The anti-inflammatory function of high-density lipoprotein in type II diabetes: A systematic review

Favourable HDL composition in endurance athletes is not associated with changes in HDL in vitro antioxidant and endothelial anti-inflammatory function

Given the failure of high-density lipoprotein (HDL) raising therapies to reduce cardiovascular disease risk, attention has turned towards HDL composition and vascular protective functions. In individuals with insulin resistance, exercise interventions recover HDL function. However, the effect of exercise on HDL in otherwise healthy individuals is unknown. This cross-sectional study aimed to measure HDL composition and antioxidant/endothelial anti-inflammatory function in insulin sensitive endurance athlete and healthy control men. HDL was isolated using density gradient ultracentrifugation. HDL composition was measured using microplate assays for apolipoprotein A-I, total cholesterol content and apolipoprotein M. HDL protein composition was measured using nano-liquid chromatography tandem mass spectrometry. HDL subclass distribution was measured by native gel electrophoresis. HDL in vitro antioxidant function was measured by paraoxonase-1 activity assay and anti-inflammatory function assessed in endothelial cells. Compared with controls, endurance athlete HDL had higher apolipoprotein A-1 (1.65 ± 0.62 mg/ml vs 1.21 ± 0.34 mg/ml, P=0.028) and higher total cholesterol content (2.09 ± 0.44 mmol/L vs 1.54 ± 0.33 mmol/L, P<0.001). Proteomics revealed higher apolipoprotein A-II, A-IV and D and transthyretin in endurance athlete HDL versus controls. There was no difference observed in in vitro HDL antioxidant or anti-inflammatory functions between controls and endurance athletes. Despite a more favourable composition, endurance athlete HDL did not have higher in vitro antioxidant or anti-inflammatory function. It is possible that HDL has a ceiling of function, i.e. that healthy HDL function cannot be enhanced by endurance exercise.

Distinct roles of size-defined HDL subpopulations in cardiovascular disease

PURPOSE OF REVIEW

Doubts about whether high-density lipoprotein-cholesterol (HDL-C) levels are causally related to atherosclerotic cardiovascular disease (CVD) risk have stimulated research on identifying HDL-related metrics that might better reflect its cardioprotective functions. HDL is made up of different types of particles that vary in size, protein and lipid composition, and function. This review focuses on recent findings on the specific roles of HDL subpopulations defined by size in CVD.

RECENT FINDINGS

Small HDL particles are more effective than larger particles at promoting cellular cholesterol efflux because apolipoprotein A-I on their surface better engages ABCA1 (ATP binding cassette subfamily A member 1). In contrast, large HDL particles bind more effectively to scavenger receptor class B type 1 on endothelial cells, which helps prevent LDL from moving into the artery wall. The specific role of medium-sized HDL particles, the most abundant subpopulation, is still unclear.

SUMMARY

HDL is made up of subpopulations of different sizes of particles, with selective functional roles for small and large HDLs. The function of HDL may depend more on the size and composition of its subpopulations than on HDL-C levels. Further research is required to understand how these different HDL subpopulations influence the development of CVD.

Monocyte to HDL ratio may predict thrombosis in patients with mechanical mitral and aortic valve prosthesis

Increased inflammatory biomarkers have been reported in prosthetic heart valve thrombosis (PHVT). Monocyte to HDL ratio (MHR) and albumin to CRP levels (CAR) are two biomarkers used widely for systemic inflammation but there is a lack of data on prosthetic heart valves. This study aimed to find out the potential predictive value of MHR and CAR for PHVT. Patients who had the diagnosis of mechanical mitral/aortic PHVT and normally functioning prosthesis were retrospectively analyzed. Laboratory data including complete blood count and biochemistry were recorded. Transesophageal echocardiography was performed to diagnose PHVT. The study included 118 patients with mechanical PHVT and 120 patients with normally functioning prosthesis. White blood count, monocyte levels, C-reactive protein, MHR and CAR were significantly higher whereas the lymphocyte, HDL and INR levels on admission were lower in patients with PHVT. Multivariate analysis showed that as well as inadequate anticoagulation, MHR, but not CAR, was found to be an independent predictor of thrombosis in patients with PHVT. Receiver operating characteristic curve analysis was performed to detect the best cut-off value of MHR in the prediction of thrombosis in patients with prosthetic valves. MHR level of > 12.8 measured on admission, yielded an AUC value of 0.791 [(CI 95% 0.733-0.848 p < 0.001) sensitivity 71%, specificity 70%]. Inadequate anticoagulation is the primary cause that leads to thrombosis in mechanical prosthetic valves. Increased MHR, but not CAR, was also shown to be an independent predictor of thrombosis in patients with mechanical mitral and aortic prosthetic valves.

