Circulating adipocyte-fatty acid binding protein levels predict the development of the metabolic syndrome: a 5-year prospective study

Bictegravir alters glucose tolerance in vivo and causes hepatic mitochondrial dysfunction

Growing evidence associates antiretroviral therapies containing integrase strand transfer inhibitors or tenofovir alafenamide (TAF) with increased weight gain and metabolic diseases, but the underlying mechanisms remain unclear. This study evaluated the impact of lamivudine, dolutegravir (DTG), bictegravir (BIC), tenofovir disoproxil fumarate, and TAF on metabolic alterations, and explored glucose homeostasis and mitochondrial stress as potential mechanisms. These pathways were analyzed both in vivo (C57BL/6J mice treated with the abovementioned drugs or vehicle for 16 weeks) and in vitro (in Hep3B cells). Mice treated with BIC exhibited higher glucose levels and a slower decrease during a glucose tolerance test. Functional enrichment analyses of livers from antiretroviral-treated mice revealed that only BIC altered the cellular response to insulin and induced a gluconeogenic-favoring profile, with Fgf21 playing a significant role. In vitro, BIC significantly reduced hepatocyte glucose uptake in a concentration-dependent manner, both under basal conditions and post-insulin stimulation, while the other drugs produced no significant changes. Hep3B cells treated with clinically relevant concentrations of BIC exhibited significant alterations in the mRNA expression of enzymes related to glucose metabolism. Both DTG and BIC reduced mitochondrial dehydrogenase activity, but only BIC increased reactive oxygen species, mitochondrial membrane potential, and cellular granularity, thereby indicating mitochondrial stress. BIC promoted mitochondrial dysfunction, modified carbohydrate metabolism and glucose consumption in hepatocytes, and altered glucose tolerance and gluconeogenesis regulation in mice. These findings suggest that BIC contributes to insulin resistance and diabetes in people living with HIV, warranting clinical studies to clarify its association with carbohydrate metabolism disorders.

High Fatty Acid-Binding Protein 4 Expression Associated with Favorable Clinical Characteristics and Prognosis in Papillary Thyroid Carcinoma

Fatty acid-binding protein 4 (FABP4), a fatty acid transporter that coordinates lipid metabolism, is reported to exert a tumorigenic role in certain cancers. We investigated the effects of FABP4 in the carcinogenesis of thyroid cancer. Bioinformatics data about FABP4 in thyroid cancer were collected from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). Sixteen paired papillary thyroid cancer (PTC) tissues from Taipei Medical University (TMU) were gathered, and commercial thyroid cancer complementary (c)DNA and tissue arrays were purchased to measure FABP4 messenger (m)RNA and protein levels. By analyzing data from the GEO and TCGA, we showed that FABP4 mRNA was reduced in PTC and follicular thyroid carcinoma (FTC). In addition, a lower FABP4 mRNA level in PTC was associated with poor clinical parameters and outcomes in the TCGA database. Moreover, FABP4 transcripts and proteins were downregulated in PTC and FTC, and its mRNA expression was associated with PTC staging in clinical specimens. In the TCGA database and TMU cohort, FABP4 mRNA levels were associated with thyroglobulin (r = 0.511 and r = 0.656, respectively), thyroid peroxidase (r = 0.612 and r = 0.909, respectively), and sodium iodide symporter (r = 0.485 and r = 0.637, respectively) transcripts. In conclusion, FABP4 mRNA and protein levels were reduced in PTC and FTC, and may be used as a potential indicator for thyroid cancer evolution in clinical settings. Further, well-designed research to dissect the molecular mechanism of FABP4 in modulating thyroid carcinogenesis is needed.

A New Insight into Fatty Acid Binding Protein 4 Mechanisms and Therapeutic Implications in Obesity-Associated Diseases: A Mini Review

Fatty acid binding proteins (FABPs), such as FABP4 (aP2, A-FABP), are essential for cellular lipid regulation, membrane-protein interactions, and the modulation of metabolic and inflammatory pathways. FABP4, primarily expressed in adipocytes, monocytes, and macrophages, is integrated into signaling networks that influence immune responses and insulin activity. It has been linked to obesity, inflammation, lipid metabolism, insulin resistance, diabetes, cardiovascular disease, and cancer. Inhibition of FABP4 is emerging as a promising strategy for treating obesity-related conditions, particularly insulin resistance and diabetes. Elevated FABP4 levels in individuals with a BMI above 30 underscore its association with obesity. Furthermore, FABP4 levels are higher not only in the tissues but also in the blood, promoting the onset and development of various cancers. Understanding its broader role reveals involvement in the mechanisms underlying metabolic syndrome, contributing to various metabolic and inflammatory responses. While blocking FABP4 offers an alternative therapeutic approach, a comprehensive understanding of potential side effects is crucial before clinical use. This review aims to provide concise insights into FABP4, elucidating its mechanisms and potential therapeutic applications in obesity and associated disorders, contributing to innovative interventions against metabolic syndrome and obesity.

Potential Role of Novel Cardiovascular Biomarkers in Pediatric Patients with Chronic Kidney Disease

BACKGROUND

Cardiovascular Disease is the leading cause of death in adult and pediatric patients with Chronic Kidney Disease (CKD) and its pathogenesis involves the interaction of multiple pathways. As Inflammatory mechanisms play a critical role in the vascular disease of CKD pediatric patients, there are several biomarkers related to inflammation strongly associated with this comorbidity.

OBJECTIVE

This review provides available evidence on the link between several biomarkers and the pathophysiology of heart disease in patients with CKD.

METHODS

The data were obtained independently by the authors, who carried out a comprehensive and non-systematic search in PubMed, Cochrane, Scopus, and SciELO databases. The search terms were "Chronic Kidney Disease", "Cardiovascular Disease", "Pediatrics", "Pathophysiology", "Mineral and Bone Disorder (MBD)", "Renin Angiotensin System (RAS)", "Biomarkers", "BNP", "NTproBNP", "CK-MB", "CXCL6", "CXCL16", "Endocan-1 (ESM-1)", "FABP3", "FABP4", h-FABP", "Oncostatin- M (OSM)", "Placental Growth Factor (PlGF)" and "Troponin I".

RESULTS

The pathogenesis of CKD-mediated cardiovascular disease is linked to inflammatory biomarkers, which play a critical role in the initiation, maintenance, and progression of cardiovascular disease. There are several biomarkers associated with cardiovascular disease in pediatric patients, including BNP, NTproBNP, CK-MB, CXCL6, CXCL16, Endocan-1 (ESM-1), FABP3, FABP4, Oncostatin- M (OSM), Placental Growth Factor (PlGF), and Troponin I.

CONCLUSION

The pathogenesis of CKD-mediated cardiovascular disease is not completely understood, but it is linked to inflammatory biomarkers. Further studies are required to elucidate the pathophysiological and potential role of these novel biomarkers.

p21-activated kinase 4 counteracts PKA-dependent lipolysis by phosphorylating FABP4 and HSL

Adipose tissue lipolysis is mediated by cAMP-protein kinase A (PKA)-dependent intracellular signalling. Here, we show that PKA targets p21-activated kinase 4 (PAK4), leading to its protein degradation. Adipose tissue-specific overexpression of PAK4 in mice attenuates lipolysis and exacerbates diet-induced obesity. Conversely, adipose tissue-specific knockout of Pak4 or the administration of a PAK4 inhibitor in mice ameliorates diet-induced obesity and insulin resistance while enhancing lipolysis. Pak4 knockout also increases energy expenditure and adipose tissue browning activity. Mechanistically, PAK4 directly phosphorylates fatty acid-binding protein 4 (FABP4) at T126 and hormone-sensitive lipase (HSL) at S565, impairing their interaction and thereby inhibiting lipolysis. Levels of PAK4 and the phosphorylation of FABP4-T126 and HSL-S565 are enhanced in the visceral fat of individuals with obesity compared to their lean counterparts. In summary, we have uncovered an important role for FABP4 phosphorylation in regulating adipose tissue lipolysis, and PAK4 inhibition may offer a therapeutic strategy for the treatment of obesity.

Fatty Acid-Binding Proteins Identification during the Evolution of Metabolic Syndrome: A Raman Spectroscopy-Based Approach

Excess fat in abdominal deposits is a risk factor for multiple conditions, including metabolic syndrome (MetS); lipid metabolism plays an essential role in these pathologies; fatty acid-binding proteins (FABPs) are dedicated to the cytosolic transport of fat. FABP4, whose primary source is adipose tissue, is released into the circulation, acting as an adipokine, while FABP5 also accompanies the adverse effects of MetS. FABP4 and 5 are potential biomarkers of MetS, but their behavior during syndrome evolution has not been determined. Raman spectroscopy has been applied as an alternative method to disease biomarker detection. In this work, we detected spectral changes related to FABP4 and 5 in the serum at different points of time, using an animal model of a high-fat diet-induced MetS. FABP4 and 5 spectral changes show a contribution during the evolution of MetS, which indicates alteration to a molecular level that predisposes to established MetS. These findings place FABPs as potential biomarkers of MetS and Raman spectroscopy as an alternative method for MetS assessment.

