Heparin inhibits interferon-γ signaling in human endometrial stromal cells by interference with the cellular binding of interferon-γ.

OBJECTIVE: To examine the impact of heparins on interferon-γ (IFN-γ) signaling in human endometrial stromal cells (ESCs) in vitro. DESIGN: In vitro experiment. SETTING: Research laboratory at a medical university center. PATIENT(S): Premenopausal women undergoing hysterectomy for benign reasons. INTERVENTION(S): The ESCs were isolated from hysterectomy specimens, decidualized in vitro using P and 17ß-E(2), and incubated with recombinant IFN-γ, unfractionated heparin, and low molecular weight heparins (LMWHs). MAIN OUTCOME MEASURE(S): Interferon response factor 1 (IRF-1) and N-myc interactor (Nmi) messenger RNA (mRNA) were measured using real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Phosphorylation of signal transducer and activator of transcription 1 (STAT-1) was detected by an in-cell Western assay, expression of the IFN-γ receptor by flow cytometry. Cell-bound IFN-γ was determined in lysates by an ELISA. RESULT(S): Heparin and LMWHs inhibit the IFN-γ-mediated induction of IRF-1, but not Nmi in undifferentiated and decidualized ESCs. The phosphorylation of signal transducer and activator of transcription 1 STAT-1 upon IFN-γ stimulation is inhibited as well. Heparin has no effect on the IFN-γ receptor in ESCs, but inhibits the binding of IFN-γ to the cells. CONCLUSION(S): Unfractionated heparin, as well as LMWHs, are able to inhibit IFN-γ signaling in human ESCs and therefore might be clinically interesting agents to modulate the actions of this proinflammatory cytokine at the implantation site.