Immunometabolic regulation by triterpene-enriched fraction of Eucalyptus tereticornis in adipose tissue cell line models

Obesity is associated with adipose tissue inflammation that eventually results in insulin resistance (IR) and it is linked with type 2 diabetes mellitus [1]. Previous studies established the beneficial effects of fractions of Eucalyptus tereticornis (Eu) on carbohydrate metabolism in a diabetic mouse model. In addition, they showed a reduction in levels of proinflammatory cytokines in adipose tissue [2]. Our aim is to evaluate the effect of Eu fractions on inflammation and IR using murine adipocyte and macrophage cell lines.

A crude methanolic extract (OBE100) from leaves of Eu was partitioned with ethyl acetate and purified by Sephadex LH-20. The fractions containing triterpenes (OBE104) were used for biological assays. 3T3-L1 adipocytes were pre-treated for 7 days or treated for 24h after differentiation with OBE100 and OBE104. Fatty acid content was evaluated by oil red staining. Macrophage cell line J774, activated with LPS and INFγ, was used to evaluate OBE100 and OBE104 anti-inflammatory action. Gene expression levels of TNFα, IL6, IL1β and MCP1 were detected by real-time RT-PCR. In addition, protein expression levels of TNFα, IL6 and MCP1 were monitored by flow cytometry.

OBE100 and OBE104 reduced mRNA and protein expression of pro-inflammatory cytokines MCP1, IL1β, IL6 and TNFα in activated macrophages. Additionally, a reduction of the intracellular fatty acid content in adipocytes pre-treated for 7 days with Eu fractions was observed. This effect was not detected in adipocytes treated for 24h after differentiation.

These results suggest that Eu fractions inhibit lipogenic activity. This study demonstrates the role of triterpenes from Eu on the regulation of immunometabolic response in cells present in adipose tissue. Our results allow us to suggest that the systemic effects observed on carbohydrate metabolism with the treatment of fractions of Eu could be explained by their action on the inflammation process established in adipose tissue of obese mice.

Acknowledgements: This research was supported by the Colciencias grant 111565740656.

Keywords: Eucalytus spp., anti-inflammatory, triterpenes, adipocytes, macrophages.

References:

[1] Lumeng CN, Deyoung SM, Bodzin JL, Saltiel AR. Increased inflammatory properties of adipose tissue macrophages recruited during diet-induced obesity. Diabetes 2007; 56: 16 – 23

[2] Guillén A, Granados S, Rivas KE, Estrada O, Echeverri F, Balcázar, N. Antihyperglycemic activity of Eucalyptus tereticornis in insulin resistant cells and a nutritional model of diabetic mice. Adv Pharm Sci 2015; 1 – 10