Lack of plasma kallikrein-kinin system cascade in teleosts

Immunonutrition: facilitating mucosal immune response in teleost intestine with amino acids through oxidant-antioxidant balance

Comparative animal models generate fundamental scientific knowledge of immune responses. However, these studies typically are conducted in mammals because of their biochemical and physiological similarity to humans. Presently, there has been an interest in using teleost fish models to study intestinal immunology, particularly intestinal mucosa immune response. Instead of targeting the pathogen itself, a preferred approach for managing fish health is through nutrient supplementation, as it is noninvasive and less labor intensive than vaccine administrations while still modulating immune properties. Amino acids (AAs) regulate metabolic processes, oxidant-antioxidant balance, and physiological requirements to improve immune response. Thus, nutritionists can develop sustainable aquafeeds through AA supplementation to promote specific immune responses, including the intestinal mucosa immune system. We propose the use of dietary supplementation with functional AAs to improve immune response by discussing teleost fish immunology within the intestine and explore how oxidative burst is used as an immune defense mechanism. We evaluate immune components and immune responses in the intestine that use oxidant-antioxidant balance through potential selection of AAs and their metabolites to improve mucosal immune capacity and gut integrity. AAs are effective modulators of teleost gut immunity through oxidant-antioxidant balance. To incorporate nutrition as an immunoregulatory means in teleost, we must obtain more tools including genomic, proteomic, nutrition, immunology, and macrobiotic and metabonomic analyses, so that future studies can provide a more holistic understanding of the mucosal immune system in fish.

Discovery of Teleost Plasma Kallikrein/Coagulation Factor XI-Like Gene from Channel Catfish (Ictalurus punctatus) and the Evidence that the Protein Encoded by it Acts as a Lectin

Mammalian plasma kallikrein (PK) and coagulation factor XI (fXI) are serine proteases that play in the kinin-kallikrein cascade and in the blood clotting pathway. These proteases share sequence homology and have four apple domains (APDs) and a serine protease domain (SPD) from their N-terminus to C-terminus. No homologs of these proteases are believed to be present in fish species, except for lobe-finned fish. Fish, however, have a unique lectin, named kalliklectin (KL), which is composed of APDs only. In the present study, we found genomic sequences encoding a protein with both APDs and SPD in a few cartilaginous and bony fishes, including the channel catfish Ictalurus punctatus, using bioinformatic analysis. Furthermore, we purified two ~ 70 kDa proteins from the blood plasma of the catfish using mannose-affinity and gel filtration chromatography sequentially. Using de novo sequencing with quadrupole time-of-flight tandem mass spectrometry, several internal amino acid sequences in these proteins were mapped onto possible PK/fXI-like sequences that are thought to be splicing variants. Exploration of APD-containing proteins in the hagfish genome database and phylogenetic analysis suggested that the PK/fXI-like gene originated from hepatocyte growth factor, and that the gene was acquired in a common ancestor of jawed fish. Synteny analysis provided evidence for chromosomal translocation around the PK/fXI-like locus that occurred in the common ancestor of holosteans and teleosts after separation from the lobe-finned fish lineage, or gene duplication into two chromosomes, followed by independent gene losses. This is the first identification of PK/fXI-like proteins in teleosts.

Anthocyanins accumulation analysis of correlated genes by metabolome and transcriptome in green and purple peppers (Capsicum annuum)

BACKGROUND

In order to clarify the the molecular mechanism of anthocyanin accumulation in green and purple fruits of pepper using metabolomics and transcriptomics,to identify different anthocyanin metabolites,and to analyze the differentially expressed genes involved in anthocyanin biosynthesis..

