Background: Wheat germ, one of the byproducts of flour milling, contains abundant
physiologically active components. Globulins in wheat germ are a class of high-quality functional
proteins and have received widespread attention. However, the composition of wheat germ globulin（
WGG）and the structure of the typical proteins have not yet been proved. The immunological
activities and immune mechanisms of the WGG have not yet been revealed in vivo.
Objectives: The proteomic analysis of WGG and the structure simulation of typical proteins were
studied. The immunoregulatory effects of WGG on immunosuppressed mice induced by cyclophosphamide
were investigated, and the immunological activities of WGG were explored.
Methods: The main components, functions, and metabolic signaling pathways of WGG were analyzed
through a combination of LC-MS method and bioinformatics. The structure of WGG was
predicted via the Phyre2 tool. Immunosuppression in mice was induced by cyclophosphamide.
After an intraperitoneal injection of WGG for 10 days, organ indexes and pathological changes of
mice were detected. The T-cell subgroups in peripheral blood were analyzed via flow cytometry.
Levels of IL-2, IL-4, TNF-α, and IFN-γ were evaluated through ELISA. The mRNA expression
levels of T-Bet and GATA-3 were measured using real-time PCR.
Results: The results indicated that the main functional components of WGG were wheat germ
globulins, histones, heat shock proteins (HSPs), and other functional proteins. Wheat germ globulins
and HSPs were the major immune components of WGG. WGG significantly reduced immunosuppression
in the spleen and thymus indexes (P<0.01), and mitigated the damage caused by cyclophosphamide
in the spleen and thymus. Moreover, WGG significantly increased the CD4+/CD8+ of
the immunosuppressed mice (P<0.01), restored Th1/Th2 imbalance (P < 0.01), enhanced the content
of IL-2 and IL-4 (P<0.01), and modified the abnormal secretion of cytokines. WGG also observably
reduced the mRNA expression of T-Bet and GATA-3 (P<0.01). These results manifested
that WGG components improved the immune system. The action mechanisms might be related to
the variation of Th1/Th2 cells resulted from the control of the mRNA expression levels of T-Bet
Conclusion: The wheat germ histone family and the HSPs are the major immune components of
WGG. It may be the immune mechanism of WGG that these globulins affect the differentiation of
Th1/Th2 cells via controlling the mRNA expression levels of related genes. The results indicated
the potential application of WGG or its further purified products as a superior plant-derived immunomodulator
in the future.