Factor VII activating protease

FSAP aggravated endothelial dysfunction and neurological deficits in acute ischemic stroke due to large vessel occlusion

Revascularization and angiogenesis, as substrates of sustained collateral circulation, play a crucial role in determining the severity and clinical outcome of acute ischemic stroke (AIS) due to large vessel occlusion (LVO). Developing an adjunct biomarker to help identify and monitor collateral status would aid stroke diagnosis and prognosis. To screen the potential biomarkers, proteomic analysis was performed in this study to identify those distinct plasma protein profiles in AIS due to LVO with different collateral status. Interestingly, we found that levels of Plasma Factor VII Activating Protease (FSAP) significantly increased in those AIS patients with poor collaterals, and were correlated with worse neurological outcome. Furtherly, both in vitro and in vivo models of ischemic stroke were used to explore pathological mechanisms of FSAP in endothelial dysfunction. We demonstrated that the FSAP inhibitor, high-molecular-weight hyaluronan (HMW-HA), enhanced the pro-angiogenic vascular factors, improved the integrity of brain blood barrier, and promoted newly formed cerebral microvessels in the ischemic penumbra, consequently improving neurological function. To elucidate the pathways that might contribute to revascularization during LVO, we applied transcriptomic analysis via unbiased RNA sequencing and showed that Wnt signaling was highly involved in FSAP mediated endothelial dysfunction. Notably, inhibition of Wnt5a largely reversed the protective effects from HMW-HA treatment, implying that FSAP might aggravate endothelial dysfunction and neurological deficits by regulating Wnt5a signaling. Therefore, FSAP may represent a potential biomarker for collateral status after LVO and a promising therapeutic target to be explored in the treatment of stroke.

Chromosome 10q25 polymorphism is associated with susceptibility to large artery atherosclerotic stroke

BACKGROUND AND AIMS

A recent genome-wide association study (GWAS) reported an association between a single nucleotide polymorphism (SNP) rs11196288 and risk of early-onset large artery atherosclerotic (LAA) stroke in European population. The interaction between genetic and environmental factors such as age has also received increasing attention. We performed this study to investigate the association between the rs11196288A > G polymorphism and LAA stroke risk in the Chinese Han population and test whether age interacts rs11196288 to influence LAA stroke risk.

METHODS

Genotyping of rs11196288 was performed in 1066 LAA stroke patients and 1167 healthy controls. Multivariate logistic regression analyses were applied to assess the effect of the rs11196288A > G polymorphism on susceptibility and short-term outcome of LAA stroke. Nomograms were performed to estimate probability of risk for an individual patient.

RESULTS

A significant decrement of LAA stroke risk was found in co-dominant (AG vs. AA, OR = 0.76, 95% CI = 0.64-0.91, P = 0.003; GG vs. AA, OR = 0.65, 95% CI = 0.50-0.85, P = 0.002), dominant (AG/GG vs. AA, OR = 0.74, 95% CI = 0.62-0.87, P < 0.001) and recessive models (GG vs. AA/AG, OR = 0.76, 95% CI = 0.59-0.97, P = 0.028) of rs11196288. However, the interaction between age and genotypes of rs11196288 was not statistically significant, and no significant association was observed between the rs11196288A > G polymorphism and short-term outcome of LAA stroke (P > 0.05).

CONCLUSIONS

In the southeastern Chinese population, the rs11196288A > G polymorphism is associated with decreased risk of LAA stroke.

Interaction of factor VII activating protease (FSAP) with neutrophil extracellular traps (NETs)

The circulating zymogen form of Factor VII activating protease (FSAP) can be activated by histones and nucleosomes in vivo. These cell-death-associated nuclear factors are also actively extruded into the extracellular space by neutrophils through a process called neutrophil extracellular trap (NET) formation (NETosis). NETs are thought to be involved in host defense, inflammation as well as thrombosis. We have investigated the bidirectional interactions of FSAP and NETs. Phorbol ester-mediated NET formation was marginally stimulated by FSAP. Plasma-derived FSAP as well as exogenous FSAP bound to NETs. There was co-localization of FSAP and NETs in coronary thrombi from patients with acute myocardial infarction. Contrary to our expectations no activation of pro-FSAP by NETs was evident. However, after disintegration of NETs with DNase, a robust activation of pro-FSAP, due to release of histones from nucleosomes, was detected. The released histones were in turn degraded by FSAP. Histone cytotoxicity towards endothelial cells was neutralized by FSAP more potently than by activated protein C (APC). One more consequence of histone degradation was a decrease in nucleosome release from apoptotic neutrophils. Taken together, NETs bind to FSAP, but do not activate pro-FSAP unless histones are released from NETs by DNAse. This activation of FSAP is likely to be important in diminishing the cytotoxic effect of histones, thus limiting the damaging effect of NETosis.

