Immune Mechanisms of Plaque Instability

Research Advance of Chinese Medicine in Treating Atherosclerosis: Focus on Lipoprotein-Associated Phospholipase A2

As a serious cardiovascular disease, atherosclerosis (AS) causes chronic inflammation and oxidative stress in the body and poses a threat to human health. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a member of the phospholipase A2 (PLA2) family, and its elevated levels have been shown to contribute to AS. Lp-PLA2 is closely related to a variety of lipoproteins, and its role in promoting inflammatory responses and oxidative stress in AS is mainly achieved by hydrolyzing oxidized phosphatidylcholine (oxPC) to produce lysophosphatidylcholine (lysoPC). Moreover, macrophage apoptosis within plaque is promoted by localized Lp-PLA2 which also promotes plaque instability. This paper reviews those researches of Chinese medicine in treating AS via reducing Lp-PLA2 levels to guide future experimental studies and clinical applications related to AS.

The clinical efficacy of Shenxiang Suhe Pill administration in posterior circulation ischemic vertigo: A randomized controlled trial

BACKGROUND

Shenxiang Suhe Pill (SXSHP) is a traditional Chinese medicine (TCM) widely used to treat coronary heart disease. The present study aims to investigate the effect of SXSHP on posterior circulation ischemic (PCI) vertigo.

METHODS

One hundred and twenty patients with PCI vertigo were randomly divided into the control, low-dose, and high-dose groups with 40 patients in each group. The control group was treated with basic Western medicine. The low-dose and high-dose groups were treated with 0.7 g SXSHP once a day in the morning and twice a day in the morning and evening, respectively. The assessments were performed on days 14 and 28. The traditional Chinese medicine symptom score, average blood flow velocity of vertebral artery and basilar artery, blood viscosity, blood lipids, serum C-reactive protein level (CRP), blood routine test, and liver and kidney function were compared before and after treatment among the 3 groups.

RESULTS

In the evaluation of the traditional Chinese medicine symptom score, both low-dose and high-dose SXSHP treatments showed higher efficacy than the control group (P = .013). The average blood flow velocity of vertebral artery and basilar artery in the 3 groups showed an upward trend from baseline (P < .05). The blood viscosity and levels of fibrinogen, hematocrit, and CRP in the 3 groups showed a downward trend from baseline level (P < .05). The levels of total cholesterol, triglycerides, low-density lipoprotein, and CRP in the low-dose group and high-dose group were lower than those in the control group on day 28 (P < .05). There were no significant differences in the routine blood test and liver and kidney function between the low-dose and high-dose groups compared with the baseline values (P > .05).

CONCLUSION

SXSHP effectively improved PCI vertigo by inhibiting blood viscosity, regulating blood lipid levels, anti-inflammation, and improving cerebrovascular blood flow without affecting liver and kidney functions.

Sialic acid as the potential link between lipid metabolism and inflammation in the pathogenesis of atherosclerosis

In the modern world, cardiovascular diseases have a special place among the most common causes of death. Naturally, this widespread problem cannot escape the attention of scientists and researchers. One of the main conditions preceding the development of fatal cardiovascular diseases is atherosclerosis. Despite extensive research into its pathogenesis and possible prevention and treatment strategies, many gaps remain in our understanding of this disease. For example, the concept of multiple low-density lipoprotein modifications was recently stated, in which desialylation is of special importance. Apart from this, sialic acids are known to be important contributors to processes such as endothelial dysfunction and inflammation, which in turn are major components of atherogenesis. In this review, we have collected information on sialic acid metabolism, analyzed various aspects of its implication in atherosclerosis at different stages, and provided an overview of the role of particular groups of enzymes responsible for sialic acid metabolism in the context of atherosclerosis.

Lipoprotein(a) and Low-Molecular-Weight Apo(a) Phenotype as Determinants of New Cardiovascular Events in Patients with Premature Coronary Heart Disease

BACKGROUND

Lipoprotein(a) (Lp(a)) is a genetic risk factor of atherosclerotic cardiovascular diseases (ASCVDs). Proprotein convertase subtilisin/kexin type 9 (PCSK9) is related to vascular inflammation and detected in atherosclerotic plaques. A temporary increase in the circulating concentration of PCSK9 and Lp(a) was shown in patients with myocardial infarction (MI). The aim of this study was to evaluate the role of the apo(a) phenotype and the Lp(a) concentration as well as its complex with PCSK9 in the development of cardiac events and MI in patients with a premature manifestation of coronary heart disease (CHD).

