Sterol O-acyltransferase (SOAT/ACAT) activity is required to form cholesterol crystals in hepatocyte lipid droplets

OBJECTIVE

Excess cholesterol storage can induce the formation of cholesterol crystals in hepatocyte lipid droplets. Such crystals distinguish metabolic dysfunction associated steatohepatitis (MASH) from simple steatosis and may underlie its pathogenesis by causing cell damage that triggers liver inflammation. The mechanism linking cholesterol excess to its crystallization in lipid droplets is unclear. As cholesteryl esters localize to and accumulate in lipid droplets more readily than unesterified free cholesterol, we investigated whether cholesterol esterification by sterol O-acyltransferase (SOAT), also known as acyl co-A cholesterol acyltransferase (ACAT), is required for hepatocyte lipid droplet crystal formation.

METHOD

Cholesterol crystals were measured in cholesterol loaded Hep3B hepatocytes, RAW264.7 macrophages, and mouse liver using polarizing light microscopy. We examined the effect of blocking SOAT activity on crystal formation and compared these results to features of cholesterol metabolism and the progression to intracellular crystal deposits.

RESULTS

Cholesterol loading of Hep3B cells caused robust levels of lipid droplet localized crystal formation in a dose- and time-dependent manner. Co-treatment with SOAT inhibitors and genetic ablation of SOAT1 blocked crystal formation. SOAT inhibitor also blocked crystal formation in low density lipoprotein (LDL) treated Hep3B cells, acetylated LDL treated RAW 264.7 macrophages, and in the liver of mice genetically predisposed to hepatic cholesterol overload and in mice with cholesterol enriched diet-induced MASH.

CONCLUSION

SOAT1-mediated esterification may underlie cholesterol crystals associated with MASH by concentrating it in lipid droplets. These findings imply that inhibiting hepatocyte SOAT1 may be able to alleviate cholesterol associated MASH. Moreover, that either a lipid droplet localized cholesteryl ester hydrolase is required for cholesterol crystal formation, or the crystals are composed of cholesteryl ester.

The effect of colchicine on cholesterol crystal formation, expansion and morphology: a potential mechanism in atherosclerosis

Background

Inflammation is pivotal to the progression of atherosclerosis. Cholesterol crystals (CCs) that grow and enlarge within the plaque core can cause plaque rupture and trigger inflammation as they deposit into the atherosclerotic bed. Thus, agents that affect CC formation, expansion, and morphology may reduce cardiovascular (CV) risk independent of lipid-lowering and anti-inflammatory therapy.

Objective

Because colchicine is highly concentrated in leukocytes that can enter the atherosclerotic plaque core, we tested its effect on the formation and growth of CCs in bench experiments to determine whether it may have direct effects on CCs, independent of its known anti-inflammatory actions.

Method

Different dosages of colchicine mixed with cholesterol (0.05-5 mg/ml/g of cholesterol) were used to influence the formation CCs and volume expansion in vitro. These were compared to control samples with cholesterol in ddH2O without colchicine. In an ex vivo study, fresh atherosclerotic human plaques were incubated with and without colchicine in a water bath at 37°C for 48 h to assess the impact of colchicine on CC morphology. Scanning electron microscopy (SEM) was utilized to analyze CC morphology in samples from the various treatment groups.

Results

The addition of colchicine to cholesterol caused a substantial dose-dependent reduction in volume (p < 0.05). Pairwise comparisons of volume reduction, showed a significant reduction in volume at 5 mg/ml/g when compared to control (p < 0.02) but the calculated Cohen's d effect size was large for five of the six pairwise comparisons. By SEM, CCs from both in vitro and ex vivo samples treated with colchicine had evidence of dissolution and changes in their morphology as evidenced by the loss of their sharp edges. In contrast, CCs in untreated specimens retained their typical geometric structure.

Conclusions

Colchicine can reduce CC formation and expansion and alter CC morphology. These previously unappreciated effects of colchicine may contribute to its clinical benefit in patients with CV disease independent of its anti-inflammatory effects.

Cholesterol crystals induce mechanical trauma, inflammation, and neo-vascularization in solid cancers as in atherosclerosis

Background and aims

Cancer and atherosclerosis share common risk factors and inflammatory pathways that promote their proliferation via vascular endothelial growth factor (VEGF). Because CCs cause mechanical injury and inflammation in atherosclerosis, we investigated their presence in solid cancers and their activation of IL-1β, VEGF, CD44, and Ubiquityl-Histone H2B (Ub-H2B), that promote cancer growth.