Prospective and Mendelian randomization analyses on the association of circulating fatty acid binding protein 4 (FABP-4) and risk of colorectal cancer

BACKGROUND

Fatty acid binding protein 4 (FABP-4) is a lipid-binding adipokine upregulated in obesity, which may facilitate fatty acid supply for tumor growth and promote insulin resistance and inflammation and may thus play a role in colorectal cancer (CRC) development. We aimed to investigate the association between circulating FABP-4 and CRC and to assess potential causality using a Mendelian randomization (MR) approach.

METHODS

The association between pre-diagnostic plasma measurements of FABP-4 and CRC risk was investigated in a nested case-control study in 1324 CRC cases and the same number of matched controls within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. A two-sample Mendelian randomization study was conducted based on three genetic variants (1 cis, 2 trans) associated with circulating FABP-4 identified in a published genome-wide association study (discovery n = 20,436) and data from 58,131 CRC cases and 67,347 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium, Colorectal Cancer Transdisciplinary Study, and Colon Cancer Family Registry.

RESULTS

In conditional logistic regression models adjusted for potential confounders including body size, the estimated relative risk, RR (95% confidence interval, CI) per one standard deviation, SD (8.9 ng/mL) higher FABP-4 concentration was 1.01 (0.92, 1.12) overall, 0.95 (0.80, 1.13) in men and 1.09 (0.95, 1.25) in women. Genetically determined higher FABP-4 was not associated with colorectal cancer risk (RR per FABP-4 SD was 1.10 (0.95, 1.27) overall, 1.03 (0.84, 1.26) in men and 1.21 (0.98, 1.48) in women). However, in a cis-MR approach, a statistically significant association was observed in women (RR 1.56, 1.09, 2.23) but not overall (RR 1.23, 0.97, 1.57) or in men (0.99, 0.71, 1.37).

CONCLUSIONS

Taken together, these analyses provide no support for a causal role of circulating FABP-4 in the development of CRC, although the cis-MR provides some evidence for a positive association in women, which may deserve to be investigated further.

Association of fatty acid binding protein-4 (FABP-4) T87C and rs8192688 gene polymorphisms and FABP-4 level with cardiovascular disease susceptibility in type 2 diabetic patients

Type 2 Diabetes Mellitus (T2DM) is known to cause dyslipidemia and increase the risk of cardiovascular disease (CVD). Fatty acid binding protein (FABP)-4 plays a significant role in various stages of T2DM and CVD. Although it has been demonstrated that genetic variations of the FABP-4 gene can affect insulin sensitivity, the results obtained so far are controversial. The aim of this study was to investigate the possible association between T87C and rs8192688 polymorphisms and serum levels of FABP-4 with CVD susceptibility in T2DM patients. The study included 70 healthy controls, 70 individuals with T2DM, and 70 T2DM patients with CVD. Genomic DNA was extracted, and FABP-4 T87C and rs8192688 gene polymorphic sites were amplified using the ARMS-PCR method. Lipid profile and FABP-4 serum levels were significantly higher in T2DM patients with CVD compared to those with only T2DM (p < 0.05). Additionally, FABP-4 T87C gene polymorphism (TC genotypes) and dominant model (TT vs. TC + CC) were significantly associated with a decreased risk of both T2DM and T2DM with CVD patients (p < 0.05). Patients carrying TC + CC genotypes had significantly lower levels of triglyceride and FABP-4 compared to those carrying the TT genotype (p < 0.05). There was no significant association between FABP-4 rs8192688 polymorphism and either T2DM or CVD disease. It appears that FABP-4 T87C polymorphism decreases FABP-4 levels leading to decreased serum TG levels. Since both T2DM and CVD have inflammatory backgrounds, reducing inflammation can improve insulin sensitivity and lower TG levels in these patients.

Epicardial adipose tissue and cardiac lipotoxicity: A review

Epicardial adipose tissue (EAT) has morphological and physiological contiguity with the myocardium and coronary arteries, making it a visceral fat deposit with some unique properties. Under normal circumstances, EAT exhibits biochemical, mechanical, and thermogenic cardioprotective characteristics. Under clinical processes, epicardial fat can directly impact the heart and coronary arteries by secreting proinflammatory cytokines via vasocrine or paracrine mechanisms. It is still not apparent what factors affect this equilibrium. Returning epicardial fat to its physiological purpose may be possible by enhanced local vascularization, weight loss, and focused pharmacological therapies. This review centers on EAT's developing physiological and pathophysiological dimensions and its various and pioneering clinical utilities.

Elevated Serum Concentration of Adipocyte Fatty Acid-Binding Protein Correlates with the Markers of Abdominal Obesity Independently of Thyroid Hormones in Non-Obese Women with Polycystic Ovary Syndrome

Adipocyte fatty acid-binding protein (A-FABP) is mainly expressed in adipocytes. The risk of abdominal obesity and autoimmune thyroid disease is increased in women with polycystic ovary syndrome (PCOS). The objective of this study was to explore the relationship of serum concentration of A-FABP with parameters of obesity, e.g., waist to hip ratio (WHR) and the amount of adipose tissue assessed by bioelectrical impedance analysis (BIA), and thyroid hormone homeostasis in women with PCOS. We examined 66 women with PCOS and 67 healthy women. Serum concentrations of A-FABP and thyroid hormones were measured; the FT3/FT4 ratio, thyroid-stimulating hormone index (TSHI), thyrotrope thyroxine resistance index (TT4RI) and thyroid feedback quantile-based index (TFQI) were calculated. In the PCOS group, serum concentrations of A-FABP, FT3 and the FT3/FT4 ratio were significantly higher in comparison to the control group (all p < 0.05). A correlation of A-FABP with WHR (r = 0.26, p = 0.04) and the percentage of adipose tissue (r = 0.33, p = 0.01) has been found only in women with PCOS. We observed no correlation between serum levels of A-FABP and TSHI, TT4RI or TFQI in women with PCOS (all p > 0.05). Our results indicate that A-FABP is an adipokine that may be connected with abdominal obesity independently of thyroid hormone homeostasis in PCOS patients.

Serum fatty acid-binding protein 4 as a biomarker for early detection of diabetic nephropathy in type 2 diabetes

Background

Diabetic nephropathy (DN) is one of the major causes of ESKD, and its complications are characterized by proteinuria, decreased glomerular filtration, and renal fibrosis resulting in the deterioration of renal functions, so early detection of nephropathy is essential to slow down and prevent the progression of the disease. Fatty acid-binding protein 4 (FABP4) is expressed in renal proximal tubule cells and released in response to hypoxia caused by decreased peritubular capillary blood flow, so serum FABP 4 is one of the promising biomarkers for early prediction of diabetic nephropathy in patients with type 2 diabetes.

Methods

This was a case–control study that included 120 patients with type-2 diabetes mellitus selected from Kasr Alainy Hospital, Cairo University Hospital, who were divided into 2 groups: the first group comprised 60 diabetic patients divided into 3 sub-groups according to their urinary albumin/creatinine ratio (normo-, micro-, and macroalbuminuria). The second group included 60 apparently healthy individuals. All patients were subjected to history, clinical examination, laboratory investigations, and serum FABP4 by ELISA.

Results

There was a significant increase in serum FABP4 in the macroalbuminuria group, followed by the microalbuminuria group, then the normoalbuminuria group, in comparison to the normal control group. There was a significant positive correlation between serum FABP 4 level and the duration of diabetes and HBA1c. There was a significantly negative correlation between serum FABP4 and serum albumin in the macroalbuminuria group. Receiver operating characteristic curve analysis found that serum FABP 4 discriminate micro- and macroalbuminuric patients with diabetes from controls with 96.6% and 98.3% diagnostic specificity and 100% diagnostic sensitivity respectively.

Conclusion

Serum FABP 4 can be used as a biomarker for the early detection of diabetic nephropathy.