ApoA-I Nanotherapy Rescues Postischemic Vascular Maladaptation by Modulating Endothelial Cell and Macrophage Phenotypes in Type 2 Diabetic Mice

BACKGROUND

Diabetes is a major risk factor for peripheral arterial disease. Clinical and preclinical studies suggest an impaired collateral remodeling and angiogenesis in response to atherosclerotic arterial occlusion in diabetic conditions, although the underlying mechanisms are poorly understood.

OBJECTIVE

To clarify the cellular and molecular mechanisms underlying impaired postischemic adaptive vascular responses and to evaluate rHDL (reconstituted HDL)-ApoA-I nanotherapy to rescue the defect in type 2 diabetic mouse model of hindlimb ischemia.

METHODS AND RESULTS

Hindlimb ischemia was induced by unilateral femoral artery ligation. Collateral and capillary parameters together with blood flow recovery were analyzed from normoxic adductor and ischemic gastrocnemius muscles, respectively, at day 3 and 7 post-ligation. In response to femoral artery ligation, collateral lumen area was significantly reduced in normoxic adductor muscles. Distally, ischemic gastrocnemius muscles displayed impaired perfusion recovery and angiogenesis paralleled with persistent inflammation. Muscle-specific mRNA sequencing revealed differential expression of genes critical for smooth muscle proliferation and sprouting angiogenesis in normoxic adductor and ischemic gastrocnemius, respectively, at day 7 post-ligation. Genes typical for macrophage (Mϕ) subsets were differentially expressed across both muscle types. Cell-specific gene expression, flow cytometry, and immunohistochemistry revealed persistent IFN-I response gene upregulation in arterial endothelial cells, ECs and Mϕs from T2DM mice associated with impaired collateral remodeling, angiogenesis and perfusion recovery. Furthermore, rHDL nanotherapy rescued impaired collateral remodeling and angiogenesis through dampening EC and Mϕ inflammation in T2DM mice.

CONCLUSIONS

Our results suggest that an impaired collateral remodeling and sprouting angiogenesis in T2DM mice is associated with persistent IFN-I response in ECs and Mϕs. Dampening persistent inflammation and skewing ECs and Mϕ phenotype toward less inflammatory ones using rHDL nanotherapy may serve as a potential therapeutic target for T2DM peripheral arterial disease.

Metabolic labeling unveils alterations in the turnover of HDL-associated proteins during diabetes progression in mice

Several aspects of diabetes pathophysiology and complications result from hyperglycemia-induced alterations in the structure and function of plasma proteins. Furthermore, insulin has a significant influence on protein metabolism by affecting both the synthesis and degradation of proteins in various tissues. To understand the role of progressive hyperglycemia on plasma proteins, in this study, we measured the turnover rates of high-density lipoprotein (HDL)-associated proteins in control (chow diet), prediabetic [a high-fat diet (HFD) for 8 wk] or diabetic [HFD for 8 wk with low-dose streptozotocin (HFD + STZ) in weeks 5-8 of HFD] C57BL/6J mice using heavy water (2H2O)-based metabolic labeling approach. Compared with control mice, HFD and HFD + STZ mice showed elevations of fasting plasma glucose levels in the prediabetic and diabetic range, respectively. Furthermore, the HFD and HFD + STZ mice showed increased hepatic triglyceride (TG) levels, total plasma cholesterol, and plasma TGs. The kinetics of 40 proteins were quantified using the proteome dynamics method, which revealed an increase in the fractional synthesis rate (FSR) of HDL-associated proteins in the prediabetic mice compared with control mice, and a decrease in FSR in the diabetic mice. The pathway analysis revealed that proteins with altered turnover rates were involved in acute-phase response, lipid metabolism, and coagulation. In conclusion, prediabetes and diabetes have distinct effects on the turnover rates of HDL proteins. These findings suggest that an early dysregulation of the HDL proteome dynamics can provide mechanistic insights into the changes in protein levels in these conditions.NEW & NOTEWORTHY This study is the first to examine the role of gradual hyperglycemia during diabetes disease progression on HDL-associated protein dynamics in the prediabetes and diabetic mice. Our results show that the fractional synthesis rate of HDL-associated proteins increased in the prediabetic mice whereas it decreased in the diabetic mice compared with control mice. These kinetic changes can help to elucidate the mechanism of altered protein levels and HDL dysfunction during diabetes disease progression.

Assessing the anti‑inflammatory effects of quercetin using network pharmacology and in vitro experiments

The present study aimed to investigate the anti-inflammatory effects of quercetin and the associated mechanisms involved. ELISA, reverse transcription-quantitative PCR and western blot analysis were performed to determine the anti-inflammatory effects of quercetin in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The molecular mechanisms of quercetin were investigated using network pharmacology, molecular docking technology and in vitro experiments. The results revealed that quercetin reduced the LPS-induced production of TNF-α, IL-6 and IL-1β in RAW264.7 macrophages. Protein-protein interaction network topology analysis indicated that Akt was the target of quercetin. Kyoto Encyclopedia of Genes and Genomes analysis indicated that quercetin may regulate the PI3K/Akt signaling pathway to exert its anti-inflammatory effects. Furthermore, the molecular docking results indicated that quercetin had a good affinity for the active sites of Akt. Western blot analysis confirmed that quercetin inhibited the phosphorylation of Akt, with an efficacy stronger than that of an Akt inhibitor. Taken together, Akt served as a target as part of the mechanism of the anti-inflammatory effect of quercetin. This result lays a foundation for the clinical application of quercetin in the treatment of inflammatory diseases.

