LSC Abstract – The estrogen-induced miR-19 downregulates secretory leukoprotease inhibitor expression in monocytes

Abstract

Introduction: The levels of circulating 17β-estradiol (E2) have been viewed as an influencing factor on the progression of many lung diseases. We hypothesize that E2 modulates the inflammatory response of circulating innate immune cells through miRNA (miR) based modulation of Secretory Leucoprotease Inhibitor (SLPI), a multifunctional antiprotease with known immunomodulatory effects. Methods: THP-1, U937 and male peripheral blood monocytes were treated with 10 nM E2 or control for various times up to 48 hours. Differentially expressed miRs in monocytes were identified using PCR profiling. Cells were transfected with miR mimics or antimiRs for 48 hours. SLPI mRNA and protein levels were quantified by qPCR and ELISA, respectively. Luciferase activity assay was carried out using SLPI 39UTR reporter constructs. ChIP was carried out on monocytes treated with E2. Results: SLPI expression is downregulated, and miR-19 is upregulated in response to E2 in monocytes, via increased MIR17HG promoter activity mediated by cMYC. Transfection of U937s with premiR-19b reduced SLPI expression at both mRNA and protein levels. This was abrogated using antimiRs against miR-19b. miR-19b directly binds the SLPI 39UTR, as determined by luciferase activity assay. Conclusions: The data show that E2 decreases expression of SLPI in monocytic cells, via changes in miR expression and further highlights the potential for estrogen to modulate key components of the innate immune system. Modulation of these miRs may offer a new therapeutic approach in the treatment of inflammatory lung diseases. This work was funded by the HRB under Grant No PHD/2007/11 and we acknowledge the support of the ERS, Fellowship STRTF 2015