Necrotic Endothelium in Atherosclerosis: Unravelling the Mechanisms of LDL Plaque-Induced Damage to The Tunica Intima in Arteries

Atherosclerosis is a chronic vascular disease, where lipids, inflammatory cells and fibrous matter are slowly deposited in the arterial wall, which particularly affects the tunica intima. This process results in the formation of atherosclerotic plaque, which can impede the flow of blood and increase the risk of cardiovascular problems such as heart disease and stroke. Balancing blood vessels is helped enough by the endothelium, which is a layer of cells found inside the blood vessels. Besides controlling blood flow, inflammation and thrombosis, it acts as an obstruction to the arterial wall. Endothelial dysfunction is a primary and important event in atherosclerosis, where the availability of nitric oxide decreases, oxidative stress increases, and the permeability of lipoprotein and inflammatory cells increases. These changes serve as the early stages of formation of atherosclerotic lesions. There is a complex interaction between cellular and molecular processes in advances of atherosclerosis. After oxidation, Low-Density Lipoprotein (LDL) enters the sub-endothelial layer of the particle artery wall and deposits there. This triggers an inflammatory response, resulting in monocytes and other immune cells being stored at that location. These monocytes become macrophages and are converted to foam cells by absorbing oxidized LDL. Foam cells, cell debris and extracellular lipid form the core of an atherosclerotic plaque. Over time, the plaque becomes large and forms a fibrous layer composed of smooth muscle cells and collagen in the centre of lipid enrichment. However, the durability of this coating is extremely important; if it bursts, a thrombus may form and may cause acute heart attack. Although the death of apoptosis or planned cell has long been recognized as an original mechanism of atherosclerosis, recent research highlights the importance of the pathway to necrotic cell death in the progression of disease. Necrosis was traditionally thought to be an uncontrolled process of cell death, but is now also seen as involving controlled pathways such as necroptosis and pyroptosis [1-3]. These processes play an important role in formation of plaque and in its instability. Necroptosis is a controlled necrosis process, which is controlled by the receptor-interacting protein kinase (RIP). It is stimulated by inflammable signals and breaks down the cell membrane, causing the material inside the cell to go out and increase inflammation. On the other hand, pyroptosis occurs through the activation of inflammatory cells, and it is associated with the cleavage of gaseous proteins, which form pores in the cell membrane and releases cytokines that cause inflammation. In the context of atherosclerosis, endothelial cells undergo the expansion of the necrotic core between the necrotic death and plaque, which is characterized by advanced stage lesions. The release of damage-related molecular patterns (DAMPs) from the necrotic cell results in increased inflammation and increased plaque progression and instability. Additionally, the death of uncontrolled cells weakens the endothelial barrier function, which facilitates the intrusion of excess lipid and immune cells into the arterial wall. It creates a vicious cycle of inflammation and tissue damage, which accelerates the disease further. Understanding the underlying mechanisms of necrotic cell death in atherosclerosis helps to identify potential therapeutic goals. Inhibiting pathways such as necroptosis or pyroptosis, it is possible to reduce the instability of plaque, which can prevent acute cardiovascular events. Additionally, strategies to improve endothelial function and reduce oxidative stress can prevent the onset and progression of atherosclerosis. Deep into the complex role of uncontrolled necrosis in the disease, scientists are trying to develop new types of therapeutic approaches to address both the root causes of atherosclerosis and its devastating consequences [4, 5].

Fig. 1. Structure of Human Artery

2. Endothelial Dysfunction: The Initial Trigger

2.1 Hemodynamic Forces and Endothelial Susceptibility

Spatial distribution of atherosclerotic lesions is closely connected to the cases of irritation in the bloodstream, especially in cases of double tension and curvature of the arteries, where hymodynamic energy is altered. These regions are subject to the oscillations of shear pressure, a type of mechanical force that disrupts normal blood flow patterns. Endothelial cells in this area exhibit significant morphological changes and enhanced permeability, making them more susceptible to damage. Research using advanced equipment such as microfluidic devices and counting models has revealed that patterns of disruptive flow play a significant role in the promotion of endothelial dysfunction, a primary event in the development of atherosclerosis. In particular, this abnormal flow condition increases the risk of low-density lipoprotein (LDL) through a number of mechanisms to damage endothelial cells. Firstly, the agents modulate the expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) on endothelial cells, Secondly, they activate inflammatory transcription factors like NF-KB and AP-1, which release inflammatory cytokines and chemokine. Third, they reduce the production of protective molecules such as nitric oxide (NO) and KLF2, which are necessary to maintain vascular homeostasis and anti - inflammatory reactions. Finally, the disruptive flow increases oxidative stress by increasing the activity of NADPH oxidation, an enzyme that produces reactive oxygen species (ROS) [6, 7]. These combined effects create a pro-atherogenic environment which encourages retention and alteration of LDL within the sub-endothelial space. Once LDL particles accumulate and oxidize, they cause an inflammatory response, attracting monocytes and other immune cells to the site. It begins to form fat lines and eventually forms mature atherosclerotic plaques. Understanding these processes highlight the important role of haemodynamic energy in shaping spatial distribution of atherosclerotic lesions, and point to the importance of targeting endothelial dysfunction in therapeutic techniques [8].

