Predominant production of amniotic interleukin-1 alpha in cases with premature rupture of the membranes

Can levels of interleukins and matrix metalloproteinases in the amniotic fluid predict postnatal bowel function in fetuses with gastroschisis?

PURPOSE

The aim of this study was to determine whether interleukin or matrix metalloproteinase (MMP) levels in the amniotic fluid can predict the postnatal condition of the bowel in fetuses with gastroschisis (GS).

METHODS

Eleven pregnant women with a fetus with GS underwent amniocentesis. Levels of IL-1alpha, IL-1beta, and IL-6 were measured in 10 of 11 specimens, and MMP-1, MMP-3, and MMP-8 levels were measured in 7 of 11 specimens. Neonates who tolerated complete oral feeding within 21 days were considered to have good bowel status (GS/good: n = 4, 4 in interleukin study or 3 in MMP study); those who did not were considered to have poor bowel status (GS/poor: n =7, 6 in interleukin study or 4 in MMP study). Seventy-eight women undergoing amniocentesis for other reasons served as controls.

RESULTS

Interleukin-1 levels were considerably lower in the pregnancies complicated by GS than in controls. Matrix metalloproteinases 3 and 8 levels were significantly higher in the GS pregnancies than in controls. Neonates with poor bowel status had higher MMP-3 and MMP-8 levels than those with good bowel status.

CONCLUSION

Amniotic fluid MMP-3 and MMP-8 levels may prove useful to assess the condition of the bowel in fetuses with GS.

Cytokines and other important inflammatory mediators in gestation and bacterial intraamniotic infections

Intraamniotic infections caused by viruses, bacteria or mycoplasmas are frequently followed by damage of fetus or increased perinatal morbidity and mortality. Cytokines are key substances regulating a number of biological processes including reproductive and inflammatory processes. An association between intraamniotic infections, rising concentrations of inflammatory cytokines in amniotic fluid and preterm labor is suggested. A great effort is made to find reliable markers typical for intraamniotic infections with high predictive value that make possible prompt identification of patients with intraamniotic infection. This review concerns inflammatory mediators, especially IL-1, IL-6, IL-8, TNF-alpha, and other important biologically active substances as prostaglandins and NO metabolites and their roles in intraamniotic infections. Finally, we discuss their relevance for diagnosis of intraamniotic infections.

Intrarenal handling of recombinant human interleukin-1alpha in rats: mechanism for proximal tubular protein reabsorption

The intrarenal distribution of recombinant human interleukin (IL)-la was studied in Sprague-Dawley male rats by immunohistochemical staining. The effects of the concurrent administration of various proteins or synthetic polypeptides on the urinary excretion of IL-1alpha were also studied to clarify the mechanism(s) for the reabsorption of IL-la in the renal tubules. Microscopic immunohistochemistry showed that IL-1alpha distributed to early proximal convoluted tubules but not to glomeruli, Henle's loops, distal tubules, or collecting ducts. Electron microscopic immunohistochemistry showed that IL-la was taken up into the endocytic vesicle located close to the apical membrane of the proximal tubular epithelial cells, then accumulated in lysosomes. Urinary excretion of intravenous IL-la at 500 microg/kg was extremely low, accounting for only 0.014% of the dose administered. The coadministration of intravenous human serum albumin did not affect the urinary excretion of IL-1alpha, whereas trypsinogen, myoglobin, and trypsin inhibitor dose-dependently produced an increase in the excretion of IL-la, the potency of which was greatest in that order. Poly-L-lysine, but not poly-L-glutamic acid dose-dependently increased the urinary excretion of IL-1alpha. These results indicate that most of the glomerular filtrated IL-1alpha could be easily reabsorbed into the proximal tubular cells via endocytosis, and the reabsorption was inhibited by coadministered low molecular weight proteins, particularly basic proteins. This result suggests that scavengers with a negative charge and broad binding ability for glomerular filtered proteins exist on the surface of the apical membrane of proximal tubular cells and play an important role in the reabsorption of filtered proteins.

Utilization of endoscopic inoculation in a mouse model of intrauterine infection-induced preterm birth: role of interleukin 1beta

A novel murine model of intrauterine infection/inflammation-induced preterm birth based on direct endoscopic intracervical inoculation is described. Using this model, we investigated infection-induced premature pregnancy loss in normal and interleukin (IL) 1beta-deficient mice. Seventy-four CD-1, HS, C57BL/6J wild type (IL-1beta+/+), and C57BL/6J IL-1beta-deficient (IL-1beta-/-) mice were inoculated intracervically using a micro-endoscope, at a time corresponding to 70% of average gestation. Intracervical injection of lipopolysaccharide (LPS) or Escherichia coli reliably induced premature birth: 100% of mice intracervically injected with LPS and 92% of mice with a positive endometrial E. coli culture delivered prematurely within 36 h after inoculation. No losses were observed in mice inoculated with saline. Pregnancy loss was associated with increased uterine tissue cyclooxygenase-2 gene expression and uterine content of IL-1beta, tumor necrosis factor alpha, macrophage inflammatory protein-1alpha, and IL-6, as well as elevation of nuclear factor-kappaB activity in uterine tissues. Although IL-1beta-/- mice exhibited decreased uterine cytokine production in response to bacteria and LPS, IL-1beta deficiency did not affect the rate of pregnancy loss. This model using direct intracervical bacterial or LPS inoculation is useful for studying preterm pregnancy loss in genetically altered mice in order to develop novel interventions for infection-associated preterm labor.

IL-1 alpha induces inducible nitric oxide synthase in uterine smooth muscle

In a previous report, we have identified interleukin-1 alpha (IL-1 alpha) in amniotic fluid of women with premature rupture of the amniotic membrane (PROM), and suggested that this cytokine may play a role in the development of the fetus. To clarify the functional role of amniotic IL-1 alpha, we studied its effect on the induction of nitric oxide (NO) synthesis in the uterus. IL-1 alpha administered intraperitoneally to rats induced an increase in the amount of mRNA encoding the macro-phage-type iNOS which was determined by reverse transcription-polymerase chain reaction. NO measurement by NO selective electrode revealed that NO production in the rat and human uterus treated with IL-1 alpha was promoted by the addition of 1 mM L-arginine to the culture medium. These findings suggest that in women with PROM, amniotic IL-1 alpha may reduce uterine contractions, in part, by inducing of iNOS.

Antibiotic therapy for preterm premature rupture of the membranes

Amniotic fluid studies and placental histopathological evaluation have confirmed the association between intrauterine infection and preterm premature rupture of the membranes (pPROM). This association is increasingly strong with pPROM at early gestational ages. The organisms associated with pPROM include a broad spectrum of aerobic and anaerobic gram-positive and gram-negative bacteria. In many cases, the patient presenting with pPROM will have overt intrauterine infection necessitating delivery. For those amenable to expectant management, the clinical course is usually of brief latency between membrane rupture and delivery. A number of well-designed prospective clinical trials have evaluated the utility of antibiotic treatment during the expectant management of pPROM. Taken together, these studies suggest broad spectrum antibiotic treatment of this population to enhance pregnancy prolongation, and to reduce maternal and neonatal infectious morbidity. There are some data suggesting the potential for a reduction in neonatal gestational age-dependent morbidity. We recommend aggressive adjunctive antibiotic treatment to prolong pregnancy and reduce morbidity in patients with pPROM, at gestations remote from term, when a significant improvement in neonatal outcome can anticipated with expectant management.