FABP4 Expression in Subcutaneous Adipose Tissue Is Independently Associated with Circulating Triglycerides in Obesity

Hypertriglyceridemia (HTG) has been associated with an increased risk of pancreatitis and cardiovascular disease. Adipose tissue plays a major role in lipid metabolism, mobilization and distribution. We have compared the histological and transcriptomic profiles of the subcutaneous (SAT) and visceral (VAT) adipose tissues from subjects with severe obesity undergoing bariatric surgery with (Ob-HTG, n = 37) and without HTG (Ob-NTG, n = 67). Mean age and BMI were 51.87 ± 11.21 years, 45.78 ± 6.96 kg/m² and 50.03 ± 10.17 years, 44.04 ± 4.69 kg/m², respectively. The Ob-HTG group showed higher levels of glycosylated hemoglobin, fasting plasma glucose, high-sensitivity C-reactive protein and prevalence of hypertension. The degree of fibrosis was increased by 14% in SAT from the Ob-HTG group (p = 0.028), while adipocyte size distribution was comparable. Twenty genes were found differentially expressed in SAT and VAT between study groups. Among them, only SAT expression of FABP4 resulted significantly associated with circulating triglyceride levels after adjusting for other covariates and independently explained 5% of the variance in triglyceride levels in the combined model. This relationship was not found in the cohort of lean or overweight patients with normotriglyceridemia (non-Ob, n = 21). These results emphasize the contribution of SAT to triglyceride concentrations in obesity and indicate that FABP4 may be a potential drug target for the treatment of HTG.

Fatty Acid-Binding Proteins in Psoriasis-A Review

Psoriasis is one of the most common skin diseases in dermatological practice. It affects about 1–3% of the general population and is associated with different comorbidities, especially metabolic syndrome. Fatty-acid-binding proteins (FABPs) are a family of cytosolic proteins which are an important link in lipid metabolism and transport; moreover, they have different tissue specificity and properties. So far, ten FABPs have been discovered and seven have been investigated in psoriasis. In this review, we discuss the nature of all FABPs and their role in psoriasis. FABPs have different organ and tissue expression, and hence various functions, and may be markers of different disorders. Considering the concentration of a few of them tends to be elevated in psoriasis, it confirms the current perception of psoriasis as a multiorgan disorder associated with plenty of comorbidities. Some FABPs may be also further investigated as biomarkers of psoriasis organ complications. FABP-1 and FABP-5 may become potential markers of metabolic complications and inflammation in psoriasis. FABP-7 could perhaps be further investigated as an indicator of the neurodegenerative processes in psoriatic patients.

FABP4 in obesity-associated carcinogenesis: Novel insights into mechanisms and therapeutic implications

The increasing prevalence of obesity worldwide is associated with an increased risk of various diseases, including multiple metabolic diseases, cardiovascular diseases, and malignant tumors. Fatty acid binding proteins (FABPs) are members of the adipokine family of multifunctional proteins that are related to fatty acid metabolism and are divided into 12 types according to their tissue origin. FABP4 is mainly secreted by adipocytes and macrophages. Under obesity, the synthesis of FABP4 increases, and the FABP4 content is higher not only in tissues but also in the blood, which promotes the occurrence and development of various cancers. Here, we comprehensively investigated obesity epidemiology and the biological mechanisms associated with the functions of FABP4 that may explain this effect. In this review, we explore the molecular mechanisms by which FABP4 promotes carcinoma development and the interaction between fat and cancer cells in obese circumstances here. This review leads us to understand how FABP4 signaling is involved in obesity-associated tumors, which could increase the potential for advancing novel therapeutic strategies and molecular targets for the systematic treatment of malignant tumors.

Blood and Urinary Biomarkers of Antipsychotic-Induced Metabolic Syndrome

Metabolic syndrome (MetS) is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Antipsychotic (AP)-induced MetS (AIMetS) is the most common adverse drug reaction (ADR) of psychiatric pharmacotherapy. Herein, we review the results of studies of blood (serum and plasma) and urinary biomarkers as predictors of AIMetS in patients with schizophrenia (Sch). We reviewed 1440 studies examining 38 blood and 19 urinary metabolic biomarkers, including urinary indicators involved in the development of AIMetS. Among the results, only positive associations were revealed. However, at present, it should be recognized that there is no consensus on the role of any particular urinary biomarker of AIMetS. Evaluation of urinary biomarkers of the development of MetS and AIMetS, as one of the most common concomitant pathological conditions in the treatment of patients with psychiatric disorders, may provide a key to the development of strategies for personalized prevention and treatment of the condition, which is considered a complication of AP therapy for Sch in clinical practice.

Serum adipocyte fatty acid-binding protein level is positively associated with aortic stiffness in nondialysis chronic kidney disease patients: A cross-sectional study

Aortic stiffness (AS) is a major predictor of cardiovascular disease and mortality in patients with chronic kidney disease (CKD) and adipocyte fatty acid-binding protein (A-FABP) is a novel adipokine that is positively correlated with AS in the general population. Therefore, we investigated the correlation between serum A-FABP levels and AS in nondialysis CKD patients. Fasting blood samples and baseline characteristics were obtained in 270 patients with nondialysis CKD. Serum A-FABP concentrations were determined by enzyme immunoassay and carotid-femoral pulse wave velocity (cfPWV) measurements were acquired using a validated tonometry system. Patients with cfPWV >10 m/s formed the AS group, while those with values ≤10 m/s comprised the comparison group. Among 270 CKD patients, 92 patients (34.1%) were in the AS group. Compared to those in the comparison group, patients in the AS group were older (P < .001), had a higher prevalence of diabetes, along with higher serum A-FABP level (P < .001), larger waist circumference (P = .004), and lower estimated glomerular filtration rate (P = .001) but higher levels of body fat mass (P = .010), systolic blood pressure (P < .001), fasting glucose (P = .014), blood urea nitrogen (P = .009), and serum creatinine (P = .004). The serum log-A-FABP level was positively associated with log-cfPWV (β = 0.178, P = .001) in nondialysis CKD patients and multivariable logistic regression analysis identified serum A-FABP (P = .006), age (P = .001), and systolic blood pressure (P = .015) as independent predictors of AS in nondialysis-dependent CKD patients. Elevated A-FABP levels may be a significant predictor of AS in nondialysis CKD patients.

Cytoplasmic fatty acid-binding proteins in metabolic diseases and cancers

Cytoplasmic fatty acid-binding proteins (FABPs) are multipurpose proteins that can modulate lipid fluxes, trafficking, signaling, and metabolism. FABPs regulate metabolic and inflammatory pathways, its inhibition can improve type 2 diabetes mellitus and atherosclerosis. In addition, FABPs are involved in obesity, metabolic disease, cardiac dysfunction, and cancers. FABPs are promising tissue biomarkers in solid tumors for diagnostic and/or prognostic targets for novel therapeutic strategies. The signaling responsive elements of FABPs and determinants of FABP-mediated functions may be exploited in preventing or treating these diseases.

Non-alcoholic fatty liver disease and type 2 diabetes - An Update

The global prevalence of non‐alcoholic fatty liver disease (NAFLD) is rising, along with the epidemic of diabesity. NAFLD is present in >70% of individuals with type 2 diabetes. Although the mutually detrimental relationship between NAFLD and type 2 diabetes has been well established, a multitude of recent studies have further shown that type 2 diabetes is closely linked to the development of cirrhosis, hepatocellular carcinoma, liver‐related morbidity and mortality. In contrast, NAFLD also negatively impacts type 2 diabetes both in terms of its incidence and related adverse clinical outcomes, including cardiovascular and chronic kidney diseases. In response to these global health threats, clinical care pathways for NAFLD and guidelines for metabolic dysfunction‐associated fatty liver disease have been developed. Several antidiabetic agents have been evaluated for their potential hepatic benefits with promising results. Furthermore, type 2 diabetes patients are increasingly represented in clinical trials of novel therapeutics for NAFLD. However, despite the wealth of knowledge in NAFLD and type 2 diabetes, lack of awareness of the disease and the potential weight of this problem remains a major challenge, especially among clinicians who are outside the field of hepatology and gastroenterology. This review therefore aimed to provide all diabetes care providers with a summary of the latest evidence that supports NAFLD as an emerging diabetic complication of increasing importance, and to present the current recommendations, focusing on the assessment and therapeutic strategies, on the management of NAFLD among type 2 diabetes patients.

Unveiling the Role of the Fatty Acid Binding Protein 4 in the Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), the main cause of chronic liver disease worldwide, is a progressive disease ranging from fatty liver to steatohepatitis (metabolic-associated steatohepatitis; MASH). Nevertheless, it remains underdiagnosed due to the lack of effective non-invasive methods for its diagnosis and staging. Although MAFLD has been found in lean individuals, it is closely associated with obesity-related conditions. Adipose tissue is the main source of liver triglycerides and adipocytes act as endocrine organs releasing a large number of adipokines and pro-inflammatory mediators involved in MAFLD progression into bloodstream. Among the adipocyte-derived molecules, fatty acid binding protein 4 (FABP4) has been recently associated with fatty liver and additional features of advanced stages of MAFLD. Additionally, emerging data from preclinical studies propose FABP4 as a causal actor involved in the disease progression, rather than a mere biomarker for the disease. Therefore, the FABP4 regulation could be considered as a potential therapeutic strategy to MAFLD. Here, we review the current knowledge of FABP4 in MAFLD, as well as its potential role as a therapeutic target for this disease.

