Evidence for a role of tumor necrosis factor alpha in disturbances of triglyceride and glucose metabolism predisposing to coronary heart disease

Exploring the bi-directional relationship between periodontitis and dyslipidemia: a comprehensive systematic review and meta-analysis

AIM

As periodontitis and dyslipidemia are diseases that occur with high incidence, the relationship between them has attracted much attention. Previous studies on these diseases have tended to focus on lipid parameters and periodontitis, we aimed to investigate the relationship between dyslipidemia and periodontitis.

MATERIALS AND METHODS

A comprehensive search to identify the studies investigating the relationship between dyslipidemia and periodontitis was performed on PubMed, Web of Science and Cochrane Library before the date of August, 2023. Studies were considered eligible if they contained data on abnormal blood lipid parameters and periodontitis. Studies that reported mean differences and 95% confidence intervals or odds ratios were used.

RESULTS

A total of 73 publications were included in the meta-analysis. Hyper total cholesterol (TC), triglycerides (TGs), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL) and lower high-density lipoprotein (HDL) levels are risk factors for periodontitis. Periodontal disease is a risk factor for high TG and low HDL levels. Three months after periodontal treatment, the levels of TC, TG and HDL were significantly improved, and statin treatment only improved gingival index (GI) levels compared to that of the dietary control.

CONCLUSIONS

The findings reported here suggest that the mutual promotion of periodontitis and dyslipidemia can be confirmed. Non-surgical periodontal therapy may improve lipid abnormalities. It can't be demonstrated whether systematic application of statins have a better effect on the improvement in periodontal status in patients with dyslipidemia compared to that of the control.

The alterations of innate immunity and enhanced severity of infections in diabetes mellitus

Diabetes mellitus (DM) is a metabolic inflammatory disease with a high incidence worldwide. Patients with DM are at a high risk for all types of infections. Type 1 DM is characterised with immune destruction of pancreatic β cells, while type 2 diabetes is characterised with insulin resistance and β cell dysfunction, both of which result in disorders of glucose and lipid metabolism. This metabolic disorder causes functional defects of immune cells, aberrant production of inflammatory cytokines, dysregulated immune responses, advanced pathophysiological injury of the body, and increased mortality in populations with DM upon infections. Starting with the change of natural immune system in patients with DM, this paper focused on the enhanced severity of infections in DM and the underlying innate immune alterations in preclinical and clinical studies, aiming to better understand the influence of DM on the susceptibility, pathophysiology, and clinical outcomes in infections.

[Alteration and significance of serum lipid levels and nutritional status during BCMA-CAR-T-cell therapy in patients with refractory or relapsed multiple myeloma: a retrospective study based on LEGEND-2]

Objective: To explore the dynamic changes in serum lipid levels and nutritional status during BCMA-CAR-T-cell therapy in patients with refractory or relapsed multiple myeloma (R/R MM) based on LEGEND-2. Methods: The data of patients with R/R MM who underwent BCMA-CAR-T therapy at our hospital between March 30, 2016, and February 6, 2018, were retrospectively collected. Serum lipid levels, controlled nutritional status (CONUT) score, and other clinical indicators at different time points before and after CAR-T-cell infusion were compared and analyzed. The best cut-off value was determined by using the receiver operator characteristic (ROC) curve. The patients were divided into high-CONUT score (>6.5 points, malnutrition group) and low-CONUT score groups (≤6.5 points, good nutrition group), comparing the progression-free survival (PFS) and total survival (OS) of the two groups using Kaplan-Meier survival analysis. Results: Before the infusion of CAR-T-cells, excluding triglycerides (TG), patients' serum lipid levels were lower than normal on average. At 8-14 d after CAR-T-cell infusion, serum albumin (ALB), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and apolipoprotein A1 (Apo A1) levels dropped to the minimum, whereas CONUT scores reached the maximum. In addition to TG, apolipoprotein B (Apo B) levels increased compared with baseline. After CAR-T-cell therapy, the patients' serum lipid levels significantly increased with well-improved nutritional status. Spearman's related analysis showed that TC, HDL, and ApoA1 levels after CAR-T-cell injection were significantly negatively correlated with the grade of cytokine-release syndrome (CRS) (r=-0.548, P=0.003; r=-0.444, P=0.020; r=-0.589, P=0.001). Furthermore, survival analysis indicated that the CONUT score was unrelated to PFS, and the median OS of patients with R/R MM in the high-CONUT score group was shorter than that in the low-CONUT score group (P=0.046) . Conclusions: During CAR-T-cell therapy, hypolipidemia and poor nutritional status were aggravated, which is possibly related to CRS. The patients' serum lipid levels and nutritional status were significantly improved after CAR-T-cell treatment. The CONUT score affected the median OS in patients treated with CAR-T-cells. Therefore, specific screening and intervention for nutritional status in patients receiving CAR-T-cell therapy are required.

Clinical Features of Acute Coronary Syndrome in Patients with Coronary Heart Disease and Its Correlation with Tumour Necrosis Factor in Cardiology

Tumour necrosis factor (TNF) levels are higher in patients who have experienced an acute ischemic stroke. Greater levels of TNF may not be linked to an increased risk of recurrent coronary events in the stable phase after myocardial ischemia (MI). Coronary atheroma is connected to endothelial and smooth muscle cells, as well as macrophages that emit the multifunctional cytokine tumour necrosis factor (TNF). Transplanted tumours become more vulnerable when TNF-α was first recognized to have a function in hemorrhagic necrosis. TNF-α has been demonstrated to induce heart failure, pulmonary edoema, and cardiomyopathy in people with advanced heart failure when it is elevated in the bloodstream. It has been postulated that prolonged overexpression of TNF-α after ischemia may contribute to poor cardiac outcomes by increasing TNF-α when the myocardium undergoes both temporary ischemia and reperfusion. A rise in TNF levels has been seen after a myocardial infarction, but it is unclear if these higher levels, found months after the initial event, are associated with an increased risk of subsequent heart attacks. We looked at TNF levels in the blood of 270 patients with coronary heart disease in the Chinese Hypertension League's Cholesterol and Recurrent Events (CARE) experiment to see if this notion held true. Recurrent coronary syndrome and coronary mortality were monitored prospectively in the participants. The min max imbalance normalization can be used to assess a patient's baseline characteristics, including hormone and cholesterol test results. Type 2 stimulant connection to aggregate the TNF-signaling qualities and fuzzy techniques was applied. There may now be enough preliminary evidence from the crucial bundle neural network analysis to identify the risk of coronary heart disease associated with TNF pregeneration studies. The tests were assessed using a variety of methods and performance metrics in a Matlab environment.

Associations among serum insulin, calprotectin, and C-reactive protein concentrations in Miniature Schnauzers with idiopathic hyperlipidemia before and after feeding an ultra-low-fat diet

Background

Miniature Schnauzers (MS) commonly have idiopathic hypertriglyceridemia (HTGL), which is associated with insulin resistance (IR) and a subclinical inflammatory phenotype.

