LINK BETWEEN VITAMIN D DEFICIENCY AND MULTIPLE SCLEROSIS
With Multiple Sclerosis being the leading cause of non-traumatic disability in young adults more attention needs to be brought not only to the treatment of MS, but its underlying cause. Numerous studies have shown Vitamin D deficiency to be the main link to both the development of MS and relapse rate of acute attacks in patients with MS. The relationship of Vitamin D deficiency has been proven not only to be correlative, but the actual causative factor. The mechanism of risk factors of MS such as smoking and Epstein Barr Virus are themselves responsible for vitamin D deficiency, which inevitably increase the chances of developing MS and presentation of a first demyelinating event. Both uncontrolled and controlled studies have demonstrated that when supplemented with high doses of Vitamin D (5,000-10,000 units), which ultimately raise the serum 25-OH-D levels to optimal levels (110 nmol/L), it consequently decreases rate of relapse and development of brain lesions on MRI, and slows progression in those who already present with the disease. Research has shown that the ultimate benefits are seen in patients who were supplemented with vitamin D at the early onset of MS. Additional benefit is conferred to those who are already receiving immuno-modulatory therapy such as Beta-interferon. The mechanism by which vitamin D deficiency has been evidenced to increase risk of MS is understood by the role vitamin D plays in regulation of the immune system's inflammatory and anti-inflammatory response in the body. Therefore, Vitamin D supplementation holds promise not only in prevention and progression of MS, but also in relation to all inflammatory auto-immune disorders.
Key words: Multiple Sclerosis, vitamin D deficiency, 25-OH-D serum level, serum vitamin D levels, relapse rate, MRI, RRMS, EDSS, immunomodulator, interferon, autoimmune, EBV, smoking
Introduction
According to the NIH (National Health Institute) autoimmune diseases plague a total of 23.5 million people in the United States alone. However, this number only includes 24 auto immune diseases. It is estimated that in reality 100 diseases may have an autoimmune basis, placing the number of those suffering from autoimmune diseases (AD) in the US at an estimated 50 million. Although this number is almost twice that of people who have cancer and heart disease combined, the research for cancer and heart disease individually trumps that of AD at a rate of 10:1 and 4:1 respectively. (AARDA) Even though the prevalence has either stayed flat or increased over time, not enough attention has been given to these debilitating and possibly fatal diseases. (Jacobson et. al, 1997) The long standing treatment for the last few decades has been to suppress the immune system using immunomodulators which may reduce the number of relapses or flare ups and delay the eventual disability, but have not caused a regression or even halted the inevitable progression of these diseases. Among these autoimmune diseases, an important one to focus on due to its prevalence is Multiple Sclerosis (MS). This paper will present research of the link between Vitamin D deficiency with instances and severity of MS, and the possible cure of MS through supplemental Vitamin D.
Multiple Sclerosis (MS) is characterized as a chronic inflammatory demyelinating disease of the central nervous system. It inflicts 400,000 people in the United States and 2.5 million worldwide and is the leading cause of non-traumatic disability in young adults. Women are twice as likely as men to develop MS (except in the primary -progressive form where there is no difference in prevalence between gender) and generally has an onset between the ages of 20 and 40 years old. (Tullman, 2013)
Symptoms and Signs of MS and clinical courses of MS
The onset of the disease usually first manifests itself with an attack of neurologic dysfunction referred to as a clinically isolated syndrome (CIS) in 90% of cases. The attack can come in the form of such neurologic dysfunctions such as optic neuritis, incomplete transverse myelitis, and brain stem or cerebellar syndrome. In addition common symptoms of an attack may include numbness, paresthesia, weakness of limbs, fatigue, ataxia, blurred vision, double vision, vertigo, cognitive dysfunction, depression, and bladder or bowel dysfunction. Less common symptoms consist of facial weakness, trigeminal neuralgia, hearing loss, and slurred speech. The clinical course of the disease in its initial form presents as a relapsing remitting multiple sclerosis (RRMS) in 90% of patients. RRMS is defined as patients having discrete attacks that evolve over days to weeks and increase in severity in each successive relapse, yet have a period of remission between attacks when they are neurologically stable without any disease progression between relapses. If MS is not treated during this stage it can escalate to secondary progressive MS in which there is a gradual deterioration of function independent of whether there are future relapses or not. About 10% of patients experience a form of the disease called primary progressive MS (PPMS) in which there is a continuous and gradual deterioration of neurologic function from the onset. (Tullman, 2013)
