**1.3 Clinical presentation of multiple sclerosis**

*An Overview and Management of Multiple Chronic Conditions*

EBV [4, 6].

**1.2 Diagnosis of multiple sclerosis**

behind anti-EBVNA IgG suggests that late adolescence exposure to EBV leads to infectious mononucleosis with significantly elevated IgG titers when compared to individuals who were exposed at a younger age [4, 5]. These titers in turn correlate to an increased risk of developing multiple sclerosis. One study done on this, "highhygiene" population found that individuals of the same age who were not infected with EBV had a 10-fold lower risk of developing multiple sclerosis when compared to their EBV infected counterparts [4]. The pathology linking EBV titers to the initiation of multiple sclerosis are not yet clear, however it may increase the risk for an autoimmune type response as was seen with Systemic Lupus Erythematous and

Several studies have shown a direct correlation between cigarette smoking and incidence of multiple sclerosis [4, 7–10]. There is some variability in the literature between gender and age groups. One study suggests cigarette smoking at a younger age (<26.4 years) is associated with a 50% increased risk that was alleviated in individuals who were older [8]. A Canadian study comparing gender and smoking history and found that 71.5% males diagnosed with multiple sclerosis had previously smoked compared to 63.6% of females [10]. Smoking has previously been defined in several pathologies including cancer, asthma, atherosclerosis and heart disease, but within multiple sclerosis, the mechanism is still not understood.

Genetic risk factors have come to the forefront of current research as some have been linked with modulation of the immune response. Initial studies linked loci of the Major Histocompatibility Complex (MHC) and Human Leukocyte Antigen (HLA) as contributing risk in the development and progression of multiple sclerosis [4, 11–14]. In particular, HLA-*DRB1 and DQB1* gene loci were thought to play a role in developing the inherent autoimmunity associated with the disease [11, 14–16].

In 2001, the McDonald criteria were created to streamline the diagnosis of multiple sclerosis even with its heterogeneous clinical presentation. The initial criteria introduced the utility of magnetic resonance imaging (MRI) and integration of multiple clinical symptoms while removing "clinically definite" and "possible multiple sclerosis" as alternatives [17]. Since 2001, 3 additional revisions have been made to the initial McDonald criteria: 2005, 2010 and 2017 [18–21]. Diagnosis of multiple sclerosis is now approached based on dissemination of time (temporal) and space. Dissemination in space is defined by either clinical presentation or MRI. Clinically, an individual must have symptoms which are distinct to different anatomical locations of the central nervous system. Usually, individuals present with optic neuritis or ocular symptoms and later acquire gait disturbances or peripheral weakness [18, 22]. On MRI, dissemination in space requires T2 evident lesions located in at least two distinct zones such as periventricular, infratentorial, juxtacortical or within the spinal cord [18, 22]. Dissemination in time requires the presence of a gadolinium-enhancing lesion on MRI, indicating an acute or active lesion, along with a non-enhancing lesion [18, 22]. The presence of a new lesion alone can meet the criteria if it is performed on a follow up scan. Essentially, dissemination in time seeks to distinguish multiple sclerosis symptomatology both typical and atypical from other neurological disorders which may share certain characteristics. As of McDonald 2010, CSF analysis is not required in order to make a definitive diagnosis [19–22]. Analysis of CSF typically presents with mildly elevated white blood cell count, protein, and IgG oligoclonal bands which are not typically seen in serum analysis [22]. IgG oligoclonal bands can be found in 90% of multiple sclerosis patients, but it may have a greater role in distinguishing individuals with clinically isolated syndrome (CIS) [20]. Some studies demonstrated that CSF

**72**

The disease course of multiple sclerosis is usually defined into four clinical subtypes: clinically isolated syndrome (CIS), relapsing-remitting multiple sclerosis, secondary progressive multiple sclerosis, and primary progressive multiple sclerosis. A majority of patients have a disease course defined by stages of relapses and remission which may later translate into the secondary progressive form [25]. Clinically, relapses are defined as distinct episodes of neurological dysfunction which can present as a wide array of symptoms including sensory defects of the limbs, visual loss, motor defects, gait disturbances, vertigo, heat sensitivity (Uhthoff phenomenon), Lhermitte sign and fatigue [22, 26]. However, multiple sclerosis can present atypically in younger individuals, making it difficult to diagnosis properly. The initial episodes are followed by periods of remission where the patient will fully or partially regain normal function and be deemed neurologically stable [27]. In the long term, as some individuals transition from the relapsingremitting form to secondary progressive, relapses no longer occur, yet patients will experience worsening neurological function [27]. After 10 years of disease, 50% of individuals with relapsing-remitting multiple sclerosis will convert to secondaryprogressive, whereas after 25 years of the disorder, more than 90% of the individuals have secondary progressive multiple sclerosis [14].