Objectives

Determine the association between indicators of IR and inflammatory biomarkers in MS with and without HTGL and identify how indicators of IR are affected by dietary intervention in MS with HTGL.

Animals

Seventy MS with HTGL and 79 MS without HTGL. In addition, 15 MS with HTGL were placed on a low‐fat diet.

Methods

Serum concentrations of triglycerides, cholesterol, calprotectin, insulin, and glucose were compared between groups.

Results

Serum glucose and calprotectin concentrations (shown to be higher in MS with HTGL than in MS without HTGL) were inversely correlated (ρ = −.28; P < .001). After dietary intervention, median serum insulin concentrations were 8.1 mU/L compared to 20.8 mU/L before dietary intervention (P = .06). Dogs with complete resolution of HTGL after dietary intervention (5 dogs) had significantly lower serum insulin concentrations compared to baseline (P = .03).

Conclusion and Clinical Importance

The subclinical inflammatory phenotype in MS with HTGL appears to be associated with IR. Resolution of HTGL by dietary intervention is associated with a decrease in serum insulin concentrations. The implication of the increase in serum calprotectin concentrations after resolution of HTGL warrants further study.

Association of Adipose Tissue and Adipokines with Development of Obesity-Induced Liver Cancer

Obesity is rapidly dispersing all around the world and is closely associated with a high risk of metabolic diseases such as insulin resistance, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD), leading to carcinogenesis, especially hepatocellular carcinoma (HCC). It results from an imbalance between food intake and energy expenditure, leading to an excessive accumulation of adipose tissue (AT). Adipocytes play a substantial role in the tumor microenvironment through the secretion of several adipokines, affecting cancer progression, metastasis, and chemoresistance via diverse signaling pathways. AT is considered an endocrine organ owing to its ability to secrete adipokines, such as leptin, adiponectin, resistin, and a plethora of inflammatory cytokines, which modulate insulin sensitivity and trigger chronic low-grade inflammation in different organs. Even though the precise mechanisms are still unfolding, it is now established that the dysregulated secretion of adipokines by AT contributes to the development of obesity-related metabolic disorders. This review focuses on several obesity-associated adipokines and their impact on obesity-related metabolic diseases, subsequent metabolic complications, and progression to HCC, as well as their role as potential therapeutic targets. The field is rapidly developing, and further research is still required to fully understand the underlying mechanisms for the metabolic actions of adipokines and their role in obesity-associated HCC.

IL-29 promoted obesity-induced inflammation and insulin resistance

Adipocyte-macrophage crosstalk plays a critical role to regulate adipose tissue microenvironment and cause chronic inflammation in the pathogenesis of obesity. Interleukin-29 (IL-29), a member of type 3 interferon family, plays a role in host defenses against microbes, however, little is known about its role in metabolic disorders. We explored the function of IL-29 in the pathogenesis of obesity-induced inflammation and insulin resistance. We found that serum IL-29 level was significantly higher in obese patients. IL-29 upregulated IL-1β, IL-8, and monocyte chemoattractant protein-1 (MCP-1) expression and decreased glucose uptake and insulin sensitivity in human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes through reducing glucose transporter 4 (GLUT4) and AKT signals. In addition, IL-29 promoted monocyte/macrophage migration. Inhibition of IL-29 could reduce inflammatory cytokine production in macrophage-adipocyte coculture system, which mimic an obese microenvironment. In vivo, IL-29 reduced insulin sensitivity and increased the number of peritoneal macrophages in high-fat diet (HFD)-induced obese mice. IL-29 increased M1/M2 macrophage ratio and enhanced MCP-1 expression in adipose tissues of HFD mice. Therefore, we have identified a critical role of IL-29 in obesity-induced inflammation and insulin resistance, and we conclude that IL-29 may be a novel candidate target for treating obesity and insulin resistance in patients with metabolic disorders.

The Dual Role of Surfactant Protein-D in Vascular Inflammation and Development of Cardiovascular Disease

Cardiovascular disease (CVD) is responsible for 31% of all global deaths. Atherosclerosis is the major cause of cardiovascular disease and is a chronic inflammatory disorder in the arteries. Atherosclerosis is characterized by the accumulation of cholesterol, extracellular matrix, and immune cells in the vascular wall. Recently, the collectin surfactant protein-D (SP-D), an important regulator of the pulmonary immune response, was found to be expressed in the vasculature. Several in vitro studies have examined the role of SP-D in the vascular inflammation leading to atherosclerosis. These studies show that SP-D plays a dual role in the development of atherosclerosis. In general, SP-D shows anti-inflammatory properties, and dampens local inflammation in the vessel, as well as systemic inflammation. However, SP-D can also exert a pro-inflammatory role, as it stimulates C-C chemokine receptor 2 inflammatory blood monocytes to secrete tumor necrosis-factor α and increases secretion of interferon-γ from natural killer cells. In vivo studies examining the role of SP-D in the development of atherosclerosis agree that SP-D plays a proatherogenic role, with SP-D knockout mice having smaller atherosclerotic plaque areas, which might be caused by a decreased systemic inflammation. Clinical studies examining the association between SP-D and cardiovascular disease have reported a positive association between circulatory SP-D level, carotid intima-media thickness, and coronary artery calcification. Other studies have found that circulatory SP-D is correlated with increased risk of both total and cardiovascular disease mortality. Both in vitro, in vivo, and clinical studies examining the relationship between SP-D and CVDs will be discussed in this review.

Combination therapy with cilostazol and pravastatin improves antiatherogenic effects in low-density lipoprotein receptor knockout mice

AIMS

Despite the therapeutic efficacy of statins and antiplatelet agents for atherosclerosis, monotherapy with each drug alone is often insufficient to achieve the patient's therapeutic goals. We previously showed that combined statin/antiplatelet agent/anti-tumor necrosis factor (TNF) agent therapy (pravastatin/sarpogrelate/etanercept) reduces atherosclerotic lesions by inhibiting TNF, an atherogenic cytokine that contributes to the progression of arteriosclerosis. In addition, our previous study showed that combined treatment with pravastatin and cilostazol is effective for reducing TNF-driven inflammation through anti-TNF activity. Therefore, in the present study, we evaluated the additive effects of combined pravastatin and cilostazol therapy on atherosclerotic progression using low-density lipoprotein receptor (LDLR) knockout (KO) mice.

METHODS

Ten-week-old LDLR KO mice were fed a high-fat, high-cholesterol diet and orally administered pravastatin and cilostazol alone or in combination. Body weight, plasma lipid levels, and the levels of intracellular adhesion molecules and inflammatory cytokines were analyzed. In addition, aortas and aortic roots were stained with Oil Red O, and atherosclerotic plaques were quantified.