Diagnosis of MS
Patients can present with a variety of symptoms that point to MS, but in order to reach a definite diagnosis, an MS diagnostic criteria called the McDonald criteria has been established. The McDonald criteria of 2010 states that in order to reach a diagnosis of MS it is required that it be demonstrated in space (DIS) and demonstrated in time (DIT) either clinically and/or by MRI. For example if a patient has at least 2 attacks with objective clinical evidence (due to documented neurological findings) of at least 2 lesions or objective clinical evidence of 1 lesion with reasonable historical evidence of a prior attack that will meet the criteria for DIT due to having at least 2 attacks and DIS because of the clinical evidence of the lesions. However, if the person only has 2 attacks with objective clinical evidence of 1 lesion, DIS has to be proven through MRI. DIS is proven through MRI with a finding of at least 1 T2 lesion in at least 2 of 4 MS-typical regions of the CNS, namely periventricular, juxtacortical, infratentorial, and spinal cord regions. If the patient does not receive an MRI, in order to demonstrate DIS the patient would need to await a further clinical attack to implicate a different CNS site. In the opposite situation where the patient meets the criteria for DIS by having objective clinical evidence of at least 2 lesions, but fails to meet the criteria of DIT because the patient only had 1 attack, DIT must be proven by MRI. DIT is demonstrated by MRI by the simultaneous presence of asymptomatic gadolinium-enhancing and non-enhancing lesions at any time or a new T2 and/or gadolinium enhancing lesion(s) on follow up MRI, with reference to a baseline scan, irrespective of the timing of the baseline MRI. If the patient does not receive an MRI, in order to demonstrate DIT the patient would need to await a second clinical attack. In the case where the patient only had 1 attack and objective clinical evidence of 1 lesion (CIS - clinically isolated syndrome) they would need to meet criteria for DIT and DIS by demonstration on MRI by the means stated previously. In the case of primary progressive MS (PPMS) a diagnosis is reached if there is 1 year of disease progression (retrospectively or prospectively determined) plus 2 of the 3 following criteria is met: Evidence of DIS in the brain based on at least 1 T2 lesion in the MS characteristic regions of the periventricular, juxtacortical, or infratentorial regions; evidence for DIS in the spinal cord based on at least T2 lesion in the cord; Positive CSF (isoelectric focusing evidence of oligoclonal bands and/ or elevated IgG). (Poleman et. al, 2011) and (Tullman, 2013)
Prognosis of MS
Although MS has a clear classification, the prognosis is difficult to predict in any individual due to the extreme variability of the illness in its presentation and possible course that it can take. However, there does seem to be a relationship between certain variables and reaching a poor prognosis of a non - reversible disability. According to a prospective study on the prognosis of MS in which 244 patients were followed for a mean period of 9.78 years an" initially progressive course and higher basal Expanded Disability Status Scale (EDSS) ( e.g. a score of 6 is defined as unable to walk 100 meters without unilateral assistance) proved to be the best predictors of unfavorable prognosis". In addition, "a greater number of functional systems involved at onset as well as higher residual deficits in pyramidal, visual, sphincteric and cerebellar systems were predictive of a poor outcome, whereas sensory system involved turned out to be favorable". The study also found that "a longer first inter-attack interval was associated with a better prognosis." It continues stating that "the overall number of relapses in the first 2 years of the disease was of no prognostic value". Finally, "the presence of oligoclonal banding in the cerebrospinal fluid (CSF) and a cerebral MRI exam strongly suggestive or suggestive of MS in the early phases of the disease were associated with a higher probability of a worse outcome." (Amato and Ponziani, 2000, p. 831) Therefore we can deduce from this study, that due to the many variables of the disease, it is nearly impossible to counsel the patient about the definite chances of developing a disability. It is even more difficult to assess how the disease will progress and manifest over time, whether it will take a mild or severe course, and the duration of time to entering a secondary-progressive phase from the initial RRMS phase of the disease.
