Expression of serum amyloid A transcripts in human trophoblast and fetal-derived trophoblast-like choriocarcinoma cells

Changes of acute-phase proteins, glucose, and lipid metabolism during pregnancy in lactating dairy cows

The study aimed to evaluate the effects of different stages of lactation (0 to >  300 d) and pregnancy (0 to >  180 d) on serum amyloid A (SAA), C-reactive protein (CRP), glucose, total cholesterol (TCho), and triglyceride (TG) concentrations in dairy cows of different breeds. Thus, 40 healthy multiparous cows (10 Holstein, 10 Simmental, 10 Brown, and 10 Modicana) were randomly selected, and blood samples were collected once every 60 d for 1 year. Overall, SAA and CRP serum concentrations progressively increased and became more variable along the lactation, peaking at >  240-300 d, and then decreased in the last period ( >  300 d). Along pregnancy, SAA and CRP initially increased, with the highest concentrations at >  60-120 d, and then decreased until the last phase of pregnancy ( >  180 d). However, lactation and gestation phases did not significantly affect SAA and CRP when all the cows were analyzed together. A significant and positive correlation was observed between SAA and CRP both along lactation ( r = 0.89 ; p < 0.0001 ) and pregnancy ( r = 0.91 ; p < 0.0001 ). Breeds only showed differences in CRP levels along gestation ( p = 0.0102 ), due to a peak registered at 0-60 d in Holstein cows. In pregnant cows, glucose was positively correlated with SAA ( r = 0.43 ; p = 0.0017 ) and CRP ( r = 0.42 ; p = 0.0019 ). Hence, these significant and positive relationships reflect the physiological adaptations of the dairy cows along both gestational and lactational dynamics, suggesting that these proteins may also be involved in non-pathological processes. In this perspective, this study established that the obtained response markedly varies among healthy individuals along lactation and gestation and thus that the physiological range of acute-phase proteins (APPs) is wide; this makes it difficult to use these proteins as a marker of different physiological reproductive and productive periods.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

Serum amyloid protein (SAA) as a healthy marker for immune function in Tridacna crocea

Serum amyloid protein (SAA) is known as an acute reactive protein of innate immunity in mammals. However, in invertebrates, the role of SAA in innate immunity is still unclear. In this study, a full-length cDNA of the SAA gene (named TcSAA) was cloned from Tridacna crocea, mollusca. The gene includes a 193 bp 5' untranslated region (UTR) and a 129 bp 3' UTR sequence, and the open reading frame (ORF) with 393 bp nucleotides encodes a polypeptide of 130 amino acids. TcSAA contains a typical signal peptide and an SAA functional domain. The mRNA expression of TcSAA was detected in all 12 selected tissues and 7 different developmental stages. Furthermore, the expression of TcSAA was increased quickly in hemocytes after challenge with V. coralliilyticus or LPS. Furthermore, rTcSAA could bind V. coralliilyticus and V. alginolyticus, and the protein could reduce the lethality rate of the clams from 80% to 55% which caused by V. coralliilyticus about 48 h after injection. In summary, these results indicate that TcSAA may act as a marker for monitoring health and protecting T. crocea.

Interrelationship between reproductive hormones and acute phase proteins during estrous cycle and pregnancy in Spanish purebred broodmares

In some species, female steroid hormones modify the profile of acute phase proteins (APPs) during the estrous cycle and pregnancy, according to the ovulation, embryonic implantation and placental development; however, nowadays there's no experimental evidence for equine species. Objectives of this study were: to compare the serum amyloid A (SAA), haptoglobin (Hp) and C-reactive protein (CRP) concentrations between cyclic and pregnant mares, and to analyze the influence of estradiol-17β (E2) during estrous cycle or estrone sulfate (E1) during pregnancy, and progesterone (P4) on these proteins to assess their potential role to identify the cyclicity or pregnancy in Spanish mares. Blood samples were taken from 20 Purebred Spanish mares on the day of ovulation (day 0), on days +5 and +16 post-ovulation, and then, monthly during the whole pregnancy. SAA, Hp and CRP did not change between day 0, +5 and +16 post-ovulation days. P4 concentrations were significantly higher on day +16 than on days +5 and 0; and E2 concentrations were significantly higher on day 0 than day +5. On the other hand, pregnancy was characterized by a progressive increase in the Hp, variable modifications of E1 and P4 concentrations, without changes in SAA and CRP. The absence of significant differences in the APPs between days 0, +5 and +16, suggested that these proteins cannot be used as biomarkers of diagnosis of heat or pregnancy in Spanish mares, at least early, since the Hp later increases during the gestation. Nevertheless, it is possible to use them for comparative purposes with other equine breeds, as supervisor instrument of health status in breeding females as diagnostic tools to monitor pregnancy's development and/or subclinical reproductive inflammations, that could lead to the early embryonic death.