FABP4 and I-FABP Levels in Pregnant Women Are Associated with Body Mass Index but Not Gestational Diabetes

OBJECTIVES

Gestational diabetes mellitus (GDM) is glucose intolerance detected initially during pregnancy. GDM poses an increased risk for the development of diabetes later in life. Fatty acid-binding protein 4 (FABP4) is a regulator of lipid metabolism and is associated with obesity, insulin resistance, and type 2 diabetes. Increased level of intestinal fatty acid-binding protein (I-FABP) may indicate impaired intestinal permeability, which may be an important contributor to the pathogenesis of type 1 diabetes and GDM. We aimed to compare FABP4 and I-FABP levels in pregnant women with GDM and in healthy pregnant controls, taking into consideration their prepregnancy body mass index (BMI), past exposures to enteroviruses (EV), and adipokine and cytokine levels, which have been shown to decrease insulin sensitivity. Material and Methods. Forty patients with GDM (median age 30.5) and 40 pregnant healthy controls (median age 31.1) were divided on the basis of their prepregnancy BMI into two groups: normal weight (BMI < 25, n = 20) and overweight (BMI ≥ 25, n = 20). FABP4 and I-FABP were measured from serum samples using commercial ELISA kits.

RESULTS

FABP4 and I-FABP levels did not differ between women with GDM and healthy pregnant controls (p > 0.05 for both comparisons). However, both levels were associated with BMI (p < 0.001 for both comparisons). Median I-FABP level was the highest in healthy controls with lower BMI (<25) (p = 0.0009). FABP4 levels correlated with BMI and C-peptide values in both groups (p < 0.001). Anti-EV antibody levels did not correlate with FABP4 or I-FABP levels. FABP4 and adiponectin levels were negatively correlated in controls (r = -0.61, p = 0.0009), while I-FABP correlated positively with adiponectin (r = 0.58, p = 0.04) and resistin (r = 0.67, p = 0.04) levels in the GDM group.

CONCLUSION

FABP4 and I-FABP levels were not dependent on the diagnosis of GDM, but rather on BMI. The correlation of I-FABP with adiponectin and resistin levels in women with GDM may suggests the importance of lipid metabolism in GDM-associated changes in intestinal permeability.

High Serum FABP4 Levels are Negatively Associated with the Reversion from Prediabetes to Normal Glucose Tolerance: A 2-Year Retrospective Cohort Community Study

OBJECTIVE

To explore the relationship between the level of fatty acid-binding protein 4 (FABP4) and reversion from prediabetes to normal glucose tolerance (NGT).

METHODS

A two-year retrospective cohort study was conducted on 398 participants with complete information. These 398 participants were divided into an NGT group and an abnormal glucose metabolism (AGM) group after 2 years of follow-up. The baseline level of FABP4 was determined, and the role of FABP4 in predicting reversion from prediabetes to NGT was investigated using an unconditional logistic regression model.

RESULTS

Over the two-year follow-up period, 37.4% (149/398) of the participants reverted from prediabetes to NGT. The participants with AGM had a higher baseline level of FABP4 than those with NGT. The baseline level of FABP4 was significantly negatively correlated with reversion from prediabetes to NGT. After adjusting for age, sex, body mass index and waist-to-hip ratio, the level of fasting blood glucose (FBG) [odds ratio (OR) 0.336, 95% confidence interval (CI) (0.196-0.576)], 2-h post-challenge blood glucose (2hBG) [OR 0.697, 95% CI (0.581-0.837)], and FABP4 [OR 0.960, 95% CI (0.928-0.993)] at baseline were significant independent predictors of reversion from prediabetes to NGT. The area under the curve (AUC) value of the receiver operating characteristic curve for FABP4 was 0.605 (95% CI: 0.546-0.665), and the AUC for FABP4 combined with FBG and 2hBG was 0.716 (95% CI: 0.663-0.769).

CONCLUSION

A higher baseline level of FABP4 was positively correlated with an adverse profile of diabetes risk factors and negatively correlated with reversion from prediabetes to NGT. FABP4, FBG and 2hBG were predictors of reversion from prediabetes to NGT.

Circulating level of fatty acid-binding protein 4 is an independent predictor of metabolic dysfunction-associated fatty liver disease in middle-aged and elderly individuals

Aims/Introduction

Metabolic dysfunction‐associated fatty liver disease (MAFLD), defined as hepatosteatosis with type 2 diabetes mellitus, overweight/obesity or metabolic dysregulation, has been proposed as a new feature of chronic liver disease. Fatty acid‐binding protein 4 (FABP4) is expressed in adipose tissue, and secreted FABP4 is associated with the development of insulin resistance and atherosclerosis. However, the relationship between MAFLD and FABP4 has not been fully addressed.

Materials and Methods

Associations of MAFLD with metabolic markers, including FABP4, fibroblast growth factor 21 and adiponectin, were investigated in 627 individuals (men/women 292/335) in the Tanno‐Sobetsu Study, a population‐based cohort.

Results

The mean age was 65 years (range 19–98 years, median [interquartile range] 68 [56–76] years). Hepatosteatosis was determined by the fatty liver index (FLI), and FLI ≥35 for men and FLI ≥16 for women were used for detection of fatty liver, as previously reported using 14,471 Japanese individuals. FLI was positively correlated with systolic blood pressure and levels of FABP4 (r = 0.331, P < 0.001), fibroblast growth factor 21, homeostasis model assessment of insulin resistance as an insulin resistance index and uric acid, and was negatively correlated with levels of high‐density lipoprotein cholesterol and adiponectin. FABP4 concentration was independently associated with FLI after adjustment of age, sex, systolic blood pressure and levels of uric acid, high‐density lipoprotein cholesterol, homeostasis model assessment of insulin resistance, adiponectin and fibroblast growth factor 21 in multivariable regression analysis. Logistic regression analysis showed that FABP4 was an independent predictor of MAFLD after adjustment of age, sex, presence of diabetes mellitus, hypertension and dyslipidemia, and levels of uric acid, homeostasis model assessment of insulin resistance, adiponectin and fibroblast growth factor 21.

Conclusions

FABP4 concentration is independently associated with FLI and is an independent predictor of MAFLD in middle‐aged and elderly individuals.

Metabolic Syndrome-Related Hyperuricemia is Associated with a Poorer Prognosis in Patients with Colorectal Cancer: A Multicenter Retrospective Study

Purpose

Hyperuricemia and metabolic syndrome (MetS) have been shown to correlate with prognosis in patients with malignant tumors. The present study evaluated the relationship between preoperative hyperuricemia and MetS in colorectal cancer (CRC) patients and analyzed the effect of this combination on prognosis within 5 years.

Patients and Methods

The study enrolled patients who had undergone radical CRC resection at three independent medical centers from January 2014 to December 2016. Patients were preoperatively categorized into four groups, those with hyperuricemia alone (H), those with MetS alone (MS), those with MetS-related hyperuricemia (MSH), and those with neither condition (control [C] group). The disease-free survival (DFS) and overall survival (OS) rates of these four groups were compared.

Results

The study population consisted of 1271 patients, with 114, 201, 101, and 855 patients categorized into the H, MS, MSH and C groups, respectively. Preoperative MetS was found to be significantly associated with hyperuricemia (P < 0.001). Multivariate Cox regression analysis showed that MetS-related hyperuricemia (hazard ratio [HR] = 2.728; P < 0.001) and MetS alone (HR = 1.631; P < 0.001) were independent predictors of death, whereas simple hyperuricemia was not (P > 0.1). Relative to the C group, the MSH group had the highest rate of tumor recurrence or metastasis (HR = 5.103, P < 0.001), followed by the MS (HR = 2.231, P < 0.001) group. In contrast, prognosis did not differ significantly in the H and C groups (P > 0.1). MetS was significantly associated with poor prognosis, with MetS-related hyperuricemia resulting in a significantly poorer prognosis. In contrast, hyperuricemia alone had no effect on the long-term prognosis of CRC patients.

Conclusion

This study highlights the prognostic importance of MetS-related hyperuricemia on the survival of patients with CRC.

Association of adipocyte fatty acid-binding protein and tumor necrosis factor alpha with periodontal health and disease: A cross-sectional investigation

Background

Adipocyte fatty acid binding protein (A-FABP) is a novel biomarker of inflammation for various chronic systemic diseases. Since periodontitis is a chronic inflammatory disease, this study explores the association of A-FABP with periodontal disease parameters and tumor necrosis factor-alpha (TNF-α) levels in gingival crevicular fluid in periodontal health and disease.

