Regulation of high-density lipoprotein by inflammatory cytokines: establishing links between immune dysfunction and cardiovascular disease

HDL functionality is dependent on hepatocyte stress defense factors Nrf1 and Nrf2

High density lipoproteins (HDL) promote homeostasis and counteract stressful tissue damage that underlie cardiovascular and other diseases by mediating reverse cholesterol transport, reducing inflammation, and abrogating oxidative damage. However, metabolically stressful conditions associated with atherosclerosis can impair these effects. Hepatocytes play a major role in the genesis and maturation of circulating HDL, and liver stress elicits marked regulatory changes to circulating HDL abundance and composition, which affect its functionality. The mechanisms linking liver stress to HDL function are incompletely understood. In this study, we sought to determine whether stress defending transcription factors nuclear factor erythroid 2 related factor-1 (Nrf1) and -2 (Nrf2) promote hepatocyte production of functional HDL. Using genetically engineered mice briefly fed a mild metabolically stressful diet, we investigated the effect of hepatocyte-specific deletion of Nrf1, Nrf2, or both on circulating HDL cholesterol, protein composition, and function. Combined deletion, but not single gene deletion, reduced HDL cholesterol and apolipoprotein A1 levels as well as the capacity of HDL to accept cholesterol undergoing efflux from cultured macrophages and to counteract tumor necrosis factor α-induced inflammatory effect on cultured endothelial cells. This coincided with substantial alteration to the HDL proteome, which correlated with liver gene expression profiles of corresponding proteins. Thus, our findings show complementary actions by hepatocyte Nrf1 and Nrf2 play a role in shaping HDL abundance and composition to promote production of functionally viable HDL. Consequently, our study illuminates the possibility that enhancing stress defense programming in the liver may improve atheroprotective and perhaps other health promoting actions of HDL.

Recombinant High-Density Lipoprotein Boosts the Therapeutic Efficacy of Mild Hypothermia in Traumatic Brain Injury

Traumatic brain injury (TBI) leads to neuropsychiatric symptoms and increased risk of neurodegenerative disorders. Mild hypothermia is commonly used in patients suffering from severe TBI. However, its effect for long-term protection is limited, mostly because of its insufficient anti-inflammatory and neuroprotective efficacy and restricted treatment duration. Recombinant high-density lipoprotein (rHDL), which possesses anti-inflammatory and antioxidant activity and blood-brain barrier (BBB) permeability, was expected to potentially strengthen the therapeutic effect of mild hypothermia in TBI treatment. To test this hypothesis and optimize the regimen for combination therapy, the efficacy of mild hypothermia plus concurrent or sequential rHDL on oxidative stress, inflammatory reaction, and cell survival in the damaged brain cells was evaluated. It was found that the effect of combining mild hypothermia with concurrent rHDL was modest, as mild hypothermia inhibited the cellular uptake and lesion-site-targeting delivery of rHDL. In contrast, the combination of mild hypothermia with sequential rHDL more powerfully improved the anti-inflammatory and antioxidant activities, promoted nerve cell survival and BBB restoration, and ameliorated neurologic changes, which thus remarkably restored the spatial learning and memory ability of TBI mice. Collectively, these findings suggest that rHDL may serve as a novel nanomedicine for adjunctive therapy of TBI and highlight the importance of timing of combination therapy for optimal treatment outcome.

Prognostic value of lipid profile in adult hemophagocytic lymphohistiocytosis

Background

Adult secondary hemophagocytic lymphohistiocytosis (sHLH) is a rare clinical syndrome with a high mortality rate. Currently, there are no feasible prognostic factors to clinically predict untreated sHLH patients' prognosis. Our objective was to characterize the lipid profile of adult sHLH patients and to determine the relationship with overall survival.

Methods

We retrospectively analyzed 247 patients with newly diagnosed sHLH from January 2017 to January 2022 according to the HLH-2004 criteria. Multivariate Cox regression analyses and restricted cubic splines were conducted to evaluate the prognostic value of the lipid profile.

Results

The median age of all patients was 52 years, and the commonest cause of sHLH in our cohort was malignancy. During a median follow-up of 88 (interquartile ranges, 22-490) days, 154 deaths occurred. The univariate analysis confirmed total cholesterol (TC) ≤ 3 mmol/L, triglycerides (TG) > 3.08 mmol/L, high-density lipoprotein cholesterol (HDL-c) ≤ 0.52 mmol/L, and low-density lipoprotein cholesterol (LDL-c) ≤ 2.17 mmol/L were associated with an inferior survival. In a multivariate model, HDL-c, hemoglobin, platelet, fibrinogen, and soluble interleukin-2 receptor were considered as independent factors. Additionally, the restricted cubic spline analyses indicated an inverse linear association between HDL-c and the risk of mortality in sHLH.

Conclusion

Lipid profiles, which were low-cost and readily available promising biomarkers, were strongly associated with the overall survival in adult sHLH patients.

The serum metabolomic profile of a distinct, inflammatory subtype of acute psychosis

A range of studies suggest that a proportion of psychosis may have an autoimmune basis, but this has not translated through into clinical practice-there is no biochemical test able to accurately identify psychosis resulting from an underlying inflammatory cause. Such a test would be an important step towards identifying who might require different treatments and have the potential to improve outcomes for patients. To identify novel subgroups within patients with acute psychosis we measured the serum nuclear magnetic resonance (NMR) metabolite profiles of 75 patients who had identified antibodies (anti-glycine receptor [GlyR], voltage-gated potassium channel [VGKC], Contactin-associated protein-like 2 [CASPR2], leucine-rich glioma inactivated 1 [LGI1], N-methyl-D-aspartate receptor [NMDAR] antibody) and 70 antibody negative patients matched for age, gender, and ethnicity. Clinical symptoms were assessed using the positive and negative syndrome scale (PANSS). Unsupervised principal component analysis identified two distinct biochemical signatures within the cohort. Orthogonal partial least squared discriminatory analysis revealed that the serum metabolomes of NMDAR, LGI1, and CASPR2 antibody psychosis patients were indistinct from the antibody negative control group while VGKC and GlyR antibody patients had significantly decreased lipoprotein fatty acids and increased amino acid concentrations. Furthermore, these patients had more severe presentation with higher PANSS scores than either the antibody negative controls or the NMDAR, LGI1, and CASPR2 antibody groups. These results suggest that a proportion of patients with acute psychosis have a distinct clinical and biochemical phenotype that may indicate an inflammatory subtype.

Dyslipidemia Among Adults With Congenital Heart Disease

Background

Atherosclerotic disease is an important cause of morbidity among adults with congenital heart disease (CHD). Prevalence of dyslipidemia in this group is poorly described.

Objectives

This study aimed to describe the prevalence of dyslipidemia among adults with CHD.

Methods

A prospective, outpatient screening study was conducted among adults aged ≥18 years at 4 New England ambulatory congenital cardiology centers. Participants were surveyed regarding cardiovascular risk factors. Nonfasting fingerstick samples were obtained for analysis using a point-of-care lipid analyzer.

