Fibrinogen, fibrin, and FDP induce C-reactive protein generation in rat vascular smooth muscle cells: pro-inflammatory effect on atherosclerosis

Surface-modified nanotherapeutics targeting atherosclerosis

Atherosclerosis is a chronic and metabolic-related disease that is a serious threat to human health. Currently available diagnostic and therapeutic measures for atherosclerosis lack adequate efficiency which requires promising alternative approaches. Nanotechnology-based nano-delivery systems allow for new perspectives for atherosclerosis therapy. Surface-modified nanoparticles could achieve highly effective therapeutic effects by binding to specific receptors that are abnormally overexpressed in atherosclerosis, with less adverse effects on non-target tissues. The main purpose of this review is to summarize the research progress and design ideas to target atherosclerosis using a variety of ligand-modified nanoparticle systems, discuss the shortcomings of current vector design, and look at future development directions. We hope that this review will provide novel research strategies for the design and development of nanotherapeutics targeting atherosclerosis.

Preoperative Fibrinogen and Hematological Indexes in the Differential Diagnosis of Idiopathic Granulomatous Mastitis and Breast Cancer

Background and Aim: Studies on hematological parameters in the differential diagnosis of idiopathic granulomatous mastitis (IGM) and breast cancer (BC) are limited. This study investigated whether preoperative fibrinogen and hematological indexes can be used in the differential diagnosis of patients with IGM and early-onset BC. Methods: Fifty patients with BC, 55 patients with IGM, and 50 healthy volunteer women were included in the study. Results: There was a statistically significant difference between the IGM and the BC with respect to fibrinogen, fibrinogen/albumin (Fib/Alb) ratio, C-reactive protein (CRP), white blood cells (WBC), neutrophils, neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR), and monocyte values. When fibrinogen (p < 0.001), the Fib/Alb ratio (p < 0.001), CRP (p < 0.001), WBC (p < 0.001), neutrophil (p < 0.001), NLR (p < 0.001), monocyte (p = 0.008), and 2-hour sedimentation rate (p < 0.001) were compared between the groups, the highest levels were found in the IGM group. There was a negative relationship between CRP and albumin, and a positive relationship was observed between CRP and WBC, NLR, PLR, and 2-h sedimentation rate. CRP had the highest sensitivity (95%), whereas the Fib/Alb ratio (86%) had the highest specificity. Patients with recurrent IGM had increased fibrinogen, Fib/Alb, CRP, neutrophils, NLR, and 2-h erythrocyte sedimentation rate (ESR) and decreased lymphocyte levels compared to non-recurrent patients. Conclusions: Preoperative CRP, albumin, fibrinogen, Fib/Alb, WBC, neutrophil, NLR, monocyte, and 2-h ESR have considerable potential to be early and sensitive biomarkers of IGM caused by inflammation compared to BC. These parameters also have a significant effect on the recurrence of the disease, suggesting their potential as a practical guide for the differential diagnosis of BC from IGM.

Predicting value of fibrinogen in identifying cerebrovascular ischemic events in patients with dizziness/vertigo

PURPOSE

Dizziness and vertigo are caused by multiple etiologies, including cerebrovascular ischemic events. However, identifying cerebrovascular ischemic events as a cause of dizziness and vertigo remains a challenge. We tried to assess the value of fibrinogen (FIB) in identifying of cerebral ischemic event in patients with dizziness/vertigo.

METHODS

The study enrolled patients with dizziness/vertigo presented within 72 h in a tertiary hospital. The plasma FIB levels were measured in all participants. According to the final diagnosis, participants were divided into cerebral ischemic events group and non-cerebrovascular diseases group. Multivariate logistic regression was performed to explore the association between FIB and cerebral ischemic events. The receiver operating characteristic curve was performed, and the nomogram was constructed to evaluate the overall prediction ability of FIB in cerebral ischemic event.