Methods

Tumor specimens from eleven different types of human cancers and atherosclerotic plaques were assessed for CCs, free cholesterol content and IL1-β by microscopy, immunohistochemistry, and biochemical analysis. Breast and colon cancer cell lines were cultured with and without CCs to select for expression of VEGF, CD44, and Ub-H2B. Western blot and immunofluorescence were performed on cells to assess the effect of CCs on signaling pathways.

Results

Cancers displayed higher CC content (+2.29 ± 0.74 vs +1.46 ± 0.84, p < 0.0001), distribution (5.06 ± 3.13 vs 2.86 ± 2.18, p < 0.001) and free cholesterol (3.63 ± 4.02 vs 1.52 ± 0.56 μg/mg, p < 0.01) than cancer free marginal tissues and similarly for atherosclerotic plaques and margins (+2.31 ± 0.51 vs +1.44 ± 0.79, p < 0.02; 14.0 ± 5.74 vs 8.14 ± 5.52, p < 0.03; 0.19 ± 0.14 vs 0.09 ± 0.04 μg/mg, p < 0.02) respectively. Cancers displayed significantly increased expression of IL1-β compared to marginal tissues. CCs treated cancer cells had increased expression of VEGF, CD44, and Ub-H2B compared to control. By microscopy, CCs were found perforating cancer tumors similar to plaque rupture.

Conclusions

These findings suggest that CCs can induce trauma and activate cytokines that enhance cancer growth as in atherosclerosis.

Examining atherosclerotic lesions in three dimensions at the nanometer scale with cryo-FIB-SEM

We employed in a correlative manner an unconventional combination of methods, comprising cathodoluminescence, cryo-scanning electron microscopy (SEM), and cryo-focused ion beam (FIB)-SEM, to examine the volumes of thousands of cubed micrometers from rabbit atherosclerotic tissues, maintained in close-to-native conditions, with a resolution of tens of nanometers. Data from three different intralesional regions, at the media-lesion interface, in the core, and toward the lumen, were analyzed following segmentation and volume or surface representation. The media-lesion interface region is rich in cells and lipid droplets, whereas the core region is markedly richer in crystals and has lower cell density. In the three regions, thin crystals appear to be associated with intracellular or extracellular lipid droplets and multilamellar bodies. Large crystals are independently positioned in the tissue, not associated with specific cellular components. This extensive evidence strongly supports the idea that the lipid droplet surfaces and the outer membranes of multilamellar bodies play a role in cholesterol crystal nucleation and growth and that crystal formation occurs, in part, inside cells. The correlative combination of methods that allowed the direct examination of cholesterol crystals and lipid deposits in the atherosclerotic lesions may be similarly used for high-resolution examination of other tissues containing pathological or physiological cholesterol deposits.

Birefringent Crystals Deposition and Inflammasome Expression in Human Atheroma Plaques by Levels of Uricemia

OBJECTIVE

To verify the monosodium urate (MSU) crystal deposition in artery walls following a structure assessment and to assess NLRP3 inflammasome expression in human atheroma plaques by levels of uricemia.

METHODS

Patients with peripheral arterial disease who were candidates for amputation were recruited and classified as normouricemic or hyperuricemic. During surgery, an artery segment from the amputated limb was sampled, divided and fixed separately by cryo-embedding, 100% ethanol or Glyo-fixx. Samples were assessed by compensated polarized-light microscopy to identify MSU crystals on the artery walls. Afterwards, macrophages, neutrophils and NLRP3 inflammasome components at the plaque were categorized by immunostaining and compared between normouricemics and hyperuricemics.

RESULTS

Thirty artery samples from 27 patients were studied; 10 (37.0%) participants were hyperuricemic. Birefringent needle-shaped crystals were found in three samples (10.0%), all processed by frozen sectioning. Other methods showed no crystals. No accompanying inflammatory process was noted, and the presence of crystals was equally distributed across ranges of uricemia, making it unlikely they were MSU crystals. Regarding immunostaining, 28 artery samples were available for analysis, with similar infiltration of macrophages and neutrophils. NLRP3 and gasdermin-D expression were significantly greater in hyperuricemics compared to normouricemics (p=0.044 and p=0.017, respectively). ASC content was numerically larger in hyperuricemics as well, while caspase-1 and IL-1beta expression were similar between groups.

