Inhibitory effects of dietary soyasaponin on 2,4-dinitrofluorobenzene-induced contact hypersensitivity in mice

More than a meat- or synthetic nitrogen fertiliser-substitute: a review of legume phytochemicals as drivers of 'One Health' via their influence on the functional diversity of soil- and gut-microbes

Legumes are essential to healthy agroecosystems, with a rich phytochemical content that impacts overall human and animal well-being and environmental sustainability. While these phytochemicals can have both positive and negative effects, legumes have traditionally been bred to produce genotypes with lower levels of certain plant phytochemicals, specifically those commonly termed as 'antifeedants' including phenolic compounds, saponins, alkaloids, tannins, and raffinose family oligosaccharides (RFOs). However, when incorporated into a balanced diet, such legume phytochemicals can offer health benefits for both humans and animals. They can positively influence the human gut microbiome by promoting the growth of beneficial bacteria, contributing to gut health, and demonstrating anti-inflammatory and antioxidant properties. Beyond their nutritional value, legume phytochemicals also play a vital role in soil health. The phytochemical containing residues from their shoots and roots usually remain in-field to positively affect soil nutrient status and microbiome diversity, so enhancing soil functions and benefiting performance and yield of following crops. This review explores the role of legume phytochemicals from a 'one health' perspective, examining their on soil- and gut-microbial ecology, bridging the gap between human nutrition and agroecological science.

Nestin+ Mesenchymal Precursors Generate Distinct Spleen Stromal Cell Subsets and Have Immunomodulatory Function

Mesenchymal stromal cells (MSCs) are known to be widespread in many tissues and possess a broad spectrum of immunoregulatory properties. They have been used in the treatment of a variety of inflammatory diseases; however, the therapeutic effects are still inconsistent owing to their heterogeneity. Spleen stromal cells have evolved to regulate the immune response at many levels as they are bathed in a complex inflammatory milieu during infection. Therefore, it is unknown whether they have stronger immunomodulatory effects than their counterparts derived from other tissues. Here, using a transgenic mouse model expressing GFP driven by the Nestin (Nes) promoter, Nes-GFP⁺ cells from bone marrow and spleen were collected. Artificial lymphoid reconstruction in vivo was performed. Cell phenotype, inhibition of T cell inflammatory cytokines, and in vivo therapeutic effects were assessed. We observed Nes-GFP⁺ cells colocalized with splenic stromal cells and further demonstrated that these Nes-GFP⁺ cells had the ability to establish ectopic lymphoid-like structures in vivo. Moreover, we showed that the Nes-GFP⁺ cells possessed the characteristics of MSCs. Spleen-derived Nes-GFP⁺ cells exhibited greater immunomodulatory ability in vitro and more remarkable therapeutic efficacy in inflammatory diseases, especially inflammatory bowel disease (IBD) than bone marrow-derived Nes-GFP⁺ cells. Overall, our data showed that Nes-GFP⁺ cells contributed to subsets of spleen stromal populations and possessed the biological characteristics of MSCs with a stronger immunoregulatory function and therapeutic potential than bone marrow-derived Nes-GFP⁺ cells.

Paeoniflorin Attenuated TREM-1-Mediated Inflammation in THP-1 Cells

Sepsis is caused by bacterial infections or viral infections. Clinically, there exist confirmed or highly suspected infection foci. Mortality caused by septic shock remains in a high rate even though antibiotic treatment works effectively. In this study, we treat THP-1 cells with 1 ug/mL LPS (lipopolysaccharide) and add paeoniflorin or LR-12 inhibitor. TREM-1 (triggering receptor expressed on myeloid cells-1), IL-6, IL-1β, and TNF-α (tumour necrosis factor alpha (a)-cachectin) were detected by ELISA and qRT-PCR, and western blotting is performed to detect related proteins in the NF-κB signaling pathway. As a result, paeoniflorin can significantly reduce the production of LPS-stimulated TREM-1 as well as inflammatory factors and attenuate the phosphorylation of NF-κB signaling pathway-related factors, such as p65 and IκBα. At the same time, the combined effect of paeoniflorin and LR-12 is more significant. The results of this study solidly prove that paeoniflorin plays a role in inhibiting TREM-1-mediated inflammation and the NF-κB pathway could be a potential mechanism of action.

Dietary soya saponin improves the lipid metabolism and intestinal health of laying hens

