Vascular Diseases and Gangliosides

Lipidomic Risk Score to Enhance Cardiovascular Risk Stratification for Primary Prevention

BACKGROUND

Accurate risk stratification is vital for primary prevention of cardiovascular disease (CVD). However, traditional tools such as the Framingham Risk Score (FRS) may underperform within the diverse intermediate-risk group, which includes individuals requiring distinct management strategies.

OBJECTIVES

This study aimed to develop a lipidomic-enhanced risk score (LRS), specifically targeting risk prediction and reclassification within the intermediate group, benchmarked against the FRS.

METHODS

The LRS was developed via a machine learning workflow using ridge regression on the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab; n = 10,339). It was externally validated with the Busselton Health Study (n = 4,492), and its predictive utility for coronary artery calcium scoring (CACS)-based outcomes was independently validated in the BioHEART cohort (n = 994).

RESULTS

LRS significantly improved discrimination metrics for the intermediate-risk group in both AusDiab and Busselton Health Study cohorts (all P < 0.001), increasing the area under the curve for CVD events by 0.114 (95% CI: 0.1123-0.1157) and 0.077 (95% CI: 0.0755-0.0785), with a net reclassification improvement of 0.36 (95% CI: 0.21-0.51) and 0.33 (95% CI: 0.15-0.49), respectively. For CACS-based outcomes in BioHEART, LRS achieved a significant area under the curve improvement of 0.02 over the FRS (0.76 vs 0.74; P < 1.0 × 10-5). A simplified, clinically applicable version of LRS was also created that had comparable performance to the original LRS.

CONCLUSIONS

LRS, augmenting the FRS, presents potential to improve intermediate-risk stratification and to predict atherosclerotic markers using a simple blood test, suitable for clinical application. This could facilitate the triage of individuals for noninvasive imaging such as CACS, fostering precision medicine in CVD prevention and management.

Resveratrol Inhibits Restenosis through Suppressing Proliferation, Migration and Trans-differentiation of Vascular Adventitia Fibroblasts via Activating SIRT1

AIM

After the balloon angioplasty, vascular adventitia fibroblasts (VAFs), which proliferate, trans-differentiate to myofibroblasts and migrate to neointima, are crucial in restenosis. Resveratrol (RSV) has been reported to protect the cardiovascular by reducing restenosis and the mechanism remains unclear.

METHODS

This study was dedicated to investigate the effect of RSV on VAFs in injured arteries and explore the potential mechanism. In this work, carotid artery balloon angioplasty was performed on male SD rats to ensure the injury of intima and VAFs were isolated to explore the effects in vitro. The functional and morphological results showed the peripheral delivery of RSV decreased restenosis of the injured arteries and suppressed the expression of proliferation, migration and transformation related genes. Moreover, after being treated with RSV, the proliferation, migration and trans-differentiation of VAFs were significantly suppressed and exogenous TGF-β1 can reverse this effect.

RESULT

Mechanistically, RSV administration activated SIRT1 and decreased the translation and expression of TGF-β1, SMAD3 and NOX4, and reactive oxygen species (ROS) decreased significantly after VAFs treated with RSV.

CONCLUSION

Above results indicated RSV inhibited restenosis after balloon angioplasty through suppressing proliferation, migration and trans-differentiation of VAFs via regulating SIRT1- TGF-β1-SMAD3-NOX4 to decrease ROS.

Lipid rafts and human diseases: why we need to target gangliosides

Gangliosides are functional components of membrane lipid rafts that control critical functions in cell communication. Many pathologies involve raft gangliosides, which therefore represent an approach of choice for developing innovative therapeutic strategies. Beginning with a discussion of what a disease is (and is not), this review lists the major human pathologies that involve gangliosides, which includes cancer, diabetes, and infectious and neurodegenerative diseases. In most cases, the problem is due to a protein whose binding to gangliosides either creates a pathological condition or impairs a physiological function. Then, I draw up an inventory of the different molecular mechanisms of protein-ganglioside interactions. I propose to classify the ganglioside-binding domains of proteins into four categories, which I name GBD-1, GBD-2, GBD-3, and GBD-4. This structural and functional classification could help to rationalize the design of innovative molecules capable of disrupting the binding of selected proteins to gangliosides without generating undesirable effects. The biochemical specificities of gangliosides expressed in the human brain must also be taken into account to improve the reliability of animal models (or any animal-free alternative) of Alzheimer's and Parkinson's diseases.

Uptake of severe acute respiratory syndrome coronavirus 2 spike protein mediated by angiotensin converting enzyme 2 and ganglioside in human cerebrovascular cells

Introduction

There is clinical evidence of neurological manifestations in coronavirus disease-19 (COVID-19). However, it is unclear whether differences in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/spike protein (SP) uptake by cells of the cerebrovasculature contribute to significant viral uptake to cause these symptoms.

Methods

Since the initial step in viral invasion is binding/uptake, we used fluorescently labeled wild type and mutant SARS-CoV-2/SP to study this process. Three cerebrovascular cell types were used (endothelial cells, pericytes, and vascular smooth muscle cells), in vitro.