Materials and Methods

This original research article describes a cross-sectional study conducted at the Department of Periodontics, M. R. Ambedkar Dental College and Hospital, Bangalore, India. This cross-sectional investigation was conducted on sixty subjects which were divided into three groups of twenty subjects each - healthy, gingivitis, and chronic periodontitis. Clinical parameters - plaque index, bleeding index, probing depth, and clinical attachment loss were recorded. Gingival crevicular fluid samples were analyzed for A-FABP and TNF-α levels using ELISA. One-way analysis of variance was used to find the significance of study parameters on a continuous scale between three groups. Pearson's correlation has been used to find the relationship between Gingival crevicular fluid concentration of markers and periodontal parameters. Multiple linear regression analysis was applied to the study. The statistical significance was considered at P < 0.05.

Results

Mean concentration of A-FABP (6.43 ± 2.51) and TNF-α (3454.82 ± 1566.44) was highest in the periodontitis group, and the difference among the groups was statistically significant (P < 0.05). A positive correlation was observed between clinical attachment loss and the two markers among all groups. The correlation between A-FABP and TNF-α in periodontitis groups was positive and statistically significant (P < 0.05). Multiple linear regression model was statistically significant (P < 0.05) indicating that there is a significant relationship between the set of predictors and the clinical attachment loss.

Conclusion

A-FABP and TNF-α levels in GCF were significantly elevated in the presence of inflammation. A-FABP has a probable stimulatory effect on TNF-α; however, its role needs to be explored. A-FABP could serve as a novel inflammatory biomarker of periodontitis and the scope of using A-FABP inhibition as a treatment modality could be investigated with interventional studies.

FABP4 and omentin-1 gene expression in epicardial adipose tissue from coronary artery disease patients

Omentin-1 and fatty acid-binding protein 4 (FABP4) are adipose tissue adipokines linked to obesity-associated cardiovascular complications. The aim of this study was to investigate epicardial adipose tissue (EAT) omentin-1 and FABP4 gene expression in obese and non-obese patients with coronary artery disease (CAD). Omentin-1 and FABP4 mRNA levels in EAT and paired subcutaneous adipose tissue (SAT) as well as adipokine serum concentrations were assessed in 77 individuals (61 with CAD; 16 without CAD (NCAD)). EAT FABP4 mRNA level was decreased in obese CAD patients when compared to obese NCAD individuals (p=0.001). SAT FABP4 mRNA level was decreased in CAD patients compared to NCAD individuals without respect to their obesity status (p=0.001). Omentin-1 mRNA level in EAT and SAT did not differ between the CAD and NCAD groups. These findings suggest that omentin-1 gene expression in adipose tissue is not changed during CAD; downregulated FABP4 gene expression in SAT is associated with CAD while EAT FABP4 gene expression is decreased only in obesity-related CAD.

Metabolic Hormones Modulate Macrophage Inflammatory Responses

Simple Summary

Macrophages are a type of immune cell which play an important role in the development of cancer. Obesity increases the risk of cancer and obesity also causes disruption to the normal levels of hormones that are produced to coordinate metabolism. Recent research now shows that these metabolic hormones also play important roles in macrophage immune responses and so through macrophages, disrupted metabolic hormone levels may promote cancer. This review article aims to highlight and summarise these recent findings so that the scientific community may better understand how important this new area of research is, and how these findings can be capitalised on for future scientific studies.

Abstract

Macrophages are phagocytotic leukocytes that play an important role in the innate immune response and have established roles in metabolic diseases and cancer progression. Increased adiposity in obese individuals leads to dysregulation of many hormones including those whose functions are to coordinate metabolism. Recent evidence suggests additional roles of these metabolic hormones in modulating macrophage inflammatory responses. In this review, we highlight key metabolic hormones and summarise their influence on the inflammatory response of macrophages and consider how, in turn, these hormones may influence the development of different cancer types through the modulation of macrophage functions.

A-FABP in Metabolic Diseases and the Therapeutic Implications: An Update

Adipocyte fatty acid-binding protein (A-FABP), which is also known as ap2 or FABP4, is a fatty acid chaperone that has been further defined as a fat-derived hormone. It regulates lipid homeostasis and is a key mediator of inflammation. Circulating levels of A-FABP are closely associated with metabolic syndrome and cardiometabolic diseases with imminent diagnostic and prognostic significance. Numerous animal studies have elucidated the potential underlying mechanisms involving A-FABP in these diseases. Recent studies demonstrated its physiological role in the regulation of adaptive thermogenesis and its pathological roles in ischemic stroke and liver fibrosis. Due to its implication in various diseases, A-FABP has become a promising target for the development of small molecule inhibitors and neutralizing antibodies for disease treatment. This review summarizes the clinical and animal findings of A-FABP in the pathogenesis of cardio-metabolic diseases in recent years. The underlying mechanism and its therapeutic implications are also highlighted.

Fatty acids and evolving roles of their proteins in neurological, cardiovascular disorders and cancers

The dysregulation of fat metabolism is involved in various disorders, including neurodegenerative, cardiovascular, and cancers. The uptake of long-chain fatty acids (LCFAs) with 14 or more carbons plays a pivotal role in cellular metabolic homeostasis. Therefore, the uptake and metabolism of LCFAs must constantly be in tune with the cellular, metabolic, and structural requirements of cells. Many metabolic diseases are thought to be driven by the abnormal flow of fatty acids either from the dietary origin and/or released from adipose stores. Cellular uptake and intracellular trafficking of fatty acids are facilitated ubiquitously with unique combinations of fatty acid transport proteins and cytoplasmic fatty acid-binding proteins in every tissue. Extensive data are emerging on the defective transporters and metabolism of LCFAs and their clinical implications. Uptake and metabolism of LCFAs are crucial for the brain's functional development and cardiovascular health and maintenance. In addition, data suggest fatty acid metabolic transporter can normalize activated inflammatory response by reprogramming lipid metabolism in cancers. Here we review the current understanding of how LCFAs and their proteins contribute to the pathophysiology of three crucial diseases and the mechanisms involved in the processes.

Adipocyte-Specific Fatty Acid-Binding Protein (AFABP) and Chemerin in Association with Gestational Diabetes: A Case-Control Study

BACKGROUND

Adipocytokines participate in regulating the inflammatory response in glucose homeostasis and type 2 diabetes. However, among these peptides, the role of adipocyte-specific fatty-acid-binding protein (AFABP), chemerin, and secreted protein acidic and rich in cysteine (SPARC) in gestational diabetes (GDM) has not been fully investigated.

METHOD

The maternal fasting level of adipocytokines of 53 subjects with GDM and 43 normal pregnant (NGDM) was measured using multiplex immunoassay at 24-28 weeks, before delivery, immediate postpartum, and 2-6 months postpuerperium.

RESULTS

Higher levels of AFABP were associated with a 3.7-fold higher risk of GDM. Low chemerin levels were associated with a 3.6-fold higher risk of GDM. Interleukin-10 (IL-10) was inversely associated with the risk of GDM. SPARC had no association with GDM. AFABP was directly correlated to interleukin-6 (r = 0.50), insulin resistance index (r = 0.26), and body mass index (r = 0.28) and inversely correlated to C-reactive protein (r = -0.27). Chemerin levels were directly and strongly correlated with IL-10 (r = 0.41) and interleukin-4 (r = 0.50) and inversely correlated to insulin resistance index (r = -0.23) in GDM but not NGDM. In the longitudinal assessment, there were no significant differences in AFABP and chemerin concentrations of both studied groups.

CONCLUSION

AFABP and chemerin were associated with a higher risk of GDM. These adipocytokines were related to insulin resistance, body mass index, and inflammation in pregnant women diagnosed with GDM.

