Estradiol Regulates Expression of Estrogen Receptor ERα46 in Human Macrophages

BACKGROUND:Monocytes and macrophages are key innate immune effector cells that produce cytokines and chemokines upon activation. We and others have shown that 17beta-estradiol (E2) has a direct role in the modulation of monocyte and macrophage immune function. However, relatively little is known about the ability of E2 to regulate isoform expression of estrogen receptors (ERs) in these cells. METHODOLOGY/PRINCIPAL FINDINGS:In this study, we quantify expression of ERalpha and ERbeta in human monocytes and macrophages. We also show for the first time that the N-terminal truncated ERalpha variant, ERalpha46, is expressed in both cell types. Promoter utilization studies reveal that transcription of ERalpha in both cell types occurs from upstream promoters E and F. Treatment with E2 induces ERalpha expression in macrophages but has no effect on ERbeta levels in either cell type. During monocyte-to-macrophage differentiation, ERalpha is upregulated in a time-dependent manner. Previous studies by our group demonstrated that E2 treatment attenuates production of the chemokine CXCL8 in an ER-dependent manner. We now show that ERalpha expression levels parallel the ability of E2 to suppress CXCL8 production. CONCLUSIONS/SIGNIFICANCE:This work demonstrates for the first time that human macrophages predominantly express the truncated ER variant ERalphap46, which is estradiol-inducible. This is mediated through usage of the ERalpha F promoter. Alternative promoter usage may account for tissue and cell type-specific differences in estradiol-induced effects on gene expression. These studies signify the importance of ERalpha expression and regulation in the ability of E2 to modulate innate immune responses

Histone H3K9 methylation regulates chronic stress and IL‐6–induced colon epithelial permeability and visceral pain

BackgroundChronic stress is associated with activation of the HPA axis, elevation in pro‐inflammatory cytokines, decrease in intestinal epithelial cell tight junction (TJ) proteins, and enhanced visceral pain. It is unknown whether epigenetic regulatory pathways play a role in chronic stress–induced intestinal barrier dysfunction and visceral hyperalgesia.MethodsYoung adult male rats were subjected to water avoidance stress ± H3K9 methylation inhibitors or siRNAs. Visceral pain response was assessed. Differentiated Caco‐2/BBE cells and human colonoids were treated with cortisol or IL‐6 ± antagonists. Expression of TJ, IL‐6, and H3K9 methylation status at gene promoters was measured. Transepithelial electrical resistance and FITC‐dextran permeability were evaluated.Key ResultsChronic stress induced IL‐6 up‐regulation prior to a decrease in TJ proteins in the rat colon. The IL‐6 level inversely correlated with occludin expression. Treatment with IL‐6 decreased occludin and induced visceral hyperalgesia. Chronic stress and IL‐6 increased H3K9 methylation and decreased transcriptional GR binding to the occludin gene promoter, leading to down‐regulation of protein expression and increase in paracellular permeability. Intrarectal administration of a H3K9 methylation antagonist prevented chronic stress–induced visceral hyperalgesia in the rat. In a human colonoid model, cortisol decreased occludin expression, which was prevented by the GR antagonist RU486, and IL‐6 increased H3K9 methylation and decreased TJ protein levels, which were prevented by inhibitors of H3K9 methylation.Conclusions & InferencesOur findings support a novel role for methylation of the repressive histone H3K9 to regulate chronic stress, pro‐inflammatory cytokine–mediated reduction in colon TJ protein levels, and increase in paracellular permeability and visceral hyperalgesia.Chronic stress increases levels of pro‐inflammatory cytokines, decreases GR transcriptional binding at epithelia cell tight junction gene promoters reducing tight junction gene expression, culminating in increased paracellular permeability and enhanced visceral pain sensation. Methylation of the repressive histone H3K9me2/me3 plays a central role in this process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163588/2/nmo13941.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163588/1/nmo13941_am.pd