Placental and Fetal Membrane Nephrin and Neph1 Gene Expression: Response to Inflammation

Abstract

Objective: Fetal and amniotic fluid (AF) proteins (eg, alpha fetoprotein [AFP]) are measurable in the maternal circulation. Elevated maternal serum AFP levels indicate a risk for fetal anomalies or for obstetrical complications that are often associated with inflammation (eg, preterm labor). However, little is known of the mechanism of protein exchange between the fetus, AF, and maternal circulation. Nephrin and Neph1 are cell membrane proteins that restrict glomerular protein filtration and which are differentially expressed with renal inflammation. We sought to investigate whether nephrin and Neph 1 were expressed in placenta and fetal membranes, and whether inflammation modifted the expression.

Methods: Pregnant rats at 18 days' gestation were injected with lipopolysacchride (LPS) or control saline intraperitoneally (IP) and killed at 1, 6, and 12 hours after injection. Placenta and fetal membranes were obtained and real-time polymerase chain reaction (PCR) performed for determination of nephrin and Neph1 levels.

Results: Nephrin and Neph1 were expressed in both placenta and fetal membranes. Following maternal LPS administration, nephrin mRNA significantly increased in the membranes (0.22 ± 0.02 to 0.51 ± 0.050, P ≤. 05), while Neph 1 expression significantly declined in the placenta (0. 19 ± 0.05 to .10 ± 0.01, P.05).

Conclusion: Fetal membranes and placenta of the rat express mRNA for the protein barriers nephrin and Neph 1, suggesting a role in the regulation of protein transfer from the fetus to mother. Under basal conditions, AF AFP transfer across fetal membranes may account for maternal serum AFP levels, whereas gestational inflammatory conditions (eg, preterm labor, threatened abortion) may augment AFP transfer across the placenta.

Keywords

Amniotic fluid nephrin placenta Nephl inflammation

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References

1. Pitkin RM , Reynolds WA . Fetal ingestion and metabolism of amniotic fluid protein. Am J Obstet Gynecol 1975;123:356-363.

2. Mann SE , Lee JJ , Ross MG . Ovine intramembranous pathway permeability: Use of solute clearance to determine membrane porosity. J Matern Fetal Med 2001;10:335-340.

3. Haddow JE , Macri JN , Munson M . The amnion regulates movement of fetally derived alpha-fetoprotein into maternal blood. J Lab Clin Med 1979;94:344-347.

4. Shobokshi A , Shaarawy M . Maternal serum and amniotic fluid cytokines in patients with preterm premature rupture of membranes with and without intrauterine infection. Int J Gynaecol Obstet 2002;79:209-215.

5. Arntzen KJ , Kjollesdal AM , Halgunset J , Vatten L , Austgulen R . TNF, IL-1, IL-6, IL-8 and soluble TNF receptors in relation to chorioamnionitis and premature labor. J Perinat Med 1998;26: 17-26.

6. Liu G , Kaw B , Kurfis J , Rahmanuddin S , Kanwar YS , Chugh SS . Nephl and nephrin interaction in the slit diaphragm is an important determinant of glomerular permeability.J Clin Invest 2003;112:209-221.

7. Khoshnoodi J , Sigmundsson K , Ofverstedt LG , et al. Nephrin promotes cell-cell adhesion through homophilic interactions.Am J Pathol 2003;163:2337-2346.

8. Toyoda M , Suzuki D , Umezono T , et al. Expression of human nephrin mRNA in diabetic nephropathy.Nephrol Dial Transplant 2004;19:380-385.

9. Bruewer M , Luegering A , Kucharzik T , et al. Proinflammatory cytokines disrupt epithelial barrier function by apoptosisindependent mechanisms.J Immunol 2003;171:6164-6172.

10.

10. McCarthy ET , Sharma R , Sharma M , et al. TNF-alpha increases albumin permeability of isolated rat glomeruli through the generation of superoxide.J Am Soc Nephrol 1998;9:433-438.