The HDL Proteome Watch: Compilation of studies leads to new insights on HDL function

PURPOSE OF REVIEW

High density lipoproteins (HDL) are a heterogeneous family of particles that contain distinct complements of proteins that define their function. Thus, it is important to accurately and sensitively identify proteins associated with HDL. Here we highlight the HDL Proteome Watch Database which tracks proteomics studies from different laboratories across the world.

RECENT FINDINGS

In 45 published reports, almost 1000 individual proteins have been detected in preparations of HDL. Of these, 251 have been identified in at least three different laboratories. The known functions of these consensus HDL proteins go well beyond traditionally recognized roles in lipid transport with many proteins pointing to HDL functions in innate immunity, inflammation, cell adhesion, hemostasis and protease regulation, and even vitamin and metal binding.

SUMMARY

The HDL proteome derived across multiple studies using various methodologies provides confidence in protein identifications that can offer interesting new insights into HDL function. We also point out significant issues that will require additional study going forward.

Role of High-Density Lipoprotein Cholesterol (HDL-C) as a Clinical Predictor of Decompensation in Patients with Chronic Liver Disease (CLD)

INTRODUCTION

Systemic inflammation triggered by bacterial products like lipopolysaccharides (LPS) in the circulation is an important factor leading to decompensation in patients with chronic liver disease (CLD). High-density lipoprotein cholesterol (HDL-C) has a significant role in innate immune response to LPS in the circulation and could therefore increase the risk for decompensation in patients with CLD. In this study, we have explored the role of HDL-C as a prognostic marker for decompensation.

METHODS

This was a prospective, observational, cohort study where consecutive patients with CLD were included. Patients with cholestatic liver disease and hepatocellular carcinoma were excluded. Fasting lipids were measured in all patients at the time of recruitment. Each patient was carefully followed up for development of decompensation events such as new-onset/worsening ascites, hepatic encephalopathy, or variceal bleed during follow-up.

RESULTS

A total of 170 patients were included (mean age 60 ± 11.5 years, M : F = 6 : 1). At the end of follow-up, 97/170 patients (57%) had decompensation events. Mean HDL-C levels were significantly lower among patients with decompensation (27.5 ± 15 mg/dL vs. 43.5 ± 13.9 mg/dL; p value 0.004). Using ROC analysis, cut-off for HDL-C of 36.4 mg/dL was identified. On multivariate analysis, HDL-C (OR = 6.072; 95% CI 2.39-15.39) was found to have an independent association with risk of decompensation.

CONCLUSIONS

HDL-C level (<36.4 mg/dL) is a reliable marker for risk of decompensation and can be a useful addition to existing prognostic scoring systems in CLD. It can be a valuable tool to streamline treatment protocols and prioritise liver transplantation.

HDL and type 2 diabetes: the chicken or the egg?

HDL is a complex macromolecular cluster of various components, such as apolipoproteins, enzymes and lipids. Quality evidence from clinical and epidemiological studies led to the principle that HDL-cholesterol (HDL-C) levels are inversely correlated with the risk of CHD. Nevertheless, the failure of many cholesteryl ester transfer protein inhibitors to protect against CVD casts doubts on this principle and highlights the fact that HDL functionality, as dictated by its proteome and lipidome, also plays an important role in protecting against metabolic disorders. Recent data indicate that HDL-C levels and HDL particle functionality are correlated with the pathogenesis and prognosis of type 2 diabetes mellitus, a major risk factor for CVD. Hyperglycaemia leads to reduced HDL-C levels and deteriorated HDL functionality, via various alterations in HDL particles' proteome and lipidome. In turn, reduced HDL-C levels and impaired HDL functionality impact the performance of key organs related to glucose homeostasis, such as pancreas and skeletal muscles. Interestingly, different structural alterations in HDL correlate with distinct metabolic abnormalities, as indicated by recent data evaluating the role of apolipoprotein A1 and lecithin-cholesterol acyltransferase deficiency in glucose homeostasis. While it is becoming evident that not all HDL disturbances are causatively associated with the development and progression of type 2 diabetes, a bidirectional correlation between these two conditions exists, leading to a perpetual self-feeding cycle.

Breakfast partly restores the anti-inflammatory function of high-density lipoproteins from patients with type 2 diabetes mellitus

Background and aims

High-density lipoproteins (HDL) of patients with type 2 diabetes mellitus (T2DM) have impaired anti-inflammatory activities. The anti-inflammatory activity of HDL has been determined ex vivo after isolation by different methods from blood mostly obtained after overnight fasting. We first determined the effect of the HDL isolation method, and subsequently the effect of food intake on the anti-inflammatory function of HDL from T2DM patients.

