Regulation of monocyte/macrophage function by factor VII activating protease (FSAP)

Nutraceuticals as Modulators of Immune Function: A Review of Potential Therapeutic Effects

Dietary supplementation with nutraceuticals can promote optimal immune system activation, modulating different pathways that enhance immune defenses. Therefore, the immunity-boosting effects of nutraceuticals encompass not only immunomodulatory but also antioxidant, antitumor, antiviral, antibacterial, and antifungal properties, with therapeutic effects against diverse pathological conditions. However, the complexity of the pathways that regulate the immune system, numerous mechanisms of action, and heterogeneity of the immunodeficiencies, and subjects treated make their application in the clinical field difficult. Some nutraceuticals appear to safely improve immune system function, particularly by preventing viral and bacterial infections in specific groups, such as children, the elderly, and athletes, as well as in frail patients, such as those affected by autoimmune diseases, chronic diseases, or cancer. Several nutraceuticals, such as vitamins, mineral salts, polyunsaturated omega-3 fatty acids, many types of phytocompounds, and probiotic strains, have the most consolidated evidence in humans. In most cases, further large and long-term randomized clinical trials are needed to confirm the available preliminary positive data.

Proteomics Landscape Mapping of Organ-Resolved Behçet's Disease Using In-Depth Plasma Proteomics for Identifying Hyaluronic Binding Protein 2 Expression Associated With Vascular Involvement

OBJECTIVE

This study was undertaken to elucidate the pathogenesis and heterogeneity of Behçet's disease (BD) involving different organs using in-depth proteomics to identify the biomarkers for clinical assessment and treatment of patients with BD.

METHODS

We measured the expression levels of proteins in plasma samples from 98 patients with BD and from 31 healthy controls using our in-depth proteomics platform with a data-independent acquisition mass spectrometer and antibody microarray. We performed bioinformatics analyses of the biologic processes and signaling pathways that were changed in the BD group and constructed a proteomics landscape of organ-resolved BD pathogenesis. We then validated the biomarkers of disease severity and the vascular subset in an independent cohort of 108 BD patients and 29 healthy controls using an enzyme-linked immunosorbent assay.

RESULTS

The BD group had 220 differentially expressed proteins, which discriminated between BD patients (88.6%) and healthy controls (95.5%). The bioinformatics analyses revealed different biologic processes associated with BD pathogeneses, including complement activation, wound healing, angiogenesis, and leukocyte-mediated immunity. Furthermore, the constructed proteomics landscape of organ-resolved BD identified proteomics features of BD associated with different organs and protein targets that could be used for the development of therapeutic treatment. Hyaluronic binding protein 2, tenascin, and serpin A3 were validated as potential biomarkers for the clinical assessment of vascular BD and treatment targets.

CONCLUSION

Our results provide valuable insight into the pathogenesis of organ-resolved BD in terms of proteomics characteristics and potential biomarkers for clinical assessment and potential therapies for vascular BD.

Metabolite, protein, and tissue dysfunction associated with COVID-19 disease severity

Proteins are direct products of the genome and metabolites are functional products of interactions between the host and other factors such as environment, disease state, clinical information, etc. Omics data, including proteins and metabolites, are useful in characterizing biological processes underlying COVID-19 along with patient data and clinical information, yet few methods are available to effectively analyze such diverse and unstructured data. Using an integrated approach that combines proteomics and metabolomics data, we investigated the changes in metabolites and proteins in relation to patient characteristics (e.g., age, gender, and health outcome) and clinical information (e.g., metabolic panel and complete blood count test results). We found significant enrichment of biological indicators of lung, liver, and gastrointestinal dysfunction associated with disease severity using publicly available metabolite and protein profiles. Our analyses specifically identified enriched proteins that play a critical role in responses to injury or infection within these anatomical sites, but may contribute to excessive systemic inflammation within the context of COVID-19. Furthermore, we have used this information in conjunction with machine learning algorithms to predict the health status of patients presenting symptoms of COVID-19. This work provides a roadmap for understanding the biochemical pathways and molecular mechanisms that drive disease severity, progression, and treatment of COVID-19.