Increased Levels of Adipocyte and Epidermal Fatty Acid-Binding Proteins in Acute Lymphoblastic Leukemia Survivors

Childhood cancer survivors are highly exposed to the development of side effects after many years of cessation of anticancer treatment, including altered lipid metabolism that may result in an increased risk of overweight and metabolic syndrome. Adipocyte (A-FABP) and epidermal (E-FABP) fatty acid-binding proteins are expressed in adipocytes and are assumed to play an important role in the development of lipid disturbances leading to the onset of metabolic syndrome. The aim of this study was to investigate the association between serum A-FABP and E-FABP levels, overweight, and components of the metabolic syndrome in acute lymphoblastic leukemia survivors. Sixty-two acute lymphoblastic leukemia (ALL) survivors (34 females) were included in the study. The mean age at the time of the study was 12.41 ± 4.98 years (range 4.71–23.43). Serum levels of A-FABP and E-FABP were analyzed using a commercially available ELISA kit. The ALL survivors presented statistically higher A-FABP levels in comparison with the healthy controls (25.57 ± 14.46 vs. 15.13 ± 7.61 ng/mL, p < 0.001). The subjects with body mass index (BMI) above the normal range (18 overweight, 10 obese) had a greater level of A-FABP compared to the ALL group with normal BMI (32.02 ± 17.10 vs. 20.33 ± 9.24 ng/mL, p = 0.006). Of all participants, 53.23% had at least one risk factor of metabolic syndrome; in this group, only the A-FABP level showed a statistically significant difference compared to the healthy control group (30.63 ± 15.91 vs. 15.13 ± 7.61 ng/mL, p < 0.001). The subjects with two or more metabolic risk factors (16.13%) presented higher levels of both A-FABP (33.62 ± 17.16 vs. 15.13 ± 7.61 ng/mL, p = 0.001) and E-FABP (13.37 ± 3.62 vs. 10.12 ± 3.21 ng/mL, p = 0.021) compared to the controls. Univariable regression models showed significant associations between BMI and systolic blood pressure with the A-FABP level (coeff. 1.02 and 13.74, respectively; p < 0.05). In contrast, the E-FABP level was only affected by BMI (coeff. 0.48; p < 0.01). The findings reported herein suggest that the increased levels of A-FABP and E-FABP may be involved in the pathogenesis of overweight and the onset of metabolic syndrome in acute lymphoblastic leukemia. However, further longitudinal, prospective studies of fatty acid-binding proteins and their potential role in the pathogenesis of obesity and metabolic syndrome in ALL survivors remain to be performed.

Serum fatty acid-binding protein 5 is a significant factor in hepatocellular carcinoma progression independent of tissue expression level

Fatty acid-binding protein 5 (FABP5) is highly expressed in hepatocellular carcinoma (HCC) tissues and is related to HCC progression. In this study, we analyzed the potential of serum FABP5 (sFABP5) as a tumor marker in HCC and its clinical significance in HCC progression. We compared the sFABP5 concentration in patients with HCC (HCC group) with that of patients with hepatitis without HCC (hepatitis group). Moreover, we measured the FABP5 expression levels in resected HCC tissues (tFABP5) and analyzed their relationship with sFABP5. We also performed cell-based assays using FABP5 knockout and overexpressing HCC cell lines to analyze the effect of extrinsic FABP5 (exFABP5) on HCC cells. We showed that sFABP5 was not a useful tumor marker for HCC, as HCC and sFABP5 were not correlated. However, sFABP5 and tFABP5 significantly correlated with survival after surgery for HCC, while sFABP5 and tFABP5 were independent of each other. In cell-based assays, exFABP5 was taken up by HCC cell lines and positively affected cell survival under glucose-depleted conditions by complementing the endogenous FABP5 function. In conclusion, sFABP5 had a significant impact on HCC progression irrespective of tFABP5 by augmenting cell viability under glucose-depleted conditions. As tFABP5 and sFABP5 are important factors that are independent of each other in HCC progression, both of them should be considered independently in improving the prognosis of patients with HCC.

Adipocyte Fatty Acid-Binding Protein, Cardiovascular Diseases and Mortality

It has been increasingly recognized that inflammation plays an important role in the pathogenesis of cardiovascular disease (CVD). In obesity, adipose tissue inflammation, especially in the visceral fat depots, contributes to systemic inflammation and promotes the development of atherosclerosis. Adipocyte fatty acid-binding protein (AFABP), a lipid chaperone abundantly secreted from the adipocytes and macrophages, is one of the key players mediating this adipose-vascular cross-talk, in part via its interaction with c-Jun NH2-terminal kinase (JNK) and activator protein-1 (AP-1) to form a positive feedback loop, and perpetuate inflammatory responses. In mice, selective JNK inactivation in the adipose tissue significantly reduced the expression of AFABP in their adipose tissue, as well as circulating AFABP levels. Importantly, fat transplant experiments showed that adipose-specific JNK inactivation in the visceral fat was sufficient to protect mice with apoE deficiency from atherosclerosis, with the beneficial effects attenuated by the continuous infusion of recombinant AFABP, supporting the role of AFABP as the link between visceral fat inflammation and atherosclerosis. In humans, raised circulating AFABP levels are associated with incident metabolic syndrome, type 2 diabetes and CVD, as well as non-alcoholic steatohepatitis, diabetic nephropathy and adverse renal outcomes, all being conditions closely related to inflammation and enhanced CV mortality. Collectively, these clinical data have provided support to AFABP as an important adipokine linking obesity, inflammation and CVD. This review will discuss recent findings on the role of AFABP in CVD and mortality, the possible underlying mechanisms, and pharmacological inhibition of AFABP as a potential strategy to combat CVD.

Molecular mechanism underlying the hypolipidemic effect of Shanmei Capsule based on network pharmacology and molecular docking

BACKGROUND:

Shanmei Capsule is a famous preparation in China. However, the related mechanism of Shanmei Capsule against hyperlipidemia has yet to be revealed.

OBJECTIVE:

To elucidate underlying mechanism of Shanmei Capsule against hyperlipidemia through network pharmacology approach and molecular docking.

METHODS:

Active ingredients, targets of Shanmei Capsule as well as targets for hyperlipidemia were screened based on database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were performed via Database for Annotation, Visualization, and Integrated Discovery (DAVID) 6.8 database. Ingredient-target-disease-pathway network was visualized utilizing Cytoscape software and molecular docking was performed by Autodock Vina.

RESULTS:

Seventeen active ingredients in Shanmei Capsule were screened out with a closely connection with 34 hyperlipidemia-related targets. GO analysis revealed 40 biological processes, 5 cellular components and 29 molecular functions. A total of 15 signal pathways were enriched by KEGG pathway enrichment analysis. The docking results indicated that the binding activities of key ingredients for PPAR-α are equivalent to that of the positive drug lifibrate.

CONCLUSIONS:

The possible molecular mechanism mainly involved PPAR signaling pathway, Bile secretion and TNF signaling pathway via acting on MAPK8, PPARγ, MMP9, PPARα, FABP4 and NOS2 targets.

Elevated circulating FABP4 concentration predicts cardiovascular death in a general population: a 12-year prospective study

Fatty acid-binding protein 4 (FABP4) is secreted from adipose tissue and acts as an adipokine, and an elevated circulating FABP4 level is associated with metabolic disorders and atherosclerosis. However, little is known about the causal link between circulating FABP4 level and mortality in a general population. We investigated the relationship between FABP4 concentration and mortality including cardiovascular death during a 12-year period in subjects of the Tanno-Sobetsu Study, a population-based cohort (n = 721, male/female: 302/419). FABP4 concentration at baseline was significantly higher in female subjects than in male subjects. All-cause death occurred in 123 (male/female: 74/49) subjects, and 34 (male/female: 20/14) and 42 (male/female: 26/16) subjects died of cardiovascular events and cancer, respectively. When divided into 3 groups according to tertiles of FABP4 level at baseline by sex (T1–T3), Kaplan–Meier survival curves showed that there were significant differences in rates of all-cause death and cardiovascular death, but not cancer death, among the groups. Multivariable Cox proportional hazard model analysis with a restricted cubic spline showed that hazard ratio (HR) for cardiovascular death, but not that for all-cause death, significantly increased with a higher FABP4 level at baseline after adjustment of age and sex. The risk of cardiovascular death after adjustment of age, sex, body mass index and levels of brain natriuretic peptide and high-sensitivity C-reactive protein in the 3rd tertile (T3) group (HR: 4.96, 95% confidence interval: 1.20–22.3) was significantly higher than that in the 1st tertile (T1) group as the reference. In conclusion, elevated circulating FABP4 concentration predicts cardiovascular death in a general population.

Fatty-Acid-Binding Protein 4 as a Novel Contributor to Mononuclear Cell Activation and Endothelial Cell Dysfunction in Atherosclerosis

Background—Elevated circulating fatty-acid-binding protein 4 (FABP4) levels may be linked with cardiovascular events. This study aimed to investigate the mechanistic role of FABP4 in atherosclerosis. Methods—We recruited 22 patients with angiographically proven coronary artery disease (CAD) and 40 control subjects. Mononuclear cells (MNCs) and human coronary endothelial cells (HCAECs) were used for in vitro study. Results—Patients with CAD were predominantly male with an enhanced prevalence of hypertension, diabetes, and smoking history. FABP4 concentrations were up-regulated in culture supernatants of MNCs from CAD patients, which were positively correlated with the patients’ age, waist–hip ratio, body mass index, serum creatinine, type 2 diabetes, and the presence of hypertension. The adhesiveness of HCAECs to monocytic cells can be activated by FABP4, which was reversed by an FABP4 antibody. FABP4 blockade attenuated the oxidized low-density lipoprotein (oxLDL)-induced expression of ICAM-1, VCAM-1, and P-selectin. FABP4 impaired the tube formation and migration via the ERK/JNK/STAT-1 signaling pathway. FABP4 suppressed phosphorylation of eNOS and expression of SDF-1 protein, both of which can be reversed by treatment with VEGF. Blockade of FABP4 also improved the oxLDL-impaired cell function. Conclusion—We discovered a novel pathogenic role of FABP4 in MNC activation and endothelial dysfunction in atherosclerosis. FABP4 may be a therapeutic target for modulating atherosclerosis.