Methods

Blood was collected from healthy controls and T2DM patients after an overnight fast, and from T2DM patients 3 h after breakfast (n = 17 each). HDL was isolated by a two-step density gradient ultracentrifugation in iodixanol (HDL_DGUC2), by sequential salt density flotation (HDL_SEQ) or by PEG precipitation (HDL_PEG). The anti-inflammatory function of HDL was determined by the reduction of the TNFα-induced expression of VCAM-1 in human coronary artery endothelial cells (HCAEC) and retinal endothelial cells (REC).

Results

HDL isolated by the three different methods from healthy controls inhibited TNFα-induced VCAM-1 expression in HCAEC. With apoA-I at 0.7 μM, HDL_DGUC2 and HDL_SEQ were similarly effective (16% versus 14% reduction; n = 3; p > 0.05) but less effective than HDL_PEG (28%, p < 0.05). Since ultracentrifugation removes most of the unbound plasma proteins, we used HDL_DGUC2 for further experiments. With apoA-I at 3.2 μM, HDL from fasting healthy controls and T2DM patients reduced TNFα-induced VCAM-1 expression in HCAEC by 58 ± 13% and 51 ± 20%, respectively (p = 0.35), and in REC by 42 ± 13% and 25 ± 18%, respectively (p < 0.05). Compared to preprandial HDL, postprandial HDL from T2DM patients reduced VCAM-1 expression by 56 ± 16% (paired test: p < 0.001) in HCAEC and by 34 ± 13% (paired test: p < 0.05) in REC.

Conclusions

The ex vivo anti-inflammatory activity of HDL is affected by the HDL isolation method. Two-step ultracentrifugation in an iodixanol gradient is a suitable method for HDL isolation when testing HDL anti-inflammatory function. The anti-inflammatory activity of HDL from overnight fasted T2DM patients is significantly impaired in REC but not in HCAEC. The anti-inflammatory function of HDL is partly restored by food intake.

HDL-C/apoA-I Ratio Is Associated with the Severity of Coronary Artery Stenosis in Diabetic Patients with Acute Coronary Syndrome

Background

Emerging evidence demonstrates that the lipid metabolism in acute coronary syndrome (ACS) patients with type 2 diabetes mellitus (T2DM) differs from nondiabetic patients. However, the distinct lipid profiles and their relationships with the severity of coronary artery stenosis and prognosis in patients with T2DM remain elusive.

Method and Result

This single-center, prospective cohort study enrolled 468 patients diagnosed with ACS undergoing coronary angiography, consisting of 314 non-DM and 154 DM patients. The HDL-C/apoA-I ratio was significantly higher in DM patients with a multivessel (≥3 affected vessels) lesion than a single-vessel (1-2 affected vessels) lesion. Regression analyses showed that the HDL-C/apoA-I ratio was positively correlated to the number of stenotic coronary arteries in DM patients but not non-DM patients. However, Kaplan-Meier survival analysis revealed no significant difference in the major adverse cardiovascular event rate regarding different HDL-C/apoA-I levels in DM or non-DM ACS patients at the end of the 2-year follow-up.

Conclusion

A higher HDL-C/apoA-I ratio is associated with increased severity of coronary artery stenosis in DM patients with ACS but not with the rate of major adverse cardiovascular events at the end of the 2-year follow-up.

Association Analysis of Hyperlipidemia with the 28-Day All-Cause Mortality of COVID-19 in Hospitalized Patients

Objective

This study aimed to determine the association of hyperlipidemia with clinical endpoints among hospitalized patients with COVID-19, especially those with pre-existing cardiovascular diseases (CVDs) and diabetes.

Methods

This multicenter retrospective cohort study included all patients who were hospitalized due to COVID-19 from 21 hospitals in Hubei province, China between December 31, 2019 and April 21, 2020. Patients who were aged < 18 or ≥ 85 years old, in pregnancy, with acute lethal organ injury (e.g., acute myocardial infarction, severe acute pancreatitis, acute stroke), hypothyroidism, malignant diseases, severe malnutrition, and those with normal lipid profile under lipid-lowering medicines (e.g., statin, niacin, fenofibrate, gemfibrozil, and ezetimibe) were excluded. Propensity score matching (PSM) analysis at 1:1 ratio was performed to minimize baseline differences between patient groups of hyperlipidemia and non-hyperlipidemia. PSM analyses with the same strategies were further conducted for the parameters of hyperlipidemia in patients with increased triglyceride (TG), increased low-density lipoprotein cholesterol (LDL-C), and decreased high-density lipoprotein cholesterol (HDL-C). Mixed-effect Cox model analysis was performed to investigate the associations of the 28-days all-cause deaths of COVID-19 patients with hyperlipidemia and the abnormalities of lipid parameters. The results were verified in male, female patients, and in patients with pre-existing CVDs and type 2 diabetes.