Results

Lipid screening was completed on 186 participants (median age 30 [range 18-71] years, 50% female). Eighteen (10%) had simple CHD anatomy, and 63 (34%) had complex anatomy. Only 15% of 169 respondents reported history of high cholesterol. Eighty-five (46%) participants met National Cholesterol Education Program definition of dyslipidemia with 60 (32%), 62 (34%), and 37 (20%) having low high-density lipoprotein cholesterol (HDL-C <40 mg/dL), high non-HDL-C (≥130 mg/dL), and high total cholesterol (TC ≥200 mg/dL), respectively. TC was higher among participants with simple CHD than among those with moderate and complex lesions (mean 178.4 ± 48.7 vs 170.1 ± 35.0 vs 157.6 ± 34.5 mg/dL; P = 0.03). HDL-C was lower among participants with complex CHD than among those with simple and moderate lesions (mean 44.1 ± 13.5 vs 46.9 ± 12.5 vs 49.8 ± 15.3 mg/dL; P = 0.05).

Conclusions

Dyslipidemia is highly prevalent among our cohort of adults with CHD, despite <15% reporting a prior diagnosis. Low HDL-C was more common in complex CHD, and high TC was more common in simple or moderate CHD. Lipid screening should be part of preventive health maintenance for all adults with CHD.

Integrative Transcriptomics and Proteomics Analysis Provide a Deep Insight Into Bovine Viral Diarrhea Virus-Host Interactions During BVDV Infection

Bovine viral diarrhea virus (BVDV) is the causative agent of bovine viral diarrhea-mucosal disease (BVD-MD), an important viral disease in cattle that is responsible for extensive economic losses to the cattle industry worldwide. Currently, several underlying mechanisms involved in viral replication, pathogenesis, and evading host innate immunity of BVDV remain to be elucidated, particularly during the early stage of virus infection. To further explore the mechanisms of BVDV-host interactions, the transcriptomics and proteomics profiles of BVDV-infected MDBK cells were sequenced using RNA-seq and iTRAQ techniques, respectively, and followed by an integrative analysis. Compared with mock-infected MDBK cells, a total of 665 differentially expressed genes (DEGs) (391 down-regulated, 274 up-regulated) and 725 differentially expressed proteins (DEPs) (461 down-regulated, 264 up-regulated) were identified. Among these, several DEGs and DEPs were further verified using quantitative RT-PCR and western blot. Following gene ontology (GO) annotation and KEGG enrichment analysis, we determined that these DEGs and DEPs were significantly enriched in multiple important cellular signaling pathways including NOD-like receptor, Toll-like receptor, TNF, NF-κB, MAPK, cAMP, lysosome, protein processing in endoplasmic reticulum, lipid metabolism, and apoptosis signaling pathways. Significantly, the down-regulated DEGs and DEPs were predominantly associated with apoptosis-regulated elements, inflammatory factors, and antiviral elements that were involved in innate immunity, thus, indicating that BVDV could inhibit apoptosis and the expression of host antiviral genes to facilitate viral replication. Meanwhile, up-regulated DEGs and DEPs were primarily involved in metabolism and autophagy signaling pathways, indicating that BVDV could utilize the host metabolic resources and cell autophagy to promote replication. However, the potential mechanisms BVDV-host interactions required further experimental validation. Our data provide an overview of changes in transcriptomics and proteomics profiles of BVDV-infected MDBK cells, thus, providing an important basis for further exploring the mechanisms of BVDV-host interactions.

Cardiovascular risk factor progression in adolescents and young adults with youth-onset type 2 diabetes

AIMS

Youth-onset type 2 diabetes (T2D) confers a high risk of early adverse cardiovascular morbidity. We describe the cumulative incidence and prevalence of cardiovascular risk factors over time and examine relationships with diabetes progression in young adults with youth-onset T2D from the Treatment Options for type 2 Diabetes in Adolescents and Youth (TODAY) study.

METHODS

Longitudinal data was used to evaluate the relationships between hypertension, LDL-C dyslipidemia, hypertriglyceridemia, and smoking with risk factors in 677 participants.

RESULTS

Baseline mean age was 14 ± 2 years and mean follow-up 10.2 ± 4.5 years. The 14-year cumulative incidence of hypertension, LDL-C dyslipidemia, and hypertriglyceridemia was 59%, 33%, and 37% respectively. Average prevalence of reported smoking was 23%. Male sex, non-Hispanic white race/ethnicity, obesity, poor glycemic control, lower insulin sensitivity, and reduced beta-cell function were significantly associated with an unfavorable risk profile. At end of follow-up, 54% had ≥2 cardiovascular risk factors in addition to T2D.

CONCLUSIONS

Cardiovascular risk factor incidence and prevalence was high over a decade of follow-up in young adults with youth-onset T2D. Glucose control and management of cardiovascular risk factors is critical in youth with T2D for prevention of cardiovascular morbidity and mortality.

Glycemic control is associated with dyslipidemia over time in youth with type 2 diabetes: The SEARCH for diabetes in youth study

BACKGROUND

Dyslipidemia has been documented in youth with type 2 diabetes. There is a paucity of studies examining dyslipidemia over time in youth with type 2 diabetes and associated risk factors.

OBJECTIVE

To evaluate lipids at baseline and follow-up and associated risk factors in youth with type 2 diabetes.

METHODS

We studied 212 youth with type 2 diabetes at baseline and after an average of 7 years of follow-up in the SEARCH for Diabetes in Youth Study. Abnormal lipids were defined as high-density lipoprotein cholesterol (HDL-C) < 35, low-density lipoprotein cholesterol (LDL-C) > 100, or triglycerides >150 (all mg/dl). We evaluated participants for progression to abnormal lipids (normal lipids at baseline and abnormal at follow-up), regression (abnormal lipids at baseline and normal at follow-up), stable normal, and stable abnormal lipids over time for HDL-C, LDL-C, and triglycerides. Associations between hemoglobin A1c (HbA1c) and adiposity over time (area under the curve [AUC]) with progression and stable abnormal lipids were evaluated.

RESULTS

HDL-C progressed, regressed, was stable normal, and stable abnormal in 12.3%, 11.3%, 62.3%, and 14.2% of participants, respectively. Corresponding LDL-C percentages were 15.6%, 12.7%, 42.9%, and 28.8% and triglycerides were 17.5%, 10.8%, 55.7%, and 16.0%. Each 1% increase in HbA1c AUC was associated with a 13% higher risk of progression and stable abnormal triglycerides and a 20% higher risk of progression and stable abnormal LDL-C. Higher adiposity AUC was marginally (p = 0.049) associated with abnormal HDL-C.

CONCLUSIONS

Progression and stable abnormal LDL-C and triglycerides occur in youth with type 2 diabetes and are associated with higher HbA1c.

Fontan-Associated Dyslipidemia

Background

Hypocholesterolemia is a marker of liver disease, and patients with a Fontan circulation may have hypocholesterolemia secondary to Fontan‐associated liver disease or inflammation. We investigated circulating lipids in adults with a Fontan circulation and assessed the associations with clinical characteristics and adverse events.