METHODS

In a prospective study with retrospective data collection, we included 116 patients with premature CHD who were followed for a median of 14 years. The medical history and information on cardiovascular events after an initial exam as well as data on the levels of lipids, Lp(a), PCSK9, PCSK9-Lp(a) complex, and apo(a) phenotype were obtained.

RESULTS

The patients were divided into two groups depending on the presence of a low- (LMW, n = 52) or high-molecular weight (HMW, n = 64) apo(a) phenotype. LMW apo(a) phenotype (odds ratio 2.3 (1.1 to 4.8), p = 0.03), but not elevated Lp(a) (1.9 (0.8-4.6), p = 0.13), was an independent predictor for the development of MI after adjustment for sex, age of CHD debut, initial lipids levels, and lipid-lowering treatment. The apo(a) phenotype also determined the relationship between Lp(a) and PCSK9 concentrations. The level of the PCSK9-Lp(a) complex was higher in LMW apo(a) patients.

CONCLUSION

The LMW apo(a) phenotype is a risk factor for non-fatal MI in a long-term prospective follow-up of patients with premature CHD, and this link could be mediated via PCSK9.

Culprit plaque morphology determines inflammatory risk and clinical outcomes in acute coronary syndrome

AIMS

Rupture of the fibrous cap (RFC) and erosion of an intact fibrous cap (IFC) are the two predominant mechanisms causing acute coronary syndromes (ACS). It is uncertain whether clinical outcomes are different following RFC-ACS vs. IFC-ACS and whether this is affected by a specific inflammatory response. The prospective, translational OPTIcal-COherence Tomography in Acute Coronary Syndrome study programme investigates the impact of the culprit lesion phenotype on inflammatory profiles and prognosis in ACS patients.

METHODS AND RESULTS

This analysis included 398 consecutive ACS patients, of which 62% had RFC-ACS and 25% had IFC-ACS. The primary endpoint was a composite of cardiac death, recurrent ACS, hospitalization for unstable angina, and target vessel revascularization at 2 years [major adverse cardiovascular events (MACE+)]. Inflammatory profiling was performed at baseline and after 90 days. Patients with IFC-ACS had lower rates of MACE+ than those with RFC-ACS (14.3% vs. 26.7%, P = 0.02). In 368-plex proteomic analyses, patients with IFC-ACS showed lower inflammatory proteome expression compared with those with RFC-ACS, including interleukin-6 and proteins associated with the response to interleukin-1β. Circulating plasma levels of interleukin-1β decreased from baseline to 3 months following IFC-ACS (P < 0.001) but remained stable following RFC-ACS (P = 0.25). Interleukin-6 levels decreased in patients with RFC-ACS free of MACE+ (P = 0.01) but persisted high in those with MACE+.

CONCLUSION

This study demonstrates a distinct inflammatory response and a lower risk of MACE+ following IFC-ACS. These findings advance our understanding of inflammatory cascades associated with different mechanisms of plaque disruption and provide hypothesis generating data for personalized anti-inflammatory therapeutic allocation to ACS patients, a strategy that merits evaluation in future clinical trials.

Assessment of Inflammatory Hematological Ratios (NLR, PLR, MLR, LMR and Monocyte/HDL-Cholesterol Ratio) in Acute Myocardial Infarction and Particularities in Young Patients

Cardiovascular disease, particularly coronary artery disease (CAD), remains a predominant cause of mortality globally. Factors such as atherosclerosis and inflammation play significant roles in the pathogenesis of CAD. The nexus between inflammation and CAD is underscored by the role of immune cells, such as neutrophils, lymphocytes, monocytes, and macrophages. These cells orchestrate the inflammatory process, a core component in the initiation and progression of atherosclerosis. The activation of these pathways and the subsequent lipid, fibrous element, and calcification accumulation can result in vessel narrowing. Hematological parameters derived from routine blood tests offer insights into the underlying inflammatory state. Recent studies have highlighted the potential of inflammatory hematological ratios, such as the neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, monocyte/lymphocyte ratio and lymphocyte/monocyte ratio. These parameters are not only accessible and cost-effective but also mirror the degree of systemic inflammation. Several studies have indicated a correlation between these markers and the severity, prognosis, and presence of CAD. Despite the burgeoning interest in the relationship between inflammatory markers and CAD, there remains a paucity of data exploring these parameters in young patients with acute myocardial infarction. Such data could offer valuable insights into the unique pathophysiology of early-onset CAD and improve risk assessment and predictive strategies.