Neonatal Levels of Acute Phase Proteins and Risk of Autism Spectrum Disorder

BACKGROUND

Immune signaling pathways influence neurodevelopment and are hypothesized to contribute to the etiology of autism spectrum disorder (ASD). We aimed to assess risk of ASD in relation to levels of neonatal acute phase proteins (APPs), key components of innate immune function, measured in neonatal dried blood spots.

METHODS

We included 924 ASD cases, 1092 unaffected population-based controls, and 203 unaffected siblings of ASD cases in this case-control study nested within the register-based Stockholm Youth Cohort. Concentrations of 9 different APPs were measured in eluates from neonatal dried blood spots from cases, controls, and siblings using a bead-based multiplex assay.

RESULTS

Neonatal C-reactive protein was consistently associated with odds of ASD in case-control comparisons, with higher odds associated with the highest quintile compared with the middle quintile (odds ratio [OR] = 1.50, 95% confidence interval [CI] = 1.10-2.04) in adjusted analyses. In contrast, the lowest quintiles of α-2-macroglobulin (OR = 3.71, CI = 1.21-11.33), ferritin (OR = 4.20, CI = 1.40-12.65), and serum amyloid P (OR = 3.05, CI = 1.16-8.01) were associated with odds of ASD in the matched sibling comparison. Neonatal APPs varied with perinatal environmental factors and maternal/fetal phenotypes. Significant interactions in terms of risk for ASD were observed between neonatal APPs and maternal infection during late pregnancy, maternal anemia, and maternal psychiatric history.

CONCLUSIONS

Indicators of the neonatal innate immune response are associated with risk of ASD, although the nature of these associations varies considerably with factors in the perinatal environment and the genetic background of the comparison group.

De novo Synthesis of SAA1 in the Placenta Participates in Parturition

Serum amyloid A1 (SAA1) is an acute phase protein produced mainly by the liver to participate in immunomodulation in both sterile and non-sterile inflammation. However, non-hepatic tissues can also synthesize SAA1. It remains to be determined whether SAA1 synthesized locally in the placenta participates in parturition via eliciting inflammatory reactions. In this study, we investigated this issue by using human placenta and a mouse model. We found that SAA1 mRNA and protein were present in human placental villous trophoblasts, which was increased upon syncytialization as well as treatments with lipopolysaccharides (LPS), tumor necrosis factor-α (TNF-α), and cortisol. Moreover, significant increases in SAA1 abundance were observed in the placental tissue or in the maternal blood in spontaneous deliveries without infection at term and in preterm birth with histological chorioamnionitis. Serum amyloid A1 treatment significantly increased parturition-pertinent inflammatory gene expression including interleukin-1β (IL-1β), IL-8, TNF-α, and cyclooxygenase-2 (COX-2), along with increased PGF2α production in syncytiotrophoblasts. Mouse study showed that SAA1 was present in the placental junctional zone and yolk sac membrane, which was increased following intraperitoneal administration of LPS. Intraperitoneal injection of SAA1 not only induced preterm birth but also increased the abundance of IL-1β, TNF-α, and COX-2 in the mouse placenta. Conclusively, SAA1 can be synthesized in the human placenta, which is increased upon trophoblast syncytialization. Parturition is accompanied with increased SAA1 abundance in the placenta. Serum amyloid A1 may participate in parturition in the presence and absence of infection by inducing the expression of inflammatory genes in the placenta.

Interleukin-1β Induces Intracellular Serum Amyloid A1 Expression in Human Coronary Artery Endothelial Cells and Promotes its Intercellular Exchange

Serum amyloid A (SAA) is an acute-phase protein with important, pathogenic role in the development of atherosclerosis. Since dysfunctional endothelium represents a key early step in atherogenesis, we aimed to determine whether induced human coronary artery endothelial cells (HCAEC) modulate SAA1/2/4 expression and influence intracellular location and intercellular transport of SAA1. HCAEC were stimulated with 1 ng/ml IL-1β, 10 ng/ml IL-6, and/or 1 μM dexamethasone for 24 h. QPCR, Western blots, ELISA, and immunofluorescent labeling were performed for detection of SAA1/2/4 mRNA and protein levels, respectively. In SAA1 transport experiments, FITC- or Cy3-labeled SAA1 were added to HCAEC separately, for 24 h, followed by a combined incubation of SAA1-FITC and SAA1-Cy3 positive cells, with IL-1β and analysis by flow cytometry. IL-1β upregulated SAA1 (119.9-fold, p < 0.01) and SAA2 (9.3-fold; p < 0.05) mRNA expression levels, while mRNA expression of SAA4 was not affected. Intracellular SAA1 was found mainly as a monomer, while SAA2 and SAA4 formed octamers as analyzed by Western blots. Within HCAEC, SAA1/2/4 located mostly to the perinuclear area and tunneling membrane nanotubes. Co-culturing of SAA1-FITC and SAA1-Cy3 positive cells for 48 h showed a significantly higher percentage of double positive cells in IL-1β-stimulated (mean ± SD; 60 ± 4%) vs. non-stimulated cells (48 ± 2%; p < 0.05). IL-1β induces SAA1 expression in HCAEC and promotes its intercellular exchange, suggesting that direct communication between cells in inflammatory conditions could ultimately lead to faster development of atherosclerosis in coronary arteries.

