Modulatory role of dietary Chlorella vulgaris powder against arsenic-induced immunotoxicity and oxidative stress in Nile tilapia (Oreochromis niloticus)

• Arsenic (As+3) induced immunotoxicity and oxidative stresses in Nile tilapia.
• Respiratory burst, lysozyme, and bactericidal activities were down-regulated.
• Antioxidant enzyme system was declined significantly after As+3 exposure.
• Phytoremediation with Chlorella (Ch) in feed alleviated the toxic effects of As+3.
• Ch feeding enhanced the innate immune response and antioxidant activity.

Arsenic intoxicant have long been regarded as an impending carcinogenic, genotoxic, and immunotoxic heavy metal to human and animals as well. In this respect, we evaluated biomarkers of the innate immune response and oxidative stress metabolism in gills and liver of Nile tilapia (Oreochromis niloticus) after arsenic exposure, and the protective role of Chlorella vulgaris (Ch) dietary supplementation were elucidated. Protective role of C. vulgaris (Ch), as supplementary feeds (5% and 10% of the diet) was studied in Nile tilapia (O. niloticus) against arsenic induced toxicity (NaAsO2 at 7 ppm) for 21 days exposure period. A significant down-regulation in innate immune response; including, respiratory burst, lysozyme, and bactericidal activity followed due to deliberately As+3 exposure. Similarly, oxidative stress response; like nitric oxide (NO), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx), malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels were significantly decreased. Combined treatment of Ch and As+3 significantly enhanced the innate immune response and antioxidant activity. Strikingly, Ch supplementation at 10% has been considered the optimum for Nile tilapia since it exhibited enhancement of innate immune response and antioxidant activity over the level 5%, and even better than that of control level. Thus, our results concluded that dietary Ch supplementation could protect Nile tilapia against arsenic induced immunosuppression and oxidative stresses.