Regulative effect of maternal serum fatty acid-binding protein 4 on insulin resistance and the development of gestational diabetes mellitus

Fatty acid binding protein 4 (FABP4) was found to be closely correlated with gestational diabetes mellitus (GDM), a severe pregnancy syndrome. However, safe and efficient treatment for GDM is limited. We aimed to investigate whether inhibition of FABP4 could ameliorate GDM and the underlying mechanism. An evaluation of blood samples from a total of 109 patients showed significantly positive correlations between serum FABP4 and biochemical parameters known to associate with GDM. This correlation was subsequently explored in vitro. FABP4 inhibition was achieved using BMS309403 in GDM mice. GDM related symptoms, including insulin resistance and macrophage infiltration in the adipose tissues, were measured. Lipid metabolism in 3T3-L1 adipocytes was tested. We firstly confirmed the positive correlations between serum FABP4, insulin resistance and inflammation cytokines, including tumor necrosis factor-α (TNF) and interleukin-6 (IL-6), in GDM patients. Surprisingly, inhibition of FABP4 by BMS309403 resulted in significant alleviation of GDM symptoms in GDM mouse model. BMS309403 improved glucose and insulin tolerance and transcriptionally repressed the levels of TNF-α and IL-6, suggesting a role of FABP4 in inflammation. Furthermore, macrophage infiltration into the adipose tissues was dramatically decreased in the BMS309403-treated GDM mice compared to untreated GDM mice. Interestingly, incubation of 3T3-L1 adipocytes with FABP4 protein decreased the mRNA and protein levels of peroxisome proliferator-activated receptor γ (PPARγ), which was absent when BMS309403 was used. However, lipid accumulation was promoted in FABP4-treated 3T3-L1 adipocytes which showed no change in the presence of BMS309403. In conclusion, inhibition of FABP4 by BMS309403 could be an effective treatment to alleviate GDM.

Inhibition of vascular adhesion protein-1 modifies hepatic steatosis in vitro and in vivo

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance and dyslipidaemia and currently is estimated to affect up to a third of all individuals in developed countries. Current standard of care for patients varies according to disease stage, but includes lifestyle interventions common insulin sensitizers, antioxidants and lipid modifiers. However, to date specific therapies have shown little histological or fibrosis stage improvement in large clinical trials, and there is still no licensed therapy for NAFLD. Given the high prevalence, limited treatment options and significant screening costs for the general population, new treatments are urgently required.

AIM

To assess the potential for inhibition of the amine oxidase enzyme vascular adhesion protein-1 (VAP-1) to modify hepatic lipid accumulation in NAFLD.

METHODS

We have used immunochemical and qPCR analysis to document expression of VAP-1 and key functional proteins and transporters across the NAFLD spectrum. We then utilised hepatocytes in culture and human precision cut liver slices in concert with selective enzyme activity inhibitors to test the effects of activating the semicarbazide-sensitive amine oxidase activity of VAP-1 on hepatic lipid uptake and triglyceride export. A murine model of NAFLD was also used to determine the consequences of VAP-1 knockout and gene expression arrays were used to quantify the effects of VAP-1 activity on key lipid modifying and proinflammatory gene expression.

RESULTS

We confirmed that increasing severity of NAFLD and progression to cirrhosis was associated with a significant increase in hepatocellular VAP-1 expression. Hepatocytes in vitro exposed to recombinant VAP-1 and its substrate methylamine showed increased lipid accumulation as determined by quantification of Oil Red O uptake. This was recapitulated using hydrogen peroxide, and lipid accumulation was accompanied by changes in expression of the lipid transporter molecules FABP3, FATP6, insulin receptor subunits and PPARα. Human liver tissue exposed to recombinant VAP-1 or substrates for endo/exogenous VAP-1 produced less triglyceride than untreated tissue and demonstrated an increase in steatosis. This response could be inhibited by using bromoethylamine to inhibit the SSAO activity of VAP-1, and mice deficient in VAP-1/AOC3 also demonstrated reduced steatosis on high fat diet. Exposure of human liver tissue to methylamine to activate VAP-1 resulted in increased expression of FABP2 and 4, FATP3-5, caveolin-1, VLDLR, PPARGC1 and genes associated with the inflammatory response.

CONCLUSION

Our data confirm that the elevations in hepatic VAP-1 expression reported in nonalcoholic steatohepatitis can contribute to steatosis, metabolic disturbance and inflammation. This suggests that targeting the semicarbazide sensitive amine oxidase capacity of VAP-1 may represent a useful adjunct to other therapeutic strategies in NAFLD.

Association between adipocyte fatty acid-binding protein with left ventricular remodelling and diastolic function in type 2 diabetes: a prospective echocardiography study

Background

The relationship between adipocyte fatty acid-binding protein (AFABP) and cardiac remodelling has been reported in cross-sectional studies, although with conflicting results. Type 2 diabetes mellitus (T2DM) is associated with left ventricular (LV) hypertrophy and diastolic dysfunction, as well as elevated circulating AFABP levels. Here we investigated prospectively the association between AFABP with the longitudinal changes of cardiac remodelling and diastolic dysfunction in T2DM.

Methods

Circulating AFABP levels were measured in 176 T2DM patients without cardiovascular diseases (CVD) at baseline. All participants received detailed transthoracic echocardiography both at baseline and after 1 year. Multivariable linear and Cox regression analyses were used to evaluate the associations of circulating AFABP levels with changes in echocardiography parameters and incident major adverse cardiovascular events (MACE), respectively.

Results

The median duration between baseline and follow-up echocardiography assessments was 28 months. Higher sex-specific AFABP quartiles at baseline were associated with increase in LV mass and worsening of average E/e′ (all P < 0.01). Multivariable linear regression demonstrated that AFABP in the highest quartile was independently associated with both increase in LV mass (β = 0.89, P < 0.01) and worsening of average E/e′ (β = 0.57, P < 0.05). Moreover, multivariable Cox regression analysis showed that elevated baseline circulating AFABP level independently predicted incident MACE (HR 2.65, 95% CI 1.16–6.05, P < 0.05) after adjustments for age, sex, body mass index, glycated haemoglobin, hypertension, dyslipidemia and presence of chronic kidney disease.

Conclusion

Circulating AFABP level at baseline predicted the development of LV hypertrophy, diastolic dysfunction and MACE in T2DM patients without CVD.

Associations between High Serum Adipocyte Fatty Acid Binding Protein and First Hospitalization in Kidney Transplantation Patients: A 5-Year Follow-up Study

Adipocyte fatty acid binding protein (A-FABP) is predictive of type 2 diabetes mellitus incidences and metabolic syndrome and is independently associated with atherosclerosis. The present study aimed to assess the association between serum A-FABP levels and future first hospitalization events in kidney transplantation (KT). We enrolled 72 KT patients from January through April 2012 and followed up on these subjects until June 2017. The first hospitalization events incidence was the primary endpoint. Using a commercially available enzyme immunoassay, serum A-FABP levels were measured from the patient's fasting blood samples. During a median 65-month follow-up, 49 first hospitalization events occurred. KT patients with first hospitalization events had greater incidences of hypertension, diabetes, and higher serum blood urea nitrogen, creatinine, triglyceride, and A-FABP levels than those without the events. Kaplan-Meier analysis showed that the cumulative incidence of first hospitalization events was greater in the high A-FABP group than in the low A-FABP group. Multivariate Cox analysis with significant variables showed that serum A-FABP (hazard ratio = 1.012; 95% confidence interval = 1.000-1.025; p = 0.044) was independently associated with first hospitalization events among KT patients. The results revealed that serum A-FABP is associated with first hospitalization events in KT patients. However, further prospective studies are needed to determine the mechanisms underlying this association.

