Evidence for participation of neutrophil gelatinase-associated lipocalin/matrix metalloproteinase-9 (NGAL•MMP-9) complex in the inflammatory response to infection in pregnancies complicated by preterm birth

Protein microarray analysis of amniotic fluid proteins associated with spontaneous preterm birth in women with preterm labor

PROBLEM

To identify proteins present in the amniotic fluid (AF) that could be associated with spontaneous preterm birth (SPTB; delivery < 7 days) in women with preterm labor (PTL).

METHOD OF STUDY

First, the AF proteome of 20 women with PTL and SPTB was compared with that of 20 matched women with term deliveries using an antibody microarray. Next, nine identified candidate biomarkers of SPTB were further validated in 267 singleton pregnant women with PTL who underwent amniocentesis at 26-33 weeks of gestation using ELISA, and whether the degree of expression of these proteins was associated with the risk severity for subsequent SPTB was retrospectively assessed.

RESULTS

Of the 507 proteins evaluated in the microarray analysis, 27 displayed significant intergroup differences. In particular, ELISA quantification confirmed that the expression of EN-RAGE, IL-6, IL-8, IP-10, lipocalin-2, MMP-8, MMP-9, S100 A8/A9, and TNFR2 were all increased in the AF of women spontaneously delivering within 7 days of sampling compared with those delivering after 7 days. Moreover, the odds of SPTB within 7 days, even upon adjusting for confounders, tended to significantly increase with each increasing quartile of baseline AF levels of each protein (P-value for trend < .05).

CONCLUSION

Nine AF proteins were found to be independently associated with higher risk of subsequent SPTB in women with PTL, all of which were immune-, inflammation-, and extracellular matrix-related proteins. Moreover, risk severity for this subsequent SPTB is closely related to the degree of expression of each of these proteins.

The Role of Innate Immune System in the Human Amniotic Membrane and Human Amniotic Fluid in Protection Against Intra-Amniotic Infections and Inflammation

Intra-amniotic infection and inflammation (IAI) affect fetal development and are highly associated with preterm labor and premature rupture of membranes, which often lead to adverse neonatal outcomes. Human amniotic membrane (hAM), the inner part of the amnio-chorionic membrane, protects the embryo/fetus from environmental dangers, including microbial infection. However, weakened amnio-chorionic membrane may be breached or pathogens may enter through a different route, leading to IAI. The hAM and human amniotic fluid (hAF) respond by activation of all components of the innate immune system. This includes changes in 1) hAM structure, 2) presence of immune cells, 3) pattern recognition receptors, 4) cytokines, 5) antimicrobial peptides, 6) lipid derivatives, and 7) complement system. Herein we provide a comprehensive and integrative review of the current understanding of the innate immune response in the hAM and hAF, which will aid in design of novel studies that may lead to breakthroughs in how we perceive the IAI.

Identification of Novel Choroidal Neovascularization-Related Genes Using Laplacian Heat Diffusion Algorithm

Choroidal neovascularization (CNV) is a type of eye disease that can cause vision loss. In recent years, many studies have attempted to investigate the major pathological processes and molecular pathogenic mechanisms of CNV. Because many diseases are related to genes, the genes associated with CNV need to be identified. In this study, we proposed a network-based approach for identifying novel CNV-associated genes. To execute such method, we first employed a protein-protein interaction network reported in STRING. Then, we applied a network diffusion algorithm, Laplacian heat diffusion, on this network by selecting validated CNV-related genes as the seed nodes. As a result, some novel genes that had unknown but strong relationships with validated genes were identified. Furthermore, we used a screening procedure to extract the most essential genes. Eleven latent CNV-related genes were finally obtained. Extensive analyses were performed to confirm that these genes are novel CNV-related genes.

Up-regulation of matrix metalloproteinases-9 in the kidneys of diabetic rats and the association with neutrophil gelatinase-associated lipocalin

Background

Matrix metalloproteinases-9 (MMP-9) can regulate extracellular matrix deposition in diabetic glomerular injury. However, it remains unknown whether MMP-9 is involved in the renal tubular injury. Meanwhile, neutrophil gelatinase-associated lipocalin (NGAL), defined as a biomarker of proximal tubular injury, may influence MMP-9 by forming the MMP-9/NGAL complex. The aim of this study was to investigate MMP-9 expression in proximal renal tubules and the relationship of MMP-9 and NGAL in diabetic rat model treated with Valsartan.

Methods

Sprague Dawley rats were randomly divided into three groups: Diabetic group, Control group, and Treated group. The diabetic rat model was established by injection of streptozotocin. Related indexes were measured at the end of the 2nd, 4th, 8th and 12th week post-modeling.