Apolipoprotein A-I vascular gene therapy reduces vein-graft atherosclerosis

Coronary artery venous bypass grafts typically fail because of atherosclerosis driven by lipid and macrophage accumulation. Therapy for vein-graft atherosclerosis is limited to statin drugs, which are only modestly effective. We hypothesized that transduction of vein-graft endothelium of fat-fed rabbits with a helper-dependent adenovirus expressing apolipoprotein AI (HDAdApoAI) would reduce lipid and macrophage accumulation. Fat-fed rabbits received bilateral external jugular vein-to-carotid artery interposition grafts. Four weeks later, one graft per rabbit (n = 23 rabbits) was infused with HDAdApoAI and the contralateral graft with HDAdNull. Grafts were harvested 12 weeks later. Paired analyses of grafts were performed, with vein graft cholesterol, intimal lipid, and macrophage content as the primary endpoints. HDAd genomes were detected in all grafts. APOAI mRNA was median 63-fold higher in HDAdApoAI grafts versus HDAdNull grafts (p < 0.001). HDAdApoAI grafts had a mean 15% lower total cholesterol (by mass spectrometry; p = 0.003); mean 19% lower intimal lipid (by oil red O staining; p = 0.02); and mean 13% lower expression of the macrophage marker CD68 (by reverse transcriptase-mediated quantitative PCR; p = 0.008). In vivo transduction of vein-graft endothelium achieves persistent APOAI expression and reduces vein-graft cholesterol, intimal lipid, and CD68 expression. Vascular gene therapy with APOAI has promise for preventing vein-graft failure caused by atherosclerosis.

Neutrophil-specific STAT4 deficiency attenuates atherosclerotic burden and improves plaque stability via reduction in neutrophil activation and recruitment into aortas of Ldlr-/- mice

Background and aims

Neutrophils drive atheroprogression and directly contribute to plaque instability. We recently identified signal transducer and activator of transcription 4 (STAT4) as a critical component for bacterial host defense in neutrophils. The STAT4-dependent functions of neutrophils in atherogenesis are unknown. Therefore, we investigated a contributory role of STAT4 in neutrophils during advanced atherosclerosis.

Methods

We generated myeloid-specific Stat4^ΔLysMLdlr^-/-, neutrophil-specific Stat4^ΔS100A8Ldlr^-/-, and control Stat4^fl/flLdlr^-/- mice. All groups were fed a high-fat/cholesterol diet (HFD-C) for 28 weeks to establish advanced atherosclerosis. Aortic root plaque burden and stability were assessed histologically by Movat pentachrome staining. Nanostring gene expression analysis was performed on isolated blood neutrophils. Flow cytometry was utilized to analyze hematopoiesis and blood neutrophil activation. In vivo homing of neutrophils to atherosclerotic plaques was performed by adoptively transferring prelabeled Stat4^ΔLysMLdlr^-/- and Stat4^fl/flLdlr^-/- bone marrow cells into aged atherosclerotic Apoe^-/- mice and detected by flow cytometry.

Results

STAT4 deficiency in both myeloid-specific and neutrophil-specific mice provided similar reductions in aortic root plaque burden and improvements in plaque stability via reduction in necrotic core size, improved fibrous cap area, and increased vascular smooth muscle cell content within the fibrous cap. Myeloid-specific STAT4 deficiency resulted in decreased circulating neutrophils via reduced production of granulocyte-monocyte progenitors in the bone marrow. Neutrophil activation was dampened in HFD-C fed Stat4^ΔLysMLdlr^-/- mice via reduced mitochondrial superoxide production, attenuated surface expression of degranulation marker CD63, and reduced frequency of neutrophil-platelet aggregates. Myeloid-specific STAT4 deficiency diminished expression of chemokine receptors CCR1 and CCR2 and impaired in vivo neutrophil trafficking to atherosclerotic aorta.

