Identification of novel functional sequence variants in the gene for peptidase inhibitor 3

Elafin and its precursor trappin-2: What is their therapeutic potential for intestinal diseases?

Elafin and its precursor trappin-2 are known for their contribution to the physiological mucosal shield against luminal microbes. Such a contribution seems to be particularly relevant in the gut, where the exposure of host tissues to heavy loads of microbes is constant and contributes to mucosa-associated pathologies. The expression of trappin-2/elafin has been shown to be differentially regulated in diseases associated with gut inflammation. Accumulating evidence has demonstrated the protective effects of trappin-2/elafin in gut intestinal disorders associated with acute or chronic inflammation, or with gluten sensitization disorders. The protective effects of trappin-2/elafin in the gut are discussed in terms of their pleiotropic modes of action: acting as protease inhibitors, transglutaminase substrates, antimicrobial peptides or as a regulator of pro-inflammatory transcription factors. Further, the question of the therapeutic potential of trappin-2/elafin delivery at the intestinal mucosa surface is raised. Whether trappin-2/elafin mucosal delivery should be considered to ensure intestinal tissue repair is also discussed.

Transcriptome analysis revealed that delaying first colostrum feeding postponed ileum immune system development of neonatal calves

Our objective was to evaluate the effect of colostrum feeding times on genome-wide gene expression of neonatal calves. In total, twenty-seven calves were assigned to three colostrum feeding treatments: within 45 min (TRT0h, n = 9), 6 h (TRT6h, n = 9) and 12 h (TRT12h, n = 9). Ileum tissues were collected at 51 h and transcriptomic analysis was conducted. Uniquely expressed genes were identified in TRT0h group with enriched "Antigen Presentation" function. Meanwhile, the weighted gene co-expression network analysis (WGCNA) identified four significant gene modules (|correlation| > 0.50 and P ≤ 0.05). In particular, Turquoise gene module with the enriched "Cadherin binding involved in cell-cell adhesion" and "Cell-cell adherences junction" GO terms were significantly correlated with Faecalibacterium prausnitzii (R = -0.70, P < 0.01) and Bifidobacterium (R = -0.55, P < 0.01). Our findings suggest feeding colostrum without delay could stimulate the expression of genes involved in immune function development related to host response and microbial colonization in neonatal claves.

A new strategy for exploring the hierarchical structure of cancers by adaptively partitioning functional modules from gene expression network

The interactions among the genes within a disease are helpful for better understanding the hierarchical structure of the complex biological system of it. Most of the current methodologies need the information of known interactions between genes or proteins to create the network connections. However, these methods meet the limitations in clinical cancer researches because different cancers not only share the common interactions among the genes but also own their specific interactions distinguished from each other. Moreover, it is still difficult to decide the boundaries of the sub-networks. Therefore, we proposed a strategy to construct a gene network by using the sparse inverse covariance matrix of gene expression data, and divide it into a series of functional modules by an adaptive partition algorithm. The strategy was validated by using the microarray data of three cancers and the RNA-sequencing data of glioblastoma. The different modules in the network exhibited specific functions in cancers progression. Moreover, based on the gene expression profiles in the modules, the risk of death was well predicted in the clustering analysis and the binary classification, indicating that our strategy can be benefit for investigating the cancer mechanisms and promoting the clinical applications of network-based methodologies in cancer researches.

Functional characterization of polymorphisms in the peptidase inhibitor 3 (elafin) gene and validation of their contribution to risk of acute respiratory distress syndrome