Fig. 2.  Haemodynamic Forces in Arteries

In straight arterial segments, sustained laminar flow generates physiological wall shear stress (WSS), maintaining endothelial cell (EC) quiescence and preserving the integrity of the endothelial glycocalyx (eGCX). This eGCX, composed of glycosaminoglycans (GAGs) such as heparan sulfate (HS), chondroitin sulfate (CS), hyaluronic acid (HA), and proteoglycans like syndecans (SDCs) and glypicans (GPCs), acts as a mechanotransducer and barrier. At arterial bifurcations, complex flow dynamics, including flow separation and recirculation, result in a heterogeneous WSS distribution. Specifically, regions of low and oscillatory WSS are observed at the outer walls and plaque shoulder regions, while elevated WSS occurs at the bifurcation apex or plaque throat. This spatial WSS gradient disrupts the eGCX, leading to its degradation and structural alteration. The resulting endothelial dysfunction is characterized by the activation of inflammatory signaling pathways, including those mediated by receptor tyrosine kinases (RTKs). These pathways promote the recruitment of inflammatory cells and contribute to the initiation and progression of atherosclerotic plaque formation.

2.2 Endothelial Permeability and LDL Transport

Interference of Low-density lipoprotein (LDL) through endothelium is an important process in transport vascular biology, which takes place through both trans-cellular and para-cellular pathways. Under normal physiological conditions, LDL cholesterol first enters the artery wall by attaching to specific receptors on the cells lining the blood vessel, then being moved across those cells, a process facilitated by LDL receptors and caveolins, which are small protestations in the cell membrane. This process ensures the controlled and controlled movement of LDL particles to the sub-endothelial space. However, in areas prone to atherosclerosis, the endothelial barrier is damaged, thereby increasing permeability and increasing flow of LDL [9, 10]. This pathological change is driven by a number of root factors including ZO-1 and Claudine, especially V-cadherin plays a crucial role in keeping our blood vessel linings strong and intact. In addition, cytoskeleton recombination in endothelial cells can induce cell compression, which creates gaps that allow LDL to pass more freely. Transcendental adds to the forming process of channels, which provide a direct path for LDL entry. Another contributing factor is the deterioration or dysfunction of endothelial glycocalyx, a protective layer of glycoproteins and proteoglycans that line the vascular lumen. When glycocalyx is compromised, the ability to resist LDL particles is reduced, to enter the vessel wall, LDL particles undergo modifications that allow them to slip through the endothelial lining and reach the sub-endothelial space. Once there, they bind to components of the extracellular matrix, particularly proteoglycans, through interactions with their negatively charged glycosaminoglycan chains. These interactions clog LDL particles, promote their retention and modification, which are the primary steps in the development of atherosclerotic plaques. This complex interplay of endothelial dysfunction, increased permeability, and retention of LDL indicates the importance of endothelial health in preventing vascular disease [11-13].

Fig. 3.  Endothelial permeability and LDL Transport

Two pathways of LDL (low-density lipoprotein) uptake by cells. On the left, the classical receptor-mediated endocytosis pathway shows LDL binding to LDLR (LDL receptor), followed by internalization into endosomes and eventual receptor recycling. On the right, the caveolae-mediated pathway demonstrates an alternative uptake mechanism involving caveolin-1, SR-B1 (scavenger receptor B1), and ALK1 (activin receptor-like kinase 1) proteins.The cell membrane is depicted with tight junctions, adherens junctions, and gap junctions maintaining cell-cell contacts. Pink circles represent other molecules (possibly cholesterol) being transported via paracellular pathways. The diagram effectively shows how LDL particles, which carry cholesterol, can enter cells through different mechanisms, highlighting the complexity of cholesterol transport and metabolism in cellular biology.

Table No. 1: Mechanisms of Endothelial Dysfunction and LDL Transport in Atherosclerosis

3. LDL Modification and Retention in the Tunica Intima

3.1 Oxidative Modification of LDL due to Mitochondrial Dysfunction:

Low-density lipoprotein (LDL) particles go through a significant change that sticks the arterial walls; the most intensively studied process is oxidation. Enzymatic and non-enzymatic processes cause these oxidative changes together. Active neutrophils and macrophages publish myeloperoxidase (MPO) that need to accelerate LDL oxidation. Leukocytes and endothelial cells publish lypoxygenase, which help in this process. Creates superoxide radicals, encourages reactive oxygen species—such as NADPH oxidase-produced-oxidase. LDL particles are also vary by reactive nitrogen species with peroxyntrite. Conversion metal ions such as iron and copper act as catalyst, accelerate lipid peroxidation process. Together, these processes form oxidized LDL (oxyLDL) that exhibits a variety of structural and functional changes. These changes affect both the lipid and protein components of LDL, resulting in a diverse group of modified particles. Recent advances in proteomic analysis have shown that it is possible to identify more than 100 oxidation-specific epitopes on apolipoprotein B-100, the main protein component of LDL. Many of these epitopes have inflammatory properties, which play an important role in the development of atherosclerosis.  Oxidation changes not only the physical and chemical properties of LDL, but also increases its recognition by scavenger receptors located in macrophages.  This results in the rapid formation of foam cells and the development of atherosclerotic plaques.  This complex interaction of oxidation processes highlights the important role of oxLDL in the progression of vascular inflammation and cardiovascular disease.Many of these epitopes have anti-inflammatory properties, which play an important role in the development of atherosclerosis [14-17].  Oxidation changes not only the physical and chemical properties of LDL, but also increases its recognition by scavenger receptors located in macrophages.  This results in the rapid formation of foam cells and the development of atherosclerotic plaques.  This complex interaction of oxidation processes highlights the important role of OxLDL in the progression of vascular inflammation and cardiovascular disease [18, 19].

