Elevated amniotic fluid nitric oxide metabolites and interleukin-6 in intra-amniotic infection.

OBJECTIVE: To compare amniotic fluid nitric oxide metabolites and interleukin-6 (IL-6) concentrations in patients with and without intra-amniotic infection. METHODS: Amniotic fluid nitric oxide metabolites, IL-6, Gram stains, glucose, leukocyte counts, leukocyte esterase activity, creatinine, pH, and specific gravity were determined in 14 patients with intra-amniotic infection and 26 patients without intra-amniotic infection. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture. The nitric oxide metabolites, nitrate and nitrite (NOx), were measured using Greiss reagent after reduction of nitrate to nitrite with aspergillus nitrate reductase. Interleukin-6 was measured by a two-site, enzyme-linked immunosorbent assay. Amniotic fluid nitric oxide metabolites and IL-6 concentrations were normalized by amniotic fluid creatinine levels. The Mann-Whitney U test, contingency table method, and Spearman's rank correlation test were used for statistical analyses. RESULTS: Amniotic fluid NOx and IL-6 levels were significantly higher in patients with intra-amniotic infection than in those without intra-amniotic infection (NOx: median = 2.06 mumol/mg creatinine, range = 0.74-6.81 versus 1.35 mumol/mg creatinine, range = 0.99-1.60, P = .01, IL-6: median = 2.00 micrograms/mg creatinine, range = 0.026-4.07 versus median = 0.04 micrograms/mg creatinine, range = 0.004-3.210, P = .0009, respectively). Patients with intra-amniotic infection had significantly elevated leukocyte counts, leukocyte esterase activity, Gram positive stains, and significantly lower amniotic fluid glucose levels compared with those without intra-amniotic infection. There were no differences in gestational age, maternal age, parity, race, pH, or specific gravity between the two groups. Amniotic fluid NOx was significantly correlated with IL-6 (r = .4, P = .02). Both amniotic fluid NOx and IL-6 were also positively correlated with amniotic fluid leukocyte counts, leukocyte esterase activity and Gram stains, and negatively correlated with glucose levels. CONCLUSIONS: Amniotic fluid NOx and IL-6 are significantly elevated and positively correlated during intra-amniotic infection. Both increased amniotic fluid IL-6 and nitric oxide may exert cytotoxic and cytostatic effects on the target cells. We suggest that measurements of amniotic fluid NOx and IL-6 may serve as useful clinical markers in patients with intra-amniotic infection.

The role of amniotic fluid interleukin-6, and cell adhesion molecules, intercellular adhesion molecule-1 and leukocyte adhesion molecule-1, in intra-amniotic infection.

PROBLEM: To determine amniotic fluid concentrations and correlations of interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and leukocyte adhesion molecule-1 (LAM-1) in patients with and without intra-amniotic infection. METHOD OF STUDY: Fourteen specimens with intra-amniotic infection and 45 without intra-amniotic infection were studied. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid IL-6, ICAM-1, and LAM-1 levels were determined by an enzyme-linked immunoassay, and normalized by amniotic fluid creatinine levels. RESULTS: Amniotic fluid concentrations of IL-6 and LAM-1 were significantly higher in patients with than without intra-amniotic infection. However, amniotic fluid ICAM-1 concentrations were not significantly different between two groups. Amniotic fluid IL-6, LAM-1, and ICAM-1 were positively correlated. CONCLUSIONS: Our data indicate that amniotic fluid IL-6 is significantly associated with an increased adhesion molecule expression in intra-amniotic infection. However, LAM-1 plays a more important role than ICAM-1 in intra-amniotic infection.

Elevated amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with intraamniotic infection.