CONCLUSIONS

The presence of MSU crystals on artery walls was not confirmed. Hyperuricemia was associated with greater NLRP3 and gasdermin-D expression on human atheroma plaques in patients with peripheral artery disease.

Pathophysiology of Atherosclerosis

Atherosclerosis is the main risk factor for cardiovascular disease (CVD), which is the leading cause of mortality worldwide. Atherosclerosis is initiated by endothelium activation and, followed by a cascade of events (accumulation of lipids, fibrous elements, and calcification), triggers the vessel narrowing and activation of inflammatory pathways. The resultant atheroma plaque, along with these processes, results in cardiovascular complications. This review focuses on the different stages of atherosclerosis development, ranging from endothelial dysfunction to plaque rupture. In addition, the post-transcriptional regulation and modulation of atheroma plaque by microRNAs and lncRNAs, the role of microbiota, and the importance of sex as a crucial risk factor in atherosclerosis are covered here in order to provide a global view of the disease.

Effect of aspirin on cholesterol crystallization: A potential mechanism for plaque stabilization

Background and aims

Cholesterol crystals (CCs) have been found to be critical in the evolution and progression of atherosclerotic plaque leading up to rupture. This includes triggering inflammation and mechanically traumatizing the plaque and surrounding tissues. Thus, inhibition of crystal formation and degrading the crystals could be an important therapeutic approach in the prevention of cardiovascular events. Because of its physico-chemical properties we examined the effect of aspirin (ASA) on cholesterol crystallization.

Methods

A first experiment tested three amounts of cholesterol (1, 2, 3 g) with a wide range of ASA (0-60 mg) on cholesterol crystallization and volume expansion. A second experiment tested the effect of CCs with and without ASA in perforation of fibrous membrane during crystallization. A third experiment evaluated the effect of ASA on melting CCs in human atherosclerotic plaques. Scanning electron microscopy (SEM) was used to evaluate crystal morphology.

Results

Aspirin significantly inhibited cholesterol crystallization and volume expansion in a dose related fashion and even at physiologic levels (0.3 mg/ml). Moreover, ASA prevented perforation of fibrous membranes. By SEM, crystals in human atherosclerotic plaques were found melted with ASA.

Conclusions

Cholesterol volume expansion during crystallization was significantly inhibited and CCs were dissolved in the presence of ASA. Fibrous membranes were not perforated with ASA because of both these effects.

Formation and Cellular Impact of Cholesterol Crystals in Health and Disease

Cholesterol crystals (CCs) were first discovered in atherosclerotic plaque tissue in the early 1900 and have since been observed and implicated in many diseases and conditions, including myocardial infarction, abdominal aortic aneurism, kidney disease, ocular diseases, and even central nervous system anomalies. Despite the widespread involvement of CCs in many pathologies, the mechanisms involved in their formation and their role in various diseases are still not fully understood. Current knowledge concerning the formation of CCs, as well as the molecular pathways activated upon cellular exposure to CCs, will be explored in this review. As CC formation is tightly associated with lipid metabolism, the role of cellular lipid homeostasis in the formation of CCs is highlighted, including the role of lysosomes. In addition, cellular pathways and processes known to be affected by CCs are described. In particular, CC-induced activation of the inflammasome and production of reactive oxygen species, along with the role of CCs in complement-mediated inflammation is discussed. Moreover, the clinical manifestation of embolized CCs is described with a focus on renal and skin diseases associated with CC embolism. Lastly, potential therapeutic measures that target either the formation of CCs or their impact on different cell types and tissues are highlighted.

Cholesterol Crystals and NLRP3 Mediated Inflammation in the Uterine Wall Decidua in Normal and Preeclamptic Pregnancies