Prior to establishing criteria for dissemination in time and space, individuals may present with clinically isolated syndrome (CIS) or radiologically isolated syndrome (RIS). Clinically isolated syndrome is defined as a clinical episode resembling a multiple sclerosis attack, after which there is full or partial recovery of neurological function [14, 20, 27]. Studies have shown that individuals with CIS may have an increased rate of conversion to multiple sclerosis especially with the presence of CSF oligoclonal bands and gadolinium enhancing lesions on MRI [14, 18, 20]. Incidental findings of cerebral and spinal cord plaques without a clinical phenotype are defined as radiologically isolated syndrome (RIS). In a 5-year study of 451 patients with RIS, 34% of individuals developed a clinical event for which 9.6% were defined as primary progressive multiple sclerosis [28]. Interestingly, this study was able to strongly correlate the presence of cervical or thoracic spinal cord lesions with the first clinical event [28]. With this increase risk of progression to multiple sclerosis, the utility of disease-modifying therapies and longitudinal monitoring of CIS and RIS has become a priority for clinicians.

### **1.4 Inflammation in multiple sclerosis**

The direct cause of multiple sclerosis still eludes the scientific community; however, several hypotheses have emerged which have been utilized to develop disease-modifying therapies (DMTs) and alter the course of disease. Traditionally, multiple sclerosis has been considered a demyelinating disease of the white matter tracts leading to peripheral symptomatology with an underlying autoimmune cause. Recently, demyelination located in the cerebral cortex and deep gray matter has emerged as a marker of progressing neurological disability [13, 29, 30]. Damage seen to the CNS with infiltration of immune cells suggests the role of peripheral immune response leading to damage of the blood brain barrier prior to established demyelination. Peripheral inflammation in this case may be a result of a foreign

pathogen (virus), autoimmune activation, or a combination of multiple events. Malpass [31] characterized the term "outside-in" based on evidence of cortical inflammation originating in the subarachnoid space in multiple sclerosis patients which transitioned into the white matter [32]. This further strengthens the argument for modulation of the peripheral inflammatory response which is facilitating early multiple sclerosis disease through activation of CD4 T lymphocytes. Once within the CNS, regional activation of microglia, astrocytes and macrophages occurs through expression of cytokines and chemokines from infiltration of T lymphocytes [13, 29, 30, 33]. Activation of specific subsets of CD4 lymphocytes dictates which cytokines are released. Pro-inflammatory cytokines are expressed after direct activation of Th1 and Th17 cells, whereas anti-inflammatory cytokines are a product of Th2 and T-regulatory cells [34–36]. Histopathology of the CNS white matter plaques has shown an abundance of macrophages, CD8, CD4 T lymphocytes, and B lymphocytes [13, 29, 30, 35]. Over time, the prolonged inflammation and infiltration of T and B lymphocytes leads to a disruption of the axonal-glial interaction which results in an increase in gray matter atrophy and axonal loss with marked demyelination [13, 29]. During the remission phase following each flare, there is some evidence to suggest a possible role for regulatory T cells with the induction of Foxp3 [37]. It is possible that during remission, a baseline level of inflammation is present; however, the expression of specific phenotypes of T lymphocytes shifts toward anti-inflammatory/regulatory rather than pro-inflammatory mechanisms. Based on these observations, vitamin D has emerged as a potential homeopathic regulator of immune cell function [2, 3, 38].

