An ERK5-NRF2 Axis Mediates Senescence-Associated Stemness and Atherosclerosis

Unravelling molecular mechanisms in atherosclerosis using cellular models and omics technologies

Despite the discovery and prevalent clinical use of potent lipid-lowering therapies, including statins and PCSK9 inhibitors, cardiovascular diseases (CVD) caused by atherosclerosis remain a large unmet clinical need, accounting for frequent deaths worldwide. The pathogenesis of atherosclerosis is a complex process underlying the presence of modifiable and non-modifiable risk factors affecting several cell types including endothelial cells (ECs), monocytes/macrophages, smooth muscle cells (SMCs) and T cells. Heterogeneous composition of the plaque and its morphology could lead to rupture or erosion causing thrombosis, even a sudden death. To decipher this complexity, various cell model systems have been developed. With recent advances in systems biology approaches and single or multi-omics methods researchers can elucidate specific cell types, molecules and signalling pathways contributing to certain stages of disease progression. Compared with animals, in vitro models are economical, easily adjusted for high-throughput work, offering mechanistic insights. Hereby, we review the latest work performed employing the cellular models of atherosclerosis to generate a variety of omics data. We summarize their outputs and the impact they had in the field. Challenges in the translatability of the omics data obtained from the cell models will be discussed along with future perspectives.

RSK1 and RSK2 as therapeutic targets: an up-to-date snapshot of emerging data

INTRODUCTION

The four members of the p90 ribosomal S6 kinase (RSK) family are serine/threonine protein kinases, which are phosphorylated and activated by ERK1/2. RSK1/2/3 are further phosphorylated by PDK1. Receiving inputs from two major signaling pathways places RSK as a key signaling node in numerous pathologies. A plethora of RSK1/2 substrates have been identified, and in the majority of cases the causative roles these RSK substrates play in the pathology are unknown.

AREAS COVERED

The majority of studies have focused on RSK1/2 and their functions in a diverse group of cancers. However, RSK1/2 are known to have important functions in cardiovascular disease and neurobiological disorders. Based on the literature, we identified substrates that are common in these pathologies with the goal of identifying fundamental physiological responses to RSK1/2.

EXPERT OPINION

The core group of targets in pathologies driven by RSK1/2 are associated with the immune response. However, there is a paucity of the literature addressing RSK function in inflammation, which is critical to know as the pan RSK inhibitor, PMD-026, is entering phase II clinical trials for metastatic breast cancer. A RSK inhibitor has the potential to be used in numerous diverse diseases and disorders.

Radiation-Induced Macrovessel/Microvessel Disease

Radiation therapy (RT) is a cornerstone in cancer treatment (used in 50% of cases), yet challenges persist because damage to normal tissue through direct impact of radiation or bystander effects is inevitable. Injury of macrovessels by RT manifests as obstructive disease, which is akin to atherosclerotic disease. Historically observed in coronary arteries of patients treated for breast cancer and lymphoma, it also affects patients receiving contemporary therapy for lung and chest cancers. Moreover, radiation at various sites can lead to peripheral vascular disease. An aspect of radiation-induced injury that has received little attention is microvascular injury, which typically results from damage to the endothelium and is considered the primary driver of RT-induced toxicity in the skin, kidney, and brain. This review delves into the clinical manifestations of RT-induced vascular disease, signaling pathways, cellular targets affected by radiation injury, and preclinical models of RT-induced vascular injury. The goal is to inspire the development of innovative strategies to prevent RT-related cardiovascular disease.

Glycoprotein non-metastatic melanoma protein B (GPNMB): An attractive target in atherosclerosis

Atherosclerosis (AS), the leading cause of cardiovascular diseases, is heavily influenced by inflammation, lipid accumulation, autophagy, and aging. The expression of glycoprotein non-metastatic melanoma B (GPNMB) has been observed to correlate with lipid content, inflammation, and aging, progressively increasing as atherosclerosis advances through its various stages, from baseline to early and advanced phases. However, the interaction between GPNMB and AS is controversial. Knockout of GPNMB has been shown to increase atherosclerotic plaque burden in mice. Conversely, targeted elimination of GPNMB-positive cells reduced atherosclerotic burden. These seemingly contradictory findings underscore the complexity of the issue and highlight the need for further research to reconcile these discrepancies and to elucidate the precise role of GPNMB in the pathogenesis of AS.