In order for MS to be diagnosed it must be clinically or radiologically evident and outcomes are to some extent predicted based on this evidence and its timing during the disease. However, even before the patient is diagnosed with MS according to the classification rules, the disease had already begun to develop well before the official onset. This is evident by the observation that "individuals with radiologically isolated syndrome (RIS), which specifically describes individuals who have structural anomalies in the CNS that are highly suggestive of demyelination, are at increased risk of developing MS". (Ramagopalan et al, 2010, p.727) And recently it has been brought to light that this precedes CIS, which as mentioned earlier, is "a neurological event with observed demyelination involving the optic nerve, cerebrum, cerebellum, brainstem, or the spinal cord." (Ramagopalan et al, 2010, p.727) In addition, a longitudinal serial MRI study of 71 patients with isolated syndromes were reassessed after a mean of 14.1 years and it was found that the "increases in the volume of the lesions seen on MRI of the brain in the first 5 years correlate with the degree of long-term disability". (Brex et al, 2002, p. 158) This therefore translates into a subclinical stage of the disease when known MS risk factors create the potential for full blown disease.
Risk Factors in development of MS
There are seemingly uncontrollable genetic risk factors which we have no power over at the current time such as the higher prevalence of MS among white men versus all other races, maternal half siblings versus paternal half siblings, women versus men, those closer to the equator versus those in higher latitudes, and the association with a specific genotype (namely the DRB1*1501 allele). The focus, one would assume, should therefore be specifically on the avoidance of the environmental risk factors. However, as will be seen later the risk factor of vitamin D deficiency may be at the root of all the other risk factors, both genetic and environmental.
One such environmental risk factor for increased risk of MS is smoking. "In a meta-analysis of prospective studies it was found that there was a 50% increased risk of MS in those who smoked cigarettes. In addition, in the Nuses Health Study cohorts, women with 10 or more pack years of smoking had a 50% to 70% increased risk of MS". (Munger et al., 2009) The awareness of this intervention alone would reduce the number of cases of MS by a large margin.
Another risk factor that has been identified with an increased risk of MS is the Epstein Barr Virus (EBV). It has been found that "nearly all individuals with MS (>99%) have been found to have been infected with EBV compared with approximately 94% of age matched controls". (Ramagopalan et al, 2010, p.729) This translates into adults that have never been infected with EBV very rarely developing MS. It addition it has been discovered that individuals with high titres of anit-EBV in the form of IgG antibodies have a two to ninefold increased risk of MS compared to people those with low titres. These nuclear antigens were detected 16 to years prior to the onset of MS and increased several years before the onset of neurological symptoms. (Spittler, 2009) In children it was also found that "a greater percentage of children with MS were in the high titer group, compared with age matched, EBV positive healthy controls (40% vs 18%)". (Kuznar, 2008, p.10) Therefore it is seen that there is a causal relationship between high viral titers in both adults and children. The abnormal immune response to EBV being linked to the increased risk of MS is further solidified by a 2006 meta-analysis study along with three other studies in Denmark, Netherlands, and Canada, which found that infectious mononucleosis, which is a marker for an abnormal immune response to the EBV, is associated with a twofold risk of MS. (Spittler, 2009) These studies illustrate that MS risk is not necessarily related to exposure to the EBV, but rather the dysfunction of the immune system in response to the virus. This idea of immune dysfunction is advanced by a study of 34 EBV seropositive patients with MS and 34 EBV seropositive healthy subjects who had not received immunomodulatory therapy in the previous 3 months, which were measured for IgG immunity to EBV nuclear antigen 1 (EBNA1), viral capsid antigen, and T cell immunity in response to autologous EBV infected B cell lymphoblastoid cell line (LCL). The result of the study found that the MS population had increased levels of anti-EBNA IgG, but a decreased frequency of LDL specific T cells compared with healthy subjects. It was concluded that "the quantitative deficiency in CD8+ T cell immunity to EBV might be responsible for the accumulation of EBV infected cells in the brain of patients with MS". (Pender et al., 2009) It can therefore be deduced from this difference in immune response to EBV that the underlying component of MS is one of dysfunctional immunity.