Fig. 4.  Oxidative Modification of LDL due to Mitochondrial Dysfunction

Cellular stress pathways triggered by mitochondrial dysfunction, which relates directly to LDL oxidative modification. Mitochondrial dysfunction (left side) leads to increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), creating oxidative stress conditions. These reactive species can oxidatively modify LDL particles when present in the cell's environment.The bidirectional arrows between mitochondrial dysfunction and oxidative stress demonstrate their self-reinforcing relationship - mitochondrial damage increases ROS/RNS production, while oxidative stress further impairs mitochondrial function. This vicious cycle accelerates LDL oxidation in the cellular milieu. Oxidative stress also triggers endoplasmic reticulum (ER) stress, disrupts protein folding via PDI (protein disulfide isomerase) dysfunction, and promotes protein aggregation. Additionally, RNA dysmetabolism and stress granule formation occur, ultimately impairing axonal transport. These cascading consequences highlight how mitochondrial dysfunction not only drives LDL oxidation but also compromises overall cellular homeostasis, potentially relevant in atherosclerosis development where oxidized LDL plays a crucial pathogenic role.

3.2 Alternative LDL Modifications

Low-density lipoprotein (LDL) goes through multiple complex changes in the arterial wall, which also extends beyond oxidation, which significantly affects its biological behaviour and contributes to pathogenesis of atherosclerosis. An important change is glycation, which occurs both essential and non-excellent. This process is pronounced especially among people suffering from diabetes, where high glucose levels help form advanced glycation and products (AGE) in LDL particles. These glycated LDL molecules display modified structural and functional properties, which make them more ethogenic. In addition, LDL particles can go through merger and combination, resulting in larger, lipid-rich particles. These collective forms are more likely to be deposited in subandothealial places, which encourage the development of foam cell structure and plaque. Another significant change includes proteolytic degradation, which mediates by matrix metalloprotein (MMP) and other proteases. This degradation not only changes the physical structure of LDL, but also increases the ability to interact with extracellular matrix elements, which contributes more to the concept of arterial wall. Chronic kidney disease (CKD) is a non-initial change powered by Urea-designed cyanate in patients. Carbamylated LDL exhibits distinct biological chemical properties, including recognition reduced by classical LDL receptors and bonding with scavenger receptors, which increase its intake by macrophage and promote the formation of foam cells. Combined, these changes change the way LDL is recognized by glycation, consolidation, proteolytic degradation and Carbamylated -cellular receptor and significantly improve its inflammatory and cytotoxic effects. These changes not only accelerate the progress of atherosclerosis but also contribute to the instability of the atherosclerotic plaque, which increases the risk of acute cardiovascular event. These processes provide critical insights about the versatile role of LDL modified in vascular pathology [20, 21]

Fig. 5.  Alternative LDL Modifications

The complex lipid metabolism pathways and their modifications leading to atherosclerosis development. The liver produces both LDL and lipoprotein (a) (Lp(a)), with PELACARSEN targeting Lp(a) production. LDL particles undergo several modification processes including oxidation by lipoxygenase (LPO) and myeloperoxidase (MPO), glycation, and peroxidation by nitric oxide (NO), with ApoC-3 playing a key role. The AKCEA-ApoCIII-LRx therapy targets these modifications. Simultaneously, the liver produces angiopoietin-like protein 3 (ANGPTL3), which inhibits lipoprotein lipase (LPL) activity. Evinacumab blocks ANGPTL3, promoting triglyceride-rich lipoprotein (TRL) lipolysis. HDL, which typically facilitates reverse cholesterol transport (RCT), can become dysfunctional through post-translational modifications including oxidation, carbamylation, and glycation, with reduced activity of key proteins (LCAT, CETP, ApoM).  This diagram also emphasizes how these modified lipoproteins—dysfunctional HDL, Lp(a), TRL remnants, and modified LDL—all contribute to plaque formation in arterial walls, driving atherosclerosis progression. CSL112 represents a therapeutic approach to enhance RCT and potentially reverse this pathological process.

Table No. 2: LDL modification and retention processes in the tunica intima

4. Mechanisms of Modified LDL-Induced Endothelial Damage

4.1 Receptor-Mediated Recognition of Modified LDL

Modified low density lipoprotein (LDL) particles, especially Oxidized LDL (oxLDL), are characterized by various pattern recognition receptors present in endothelial cells. Among these, Lectin-like oxidized LDL receptor-1 (LOX-1) acts as the primary Endothelial Scavenger Receptor, which plays an important role in detection and interior of oxLDL. Additionally, Toll-like receptor (TLRs), especially TLR2 and TLR4, contribute to modified LDL particles detection. Other Scavenging receptors, such as CD36, participate in this process, as well as Fc Gamma receptor, which detects LDL-containing immune complexes. oxLDL’s boundaries with these receptors begin multiple intercellular signal pathways that combined lead to endothelial activation and under prolonged or additional stimuli, causing endothelial cell death.
Using endothelial-specific receptor knockout models have highlighted the central role of LOX-1 in the recent study of oxLDL-induced endothelial dysfunction and necrosis, especially in the early stages of atherosclerosis. These results highlight LOX-1’s importance in pathological progress of vascular disease, as its activation not only simplifies the taking of oxLDL but also encourages the release of pro-inflammatory cytokine and responsive oxygen species [22, 23]. These cascade of events further enhance endothelial injuries and contribute to the development of atherosclerotic wounds. The involvement of TLR and CD36 further increases inflammatory response, creating a response loop that adjusts endothelial damage. Combinely, these processes depict complex mutual action between LDL particles and endothelial receptors that have changed in the management of vascular pathology [24, 25].

