AUTHOR=Ibrahim Doaa , Pet Ioan , Anter Reham G. A. , Abdelwarith Abdelwahab A. , Rahman Mona Mohammed I. Abdel , Shafik Basant M. , Younis Elsayed M. , Basiony Asmaa , Atwa Shimaa A. E. , Metwally Aya Sh. , Tolba Heba A. , Ahmadi Mirela , Kishawy Asmaa T. Y. 

TITLE=Marine Smenospongia extract mitigated co-infection with Trichodina sp. and Flavobacterium columnare in Nile tilapia: insights into promoting growth performance, immune, antioxidant and autophagy defenses, and suppression of endoplasmic reticulum stress-related genes

JOURNAL=Frontiers in Marine Science

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1475150

DOI=10.3389/fmars.2024.1475150

ISSN=2296-7745

ABSTRACT=<p>Identifying novel natural sources from the marine environment with unique immunomodulatory and antioxidant efficacies is of interest in intensive fish farming. In this sense, marine sponge extract derived from <italic>Smenospongia</italic> (SS-extract) was tested for its potential anti-inflammatory, antioxidant and antimicrobial activities during the concurrent infection with <italic>Trichodina</italic> sp. and <italic>Flavobacterium columnare</italic> in Nile tilapia. A total of 625 Nile tilapia fingerlings were distributed into five groups: the control group (with no additives) and four groups fed the control diet fortified with SS-extract at 50, 100, 150, and 200 mg/kg, respectively, for 60 days. The parasitic challenge with <italic>Trichodina sp</italic> was done at the endpoint of the feeding trial and at 7 days post-infection (dpi); the fish were coinfected with <italic>F. columnare</italic>. A significant improvement in growth-related parameters of Nile tilapia was detected in the groups that received SS-extract at the levels of 150 and 200 mg/kg. The scavenging ability for free radicals (2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH)) was maximized with higher SS-extract supplementation levels. Simultaneously, the antioxidant defense of the Nile tilapia fed 150 and 200 mg/kg was augmented with a decline in oxidation-associated indicators [reactive oxygen species (ROS), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), and malondialdehyde (MDA)]. The higher concentrations of SS-extract in the feed potentiated the immune response of Nile tilapia before infection and even after coinfection and was paralleled by a subsiding in the exaggerated inflammatory response after concurrent infection. Concurrently, the mRNA expression of autophagy-encountered genes (<italic>Atg5</italic> and 12, <italic>LC3-II</italic> and <italic>BCLN1</italic>) had its highest expression in the fish fed the 200 mg/kg diet with the lowest expression of the mTOR gene in the same fish. The lowest infection intensity and rate and mucus score were displayed in fish fed 200 mg/kg SS-extract at 20 dpi. Interestingly, higher levels of SS-extract triggered antimicrobial peptides (upregulation of Hepcidin and β-defensin-1). In contrast, excessive expression of endoplasmic reticulum genes (<italic>atf4</italic>, <italic>JAK1</italic>, <italic>PERK</italic>, and <italic>eif2α</italic>) in the control infected group was downregulated by 200 mg/kg of SS-extract. The quantification of <italic>F. columnare</italic> indicated that columnaris coinfection severity displayed its lowest rate in the group supplemented with 200 mg/kg of SS-extract. In conclusion, a strategic siting based on fortification of the diet of Nile tilapia with SS-extract was elucidated to reinforce its immune and antioxidant defenses during a concurrent infection.</p>