Polydatin attenuated food allergy via store-operated calcium channels in mast cell.

AIM: To investigate the effect of polydatin (PD), a resveratrol glucoside, on mast cell degranulation and anti-allergic activity. METHODS: After the rats were orally sensitized with ovalbumin (OVA) for 48 d and underwent PD treatment for 4 d, all the rats were stimulated by 100 mg/mL OVA for 24 h and then sacrificed for the following experiments. The small intestines from all the groups were prepared for morphology examination by hematoxylin and eosin staining. We also used a smooth muscle organ bath to evaluate the motility of the small intestines. The OVA-specific immunoglobulin E (IgE) production and interleukin-4 (IL-4) levels in serum or supernatant of intestinal mucosa homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA). Using toluidine blue stain, the activation and degranulation of isolated rat peritoneal mast cells (RPMCs) were analyzed. Release of histamine from RPMCs was measured by ELISA, and regulation of PD on intracellular Ca(2+) mobilization was investigated by probing intracellular Ca(2+) with fluo-4 fluorescent dye, with the signal recorded and analyzed. RESULTS: We found that intragastric treatment with PD significantly reduced loss of mucosal barrier integrity in the small intestine. However, OVA-sensitization caused significant hyperactivity in the small intestine of allergic rats, which was attenuated by PD administration by 42% (1.26 ± 0.13 g vs OVA 2.18 ± 0.21 g, P < 0.01). PD therapy also inhibited IgE production (3.95 ± 0.53 ng/mL vs OVA 4.53 ± 0.52 ng/mL, P < 0.05) by suppressing the secretion of Th2-type cytokine, IL-4, by 34% (38.58 ± 4.41 pg/mL vs OVA 58.15 ± 6.24 pg/mL, P < 0.01). The ratio of degranulated mast cells, as indicated by vehicles (at least five) around the cells, dramatically increased in the OVA group by 5.5 fold (63.50% ± 15.51% vs phosphate-buffered saline 11.15% ± 8.26%, P < 0.001) and fell by 65% after PD treatment (21.95% ± 4.37% vs OVA 63.50% ± 15.51%, P < 0.001). PD mediated attenuation of mast cell degranulation was further confirmed by decreased histamine levels in both serum (5.98 ± 0.17 vs OVA 6.67 ± 0.12, P < 0.05) and intestinal mucosa homogenates (5.83 ± 0.91 vs OVA 7.35 ± 0.97, P < 0.05). Furthermore, we demonstrated that administration with PD significantly decreased mast cell degranulation due to reduced Ca(2+) influx through store-operated calcium channels (SOCs) (2.35 ± 0.39 vs OVA 3.51 ± 0.38, P < 0.01). CONCLUSION: Taken together, our data indicate that PD stabilizes mast cells by suppressing intracellular Ca(2+) mobilization, mainly through inhibiting Ca(2+) entry via SOCs, thus exerting a protective role against OVA-sensitized food allergy.

Herbal Formula-3 inhibits food allergy in rats by stabilizing mast cells through modulating calcium mobilization.

BACKGROUND: The prevalence of food allergy has increased dramatically during the last three decades, but currently there was no effective therapy except avoidance of allergen. This study aimed to investigate the effect of a modified Chinese herbal formula, Formula-3, on mast cell degranulation and the anti-allergic activity in both animal and cell models. METHODS: With OVA-sensitized food allergic model in Brown-Norway rats, we checked tissue injury in the small intestines by H&E staining. The Th2 cytokine levels and IgE production in serum or supernatant of the intestinal mucosa homogenates were analyzed by ELISA. Meanwhile, rat peritoneal mast cell activation and degranulation were examined by Toluidine Blue Stain and the release of histamine was measured. Furthermore, the regulation of Formula-3 on Ca(2+) mobilization was investigated by probing intracellular Ca(2+) with fluo-4 fluorescence. The direct effect of Formula-3 on mast cell stabilization was also studied in RBL-2H3 cell line. RESULTS: In vivo Formula-3 administration significantly reduced tissue damage in the small intestines of rat and suppressed Th2 cytokine secretion and IgE production. We demonstrated that Formula-3 treatment significantly suppressed FcεR1-mediated mast cell degranulation no matter in OVA-challenged allergic rats or IgE-sensitized RBL-2H3 cell line. Furthermore, Formula-3 significantly decreased Ca(2+) influx through store-operated calcium channels (SOCs) evoked by dinitrophenyl-BSA or thapsigargin in mast cells. CONCLUSION: Taken together, our data indicate that Formula-3 stabilizes mast cells by suppressing FcεR1-induced Ca(2+) mobilization mainly through inhibiting Ca(2+) entry via SOCs, thus exerting a protective effect against OVA-sensitized food allergy.