13,172 research outputs found
Interleukin-1 receptor antagonist mediates toll-like receptor 3-induced inhibition of trophoblast adhesion to endometrial cells in vitro
STUDY QUESTION
Is interleukin-1 receptor antagonist (IL-1RA) involved in the toll-like receptor 3 (TLR 3)-induced inhibition of trophoblast cells' adhesion to endometrial cells in vitro?
SUMMARY ANSWER
IL-1RA mediates the TLR 3-induced inhibition of trophoblast cells' adhesion to endometrial cells in vitro.
WHAT IS KNOWN ALREADY
It is well documented that endometrial TLR 3 activation leads to impairment of trophoblast binding to endometrial cells in vitro. IL-1RA is known as an anti-implantation factor, as its injection significantly reduced implantation rates in mice by an effect on endometrial receptivity.
STUDY DESIGN, SIZE, DURATION
Poly I:C was used as a TLR3 specific ligand and endometrial cells were either treated or not with Poly I:C (treated versus control) in vitro. IL-1RA was applied to block IL-1 signal transduction. IL-1RA was knocked down by Accell Human IL1RN siRNA. Flagellin was used to stimulate TLR 5. SP600125 (JNK) was applied to inhibit the mitogen-activated protein kinases (MAPK) pathway. BAY11 -7082 was used to inhibit the nuclear factor-κB (NF-κB) pathway. The experiments were performed in three replicates on three separate days.
PARTICIPANTS/MATERIALS, SETTING, METHODS
An in vitro assay was developed using RL95-2 (an endometrial cell line) and JAr (a trophoblast cell line) cells. Initially, the production of IL-1RA in RL95-2 cells in response to TLR 3 activation was measured. To determine whether the TLR 3-induced inhibition of trophoblast binding was mediated through IL-1RA: (i) we evaluated the effect of IL-1RA on the attachment of trophoblast cells to endometrial cells; (ii) we knocked down TLR3-induced IL-1RA gene expression by IL-1RA Small interfering RNA (siRNA) and evaluated trophoblast attachment to endometrial cells. Finally, to clarify through which pathway TLR 3-induced inhibition of trophoblast binding occurs: (i) activation of NF-κB and MAPK was detected by transfecting the cells with secreted placental alkaline phosphatase reporter plasmids bearing promoter sequences for each transcription factor; (ii) the inhibitors for NF-κB and MAPK were used to block signaling; (iii) it was then investigated whether addition of these inhibitors could restore the TLR 3-induced impairment of trophoblast attachment to the endometrial cells.
MAIN RESULTS AND THE ROLE OF CHANCE
Our results showed that addition of polyinosinic:polycytidylic acid (Poly I:C) to RL95-2 cells significantly increased the production of IL-1RA (P < 0.05). Addition of human recombinant IL-1RA to RL95-2 cells remarkably decreased the adhesion rate of trophoblast cells to endometrial cells (P < 0.05). In addition, suppression of TLR3-induced IL-1RA gene expression in RL95-2 cells significantly restored trophoblast cells attachment to endometrial cells in the presence of Poly I:C (P < 0.05). Only TLR3 and not TLR5 induced MAPK activation (P < 0.05). TLR3 ligation did not affect NF-κB activation. Of NF-kB and MAPK inhibitors, only MAPK's inhibitor could achieve restoration of spheroid adhesion to endometrial cells (P < 0.05).
LIMITATIONS, REASONS FOR CAUTION
This study has been only done in vitro. Future in vivo studies will confirm our data.
WIDER IMPLICATIONS OF THE FINDINGS
The findings of this study have a potential clinical application in introducing IL-1RA as one of the diagnostic infertility markers in the endometrium, which can affect the process of embryo adhesion at the time of implantation. Moreover, based on the novel data obtained in the current study, blocking and regulating the MAPK pathway by its inhibitors can be used as a new strategy to prevent and treat virus-induced infertility cases in ART techniques.