Results

There was differential SARS-CoV-2/SP uptake by these cell types. Endothelial cells had the least uptake, which may limit SARS-CoV-2 uptake into brain from blood. Uptake was time and concentration dependent, and mediated by angiotensin converting enzyme 2 receptor (ACE2), and ganglioside (mono-sialotetrahexasylganglioside, GM1) that is predominantly expressed in the central nervous system and the cerebrovasculature. SARS-CoV-2/SPs with mutation sites, N501Y, E484K, and D614G, as seen in variants of interest, were also differentially taken up by these cell types. There was greater uptake compared to that of the wild type SARS-CoV-2/SP, but neutralization with anti-ACE2 or anti-GM1 antibodies was less effective.

Conclusion

The data suggested that in addition to ACE2, gangliosides are also an important entry point of SARS-CoV-2/SP into these cells. Since SARS-CoV-2/SP binding/uptake is the initial step in the viral penetration into cells, a longer exposure and higher titer are required for significant uptake into the normal brain. Gangliosides, including GM1, could be an additional potential SARS-CoV-2 and therapeutic target at the cerebrovasculature.

PRC2-dependent regulation of ganglioside expression during dedifferentiation contributes to the proliferation and migration of vascular smooth muscle cells

Phenotypic switching between contractile (differentiated state) and proliferative (dedifferentiated state) vascular smooth muscle cells (VSMCs) is a hallmark of vascular remodeling that contributes to atherosclerotic diseases. Gangliosides, a group of glycosphingolipids, have been detected in atherosclerotic lesions and are suspected to contribute to the disease process. However, the underlying mechanism, specifically with respect to their role in VSMC phenotype switching, is not clear. In this study, we sought to reveal the endogenous expression of gangliosides and their functional significance in VSMCs during atherosclerosis. We found that switching from the contractile to proliferative phenotype was accompanied by upregulation of a- and b-series gangliosides, which in turn, were regulated by polycomb repressor complex 2 (PRC2). Downregulation of ganglioside expression using an siRNA targeting ST3GAL5, which is required for the synthesis of a- and b-series gangliosides, attenuated the proliferation and migration of dedifferentiated VSMCs. Therefore, we concluded that the increased expression of a- and b-series gangliosides via PRC2 activity during dedifferentiation is involved in the proliferation and migration of VSMCs. Gangliosides may be an effective target in VSMCs for atherosclerosis prevention and treatment.

Glucosylceramide synthase inhibition protects against cardiac hypertrophy in chronic kidney disease

A significant population of patients with chronic kidney disease (CKD) develops cardiac hypertrophy, which can lead to heart failure and sudden cardiac death. Soluble klotho (sKL), the shed ectodomain of the transmembrane protein klotho, protects the heart against hypertrophic growth. We have shown that sKL protects the heart by regulating the formation and function of lipid rafts by targeting the sialic acid moiety of gangliosides, GM1/GM3. Reduction in circulating sKL contributes to an increased risk of cardiac hypertrophy in mice. sKL replacement therapy has been considered but its use is limited by the inability to mass produce the protein. Therefore, alternative methods to protect the heart are proposed. Glucosylation of ceramide catalyzed by glucosylceramide synthase is the entry step for the formation of gangliosides. Here we show that oral administration of a glucosylceramide synthase inhibitor (GCSi) reduces plasma and heart tissue glycosphingolipids, including gangliosides. Administration of GCSi is protective in two mouse models of cardiac stress-induction, one with isoproterenol overstimulation and the other with 5/6 nephrectomy-induced CKD. Treatment with GCSi does not alter the severity of renal dysfunction and hypertension in CKD. These results provide proof of principle for targeting glucosylceramide synthase to decrease gangliosides as a treatment for cardiac hypertrophy. They also support the hypothesis that sKL protects the heart by targeting gangliosides.

Protective Effect of Panax Notoginseng Saponins on Apolipoprotein-E-deficient Atherosclerosis-prone mice

BACKGROUND

It is widely recognized that atherosclerosis（AS）is related to vascular inflammation. Panax notoginseng saponins (PNS) extracted from the roots of Panax notoginseng has been shown to possess anti-inflammatory activity. It is widely used in the clinical treatment of cardiovascular and cerebrovascular diseases, but the protective effect of PNS on atherosclerosis is not fully understood. This study was designed to test the effects of PNS administration in apolipoprotein (apo)-E-deficient (ApoE-/-) mice on the activation of NF-κB p65, IL-1β, IL-6, TNF-α and Calpain1 proteins.

METHODS

24 ApoE-/- mice fed with high-fat diet for 8 weeks to create the AS model. PNS, dissolved in three distilled water, was administered orally to two treatment groups at dosages of 60 mg/kg/d/mice and 180 mg/kg/d/mice. After for 8 weeks, Peripheral blood was collected for assessing the levels of TG, TC, LDL-C and HDL-C in serum by Biochemical Analyzer. HE staining was used to observe pathomorphological changes in the aorta root. Oil Red O staining was used to observe the lipid deposition in the aorta root. ELISA kits were used to assess the levels of IL-1β and TNF-α in serum. The expression levels of NF-κB p65, IL-1β, IL-6, TNF-α, and Calpain1 proteins in aorta root were identified by Western blot.

