretreated group. Moreover, disease duration period could be connected with LHP level increase in interferons and mitoxantrone group. Furthermore, oxidative stress marker LHP could reflects inflammatory MS phase during RRMS, but not progressive forms what could be confirmed by active (Gd+) brain MRI lesions in RRMS versus SP/PP MS group.
Previously, it was reported that lipid peroxidation is elevated in females with chronic fatigue syndrome (36). Moreover, it was proved that myalgic encephalomyelitis/chronic fatigue syndrome is characterized by increased oxidative stress through plasma peroxide concentrations elevation (37). These observations show increased ROS and oxidative stress in myalgic encephalomyelitis/chronic fatigue syndrome. Additional papers presented that myalgic encephalomyelitis/chronic fatigue syndrome is accompanied by lowered antioxidant serum/plasma levels like zinc, coenzyme-Q10 and vitamin E (48-50). In our study we noticed higher plasma lipid hydroxyperoxides levels and high fatigue level in MS patients compared to controls, but these values did not correlate with the fatigue score.
Fatigue is one of the most annoying symptoms reported by MS-affected people. There are several scales designed to estimate fatigue in MS, but it still seems to be difficult and too subjective to evaluate (16, 17). Many of the instruments have been developed as the ‘golden standard’ and the final choice depends on the aim of the research. According to our needs we used the MFIS tool. The results of our study present higher fatigue scores in immunomodifying MS patients than in immunomodifying pretreated group, but the highest fatigue scores were observed in the mitoxantrone administered SP/PP MS group. In other research conducted on a Polish group of MS patients the fatigue mean score was higher, than in the control group (51). It was in accordance with the MS patients’ results obtained by Jamroz-Wisniewska et al. (52). Performed by Gruszczak et al., a Polish validation of the MFIS evaluated a fatigue mean score in general as 40.71 ± 14.94 (15). Flachenecker et al. reported a Fatigue Severity Scale (FSS) and MFIS as the most discriminative scales for fatigue (53). Results of the mentioned publications indicated a higher level of fatigue among MS-affected patients, than in control group, which confirms the findings of authors from other countries (54, 55). Significantly higher FSS scores occurred in patients with progressive MS, than in those with relapsing-remitting MS with median levels of 6.0 (4.8 – 6.6) and 4.9 (3.8 – 6.1), respectively (53). A similar connection was also confirmed by Kroencke et al. (56) and Bergamaschi et al. (57), while Pittion-Vouyovitch et al. showed that fatigue occurred independently of clinical forms of MS (58). In our research we reported that the highest fatigue score concern progressive forms of MS (SP/PPMS). It is probably associated not with direct drug effects, but with long disease duration and higher EDSS score in these patients. In our study there were no significant differences in mean MFIS scores in the studied groups before and after melatonin therapy.
Pathophysiology of chronic fatigue syndrome is completely unknown. Some previous papers documented that myalgic encephalomyelitis/chronic fatigue syndrome is characterized by activation of immune, inflammatory, oxidative and nitrosative stress mechanisms (34, 35).
Chronic fatigue syndrome is characterized by intense fatigue not improving by rest, neurocognitive dysfunction and poor exercise tolerance. Very frequent symptoms are muscle pain, as well as sleep and cognitive disturbances. Chronic fatigue syndrome occurs in about 80 – 90% of MS patients (1, 8, 9, 11, 12). It can be present at any stage of the disease and it affects many aspects of life, such as social functioning, employment, driving safety, physical independence, rehabilitation gains, disease management, treatment adherence, mood, and finally, a reduced quality of life (8, 9, 13). It was reported that melatonin supplementation improve mood, sleep and body mass in postmenopausal women with increased appetite (45, 59).