RESULTS

A total of 298 participants were enrolled in our study, of 126 cerebral ischemic events patients. Multivariate logistic regression analysis showed that FIB was independently associated with cerebral ischemic event in patients with dizziness (OR = 1.84, 95%CI [1.15, 2.92], p = 0.010). The cut-off value of FIB in predicting cerebral ischemic event was 2.43 g/L (AUC = 0.658). The nomogram showed that higher FIB level was associated with a greater risk of cerebral ischemic event (C-index = 0.800).

CONCLUSIONS

Our study suggested that FIB may be a useful biochemical parameter for identifying cerebral ischemic event in patients with dizziness/vertigo.

Protective effect of vitamin E against diabetes-induced oxidized LDL and aorta cell wall proliferation in rat

Hyperlipidemia and oxidized-low-density lipoproteins (Ox-LDL) are important independent cardiovascular risk factors that have been shown to stimulate vascular smooth muscle cell (VSMC) proliferation. The purpose of the present study was to investigate the effect of vitamin E on Ox-LDL, lipid profile, C-reactive protein (CRP), and VSMC proliferation of rat aorta.

METHODS

Male Wistar rats (n = 32) were divided into four groups namely: sham (SH), control (C), non-treated diabetic, and vitamin E-treated diabetic (VETD) groups. Ox-LDL, lipid profile, CRP and VSMC proliferation of aorta were measured after 42 days.

RESULTS

The results revealed that along with a significant increase in VSMC proliferation, the amount of CRP, Ox-LDL, and lipid profiles in diabetic rats. VSMC proliferation was significantly ameliorated, and elevated CRP, Ox-LDL, and lipid profiles were also restored to those of shams in VETD.

CONCLUSIONS

These findings strongly support the idea that diabetes induces Ox-LDL-mediated oxidative stress and VSMC proliferation in aorta of rat and imply that vitamin E has a strong protective effect as an antioxidant.

Cardiovascular response to thermoregulatory challenges

A growing number of extreme climate events are occurring in the setting of ongoing climate change, with an increase in both the intensity and frequency. It has been shown that ambient temperature challenges have a direct and highly varied impact on cardiovascular health. With a rapidly growing amount of literature on this issue, we aim to review the recent publications regarding the impact of cold and heat on human populations with regard to cardiovascular disease (CVD) mortality/morbidity while also examining lag effects, vulnerable subgroups, and relevant mechanisms. Although the relative risk of morbidity/mortality associated with extreme temperature varied greatly across different studies, both cold and hot temperatures were associated with a positive mean excess of cardiovascular deaths or hospital admissions. Cause-specific study of CVD morbidity/mortality indicated that the sensitivity to temperature was disease-specific, with different patterns for acute and chronic ischemic heart disease. Vulnerability to temperature-related mortality was associated with some characteristics of the populations, including sex, age, location, socioeconomic condition, and comorbidities such as cardiac diseases, kidney diseases, diabetes, and hypertension. Temperature-induced damage is thought to be related to enhanced sympathetic reactivity followed by activation of the sympathetic nervous system, renin-angiotensin system, as well as dehydration and a systemic inflammatory response. Future research should focus on multidisciplinary adaptation strategies that incorporate epidemiology, climatology, indoor/building environments, energy usage, labor legislative perfection, and human thermal comfort models. Studies on the underlying mechanism by which temperature challenge induces pathophysiological response and CVD await profound and lasting investigation.

A regenerative label-free fiber optic sensor using surface plasmon resonance for clinical diagnosis of fibrinogen

Purpose

We present the regenerative label-free fiber optical biosensor that exploits surface plasmon resonance for quantitative detection of fibrinogen (Fbg) extracted from human blood plasma.

Materials and methods

The sensor head was made up of a multimode optical fiber with its polymer cladding replaced by metal composite of nanometer thickness made of silver, aluminum, and nickel. The Ni layer coated allowed a direct immobilization of histidine-tagged peptide (HP) on its metal surface without an additional cross-linker in between. On the coated HP layer, immunoglobulin G was then immobilized for specific capturing of Fbg.

Results

We demonstrated a real-time quantitative detection of Fbg concentrations with limit of detection of ~10 ng/mL. The fact that the HP layer could be removed by imidazole with acid also permitted us to demonstrate the regeneration of the outermost metal surface of the sensor head for the sensor reusability.