OBJECTIVE: Our purpose was to compare amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with and without intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 72 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection and 58 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid Gram stain, glucose, leukocyte counts, leukocyte esterase activity, creatinine, pH, and specific gravity were performed. Endogenous nitrite was determined using Griess reagent. Amniotic fluid nitric oxide metabolites (nitrite and nitrate) were measured after reduction of nitrate to nitrite with Aspergillus nitrate reductase. Tests for amniotic fluid cyclic guanosine monophosphate levels were determined by enzyme immunoassay. Two-tailed t test, contingency table methods, linear regression, and correlation were used for statistical analyses. RESULTS: Amniotic fluid levels of nitric oxide metabolites, endogenous nitrite, nitrate, and cyclic guanosine monophosphate were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (2.66 +/- 0.49 vs 1.77 +/- 0.07 mumol/mg creatinine, p = 0.002; 0.69 +/- 0.15 vs 0.38 +/- 0.03 mumol/mg creatinine, p = 0.003; 1.99 +/- 0.41 vs 1.38 +/- 0.07 mumol/mg creatinine, p = 0.02; and 1.47 +/- 0.22 vs 0.90 +/- 0.08 nmol/mg creatinine, p = 0.004, respectively). Both amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate were positively correlated with amniotic fluid leukocyte counts and leukocyte esterase activity and negatively correlated with amniotic fluid glucose concentrations. CONCLUSIONS: Our data indicate that amniotic fluid nitric oxide and cyclic guanosine monophosphate may play important roles in the pathogenesis of intraamniotic infection. Measurements of amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate may be part of a panel of tests that can be used to detect intraamniotic infection.

The role of amniotic fluid L-selectin, GRO-alpha, and interleukin-8 in the pathogenesis of intraamniotic infection.

OBJECTIVE: Our purpose was to compare and correlate amniotic fluid GRO-alpha, interleukin-8, and L-selectin in patients with and without intraamniotic infection. STUDY DESIGN: Amniocentesis was performed on 45 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection, and 31 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid tests for Gram stain, glucose, neutrophil counts, creatinine, pH, and specific gravity were performed. Amniotic fluid levels of soluble L-selectin, interleukin-8, and GRO-alpha were measured by an enzyme-linked immunoassay and normalized by amniotic fluid creatinine levels. The Mann-Whitney Utest and Spearman's rank correlation test were used for statistical analyses. RESULTS: Amniotic fluid median levels of soluble L-selectin, interleukin-8, and GRO-alpha were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (soluble L-selectin: median 3334.6 ng/mg creatinine, range 408.4 to 15,956.8 vs 717.2 ng/mg creatinine, range 129.4 to 4601.9, p = 0.009; GRO-alpha: median 841.6 ng/mg creatinine, range 28.1 to 8591.7 vs 56.8 ng/mg creatinine, range 0.0 to 440.2, p < 0.0001; interleukin-8: median 4932.7 ng/mg creatinine, range 0.0 to 55,058.7 vs 28.3 ng/mg creatinine, range 0.0 to 1161.6, p = 0.0004). Patients with intraamniotic infection had significantly higher amniotic fluid leukocyte counts and leukocyte esterase activities and significantly lower amniotic fluid glucose concentrations compared with those without intraamniotic infection. Amniotic fluid GRO-alpha, interleukin-8, and soluble L-selectin were positively correlated, and each was positively correlated with amniotic fluid leukocytes and negatively correlated with amniotic fluid levels of glucose. CONCLUSIONS: Our data indicate amniotic fluid GRO-alpha and interleukin-8 may be two potent leukocyte chemoattractants and activators, and L-selectin is rapidly shed from leukocytes in the amniotic fluid in patients with intraamniotic infection.

Dual roles of amniotic fluid nitric oxide and prostaglandin E2 in preterm labor with intra-amniotic infection.

We hypothesized that induction of nitric oxide synthase and cyclo-oxygenase-2 by bacterial products in intra-amniotic infection could increase the production of proinflammatory nitric oxide and prostaglandin E2 (PGE2) and cause preterm labor. Thus, we sought to determine amniotic fluid levels of nitric oxide metabolites (NOx) and PGE2 in preterm labor patients with and without intra-amniotic infection. Amniotic fluid from 13 preterm labor patients with intra-amniotic infection and 24 without intra-amniotic infection were studied. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid was tested for NOx, PGE2, glucose, leukocyte counts, Gram stains, creatinine, pH, and specific gravity. NOx was determined using Griess reagent after reduction of nitrate to nitrite with aspergillus nitrate reductase. PGE2 was measured by an enzyme-linked immunoassay. Both amniotic fluid NOx and PGE2 were normalized by amniotic fluid creatinine. We found that amniotic fluid concentrations of NOx and PGE2 were significantly higher in preterm labor patients with intra-amniotic infection compared to those without intraamniotic infection (NOx: median 1.8 micromol/mg creatinine, range 0.7 to 6.8 vs. 1.3 micromol/mg creatinine, range 0.9 to 2.1, p=0.03; PGE2: median 33.5 ng/mg creatinine, range 0.0 to 1048.6 vs. 0.0 ng/mg creatinine, range 0.0 to 33.6, p=0.004). In addition, amniotic fluid NOx and PGE2 were positively correlated (r=0.343, p=0.0398). We conclude that there may be an interaction between the nitric oxide and prostaglandin pathways in intraamniotic infection. Increased production of amniotic fluid pro-inflammatory nitric oxide and PGE2 may play an important role in the pathogenesis of preterm labor in patients with intra-amniotic infection.