In our work we reported similar homocysteine levels in all MS patients groups compared to controls. Interestingly, we observed significantly higher homocysteine levels in the relapse MS group. This data suggests that homocysteine could be a potential marker of acute phase of MS. Recent studies showed elevated levels of homocysteine observed in patients with MS (60, 61). On the other hand, unchanged homocysteine levels in MS patients compared to controls were also reported (38). Homocysteine causes production of free radicals and hydrogen peroxide and, interestingly, this could conceivably lead to increased plasma lipid hydroperoxides levels (39). Mental fatigue loading in humans leads to a decrease in blood levels of branched-chain amino acids inter alia homocysteine precursor - methionine (40). Neurons could be susceptible to homocysteine-induced excitotoxicity. Elevated homocysteine levels compromise methionine availability, which in turn interferes with methyl group donor. Myelin protein hypomethylation could result in less stable myelin structure susceptible to neurodegeneration (60, 61). Homocysteine as an aliphatic sulfhydryl compound could cause lipid peroxidation thanks to the ability to reduce atmospheric oxygen to hydrogen peroxide. Elevated plasma homocysteine level associated with increased plasma lipid hydroperoxides might trigger proliferation of smooth-muscle cells, promote oxidation of low-density lipoprotein, increase collagen synthesis and procoagulant activity, leading to development of vascular disease (39, 62).
Many studies have proved that melatonin and its’ precursors act in immune response modulating, but specified mechanism of it is still unknown (63-65). This pineal hormone can have either suppressing or activating immune response, because it regulates Th1/Th2 balance (20, 21). Finally, interferons as well as melatonin are immunomodulators. Dysregulated melatonin secretion in MS patients may be influenced by interferons b. Even many years of interferons beta presence in MS treatment detailed mechanisms of their therapeutic actions are still unknown. It has been reported that interferons beta, has potential modulatory effects on costimulatory molecules present on dendritic and other cells, decreases antigen presentation, suppresses proliferation of the Th1 cells, increases expression of anti-inflammatory IL-10, change the inflammatory environment from proinflammatory to anti-inflammatory (66). Melamud et al. showed significantly decreased levels of melatonin secretion in MS and disrupted circadian clock, which were increased after interferons β therapy in relationship with improved fatigue (31). Moreover, other effective MS drug natalizumab caused an increase in serum melatonin concentrations in RRMS patients confirming the role of this monoclonal antibody in increase of antioxidants and a reduction in oxidative stress biomarkers (67).
Taking into account the hypothesis that serum/plasma lipid hydroxyperoxides and homocysteine concentrations could be potential biochemical chronic fatigue syndrome biomarkers we reported only increased plasma lipid hydroxyperoxides levels in all MS patients. What is important is that we noticed for the first time that plasma homocysteine level was elevated in the relapse patient group, suggesting that homocysteine could be a potential marker of acute phase of MS. Based on the decreased serum/plasma lipid hydroxyperoxides after melatonin supplementation, we proved it antioxidative actions in MS patients. On the other hand, melatonin had no effect on the serum/plasma levels of homocysteine and also on fatigue assessed by MFIS. Results from our study indicate that melatonin supplementation could be potentially beneficial in MS patients. This issue of melatonin is intriguing one which could be further explored in. Also, additional studies to test the biomarkers of chronic fatigue syndrome are required.
Conflict of interest: None declared.
- Ramagopalan SV, Sadovnick AD. Epidemiology of multiple sclerosis. Neurol Clin 2011; 29: 207-217.
- Olazaran J, Cruz I, Benito-Leon J, Morales JM, Duque P, Rivera-Navarro J. Cognitive dysfunction in multiple sclerosis: methods and prevalence from the GEDMA Study. Eur Neurol 2009; 61: 87-93.
- Chiaravalloti ND, DeLuca J. Cognitive impairment in multiple sclerosis. Lancet Neurol 2008; 7: 1139-1151.
- Hoang H, Laursen B, Stenager EN, Stenager E. Psychiatric co-morbidity in multiple sclerosis: the risk of depression and anxiety before and after MS diagnosis. Mult Scler 2015; Jun 3. pii:1352458515588973.
- Tallner A, Waschbisch A, Hentschke C, Pfeifer K, Maurer M. Mental health in multiple sclerosis patients without limitation of physical function: the role of physical activity. Int J Mol Sci 2015; 16: 14901-14911.
- Akaishi T, Nakashima I, Misu T, Fujihara K, Aoki M. Depressive state and chronic fatigue in multiple sclerosis and neuromyelitis optica. J Neuroimmunol 2015; 283: 70-73.
- Kunkel A, Fischer M, Faiss J, Dahne D, Kohler W, Faiss JH. Impact of natalizumab treatment on fatigue, mood, and aspects of cognition in relapsing-remitting multiple sclerosis. Front Neurol 2015; 6: 97. doi: 10.3389/fneur.2015.00097.