Conclusion

The sensor detection limit was estimated to be ~10 pM, which was believed to be sensitive enough for detecting Fbg during the clinical diagnosis of cardiovascular diseases, myocardial infarction, strokes, and Alzheimer’s diseases.

Pravastatin inhibits fibrinogen- and FDP-induced inflammatory response via reducing the production of IL-6, TNF-α and iNOS in vascular smooth muscle cells

Atherosclerosis is a chronic inflammatory response of the arterial wall to pro‑atherosclerotic factors. As an inflammatory marker, fibrinogen directly participates in the pathogenesis of atherosclerosis. Our previous study demonstrated that fibrinogen and fibrin degradation products (FDP) produce a pro‑inflammatory effect on vascular smooth muscle cells (VSMCs) through inducing the production of interleukin‑6 (IL‑6), tumor necrosis factor‑α (TNF‑α) and inducible nitric oxide synthase (iNOS). In the present study, the effects of pravastatin on fibrinogen‑ and FDP‑induced expression of IL‑6, TNF‑α and iNOS were observed in VSMCs. The results showed that pravastatin dose‑dependently inhibited fibrinogen‑ and FDP‑stimulated expression of IL‑6, TNF‑α and iNOS in VSMCs at the mRNA and protein level. The maximal inhibition of protein expression of IL‑6, TNF‑α and iNOS was 46.9, 42.7 and 49.2% in fibrinogen‑stimulated VSMCs, and 50.2, 49.8 and 53.6% in FDP‑stimulated VSMCs, respectively. This suggests that pravastatin has the ability to relieve vascular inflammation via inhibiting the generation of IL‑6, TNF‑α and iNOS. The results of the present study may aid in further explaining the beneficial effects of pravastatin on atherosclerosis and related cardiovascular diseases. In addition, they suggest that application of pravastatin may be beneficial for prevention of atherosclerosis formation in hyperfibrinogenemia.

mRNA expression of genes involved in inflammation and haemostasis in equine fibroblast-like synoviocytes following exposure to lipopolysaccharide, fibrinogen and thrombin

Background

Studies in humans have shown that haemostatic and inflammatory pathways both play important roles in the pathogenesis of joint disease. The aim of this study was to assess mRNA expression of haemostatic and inflammatory factors in cultured equine fibroblast-like synoviocytes exposed to lipopolysaccharide (LPS), fibrinogen and thrombin. Synovial membranes were collected from metacarpo-phalangeal joints of 6 skeletally mature horses euthanized for non-orthopaedic reasons. Passage 4 fibroblast-like synoviocytes were left non-treated or treated with either 0.1 μg/ml LPS, 5 mg/ml fibrinogen or 5 U/ml thrombin and harvested at time points 0, 6, 24 and 48 h. mRNA expression of serum amyloid A (SAA), interleukin-6 (IL-6), monocyte chemotactic protein 1 (MCP-1), tissue factor (TF), plasminogen activator inhibitor 1 (PAI-1), urokinase plasminogen activator (uPA), vascular endothelial growth factor (VEGF) and protease activator receptor 1 (PAR-1) was assessed using quantitative real time reverse transcriptase PCR.

Results

LPS caused a significant increase in mRNA expression of SAA, IL-6, MCP-1 and uPA, and a decrease in TF, PAI-1 and PAR-1 when compared to non-treated cells. Treatment with thrombin resulted in increased mRNA expression of SAA, IL-6, MCP-1 and PAI-1, and a decreased PAR-1 expression compared to non-treated cells. The fibrinogen-treated synoviocytes showed significantly increased mRNA expression of IL-6, MCP-1, TF and PAI-1, and decreased PAR-1 expression compared to non-treated cells.

Conclusion

LPS, fibrinogen and thrombin induced an increased gene expression of inflammatory markers in isolated equine fibroblast-like synoviocytes. LPS caused changes in gene expression promoting increased fibrinolysis, while fibrinogen and thrombin changed the gene expression resulting potentially in reduced fibrinolysis. Overall, it appeared that both inflammatory and haemostatic stimuli affected expression of genes involved in inflammatory and haemostatic pathways, supporting their importance in equine joint diseases.