### **1.5 Current disease-modifying therapies**

Currently, there is no definitive treatment for multiple sclerosis. Most approved therapies are focused on controlling peripheral inflammation and preventing migration across the blood brain barrier thereby reducing the incidence of acute flares [13, 30, 39, 40]. A majority of these therapies are administered orally, as an injection or through an infusion. With both invasive and non-invasive methods, side effects include increases in liver enzymes, injection site reactions, nausea, diarrhea, and most importantly, progressive multifocal leukoencephalopathy (PML) [39]. The primary therapies prescribed at our institution are Copaxone®, Gilenya®, and Tecfidera®. Copaxone®, glatiramer acetate is an immunomodulator that is FDA approved to reduce the frequency of relapses. Gilenya®, fingolimod, is also an immunomodulator that targets reduction in the number of relapses more than progression of disease. Tecfidera®, dimethyl fumarate, is a combination of fumaric acid esters that was originally approved for oral treatment of psoriasis. Because of the inconsistent or incomplete outcomes from treatment, as well as the evolving nature of the disorder, other biotherapies have been used as adjuvants.

### **1.6 Enkephalins as therapeutic treatment**

One alternative biotherapeutic is the use of low doses of naltrexone (LDN), an opioid receptor antagonist. LDN is often used as an adjuvant to disease-modifying therapy to target fatigue associated with either the disorder or the medication. LDN has a strong profile of safety and tolerability [41–44]. Pilot studies utilizing LDN demonstrated that MS patients had an improvement in peripheral spasticity and mental health composite scores without inducing any side effects [42, 45]. In a retrospective analysis which compared LDN patients with LDN plus Copaxone® patients, there was no significant difference between the groups with respect to MRI, complete blood count, liver enzymes and the 25-foot walk test [44].

**75**

understood.

*1.6.2 Clinical studies on LDN*

Crohn's disease [63] and fibromyalgia [64].

*1.6.3 Clinical studies on LDN and multiple sclerosis*

*Enkephalin Therapy Improves Relapsing-Remitting Multiple Sclerosis*

A number of published studies, clinical trials and anecdotal stories have supported the use of LDN as a beneficial therapy for multiple sclerosis [41–48]. The mechanism of action for this general antagonist is to block the interaction of Opioid

at the nuclear-associated receptor OGFr. In addition to being a neurotransmitter, OGF is an inhibitory growth factor that suppresses proliferation of cells, including T and B cells associated with autoimmune disorders. Naltrexone was initially developed to treat opioid use disorder and alcoholism at a dosing of 50 mg where it acts as an opioid receptor antagonist for mu, delta, and kappa opiate receptors. At a dosage less than 5 mg, LDN acts as a biotherapeutic and modulates the activity of endogenous enkephalins and endorphins [49, 50]. In the multiple sclerosis patient

to non-multiple sclerosis patients [51]. It is hypothesized that the reduction in serum levels of this inhibitory growth factor are unable to control the increase in T cell proliferation that occurs with immune-related flares. These T cells are the source of other pro-inflammatory cytokines that exacerbate the symptomatology of multiple sclerosis. The decreased serum levels of OGF appear to be compensated by

Animal studies have been used to study both the mechanisms of LDN, as well as to establish the role of LDN as a biotherapy in mice with experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. In these studies, mice were immunized with antigens against myelin proteins—either myelin oligodendrocyte glycoprotein 35–55 or proteolipid peptides 139–151. The key component in the mechanistic pathway is the duration of opioid receptor blockade. This work is detailed in animal studies [51–57]. LDN produces an intermittent blockade of OGFr preventing OGF from binding and thereby increasing cellular replication, similar to what is seen with high doses of Naltrexone (HDN) through a prolonged blockade of OGFr [49]. Conversely, after the blockade has subsided, within 4–6 h, there is over proliferation of endogenous OGF and OGFr and a resulting exaggerated expression

A newly discovered pathway involves the antagonism of Toll-like receptor 4 (TLR4) by LDN as means to reduce neuroinflammation or persistent pain [58, 59]. Specifically, activation of Toll-like receptor 4 (TLR4) initiates the release of inflammatory cytokines: interleukin 1 (IL-1), tumor necrosis factor α (TNFα), nitric oxide (NO), and interferon β (IFNβ) [48, 60]. Currently, the relationship of the Tolllike receptor pathway to pro-inflammatory cytokine activation is not completely

Several studies have been conducted to evaluate multiple sclerosis patients who are prescribed LDN. The use of enkephalins, particularly OGF, has been demonstrated to be safe and tolerable in Phase I and Phase II studies of pancreatic cancer [61, 62]. LDN is widely used for treatment of other autoimmune disorders including

Clinical trials using LDN for multiple sclerosis were conducted more than a decade ago, and most likely because it is widely used with no side-effects,

of p16 and p21 leading to promotion of cellular senescence [49].