- Hourihan SJ. Managing fatigue in adults with multiple sclerosis. Nurs Stand 2015; 29: 51-58.
- Lukoschek C, Sterr A, Claros-Salinas D, Gutler R, Dettmers C. Fatigue in multiple sclerosis compared to stroke. Front Neurol 2015; 6: 116. doi: 10.3389/fneur.2015.00116.
- Wilting J, Rolfsnes HO, Zimmermann H, et al. Structural correlates for fatigue in early relapsing remitting multiple sclerosis. Eur Radiol 2016; 26: 515-523.
- Stanton BR, Barnes F, Silber E. Sleep and fatigue in multiple sclerosis. Mult Scler 2006; 12: 481-486.
- Morris G, Berk M, Walder K, Maes M. Central pathways causing fatigue in neuro-inflammatory and autoimmune illnesses. BMC Med 2015; 13: 28. doi: 10.1186/s12916-014-0259-2.
- Fernandez-Munoz JJ, Moron-Verdasco A, Cigaran-Mendez M, Munoz-Hellin E, Perez-de-Heredia-Torres M, Fernandez-de-Las-Penas C. Disability, quality of life, personality, cognitive and psychological variables associated with fatigue in patients with multiple sclerosis. Acta Neurol Scand 2015; 132: 118-124.
- Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. The chronic fatigue syndrome: a comprehensive approach to its definition and study. International Chronic Fatigue Syndrome Study Group. Ann Intern Med 1994; 121: 953-959.
- Gruszczak A, Bartosik-Psujek H, Pocinska K, Stelmasiak Z. Validation analysis of selected psychometric features of Polish version of Modified Fatigue Impact Scale-preliminary findings. Neurol Neurochir Pol 2009; 43: 148-54.
- Kos D, Kerckhofs E, Carrea I, Verza R, Ramos M, Jansa J. Evaluation of the modified fatigue impact scale in four different European countries. Mult Scler 2005; 11: 76-80.
- Tellez N, Rio J, Tintore M, Nos C, Galan I, Montalban X. Does the modified fatigue impact scale offer a more comprehensive assessment of fatigue in MS? Mult Scler 2005; 11: 198-202.
- Mehta BK. New hypotheses on sunlight and the geographic variability of multiple sclerosis prevalence. J Neurol Sci 2010; 292: 5-10.
- Golan D, Staun-Ram E, Glass-Marmor L, et al. The influence of vitamin D supplementation on melatonin status in patients with multiple sclerosis. Brain Behav Immun 2013; 32: 180-185.
- Carrillo-Vico A, Lardone PJ, Alvarez-Sanchez N, Rodriguez-Rodriguez A, Guerrero JM. Melatonin: buffering the immune system. Int J Mol Sci 2013; 14: 8638-8683.
- Calvo JR, Gonzalez-Yanes C, Maldonado MD. The role of melatonin in the cells of the innate immunity: a review. J Pineal Res 2013; 55: 103-120.
- Reiter RJ, Tan DX, Manchester LC, Pilar Terron M, Flores LJ, Koppisepi S. Medical implications of melatonin: receptor-mediated and receptor independent actions. Adv Med Sci 2007; 52: 11-28.
- Cuzzocrea S. Antiinflammatory activity of melatonin in central nervous system. Curr Neuropharmacol 2010; 8: 228-242.
- Korkmaz A, Reiter RJ, Topal T, Manchester LC, Oter S, Tan DX. Melatonin: an established antioxidant worthy of use in clinical trials. Mol Med 2009; 15: 43-50.
- Kostoglou-Athanassiou I. Therapeutic applications of melatonin. Ther Adv Endocrinol Metab 2013; 4: 13-24.
- Aranami T, Yamamura T. Th17 Cells and autoimmune encephalomyelitis (EAE/MS). Allergol Int 2008; 57: 115-120.
- Lin GJ, Huang SH, Chen SJ, Wang CH, Chang DM, Sytwu HK. Modulation by melatonin of the pathogenesis of inflammatory autoimmune diseases. Int J Mol Sci 2013; 14: 11742-11766.
- Arushanian EB. Melatonin treatment of autoimmune and allergic pathology [article in Russian]. Eksp Klin Farmakol 2015; 78: 29-34.
- Kashani IR, Rajabi Z, Akbari M, et al. Protective effects of melatonin against mitochondrial injury in a mouse model of multiple sclerosis. Exp Brain Res 2014; 232: 2835-2846.