Results

Of 10 945 inpatients confirmed as COVID-19, there were 9 822 inpatients included in the study, comprising 3513 (35.8%) cases without hyperlipidemia and 6309 (64.2%) cases with hyperlipidemia. Based on a mixed-effect Cox model after PSM at 1:1 ratio, hyperlipidemia was not associated with increased or decreased 28-day all-cause death [adjusted hazard ratio (HR), 1.17 (95% CI, 0.95-1.44), P =0.151]. We found that the parameters of hyperlipidemia were not associated with the risk of 28-day all-cause mortality [adjusted HR, 1.23 (95% CI, 0.98-1.55), P = 0.075 in TG increase group; 0.78 (95% CI, 0.57-1.07), P = 0.123 in LDL-C increase group; and 1.12 (95% CI, 0.9-1.39), P = 0.299 in HDL-C decrease group, respectively]. Hyperlipidemia was also not significantly associated with the increased mortality of COVID-19 in patients accompanied with CVDs or type 2 diabetes, and in both male and female cohorts.

Conclusion

Our study support that the imbalanced lipid profile is not significantly associated with the 28-day all-cause mortality of COVID-19 patients, even in those accompanied with CVDs or diabetes. Similar results were also obtained in subgroup analyses of abnormal lipid parameters. Therefore, hyperlipidemia might be not a major causative factor for poor outcome of COVID-19, which provides guidance for the intervention of inpatients during the epidemic of COVID-19.

High-density lipoprotein's vascular protective functions in metabolic and cardiovascular disease - could extracellular vesicles be at play?

High-density lipoprotein (HDL) is a circulating complex of lipids and proteins known primarily for its role in reverse cholesterol transport and consequent protection from atheroma. In spite of this, therapies aimed at increasing HDL concentration do not reduce the risk of cardiovascular disease (CVD), and as such focus has shifted towards other HDL functions protective of vascular health - including vasodilatory, anti-inflammatory, antioxidant and anti-thrombotic actions. It has been demonstrated that in disease states such as CVD and conditions of insulin resistance such as Type 2 diabetes mellitus (T2DM), HDL function is impaired owing to changes in the abundance and function of HDL-associated lipids and proteins, resulting in reduced vascular protection. However, the gold standard density ultracentrifugation technique used in the isolation of HDL also co-isolates extracellular vesicles (EVs). EVs are ubiquitous cell-derived particles with lipid bilayers that carry a number of lipids, proteins and DNA/RNA/miRNAs involved in cell-to-cell communication. EVs transfer their bioactive load through interaction with cell surface receptors, membrane fusion and endocytic pathways, and have been implicated in both cardiovascular and metabolic diseases - both as protective and pathogenic mediators. Given that studies using density ultracentrifugation to isolate HDL also co-isolate EVs, biological effects attributed to HDL may be confounded by EVs. We hypothesise that some of HDL's vascular protective functions in cardiovascular and metabolic disease may be mediated by EVs. Elucidating the contribution of EVs to HDL functions will provide better understanding of vascular protection and function in conditions of insulin resistance and potentially provide novel therapeutic targets for such diseases.

The role of high-density lipoprotein cholesterol, apolipoprotein A and paraoxonase-1 in the pathophysiology of neuroprogressive disorders

Lowered high-density lipoprotein (HDL) cholesterol has been reported in major depressive disorder, bipolar disorder, first episode of psychosis, and schizophrenia. HDL, its major apolipoprotein component, ApoA1, and the antioxidant enzyme paraoxonase (PON)1 (which is normally bound to ApoA1) all have anti-atherogenic, antioxidant, anti-inflammatory, and immunomodulatory roles, which are discussed in this paper. The paper details the pathways mediating the anti-inflammatory effects of HDL, ApoA1 and PON1 and describes the mechanisms leading to compromised HDL and PON1 levels and function in an environment of chronic inflammation. The molecular mechanisms by which changes in HDL, ApoA1 and PON1 might contribute to the pathophysiology of the neuroprogressive disorders are explained. Moreover, the anti-inflammatory actions of ApoM-mediated sphingosine 1-phosphate (S1P) signalling are reviewed as well as the deleterious effects of chronic inflammation and oxidative stress on ApoM/S1P signalling. Finally, therapeutic interventions specifically aimed at improving the levels and function of HDL and PON1 while reducing levels of inflammation and oxidative stress are considered. These include the so-called Mediterranean diet, extra virgin olive oil, polyphenols, flavonoids, isoflavones, pomegranate juice, melatonin and the Mediterranean diet combined with the ketogenic diet.