RESULTS

We analyzed the anthocyanin metabolome and transcriptome data of the fruits of 2 purple pepper and 1 green pepper. A total of 5 anthocyanin metabolites and 2224 differentially expressed genes were identified between the green and purple fruits of pepper. Among the 5 anthocyanin metabolites,delphin chloride was unique to purple pepper fruits,which is the mainly responsible for the purple fruit color of pepper. A total of 59 unigenes encoding 7 enzymes were identified as candidate genes involved in anthocyanin biosynthesis in pepper fruit. The six enzymes (PAL,C4H,CHI,DFR,ANS,UFGT) had higher expression levels except the F3H gene in purple compared with green fruits. In addition,seven transcription factors were also found in this study. These transcription factors may contribute to anthocyanin metabolite biosynthesis in the fruits of pepper. One of differentially expressed gene novel.2098 was founded. It was not annotated in NCBI. Though blast analysis we preliminarily considered that this gene related to MYB transcription factor and was involved in anthocyanin biosynthesis in pepper fruit.

CONCLUSIONS

Overall, the results of this study provide useful information for understanding anthocyanin accumulation and the molecular mechanism of anthocyanin biosynthesis in peppers.

Identification of Proteins Responsible for High Activity of Cysteine Proteinase Inhibitor in the Blood of Nile Tilapia Oreochromis niloticus

Cysteine proteinase inhibitors (CPIs) protect tissues and organs against cysteine proteinases in animal blood and have attracted much attention for use in food processing and medical sciences for humans and animals. Several CPI proteins, which include stefins, cystatins, kininogens, histidine-rich glycoproteins (HRG) and fetuins, have been identified and characterized in mammals. Fish blood also contains high CPI activity, but the identity of the major protein responsible for this activity has not been clarified. This study was conducted to screen CPI activity by examining papain inhibitory activity from various different tissues in Nile tilapia Oreochromis niloticus and to identify major proteins for the activity in the blood. CPI activity was highest in the serum among the tissues screened in this study (at least fourfold higher than in other tissues)(P < 0.05). Major proteins for CPI activity in serum were purified using a CNBr-activated sepharose 4B column, gel filtration and an ion exchange FPLC column. From these purifications, two proteins with strong CPI activity were isolated and partially sequenced. Based on their molecular weights and partial amino sequences, the two major proteins with CPI activity from the blood in this species were found to be fetuin B (60 kDa) and kininogen (54 kDa).

Repurposing new drug candidates and identifying crucial molecules underlying PCOS Pathogenesis Based On Bioinformatics Analysis

BACKGROUNDS

Polycystic ovary syndrome affects 7% of women of reproductive ages. Poor-quality oocytes, along with lower cleavage and implantation rates, reduce fertilization.

OBJECTIVE

This study aimed to determine crucial molecular mechanisms behind PCOS pathogenesis and repurpose new drug candidates interacting with them. To predict a more in-depth insight, we applied a novel bioinformatics approach to analyze interactions between the drug-related and PCOS proteins in PCOS patients.

METHODS

The newest proteomics data was retrieved from 16 proteomics datasets and was used to construct the PCOS PPI network using Cytoscape. The topological network analysis determined hubs and bottlenecks. The MCODE Plugin was used to identify highly connected regions, and the associations between PCOS clusters and drug-related proteins were evaluated using the Chi-squared/Fisher's exact test. The crucial PPI hub-bottlenecks and the shared molecules (between the PCOS clusters and drug-related proteins) were then investigated for their drug-protein interactions with previously US FDA-approved drugs to predict new drug candidates.

RESULTS

The PI3K/AKT pathway was significantly related to one PCOS subnetwork and most drugs (metformin, letrozole, pioglitazone, and spironolactone); moreover, VEGF, EGF, TGFB1, AGT, AMBP, and RBP4 were identified as the shared proteins between the PCOS subnetwork and the drugs. The shared top biochemical pathways between another PCOS subnetwork and rosiglitazone included metabolic pathways, carbon metabolism, and citrate cycle, while the shared proteins included HSPB1, HSPD1, ACO2, TALDO1, VDAC1, and MDH2. We proposed some new candidate medicines for further PCOS treatment investigations, such as copper and zinc compounds, reteplase, alteplase, gliclazide, Etc.