Elafin (peptidase inhibitor 3 [PI3]) and its biologically active precursor, pre-elafin, are neutrophil serine proteinase inhibitors with an important role in preventing excessive tissue injury during inflammatory events. Recently, we reported an association between single-nucleotide polymorphism (SNP) rs2664581 in the PI3 gene, increased risk of acute respiratory distress syndrome (ARDS) and pre-elafin circulating levels. This study aims to validate the legitimacy of this association by using a cohort of patients who met the criteria for systemic inflammatory response syndrome and were at risk of developing ARDS (n = 840). A comprehensive functional study of SNPs in PI3 gene was also performed. Luciferase assays and electrophoretic mobility shift assays were conducted to determine the functional relevance of promoter region variants. The effect of the coding SNP rs2664581 on the neutrophil elastase inhibitory activity and transglutaminase binding properties of pre-elafin was also investigated. The variant allele of rs2664581 (C) was significantly associated with increased ARDS risk, mainly among subjects with sepsis (odds ratio = 1.44; 95% confidence interval = 1.04-1.99; P = 0.0276, adjusted by age, sex, and Acute Physiology and Chronic Health Evaluation III). Pre-elafin recombinant protein carrying the amino acid change associated with rs2664581 (Thr34Pro, mutant protein [MT]) had greater capacity to undergo transglutaminase-mediated cross-linking to immobilized fibronectin than wild-type protein in vitro (P < 0.003). No differences were observed in the neutrophil elastase inhibitory activities of wild-type versus MT proteins. In addition, the risk allele-promoter construct had significantly lower cytokine-induced transcriptional activity. Electrophoretic mobility shift assay results indicated a differential binding of nuclear proteins to the G and A alleles of SNP -338G > A. Our results confirm the association between SNP rs2664581 and enhanced risk of ARDS, further supporting the role of PI3 in ARDS development. SNPs in the PI3 locus may act synergistically by regulating PI3 gene expression and pre-elafin biological functions.

Raised trappin2/elafin protein in cervico-vaginal fluid is a potential predictor of cervical shortening and spontaneous preterm birth

Early spontaneous preterm birth is associated with inflammation/infection and shortening of the cervix. We hypothesised that cervico-vaginal production of trappin2/elafin (peptidase inhibitor 3) and cathelicidin antimicrobial peptide (cathelicidin), key components of the innate immune system, are altered in women who have a spontaneous preterm birth. The aim was to determine the relationship between cervico-vaginal fluid (CVF) trappin2/elafin and cathelicidin protein concentrations with cervical length in woman at risk of spontaneous preterm birth. Trappin2/elafin and cathelicidin were measured using ELISA in longitudinal CVF samples (taken between 13 to 30 weeks' gestation) from 74 asymptomatic high risk women (based on obstetric history) recruited prospectively. Thirty six women developed a short cervix (<25 mm) by 24 weeks' and 38 women did not. Women who developed a short cervix had 2.71 times higher concentrations of CVF trappin2/elafin from 14 weeks' versus those who did not (CI 1.94–3.79, p<0.0005). CVF trappin2/elafin before 24 weeks' was 1.79 times higher in women who had a spontaneous preterm birth <37 weeks' (CI: 1.05–3.05, p = 0.034). Trappin2/elafin (>200 ng/ml) measured between 14⁺⁰–14⁺⁶ weeks' of pregnancy predicted women who subsequently developed a short cervix (n = 11, ROC area = 1.00, p = 0.008) within 8 weeks. Cathelicidin was not predictive of spontaneous delivery. Vitamin D status did not correlate with CVF antimicrobial peptide concentrations. Raised CVF trappin2/elafin has potential as an early pregnancy test for prediction of cervical shortening and spontaneous preterm birth. This justifies validation in a larger cohort.

Reproduction and immunity-driven natural selection in the human WFDC locus

The whey acidic protein (WAP) four-disulfide core domain (WFDC) locus located on human chromosome 20q13 spans 19 genes with WAP and/or Kunitz domains. These genes participate in antimicrobial, immune, and tissue homoeostasis activities. Neighboring SEMG genes encode seminal proteins Semenogelin 1 and 2 (SEMG1 and SEMG2). WFDC and SEMG genes have a strikingly high rate of amino acid replacement (dN/dS), indicative of responses to adaptive pressures during vertebrate evolution. To better understand the selection pressures acting on WFDC genes in human populations, we resequenced 18 genes and 54 noncoding segments in 71 European (CEU), African (YRI), and Asian (CHB + JPT) individuals. Overall, we identified 484 single-nucleotide polymorphisms (SNPs), including 65 coding variants (of which 49 are nonsynonymous differences). Using classic neutrality tests, we confirmed the signature of short-term balancing selection on WFDC8 in Europeans and a signature of positive selection spanning genes PI3, SEMG1, SEMG2, and SLPI. Associated with the latter signal, we identified an unusually homogeneous-derived 100-kb haplotype with a frequency of 88% in Asian populations. A putative candidate variant targeted by selection is Thr56Ser in SEMG1, which may alter the proteolytic profile of SEMG1 and antimicrobial activities of semen. All the well-characterized genes residing in the WDFC locus encode proteins that appear to have a role in immunity and/or fertility, two processes that are often associated with adaptive evolution. This study provides further evidence that the WFDC and SEMG loci have been under strong adaptive pressure within the short timescale of modern humans.