Results

In diabetic groups, the concentrations of MMP-9 markedly increased in the serum and urine of rats in the early stage, even before the appearance of pathological albuminuria. Markedly elevated MMP-9/NGAL complex concentrations were also tested in diabetic groups. Western blot and qPCR tests confirmed that MMP-9 expression levels in the proximal renal tubular epithelial cells of diabetic rats were significantly higher than in control groups (P < 0.05). Correlation analysis showed that MMP-9 was positively correlated with NGAL at both protein and gene expression levels. In addition, Valsartan observably reduced tubular injury as well as MMP-9 expression in diabetic rats.

Conclusions

In diabetic kidney injury, the expression of MMP-9 in the proximal renal tubular epithelial cells was significantly increased. Besides, a positive correlation was found between MMP-9 and NGAL expression, along with high levels of MMP-9/NGAL complex, which indicated that NGAL might participate in the regulation of MMP-9 expression. The administration of Valsartan may reduce this effect.

A protein microarray analysis of amniotic fluid proteins for the prediction of spontaneous preterm delivery in women with preterm premature rupture of membranes at 23 to 30 weeks of gestation

Objective

We sought to identify novel biomarkers in the amniotic fluid (AF) related to imminent spontaneous preterm delivery (SPTD) (≤ 14 days after sampling) in women with early preterm premature rupture of membranes (PPROM), using a protein microarray.

Method

This was a retrospective cohort study of a total of 88 singleton pregnant women with PPROM (23+0 to 30+6 weeks) who underwent amniocentesis. A nested case-control study for biomarker discovery was conducted using pooled AF samples from controls (non-imminent delivery, n = 15) and cases (imminent SPTD, n = 15), which were analyzed using an antibody microarray. Quantitative validation of four candidate proteins was performed, using ELISA, in the total cohort (n = 88). IL-8, MMP-9, and Fas levels were additionally measured for the comparison and to examine association of SPTD with the etiologic factors of PPROM.

Results

Of all the proteins studied in the protein microarray, four showed significant intergroup differences. Analyses of the total cohort by ELISA confirmed the significantly elevated concentrations of AF lipocalin-2, MMP-9, and S100 A8/A9, but not of endostatin and Fas, in women who delivered within 14 days of sampling. For inflammatory proteins showing a significant association, the odds of SPTD within 14 days increased significantly with an increase in baseline AF levels of the proteins (P for trend <0.05 for each) in each quartile, especially in the 3rd and 4th quartile.

Conclusions

We identified several potential novel biomarkers (i.e., lipocalin-2, MMP-9, and S100 A8/A9) related to SPTD within 14 days of sampling, all of which are inflammation-related molecules. Furthermore, the SPTD risk increased with increasing quartiles of each of these inflammatory proteins, especially the 3rd and 4th quartile of each protein. The present findings may highlight the importance of inflammatory mechanisms and the degree of activated inflammatory response in developing SPTD in early PPROM.

Identifying potential biomarkers related to pre-term delivery by proteomic analysis of amniotic fluid

We sought to identify biomarkers in the amniotic fluid (AF) and specific signaling pathways related to spontaneous preterm delivery (SPTD, < 34 weeks) in women with preterm labor (PTL) without intra-uterine infection/inflammation (IUI). This was a retrospective cohort study of a total of 139 PTL women with singleton gestation (24 + 0 to 32 + 6 weeks) who underwent amniocentesis and who displayed no evidence of IUI. A nested case-control was conducted using pooled AF samples (n = 20) analyzed via label-free liquid chromatography-tandem mass spectrometry. In the total cohort, an ELISA validation study was performed for seven candidate proteins of interest. Proteomic analysis identified 77 differentially expressed proteins (DEPs, P < 0.05) in the AF from SPTD cases compared to term delivery controls. ELISA validation confirmed that women who had an SPTD before 34 weeks had significantly independently lower levels of VEGFR-1 and higher levels of lipocalin-2 and the Fc fragment of IgG binding protein in the AF. Five principle pathways associated with the 77 DEPs were identified, including glycolysis, gluconeogenesis, and iron homeostasis. The proteomic analysis data of AFs from women with PTL identified several novel biomarkers and specific protein pathways related to SPTD in the absence of IUI.