Association of GWAS-Reported Variant rs11196288 near HABP2 with Ischemic Stroke in Chinese Han Population

A recent genome-wide association analysis identified a novel single nucleotide polymorphism locus on chromosome 10q25.3 (rs11196288, near HABP2) associated with the risk of early-onset ischemic stroke (IS) in European population, but not with late-onset IS. However, the role of this genome-wide association study (GWAS)-reported variant in ischemic stroke in Chinese Han population remained unknown. In our study, 389 adult ischemic stroke patients with an age of onset <60 years and 389 matched healthy controls were enrolled to investigate association of rs11196288 genotypes with early-onset ischemic stroke and its subtypes; the association was further examined in another independent population consisting of 349 ischemic stroke patients with an age of onset ≧60 years and 349 matched healthy individuals. Logistic regression analysis showed no significant association between rs11196288 and early-onset ischemic stroke (IS), large artery atherosclerotic (LAA) stroke, or small vessel disease (SVD) stroke (all P > 0.050). Nevertheless, in subgroup analysis of the older population, rs11196288 presented significant effect on late-onset SVD stroke susceptibility in the dominant model (GG/GA vs AA, OR 1.70; 95%CI 1.02 to 2.85; P = 0.042). The results indicated that the role of rs11196288 polymorphism in ischemic stroke susceptibility in Chinese Han population may be different from that in European. Larger studies with diverse populations are warranted to confirm and extend our findings.

The various assays for measuring activity states of factor VIIa in plasma and therapeutic products: Diagnostic value and analytical usefulness in various pathophysiological states

The key coagulation factor FVII, and its activated form FVIIa, present a major interest for their role at the initiation phase of blood coagulation, and because they can activate all blood coagulation cascade, through the extrinsic, but also the intrinsic pathway. Blood activation initiated through FVII is first presented, as it is understood nowadays. Measurement of FVII and FVIIa were of main interest for epidemiological studies, but FVIIa contribution to assay results was only deduced. The introduction of specific FVIIa assays, functional or immunoassays, allowed measuring directly FVIIa without any interference of non-activated FVII, or other coagulation factors or their activated forms. The various methods available, and their characteristics are presented, with a special focus on two assays developed by our group for FVIIa (a clotting one and a chromogenic one). The FVIIa clotting assay shows evident superiority for measuring its activity in plasma, in pathophysiological conditions. The normal range is <2.5ng/ml, which represents less than 0.5% of the FVII protein. FVIIa is elevated in some pathological states. The chromogenic assay is of interest for assigning the potency of FVIIa concentrates, as it has a higher dynamic range. Both assays are fully automatable on laboratory instruments, and standardized in a satisfactory manner thanks to the use of the FVIIa concentrate WHO International Standard (NIBSC). The various applications and usefulness of FVIIa laboratory assays are discussed, for the measurement of therapeutic products, or for following recoveries in treated patients, including hemophiliacs with inhibitors, patients with severe bleeding risk (liver diseases, surgery, trauma, …), and lastly for measurement of its activity in therapeutic products.

Genome-Wide Association Analysis of Young-Onset Stroke Identifies a Locus on Chromosome 10q25 Near HABP2

BACKGROUND AND PURPOSE

Although a genetic contribution to ischemic stroke is well recognized, only a handful of stroke loci have been identified by large-scale genetic association studies to date. Hypothesizing that genetic effects might be stronger for early- versus late-onset stroke, we conducted a 2-stage meta-analysis of genome-wide association studies, focusing on stroke cases with an age of onset <60 years.

METHODS

The discovery stage of our genome-wide association studies included 4505 cases and 21 968 controls of European, South-Asian, and African ancestry, drawn from 6 studies. In Stage 2, we selected the lead genetic variants at loci with association P<5×10(-6) and performed in silico association analyses in an independent sample of ≤1003 cases and 7745 controls.