Initial experience using Sivelestat to manage preterm labor with a bulging fetal membrane in pregnant women

Intrauterine infection and inflammation are recognized as major contributors to the onset of preterm labor. We describe two cases of severe preterm labor with bulging membrane that were treated by intravenous injection of Sivelestat, a neutrophil elastase inhibitor. Ritodrine hydrochloride and magnesium sulfate were intravenously administered for tocolysis, and ampicillin was provided as an antibiotic. Urinary trypsin inhibitor (UTI) was administered transvaginally. Sivelestat was infused intravenously at 4.8 mg kg(-1) day(-1) through the maternal vein. No side effects were observed. Levels of interleukin (IL)-6 and IL-8 in amniotic fluid decreased, and gestations were prolonged without complications for >1 week. Two healthy infants were delivered. Our experience suggests that multidrug therapy with Sivelestat offers a new therapeutic strategy for preterm labor, but further investigations of the indications, administration period and dosage are required.

The protease inhibitor, elafin, induces p53-dependent apoptosis in human melanoma cells

Expression of the protease inhibitor elafin is deregulated in several human cancers. However, functions of the protein in cancer are yet to be established. Here, we show that elafin elicits pro-apoptotic effects in melanoma cells but not in normal melanocytes. Elafin triggered the intrinsic apoptotic pathway as evidenced by the increased caspase 9 activity and unaltered caspase 8 activity. Caspase 9-specific siRNA, but not caspase 8-specific siRNA, dramatically abrogated elafin-induced apoptosis. Elevated level of p53 was observed, resulting in increased transcriptional activation and consequent expression of downstream effector molecules (Bax, Puma, Noxa, p21). Moreover, the apoptotic effect of elafin was inhibited by p53-specific siRNA and the p53 inhibitor pifithrin-alpha. Elafin treatment of xenograft mice of melanoma cells led to significantly smaller tumor sizes compared with those of untreated control mice. Immunohistochemical analysis revealed decreased elafin expression in melanoma tissue specimens. Western blot and reverse transcription analyses indicated transcriptional repression of the elafin gene in melanoma cells. Our results collectively indicate that elafin induces apoptosis in melanoma cells through a p53-dependent intrinsic apoptotic pathway, and that repression of elafin expression in melanoma may contribute to disease progression.

Overexpression of elafin in ovarian carcinoma is driven by genomic gains and activation of the nuclear factor kappaB pathway and is associated with poor overall survival

Ovarian cancer is a leading cause of cancer mortality in women. The aim of this study was to elucidate whether whey acidic protein (WAP) genes on chromosome 20q13.12, a region frequently amplified in this cancer, are expressed in serous carcinoma, the most common form of the disease. Herein, we report that a trio of WAP genes (HE4, SLPI, and Elafin) is overexpressed and secreted by serous ovarian carcinomas. To our knowledge, this is the first report linking Elafin to ovarian cancer. Fluorescence in situ hybridization analysis of primary tumors demonstrates genomic gains of the Elafin locus in a majority of cases. In addition, a combination of peptidomimetics, RNA interference, and chromatin immunoprecipitation experiments shows that Elafin expression can be transcriptionally upregulated by inflammatory cytokines through activation of the nuclear factor kappaB pathway. Importantly, using a clinically annotated tissue microarray composed of late-stage, high-grade serous ovarian carcinomas, we show that Elafin expression correlates with poor overall survival. These results, combined with our observation that Elafin is secreted by ovarian tumors and is minimally expressed in normal tissues, suggest that Elafin may serve as a determinant of poor survival in this disease.

Secretory leukocyte protease inhibitor and elafin/trappin-2: versatile mucosal antimicrobials and regulators of immunity

Elafin and secretory leukocyte protease inhibitor (SLPI) are pleiotropic molecules chiefly synthesized at the mucosal surface that have a fundamental role in the surveillance against microbial infections. Their initial discovery as anti-proteases present in the inflammatory milieu in chronic pathologies such as those of the lung suggested that they may play a role in keeping in check extracellular proteases released during the excessive activation of innate immune cells such as neutrophils. This soon proved to be a simplistic explanation, as other functions were also soon ascribed to these molecules (antimicrobial, modulation of innate and adaptive immunity, regulation of tissue repair). Data emanating from patients with chronic pathologies (in the lung and elsewhere) have shown that SLPI and elafin are often inactivated in inflammatory secretions, either through the action of host or microbial products, justifying attempts at antiprotease supplementation in clinical protocols. Although these have been sparse, proof of principle has been demonstrated, and future challenges will undoubtedly rest with improvements in methods of delivery in the context of tissue inflammation and in careful selection of patients more likely to benefit from SLPI/elafin augmentation.

