Anti-allergic effect of strawberry extract

Immunomodulatory effect of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in allergic conditions in vitro and in vivo

We found that strawberry extract suppressed immunoglobulin (Ig) E production in vitro and in vivo, and identified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as one of the IgE suppressor in the extract. We report here the effect of GAPDH on various Ig productions in vitro and in vivo. GAPDH suppressed IgE and enhanced IgA, IgG and IgM productions in ovalbumin (OVA)-stimulated human peripheral blood mononuclear cells. Oral administration of GAPDH at 10 mg/kg/day to OVA-induced allergy model mice tended to decrease total IgE level and increase total IgA and IgG levels in sera, and also decreased OVA-specific IgE and IgG levels. It is known that the increase of total IgA as well as the decrease of total and specific IgE is important for alleviating allergic symptoms. In addition, GAPDH accelerated IgA production and increased some cytokine secretions such as IL-4, TGF-β1 and IFN-γ in the OVA-immunized mice spleen lymphocytes. These cytokines involved in the class-switching, IgA enhancement, and IgE suppression, respectively, supporting above results. Our study suggests a possibility that oral administration of GAPDH may induce the immunomodulation in allergic responses.

Inhibitory Effects of Green Asparagus Extract, Especially Phospholipids, on Allergic Responses in Vitro and in Vivo

Asparagus (Asparagus officinalis L.) is one of the widely consumed vegetables. To investigate the mechanism underlying the anti-allergic responses of asparagus, we extracted different fractions from asparagus and measured their inhibitory effects on β-hexosaminidase release in RBL-2H3 cells in vitro and an atopic dermatitis NC/Nga mouse model in vivo. The lipid fractions from asparagus were extracted with 50% ethanol, separated using chloroform by liquid-liquid phase separation, and fractionated by solid-phase extraction. Among them, acetone fraction (rich in glycolipid) and MeOH fraction (rich in phospholipid) markedly inhibited β-hexosaminidase release from RBL-2H3 cells. In NC/Nga mice treated with picryl chloride, atopic dermatitis was alleviated following exposure to the 50% EtOH extract, acetone fraction, and methanol fraction. The inhibitory effects of asparagus fractions in vivo were supported by the significant decrease in serum immunoglobulin E (IgE) levels. The phospholipid fractions showed significantly better inhibitory effects, and phosphatidic acid from this fraction showed the best inhibitory effect on β-hexosaminidase release. In mice challenged with ovalbumin (OVA), oral administration of asparagus extract and its fractions decreased the OVA-specific IgE level and total IgE, indicating that these effects may be partly mediated through the downregulation of antigen-specific IgE production. Taken together, the present study shows for the first time that asparagus extract and its lipid fractions could potentially mitigate allergic reactions by decreasing degranulation in granulocytes. Our study provides useful information to develop nutraceuticals and functional foods fortified with asparagus.

Alkali-soluble pectin suppresses IgE production in human myeloma cell line in vitro

We found that strawberry (Fragaria x ananassa) extract has an IgE production suppressive activity and its oral administration improved skin manifestation in atopic dermatitis model mice. In present study, we identified an active substance using the IgE-producing human myeloma cell line U266. Gel filtration experiment indicated that the IgE suppressor was more than 6 kDa in molecular size. In addition, its pectinase treatment inhibited the activity, suggesting that the active substance in strawberry extract is pectin. Among solutions of water-(WP), hexametaphosphate-(HXP), acid-(HP) and alkali soluble pectin (OHP) extracted from strawberry, only OHP suppressed IgE production, and their suppressive activity was cancelled by pectinase treatment. In addition, OHP extracted from apple also inhibited IgE production. Furthermore, OHP also suppressed IgE production and did not affect IgG and IgM production in human peripheral blood mononuclear cells in an in vitro immunization condition. From these results, we concluded that OHP was an IgE suppressor in strawberry extract.