Polysaccharide suitable to modulate immune response
Objective of the present invention is to provide polysaccharides which modulate immune response, and which can be used as ingredients in edible products or pharmaceutical compositions. The present invention provides such polysaccharides obtained from the species Camellia sinensis , which comprise a rhamnogalacturonan-I core, and wherein the molar ratio of galacturonyl acid residues to rhamnosyl residues in the backbone of the polysaccharide is close to 1:1. The present invention also provides edible products or pharmaceutical compositions containing such polysaccharides, in order to modulate immune response.
1. A method of stimulating immune response in a mammal, comprising administering to a mammal in need of stimulation of its immune responsiveness a composition, wherein:
(a) the composition comprises 0.5 to 25 wt. % of the polysaccharide;
(b) the polysaccharide has a molecular weight of at least 110 kDa;
(c) 20-90 mol. % of the rhamnosyl residues in the backbone of the polysaccharide are substituted at the 4-OH position;
(d) the backbone of the polysaccharide comprises one or more side chains comprising alpha(1,5)-linked arabinosyl residues, said side chains being substituted at the 4-OH position of the rhamnosyl residue, and the molar ratio of arabinosyl residues to rhamnosyl residues being between 50:1 and 1:2;
(e) the backbone of the polysaccharide comprises one or more side chains comprising beta(1,4)-linked galactosyl residues, said side chains being substituted at the 4-OH position of the rhamnosyl residue, and the molar ratio of galactosyl residues to rhamnosyl residues being between 50:1 and 1:1;
(f) the backbone comprising alternating rhamnogalacturonan-I cores and alpha(1,4)-linked polygalacturonic acid or alpha(1,4)-linked oligogalacturonic acid cores, wherein the molar ratio of galacturonyl acid residues to rhamnosyl residues in the backbone of the polysaccharide ranges from 2.5:1 to 1:1;
(g) less than 2 mol. % of galactosyl residues present in the side chains are beta(1,3)-linked or beta(1,6)-linked galactosyl residues; and
(h) the polysaccharide is administered at a daily dose of at least 10 mg.
2. The method according to claim 1 , for treating common cold.
3. The method according to claim 1 , wherein the polysaccharide is administered as an adjuvant for a vaccine.
4. The method according to claim 1 , wherein the polysaccharide has a molecular weight between 110 and 2,000 kDa.
5. The method according to claim 1 , wherein the rhamnogalacturonan-I core comprises:
(a) one or more side chains comprising a backbone of at least one or more alpha(1,5)-linked arabinosyl residues and wherein the one or more side chains are substituted at the 4-OH position of the rhamnosyl residues, wherein the polysaccharide has a molar ratio of arabinosyl residues to rhamnosyl residues between 50:1 and 1:2, and
(b) the one or more side chains comprising a backbone of at least one or more beta(1,4)-linked galactosyl residues and wherein the one or more side chains are substituted at the 4-OH position of the rhamnosyl residues, wherein the polysaccharide has a molar ratio of galactosyl residues to rhamnosyl residues between 50:1 and 1:1.
6. The method according to claim 1 , wherein the composition comprises 3 to 25 wt. % of the polysaccharide.