RESULTS

The atherosclerotic plaques in the combined pravastatin and cilostazol treatment groups were significantly reduced compared to those in each drug monotherapy group. The combination therapy group also showed the downregulation of ICAM-1, MOMA-2, TNF, interleukin (IL)-6, triglyceride, total cholesterol, and low-density lipoprotein levels and the upregulation of high-density lipoprotein levels compared to those of the pravastatin- or cilostazol-treated groups.

CONCLUSIONS

Our results suggest that combination therapy with pravastatin and cilostazol exerts beneficial effects by decreasing atherosclerotic lesion progression and improving the pro-inflammatory state in the vascular endothelium. These effects are mediated by the reduction in adhesion molecule expression, immune cell infiltration, and cytokine levels and the antiatherosclerotic modulation of serum cholesterol levels. Therefore, we conclude that combined treatment with pravastatin and cilostazol may be a more effective antiatherosclerotic strategy than treatment with either agent alone.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

Green Tea Polyphenol Epigallocatechin-3-gallate Suppresses Toll-like Receptor 4 Expression via Up-regulation of E3 Ubiquitin-protein Ligase RNF216

Toll-like receptor 4 (TLR4) plays an essential role in innate immunity through inflammatory cytokine induction. Recent studies demonstrated that the abnormal activation of TLR4 has a pivotal role in obesity-induced inflammation, which is associated with several diseases, including hyperinsulinemia, hypertriglyceridemia, and cardiovascular disease. Here we demonstrate that (-)-epigallocatechin-3-O-gallate, a natural agonist of the 67-kDa laminin receptor (67LR), suppressed TLR4 expression through E3 ubiquitin-protein ring finger protein 216 (RNF216) up-regulation. Our data indicate cyclic GMP mediates 67LR agonist-dependent RNF216 up-regulation. Moreover, we show that the highly absorbent 67LR agonist (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG3″Me) significantly attenuated TLR4 expression in the adipose tissue. EGCG3″Me completely inhibited the high-fat/high-sucrose (HF/HS)-induced up-regulation of tumor necrosis factor α in adipose tissue and serum monocyte chemoattractant protein-1 increase. Furthermore, this agonist intake prevented HF/HS-induced hyperinsulinemia and hypertriglyceridemia. Taken together, 67LR presents an attractive target for the relief of obesity-induced inflammation.

Effects of High Protein and Balanced Diets on Lipid Profiles and Inflammation Biomarkers in Obese and Overweight Women at Aerobic Clubs: A Randomized Clinical Trial

BACKGROUND

We studied the effects of high protein (HP) and balanced diets (BDs) on lipid profiles, and high-sensitive C-reactive protein (hs-CRP) levels in obese and overweight women.

METHODS

In a parallel designed randomized controlled clinical trial, 60 healthy women with body mass index ≥25 kg/m², aged 20-46 years, enrolled in an 8-week investigation at aerobic clubs. They were categorized into two groups (HP and BDs), randomly. Fasting lipid profile and hs-CRP levels were evaluated at the beginning and end of the trial. We assessed dietary intake by 3-day records and also used SPSS (version 18; SPSS Inc., Chicago, IL, USA) for data analyzing.

RESULTS

Fifty-six participants completed the intervention. Concentrations of low-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.023 in HP group) and high-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.002 in HP group) increased significantly in both groups. Circulating triglycerides levels increased in both intervention grows, but the change in the HP group was not significant compared with the other group (P = 0.007 in BD group vs. P =0.099 in HP group). Whereas total cholesterol concentration decreased but not significantly so (P = 0.53 in BD group vs. P =0.73 in HP group). There were marginally significant decreases in the hs-CRP levels due to both diets (P = 0.057 in BD group vs. P =0.086 in HP group); however, there were no significant differences between the groups.

CONCLUSIONS

Administration of HP and BD in overweight and obese women with regular aerobic exercise showed improvement in lipid profiles and hs-CRP levels within the groups, but there were no significant differences between groups.

Association of the -1031T>C polymorphism and soluble TNF-α levels with Acute Coronary Syndrome

INTRODUCTION

Inflammation has gained a pivotal role in the pathophysiology of Acute Coronary Syndrome (ACS). TNF-α is a pro-inflammatory cytokine that could be a potential biomarker in ACS due to its multiple functions. The rs1799964 TNFA polymorphism (-1031T>C) has been associated with a decrease in gene transcription and cytokine levels.

OBJECTIVE

To determine the association of rs1799964 TNFA polymorphism and TNF-α soluble levels in ACS.

METHODS

A total of 251 patients diagnosed with ACS and 164 individuals without cardiovascular diseases classified as the reference group (RG), were included. The rs1799964 polymorphism was genotyped by PCR-RFLP. Soluble protein levels were determined by ELISA. Statistical analyses were performed using chi square and U-Mann Whitney tests.

RESULTS

The genotype and allele frequencies were different between ACS and RG (OR=0.317, p=0.01; OR=0.688, p=0.03 respectively). ACS patients had higher soluble TNF-α levels compared with the RG (31.08 vs 23.00pg/mL, p<0.001); according genotype significant differences were observed (T/T: 24.06 vs T/C: 34.95pg/mL, p=0.0001) in patients. In the RG, T/T carriers showed discrete lower levels than C/C genotype (22.14 vs 27.83pg/mL, p=0.04).

CONCLUSIONS

The -1031C allele of the TNFA polymorphism confers protection for the development of ACS. The T/C genotype carriers had higher TNF-α serum levels compared to the T/T genotype in ACS. In addition, the -1031T>C TNFA polymorphism was associated with dyslipidemia in ACS in a Western Mexican population.

Nutrigenetics of cholesterol metabolism: observational and dietary intervention studies in the postgenomic era

Cholesterol metabolism is a well-defined responder to dietary intakes and a classic biomarker of cardiovascular health. For this reason, circulating cholesterol levels have become key in shaping nutritional recommendations by health authorities worldwide for better management of cardiovascular disease, a leading cause of mortality and one of the most costly health problems globally. Data from observational and dietary intervention studies, however, highlight a marked between-individual variability in the response of cholesterol metabolism to similar dietary protocols, a phenomenon linked to genetic heterogeneity. This review summarizes the postgenomic evidence of polymorphisms within cholesterol-associated genes relative to fasting circulating cholesterol levels under diverse nutritional conditions. A number of cholesterol-related gene-diet interactions are confirmed, which may have clinical importance, supporting a deeper look into the rapidly emerging field of nutrigenetics for meaningful conclusions that may eventually lead to genetically targeted dietary recommendations in the era of personalized nutrition.

