Li_2026_Biology.(Basel)_15_

No. 0 diesel oil may pose a serious threat to sea cucumber (Apostichopus japonicus) aquaculture by inducing skin ulceration. This study aimed to evaluate the protective efficacy and mechanism of a previously developed inhibitor composition against diesel-induced injury. The inhibitor composition significantly alleviated skin ulceration in the experimental group (Eg), reducing the lesion area to 14.44 +/- 1.79% after 96 h, compared to 33.19 +/- 2.94% in the diesel-exposed control group (Cg) (p < 0.05). It effectively suppressed the overactivation of autolytic enzymes (cathepsin L and B) while enhancing the activities of acetylcholinesterase, superoxide dismutase, and catalase. Transcriptomic profiling revealed 3137 differentially expressed genes, with functional enrichment in pathways related to Notch signaling, ECM-receptor interaction, glycosaminoglycan biosynthesis, and detoxification. The upregulation of genes such as HES-C, CYP1A1, GST, and UGT may be linked to the regulation of apoptosis inhibition, xenobiotic metabolism, and antioxidant defense. Furthermore, enhanced expression of NAD kinase and PNLIPRP may indicate a potential strengthening of energy metabolism and lipid utilization during stress adaptation. This study suggests that the inhibitor composition may exert a multi-level protective effect against diesel-induced injury by coordinating tissue repair, oxidative balance, and detoxification processes, offering a potential strategy to mitigate pollution impacts in sea cucumber aquaculture.