Glycation of HDL Polymerizes Apolipoprotein M and Attenuates Its Capacity to Bind to Sphingosine 1-Phosphate

Aim: Recently, it has been established that most of the pleiotropic effects of high-density lipoprotein (HDL) are attributed to sphingosine 1-phosphate (S1P), which rides on HDL via apolipoprotein M (ApoM). In subjects with diabetes mellitus, both the pleiotropic effects of HDL and its role in reverse cholesterol transport are reported to be impaired. To elucidate the mechanisms underlying the impaired pleiotropic effects of HDL in subjects with diabetes, from the aspects of S1P and ApoM.

Methods: The incubation of HDL in a high-glucose condition resulted in the dimerization of ApoM. Moreover, the treatment of HDL with methylglyoxal resulted in the modulation of the ApoM structure, as suggested by the results of western blot analysis, isoelectric focusing electrophoresis, and two-dimensional gel electrophoresis, which was reversed by treatment with anti-glycation reagents.

Results: The glycation of HDL resulted in impaired binding of the glycated HDL to S1P, and the S1P on glycated HDL degraded faster. In the case of human subjects, on the other hand, although both the serum ApoM levels and the ApoM content in HDL were lower in subjects with diabetes, we did not observe the polymerization of ApoM.

Conclusions: Modulation of the quantity and quality of ApoM might explain, at least in part, the impaired functions of HDL in subjects with diabetes mellitus. ApoM might be a useful target for laboratory testing and/or the treatment of diabetes mellitus.

Molecular mechanism of the anti-inflammatory effects of Sophorae Flavescentis Aiton identified by network pharmacology

Inflammation, a protective response against infection and injury, involves a variety of biological processes. Sophorae Flavescentis (Kushen) is a promising Traditional Chinese Medicine (TCM) for treating inflammation, but the pharmacological mechanism of Kushen’s anti-inflammatory effect has not been fully elucidated. The bioactive compounds, predicted targets, and inflammation-related targets of Kushen were obtained from open source databases. The “Component-Target” network and protein–protein interaction (PPI) network were constructed, and hub genes were screened out by topological analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on genes in the PPI network. Furthermore, nitric oxide (NO) production analysis, RT-PCR, and western blot were performed to detect the mRNA and protein expression of hub genes in LPS-induced RAW264.7 cells. An immunofluorescence assay found that NF-κB p65 is translocated. A total of 24 bioactive compounds, 465 predicted targets, and 433 inflammation-related targets were identified and used to construct “Component-Targets” and PPI networks. Then, the five hub genes with the highest values-IL-6, IL-1β, VEGFA, TNF-α, and PTGS2 (COX-2)- were screened out. Enrichment analysis results suggested mainly involved in the NF-κB signaling pathway. Moreover, experiments were performed to verify the predicted results. Kushen may mediate inflammation mainly through the IL-6, IL-1β, VEGFA, TNF-α, and PTGS2 (COX-2), and the NF-κB signaling pathways. This finding will provide clinical guidance for further research on the use of Kushen to treat inflammation.

Association of carbamylated high-density lipoprotein with coronary artery disease in type 2 diabetes mellitus: carbamylated high-density lipoprotein of patients promotes monocyte adhesion

BACKGROUND

Increasing evidence showed that carbamylated lipoprotein accelerated atherosclerosis. However, whether such modification of high-density lipoprotein (HDL) particles alters in type 2 diabetes mellitus (T2DM) patients and facilitates vascular complications remains unclear. We aimed to investigate the alteration of the carbamylation in HDL among T2DM patients and clarify its potential role in atherogenesis.

METHODS

A total of 148 consecutive T2DM patients undergoning angiography and 40 age- and gender-matched control subjects were included. HDL was isolated from plasma samples, and the concentration of HDL carbamyl-lysine (HDL-CBL) was measured. Furthermore, the HDL from subjects and in-vitro carbamylated HDL (C-HDL) was incubated with endothelial cells and monocyte to endothelial cell adhesion. Adhesion molecule expression and signaling pathway were detected.

RESULTS

Compared with the control group, the HDL-CBL level was remarkably increased in T2DM patients (6.13 ± 1.94 vs 12.00 ± 4.06 (ng/mg), P < 0.001). Of note, HDL-CBL demonstrated a more significant increase in T2DM patients with coronary artery disease (CAD) (n = 102) than those without CAD (n = 46) (12.75 ± 3.82 vs. 10.35 ± 4.11(ng/mg), P = 0.001). Multivariate logistic regression analysis demonstrated that higher HDL-CBL level was independently associated with a higher prevalence of CAD in diabetic patients after adjusting for established cofounders (adjusted odds ratio 1.174, 95% confidence Interval 1.045-1.319, p = 0.017). HDL from diabetic patients with CAD enhanced greater monocyte adhesion than that from the non-CAD or the control group (P < 0.001). Such pro-atherogenic capacity of diabetic HDL positively correlated with HDL-CBL level. Furthermore, in-vitro incubation of carbamylated HDL (C-HDL) with endothelial promoted monocyte to endothelial cell adhesion, induced upregulation of cell adhesion molecules expression, and activated NF-κB/p65 signaling in endothelial cells. Inhibiting carbamylation of HDL or NF-κB activation attenuated the monocyte to endothelial cell adhesion and cell surface adhesion molecules expression.