Pro-inflammatory effect of fibrinogen on vascular smooth muscle cells by regulating the expression of PPARα, PPARγ and MMP-9

Atherosclerosis is a chronic inflammatory disease in the vessel. As one of the inflammatory markers, fibrinogen has been indicated in formation and progression of atherosclerosis. However, it is completely unclear whether fibrinogen produces a pro-inflammatory effect on vascular smooth muscle cells (VSMCs). The purpose of the present study was to observe the effect of fibrinogen on the expression of peroxisome proliferator-activated receptors-α (PPARα), PPARγ and matrix metalloproteinase-9 (MMP-9) in VSMCs. Rat VSMCs were cultured and fibrinogen was used as a stimulant for PPARα, PPARγ and MMP-9 expression. mRNA expression of PPARα, PPARγ and MMP-9 was identified with the reverse transcription polymerase chain reaction. Protein production of PPARα and PPARγ was examined by western blot analysis and the MMP-9 level in the supernatant of VSMCs was measured with the enzyme-linked immunosorbent assay. The results showed that fibrinogen downregulated mRNA and protein expression of PPARα and PPARγ, and upregulated mRNA and protein generation of MMP-9 in VSMCs in time- and concentration-dependent manners. The maximal inhibition of protein expression of PPARα and PPARγ was 71.8 and 79.9%, respectively. The maximal release of MMP-9 was 4 times over the control. The results suggest that fibrinogen exerts a pro-inflammatory effect on VSMCs through inhibiting the expression of anti-inflammatory cytokine PPARα and PPARγ and stimulating the production of pro-inflammatory cytokine MMP-9. The findings provide new evidence for the pro-inflammatory and pro-atherosclerotic effects of fibrinogen.

Effects of different cold-air exposure intensities on the risk of cardiovascular disease in healthy and hypertensive rats

Ten-week-old male Wistar rats (systolic blood pressure, 106-116 mmHg; body weight, 300-320 g) and spontaneously hypertensive rats (systolic blood pressure, 160-176 mmHg; body weight, 210.9-244.9 g) were used as healthy and hypertensive subjects to determine the effects of varying degrees of cold-air exposure in a climate chamber box. The three cold-air ranks were cold air I [minimum temperature (TMIN) 6.4 °C, ↓∆T48 8.6 °C], cold air II (TMIN 3.8 °C, ↓∆T48 11.2 °C), and cold air III (TMIN -0.3 °C, ↓∆T48 15.3 °C), as established from the cold-air data of Zhangye City, China. Each cold-air rank consisted of a temperature drop and a temperature increase with the same initial and terminal temperatures (15 °C). After cold-air exposure, the risk factors for cardiovascular disease (CVD) such as systolic blood pressure, whole blood viscosity (10/s and 150/s), plasma fibrinogen, and blood lipids of the rats were determined. The results indicated that the CVD risk factors of the healthy and hypertensive rats increased significantly with cold-air exposure intensities. The increase in systolic blood pressure was greater during temperature drops, whereas the increases in whole blood viscosity and plasma fibrinogen were greater after cold-air exposure. The effects of cold-air exposure on the CVD risk factors of healthy rats, particularly the systolic blood pressure, whole blood viscosity (150/s), and LDL/HDL, were greater than those in hypertensive rats. In conclusion, CVD risk may increase with cold-air ranks. Blood pressure-induced CVD risk may be greater during cold-air temperature drop, whereas atherosclerosis-induced CVD risk may be greater after cold-air exposure. The effect of cold air on the CVD risk factors in healthy subjects may be more significant than those in hypertensive subjects.

