Inflammasomes: a preclinical assessment of targeting in atherosclerosis

Efficacy of Jiangzhi Xiaoban tablet on toll-like receptor 4/nuclear factor-kappa B/nod-like receptor protein 3 signaling pathway in mice with atherosclerosis induced by high-fat diet

OBJECTIVE

To study the effect of Jiangzhi Xiaoban tablet (, JZXB) on toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB)/Nod-like receptor protein 3 (NLRP3) signaling pathway expression in atherosclerosis (AS) mice by establishing a mouse model of AS, and to explore its mechanism of prevention and treatment of AS.

METHODS

Sixty-four male C57BL/6J mice were randomly divided into two groups, 12 in the normal control group and 52 in the model group (MOD). Seven weeks later, two mice in each of the above two groups were randomly sacrificed, and the whole aortic tissue of the mice was taken out for hematoxylin-eosin staining. After successful modeling, 50 mice in the modeling group were randomly divided into 5 groups: MOD, atorvastatin group (ATO), low-dose group of JZXB (JZXB-L), middle-dose group of JZXB (JZXB-M), and high-dose group of JZXB (JZXB-H), 10 mice in each group. The mice in each group were killed after 6 weeks of preventive administration. HE staining was used to observe the pathological changes of aorta in AS mice. The levels of serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were detected by automatic biochemical analyzer. The levels of inflammatory factor interleukin-1β (IL-1β) were detected by enzyme linked immunosorbent assay. The expression of TLR4, NF-κB and NLRP3 proteins in aortic tissue was detected by immunohistochemistry.

RESULTS

Compared with the MOD, the levels of serum TC, TG and LDL-C in the JZXB-H and ATO were significantly decreased, while the level of HDL-C was significantly increased. The levels of serum TG, LDL-C in the JZXB-M were significantly decreased, and the level of HDL-C was significantly increased. Compared with the MOD, the levels of IL-1β were significantly decreased, aortic lesions were significantly improved, and the expression of TLR4, NF-κB, and NLRP3 proteins in the aortic tissue was significantly decreased in the JZXB-H, JZXB-M, and ATO.

CONCLUSION

JZXB has inhibitory effect on atherosclerosis in mice, and its mechanism may be through regulating the TLR4/NF-κB/NLRP3 signaling pathway and reducing the inflammatory response, so as to play a role in inhibiting atherosclerosis.

Anti-inflammation-based treatment of atherosclerosis using Gliclazide-loaded biomimetic nanoghosts

In the study, a biomimetic platform for anti-inflammatory-based treatment of atherosclerotic plaque was developed. Gliclazide (GL) as an anti-inflammasome agent was encapsulated in PLGA nanoparticles (NP), which were coated by monocyte membrane using an extrusion procedure. The size and zeta potential of the nanoghost (NG) changed to 292 and - 10 nm from 189.5 to -34.1 in the core NP. In addition, the actual size of 62.5 nm with a coating layer of 5 nm was measured using TEM. The NG was also showed a sustained release profile with the drug loading content of about 4.7%. Beside to attenuated TNFα, decrease in gene expression levels of NLRP3, MyD88, NOS, IL-1β, IL-18 and caspases 1/3/8/9 in LPS-primed monocytes exposed to NG strongly indicated remarkable inflammation control. After systemic toxicity evaluation and pharmacokinetic analysis of NP and NG, intravenous NG treatment of rabbits with experimentally induced atherosclerosis revealed remarkably less plaque lesions, foam cells, lipid-laden macrophages, and pathological issues in tunica media of aorta sections. Higher expression of CD163 than CD68 in aorta of NG-treated rabbits strongly reveals higher M2/M1 macrophage polarization. The bio/hemocompatible, biomimetic and anti-inflammatory NG can be considered as a potential platform for immunotherapy of particularly atherosclerosis in the field of personalized medicine.

Loss of Macrophage mTORC2 Drives Atherosclerosis via FoxO1 and IL-1β Signaling

BACKGROUND

The mTOR (mechanistic target of rapamycin) pathway is a complex signaling cascade that regulates cellular growth, proliferation, metabolism, and survival. Although activation of mTOR signaling has been linked to atherosclerosis, its direct role in lesion progression and in plaque macrophages remains poorly understood. We previously demonstrated that mTORC1 (mTOR complex 1) activation promotes atherogenesis through inhibition of autophagy and increased apoptosis in macrophages.

