Th17 mediators and vitamin D status

Abstract

In their study on Th1 and Th17 hypercytokinemia in severe pandemic influenza, Bermejo-Martin and colleagues [1] observed significantly elevated levels of IL-17 and particularly IL-6 in critically ill patients. They also reported that up to 50% of critical care patients studied were obese. Correale and colleagues [2] indicate that activated vitamin D enhances the development of IL-10-producing cells and reduces the number of IL-6- and IL-17- secreting cells. Studies show that obese and overweight individuals are more likely to have an inadequate vitamin D status [3,4]. According to Louie and colleagues [5], diabetes and obesity were the most frequently identified underlying conditions in fatal pandemic 2009 influenza A (H1N1) infection cases older than age 20 years world wide. In addition, obese people usually have high calorie and low nutritional value diets. Aasheim and colleagues [6] showed that low concentrations of vitamin B-6, vitamin C, 25-hydroxyvitamin D, and vitamin E adjusted for lipids are prevalent in morbidly obese Norwegian patients seeking weight-loss treatment. It would be interesting to see if any of the critical cases observed in the study by Bermejo-Martin and colleagues were insufficient or deficient in vitamin D and/or other nutrients relevant for intracellular signaling involved in inflammation. If vitamin D plays a role in human general capacity to deal with infection and other diseases, then an increase in Th17 mediators in severe pandemic influenza patients could be, at least in part, related to vitamin D insufficiency/deficiency.