Soya saponin (SS) is a natural active substance of leguminous plant, which could improve lipid metabolism and regulate immune function. Intestinal flora might play a key role in the biological functions of SS. The objective of this study was to measure the effects of dietary SS on immune function, lipid metabolism, and intestinal flora of laying hens with or without antibiotic treated. The experiment was designed as a factorial arrangement of 3 dietary SS treatments × 2 antibiotic treatments. Birds were fed a basal diet (CON) or a low-SS diet (50 SS) containing 50 mg/kg SS, or a high-SS diet (500 SS) containing 500 mg/kg SS. Birds were cofed with or without antibiotics. The growth experiment lasted for 10 wk. Results showed that birds fed the 50 mg/kg SS diet tended to have lower abdominal fat rate. The gene expression of liver X receptor-α (LxR-α) in liver and serum total cholesterol (TC) were dropped, and the gene expression of acyl-CoA thioesterase 8 (ACOT8) in liver were upregulated. Compared with CON group, the levels of lysozyme, IL-10, and transforming growth factor (TGF-β) in the serum were elevated as along with gene expression of IL-10, TGF-β, and LYZ in ileum of both 50 and 500 SS group. However, the level of secretory immunoglobulin A (sIgA) and Mucin-2 in the ileum were downregulated in the 500 SS group. Additionally, Lactobacillus and Lactobacillus gasseri were the dominant bacteria in the 50 SS group, whereas the relative abundance of Lactobacillus was dropped in the 500 SS group. With combined antibiotics treatment, the α-diversity of bacteria was reduced, and the biological effects of SS were eliminated. In conclusion, the lipid metabolism, immune function, and intestinal flora of the laying hens were improved with the dietary supplementation of 50 mg/kg SS. But dietary 500 mg/kg SS had negative effects on laying hens.

An isoflavone extract from soybean cake suppresses 2,4-dinitrochlorobenzene-induced contact dermatitis

ETHNOPHARMACOLOGICAL RELEVANCE

Numerous epidemiological and clinical studies have demonstrated the protective role of dietary isoflavones against development of several chronic diseases. ISO-1, one fraction of isoflavone powders derived from soybean cake, is reported to attenuate inflammation and photodamage.

AIM OF THE STUDY

Contact dermatitis is a common inflammatory skin disease, which accounts for most occupational skin disorders. Instead of oral administration, we aimed to explore the effects of topical ISO-1 application on contact dermatitis by using 2,4-dinitrochlorobenzene (DNCB)-stimulated HaCaT keratinocytes and DNCB-induced mouse dermatitis as models.

MATERIALS AND METHODS

In the in vitro study, we first evaluated the biologic effects of DNCB on HaCaT keratinocytes. HaCaT keratinocytes were treated with 2,4-dinitrochlorobenzene (DNCB), and cell viability was measured by MTT assay. Then, we detect the prominent induction of IL-8 mRNA expression after DNCB and ISO-1 treatment by reverse transcription polymerase chain reaction (RT-PCR), and release of IL-8 from HaCaT keratinocytes was measured by ELISA assay. HaCaT keratinocytes were pretreated with ISO-1 and then treated with DNCB, phosphorylation of JNK, p38, ERK and IκBα was analyzed by western blot. In the in vivo study, the hairless mice were used for an induced contact dermatitis model. The surface changes in the dorsal skin after DNCB and ISO-1 treatment were recorded using photography, and TEWL, erythema were measured using an MPA-580 cutometer. Blood was also collected from mice for measurement of white blood cell counts.

RESULTS

Results showed ISO-1 inhibited DNCB-induced IL-8 production and also suppressed DNCB-induced phosphorylation of JNK and p38, and IκBα in HaCaT. In the animal model of DNCB-induced contact dermatitis, topical ISO-1 treatment significantly decreased DNCB-induced erythema and transepidermal water loss (TEWL) in mouse skin. ISO-1 also reduced DNCB-induced skin thickening and increase of white blood cell count.

CONCLUSIONS

ISO-1 is promising for improvement of DNCB-induced inflammation and skin barrier impairment, suggesting the potential application of topical ISO-1 for inflammatory dermatoses.

Inhibitory effects of dietary soy isoflavone and gut microbiota on contact hypersensitivity in mice

Soy isoflavones (SIs) are abundant in soybeans and have inhibitory effects on contact hypersensitivity (CHS), which is often used as a mouse model for allergic contact dermatitis (ACD); however, their therapeutic mechanisms remain unknown. We studied the suppressive activity of dietary SI and gut microbiota on dinitrofluorobenzene (DNFB)-induced CHS. Low-dose SI diets alleviated DNFB-induced ear swelling and oedema and decreased infiltration of Gr-1-positive cells into ear tissue. In addition, dietary SIs also decreased interleukin-1β and chemokine (C-X-C motif) ligand 1 production in ear tissue compared to controls. Furthermore, ciprofloxacin and metronidazole treatments blocked the suppressive activity of dietary SIs on CHS, whereas vancomycin treatment had a marginal effect. These antibiotic treatments differed in their effects on the gut microbiota composition. These results demonstrated that consumption of physiologically relevant doses of SIs reduced CHS symptoms, and suggested that the gut microbiota influenced their suppressive activities on CHS.