CONCLUSIONS

Our study identified elevated carbamylation modification of HDL from T2DM patients, especially in those with concomitant CAD. We also evidenced that C-HDL enhanced monocyte to endothelial cell adhesion, indicating a potential pro-atherogenic role of C-HDL in atherosclerosis among T2DM patients. Trial registration https://register.clinicaltrials.gov , NCT04390711 Registered on 14 May 2020; Retrospectively registered.

Cholesterol homeostasis: Researching a dialogue between the brain and peripheral tissues

Cholesterol homeostasis is a highly regulated process in human body because of its several functions underlying the biology of cell membranes, the synthesis of all steroid hormones and bile acids and the need of trafficking lipids destined to cell metabolism. In particular, it has been recognized that peripheral and central nervous system cholesterol metabolism are separated by the blood brain barrier and are regulated independently; indeed, peripherally, it depends on the balance between dietary intake and hepatic synthesis on one hand and its degradation on the other, whereas in central nervous system it is synthetized de novo to ensure brain physiology. In view of this complex metabolism and its relevant functions in mammalian, impaired levels of cholesterol can induce severe cellular dysfunction leading to metabolic, cardiovascular and neurodegenerative diseases. The aim of this review is to clarify the role of cholesterol homeostasis in health and disease highlighting new intriguing aspects of the cross talk between its central and peripheral metabolism.

Is HDL cholesterol protective in patients with type 2 diabetes? A retrospective population-based cohort study

BACKGROUND

The protective role of high HDL cholesterol levels against cardiovascular diseases has been recently questioned. Limited data are available on this specific topic in patients with type 2 diabetes mellitus (T2DM). We aimed to evaluate the association of HDL cholesterol concentrations with all-cause and cause-specific mortality in a historical cohort of T2DM patients with 14 years of follow-up.

METHODS

This is a retrospective population-based cohort study involving 2113 T2DM patients attending the Diabetic Clinic of Asti. Survival analyses were performed to assess hazard ratios for overall and specific-cause mortality by HDL cholesterol tertiles, using the middle HDL cholesterol tertile as a reference.

RESULTS

The mean age was 66 ± 11 years; 51.4% of patients had low HDL-cholesterol levels. After a 14-year follow-up, 973/2112 patients had died (46.1%). The HDL cholesterol tertile cut-off points were 37.5 and 47.5 mg/dL (males) and 41.5 and 52.0 mg/dL (females). No associations between lower and upper HDL cholesterol tertiles respectively and all-cause (HR = 1.12; 95% CI 0.96-1.32; HR = 1.11; 0.95-1.30), cardiovascular (HR = 0.97; 0.77-1.23; HR = 0.94; 0.75-1.18) or cancer (HR = 0.92; 0.67-1.25; HR = 0.89; 0.66-1.21) mortality were found. A significantly increased risk for infectious disease death was found both in the lower (HR = 2.62; 1.44-4.74) and the upper HDL-cholesterol tertiles (HR = 2.05; 1.09-3.85) when compared to the reference. Individuals in the upper tertile showed an increased risk for mortality due to diabetes-related causes (HR = 1.87; 1.10-3.15).

CONCLUSIONS

Our results corroborate the hypothesis that HDL cholesterol levels are nonprotective in T2DM patients. The U-shaped association between HDL-cholesterol levels and mortality associated with infectious diseases should be verified by further studies.

Apolipoprotein AI) Promotes Atherosclerosis Regression in Diabetic Mice by Suppressing Myelopoiesis and Plaque Inflammation

BACKGROUND

Despite robust cholesterol lowering, cardiovascular disease risk remains increased in patients with diabetes mellitus. Consistent with this, diabetes mellitus impairs atherosclerosis regression after cholesterol lowering in humans and mice. In mice, this is attributed in part to hyperglycemia-induced monocytosis, which increases monocyte entry into plaques despite cholesterol lowering. In addition, diabetes mellitus skews plaque macrophages toward an atherogenic inflammatory M1 phenotype instead of toward the atherosclerosis-resolving M2 state typical with cholesterol lowering. Functional high-density lipoprotein (HDL), typically low in patients with diabetes mellitus, reduces monocyte precursor proliferation in murine bone marrow and has anti-inflammatory effects on human and murine macrophages. Our study aimed to test whether raising functional HDL levels in diabetic mice prevents monocytosis, reduces the quantity and inflammation of plaque macrophages, and enhances atherosclerosis regression after cholesterol lowering.

METHODS

Aortic arches containing plaques developed in Ldlr-/- mice were transplanted into either wild-type, diabetic wild-type, or diabetic mice transgenic for human apolipoprotein AI, which have elevated functional HDL. Recipient mice all had low levels of low-density lipoprotein cholesterol to promote plaque regression. After 2 weeks, plaques in recipient mouse aortic grafts were examined.

