Tumor necrosis factor-α (TNF-α) is a critical pro-inflammatory
cytokine regulating
neuroinflammation. At high concentrations, it is toxic to neurons, and such damage is positively correlated with acute and chronic neurological diseases. Our previous studies showed that inhibition of
phosphodiesterase 4 (PDE4) attenuated the production of TNF-α induced by
lipopolysaccharides in microglial cells. However, whether PDE4 inhibition can block the neurotoxic effects of TNF-α in neuronal cells is unknown. In this study, we investigated the protective effects of
FCPR16, a novel
PDE4 inhibitor, against TNF-α-induced cellular apoptosis in HT-22 hippocampal neuronal cells. We demonstrated that
FCPR16 dose-dependently increased the viability of HT-22 cells exposed to TNF-α insult.
Propidium iodide/
calcein staining and flow cytometry analysis showed that
FCPR16 decreased cell apoptosis triggered by TNF-α. Western blot analysis showed that
FCPR16 decreased the level of cleaved
caspase 3 and
caspase 8, but had no effect on
caspase 9. Mechanistically,
FCPR16 blocked the TNF-α-induced phosphorylation of
c-Jun N-terminal kinase (JNK) in HT-22 cells, and inhibition of JNK showed a similar protective effect as
FCPR16. Furthermore,
FCPR16 decreased the translocation of nuclear factor-κB (NF-κB) p65 from the cytosol into the nucleus. In addition,
FCPR16 decreased the expression of
inducible nitric oxide synthase and the production of
reactive oxygen species in HT-22 cells exposed to TNF-α. Moreover, knockdown of PDE4B by specific
small interfering RNA reduced the apoptosis of HT-22 cells treated with TNF-α. Taken together, our findings suggest that
FCPR16 promotes the survival of neuronal cells exposed to TNF-α by suppressing the activation of JNK and NF-κB.