Methods and Results

We enrolled 164 outpatients with a Fontan circulation, aged ≥18 years, in the Boston Adult Congenital Heart Disease Biobank and compared them with 81 healthy controls. The outcome was a combined outcome of nonelective cardiovascular hospitalization or death. Participants with a Fontan (median age, 30.3 [interquartile range, 22.8–34.3 years], 42% women) had lower total cholesterol (149.0±30.1 mg/dL versus 190.8±41.4 mg/dL, P<0.0001), low‐density lipoprotein cholesterol (82.5±25.4 mg/dL versus 102.0±34.7 mg/dL, P<0.0001), and high‐density lipoprotein cholesterol (42.8±12.2 mg/dL versus 64.1±16.9 mg/dL, P<0.0001) than controls. In those with a Fontan, high‐density lipoprotein cholesterol was inversely correlated with body mass index (r=−0.30, P<0.0001), high‐sensitivity C‐reactive protein (r=−0.27, P=0.0006), and alanine aminotransferase (r=−0.18, P=0.02) but not with other liver disease markers. Lower high‐density lipoprotein cholesterol was independently associated with greater hazard for the combined outcome adjusting for age, sex, body mass index, and functional class (hazard ratio [HR] per decrease of 10 mg/dL, 1.37; 95% CI, 1.04–1.81 [P=0.03]). This relationship was attenuated when log high‐sensitivity C‐reactive protein was added to the model (HR, 1.26; 95% CI, 0.95–1.67 [P=0.10]). Total cholesterol, low‐density lipoprotein cholesterol, and triglycerides were not associated with the combined outcome.

Conclusions

The Fontan circulation is associated with decreased cholesterol levels, and lower high‐density lipoprotein cholesterol is associated with adverse outcomes. This association may be driven by inflammation. Further studies are needed to understand the relationship between the severity of Fontan‐associated liver disease and lipid metabolism.

The Rise and Fall "ing" of the HDL Hypothesis

Earlier epidemiological studies have shown an inverse correlation between high-density lipoprotein cholesterol (HDLc) and coronary heart disease (CHD). This observation along with the finding that reverse cholesterol transport is mediated by HDL, supported the hypothesis that the HDL molecule has a cardioprotective role. More recently, epidemiological data suggest a U-shaped curve correlating HDLc and CHD. In addition, randomized clinical trials of drugs that significantly increase plasma HDLc levels, such as nicotinic acid and cholesterol ester transfer protein (CETP) inhibitors failed to show a reduction in major adverse cardiovascular events. These observations challenge the hypothesis that HDL has a cardioprotective role. It is possible that HDL quality and function is optimal only when de novo synthesis of apo A-I occurs. Inhibition of turnover of HDL with currently available agents yields HDL molecules that are ineffective in reverse cholesterol transport. To test this hypothesis, newer therapeutic drugs that increase de novo production of HDL and apo A-I should be tested in clinical trials.

In silico identification of common and specific signatures in coronary heart diseases

Coronary heart disease (CHD) is on the increase in developing countries, where lifestyle choices such as smoking, bad diet, and no exercise contribute and increase the incidence of high blood pressure and high cholesterol levels to cause CHD. Through utilization of a biomarker-based approach for developing interventions, the aim of the study was to identify differentially expressed genes (DEGs) and their association and impact on various bio-targets. The microarray datasets of both healthy and CHD patients were analyzed to identify the DEGs and their interactions using Gene Ontology, PANTHER, Reactome, and STRING (for the possible associated genes with multiple targets). Our data mining approach suggests that the DEGs were associated with molecular functions, including protein binding (75%) and catalytic activity (56%); biological processes such as cellular process (83%), biological regulation (57%), and metabolic process (44%); and cellular components such as cell (65%) and organelle (58%); as well as other associations including apoptosis, inflammatory, cell development and metabolic pathways. The molecular functions were further analyzed, and protein binding in particular was analyzed using network analysis to determine whether there was a clear association with CHD and disease. The ingenuity pathway analysis revealed pathways related to cell cholesterol biosynthesis, the immune system including cytokinin signaling, in which, the understanding of DEGs is crucial to predict the advancement of preventive strategies. Results of the present study showed that, there is a need to validate the top DEGs to rule out their molecular mechanism in heart failure caused by CHD.

Atherogenic index of plasma predicts cerebrovascular accident occurrence in antineutrophil cytoplasmic antibody-associated vasculitis

Background

To investigate whether atherogenic index of plasma (AIP) at diagnosis is associated with the occurrence of cerebrovascular accident (CVA) or coronary artery disease (CAD) in antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

Methods

The medical records of 167 AAV patients on initial diagnosis was reviewed, and 300 healthy controls were included. AIP was calculated using the following equation: AIP = Log (triglyceride [mg/dL] / high-density lipoprotein cholesterol [mg/dL]). AAV patients were divided into two groups according to the AIP cut-off of 0.11. The event of stroke, transient ischemic attack, and cerebral hemorrhage was recorded as CVA, and CAD events consisted of either myocardial infarction and angina pectoris. CVA- and CAD- free survival rate between those with AIP ≥ 0.11 and < 0.11 were compared by the Kaplan-Meier analysis, and Cox hazard analysis was conducted to identify predictors of CVA.

Results

The median age of AAV patients were 59.0 years, and 54 (32.3%) patients were male. One-hundred and fifteen (68.9%) patients had AIP < 0.11 and 52 (31.1%) had AIP ≥ 0.11. The mean Birmingham vasculitis activity score in AAV patients with AIP < 0.11 was lower than that seen in patients with AIP ≥ 0.11 (12.0 vs. 14.0, P = 0.041). AAV patients had a significantly higher AIP compared to controls (mean − 0.01 vs. -0.10, P < 0.001). During follow-up, the occurrence of CVA and CAD was observed in 16 (9.6%) and 14 (8.4%) patients, respectively. In Kaplan-Meier analysis, AAV patients with AIP ≥ 0.11 had significantly lower CVA-free survival rates than in those with AIP < 0.11 (P = 0.027), whereas there was no difference in CAD according to AIP (P = 0.390). Multivariable Cox analysis indicated that AIP ≥ 0.11 at diagnosis was the sole predictor of CVA (Hazard ratio 3.392, 95% confidence interval 1.076, 10.696, P = 0.037).

Conclusions

AIP is significantly higher in AAV patients than in healthy controls, and AIP ≥ 0.11 at diagnosis is a significant predictor of CVA during follow-up. Stringent surveillance should be provided in AAV patients with AIP ≥ 0.11 regarding the occurrence of CVA.

Trial registration

Retrospectively registered (4–2017-0673).

