Endocrine Abstracts

Increased fatty acid (FA) concentration is implicated in the development of insulin resistance (IR) in tissues such as the kidney. Research indicates the protective role of glucagon-like peptide (GLP)-1 receptor agonists; GLP-1 (7-36) amide and incretin mimetic; liraglutide, against IR. We aimed to induce IR in HEK293T cells, using the three most abundantly consumed FAs; palmitate, oleate, and stearate, or in a combination termed POS. This model was used to assess the extent of protection upon co-treatment with 1µM GLP-1 amide and liraglutide, in HEK293T cells, following IR and hypoxia (2% O₂). To increase physiological relevance, studies were performed under traditional 2D methodologies and 3D spheroid cultures. Palmitate (50-750µM) induced the highest toxicity (up to 60%) compared to all other FAs at all concentrations using the alamarBlue assay. Stearate offered the lowest toxicity (33%), whilst POS appeared to be an average of all three. Hypoxia increased toxicity of palmitate treated cells in comparison to normoxia. Co-administration of GLP-1 agonist with POS, significantly reduced cellular toxicity in both normoxic and hypoxic conditions, when compared to POS-only (P ≤ 0.05). 3D viability studies showed a reduction in toxicity of all FAs when compared to 2D. Interestingly, GLP-1 agonists offered higher protection at high concentrations of FA (500 and 650µM) compared to 2D. To determine the mechanism of action for GLP1 agonists, several key proteins in the GLP-1R cascade were targeted. Inhibition of CPT1 (Etomoxir) or PPARα (GW6471), in the presence of fatty acids, decreased toxicity, similar to the effects of GLP1. In conclusion, the presence of FAs in HEK293Ts decreases cell viability and induced IR, which can be partially reversed using GLP-1 agonists. GLP-1 and liraglutide may offer therapeutic management of FA-induced toxicity, although the mechanism of protection needs further investigation, it appears to involve PPARα and handling of mitochondrial FA uptake.