Evidence of in vitro differential secretion of human beta-defensins-1, -2, and -3 after selective exposure to Streptococcus agalactiae in human fetal membranes

OBJECTIVE

The aim of this work was to characterize the individual contribution of the amnion (AMN) and choriodecidua (CHD) regions to the secretion of human beta defensins (HBD)-1, -2, and -3, after stimulation with Streptococcus agalactiae.

METHODS

Full-thickness membranes were mounted on a Transwell device, constituted by two independent chambers; 1 × 10(6) CFU/ml of S. agalactiae were added to either the AMN or CHD face or to both. Secretion profiles of HBD-1, HBD-2, and HBD-3 to the culture medium were quantified by enzyme-linked immunosorbent sandwich assay (ELISA).

RESULTS

Secretion profile of HBD-1 remained without significant changes; HBD-2 secretion level by the CHD increased 2.0 (2.73 ± 0.19 pg/μg) and 2.6 (3.62 ± 0.60 pg/μg) times when the stimulus was applied only to the CHD region and simultaneously to both compartments, respectively. The bacterial stimulation in the AMN induced a 2.0 times (2.06 ± 0.29 pg/μg) increase in this region. HBD-3 secretion level increased significantly in the CHD (15.65 ± 2.68 pg/μg) and the AMN (14.94 ± 1.85 pg/μg) only when both regions were stimulated simultaneously.

CONCLUSION

The stimulation of human fetal membranes with S. agalactiae induced a differential and tissue-specific profile of HBD-1, HBD-2, and HBD-3 secretion.

In vitro secretion and activity profiles of matrix metalloproteinases, MMP-9 and MMP-2, in human term extra-placental membranes after exposure to Escherichia coli

BACKGROUND

Premature rupture of fetal membranes (PROM) complicated with intrauterine infection has been associated to alterations of the extracellular matrix (ECM) homeostasis. The aim of this work was to evaluate the integral/functional response of the amnion (AMN) and choriodecidua (CHD) to synthesis, secretion, and activity of MMP-2 and MMP-9 and of their inhibitors TIMP-1, -2, and -4, after stimulation with Escherichia coli.

METHODS

Full-thickness membranes were mounted on a Transwell device, constituting two independent chambers, Escherichia coli (1×10 (6) CFU/mL) were added to either the amniotic or the choriodecidual face or to both. Secretion profiles of MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-4 were quantified by ELISA and gelatinolytic activity by zymography. Immunoreactivity for MMP-2 and MMP-9 was revealed by immunohistochemistry and the collagen content was assessed by the hydroxyproline assay.

RESULTS

Levels of MMP-9 in CHD and AMN increased 4- and 8-fold, respectively, after simultaneous infection. MMP-2 secreted to the medium by CHD increased a mean of 3 times after direct stimulation. Secretion profiles of TIMP-1, TIMP-2, and TIMP-4 remained without significant changes. Collagen content was significantly decreased (4-fold) in infected membranes, and was associated with loss of structural continuity and co-localization with immunoreactive forms of MMP-2 and MMP-9.

CONCLUSIONS

Infection of chorioamniotic membranes with E. coli induces an increase in the secretion of inactive forms and an association to ECM of active forms of MMP-2 and MMP-9 without changes in TIMP-1, -2, and -4. These changes could explain the significant decrease of collagen content and loss of structural continuity.

Tissue-specific human beta-defensins (HBD)1, HBD2, and HBD3 secretion from human extra-placental membranes stimulated with Escherichia coli

BACKGROUND

During an ascending infection along the reproductive tract, the extra-placental membranes must act as a selective and competent barrier against pathogens. Human beta defensins (HBD)1, HBD2, and HBD3 are key elements of innate immunity that are secreted to neutralize/control the progression of infection.

METHODS

Full-thickness membranes were mounted on a Transwell device, constituted by two independent chambers, 1 × 10(6) CFU/ml of Escherichia coli were added to either the amnion (AMN) or the choriodecidual (CHD) face or to both. Secretion profiles of HBD1, HBD2, and HBD3 to the culture medium were quantified by ELISA.

