Ultra-High Performance Liquid Chromatography Method for Bioanalysis of Fampridine Using Dried Blood Spot (DBS) Methodology: Application to Pharmacokinetic Study in Albino Rats

Fampridine (dalfampridine) is used to improve walking in people who have multiple sclerosis (a disease in which the nerves do not function properly and may cause weakness, numbness, loss of muscle coordination and problems with vision, speech and bladder control). Measurement of fampridine plasma concentrations is not practical at sites lacking the facilities to prepare and process blood samples. A dried blood spot (DBS) sampling method, in which a few drops of blood, drawn by lancet from the finger, are applied onto specially manufactured absorbent filter paper, can be used as an alternative to plasma monitoring and would allow for simplified sample storage and transport. Using blood samples from pharmacokinetic studies, an ultra-high performance liquid chromatography assay method for quantification of fampridine in DBS is developed and validated for specificity, selectivity, accuracy, precision, reproducibility and stability. Method was specific and selective relative to endogenous compounds, with required process efficiency, and no matrix effect. Inaccuracy and precision for intra-day and inter-day analyses were tested at all concentrations. Quantification of fampridine in DBS assay was not affected by blood deposit volume and punch position within spot, and hematocrit level had a limited but acceptable effect on measurement accuracy. Fampridine was stable for at least 2 months at room temperature. The correlation between DBS and plasma concentrations with an average blood-to-plasma ratio is determined. DBS sampling is a simple and practical method for monitoring fampridine concentrations. The method is completely validated as per ICH guidelines and extended to the in vivo determination of fampridine in male albino rats.

Mood Symptoms and Chronic Fatigue Syndrome Due to Relapsing-Remitting Multiple Sclerosis Are Associated with Immune Activation and Aberrations in the Erythron

BACKGROUND

Multiple sclerosis (MS) is a chronic autoimmune and neuroinflammatory disease of the central nervous system characterized by peripheral activation of immune-inflammatory pathways which culminate in neurotoxicity causing demyelination of central neurons. Nonetheless, the pathophysiology of relapsing-remitting MS (RRMS)-related chronic fatigue, depression, anxiety, cognitive impairments, and autonomic disturbances is not well understood.

OBJECTIVES

The current study aims to delineate whether the remitted phase of RRMS is accompanied by activated immune-inflammatory pathways and if the latter, coupled with erythron variables, explain the chronic fatigue and mood symptoms due to RRMS.

MATERIAL AND METHODS

We recruited 63 MS patients, 55 in the remitted phase of RRMS and 8 with secondary progressive MS, and 30 healthy controls and assessed erythron variables, and used a bio-plex assay to measure 27 serum cytokines.

RESULTS

A significant proportion of the MS patients (46%) displayed activation of the immune-inflammatory response (IRS) and compensatory immune response (CIRS) systems, and T helper (Th)1 and Th17 cytokine profiles. Remitted RRMS patients showed increased chronic fatigue, depression, anxiety, physiosomatic, autonomic, and insomnia scores, which could partly be explained by M1 macrophage, Th1, Th-17, growth factor, and CIRS activation, as well as aberrations in the erythron including lowered hematocrit and hemoglobin levels.

CONCLUSIONS

Around 50% of remitted RRMS patients show activation of immune-inflammatory pathways in association with mood and chronic-fatigue-like symptoms. IRS and CIRS activation as well as the aberrations in the erythron are new drug targets to treat chronic fatigue and affective symptoms due to MS.

Interferon-β Decreases the Hypermetabolic State of Red Blood Cells from Patients with Multiple Sclerosis

Multiple sclerosis (MS) is an inflammatory disease characterized by damage to the myelin sheath surrounding axons in the central nervous system. While the exact mechanism of this destruction is unknown, excess nitric oxide (NO) and adenosine triphosphate (ATP) have been measured in tissues and fluids obtained from people with MS. Here, incubation of interferon-beta (IFN-β), an MS drug with an unknown mechanism of action, with red blood cells (RBCs) obtained from people with MS provide evidence of a potential hypermetabolic state in the MS RBC that is decreased with IFN-β intervention. Specifically, binding of all three components of an albumin/C-peptide/Zn²⁺ complex to MS RBCs was significantly increased in comparison to control RBCs. For example, the binding of C-peptide to MS RBCs was significantly increased (3.4 ± 0.1 nM) compared to control RBCs (1.6 ± 0.2 nM). However, C-peptide binding to MS RBCs was reduced to a value (1.6 ± 0.3 nM) statistically equal to that of control RBCs in the presence of 2 nM IFN-β. Similar trends were measured for albumin and Zn²⁺ binding to RBCs when in the presence of IFN-β. RBC function was also affected by incubation of cells with IFN-β. Specifically, RBC-derived ATP and measurable membrane GLUT1 were both significantly decreased (56 and 24%, respectively) in the presence of IFN-β. Collectively, our results suggest that IFN-β inhibits albumin binding to the RBC, thereby reducing its ability to deliver ligands such as C-peptide and Zn²⁺ to the cell and normalizing the basal hypermetabolic state.