Induction of pro-inflammatory genes by serum amyloid A1 in human amnion fibroblasts

Serum amyloid A1 (SAA1) is an acute response protein, which is mainly produced by the liver, during infection. However, it remains unknown whether SAA1 can be produced in human fetal membranes where it is able to elicit events pertinent to labor initiation. We demonstrated that SAA1 was expressed in the fibroblasts and epithelium of the amnion and the trophoblasts of the chorion. Further study in human amnion fibroblasts showed that SAA1 production was augmented by interleukin-1β (IL-1β) and cortisol alone and synergistically, and SAA1 in turn induced the expression of IL-1β, interleukin-6 (IL-6), cyclooxygenase-2 (COX-2) and PGE2 production. These effects of SAA1 were mediated through activation of the NF-κB, p38 and ERK1/2 pathways via the toll-like receptor 4 (TLR4). Inhibition of TLR4 attenuated not only SAA1-induced activation of NF-κB, p38 and ERK1/2 but also increases in IL-1β, IL-6 and COX-2 expression. Moreover, SAA1 expression was increased in human amnion tissue following spontaneous labor. In conclusion, this study has demonstrated for the first time that SAA1 can be produced in human fetal membranes, which can be greatly induced in the presence of proinflammatory cytokines and glucocorticoids thereby producing effects associated with parturition.

Structure and Expression of Different Serum Amyloid A (SAA) Variants and their Concentration-Dependent Functions During Host Insults

Serum amyloid A (SAA) is, like C-reactive protein (CRP), an acute phase protein and can be used as a diagnostic, prognostic or therapy follow-up marker for many diseases. Increases in serum levels of SAA are triggered by physical insults to the host, including infection, trauma, inflammatory reactions and cancer. The order of magnitude of increase in SAA levels varies considerably, from a 10- to 100-fold during limited inflammatory events to a 1000-fold increase during severe bacterial infections and acute exacerbations of chronic inflammatory diseases. This broad response range is reflected by SAA gene duplications resulting in a cluster encoding several SAA variants and by multiple biological functions of SAA. SAA variants are single-domain proteins with simple structures and few post-translational modifications. SAA1 and SAA2 are inducible by inflammatory cytokines, whereas SAA4 is constitutively produced. We review here the regulated expression of SAA in normal and transformed cells and compare its serum levels in various disease states. At low concentrations (10-100 ng/ml), early in an inflammatory response, SAA induces chemokines or matrix degrading enzymes via Toll-like receptors and functions as an activator and chemoattractant through a G protein-coupled receptor. When an infectious or inflammatory stimulus persists, the liver continues to produce more SAA (> 1000 ng/ml) to become an antimicrobial agent by functioning as a direct opsonin of bacteria or by interference with virus infection of host cells. Thus, SAA regulates innate and adaptive immunity and this information may help to design better drugs to treat specific diseases.

Maternal serum amyloid A level as a novel marker of primary unexplained recurrent early pregnancy loss

OBJECTIVE

To assess maternal serum amyloid A (SAA) levels among women with primary unexplained recurrent early pregnancy loss (REPL).

METHODS

A prospective study was conducted among women with missed spontaneous abortion in the first trimester at Ain Shams University Maternity Hospital, Cairo, Egypt, between January 21 and December 25, 2014. Women with at least two consecutive primary unexplained REPLs and no previous live births were enrolled. A control group was formed of women with no history of REPL who had at least one previous uneventful pregnancy with no adverse outcomes. Serum samples were collected to measure SAA levels. The main outcome was the association between SAA and primary unexplained REPL.

RESULTS

Each group contained 96 participants. Median SAA level was significantly higher among women with REPL (50.0 μg/mL, interquartile range 26.0-69.0) than among women in the control group (11.6 μg/mL, interquartile range 6.2-15.5; P<0.001). The SAA level was an independent indicator of primary unexplained REPL, after adjusting for maternal age and gestational age (odds ratio 1.12, 95% confidence interval 1.06-1.19; P<0.001).

CONCLUSION

Elevated SAA levels found among women with primary unexplained REPL could represent a novel biomarker for this complication of pregnancy.