Dietary soyasaponin attenuates 2,4-dinitrofluorobenzene-induced contact hypersensitivity via gut microbiota in mice

Soyasaponins (SSs) are abundant in soybeans and display inhibitory activity against contact hypersensitivity (CHS), which is often used as a mouse model for allergic contact dermatitis (ACD); however, their therapeutic mechanisms remain unknown. Here, we attempted to clarify the role of gut microbiota in the inhibition of CHS by dietary soyasaponins. For antibiotic treatment, mice were administered a mixture of ciprofloxacin and metronidazole or vancomycin. These antibiotics and SSs were given to mice via drinking water 3-weeks prior to CHS induction with 2,4-dinitrofluorobenzene, and the mice were analysed for ear swelling, tissue oedema, infiltration of Gr-1-positive immune cells, the composition of faecal microbiota and regulatory T (Treg ) cells. The soyasaponin diets attenuated ear swelling and tissue oedema, and reduced the number of Gr-1-positive cells infiltrating ear tissues. CHS caused changes in the structure of the gut microbiota, but dietary SSs blocked the changes in the microbiota composition. Ciprofloxacin and metronidazole treatments significantly enhanced the severity of CHS symptoms, whereas vancomycin treatment blocked the suppressive effect of dietary SSs on CHS. These antibiotic treatments differed in their effects on the gut microbiota composition. Treg cells in auricular lymph node and spleen increased under SS-enriched diets, but this increase was blocked by vancomycin treatment. These results suggest that dietary SSs exert their inhibitory activity on CHS via the gut microbiota in mice, suggesting that dietary supplementation with SSs may have beneficial effects on ACD patients, but that the gut microbiota is a critical determinant of the therapeutic value of dietary SSs.

Impact of soymilk consumption on 2,4-dinitrofluorobenzene-induced contact hypersensitivity and gut microbiota in mice

Soymilk is rich in phytochemicals such as soy isoflavones (SIs) and soyasaponins (SSs). Dietary SIs and SSs display inhibitory effects on contact hypersensitivity (CHS), which was reported in a mouse model for allergic contact dermatitis (ACD); however, the beneficial effects of soymilk consumption on CHS remain unknown. Here, we studied the effects of drinking soymilk on CHS and gut microbiota. Soymilk consumption attenuated ear oedema and swelling, decreased the infiltration of Gr-1-positive cells into ear tissues, and reduced the production of chemokine (C-X-C motif) ligand 2 and triggering receptor expressed on myeloid cells-1 in ear tissues. The analysis of bacterial 16S ribosomal RNA gene sequences indicated that CHS caused changes in the gut microbiota structure and that consuming soymilk reduced these changes. These results suggest that soymilk consumption may be of therapeutic value for patients with ACD and may help control the balance of intestinal microbiota.

A Sensitive and Rapid UPLC-MS/MS Method for Determination of Monosaccharides and Anti-Allergic Effect of the Polysaccharides Extracted from Saposhnikoviae Radix

Background: Allergic disease is a common clinical disease. Natural products provide an important source for a wide range of potential anti-allergic agents. This study was designed to evaluate the anti-allergic activities of the water-soluble polysaccharides extracted and purified from Saposhnikoviae Radix (SRPS). The composition and content of monosaccharides were determined to provide a material basis. Methods: An ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established to determine the composition and content of SRPS. 2,4-dinitrofluorobenzene (DNFB) induced a delayed-type hypersensitivity (DTH) mouse model orally administrated SRPS for seven consecutive days. Ear swelling, organ index, and serum IgE levels were observed to evaluate the anti-allergic activities. Results: The UPLC-MS/MS analysis showed that SRPS was consisted of eight monosaccharides including galacturonic acid, mannose, glucose, galactose, rhamnose, fucose, ribose, and arabinose with a relative molar ratio of 4.42%, 7.86%, 23.69%, 12.06%, 3.10%, 0.45%, 0.71%, and 47.70%, respectively. SRPS could effectively reduce ear swelling, a thymus index, and a serum IgE levels. Conclusions: The method was simple, rapid, sensitive, and reproducible, which could be used to analyze and determine the monosaccharide composition of SRPS. The vivo experiments demonstrated that SRPS may effectively inhibit development of DNFB-induced DTH. SRPS is a novel potential resource for natural anti-allergic drugs.

Group B Soyasaponin Aglycone Suppresses Body Weight Gain and Fat Levels in High Fat-Fed Mice

Group B soyasaponins, found in soy, have various health-promoting properties, but it is unclear whether they have an anti-obesity effect. The aim of this study was to evaluate the anti-obesity effect of group B soyasaponin glycosides and aglycone in mice fed a high-fat diet. Six-week-old C57/BL6 mice were divided into three groups (each n=10) and orally administered a high-fat diet for 35 d; two of the groups also received group B soyasaponin glycosides or aglycone. Although there was no significant difference among the three groups in consumption, the weight of fat adipose tissue at autopsy was more than 30% lower in the group B soyasaponin aglycone group than in the control group, but X-ray computed tomography showed no significant difference in muscle weight between these two groups. The ratio of muscle to whole body weight was higher in the group B soyasaponin aglycone group than in the control group. These results suggest that group B soyasaponin aglycone has a stronger anti-obesity effect than group B soyasaponin glycosides, without a loss in muscle weight, and that it increases the ratio of muscle to whole body weight. To our knowledge, this is the first report showing the anti-obesity effect of soyasaponin aglycone in vivo using animal models.