Nath MC, Cubro H, McCormick DJ, et al. - In preeclampsia, a pregnancy-specific hypertensive disorder, further characterized by multi-system involvement, dysregulation of a key immunomodulatory cytokine, IL-10 (interleukin-10), has been observed. Researchers conducted a systematic review and meta-analysis with the aim to determine circulating IL-10 levels in preeclamptic and normotensive pregnancies at 2 time points: before, and at the time of preeclampsia diagnosis. Searching PubMED, EMBASE, and Web of Science databases, they screened 876 abstracts; of these, 56 studies were included in the meta-analysis. Before the time of active disease, there were no differences in circulating IL-10 levels. At the time of active disease, significantly lower IL-10 levels were recorded in women with preeclampsia (n = 1,599) vs normotensive controls (n = 1,998). Both early/severe and late/mild forms of preeclampsia were correlated with lower IL-10 levels. The use of sera paired with ELISA technology yielded the best distinction in IL-10 levels between preeclamptic and normotensive pregnancies. Overall findings support the role of reduced IL-10 levels in the pathophysiology of preeclampsia.