Fatty Acid Binding Protein 4-A Circulating Protein Associated with Peripheral Arterial Disease in Diabetic Patients

Diabetic patients with peripheral arterial disease (PAD) often suffer from poor clinical outcomes such as limb-loss. Fatty acid binding protein 4 (FABP4) is mainly expressed by adipocytes and is known to play a significant role in the development of atherosclerosis. In this study, we sought to investigate whether FABP4 is associated with PAD in patients with type 2 diabetes mellitus (DM). FABP4 plasma levels were studied in 119 diabetic patients with PAD (DM-PAD) and 49 diabetic patients without PAD (DM-noPAD) presenting to St. Michael’s Hospital between October 2017 and September 2018. Levels of FABP4 in DM-PAD patients (23.34 ± 15.27 ng/mL) were found to be over two-fold higher than the levels in DM-noPAD patients (10.3 ± 7.59 ng/mL). Regression analysis demonstrated a significant association between FABP4 levels and DM-PAD after adjusting for age, sex, prior history of coronary arterial disease and white blood cells count (OR, 2.77; 95% CI, 1.81–4.31; p-value = 0.001). Relative to DM-noPAD controls, plasma FABP4 levels in DM-PAD patients were noted to be inversely correlated with the ankle brachial index (ABI; r= −0.374, p-value < 0.001). The diagnostic ability of FABP4 was investigated using receiver operator curves (ROC) and area under the curve (AUC) analysis. FABP4 had an AUC of 0.79, which improved to 0.86 after adjusting for age, sex and prior history of coronary arterial disease. This raises a possibility of utilizing FABP4 as a biomarker for diagnosing PAD in diabetic patients.

Investigation of 3T3-L1 Cell Differentiation to Adipocyte, Affected by Aqueous Seed Extract of Phoenix Dactylifera L

Background

Obesity, often associated with insulin resistance and type 2 diabetes, is a metabolic disease that can result in dyslipidemia and hyperglycemia. Many reports describe the hypoglycemic and hypolipidemic properties of the Phoenix dactylifera L. seed extract in STZ-induced diabetic rat models, however, its anti-diabetic effects in other diabetic models are less characterized in the literature. This study set out to determine the possible effects of the Phoenix dactylifera L. seed extract on adipogenesis and glucose homeostasis.

Methods

3T3-L1 cells were cultured in adipocyte differentiation media with or without varying doses of Phoenix dactylifera L. extract (0.312-1 mg/ml). Assays were performed on days 5, 8, and 12 after induced differentiation.

Results

Our results demonstrate that the triglyceride content in treated groups was significantly lower compared to controls. Further, treating 3T3-L1 cells with Phoenix dactylifera L. seed extract reduced adipogenesis through the downregulation of PPAR-γ and CEBP-α, and adipocyte-specific genes involved in fatty acid metabolism including ap2, ACACA, and FAS.

Conclusion

Phoenix dactylifera L. seeds have the potential to inhibit adipogenesis and obesity. Overall, this study explored the inhibitory effects of Phoenix dactylifera L. seed extract on adipogenesis in 3T3-L1 cells on the molecular level.

Role of Fatty Acid Binding Protein 4 (FABP4) in Kidney Disease

Accumulating evidences indicated that obesity and metabolic syndrome were independent risk factors for the development and progression of kidney diseases. Apart from inflammation, lipotoxicity, and hemodynamic factors, adipokines have been proposed to play crucial roles in the relationship between kidney diseases and metabolic disorders. As one of the key adipokines, fatty acid binding protein 4 (FABP4), which is mainly expressed in adipocytes and macrophages, has recently been shown to be associated with renal dysfunction and kidney damage. Both clinical and experimental studies have proposed circulating FABP4 as a novel predictor for renal injuries, and it might also be a predictor for cardiovascular events in patients with end stage renal disease (ESRD). FABP4 has also been detected in the glomerular cells and epithelial tubular cells in mouse and human kidneys, and the expression of FABP4 in these cells has been involved in the pathogenesis of kidney diseases. In addition, experimental studies suggested that inhibition of FABP4 had protective effects on renal damage. Here, we reviewed current knowledge regarding the role of FABP4 in pathophysiological insights as well as its potential function as a predictor and therapeutic target for kidney diseases.

The influence of equine body weight gain on inflammatory cytokine expressions of adipose tissue in response to endotoxin challenge

Background

Human obesity is linked with systemic inflammation. However, it is still controversial if equines produce more inflammatory cytokines with increasing body weight and if the production of those show breed type specific patterns. The main objective of this study was to determine if diet induced obesity is associated with increased inflammatory signatures in adipose tissue of equines and if a breed predisposition exists between ponies and horses. Additionally, we aimed to identify adipose tissue depot differences in inflammatory cytokine expression. Nineteen healthy, non-overweight and metabolically healthy equines received a hypercaloric diet for 2 years. Body weight, body condition score and cresty neck score were assessed weekly throughout the study. At three time points, insulin sensitivity was determined by a combined glucose-insulin test. Adipose tissue samples were collected from two intra-abdominal and two subcutaneous depots under general anesthesia at each time point after an endotoxin trigger. In the adipose tissue samples levels of CD68 mRNA (a marker of macrophage infiltration) and pro-inflammatory cytokine mRNA (IL-1β, IL-6 and TNFα) were analyzed with RT-qPCR. As markers of lipid metabolism mRNA levels of lipoprotein lipase (LPL) and fatty acid binding protein 4 (FABP4) were determined with RT-qPCR.

Results

CD68 mRNA levels increased with body weight gain in several adipose tissue (AT) depots (Wilcoxon signed rank test with Bonferroni correction; retroperitoneal AT horses: P = 0.023, mesocolonial AT horses: P = 0.023, subcutaneous tail head AT ponies: P = 0.015). In both abdominal depots CD68 mRNA levels were higher than in subcutaneous adipose tissue depots (Kruskal–Wallis-ANOVA with Bonferroni correction: P < 0.05). No breed related differences were found. Pro-inflammatory cytokine mRNA IL-1β, IL-6 and TNFα levels were higher in subcutaneous depots compared to abdominal depots after body weight gain. IL-1β, IL-6 and TNFα mRNA levels of mesocolon adipose tissue were higher in obese horses compared to obese ponies (Mann–Whitney-U test; IL-1β: P = 0.006; IL-6: P = 0.003; TNFα: P = 0.049). In general, horses had higher FABP4 and LPL mRNA levels compared to ponies in neck AT and tail AT at all time points.

Conclusion

Our findings suggest an increased invasion of macrophages in intra-abdominal adipose tissue with increasing body weight gain in equines in combination with a low dose endotoxin stimulus. This might predispose equines to obesity related comorbidities. In obese horses mesocolon adipose tissue showed higher inflammatory cytokine expression compared to obese ponies. Additionally, subcutaneous adipose tissue expressed more pro-inflammatory cytokines compared to intra-abdominal adipose tissue. Horses had higher FABP4 and LPL mRNA levels in selected AT depots which may indicate a higher fat storage capacity than in ponies. The differences in lipid storage might be associated with a higher susceptibility to obesity-related comorbidities in ponies in comparison to horses.

Exogenous FABP4 interferes with differentiation, promotes lipolysis and inflammation in adipocytes

PURPOSE

Fatty acid binding protein 4 (FABP4) has been demonstrated to be secreted from adipocytes in an unconventional pathway associated with lipolysis. Circulating FABP4 is elevated in metabolic disorders and has been shown to affect various peripheral cells such as pancreatic β-cells, hepatocytes and macrophages, but its effects on adipocytes remains unclear. The aim of this study was to investigate the effects of exogenous FABP4 (eFABP4) on adipocyte differentiation and function.

METHODS

3T3-L1 pre-adipocytes or mature adipocytes were treated with recombinant FABP4 in the absence or presence of FABP4 inhibitor I-9/p38 MAPK inhibitor SB203580; Meanwhile male C57BL/6J mice were subcutaneously injected twice a day with recombinant FABP4 (0.35 mg/kg) with or without I-9 (50 mg/kg) for 2 weeks. The effects of eFABP4 on differentiation, lipolysis and inflammation were determined by triglyceride measurement or lipolysis assay, western blotting, or RT-qPCR analysis.

RESULTS

eFABP4 treatment significantly reduced intracellular triglyceride content and decreased expression of adipogenic markers peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), intracellular FABP4, and adiponectin in 3T3-L1 cells. Besides, eFABP4 promoted lipolysis and inflammation in differentiated 3T3-L1 adipocytes as well as in adipose tissue of eFABP4-treated C57BL/6J mice, with elevated gene expression of monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF)-α, and elevated protein expression of adipose triglyceride lipase (ATGL), phosphorylation of hormone-sensitive lipase (HSL) (Ser-660), p38, and nuclear factor-kappa B (NF-κB). The pro-inflammatory and pro-lipolytic effects of eFABP4 could be reversed by SB203580/I-9.

CONCLUSIONS

These findings indicate that eFABP4 interferes with adipocyte differentiation, induces p38/HSL mediated lipolysis and p38/NF-κB mediated inflammation in adipocytes in vitro and in vivo.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.