Preeclampsia is a hypertensive and inflammatory pregnancy disorder associated with cholesterol accumulation and inflammation at the maternal-fetal interface. Preeclampsia can be complicated with fetal growth restriction (FGR) and shares risk factors and pathophysiological mechanisms with cardiovascular disease. Cholesterol crystal mediated NLRP3 inflammasome activation is central to cardiovascular disease and the pathway has been implicated in placental inflammation in preeclampsia. Direct maternal-fetal interaction occurs both in the uterine wall decidua and at the placental surface and these aligned sites constitute the maternal-fetal interface. This study aimed to investigate cholesterol crystal accumulation and NLRP3 inflammasome expression by maternal and fetal cells in the uterine wall decidua of normal and preeclamptic pregnancies. Pregnant women with normal (n = 43) and preeclamptic pregnancies with (n = 28) and without (n = 19) FGR were included at delivery. Cholesterol crystals were imaged in decidual tissue by both second harmonic generation microscopy and polarization filter reflected light microscopy. Quantitative expression analysis of NLRP3, IL-1β and cell markers was performed by immunohistochemistry and automated image processing. Functional NLRP3 activation was assessed in cultured decidual explants. Cholesterol crystals were identified in decidual tissue, both in the tissue stroma and near uterine vessels. The cholesterol crystals in decidua varied between pregnancies in distribution and cluster size. Decidual expression of the inflammasome components NLRP3 and IL-1β was located to fetal trophoblasts and maternal leukocytes and was strongest in areas of proximity between these cell types. Pathway functionality was confirmed by cholesterol crystal activation of IL-1β in cultured decidual explants. Preeclampsia without FGR was associated with increased trophoblast dependent NLRP3 and IL-1β expression, particularly in the decidual areas of trophoblast and leukocyte proximity. Our findings suggest that decidual accumulation of cholesterol crystals may activate the NLRP3 inflammasome and contribute to decidual inflammation and that this pathway is strengthened in areas with close maternal-fetal interaction in preeclampsia without FGR.

Cholesterol induced heart valve inflammation and injury: efficacy of cholesterol lowering treatment

BACKGROUND

Heart valves often undergo a degenerative process leading to mechanical dysfunction that requires valve replacement. This process has been compared with atherosclerosis because of shared pathology and risk factors. In this study, we aimed to elucidate the role of inflammation triggered by cholesterol infiltration and cholesterol crystals formation causing mechanical and biochemical injury in heart valves.

METHODS

Human and atherosclerotic rabbit heart valves were evaluated. New Zealand White male rabbits were fed an enriched cholesterol diet alone or with simvastatin and ezetimibe simultaneous or after 6 months of initiating cholesterol diet. Inflammation was measured using C-reactive protein (CRP) and RAM 11 of tissue macrophage content. Cholesterol crystal presence and content in valves was evaluated using scanning electron microscopy.

RESULTS

Cholesterol diet alone induced cholesterol infiltration of valves with associated increased inflammation. Tissue cholesterol, CRP levels and RAM 11 were significantly lower in simvastatin and ezetimibe rabbit groups compared with cholesterol diet alone. However, the treatment was effective only when initiated with a cholesterol diet but not after lipid infiltration in valves. Aortic valve cholesterol content was significantly greater than all other cardiac valves. Extensive amounts of cholesterol crystals were noted in rabbit valves on cholesterol diet and in diseased human valves.

CONCLUSIONS

Prevention of valve infiltration with cholesterol and reduced inflammation by simvastatin and ezetimibe was effective only when given during the initiation of high cholesterol diet but was not effective when given following infiltration of cholesterol into the valve matrix.

Cholesterol Crystals Induce Coagulation Activation through Complement-Dependent Expression of Monocytic Tissue Factor

Cholesterol crystals (CC) are strong activators of complement and could potentially be involved in thromboinflammation through complement-coagulation cross-talk. To explore the coagulation-inducing potential of CC, we performed studies in lepirudin-based human whole blood and plasma models. In addition, immunohistological examinations of brain thrombi and vulnerable plaque material from patients with advanced carotid atherosclerosis were performed using polarization filter reflected light microscopy to identify CC. In whole blood, CC exposure induced a time- and concentration-dependent generation of prothrombin fragment 1+2 (PTF1.2), tissue factor (TF) mRNA synthesis, and monocyte TF expression. Blocking Abs against TF abolished CC-mediated coagulation, thus indicating involvement of the TF-dependent pathway. Blockade of FXII by corn trypsin inhibitor had a significant inhibitory effect on CC-induced PTF1.2 in platelet-free plasma, although the overall activation potential was low. CC exposure did not induce platelet aggregation, TF microparticle induction, or TF on granulocytes or eosinophils. Inhibition of complement C3 by CP40 (compstatin), C5 by eculizumab, or C5aR1 by PMX53 blocked CC-induced PTF1.2 by 90% and reduced TF⁺ monocytes from 18-20 to 1-2%. The physiologic relevance was supported by birefringent CC structures adjacent to monocytes (CD14), TF, and activated complement iC3b and C5b-9 in a human brain thrombus. Furthermore, monocyte influx and TF induction in close proximity to CC-rich regions with activated complement were found in a vulnerable plaque. In conclusion, CC could be active, releasable contributors to thrombosis by inducing monocyte TF secondary to complement C5aR1 signaling.

