Interleukin-33 enhances ASIC currents in mouse dorsal root ganglion neurons.

Cytokine interleukin-33 (IL-33) signaling in primary sensory neurons plays a crucial role in pain. However, the underlying molecular mechanisms remain poorly understood. Therefore, we investigated whether IL-33 signaling affects ion channels in nociceptive dorsal root ganglion (DRG) neurons. Herein, we reported that the application of IL-33 enhanced the electrophysiological activity of acid-sensing ion channels (ASICs). IL-33 dose-dependently increased acid-evoked ASIC currents in mouse DRG neurons. IL-33 enhanced the maximum responses of ASICs, whereas the sensitivity to acidic stimuli remained unaffected. This IL-33-induced enhancement of ASIC currents was dependent on suppression of the tumorigenicity 2 (ST2) receptors. The enhancing effect of IL-33 on ASIC currents was prevented by the p38 mitogen-activated protein kinase inhibitor SB202190, but not by the ERK inhibitor U0126 or the JNK inhibitor SP600125, indicating the effect was p38-dependent. Moreover, IL-33 potentiated the action potentials triggered by acidic stimuli. Finally, ASIC3-deficient mice displayed attenuated mechanical hyperalgesia induced by intraplantar or intramuscular injection of IL-33. Our findings revealed that IL-33 enhanced ASIC function via ST2 and the intracellular p38 signaling pathway, which might provide a promising therapeutic approach for pain treatment by targeting IL-33/ST2 signaling.