Abstract: Objective: To study the impact of Tremella polysaccharide on the ameliorative effect of probiotic-fermented camel milk on immunity and intestinal mucosal barrier function in cyclophosphamide (CTX)-induced immunosuppressed mice. Methods: The physicochemical indexes and antioxidant activities of probiotic-fermented camel milk with and without added Tremella polysaccharide were determined. BALB/C mice were randomly divided into four groups: normal (NC), model (MD), probiotic-fermented camel milk (FCM), and probiotic-fermented camel milk with Tremella polysaccharide (FYCM), which were gavaged with 0.2 mL of normal saline, normal saline, FCM, and FYCM for 30 days, respectively. During the last four days, all groups except the NC group were intraperitoneally injected with a daily dose of 60 mg/kg·mb CTX to establish an immunosuppression model. Organ indexes, the proliferation activity of spleen lymphocytes, delayed-type allergic reaction, cytokine and immunoglobulin contents, spleen and jejunum morphology were analyzed. Results: During 21 days of low temperature storage, the pH of FYCM decreased slowly from 4.52 to 4.30, the titratable acidity increased gradually from 95.7 to 124.73 °T, the number of lactic acid bacteria decreased from 9.40 × 109 to 8.38 × 109 CFU/mL, and the water holding capacity decreased from 39.23% to 35.13%. Compared with FCM, the antioxidant capacity of FYCM was significantly improved (P < 0.01). Furthermore, compared with the MD group, FYCM significantly improved organ indexes, spleen lymphocyte proliferation activity and delayed-type hypersensitivity (DTH), upregulated the levels of interleukin (IL)-6, interferon-γ (IFN-γ), immunoglobulin G (IgG), immunoglobulin M (IgM), and secretory immunoglobulin A (sIgA), and repaired spleen and jejunum mucosal structures, and its effect was significantly more pronounced than that of FCM. Conclusion: Probiotic-fermented camel milk incorporated with Tremella polysaccharide has the potential to regulate immune and intestinal mucosal barrier function, thereby having broad application prospects in the functional dairy market.

Key words: Tremella polysaccharide; camel milk; probiotics; fermented milk; immunomodulation