Factor VII Activating Protease Expression in Human Platelets and Accumulation in Symptomatic Carotid Plaque

Background

Factor VII activating protease (FSAP) is of interest as a marker for vascular inflammation and plaque destabilization. The aim of this study was to analyze the expression profile of FSAP in endarterectomy specimens that were taken from patients with asymptomatic and symptomatic carotid atherosclerotic plaques and to compare them with circulating FSAP levels.

Methods and Results

Plasma FSAP concentration, activity, and mRNA expression were measured in endarterectomy specimens and in monocytes and platelets. Plaque and plasma FSAP levels were higher in symptomatic patients (n=10) than in asymptomatic patients (n=14). Stronger FSAP immunostaining was observed in advanced symptomatic lesions, in intraplaque hemorrhage‐related structures, and in lipid‐rich areas within the necrotic core. FSAP was also colocalized with monocytes and macrophages (CD11b/CD68‐positive cells) and platelets (CD41‐positive cells) of the plaques. Moreover, human platelets expressed FSAP in vitro, at both the mRNA and protein levels. Expression is stimulated by thrombin receptor‐activating peptide and ADP and reduced by acetylsalicylic acid.

Conclusions

Plasma FSAP levels were significantly increased in patients with symptomatic carotid stenosis and thus may be involved in plaque development This plaque‐associated FSAP may be produced by platelets or macrophages or may be taken up from the circulation. To establish FSAP’s utility as a circulating or plaque biomarker in patients with symptomatic carotid atherosclerotic plaques, further studies are needed.

Cellular effects of factor VII activating protease (FSAP)

Factor VII activating protease (FSAP) is a circulating serine protease of broad specificity that is likely to be involved in many pathophysiological processes. The activation of the circulating zymogen form of FSAP by histones, released from damaged cells, underlines its roles in regulating host responses to tissue damage and inflammation. Some of the direct cellular effects of FSAP are mediated through protease-activated receptors (PARs). Knock-down of each one of the four PARs in endothelial cells indicated that PAR-1 and -3 are involved in regulating endothelial permeability in response to FSAP. Overexpression of PARs in cell lines led to the conclusion that PAR-2 and -1 were the main receptors for FSAP. Studies with synthetic peptides and receptor mutants demonstrate that FSAP cleaves PAR-1 and -2 at their canonical cleavage site. However, PAR-1 is not activated by FSAP in all cells, which may be related to other, as yet, undefined factors. Inhibition of apoptosis by FSAP is mediated through PAR-1 and was observed in neurons, astrocytes and A549 cells. FSAP also mediates cellular effects by modulating the activity of growth factors, generation of bradykinin, C5a and C3a generation or histone inactivation. These cellular effects need to be further investigated at the in vivo level.

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.

Genome-wide analysis of genetic determinants of circulating factor VII-activating protease (FSAP) activity

Essentials Knowledge of genetic regulators of plasma factor VII activating protease (FSAP) levels is limited. We performed a genome-wide analysis of variants influencing FSAP activity in Scandinavian cohorts. We replicated an association for Marburg-1 and identified an association for a HABP2 stop variant. We identified a novel locus near ADCY2 as a potential additional regulator of FSAP activity.