Fig. 6.  Receptor-Mediated Recognition of Modified LDL:

The illustrated diagram provides a comprehensive depiction of receptor-mediated recognition of modified LDL in atherosclerosis pathogenesis. Native LDL particles containing ApoB100 undergo oxidative modification via dual pathways: an enzymatic route involving lipoxygenases and metalloproteinases, and a non-enzymatic process catalyzed by transition metal ions (Fe²?/Cu²?). This oxidation cascade, occurring predominantly within the subendothelial space, represents a critical initiating event in atherogenesis. The resultant mildly oxidized LDL (mmLDL) maintains affinity for the canonical LDL receptor (LDLR) while simultaneously exhibiting pro-inflammatory properties through recruitment of cytokines/chemokines and apoptotic signaling. With progressive oxidation, highly oxidized LDL (oxLDL) emerges, characterized by extensive modifications to its constituent phospholipids, triglycerides, cholesteryl esters, free cholesterol, and ApoB100 moieties. Significantly, oxLDL loses LDLR binding capacity (depicted by the red dashed line) and is instead recognized by scavenger receptors, particularly SR-B1 expressed on macrophages. The diagram accurately portrays oxLDL's pro-apoptotic properties and its activation of inflammatory transcription factors and receptors (NFκB, TNFR1, TNFR2). Macrophage internalization of oxLDL via these scavenger receptors proceeds in an unregulated manner, leading to intracellular lipid accumulation and subsequent transformation into foam cells—hallmark cellular components of atherosclerotic lesions. Throughout this pathological sequence, ApoB100 undergoes conformational changes that transition it from an LDLR ligand in native LDL to a recognition element for scavenger receptors in its oxidized state, thus playing a pivotal role in directing lipoprotein-cell interactions that drive atherosclerotic plaque formation.

4.2 Oxidative Stress and Mitochondrial Dysfunction

Modified low-density lipoprotein (LDL) particles play an important role in inducing oxidative stress within endothelial cells through several interconnected pathways [26]. A primary mechanism involves the activation of NADPH oxidases, specifically NOX2 and NOX4, which are major enzymatic sources of reactive oxygen species (ROS). These enzymes catalyze the reduction of molecular oxygen to superoxide ions, initiating a sequence of oxidative events. Additionally, modified LDL disrupts the mitochondrial electron transport chain, leading to electron leakage and further ROS production. This disruption is complicated by the dissociation of endothelial nitric oxide synthase (eNOS), which changes its function from producing nitric oxide (NO) a vasoprotective molecule to producing superoxide radicals. At the same time, modified LDL reduces important antioxidant defenses such as glutathione and thioredoxin, reducing the ability of cells to neutralize ROS and maintain redox balance. The accumulation of ROS as a result of these processes causes extensive oxidative damage to cellular components, to which mitochondria are particularly sensitive [27, 28]. The symptoms of mitochondrial breakdown vary among individuals. First, the mitochondrial membrane's capacity, which is equivalent to the angina's energy-generating capacity, significantly declines. Furthermore, structural modifications such as Atomic remodeling and fragmentation interfere with the electron transport series' effective configuration. In addition, mitochondrial DNA (mtDNA) is damaged, and its repair process is impaired, resulting in mutations and further dysfunction. As a result, ATP production is significantly reduced, depriving cells of the necessary energy. These mitochondrial changes also initiate the release of pro-death factors such as mitochrome c, which initiates the apoptotic pathway (see fig. No. 4). Collectively, these changes represent an important link between oxidative stress and endothelial cell death, highlighting the central role of mitochondrial dysfunction in the pathogenesis of endothelial damage introduced by altered LDL. The interaction of these processes characterizes the complexity of oxidative stress in intracellular cells and its contribution to the progression of vascular disease [29-30].

4.3 ER Stress and the Unfolded Protein Response

Modern resesearch ensures that at least the lipoprotein (LDL) endoplasmic reticulum (ER) endothelial cells, which is a precursor to vascular disease. This type of attack is triggered by a cellular unprotected system and unfolded protein attack (IPR). If the IPPR methodically detects cellular homeostasis, they can also detect the presence of a drug that is responsible for the development of endothelial cells. Modified LDL detects three pathological IPR sensor routes: PARK (Protein kinase ANN-based IPR kinase) IR1α (Inositol-requiring transmembrane kinase endoribonuclease-1α) and ATF6 (Transcription factor 6). The first one is the filtration of the encryptive start file 2α (eIF2α), which destroys the global protein count of the EIR protein load. Furthermore, AR1α ex-box binding protein 1 (XBP1) catalyzes the splicing of MRNA, which upgrades the protein fragment and gene associated with the protein, and cleaves a secreted transcription folder. First of all, IRE1α c-Jun an-terminal kinase (JNK) which is a protein and a complex associated with the adaptogenesis. ATF6, the attack pattern sensors, are activated in the system, where it is divided by the domain name of your cytoplasm, which is used to detect the intrinsic nature of the intrinsic network and to generate the intrinsic protein expression. When cells experience endoplasmic reticulum (ER) stress, potentially induced by LDL, the unfolded protein response (UPR) activates CHOP, a transcription factor that promotes apoptosis by regulating the expression of pro-apoptotic factors and decreasing anti-apoptotic protein levels. First of all, the second one which uses the IP address system, which locks the file system. So, this is what we do and this is what we do and this is what we do and this is what we do and this is what we do and this is what we do. Simply put, these threats introduce a lot of intrinsic value in the form of robotic and cryptic behavioural routes, cause virtual chaos and lead to filtration. The critical role of the social LDL-propagated IRP, IPR activation and endothelial cell multiplication mechanism of the reproductive system is to prevent the spread of the related vascular disease and to improve the quality of these processes in the future. These routes can serve as an interface to the other software programs that enable the ER to perform endothelial disinfection and its integrated functionality [31, 32].

