More than just inflammation: Ureaplasma species induce apoptosis in human brain microvascular endothelial cells

Area of Science:

• Microbiology
• Immunology
• Cell Biology

Background:

• Ureaplasma species are often considered commensals but can cause invasive infections, particularly in neonates.
• The mechanisms by which Ureaplasma species interact with host defense systems are not well understood.
• This study investigates Ureaplasma-induced cell death, focusing on apoptosis and inflammatory cell death pathways.

Purpose of the Study:

• To investigate the effects of Ureaplasma species on programmed cell death in human brain microvascular endothelial cells (HBMEC).
• To elucidate the roles of apoptosis and inflammatory cell death in Ureaplasma-mediated pathogenesis.
• To understand how Ureaplasma interactions might compromise the blood-brain barrier.

Main Methods:

• HBMEC were exposed to Ureaplasma urealyticum serovar 8 (Uu8) and Ureaplasma parvum serovar 3 (Up3).
• Cell death, mRNA levels of key programmed cell death genes, and enzyme activity were assessed using flow cytometry, RNA sequencing, and qRT-PCR.
• Real-time monitoring of cell adhesion was performed using xCELLigence technology.

Main Results:

• Both Ureaplasma isolates significantly induced cell death in HBMEC.
• Ureaplasma spp. upregulated mRNA expression for key apoptosis-related genes, including caspases 3, 7, and 9.
• Conversely, Ureaplasma isolates downregulated mRNA levels for proteins involved in inflammatory cell death, such as caspase 1, caspase 4, NLRP3, and RIPK3.

Conclusions:

• Ureaplasma species induce apoptosis in HBMEC, a critical component of the blood-brain barrier, potentially leading to barrier dysfunction.
• The concurrent suppression of inflammatory cell death pathways by Ureaplasma may impair host defense mechanisms.
• These mechanisms could facilitate invasive and persistent central nervous system infections by Ureaplasma species.