The Effects of Anthocyanins and Their Microbial Metabolites on the Expression and Enzyme Activities of Paraoxonase 1, an Important Marker of HDL Function

High circulating HDL concentrations and measures of various HDL functions are inversely associated with cardiovascular disease (CVD) risk. Paraoxonase 1 (PON1) contributes to many of the athero-protective functions of HDL, such as promoting the reverse cholesterol transport process and reducing the levels of oxidized LDL. PON1 activities are influenced by several factors, the most important being diet and genetic polymorphisms. Reported data from randomized controlled trials have shown that anthocyanin consumption increased PON1 activity. However, the underlying molecular mechanisms by which anthocyanins increase PON1 activity are not understood. Therefore, the aim of this research was to investigate the ability of anthocyanins and their metabolites to increase PON1 gene expression and/or enzyme activities as potential mechanisms. The effect of the two predominant dietary anthocyanins and 18 of their recently identified microbial metabolites including their phase-II conjugates on PON1 gene expression was studied using a PON1-Huh7 stably-transfected cell line and reporter gene assay. The effects of these compounds on PON1 arylesterase and lactonase activities were investigated using two isoforms of the PON1 enzyme that are the phenotypes of the 192Q/R polymorphism. None of the compounds caused even modest changes in PON1 promoter activity (p ≥ 0.05). Further, none of the compounds at physiological concentrations caused any significant changes in the arylesterase or lactonase activity of either of the iso-enzymes. Cyanidin reduced the lactonase activity of the PON1-R192R enzyme at high concentrations (−22%, p < 0.001), but not at physiologically achievable concentrations. In conclusion, none of the data reported here support the notion that anthocyanins or their metabolites affect PON1 transactivation or enzyme activities.

Metabolic Regulators Nampt and Sirt6 Serially Participate in the Macrophage Interferon Antiviral Cascade

Molecular determinants underlying interferon (IFN)-macrophage biology can help delineate enzyme systems, pathways and mechanisms for enabling host-directed therapeutic approaches against infection. Notably, while the IFN antiviral response is known to be directly coupled to mevalonate-sterol biosynthesis, mechanistic insight for providing host pathway-therapeutic targets remain incomplete. Here, we show that Nampt and Sirt6 are coordinately regulated upon immune activation of macrophages and contribute to the IFN-sterol antiviral response. In silico analysis of the Nampt and Sirt6 promoter regions identified multiple core immune gene-regulatory transcription factor sites, including Stat1, implicating a molecular link to IFN control. Experimentally, we show using a range of genetically IFN-defective macrophages that the expression of Nampt is stringently regulated by the Jak/Stat-pathway while Sirt6 activation is temporally displaced in a partial IFN-dependent manner. We further show that pharmacological inhibition of Nampt and small interfering RNA (siRNA)-mediated inhibition of Nampt and Sirt6 promotes viral growth of cytomegalovirus in both fibroblasts and macrophages. Our results support the notion of pharmacologically exploiting immune regulated enzyme systems of macrophages for use as an adjuvant-based therapy for augmenting host protective pathway responses to infection.

Nonmelanoma skin cancer and risk of all-cause and cancer-related mortality: a systematic review

Some reports suggest that a history of nonmelanoma skin cancer (NMSC) may be associated with increased mortality. NMSCs have very low fatality rates, but the high prevalence of NMSC elevates the importance of the possibility of associated subsequent mortality from other causes. The variable methods and findings of existing studies leave the significance of these results uncertain. To provide clarity, we conducted a systematic review to characterize the evidence on the associations of NMSC with: (1) all-cause mortality, (2) cancer-specific mortality, and (3) cancer survival. Bibliographic databases were searched through February 2016. Cohort studies published in English were included if adequate data were provided to estimate mortality ratios in patients with-versus-without NMSC. Data were abstracted from the total of eight studies from independent data sources that met inclusion criteria (n = 3 for all-cause mortality, n = 2 for cancer-specific mortality, and n = 5 for cancer survival). For all-cause mortality, a significant increased risk was observed for patients with a history of squamous cell carcinoma (SCC) (mortality ratio estimates (MR) 1.25 and 1.30), whereas no increased risk was observed for patients with a history of basal cell carcinoma (BCC) (MRs 0.96 and 0.97). Based on one study, the association with cancer-specific mortality was stronger for SCC (MR 2.17) than BCC (MR 1.15). Across multiple types of cancer both SCC and BCC tended to be associated with poorer survival from second primary malignancies. Multiple studies support an association between NMSC and fatal outcomes; the associations tend to be more potent for SCC than BCC. Additional investigation is needed to more precisely characterize these associations and elucidate potential underlying mechanisms.

The Distribution of Apolipoprotein E Gene Polymorphism and Apolipoprotein E Levels among Coronary Artery Patients Compared to Controls

OBJECTIVE

Coronary artery disease (CAD) is a multifactorial disease that is caused by various genetics and environmental factors. Genetically, predisposition is an important component for CAD. The candidate apolipoprotein E (apoE) gene is the most studied one. ApoE is composed of e2, e3, e4 alleles and E2/2, E2/3, E2/4, E3/3, E3/4, E4/4 genotypes. In this study, the relationship between CAD and apoE polymorphism and apoE level has been studied in Tokat region.

MATERIALS AND METHODS

The study population is composed of 100 CAD patients diagnosed by coronary angiography and 100 control patients of whom fifty have normal coronary angiography and fifty did not have any CAD symptoms. The serum lipid and apoE levels and apoE genotypes of all participants have been measured, and the relationship between these parameters has been evaluated.

RESULTS

Apolipoprotein E, total cholesterol, HDL cholesterol and LDL cholesterol levels were statistically low at CAD patients than control patients (p=0.0004, p=0.0005, p=0.0107, p=0.0052 respectively). There was not any significant difference between triglyceride levels (p=0.0848). Waist circumferences were significantly high at CAD patients (p=0.0012). Allele frequencies were as e2 (7.25%), e3 (83.5%), e4 (9.25%) and genotype distributions were as E2/2 (0.5%), E2/3 (13%), E2/4 (0.5%), E3/3 (68.5%), E3/4 (16.5%), E4/4 (1%). The distribution of alleles and genotypes were not significantly different (p>0.05). ApoE levels were higher at e2 allele carriers than e3 and e4 allele carriers (p<0.05). However, there was no significant difference between e3 and e4 allele carriers.

CONCLUSION

In conclusion, the distribution of apoE genotype and allele at our region is similar to the general of Turkey. The low apoE levels in CAD patients may show the influence of apoE on CAD by local and systemic mechanisms.

'Bedside assessment' of acute hantavirus infections and their possible classification into the spectrum of haemophagocytic syndromes

Hantavirus infections, recently renamed 'hantavirus fever' (HTVF), belong to the most common but also most underestimated zoonoses in the world. A small number of reports described the so-called 'lipid paradox' in HTVF, i.e. the striking contrast between a very low serum total cholesterol and/or high-density lipoprotein cholesterol (HDLc), and a paradoxical concomitant hypertriglyceridaemia. In a prospective study, with patients being their own control after illness, we wanted to verify if this quick and easy 'bedside test' was robust enough to warrant a preliminary diagnosis of acute kidney injury (AKI) caused by HTVF. The study cohort consisted of 58 Belgian cases (mean age 44 years), admitted with varying degrees of AKI and of thrombocytopaenia, both characteristic for presumptive HTVF. All cases were sero-confirmed as having acute HTVF. At or shortly after hospital admission, a significant (p < 0.001) decrease of total cholesterol and HDLc was found in comparison with normalised levels in the same cohort, quantified a few days after spontaneous AKI recovery. Conversely, fasting triglyceride levels during HTVF infection were significantly (p < 0.001) higher during illness than after recovery. This 'lipid paradox' was most outspoken in severe HTVF cases, often accompanying, or even predicting, major kidney or lung complications. Thus, this 'bedside assessment' seems to hold even promise for presumptive diagnosis of more severe so-called 'hantavirus cardio-pulmonary syndrome' (HCPS) cases, mostly described hitherto in the New World. In more severe AKI cases, the mean total cholesterol was significantly lower (p = 0.02) than in milder cases, i.e. cases with peak serum creatinine levels of < 1.5 mg/dL. Thrombocytopaenia, generally accepted as the severity index in HTVF, appeared, moreover, significantly correlated with serum levels of total cholesterol (R = 0.52, p < 0.001) and with serum levels of HDLc (R = 0.45, p < 0.01). A link with the novel clinical entity of haemophagocytic syndromes, also characterised by manifest hypertriglyceridaemia, is discussed.