Fig. 7.  ER Stress and the Unfolded Protein Response

The diagram illustrates the receptor-mediated recognition of modified LDL in atherosclerosis, demonstrating the progressive oxidation of LDL and subsequent cellular interactions that contribute to disease pathogenesis. Native LDL, containing apolipoprotein B100 (ApoB100), undergoes oxidative modification through two distinct pathways: enzymatic mechanisms involving lipoxygenase and metalloproteinase activity, and non-enzymatic processes mediated by transition metal ions (Fe²?/Cu²?). The resultant mildly oxidized LDL retains affinity for the LDL receptor (LDLR) but acquires pro-inflammatory properties, recruiting inflammatory cytokines/chemokines and exhibiting apoptotic characteristics. With continued oxidation, highly oxidized LDL (oxLDL) develops, characterized by extensive modifications of its phospholipids, triglycerides, cholesteryl esters, and free cholesterol components. Critically, oxLDL loses LDLR recognition and instead binds to scavenger receptors, notably SR-B1 expressed on macrophages. This receptor-mediated recognition facilitates unregulated uptake of oxLDL by macrophages, leading to intracellular lipid accumulation and foam cell transformation—a hallmark of atherosclerotic lesion development. The highly oxidized LDL exhibits pro-apoptotic properties and activates inflammatory signaling pathways via NFκB, TNFR1, and TNFR2, further exacerbating local inflammation and tissue damage. ApoB100 remains present throughout the oxidation continuum but undergoes structural modifications that alter its receptor recognition properties. This mechanistic progression from native LDL to increasingly oxidized derivatives, coupled with the transition from regulated LDLR-mediated uptake to unregulated scavenger receptor-mediated internalization, constitutes a fundamental pathological sequence in atherosclerotic plaque formation and progression.

Table No. 3: Mechanisms of Modified LDL-Induced Endothelial Damage

5. Modes of Endothelial Cell Death in Atherosclerosis

5.1 Necroptosis: Programmed Inflammatory Necrosis

Modern research states that the endoplasmic reticula (ER) gap in the circulating low density lipoprotein (LDL) endothelial cells, which is a process that occurs in the body of the vascular pathogen. This type of process is executed by a certain type of unprotected process, called Protein Processor (UPR). If the UPR method is what the ER system does to repair the cellular homeostasis, in the case of the TEXPER system and the directed processor is a very important part of the system, which is the core of the ER system. The following LDL proteins activate the UPR sensor path: PERK (protein-coding RNA), IRE1α (inositol-stimulating enzyme 1α), and ATF6 (transcription factor 6). PERK is the filename for the Protective Initiation File 2α (eIF2α), which protects the ER Protein Load. On the other hand, IRE1α, X-box bound protein 1 (XBP1) regulates the division of mRNA, a specialized transcription factor that regulates the protein fragmentation and the genes encoded by the inhibitor. In fact, IRE1α c-Jun encodes N-terminal linkage (JNK), which is a link between the stress response and the network. ATF6, an attack primary sensor, is installed on the front of the processor, where it is designed to detect the domain of your cytoplasmic, which is responsible for the processing of the ER and ER filtration proteins. So, when the ER stress is induced by the direct exposure of the circulating LDL, then the UPR is essentially a pro-automatic process [33, 34]. This process is called C / EBP homologous protonation (CHOP), a transcription factor that damages the anti-apoptotic protein and allows pro-apoptotic receptors to interact with the organism. In fact, the dedicated UPR processor uses the ER's type of home system, which in turn is the cytosol home system leakage. So, this is what is called a call sign and this is what is called a call and a call to the web directory operator. Simply put, these threats are called endothelial threats in the form of an automatic and encrypted method, which is used by the user and the operator. LDL-preformed ERAP, UPR processing and endothelial cells are the main components of these processes in the development and integration of various types of surgical and surgical procedures. These are the methods by which you can do the endothelial work and then you can implement the specific methodologies that can be used to address the ER problem [35, 36].

Fig. 8. Programmed Inflammatory Necrosis: a. TNF-α-induced Signaling Pathway

The upper panel depicts the initiation of necroptosis through the TNF-α/TNFR1 signaling axis. Upon TNF-α binding to TNFR1 at the cell membrane, a signaling cascade is triggered that recruits the adaptor protein TRADD, which forms a complex with RIP1 (receptor-interacting protein kinase 1) and cIAP (cellular inhibitor of apoptosis protein). This complex, known as Complex I, can activate the NF-κB pathway through RIP1 ubiquitination (Ub), promoting inflammatory responses. However, when caspase 8 is inhibited (as shown by "caspase 8 inhibitor"), the signaling shifts from apoptosis to necroptosis. This causes the formation of the necrosome, where RIP1 associates with RIP3 and FADD, leading to RIP1-RIP3 phosphorylation and activation. This molecular switch is critical in atherosclerotic lesions where caspase inhibition may occur due to oxidative stress or other inflammatory factors.

b. Execution Phase of Necroptosis The lower panel illustrates the downstream events following necrosome formation. Activated RIP1-RIP3 complex recruits and phosphorylates MLKL (mixed lineage kinase domain-like protein), which then translocates to the mitochondria. This interaction with PGAM5 (phosphoglycerate mutase family member 5) at the mitochondrial membrane leads to mitochondrial dysfunction. Simultaneously, phosphorylated MLKL triggers Drp1 (dynamin-related protein 1) phosphorylation at Ser637, promoting mitochondrial fission. These events collectively lead to mitochondrial fragmentation, membrane permeabilization, and ultimately necrotic cell death with the release of damage-associated molecular patterns (DAMPs).

