Insight into the anti-allergic impacts of fucoidan from Gracilaria lemaneiformis in mitigating allergic reactions induced by shrimp tropomyosin via regulating Th1/Th2 cytokines and T cell subsets.

Fucoidan is a natural sulfated polysaccharide with immunoregulatory function. In this work, the anti-allergic impacts of Gracilaria lemaneiformis fucoidan (GLF) in mitigating allergic reactions induced by shrimp tropomyosin were investigated. As the results, GLF performed significant hyaluronidase inhibition ability (IC50 = 0.272 mg/mL), alleviated the allergic reactions of RAW 264.7 macrophage cells via decreasing the secretion of TNF-α and NO by 58.75 % and 46.17 %, respectively, and mitigated the degranulation degree and secretion of IL-4, TNF-α and histamine as well as promoted IL-10 secretion in RBL-2H3 mast cells. In BALB/c mouse, after gavage of GLF, the mouse allergic symptoms got significantly alleviated, the secretion of IgE and IgG1 got reduced, IgG2a got promoted, the IL-4 secretion from mouse spleen lymphocytes (SLP) significantly declined, and IL-10 and IFN-γ secretion in SLP got improved, which indicated GLF performed significantly anti-allergic functions via transforming Th2 response into Th1 and Treg response. Moreover, the SLP cells treated by GLF had lower expression of GATA-3, higher T-bet and Foxp3 expression, which indicated GLF could mitigate allergic reactions via regulating T-bet, GATA3 and Foxp3 transcription factor expression of T cell subsets. Therefore, GLF could serve as anti-allergic substances for shrimp-induced allergy via regulating Th1/Th2 cytokines and T cell subsets.