Mitochondrial morphofunctional alterations in smooth muscle cells of aorta in rats

In an experimental model of atherogenesis induced by hyperfibrinogenemia (HF), the pharmacological response of vitamin E was studied in order to assess its antioxidant effect on the mitochondrial morphofunctional alterations in aortic smooth muscle cells. Three groups of male rats were used: (Ctr) control, (AI) atherogenesis induced for 120 days, and (AIE) atherogenesis induced for 120 days and treated with vitamin E. HF was induced by adrenalin injection (0.1 mg/day/rat) for 120 days. AIE group was treated with the administration of 3.42 mg/day/rat of vitamin E for 105 days after the first induction. Mitochondria morphology was analyzed by electronic microscopy (EM) and mitochondrial complexes (MC) by spectrophotometry. In group AI the total and mean number of mitochondria reduced significantly, the intermembranous matrix increased, and swelling was observed with respect to Ctr and AIE (P < 0.01). These damages were related to a significant decrease in the activity of citrate synthase and complexes I, II, III, and IV in group AI in comparison to Ctr (P < 0.001). Similar behavior was presented by group AI compared to AIE (P < 0.001). These results show that vitamin E produces a significative regression of inflammatory and oxidative stress process and it resolved the morphofunctional mitochondrial alterations in this experimental model of atherogenic disease.

The role of fibrinogen, fibrin and fibrin(ogen) degradation products (FDPs) in tumor progression

Participation of fibrin, fibrinogen, and their degradation products in pathogenesis and progression of cancer may lead to complications of thromboembolic events. The tumor may be a source of fibrinogen. Fibrinogen inside the tumor is one of the factors of its growth and metastasis. Fibrinogen, fibrin and their degradation products possess proinflammatory activity. They indirectly stimulate endothelium to secrete von Willebrand factor, leading to activation of platelets accompanying neoplastic disorders. Fragments E and D are the end products of fibrin(ogen) degradation and E and DD are the end products of stabilized fibrin. E stimulates proliferation, migration and differentiation of endothelial cells, contributing to tumor vasculature. Increased levels of DD are observed in malignant neoplasms, such as breast, lung, colon and ovary cancers. In breast cancers DD correlates with progression of disease and metastasis. The role of fibrinogen and the products of its degradation in the progression of various tumors is not sufficiently understood.

Impaired fibrinolysis is associated with the severity of aortic stenosis in humans

BACKGROUND

A role of fibrinolysis in the pathogenesis of aortic valve stenosis (AS) is unknown, although fibrinolytic proteins have been detected in aortic stenotic valves.

OBJECTIVE

To investigate whether impaired fibrinolysis could be associated with AS.

METHODS AND RESULTS

We studied 74 patients with AS (43 male, 31 female, aged 62.7 ± 10.7 years) without documented atherosclerotic valvular disease scheduled for isolated valve replacement and 68 controls. The plasma fibrin clot lysis time (CLT) in the presence of tissue factor (TF) and tissue plasminogen activator (tPA), along with plasma plasminogen activator inhibitor-1 (PAI-1) were determined. Valvular expression of fibrin and PAI-1 together with macrophages and mast cells (MC) was evaluated by immunostaining. Patients with AS compared with controls were characterized by a prolonged CLT (median, 110 [54-153] vs. 92.5 [58-115] min, P = 0.0007) and increased plasma PAI-1 (78.6 [35.5-149] vs. 38.5 [18-61] ng mL(-1) , P < 0.0001). CLT was correlated with maximal (r = 0.43, P = 0.0002) and mean (r = 0.38, P = 0.001) transvalvular pressure gradients, and aortic valve area (r = -0.59, P < 0.0001). In AS patients, the CLT was positively correlated with the valve leaflet thickness (r = 0.67, P = 0.003), the degree of valve calcification (r = 0.65, P < 0.00001), valvular fibrin (r = 0.54, P = 0.007) and PAI-1 expression (r = 0.48, P = 0.007). Double-immunostaining revealed colocalization of valvular PAI-1 with MC (87 ± 17% cells) and macrophages (48 ± 11% cells) within stenotic valves.

CONCLUSIONS

Hypofibrinolysis might be a marker of severe AS and be implicated in AS progression.

