Modulatory effect of different doses of β-1,3/1,6-glucan on the expression of antioxidant, inflammatory, stress and immune-related genes of Oreochromis niloticus challenged with Streptococcus iniae

• Published in: Fish & shellfish immunology 2017-11, Vol.70, p.204-213
• Main Authors: Salah, Abdallah S., El Nahas, Abeer F., Mahmoud, Shawky
• Format: Article
• Language: English
• Subjects: Adaptive immune-related genes; Adjuvants, Immunologic - administration & dosage; Adjuvants, Immunologic - pharmacology; Animal Feed - analysis; Animals; Antioxidant genes; Antioxidants - metabolism; beta-Glucans - administration & dosage; beta-Glucans - pharmacology; Cichlids; Diet - veterinary; Dietary Supplements - analysis; Dose-Response Relationship, Drug; Fish Diseases - immunology; Fish Diseases - microbiology; Gene expression; Immunity, Innate - drug effects; Inflammation - genetics; Inflammation-related; Oreochromis niloticus; Streptococcal Infections - immunology; Streptococcal Infections - microbiology; Streptococcal Infections - veterinary; Streptococcus iniae; Streptococcus iniae - physiology; Stress, Physiological - drug effects; β-Glucan
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2017.09.008

β-glucans are widely-known immunostimulants that are profusely used in aquaculture industry. The present study was conducted to evaluate the effect of different in-feed doses of β-1,3/1,6-glucans on the expression of antioxidant and stress-related genes (GST, HSP-70, Vtg), inflammation related genes (Il-8, TNFα, CXC-chemokine and CAS) and adaptive immune-related genes (MHC-IIβ, TLR-7, IgM-H, and Mx) of Oreochromis niloticus challenged and non-challenged with Streptococcus iniae. Six experimental groups were established: non-challenged control (non-supplemented diet), challenged control (non-supplemented diet), non-challenged supplemented with 0.1% β-glucan, challenged supplemented with 0.1% β-glucan, non-challenged supplemented with 0.2% β-glucan and challenged supplemented with 0.2% β-glucan. Fish were fed with β-glucan for 21 days prior challenge and then sampled after 1, 3 and 7 days post-challenge. In non-challenged group, variable effects of the two doses of β-Glucans on the expression of the studied genes were observed; 0.1% induced higher expression of HSP70, CXC chemokine, MHC-IIβ and MX genes. Meanwhile, 0.2% induced better effect on the expression of Vtg, TNF-α, CAS and IgM-H, and almost equal effects of both doses on GST and IL8. However, with the challenged group, 0.2% β-Glucans showed better effect than 0.1% at day one post challenge through significant up-regulation of GST, HSP, IL8, TNF-α, CXC, and MHC-IIβ, meanwhile, the effect of 0.1% was only on the expression of HSP70, MHC-IIβ, and TLR7 at day 3 post challenge. No stimulatory role for both doses of β-Glucans on the expression of almost all genes at day 7 post-challenge. We conclude that both doses of β-glucan can modulate the antioxidant, inflammation, stress and immune-related genes in Nile tilapia, moreover, 0.2% β-Glucans showed better protective effect with Streptococcus iniae challange. •β-glucans are widely-known immunostimulants in aquaculture industry.•Two doses of β-Glucans (0.1 and 0.2%) induced variable effect on gene expression of the immune, antioxidant and stress response-related genes.•0.2% β-Glucans showed better effect than 0.1% in the challenged fish with Streptococcus iniae.•No stimulatory role of both doses of β-Glucans on the expression of many genes at day 7 post-challenge.•Both doses of β-glucan can modulate the immune, antioxidant and stress response of Nile tilapia.