RESULTS

In comparison with basal conditions, the secretion profile of HBD1 remained without significant changes; HBD2 level in CHD and AMN increased 1.9- and 1.4-times, respectively, after stimulation with bacteria. HBD3 secretion level increased significantly (7.8 +/- 1.9 pg/micrograms) in the CHD but only if the stimulus was applied on the AMN side.

CONCLUSIONS

Selective stimulation of extra-placental membranes with E. coli, results in a tissue specific secretion of HBD1, HBD2, and HBD3 mainly in the CHD, which is the first infected region during an ascending infection.

In vitro secretion profiles of interleukin (IL)-1beta, IL-6, IL-8, IL-10, and TNF alpha after selective infection with Escherichia coli in human fetal membranes

BACKGROUND

Chorioamniotic membranes infection is a pathologic condition in which an abnormal secretion of proinflammatory cytokines halts fetal immune tolerance. The aim of the present study was to evaluate the functional response of human chorioamniotic membranes, as well as the individual contribution of the amnion and choriodecidua after stimulation with Escherichia coli, a pathogen associated with preterm labor.

METHODS

Explants of chorioamniotic membranes from 10 women (37-40 weeks of gestation) were mounted and cultured in a Transwell system, which allowed us to test the amnion and choriodecidua compartments independently. Escherichia coli (1 x 10 6 CFU/mL) was added to either the amniotic or the choriodecidual regions or both; after a 24-h incubation, the secretion of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10 in both compartments was measured using a specific ELISA. Data were analyzed by Kruskal-Wallis one-way analysis of variance.

RESULTS

After stimulation with Escherichia coli, the choriodecidua compartment showed an increase in the secretion of IL-1beta (21-fold), IL-6 (2-fold), IL-8 (6-fold), and IL-10 (37-fold), regardless of which side of the membrane was stimulated; TNFalpha secretion augmented (22-fold) also but only when the stimulus was applied simultaneously to both sides. When the amnion was stimulated directly, the level of IL-1beta (13-fold) rose significantly; however, the increase in IL-8 secretion was larger (20-fold), regardless of the primary site of infection. TNFalpha secretion in the amnion compartment rose markedly only when Escherichia coli was simultaneously applied to both sides.

CONCLUSION

Selective stimulation of fetal membranes with Escherichia coli results in a differential production of IL-1beta, IL-6, TNFalpha, IL-8, and IL-10. These tissues were less responsive when the amnion side was stimulated. This is in agreement with the hypothesis that the choriodecidua may play a primary role during an ascending intrauterine infection, being the main barrier to progression of the infection into the amniotic cavity. Therefore, the tissue-specific capacities for the secretion of these immune modulators could be a determining factor for the degree of severity of the inflammation process in fetal membranes.

Evidence of in vitro differential secretion of 72 and 92 kDa type IV collagenases after selective exposure to lipopolysaccharide in human fetal membranes

Premature rupture of chorioamniotic membranes complicated with intrauterine infection has been associated to degradation of extracellular matrix (ECM), which could explain local morphological changes. We used a culture system in which the chorioamniotic membranes form two independent chambers, allowing for the selective stimulation of either the amnion (AMN) and/or the choriodecidua (CHD) regions. Lipopolysaccharide (500 ng/ml) was added to the AMN and/or the CHD; secretions and gelatinolytic activity of matrix metalloproteinase (MMP)-2 and MMP-9 were measured in both compartments by enzyme-linked immunosorbent assay (ELISA) and zymography. Secretions of TIMP-1, TIMP-2 and TIMP-4 were measured by ELISA. Both metalloproteinases were immunolocalized in tissue sections. All stimulation modalities induced a similar proMMP-2 and proMMP-9 secretion pattern in the CHD with concentrations of 2.49 ng/ml and 90.91 pg/ml, respectively; the AMN showed no significant changes. The active forms of both enzymes did not change with any stimulation modality. TIMP-1, TIMP-2 and TIMP-4 secretions remained without significant changes (P = 0.41). ECM degradation and structural disarrangement were evident after stimulation. Secretion of proMMP-2 and proMMP-9 mainly in the CHD, presence of active forms associated to the tissue and minor changes in TIMPs secretion could favor ECM degradation and explain the weakening and thinning associated with the pathological rupture of chorioamniotic membranes.