Small molecules of RNA are positively associated with disease relapses in multiple sclerosis (MS) in patients according to a report published online this week in Nature Immunology. These RNA molecules could potentially serve as a biomarker for MS and may have therapeutic applications for the treatment of the disease.
The short RNA molecules, called microRNAs, bind complementary regions of untranslated mRNA together and inhibit their translation into proteins. Gang Pei and colleagues found that the amount of one such microRNA, miR-326, in humans is positively correlated to a flare of MS symptoms. Notably manipulation of miR-326 abundance in a mouse model of MS could worsen or alleviate symptoms depending on whether microRNA expression was increased or decreased, respectively.
Pei and his team show that miR-326 inhibits the production of a protein known to inhibit T helper cells that produce the cytokine interleukin 17. These interleukin cells have previously been associated with MS. Measuring miR-326 amounts may therefore serve as a useful diagnostic marker. If ways can be found to inhibit miR-326 in humans, this discovery could prove useful therapeutically by reducing interleukin 17 cell numbers in MS patients.