Levels of High-Density Lipoprotein Cholesterol are Associated With Biomarkers of Inflammation in Patients With Acute Coronary Syndrome

Pathologic conditions associated with inflammation show an inverse correlation between high-density lipoprotein cholesterol (HDL-C) and inflammatory biomarker levels. Our aim was to investigate, in patients with acute coronary syndrome (ACS), whether very low HDL-C levels are associated with inflammatory biomarkers. In a cross-sectional study, we included 6,134 patients with ACS; they were classified as having very low (<30 mg/dl), low (30 to 39.9 mg/dl), and normal HDL-C (≥ 40 mg/dl) levels. We analyzed the association of different categories of HDL-C levels with serum levels of inflammatory biomarkers, high-sensitivity C-reactive protein (hs-CRP), albumin, and white blood cell count at admission. Overall, 18.5% of patients had very low HDL-C levels. Patients with very low HDL-C levels, compared to patients with low or normal HDL-C levels, had the highest hs-CRP (median 17.8 [interquartile range 7.2 to 54.5] vs 12.6 [5.6 to 33.9] vs 12.0 [5.4 to 36.9] mg/L, respectively, p <0.001) and the lowest albumin levels (median 3.6 [IQR 3.3 to 4.0] vs 3.8 [3.5 to 4.0] vs 3.8 [3.5 to 4.1] g/dl, respectively, p <0.001). White blood cell count did not differ significantly (p = 0.40). The multivariate analysis showed that albumin ≤ 3.5 g/dl (odds ratio 2.16, 95% confidence interval 1.88 to 2.49, p <0.001) and hs-CRP ≥ 10 mg/L (odds ratio 1.35, 95% confidence interval 1.17 to 1.55, p <0.001) were independent predictors of very low HDL-C levels. Patients with very low HDL-C levels had the highest inhospital mortality rates compared with the other groups. In conclusion, in patients with ACS, hs-CRP and serum albumin were associated independently with very low HDL-C levels.

Childhood hospitalisation with infection and cardiovascular disease in early-mid adulthood: a longitudinal population-based study

Background

Pathogen-specific and overall infection burden may contribute to atherosclerosis and cardiovascular disease (CVD), but the effect of infection severity and timing is unknown. We investigated whether childhood infection-related hospitalisation (IRH, a marker of severity) was associated with subsequent adult CVD hospitalisation.

Methods

Using longitudinal population-based statutorily-collected administrative health data from Western Australia (1970-2009), we identified adults hospitalised with CVD (ischaemic heart disease, ischaemic stroke, and peripheral vascular disease) and matched them (10:1) to population controls. We used Cox regression to assess relationships between number and type of childhood IRH and adulthood CVD hospitalisation, adjusting for sex, age, Indigenous status, socioeconomic status, and birth weight.

Results

631 subjects with CVD-related hospitalisation in adulthood (≥ 18 years) were matched with 6310 controls. One or more childhood (< 18 years) IRH was predictive of adult CVD-related hospitalisation (adjusted hazard ratio, 1.3; 95% CI 1.1-1.6; P < 0.001). The association showed a dose-response; ≥ 3 childhood IRH was associated with a 2.2 times increased risk of CVD-related hospitalisation in adulthood (adjusted hazard ratio, 2.2; 95% CI 1.7-2.9; P < 0.001). The association was observed across all clinical diagnostic groups of infection (upper respiratory tract infection, lower respiratory tract infection, infectious gastroenteritis, urinary tract infection, skin and soft tissue infection, and other viral infection), and individually with CVD diagnostic categories (ischaemic heart disease, ischaemic stroke and peripheral vascular disease).

Conclusions

Severe childhood infection is associated with CVD hospitalisations in adulthood in a dose-dependent manner, independent of population-level risk factors.

Induction of apolipoprotein A-I gene expression by black seed (Nigella sativa) extracts

CONTEXT

Black seed [Nigella sativa L. (Ranunculaceae)] has been shown in animal models to lower serum cholesterol levels.

OBJECTIVES

In order to determine if extracts from black seed have any effects on high-density lipoprotein (HDL), we characterized the effects of black seed extract on apolipoprotein A-I (apo A-I) gene expression, the primary protein component of HDL.

MATERIALS AND METHODS

Hepatocytes (HepG2) and intestinal cells (Caco-2) were treated with black seed extracts, and Apo A-I, peroxisome proliferator-activated receptor α (PPARα), and retinoid-x-receptor α (RXRα) were measured by Western blot analysis. Apo A-I mRNA levels were measured by quantitative real-time polymerase chain reaction and apo A-I gene transcription was measured by transient transfection of apo A-I reporter plasmids.

RESULTS

Extracts from black seeds significantly increased hepatic and intestinal apo A-I secretion, as well as apo A-I mRNA and gene promoter activity. This effect required a PPARα binding site in the apo A-I gene promoter. Treatment of the extract with either heat or trypsin had no effect on its ability to induce apo A-I secretion. Treatment with black seed extract induced PPARα expression 9-fold and RXRα expression 2.5-fold. Furthermore, the addition of PPARα siRNA but not a control siRNA prevented some but not all the positive effects of black seed on apo A-I secretion.

DISCUSSION

Black seed extract is a potent inducer of apo A-I gene expression, presumably by enhancing PPARα/RXRα expression.

CONCLUSIONS

We conclude that black seed may have beneficial effects in treating dyslipidemia and coronary heart disease.

The effect of nutritional supplements on serum high-density lipoprotein cholesterol and apolipoprotein A-I

One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol. Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). Diet has an important role in modulating HDL cholesterol level. The widespread use of nutritional supplements may also alter the biology of HDL. In this review, we discuss the effect of select nutritional supplements on serum HDL cholesterol and apo A-I levels. Some nutritional supplements, such as phytosterols, soy proteins, and black seed extracts, may increase HDL cholesterol levels, while others such as cholic acid and high doses of commonly used antioxidant vitamins may downregulate HDL cholesterol levels and reduce its cardioprotection. Multiple mechanisms are involved in the regulation of HDL levels, so changes in production and clearance of HDL may have different clinical implications. The clinical relevance of the changes in HDL and apo A-I caused by nutrient supplementation needs to be tested in controlled clinical trials.

