Background-Targeted therapies to stabilize the clinical manifestations and prolong pregnancy in preeclampsia do not exist. Soluble fms-like tyrosine kinase 1 (sFlt-1), an alternatively spliced variant of the vascular endothelial growth factor receptor 1, induces a preeclampsia-like phenotype in experimental models and circulates at elevated levels in human preeclampsia. Removing sFlt-1 may benefit women with very preterm (Ͻ32 weeks) preeclampsia. Methods and Results-We first show that negatively charged dextran sulfate cellulose columns adsorb sFlt-1 in vitro. In 5 women with very preterm preeclampsia and elevated circulating sFlt-1 levels, we next demonstrate that a single dextran sulfate cellulose apheresis treatment reduces circulating sFlt-1 levels in a dose-dependent fashion. Finally, we performed multiple apheresis treatments in 3 additional women with very preterm (gestational age at admission 28, 30, and 27ϩ4 weeks) preeclampsia and elevated circulating sFlt-1 levels. Dextran sulfate apheresis lowered circulating sFlt-1, reduced proteinuria, and stabilized blood pressure without apparent adverse events to mother and fetus. Pregnancy lasted for 15 and 19 days in women treated twice and 23 days in a woman treated 4 times. In each, there was evidence of fetal growth. Conclusions-This pilot study supports the hypothesis that extracorporeal apheresis can lower circulating sFlt-1 in very preterm preeclampsia. Further studies are warranted to determine whether this intervention safely and effectively prolongs pregnancy and improves maternal and fetal outcomes in this setting. (Circulation. 2011;124:940-950.)Key Words: angiogenic factor Ⅲ apheresis Ⅲ preeclampsia P reeclampsia is a devastating medical complication of pregnancy associated with significant maternal and fetal morbidity and mortality. 1 The risk is highest in very preterm (Ͻ32 weeks) preeclampsia when the infant mortality rate is 70 times higher than at term. 2,3 Delivery of the placenta remains the only effective means to treat preeclampsia. Randomized trials have tested nonspecific interventions including antihypertensive agents; however, the ability of these and other interventions to prevent or stabilize the clinical manifestations and prolong pregnancy in preterm preeclampsia is limited. 4 -6 The underlying pathogenesis of preeclampsia has remained elusive, hampering successful development of targeted interventions for the condition. Clinical Perspective on p 950The prevailing hypothesis suggests that preeclampsia involves a placental factor that circulates to distal organs and causes damage to the vasculature. 7 We and others have suggested that excess placental derived soluble fms-like tyrosine kinase 1 (sFlt-1) or the soluble vascular endothelial growth factor (VEGF) receptor 1, an alternatively spliced variant of VEGF receptor 1, mediates the signs and symptoms of preeclampsia, and elevated circulating levels are associated with clinical preeclampsia. 8 -11 Circulating sFlt-1 levels in very preterm preeclampsia are among the highest obs...

The porcine lymphotropic herpesvirus 1 (PLHV-1), the first gammaherpesvirus of pigs, has been detected at a high prevalence in healthy pig populations. A porcine gammaherpesvirus has also been detected at high copy numbers in animals suffering from posttransplant lymphoproliferative disease (PTLD). While human PTLD is a EBV-associated complication following clinical transplantation, porcine PTLD is a disease recently described in pigs undergoing experimental allogeneic hematopoietic stem cell transplantation. Here we demonstrate that PLHV-1 and the virus present in porcine PTLD are indistinguishable, and present the characterization of 73 kbp of the genome of PLHV-1. We identified homologs of cellular genes, including a putative G protein-coupled receptor (GCR) as well as a viral homolog of the bcl-2 oncogene (v-bcl-2) and show significant transcription of these genes as well as of several other PLHV-1 genes in lymph nodes of a PTLD-affected pig. These data indicate that PLHV-1 is active during PTLD and may be involved in the etiology of this lymphoproliferative disease.

The porcine lymphotropic herpesviruses (PLHV) are discussed as possible risk factors in xenotransplantation because of the high prevalence of PLHV-1, PLHV-2 and PLHV-3 in pig populations world-wide and the fact that PLHV-1 has been found to be associated with porcine post-transplant lymphoproliferative disease. To provide structural and functional knowledge on the PLHV immediate-early (IE) transactivator genes, the central regions of the PLHV genomes were characterized by genome walking, sequence and splicing analysis. Three spliced genes were identified (ORF50, ORFA6/BZLF1(h), ORF57) encoding putative IE transactivators, homologous to (i) ORF50 and BRLF1/Rta, (ii) K8/K-bZIP and BZLF1/Zta and (iii) ORF57 and BMLF1 of HHV-8 and EBV, respectively. Expressed as myc-tag or HA-tag fusion proteins, they were located to the cellular nucleus. In reporter gene assays, several PLHV-promoters were mainly activated by PLHV-1 ORF50, to a lower level by PLHV-1 ORFA6/BZLF1(h) and not by PLHV-1 ORF57. However, the ORF57-encoded protein acted synergistically on ORF50-mediated activation.

Winkler et al raise an interesting point that perhaps lowering of soluble fms-like tyrosine kinase 1 (sFlt-1) may not have been the sole reason for the therapeutic benefit noted in our study, 1 and that lowering other substances such as low-density lipoprotein cholesterol by dextran sulfate cellulose (DSC) apheresis may have contributed to the benefit we observed. In addition, Winkler et al contend that the therapeutic benefit noted in a prior study by Wang et al 2 that used heparin-mediated extracorporeal low-density lipoprotein precipitation (HELP) apheresis may have been caused by lowering of low-density lipoprotein cholesterol. We agree with Winkler et al that we cannot conclude lowering sFlt-1 was the sole reason for the therapeutic benefit. Future clinical studies using specific apheretic columns (eg, sFlt-1 antibody columns) are needed to directly answer the contributing role of sFlt-1 in mediating preeclamptic signs and symptoms. We would like to point out that although lipid abnormalities frequently accompany preeclampsia, patients with familial hypercholesterolemia (who have the most dramatic lipid abnormalities) are not particularly prone to pregnancy complications such as preeclampsia, preterm delivery, or growth restriction. 3 The study by Wang et al 2 did not measure postapheresis sFlt-1 levels, and therefore, we are unable to comment specifically on the role of sFlt-1 reduction in that study. Because heparin use has been shown to mobilize sFlt-1 into the circulation, 4,5 it is critical to only use sFlt-1 levels measured after the effects of heparin have disappeared to evaluate for sFlt-1 reduction in any apheresis strategy.Espinoza raises an interesting point that perhaps the criteria used to exclude fetal growth restriction in our study should have been at the Ͻ10th percentile rather than Ͻ5th percentile. He argues that sFlt-1 release by the placenta may be an adaptive response and that overzealous reduction may further compromise fetal growth. We agree with Espinoza that maternal hypertension is likely secondary to severe placental disease in patients with severe very preterm preeclampsia and that aggressive reduction of maternal blood pressure may further compromise fetal growth. We therefore intentionally used a modified apheretic protocol that did not induce a substantial fall in blood pressure. Importantly, twice-weekly maternal and fetal Doppler studies did not show any deterioration of placental flow, and fetal growth was evident in all cases in which women were treated more than once. Because the majority of the patients with severe very preterm preeclampsia have fetal growth restriction, using a Ͻ10th percentile cutoff would deny offering this potentially important therapy to the vast majority of the patients. We therefore chose to only exclude subjects at Ͻ5th percentile and insisted in our protocol that all subjects have close fetal monitoring throughout the study period. Only randomized controlled studies will provide information on whether DSC apheresis can prolong pregnancy and impr...