- Farez MF, Mascanfroni ID, Mendez-Huergo SP et al. Melatonin contributes to the seasonality of multiple sclerosis relapses. Cell 2015; 162: 1338-1352.
- Melamud L, Golan D, Luboshitzky R, Lavi I, Miller A. Melatonin dysregulation, sleep disturbances and fatigue in multiple sclerosis. J Neurol Sci 2012; 314: 37-40.
- Lopez-Gonzalez A, Alvarez-Sanchez N, Lardone PJ, et al. Melatonin treatment improves primary progressive multiple sclerosis: a case report. J Pineal Res 2015; 58: 173-177. doi: 10.1111/jpi.12203.
- Gilgun-Sherki Y, Melamed E, Offen D. The role of oxidative stress in the pathogenesis of multiple sclerosis: the need for effective antioxidant therapy. J Neurol 2004; 251: 261-268.
- Maes M. Inflammatory and oxidative and nitrosative stress pathways underpinning chronic fatigue, somatization and psychosomatic symptoms. Curr Opin Psychiatry 2009; 22: 75-83.
- Maes M, Twisk FN. Chronic fatigue syndrome: Harvey and Wessely’s (bio)psychosocial model versus a bio (psychosocial) model based on inflammatory and oxidative and nitrosative stress pathways. BMC Medicine 2010; 8: 35. doi: 10.1186/1741-7015-8-35.
- Brkic S, Tomic S, Maric D, Novakov Mikic A, Turkulov V. Lipid peroxidation is elevated in female patients with chronic fatigue syndrome. Med Sci Monit 2010; 16: CR628-CR632.
- Maes M, Kubera M, Uytterhoeven M, Vrydags N, Bosmans E. Increased plasma peroxides as a marker of oxidative stress in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Med Sci Monit 2011; 17: SC11-SC15.
- Ansari R, Mahta A, Mallack E, Luo JJ. Hyperhomo-cysteinemia and neurologic disorders: a review. J Clin Neurol 2014; 10: 281-288.
- Dudman NP, Wilcken DE, Stocker R. Circulating lipid hydroperoxide levels in human hyperhomocysteinemia. Relevance to development of arteriosclerosis. Arterioscler Thromb 1993; 13: 512-516.
- Mizuno K, Tanaka M, Nozaki S, et al. Mental fatigue-induced decrease in levels of several plasma amino acids. J Neural Transm 2007; 114: 555-561.
- Polman CH, Reingold SC, Edan G, et al. Diagnostic criteria for multiple sclerosis: 2005 revisions to the “McDonald Criteria”. Ann Neurol 2005; 58: 840-846.
- Kurtzke JF. Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS). Neurology 1983; 33: 1444-1452.
- Sodergren E, Nourooz-Zadeh J, Berglund L, Vessby B. Re-evaluation of the ferrous oxidation in xylenol orange assay for the measurement of plasma lipid hydroperoxides. J Biochem Biophys Methods 1998; 37: 137-146.
- Adamczyk-Sowa M, Sowa P, Pierzchala K, Polaniak R, Labuz-Roszak B. Antioxidative enzymes activity and malondialdehyde concentration during mitoxantrone therapy in multiple sclerosis patients. J Physiol Pharmacol 2012; 63: 683-690.
- Adamczyk-Sowa M, Pierzchala K, Sowa P, Polaniak R, Kukla M, Hartel M. Influence of melatonin supplementation on serum antioxidative properties and impact of the quality of life in multiple sclerosis patients. J Physiol Pharmacol 2014; 65: 543-550.
- Ferretti G, Bacchetti T. Peroxidation of lipoproteins in multiple sclerosis. J Neurol Sci 2011; 311: 92-97.
- Davitashvili D, Beridze M, Shakarishvili R, Kiziria M, Sanikidze T. The role of endogenous antiradical protective system in multiple sclerosis. Georgian Med News 2012; 205: 11-19.
- Maes M, Mihaylova I, Kubera M, et al. Coenzyme Q10 deficiency in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is related to fatigue, autonomic and neurocognitive symptoms and is another risk factor explaining the early mortality in ME/CFS due to cardiovascular disorder. Neuro Endocrinol Lett 2009; 30: 462-469.
