Pathophysiology and targeted treatment of cholesterol crystal embolism and the related thrombotic angiopathy

Cholesterol crystals in the pathogenesis of atherosclerosis

The presence of cholesterol crystals (CCs) in tissues was first described more than 100 years ago. CCs have a pathogenic role in various cardiovascular diseases, including myocardial infarction, aortic aneurysm and, most prominently, atherosclerosis. Although the underlying mechanisms and signalling pathways involved in CC formation are incompletely understood, numerous studies have highlighted the existence of CCs at various stages of atheroma progression. In this Review, we summarize the mechanisms underlying CC formation and the role of CCs in cardiovascular disease. In particular, we explore the established links between lipid metabolism across various cell types and the formation of CCs, with a focus on CC occurrence in the vasculature. We also discuss CC-induced inflammation as one of the pathogenic features of CCs in the atheroma. Finally, we summarize the therapeutic strategies aimed at reducing CC-mediated atherosclerotic burden, including approaches to inhibit CC formation in the vasculature or to mitigate the inflammatory response triggered by CCs. Addressing CC formation might emerge as a crucial component in our broader efforts to combat cardiovascular disease.

The role of cholesterol crystals and ocular crystal emboli in retinal pathology

Cholesterol crystals (CC) can be responsible for a range of clinical syndromes in the retina from asymptomatic plaques to retinal artery occlusion with clinical trials providing evidence for the efficacy in lipid lowering therapies in preventing ocular pathology. Much of the literature has focused on CC in retinal circulation as a marker of poor systemic health and have attempted to use them to categorize risk of mortality and stroke. More recently cholesterol accumulation and CC formation have been linked to development of diabetic retinopathy with CC formation in the retina due to aberrant retinal cholesterol homeostasis and not simply systemic dyslipidemia.

Looking into the cholesterol crystal ball: is complement the answer?

Cholesterol crystal embolism (CCE) is a complication of atherosclerosis and can cause microvascular obstruction in multiple organs. Because the consequences may be fatal, and there is no specific treatment, it is crucial to understand the mechanisms and identify treatment strategies. In this issue, Zhao et al., using a mouse model of kidney CCE, demonstrated that inhibition of C5a/C5aR prevented and resolved CCE-induced renal thrombosis and angiopathy. Although these findings must be extended to human condition, they offer hope for management of CCE syndrome.

Cutaneous Dermatologic Manifestations of Cardiovascular Diseases: A Narrative Review

Cardiovascular diseases represent the largest worldwide cause of morbidity and mortality. Common signs and symptoms of cardiovascular disease are well characterized and taught in medical curricula, allowing clinicians to quickly recognize and diagnose the more acute and emergent cardiovascular diseases. Dermatological features associated with cardiovascular diseases are less understood but very valuable to appreciate in clinical practice. The present investigation evaluates heart conditions such as heart failure, atherosclerosis, infective endocarditis, and Takotsubo cardiomyopathy, highlighting dermatologic signs that indicate underlying cardiovascular pathology and serve as important diagnostic and prognostic markers.

The function of the complement system remains fully intact throughout the course of allogeneic stem cell transplantation

Introduction

Hematopoietic stem cell transplantation (HSCT) is associated with immune complications and endothelial dysfunction due to intricate donor-recipient interactions, conditioning regimens, and inflammatory responses.

Methods

This study investigated the role of the complement system during HSCT and its interaction with the cytokine network. Seventeen acute myeloid leukemia patients undergoing HSCT were monitored, including blood sampling from the start of the conditioning regimen until four weeks post-transplant. Clinical follow-up was 200 days.

Results

Total complement functional activity was measured by WIELISA and the degree of complement activation by ELISA measurement of sC5b-9. Cytokine release was measured using a 27-multiplex immuno-assay. At all time-points during HSCT complement functional activity remained comparable to healthy controls. Complement activation was continuously stable except for two patients demonstrating increased activation, consistent with severe endotheliopathy and infections. In vitro experiments with post-HSCT whole blood challenged with Escherichia coli, revealed a hyperinflammatory cytokine response with increased TNF, IL-1β, IL-6 and IL-8 formation. Complement C3 inhibition markedly reduced the cytokine response induced by Staphylococcus aureus, Aspergillus fumigatus, and cholesterol crystals.

