Dietary plasma proteins modulate the adaptive immune response in mice with acute lung inflammation

We examined the effects of oral plasma protein supplements on the pulmonary adaptive immune response in mice challenged with intranasal LPS. C57BL/6 mice were fed a control diet or a diet supplemented with plasma proteins [spray-dried plasma (SDP) 80 g/kg] or with an Ig concentrate [(IC) 20 g/kg] from postnatal d 19 (weaning) until d 34. Mice were challenged with PBS or LPS from Escherichia coli at d 33 and killed 24 h later for leukocyte analyses or at d 34 and killed 6 h later for cytokine determination. LPS induced the activation of T helper (Th) lymphocytes in lung and blood and this response was reduced by SDP and IC (P < 0.05). In both tissues, LPS increased the Th1 and Th2 subpopulations and this effect was inhibited by the two plasma protein supplements (P < 0.05). The LPS challenge increased the expression of all the cytokines studied (P < 0.01). SDP and IC reduced the expression of IFNγ, IL-5, IL-12p40, IL-12p70, IL-13, and IL-17 in both tissues, whereas they increased the percentage of regulatory Th lymphocytes in lung, even in PBS-treated mice (P < 0.05). LPS reduced the concentration of mature TGFβ1 (P < 0.05) in the lung but did not modify the expression of IL-10. Mice exposed to LPS and supplemented with SDP or IC showed an increased expression of the anti-inflammatory cytokine IL-10 (P < 0.05). Moreover, the two supplements increased the concentration of IL-10 in intestinal mucosa (P < 0.05). Our results show that plasma supplementation reduces the immune response that characterizes the acute lung inflammation syndrome.