Elevated serum amyloid A is associated with venous thromboembolism

Aqueous humor perturbations in chronic smokers: a proteomic study

The detrimental effects of smoking are multisystemic and its effects on the eye health are significant. Smoking is a strong risk factor for age-related nuclear cataract, age-related macular degeneration, glaucoma, delayed corneal epithelial healing and increased risk of cystoid macular edema in patients with intermediate uveitis among others. We aimed to characterize the aqueous humor (AH) proteome in chronic smokers to gain insight into its perturbations and to identify potential biomarkers for smoking-associated ocular pathologies. Compared to the control group, chronic smokers displayed 67 (37 upregulated, 30 downregulated) differentially expressed proteins (DEPs). Analysis of DEPs from the biological point of view revealed that they were proteins involved in complement activation, lymphocyte mediated immunity, innate immune response, cellular oxidant detoxification, bicarbonate transport and platelet degranulation. From the molecular function point of view, DEPs were involved in oxygen binding, oxygen carrier activity, hemoglobin binding, peptidase/endopeptidase/cysteine-type endopeptidase inhibitory activity. Several of the upregulated proteins were acute phase reactant proteins such as clusterin, alpha-2-HS-glycoprotein, fibrinogen, alpha-1-antitrypsin, C4b-binding protein and serum amyloid A-2. Further research should confirm if these proteins might serve as biomarkers or therapeutic target for smoking-associated ocular diseases.

Recent Advances on the Molecular Mechanism and Clinical Trials of Venous Thromboembolism

Venous thromboembolism is a condition that includes deep vein thrombosis and pulmonary embolism. It is the third most common cardiovascular disease behind acute coronary heart disease and stroke. Over the past few years, growing research suggests that venous thrombosis is also related to the immune system and inflammatory factors have been confirmed to be involved in venous thrombosis. The role of inflammation and inflammation-related biomarkers in cerebrovascular thrombotic disease is the subject of ongoing debate. P-selectin leads to platelet-monocyte aggregation and stimulates vascular inflammation and thrombosis. The dysregulation of miRNAs has also been reported in venous thrombosis, suggesting the involvement of miRNAs in the progression of venous thrombosis. Plasminogen activator inhibitor-1 (PAI-1) is a crucial component of the plasminogen-plasmin system, and elevated levels of PAI-1 in conjunction with advanced age are significant risk factors for thrombosis. In addition, it has been showed that one of the ways that neutrophils promote venous thrombosis is the formation of neutrophil extracellular traps (NETs). In recent years, the role of extracellular vesicles (EVs) in the occurrence and development of VTE has been continuously revealed. With the advancement of research technology, the complex regulatory role of EVs on the coagulation process has been gradually discovered. However, our understanding of the causes and consequences of these changes in venous thrombosis is still limited. Therefore, we review our current understanding the molecular mechanisms of venous thrombosis and the related clinical trials, which is crucial for the future treatment of venous thrombosis.

Study on the Mechanism of NLRP3/IL-1/ NF-κB Signaling Pathway and Macrophage Polarization in the Occurrence and Development of VTE

BACKGROUND

The role of inflammation in venous thromboembolism (VTE) has been the focus of recent research. The NLRP3/IL-1/NF-κB signaling pathway and cytokines such as IL-1, regulated by macrophage polarization, may be the key indicators of a prethrombotic state; however, the mechanisms by which they affect the occurrence of VTE remain unclear.

METHODS

We used neurobiological clamps to stimulate the vein wall to induce vascular endothelial damage to generate a rat model of VTE, applied enzyme-linked immunosorbent assay and real time-polymerase chain reaction technology to identify key proteins (IL1β, Caspase-1, NLRP3, and NF-κB P65), gene mRNA levels and protein expression levels of the NLRP3/IL-1/NF-κB signaling pathway in each group of Sprague Dawley rats, and observed the polarization state of M1 (CD86) and M2 (CD206) macrophages using immunohistochemistry.

RESULTS

A dark red, small thrombus developed in the inferior vena cava immediately after modeling in the model and inhibitor groups. The plasma levels of IL-1 and TNF-α, mRNA expression of key proteins (IL1β, Caspase-1, NLRP3, and NF-κB P65), and expression of key proteins (IL1β, Caspase-1, NLRP3, and NF-κB P65) in VTE model rats were significantly higher than inhibitor, sham operation, and normal control groups (P < 0.05). Six hours after VTE modeling, M₁ type macrophages were more significantly increased than M₂ type macrophages in thrombus tissue (P < 0.05).