Human plasma lipid modulation in schistosomiasis mansoni depends on apolipoprotein E polymorphism

Background

Schistosomiasis mansoni is a parasitic liver disease, which causes several metabolic disturbances. Here, we evaluate the influence of Apolipoprotein E (APOE) gene polymorphism, a known modulator of lipid metabolism, on plasma lipid levels in patients with hepatosplenic schistosomiasis.

Methodology/Principal Findings

Blood samples were used for APOE genotyping and to measure total cholesterol (TC), LDL-C, HDL-C and triglycerides. Schistosomiasis patients had reduced TC, LDL-C and triglycerides (25%, 38% and 32% lower, respectively; P<0.0001) compared to control individuals, whereas HDL-C was increased (10% higher; P = 0.0136). Frequency of the common alleles, ε2, ε3 and ε4, was similar (P = 0.3568) between controls (n = 108) and patients (n = 84), implying that APOE genotype did not affect susceptibility to the advanced stage of schistosomiasis. Nevertheless, while patient TC and LDL-C levels were significantly reduced for each allele (except TC in ε2 patients), changes in HDL-C and triglycerides were noted only for the less common ε2 and ε4 alleles. The most striking finding, however, was that accepted regulation of plasma lipid levels by APOE genotype was disrupted by schistosomiasis. Thus, while ε2 controls had higher TC and LDL-C than ε3 carriers, these parameters were lower in ε2 versus ε3 patients. Similarly, the inverse relationship of TG levels in controls (ε2>ε3>ε4) was absent in patients (ε2 or ε4>ε3), and the increase in HDL-C of ε2 or ε4 patients compared to ε3 patients was not seen in the control groups.

Conclusion/Significance

We confirm that human schistosomiasis causes dyslipidemia and report for the first time that certain changes in plasma lipid and lipoprotein levels depend on APOE gene polymorphism. Importantly, we also concluded that S. mansoni disrupts the expected regulation of plasma lipids by the different ApoE isoforms. This finding suggests ways to identify new metabolic pathways affected by schistosomiasis and also potential molecular targets to treat associated morbidities.

The relationship between epicardial fat and indices of obesity and the metabolic syndrome: a systematic review and meta-analysis

Epicardial fat (epicardial adipose tissue, EAT) has been implicated in the pathogenesis of coronary artery disease (CAD). The objective of this study was to examine the relationship between EAT and generalized obesity, central or visceral adipose tissue (VAT), and the components of the metabolic syndrome--systolic blood pressure (SBP), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), and fasting blood glucose (FBG)--that are linked to CAD. A systematic review of the literature, following meta-analysis guidelines, was conducted until May, 2013, using the search strategy "Obesity" OR "abdominal obesity" OR "metabolic syndrome" OR "metabolic syndrome X" AND "epicardial fat". Thirty-eight studies fulfilled the criteria. There was a highly significant (P<0.00001) correlation between EAT and body mass index (BMI), waist circumference (WC), or VAT. The correlation between EAT and VAT was significantly (P<0.0001) greater than the correlation between EAT and WC, which in turn was significantly greater than the correlation between EAT and BMI. Overall, EAT was 7.5 ± 0.1 mm in thickness in the metabolic syndrome (n=427) compared to 4.0 ± 0.1 mm in controls (n=301). EAT correlated significantly (P<0.0001) with SBP, TGs, HDL, and FBG, but the strength of the association was less than one-half of the relationship of EAT to indices of obesity. The results of multivariate analysis were less consistent but show a relationship between EAT and metabolic syndrome independent of BMI. In summary, the very strong correlation between EAT and VAT suggests a relationship between these two adipose tissue depots. Measurement of EAT can be useful to indicate VAT. Whereas EAT correlates significantly with each of the components of the metabolic syndrome- SBP, TGs, HDL, or FBG-the magnitude of the relationship is considerably and significantly less than the relationship of EAT to BMI. These data show the strong relationship between EAT and BMI but especially with WC and VAT. They also demonstrate the smaller magnitude of the association of EAT with standard coronary risk factors, related to the metabolic syndrome, and suggest that the unique features of this adipose tissue warrant detailed investigation.

Role of HDL in cholesteryl ester metabolism of lipopolysaccharide-activated P388D1 macrophages

Infections share with atherosclerosis similar lipid alterations, with accumulation of cholesteryl esters (CEs) in activated macrophages and concomitant decrease of cholesterol-HDL (C-HDL). Yet the precise role of HDL during microbial infection has not been fully elucidated. Activation of P388D1 by lipopolysaccharide (LPS) triggered an increase of CEs and neutral lipid contents, along with a remarkable enhancement in 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-HDL uptake. Similar results were found in human monocyte-derived macrophages and monocytes cocultured with phytohemagglutinin-activated lymphocytes. Inhibition of cholesterol esterification with Sandoz-58035 resulted in 80% suppression of CE biosynthesis in P388D1. However, only a 35% decrease of CE content, together with increased scavenger receptor class B member 1 (SR-B1) protein expression, was found after 72 h and thereafter up to 16 passages of continuous ACAT suppression. Chronic inhibition blunted the effect of LPS treatment on cholesterol metabolism, increased the ratio of free cholesterol/CE content and enhanced interleukin 6 secretion. These results imply that, besides de novo biosynthesis and acquisition by LDL, HDL contributes probably through SR-B1 to the increased CE content in macrophages, partly explaining the low levels of C-HDL during their activation. Our data suggest that in those conditions where more CEs are required, HDL rather than removing, may supply CEs to the cells.

Partial restoration of macrophage alteration from diet-induced obesity in response to Porphyromonas gingivalis infection

Obesity is a chronic inflammatory disease that weakens macrophage innate immune response to infections. Since M1 polarization is crucial during acute infectious diseases, we hypothesized that diet-induced obesity inhibits M1 polarization of macrophages in the response to bacterial infections. Bone marrow macrophages (BMMΦ) from lean and obese mice were exposed to live Porphyromonas gingivalis (P. gingivalis) for three incubation times (1 h, 4 h and 24 h). Flow cytometry analysis revealed that the M1 polarization was inhibited after P. gingivalis exposure in BMMΦ from obese mice when compared with BMMΦ from lean counterparts. Using a computational approach in conjunction with microarray data, we identified switching genes that may differentially control the behavior of response pathways in macrophages from lean and obese mice. The two most prominent switching genes were thrombospondin 1 and arginase 1. Protein expression levels of both genes were higher in obese BMMΦ than in lean BMMΦ after exposure to P. gingivalis. Inhibition of either thrombospondin 1 or arginase 1 by specific inhibitors recovered the M1 polarization of BMMΦ from obese mice after P. gingivalis exposure. These data indicate that thrombospondin 1 and arginase 1 are important bacterial response genes, whose regulation is altered in macrophages from obese mice.