CONCLUSION

Some of the crucial molecules suggested by our model have already been experimentally reported as critical molecules in PCOS pathogenesis. Moreover, some repurposed medications have already shown beneficial effects on infertility treatment. These previous experimental reports confirm our suggestion for investigating our other repurposed drugs (in vitro and in vivo).

Molecular evolution of kalliklectin in teleost and identification of the novel type with eight apple domains in channel catfish, Ictalurus punctatus

Kalliklectin is a unique fish-specific lectin that demonstrates sequence similarity to mammalian plasma kallikrein and coagulation factor XI, which are not lectins but proteases. Reported fish kalliklectins and these mammalian proteases comprise four characteristic "apple domains" (APDs). Bioinformatics analysis revealed that Siluriformes species possess anomalous kalliklectins comprising 6 to 16 APDs. Complementary DNA cloning showed that the full-length nucleotide sequence of Ictalurus punctatus consists of 2240 bp that encode 720 amino acid residues to produce a mature protein with a putative 18 amino acid N-terminus peptide sequence. This protein has a predicted molecular mass of 83,417.23 Da. Reverse transcription-polymerase chain reaction (RT-PCR) showed that this lectin gene expresses in the liver but not in any other tissues, including the mucosal tissues. This differential expression pattern makes this lectin unique compared to other lectins described in previous studies. We successfully detected an 85-kDa protein in the serum using western blotting analysis, suggesting that this lectin protein is produced by the liver and secreted into the bloodstream. We characterized a novel cDNA sequence encoding a new type of kalliklectin with eight APDs isolated from channel catfish, I. punctatus. Based on phylogenetic analysis, we speculated that there was a duplication of the third and fourth APD set in a common Siluriformes ancestor at some point after its separation from the common teleost ancestor and that these duplications then underwent independent repeats in different lineages resulting in the generation of the [APD1]-[APD2]-{[APD3]-[APD-4]} × n structure in modern catfishes.

Cloning, Expression, Characterization, and Tissue Distribution of Cystatin C from Silver Carp (Hypophthalmichthys molitrix)

Cystatins are proteins, which inhibit cysteine proteases, such as papain. In this study, the 336-bp cystatin C gene (family II, HmCysC) of silver carp (Hypophthalmichthys molitrix) was cloned and expressed in Escherichia coli BL21 (DE3). HmCysC encodes the mature peptide of cystatin C (HmCystatin C), with 111 amino acids. A typical QXXXG motif was found in HmCystatin C and it formed a cluster with Cyprinus carpio and Danio rerio cystatin C in the phylogenetic tree. Quantitative real-time polymerase chain reaction analysis indicated that HmCysC was transcribed at different levels in five tested tissues of silver carp. Following purification with Ni²⁺- nitrilotriacetic acid agarose affinity chromatography, HmCystatin C displayed a molecular weight of 20 kDa in sodium dodecyl sulfate polyacrylamide gel electrophoresis. Purified HmCystatin C had strong inhibitory effects toward the proteolytic activity of papain. Immunochemical staining with anti-HmCystatin C antibody showed that HmCystatin C was widely distributed in silver carp tissues. These results collectively demonstrated the properties of HmCystatin C, providing information for further studies of cystatins from fish organisms.

The evolution of factor XI and the kallikrein-kinin system

Factor XI (FXI) is the zymogen of a plasma protease (FXIa) that contributes to hemostasis by activating factor IX (FIX). In the original cascade model of coagulation, FXI is converted to FXIa by factor XIIa (FXIIa), a component, along with prekallikrein and high-molecular-weight kininogen (HK), of the plasma kallikrein-kinin system (KKS). More recent coagulation models emphasize thrombin as a FXI activator, bypassing the need for FXIIa and the KKS. We took an evolutionary approach to better understand the relationship of FXI to the KKS and thrombin generation. BLAST searches were conducted for FXI, FXII, prekallikrein, and HK using genomes for multiple vertebrate species. The analysis shows the KKS appeared in lobe-finned fish, the ancestors of all land vertebrates. FXI arose later from a duplication of the prekallikrein gene early in mammalian evolution. Features of FXI that facilitate efficient FIX activation are present in all living mammals, including primitive egg-laying monotremes, and may represent enhancement of FIX-activating activity inherent in prekallikrein. FXI activation by thrombin is a more recent acquisition, appearing in placental mammals. These findings suggest FXI activation by FXIIa may be more important to hemostasis in primitive mammals than in placental mammals. FXI activation by thrombin places FXI partially under control of the vitamin K-dependent coagulation mechanism, reducing the importance of the KKS in blood coagulation. This would explain why humans with FXI deficiency have a bleeding abnormality, whereas those lacking components of the KKS do not.