Arterial ageing

Arterial ageing is characterized by age associated degeneration and sclerosis of the media layer of the large arteries. However, besides ageing, clinical conditions, which enhance oxidative stress and inflammation act to accelerate the degree of arterial ageing. In this review, we summarized the pathophysiology and contributing factors that accelerate arterial ageing. Among them, we focused on hypertension, the renin-angiotensin-aldosterone system and vascular inflammation which are modifiable causes of the arterial ageing process. Also, novel treatment targets derived from the disease models such as the Hutchinson Gilford Progeria Syndrome were reviewed.

Artificial cold air increases the cardiovascular risks in spontaneously hypertensive rats

The purpose was to investigate the effects of artificial cold air on cardiovascular risk in hypertensive subjects. An artificial cold air was simulated with hourly ambient temperature data of a real moderate cold air in China. Twenty-four male SHR rats were randomly divided into the minimum temperature (Tmin) group, the rewarming temperature (Tr) group and two concurrent control groups with six rats in each (Tmin and Tr represent two cold air time points, respectively). Tmin and Tr groups were exposed to the cold air that was stopped at Tmin and Tr, respectively. After cold air exposure, blood pressure, heart rate and body weight were monitored, blood was collected for the detection of some indexes like fibrinogen, total cholesterol and uric acid. Results demonstrated that blood pressure, whole blood viscosity, blood fibrinogen, total cholesterol and uric acid increased significantly both in the Tmin and Tr groups; low density lipoprotein/high density lipoprotein increased significantly only in Tr group; there was higher level of blood fibrinogen in the Tr group than the Tmin group; higher levels of creatine kinase-MB was found in both the Tmin and Tr groups. These results suggest that cold air may increase the cardiovascular risks in hypertensive subjects indirectly through its effects on the sympathetic nervous system and renin angiotensin system, blood pressure and atherosclerosis risk factors like blood viscosity and fibrinogen, lipids and uric acid in the blood.

Effects of cold air on cardiovascular disease risk factors in rat

The purpose of this study is to explore possible potential implications of cold air in cardiovascular disease (CVD) risk in rats. Healthy Wistar rats were exposed to artificial cold air under laboratory conditions, and their systolic blood pressure, heart rate, vasoconstriction, CVD risk factors, and myocardial damage indicators after cold air exposure were determined and evaluated. Systolic blood pressure, whole blood viscosity, and plasma level of norepinephrine, angiotensinⅡ, low density lipoprotein, total cholesterol, and fibrinogen in treatment groups increased significantly compared with control groups. No significant variations were found in plasma Mb and cTnT and myocardial tissue between the treatment and control groups. Results indicate that: (1) higher levels of SBP, WBV and LDL/HDL, total cholesterol (TC), and FG in blood may indicate higher CVD risks during cold air exposure; (2) cold air may exert continuous impacts on SBP and other CVD risk factors.

Pravastatin inhibits C-reactive protein generation induced by fibrinogen, fibrin and FDP in isolated rat vascular smooth muscle cells

OBJECTIVE

The available evidence indicates that C-reactive protein (CRP) participates directly in atherosclerosis formation as an inflammatory molecule. Our previous investigation suggested that fibrinogen, fibrin and fibrinogen degradation products (FDP) produce a pro-inflammatory effect on vascular smooth muscle cells (VSMCs) through inducing CRP generation. In the present study, we observed the effect of pravastatin on CRP generation induced by fibrinogen, fibrin and FDP in rat VSMCs.

METHODS

VSMCs from Sprague-Dawley rats were cultured. Fibrinogen, fibrin and FDP were used as stimulants for CRP generation. VSMCs were preincubated with pravastatin at 10, 30, 100 μM for 30 min prior to stimulation. CRP mRNA expression was studied by reverse transcription polymerase chain reaction (RT-PCR). CRP levels in the supernatant of VSMCs were measured by enzyme-linked immunosorbent assay (ELISA). CRP expression in VSMCs was examined with immunocytochemical staining.

RESULTS

ELISA analysis showed that the pravastatin concentration-dependently reduced fibrinogen-, fibrin- and FDP-stimulated generation of CRP in VSMCs, with maximal inhibition of 56.6, 55.7 and 62.3%, respectively. Immunocytochemical staining and RT-PCR revealed that pravastatin inhibited protein and mRNA expression of CRP in VSMCs significantly.