RESULTS

One stroke susceptibility locus at 10q25 reached genome-wide significance in the combined analysis of all samples from the discovery and follow-up stages (rs11196288; odds ratio =1.41; P=9.5×10(-9)). The associated locus is in an intergenic region between TCF7L2 and HABP2. In a further analysis in an independent sample, we found that 2 single nucleotide polymorphisms in high linkage disequilibrium with rs11196288 were significantly associated with total plasma factor VII-activating protease levels, a product of HABP2.

CONCLUSIONS

HABP2, which encodes an extracellular serine protease involved in coagulation, fibrinolysis, and inflammatory pathways, may be a genetic susceptibility locus for early-onset stroke.

The factor VII-activating protease (FSAP) enhances the activity of bone morphogenetic protein-2 (BMP-2)

Factor VII-activating protease (FSAP) is a circulating protease involved in the pathogenesis of atherosclerosis, calcification, and fibrotic processes. To understand how FSAP controls the balance of local growth factors, we have investigated its effect on the regulation of bone morphogenetic proteins (BMPs). BMP-2 is produced as a large pro-form and secreted as a mature heparin-binding growth factor after intracellular processing by pro-protein convertases (PCs). In this study, we discovered that FSAP enhances the biological activity of mature BMP-2 as well as its pro-form, as shown by osteogenic differentiation of C2C12 myoblasts. These findings were complemented by knockdown of FSAP in hepatocytes, which revealed BMP-2 processing by endogenous FSAP. N-terminal sequencing indicated that pro-BMP-2 was cleaved by FSAP at the canonical PC cleavage site, giving rise to mature BMP-2 (Arg(282)↓Gln(283)), as well as in the N-terminal heparin binding region of mature BMP-2, generating a truncated mature BMP-2 peptide (Arg(289)↓Lys(290)). Similarly, mature BMP-2 was also cleaved to a truncated peptide within its N-terminal region (Arg(289)↓Lys(290)). Plasmin exhibited a similar activity, but it was weaker compared with FSAP. Thrombin, Factor VIIa, Factor Xa, and activated protein C were not effective. These results were further supported by the observation that the mutation of the heparin binding region of BMP-2 inhibited the processing by FSAP but not by PC. Thus, the proteolysis and activation of pro-BMP-2 and mature BMP-2 by FSAP can regulate cell differentiation and calcification in vasculature and may explain why polymorphisms in the gene encoding for FSAP are related to vascular diseases.

Lac color inhibits development of rat thyroid carcinomas through targeting activation of plasma hyaluronan-binding protein

Coccid-derived natural food colorants contain active ingredients that potentiate inhibition of tissue proteolysis mediated by activation of plasma hyaluronan-binding protein (PHBP). In the present study, we examined the effect of lac color (LC) and cochineal extract (CE), representative coccid-derived colorants containing laccaic acid and carminic acid as active ingredients, in an intracapsular invasion model of experimental thyroid cancers using rats. One week after initiation with N-bis(hydroxypropyl)nitrosamine, male F344/NSIc rats were fed a powdered diet containing 5.0% LC or 3.0% CE during promotion with 0.15% sulfadimethoxine (SDM) in the drinking water for 13 weeks. Capsular invasive carcinomas (CICs) and lung metastases were decreased by LC treatment and accompanied by transcript downregulation on angiogenesis and PHBP-related tissue proteolysis in CICs. In contrast, CE upregulated angiogenesis-related genes in CICs. PHBP was expressed in capsular macrophages and thyroid proliferative lesions with increased intensity in CICs, and LC decreased PHBP-expressing CICs. The size of CICs and their proliferation activity, however, were unchanged compared with those treated with SDM alone. Suppression of cancer by invasion by LC was more evident after an eight-week treatment, exhibiting a profound decrease in tenascin-C-positive early invasive foci and marked reductions in capsular inflammation and fibrosis. These results suggest that LC and CE exerted dissimilar effects on CIC development, the former suppressing the initial step of neoplastic cell invasion into the capsule by targeting PHBP activity of macrophages and neoplastic cells on tissue proteolysis involving inflammatory responses and angiogenesis, and the latter promoting angiogenesis of developed CICs at later stages.