CONCLUSIONS

Our analyses demonstrated that the nod-like receptor protein3/Interleukin-1/nuclear factor-κB signaling pathway and macrophage polarization are important in the occurrence and development of VTE and that their target regulation may become a new strategy for VTE prevention and treatment.

Association between Serum Amyloid A Level and White Matter Hyperintensity Burden: a Cross-Sectional Analysis in Patients with Acute Ischemic Stroke

INTRODUCTION

This work aimed to determine the potential link between white matter hyperintensity (WMH) burden and serum amyloid A (SAA) level in patients with acute ischemic stroke.

METHODS

Consecutive patients with acute large artery atherosclerosis (LAA) stroke between April 2021 and May 2022 were included. WMH volumes (periventricular, deep, and total) were measured using the Fazekas score and a semiautomated volumetric analysis on fluid-attenuated inversion recovery-magnetic resonance imaging. The burdens of WMH were scored to assess the dose-dependent association between SAA and WMH volume. Multivariate regression and a two-piecewise linear regression model were used to evaluate whether SAA levels are an independent predictor of WMH, and to discover the threshold effect or saturation effect of SAA levels with respect to WMH volume.

RESULTS

The mean age of patients was 63.2 ± 11.5 years, with 65.9% men. The median SAA level was 3.93 mg/L and the total WMH volume of 6.86 cm³. In the multivariable analysis, SAA remained an independent predictor of total WMH volume [β = 0.82, 95% confidence interval (CI) = 0.49-1.07, p < 0.001], periventricular WMH volume (adjusted β = 0.76, 95% CI = 0.46-1.07, p < 0.001), and deep WMH volume (adjusted β = 0.26, 95% CI = 0.06-0.45, p = 0.011) after controlling for confounders. Furthermore, SAA levels were associated with periventricular Fazekas score, deep Fazekas score, and Fazekas grades. Threshold effect and saturation effect analyses demonstrated a nonlinear relationship between SAA levels and periventricular white matter hyperintensity (PVWMH) volumes, with SAA levels (2.12-19.89 mg/L) having significant dose-dependent relationships with periventricular WMH volumes (adjusted β = 1.98, 95% CI = 1.12-2.84, p < 0.001).

CONCLUSION

SAA level ranging from 2.12 to 19.89 mg/L is dose-dependently associated with periventricular WMH development. These findings point the way forward for future research into the pathophysiology of WMH.

Stem cells part of the innate and adaptive immune systems as a therapeutic for Covid-19

Some stem cell types not only release molecules that reduce viral replication, but also reduce the hypercytokinemia and inflammation induced by the immune system, and have been found to be part of the innate and adaptive immune systems. An important component of the stem cell's ability to ameliorate viral diseases, especially the complications post-clearance of the pathogen, is the ability of adult stem cells to reset the innate and adaptive immune systems from an inflammatory state to a repair state. Thus, the molecules released from certain stem cell types found to be safe and efficacious, may be an important new means for therapeutic development in Covid-19, especially for late-stage inflammation and tissue damage once the virus has cleared, particularly in the aged population.

Plasma fibrinolysis, inflammatory markers, and postthrombotic syndrome: preliminary findings from the Kids-DOTT Biobank

Plasma levels of markers of coagulation and inflammation have been identified as prognostic factors for adult postthrombotic syndrome (PTS). We aimed to determine whether plasma fibrinolytic capacity and cytokine levels during the first 3 months after provoked deep venous thrombosis (DVT) are associated with risk of PTS in young patients. We analyzed plasma biospecimens (6 weeks and 3 months after provoked DVT) and clinical data from a National Heart, Lung, and Blood Institute-sponsored multinational trial of anticoagulation for provoked venous thromboembolism in patients younger than age 21 years (Kids-DOTT). Patients with a provoked extremity DVT who had plasma samples available at both 6-week and 3-month post-DVT time points and PTS assessment at 1 year were included. We measured plasma fibrinolytic capacity using the Clot Formation and Lysis (CloFAL) assay and plasma cytokine levels by multiplex immunoassay. Logistic regression analyses evaluated prognostic associations with PTS. Seventy-nine patients were included (median age, 12.8 years; range, 0.04-20.8 years). PTS developed in 34%. Complete veno-occlusion at 6 weeks after diagnosis of DVT (odds ratio [OR], 3.12; 95% confidence interval [CI], 0.81-11.94; P = .097), low fibrinolytic capacity in plasma at 3 months post-DVT (OR, 2.71; 95% CI, 0.92-7.97; P = .07), and elevated serum amyloid A at 3 months post-DVT (OR, 2.85; 95% CI, 0.98-8.34; P = .055) were identified as putative prognostic factors for development of PTS. In multivariable logistic regression analysis, these factors did not retain a statistically significant independent association with PTS, but these preliminary results warrant further investigation in an independent data set to definitively evaluate these findings and identify additional potential prognostic factors for the development of PTS after a provoked DVT in young patients.

