The Inflammasomes in Cardiovascular Disease

Cardiac hypertrophy that affects hyperthyroidism occurs independently of the NLRP3 inflammasome

Cardiac hypertrophy (CH) is an adaptive response to maintain cardiac function; however, persistent stress responses lead to contractile dysfunction and heart failure. Although inflammation is involved in these processes, the mechanisms that control cardiac inflammation and hypertrophy still need to be clarified. The NLRP3 inflammasome is a cytosolic multiprotein complex that mediates IL-1β production. The priming step of NLRP3 is essential for increasing the expression of its components and occurs following NF-κB activation. Hyperthyroidism triggers CH, which can progress to maladaptive CH and even heart failure. We have shown in a previous study that thyroid hormone (TH)-induced CH is linked to the upregulation of S100A8, leading to NF-κB activation. Therefore, we aimed to investigate whether the NLRP3 inflammasome is involved in TH-induced CH and its potential role in CH pathophysiology. Hyperthyroidism was induced in NLRP3 knockout (NLRP3-KO), Caspase-1-KO and Wild Type (WT) male mice of the C57Bl/6J strain, aged 8-12 weeks, by triiodothyronine (7 μg/100 g BW, i.p.) administered daily for 14 days. Morphological and cardiac functional analysis besides molecular assays showed, for the first time, that TH-induced CH is accompanied by reduced NLRP3 expression in the heart and that it occurs independently of the NLRP3 inflammasome and caspase 1-related pathways. However, NLRP3 is important for the maintenance of basal cardiac function since NLRP3-KO mice had impaired diastolic function and reduced heart rate, ejection fraction, and fractional shortening compared with WT mice.

Repurposing FDA-approved drugs as NLRP3 inhibitors against inflammatory diseases: machine learning and molecular simulation approaches

Activation of NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) has been associated with multiple chronic pathologies, including diabetes, atherosclerosis, and rheumatoid arthritis. Moreover, histone deacetylases (HDACs), specifically HDAC6 is required for the NLRP3 inflammasome to assemble and activate. Thus, NLRP3 serves as an attractive target for the development of novel therapeutic approaches. Several companies are now attempting to develop specific modulators of the NLRP3 inflammasome, but only a handful of small molecules of NLRP3 inflammasome inhibitors, such as MCC950 and Tranilast, are currently available for clinical use. However, their use is limited due to severe side effects and short half-lives. Thus, the repurposing of FDA-approved drugs with NLRP3 inhibitory activity is needed. The present study was aimed at repurposing preexisting drugs that might act as safe and effective NLRP3 inhibitors. A library of 2,697 FDA-approved drugs was screened for binding with NLRP3 (PDB: 7ALV) using Glide (Schrödinger). The top seven FDA-approved drugs with potential binding affinities were selected based on docking scores and subjected to ADMET profiling using pkCSM and SwissADME. The binding of the ADMET-favorable FDA-approved drugs to NLRP3 was validated using MMGBSA (Prime) and Molecular Dynamics (Desmond) in the Schrödinger suite. ADMET profiling revealed that of the seven best docking drugs, empagliflozin and citicoline had good drug-likeness properties. Moreover, MMGBSA analysis and molecular dynamics demonstrated that empagliflozin and citicoline exhibited stable ligand-NLRP3 interactions in the presence of solvents. This study sheds light on the ability of various FDA-approved drugs to act as NLRP3 inhibitors.Communicated by Ramaswamy H. Sarma.

Mitophagy, Inflammasomes and Their Interaction in Kidney Diseases: A Comprehensive Review of Experimental Studies

Mitophagy is an important mechanism for mitochondrial quality control by regulating autophagosome-specific phagocytosis, degradation and clearance of damaged mitochondria, and involved in cell damage and diseases. Inflammasomes are important inflammation-related factors newly discovered in recent years, which are involved in cell innate immunity and inflammatory response, and play an important role in kidney diseases. Based on the current studies, we reviewed the progress of mitophagy, inflammasomes and their interaction in kidney diseases.

Cell-free circulating mitochondrial DNA: An emerging biomarker for airborne particulate matter associated with cardiovascular diseases

The association of airborne particulate matter exposure with the deteriorating function of the cardiovascular system is fundamentally driven by the impairment of mitochondrial-nuclear crosstalk orchestrated by aberrant redox signaling. The loss of delicate balance in retrograde communication from mitochondria to the nucleus often culminates in the methylation of the newly synthesized strand of mitochondrial DNA (mtDNA) through DNA methyl transferases. In highly metabolic active tissues such as the heart, mtDNA's methylation state alteration impacts mitochondrial bioenergetics. It affects transcriptional regulatory processes involved in biogenesis, fission, and fusion, often accompanied by the integrated stress response. Previous studies have demonstrated a paradoxical role of mtDNA methylation in cardiovascular pathologies linked to air pollution. A pronounced alteration in mtDNA methylation contributes to systemic inflammation, an etiological determinant for several co-morbidities, including vascular endothelial dysfunction and myocardial injury. In the current article, we evaluate the state of evidence and examine the considerable promise of using cell-free circulating methylated mtDNA as a predictive biomarker to reduce the more significant burden of ambient air pollution on cardiovascular diseases.

