A-FABP and E-FABP as cutaneous biomarkers of Metabolic Syndrome
Authors: Donjuán-Loredo Guadalupe E. , Espinosa-Tanguma Ricardo , Ramírez-Elías Miguel G. , Medina-Hernández Alejandra 
Published: May 2024

Introduction: In Metabolic syndrome (MetS), tissues such as adipose, liver, and skin with very active lipid metabolism are dysfunctional, making it diffcult to store the excess fat. Fatty acid binding proteins (FABPs) are cytosolic proteins that can reversibly bind to lipids and transport them to different cell organelles. In this work, we focus on adipocyte (A-FABP) and epidermal (E-FABP) FABPs, which have been proposed as potential biomarkers of MetS due to their different tissue expression patterns. When MetS impacts the skin, the integrity of the barrier is affected, such as changes in the structure and function of collagen fibers, changes in microcirculation and macrocirculation, damage to lymphatic vessels, diffculty in wound healing, increased production of sebum and sweat. All those changes seem to depend on the abnormal function of lipids and FABPs. In MetS, E-FABP and A-FABP increase significantly in serum and probably in the skin in order to facilitate lipid transport. For this reason, they can be considered a molecular sensors of the inflammation induced in the skin by MetS. Objective: Analyze the concentrations of A-FABP and E-FABP in the skin of a MetS model to determine their value as biomarkers. Methods: We used a Wistar rat model (N=32) of MetS with a 41% extra fat diet during 8, 18, 28, and 52 weeks. The protocol was approved by the "Internal Committee for the Care and Use of Laboratory Animals of the Faculty of Medicine of the Autonomous University of San Luis Potosí" (assigned code: BGFMUASLP -07-19). At the end of every period of time (8, 18, etc) a biopsy of the skin (1 cm2) was took and cleaned from connective and subcutaneous adipose tissue. For Western Blot (WB) experiments the protein extraction was performed using cell lysis and homogenization, and 50 μg of protein of each sample was used. The WB was performed following the supplier's specifications and the standardized protocol in our laboratory. The primary antibodies used for incubation were rat A-FABP antibody (R&D Systems, AF1443) and rat E-FABP antibody (R&D Systems, AF1476). The secondary antibody was Goat IgG HRP-conjugated Antibody (R&D Systems, HAF017). As a control gene, GAPDH reconstituted as indicated by the supplier. Bands were visualized using chemiluminescent detection, and their density in each group was analyzed using ImageJ software. Results: animals developed MetS after being 28 weeks in high fat diet showing excess of abdominal fat, hypertension, high triglycerides, and low cholesterol-HDL. At 52 weeks, we observed an increase in total cholesterol and in the severity of the blood lipids mentioned. Also, 40% of the animals showed visible skin lesions characterized by redness, eruptions, scratching marks, and wounds that do not heal, mainly in the cervical region, suggesting an inflammatory process. A-FABP expression was increased in MetS rats at 8 and 18 weeks and remained high at 28 and 52 weeks, although the increase was not significant. On the other hand E-FABP expression increased in MetS rats from week 18 and 28 but decreasing at 52. It suggests a greater presence of the protein and a probable participation of it in the inflammatory processes and skin lesions observed. Conclusions: E-FABP and A-FABP, increase significantly in the skin of MetS rats, mainly in the in the initial stages of MetS. E-FABP can considered a molecular sensor of skin inflammation induced by obesity. We also observed the presence of A-FABP in the skin, probably from subcutaneous adipose tissue. We propose the feasibility of both FABPs as early markers of MetS. This work has been supported by the National Council of Science and Technology (CONAHCYT) Project No. 320024. GE Donjuán-Loredo thanks CONAHCYT CVU 775467. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.