Link of Vitamin D deficiency to MS
Dysfunctional immunity being the essential reason for the development of MS and its severity of course is further bolstered by the risk factor of Vitamin D deficiency and its relationship to regulation of the immune system. As we will explain later, vitamin D acting as immunomodulator is not only a risk factor in of itself, but also may be linked to all other risk factors for the development and relapse rate of MS. However, first it will be demonstrated in numerous studies the inverse relationship between serum vitamin D levels and the severity of the progression of MS.
Effect of vitamin D deficiency on relapse rate, lesion formation on MRI,
and disability score
Vitamin D has been shown to reduce MS activity and slower the rate of progression of MS. In a 2012 prospective longitudinal study, 73 patients with RRMS had their blood samples measured for 25 hydroxy-vitamin D (25-OH-D) levels every 8 weeks for a mean of 1.7 years. Exacerbation rates were assessed as associated with the 25-OH-D serum levels which acted as the time-dependent variable. The monthly moving averages of 25-OH-D levels were categorized as low (<50 nmol/L), medium (50-100 nmol/L), and high (>100nmol/L). The finding of the results were that "exacerbation risk decreased significantly with higher serum vitamin D levels: respective relative exacerbation rates for
the medium and high level category as compared to the low-level category were 0.7 and 0.5." (Runia et al., 2012, p.261) When plotted as a log linear without a threshold it found as the serum 25-OH-D doubled in concentration the exacerbation rate decreased by 27%. (Runia et. al, 2012) Similar results were found in a study in 2014 named the Betaferon/Betaseron in Newly Emerging multiple sclerosis For Initial Treatment (BENEFIT) trial which was originally meant to solely be a randomized trial designed to evaluate the impact of early versus delayed interferon beat-1b in treatment in patients with CIS. The study also conducted a corresponding analysis of vitamin D concentrations, following the patients for 5 years both clinically and by MRI. It found that "a 50 nmol/L increment in average serum 25(OH)D levels within the first 12 months predicted a 57% lower rate of new active lesions, 57% lower relapse rate, 25% lower yearly increase in T2 lesion volume, 0.41% lower yearly loss in brain volume from months 12 to 60, and lower disability as measured by (Expanded Disability Status Scale) EDSS during the following 4 years". (Ascherio, 2014, p.306) Both studies demonstrate the correlation between higher vitamin D levels and the lower rate of progression of MS both clinically and radiologically. However in Runia et al. (2012) it states that "the possibility of reverse causality cannot be ruled out completely" (Runia et al, 2012, p.261) This means that it may be possible that it is not necessarily that vitamin D levels have an effect, but on the contrary, MS may have an effect on vitamin D levels.
Causation link of vitamin D deficiency to MS, not just correlation
A 2006 prospective, nested case-control study among more than 7 million US military personnel who had serum samples stored in the Department of Defense Serum Repository resolves the reverse causality dilemma. The Army and Navy physical disability databases between 1992 and 2004 recorded 257 cases of MS which were later confirmed by medical record review. The average 25-OH-D of 2 or more serum samples collected before the date of initial MS symptoms was used to evaluate the vitamin D status of each case. The results were that among whites (148 cases, 296 controls) there was a 41% decrease in MS risk for every 50 nmol/L increase in 25-OH-D, with no significant difference by sex. In addition there was a significant 51% reduction among those with 25-OH-D levels of 100 nmol/L or higher compared with those with levels less than 75 nmol/L. This impact of vitamin D levels with lower MS risk was especially noted in those before 20 years of age. (Munger et al., 2006) In the study Munger et al. (2006) voice the same concern as Runia et al, (2012) in that there may possibly be an unknown mechanism by which MS has an effect on vitamin D metabolism. It goes even further to question that even more likely could be that due to the fact that heat commonly exacerbates MS symptoms, individual with MS will intentionally avoid sun exposure, and therefore would automatically have lower 25 (OH) D levels than healthy individuals. This dilemma is reconciled by examining the results that the vitamin D levels among individuals who developed MS were stable at low levels of 71.8 nmol/L more than 6 years before symptoms, 71.6 nmol/L between 4 and 6 years before, 73.5 nmol/L between 2 and 4 years before, 70.3 nmol/L between 1 and 2 years before, and only drop significantly to 63.3 nmol/L after symptom onset. (Munger et al, 2006) If it was MS that caused lower levels of vitamin D, as a consequence, the levels would have trended down till the onset of MS during the years preceding MS, but instead remained steady. As is mentioned earlier, there is a state of MS, when the radiologically isolated syndrome (RIS) precedes the clinically isolated syndrome (CIS) (Ramagopalan et al, 2010). Therefore the subclinical MS should have triggered the lower vitamin D levels, but rather it happened in reverse.
