Immunomodulatory effects of QsCATH on macrophages: transcriptomic insights and molecular docking analysis.

The molecular mechanisms underlying the immunomodulatory effects of cathelicidins on macrophages remain poorly characterized. This study aimed to elucidate the immunomodulatory mechanisms of QsCATH, an antimicrobial peptide derived from the Chinese spiny frog (Quasipaa spinosa), in RAW264.7 macrophages using RNA sequencing and molecular docking. Transcriptomic analysis revealed that QsCATH significantly downregulated inflammatory-related genes (tnf, il6, ccl5, il1b) and suppressed pro-inflammatory cytokine production (tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β) by inhibiting key pathways such as NF-κB, TNF, and NOD-like receptor signaling. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analyses showed that QsCATH balanced inflammatory resolution with host defense by modulating biological processes including "immune system processes," "defense responses," and "oxidative stress responses." Using molecular docking simulations, potential interactions were predicted between QsCATH and membrane-associated proteins Nod2, Ripk2, and Itga3 (binding scores: - 239.00, - 213.24, and - 290.08, respectively), suggesting direct interference with receptor-mediated signaling cascades. This study presents the first transcriptome-level analysis of the immunoregulatory network of amphibian cathelicidins, providing insights for developing novel peptide-based therapeutics against drug-resistant infections and inflammatory disorders.