SUMMARY

Background Factor VII-activating protease (FSAP) has roles in both coagulation and fibrinolysis. Recent data indicate its involvement in several other processes, such as vascular remodeling and inflammation. Plasma FSAP activity is highly variable among healthy individuals and, apart from the low-frequency missense variant Marburg-I (rs7080536) in the FSAP-encoding gene HABP2, determinants of this variation are unclear. Objectives To identify novel genetic variants within and outside of the HABP2 locus that influence circulating FSAP activity. Patients/Methods We performed an exploratory genome-wide association study (GWAS) on plasma FSAP activity amongst 3230 Swedish subjects. Directly genotyped rare variants were also analyzed with gene-based tests. Using GWAS, we confirmed the strong association between the Marburg-I variant and FSAP activity. HABP2 was also significant in the gene-based analysis, and remained significant after exclusion of Marburg-I carriers. This was attributable to a rare HABP2 stop variant (rs41292628). Carriers of this stop variant showed a similar reduction in FSAP activity as Marburg-I carriers, and this finding was replicated. A secondary genome-wide significant locus was identified at a 5p15 locus (rs35510613), and this finding requires future replication. This common variant is located upstream of ADCY2, which encodes a protein catalyzing the formation of cAMP. Results and Conclusions This study verified the Marburg-I variant to be a strong regulator of FSAP activity, and identified an HABP2 stop variant with a similar impact on FSAP activity. A novel locus near ADCY2 was identified as a potential additional regulator of FSAP activity.

Expression of the Marburg I Single Nucleotide Polymorphism (MI-SNP) and the Marburg II Single Nucleotide Polymorphism (MII-SNP) of the Factor VII-Activating Protease (FSAP) Gene and Risk of Coronary Artery Disease (CAD): A Pilot Study in a Single Population

Background

Factor VII-activating protease (FSAP) has a role in vascular inflammation and may have a role coronary artery disease (CAD). The aim of this study was to investigate the association between two naturally occurring single nucleotide polymorphisms (SNPs) in the FSAP gene and the risk of coronary artery disease (CAD).

Material/Methods

Of 733 patients, 173 patients had symptoms of angina, and 560 patients had CAD confirmed by coronary angiography. All patients were genotyped for SNPs of the FSAP gene, Marburg I (MI-SNP) and Marburg II (MII-SNP), using 5′ exonuclease TaqMan assays. Logistic regression analysis was used to evaluate the association between two gene polymorphisms, metabolic and other cardiovascular risk factors in patients with CAD.

Results

The presence of MI-SNP and MII-SNP FSAP gene polymorphisms were not associated with the presence of CAD. However, the MII-SNP polymorphism was significantly associated with a reduced risk of developing CAD (OR=0.422; 95% CI, 0.194–0.920; P=0.035); the MI-SNP polymorphism was associated with absence of hyperlipoproteinemia (OR=0.601; 95% CI, 0.344–1.051; P=0.074). There was no significant association between expression of the MI-SNP and MII-SNP FSAP gene polymorphisms and the incidence of myocardial infarction, or of a history of diabetes mellitus, arterial hypertension, obesity, or smoking.

Conclusions

The MI-SNP and MII-SNP FSAP gene polymorphisms were not predictive or prognostic biomarkers for CAD or its main risk factors. However, the presence of the MII-SNP polymorphism was associated with a reduced risk of developing CAD.

A Positively Charged Surface Triggers Coagulation Activation Through Factor VII Activating Protease (FSAP)

Contact between biomedical materials and blood often initiates undesirable pro-coagulant and pro-inflammatory processes. On negatively charged materials, blood coagulation is known to be triggered through autoactivation of Factor XII, while activation on cationic surfaces follows a distinct and so far enigmatic mechanism. Because Factor VII activating protease (FSAP) is known to be activated on positively and on negatively charged macromolecules in plasma, we have investigated its interaction with charged biomaterials and its consequences for coagulation. Several activation processes in blood and plasma were characterized after contact with material surfaces with varied charge. FSAP was found to be exclusively activated by the positively charged surfaces polyethylenimine (PEI) and poly-l-lysine (PLL), not by the negatively charged glass or self-assembled monolayer with carboxyl group termination (SAM-COOH), as well as uncharged (Teflon AF) surfaces. Whole blood incubation on PEI showed that this activation was concomitant with coagulation as determined by thrombin and fibrin formation, which was high for glass (F1+2, 138 nM) and PEI (F1+2, 44 nM) but low for Teflon AF (F1+2, 3.3 nM) and SAM COOH (F1+2, 5.8 nM). Contact phase inhibitor diminished coagulation to background levels for all surfaces except PEI (F1+2: ^PEI 43 to 25 nM; glass, 58 to 1.5 nM) indicating that coagulation activation is not dependent on FXII activation on the PEI surface. A decisive role of endogenous FSAP for coagulation however was confirmed with the use of FSAP inhibitory antibodies which showed no influence on Teflon AF, glass and SAM COOH but diminished F1+2 on PEI to less than 50%. We propose that FSAP activation could be a novel mechanism of surface-driven coagulation. An inhibition of this protease might improve hemocompatibility of cationic surfaces and therefore facilitate the application of polycationic surfaces in blood.