Proving causation of low levels of Vitamin D as a risk factor for MS and not a correlation explains the results of another nested case control study which prospectively analyzed the blood samples of MS cases (192) in the northern half of Sweden from the years 1976 - 2005. In epidemiologic studies it found that during those years prevalence with MS increased, while the prevalence of 25(OH) D levels were decreasing gradually. It discovered that those with levels >75 nmol/L were associated with a decreased risk of MS by an odds ratio of 0.39 ( although there was no association between gestational 25(OH)D levels and MS risk in offspring). Therefore the rise in cases of MS in Northern Sweden is necessarily explained by vitamin D deficiency. (Salzer et al., 2012)
MS relapse event and its effect on lowering serum vitamin D levels
However, there exists the possibility that there may be a drop off of vitamin D levels during MS relapses due to the alteration of the endocrine circuitry regulating serum calcium. In the study of 23 patients with MS that found that " while 25(OH)D had a similar seasonal variation in MS patients and healthy controls25(OH)D, serum levels were lower and intact parathyroid hormone (iPTH) serum levels were higher during MS relapses than in remission. All 21 relapses during the study occured at serum iPTH levels >20 ng/l, whereas 38% of patients in remission had iPTH levels ≤ 20 ng/l". (Hanninen et al., 2007, p.152) Therefore, although it was established earlier that low vitamin D levels precede the onset of MS and , according to this an acute exacerbation can trigger a decrease in vitamin D levels. This would explain why in the military study by Munger et al. (2006) the vitamin D levels showed such a sharp drop at the onset, hovering levels in the low 70s nmol/L to 63.3 nmol/L. The reason this could be happening is the patient's aversion to sunlight during a relapse, the actual flare up of MS preventing the absorption of vitamin D through some unknown mechansim, or for some other reason. Regardless of the reason, the fact is that each successive relapse temporarily decreases serum vitamin D levels which translates into a bad cycle of events. The underlying vitamin D deficiency brings on the initial relapse, which decreases vitamin D levels which can potentially bring on a successive relapse. his clarifies the research mentioned earlier that found that when there were more relapses during the early stages of MS, the eventual progression of the disease was more severe in those individuals. It is therefore deductive reasoning that if MS patients are treated with vitamin D supplementation during the early stages of disease, they could potentially avoid a serious progression of the disease.
Reducing relapse rate through supplementation of vitamin D
The idea of sustaining high vitamin D levels through supplementation lowering the relapse rate is seen in an "observational, uncontrolled study of vitamin D3 supplementation (3010 IU/day on average) given to 156 consecutive patients with relapsing remitting multiple sclerosis, under first line immunomodulatory therapy and with inital 25-OH-D serum level lower than 100 nmol/l. Relapses were determined for 29.1+ 8.4 months during vitamin D and 29.8 + 10.1 months before supplementation." The results were that for "every 10 nmol increase in 25-OH-D level there was an association to a reduction in the relapse incidence rate of 13.7%". (Pierrot-Deseilligny et al, 2012, p.187) In addition it was the finding of the study that the "effect of vitamin D supplementation was independent of the presence of or absence of an immuno-modulated therapy (IMT) (glatiremer acetate in 54% of cases and various types of interferon betas in 46%) prior to inclusion [in 76 patients, an IMT had already been present for a variable period (4.2 + 2.7 years; median 4 years; range 0.5-12 years) and in 80 patients the first IMT was started simultaneously with vitamin D supplementation]. This strongly suggests that the reduction of incidence of relapse could not be explained by the sole action of IMT".(Pierrot-Deseilligny et al, 2012, p.191-193) Another interesting outcome of was the inverse relationship between 25-OH-D level increase with relapse rate decreased had a plateau effect at a level of 110 nmol/l. Finally, the study possibly discredits the notion that the lower vitamin D insufficiency during MS is a consequence of MS patients limiting sunlight exposure due to the worsening of symptoms, because the serum vitamin D levels were "considerably higher than would be expected if the reduction in relapse rate had modified patients' lifestyle habits regarding sunlight exposure". (Pierrot-Deseilligny et al, 2012, p.196) However, another explanation could be that the disease itself had subsided to such an extent that the patients no longer were sensitive to sunlight and now had both vitamin D from sunlight and vitamin D from supplementation as contributing to the high levels of serum vitamin D. One disadvantages of this study was that although it was analyzed subsequently and adjusted for factors such as gender, age, disease duration, degree of disability (EDSS, and the type of IMT, it was uncontrolled at the onset of the study. Another thing that can not be determined from the study was the difference in contributory effectiveness between the IMT and vitamin D supplementation, although it was shown that vitamin D was independent factor for the decrease in rate of relapse.