CONCLUSIONS

Pravastatin at the concentrations used in the present experiment has ability to relieve vascular inflammation and to restrain atherosclerotic processes via inhibiting the CRP production induced by fibrinogen, fibrin and FDP in VSMCs, which helps explain the beneficial effects of pravastatin on atherosclerosis.

Histidine-rich glycoprotein binds fibrin(ogen) with high affinity and competes with thrombin for binding to the gamma'-chain

Histidine-rich glycoprotein (HRG) is an abundant protein that binds fibrinogen and other plasma proteins in a Zn(2+)-dependent fashion but whose function is unclear. HRG has antimicrobial activity, and its incorporation into fibrin clots facilitates bacterial entrapment and killing and promotes inflammation. Although these findings suggest that HRG contributes to innate immunity and inflammation, little is known about the HRG-fibrin(ogen) interaction. By immunoassay, HRG-fibrinogen complexes were detected in Zn(2+)-supplemented human plasma, a finding consistent with a high affinity interaction. Surface plasmon resonance determinations support this concept and show that in the presence of Zn(2+), HRG binds the predominant γ(A)/γ(A)-fibrinogen and the γ-chain elongated isoform, γ(A)/γ'-fibrinogen, with K(d) values of 9 nm. Likewise, (125)I-labeled HRG binds γ(A)/γ(A)- or γ(A)/γ'-fibrin clots with similar K(d) values when Zn(2+) is present. There are multiple HRG binding sites on fibrin(ogen) because HRG binds immobilized fibrinogen fragment D or E and γ'-peptide, an analog of the COOH terminus of the γ'-chain that mediates the high affinity interaction of thrombin with γ(A)/γ'-fibrin. Thrombin competes with HRG for γ'-peptide binding and displaces (125)I-HRG from γ(A)/γ'-fibrin clots and vice versa. Taken together, these data suggest that (a) HRG circulates in complex with fibrinogen and that the complex persists upon fibrin formation, and (b) by competing with thrombin for γ(A)/γ'-fibrin binding, HRG may modulate coagulation. Therefore, the HRG-fibrin interaction may provide a novel link between coagulation, innate immunity, and inflammation.

Pro-inflammatory effect of fibrinogen and FDP on vascular smooth muscle cells by IL-6, TNF-α and iNOS

AIMS

Atherosclerosis is a chronic inflammatory response of the arterial wall to multiple endothelial injuries. As one of the inflammatory markers, fibrinogen has been implicated in pathogenesis of atherosclerosis. But, it is not completely understood whether atherogenesis of fibrinogen is related to its pro-inflammatory effect on vascular smooth muscle cells (VSMCs). The purpose of the present study was to observe effects of fibrinogen and fibrin degradation products (FDP) on interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and inducible nitric oxide synthase (iNOS) generation in rat VSMCs.

MAIN METHODS

Rat VSMCs were cultured, and fibrinogen and FDP were used as stimulants for IL-6, TNF-α, and iNOS. IL-6 and TNF-α level in the supernatant were measured by ELISA, mRNA expression of IL-6, TNF-α, and iNOS were assayed with RT-PCR, and protein expression of iNOS was detected with western blot and immunocytochemistry.

KEY FINDINGS

Fibrinogen and FDP both significantly stimulated mRNA and protein expressions of IL-6, TNF-α and iNOS in VSMCs in time- and concentration-dependent ways. The pro-inflammatory potency of FDP is higher than fibrinogen, which seems to mean that smaller fragments of the protein have greater pro-inflammatory activity. Fibrinogen and FDP promote more protein expressions of IL-6 and TNF-α compared to iNOS, suggesting that fibrinogen and FDP produce a pro-inflammatory effect on VSMCs mainly by IL-6 and TNF-α.

SIGNIFICANCE

These findings are helpful to better understand pro-inflammatory effect of fibrinogen on VSMCs involved in atherogenesis, and imply a therapeutic strategy targeting hyperfibrinogenemia in atherosclerosis.