The Research Roundup provides an overview of the past week’s research from Mayo Medical Laboratories consultants, including featured abstracts and complete list of published studies and reviews.
Renal histologic expression of the podocyte-specific protein, nephrin, but not podocin, is reduced in preeclamptic compared with normotensive pregnancies. Mayo Clinic researchers hypothesized that renal expression of podocyte-specific proteins would be reflected in urinary extracellular vesicles (EVs) of podocyte origin and accompanied by increased urinary soluble nephrin levels (nephrinuria) in preeclampsia. They further postulated that podocyte injury and attendant formation of EVs are related mechanistically to cell-free fetal hemoglobin (HbF) in maternal plasma. Compared with urine from women with normotensive pregnancies, urine from women with preeclamptic pregnancies contained a high ratio of podocin-positive to nephrin-positive urinary EVs (podocin+ EVs-to-nephrin+ EVs ratio) and increased nephrinuria, both of which correlated with proteinuria. Plasma levels of hemopexin, which were decreased in women with preeclampsia, negatively correlated with proteinuria, urinary podocin+ EVs-to-nephrin+ EVs ratio, and nephrinuria. Administration of HbF to pregnant rabbits increased the number of urinary EVs of podocyte origin. These findings provide evidence that urinary EVs are reflective of preeclampsia-related altered podocyte protein expression. Furthermore, renal injury in preeclampsia associated with an elevated urinary podocin+ EVs-to-nephrin+ EVs ratio and may be mediated by prolonged exposure to cellfree HbF. The study was published in the Journal of the American Society of Nephrology.