A TRPV1 agonist from the transcriptome profiling of Dipsastraea rotumana inhibits neuroinflammation in vivo through the NF-κB and MAPK pathways

Neuroinflammation, defined as the inflammatory response in the brain or spinal cord, plays a pivotal role in multiple neurodegenerative conditions including Parkinson's and Alzheimer's diseases. Transient receptor potential cation channel subfamily V member 1 (TRPV1), widely expressed in microglia, influences their function by regulating the production of these immune-modulating molecules. To identify peptides with anti-neuroinflammatory properties targeting TRPV1, a set of seven Kunitz-type peptides named DrKuz1 to 7 was discovered in Dipsastraea rotumana. Through molecular docking and dynamic simulations, it was shown that DrKuz1 interacted with key residues crucial for TRPV1 activation. Functional assays confirmed that DrKuz1 induced calcium influx in HEK293 cells overexpressing hTRPV1. Furthermore, DrKuz1 demonstrated its anti-inflammatory properties by reducing the levels of nitric oxide (NO), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) activated by lipopolysaccharides (LPS) in mouse microglial cells (BV-2). Moreover, DrKuz1 restored the LPS-activated inflammatory gene expression and abnormal locomotory behavior in zebrafish larvae. This anti-inflammatory effect of DrKuz1 has been found to involve modulation of the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways in LPS-treated BV-2 cells. Therefore, DrKuz1 emerges as a promising tool for investigating TRPV1 function and as a potential therapeutic candidate for neuroinflammation.