STUDY FUNDING/COMPETING INTEREST
This study was partially funded by a Marie Curie IIF-253948 grant to I.C. and was partially funded by the author's institutions. The authors have no conflict of interest to declare
The metallicity - redshift relations for emission-line SDSS galaxies: examination of the dependence on the star formation rate
We analyse the oxygen abundance and specific star formation rates (sSFR)
variations with redshift in star-forming SDSS galaxies of different masses. We
find that the maximum value of the sSFR, sSFRmax, decreases when the stellar
mass, Ms, of a galaxy increases, and decreases with decreasing of redshift. The
sSFRmax can exceed the time-averaged sSFR by about an order of magnitude for
massive galaxies. The metallicity - redshift relations for subsamples of
galaxies with sSFR = sSFRmax and with sSFR = 0.1sSFRmax coincide for massive
(log(Ms/Mo) > 10.5, with stellar mass Ms in solar units) galaxies and differ
for low-mass galaxies. This suggests that there is no correlation between
oxygen abundance and sSFR in massive galaxies and that the oxygen abundance
correlates with the sSFR in low-mass galaxies. We find evidence in favour of
that the irregular galaxies show, on average, higher sSFR and lower oxygen
abundances than the spiral galaxies of similar masses and that the mass -
metallicity relation for spiral galaxies differs slightly from that for
irregular galaxies. The fact that our sample of low-mass galaxies is the
mixture of spiral and irregular galaxies can be responsible for the dependence
of the metallicity - redshift relation on the sSFR observed for the low-mass
SDSS galaxies. The mass - metallicity and luminosity - metallicity relations
obtained for irregular SDSS galaxies agree with corresponding relations for
nearby irregular galaxies with direct abundance determinations. We find that
the aperture effect does not make a significant contribution to the redshift
variation of oxygen abundances in SDSS galaxies.Comment: 14 pages, 7 figures, accepted for publication in the MNRA
Human Trophoblast Cells Modulate Endometrial Cells Nuclear Factor kappa B Response to Flagellin In Vitro
Background: Implantation is a complex process that requires a delicate cooperation between the immune and reproductive system. Any interference in the fine balance could result in embryo loss and infertility. We have recently shown that Toll-like receptor 5 activation results in a decrease of trophoblast cells binding to endometrial cells in an in vitro model of human implantation. However, little is known about the downstream signalling leading to the observed failure in implantation and the factors that modulate this immune response. Methods and Principal Findings: An in vitro model of embryo implantation was used to evaluate the effect of trophoblasts and flagellin on the activation of NF-kappa B in endometrial cells and whether TLR5-related in vitro implantation failure is signalled through NF-kappa B. We generated two different NF-kappa B reporting cell lines by transfecting either an immortalized endometrial epithelial cell line (hTERT-EECs) or a human endometrial carcinoma cell line (Ishikawa 3-H-12) with a plasmid containing the secreted alkaline phosphatase (SEAP) under the control of five NF-kappa B sites. The presence of trophoblast cells as well as flagellin increased NF-kappa B activity when compared to controls. The NF-kappa B activation induced by flagellin was further increased by the addition of trophoblast cells. Moreover, blocking NF-kappa B signalling with a specific inhibitor (BAY11-7082) was able to restore the binding ability of our trophoblast cell line to the endometrial monolayer. Conclusions: These are the first results showing a local effect of the trophoblasts on the innate immune response of the endometrial epithelium. Moreover, we show that implantation failure caused by intrauterine infections could be associated with abnormal levels of NF-kappa B activation. Further studies are needed to evaluate the target genes through which NF-kappa B activation after TLR5 stimulation lead to failure in implantation and the effect of the embryo on those genes. Understanding these pathways could help in the diagnosis and treatment of implantation failure cases
Quiet Sun magnetic fields from simultaneous inversions of visible and infrared spectropolarimetric observations
We study the quiet Sun magnetic fields using spectropolarimetric observations
of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648 and 15653 A.
Magnetic field strengths and filling factors are inferred by the simultaneous
fit of the observed Stokes profiles under the MISMA hypothesis. The
observations cover an intra-network region at the solar disk center. We analyze
2280 Stokes profiles whose polarization signals are above noise in the two
spectral ranges, which correspond to 40% of the field of view. Most of these
profiles can be reproduced only with a model atmosphere including 3 magnetic
components with very different field strengths, which indicates the
co-existence of kG and sub-kG fields in our 1.5" resolution elements. We
measure an unsigned magnetic flux density of 9.6 G considering the full field
of view. Half of the pixels present magnetic fields with mixed polarities in
the resolution element. The fraction of mixed polarities increases as the
polarization weakens. We compute the probability density function of finding
each magnetic field strength. It has a significant contribution of kG field
strengths, which concentrates most of the observed magnetic flux and energy.
