Vitamin D and autoimmune rheumatic diseases

Abstract

Sir, We have read the letter by Belloli L et al. [1], who commented on our paper concerning low levels of vitamin D in patients affected by systemic sclerosis (SSc) [2] and showed further data on hypovitaminosis D in SSc. We agree with Belloli L et al. that in Italy, hypovitaminosis D is very frequent not only in systemic rheumatic diseases as SSc but also in very different unrelated diseases like osteoarthritis [1] as well as in elderly women [3], but not in premenopusal women, in whom low concentrations of vitamin D were found in 27.8% and 3.4% of the cases in winter and in summer, respectively [4]. But in our opinion, the interest concerning hypovitaminosis D in SSc and in other connective tissue diseases was that low levels of vitamin D may influence clinical manifestations; in SLE hypovitaminosis D has been associated with disease activity and severity [5–7] and in undifferentiated connective tissue diseases with a high risk of developing a well-defined connective tissue disease [8]. In rheumatoid arthritis, the serum concentration of vitamin D correlated negatively with disease activity (DAS28) and disability as evaluated by Health Assessment Questionnaire and mobility activities of daily living score [9]. In SSc, an inverse correlation between the serum level of vitamin D has been reported with disease activity and with acutephase reactants [10]; vitamin D deficiency was also associated with more severe diseases [2], supporting both the immunomodulatory properties [11] and the antifibrotic action of the vitamin [12, 13]. Moreover, very recently, it has been reported that vitamin D plays an antiproliferative effect on mesenchymal multipotent cells [14] revealing possible new perspectives on the pleiotropic properties of the molecule. As recently reviewed, the development of autoimmune rheumatic diseases is dependent on the interaction between genetic background and many environmental factors, which include hypovitaminosis D [15]. Therefore, low vitamin D status may represent an easily modifiable factor, whereby treatment may have a beneficial impact on both the development and the clinical phenotype of connective tissue diseases.