β-1,3-Glucan reverses aflatoxin B1-mediated suppression of immune responses in mice

Aflatoxin B-1 (AFB(1)) is immunotoxic to animals and is a suspected immunosuppressant in humans. beta-1,3-Glucan (BG) consists of glucose polymers and has a variety of stimulatory effects on the immune system. In this study, we investigated the role of BG on the expression of phenotypic markers and cytokine secretion in mice exposed to AFB(1). We treated animals with BG (150 mg/kg, p.o., once daily) for 7 days beginning at the onset of AFB(1) exposure. Exposure of animals to AFB(1) alone (1250 mu g/kg, p.o, once daily) for 7 days resulted in a decrease in the percentages of lymphocyte subsets (CD4(+), GITR(+), CD8(+), TCR beta(+), CD3(+), Foxp3(+), CD4(+) Foxp3(+), and CD127(+)) as compared to an normal control (NC). However, both BG alone and BG given in conjunction with exposure to AFB(1) significantly increased the percentages of these lymphocyte subsets in blood. We also observed that mice exposed to AFB(1) showed reduced IL-2, TNF-alpha, IL-17, and IFN-gamma production in the spleen and serum. In contrast, oral administration of BG alone and in conjunction with AFB(1) exposure augmented the levels of these cytokines. Moreover, this findingwas confirmed through RT-PCR andwestern blot analysis ofmRNA and protein expression in the spleen. Altogether, it can be concluded from these studies that BG enhances the responses of lymphocyte subsets, including cytokine production, even when given following exposure to AFB(1) immunotoxin. These data demonstrate that BG carries out its immunomodulating activity by regulating cytokine production. Our findings also provide a direction for development of specific immunomodulating therapy. (c) 2016 Elsevier Inc. All rights reserved.