RESULTS

After PNS administration for 8 weeks, the levels of TG, TC, LDL-C, IL -1β and TNF-α were decreased, the level of HDL-C was increased in apoE-/- mice. The arrangement of the tissue of aortic root tended to be normal, the cell morphology was restored, and the lipid depositions were reduced in apoE-/- mice treated with PNS. Moreover, PNS inhibited the expression levels of NF-κB p65, IL-6, IL-1β, TNF-α and Calpain1 proteins of aortic root tissues in apoE-/- mice.

CONCLUSION

PNS may inhibit the progression of atherosclerotic lesion via their anti-inflammatory biological property. PNS suppress the NF-κB signaling pathway and inhibite the expression of pro-inflammatory factors such as NF-κB p65, IL-6, IL-1β, TNF-α and Calpain1 proteins in aortic root tissues of apoE-/- mice.

Enhanced Anti-Atherosclerotic Efficacy of pH-Responsively Releasable Ganglioside GM3 Delivered by Reconstituted High-Density Lipoprotein

Recently, the atheroprotective role of endogenous GM3 and an atherogenesis-inhibiting effect of exogenous GM3 suggested a possibility of exogenous GM3 being recruited as an anti-atherosclerotic drug. This study seeks to endow exogenous GM3 with atherosclerotic targetability via reconstituted high-density lipoprotein (rHDL), an atherosclerotic targeting drug nanocarrier. Unloaded rHDL, rHDL loaded with exogenous GM3 at a low concentration (GM3_L-rHDL), and rHDL carrying GM3 at a relatively high concentration (GM3_H-rHDL) were prepared and characterized. The inhibitory effect of GM3-rHDL on lipid deposition in macrophages was confirmed, and GM3-rHDL did not affect the survival of red blood cells. In vivo experiments using ApoE^-/- mice fed a high fat diet further confirmed the anti-atherosclerotic efficacy of exogenous GM3 and demonstrated that GM3 packed in HDL nanoparticles (GM3-rHDL) has an enhanced anti-atherosclerotic efficacy and a reduced effective dose of GM3. Then, the macrophage- and atherosclerotic plaque-targeting abilities of GM3-rHD, most likely via the interaction of ApoA-I on GM3-rHDL with its receptors (e.g., SR-B1) on cells, were certified via a microsphere-based method and an aortic fragment-based method, respectively. Moreover, we found that solution acidification enhanced GM3 release from GM3-rHDL nanoparticles, implying the pH-responsive GM3 release when GM3-rHDL enters the acidic atherosclerotic plaques from the neutral blood. The rHDL-mediated atherosclerotic targetability and pH-responsive GM3 release of GM3-rHDL enhanced the anti-atherosclerotic efficacy of exogenous GM3. The development of the GM3-rHDL nanoparticle may help with the application of exogenous GM3 as a clinical drug. Moreover, the data imply that the GM3-rHDL nanoparticle has the potential of being recruited as a drug nanocarrier with atherosclerotic targetability and enhanced anti-atherosclerotic efficacy.

Molecular recognition of sialoglycans by streptococcal Siglec-like adhesins: toward the shape of specific inhibitors

Streptococcus gordonii and Streptococcus sanguinis, commensal bacteria present in the oral cavity of healthy individuals, upon entry into the bloodstream can become pathogenic, causing infective endocarditis (IE). Sialic acid-binding serine-rich repeat adhesins on the microbial surface represent an important factor of successful infection to cause IE. They contain Siglec-like binding regions (SLBRs) that variously recognize different repertoires of O-glycans, with some strains displaying high selectivity and others broader specificity. We here dissect at an atomic level the mechanism of interaction of SLBR-B and SLBR-H from S. gordonii with a multivarious approach that combines NMR spectroscopy and computational and biophysical studies. The binding pockets of both SLBRs are broad enough to accommodate extensive interactions with sialoglycans although with key differences related to strain specificity. Furthermore, and significantly, the pattern of interactions established by the SLBRs are mechanistically very different from those reported for mammalian Siglecs despite them having a similar fold. Thus, our detailed description of the binding modes of streptococcal Siglec-like adhesins sparks the development of tailored synthetic inhibitors and therapeutics specific for Streptococcal adhesins to counteract IE, without impairing the interplay between Siglecs and glycans.

We here present a detailed molecular description of sialoglycans recognition by Siglec-like adhesins from S. gordonii opening the venue for the design of specific inhibitors to influence the propensity of streptococci to cause infective endocarditis.

Editorial for Special Issue "Gangliosides: Modes of Action and Cell Fates"

Gangliosides have been considered to play essential roles in the regulation of nervous systems. Novel findings about their functions based on the unique genetic and biochemical approaches have been recently accumulated, and representative results were collected here. In particular, new developments of analytical methods, regulatory mechanisms for ganglioside synthesis and degradation, and novel aspects of their functions in nervous systems and various other organs were introduced in this Special Issue, promoting further fundamental investigation and applied research.