Identification of serum protein markers for early diagnosis of pregnancy in buffalo

Improper or delayed pregnancy diagnosis has significant impact over animal production, particularly in buffaloes which inherently suffer from several reproductive inefficiencies. Thus the present study has undertaken to identify serum protein markers pertaining to early pregnancy diagnosis in buffaloes. Serum samples were collected from 10 pregnant Murrah Buffalo heifers at weekly intervals from days 0-35 post-artificial insemination and from 12 inseminated non-pregnant cyclic buffalo heifers on days 0, 7, 14 and 21. Two-dimensional gel electrophoresis and densitometric analysis revealed the presence of five protein spots showing average density fold change of ≥4 during early pregnancy. Mass spectrometry analysis identified these up-regulated proteins as anti-testosterone antibody light chain, apolipoprotein A-II precursor, serum amyloid A, cytokeratin type II, component IV isoform 1, which are have established roles in embryogenesis, but over-expression of the fifth identified protein immunoglobulin lambda light chain in pregnancy has been elucidated as a novel finding in the current study. Further, with bioinformatics analysis, potential antigenic B-cell epitopes were predicted for all these five proteins. An antibody cocktail-based approach involving antibodies against all these five up-regulated entire proteins or their epitopes could be developed for early detection of pregnancy in buffaloes. © 2016 Japanese Society of Animal Science.

The cytokine-serum amyloid A-chemokine network

Levels of serum amyloid A (SAA), a major acute phase protein in humans, are increased up to 1000-fold upon infection, trauma, cancer or other inflammatory events. However, the exact role of SAA in host defense is yet not fully understood. Several pro- and anti-inflammatory properties have been ascribed to SAA. Here, the regulated production of SAA by cytokines and glucocorticoids is discussed first. Secondly, the cytokine and chemokine inducing capacity of SAA and its receptor usage are reviewed. Thirdly, the direct (via FPR2) and indirect (via TLR2) chemotactic effects of SAA and its synergy with chemokines are unraveled. Altogether, a complex cytokine-SAA-chemokine network is established, in which SAA plays a key role in regulating the inflammatory response.

Expression of serum amyloid A4 in human trophoblast-like choriocarcinoma cell lines and human first trimester/term trophoblast cells

Trophoblast invasion into uterine tissues represents a hallmark of first trimester placental development. As expression of serum amyloid A4 (SAA4) occurs in tumorigenic and invasive tissues we here investigated whether SAA4 is present in trophoblast-like human AC1-M59/Jeg-3 cells and trophoblast preparations of human first trimester and term placenta. SAA4 mRNA was expressed in non-stimulated and cytokine-treated AC1-M59/Jeg-3 cells. In purified trophoblast cells SAA4 mRNA expression was upregulated at weeks 10 and 12 of pregnancy. Western-blot and immunohistochemical staining of first trimester placental tissue revealed pronounced SAA4 expression in invasive trophoblast cells indicating a potential role of SAA4 during invasion.

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SAA4 mRNA is expressed in Jeg-3 and AC1-M59 cells.

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SAA4 mRNA is expressed in first trimester/term trophoblast cells.

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SAA4 mRNA is upregulated at pregnancy week 10 and 12.

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SAA4 protein is present in interstitial, intramural and intraluminal trophoblast cells.

Serum amyloid A promotes invasion of feline mammary carcinoma cells

The serum amyloid A (SAA) concentration is higher in mammary tumors with metastases in both humans and animals. In the present study, the direct effects of recombinant feline SAA (rfSAA) protein on invasiveness of feline mammary carcinoma cells were evaluated. As an indicator of invasiveness, matrix metalloproteinase-9 (MMP-9) expression was investigated in 4 feline mammary carcinoma cell lines of different origins. In 3 of 4 cell lines, MMP-9 expression was significantly increased by rfSAA stimulation. The invasive capacities of feline mammary carcinoma cells were also stimulated by rfSAA. The findings of this study have identified a novel role for SAA in mammary tumorigenesis and suggest that therapeutic strategies targeting SAA may provide new alternatives in treating tumor invasion and metastasis.

Serum amyloid A in the placenta and its role in trophoblast invasion

The serum amyloid A (SAA) protein is known to function in the acute phase response and immunoregulation. Recently, SAA has been shown to be involved in cell proliferation, differentiation and migratory behavior in different cell types. Here, we evaluated whether exogenous SAA could influence trophoblast invasion and differentiation using both the trophoblast-like BeWo cell line and fully differentiated human extravillous trophoblast cells (EVT) isolated from term placentae. SAA stimulated BeWo cell invasion, as measured in Matrigel invasion assays, and induced metalloprotease mRNA expression and activity. Given that BeWo cells express Toll-like receptor 4 (TLR4), a known receptor for SAA, we examined the role of TLR4 in SAA-induced invasion using a TLR4 neutralizing antibody. We also tested whether SAA could affect markers of trophoblast syncytialization in BeWo cells. We observed that SAA decreased βhCG secretion and did not influence trophoblast syncytialization. Using EVT cells isolated from human term basal plates, we confirmed that SAA at 1 and 10 µg/mL doubled EVT invasion in a TLR4-dependent manner, but at 20 µg/mL inhibited EVT cells invasiveness. In addition, we observed that SAA was expressed in both BeWo cells and human term placentae, specifically in the syncytiotrophoblast, decidual cells and EVT. In conclusion, SAA was identified as a molecule that functions in the placental microenvironment to regulate metalloprotease activity and trophoblast invasion, which are key processes in placentation and placental homeostasis.

