Thymosin beta 4 prevents systemic lipopolysaccharide-induced plaque load in middle-age APP/PS1 mice.

Lipopolysaccharide (LPS) produced by the gut during systemic infections and inflammation is thought to contribute to Alzheimer's disease (AD) progression. Since thymosin beta 4 (Tß4) effectively reduces LPS-induced inflammation in sepsis, we tested its potential to alleviate the impact of LPS in the brain of the APPswePS1dE9 mouse model of AD (APP/PS1) and wildtype (WT) mice. 12.5-month-old male APP/PS1 mice (n = 30) and their WT littermates (n = 29) were tested for baseline food burrowing performance, spatial working memory and exploratory drive in the spontaneous alternation and open-field tests, prior to being challenged with LPS (100ug/kg, i.v.) or its vehicle phosphate buffered saline (PBS). Tß4 (5 mg/kg, i.v.) or PBS, was administered immediately following and at 2 and 4 h after the PBS or LPS challenge, and then once daily for 6 days (n = 7-8). LPS-induced sickness was assessed though monitoring of changes in body weight and behaviour over a 7-day period. Brains were collected for the determination of amyloid plaque load and reactive gliosis in the hippocampus and cortex. Treatment with Tß4 alleviated sickness symptoms to a greater extent in APP/PS1 than in WT mice by limiting LPS-induced weight loss and inhibition of food burrowing behaviour. It prevented LPS-induced amyloid burden in APP/PS1 mice but increased astrocytic and microglial proliferation in the hippocampus of LPS-treated WT mice. These data show that Tß4 can alleviate the adverse effects of systemic LPS in the brain by preventing exacerbation of amyloid deposition in AD mice and by inducing reactive microgliosis in aging WT mice.

Rapid Assessment of Insect Steroid Hormone Entry Into Cultured Cells.

Steroid hormones control development and homeostasis in a wide variety of animals by interacting with intracellular nuclear receptors. Recent discoveries in the fruit fly Drosophila melanogaster revealed that insect steroid hormones or ecdysteroids are incorporated into cells through a membrane transporter named Ecdysone Importer (EcI), which may become a novel target for manipulating steroid hormone signaling in insects. In this study, we established an assay system that can rapidly assess EcI-mediated ecdysteroid entry into cultured cells. Using NanoLuc Binary Technology (NanoBiT), we first developed an assay to detect ligand-dependent heterodimerization of the ecdysone receptor (EcR) and retinoid X receptor (RXR) in human embryonic kidney (HEK) 293T cells. We also developed HEK293 cells that stably express EcI. By combining these tools, we can monitor ecdysteroid entry into the cells in real time, making it a reliable system to assess EcI-mediated steroid hormone incorporation into animal cells.