Discussion

In conclusion, HSCT patients generally retained a fully functional complement system, whereas activation occurred in patients with severe complications. The complement-cytokine interaction indicates the potential for new complement-targeting therapeutic strategies in HSCT.

Characterization of active peptides derived from three leeches and comparison of their anti-thrombotic mechanisms using the tail vein thrombosis model in mice and metabonomics

Background and aims: The increasing incidence of cardiovascular diseases has created an urgent need for safe and effective anti-thrombotic agents. Leech, as a traditional Chinese medicine, has the effect of promoting blood circulation and removing blood stasis, but its real material basis and mechanism of action for the treatment of diseases such as blood stasis and thrombosis have not been reported. Methods: In this study, Whitmania Pigra Whitman (WPW), Hirudo nipponica Whitman (HNW) and Whitmania acranutata Whitman (WAW) were hydrolyzed by biomimetic enzymatic hydrolysis to obtain the active peptides of WPW (APP), the active peptides of HNW (APH) and the active peptides of WAW (APA), respectively. Then their structures were characterized by sykam amino acid analyzer, fourier transform infrared spectrometer (FT-IR), circular dichroism (CD) spectrometer and LC-MS. Next, the anti-thrombotic activities of APP, APH and APA were determined by carrageenan-induced tail vein thrombosis model in mice, and the anti-thrombotic mechanisms of high-dose APP group (HAPP), high-dose APH group (HAPH) and high-dose APA group (HAPA) were explored based on UHPLC-Q-Exactive Orbitrap mass spectrometry. Results: The results showed that the amino acid composition of APP, APH and APA was consistent, and the proportion of each amino acid was few different. The results of FT-IR and CD showed that there were no significant differences in the proportion of secondary structures (such as β-sheet and random coil) and infrared absorption peaks between APP, APH and APA. Mass spectrometry data showed that there were 43 common peptides in APP, APH and APA, indicating that the three have common material basis. APP, APH and APA could significantly inhibit platelet aggregation, reduce black-tail length, whole blood viscosity (WBV), plasma viscosity (PV), and Fibrinogen (FIB), and prolong coagulation time, including activated partial thrombin time (APTT), prothrombin time (PT) and thrombin time (TT). In addition, 24 metabolites were identified as potential biomarkers associated with thrombosis development. Among these, 19, 23, and 20 metabolites were significantly normalized after administration of HAPP, HAPH, and HAPA in the mice, respectively. Furthermore, the intervention mechanism of HAPP, HAPH and HAPA on tail vein thrombosis mainly involved in linoleic acid metabolism, primary bile acid biosynthesis and ether lipid metabolism. Conclusion: Our findings suggest that APP, APH and APA can exert their anti-blood stasis and anti-thrombotic activities by interfering with disordered metabolic pathways in vivo, and there is no significant difference in their efficacies.

Acute type B aortic dissection with multiple cholesterol embolism: an autopsy case report

Background

Most cases of cholesterol embolism are known to be triggered by cardiac catheterization, cardiovascular surgery, anticoagulation, or fibrinolytic therapy; however, spontaneous cases after aortic dissection are rare. In this report, we describe a case of cholesterol embolism after type B aortic dissection, which rapidly developed into multiple organ failure and death.

Case summary

A 65-year-old man with untreated hypertension was admitted to our hospital with sudden back pain and diagnosed with type B aortic dissection. The patient experienced a rapid progression of inflammation and developed respiratory and renal failure, despite computed tomography showing no obvious progression of dissection. We attributed them to a cytokine storm and acute respiratory distress syndrome, but steroid pulse therapy did not alleviate the symptoms. Finally, the patient died on Day 6 after admission, and an autopsy was performed, which revealed cholesterol crystal occlusions in the kidney, spleen, and the left lower leg. The lumen in the aorta is filled with atheroma and thrombus, and we suspect that aortic dissection triggered failure of the aortic plaques and released cholesterol crystals to distal arteries that led to cholesterol embolism.

Discussion

We experienced a patient with a type B aortic dissection that led to cholesterol embolism and rapid progression of respiratory and renal failure, resulting in death. The aortic dissection combined with cholesterol embolism was considered to trigger the subsequent severe inflammation, leading to rapid respiratory and renal failure. Our case points to the possibility that cholesterol embolism can extensively escalate inflammation after aortic dissection.