Abstract
Glucocorticoids (GCs) have been employed as immunosuppressive agents for many years. However, it is still unclear how GCs instantly uncouple T cells from acute stressful inflammatory. In terms of time scale, the genomic activity of the classic GC receptor cannot fulfill this role under crisis; but a rapid non-genomic response can. In a previous study, intracellular acidification was found to be due to a rapid non-genomic inhibition of Na+/H +-exchange 1 (NHE1) and this event led to the immunosuppression of T cell proliferation by progesterone. The aim of this study was to examine whether there is a rapid acidification response caused by an inhibition of NHE1 activity and to explore the differential non-genomic effect on immunosuppression of hydrocortisone and dexamethasone. The IC50 values for NHE1-dependent pHi recovery by hydrocortisone and dexamethasone are 250 and 1 nM, respectively. Co-stimulation of GCs with phytohemagglutinin (PHA) is able to inhibit PHA-induced IL-2 secretion, IL-4 secretion, and T-cell proliferation. Furthermore, apoptosis in PHA-activated T cells is not induced by hydrocortisone but by dexamethasone. The mechanism of immunosuppression on proliferation by dexamethasone was found to be different of hydrocortisone and seems to involve cytotoxicity against T cells. Moreover, apoptosis induced by dexamethasone and impermeable dexamethasone - bovine serum albumin suggests that the apoptotic immunosuppression occurs through both the plasma membrane and cytoplasmic sites. The rapid inhibitory responses triggered by GCs would seem to release T cells instantly when an acute stress-related response is needed. Nonetheless, the apoptotic immunosuppression by dexamethasone is attributable to its severe cytotoxicity.
Original language | English |
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Pages (from-to) | 679-686 |
Number of pages | 8 |
Journal | Journal of Cellular Physiology |
Volume | 223 |
Issue number | 3 |
DOIs | |
State | Published - 06 2010 |