5.2 Pyroptosis: Inflammasome-Mediated Cell Death

Pyropotosis is a highly inflammatory form of programmed cell death that mediates by activation of Caspes-1 or Caspes-11/4/5, due to the gasdermin-D's (GSDMD) cleavage and pro-inflammatory cytokines such as Interleukin-1 beta (IL-1 beta) and Interleukin-18 (IL-18) are different from other forms of cell death due to its role in increasing the lytic nature and inflammatory reactions. Emerging research highlights the involvement of pyroptosis in pathogenesis of atherosclerosis, especially through its effect on endothelial cells. Modified Low-Density lipoprotein (LDL) elements, especially oxidized phospholipids have been seen to activate NLRP3 inflammation in endothelial cells, which starts a cascade of inflammatory events. In addition, cholesterol crystal, which can enter the endothelial level, induce lysosomal damage, NLRP3 enhances inflammatory activation further. These processes contribute to endothelial dysfunction, which is an important primary step in atherosclerosis. The study identified gasdermin-D clivase in endothelial cells in advanced human atherosclerotic plaque, which indicates the relevance of pyropotosis in the progress of the disease. Testing evidence of murine models support this observation, as NLRP3 has shown to reduce the structure of endothelial-specific erased atherosclerotic plaque, which highlights the key role of endothelial pyroptosis in vascular inflammation. Pyroptic endothelial cells publish processed forms of damage-related molecular patterns (DAMP) and IL-1 beta and IL-18, which act as a powerful intermediary of inflammation [37, 38]. These cytokines increase leukocytes recruitment on the vascular wall, permanent a cycle of inflammation and endothelial injury. The release of IL-1 beta and IL-18 also encourages the activation of neighbouring cells, including macrophase and smooth muscle cells, further enhancing the development and instability of the plaque. However, these findings indicate the critical role of pyropotosis in the dysfunction of endothelial cells and its contribution to the inflammatory environment that drives atherosclerosis. The underlying molecular processes of pyroptosis in endothelial cells can provide fancy therapeutic targets to mitigate vascular inflammation and reduce the burden of atherosclerotic cardiovascular disease [39, 40].

Fig. 9. Inflammasome-Mediated Cell Death

The diagram depicts the molecular mechanisms of inflammasome-mediated pyroptosis, a specialized form of programmed inflammatory cell death. In the canonical pathway, cellular sensors recognize PAMPs (Pathogen-Associated Molecular Patterns) and DAMPs (Damage-Associated Molecular Patterns) via PRRs (Pattern Recognition Receptors), initiating the assembly of a multiprotein complex comprising PRR, ASC adaptor proteins, and pro-caspase-1—collectively termed the inflammasome. Upon assembly, this platform facilitates the autocatalytic activation of caspase-1, which subsequently cleaves pro-IL-1β and pro-IL-18 into their bioactive forms while concurrently processing GSDMD (Gasdermin D) to liberate its pore-forming N-terminal domain. Complementarily, the non-canonical pathway is triggered by intracellular LPS from gram-negative bacteria, directly activating inflammatory caspases (caspase-4/5 in humans, caspase-11 in mice), which similarly cleave GSDMD. This pathway additionally induces pannexin-1 channel opening, mediating ATP release into the extracellular milieu, where it activates P2X7 purinergic receptors, facilitating potassium efflux. The resultant ionic imbalance triggers NLRP3 inflammasome assembly, creating a feed-forward amplification loop for caspase-1 activation. The execution phase converges on the oligomerization of GSDMD N-terminal fragments, which form transmembrane pores in the plasma membrane. These pores serve as conduits for the extracellular release of mature IL-1β and IL-18 while simultaneously compromising membrane integrity, leading to osmotic cell swelling, cytoplasmic content release, and ultimately pyroptotic cell death characterized by the extrusion of inflammatory mediators. This coordinated molecular cascade represents a critical immunological mechanism linking cellular death to inflammatory signaling in diverse pathological contexts.

5.3 Ferroptosis: Iron-Dependent Lipid Peroxidation

Ferropotosis is a form of controlled cell death that is separated by iron-dependent storage in lipid hydroperoxide toxic doses, which lead to cell death. Emerging evidence suggests an important role in the pathogenesis of the pathogenesis of the atherosclerotic endothelial injury. The main observations that support this relationship include the presence of high iron deposit in the atherosclerotic plaque, which can accelerate the production of reactive oxygen species (ROS) through fenton reaction. Also, glutathione peroxidase 4 (GPX4), an important enzyme that reduces lipid peroxidation, significantly reduces endothelial cells of these plaques. This deficit disrupts the ability to neutralize cell’s peroxide, enhances oxidative stress. In addition, atherosclerotic lesions display oxidized Phosphatidylserine storage, especially those who contain arachidonic acid, which is highly sensitive to peroxidation and act as biomarker of ferropotosis. Experimental studies have shown that pharmacological resistance to ferropotosis provides protective effects on animal models of atherosclerosis, indicating its pathological relevance. Modified Low-density is associated with lipoprotein (LDL) particles, especially oxidized LDL, promoting the death of ferroptotic cells in endothelial cells. These modified LDL particles contribute to ferropotosis by reducing intracellular glutathione, which is an important antioxidant that supports GPX4 activities. The inactivity of GPX4 further disrupts the balance of cellular redox, resulting in uncontrolled lipid peroxidation. In addition, modified LDL particles increase the labile iron pool in cells, which increases iron-dependent oxidative damage. Although modified LDL is interpreted incompletely by precise processes, it is estimated that they are associated with the iron metabolism and the increased intake of iron-loaded LDL by endothelial cells. Therefore, these processes create a pro-ferroptotic environment that enhances endothelial dysfunction and contributes to the progress of atherosclerosis. Understanding the underlying molecular pathways of ferroptosis in atherosclerosis can mitigate endothelial damage and provide fancy therapeutic targets to prevent the progress of cardiovascular disease [41, 42].

