For some time now, the observation that MS prevalence increases with latitude, meaning the further from the equator one gets, the higher likelihood of MS in the environment. Researchers in this article therefore look at Vitamin D and how its levels may in these different latitudes may help explain the differences in prevalence.
The article notes that 400,000 people in the U.S. have MS, of nearly 309, 055, 803 people in the U.S. (U.S. Census Bureau). UV exposure, as well as vitamin D levels can effect immune responses, but the question which arises is whether immunoregulation is done via UV exposure, or indirectly via vitamin D levels, or the two? As referenced in the article, research somewhere (not cited) has shown that increased levels of the active form of vitamin D can "block" the disease in animals.
The experiment uses mice which are genetically predisposed to an MS-like disease state, and the mice are injected with nerve antigen to initiate the disease. After initiation, one group of animals were exposed to "moderate" UV strength (equal to 2 hours of direct summer sun) for one week and the other group was irradiated every 2nd or 3rd day. They found that the exposure reduced the expression of symptoms for MS, but not the prevalence, especially in those mice irradiated every other day. The researchers also deduced that although vitamin D levels were increased with UV exposure, that factor alone could not explain the results.
The groups next area of study is to see what role skin may play with UV exposure to the production and expression of compounds involved in inflammation and the inflammatory response. The article identifies two possibilities of usefulness:
1. In the short term, if they can identify the specific active wavelength at which these same results can be obtained, this can be used as a therapy for those people suffering from MS.
2. In a more long term goal, if the group can discover the compound or compounds that the skin may be producing, the may be able to isolate or synthesize the compound and market a drug treatment.
The group does caution that this information is in the early experimental stages of development, and that results of a similar treatment may not lead to intentions.
I also found an article that correlated UV exposure with MS. The article is called,"Childhood Sun Exposure May Lower Multiple Sclerosis Risk." In this article a study was conducted to compare sun expose and the risk of MS among twins.
ReplyDeleteThe study contained 79 pairs of monozygotic twins. They measured each twin's sun exposure using a sun exposure index which was created by adding up exposure in 9 different outdoor activities.
The researchers found that, "the twin who spent more hours outdoors as a child had a 25% to 57% reduced risk of developing MS" They also calculated that "For each unit increase in the sun index, the relative risk of MS decreased by 25%, independent of birthplace and age at diagnosis"
The researchers mention that these findings may be due to vitamin D production, but they also suggest that, "Ultraviolet radiation may exert its effect directly by producing cytokines, and reducing natural killer cell activity, thus affecting innate immunity."
The study did contain some bias due to the fact that the sun exposure could not be directly quantified, but relationship between MS and UV exposure does seem prevalent. The researchers believe that studies in this area should take high priority in discovering the etiology of MS.
http://www.medpagetoday.com/Neurology/MultipleSclerosis/6236
This is an interesting correlation, but it will be even more interesting to see the overall outcome if the relationship between UV and MS is solidified. Meaning, how much constant UV exposure would be necessary and would the benefits outweigh the potential dangers of being exposed to these excessive amounts of UV radiation?
ReplyDelete