Defensing intestinal dysbiosis in obesity: Exploring the phyla Bacteroidetes and Firmicutes and the role of LPS endotoxin
Authors: Toledo Gustavo Honório , Faria Camila Belfort Piantino , Prudêncio Pedro Henrique Goveia , Faria Breno Henrique Ferreira 
Published: March 2024

Introduction: Obesity is a complex metabolic disorder influenced by genetic and environmental factors. Individuals with a body mass index (BMI) of 30 or greater are considered obese, but even being overweight (BMI between 25 and 29.9) can have adverse consequences. In Brazil, about 60% of adults were overweight in 2020, indicating a growing concern. In addition to physical transformations, obesity is associated with conditions such as insulin resistance, dyslipidemia, and systemic inflammation, increasing the risk of cardiovascular disease and cancer. Dysbiosis in the gut microbiota, an imbalance between bacterial species, plays a crucial role in the etiology of obesity by influencing metabolic homeostasis. LPS endotoxin, when expressed at high levels, contributes to adipose tissue inflammation and the progression of obesity. Thus, the health of the gut microbiota is essential for maintaining metabolic balance and preventing the development of obesity. Objective: The present study investigates how gut dysbiosis, an imbalance in the microbiota, affects obesity and its complications. In addition, it examines the role of LPS endotoxin in gut inflammation and obesity. Methodology: This literature review used the Pubmed database to analyze the role of gut dysbiosis in obesity. Articles published between 2020 and 2024 that addressed the phyla Bacteroidetes and Firmicutes were included, excluding reviews and articles unavailable in full. The central question was about how dysbiosis and LPS endotoxin contribute to inflammation in obesity. Literature review: The gut microbiota, composed mainly of Firmicutes and Bacteroidetes, plays a crucial role in metabolic health. In obese individuals, there is an imbalance in this composition, associated with a predisposition to obesity and metabolic disorders. Factors such as diet, physical activity, and age influence the composition of the microbiota. Certain bacterial strains, such as Bifidobacterium, have varying effects on obesity. Bariatric surgery can remodel the gut microbiota, contributing to weight loss and improved metabolic health. In addition, obesity triggers chronic inflammation, influenced by the presence of Gram-negative gut bacteria that release LPS endotoxin, contributing to pro-inflammatory conditions. A high-fat diet increases the adhesion of these bacteria to the intestinal mucosa, facilitating their passage into the bloodstream and contributing to obesity and insulin resistance. Conclusion: In this study, we investigated the impact of gut microbiota on obesity and metabolic health. Factors such as diet, physical activity, and age influence the imbalance in the composition of the microbiota, with a predominance of Firmicutes over Bacteroidetes in obese individuals. Reduced Bifidobacterium is associated with obesity, while different bacterial strains can affect body weight differently. Bariatric surgery can alter the microbiota, potentially improving metabolism. Obesity triggers chronic inflammation, with Gram-negative gut bacteria and endotoxins contributing to this process, especially with a high-fat diet. These findings underscore the importance of the gut microbiota in metabolic regulation and suggest therapeutic approaches to treat obesity and associated metabolic conditions.