Elafin (SKALP/Trappin-2/proteinase inhibitor-3) is produced by the cervix in pregnancy and cervicovaginal levels are diminished in bacterial vaginosis

OBJECTIVES

To examine cervicovaginal elafin production in pregnancy and determine its relationship in bacterial vaginosis.

STUDY DESIGN

Samples of cervicovaginal secretions were collected from women with uncomplicated singleton pregnancies (n = 112) below 20 weeks gestation. Bacterial flora was assessed using Nugent's criteria, and levels of elafin were measured by enzyme-linked immunosorbent serologic assay (ELISA). Elafin expression in the cervix was also examined by immunohistochemistry. In vitro expression of elafin was examined using cervix and vaginal cell lines.

RESULTS

Elafin is expressed in the cervical glandular epithelium. Elafin was found in all 112 samples of cervicovaginal secretions and levels were diminished in women with bacterial vaginosis (P < .05). Interleukin 1beta (IL-1beta) stimulated elafin expression in cells derived from the endocervix, but not in those derived from the vaginal epithelium.

CONCLUSIONS

Elafin is a component of cervicovaginal secretions in pregnancy, and levels are diminished in bacterial vaginosis. It may be an important component of innate immunity in the lower genital tract.

Genetic polymorphisms of peptidase inhibitor 3 (elafin) are associated with acute respiratory distress syndrome

Peptidase inhibitor 3 (PI3, elafin) is a protease inhibitor produced locally in the lung, where it plays a central role in controlling excessive activity of neutrophil elastase. Our previous study revealed that PI3 gene expression is down-regulated during the acute stage of acute respiratory distress syndrome (ARDS). We conducted a case-control study to investigate whether genetic variants in PI3 gene are associated with ARDS development. Based on resequencing data from 29 unrelated white subjects, three tagging single-nucleotide polymorphisms were selected and genotyped in a prospective cohort consisting of 449 white patients with ARDS (cases) and 1,031 critically ill patients (at-risk control subjects). We found that the variant allele of rs2664581 (T34P) was significantly associated with increased ARDS risk (odds ratio [OR], 1.35; 95% confidence interval [CI], 1.09-1.67; P = 0.006; false discovery rate adjusted P = 0.018). Moreover, this association was stronger among subjects with extrapulmonary injury. The common haplotype Hap2 (TTC), containing the variant allele of rs2664581, was also identified as a risk haplotype for ARDS (OR, 1.31; 95% CI, 1.05-1.64; P = 0.015). Furthermore, the rs2664581 polymorphism was associated with circulating PI3 levels in multivariate analyses. Patients with ARDS homozygous for the wild-type A allele of rs2664581 showed significant lower PI3 plasma level (P = 0.019) at ARDS onset as compared with those homozygous or heterozygous for the variant C allele. Our data suggest that polymorphisms in PI3 gene are significantly associated with ARDS risk and with circulating PI3 levels.

Multifaceted roles of human elafin and secretory leukocyte proteinase inhibitor (SLPI), two serine protease inhibitors of the chelonianin family

Elafin and SLPI are low-molecular weight proteins that were first identified as protease inhibitors in mucous fluids including lung secretions, where they help control excessive proteolysis due to neutrophil serine proteases (elastase, proteinase 3 and cathepsin G). Elafin and SLPI are structurally related in that both have a fold with a four-disulfide core or whey acidic protein (WAP) domain responsible for inhibiting proteases. Elafin is derived from a precursor, trappin-2 or pre-elafin, by proteolysis. Trappin-2, which is itself a protease inhibitor, has a unique N-terminal domain that enables it to become cross-linked to extracellular matrix proteins by transglutaminase(s). SLPI and elafin/trappin-2 are attractive candidates as therapeutic molecules for inhibiting neutrophil serine proteases in inflammatory lung diseases. Hence, they have become the WAP proteins most studied over the last decade. This review focuses on recent findings revealing that SLPI and elafin/trappin-2 have many biological functions as diverse as anti-bacterial, anti-fungal, anti-viral, anti-inflammatory and immuno-modulatory functions, in addition to their well-recognized role as protease inhibitors.