Glucocorticoid receptor hypersensitivity enhances inflammatory signaling and inhibits cell cycle progression in porcine PBMCs

Abstract

The consequences of glucocorticoid receptor (GR) hypersensitivity during infection have so far received little attention. We previously discovered that a natural gain-of-function Ala610Val substitution in the porcine GR aggravates response of pigs to lipopolysaccharide (LPS)-induced endotoxemia, which can be alleviated by dexamethasone (DEX) pretreatment. In this work, we investigated the relevant molecular basis of these phenotypes by transcriptomic profiling of porcine peripheral blood mononuclear cells (PBMCs) carrying different GR genotypes, in unstimulated conditions or in response to DEX and/or LPS in vitro. The Val allele differentially regulated abunda+nt genes in an additive-genetic manner. A subset of more than 200 genes was consistently affected by the substitution across treatments. This was associated with upregulation of genes related i.a. to endo-lysosomal system, lipid and protein catabolism, and immune terms including platelet activation, and antigen presentation, while downregulated genes were mainly involved in cell cycle regulation. Most importantly, the set of genes constitutively upregulated by Val includes members of the TLR4/LPS signaling pathway, such as LY96. Consequently, when exposing PBMCs to LPS treatment, the Val variant upregulated a panel of additional genes related to TLR4 and several other pattern recognition receptors, as well as cell death and lymphocyte signaling, ultimately amplifying the inflammatory responses. In contrast, when stimulated by DEX treatment, the Val allele orchestrated several genes involved in anti-inflammatory responses during infection. This study provides novel insights into the impact of GR hypersensitivity on the fate and function of immune cells, which may be useful for endotoxemia therapy.

Heat-Induced Secretion of Heat Shock Proteins 70 and 90 Does not Affect the Expression of the Glucocorticoid Receptor in Primary Airway Cells in COPD

“…Further studies using endobronchial tissue biopsies from patients with COPD are needed to confirm the in vitro data presented in this study and to elucidate under which clinical conditions the anti-inflammatory effect of eHSPs will counterbalance the pro-inflammatory effect of TLR4. Other studies, however, indicated that the interaction between LPS and TLR4 led to an increased sensitivity to steroids in cell and animal models [ 32 , 33 ]. The different effects of TLR4 on the regulation of GR imply that assessment of such mechanisms has to carefully consider cell- or species-specific signaling sequences.…”

“…A significant limitation of our study is the short life span and limited expansion of primary human BECs, which hindered obtaining a sufficient number of cells for an in-depth investigation into the exact mechanisms underlying the reduced expression of TLR4 in response to HSP70 and HSP90. This constraint also prevented further experiments to explore whether the interaction of TLR4 with the GR might be cell-type or organ-specific [ 43 ], or if TLR4 and GR interact with the same chaperone proteins such as HSPs to regulate basic cell functions, and whether silencing either molecule may impact the function of the other [ 33 ]. However, a strength of our study is that it is the first to involve primary BEC and ASMC from a well-characterized COPD cohort, distinguishing between responders and non-responders to ICS, based on a randomized, placebo-controlled clinical trial.…”