Proteomic profiling for the identification of serum diagnostic biomarkers for abdominal and thoracic aortic aneurysms

BACKGROUND

Aortic aneurysm is an increasingly common vascular disorder with fatal implication. However, there is no established diagnosis other than that based on aneurysmal size. For this purpose, serum protein biomarkers for aortic aneurysms are valuable. Although most of the studies on serum biomarker discovery have been based on comparison of serum proteins from the patient group with those from the healthy group, we considered that comparison of serial protein profiles such as those in presurgical and postsurgical sera within one patient would facilitate identification of biomarkers since the variability of serial protein profiles within one patient is smaller than that between groups. In this study, we examined serum proteins with differential levels in postsurgery compared with those in presurgery after the removal of aneurysmal tissues in abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA) patients in order to identify potential serum biomarkers for AAAs and TAAs.

RESULTS

A proteomic approach with an isobaric tag for relative and absolute quantitation (iTRAQ) labeling followed by nano liquid chromatography (nanoLC)-matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF/TOF)-tandem mass spectrometry (MS/MS) was used. In the sera of patients with AAAs and TAAs, a total of 63 and 71 proteins with differential levels were further narrowed down to 6 and 8 increased proteins (≧1.3 fold, postsurgical vs. presurgical) (p < 0.05, patient vs. control) and 12 and 17 decreased proteins (< 0.77 fold, postsurgical vs. presurgical) (p < 0.05, patient vs. control) in postsurgical sera compared with those in presurgical sera, respectively. All of the increased proteins in postsurgical sera of both AAA and TAA patients included several known acute-phase proteins. On the other hand, in the decreased proteins, we found intriguing molecules such as α-2-macroglobulin, gelsolin, kallistatin, and so on. Among them, we confirmed that kallistatin in both AAA and TAA patients and α-2-macroglobulin in TAA patients showed decrease levels in postsurgical sera similar to those in control sera by Western blot analysis with other sera from AAA and TAA patients.

CONCLUSIONS

Taken together, our findings suggest that Kallistatin and α-2-macroglobulin are potential serum biomarkers for both AAA and TAA and TAA, respectively.

High-density lipoprotein: a novel marker for risk of in-hospital infection in acute ischemic stroke patients?

BACKGROUND

Several studies have shown that high-density lipoprotein (HDL) cholesterol provides protection against bacterial infections. Our aim was to investigate the influence of HDL cholesterol levels on the risk of developing in-hospital infectious complications after an acute ischemic stroke (IS) as well as the possible effect of prestroke statin treatment on this association.

METHODS AND RESULTS

Observational study that included consecutive IS patients during a 5-year period (2006-2010). We analyzed vascular risk factors, prestroke treatments (including statins), laboratory data (including HDL cholesterol levels), stroke severity, and the development of infectious complications (pneumonia, urinary tract infection and sepsis). A multivariate analysis that included HDL cholesterol levels, prior statin treatment and the interaction between both variables was performed to identify those factors associated with the presence of infectious complications. A total of 1,385 patients were included, 130 of whom (9.4%) developed in-hospital infections. The receiver operating characteristic curve showed the predictive value of HDL cholesterol with an area under the curve of 0.597 (95% CI, 0.526-0.668; p = 0.006) and pointed to 38.5 mg/dl of HDL cholesterol (65.5% sensitivity and 53.4% specificity) as the optimal cutoff level for developing infectious complications during hospitalization. An HDL cholesterol level ≥38.5 mg/dl was an independent predictive factor for lower risk of infection (OR 0.308; 95% CI 0.119-0.795), whereas prestroke statin treatment was not associated with the development of infection.

CONCLUSIONS

An HDL cholesterol level ≥38.5 mg/dl was independently associated with lower risk for developing infectious complications in acute IS patients. Statins do not influence this association.

Induction of apolipoprotein A-I gene expression by glucagon-like peptide-1 and exendin-4 in hepatocytes but not intestinal cells

OBJECTIVE

Diabetic dyslipidemia is an important risk factor for the development of macrovascular complications. Recent clinical trials suggest that diabetics treated with glucagon-like peptide-1 (GLP-1) have normalized lipid levels, including an increase in plasma high-density lipoprotein cholesterol (HDLc) levels.

METHODS

To determine if GLP-1 (7-36 amide) and the GLP-1-like insulinotropic peptide exendin-4 regulate expression of apolipoprotein A-I (apo A-I), the primary anti-atherogenic component of high-density lipoprotein (HDL), HepG2 hepatocytes and Caco-2 intestinal cells, representative of tissues that express the majority of apo A-I, were treated with increasing amounts of each peptide and apo A-I gene expression was measured in the conditioned medium.

RESULTS

Apo A-I secretion increased in both GLP-1 and exendin-4-treated HepG2, but not Caco-2 cells, and this was accompanied by similar changes in apo A-I mRNA levels and apo A-I promoter activity. Induction of apo A-I promoter activity by GLP-1 and exendin-4 required an SP1-responsive element. Hepatic ATP binding cassette protein A1 (ABCA1) expression, but not scavenger receptor class B type1 receptor expression was also induced by GLP-1 and exendin-4.

CONCLUSIONS

These results suggest that GLP-1- and exendin-4-mediated changes in HDLc are likely due to changes in hepatic expression of apo A-I and ABCA1.

Microcirculation and atherothrombotic parameters in prolactinoma patients: a pilot study

Atherothrombosis is a multifactorial process, governed by an interaction between the vessel wall, hemodynamic factors and systemic atherothrombotic risk factors. Recent in vitro, human ex vivo and animal studies have implicated the hormone prolactin as an atherothrombotic mediator. To address this issue, we evaluated the anatomy and function of various microvascular beds as well as plasma atherothrombosis markers in patients with elevated prolactin levels. In this pilot study, involving 10 prolactinoma patients and 10 control subjects, sidestream dark field (SDF) imaging revealed a marked perturbation of the sublingual microcirculation in prolactinoma patients compared to control subjects, as attested to by significant changes in microvascular flow index (2.74 ± 0.12 vs. 2.91 ± 0.05, respectively; P = 0.0006), in heterogeneity index (0.28 [IQR 0.18-0.31] vs. 0.09 [IQR 0.08-0.17], respectively; P = 0.002) and lower proportion of perfused vessels (90 ± 4.0% vs. 95 ± 3.0%, respectively; P = 0.016). In the retina, fluorescein angiography (FAG) confirmed these data, since prolactinoma patients more often have dilatated perifoveal capillaries. In plasma, prolactinoma patients displayed several pro-atherogenic disturbances, including a higher endogenous thrombin potential and prothrombin levels as well as decreased HDL-cholesterol levels. Prolactinoma patients are characterized by microvascular dysfunction as well as plasma markers indicating a pro-atherothrombotic state. Further studies are required to assess if prolactin is causally involved in atherothrombotic disease.