High-Density Lipoproteins and Serum Amyloid A (SAA)

PURPOSE OF REVIEW

Serum amyloid A (SAA) is a highly sensitive acute phase reactant that has been linked to a number of chronic inflammatory diseases. During a systemic inflammatory response, liver-derived SAA is primarily found on high-density lipoprotein (HDL). The purpose of this review is to discuss recent literature addressing the pathophysiological functions of SAA and the significance of its association with HDL.

RECENT FINDINGS

Studies in gene-targeted mice establish that SAA contributes to atherosclerosis and some metastatic cancers. Accumulating evidence indicates that the lipidation state of SAA profoundly affects its bioactivities, with lipid-poor, but not HDL-associated, SAA capable of inducing inflammatory responses in vitro and in vivo. Factors that modulate the equilibrium between lipid-free and HDL-associated SAA have been identified. HDL may serve to limit SAA's bioactivities in vivo. Understanding the factors leading to the release of systemic SAA from HDL may provide insights into chronic disease mechanisms.

Correlation Study of the Long-Term Prognosis of Venous Thromboembolism and Inflammatory Gene Polymorphisms

Background

Venous thromboembolism (VTE) is the third most common cause of cardiovascular death worldwide, following coronary heart disease and stroke, and many risk factors for VTE are not yet clear. Our study investigated the association between multiple inflammatory gene polymorphisms and VTE prognosis, aiming to find a new predictor of VTE prognosis.

Methods

Based on our previous studies, we detected the plasma levels of serum amyloid A protein (SAA), interleukin-1 (IL-1) and tumor necrosis factor-a (TNF-a) and their 8 gene polymorphisms by ELISA and a multiplex ligation detection reaction (iMLDR) method in 284 patients with VTE. All subjects were followed up for 5 years.

Results

The 5-year follow-up results of this study showed that 62 of the 284 patients (21.83%) had reached the endpoint (all-cause death). Kaplan–Meier survival analyses revealed that the mortality rate of VTE patients with a high Simplified Pulmonary Embolism Severity Index (SPESI) score and carrying IL-1 rs1800587 mutation genotypes was significantly increased (log-rank p=0.000 and 0.034 respectively). The multifactor Cox regression results confirmed that the mortality rate of patients who carrying IL-1 rs1800587 mutation genotypes was significantly increased (HR=2.982; 95% CI: 1.681–5.100). The mortality rate of those carrying IL-1 rs1143634 mutation genotypes was significantly decreased (HR=0.294; 95% CI: 0.132–0.652). There were no significant differences in mortality rates between wild-type and mutant genotypes of IL-1 rs1143634, IL-1 rs2234650, SAA rs11603089, and TNF-α rs1800629 (P>0.05).

Conclusion

A high SPESI score and the presence of the IL-1 rs1800587 mutant genotype predict shorter survival in patients with VTE, whereas the IL-1 rs1143634 genotype is associated with a lower mortality rate. Screening for mutations in inflammation-related genes has prognostic value in the clinical management of VTE.

Serum amyloid A1 can be a novel biomarker for evaluating the presence and severity of acute coronary syndrome

BACKGROUND

Serum amyloid A (SAA) is an acute phase protein and a novel inflammatory biomarker of cardiovascular diseases. Of the four subtypes, SAA1 is the most representative biomarker. In this study, we aimed to assess the value of SAA1 as a novel biomarker for evaluating the presence and severity of acute coronary syndrome (ACS) in Chinese patients.