METHODS

Using macrophage-specific Rictor- and mTOR-deficient mice, we now dissect the distinct functions of mTORC2 pathways in atherogenesis.

RESULTS

In contrast to the atheroprotective effect seen with blockade of macrophage mTORC1, macrophage-specific mTORC2-deficient mice exhibit an atherogenic phenotype, with larger, more complex lesions and increased cell death. In cultured macrophages, we show that mTORC2 signaling inhibits the FoxO1 (forkhead box protein O1) transcription factor, leading to suppression of proinflammatory pathways, especially the inflammasome/IL (interleukin)-1β response, a key mediator of vascular inflammation and atherosclerosis. In addition, administration of FoxO1 inhibitors efficiently rescued the proinflammatory response caused by mTORC2 deficiency both in vitro and in vivo. Interestingly, collective deletion of macrophage mTOR, which ablates mTORC1- and mTORC2-dependent pathways, leads to minimal change in plaque size or complexity, reflecting the balanced yet opposing roles of these signaling arms.

CONCLUSIONS

Our data provide the first mechanistic details of macrophage mTOR signaling in atherosclerosis and suggest that therapeutic measures aimed at modulating mTOR need to account for its dichotomous functions.

Synthesis and Evaluation of [11C]MCC950 for Imaging NLRP3-Mediated Inflammation in Atherosclerosis

Overexpression of the NLRP3 inflammasome has been attributed to the progressive worsening of a multitude of cardiovascular inflammatory diseases such as myocardial infarction, pulmonary arterial hypertension, and atherosclerosis. The recently discovered potent and selective NLRP3 inhibitor MCC950 has shown promise in hindering disease progression, but NLRP3-selective cardiovascular positron emission tomography (PET) imaging has not yet been demonstrated. We synthesized [¹¹C]MCC950 with no-carrier-added [¹¹C]CO₂ fixation chemistry using an iminophosphorane precursor (RCY 45 ± 4%, >99% RCP, 27 ± 2 GBq/μmol, 23 ± 3 min, n = 6) and determined its distribution both in vivo and ex vivo in C57BL/6 and atherogenic ApoE^-/- mice. Small animal PET imaging was performed in both strains following intravenous administration via the lateral tail vein and revealed considerable uptake in the liver that stabilized by 20 min (7-8.5 SUV), coincident with secondary renal excretion. Plasma metabolite analysis uncovered excellent in vivo stability of [¹¹C]MCC950 (94% intact). Ex vivo autoradiography performed on excised aortas revealed heterogeneous uptake in atherosclerotic plaques of ApoE^-/- mice in comparison to C57BL/6 controls (48 ± 17 %ID/m² vs 18 ± 8 %ID/m², p = 0.002, n = 4-5). Treatment of ApoE^-/- mice with nonradioactive MCC950 (5 mg/kg, iv) 10 min prior to radiotracer administration increased uptake in the intestine (5.3 ± 1.8 %ID/g vs 11.0 ± 3.7 %ID/g, p = 0.04, n = 4-6) and in aortic lesions (48 ± 17 %ID/m² vs 104 ± 15 %ID/m², p = 0.0002, n = 5) by 108% and 117%, respectively, without significantly increasing plasma free fraction (f_p, 1.3 ± 0.4% vs 1.7 ± 0.8%, n = 2). These results suggest that [¹¹C]MCC950 uptake demonstrates specific binding and may prove useful for in vivo NLRP3 imaging in atherosclerosis.

