Immunity improvement and gut microbiota remodeling of mice by wheat germ globulin

Abstract

The wheat germ protein (WG) and it's proteolytic peptide have a variety of biological activities. Our previous work showed that WG could improve immunity of the immunosuppressive mice established by cyclophosphamide. However, in the healthy condition and normal diet, as a supplementary food, the effects of immunity improvement and gut microbiota remodeling by the wheat germ globulin has not been studied yet. Here, we reported that WG could improve the immunity and remodel the gut microbiota of the mice, as a safe functional supplementary food for the rst time. The increase of interleukin-6 (IL-6) and the decrease of tumor necrosis factor α (TNF-α) and interleukin-10 (IL-10) indicated that WG could enhance the levels of activated T cells and monocytes and antiin ammatory ability, meanwhile, the signi cant increase of immunoglobin G (lgG) and the notable decrease of the immunoglobin M (lgM) and immunoglobin A (lgA) illustrated that WG could improve immunity by promoting the differentiation and maturation process of B cells, compared with the NC group. 16S rRNA sequencing showed WG could remodel the gut microbiota. At the phylum level, the Bacteroidetes were reduced and Firmicutes were increased in WG group, compared with NC group. At the genus level, the SCFA producing genera of unclassi ed_f_Lachnospiraceae, Blautia and especially the Roseburia (increased more than threefold) increased notably. Further, the level changes of cytokines and immunoglobulins were associated with the gut microbiota. This work showed that WG could improve immunity and has potential application value as an immune-enhancing functional food.

Isolation, purification, and characterization of the globulin from wheat germ

“…Due to the existence of these proteins, wheat could not only prevent diseases, resist adversity, and maintain normal metabolism in the process of growth and development but also had high medicinal value in the prevention and treatment of cardiovascular diseases, cancer, and tumor and improve immunity (Zhang et al ., 2019). The WGG had been reported to stimulate their immune effects in terms of engulfing foreign particles, stimulating cells to produce nitric oxide, and exciting cells to produce interleukin‐6 and tumor necrosis factor‐α (Wu et al ., 2017a,b; Yu et al ., 2021a,b). Ji et al .…”

“…Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) was applied to determine the molecular weight of globulin with 12% dissolved gel and 4% stacked gel (Yu et al ., 2021a,b). The protein sample was dissolved in electrophoresis sample buffer (0.125 mol L −1 Tris‐HCl buffer, containing 1% (m/V) SDS, 2% (V/V) mercaptoethanol, 5% (V/V) glycerol, and 0.025% (m/V) bromophenol blue.…”

“…The structure information of wheat germ globulin was analyzed by PeakFit V4.12 software. The corresponding relationship between the secondary structure and ranges of the amide I region is as follows: (i) β‐sheet, the bands located at 1610–1640 cm −1 ; (ii) random coils, the bands located at 1640–1650 cm −1 ; (iii) α‐helix, the bands located at 1650–1658 cm −1 ; (iv) β‐turns, the bands located at 1660–1695 cm −1 (Yu et al ., 2021a,b).…”

“…At present, more and more researchers shift their attentions from animal‐source globulin to plant‐source globulin. The plant‐source globulin has some interesting properties such as antioxidation, anticancer, antiaging and antiobesity, and is a functional protein involved in immune regulation (Amagliani et al ., 2017; Yu et al ., 2021a,b). Especially, plant‐source globulin is more abundant, cheaper, and more accessible than animal‐source globulin (Wu et al ., 2017a,b; Wen et al ., 2019).…”

“…Many studies have shown that proteins are assisted extracted by ultrasound treatment, microwave treatment, high‐pressure treatment, and enzymatic degradation (Amagliani et al ., 2017; Wen et al ., 2018; Leal et al ., 2021). The functional properties of proteins are greatly influenced not only by raw materials (e.g., variety) but also by processing parameters and/or extraction methods (Yao et al ., 2021; Yu et al ., 2021a,b). The stress of proteins to external conditions (such as ultrasound, pH value, pretreatment, and heating) is different, which leads to difference of their processing characteristics (Malumba et al ., 2008; Emkani et al ., 2021; Liu et al ., 2021; Wen et al ., 2019).…”