Sea Buckthorn Flavonoid Extracted with High Hydrostatic Pressure Alleviated Shrimp Allergy in Mice through the Microbiota and Metabolism

Sea buckthorn (<i>Hippophaë rhamnoides</i> L.) known as the deciduous shrub has been reported to have effects of antioxidant, anti-inflammatory, and immunomodulatory activities. Tropomyosin (TM) induced a regulatory immune response associated with food allergy. In this study, a mouse model of food allergy sensitized to tropomyosin (TM) was established to assess the antiallergic properties of sea buckthorn flavonoid extract (SBF). SBF alleviated mice's allergic symptoms and exhibited a significant reduction in the levels of IgE and histamine. Meanwhile, SBF repaired the allergic Th2 cell overpolarization generated by TM, via downregulating the IL-4 production and upregulating IFN-γ production to restore the balance of Th1/Th2 cells. Furthermore, the 16S RNA analysis showed that SBF primarily restored the gut microbiota via increasing the abundance in <i>Chitinophilidae</i> and decreasing in <i>Burkholderiaceae, Pneumatobacteriaceae</i>, and <i>Sphingomonadaceae</i>. Gut metabolomes determined by liquid chromatography-mass spectrometry (LC-MS) suggested that TM upregulated PE (14:0/22:1(13Z)) and SBF decreased formimino-l-glutamic acid and urocanic acid levels. According to the KEGG pathway analysis, SBF treatment has been shown to modulate glycerophospholipid and histidine metabolism to improve allergic reactions. SBF holds great promise as a novel potential agent for the treatment of food allergies.