Elevated amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in intra-amniotic infection.

OBJECTIVE: The study's objective was to determine and correlate amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in patients with and without intra-amniotic infection. STUDY DESIGN: Amniocentesis was performed on 41 pregnant women with preterm contractions, labor, or premature rupture of membranes. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture result. Amniotic fluid tests for Gram stain, glucose, leukocyte counts, creatinine level, pH, and specific gravity were performed. Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were measured by an enzyme-linked immunoassay. Unlike in previous reports, cytokines were normalized by amniotic fluid creatinine levels. RESULTS: Fifteen patients had intra-amniotic infection and 26 did not. Amniotic fluid median levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were significantly higher in pregnant women with intra-amniotic infection than in those without intra-amniotic infection (leukemia inhibitory factor median 3912 pg/mg creatinine, range 0.0-199314, vs 56 pg/mg creatinine, range 0. 0-12148, P =.01; interleukin 6 median 2005 ng/mg creatinine, range 27-4071, vs 990 ng/mg creatinine, range 7.5-3409, P =.005; interleukin 8: median 4933 ng/mg creatinine, range 0.0-55058, vs 61 ng/mg creatinine, range 0.0-2399, P =.005). Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were positively correlated. CONCLUSIONS: The data indicate that leukemia inhibitory factor plays an important role in the pathogenesis of intra-amniotic infection. In addition, significant elevations of and correlations among amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 suggest that measurements of these cytokines in amniotic fluid may be of diagnostic and prognostic importance.

Nitric oxide: a clinically important amniotic fluid marker to distinguish between intra-amniotic mycoplasma and non-mycoplasma infections.

The objective of this study was to determine whether the measurements of amniotic fluid nitric oxide metabolite (NOx: nitrate + nitrite) concentrations could be a clinically useful marker to differentiate between intra-amniotic mycoplasma and nonmycoplasma infections. Amniocentesis was performed on 76 pregnant women with suspicion of intra-amniotic infection. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture with either mycoplasma or nonmycoplasma infections. Rapid amniotic fluid tests for Gram stain, glucose, leukocyte counts, interleukin-6, and NOx were performed. Amniotic fluid NOx was measured with aspergillus nitrate reductase and Griess reagent. Interleukin-6 was determined by enzyme immunoassays. Amniotic fluid NOx and interleukin-6 were normalized by amniotic fluid creatinine levels. Patients with intra-amniotic mycoplasma (n = 7) and nonmycoplasma infections (n = 8) had significantly higher amniotic fluid leukocyte counts and interleukin-6 concentrations and significantly lower amniotic fluid glucose levels than noninfected controls (n = 61). Amniotic fluid concentrations of NOx were significantly higher in those with intraamniotic nonmycoplasma infection as compared to those with intraamniotic mycoplasma infection and noninfected controls (NOx: 3.35+/-0.74 vs. 2.03+/-0.41 micromol/mg creatinine, p = 0.005, and 3.35+/-0.74 vs. 1.72+/-0.07 micromol/mg creatinine, p < 0.0001, respectively). However, patients with intra-amniotic mycoplasma infection did not differ significantly from noninfected controls. Our data indicate that clinical characteristics of intra-amniotic mycoplasma infection may differ from intra-amniotic nonmycoplasma infection. As delivery is not always indicated in intra-amniotic mycoplasma infection, elevated rapid amniotic fluid tests (leukocyte counts, interleukin-6, and glucose) may not be appropriate in the clinical management of intra-amniotic mycoplasma infection. In addition to these rapid amniotic fluid tests, incorporation of the measurement of amniotic fluid NOx may be of clinical importance in the differentiation and management of patients with suspected intra-amniotic mycoplasma and nonmycoplasma infection.