Visible-free cholesterol crystal emboli adjacent to microinfarcts in myocardial capillaries and arterioles on H&E-stained frozen sections of an autopsied patient

The number of released free cholesterol crystal emboli (fCCE) and their role during percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) have not been documented yet. Furthermore, fCCE manifesting in the coronary lumen following plaque rupture has been historically overlooked owing to the standard tissue preparation for light microscopy which uses ethanol as a dehydrating agent that can dissolve fCCE, leaving behind empty tissue. In this case report, we evaluated fCCE released during PCI for ACS and their relationship with myocardial injury and coronary artery obstruction on the H&E-stained sections by using polarised light microscopy. To our knowledge, there has been no mention of the visibility of fCCE on H&E-stained frozen polarised sections before.

PET/CTA detection of muscle inflammation related to cholesterol crystal emboli without arterial obstruction

BACKGROUND

PET/CTA was used to evaluate the effect of cholesterol crystal emboli (CCE) on muscle injury. Cholesterol crystals (CCs) released during plaque rupture travel downstream and lodge in muscle triggering inflammation and tissue injury.

METHODS

Thigh muscles in three groups of rabbits (n = 22) were studied after intra-arterial injection of CCs, Group I (n = 10); polystyrene microspheres, Group II (n = 5); or normal saline, Group III (n = 7). After 48 hours, muscle inflammation and injury were measured by fluorodeoxy-glucose uptake using PET/CTA, serum tissue factor (TF), and creatinine phosphokinase (CPK). Macrophages were stained with RAM11 and CCs with Bodipy.

RESULTS

SUVmax of thigh muscles was greater for Group I vs Group II and III (0.40 ± 0.16 vs 0.21 ± 0.11, P = .038 and 0.23 ± 0.06, P = .036). CPK levels rose significantly in Group I vs Group II and III (6.7 ± 6.0 vs 0.6 ± 0.4, P = .007 and 0.9 ± 0.4 mg·dL-1, P = .023). No arterial thrombosis was detected by CTA or histology of embolized arteries and TF did not rise significantly. There were extensive macrophage infiltrates surrounding muscle necrosis in Group I only.

CONCLUSIONS

Cholesterol crystal emboli triggered muscle inflammation and necrosis with an intact circulation. PET/CTA may help in the early detection of inflammation caused by CCs.

Frequency of Cholesterol Crystals in Culprit Coronary Artery Aspirate During Acute Myocardial Infarction and Their Relation to Inflammation and Myocardial Injury

Cholesterol crystals (CCs) have been associated with plaque rupture through mechanical injury and inflammation. This study evaluated the presence of CCs during acute myocardial infarction (AMI) and associated myocardial injury, inflammation, and arterial blood flow before and after percutaneous coronary intervention. Patients presenting with AMI (n = 286) had aspiration of culprit coronary artery obstruction. Aspirates were evaluated for crystal content, size, composition, and morphology by scanning electron microscopy, crystallography, and infrared spectroscopy. These were correlated with inflammatory biomarkers, cardiac enzymes, % coronary stenosis, and Thrombolysis in Myocardial Infarction (TIMI) blush and flow grades. Crystals were detected in 254 patients (89%) and confirmed to be cholesterol by spectroscopy. Of 286 patients 240 (84%) had CCs compacted into clusters that were large enough to be measured and analyzed. Moderate to extensive CC content was present in 172 cases (60%). Totally occluded arteries had significantly larger CC clusters than partially occluded arteries (p <0.05). Patients with CC cluster area >12,000 µm² had significantly elevated interleukin-1 beta (IL-1β) levels (p <0.01), were less likely to have TIMI blush grade of 3 (p <0.01), and more likely to have TIMI flow grade of 1 (p <0.01). Patients with recurrent AMI had smaller CC cluster area (p <0.04), lower troponin (p <0.02), and IL-1β levels (p <0.04). Women had smaller CC clusters (p <0.04). Macrophages in the aspirates were found to be attached to CCs. Coronary artery aspirates had extensive deposits of CCs during AMI. In conclusion, presence of large CC clusters was associated with increased inflammation (IL-1β), increased arterial narrowing, and diminished reflow following percutaneous coronary intervention.

