Peroxisome proliferator-activated receptor-γ ligand reduced tumor necrosis factor-α-induced interleukin-8 production and growth in endometriotic stromal cells

Objective

To evaluate the influence of peroxisome proliferator-activated receptor-γ (PPARγ) ligand (pioglitazone) on tumor necrosis factor-α (TNF-α)-induced interleukin-8 (IL-8) expression in endometriotic stromal cells (ESCs) and on proliferation of ESCs.

Design

Prospective study.

Setting

Department of Obstetrics and Gynecology, Tottori University Hospital, Yonago, Japan.

Patient(s)

Twenty-seven patients who underwent laparoscopic surgery.

Intervention(s)

The ESCs were obtained from the chocolate cyst linings of ovaries.

Main Outcome Measure(s)

The expression of PPARγ gene and protein was determined by reverse transcriptase–polymerase chain reaction (RT-PCR) and immunocytochemistry. We determined the effect of pioglitazone on the production of TNF-α-induced IL-8 protein in culture supernatant of ESCs using ELISA. The effect of pioglitazone on TNF-α-induced proliferation of ESCs was evaluated by 5-bromo-2′-deoxyuridine proliferation assay. The activation of nuclear factor (NF)-κB in ESCs was evaluated by Western blot analyses and NF-κB transcription factor assays.

Result(s)

Immunocytochemistry and RT-PCR revealed the expression of PPARγ gene and protein in ESCs. The PPARγ protein was predominantly located in the cell nucleus. Measurement of IL-8 protein by ELISA showed that adding TNF-α (100 pg/mL) significantly increased IL-8 protein. Treating ESCs with 0.1–10 μM of pioglitazone significantly reduced the TNF-α-induced IL-8 production. The presence of 0.1–10 μM of pioglitazone significantly suppressed growth of ESCs. The TNF-α increased the expression of phosphorylation of inhibitor κB (IκB). Adding pioglitazone (10 μM) did not influence the expression of phosphorylated inhibitor κB (IκB). The TNF-α markedly increased the intranuclear concentration of p65, and adding pioglitazone (10 μM) significantly reduced the concentration of p65.

Conclusion(s)

The present study demonstrates for the first time that PPARγ is expressed in ESCs, and that pioglitazone reduced IL-8 secretion and the proliferation of ESCs. The PPARγ ligand may be an attractive therapeutic agent for endometriosis.

Key Words: Endometriosis, PPARγ, pioglitazone, TNF-α, IL-8, ESCs