Plasma Proteome Responses in Salmonid Fish Following Immunization

Vaccination plays a critical role in the protection of humans and other animals from infectious diseases. However, the same vaccine often confers different protection levels among individuals due to variation in genetics and/or immunological histories. While this represents a well-recognized issue in humans, it has received little attention in fish. Here we address this knowledge gap in a proteomic study of rainbow trout (Oncorhynchus mykiss, Walbaum), using non-lethal repeated blood sampling to establish the plasma protein response of individual fish following immunization. Six trout were immunized with adjuvanted hen egg-white lysozyme (HEL) and peripheral blood sampled at ten time points from day 0 to day 84 post-injection. We confirm that an antigen-specific antibody response to HEL was raised, showing differences in timing and magnitude among individuals. Using label-free liquid chromatography-mass spectrometry, we quantified the abundance of 278 plasma proteins across the timecourse. As part of the analysis, we show that this approach can distinguish many (but not all) duplicated plasma proteins encoded by paralogous genes retained from the salmonid-specific whole genome duplication event. Global variation in the plasma proteome was predominantly explained by individual differences among fish. However, sampling day explained a major component of variation in abundance for a statistically defined subset of 41 proteins, representing 15% of those detected. These proteins clustered into five groups showing distinct temporal responses to HEL immunization at the population level, and include classical immune (e.g. complement system members) and acute phase molecules (e.g. apolipoproteins, haptoglobins), several enzymes and other proteins supporting the immune response, in addition to evolutionarily conserved molecules that are as yet uncharacterized. Overall, this study improves our understanding of the fish plasma proteome, provides valuable marker proteins for different phases of the immune response, and has implications for vaccine development and the design of immune challenge experiments.

Differential gene regulation in selected lines for high and low sperm production in male guppies

In species where females mate with more than one male during the same reproductive event, males typically increase the number of sperm produced to boost their fertilization share. Sperm is not limitless, however, and theory predicts that their production will come at the cost of other fitness-related traits, such as body growth or immunocompetence, although these evolutionary trade-offs are notoriously difficult to highlight. To this end, we combined artificial selection for sperm production with a transcriptome analysis using Poecilia reticulata, a fish characterized by intense sperm competition in which the number of sperm transferred during mating is the most important predictor of fertilization success, yet sperm production is highly variable among males. We compared the brain and testes transcriptome in male guppies of lines artificially selected for high and low sperm production by identifying pivotal differentially expressed gene sets that may regulate spermatogenesis and immune function in this species. Despite the small differences in single genes' expression, gene set enrichment analysis showed coordinated gene expression differences associated with several pathways differentially regulated in the two selection lines. High sperm production males showed an upregulation of pathways related to immunosuppression and development of spermatozoa indicating a possible immunological cost of sperm production.