Inflammation in coronary artery disease

Coronary artery disease (CAD) is the leading cause of death in the United States. Although CAD was formerly considered a lipid accumulation-mediated disease, it has now been clearly shown to involve an ongoing inflammatory response. Advances in basic science research have established the crucial role of inflammation in mediating all stages of CAD. Today, there is convincing evidence that multiple interrelated immune mechanisms interact with metabolic risk factors to initiate, promote, and ultimately activate lesions in the coronary arteries. This review aims to provide current evidence pertaining to the role of inflammation in the pathogenesis of CAD and discusses the impact of inflammatory markers and their modification on clinical outcomes.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Obesity and its metabolic complications: the role of adipokines and the relationship between obesity, inflammation, insulin resistance, dyslipidemia and nonalcoholic fatty liver disease

Accumulating evidence indicates that obesity is closely associated with an increased risk of metabolic diseases such as insulin resistance, type 2 diabetes, dyslipidemia and nonalcoholic fatty liver disease. Obesity results from an imbalance between food intake and energy expenditure, which leads to an excessive accumulation of adipose tissue. Adipose tissue is now recognized not only as a main site of storage of excess energy derived from food intake but also as an endocrine organ. The expansion of adipose tissue produces a number of bioactive substances, known as adipocytokines or adipokines, which trigger chronic low-grade inflammation and interact with a range of processes in many different organs. Although the precise mechanisms are still unclear, dysregulated production or secretion of these adipokines caused by excess adipose tissue and adipose tissue dysfunction can contribute to the development of obesity-related metabolic diseases. In this review, we focus on the role of several adipokines associated with obesity and the potential impact on obesity-related metabolic diseases. Multiple lines evidence provides valuable insights into the roles of adipokines in the development of obesity and its metabolic complications. Further research is still required to fully understand the mechanisms underlying the metabolic actions of a few newly identified adipokines.

Lifestyle modification and endothelial function in obese subjects

The metabolic syndrome is a cluster of metabolic and vascular abnormalities that include central obesity, insulin resistance, hyperinsulinemia, glucose intolerance, hypertension, dyslipidemia, hypercoagulability and an increased risk of coronary and cerebral vascular disease. These metabolic and vascular abnormalities are the main cause of cardiovascular mortality in western societies. Endothelial dysfunction, an early step in the development of atherosclerosis, has been reported in obese nondiabetic individuals and in patients with Type 2 diabetes. It has also been observed in individuals at high risk for Type 2 diabetes, including those with impaired glucose tolerance and the normoglycemic first-degree relatives of Type 2 diabetic patients. Recent evidence points to adipocytes as a complex and active endocrine tissue whose secretory products, including free fatty acids and several cytokines (i.e., leptin, adiponectin, tissue necrosis factor-alpha, interleukin-6, and resistin) play a major role in the regulation of human metabolic and vascular biology. These adipocytokines have been claimed to be the missing link between insulin resistance and cardiovascular disease. Interventions designed to improve endothelial and/or adipose-tissue functions may reduce cardiovascular events in obese individuals with either the metabolic syndrome or Type 2 diabetes. Lifestyle modification in the form of caloric restriction and increased physical activity are the most common modalities used for treating those individuals at risk and is unanimously agreed to be the initial step in managing Type 2 diabetes. Several recent studies have demonstrated favorable impacts of lifestyle modifications in improving endothelial function and insulin sensitivity, in addition to altering serum levels of adipocytokines and possibly reducing cardiovascular events. This review discusses current knowledge of the role of lifestyle modifications in ameliorating cardiovascular risk in obese subjects with either the metabolic syndrome or Type 2 diabetes.

Inflammatory biomarkers for predicting cardiovascular disease

The pathology of cardiovascular disease (CVD) is complex; multiple biological pathways have been implicated, including, but not limited to, inflammation and oxidative stress. Biomarkers of inflammation and oxidative stress may serve to help identify patients at risk for CVD, to monitor the efficacy of treatments, and to develop new pharmacological tools. However, due to the complexities of CVD pathogenesis there is no single biomarker available to estimate absolute risk of future cardiovascular events. Furthermore, not all biomarkers are equal; the functions of many biomarkers overlap, some offer better prognostic information than others, and some are better suited to identify/predict the pathogenesis of particular cardiovascular events. The identification of the most appropriate set of biomarkers can provide a detailed picture of the specific nature of the cardiovascular event. The following review provides an overview of existing and emerging inflammatory biomarkers, pro-inflammatory cytokines, anti-inflammatory cytokines, chemokines, oxidative stress biomarkers, and antioxidant biomarkers. The functions of each biomarker are discussed, and prognostic data are provided where available.

Metabolic syndrome in French HIV-infected patients: prevalence and predictive factors after 3 years of antiretroviral therapy

Treatment of HIV infection with highly active antiretroviral therapy can induce metabolic complications and increase the risk of developing the metabolic syndrome (MS). The purpose of this study was to report the prevalence and the risk factors for MS in HIV-infected patients who started highly active antiretroviral therapy (HAART) after 2000. SYMET is a prospective, multicentric, cohort study evaluating the prevalence of MS in 269 patients who had received continuous HAART for 1 to 4 years up to September 2007. MS was defined according to the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute (NHLBI) 2005 criteria. Cross-sectional assessment included clinical examination and fasting evaluation of metabolic, inflammatory, and oxidative parameters. Data were analyzed with Chi-square, Student, or Wilcoxon tests. Univariate and multivariate logistic regressions were performed to identify predictive factors for MS. The prevalence of MS was 18.2% after a median duration of HAART of 29.8 months. In multivariate analysis, predictive factors of MS were high non-HDL-cholesterol (OR=1.87; p<0.0001), high-sensitivity C-reactive protein levels (hsCRP) (OR=1.56; p=0.01), coinfection with hepatitis C virus (HCV) (OR=5.67; p=0.02), as well as age (OR=1.04; p=0.02) and duration of exposure to protease inhibitors (PI) (OR=1.03; p=0.02) or to abacavir (ABC) (OR=1.03; p=0.02). In this cohort of patients exposed to less than 4 years of HAART, MS prevalence was 18.2%. Older age, high hsCRP, HCV coinfection, and elevated non-HDL-cholesterol were risk factors for the MS. There was also a moderate significant association of increased risk of MS with cumulative PI and ABC exposure.

Metabolic syndrome: a brain disease

Recent research indicates an association between brain dysfunction and the pathogenesis of metabolic syndrome. To investigate this, we created a Medline search (up to December 2011) of articles in PubMed. The results indicated that refined carbohydrates, saturated and total fat, high levels of ω-6 fatty acids, and low levels of ω-3 fatty acids and other long chain polyunsaturated fatty acids (PUFA), all in conjunction with sedentary behaviour and mental stress can predispose to inflammation. Increased sympathetic activity, with increased secretion of catecholamine, cortisol, and serotonin can cause oxidative stress, which may damage the arcuate nucleus as well as the hypothalamus and macrophages, and the liver may release pro-inflammatory cytokines. These, in conjunction with an underlying deficiency in long chain PUFA, may damage the arcuate nucleus as well as neuropeptide-Y and pro-opiomelanocortin neurons and insulin receptors in the brain, especially during fetal life, infancy, and childhood, resulting in their dysfunction. Of the fatty acids in the brain, 30%-50% are long chain PUFA, which are incorporated in the cell membrane phospholipids. Hence, ω-3 fatty acids, which are also known to enhance parasympathetic activity and increase the secretion of anti-inflammatory cytokines interleukin (IL)-4 and IL-10 as well as acetylcholine in the hippocampus, may be protective. Therefore, treatment with ω-3 fatty acids may be applied for the prevention of metabolic syndrome.