Systemic AA amyloidosis as a unique manifestation of a combined mutation of TNFRSF1A and MEFV genes

We report the case of a 22-year-old Caucasian woman presenting with a new-onset nephrotic syndrome with normal renal function during the 35th week of pregnancy. AA (secondary) amyloidosis was further diagnosed at the renal biopsy. Extensive genetic testing revealed that the patient was heterozygous for both TNFRSF1A p.R92Q and MEFV p.M694I mutations leading to an autoinflammatory syndrome characterized by amyloid deposition as the sole manifestation.

Angiogenic factors and acute-phase proteins in serum samples of preeclampsia and HELLP patients: a matched-pair analysis

OBJECTIVES

To investigate the serum level distribution of angiogenic markers (PlGF, endoglin, sFlt-1) and acute-phase proteins (SAA, CRP) in patients with HELLP syndrome or preeclampsia (PE) including matched controls.

METHODS

The matching procedure revealed 46 controls for 23 HELLP cases, and 81 controls for 42 preeclamptic patients. Maternal serum concentrations were determined by immunoassays.

RESULTS

SAA and CRP levels were significantly higher in HELLP patients compared with controls. This finding was not observed in preeclamptic subgroup. Pro-angiogenic PlGF is significantly lower in PE and HELLP syndrome. Anti-angiogenic endoglin is significantly higher in PE and HELLP syndrome. The sFlt-1 analysis supports the anti-angiogenic shift in HELLP and preeclamptic patients, but with smaller differences between subgroups. The SAA/PlGF ratio showed the highest ROC value of all tested parameters in discrimination between HELLP and HELLP controls.

CONCLUSIONS

These findings support the concept that patients with HELLP syndrome have both an anti-angiogenic state and a pronounced inflammatory response, while patients with PE are characterized only by an anti-angiogenic shift.

LPA-induced suppression of periostin in human osteosarcoma cells is mediated by the LPA(1)/Egr-1 axis

Lysophosphatidic acid (LPA), a naturally occurring bioactive phospholipid, mediates a multitude of (patho)physiological events including activation of mitogen-activated protein kinases (MAPKs). As LPA may induce cellular reponses in human osteosarcoma, the present study aimed at investigating expression of various LPA receptors, LPA-mediated activation of MAPK via G-protein coupling, and expression of early response genes in a cellular model for human osteosarcoma. We show that MG-63 cells express three members of the endothelial differentiation gene (Edg) family of G-protein coupled receptor transcripts (LPA(1-3)) but only two (LPA(4/5)) out of three members of the non-Edg family LPA receptor transcripts. Stimulation of MG-63 cells with LPA or synthetic LPA receptor agonists resulted in p42/44 MAPK phosphorylation via LPA(1)-LPA(3) receptors. Using pharmacological inhibitors, we show that LPA-mediated phosphorylation of p42/44 MAPK by LPA receptor engagement is transmitted by G(αi)-dependent pathways through the Src family of tyrosine kinases. As a consequence, a rapid and transient upregulation of the zinc finger transcription factor early growth response-1 (Egr-1) was observed. Egr-1 expression was strictly mediated via G(αi)/Src/p42/44 MAPK pathway; no involvement of the G(αq/11)/PLC/PKC or the PLD/PI3 kinase/Akt pathways was found. LPA-induced expression of functional Egr-1 in MG-63 cells could be confirmed by electrophoretic mobility shift assay. LPA-induced Egr-1 upregulation was accompanied by a time-dependent decrease of periostin (previously called osteoblast-specific factor 2), a cell adhesion protein for pre-osteoblasts. Silencing of LPA(1) and/or Egr-1 in MG-63 cells reversed LPA-mediated suppression of periostin. We here demonstrate a crosslink between Egr-1 and periostin in cancer cells, in particular in human osteosarcoma.

