# Transplantation of Soluble Epoxide Hydrolase Inhibitor-Treated Human Brown Adipocytes Promotes Adipose Tissue Activation in High-Fat-Diet-Fed Nude Mice

## TL;DR

Treating human brown fat cells with a specific inhibitor and transplanting them into mice reduced fat buildup and boosted fat-burning genes.

## Contribution

This study shows that sEH inhibition during human brown adipocyte differentiation enhances thermogenic and lipid metabolism gene expression in transplanted mice.

## Key findings

- Mice receiving AUCB 5-treated human brown adipocytes had reduced lipid accumulation in brown adipose tissue.
- Thermogenic proteins PGC1α and UCP1 were upregulated in the transplanted mice.
- Adipocyte size decreased in white adipose tissue of mice with AUCB-treated cells.

## Abstract

Brown adipose tissue (BAT) plays a key role in non-shivering thermogenesis and is a promising target for enhancing energy expenditure to combat obesity. Soluble epoxide hydrolase (sEH) is a cytosolic enzyme that catalyzes the conversion of epoxy fatty acids into less active diols. We have reported that local administration of the sEH inhibitor, t-TUCB, to the endogenous interscapular BAT (iBAT) of diet-induced obese mice decreased serum triglycerides and enhanced the expression of essential genes associated with lipid metabolism. Here, the effects of sEH inhibition by t-AUCB were assessed on human brown adipocyte (HuBr) differentiation and in nude mice transplanted with t-AUCB-treated HuBr. HuBr cells were differentiated with t-AUCB (1–10 µM) or the vehicle (0.1% DMSO). HuBr differentiated with t-AUCB at 5 μM (AUCB 5) or DMSO was mixed with matrix gel and transplanted into the nude mice. The mice were then fed a high-fat diet for eight weeks. The mice receiving AUCB 5-treated HuBr exhibited markedly reduced lipid accumulation in the iBAT compared with DMSO or matrix-only controls, along with increased protein expression of thermogenic PGC1α and UCP1, fatty acid transporter CD36, and CPT1A in the iBAT, while the NFκB inflammatory pathways were suppressed in both the AUCB 5 and DMSO groups. Moreover, the PGC1α and CPT1A protein levels were elevated, and the adipocyte sizes were decreased in the epididymal white adipose tissue of the AUCB 5 group. Our findings indicate that the transplantation of HuBr treated with AUCB 5 may stimulate thermogenesis, enhance lipid metabolism, and reduce inflammation in iBAT.