Cholesterol crystal embolization following plaque rupture: a systemic disease with unusual features

Cholesterol crystal embolic (CCE) syndrome is often a clinically challenging condition that has a poor prognostic implication. It is a result of plaque rupture with release of cholesterol crystals into the circulation that embolize into various tissue organs. Plaque rupture seems to be triggered by an expanding necrotic core during cholesterol crystallization forming sharp tipped crystals that perforate and tear the fibrous cap. Embolizing cholesterol crystals then initiate both local and systemic inflammation that eventually lead to vascular fibrosis and obstruction causing symptoms that can mimic other vasculitic conditions. In fact, animal studies have demonstrated that cholesterol crystals can trigger an inflammatory response via NLRP3 inflammasome similar to that seen with gout. The diagnosis of CCE syndrome often requires a high suspicion of the condition. Serum inflammation biomarkers including elevated sedimentation rate, abnormal renal function tests and eosinophilia are useful but non-specific. Common target organ involvement includes the skin, kidney, and brain. Various testing including fundoscopic eye examination and other non-invasive procedures such as trans-esophageal echocardiography and magnetic resonance imaging may be helpful in identifying the embolic source. Treatment includes aspirin and clopidogrel, high dose statin and possibly steroids. In rare cases, mechanical intervention using covered stents may help isolate the ruptured plaque. Anticoagulation with warfarin is not recommended and might even be harmful. Overall, CCE syndrome is usually a harbinger of extensive and unstable atherosclerotic disease that is often associated with acute cardiovascular events.

Plaque Rupture and Thrombosis: the Value of the Atherosclerotic Rabbit Model in Defining the Mechanism

Persistent inflammation and mechanical injury associated with cholesterol crystal accretion within atherosclerotic plaques typically precedes plaque disruption (rupture and/or erosion) and thrombosis--often the terminal events of atherosclerotic cardiovascular disease. To elucidate the mechanisms of these events, the atherosclerotic rabbit model provides a unique and powerful tool that facilitates studies of atherogenesis starting with plaque buildup to eventual disruption. Examination of human coronary arteries obtained from patients who died with myocardial infarction demonstrates evidence of cholesterol crystals perforating the plaque cap and intimal surface of the arterial wall that can lead to rupture. These observations were made possible by omitting ethanol, an avid lipid solvent, from the tissue processing steps. Importantly, the atherosclerotic rabbit model exhibits a similar pathology of cholesterol crystals perforating the intimal surface as seen in ruptured human plaques. Local and systemic inflammatory responses in the model are also similar to those observed in humans. The strong parallel between the rabbit and human pathology validates the atherosclerotic rabbit model as a predictor of human pathophysiology of atherosclerosis. Thus, the atherosclerotic rabbit model can be used with confidence to evaluate diagnostic imaging and efficacy of novel anti-atherosclerotic therapy.

Cholesterol crystal induced arterial inflammation and destabilization of atherosclerotic plaque

Evolution of plaque that is prone to rupture is characterized by inflammation and physical changes. Accumulation of low-density lipoprotein in the sub-intima provides esterified cholesterol (ESC) to macrophages and smooth muscle cells that convert it into free cholesterol (FRC) by cholesteryl ester hydrolases (CEHs). Membrane-bound cholesterol carriers transport FRC to high-density lipoprotein (HDL). Impaired HDL transport function and altered composition can lead to extracellular accumulation of FRC, whereas impaired membrane carrier activity can lead to intracellular FRC accumulation. Saturation of FRC can result in cholesterol crystallization with cell death and intimal injury. Disequilibrium between ESC and FRC can impact foam cell and cholesterol crystal (CC) formation. Cholesterol crystals initiate inflammation via NLRP3 inflammasome leading to interleukin-1β (IL-1β) production inducing C-reactive protein. Eventually, crystals growing from within the plaque and associated inflammation destabilize the plaque. Thus, inhibition of inflammation by antagonists to IL-1β or agents that dissolve or prevent CC formation may stabilize vulnerable plaques.