Inflammation and metabolic dysfunction: links to cardiovascular diseases

Abdominal obesity is a major risk factor for cardiovascular disease, and recent studies highlight a key role of adipose tissue dysfunction, inflammation, and aberrant adipokine release in this process. An increased demand for lipid storage results in both hyperplasia and hypertrophy, finally leading to chronic inflammation, hypoxia, and a phenotypic change of the cellular components of adipose tissue, collectively leading to a substantially altered secretory output of adipose tissue. In this review we have assessed the adipo-vascular axis, and an overview of adipokines associated with cardiovascular disease is provided. This resulted in a first list of more than 30 adipokines. A deeper analysis only considered adipokines that have been reported to impact on inflammation and NF-κB activation in the vasculature. Out of these, the most prominent link to cardiovascular disease was found for leptin, TNF-α, adipocyte fatty acid-binding protein, interleukins, and several novel adipokines such as lipocalin-2 and pigment epithelium-derived factor. Future work will need to address the potential role of these molecules as biomarkers and/or drug targets.

Inflammation and type 2 diabetes

Low-grade inflammation is a common feature in subjects with type 2 diabetes (T2D). Heart disease, the metabolic syndrome and T2D all have in common the increased concentration of circulatory cytokines as a result of inflammation. Inflammatory cytokines are produced by different cell types and secreted into the circulation, where they regulate different tissues through their local, central and peripheral actions. This review focuses on C-reactive protein (CRP), a well-established marker of the development of inflammation, on tumour necrosis factor (TNF)-α, an inflammatory marker strongly associated with diabetes, and on adiponectin, a cytokine produced by adipose tissue and associated with insulin sensitivity. While it is clear from the literature that these cytokines play a major role in the development of T2D or, in the case of adiponectin, its prevention, the best strategy for favourably altering the inflammatory response is still a matter of debate.

A closer look at the role of urotensin II in the metabolic syndrome

Urotensin II (UII) is a vasoactive peptide that was first discovered in the teleost fish, and later in mammals and humans. UII binds to the G protein coupled receptor GPR14 (now known as UT). UII mediates important physiological and pathological actions by interacting with its receptor. The metabolic syndrome (MetS) is described as cluster of factors such as obesity, dyslipidemia, hypertension, and insulin resistance (IR), further leading to development of type 2 diabetes mellitus and cardiovascular diseases. UII levels are upregulated in patients with the MetS. Evidence directly implicating UII in every risk factor of the MetS has been accumulated. The mechanism that links the different aspects of the MetS relies primarily on IR and inflammation. By directly modulating both of these factors, UII is thought to play a central role in the pathogenesis of the MetS. Moreover, UII also plays an important role in hypertension and hyperlipidemia thereby contributing to cardiovascular complications associated with the MetS.

NF-κB regulates MICA gene transcription in endothelial cell through a genetically inhibitable control site

Endothelial cells form a barrier between blood and the underlying vessel wall, which characteristically demonstrates inflammatory damage in atherosclerotic disease. MICA is a highly polymorphic ligand for the activating immune receptor NKG2D and can be expressed on endothelial cells. We hypothesized that damaged vessel walls, such as those involved in atherosclerosis, might express MICA, which could contribute to the vascular immunopathology. Immune activation resulting from MICA expression could play a significant role in the development of vascular damage. We have demonstrated that TNFα up-regulates MICA on human endothelial cells. The up-regulation is mediated by NF-κB, and we have defined the regulatory control site responsible for this at -130 bp upstream of the MICA transcription start site. This site overlaps with a heat shock response element and integrates input from the two pathways. We have shown that in atherosclerotic lesions there is expression of MICA on endothelial cells. Using lentivirus-mediated gene delivery in primary human endothelial cells, we were able to inhibit the MICA response to TNFα with a truncated HSF1 that lacked a transactivation domain. This highlights the potential for transcription-based therapeutic approaches in atherosclerotic vascular disease to reduce immune-mediated endothelial and vessel wall damage.

Effect of pomegranate seed oil on serum TNF-α level in dyslipidemic patients

Pomegranate punicic acid and pomegranate fruit extracts have the potential effects in inhibiting tumour necrosis factor-α (TNF-α) and inflammatory diseases. The aim of this study was to evaluate the effect of pomegranate seed oil (PSO) consumption on serum TNF-α level in dyslipidemic patients. Fifty-one subjects with serum total cholesterol concentration >200 mg/dl and serum triglyceride concentrations >150 mg/dl were randomly assigned into the PSO (n = 25) and placebo (n = 26) groups. Subjects were given 400 mg PSO or placebo capsules twice daily for 4 weeks. Six patients were excluded because of complications or lack of compliance. Serum TNF-α level was measured at baseline and after 4 weeks. Mean (SD) serum concentration of TNF-α decreased from 14.73 ± 5.25 to 13.28 ± 3.79 pg/ml in the PSO group (P = NS). Corresponding values in the placebo group were 12.46 ± 1.67 versus 13.14 ± 1.67 pg/ml (P = NS). In conclusion, administration of PSO in dyslipidemic patients does not affect the serum TNF-α.

Pollock oil supplementation modulates hyperlipidemia and ameliorates hepatic steatosis in mice fed a high-fat diet

Background

Hyperlipidemia associated with obesity is closely related to the development of atherosclerosis. Both n-3 polyunsaturated fatty acids (PUFAs) and long-chain monounsaturated fatty acids (MUFAs; i.e., C20:1 and C22:1 isomers) supplementation modulate risk factors for metabolic syndrome via multiple mechanisms, including the restoration of impaired lipid metabolism. We therefore examined the effects of pollock oil, which contains a considerable amount of n-3 PUFAs as well as long-chain MUFAs, on plasma hyperlipidemia and hepatic steatosis in diet-induced obese mice.

Methods

Male C57BL/6J mice (24-26 g) were divided into two groups (n = 10/group) and were fed a high-fat diet containing 32% lard (control group) or 17% lard plus 15% pollock oil (experimental group) for 6 weeks. For both groups, fat comprised 60% of the total caloric intake.