A novel Kunitz protein with proposed dual function from Eudiplozoon nipponicum (Monogenea) impairs haemostasis and action of complement in vitro

Serine peptidases are involved in many physiological processes including digestion, haemostasis and complement cascade. Parasites regulate activities of host serine peptidases to their own benefit, employing various inhibitors, many of which belong to the Kunitz-type protein family. In this study, we confirmed the presence of potential anticoagulants in protein extracts of the haematophagous monogenean Eudiplozoon nipponicum which parasitizes the common carp. We then focused on a Kunitz protein (EnKT1) discovered in the E. nipponicum transcriptome, which structurally resembles textilinin-1, an antihemorrhagic snake venom factor from Pseudonaja textilis. The protein was recombinantly expressed, purified and biochemically characterised. The recombinant EnKT1 did inhibit in vitro activity of Factor Xa of the coagulation cascade, but exhibited a higher activity against plasmin and plasma kallikrein, which participate in fibrinolysis, production of kinins, and complement activation. Anti-coagulation properties of EnKT1 based on the inhibition of Factor Xa were confirmed by thromboelastography, but no effect on fibrinolysis was observed. Moreover, we discovered that EnKT1 significantly impairs the function of fish complement, possibly by inhibiting plasmin or Factor Xa which can act as a C3 and C5 convertase. We localised Enkt1 transcripts and protein within haematin digestive cells of the parasite by RNA in situ hybridisation and immunohistochemistry, respectively. Based on these results, we suggest that the secretory Kunitz protein of E. nipponicum has a dual function. In particular, it impairs both haemostasis and complement activation in vitro, and thus might facilitate digestion of a host's blood and protect a parasite's gastrodermis from damage by the complement. This study presents, to our knowledge, the first characterisation of a Kunitz protein from monogeneans and the first example of a parasite Kunitz inhibitor that impairs the function of the complement.

Identification and partial characterization of a novel serpin from Eudiplozoon nipponicum (Monogenea, Polyopisthocotylea)

Background: Serpins are a superfamily of serine peptidase inhibitors that participate in the regulation of many physiological and cell peptidase-mediated processes in all organisms (e.g. in blood clotting, complement activation, fibrinolysis, inflammation, and programmed cell death). It was postulated that in the blood-feeding members of the monogenean family Diplozoidae, serpins could play an important role in the prevention of thrombus formation, activation of complement, inflammation in the host, and/or in the endogenous regulation of protein degradation.

Results: In silico analysis showed that the DNA and primary protein structures of serpin from Eudiplozoon nipponicum (EnSerp1) are similar to other members of the serpin superfamily. The inhibitory potential of EnSerp1 on four physiologically-relevant serine peptidases (trypsin, factor Xa, kallikrein, and plasmin) was demonstrated and its presence in the worm’s excretory-secretory products (ESPs) was confirmed.

Conclusion: EnSerp1 influences the activity of peptidases that play a role in blood coagulation, fibrinolysis, and complement activation. This inhibitory potential, together with the serpin’s presence in ESPs, suggests that it is likely involved in host-parasite interactions and could be one of the molecules involved in the control of feeding and prevention of inflammatory responses.

The coagulation system helps control infection caused by the ciliate parasite Philasterides dicentrarchi in the turbot Scophthalmus maximus (L.)

Many studies have shown that coagulation systems play an important role in the defence against pathogens in invertebrates and vertebrates. In vertebrates, particularly in mammals, it has been established that the coagulation system participates in the entrapment of pathogens and activation of the early immune response. However, functional studies investigating the importance of the fish coagulation system in host defence against pathogens are scarce. In the present study, injection of turbot (Scopthalamus maximus) with the pathogenic ciliate Philasterides dicentrarchi led to the formation of macroscopic intraperitoneal clots in the fish. The clots contained abundant, immobilized ciliates, many of which were lysed. We demonstrated that the plasma clots immobilize and kill the ciliates in vitro. To test the importance of plasma clotting in ciliate killing, we inhibited the process by adding a tetrapeptide known to inhibit fibrinogen/thrombin clotting in mammals. Plasma tended to kill P. dicentrarchi slightly faster when clotting was inhibited by the tetrapeptide, although the total mortality of ciliates was similar. We also found that kaolin, a particulate activator of the intrinsic pathway in mammals, accelerates plasma clotting in turbot. In addition, PMA-stimulated neutrophils, living ciliates and several ciliate components such as cilia, proteases and DNA also displayed procoagulant activity in vitro. Injection of fish with the ciliates generated the massive release of neutrophils to the peritoneal cavity, with formation of large aggregates in those fish with live ciliates in the peritoneum. We observed, by SEM, numerous fibrin-like fibres in the peritoneal exudate, many of which were associated with peritoneal leukocytes and ciliates. Expression of the CD18/CD11b gene, an integrin associated with cell adhesion and the induction of fibrin formation, was upregulated in the peritoneal leukocytes. In conclusion, the findings of the present study show that P. dicentrarchi induces the formation of plasma clots and that the fish coagulation system may play an important role in immobilizing and killing this parasite.