Identification of potential serum biomarkers for Wilms tumor after excluding confounding effects of common systemic inflammatory factors

Wilms tumor is the most common pediatric tumor of the kidney. Previous studies have identified several serum biomarkers for Wilms tumor; however, they lack sufficient specificity and may not adequately distinguish Wilms tumor from confounding conditions. To date, no specific protein biomarker has been confirmed for this pediatric tumor. To identify novel serum biomarkers for Wilms tumor, we used proteomic technologies to perform protein profiling of serum samples from pre-surgery and post-surgery patients with Wilms tumor and healthy controls. Some common systemic inflammatory factors were included to control for systemic inflammation. By comparing protein peaks among the three groups of sera, we identified two peaks (11,526 and 4,756 Da) showing significant differential expression not only between pre-surgery and control sera but also between pre-surgery and post-surgery sera. These two peaks were identified as serum amyloid A1 (SAA1) and apolipoprotein C-III (APO C-III). Western blot analysis confirmed that both proteins were expressed at higher levels in pre-surgery sera than in post-surgery and control sera. Using the method of leave-1-out for cross detection, we demonstrate that detection of these two candidate biomarkers had high sensitivity and specificity in discriminating pre-surgery sera from post-surgery and normal control sera. Taken together, these findings suggest that SAA1 and APO C-III are two potential biomarkers for Wilms tumor.

Four and a half LIM protein 1C (FHL1C): a binding partner for voltage-gated potassium channel K(v1.5)

Four-and-a-half LIM domain protein 1 isoform A (FHL1A) is predominantly expressed in skeletal and cardiac muscle. Mutations in the FHL1 gene are causative for several types of hereditary myopathies including X-linked myopathy with postural muscle atrophy (XMPMA). We here studied myoblasts from XMPMA patients. We found that functional FHL1A protein is completely absent in patient myoblasts. In parallel, expression of FHL1C is either unaffected or increased. Furthermore, a decreased proliferation rate of XMPMA myoblasts compared to controls was observed but an increased number of XMPMA myoblasts was found in the G₀/G₁ phase. Furthermore, low expression of K_v1.5, a voltage-gated potassium channel known to alter myoblast proliferation during the G₁ phase and to control repolarization of action potential, was detected. In order to substantiate a possible relation between K_v1.5 and FHL1C, a pull-down assay was performed. A physical and direct interaction of both proteins was observed in vitro. In addition, confocal microscopy revealed substantial colocalization of FHL1C and K_v1.5 within atrial cells, supporting a possible interaction between both proteins in vivo. Two-electrode voltage clamp experiments demonstrated that coexpression of K_v1.5 with FHL1C in Xenopus laevis oocytes markedly reduced K⁺ currents when compared to oocytes expressing K_v1.5 only. We here present the first evidence on a biological relevance of FHL1C.

Colchicine-sensitive nephrotic syndrome due to AA amyloidosis

A 28-year-old women is presented who was evaluated for a new-onset postpartum nephrotic syndrome with normal renal function. Histological diagnosis was AA amyloidosis but no underlying disease has been diagnosed despite extensive workup. Complete remission was achieved with colchicine. Upon discontinuation of colchicines, the patient's nephrotic syndrome flared up but completely responded to reinstitution of colchicine therapy. Remission of this patient's nephrotic syndrome is thus not attributable to resolution of any "idiopathic" primary disease.

Cancer-specific MALDI-TOF profiles of blood serum and plasma: biological meaning and perspectives

MALDI-TOF mass-spectrometry has become a popular tool of cancer research during the last decade. High throughput and relative simplicity of this technology have made it attractive for biomarker discovery and validation across various platforms in blood serum/plasma. Many technical approaches have been developed for plasma/serum profiling including protein-chip based SELDI-TOF mass-spectrometry, purification of serum on magnetic beads, analysis of carrier-associated fraction and mass-spectrometric immunoassays. Extensive data about the identity of differential features detected on mass-spectra up to now makes it possible to draw conclusions about potency and perspectives of MALDI-TOF mass-spectrometry in this field. A great majority of identified differentially expressed proteins are either house-keeping or inflammatory proteins as well as their modifications or fragments. Discriminating ability of mass-spectra is likely to be based on differential modification and fragmentation patterns of abundant serum proteins reflecting activity of enzymes including proteases and their inhibitors.

Plasma biomarkers in a mouse model of preterm labor

Preterm labor (PTL) is frequently associated with inflammation. We hypothesized that biomarkers during pregnancy can identify pregnancies most at risk for development of PTL. An inflammation-induced mouse model of PTL was used. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry was used to analyze and compare the plasma protein (PP) profile between CD-1 mice injected intrauterine with either lipopolysaccharide (LPS) or PBS on d 14.5 of gestation. The median differences of normalized PP peaks between the two groups were determined using the Mann-Whitney U test and the false discovery rate. In a second series of experiments, both groups of mice were injected with a lower dose of LPS. A total of 1665 peaks were detected. Thirty peaks were highly differentially expressed (p < 0.0001) between the groups. Two 11 kDa protein peaks were identified by MALDI-TOF/TOF-MS and confirmed to be mouse serum amyloid A (SAA) 1 and 2. Plasma SAA2 levels were increased in LPS-treated animals compared with controls and in LPS-treated animals that delivered preterm vs. those that delivered at term. SAA2 has the potential to be a plasma biomarker that can identify pregnancies at risk for development of PTL.

