The effects of whole mushrooms during inflammation

Abstract

Background: Consumption of edible mushrooms has been suggested to improve health. A number of isolated mushroom constituents have been shown to modulate immunity. Five commonly consumed edible mushrooms were tested to determine whether whole mushrooms stimulate the immune system in vitro and in vivo.

Results: The white button (WB) extracts readily stimulated macrophage production of TNF-alpha. The crimini, maitake, oyster and shiitake extracts also stimulated TNF-alpha production in macrophage but the levels were lower than from WB stimulation. Primary cultures of murine macrophage and ovalbumin (OVA) specific T cells showed that whole mushroom extracts alone had no effect on cytokine production but co-stimulation with either lipopolysaccharide or OVA (respectively) induced TNF-alpha, IFN-gamma, and IL-1beta while decreasing IL-10. Feeding mice diets that contained 2% WB mushrooms for 4 weeks had no effect on the ex vivo immune responsiveness or associated toxicity (changes in weight or pathology of liver, kidney and gastrointestinal tract). Dextran sodium sulfate (DSS) stimulation of mice that were fed 1% WB mushrooms were protected from DSS induced weight loss. In addition, 2% WB feeding protected the mice from transient DSS induced colonic injury. The TNF-alpha response in the colon and serum of the DSS challenged and 2% WB fed mice was higher than controls.

Conclusion: The data support a model whereby edible mushrooms regulate immunity in vitro. The in vivo effects of edible mushrooms required a challenge with DSS to detect small changes in TNF-alpha and transient protection from colonic injury. There are modest effects of in vivo consumption of edible mushrooms on induced inflammatory responses. The result is not surprising since it would certainly be harmful to strongly induce or suppress immune function following ingestion of a commonly consumed food.

Figure 1

Production of TNF-α by RAW 264.7 cells. Mushroom extracts (100 μg/ml), LPS or vehicle (DMSO) controls were added to Raw 264.7 cells and 72 h later TNF-α production was evaluated in triplicate cultures. Data from one representative of three individual experiments are shown. Values are mean ± SD, *p < 0.05 compared to the LPS TNF-α response.

Figure 2

Cytokine production by primary BMDM. WB mushroom extracts alone, LPS alone or WB in combination with LPS (WB+LPS) were added to BMDM. Supernatants were harvested 72 h later and (A) TNF-α, (B) IL-1β and (C) IL-10 were detected by ELISA. The data is one representative of four individual experiments. Values are mean ± SD of triplicate cultures. Values for WB+LPS are significantly different from LPS stimulated with the p value as shown.

Figure 3

Mushroom mediated inhibition of IL-10 and enhancement of IFN-γ. Splenocytes from OT II mice were stimulated with OVA plus WB, Crimini, Shiitake, Oyster and Maitake extracts or Control (OVA plus DMSO). (A) IL-10 and (B) IFN-γ secretion. Representative data from two individual experiments with n = 5–6 mice each. Values are mean ± SEM. Values are significantly different from the control group, *p < 0.05, **p < 0.01.

Figure 4

In vivo effects of feeding mushrooms. C57BL/6 mice were fed control diet only or control diet that contained 2% WB freeze dried mushrooms. (A) Weights of the WB fed mice gained weight over the 4 weeks of the study. Values are mean ± SEM with 6–10 mice per group. (B) IL-10 and (C) IFN-γ production of Con A and LPS stimulated splenocytes from 1% WB fed, 1% oyster fed and control (Ctrl) fed mice. Values are mean ± SEM with 3–5 mice per group.

Figure 5

DSS challenge of 1% WB, 1% oyster and control fed mice. Control, WB and oyster fed mice that were treated with DSS for 5 d followed by water for 5 d (10 d post-DSS). (A) Percentage of starting weight following DSS treatment, (B) colonic length at d 10 after DSS treatment, and (C) colonic production of TNF-α, IL-1β and IL-10 at d 10 post-DSS. Values are mean ± SEM of 4–6 mice per group.

Figure 6

DSS colitis of 2% WB fed and control fed mice. Control, and WB fed mice were treated with DSS for 5 d (5 d post-DSS) followed by water for 5 d (10 d post-DSS). (A) Colonic length as a function of DSS treatment, TNF-α production at d 10 post-DSS in the colon (B) and serum (C). Values are mean ± SEM of 4–8 mice per group. Values are significantly different from the control group, *p < 0.05.

Figure 7

Model of the effects of whole mushrooms on anti-cancer immunity. Whole mushrooms contain active components that can induce TNF-α, and IL-1β in vitro while inhibiting IL-10 production. Consuming mushrooms in the diet also had an effect on immune function but that effect is evident only when the immune system is challenged. The change in the immune response induced by whole mushrooms is consistent with a potentially important improvement in cancer surveillance and anti-microbial killing while increasing inflammation and perhaps autoimmunity.