METHODS AND RESULTS

A total of 140 ACS patients and 88 non-ACS patients (including 36 stable coronary artery disease (SCAD) patients and 52 healthy controls) who underwent coronary angiography were enrolled. The SAA1 level was significantly higher in ACS patients compared with the SCAD and healthy control subgroups (P < 0.001, respectively), and was significantly higher in the high SYNTAX Score II (SS II) group compared with the medium SS II group and low SS II group (P < 0.001, respectively) in ACS patients. The cutoff level of SAA1 for indicating the presence of ACS was 324.65 ng/mL (sensitivity of 77.9%, specificity of 60.2% and an area under the curve of 0.717). The increased SAA1 levels were positively associated with the presence (OR = 1.013, P < 0.001) and severity (OR = 1.023, P < 0.001) of ACS. Furthermore, there was a positive correlation between SAA1 levels and SS II (r = 0.467, P < 0.001).

CONCLUSIONS

Our results suggest that elevated SAA1 levels may be a novel biomarker for evaluating the presence of ACS and the severity of CAD in ACS patients. Measuring SAA1 levels makes it possible to evaluate the presence of ACS and severity of CAD in ACS patients.

Serum amyloid A4 is a procoagulant apolipoprotein that it is elevated in venous thrombosis patients

BACKGROUND

Serum amyloid A4 (SAA4) is an apolipoprotein that is in the SAA family and it is constitutively translated. Previously, acute-phase SAA1 and SAA2 levels were associated with venous thromboembolism (VTE).

OBJECTIVE

We investigated the association of plasma SAA4 with VTE and the role of SAA4 in coagulation.

PATIENTS AND METHODS

The association of SAA4 with VTE in a case-control study of adult VTE subjects (N = 113 each group) and the effects of recombinant SAA4 on plasma blood coagulation assays and prothrombin activation initiated by factor Xa were evaluated.

RESULTS

Plasma SAA4 levels in VTE subjects were higher vs. controls (48.1 vs. 38.4 µg/mL; P < .001). Elevated plasma SAA4 level (above the 90th percentile of controls) was associated with increased VTE occurrence (odds ratio, 3.8; 95% confidence interval, 1.8-8.0). This association remained significant after the adjustment for acute-phase SAA level, suggesting that SAA4 associated with VTE is independent of acute-phase SAA. Two isoforms of SAA4, that is, glycosylated and nonglycosylated SAA4 isoforms, were each higher in VTE patients. When recombinant SAA4 was added to plasma, it shortened factor Xa-1-stage clotting times, showing that it enhances clotting in plasma. In reaction mixtures containing purified factors Xa and Va and prothrombin, recombinant SAA4 increased prothrombin activation, showing that it enhances prothrombinase activity.

CONCLUSION

Elevated plasma constitutive SAA4 levels were linked to VTE in adults, and SAA4 can enhance thrombin generation in plasma. Our data highlight a previously unknown procoagulant activity of SAA4 that appears to be related to risk of venous thrombotic events.

Correlation study of venous thromboembolism with SAA, IL-1, and TNF-a levels and gene polymorphisms in Chinese population

Background

The relationship between inflammation and venous thromboembolism (VTE) has not been fully elucidated.

Methods

Based on our previous studies, we detected the plasma levels of serum amyloid A protein (SAA), interleukin-1 (IL-1), and tumor necrosis factor-a (TNF-a) and their 8 gene polymorphisms by ELISA and a multiplex ligation detection reaction (iMLDR) method in 284 patients with VTE and 268 healthy controls.

Results

Levels of SAA (P=0.032), IL-1 (P=0.045), and TNF-a (P=0.040) were significantly higher in the VTE group than in the control group. Recessive model analysis of the IL-1 rs1800587 variant showed that the risk of VTE in patients with the GG + GA genotype was significantly higher than that in patients with the AA genotype [odds ratio (OR): 4.444; 95% CI: 1.466-13.470]. Recessive model analysis of the IL-1 rs2234650 polymorphism showed that the risk of VTE in patients with the CC + CT genotype was significantly lower than that in patients with the TT genotype (OR: 0.500; 95% CI: 0.268-0.934). Multivariate logistic regression analysis showed that the TT genotype at IL-1 rs2234650 (OR: 2.086; 95% CI: 1.091-3.985) was an independent risk factor for VTE. The AA genotype of IL-1 rs1800587 (OR: 0.226; 95% CI: 0.074-0.890) was an independent protective factor against VTE.

Conclusions

In summary, an intrinsic relationship may exist between inflammatory activation and the occurrence of VTE.

