Mycoplasma genitalium lipoproteins inhibit tumour necrosis factor α-induced apoptosis in HeLa cells

Abstract

This aim of this study was to investigate the effects of Mycoplasma genitalium lipoproteins on the tumour necrosis factor α (TNF-α)-induced apoptosis in HeLa cells. We separated the M. genitalium lipid-associated membrane proteins (LAMPs) from M. genitalium and used them to treat HeLa cells. Apoptosis was induced by TNF-α treatment. Cell cycle and apoptosis were detected by flow cytometry. Pro-inflammatory cytokine contents were determined by enzyme-linked immunosorbent assay (ELISA). Mitochondrial membrane potential and caspase-3 protease activity were also measured. There was no significant difference in the viable cell percentage in HeLa cells treated with M. genitalium LAMPs at 0–20 μg/mL. However, when treated with 40 μg/mL LAMPs, cytocidal activity was observed during the first 24 h. M. genitalium LAMPs induced cell cycle arrest at the G1 phase in HeLa cells. When apoptosis was induced by TNF-α in HeLa cells, M. genitalium LAMPs significantly reduced the percentage of apoptotic cells. In addition, M. genitalium LAMPs significantly reduced the loss of mitochondrial membrane potential and caspase-3 protease activity in TNF-α-treated HeLa cells. However, the blocking of NF-κB significantly increased the mitochondrial membrane potential and caspase-3 protease activity in TNF-α-induced HeLa cells treated with M. genitalium LAMPs. The obtained results suggest that M. genitalium LAMPs could inhibit TNF-α-induced apoptosis in HeLa cells, which would contribute to the understanding of the pathogenesis of M. genitalium.

Keywords

• Mycoplasma genitalium lipoproteins
• LAMPs
• tumour necrosis factor α (TNF-α)
• apoptosis
• HeLa cells