RESULTS

Diabetic wild-type mice had impaired atherosclerosis regression, which was normalized by raising HDL levels. This benefit was linked to suppressed hyperglycemia-driven myelopoiesis, monocytosis, and neutrophilia. Increased HDL improved cholesterol efflux from bone marrow progenitors, suppressing their proliferation and monocyte and neutrophil production capacity. In addition to reducing circulating monocytes available for recruitment into plaques, in the diabetic milieu, HDL suppressed the general recruitability of monocytes to inflammatory sites and promoted plaque macrophage polarization to the M2, atherosclerosis-resolving state. There was also a decrease in plaque neutrophil extracellular traps, which are atherogenic and increased by diabetes mellitus.

CONCLUSIONS

Raising apolipoprotein AI and functional levels of HDL promotes multiple favorable changes in the production of monocytes and neutrophils and in the inflammatory environment of atherosclerotic plaques of diabetic mice after cholesterol lowering and may represent a novel approach to reduce cardiovascular disease risk in people with diabetes mellitus.

Predictive value of lymphocyte to monocyte ratio and monocyte to high-density lipoprotein ratio for acute deep vein thrombosis after total joint arthroplasty: a retrospective study

Background

Deep vein thrombosis (DVT) is one of the most dangerous complications of total joint arthroplasty (TJA). Systemic inflammation has proved to have a great contribution to thrombosis and has been considered as a risk factor for DVT recently. The lymphocyte to monocyte ratio (LMR) and monocyte to high-density lipoprotein (HDL) ratio (MHR) are two biomarkers used widely for systemic inflammation. This study aims to find out the potential predictive value of LMR and MHR for DVT after TJA.

Methods

A total of 853 patients who underwent primary TJA were finally included in this retrospective study. Acute DVT after TJA was evaluated by venography. Preoperative and postoperative LMR and MHR were calculated according to the blood routine test and blood biochemistry test. The association between LMR or MHR and DVT and their predictive value were evaluated by multiple logistic regression analysis and ROC curve respectively.

Results

Totally, 126 patients (14.8%) were diagnosed with DVT by venography. Patients with DVT had a significantly higher level of preoperative MHR (P < 0.001) and postoperative MHR (P < 0.001), along with a significantly lower level of preoperative LMR (P < 0.001) and postoperative LMR (P < 0.001). Multiple logistic regression indicated that BMI (OR = 1.10, P = 0.001), preoperative LMR (OR = 0.72, P<0.001), and postoperative LMR (OR = 0.32, P < 0.001) were independent risk factors for DVT. Besides, BMI (OR = 1.17, P = 0.001), female (OR = 4.6, P = 0.004), preoperative MHR (OR = 10.43, P = 0.008), postoperative Hb (OR = 0.96, P = 0.002), and postoperative LMR were independently associated with symptomatic DVT. The ROC curve suggested that the postoperative LMR had a potential to predict DVT after TJA.

Conclusion

In summary, the present study found out a significant association of perioperative LMR or MHR with DVT after TJA. Moreover, the postoperative LMR had a potential to predict DVT accurately.

The role and function of HDL in patients with diabetes mellitus and the related cardiovascular risk

BACKGROUND

Diabetes mellitus (DM) is a major public health problem which prevalence is constantly raising, particularly in low- and middle-income countries. Both diabetes mellitus types (DMT1 and DMT2) are associated with high risk of developing chronic complications, such as retinopathy, nephropathy, neuropathy, endothelial dysfunction, and atherosclerosis.

METHODS

This is a review of available articles concerning HDL subfractions profile in diabetes mellitus and the related cardiovascular risk. In this review, HDL dysfunction in diabetes, the impact of HDL alterations on the risk diabetes development as well as the association between disturbed HDL particle in DM and cardiovascular risk is discussed.

RESULTS

Changes in the amount of circulation lipids, including triglycerides and LDL cholesterol as well as the HDL are frequent also in the course of DMT1 and DMT2. In normal state HDL exerts various antiatherogenic properties, including reverse cholesterol transport, antioxidative and anti-inflammatory capacities. However, it has been suggested that in pathological state HDL becomes "dysfunctional" which means that relative composition of lipids and proteins in HDL, as well as enzymatic activities associated to HDL, such as paraoxonase 1 (PON1) and lipoprotein-associated phospholipase 11 (Lp-PLA2) are altered. HDL properties are compromised in patients with diabetes mellitus (DM), due to oxidative modification and glycation of the HDL protein as well as the transformation of the HDL proteome into a proinflammatory protein. Numerous studies confirm that the ability of HDL to suppress inflammatory signals is significantly reduced in this group of patients. However, the exact underlying mechanisms remains to be unravelled in vivo.

CONCLUSIONS

The understanding of pathological mechanisms underlying HDL dysfunction may enable the development of therapies targeted at specific subpopulations and focusing at the diminishing of cardiovascular risk.