]-enkephalin) from interacting

]-enkephalin (i.e., OGF) is reduced when compared

*DOI: http://dx.doi.org/10.5772/intechopen.91010*

population, endogenous [Met<sup>5</sup>

low dosages of naltrexone (LDN).

*1.6.1 Laboratory studies on LDN*

Growth Factor (OGF) (chemically termed [Met<sup>5</sup>

### *Enkephalin Therapy Improves Relapsing-Remitting Multiple Sclerosis DOI: http://dx.doi.org/10.5772/intechopen.91010*

A number of published studies, clinical trials and anecdotal stories have supported the use of LDN as a beneficial therapy for multiple sclerosis [41–48]. The mechanism of action for this general antagonist is to block the interaction of Opioid Growth Factor (OGF) (chemically termed [Met<sup>5</sup> ]-enkephalin) from interacting at the nuclear-associated receptor OGFr. In addition to being a neurotransmitter, OGF is an inhibitory growth factor that suppresses proliferation of cells, including T and B cells associated with autoimmune disorders. Naltrexone was initially developed to treat opioid use disorder and alcoholism at a dosing of 50 mg where it acts as an opioid receptor antagonist for mu, delta, and kappa opiate receptors. At a dosage less than 5 mg, LDN acts as a biotherapeutic and modulates the activity of endogenous enkephalins and endorphins [49, 50]. In the multiple sclerosis patient population, endogenous [Met<sup>5</sup> ]-enkephalin (i.e., OGF) is reduced when compared to non-multiple sclerosis patients [51]. It is hypothesized that the reduction in serum levels of this inhibitory growth factor are unable to control the increase in T cell proliferation that occurs with immune-related flares. These T cells are the source of other pro-inflammatory cytokines that exacerbate the symptomatology of multiple sclerosis. The decreased serum levels of OGF appear to be compensated by low dosages of naltrexone (LDN).

### *1.6.1 Laboratory studies on LDN*

*An Overview and Management of Multiple Chronic Conditions*

regulator of immune cell function [2, 3, 38].

**1.5 Current disease-modifying therapies**

**1.6 Enkephalins as therapeutic treatment**

pathogen (virus), autoimmune activation, or a combination of multiple events. Malpass [31] characterized the term "outside-in" based on evidence of cortical inflammation originating in the subarachnoid space in multiple sclerosis patients which transitioned into the white matter [32]. This further strengthens the argument for modulation of the peripheral inflammatory response which is facilitating early multiple sclerosis disease through activation of CD4 T lymphocytes. Once within the CNS, regional activation of microglia, astrocytes and macrophages occurs through expression of cytokines and chemokines from infiltration of T lymphocytes [13, 29, 30, 33]. Activation of specific subsets of CD4 lymphocytes dictates which cytokines are released. Pro-inflammatory cytokines are expressed after direct activation of Th1 and Th17 cells, whereas anti-inflammatory cytokines are a product of Th2 and T-regulatory cells [34–36]. Histopathology of the CNS white matter plaques has shown an abundance of macrophages, CD8, CD4 T lymphocytes, and B lymphocytes [13, 29, 30, 35]. Over time, the prolonged inflammation and infiltration of T and B lymphocytes leads to a disruption of the axonal-glial interaction which results in an increase in gray matter atrophy and axonal loss with marked demyelination [13, 29]. During the remission phase following each flare, there is some evidence to suggest a possible role for regulatory T cells with the induction of Foxp3 [37]. It is possible that during remission, a baseline level of inflammation is present; however, the expression of specific phenotypes of T lymphocytes shifts toward anti-inflammatory/regulatory rather than pro-inflammatory mechanisms. Based on these observations, vitamin D has emerged as a potential homeopathic

Currently, there is no definitive treatment for multiple sclerosis. Most approved

therapies are focused on controlling peripheral inflammation and preventing migration across the blood brain barrier thereby reducing the incidence of acute flares [13, 30, 39, 40]. A majority of these therapies are administered orally, as an injection or through an infusion. With both invasive and non-invasive methods, side effects include increases in liver enzymes, injection site reactions, nausea, diarrhea, and most importantly, progressive multifocal leukoencephalopathy (PML) [39]. The primary therapies prescribed at our institution are Copaxone®, Gilenya®, and Tecfidera®. Copaxone®, glatiramer acetate is an immunomodulator that is FDA approved to reduce the frequency of relapses. Gilenya®, fingolimod, is also an immunomodulator that targets reduction in the number of relapses more than progression of disease. Tecfidera®, dimethyl fumarate, is a combination of fumaric acid esters that was originally approved for oral treatment of psoriasis. Because of the inconsistent or incomplete outcomes from treatment, as well as the evolving

nature of the disorder, other biotherapies have been used as adjuvants.