Role of serum amyloid A in atherosclerosis

PURPOSE OF REVIEW

Acute phase serum amyloid A (SAA) is persistently elevated in chronic inflammatory conditions, and elevated levels predict cardiovascular risk in humans. More recently, murine studies have demonstrated that over-expression of SAA increases and deficiency/suppression of SAA attenuates atherosclerosis. Thus, beyond being a biomarker, SAA appears to play a causal role in atherogenesis. The purpose of this review is to summarize the data supporting SAA as a key player in atherosclerosis development.

RECENT FINDINGS

A number of pro-inflammatory and pro-atherogenic activities have been ascribed to SAA. However, the literature is conflicted, as recombinant SAA, and/or lipid-free SAA, used in many of the earlier studies, do not reflect the activity of native human or murine SAA, which exists largely lipid-associated. Recent literatures demonstrate that SAA activates the NLRP3 inflammasome, alters vascular function, affects HDL function, and increases thrombosis. Importantly, SAA activity appears to be regulated by its lipid association, and HDL may serve to sequester and limit SAA activity.

SUMMARY

SAA has many pro-inflammatory and pro-atherogenic activities, is clearly demonstrated to affect atherosclerosis development, and may be a candidate target for clinical trials in cardiovascular diseases.

Serum amyloid A, protein Z, and C4b-binding protein β chain as new potential biomarkers for pulmonary tuberculosis

The aim of this study was to discover novel biomarkers for pulmonary tuberculosis (TB). Differentially expressed proteins in the serum of patients with TB were screened and identified by iTRAQ-two dimensional liquid chromatography tandem mass spectrometry analysis. A total of 79 abnormal proteins were discovered in patients with TB compared with healthy controls. Of these, significant differences were observed in 47 abnormally expressed proteins between patients with TB or pneumonia and chronic obstructive pulmonary disease (COPD). Patients with TB (n = 136) exhibited significantly higher levels of serum amyloid A (SAA), vitamin K-dependent protein Z (PROZ), and C4b-binding protein β chain (C4BPB) than those in healthy controls (n = 66) (P<0.0001 for each) albeit significantly lower levels compared with those in patients with pneumonia (n = 72) (P<0.0001 for each) or COPD (n = 72) (P<0.0001, P<0.0001, P = 0.0016, respectively). After 6 months of treatment, the levels of SAA and PROZ were significantly increased (P = 0.022, P<0.0001, respectively), whereas the level of C4BPB was significantly decreased (P = 0.0038) in treated TB cases (n = 72). Clinical analysis showed that there were significant differences in blood clotting and lipid indices in patients with TB compared with healthy controls, patients with pneumonia or COPD, and treated TB cases (P<0.05). Correlation analysis revealed significant correlations between PROZ and INR (rs = 0.414, P = 0.044), and between C4BPB and FIB (rs = 0.617, P = 0.0002) in patients with TB. Receiver operating characteristic curve analysis revealed that the area under the curve value of the diagnostic model combining SAA, PROZ, and C4BPB to discriminate the TB group from the healthy control, pneumonia, COPD, and cured TB groups was 0.972, 0.928, 0.957, and 0.969, respectively. Together, these results suggested that SAA, PROZ, and C4BPB may serve as new potential biomarkers for TB. Our study may thus provide experimental data for the differential diagnosis of TB.

Serum amyloid A and atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis is a chronic inflammation associated with increased expression of the acute phase isoforms of serum amyloid A (SAA) and in humans is a plasma biomarker for future cardiovascular events. However, whether SAA is only a biomarker or participates in the development of cardiovascular disease is not well characterized. The purpose of this review is to summarize putative functions of SAA relevant to atherogenesis and in-vivo murine studies that directly examine the effect of SAA on atherosclerosis.

RECENT FINDINGS

Modulation of the expression of SAA1 and/or SAA2 in murine models of atherosclerosis suggests that SAA promotes early atherogenesis. SAA secreted from bone-marrow-derived cells contributes to this antiatherogenic phenotype. SAA also promotes angiotensin-induced abdominal aneurysm in atherogenic mouse models. The reduction in atherosclerosis may be due, at least in part, to remodeling of the acute phase HDL to reduce its capacity to promote cholesterol efflux and reduce its anti-inflammatory ability.

SUMMARY

SAA is more than a marker of cardiovascular disease and is a participant in the early atherogenic process.