Safety and efficacy of high dose vitamin D supplementation in MS patients
An open-label randomized prospective controlled trial of 45 patients with RRMS and 4 with secondary progressive MS exhibiting the association of vitamin D supplementation with reduction in risk of MS can compensate for the previous study's uncontrolled environment. "Forty women and 9 men participated. The mean age of all subjects was 40.5 years (21-54), with mean EDSS 1.34 (0-6.0) and disease duration of 7.8 years (1-25)" (Burton et al, 2010, p.1855). In addition to evaluating the efficacy of vitamin D on relapse rate and EDSS score, this trial wanted to demonstrate the safety of high doses of vitamin D and measure immunogical markers for immunomodulatory effects. The vitamin D doses of the treatment patients were rapidly escalated to 40,000 IU/day over 28 weeks, followed by 10,000 IU/day for 12 weeks, and eventually titrated to 0 IU/day which resulted in a mean daily dose of roughly 14,000 IU/day and reaching a mean peak of serum 25(OH)D level of >2000 nmol/L. Together with the vitamin D patients also received 1200 mg/day dose of tricalcium phosphate both because the combination of vitamin D and calcium was extremely effective in both experimental autoimmune encephalitis (a useful animal model for MS) and human cancer prevention trials and to allow safety data to be generalized to those already on calcium supplementation. The results were "a proportion of treatment patients experiencing relapses during the trial being 0.16 versus 0.37 in the control group" (Burton et al, 2010, p.1856). which translates as a "41% reduction in annualized relapse rate versus 17% in the control group". (Burton et al, 2010, p.1856). Another encouraging statistic was that a significantly larger portion of those with a 25(OH)D level = or > 100nmol/L had a decrease in T-cell reactivity and proliferation (an autoimmune response suspected to be a factor in MS, as will be mentioned later) compared to those with levels of <100 nmol/L. Yet, MMP-9TIMP-1 values and cytokine profiles change did not differ between groups which may signify that vitamin D does not have an influence on these inflammatory markers. An additional finding was that only 8% of the treatment group had a greater EDSS score versus 37.5% in the control group. However, since the mean EDSS of 1.34 was low to begin with, they were small changes. A very valuable takeaway from this study was the recognition of the safety of vitamin D, even at high doses (about 10,000 IU). The cited value for serum value toxic value was is 250 nmol/L yet, patient mean serum values were above this threshold for over 18 weeks with no adverse consequences. Neither hypercalcemia or persistent hypercalciuria was ever observed in lab values, along with the absence of any disruption in renal or hepatic function. This demonstrates the protective character of vitamin D against hypercalcemia. The obvious downfall of the study is that it was that although randomized, it was not blinded. As the authors of the study conclude, a "development of a multicenter, randomized, blinded controlled phase II proof-of concept trial which is underway, is likely the only way to truly defne the impact of vitamin D on outcomes meaningful to patients with MS". (Burton et al, 2010, p.1858)
Connection of other risk factors of MS with vitamin D deficiency
Now that the link between vitamin D and MS rate and severity has been established, it is important to understand why vitamin D deficiency has such a crucial role in the development of MS. To better comprehend the detriment of vitamin D deficiency in relationship, it is best to analyze its connection with some of the risk factors that were noted earlier and its importance in maintaining a functional immune system. (Refer to Table 1)
Table 1 (Hanwell and Banwell, 2010)