Results

Although body and liver masses for the two groups did not differ significantly, hepatic lipids concentrations (triglycerides and total cholesterols) were lower (P < 0.05) after pollock oil ingestion. After 2 weeks on the specified diets, plasma lipid levels (total cholesterol, LDL cholesterol, and triglycerides) significantly decreased (P < 0.05) in the experimental group compared with the control group, although plasma HDL cholesterol levels did not differ. At the end of 6 weeks, plasma adiponectin levels increased (P < 0.05), whereas plasma resistin and leptin levels decreased (P < 0.05) in the experimental mice. Increased levels of long-chain MUFAs and n-3 PUFAs in plasma, liver and adipose tissue by ingesting pollock oil were possibly correlated to these favorable changes. Expression of hepatic genes involved in cholesterol metabolism (SREBP2, HMGCR, and ApoB) and lipogenesis (SREPB1c, SCD-1, FAS, and Acacα) was suppressed in the experimental group, and may have favorably affected hyperlipidemia and hepatic steatosis induced by the high-fat diet.

Conclusions

We demonstrated that pollock oil supplementation effectively improved hyperlipidemia, attenuated hepatic steatosis, and downregulated the express of hepatic genes involved in cholesterol and lipid metabolism in mice with diet-induced obesity.

Antiretroviral treatment-induced dyslipidemia in HIV-infected patients is influenced by the APOC3-related rs10892151 polymorphism

Background

The recently observed association between the APOC3-related rs10892151 polymorphism and serum triglyceride levels has prompted us the possibility to explore whether this genetic variant may play a major role in human immunodeficiency virus (HIV)/antiretroviral therapy-induced dyslipidemia.

Methods

We determined the rs10892151 genotype distribution and serum apolipoprotein (apo) C-III concentration in a group of HIV-infected patients (n = 208) and in a group of age and sex-matched healthy volunteers (n = 200). Circulating lipid and lipoprotein levels were followed for 12 months after antiretroviral treatment initiation in the HIV-infected group.

Results

There were no significant variations in the frequency of the A allele between the healthy and HIV-infected groups (7.5 vs. 8.6%, respectively; p = 0.7); additionally, the A allele was not related to serum apo C-III concentration. However, among patients receiving protease inhibitor (PI) treatment, carriers of the A allele had significantly increased serum triglyceride (5.76 ± 2.54 mmol/L) and total cholesterol (6.63 ± 2.85 mmol/L) concentrations together with depressed levels of HDL-cholesterol (0.75 ± 0.3 mmol/L) when compared with patients not carrying the allele (2.43 ± 1.32, 5.2 ± 2.17 and 1.24 ± 0.4 mmol/L, respectively) at the end of the study. This effect was only evident for HDL-cholesterol concentration when patients were treated with non-nucleoside reverse transcriptase inhibitors (1.05 ± 0.4 vs. 1.28 ± 0.4 mmol/L).

Conclusions

The A allelic variant of the rs10892151 polymorphism is not associated with serum apo C-III concentration, but predisposes HIV-infected patients to less favorable lipid profile, particularly in those patients treated with PIs.

Interactions between smoking, pulmonary surfactant protein B, and atherosclerosis in the general population: the Dallas Heart Study

OBJECTIVE

Pulmonary surfactant protein B (SP-B), an alveolar protein normally detectable at only very low concentrations in blood, circulates at higher levels among smokers and those with alveolar injury and inflammation. We hypothesized that SP-B may serve as a marker of the vascular effects of smoking and would thus be associated with subclinical measures of atherosclerosis.

METHODS AND RESULTS

Plasma levels of SP-B were measured in 3294 subjects, ages 30 to 65, enrolled in the Dallas Heart Study, a probability-based population sample of Dallas County adults. Coronary artery calcium (CAC) was measured by computed tomography and abdominal aortic plaque (AP) by magnetic resonance imaging. The cohort comprised 29% current and 17% former smokers. The overall prevalence of CAC was 22%, and that of AP was 39%. Median SP-B levels were 5-fold higher among current versus never smokers (P<0.0001) and were significantly correlated with estimated pack-years smoked (Spearman ρ=0.35, P<0.0001). Increasing levels of SP-B also associated with other traditional cardiac risk factors and higher levels of inflammatory biomarkers. In univariable analyses, increasing SP-B quartiles associated with higher prevalence of both CAC and AP (P(trend)<0.0001 for each). In multivariable analyses adjusting for traditional cardiovascular risk factors, SP-B remained associated with AP (OR 1.87 for the 4th versus 1st quartiles, 95% confidence interval 1.39 to 2.51; P<0.0001) but not CAC. An interaction was observed between SP-B, smoking status, and AP (P(interaction)=0.01), such that SP-B associated with AP in current smokers (adjusted OR 2.15 for the 4th versus 1st quartile, 95% confidence interval 1.26 to 3.67; P=0.005) but not in former or never smokers.

CONCLUSIONS

Circulating levels of SP-B increase with greater smoking burden and independently associate with abdominal AP among current smokers. Our findings support further investigation of the role of SP-B as a marker of the vascular effects of smoking.

Brain derived neurotrophic factor, cardiopulmonary fitness and cognition in patients with coronary artery disease

OBJECTIVE

To assess serum brain derived neurotrophic factor (BDNF) concentrations as a correlate of cardiopulmonary fitness and as a predictor of cognitive performance in subjects with coronary artery disease (CAD).

METHODS

Serum BDNF concentrations were assayed by ELISA and fitness was assessed using a standardized exercise stress test. The Mini Mental Status Examination (MMSE), California Verbal Learning Test 2nd Ed., Stroop, Trail Making Test B and the Digit Symbol-Coding task were administered. The val66met BDNF genotype and serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentrations were determined as potential confounders.

RESULTS

In subjects with CAD (n=88; 85.2% male, mean age 62.8±10.5 yr), cardiopulmonary fitness was associated with higher serum BDNF concentrations (β=.305, p=.013). Higher serum BDNF concentrations were associated with higher MMSE scores (F(1,87)=15.406, p<.0005) and better performance on the Digit Symbol-Coding task (F(1,87)=9.620, p=.003). IL-6, TNF-α and the val66met genotype did not influence these results.

CONCLUSION

Serum BDNF concentrations were associated with cardiopulmonary fitness, psychomotor processing speed and overall cognition in subjects with CAD.

The -308 G/A polymorphism of the tumour necrosis factor-α gene modifies the association between saturated fat intake and serum total cholesterol levels in white South African women

This study explored interactions between dietary fat intake and the tumour necrosis factor-α gene (TNFA) -308 G/A polymorphism on serum lipids in white South African (SA) women. Normal-weight (N = 88) and obese (N = 60) white SA women underwent measurements of body composition, fat distribution, fasting serum lipids, glucose, insulin concentrations and dietary intake. Subjects were genotyped for the functional -308 G/A polymorphism within the TNFA gene. There were no significant differences in the genotype or allele frequencies between groups, and no significant genotype associations were found for body fatness or distribution, or serum lipid concentrations. However, there was a significant interaction effect between dietary saturated fat (SFA) intake (%E) and TNFA -308 genotypes on serum total cholesterol concentrations (P = 0.047). With increasing SFA intake (%E), serum total cholesterol levels decreased for the GG genotype and increased for the GA plus AA genotypes. The TNFA -308 G/A polymorphism appears to modify the relationship between dietary fat intake and serum total cholesterol concentrations in white SA women.

