Lactate dehydrogenase isoform activity mapping in patients with intra-amniotic infection
ABSTRACT Five distinct lactate dehydrogenase isoenzymes have been described. We sought to illustrate the specific amniotic fluid lactate dehydrogenase isoenzyme activity profiles in women with intra-amniotic infection.
Amniotic fluid was retrieved from 82 women who were stratified in the following groups: (1) positive amniotic fluid cultures (n = 23 women; gestational age, 26 weeks [range, 21-32 weeks]); (2) negative amniotic fluid cultures (n = 22 women; gestational age, 30 weeks [range, 16-36 weeks]); (3) second trimester control (normal genetic karyotype; n = 17 women; gestational age, 18 weeks [range, 16-22 weeks]); and (4) third trimester control (fetal lung maturity testing; n = 20 women; gestational age, 36 weeks [range, 31-38 weeks]). The optical density of each isoform was determined relative to a standard with 5 known lactate dehydrogenase isoenzyme activities. Total lactate dehydrogenase activity was measured by the clinical laboratory immediately after retrieval and by a kinetic UV spectrophotometric assay at the time of the isoelectric focusing.
Infection increased total lactate dehydrogenase activity: positive amniotic fluid cultures (median, 762.4 [range, 169.3-3374.8]) vs negative amniotic fluid cultures (median, 203.7 [range, 57.8-1939.3]; U/L; P < .001]). Lactate dehydrogenase isoform profiling identified significant and specific increases in lactate dehydrogenase isoforms 3, 4 (P < .01), and 5 (P < .05) in positive amniotic fluid cultures compared to the negative amniotic fluid cultures group. A selective up-regulation in lactate dehydrogenase isoform 5 was identified at term in healthy subjects.
Intra-amniotic infection is characterized by an increase in the activities of lactate dehydrogenase isoforms 3, 4, and 5; advancing gestational age demonstrates an up-regulation of isoform 5 only.
SourceAvailable from: Soghra Khani
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ABSTRACT: Classic IL-6 signaling is conditioned by the transmembrane receptor (IL-6R) and homodimerization of gp130. During trans-signaling, IL-6 binds to soluble IL-6R (sIL-6R), enabling activation of cells expressing solely gp130. Soluble gp130 (sgp130) selectively inhibits IL-6 trans-signaling. To characterize amniotic fluid (AF) IL-6 trans-signaling molecules (IL-6, sIL-6R, sgp130) in normal gestations and pregnancies complicated by intra-amniotic inflammation (IAI), we studied 301 women during second trimester (n = 39), third trimester (n = 40), and preterm labor with intact (n = 131, 85 negative IAI and 46 positive IAI) or preterm premature rupture of membranes (PPROM; n = 91, 61 negative IAI and 30 positive IAI). ELISA, Western blotting, and real-time RT-PCR were used to investigate AF, placenta, and amniochorion for protein and mRNA expression of sIL-6R, sgp130, IL-6R, and gp130. Tissues were immunostained for IL-6R, gp130, CD15(+) (polymorphonuclear), and CD3(+) (T cell) inflammatory cells. The ability of sIL-6R and sgp130 to modulate basal and LPS-stimulated release of amniochorion matrix metalloprotease-9 was tested ex vivo. We showed that in physiologic gestations, AF sgp130 decreases toward term. AF IL-6 and sIL-6R were increased in IAI, whereas sgp130 was decreased in PPROM. Our results suggested that fetal membranes are the probable source of AF sIL-6R and sgp130. Immunohistochemistry and RT-PCR revealed increased IL-6R and decreased gp130 expression in amniochorion of women with IAI. Ex vivo, sIL-6R and LPS augmented amniochorion matrix metalloprotease-9 release, whereas sgp130 opposed this effect. We conclude that IL-6 trans-signaling molecules are physiologic constituents of the AF regulated by gestational age and inflammation. PPROM likely involves functional loss of sgp130.The Journal of Immunology 03/2011; 186(5):3226-36. DOI:10.4049/jimmunol.1003587 · 5.36 Impact Factor
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