The nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 1 (NLRP1) and NLRP3 inflammasomes are activated in temporal lobe epilepsy (TLE), leading to neuroinflammation, pyroptosis, and neuronal injury. Protein phosphatase 2 A (PP2A) and the toll-like receptor 4 (TLR4)–p38 MAPK signaling pathway participate in regulating these inflammasomes. Although blocking transient receptor potential vanilloid 4 (TRPV4) alleviates inflammation and neuronal damage after pilocarpine-induced status epilepticus (PISE), the underlying mechanisms remain unclear. Here, we found that NLRP1 and NLRP3 expression and activation were markedly increased in the hippocampus during the acute phase post-PISE, accompanied by enhanced pyroptosis and inflammatory responses. Both PP2A activity and TLR4–p38 MAPK signaling were upregulated. Pharmacological inhibition revealed that PP2A primarily drove NLRP3 activation, whereas TLR4–p38 MAPK signaling promoted NLRP1 activation, collectively contributing to pyroptosis and neuronal injury. TRPV4 blockade simultaneously suppressed PP2A activity and TLR4–p38 MAPK signaling, thereby inhibiting NLRP1/NLRP3 inflammasome activation and exerting neuroprotective effects. Conversely, TRPV4 activation with GSK1016790A promoted inflammasome activation, pyroptosis, and activation of PP2A and TLR4–p38 MAPK signaling; these effects were attenuated by inhibiting PP2A or TLR4–p38 MAPK. In HT-22 cells, TRPV4 activation activated the TLR4–p38 MAPK–NLRP1 axis, and NLRP1 knockdown alleviated pyroptosis. Finally, inhibition of TRPV4, PP2A, NLRP3, or NLRP1 markedly reduced seizure frequency and duration in PISE mice. Collectively, these findings suggest that TRPV4 blockade suppresses the PP2A–NLRP3 and TLR4–p38 MAPK–NLRP1 pathways, attenuating neuroinflammation and pyroptosis, and thereby reducing seizure activity during the acute phase following PISE.
Liu et al. (Sun,) studied this question.