Unveiling Antioxidant Mechanisms: Novel Gene Expression Profiling Reveals How Carboxylated Cellulose Nanocrystal/ZnO Bio-nanohybrid Counteracts Babesiosoma-Induced Oxidative Stress in Catfish

Abstract Parasitic infections, particularly by Babesiosoma spp., severely impact aquaculture productivity, leading to compromised fish health and significant economic burdens. This research presents the fabrication and comprehensive evaluation of an innovative carboxylated cellulose nanocrystals/zinc oxide (CCNs/ZnO) bio-nanohybrid, derived sustainably from date palm fronds, as a therapeutic agent against Babesiosoma infection in African catfish ( Clarias gariepinus ). Advanced characterization techniques confirmed the successful formation and distribution of the ZnO nanoparticles within the CCN matrix. To gain unprecedented molecular insights into host-parasite interactions and treatment efficacy, we designed a robust in vivo experimental model comprising four distinct groups: Group A (Negative Control) of non-infected fish fed a basal diet; Group B (Infected Control) of Babesiosoma spp.-infected fish fed a basal diet; Group C (Low Concentration Treatment) of infected fish supplemented with 50 mg CCNs/ZnO per kg of diet; and Group D (High Concentration Treatment) of infected fish supplemented with a potent 70 mg CCNs/ZnO per kg of diet. We then conducted comprehensive gene expression profiling using novel, meticulously designed primers targeting a broad spectrum of immune, erythropoiesis, oxidative stress, apoptosis, and metabolic genes. Our study revealed that Babesiosoma infection induced a cascade of detrimental effects in the Infected Control group, including stunted growth, dysregulated immune responses (elevated pro-inflammatory cytokines, reduced TGF-β1), severe anemia marked by suppressed erythropoiesis-related genes, increased oxidative stress (hsp70 upregulation, antioxidant gene downregulation), heightened apoptosis, and significant multi-organ pathology. Strikingly, dietary administration of the CCNs/ZnO bio-nanohybrid dose-dependently reversed these debilitating effects, with the High Concentration Treatment (Group D) demonstrating the most potent and comprehensive therapeutic benefits. Supplemented fish, particularly those receiving the high dose, exhibited restored growth, balanced immune gene expression, enhanced red blood cell production, improved antioxidant capacity, reduced cellular apoptosis, normalized metabolism, and remarkable histopathological recovery. Our findings provide compelling evidence for the multifaceted benefits of this eco-friendly bio-nanohybrid in fortifying fish health against parasitic challenges, promising a sustainable advancement in aquaculture disease management. Graphical Abstract