Epigenetic effects of a high-calorie, high-fat diet and micronutrient supplementation in animals with lupus

Author(s)

Amanda Alves Ribeiro

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2024-05-23

Examining board members

Carolina Nicoletti Ferreira Fino; Guilherme Giannini Artioli; Marcela Augusta de Souza Pinhel; Lígia Moriguchi Watanabe

• Advisor: Carolina Nicoletti Ferreira Fino

Abstract

Introduction: Systemic lupus erythematosus (SLE) is a complex condition associated with immune dysregulation, where the pathophysiology results from the interaction between genetic, epigenetic, and environmental factors, including diet. Thus, DNA methylation patterns are emerging as a crucial element in the development of autoimmunity, disease progression, and response to treatments. Furthermore, obesity represents an additional risk for complications, exacerbating the inflammatory state and severity of SLE, likely due to the increased secretion of inflammatory adipokines. Objective: This exploratory study aimed to evaluate the DNA methylation profile and the expression of the genes Dnmt1, Il-6, TNF-alpha, Stat3, and Lep in adipose tissue of an SLE animal model fed either a standard diet or a high-calorie, high-fat diet; additionally, the study sought to investigate the effects of folic acid and vitamin B12 supplementation on these variables. Materials and Methods: Thirty female NZBWF1/J mice were randomly assigned into four groups according to the diet received over 12 weeks of the experimental protocol: 1. Standard Diet Group (SD, n = 7) receiving regular chow (4.2 kcal/g), 2. Obesity Group (HFD, n = 7) receiving high-calorie, high-fat chow (6.6 kcal/g); 3. Supplemented Standard Diet Group (SDS, n = 8) receiving regular chow with supplementation, and 4. Supplemented Obesity Group (HFDS, n = 8) receiving high-calorie, high-fat chow with supplementation. The supplementation consisted of 8 mg of folic acid and 50 g of vitamin B12 per kg of chow. After 12 weeks, adipose tissue samples were collected for DNA and RNA extraction using specific commercial kits. DNA methylation analysis was performed using the Infinium Mouse Methylation BeadChip assay, while gene expression was assessed by polymerase chain reaction. Changes () in methylation levels at each CpG site were calculated, considering a minimum value of 5%, p<0.001, and a false discovery rate <0.05. Results: The HFD group animals gained twice as much weight as those in the SD group (14.5±1.6 g vs. 7.5±2.7 g, p< 0.05); however, there were no significant weight differences between the SDS vs. SD and HFDS vs. HFD groups. A total of 193 differentially methylated CpG sites (DMCpGs) were identified between the SD and HFD groups, associated with genes involved in insulin signaling and leukocyte transendothelial migration pathways. Between the SD and SDS groups, 79 DMCpGs were found related to genes in the adipocyte lipolysis regulation pathway and cytokine-cytokine receptor interaction. Comparing the HFD and HFDS groups revealed 356 DMCpGs related to genes in the insulin signaling and cytosolic DNA sensing pathways. Notably, TNF-alpha and Stat3 expression was lower in the supplemented groups compared to the non-supplemented ones. Conclusion: Animals fed a high-calorie, high-fat diet displayed different DNA methylation and gene expression profiles compared to those fed a standard diet, highlighting hypomethylation of genes associated with inflammation and insulin resistance. The DNA methylation profile and target gene expression differed between animals fed a supplemented diet and those on a standard diet, modulating genes involved in the inflammation and autoimmunity cascade (AU)

• FAPESP's process: 21/09753-8 - Epigenetic effects of high fat diet in adipose tissue of animals with lupus
• Grantee: Amanda Alves Ribeiro
• Support Opportunities: Scholarships in Brazil - Master