Research: Interleukin -7 a risk factor is reduced in MS

Kreft KL, Verbraak E, Wierenga-Wolf AF, van Meurs M, Oostra BA, Laman JD, Hintzen RQ. Decreased systemic IL-7 and soluble IL-7Rα in multiple sclerosis patients.Genes Immun. 2012 Aug 23. doi: 10.1038/gene.2012.34. [Epub ahead of print].

Polymorphisms (single-nucleotide polymorphism (SNP)) in the interleukin-7 receptor-α (IL-7Rα)/IL-7 pathway are associated with an increased risk to develop multiple sclerosis (MS). The rs6897932 SNP in the IL-7Rα leads to increased soluble IL-7Rα production. Given the functional interaction between sIL-7Rα, membrane-bound IL-7Rα and IL-7, we assessed IL-7, mIL-7Rα and sIL-7Rα levels in MS patients and healthy controls (HCs). One-hundred and twenty eight MS patients had significantly lower sIL-7Rα levels compared with 73 HCs. The levels of sIL-7Rα increased dose-dependent upon rs6897932 [C] risk allele carriership in both HCs and MS. Next, we hypothesized that lower sIL-7Rα could result in a higher mIL-7Rα to soluble IL-7Rα ratio. Indeed, 52 MS patients had significantly increased mIL-7Rα to sIL-7Rα ratio for both CD4 and CD8 T cells compared with 44 HCs. Given the supposed role of IL-7 in autoimmunity, we determined whether sIL-7Rα influences IL-7 levels. IL-7 levels were significantly decreased in 40 MS patients compared with 40 HCs. In conclusion, MS patients had lower free IL-7 and a higher membrane to soluble IL-7Rα ratio. The soluble IL-7Rα levels correlate with the rs6897932 [C] risk allele carriership. The skew at the IL-7 and IL-7Rα level may influence responsiveness of IL-7Rα(+) cells

Genes relating to the interleukin 7 receptor, which binds interleukin 7 (IL-7), which is a white blood cell growth factor are linked to the susceptibility of MS. When IL-7 receptor (soluble IL-7R) is shed from cells if floats around the blood mopping up IL-7. The genetic variant as receptorsocated with MS leads to an increase in the production of the shedv version of IL-7 receptor and indeed people with MS had lower IL-7 in their blood. HOw this actually influences MS is unknown but it is likely going to be something to do with the development of the immune response.

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