An atherogenic lipid profile with low serum paraoxonase-1 activity during nematode infection in rats

BACKGROUND

Inflammation and oxidative stress are associated with cardiovascular diseases and underlying atherosclerosis. The high density lipoprotein (HDL)-associated paraoxonase-1 (PON1) enzyme is known to be involved in the protection of serum lipids from such oxidation. Nonetheless, the disturbances of lipid profile during nematode-infected model have not yet been studied. Therefore, we aimed to explore the effects of Nippostrongylus brasiliensis infection in male Wistar rats, a model of human gastrointestinal nematode infections, on hepatic PON1 synthesis and the levels of lipid parameters.

MATERIALS AND METHODS

Nippostrongylus brasiliensis-infected rats fed standard and high-fat diets. Serum paraoxonase and arylesterase activities were measured on day 0, 2, 4, 7, and 14 post-infection (PI). Hepatic PONs and pro-inflammatory cytokines mRNA expression levels were evaluated in a standard diet-fed groups, and the disturbances in lipid profile as well as the levels of thiobarbituric acid reactive species (TBARS) and oxidized-LDL (Ox-LDL) were measured in high-fat diet-fed groups.

RESULTS

We found that N. brasiliensis-infected rats fed the standard diet show a significant reduction in serum PON1 activity and down-regulation of hepatic PON1 mRNA expression as well as up-regulation of hepatic IL-1β, IL-β receptor (R), TNF-α, and TNFR1 mRNA expressions in association with hepatic recruitments of Kupffer cells and neutrohils. In the presence of the high-fat diet, N. brasiliensis infection increases serum triglycerides, total cholesterol, LDL/VLDL, TBARS and Ox-LDL as well as decreases serum HDL coinciding with a maximum serum PON1 reduction.

CONCLUSIONS

Nippostrongylus brasiliensis infection can induce atherogenic lipid profile and reduce serum PON1 activity.

Influence of Vascular Oxidative Stress and Inflammation on the Development and Progression of Atherosclerosis

Cardiovascular disease (CVD) risk factors such as hypertension, diabetes, dyslipidemia, smoking, physical inactivity, and obesity increase production of vascular reactive oxygen species (ROS), which results in a reduction of bioavailable nitric oxide and ultimately endothelial dysfunction and endothelial cell activation. ROS appears to mediate the inflammatory pathways that participate in the development and progression of atherosclerosis. There are numerous markers of oxidative stress and inflammation available for assessing the therapeutic response to interventions, but few are currently recommended for clinical use. Exercise training improves endothelial function via several mechanisms, including increased endothelial nitric oxide synthase—nitric oxide (eNOS-NO)— mediated production, increased activity and amount of antioxidants, attenuated ROS production, and an apparent reduction in systemic inflammation, possibly related to an increase in myokines resulting from skeletal muscle activation. Dietary antioxidant supplementation may improve endothelial function, oxidative stress, and inflammation, but much controversy exists regarding the use of antioxidant supplementation in primary and secondary CVD prevention. The purpose of this article is to review the contribution of vascular oxidative stress and activation of the inflammatory pathways in the pathogenesis of CVD and to review common methods used in clinical research to assess vascular oxidative stress and inflammation in response to therapeutic lifestyle interventions.

Metabolic syndrome is a low-grade systemic inflammatory condition

An increase in proinflammatory cytokines, a decrease in endothelial nitric oxide and adiponectin levels and an alteration in hypothalamic peptides and gastrointestinal hormones that regulate satiety, hunger and food intake all occur in metabolic syndrome. Consumption of a diet that is energy dense and rich in saturated and trans-fats by pregnant women and lactating mothers, in childhood and adult life may trigger changes in the hypothalamic and gut peptides and hormones. Such changes modulate immune response and inflammation and lead to alterations in the hypothalamic 'bodyweight/appetite/satiety set point' and result in the initiation and development of the metabolic syndrome. Roux-en-gastric bypass induces weight loss, decreases the levels of cytokines and restores hypothalamic neuropeptides and gut hormones and the hypothalamic bodyweight/appetite/satiety set point to normal. Thus, metabolic syndrome is a low-grade systemic inflammatory condition with its origins in the perinatal period and childhood.

Tumor necrosis factor-alpha gene -308 G/A polymorphism modulates the relationship between dietary fat intake, serum lipids, and obesity risk in black South African women

The prevalence of obesity and related disease risk is high in black South African (SA) women, possibly influenced by the dietary transition associated with urbanization. This study explored interactions between dietary fat intake and the tumor necrosis factor-alpha (TNFA) -308 G/A polymorphism on obesity, insulin resistance, and serum lipid concentrations in urbanized black SA women. Normal-weight (n = 105) and obese (n = 118) women underwent measurements of body composition, fat distribution, fasting serum lipids, glucose and insulin concentrations, and dietary intake. Participants were genotyped for the functional TNFA -308 G/A polymorphism. The genotype or allele frequency of the TNFA -308 G/A polymorphism did not differ between the BMI groups. However, when dietary fat intake was 30% of total energy intake [percentage energy (%E)], the odds of being obese with the TNFA GA+AA genotype was only 12% of that with GG, but increasing intake of dietary fat (%E) was associated with a significantly faster rate of increase in obesity risk in women with the TNFA GA+AA genotype compared with those with the GG genotype (P = 0.036). There were significant diet-gene interactions between alpha-linolenic acid (%E) and the total cholesterol:HDL-cholesterol ratio (P = 0.036), and PUFA (%E) and LDL cholesterol levels (P = 0.026), with participants with the A allele being more responsive to changes in relative fat intake. The TNFA -308 G/A polymorphism modified the relationship between dietary fat intake, obesity risk, and serum lipid concentrations in black SA women.