Dynamic Status of SII and SIRI Alters the Risk of Cardiovascular Diseases: Evidence from Kailuan Cohort Study

Background

Two novel systemic inflammation indices, SII and SIRI, are associated with increased risk of cardiovascular diseases (CVD). However, SII and SIRI are prone to change over time and the association between changeable status and long-term outcome risk remains to be uncovered. This study aims to examine the association between the dynamic status of SII and SIRI and risk of CVD.

Methods

This prospective study included a total of 45,809 subjects without MI, stroke and cancer prior to or in 2010 (baseline of this study). The dynamic status of SII and SIRI during 2006, 2008, and 2010 was assessed by dynamic trajectories (primary exposure), annual increase, and average value. The outcome was CVD incidence during 8.6 years' follow-up. Multiple Cox regression models were used to calculate the adjusted hazard ratios (HRs) and confidence intervals (95% CIs).

Results

Four dynamic trajectories of SII and SIRI were identified as follows: low stable pattern, moderate stable pattern, increase pattern, and decrease pattern. For SII, compared with "low stable pattern", after controlling confounders and level of SII in 2006, adjusted HRs were 1.24 (95% CI = 1.02-1.51) for "increase pattern" and 1.11 (95% CI = 1.00-1.23) for "moderate-stable pattern" while the association was not significant for "decrease pattern". Additionally, the highest group of annual SII increase and average SII had respective HR of 1.20 (95% CI = 1.05-1.37) and 1.32 (95% CI = 1.13-1.55). The results were consistent for SIRI. "Increase pattern" and "moderate stable pattern" increased the risk of CVD by 38% (HR = 1.38, 95% CI = 1.17-1.63) and 12% (HR = 1.12, 95% CI = 1.01-1.25), while no significant association was found for "decrease pattern". The highest group of annual SIRI increase and average SIRI had respective HR of 1.25 (95% CI = 1.09-1.44) and 1.39 (95% CI = 1.19-1.63).

Conclusion

Dynamic status of SII and SIRI was significantly associated with risk of CVD, which highlighted that we should focus on the dynamic change of SII and SIRI.

Emerging Roles of Inflammasomes in Cardiovascular Diseases

Cardiovascular diseases are known as the leading cause of morbidity and mortality worldwide. As an innate immune signaling complex, inflammasomes can be activated by various cardiovascular risk factors and regulate the activation of caspase-1 and the production and secretion of proinflammatory cytokines such as IL-1β and IL-18. Accumulating evidence supports that inflammasomes play a pivotal role in the progression of atherosclerosis, myocardial infarction, and heart failure. The best-known inflammasomes are NLRP1, NLRP3, NLRC4, and AIM2 inflammasomes, among which NLRP3 inflammasome is the most widely studied in the immune response and disease development. This review focuses on the activation and regulation mechanism of inflammasomes, the role of inflammasomes in cardiovascular diseases, and the research progress of targeting NLRP3 inflammasome and IL-1β for related disease intervention.

Sulfiredoxin-1 Inhibits PDGF-BB-Induced Vascular Smooth Muscle Cell Proliferation and Migration by Enhancing the Activation of Nrf2/ARE Signaling

Sulfiredoxin1 (Srxn1), an endogenous antioxidant protein, is involved in cardiovascular diseases. In this study, we aimed to investigate the role of Srxn1 in VSMCs and its molecular mechanism. The murine vascular smooth muscle cells MOVAS were treated with different doses of platelet-derived growth factor-BB (PDGF-BB); then, Srxn1 expression was detected using reverse transcription-quantitative polymerase chain reaction and western blot analysis. MTT and wound healing assay were used to examine the effect of Srxn1 on MOVAS cell proliferation and migration. Reactive oxygen species (ROS) production, malondialdehyde (MDA) level, and superoxide dismutase (SOD) activity in MOVAS cells were detected using corresponding commercial kits. Moreover, the expression of proliferating cell nuclear antigen (PCNA), matrix metalloproteinase 2 (MMP-2), and nuclear factor erythroid-2-related factor 2 (Nrf2) /antioxidant response element (ARE) signaling-related proteins was detected using western blot analysis. In our study, PDGF-BB dose-dependently increased Srxn1 expression in MOVAS cells, and Srxn1 expression was increased with time dependence in PDGF-BB-treated MOVAS cells. The knockdown of Srxn1 increased PDGF-BB-induced the proliferation, migration, ROS production, MDA level, and the protein expression of PCNA and MMP-2, as well as decreased SOD activity and the expression of Nrf2/ARE signaling-related proteins in PDGF-BB-stimulated MOVAS cells. However, the overexpression of Srxn1 showed the opposite results to those of knockdown of Srxn1. Moreover, the inhibitory effects of Srxn1 overexpression on PDGF-BB induced proliferation, migration, ROS production, and MDA level and the promotion of Srxn1 overexpression on PDGF-BB induced SOD activity were partially reversed by the knockdown of Nrf2. Srxn1 inhibited PDGF-BB-induced proliferation, migration, and oxidative stress through activating Nrf2/ARE signaling.