α-Lipoic acid blocks the GMCSF induced protease/protease inhibitor spectrum associated with fetal membrane weakening in-vitro

INTRODUCTION

We use an in-vitro human fetal membrane (FM) explant-based model to study inflammation-induced FM weakening, a prerequisite for PPROM. In this system, GMCSF is a critical intermediate, both necessary and sufficient for TNFα and thrombin induced FM weakening. α-Lipoic-acid (LA) blocks TNFα and thrombin, as well as GMCSF-induced weakening. Recently, we reported LA concomitantly blocks GMCSF-induction of MMPs 2, 9 and 10 and inhibition of TIMPs 1-3. The aim of this study was to show that LA blocks GMCSF-induced increases in additional proteases and reductions in additional protease inhibitors.

METHODS

FM fragments were cultured±LA and then±GMCSF. In other experiments, weak versus strong, fresh FM were cultured without additions. Fragments were strength tested and media analyzed by multiplex protein ELISA for proteases and protease inhibitors.

RESULTS

GMCSF induced FM weakening and concomitantly increased several Proteases (Cathepsin-S, Proteinase-3, Elastase-2) and decreased several protease inhibitors (NGAL, Cystatin-C, HE4 and Thrombospondin1). LA inhibited GMCSF-induced FM weakening and all enzymatic changes. Untreated weaker versus stronger regions of fresh FM showed comparable differences in proteases and protease inhibitor patterns to GMCSF-stimulated versus controls.

CONCLUSION

LA blocks GMCSF-induced human FM weakening and associated protease increases and inhibitor decreases. The GMCSF-induced spectrum of protease/protease-inhibitor changes is similar to that in the natural weak FM fragments. In concert with previously reported GMCSF-induced changes in MMPs & TIMPs, these other protease and protease-inhibitor changes presumably facilitate FM weakening and rupture. LA blocks these GMCSF effects and therefore may be a useful agent to prevent PPROM.

Some more about dogs: Proteomics of neglected biological fluids

We report in this manuscript what is known about the protein makeup of a selection of biological fluids in the domestic dog. The samples we review - amniotic and allantoic fluid, seminal fluid, saliva, bile, synovial fluid, tears - are still very poorly characterized in this species. For some of them we can present results from our own, mainly unpublished experiments. SIGNIFICANCE: The dog is one of the most widespread companion animals, and also of medical relevance as model species for some human diseases. Still, investigation of body fluids other than serum and urine is not so commonly undertaken, although - like in humans - also these sample types may have potential for diagnostic purposes. We compile published data about proteomes of fetal fluids, seminal plasma, saliva, bile, synovial fluid and tears, enriched by some yet unpublished data of our own (proteins of amniotic and allantoic fluid, tears). Closing gaps in our knowledge on dog proteins will further our understanding of (patho)physiological processes.

Identification of Cultivable Bacteria in Amniotic Fluid Using Cervicovaginal Fluid Protein Microarray in Preterm Premature Rupture of Membranes

We aimed to identify cervicovaginal fluid (CVF) protein biomarkers of microbial invasion of the amniotic cavity (MIAC) in women with preterm premature rupture of membranes (PPROM), using an antibody microarray. This retrospective cohort study included 99 consecutive women with singleton pregnancies and PPROM (23-33 weeks) who underwent amniocentesis and who gave CVF samples. CVF proteomes from the MIAC (n = 20) versus non-MIAC groups (n = 20) were comparatively profiled by an antibody microarray using a nested case-control study design. The seven candidate biomarkers of interest were validated in the total cohort (n = 99) by enzyme-linked immunosorbent assays (ELISA). For comparison with candidate markers, amniotic fluid (AF) white blood cell (WBC) count was also measured. The primary outcome measure was MIAC (defined as positive AF culture). Thirty of the proteins studied exhibited significant intergroup differences. Measurements of the total cohort with ELISA confirmed a significant increase in the levels of CVF IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1 in women with MIAC, independent of gestational age at sampling. A combined, non-invasive model was developed by using a stepwise regression procedure, which included CVF IL-8 and CVF MMP-9 (area under the curve [AUC] = 0.763), and this AUC was comparable with the AUC of AF WBC. Using protein-antibody microarray technology, we found several novel, independent, non-invasive biomarkers to identify MIAC in women with PPROM: IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1. Furthermore, the combined non-invasive model (IL-8 and MMP-9) was a useful independent predictor for MIAC with good discriminatory power, similar to AF WBC count.