Autoantibody-mediated angiotensin receptor activation contributes to preeclampsia through tumor necrosis factor-alpha signaling

Preeclampsia is a prevalent life-threatening hypertensive disorder of pregnancy for which the pathophysiology remains largely undefined. Recently, a circulating maternal autoantibody, the angiotensin II type I (AT(1)) receptor agonistic autoantibody (AA), has emerged as a contributor to disease features. Increased circulating maternal tumor necrosis factor alpha (TNF-alpha) is also associated with the disease; however, it is unknown whether this factor directly contributes to preeclamptic symptoms. Here we report that this autoantibody increases the proinflammatory cytokine TNF-alpha in the circulation of AT(1)-AA-injected pregnant mice but not in nonpregnant mice. Coinjection of AT(1)-AA with a TNF-alpha neutralizing antibody reduced cytokine availability in AT(1)-AA-injected pregnant mice. Moreover, TNF-alpha blockade in AT(1)-AA-injected pregnant mice significantly attenuated the key features of preeclampsia. Autoantibody-induced hypertension was reduced from 131+/-4 to 110+/-4 mm Hg, and proteinuria was reduced from 212+/-25 to 155+/-23 microg of albumin per milligram of creatinine (both P<0.05). Injection of AT(1)-AA increased the serum levels of circulating soluble fms-like tyrosine kinase 1 and soluble endoglin (34.1+/-5.1, 2.4+/-0.3 ng/mL, respectively) and coinjection with the TNF-alpha blocker significantly reduced their levels (21.7+/-3.4 and 1.2+/-0.4 ng/mL, respectively). Renal damage and placental abnormalities were also decreased by TNF-alpha blockade. Lastly, the elevated circulating TNF-alpha in preeclamptic patients is significantly correlated with the AT(1)-AA bioactivity in our patient cohort. Similarly, the autoantibody, through AT(1) receptor-mediated TNF-alpha induction, contributed to increased soluble fms-like tyrosine kinase 1, soluble endoglin secretion, and increased apoptosis in cultured human villous explants. Overall, AT(1)-AA is a novel candidate that induces TNF-alpha, a cytokine that may play an important pathogenic role in preeclampsia.

TNF-alpha, a potent lipid metabolism regulator

As a multifunctional cytokine, tumor necrosis factor alpha (TNF-alpha) exerts a series of biological actions in different cells, tissues, organs, and species and has been demonstrated to regulate and interfere with energy metabolism, especially lipid homeostasis. A large body of researches suggested that the effects of TNF-alpha on lipid metabolism mainly include five aspects: (1) suppresses free fatty acid (FFA) uptake and promotes lipogenesis; (2) induces lipolysis; (3) inhibits lipid-metabolism-related enzymes activity; (4) regulates cholesterol metabolism; (5) regulates other adipocyte-derived adipokines. The molecular mechanisms underlying these actions are complex and several signal transduction pathways might be involved. Regulation of metabolism-related gene expression at transcriptional and protein levels and impact on enzymes activity might be of importance. Identification and verification of these pathways might provide novel potential strategies and drug targets for dyslipidemia therapy. However, the inconsistent and even conflict conclusions on lipid profile drawn from human subjects after infliximab therapy poses the possibility that the effect of TNF-alpha on lipid metabolism might be more complicated than it appeared to be.

Tumor necrosis factor-alpha does not mediate diabetes-induced vascular inflammation in mice

OBJECTIVE

Vascular inflammation is a key feature of both micro- and macrovascular complications in diabetes. Several lines of evidence have implicated the cytokine tumor necrosis factor (TNF) alpha as an important mediator of inflammation in diabetes. In the present study we evaluated the role of TNF alpha in streptozotocin (STZ)-induced diabetes on vascular inflammation in C57BL/6 wild-type and apoE-/- mice.

METHODS AND RESULTS

Diabetes increased the expression of vascular cell adhesion molecule (VCAM)-1 in cerebral arteries 150 m in diameter as well as the macrophage accumulation in aortic root atherosclerotic plaques in apoE-/- mice. A more pronounced vascular inflammatory response was observed in diabetic TNF alpha-deficient apoE-/- mice. These mice were also characterized by increased accumulation of IgG and IgM autoantibodies in atherosclerotic lesions. Diabetes also increased VCAM-1 expression and plaque formation in apoE-competent TNF alpha -/- mice, whereas no such effects were observed in C57BL/6 wild-type mice.

CONCLUSIONS

The present findings suggest that TNF alpha does not mediate diabetic-induced vascular inflammation in mice and reveal an unexpected protective role for TNF alpha. These effects are partly attributable to a direct antiinflammatory role of TNF alpha, but may also reflect a defective development of the immune system in these mice.

Interferon regulatory factor-1 exerts inhibitory effect on neointimal formation after vascular injury

OBJECTIVE

To investigate the effect of interferon regulatory factors (IRFs) on neointimal formation after vascular injury in the mouse, and its possible mechanism.

METHODS

Vascular injury was induced by polyethylene cuff placement around the left femoral artery of IRF-1-deficient mice and C57BL/6J mice. The mRNA expressions of IRF-1, IRF-2, angiotensin II type 2 (AT2) receptor, interleukin-1 beta converting enzyme (ICE), inducible nitric oxide synthase (iNOS) were detected by RT-PCR and immunohistochemical staining.

RESULTS

Neointimal formation after vascular injury was significantly greater in IRF-1-deficient mice than that in C57BL/6J mice (P<0.05). In contrast, TUNEL-positive nuclei to total nuclei in the neointima and media in vascular smooth muscle cell (VSMC) in the injured artery significantly attenuated in IRF-1-deficient mice compared to C57BL/6J mice (P<0.05). The expressions of AT2 receptor as well as pro-apoptotic genes such as ICE and iNOS in C57BL/6J mice were up-regulated in response to vascular injury, but this upregulation was attenuated in IRF-1-deficient mice.

CONCLUSIONS

Our results suggest that IRF-1 induces VSMC apoptosis and inhibits neointimal formation after vascular injury at least partly due to the upregulation of AT2 receptor, ICE and iNOS expressions. These results indicate that IRF-1 exerts an inhibitory effect on neointimal formation through the induction of apoptosis in VSMCs.

Establishment of a cut-point value of serum TNF-alpha levels in the metabolic syndrome

Cardiovascular diseases and type 2 diabetes are the major causes of mortality in Mexico. Metabolic syndrome (MS) is a cluster of factors that increase the risk to develop such diseases. Previous studies have shown that MS is associated with high tumor necrosis factor (TNF-alpha) levels. In fact, TNF-alpha has been proposed to be a useful marker for clinical diagnosis of inflammation at an early stage. Therefore, we analyzed TNF-alpha concentrations in Mexican individuals with or without MS and related these levels to the associated MS components. Clinical, anthropometric, and biochemical data were analyzed in 41 healthy and 39 MS individuals. Individuals were similarly grouped by age and gender.The serum TNF-alpha levels measured by a highly sensitive enzyme-linked immunosorbent assay (ELISA) kit were increased significantly in MS subjects compared with healthy individuals (P<0.001). The assay showed 78.1% sensitivity and 61.5% specificity with a cut-point level of 1.36 pg/mL. TNF-alpha levels higher than the cut-point value were correlated with insulin resistance indices. These findings support the hypothesis that serum TNF-alpha concentration could be a useful marker for early MS diagnosis. Nevertheless, we suggest the establishment of specific cut-point values in each studied population to evaluate potential clinical applications.