Conclusions

Our work indicates a pro-atherogenic role for STAT4-dependent neutrophil activation and how it contributes to multiple factors of plaque instability during advanced atherosclerosis in mice.

Enhanced Local Delivery of microRNA-145a-5P into Mouse Aorta via Ultrasound-Targeted Microbubble Destruction Inhibits Atherosclerotic Plaque Formation

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) play a key role in the formation and rupture of atherosclerotic plaques. Previous studies have confirmed that microRNA-145 (miR-145) is involved in the phenotypic regulation of VSMCs and reduction of atherosclerosis. At present, seeking safe and effective gene delivery remains a key problem restricting the development of gene therapy. In recent years, ultrasound-targeted microbubble destruction (UTMD) has become a safe and effective transfection method that is widely used in the basic research of gene therapy for heart and tumor diseases. Here, we synthesized cationic microbubbles to encapsulate miR-145 and targeted their release into VSMCs in vitro and in vivo using ultrasound. The feasibility of this gene therapy was verified by fluorescence microscopy and an in vivo imaging system. The results showed that treatment with miR-145 delivered via UTMD considerably improved the gene transfection efficiency and promoted the contraction phenotype of VSMCs in vitro. In vivo, this treatment reduced the atherosclerotic plaque area by 48.04% compared with treatment with free miR-145. Therefore, UTMD-mediated miRNA therapy may provide a new targeted therapeutic approach for atherosclerotic plaques.

Association of Interleukin-32 and Interleukin-34 with Cardiovascular Disease and Short-Term Mortality in COVID-19

BACKGROUND

Excess cardiovascular (CV) morbidity and mortality has been observed in patients with COVID-19. Both interleukin-32 (IL-32) and interleukin-34 (IL-34) have been hypothesized to contribute to CV involvement in COVID-19.

METHODS

This prospective, observational study of patients with laboratory-confirmed COVID-19 infection was conducted from 6 June to 22 December 2020 in a tertiary care hospital in Vienna, Austria. IL-32 and IL-34 levels on admission were collected and tested for their association with CV disease and short-term mortality in patients with COVID-19. CV disease was defined by the presence of coronary artery disease, heart failure, stroke or atrial fibrillation and patients were stratified by CV disease burden.

RESULTS

A total of 245 eligible patients with COVID-19 were included, of whom 37 (15.1%) reached the primary endpoint of 28-day mortality. Of the total sample, 161 had no CV disease (65.7%), 69 had one or two CV diseases (28.2%) and 15 patients had ≥three CV diseases (6.1%). Median levels of IL-32 and IL-34 at admission were comparable across the three groups of CV disease burden. IL-32 and IL-34 failed to predict mortality upon both univariable and multivariable Cox regression analysis. The two CV disease groups, however, had a significantly higher risk of mortality within 28 days (one or two CV diseases: crude HR 4.085 (95% CI, 1.913-8.725), p < 0.001 and ≥three CV diseases: crude HR 13.173 (95% CI, 5.425-31.985), p < 0.001). This association persisted for those with ≥three CV diseases after adjustment for age, gender and CV risk factors (adjusted HR 3.942 (95% CI, 1.288-12.068), p = 0.016).

CONCLUSION

In our study population of hospitalized patients with COVID-19, IL-32 and IL-34 did not show any associations with CV disease or 28-day mortality in the context of COVID-19. Patients with multiple CV diseases, however, had a significantly increased risk of short-term mortality.

Guanmaitong Granule Attenuates Atherosclerosis by Inhibiting Inflammatory Immune Response in ApoE−/− Mice Fed High-Fat Diet

Background

Atherosclerosis (AS) is the leading cause of cardiovascular diseases, such as myocardial infarction and stroke. Guanmaitong granule (GMTG) is a TCM (Traditional Chinese medicine) prescribed to treat AS. However, its mechanism remains unclear.

Methods

We obtained reliable ingredients and targets of GMTG using the HERB database. AS-related targets were obtained from HERB and GeneCards databases. The target database was constructed by intersecting the ingredients of GMTG with the AS-related targets. STRING and Cytoscape were used to create protein-protein interaction (PPI) network and screen core targets. GO enrichment analysis and KEGG pathway analyses were performed using R. Finally, the ApoE^−/− mice AS model was induced by a high-fat diet (HFD) for in vivo validation of core pathways and targets.