Employing metabolomic approaches to determine the influence of age on experimental autoimmune encephalomyelitis (EAE)

The immune system plays a critical role not only in homeostasis of the body but also in pathogenesis. Autoimmunity and dysregulation of the immune balance are closely related to age. To examine the influence of age on autoimmunity, the pathophysiological features of experimental autoimmune encephalomyelitis (EAE) induced at different ages were elucidated on the basis of plasma-level metabolic changes. In the present study, female 6 week-old (6 W) and 15 month-old (15 M) C57BL/6 mice were immunized for EAE induction. The plasma and tissue samples were collected to determine the phenotypic characteristics. The activity of NADPH oxidase in plasma and the IL-6 concentrations in the brain and spinal cord were higher in both EAE groups compared to those in the control groups as well as in the 15 M EAE (15 M-E) group compared to those in the 6 W EAE (6 W-E) group. The metabolomic profiles related to characteristics of EAE were characterized by the biosynthesis of unsaturated fatty acids and the metabolism of tryptophan, tyrosine and sphingolipid. The reduced availability of unsaturated fatty acids and perturbations in tryptophan metabolism were high risk factors for EAE development regardless of age. The changes in tyrosine metabolism and sphingolipid metabolites were more dramatic in the 15 M-E group. From these findings, it can be concluded that changes in unsaturated fatty acid and tryptophan metabolism contributed to the development of EAE, whereas changes in sphingolipid and tyrosine metabolism, which corresponded to age, were additional risk factors that influenced the incidence and severity of EAE.

An overview of lipidomic analysis in different human matrices of multiple sclerosis

Multiple sclerosis is a chronic inflammatory and neurodegenerative disease of the central nervous system, and it is one of the most common neurological cause of disability in young adults. It is known that several factors contribute to increase the risk of development and pathogenesis of multiple sclerosis, nonetheless, but the true etiology of this pathology remains unknown. Similar to other inflammatory diseases, oxidative stress and lipid peroxidation are also associated to multiple sclerosis. Alterations in the lipid profile seem to be a hallmark of this pathology which can contribute to the dysregulation of lipid homeostasis and lipid metabolism in multiple sclerosis. Lipidomic studies analysed in this review clearly demonstrate the role of lipids in inflammatory processes, in immunity, and in the onset and development of multiple sclerosis. Several investigations reported alterations of some molecular lipid species, in particular, with decrease of fatty acids (FA) 18:2 and 20:4 and total polyunsaturated FA, with compensatory increases of saturated FA with shorter carbon chains. Oxidized phospholipids were reported in few studies as well. Also, it was shown that clinical lipidomics has potential as a tool to aid both in multiple sclerosis diagnosis and therapeutics by allowing a detailed lipidome profiling of the patients suffering with this disease.

[Anemia and dysregulation of iron metabolism in multiple sclerosis]

Anemia is one of the common diseases comorbid with multiple sclerosis (MS). This article reviews the prevalence and types of anemia in MS patients. It has been shown that anemia is often accompanied by a decrease in serum iron level. The authors present the data on iron metabolism in patients with MS and MRI findings concerning deposits of iron in the gray matter of the brain. The causal relationship between abnormalities in iron metabolism and MS remains unclear; this study allows to approach the understanding of the MS pathogenesis and to increase the efficacy of therapy for this disease.

Dried Blood Spot Methodology in Combination With Liquid Chromatography/Tandem Mass Spectrometry Facilitates the Monitoring of Teriflunomide

Background:

Teriflunomide, a once-daily oral immunomodulator approved for treatment of relapsing-remitting multiple sclerosis, is eliminated slowly from plasma. If necessary to rapidly lower plasma concentrations of teriflunomide, an accelerated elimination procedure using cholestyramine or activated charcoal may be used. The current bioanalytical assay for determination of plasma teriflunomide concentration requires laboratory facilities for blood centrifugation and plasma storage. An alternative method, with potential for greater convenience, is dried blood spot (DBS) methodology. Analytical and clinical validations are required to switch from plasma to DBS (finger-prick sampling) methodology.

Methods:

Using blood samples from healthy subjects, an LC-MS/MS assay method for quantification of teriflunomide in DBS over a range of 0.01–10 mcg/mL was developed and validated for specificity, selectivity, accuracy, precision, reproducibility, and stability. Results were compared with those from the current plasma assay for determination of plasma teriflunomide concentration.

