Bacterial pathogen–associated molecular patterns upregulate human glucocorticoid receptor expression in peripheral blood mononuclear cells

It is well known that bacterial components (pathogen-associated molecular patterns [PAMPs]) induce a proinflammatory response through pattern recognition receptor signaling. What is not known, however, is how the inflammatory response is downregulated. We hypothesize that bacterial products initiate compensatory anti-inflammatory responses by inducing expression of the human glucocorticoid receptor (hGR). Peripheral blood mononuclear cells (PBMCs) were isolated from leukocytes concentrated from single human donors (Leukopaks). PBMCs were treated with a gram-negative bacterial component, LPS, or gram-positive bacterial components, lipoteichoic acid (LTA) or peptidoglycan (PGN), for 1, 3, or 13 h. Protein expression of hGR was evaluated by Western blot analysis. RNA was extracted from similarly treated cells for reverse transcription-polymerase chain reaction analysis of hGR and cytokine expression. At 13 h after LPS treatment, there was an increase in the reference hGR protein (hGRα) expressed within some but not all PBMCs isolated from Leukopaks. There was also a dose-dependent increase in hGRα expression with increasing concentrations of PGN (10 and 50 μg/mL). LTA, however, did not affect hGRα expression. PGN also increased the mRNA expression of an hGR splice variant, hGR-B(54). The mRNA expression changes for the inflammatory cytokines were Leukopak specific. We found that cell wall components of both gram-positive and gram-negative bacteria can increase the expression...
Source: Shock - Category: Emergency Medicine Tags: Clinical Science Aspects Source Type: research