Parbendazole induces semaphorin 3A expression via JNK/c-Jun signaling pathway in normal human epidermal keratinocytes

Epidermal hyperinnervation is a partial cause of antihistamine-resistant itch. The nerve repulsion factor semaphorin 3 A (Sema3A) plays a key role in regulating intraepidermal nerve fiber density. In a preliminary study, we screened pre-existing drugs for potential Sema3A inducers and identified benzimidazole anthelmintics as Sema3A inducers in normal human epidermal keratinocytes (NHEKs).

This study aimed to investigate the mechanisms underlying Sema3A induction by benzimidazole anthelmintics, such as parbendazole, in NHEKs.

Parbendazole was added to NHEKs or a reconstructed human epidermis (RHE) model and incubated for 24 h at 37°C. Sema3A expression levels were analyzed by quantitative real-time PCR and enzyme-linked immunosorbent assay. Cell viability was assessed using a cell-counting kit-8 assay or methylthiazole tetrazolium assay. The molecular mechanisms of Sema3A induction by parbendazole were examined using signaling inhibitors and siRNAs. Phosphorylation of Jun-N-terminal kinase (JNK) and c-Jun was analyzed by western blotting.

Parbendazole dose-dependently increased Sema3A gene expression and extracellular secretion in NHEKs, with similar results observed in RHE models. Parbendazole also upregulated the expression of the nerve repulsion factor KAL-1 mRNA. Regarding nerve elongation factors, parbendazole decreased nerve growth factor levels, whereas amphiregulin and artemin remained unchanged. Parbendazole promoted JNK and c-Jun phosphorylation in NHEKs. JNK inhibitors suppressed parbendazole-mediated Sema3A induction. Additionally, siRNA targeting c-Jun and the AP-1 inhibitor T-5224 both suppressed parbendazole-induced Sema3A upregulation.

Parbendazole dose-dependently induced Sema3A expression via the JNK/c-Jun signaling axis. Benzimidazole anthelmintics may have potential for developing new antipruritic drugs.