PDGF-BB promotes vascular smooth muscle cell migration by enhancing Pim-1 expression via inhibiting miR-214

Background

Several studies have indicated that the platelet-derived growth factor/platelet-derived growth factor receptor (PDGF/PDGFR) pathway is involved in the process of atherosclerosis. However, its underlying mechanism remains to be further elucidated. Serine/threonine-protein kinase pim-1 (Pim-1), a member of serine/threonine-specific kinases, is a pro-oncogene published to be related to cell proliferation, apoptosis, and metastasis of cancer cells. Whether Pim-1 is involved in PDGF/PDGFR pathway-mediated coronary atherosclerotic heart disease remains to be elucidated.

Methods

We established a cell model of PDGF-BB-stimulated smooth muscle cells using A7r5 cells. Transwell assay was used to detect the potential of cell migration and invasion. The targeted regulation of Pim-1 by miR-214 was confirmed by luciferase assay. Rescue experiments were performed to determine the role of the PDGF-BB/miR-214/Pim-1 axis on the cell migration of smooth muscle cells by including PDGF-BB treatment, and the overexpression of miR-214 and Pim-1. Quantitative polymerase chain reaction (qPCR) was used to examine the gene expression and western blot was performed to detect the protein expression.

Results

Our data indicated that PDGF-BB could effectively enhance smooth muscle cell migration. We also showed Pim-1 was a target of miR-214 in A7r5 cells. The expression of Pim-1 was shown to be upregulated by PDGF-BB via suppression of the expression of miR-214. Moreover, overexpression miR-214 inhibited PDGF-BB-stimulated Pim-1 expression and smooth muscle cell migration via modulating epithelial-mesenchymal transition (EMT), but no change on cell cycle. However, overexpression of Pim-1 reversed miR-214-blocked cell migration by promoting the activation of the STAT3, AKT, and ERK signaling pathways.

Conclusions

Our data suggested that the PDGF/miR-214/Pim-1 axis could be a potential target for coronary atherosclerotic heart disease.

Vascular and Cardiac Oxidative Stress and Inflammation as Targets for Cardioprotection

Cardiac and vascular diseases are often associated with increased oxidative stress and inflammation, and both may contribute to the disease progression. However, successful applications of antioxidants in the clinical setting are very rare and specific anti-inflammatory therapeutics only emerged recently. Reasons for this rely on the great diversity of oxidative stress and inflammatory cells that can either act as cardioprotective or cause tissue damage in the heart. Recent large-scale clinical trials found that highly specific anti-inflammatory therapies using monoclonal antibodies against cytokines resulted in lower cardiovascular mortality in patients with pre-existing atherosclerotic disease. In addition, unspecific antiinflammatory medication and established cardiovascular drugs with pleiotropic immunomodulatory properties such as angiotensin converting enzyme (ACE) inhibitors or statins have proven beneficial cardiovascular effects. Normalization of oxidative stress seems to be a common feature of these therapies, which can be explained by a close interaction/crosstalk of the cellular redox state and inflammatory processes. In this review, we give an overview of cardiac reactive oxygen species (ROS) sources and processes of cardiac inflammation as well as the connection of ROS and inflammation in ischemic cardiomyopathy in order to shed light on possible cardioprotective interventions.

Interleukin-1 Beta in Peripheral Blood Mononuclear Cell Lysates as a Longitudinal Biomarker of Response to Antidepressants: A Pilot Study