Fig. 10. Iron-Dependent Lipid Peroxidation:

The diagram comprehensively illustrates the molecular mechanisms underlying ferroptosis, a form of regulated cell death characterized by iron-dependent lipid peroxidation. Centrally positioned, Fe²? serves as the critical catalyst for lipid reactive oxygen species (ROS) generation via the Fenton reaction. Iron homeostasis is depicted through multiple regulatory pathways: transferrin-bound Fe³? enters cells via transferrin receptor 1, undergoes reduction to Fe²?, and is either stored in ferritin or metabolically utilized. NCOA4-mediated ferritinophagy releases stored iron through autophagic degradation, while iron regulatory proteins like IREB2 modulate iron metabolism at the transcriptional level. The right side illustrates the system Xc- antiporter (composed of SLC3A2 and SLC7A11), which imports cystine in exchange for glutamate. Intracellular cystine is reduced to cysteine and subsequently incorporated into glutathione (GSH) through γ-glutamylcysteine synthetase (γ-GCS). GSH serves as a critical cofactor for glutathione peroxidase 4 (GPX4), which detoxifies lipid hydroperoxides (PUFAs-OOH) to non-toxic lipid alcohols (PUFAs-OH). The bottom portion depicts how polyunsaturated fatty acids (PUFAs) within membrane phospholipids are susceptible to peroxidation by lipoxygenases (LOXs), generating lipid hydroperoxides. When the GPX4-dependent detoxification system is compromised, these hydroperoxides accumulate and propagate in a free radical chain reaction catalyzed by Fe²?, culminating in ferroptotic cell death. The diagram also indicates key pharmacological modulators: erastin and sorafenib inhibit system Xc-, BSO inhibits γ-GCS, and (1S,3R)-RSL3 inhibits GPX4, all promoting ferroptosis by compromising the cell's antioxidant defenses. HSPB1 is shown as a protective factor against Fe²?-mediated damage, while PHKG2 promotes iron availability. This schematic effectively captures the intricate interplay between iron metabolism, lipid peroxidation, and antioxidant defense systems that collectively determine cellular susceptibility to ferroptosis.

Table No. 4: Modes of Endothelial Cell Death in Atherosclerosis

6. Consequences of Endothelial Necrosis in Atherosclerosis Progression

6.1 Endothelial Denudation and Thrombosis

The necrotic death of endothelial cells leads to the local degradation of the arterial surface, which exposes the underlying sub-endothelial matrix elements to circulate blood. This exposure triggers a cascade of instant pathophysiological reactions. Platelets interact with and become active in and active with open collagen and von Willbrand factor, the key components of sub-endothelial matrix. At the same time, Thrombin production begins through the way of tissue factor, which is an important process of freezing. The Microthrombi structure occurs, which can either be immobilized in remote vascular beds or incorporated into developing placing. In addition, active platelets reveal the reasons for growth, such as the platelet-derived growth factor (PDGF) that stimulate the transfer and expansion of vascular smooth muscle cells, contribute to the progress and rebuilding of the plate. Endothelial denudation range and subsequent thrombotic complexity are administered by dynamic balance between endothelial repair process and ongoing injury. Endothelial repair involves the spread and transfer of endothelial cells adjacent to recruit and segregation of endothelial cells as well as the integrity of vascular lining. However, when endothelial injury rate exceeds the repair capacity, the permanent denudation of sub-endothelial matrix and thrombogenic exposure vascular pathology further enhances. This imbalance can lead to progress in atherosclerotic lesions, increase the risk of atherosclerotic and potentially intense vascular events such as myocardial infarction or stroke. Thus, mutual action between endothelial damage and repair methods is an important determinant of the progress of vascular health and disease [43, 44].

Fig. 11. Endothelial Denudation and Thrombosis

This diagram illustrates the process of endothelial denudation and thrombosis in atherosclerosis. Upon laser-induced injury to the blood vessel wall, endothelial activation occurs, which is a critical early event in atherosclerosis development. This activation leads to the expression of tissue factor (TF), which initiates the coagulation cascade. The coagulation process results in thrombus formation (thrombosis) at the site of endothelial damage. In the lower portion of the diagram, we can see the molecular mediators involved in this process, including tissue factor (TF), COX-2 (cyclooxygenase-2), ICAM-1 (intercellular adhesion molecule 1), and TNF-α (tumor necrosis factor alpha), which are upregulated following endothelial damage. The presence of SIRT1 (sirtuin 1) on the left side suggests its potential protective role in regulating endothelial function. This process of endothelial denudation (loss of endothelial cells) creates a prothrombotic environment that contributes to atherosclerotic plaque progression and potential complications such as plaque rupture and subsequent thrombotic events, which are major causes of adverse cardiovascular events including heart attacks and strokes.

