mune responses. Algimun bioactive molecules proved resist- ant to aquaculture feed processing in general, and in particular to extrusion.
Immunomodulating and properties A research project in collaboration with INRA (France) led to the demonstration of the effect of MSP®Immunity on im- mune mediator transcription in a IPEC-1 model (epithelial cell line). This included identifying the metabolic pathways involved. Green algal extract could positively influence the gene transcription of a wide range of immune mediators in- volved in defense mechanisms within innate and the adap- tive immune responses, including the recruitment and acti- vation of antigen-presenting cells, the differentiation and proliferation of lymphocyte populations, while inducing im- mune tolerance thanks to its anti-inflammatory properties. In-vivo scientific studies further confirmed the immuno- modulating properties of MSP®Immunity, namely by im- proving the phagocytic activity of macrophages and neu- trophils in rainbow trout and also by regulating the gene expression of immune mediators with anti-inflammatory activities in carp macrophages. Olmix Group conducted a set of experiments in collabora- tion with Intestinal Biotech Development in order to assess the effect of the MSP®Barrier on the intestinal barrier func- tion using epithelial cell lines. Results showed that this red algal extract upregulates the gene expression of transmem- brane and scaffolding proteins, which are essential for opti- mal functioning of tight junction complexes. Besides that, the red algal extract upregulates the expression of mucin- targeted genes that play a crucial role in establishing the mucus layer and the preventing pathogen colonisation. Red algal extract also plays an important role in maintaining gut mucosa integrity by making the tight junctions stronger and the mucus layer more functional. These findings were corroborated in an in-vivo scientific study. MSP®Barrier reduced the paracellular passage of FITC-dex- tran (gut permeability marker) to the blood in an animal stress model known to cause inflammation of the gut mu- cosa, leading to a higher degree of gut permeability. MSP®Barrier supplementation to stressed animals signifi- cantly reinforced the barrier function of the gut mucosa which is currently at the front line of the innate immune defense.
The effect of macroalgal extracts
Scientific and commercial trials have shown that Algimun in- clusion in feed ensures regular growth performance while modulating the immune response and reinforcing the gut barrier function, resulting in enhanced resistance to patho- genic challenges in several species such as red tilapia, rainbow trout, olive flounder and shrimp. Red tilapia fed with 0.3% of Algimun had a higher survival
50 50c
Red algal extract enhances the gut barrier function, while green algal extract modulates innate and adaptive im- mune responses.
rate (+25%, p<0.05, Figure 2) 14 days after a Streptococcus agalactiae challenge due to a better immune response demonstrated by a significant increase in the blood respirato- ry burst when compared to the control challenge group (p<0.05) and by significantly higher counts of intestinal gob- let cells when compared to the control group (p<0.05). In a rainbow trout commercial farm (Brazil, 2019), the inclu- sion of 0.3% of Algimun in the feed led to a significantly im- proved skin-mucus immune response when compared to the control group. The skin mucus complement system activity (hemolysis activity) in trout fed Algimun at week 4 and week 11 was improved by 13% (p<0.05) and 28% (p<0.10), respectively. What’s more, the hemolytic activity was higher at week 11 compared to week 4 (p<0.001). These results indicate that the product reinforces the skin-mucus innate immune response over time, both in short and long=term use, while maintain- ing regular performance. These trials confirm that the product can be used as a natural marine in-feed strategy to improve the natural defenses and thus improve the resistance of animals to several stressors in aquaculture production systems.
Figure 2 - Survival rate of red tilapia 14 days after Streptococcus agalactiae challenge. 100c
100
Control – (unchallenged) Control + (challenged) ALGIMUN® 0.3%
75c
0 ▶ ALL ABOUT FEED | Volume 28, No. 6, 2020 17
PHOTO: OLMIX
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