Results:

Method was specific and selective relative to endogenous compounds, with process efficiency ∼88%, and no matrix effect. Inaccuracy and imprecision for intraday and interday analyses were <15% at all concentrations tested. Quantification of teriflunomide in DBS assay was not affected by blood deposit volume and punch position within spot, and hematocrit level had a limited but acceptable effect on measurement accuracy. Teriflunomide was stable for at least 4 months at room temperature, and for at least 24 hours at 37°C with and without 95% relative humidity, to cover sampling, drying, and shipment conditions in the field. The correlation between DBS and plasma concentrations (R² = 0.97), with an average blood to plasma ratio of 0.59, was concentration independent and constant over time.

Conclusions:

DBS sampling is a simple and practical method for monitoring teriflunomide concentrations.

Understanding a role for hypoxia in lesion formation and location in the deep and periventricular white matter in small vessel disease and multiple sclerosis

The deep and periventricular white matter is preferentially affected in several neurological disorders, including cerebral small vessel disease (SVD) and multiple sclerosis (MS), suggesting that common pathogenic mechanisms may be involved in this injury. Here we consider the potential pathogenic role of tissue hypoxia in lesion development, arising partly from the vascular anatomy of the affected white matter. Specifically, these regions are supplied by a sparse vasculature fed by long, narrow end arteries/arterioles that are vulnerable to oxygen desaturation if perfusion is reduced (as in SVD, MS and diabetes) or if the surrounding tissue is hypoxic (as in MS, at least). The oxygen crisis is exacerbated by a local preponderance of veins, as these can become highly desaturated 'sinks' for oxygen that deplete it from surrounding tissues. Additional haemodynamic deficiencies, including sluggish flow and impaired vasomotor reactivity and vessel compliance, further exacerbate oxygen insufficiency. The cells most vulnerable to hypoxic damage, including oligodendrocytes, die first, resulting in demyelination. Indeed, in preclinical models, demyelination is prevented if adequate oxygenation is maintained by raising inspired oxygen concentrations. In agreement with this interpretation, there is a predilection of lesions for the anterior and occipital horns of the lateral ventricles, namely regions located at arterial watersheds, or border zones, known to be especially susceptible to hypoperfusion and hypoxia. Finally, mitochondrial dysfunction due to genetic causes, as occurs in leucodystrophies or due to free radical damage, as occurs in MS, will compound any energy insufficiency resulting from hypoxia. Viewing lesion formation from the standpoint of tissue oxygenation not only reveals that lesion distribution is partly predictable, but may also inform new therapeutic strategies.

Hemoglobins as new players in multiple sclerosis: metabolic and immune aspects

Basic science investigations and clinical observations in recent years indicate that hemoglobins (Hbs) may have important roles in the pathogenesis of multiple sclerosis (MS). These findings can be summarized as follows: 1- Erythrocyte fragility is higher in MS patients, the released free Hb damages blood-brain barrier, myelin basic protein and also triggers iron overload and inflammation. 2- Free Hb may further activate the inflammatory responses through Toll-like receptor 4 (TLR4), present on microglia and other innate immunocytes. 3- Hbs are expressed in neural cells including dopaminergic neurons. Also, several studies have demonstrated that Hbs are expressed in astrocytes and oligodendroglia. 4- Hb overexpression in neural cells upregulate mitochondrial complex I-V subunits. The comparison of the mitochondrial proteome between healthy and patients with MS revealed only four differentially expressed proteins including Hb β-chain. 5- Microarray analysis of 8300 genes in monocytes of twins with and without MS showed a difference in 25 genes that include genes encoding α- and β-globins as well. 6- β- and α-globin gene clusters reside at chromosomal regions 11p15.5 and 16p13.3, respectively. Whole genome screen (WGS) in Sardinian MS families using 327 markers revealed linkage in 3 regions including 11p15.5 loci. Further, 11p15.5 and 16p13.3 were part of the 17 regions identified in the WGS study of 136 sibling-pairs in Nordic countries analyzing 399 microsatellite markers. In the light of these findings, we propose that free Hb released from dying erythrocytes is detrimental. On the contrary, intracellular Hbs in neural cells are protective in MS. The genomic linkage findings can be explained by common haematologically-silent Hb variants that may lower the protective function of intracellular Hbs, and therefore, enhance the risk for MS. In the absence of such variants, aberrations in the translational and post-translational mechanisms controlling synthesis of neural Hbs may also enhance the vulnerability to MS. Alternatively, such genetic variants may perturb the metabolism of anti-inflammatory hemorphins produced via cleavage of Hbs.