- Miwa K, Fujita M. Increased oxidative stress suggested by low serum vitamin E concentrations in patients with chronic fatigue syndrome. Int J Cardiol 2009; 136: 238-239.
- Maes M, Mihaylova I, De Ruyter M. Lower serum zinc in chronic fatigue syndrome (CFS): relationships to immune dysfunctions and relevance for the oxidative stress status in CFS. J Affect Disord 2006; 90: 141-147.
- Papuc E, Stelmasiak Z. Factors predicting quality of life in a group of Polish subjects with multiple sclerosis: accounting for functional state, socio-demographic and clinical factors. Clinical Neurol Neurosurg 2012; 114: 341-346.
- Jamroz-Wisniewska A, Papuc E, Bartosik-Psujek H, Belniak E, Mitosek-Szewczyk K, Stelmasiak Z. Validation of selected aspects of psychometry of the Polish version of the multiple sclerosis impact scale 29 (MSIS-29) [article in Polish]. Neurol Neurochir Pol 2007; 41: 215-222.
- Flachenecker P, Kumpfel T, Kallmann B, et al. Fatigue in multiple sclerosis: A comparison of different rating scales and correlation to clinical parameters. Mult Scler 2002; 8: 523-526.
- Niino M, Mifune N, Kohriyama T, et al. Apathy/depression, but not subjective fatigue, is related with cognitive dysfunction in patients with multiple sclerosis. BMC Neurol 2014; 14: 3. doi: 10.1186/1471-2377-14-3.
- Ghajarzadeh M, Jalilian R, Eskandari G, Sahraian MA, Azimi A, Mohammadifar M. Fatigue in multiple sclerosis: Relationship with disease duration, physical disability, disease pattern, age and sex. Acta Neurol Belg 2013; 113: 411-414.
- Kroencke DC, Lynch SG, Denney DR. Fatigue in multiple sclerosis: relationship to depression, disability, and disease pattern. Mult Scler 2000; 6: 131-136.
- Bergamaschi R, Romani A, Versino M, Poli R, Cosi V. Clinical aspects of fatigue in multiple sclerosis. Funct Neurol 1997; 12: 247-251.
- Pittion-Vouyovitch S, Debouverie M, Guillemin F, Vandenberghe N, Anxionnat R, Vespignani H. Fatigue in multiple sclerosis is related to disability, depression and quality of life. J Neurol Sci 2006; 243: 39-45.
- Chojnacki C, Walecka-Kapica E, Klupinska G, Pawlowicz M, Blonska A, Chojnacki J. Effects of fluoxetine and melatonin on mood, sleep quality and body mass index in postmenopausal women. J Physiol Pharmacol 2015; 66: 665-671.
- Ho PI, Ortiz D, Rogers E, Shea TB. Multiple aspects of homocysteine neurotoxicity: glutamate excitotoxicity, kinase hyperactivation and DNA damage. J Neurosci Res 2002; 70: 694-702.
- Kruman II, Culmsee C, Chan SL, et al. Homocysteine elicits a DNA damage response in neurons that promotes apoptosis and hypersensitivity to excitotoxicity. J Neurosci 2000; 20: 6920-6926.
- Petras M, Tatarkova Z, Kovalska M, et al. Hyperhomocysteinemia as a risk factor for the neuronal system disorders. J Physiol Pharmacol 2014; 65: 15-23.
- Michalowska M, Znorko B, Kaminski T, Oksztulska-Kolanek E, Pawlak D. New insights into tryptophan and its metabolites in the regulation of bone metabolism. J Physiol Pharmacol 2015; 66: 779-791.
- Rajaratnam SM, Arendt J. Health in a 24-h society. Lancet 2001; 358(9286): 999-1005.
- Radogna F, Diederich M, Ghibelli L, et al. Melatonin: a pleiotropic molecule regulating inflammation. Biochem Pharmacol 2010; 80: 1844-1852.
- Minagar A. Current and future therapies for multiple sclerosis. Scientifica (Cairo). 2013; 2013: 249101. doi: 10.1155/2013/249101.
- Bahamonde C, Conde C, Aguera E, et al. Elevated melatonin levels in natalizumab-treated female patients with relapsing-remitting multiple sclerosis: relationship to oxidative stress. Eur J Pharmacol 2014; 730: 26-30.
A c c e p t e d : February 19, 2016