Asperuloside as a Novel NRF2 Activator to Ameliorate Endothelial Dysfunction in High Fat Diet-Induced Obese Mice

Aims: Current treatments are inadequate in alleviating obesity-associated vascular diseases. The development of effective therapies to ameliorate endothelial dysfunction and attenuate oxidative stress is of utmost importance. Asperuloside (ASP), a bioactive compound extracted from Eucommia species, exhibits antiobesity properties. However, the effects of ASP on vasculopathy have not been investigated. Therefore, the effects of ASP on vascular dysfunction and related mechanisms were elucidated. Results: ASP significantly reversed the impaired endothelium-dependent relaxations (EDRs) in obese mice and interleukin (IL)-1β-treated aortas. ASP suppressed endothelial activation in obese mice aortas and IL-1β-treated endothelial cells. ASP attenuated oxidative stress, scavenged mitochondrial reactive oxygen species (ROS), and upregulated heme oxygenase-1 (HO-1) expression in endothelium, independent of its anti-inflammatory properties. HO-1 knockdown diminished the protective effects of ASP against impaired EDRs, ROS overproduction, and endothelial activation. Endothelial cell-specific nuclear factor erythroid 2-related factor 2 (Nrf2) knockdown eliminated the ASP-mediated vascular protective effects and endothelial HO-1 upregulation, emphasizing that ASP improves endothelial function by activating Nrf2/HO-1 signaling. ASP facilitated Nrf2 nuclear translocation and the direct binding of Nrf2 to antioxidant response element, thereby enhancing HO-1 transcription and scavenging ROS. The cellular thermal shift assay results provide the first experimental characterization of the direct binding of ASP to Nrf2. Conclusions: These findings demonstrate that ASP ameliorates obesity-associated endothelial dysfunction by activating Nrf2/HO-1 signaling and thereby maintaining redox hemostasis, suggesting its potential as a novel Nrf2-targeted therapeutic agent and dietary supplement for vasculopathy.

The role of aryl hydrocarbon receptors in nutrient metabolism and immune regulation at the maternal-fetal interface

The maternal-fetal interface is composed of the placenta, which is affiliated with the fetus, and the maternal decidua. During pregnancy, the placenta is mainly responsible for nutrient transport and immune tolerance maintenance, which plays a key role in fetal growth and development and pregnancy maintenance. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that exists in various cell types at the maternal-fetal interface and is involved in multiple cellular processes. Recent studies have highlighted the role of AhR in regulating various physiological processes, including glucose and lipid metabolism, as well as tryptophan metabolism and immune responses, within non-pregnant tissues. This review shifts focus towards understanding how AhR modulation impacts metabolism and immune regulation at the maternal-fetal interface. This may implicate the development of pregnancy-related complications and the potential target of the AhR pathway for therapeutic strategies against poor pregnancy outcomes.

Bone and Extracellular Signal-Related Kinase 5 (ERK5)

Bones are vital for anchoring muscles, tendons, and ligaments, serving as a fundamental element of the human skeletal structure. However, our understanding of bone development mechanisms and the maintenance of bone homeostasis is still limited. Extracellular signal-related kinase 5 (ERK5), a recently identified member of the mitogen-activated protein kinase (MAPK) family, plays a critical role in the pathogenesis and progression of various diseases, especially neoplasms. Recent studies have highlighted ERK5's significant role in both bone development and bone-associated pathologies. This review offers a detailed examination of the latest research on ERK5 in different tissues and diseases, with a particular focus on its implications for bone health. It also examines therapeutic strategies and future research avenues targeting ERK5.