Results

A total of 124 ingredients and 418 potential targets of GMTG for treating AS were obtained. Numerous ingredients and targets were related to Panax notoginseng, Salvia miltiorrhiza, and Astragalus. Most core targets and pathways were involved in the inflammatory immune response. GMTG could decrease serum triglycerides, total cholesterol, low-density lipoprotein-cholesterol, and oxidized low-density lipoprotein level and increase the serum high-density lipoprotein-cholesterol level. Furthermore, GMTG reduced the plaque burden and promoted plaque remodeling by reducing plaque area, lipid deposition, foam cell content, and collagen fiber content in the plaque in the aortic root of ApoE^−/− mice. GMTG inhibited systemic and plaque inflammatory immune response and increased plaque stability by inhibiting the excessive release of the TLR4/MyD88/NF-κB pathway-induced inflammatory cytokines, tumor necrosis factor, interleukin-6, and interleukin-1 beta.

Conclusion

Radix notoginseng, Radix salviae liguliobae, and Radix astragali are the main ingredients of GMTG for treating AS. Further, GMTG could regulate the level of serum lipids and inhibit inflammatory immune response, which resulted in anti-AS effects such as plaque stabilization, reduction of plaque burden, and plaque remodeling. GMTG is a promising multi-target treatment for AS.

Bacterial Infections and Atherosclerosis – A Mini Review

Atherosclerosis is the most challenging subsets of coronary artery disease in humans, in which risk factors emerge from childhood, and its prevalence increases with age. Experimental research demonstrates that infections due to bacteria stimulate atherogenic events. Atherosclerosis has complex pathophysiology that is linked with several bacterial infections by damaging the inner arterial wall and heart muscles directly and indirectly by provoking a systemic pro-inflammation and acute-phase protein. Repeated bacterial infections trigger an inflammatory cascade that triggers immunological responses that negatively impact cardiovascular biomarkers includes triglycerides, high-density lipoprotein, C-reactive protein, heat shock proteins, cytokines, fibrinogen, and leukocyte count. Herein, we intended to share the role of bacterial infection in atherosclerosis and evaluate existing evidence of animal and human trials on the association between bacterial infections and atherosclerosis on update.

Dynamic Changes of Carotid Atherosclerosis and Their Relation with Stroke Recurrence in Patients with Stroke or Transient Ischemic Attack

BACKGROUND AND PURPOSE

The purpose of this study was to show dynamic changes in carotid and vertebral artery using carotid Doppler ultrasonography (DUS) through a long-term follow- up exam, and determine their associations with stroke recurrence.

METHODS

We consecutively enrolled stroke or transient ischemic attack (TIA) patients who had undergone DUS more than twice with intervals of three months or more. Stroke recurrence during follow-up was also investigated by reviewing medical records. Progress or regress of plaque was defined as more than 0.1 mm change from the initial scan with a semi-quantitative measurement. The development of new plaque was also regarded as plaque progress. Increased intima-media thickness and plaque presence were interpreted at the initial and follow-up scans. Factors related to progression or regression were analyzed. The relationship between plaque change and stroke recurrence was investigated.

RESULTS

A total of 201 patients were enrolled (186 ischemic stroke patients and 15 TIA patients). There were 61 (30.3%) females. Their mean age was 64.2 ± 9.9 years. During a follow-up of 35.0 ± 22.6 (mean ± SD) months, plaque progress was observed in 92 (45.8%) and plaque regress in 13 (6.5%). Stroke recurred in 18 patients. Plaque progression showed no significant association with age, risk factors, statin use, or subtype. After adjustment of age, sex, diabetes, and stroke subtype, multiple logistic regression showed a significant association of plaque progression with stroke recurrence (odds ratio: 3.8, 95% confidence interval: 1.1 to 13.1, p = 0.034). Patients with plaque regress were significantly younger than those without plaque regress (57.8 years vs. 64.6 years, p = 0.041).

CONCLUSION

Plaque progression occurred in 46% of stroke or TIA patients. Plaque progression was significantly associated with clinical stroke recurrence. Plaque regressed in 6.5% of patients. Patients with regression were younger than those without.