6.2 Enhanced Inflammatory Cell Recruitment

Necrotic endothelial cells play an important role in the growth of inflammatory reactions by expressing Damage-Related Molecular Patterns (DAMP) that signal cellular injury. Released DAMP-s include High-Mobility Group Box 1 (HMGB1) A nuclear protein that acts as pro-inflammatory cytokine if extracellular; Adenosine Triphosphate (ATP) and other nucleotides, which act as signal molecules to activate immune cells; when mitochondrial DNA, which includes unmethylated CpG motifs, is released from damaged cells, it can stimulate an inflammatory response. This occurs because Toll-like receptor 9 (TLR9) recognizes these unmethylated CpG motifs. While histones and nucleosomes are essential for chromatin structure, they are distinct from the mitochondrial DNA and are not directly recognized by TLR9.; hit shock protein (HSP) which is molecular chaperones that can trigger immune response; and interleukin-1 alpha (IL-1α) is a powerful pro-inflammatory cytokine. These DAMPs interact with pattern recognition receptors (PRR) such as toll-like receptors (TLR) and NOD-like receptors (NLR) that are published in neighbouring endothelial cells and leukocytes. This interaction starts downstream signalling cascade which further enhances inflammatory response, resulting in additional immune cell recruitment and activate. When cells lining our blood vessels die in an uncontrolled way, they release alarm signals called DAMPs. These signals do two harmful things: first, they keep inflammation going, making it last longer. Second, they damage the blood vessel lining itself, making it work poorly. One of the main consequences of endothelial cell necrosis is to disrupt endothelial obstacles, which usually control the passage of molecules and cells between blood flow and surrounding tissues. The damage to the integrity of the barrier facilitates the increased transfer of monocyte in sub-endothelial space. Once in this place, monocytes are divided into macrophase and oxidized low-density lipoprotein (oxLDL) is a process that converts them into foam cells. Foam cells are a feature of the formation of atherosclerotic plaque and contribute to the progress of vascular inflammation and disease. The savings of foam cells in sub-endothelial space further enhances endothelial dysfunction, which creates a wicked cycle of inflammation and tissue damage. The role of DAMP in this process is versatile. For example, HMGB1, Once released, Advanced Glycation and Products (RAGe) and T. L. R is bound with receptors, which trigger the production of pro-inflammatory cytokine and chemokine. Similarly, Extracellular ATP activates purinergic receptors such as P2 X7, which leads to inflammatory structure and release of the next IL-1 beta, another powerful inflammatory intermediary. Mitochondrial DNA, with its non-methylated CPG motif, is recognized by TLR9, which further drives inflammatory response. The histones, when released externally, can directly damage endothelial cells and promote thrombosis, while hit shock protein and IL-1α endothelial cells and leukocytes, adjusting inflammatory cascade [45- 48].

6.3 Impaired Endothelial Regeneration

Atherosclerosis is characterized by a significant weakness of the reproduction of endothelium, which is driven by multiple interrelated processes. An important reason is the reduced availability and effective fall of conventional endothelial breeding cells (EPC) that plays an important role in endothelial repair and maintenance. These reproductive cells are necessary to re-fill the damaged endothelial cells and maintain vascular homeostasis; however, prevent their reduced number and weak functionality in atherosclerosis and the ability to effectively reproduce endothelium. Also, the cells lining our blood vessels experience changes over time, and this aging process is sped up by the shortening of their protective caps (telomeres) and ongoing damage from harmful molecules (oxidative stress). Telomere summarization, a feature of aging, limiting the possibility of replication of endothelial cells, while on the other hand intensifies by risk factors such as oxidative stress, high blood pressure and hyperlipidaemia, which contributes more to cellular dysfunction and aging. These aged cells, rather than helping repair blood vessel linings, actually hinder their healing and create an environment that promotes inflammation and plaque accumulate in arteries. Epigenetic changes further enhance endothelial dysfunction by changing important gene expression patterns for cell expansion and repair. These changes, including DNA methylation and histone acetylation, can silence the genes involved in the progress and survival of endothelial cell cycle, which inhibits their reproductive potential. Moreover, endothelium of atherosclerosis is constantly in contact with cytotoxic modified lipoprotein, such as oxidized low-density lipoprotein (oxLDL) [49, 50]. These lipoproteins induce endothelial injury, encourage apoptosis and damage the effective integrity of endothelial cells. The growing effect of these processes is compromised ability to restore endothelial continuity, which leads to permanent endothelial down regulation and dysfunction. Inadequate endothelial repair encourages an inflammatory microenvironment, which is characterized by increased adhesive molecule expression, leukocytes recruitment and cytokine release. This chronic inflammatory condition lasts endothelial injury and encourages the development and progress of the atherosclerotic plaque. In addition, interrupted endothelial obstacle facilitates the penetration of lipoprotein and immune cells in the arteries, accelerates the structure and instability of the plaque. Thus, the reproductive ability of endothelium in atherosclerosis not only contributes to the beginning and progress of vascular wounds, but also the importance of developing therapeutic techniques aimed at increasing endothelial repair process to reduce the severity of the disease [51, 52].

Fig. 12. Enhanced Inflammatory Cell Recruitment

This diagram comprehensively illustrates the progression of endothelial dysfunction and impaired regeneration during atherosclerosis. Beginning with healthy endothelium (left), characterized by intact endothelial cells (EC) and smooth muscle cells (SMC), the diagram shows the transition to inflammation where adhesion molecules (ICAM1, VCAM1) are upregulated, facilitating leukocyte attachment and infiltration. A critical metabolic alteration known as the Warburg effect emerges in dysfunctional endothelial cells, shifting energy production from efficient aerobic respiration toward glycolysis despite oxygen availability, producing excess lactate. This metabolic reprogramming compromises endothelial regenerative capacity by limiting energy available for repair processes. The vessel undergoes vascular remodeling with increased expression of CD31 and α-SMA, indicating endothelial-to-mesenchymal transition (EndoMT) where endothelial cells adopt a mesenchymal phenotype, further impairing their regenerative function. Oxidative stress, shown by increased reactive oxygen species (ROS) and reactive nitrogen species (RNS), damages cellular components and inhibits endothelial progenitor cell activity essential for regeneration. The culmination is a dysfunctional endothelium (right) with accumulated macrophages (MC), transformed smooth muscle cells, and persistent leukocyte infiltration, creating a vasoconstrictive environment resistant to normal regenerative processes. This pathological cascade demonstrates how atherosclerosis progressively undermines the endothelium's innate regenerative capabilities through metabolic, inflammatory, and phenotypic alterations.

Table No. 5: Consequences of Endothelial Necrosis in Atherosclerosis Progression