Rapamycin sensitive ROS formation and Na(+)/H(+) exchanger activity in dendritic cells

Area of Science:

• Immunology
• Cell Biology
• Pharmacology

Background:

• Dendritic cells (DCs) are crucial antigen-presenting cells for initiating immune responses.
• The Na+/H+ exchanger (NHE) regulates DC function, responding to stimuli like lipopolysaccharide (LPS).
• Rapamycin is an immunosuppressive drug known to affect DC function.

Purpose of the Study:

• To investigate the impact of rapamycin on Na+/H+ exchanger (NHE) activity and reactive oxygen species (ROS) production in dendritic cells (DCs).
• To elucidate the role of ROS in LPS-induced DC responses, including NHE activity, cell swelling, and TNF-α release.

Main Methods:

• Mouse DCs were treated with LPS and rapamycin.
• Measurements included ROS production (DCFDA fluorescence), cytosolic pH (BCECF fluorescence), NHE activity (ammonium pulse assay), cell volume (FACS), and TNF-α release (ELISA).
• Inhibitors like Vas-2870 and antioxidants like Tempol were used to probe mechanisms.

Main Results:

• Rapamycin alone reduced ROS formation in DCs.
• LPS-induced NHE activity, cell swelling, and TNF-α release were significantly blunted by rapamycin.
• NADPH oxidase inhibition and ROS scavenging mimicked rapamycin's effects on LPS-induced responses.

Conclusions:

• Rapamycin disrupts LPS-induced ROS formation in DCs.
• This ROS disruption leads to the inhibition of NHE activity, cell swelling, and TNF-α release.
• ROS signaling is critical for LPS-mediated DC activation pathways targeted by rapamycin.