One alternative biotherapeutic is the use of low doses of naltrexone (LDN), an opioid receptor antagonist. LDN is often used as an adjuvant to disease-modifying therapy to target fatigue associated with either the disorder or the medication. LDN has a strong profile of safety and tolerability [41–44]. Pilot studies utilizing LDN demonstrated that MS patients had an improvement in peripheral spasticity and mental health composite scores without inducing any side effects [42, 45]. In a retrospective analysis which compared LDN patients with LDN plus Copaxone® patients, there was no significant difference between the groups with respect to MRI, complete blood count, liver enzymes and the 25-foot walk test [44].

**74**

Animal studies have been used to study both the mechanisms of LDN, as well as to establish the role of LDN as a biotherapy in mice with experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. In these studies, mice were immunized with antigens against myelin proteins—either myelin oligodendrocyte glycoprotein 35–55 or proteolipid peptides 139–151. The key component in the mechanistic pathway is the duration of opioid receptor blockade. This work is detailed in animal studies [51–57]. LDN produces an intermittent blockade of OGFr preventing OGF from binding and thereby increasing cellular replication, similar to what is seen with high doses of Naltrexone (HDN) through a prolonged blockade of OGFr [49]. Conversely, after the blockade has subsided, within 4–6 h, there is over proliferation of endogenous OGF and OGFr and a resulting exaggerated expression of p16 and p21 leading to promotion of cellular senescence [49].

A newly discovered pathway involves the antagonism of Toll-like receptor 4 (TLR4) by LDN as means to reduce neuroinflammation or persistent pain [58, 59]. Specifically, activation of Toll-like receptor 4 (TLR4) initiates the release of inflammatory cytokines: interleukin 1 (IL-1), tumor necrosis factor α (TNFα), nitric oxide (NO), and interferon β (IFNβ) [48, 60]. Currently, the relationship of the Tolllike receptor pathway to pro-inflammatory cytokine activation is not completely understood.

### *1.6.2 Clinical studies on LDN*

Several studies have been conducted to evaluate multiple sclerosis patients who are prescribed LDN. The use of enkephalins, particularly OGF, has been demonstrated to be safe and tolerable in Phase I and Phase II studies of pancreatic cancer [61, 62]. LDN is widely used for treatment of other autoimmune disorders including Crohn's disease [63] and fibromyalgia [64].

### *1.6.3 Clinical studies on LDN and multiple sclerosis*

Clinical trials using LDN for multiple sclerosis were conducted more than a decade ago, and most likely because it is widely used with no side-effects,

government agencies are reluctant to support new trials. Three clinical trials have suggested that LDN increased the quality of life of patients with relapse-remitting or secondary progressive multiple sclerosis, without serious adverse effects [42, 43, 45]. Two retrospective studies examining charts of patients prescribed LDN alone, as well as in combination with the disease-modifying therapy Copaxone®, revealed no exacerbation of the disease or any substantial side effect for patients in either cohort [44]. In this study, the average length of disease was 14 years, with an average of 3 years on LDN alone. Clinical laboratory data revealed that patients on LDN alone had no significant differences in their blood chemistry, nutrition or liver data from patients on disease-modifying therapies.

However, these studies did not measure serum enkephalins, endorphins, or cytokines in an effort to gain more information on the mechanism of action for this biotherapeutic. A small study obtained stored serum from relapsing-remitting multiple sclerosis subjects and reported that enkephalin (i.e., OGF) levels were depressed relative to controls [51]. In the few individuals on LDN alone, serum OGF levels were elevated 2-fold in comparison to multiple sclerosis subjects on Copaxone® alone, suggesting that LDN may be effective at restoring serum enkephalin. Given this information, studies on both the mouse model of EAE and multiple sclerosis have been pursued to evaluate select cytokines that may be dysregulated in multiple sclerosis and possibly modulated by LDN (and enkephalin levels) and restored to normal levels.
