TRPM2 exacerbates airway inflammation by regulating oxidized-CaMKⅡ in allergic asthma.

Background: Airway epithelial cells play important roles in allergic asthma. Transient receptor potential melastatin-related 2 (TRPM2) and oxidized Ca/calmodulin-dependent protein kinase Ⅱ (ox-CaMKⅡ) participate in the airway inflammation. This study aimed to analyze the effects of TRPM2 on ox-CaMKⅡ in the airway epithelial cells during allergic asthma.

Methods: BEAS-2B cells were treated with different dose of IL-13 (0, 5, 10, 20 ng/mL) for 24 h to analyze the changes of TRPM2 and ox-CaMKⅡ protein. Cells expressing different level of TRPM2 were obtained by transfection of TRPM2 siRNA or TRPM2-short cDNA. The transfected cells were treated with 10 ng/mL of IL-13 to analyze the effects of TRPM2 on the ox-CaMKⅡ. A CaMKⅡ inhibitor KN-93 was used to confirm the effects of TRPM2 on levels of ox-CaMKⅡ, -MEK and -ERK in the IL-13-treated BEAS-2B cells. Wild-type (WT) mice and TRPM2-knockout (TRPM2) mice were induced by ovalbumin (OVA) to compare the differences of inflammation, levels of ox-CaMKII, -MEK and -ERK in airways.

Results: Cell viability was clearly decreased by the 20 ng/mL of IL-13. The levels of TRPM2 and ox-CaMKII protein in cells were increased with increasing doses of IL-13. Transfection of TRPM2 siRNA or TRPM2-short cDNA respectively decreased or increased the levels of ox-CaMKⅡ in the IL-13-stimulated cells. The results of KN-93 treatment were similar to the results of TRPM2 siRNA transfection, that the levels of ox-CaMKⅡ, -MEK and -ERK were significantly decreased in the IL-13-treated cells. Compared with the OVA-induced WT mice, levels of inflammation, ox-CaMKⅡ, -MEK and -ERK in the airways were significantly weakened in the OVA-induced TRPM2 mice.

Conclusions: TRPM2 plays a vital role in regulating ox-CaMKⅡ in airway epithelial cells during allergic asthma.