Interleukin-1 beta (IL1β) is primarily produced by monocytes in the periphery and the brain. Yet, IL1β protein levels have to date been investigated in major depressive disorder (MDD) and antidepressant response using either plasma or serum assays although with contradictory results, while mononuclear cell assays are lacking despite their extensive use in other contexts. In this pilot study, we comparatively assessed IL1β in mononuclear lysates and plasma in depressed MDD patients over treatment and healthy controls (HC). We recruited 31 consecutive adult MDD inpatients and 25 HC matched on age, sex, and BMI. Twenty-six patients completed an 8-week follow-up under treatment. IL1β was measured in both lysates and plasma in patients at baseline (T0) and at study end (T1) as well as in HC. We calculated ΔIL1β(%) for both lysates and plasma as IL1β percent changes from T0 to T1. Seventeen patients (65.4% of completers) were responders at T1 and had lower baseline BMI than non-responders (p = 0.029). Baseline IL1β from either plasma or lysates could not efficiently discriminate between depressed patients and HC, or between responders and non-responders. However, the two response groups displayed contrasting IL1β trajectories in lysates but not in plasma assays (response group by time interactions, p = 0.005 and 0.96, respectively). ΔIL1β(%) in lysates predicted response (p = 0.025, AUC = 0.81; accuracy = 84.6%) outperforming ΔIL1β(%) in plasma (p = 0.77, AUC=0.52) and was robust to adjusting for BMI. In conclusion, ΔIL1β(%) in mononuclear lysates may be a longitudinal biomarker of antidepressant response, potentially helpful in avoiding untimely switching of antidepressants, thereby warranting further investigation.

Gender Differences of NLRP1 Inflammasome in Mouse Model of Alzheimer's Disease

Background: There is a significant gender difference in the incidence and symptoms of Alzheimer's disease (AD), but its mechanisms are not completely understood. Recent studies showed that NLRP1 inflammasome was overexpressed in females under some pathological conditions such as nodular melanoma. Whether NLRP1 signals have a gender difference in AD has not been elucidated. This study was designed to investigate gender difference on the expressions of NLRP1 signals including NLRP1, Capase-1 and IL-1β in the brains of APP/PS1^+/- mice. Methods: Female and male APP/PS1^+/- mice (30-weeks-old) were used in this study. Amyloid-β (Aβ) plaques were stained with Congo red dye and cell apoptosis was detected by TUNEL staining. Expressions of NLRP1, Capase-1 and IL-1β were measured by immunofluorescent staining and Western blotting assay. Results: The numbers of Aβ plaques in cortex and hippocampus and neuronal apoptosis in cortex were 4 and 2-folds in females than males, respectively (P < 0.001). The average size of Aβ plaques in both cortex (females: 3527.11 ± 539.88 μm² vs. males: 1920.44 ± 638.49 μm²) and hippocampus (females: 1931 ± 308.61 μm² vs. males: 1038.55 ± 220.40 μm²) were also larger in females than males (P < 0.01). More interestingly, expressions of NLRP1, Caspase-1, and IL-1β were markedly increased in the cortex of females as compared with males. Conclusions: These findings show that NLRP1 signals are higher in brains of female APP/PS1^+/- mice than males, which may be related to the gender differences of AD.

Silencing CCL8 inhibited the proliferation and migration of PDGF-BB-stimulated human aortic smooth muscle cells

C-C motif Chemokine ligand 8 (CCL8) has been found in diseases' pathogenesis. But its molecular mechanism in atherosclerosis (AS) remains to be elucidated. Human aortic smooth muscle cells (HASMCs) were stimulated by PDGF-BB to establish cell model. α-SMA in PDGF-BB-stimulated HASMCs was measured by immunofluorescence staining. Relative gene expressions in PDGF-BB-stimulated HASMCs were detected by quantitative real-time polymerase chain reaction and western blot. HASMCs proliferation, migration, and cell cycle were assessed by cell counting kit-8, wound-healing assay, and flow cytometry. HASMCs viability was increased after PDGF-BB stimulation, with α-SMA downregulation yet CCL8 upregulation. Silencing CCL8 inhibited PDGF-BB-stimulated HASMCs proliferation and migration, and increased cells percentage in G1 phases but decreased those in S phase. Also, silencing CCL8 decreased OPN and cyclinD1 expressions and AKT and ERK1/2 phosphorylation while increased those of α-SMA and Sm22α. However, upregulating CCL8 led to opposite effects, suggesting CCL8 could be an atherosclerosis therapeutic target.

Female Heart Health: Is GPER the Missing Link?

The G Protein-Coupled Estrogen Receptor (GPER) is a novel membrane-bound receptor that mediates non-genomic actions of the primary female sex hormone 17β-estradiol. Studies over the past two decades have elucidated the beneficial actions of this receptor in a number of cardiometabolic diseases. This review will focus specifically on the cardiac actions of GPER, since this receptor is expressed in cardiomyocytes as well as other cells within the heart and most likely contributes to estrogen-induced cardioprotection. Studies outlining the impact of GPER on diastolic function, mitochondrial function, left ventricular stiffness, calcium dynamics, cardiac inflammation, and aortic distensibility are discussed. In addition, recent data using genetic mouse models with global or cardiomyocyte-specific GPER gene deletion are highlighted. Since estrogen loss due to menopause in combination with chronological aging contributes to unique aspects of cardiac dysfunction in women, this receptor may provide novel therapeutic effects. While clinical studies are still required to fully understand the potential for pharmacological targeting of this receptor in postmenopausal women, this review will summarize the evidence gathered thus far on its likely beneficial effects.