Inflammation in coronary artery disease-clinical implications of novel HDL-cholesterol-related inflammatory parameters as predictors

Coronary artery disease (CAD) is the leading cause of death worldwide. Inflammation and atherosclerotic plaques are the primary pathological mechanisms of CAD. Upon stimulation by deposited lipids and damaged endothelium, innate and adaptive immune cells are activated and recruited to initiate plaque development. Therefore, inflammatory cells and mediators are used to identify inflammatory risk in CAD patients. HDL-cholesterol (HDL-C) is demonstrated to have anti-inflammatory roles in atherosclerosis by interfering with plasma membrane lipid rafts of immune cells. Based on this, novel inflammatory parameters such as monocyte to HDL-C ratio are explored to improve the risk estimation of CAD prognosis. Moreover, with the advance in treatment strategies targeting the inflammatory process in atherosclerosis, identifying CAD patients with increased inflammatory risk by novel inflammatory parameters is of great importance in guiding CAD management. Therefore, this review aims to summarize the current information regarding inflammatory activation and HDL-C in atherosclerosis with a particular focus on the clinical implication of the novel HDL-C-related inflammatory parameters in CAD.

The Role of Mitochondria-Derived Peptides in Cardiovascular Diseases and Their Potential as Therapeutic Targets

Mitochondria-derived peptides (MDPs) are small peptides hidden in the mitochondrial DNA, maintaining mitochondrial function and protecting cells under different stresses. Currently, three types of MDPs have been identified: Humanin, MOTS-c and SHLP1-6. MDPs have demonstrated anti-apoptotic and anti-inflammatory activities, reactive oxygen species and oxidative stress-protecting properties both in vitro and in vivo. Recent research suggests that MDPs have a significant cardioprotective role, affecting CVDs (cardiovascular diseases) development and progression. CVDs are the leading cause of death globally; this term combines disorders of the blood vessels and heart. In this review, we focus on the recent progress in understanding the relationships between MDPs and the main cardiovascular risk factors (atherosclerosis, insulin resistance, hyperlipidaemia and ageing). We also will discuss the therapeutic application of MDPs, modified and synthetic MDPs, and their potential as novel biomarkers and therapeutic targets.

NLRP3 Inflammasome as a Common Denominator of Atherosclerosis and Abdominal Aortic Aneurysm

Atherosclerosis and abdominal aortic aneurysm (AAA) are multifactorial diseases characterized by inflammatory cell infiltration, matrix degradation, and thrombosis in the arterial wall. Although there are some differences between atherosclerosis and AAA, inflammation is a prominent common feature of these disorders. The nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a cytosolic multiprotein complex that activates caspase-1 and regulates the release of proinflammatory cytokines interleukin (IL)-1β and IL-18, as well as the induction of lytic cell death, termed pyroptosis, thereby leading to inflammation. Previous experimental and clinical studies have demonstrated that inflammation in atherosclerosis and AAA is mediated primarily through the NLRP3 inflammasome. Furthermore, recent results of the Canakinumab Anti-inflammatory Thrombosis and Outcome Study (CANTOS) showed that IL-1β inhibition reduces systemic inflammation and prevents atherothrombotic events; this supports the concept that the NLRP3 inflammasome is a promising therapeutic target for cardiovascular diseases, including atherosclerosis and AAA. This review summarizes current knowledge with a focus on the role of the NLRP3 inflammasome in atherosclerosis and AAA, and discusses the prospects of NLRP3 inflammasome-targeted therapy.

NLRP3 inflammasome as a key driver of vascular disease

NLRP3 (nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3) is an intracellular innate immune receptor that recognizes a diverse range of stimuli derived from pathogens, damaged or dead cells, and irritants. NLRP3 activation causes the assembly of a large multiprotein complex termed the NLRP3 inflammasome, and leads to the secretion of bioactive interleukin (IL)-1β and IL-18 as well as the induction of inflammatory cell death termed pyroptosis. Accumulating evidence indicates that NLRP3 inflammasome plays a key role in the pathogenesis of sterile inflammatory diseases, including atherosclerosis and other vascular diseases. Indeed, the results of the Canakinumab Anti-inflammatory Thrombosis Outcome Study (CANTOS) trial demonstrated that IL-1β-mediated inflammation plays an important role in atherothrombotic events and suggested that NLRP3 inflammasome is a key driver of atherosclerosis. In this review, we will summarize the current state of knowledge regarding the role of NLRP3 inflammasome in vascular diseases, in particular in atherosclerosis, vascular injury, aortic aneurysm, and Kawasaki disease vasculitis, and discuss NLRP3 inflammasome as a therapeutic target for these disorders.