Inhibition of plasma kallikrein-kinin system to alleviate renal injury and arthritis symptoms in rats with adjuvant-induced arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Impairment of kidney functions in RA was observed. However, the mechanism of kidney injury of RA has not been clear. Plasma kallikrein-kinin system (KKS) was involved in inflammatory processes in kidney disease.

AIM

This study aimed to explore the role of plasma KKS in immune reactions and kidney injury of RA.

RESULTS

The paw of AA rats appeared to be swelling and redness, the arthritis index was significantly increased on the 18, 21 and 24 d after injection and secondary inflammation in multi-sites was observed. Kidney dysfunction accompanied with inflammatory cell infiltration, tubular epithelial cell mitochondrial swelling and vacuolar degeneration, renal glomerular foot process fusions and glomerular basement membrane thickening were observed in AA rats. The expressions of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (Kim-1) in kidney of AA rats were increased. In addition, expressions of BK, PK, B1R and B2R in the renal tissue of AA rats were up-regulated. Pro-inflammatory cytokines IL-2, IFN-γ and TNF-α were increased and anti-inflammatory cytokines IL-4 and IL-10 were low in kidney. Plasma kallikrein (PK) inhibitor PKSI-527 attenuated arthritis signs and renal damage, and inhibited BK, PK, B1R and B2R expressions. The protein expressions of P38, p-P38 and p-JNK and IFN-γ and TNF-α were inhibited by PKSI-527.

CONCLUSIONS

These findings demonstrate that plasma KKS activation contributed to the renal injury of AA rats through MAPK signaling pathway. Plasma KKS might be a potential target for RA therapy.

Proteomic analysis of preovulatory follicular fluid reveals differentially abundant proteins in less fertile dairy cows

The follicular fluid (FF) proteome can provide an indication of follicular quality. High-yielding dairy cows suffer from low fertility, which could be related to follicular function. However, the proteome of preovulatory follicles has never been described in cows. Our objectives were to: 1) define the bovine preovulatory FF proteome, and 2) examine differentially abundant proteins in FF of controls (CTL, n=10) and less fertile cows (LFC; failed to conceive following ≥6 inseminations, n=8). Follicles ≥7mm in diameter were aspirated in vivo, and estradiol (E2) and progesterone (P4) were examined. The FF from 10 preovulatory follicles (E2/P4>1) was analyzed; E2 was higher and follicle diameter tended to be larger in LFC. As aspirations were conducted at a fixed time, this suggests accelerated follicular growth in LFC. The 219 identified and quantified proteins consisted mainly of binding proteins, proteases, receptor ligands, enzymes and transporters. Differential abundance of 8 relevant proteins was found in LFC compared to CTL: SERPINA1, TIMP2, ITIH1, HSPG2, C8A, COL1A2, F2, and IL1RAP. These proteins could influence follicular function-e.g., decreased SERPINA1 may be related to accelerated follicular growth-and therefore, further examination of their roles in the etiology of LFC is warranted.

SIGNIFICANCE

High yielding dairy cows suffer from infertility that leads to major economic losses worldwide. In Israel, about 30% of dairy cows fail to conceive following ≥4 inseminations. The etiology of this low fertility is multifactorial and remains a serious challenge. Follicular fluid proteome can provide indication to follicular quality, yet the proteome of pre-ovulatory follicles has not been described in cows. This work examined the differential abundance of proteins in less fertile dairy cows compared to controls, and found 8 relevant novel proteins that could influence follicular function. The role of these proteins in the etiology of less fertile cows should be further examined.