Inhibition effect of copper-bearing metals on arterial neointimal hyperplasia via the AKT/Nrf2/ARE pathway in vitro and in vivo

In-stent restenosis can be caused by the activation, proliferation and migration of vascular smooth muscle cells (VSMCs), which affects long-term efficacy of interventional therapy. Copper (Cu) has been proved to accelerate the endothelialization and reduce thrombosis formation, but little is known about its inhibition effect on the excessive proliferation of VSMCs. In this study, 316L-Cu stainless steel and L605-Cu cobalt-based alloy with varying Cu content were fabricated and their effects on surface property, blood compatibility and VSMCs were studied in vitro and in vivo. CCK-8 assay and EdU assay indicated that the Cu-bearing metals had obvious inhibitory effect on proliferation of VSMCs. Blood clotting and hemolysis tests showed that the Cu-bearing metals had good blood compatibility. The inhibition effect of the Cu-bearing metals on migration of cells was detected by Transwell assay. Further studies showed that Cu-bearing metals significantly decreased the mRNA expressions of bFGF, PDGF-B, HGF, Nrf2, GCLC, GCLM, NQO1 and HO1. The phosphorylation of AKT and Nrf2 protein expressions in VSMCs were significantly decreased by Cu-bearing metals. Furthermore, it was also found that SC79 and TBHQ treatments could recover the protein expressions of phospho-AKT and Nrf2, and their downstream proteins as well. Moreover, 316L-Cu stent proved its inhibitory action on the proliferation of VSMCs in vivo. In sum, the results demonstrated that the Cu-bearing metals possessed apparent inhibitory effect on proliferation and migration of VSMCs via regulating the AKT/Nrf2/ARE pathway, showing the Cu-bearing metals as promising stent materials for long-term efficacy of implantation.

Cardiovascular aging: spotlight on mitochondria

Mitochondria are cellular organelles critical for ATP production and are particularly relevant to cardiovascular diseases including heart failure, atherosclerosis, ischemia-reperfusion injury, and cardiomyopathies. With advancing age, even in the absence of clinical disease, mitochondrial homeostasis becomes disrupted (e.g., redox balance, mitochondrial DNA damage, oxidative metabolism, and mitochondrial quality control). Mitochondrial dysregulation leads to the accumulation of damaged and dysfunctional mitochondria, producing excessive reactive oxygen species and perpetuating mitochondrial dysfunction. In addition, mitochondrial DNA, cardiolipin, and N-formyl peptides are potent activators of cell-intrinsic and -extrinsic inflammatory pathways. These age-related mitochondrial changes contribute to the development of cardiovascular diseases. This review covers the impact of aging on mitochondria and links these mechanisms to therapeutic implications for age-associated cardiovascular diseases.

Transcription Factor NRF2 in Shaping Myeloid Cell Differentiation and Function

NFE2-related factor 2 (NRF2) is a master transcription factor (TF) that coordinates key cellular homeostatic processes including antioxidative responses, autophagy, proteostasis, and metabolism. The emerging evidence underscores its significant role in modulating inflammatory and immune processes. This chapter delves into the role of NRF2 in myeloid cell differentiation and function and its implication in myeloid cell-driven diseases. In macrophages, NRF2 modulates cytokine production, phagocytosis, pathogen clearance, and metabolic adaptations. In dendritic cells (DCs), it affects maturation, cytokine production, and antigen presentation capabilities, while in neutrophils, NRF2 is involved in activation, migration, cytokine production, and NETosis. The discussion extends to how NRF2's regulatory actions pertain to a wide array of diseases, such as sepsis, various infectious diseases, cancer, wound healing, atherosclerosis, hemolytic conditions, pulmonary disorders, hemorrhagic events, and autoimmune diseases. The activation of NRF2 typically reduces inflammation, thereby modifying disease outcomes. This highlights the therapeutic potential of NRF2 modulation in treating myeloid cell-driven pathologies.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

The significance of ERK5 catalytic-independent functions in disease pathways

Extracellular signal-regulated kinase 5 (ERK5), also known as BMK1 or MAPK7, represents a recent addition to the classical mitogen-activated protein kinase (MAPK) family. This family includes well-known members such as ERK1/2, c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK), as well as atypical MAPKs such as ERK3, ERK4, ERK7 (ERK8), and Nemo-like kinase (NLK). Comprehensive reviews available elsewhere provide detailed insights into ERK5, which interested readers can refer to for in-depth knowledge (Nithianandarajah-Jones et al., 2012; Monti et al., Cancers (Basel), 2022, 14). The primary aim of this review is to emphasize the essential characteristics of ERK5 and shed light on the intricate nature of its activation, with particular attention to the catalytic-independent functions in disease pathways.