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.

Factor VII-activating protease deficiency promotes neointima formation by enhancing leukocyte accumulation

Essentials Factor VII-activating protease (FSAP) is a plasma protease involved in vascular processes. Neointima formation was investigated after vascular injury in FSAP-/- mice. The neointimal lesion size and the accumulation of macrophages were increased in FSAP-/- mice. This was due to an increased activity of the chemokine (C-C motif) ligand 2 (CCL2).

SUMMARY

Background Factor VII-activating protease (FSAP) is a multifunctional circulating plasma serine protease involved in thrombosis and vascular remodeling processes. The Marburg I single-nucleotide polymorphism (MI-SNP) in the FSAP-coding gene is characterized by low proteolytic activity, and is associated with increased rates of stroke and carotid stenosis in humans. Objectives To determine whether neointima formation after vascular injury is increased in FSAP-/- mice. Methods and Results The neointimal lesion size and the proliferation of vascular smooth muscle cells (VSMCs) were significantly enhanced in FSAP-/- mice as compared with C57BL/6 control mice after wire-induced injury of the femoral artery. Accumulation of leukocytes and macrophages was increased within the lesions of FSAP-/- mice at day 3 and day 14. Quantitative zymography demonstrated enhanced activity of gelatinases/matrix metalloproteinase (MMP)-2 and MMP-9 within the neointimal lesions of FSAP-/- mice, and immunohistochemistry showed particular costaining of MMP-9 with accumulating leukocytes. Using intravital microscopy, we observed that FSAP deficiency promoted the intravascular adherence and the subsequent transmigration of leukocytes in vivo in response to chemokine ligand 2 (CCL2). CCL2 expression was increased in FSAP-/- monocytes but not in the vessel wall. There was no difference in the expression of platelet-derived growth factor (PDGF-BB). Conclusions FSAP deficiency causes an increase in CCL2 expression and CCL2-mediated infiltration of leukocytes into the injured vessel, thereby promoting SMC proliferation and migration by the activation of leukocyte-derived gelatinases. These results provide a possible explanation for the observed association of the loss-of-function MI-SNP with vascular proliferative diseases.

Coagulation Factor Xa and Protease-Activated Receptor 2 as Novel Therapeutic Targets for Diabetic Nephropathy

OBJECTIVE

The role of hypercoagulability in the pathogenesis of diabetic nephropathy (DN) remains elusive. We recently reported the increased infiltration of macrophages expressing tissue factor in diabetic kidney glomeruli; tissue factor activates coagulation factor X (FX) to FXa, which in turn stimulates protease-activated receptor 2 (PAR2) and causes inflammation.

APPROACH AND RESULTS

Here, we demonstrated that diabetes mellitus increased renal FX mRNA, urinary FXa activity, and FX expression in glomerular macrophages. Administration of an oral FXa inhibitor, edoxaban, ameliorated DN with concomitant reductions in the expression of PARs (Par1 and Par2) and of proinflammatory and profibrotic genes. Diabetes mellitus induced PAR2, and lack of Par2 ameliorated DN. FXa or PAR2 agonist increased inflammatory cytokines in endothelial cells and podocytes in vitro.

CONCLUSIONS

We conclude that enhanced FXa and PAR2 exacerbate DN and that both are promising targets for preventing DN. Alleviating inflammation is probably more important than inhibiting coagulation per se when treating kidney diseases using anticoagulants.

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.