MS risk has a strong correlation with latitude, with those countries receiving the most sun in the winter months having a lower prevalence of cases of MS. This was proven by a case-control study in Australia from various latitudes. Those with the higher actinic skin damage and serum vitamin D status were independently associated with decreased first demyelinating events (FDEs). In contrast differences in leisure time sun exposure, serum 25(OH)D level, and skin type additively accounted for a 32.4% increase in FDE incidence from the low to high latitude regions. (Lucas et al., 2011) Northern European populations show the same trend with the exception of Norway, which can be explained by their high vitamin D intake through consumption of oily fish. It additionally has been indentified that "those who migrate before adolescence acquire the risk of their new county, while those who migrate after retain the risk of their home country". (Ramogopalan et al, 2009, p.4) With these findings it was hypothesized that the environmental candidate of vitamin D exposure may interact with inherited factors. It has been found through genome sequencing that "the Major Histocompatibility Complex (MHC) on chromosome 6 exerts the strongest genetic effect on the disease". Through sequence analysis, a single MHC vitamin D response element (VDRE), was localized to the promoter region of HLA-DRB1. Interestingly enough it was discovered that the dominant haplotype of Northern Europeans is 1 of 400 possible alleles of HLA-DRB1, namely the HLA-DRB1*1501 haplotype, responsible for increasing MS risk among Northern Europeans 3-fold, was the only variant identified as having a functional VDRE in the promoter region. Other allele variants of HLA-DRB1 are therefore not sensitive to vitamin D status. Being the VDRE on HLA-DRB1*1501 haplotype lies close to the MHC class II, if there is lack of vitamin D or impaired metabolism of vitamin D in those individuals early in life, as a consequence there will be a reduced expression of MHC class II molecules. Since MHC class II molecules act as regulator in self antigen negative selection of T cells as they mature in the thymus, the reduced expression of MHC class II molecules could allow auto-reactive T cells to escape thymic deletion. This would as a consequence increase autoimmune disease risk. (Ramogopalan et al, 2009) "If the immune system fails to establish and maintain immune tolerance to molecules derived from the blood brain barrier (BBB) or CNS myelin, this could result in the type of demyelinating immune attacks observed in MS". (Hanwell and Banwell (2010, p.207) Thus, from this evidence there is a strong case made that by supplementing with vitamin D, it can reduce the prevalence of MS, even among those individuals that carry the genetic factor that causes certain individual to be more susceptible to acquire MS.
Interestingly enough vitamin D deficiency is also thought to be the culprit for the aforementioned risk factor of cigarette smoke on development of MS. Benzoapyrene (BaP) is a polycyclic aromatic hydrocarbon produced by cigarette smoking. In one study it was shown that BaP enhanced the hydroxylation of 1,25(OH)2D3 by CYP24A1 in THP-1 cells in human macrophages. This process normally happens in a healthy person, but this enhancement of elimination leads to vitamin D3 insufficiency. This thereby reduces vitamin D-mediated immunity which can eventually lead to the onset of MS. (Matsunawa et al, 2009)
Finally in relation to Epstein-Barr virus's (EBV) role in MS, there are a couple of explanations on its connection to vitamin D insufficiency. One explanation is that in the presence of vitamin D insufficiency there is a decrease in production of IL-10, an anti-inflammatory cytokine, which acts during infection states. IL-10 is also produced by the Epstein Barr virus, but in the form of viral Il-10. This consequently down regulates human IL-10 production which is already suppressed in an individual with vitamin D insufficiency. This could eventually lead to an enhanced pro-inflammatory state which may responsible for MS. (Hanwell and Banwell, 2010) Another way EBV is connected to vitamin D insufficiency is by the EBV's self preservation mechanism by blocking the vitamin D receptor (VDR) dependent genes. EBNA-3 is one of the proteins expressed by cell lines (LCLs) that grow as a consequence of EBV infected B cells that were transformed into immortalized lymphoblasts. Since EBNA-3 is a binding partner of VDR it "blocks or downregulates transcription of the VDR dependent genes at the basal level and upon its activation by a ligand, namely the 1-alpha,25-di-hydroxyvitamin D3". Consequently, vitamin D which normally will by to the VDR to induce growth arrest and/or apoptosis of the virus. Regardless whether it is the vitamin D that initializes the immunocompromised state in EBV or the EBV that impedes the immune action of vitamin D through blocking its receptor, vitamin D has an important role in maintaining the correctly functioning immune system.