Aberrant expression of serum amyloid A in head and neck squamous cell carcinoma

Serum amyloid A (SAA) is an acute-phase reactant, the blood level of which is often elevated in response to some types of neoplasia. Here, we investigated expression of the gene SAA1 and the protein SAA in head and neck squamous cell carcinoma (HNSCC) and normal oral mucosal tissues as well as blood SAA levels in HNSCC patients. Also, we investigated the effects of inhibiting signal transducer and activator of transcription 3 (STAT3) signaling on SAA1 expression in the HNSCC cell line SAS. Serum SAA levels in HNSCC patients were significantly higher than those in healthy volunteers. In addition, real-time quantitative reverse transcription-polymerase chain reaction analysis revealed a significantly higher SAA1 expression level in HNSCC than in normal mucosa (P < 0.0001). Furthermore, Western blot and immunohistochemical analyzes revealed that high expression of SAA in carcinomas was detected predominantly in tumor cells, but not in normal mucosal tissues. An inhibitor of STAT3 activation, AG490, significantly reduced SAA1 expression in SAS cells. These data demonstrated that SAA was up-regulated in HNSCC through the Janus kinase-STAT3 pathway.

Serum amyloid A: an acute-phase protein involved in tumour pathogenesis

The synthesis of acute-phase protein serum amyloid A (SAA) is largely regulated by inflammation- associated cytokines and a high concentration of circulating SAA may represent an ideal marker for acute and chronic inflammatory diseases. However, SAA is also synthesized in extrahepatic tissues, e.g. human carcinoma metastases and cancer cell lines. An increasing body of in vitro data supports the concept of involvement of SAA in carcinogenesis and neoplastic diseases. Accumulating evidence suggests that SAA might be included in a group of biomarkers to detect a pattern of physiological events that reflect the growth of malignancy and host response. This review is meant to provide a broad overview of the many ways that SAA could contribute to tumour development, and accelerate tumour progression and metastasis, and to gain a better understanding of this acute-phase reactant as a possible link between chronic inflammation and neoplasia.

Serum amyloid A as indicator of distant metastases but not as early tumor marker in patients with renal cell carcinoma

The aim of the present study was to evaluate the clinical significance of the concentration of serum amyloid A (SAA) in patients with renal cell carcinoma (RCC). SAA protein was determined with enzyme-linked immunosorbent assay in serum samples of 55 healthy controls and 98 RCC patients subdivided into groups with localized tumor (N0M0, n=40), with lymph node metastases (N1M0, n=13), and distant metastases (M1, n=45). SAA concentrations in controls and N0M0 group of RCC were not different while SAA concentrations were significantly elevated in M1 patients compared to the N1M0 and N0M0 patients. In this respect, SAA provided an accurate detection of distant metastases with the area under the ROC curve of 0.86. SAA was identified as a significant independent factor of survival in RCC patients using the multivariate Cox proportional hazards regression model. SAA could be a useful analyte in predicting the survival outcome of RCC patients.

Gene network and canonical pathway analysis in prostate cancer: a microarray study

The molecular mechanism playing a role in the development of prostate cancer (PCA) is not well defined. We decided to determine the changes in gene expression in PCA tissues and to compare them to those in non-cancerous samples. Prostate tissue samples were collected by needle biopsy from 21 PCA and 10 benign prostate hyperplasic (BPH) patients. Total RNA was isolated, cDNA was synthesized, and gene expression levels were determined by microarray method. In the progression to PCA, 738 up-regulated and 515 down-regulated genes were detected in samples. Analysis using Ingenuity Pathway Analysis (IPA) software revealed that 466 network and 423 functions-pathways eligible genes were up-regulated, and 363 network and 342 functions-pathways eligible genes were down-regulated. Up-regulated networks were identified around IL-1beta and insulin-like growth factor-1 (IGF-1) genes. The NFKB gene was centered around two up- and down-regulated networks. Up-regulated canonical pathways were assigned and four of them were evaluated in detail: acute phase response, hepatic fibrosis, actin cytoskeleton, and coagulation pathways. Axonal guidance signaling was the most significant down-regulated canonical pathway. Our data provide not only networks between the genes for understanding the biologic properties of PCA but also useful pathway maps for future understanding of disease and the construction of new therapeutic targets.

Endothelin (ET)-1 and ET-3 promote expression of c-fos and c-jun in human choriocarcinoma via ET(B) receptor-mediated G(i)- and G(q)-pathways and MAP kinase activation

BACKGROUND AND PURPOSE

Endothelins (ETs) and their G protein-coupled receptors exert key physiological functions during normal and aberrant placental development. Trophoblast cells mediate the contact between the embryo and the mother, by establishing a transient organ, the placenta. Choriocarcinoma cells display many of the biochemical and morphological characteristics of in utero invasive trophoblast cells and may therefore be used as a suitable model to study epithelial tumour progression of foetal-derived cells.