Evolution of Klk4 and enamel maturation in eutherians

Kallikrein-related peptidase 4 (KLK4) is a secreted serine protease that degrades residual enamel proteins to facilitate their removal by ameloblasts, which increases mineralization and hardens the enamel. Mutations in human KLK4 cause hypomaturation amelogenesis imperfecta. Enamel formed by Klk4 null mice is normal in thickness and prism structure, but the enamel layer retains proteins, is hypomineralized, and undergoes rapid attrition following tooth eruption. We searched multiple databases, retrieved Klk4 and Klk5 from various mammalian genomes, and identified Klk4 in 46 boreoeutherian genomes. In non-Boreoeutheria, Klk4 was detected in only one afrotherian genome (as a pseudogene), and not in the other six afrotherian, two xenarthran, or three marsupial genomes. In contrast, Klk5 was detected in both marsupial and eutherian mammals. Our phylogenetic and mutation rate analyses support the hypothesis that Klk4 arose from Klk5 by gene duplication near the divergence of Afrotheria, Xenarthra and Boreoeutheria, and that functionally-differentiated Klk4 survived only in Boreoeutheria. Afrotherian mammals share the feature of delayed dental eruption relative to boreoeutherian mammals. KLK4 shortens the time required for enamel maturation and could have alleviated negative selection following mutations that resulted in thicker enamel or earlier tooth eruption, without reducing enamel hardness or causing dental attrition.

Overlap of proteomics biomarkers between women with pre-eclampsia and PCOS: a systematic review and biomarker database integration

STUDY QUESTION

Do any proteomic biomarkers previously identified for pre-eclampsia (PE) overlap with those identified in women with polycystic ovary syndrome (PCOS).

SUMMARY ANSWER

Five previously identified proteomic biomarkers were found to be common in women with PE and PCOS when compared with controls.

WHAT IS KNOWN ALREADY

Various studies have indicated an association between PCOS and PE; however, the pathophysiological mechanisms supporting this association are not known.

STUDY DESIGN, SIZE, DURATION

A systematic review and update of our PCOS proteomic biomarker database was performed, along with a parallel review of PE biomarkers. The study included papers from 1980 to December 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In all the studies analysed, there were a total of 1423 patients and controls. The number of proteomic biomarkers that were catalogued for PE was 192.

MAIN RESULTS AND THE ROLE OF CHANCE

Five proteomic biomarkers were shown to be differentially expressed in women with PE and PCOS when compared with controls: transferrin, fibrinogen α, β and γ chain variants, kininogen-1, annexin 2 and peroxiredoxin 2. In PE, the biomarkers were identified in serum, plasma and placenta and in PCOS, the biomarkers were identified in serum, follicular fluid, and ovarian and omental biopsies.

LIMITATIONS, REASONS FOR CAUTION

The techniques employed to detect proteomics have limited ability in identifying proteins that are of low abundance, some of which may have a diagnostic potential. The sample sizes and number of biomarkers identified from these studies do not exclude the risk of false positives, a limitation of all biomarker studies. The biomarkers common to PE and PCOS were identified from proteomic analyses of different tissues.

WIDER IMPLICATIONS OF THE FINDINGS

This data amalgamation of the proteomic studies in PE and in PCOS, for the first time, discovered a panel of five biomarkers for PE which are common to women with PCOS, including transferrin, fibrinogen α, β and γ chain variants, kininogen-1, annexin 2 and peroxiredoxin 2. If validated, these biomarkers could provide a useful framework for the knowledge infrastructure in this area. To accomplish this goal, a well co-ordinated multidisciplinary collaboration of clinicians, basic scientists and mathematicians is vital.

STUDY FUNDING/COMPETING INTERESTS

No financial support was obtained for this project. There are no conflicts of interest.