Deletion of scavenger receptor A gene in mice resulted in protection from septic shock and modulation of TLR4 signaling in isolated peritoneal macrophages

Scavenger receptor A (Sra), also known as macrophage scavenger receptor 1 (Msr1), is a surface glycoprotein preferentially present in macrophages that plays a primary role in innate immunity. Previous studies have shown that Sra is a modifier gene for the response to bacterial LPS in mice at the level of IL-10 production, in particular. In the present study, we found that Sra(-/-) mice are more resistant to septic shock induced by cecal ligation and puncture than wild-type C57BL/6 J (B6) mice. In addition, Sra(-/-) mice displayed initial elevated high density lipoprotein (HDL) circulating levels. Naïve peritoneal macrophages (PMs) were isolated from Sra(-/-) mice to understand the possible protective mechanism. Incubation of these cells with LPS was found to modulate TLR4 signaling, leading to a reduction in IL-10 and IL-6 mRNA levels, but not TNF-α expression, at low concentrations of LPS in comparison with PMs isolated from B6 mice. No differences were found in LPS binding between PMs derived from Sra(-/-) or B6 mice. The lack of Sra binding to LPS was confirmed after transfection of Chinese hamster ovary (CHO) cells with the Sra gene. The contribution of Sra to the outcome of sepsis may be a combination of changes in TLR4 signaling pathway and elevated levels of HDL in circulation, but also LPS toxicity.

Endothelial expression of human ABCA1 in mice increases plasma HDL cholesterol and reduces diet-induced atherosclerosis

The role of endothelial ABCA1 expression in reverse cholesterol transport (RCT) was examined in transgenic mice, using the endothelial-specific Tie2 promoter. Human ABCA1 (hABCA1) was significantly expressed in endothelial cells (EC) of most tissues except the liver. Increased expression of ABCA1 was not observed in resident peritoneal macrophages. ApoA-I-mediated cholesterol efflux from aortic EC was 2.6-fold higher (P < 0.0001) for cells from transgenic versus control mice. On normal chow diet, Tie2 hABCA1 transgenic mice had a 25% (P < 0.0001) increase in HDL-cholesterol (HDL-C) and more than a 2-fold increase of eNOS mRNA in the aorta (P < 0.04). After 6 months on a high-fat, high-cholesterol (HFHC) diet, transgenic mice compared with controls had a 40% increase in plasma HDL-C (P < 0.003) and close to 40% decrease in aortic lesions (P < 0.02). Aortas from HFHC-fed transgenic mice also showed gene expression changes consistent with decreased inflammation and apoptosis. Beneficial effects of the ABCA1 transgene on HDL-C levels or on atherosclerosis were absent when the transgene was transferred onto ApoE or Abca1 knockout mice. In summary, expression of hABCA1 in EC appears to play a role in decreasing diet-induced atherosclerosis in mice and is associated with increased plasma HDL-C levels and beneficial gene expression changes in EC.

Extracellular modifications of HDL in vivo and the emerging concept of proteolytic inactivation of preβ-HDL

PURPOSE OF REVIEW

Both quantity and quality of the circulating HDL particle matter for the optimal antiatherogenic potential of HDL. This review summarizes various mechanisms capable of inducing extracellular modifications of HDL and reducing the function of HDL subclasses as cholesterol acceptors. Special emphasis is laid on the proteolytic inactivation of lipid-poor preβ-migrating HDL (preβ-HDL).

RECENT FINDINGS

HDL particles can undergo functional inactivation in vivo. During atherogenesis, different cell types in the arterial intima release enzymes into the intimal fluid, potentially capable of causing structural and chemical modifications of the various components present in the lipid core or in the polar surface of the HDL particles. Enzymatic oxidation, lipolysis and proteolysis, and nonenzymatic glycosylation are among the HDL modifications that adversely affect HDL functionality. Proteolysis of preβ-HDL by various proteases present in the arterial intima has emerged as a potential mechanism that impairs the efficiency of HDL to promote cholesterol efflux from macrophage foam cells, the mast cell-derived neutral protease chymase being a prime example of such impairment. A paradigm of proteolytic inactivation of preβ-HDL in vivo is emerging.

SUMMARY

Several extracellular enzymes present in the arterial intima may compromise various cardioprotective functions of HDL. Observations on proteolysis of specific lipid-poor HDL subpopulations in vivo constitute the basis for future studies evaluating the actual impact of proteolytic microenvironments on the initiation and progression of atherosclerotic lesions.

Particular human leukocyte antigen alleles are associated with biochemical traits in the Japanese population

We analyzed genetic associations among 7 biochemical traits (fasting plasma glucose, HbA1c, total cholesterol, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein cholesterol, triglyceride, and uric acid) and 6 HLA loci using 1,616 individuals who visited the Health Evaluation and Promotion Center at Tokai University Hospital. Significant differences between the individuals carrying particular HLA alleles and those not carrying the alleles in certain biochemical traits were observed by Mann-Whitney U test. In female subjects, DPB1*03:01 was significantly associated with HbA1c (p = 0.0000665), and DRB1*14:03 was associated with total cholesterol concentration (p = 0.0015). In male subjects, C*14:02 demonstrated significant associations with fasting plasma glucose with p values of 0.0041. By contrast, Fisher's exact test indicated that female DRB1*14:03 was associated with a high concentration of total cholesterol (p = 000323, odds ratio [OR] = 4.32, 95% confidence interval [95% CI] = 1.83-10.36), whereas female DPB1*02:01 had a protective effect against a high concentration of LDL cholesterol (p =0.0043, OR = 0.41, 95% CI = 0.19-0.79). These associations have a statistical power of more than 0.8 and still retain significance after Bonferroni correction.

Host defense against viral infection involves interferon mediated down-regulation of sterol biosynthesis

Little is known about the protective role of inflammatory processes in modulating lipid metabolism in infection. Here we report an intimate link between the innate immune response to infection and regulation of the sterol metabolic network characterized by down-regulation of sterol biosynthesis by an interferon regulatory loop mechanism. In time-series experiments profiling genome-wide lipid-associated gene expression of macrophages, we show a selective and coordinated negative regulation of the complete sterol pathway upon viral infection or cytokine treatment with IFNγ or β but not TNF, IL1β, or IL6. Quantitative analysis at the protein level of selected sterol metabolic enzymes upon infection shows a similar level of suppression. Experimental testing of sterol metabolite levels using lipidomic-based measurements shows a reduction in metabolic output. On the basis of pharmacologic and RNAi inhibition of the sterol pathway we show augmented protection against viral infection, and in combination with metabolite rescue experiments, we identify the requirement of the mevalonate-isoprenoid branch of the sterol metabolic network in the protective response upon statin or IFNβ treatment. Conditioned media experiments from infected cells support an involvement of secreted type 1 interferon(s) to be sufficient for reducing the sterol pathway upon infection. Moreover, we show that infection of primary macrophages containing a genetic knockout of the major type I interferon, IFNβ, leads to only a partial suppression of the sterol pathway, while genetic knockout of the receptor for all type I interferon family members, ifnar1, or associated signaling component, tyk2, completely abolishes the reduction of the sterol biosynthetic activity upon infection. Levels of the proteolytically cleaved nuclear forms of SREBP2, a key transcriptional regulator of sterol biosynthesis, are reduced upon infection and IFNβ treatment at both the protein and de novo transcription level. The reduction in srebf2 gene transcription upon infection and IFN treatment is also found to be strictly dependent on ifnar1. Altogether these results show that type 1 IFN signaling is both necessary and sufficient for reducing the sterol metabolic network activity upon infection, thereby linking the regulation of the sterol pathway with interferon anti-viral defense responses. These findings bring a new link between sterol metabolism and interferon antiviral response and support the idea of using host metabolic modifiers of innate immunity as a potential antiviral strategy.