EXPERIMENTAL APPROACH

The present study aimed at investigating ET receptor-mediated activation of the mitogen-activated protein kinase (MAPK) pathway in human choriocarcinoma.

KEY RESULTS

Both JAR and Jeg-3 choriocarcinoma cell lines expressed ET receptor subtype B (ET(B)) but not ET(A) receptor transcripts. ET(B) receptor engagement by ET-1 and ET-3 resulted in a similar time- and concentration-dependent phosphorylation of p42/44 MAPK, also known as extracellular regulated kinase 1/2. Using specific pharmacological antagonists/inhibitors, we showed that ET-1/-3-mediated signal transduction by the ET(B) receptor is transmitted via G(i)- and G(q)-dependent pathways through activation of the Src (G(i)) and protein kinase C (G(q)) axis that converge at Ras/Raf, leading to downstream activation of p42/44. On a functional level, ET(B) engagement and subsequent phosphorylation of p42/44 resulted in enhanced transcription of the immediate early response genes c-fos and c-jun, a process commonly assumed to be mediated by the ET(A) receptor, and increased cell growth and relative cell area.

CONCLUSIONS AND IMPLICATIONS

As human choriocarcinoma cells secrete ETs, pharmacological antagonism of ETs and/or ET(B) receptor-mediated signal transduction could represent a likely target therapy for choriocarcinoma.

Expression of serum amyloid A transcripts in human bone tissues, differentiated osteoblast-like stem cells and human osteosarcoma cell lines

Although the liver is the primary site of cytokine-mediated expression of acute-phase serum amyloid A (SAA) protein, extrahepatic production has also been reported. Besides its role in amyloidosis and lipid homeostasis during the acute-phase, SAA has recently been assumed to contribute to bone and cartilage destruction. However, expression of SAA in human osteogenic tissue has not been studied. Therefore, we first show that SAA1 (coding for the major SAA isoform) but not SAA2 transcripts are expressed in human trabecular and cortical bone fractions and bone marrow. Next, we show expression of (i) IL-1, IL-6, and TNF receptor transcripts; (ii) the human homolog of SAA-activating factor-1 (SAF-1, a transcription factor involved in cytokine-mediated induction of SAA genes); and (iii) SAA1/2 transcripts in non-differentiated and, to a higher extent, in osteoblast-like differentiated human mesenchymal stem cells. Third, we provide evidence that human osteoblast-like cells of tumor origin (MG-63 and SAOS-2) express SAF-1 under basal conditions. SAA1/2 transcripts are expressed under basal conditions (SAOS-2) and cytokine-mediated conditions (MG-63 and SAOS-2). RT-PCR, Western blot analysis, and immunofluorescence technique confirmed cytokine-mediated expression of SAA on RNA and protein level in osteosarcoma cell lines while SAA4, a protein of unknown function, is constitutively expressed in all osteogenic tissues investigated.

Molecular interactions of acute phase serum amyloid A: possible involvement in carcinogenesis

Acute phase serum amyloid A (A-SAA) is a well-known marker of inflammation. The present review summarizes data on the regulation of A-SAA expression, signaling pathways which it is involved in, its effects, and possible influences on progression of malignant tumors.

Inflammation-responsive transcription factor SAF-1 activity is linked to the development of amyloid A amyloidosis

Abundantly expressed serum amyloid A (SAA) protein under chronic inflammatory conditions gives rise to insoluble aggregates of SAA derivatives in multiple organs resulting in reactive amyloid A (AA) amyloidosis, a consequence of rheumatoid arthritis, Crohn's disease, ankylosing spondylitis, familial Mediterranean fever, and Castleman's disease. An inflammation-responsive transcription factor, SAF (for SAA activating factor), has been implicated in the sustained expression of amyloidogenic SAA under chronic inflammatory conditions. However, its role in the pathogenesis of AA amyloidosis has thus far remained obscure. In this paper we have shown that SAF-1, a major member of the SAF family, is abundantly present in human AA amyloidosis patients. To assess whether SAF-1 is directly linked to the pathogenesis of AA amyloidosis, we have developed a SAF-1 transgenic mouse model. SAF-1-overexpressing mice spontaneously developed AA amyloidosis at the age of 14 mo or older. Immunohistochemical analysis confirmed the nature of the amyloid deposits as an AA type derived from amyloidogenic SAA1. Furthermore, SAF-1 transgenic mice rapidly developed severe AA amyloidosis in response to azocasein injection, indicating increased susceptibility to inflammation. Also, during inflammation SAF-1 transgenic mice exhibited a prolonged acute phase response, leading to an extended period of SAA synthesis. Together, these results provide direct evidence that SAF-1 plays a key role in the development of AA amyloidosis, a consequence of chronic inflammation.