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Les hydrolysats de requin stimulent le système immunitaire

06/05/2014 | Etudes Compléments alimentaires et Etudes Anti-âge

 

The immunopotentiating effects of shark-derived protein hydrolysate
Jean-François Mallet   Nutrition Volume 30, Issue 6, June 2014, Pages 706–712

Objective

Peptides derived from natural sources can act as immunomodulating agents and prevent infections. The aim of this study was to investigate the immunopotentiating and protective effects of a shark-derived protein hydrolysate (SPH) against an enterotoxigenic Escherichia coli H10407 infection in a murine model.

Methods

Mice were fed an aqueous solution of SPH for 7 days before being inoculated with an experimental enterotoxigenic Escherichia coli H10407 infection. After euthanasia, small intestines were removed for histological study and the number of IgA and IgG producing cells was determined by direct immunofluorescence. Cytokines were measured in the serum and the intestinal fluid.

Results

The oral administration of SPH enhanced the gut barrier function via up-regulation of immunoglobulin A-producing cells and intestinal cytokines production, including interleukin-6 and tumor necrosis factor-α. The increase of transforming growth factor-β and interleukin-10 contribute to the down-regulation of uncontrolled-inflammatory reaction induced by E. coli infection. From these results, the anti-inflammatory properties of SPH may be caused by regulation and priming mechanisms of the immune system.

Conclusion

Enzymatic protein degradation confers immunomodulating and protective potentials to shark proteins and the resulted peptides could be used as an alternative therapy to reduce the risk of bacterial infections and inflammatory-related diseases.

Shark protein improves bone mineral density in ovariectomized rats and inhibits osteoclast differentiation
Kazuki Uehara           Nutrition   Volume 30, Issue 6, June 2014, Pages 719–725

Objectives

Fish proteins are potential sources of natural medicines and food additives. There are many studies being performed to develop underutilized fish proteins. Therefore, the aim of this study was to determine how shark protein functions as a dietary supplement for bone health.

Methods

Three groups of ovariectomized (OVX) rats were fed different diets containing 20% casein protein, 20% shark protein, or 20% cod protein for 4 wk. Bone mineral density of the right femur was measured by dual-energy x-ray absorptiometry and quantitative computed tomography. Furthermore, we prepared low-molecular-weight peptides from shark protein using protease for in vitro studies. Calcitriol was added to bone marrow cells and the receptor activator of the nuclear factor-κB ligand was added to RAW264 cells. After 7 d, the number of tartrate-resistant acid phosphatase-positive cells was counted.

Results

In the shark protein-fed group, bone mineral density of the femur epiphysis was higher than that of the casein protein-fed group. In particular, the shark protein-fed group showed an increase in bone mineral density, represented mainly by trabecular bone. Shark protein hydrolysates inhibited osteoclast formation in bone marrow cells and RAW264 cells.

Conclusions

These results suggest that shark protein might suppress the bone loss caused by estrogen deficiency through the suppression of osteoclast formation.

 

 

 

 

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