Comparison of vitamin D supplementation as treatment for MS versus current conventional treatments These previously stated roles of vitamin D and how its inter related with other risk factors for MS demonstrate the significance of vitamin D for a properly functioning immune system. However, these are only a few of the many ways vitamin D support and modulate the immune system. (Below in Table 2 is a list of the various effects of vitamin D on different components of the immune system.)
Table 2 (Guillot et al., 2010)
With all the significant evidence to make the case for vitamin D supplementation in MS patients or at least to further investigate the effectiveness of vitamin D in preventing relapse and possibly slowing down the progression of the disease. This is especially emphasized when comparing vitamin D supplementation with current treatments such as interferon beta-1b (IB) and glatiramer (GA).
Firstly, the mechanism by which IB and GA create an anti-inflammatory environment to diminish the autoimmune response is almost identical to that of vitamin D. In the differentiation of naive CD4 helper T cells, the products are Th1 (T-helper lymphocyte 1) cells which are pro-inflammatory and Th2 cells that are anti-inflammatory or regulatory. When GA is administered it generates GA specific T cells which are predominantly Th2 biased thereby reducing the inflammation in autoimmune disease. IB on the other hand, prevents interferon-y, a pro-inflammatory Th1cytokine. Both GA and IB have been "shown to decrease the production of IL-12 , another pro-inflammatory cytokine, required for differentiation along the Th1 route". (Wee Yong, 2002, p.59) It is debated whether IB has an affect on the Th2 shift as is the case for GA. In terms of vitamin D (calcitriol) it "down regulates pro-inflammatory dendritic cells and Th1, while promoting an anti-inflammatory Th2 lymphocyte profile." (Hanwell and Banwell, 2011, p.207) Additionally, "various in vitro models have demonstrated that calcitriol also suppresses expression or reduces mRNA stability of matrix metalloproteinase (MMP-9 which increases the permeability of the BBB to auto reactive immune cells." (Hanwell and Banwell, 2011, p.207) These are among other anti inflammatory mechanisms (refer to figure 2) which the immunomodulators of GA and IB do not accomplish. Secondly, just as research has shown that treatment with beta interferon, especially in the early stages of the disease, slows down EDSS progression and reduces relapse rate (but does not halt the progression of the disease) (Kappos, 2009), it is also evident that vitamin D can achieve similar results. [In reference to the results for beta interferon and glatiramer their outcomes were similar in terms of relapse rates and number and change of T2 lesions on MRI (Mikol, 2008).] However, what really sets apart vitamin D from conventional treatments are the adverse effects. While vitamin D has been proven to be safe even at high doses, current immune therapies contain adverse effects such as flu-like syndrome and increased risk of infection with Beta-interferon, cardiotoxicity wtih mitoxantrone, and potential risk of progressive multifocal leukoencephalopathy with natalizumab. (Moses Jr and Brandes, 2008).
Conclusion
For these reasons there is a need for a randomized, blinded, long term study, preferably over a 10 year span, that measures the effect of high dose vitamin D supplementation (which has been proven to be safe), which is necessary in order to reach optimal serum 25(OH)D levels of >100 nmol/L, on the progression of MS in terms of EDSS score, relapse rate, progression of the actual disease in terms of neurological symptoms and T2 and gadolinium lesions on MRI [there has been a study that included MRI lesions that reduced them from 33% at baseline to 29% at 28 weeks, but the study only lasted 48 weeks (Wingerchuk et al, 2005)]. Chart from Dr. Josh Axe
However, it has already been proven that the initial development of MS is dependent on serum levels of vitamin D. Therefore, more must be done by practitioners in stressing to patients how vital of a role vitamin D takes in preventing the avoidable debilitating disease of MS. Additionally, practitioners should be open to suggesting high doses of vitamin D to supplement their current therapy in treating patients with MS, which has been shown to have added benefits to interferon therapy. Finally, although MS is an autoimmune disease on its own merit in specifically targeting the CNS myelin sheath, it is grouped together in the larger class of autoimmune diseases that include lupus, rheumatoid arthritis, irritable bowel disease, etc. Thus, research has shown benefits of vitamin D in prevention and treatment of numerous other auto immune diseases by regulating the immune system to function how it was meant to.
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