The effect of long-chain n-3 PUFA on liver transcriptome in human obesity

Background and aims

Obesity is associated with a higher risk of severe diseases such as atherosclerotic cardiovascular disease, type 2 diabetes mellitus (T2DM), and metabolic dysfunction-associated steatotic liver disease (MASLD). Polyunsaturated fatty acids, of the omega-3 family (n-3 PUFA), have been shown to reduce adipose tissue inflammation in obesity, as well as to have lipid-lowering effects and improve insulin sensitivity. However, direct effects on liver transcriptome in humans have not been described. Our aim was to understand the impact of n-3 PUFA on gene expression in obese human liver.

Approach and Results

Patients with obesity (BMI $\ge$ 40 kg/m²) were treated for eight weeks with 3.36 g n-3 PUFAs (1.84 g eicosapentaenoic acid (EPA) and 1.53 g docosahexaenoic acid (DHA)), or with 5 g of butter as a control (n = 15 per group) before undergoing bariatric surgery where liver biopsies were taken. Liver samples were used for mRNA microarray analyses and subsequently Gene Set Enrichment Analysis (GSEA) was performed. This bioinformatic approach led us to identify 80 significantly dysregulated pathways that were divided into 9 different clusters including insulin and lipid metabolism, and immunity. N-3 PUFA treatment significantly affected pathways related to immunity, metabolism, and inflammation. Specifically, it upregulated pathways involved in T-cell and B-cell functions and lipid metabolism, while downregulating glucagon signalling. These findings highlight the impact of n-3 PUFAs on key metabolic and immune processes in the liver of patients with obesity.

Conclusion

This study provides further insights into the impact on n-3 PUFA on human liver gene expression, particularly in pathways associated with immunity, lipid metabolism, and inflammation, setting basis for further clinical research.

Summary

Obesity increases the risk of diseases like atherosclerotic- cardiovascular disease, type 2 diabetes mellitus and metabolic dysfunction-associated steatotic liver disease (MASLD). Omega-3 polyunsaturated fatty acids (n-3 PUFA) are known for their anti-inflammatory and metabolic benefits, but their direct impact on liver gene expression in people with obesity, remains unclear. In this study, patients with obesity (BMI ≥ 40 kg/m2) were administered either n-3 PUFAs or butter before bariatric surgery. Liver biopsies were analysed for gene expression via Gene Set Enrichment Analysis (GSEA). The results revealed 80 dysregulated pathways across 9 clusters, including those related to insulin and lipid metabolism, and immunity. This sheds light on how n-3 PUFAs influence gene expression in the liver of patients with obesity, setting the groundwork for further clinical exploration.