Proteomic Analysis of Amniotic Fluid Proteins for Predicting the Outcome of Emergency Cerclage in Women with Cervical Insufficiency

We aimed to identify novel biomarkers in amniotic fluid (AF) that predict the outcome of emergency cerclage in women with cervical insufficiency. This retrospective cohort study included 40 singleton pregnant women who received emergency cerclage for cervical insufficiency (17-25 weeks) and underwent amniocentesis. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify AF proteins in pooled samples (n = 16) using a nested case-control approach. The six candidate biomarkers of interest were validated by enzyme-linked immunosorbent assays (ELISA) in the final cohort (n = 40). The differentially expressed proteins (DEPs) were analyzed by pathway analysis software. The primary outcome measure was failure of emergency cerclage [defined as spontaneous preterm delivery (SPTD) at < 34 weeks of gestation after cerclage placement]. Sixty-eight proteins were differentially expressed (P < 0.001) in AF from SPTD cases and near-term controls, of which 44 (64.7%) were upregulated and 24 (35.3%) were downregulated. Validation by ELISA confirmed that AF from women with cerclage failure contained significantly higher levels of myeloperoxidase, lactoferrin, glucose-6-phosphate isomerase, lipocalin-2, and lymphocyte cytosolic protein 1, the first four of which were independent of cervical dilatation at presentation. The five pathways with the most differentially regulated proteins were actin cytoskeleton signaling, acute phase response signaling, ILK signaling, glycolysis, and gluconeogenesis. Proteomic analyses of AF in this study identified DEPs and specific protein pathways related to poor prognosis after emergency cerclage for cervical insufficiency. Four novel independent biomarkers in AF for cerclage failure have been identified using proteomics.

Perinatal lipocalin-2 profile at the extremes of fetal growth

BACKGROUND

Lipocalin-2 (LCN-2) has been identified as an osteoblast-secreted hormone regulating immunity, inflammation and metabolic homeostasis and has emerged as a diagnostic and prognostic biomarker for acute kidney injury in neonates. We investigated the impact of fetal growth on antepartum maternal serum, cord serum and breast milk LCN-2 concentrations and the associations of the latter with perinatal parameters.

METHODS

Maternal serum, cord serum and breast milk LCN-2 concentrations were measured by ELISA in samples from 80 mothers who delivered 40 appropriate (AGA), 20 large for gestational age (LGA) and 20 intrauterine growth restricted (IUGR) neonates, classified by customized weight centiles. LCN-2 concentrations were associated with birth weight, customized centile, gender, maternal age and delivery mode.

RESULTS

Antepartum maternal serum LCN-2 concentrations were significantly higher in women delivering AGA infants compared to the other two groups. Cord blood LCN-2 concentrations were significantly higher compared to maternal ones; furthermore, they were significantly elevated in the IUGR group compared to the LGA one (p = .019). Lowest concentrations were detected in breast milk, which did not differ between the three growth groups. A negative correlation was documented between cord blood LCN-2 concentrations and customized centiles (r: -0.304, p = .007).

CONCLUSIONS

The higher cord serum LCN-2 concentrations, compared to maternal ones, may point to its fetal origin and potential role in intrauterine growth. The negative correlation of cord LCN-2 concentrations with customized centiles, possibly implies reduced nephron endowment/subclinical kidney damage in IUGR neonates. The extremely low LCN-2 breast milk concentrations could imply that the secretion of LCN-2 from maternal circulation to breast milk is not influenced by factors leading to intrauterine growth pathology.

Neutrophil exosomes enhance the skin autoinflammation in generalized pustular psoriasis via activating keratinocytes

Generalized pustular psoriasis (GPP) is a rare and severe inflammatory skin disease that can be life-threatening. Gene mutations are found in some cases, but its immune pathogenesis is largely unknown. Here, we observed that the neutrophil:lymphocyte ratio in patients with GPP was higher than that in healthy controls and decreased after effective treatment. Neutrophils isolated from patients with GPP induced higher expressions of inflammatory genes including IL-1β, IL-36G, IL-18, TNF-α, and C-X-C motif chemokine ligands in keratinocytes than normal neutrophils did. Moreover, neutrophils from patients with GPP secreted more exosomes than controls, which were then rapidly internalized by keratinocytes, increasing the expression of these inflammatory molecules via activating NF-κB and MAPK signaling pathways. The proteomic profiles in neutrophil exosomes further characterized functional proteins and identified olfactomedin 4 as the critical differentially expressed protein that mediates the autoimmune inflammatory responses of GPP. These results demonstrate that neutrophil exosomes have an immune-regulatory effect on keratinocytes, which modulates immune cell migration and autoinflammation in GPP.-Shao, S., Fang, H., Zhang, J., Jiang, M., Xue, K., Ma, J., Zhang, J., Lei, J., Zhang, Y., Li, B., Yuan, X., Dang, E., Wang, G. Neutrophil exosomes enhance the skin autoinflammation in generalized pustular psoriasis via activating keratinocytes.