A study published in the journal Cornea provides new evidence that the pro-inflammatory cytokine interleukin (IL)-21 may contribute to the development and severity of Sjögren’s syndrome.
Primary Sjögren’s syndrome is an autoimmune disease causing dry eyes and dry mouth, and featuring mononuclear and plasma cell infiltration in the salivary and lacrimal glands. Recent research indicates that IL-21 may play a significant role in the pathogenesis of Sjögren syndrome through effects on interferon signaling, and the stimulation of IL-17 helper T cells (Th17) and plasma-cell differentiation or B cell hyperactivity (SK Kwok et al., Nat Rev Rheumatol. 2015 Jan 13. doi: 10.1038/nrrheum.2014, 225; FG Kroese et al., Expert Rev Clin Immunol, 2014, 4:483).
In the Cornea publication, Lim SA and colleagues from the Catholic University of Korea, Seoul, Korea, report the presence of increased tear IL-21 levels and higher IL-21 gene expression in the conjunctiva of patients with Sjögren syndrome. Importantly, the tear IL-21 level correlated with markers of disease activity in these patients.
Currently, there is no definitive treatment for Sjogren’s syndrome, and therapies are basically symptomatic (R Hal Scofield, 2011). It is known that IL-21 is involved in the differentiation of Th17 cells that are major players in autoimmunity. Thus, taking into consideration previous reports implicating the involvement of IL-21, the study may suggests new therapeutic developments directed at the underlying pathophysiology of Sjogren’s syndrome.