11.

11. Huwiler A , Ren S , Holthofer H , Pavenstadt H , Pfeilschifter J . Inflammatory cytokines upregulate nephrin expression in human embryonic kidney epithelial cells and podocytes. Biochem Biophys Res Commun 2003;305:136-142.

12.

12. Gayle DA , Beloosesky R , Desai M , Amidi F , Nunez SE , Ross MG . Maternal LPS induces cytokines in the amniotic fluid and corticotropin releasing hormone in the fetal rat brain. Am J Physiol Regul Integr Comp Physiol 2004;286:R1024-R1029.

13.

13. Chugh SS , Kaw B , Kanwar YS . Molecular structure-function relationship in the slit diaphragm. Semin Nephrol 2003;23: 544-555.

14.

14. LyJ , Alexander M , Quaggin SE . A podocentric view of nephrology. Curr Opin Nephrol Hypertens 2004;13:299-305.

15.

15. Kuusniemi AM , Kestila M , Patrakka J , et al. Tissue expression of nephrin in human and pig. Pediatr Res 2004;55:774-781.

16.

16. Putaala H , Soininen R , Kilpelainen P , Wartiovaara J , Tryggvason K . The murine nephrin gene is specifically expressed in kidney, brain and pancreas: Inactivation of the gene leads to massive proteinuria and neonatal death. Hum Mol Genet 2001;10:1-8.

17.

17. Liu L , Aya K , Tanaka H , Shimizu J , Ito S , Seino Y . Nephrin is an important component of the barrier system in the testis. Acta Med Okayama 2001;55:161-165.

18.

18. Lai PC , Forrester PI , Hancock RL , Hay DM , Lorscheider FL . Rat alpha-fetoprotein: isolation, radioimmunoassay and fetalmaternal distribution during pregnancy. J Reprod Fertil 1976;48:1-8.

19.

19. Crandall BF . Alpha-fetoprotein: A review. Crit Rev Clin Lab Sci 1981;15:127-185.

20.

20. Van Lith JM , Beekhuis JR , Van Loon AJ , Mantingh A , De Wolf BT , Breed AS . Alpha-fetoprotein in fetal serum, amniotic fluid, and maternal serum. Prenat Diagn 1991;11:625-628.

21.

21. Spencer K , Muller F , Aitken DA . Biochemical markers of trisomy 21 in amniotic fluid. Prenat Diagn 1997;17:31-37.

22.

22. Kronquist KE , Dreazen E , Keener SL , Nicholas TW , Crandall BF . Reduced fetal hepatic alpha-fetoprotein levels in Down's syndrome. Prenat Diagn 1990;10:739-751.

23.

23. Brizot ML , Mckie AT , von Kaisenberg CS , Farzaneh F , Nicolaides KH . Fetal hepatic alpha-fetoprotein mRNA expression in fetuses with trisomy 21 and 18 at 12-15 weeks gestation. Early Hum Dev 1996;44:155-159.

24.

24. Chandra S , Scott H , Dodds L , Watts C , Blight C , Van Den HM . Unexplained elevated maternal serum alpha-fetoprotein and/or human chorionic gonadotropin and the risk of adverse outcomes. Am J Obstet Gynecol 2003;189:775-781.

25.

25. Krause TG , Christens P , Wohlfahrt J , et al. Second-trimester maternal serum alpha-fetoprotein and risk of adverse pregnancy outcome(l). Obstet Gynecol 2001;97:277-282.

26.

26. Wenstrom KD , Owen J , Davis RO , Brumifield CG . Prognostic significance of unexplained elevated amniotic fluid alphafetoprotein. Obstet Gynecol 1996;87:213-216

27.

27. Chaiworapongsa T , Romero R , Tolosa JE , et al. Elevated monocyte chemotactic protein-1 in amniotic fluid is a risk factor for pregnancy loss. J Matern Fetal Neonatal Med 2002;12:159-164.