Immune-antioxidant potential, splenic cytokines regulation, and tissue architecture restoration by grape seed oil nanoemulsion in Nile tilapia subjected to acrylamide toxicity.

This study represents a pioneering investigation into the protective role of dietary grape seed oil nanoemulsion (GON) against acrylamide (AC)-induced growth impairment, oxidative stress, immunosuppression, gene expression dysregulation, and histopathological damage in Nile tilapia (Oreochromis niloticus). A total of 240 fish were randomly allocated into six experimental groups (four replicates each). The control, GON20, and GON40 groups received basal, 20 and 40 mg/kg GON-supplemented diets, respectively, without AC exposure. The AC, AC + GON20, and AC + GON40 groups were exposed to waterborne AC at 1/8 of the 96-h median lethal concentration (4.33 mg/L) for 45 days while receiving the corresponding diets. Growth performance, immune and oxidative stress biomarkers were assessed, alongside splenic cytokine expression and histopathological alterations. AC exposure significantly reduced growth parameters (p < 0.0001), including weight gain and specific growth rate, and induced pronounced immunosuppression and oxidative stress, evidenced by decreased lysozyme activity, complement 3, total protein, catalase, superoxide dismutase, and glutathione peroxidase activities, concomitant with elevated malondialdehyde levels. Severe inflammatory and necrotic lesions were observed in intestinal and splenic tissues. Furthermore, AC significantly downregulated (p < 0.0001), the expression of interleukin-6, interleukin-8, cathepsin-B, and nuclear factor erythroid 2-related factor 2, increasing cellular susceptibility to toxic and oxidative insults. Conversely, GON supplementation significantly improved growth performance, immune competence, and antioxidant capacity in a dose-dependent manner, accompanied by marked upregulation (p < 0.0001), of IL-6, IL-8, cathepsin-B, and NRF2 expression. These molecular modulations were associated with substantial histological recovery of intestinal and splenic architecture, with near-complete restoration observed in the AC + GON40 group. Collectively, these findings highlight GON as a promising multifunctional dietary additive capable of mitigating acrylamide-induced toxicity and enhancing physiological resilience in Nile tilapia as a valuable fish in aquaculture practice.