Trypanosoma cruzi induces changes in gene expression of glucocorticoid and prolactin receptors in CD4⁺CD8⁺ cells and alters their sensitivity to GC-induced apoptosis.

<p>Panel <b>A</b> (left) shows gene expression levels for the receptors for glucocorticoids (GR) and prolactin (PRLR) in CD4⁺CD8⁺ thymocytes, as ascertained by real time quantitative PCR. There is a progressive decrease in GR expression levels during T. cruzi infection, which were paralleled by an increase in PRLR gene expression. The values were normalized to the endogenous reference transcript RPL-13. Values are expressed as fold changes related to uninfected animals and represented as (2<b>^−ΔΔct</b>). Panel <b>A</b> (right) represents the ratio of GR/PRLR in CD4⁺CD8⁺ thymocytes during infection. These data are representative of three independent experiments using three mice per group in each experiment. Statistically significant differences (p<0.05) between uninfected versus infected (<b>*</b>) or between 8 and 15 dpi (<b>#</b>) mice. Panel <b>B</b> (left) depicts progressive increase in apoptosis (revealed by the relative numbers of Annexin V⁺CD4⁺CD8⁺ cells). We can see that in cells treated with vehicle alone or after inbubation with dexamethasone (DEX) there is an increase in the numbers of apoptotic thymocytes. However, if we evaluate the ratio of vehicle-treated over DEX-treated cells (panel <b>B</b> right) the sensitivity to DEX-induced apoptosis on CD4⁺CD8⁺ thymocytes is significantly decreased as disease progresses. Thymyses were removed from uninfected, 8 and 15 dpi mice and homogenized. One million cells/animal were incubated with DEX (10⁻⁹ M) or RPMI (vehicle) during 8 hours under 37°C at 5% CO₂ atmosphere. Thymocytes were then washed and incubated with anti-CD4/APC, anti-CD8/PercP or Annexin-V/FITC, for the cytofluorometric characterization of apoptosis within each thymocyte subset. These data are representative of two independent experiments using five mice per group in each experiment. Statistically significant differences (p<0.05) between uninfected versus infected (<b>*</b>) or between 8 and 15 dpi (<b>#</b>) mice. *p<0.05; **p<0.01, ***p<0.001.