Cytotoxic Actions of FTY720, a Novel Immunosuppressant, on Thymocytes and Brain Neurons Dissociated From the Rat

Abstract

Effects of FTY720 (2-amino-2-(2-[4-octylphenyl]ethyl)-1,3-propanediol HCl), a novel immunosuppressant, were examined on neurons and thymocytes respectively dissociated from rat brains and thymus glands using a flow cytometer to see if FTY720 exerts cytotoxic actions not only on spleen cells as previously reported but also on the other cells. FTY720 at a concentration of 10 microM deteriorated almost all of the thymocytes, while it was not the case for brain neurons. FTY720 increased the intracellular concentration of Ca2+ ([Ca2+]i) of thymocytes in both the presence and absence of external Ca2+, although the [Ca2+]i increased by FTY720 in the presence of external Ca2+ was much greater than that in the absence of external Ca2+. Thus, FTY720 may increase the membrane permeability of Ca2+ and release Ca2+ from intracellular Ca2+ stores in thymocytes. Furthermore, the number of thymocytes stained with ethidium, a dye impermeant to intact membranes, time-dependently increased after drug application. Therefore, FTY720 at concentrations of 3 - 10 microM non-specifically increases the membrane permeability of thymocytes, resulting in necrotic cell death, although FTY720 at micromolar concentrations was reported to induce apoptosis of spleen cells.

Effect of Fingolimod on Neural Stem Cells: A Novel Mechanism and Broadened Application for Neural Repair

“…45 In the previously mentioned chemical-induced demyelination models, FTY720 had been either directly injected into the demyelination foci, in which an extremely high concentration in situ (2 mg/mL; 6.7 mM) of FTY720 would be toxic and kill OPCs and OLGs, or it was administered as an oral treatment at a dosage of 1 mg/kg/day. 52 In in vitro studies, Oyama et al showed that FTY720 treatment was cytotoxic to neurons at high concentrations (>30 mM), 53 while Miron et al reported that low doses of FTY720 (0.1-1 nM) induced OLG membrane elaboration, with higher doses (10 nM to 1 mM) causing the opposite modulation of membrane dynamics. 45 Consistent with these findings, our in vitro results showed that low doses of FTY720 (%5 nM) are safe and have positive effects on NSC proliferation, driving NSCs to differentiate into greater numbers of neurons, OPCs, and OLGs but fewer astrocytes, while at high concentrations (e.g., 10 nM) FTY720 reduced numbers of OLGs and even induced OLG death.…”

Central nervous system-directed effects of FTY720 (fingolimod)

“…Although FTY720 is distributed to the brain, it does not seem to be primarily located in neurons suggesting that impacts on neuronal function may be limited. Accordingly, in vitro studies indicate that only supra-physiological micromolar concentrations of FTY720 can lead to apoptosis in rat cerebellar neurons [65].…”

“…Many studies have shown that FTY720 is highly effective in different EAE models, both prophylactically and therapeutically [65][66][67][68][69]. In both mouse and rat models, treatment with FTY720 is associated with a pronounced reduction in inflammatory infiltrates (T cells, B cells and macrophages), demyelination and axonal loss.…”

Is overall blockade superior to selective blockade of adrenergic receptor subtypes in suppressing left ventricular remodeling in spontaneously hypertensive rats?

“…16 The myocardial cells were harvested and resuspended in PBS buffer without Ca 2+ and Mg 2+ . A 490 ml myocardial cell (4Â10 6 ml À1 ) suspension was then incubated with 10 ml Fluo-3/AM buffer (1.0 mM, Dojindo, Kumamoto, Japan) for 30 min at 37 1C, then washed twice and resuspended in PBS buffer.…”