This kG contribution has a preferred magnetic polarity, while the polarity of
the weak fields is balanced.Comment: 16 pages and 14 figure
PhyloFlu, a DNA Microarray for Determining the Phylogenetic Origin of Influenza A Virus Gene Segments and the Genomic Fingerprint of Viral Strains
Metal-THINGS: The association and optical characterization of SNRs with HI holes in NGC 6946
NGC~6946, also known as the `Fireworks' galaxy, is an unusual galaxy that
hosts a total of 225 supernova remnant (SNR) candidates, including 147
optically identified with high [SII]/Ha line ratios. In addition, this galaxy
shows prominent HI holes, which were analyzed in previous studies. Indeed, the
connection between SNRs and HI holes together with their physical implications
in the surrounding gas is worth of attention. This paper explores the
connection between the SNRs and the HI holes, including an analysis of their
physical link to observational optical properties inside and around the rims of
the holes, using new integral field unit (IFU) data from the Metal-THINGS
survey. We present an analysis combining previously identified HI holes, SNRs
candidates, and new integral field unit (IFU) data from Metal-THINGS of the
spiral galaxy NGC 6946. We analyze the distributions of the oxygen abundance,
star formation rate surface density, extinction, ionization, diffuse ionized
gas, and the Baldwin-Phillips-Terlevich classification throughout the galaxy.
By analyzing in detail the optical properties of the 121 previously identify HI
holes in NGC 6946, we find that the SNRs are concentrated at the rims of the HI
holes. Furthermore, our IFU data shows that the star formation rate and
extinction are enhanced at the rims of the holes. To a lesser degree, the
oxygen abundance and ionization parameter show hints of enhancement on the rims
of the holes.
Altogether, this provides evidence of induced star formation taking place at
the rims of the holes, whose origin can be explained by the expansion of
superbubbles created by multiple supernova explosions in large stellar clusters
dozens of Myr ago.Comment: Accepted by A&
Galaxy And Mass Assembly (GAMA) : galaxy close pairs, mergers and the future fate of stellar mass
ASGR acknowledges STFC and SUPA funding that were used to do this work. GAMA is funded by the STFC (UK), the ARC (Australia), the AAO and the participating institutions.We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 10(8) and 10(12)M(circle dot). Using the analytic form of this fit we investigate the total stellar mass accreting on to more massive galaxies across all mass ratios. Depending on how conservatively we select our robust merging systems, the fraction of mass merging on to more massive companions is 2.0-5.6 per cent. Using the GAMA-II data we see no significant evidence for a change in the close pair fraction between redshift z = 0.05 and 0.2. However, we find a systematically higher fraction of galaxies in similar mass close pairs compared to published results over a similar redshift baseline. Using a compendium of data and the function gamma(M) = A(1 + z)(m) to predict the major close pair fraction, we find fitting parameters of A = 0.021 +/- 0.001 and m = 1.53 +/- 0.08, which represents a higher low-redshift normalization and shallower power-law slope than recent literature values. We find that the relative importance of in situ star formation versus galaxy merging is inversely correlated, with star formation dominating the addition of stellar material below M* and merger accretion events dominating beyond M*. We find mergers have a measurable impact on the whole extent of the galaxy stellar mass function (GSMF), manifest as a deepening of the 'dip' in the GSMF over the next similar to Gyr and an increase in M* by as much as 0.01-0.05 dex.Publisher PDFPeer reviewe
The SAMI Galaxy Survey: the intrinsic shape of kinematically selected galaxies
Using the stellar kinematic maps and ancillary imaging data from the Sydney
AAO Multi Integral field (SAMI) Galaxy Survey, the intrinsic shape of
kinematically-selected samples of galaxies is inferred. We implement an
efficient and optimised algorithm to fit the intrinsic shape of galaxies using
an established method to simultaneously invert the distributions of apparent
ellipticities and kinematic misalignments. The algorithm output compares
favourably with previous studies of the intrinsic shape of galaxies based on
imaging alone and our re-analysis of the ATLAS3D data. Our results indicate
that most galaxies are oblate axisymmetric. We show empirically that the
intrinsic shape of galaxies varies as a function of their rotational support as
measured by the "spin" parameter proxy Lambda_Re. In particular, low spin
systems have a higher occurrence of triaxiality, while high spin systems are
more intrinsically flattened and axisymmetric. The intrinsic shape of galaxies
is linked to their formation and merger histories. Galaxies with high spin
values have intrinsic shapes consistent with dissipational minor mergers, while
the intrinsic shape of low-spin systems is consistent with dissipationless
multi-merger assembly histories. This range in assembly histories inferred from
intrinsic shapes is broadly consistent with expectations from cosmological
simulations.Comment: 15 pages, 11 figures, MNRAS in prin
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