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

Investigating the Role of FABP4 in Diabetes and Obesity and the Influence of Age and Ethnicity: A Comprehensive Analysis of a Cohort from the KEDP-Study

Adipocyte P2 (aP2), also known as FABP4, is an adipokine that adipose tissue produces and expresses in macrophages. Its primary role is to facilitate the transportation of fatty acids across cell membranes. Numerous studies have reported associations between FABP4 and the development of metabolic disorders. However, there is limited knowledge regarding FABP4 expression in diabetes and obesity, especially about different age groups, genders, and ethnicities. This study aims to investigate the association between FABP4 levels, diabetes mellitus, and obesity within various ethnic groups. We measured plasma FABP4 concentrations in a cohort of 2083 patients from the KDEP study and gathered anthropometric data. Additionally, we collected and analyzed clinical, biochemical, and glycemic markers using multivariate regression analysis. The average FABP4 concentration was significantly higher in female participants than in males (18.8 ng/mL vs. 14.4 ng/mL, p < 0.001, respectively), and in those over 50 years old compared to those under 50 years of age (19.3 ng/mL vs. 16.2 ng/mL, p < 0.001, respectively). In this study, significant positive associations were found between the plasma level of FABP4 and obesity markers: BMI (r = 0.496, p < 0.001), hip circumference (r = 0.463, p < 0.001), and waist circumference (WC) (r = 0.436, p < 0.001). Similar observations were also seen with glycemic markers, which included HbA1c (r = 0.126, p < 0.001), fasting blood glucose (FBG) (r = 0.184, p < 0.001), fasting insulin (r = 0.326, p < 0.001), and HOMA-IR (r = 0.333, p < 0.001). Importantly, these associations remained significant even after adjusting for age, gender, and ethnicity. Furthermore, FABP4 levels were negatively associated with male gender (β: -3.85, 95% CI: -4.92, -2.77, p < 0.001), and positively associated with age (β: 0.14, 95% CI: 0.096, 0.183, p < 0.001), BMI (β: 0.74, 95% CI: 0.644, 0.836, p < 0.001), and fasting insulin (β: 0.115, 95% CI: 0.091, 0.138, p < 0.001). In this study, plasma FABP4 levels were significantly higher in diabetic and obese participants, and they were strongly influenced by age, gender, and ethnicity. These findings suggest that FABP4 may serve as a valuable prognostic and diagnostic marker for obesity and diabetes, particularly among female patients, individuals over 50 years old, and specific ethnic groups.

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.

Reproductive Immunology and Pregnancy 3.0

This Special Issue, the third dedicated to reproductive immunology and pregnancy, is another review of the latest trends in research topics in this field [...].

Adipose tissue-derived FABP4 mediates glucagon-stimulated hepatic glucose production in gestational diabetes

AIMS

One of the most common complications of pregnancy is gestational diabetes mellitus (GDM), which may result in significant health threats of the mother, fetus and the newborn. Fatty acid-binding protein 4 (FABP4) is an adipokine that regulates glucose homeostasis by promoting glucose production and liver insulin resistance in mouse models. FABP4 levels are increased in GDM and correlates with maternal indices of insulin resistance, with a rapid decline post-partum. We therefore aimed to determine the tissue origin of elevated circulating FABP4 levels in GDM and to assess its potential contribution in promoting glucagon-induced hepatic glucose production.

MATERIALS AND METHODS

FABP4 protein and gene expression was determined in biopsies from placenta, subcutaneous (sWAT) and visceral (vWAT) white adipose tissues from GDM and normoglycaemic pregnant women. FABP4 differential contribution in glucagon-stimulated hepatic glucose production was tested in conditioned media before and after its immune clearance.

RESULTS

We showed that FABP4 is expressed in placenta, sWAT and vWAT of pregnant women at term, with a significant increase in its secretion from vWAT of women with GDM compared with normoglycaemic pregnant women. Neutralizing FABP4 from both normoglycaemic pregnant women and GDM vWAT secretome, resulted in a decrease in glucagon-stimulated hepatic glucose production.

CONCLUSIONS

This study provides new insights into the role of adipose tissue-derived FABP4 in GDM, highlighting this adipokine, as a potential co-activator of glucagon-stimulated hepatic glucose production during pregnancy.

Pathophysiological Insight into Fatty Acid-Binding Protein-4: Multifaced Roles in Reproduction, Pregnancy, and Offspring Health

Fatty acid-binding protein-4 (FABP4), commonly known as adipocyte-fatty acid-binding protein (A-FABP), is a pleiotropic adipokine that broadly affects immunity and metabolism. It has been increasingly recognized that FABP4 dysfunction is associated with various metabolic syndromes, including obesity, diabetes, cardiovascular diseases, and metabolic inflammation. However, its explicit roles within the context of women's reproduction and pregnancy remain to be investigated. In this review, we collate recent studies probing the influence of FABP4 on female reproduction, pregnancy, and even fetal health. Elevated circulating FABP4 levels have been found to correlate with impaired reproductive function in women, such as polycystic ovary syndrome and endometriosis. Throughout pregnancy, FABP4 affects maternal-fetal interface homeostasis by affecting both glycolipid metabolism and immune tolerance, leading to adverse pregnancy outcomes, including miscarriage, gestational obesity, gestational diabetes, and preeclampsia. Moreover, maternal FABP4 levels exhibit a substantial linkage with the metabolic health of offspring. Herein, we discuss the emerging significance and potential application of FABP4 in reproduction and pregnancy health and delve into its underlying mechanism at molecular levels.

Adipokines in Pregnancy: A Systematic Review of Clinical Data

Adipokines are signaling proteins involved in metabolic, endocrinological, vascular and immunogenic processes. Associations of various adipokines with not only insulin resistance but also with increased insulin sensitivity, increased systolic blood pressure, and atherosclerosis highlight the significance of adipokines in several components of metabolic syndrome and metabolic diseases in general. As pregnancy presents a unique metabolic state, the role of adipokines in pregnancy, and even in various pregnancy complications, appears to be key to elucidating these metabolic processes. Many studies in recent years have attempted to clarify the role of adipokines in pregnancy and gestational pathologies. In this review, we aim to investigate the changes in maternal adipokine levels in physiological gestation, as well as the association of adipokines with pregnancy pathologies, such as gestational diabetes mellitus (GDM) and preeclampsia (PE). Furthermore, we will analyze the association of adipokines in both maternal serum and cord blood with parameters of intrauterine growth and various pregnancy outcomes.