Circulating microRNAs (miRNAs) have emerged as candidate biomarkers of various diseases and conditions including malignancy and pregnancy. This approach requires sensitive and accurate quantitation of miRNA concentrations in body fluids. Herein we report that enzyme-based miRNA quantitation, which is currently the mainstream approach for identifying differences in miRNA abundance among samples, is skewed by endogenous serum factors that co-purify with miRNAs and anticoagulant agents used during collection. Of importance, different miRNAs were affected to varying extent among patient samples. By developing measures to overcome these interfering activities, we increased the accuracy, and improved the sensitivity of miRNA detection up to 30-fold. Overall, the present study outlines key factors that prevent accurate miRNA quantitation in body fluids and provides approaches that enable faithful quantitation of miRNA abundance in body fluids.

Citation Kwak‐Kim J, Park JC, Ahn HK, Kim JW, Gilman‐Sachs A. Immunological modes of pregnancy loss. Am J Reprod Immunol 2010During the implantation period, a significant portion of embryos are lost and eventually less than half of clinically established pregnancies end as full‐term pregnancies without obstetrical complications. A significant portion of these pregnancy losses is associated with immune etiologies, including autoimmune and cellular immune abnormalities. Although an autoimmune etiology such as anti‐phospholipid antibodies (APAs) has been reported to induce placental infarct and thrombosis at maternal–fetal interface, APAs induce inflammatory immune responses as well. Inflammatory immune responses, such as increased proportions of NK cells and Th1/Th2 cell ratios in peripheral blood are related to recurrent pregnancy losses and multiple implantation failures. Systemic and local inflammatory immune responses seem to be induced by activation of Toll‐like receptors with infectious agents, fetal cell debris, or gonadotropin‐releasing hormone agonist, etc. Cellular activation of T and NK cells leads to pro‐inflammatory cytokine storm and consequently, placental infarction and thrombosis. Potential application of anti‐inflammatory therapeutic agents for the prevention of pregnancy losses should be explored further.

TAI is associated with impaired cellular and humoral immune responses in women with RSA or UI. In women with TAI, serial TFT is recommended when pregnancy is established.