Macrophage immunomodulating and antitumor activities of polysaccharides isolated from Agaricus bisporus white button mushrooms.

Agaricus bisporus white button mushroom (WBM) is widely consumed in most countries for its culinary properties. Recently, its dietary intake has been shown to protect against breast cancer. Mushroom polysaccharides are known for their immunomodulating and antitumor properties; however, little is known regarding the properties of A. bisporus polysaccharides. Using size-exclusion chromatography to fractionate the crude extract of A. bisporus, two polysaccharide fractions (designated as ABP-1 and ABP-2) were obtained. The estimated molecular masses of ABP-1 and ABP-2 were 2,000 kDa and 40-70 kDa, respectively, and their sugar compositions consisted mainly of glucose, mannose, xylose, and fructose. Analysis of the effects of the polysaccharides on murine macrophages demonstrated that both fractions stimulated the production of nitric oxide, interleukin-6, and tumor necrosis factor-α. Modulation of macrophage function by A. bisporus polysaccharides was mediated in part through activation of nuclear factor-κB with the production p50/105 heterodimers. Both ABP-1 and ABP-2 had the ability to inhibit the growth of human breast cancer MCF-7 cells but had little effect on the growth of human colon, prostate, gastric cancer, and murine Sarcoma 180 cells as assessed by a tetrazolium dye [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]-based assay. However, when murine Sarcoma 180 cells exposed to ABP-1 or ABP-2 were implanted subcutaneously into mice, a reduction in tumor growth was observed compared with that observed in control mice. Taken together, our data provide a molecular basis to explain in part the reported beneficial therapeutic effects of A. bisporus WBM intake and suggest that macrophages likely contribute to the antitumor effects of Agaricus polysaccharides.

Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers.

OBJECTIVE: Secretory immunoglobulin A (SIgA) acts as the first line of adaptive humoral immune defense at mucosal surfaces. A lack of SIgA or the inability to produce antigen-specific SIgA can lead to an increased risk of infections. Dietary intake may improve mucosal immunity by accelerating SIgA secretion. This study investigated the effect of dietary intake of Agaricus bisporus white button mushroom (WBM) on salivary IgA (sIgA) secretion in healthy subjects. METHODS: Twenty-four healthy volunteers were randomly assigned to a normal daily diet (control group) or a normal diet with WBM. The subjects in the active group (n = 12, 41.4 ± 11.3 y old) consumed 100 g of blanched WBM daily with their normal diet for 1 wk, whereas those in the control group consumed their normal diet (n = 12, 43.5 ± 12.5 y old) without WBM. Saliva was collected before and after commencement of the study and every week thereafter for 3 wk. Saliva flow rate, sIgA concentration, and osmolality were determined and the sIgA:osmolality ratio and the sIgA secretion rate were calculated. RESULTS: There was no significant difference between pre- and postdietary mushroom intakes for all indices in the control group (P > 0.05). In contrast, the mean sIgA secretion rate increased significantly at weeks 1 and 2 by 53% and 56%, respectively, compared with that at week 0 (P < 0.0005) in the WBM intake group and then returned to a baseline level at week 3. Changes in sIgA secretion rate over the intervention period were greater in the WBM group than in the control group without WBM. In both groups, no significant changes in osmolality and saliva IgG were noted. There was, however, a significant increase in the sIgA:osmolality ratio (P < 0.0012), confirming the postdietary WBM-induced sIgA increase. CONCLUSION: The dietary intake of A. bisporus WBM significantly accelerates sIgA secretion, thereby indicating its potential health benefits for improving mucosal immunity.

White button mushroom (Agaricus bisporus) lowers blood glucose and cholesterol levels in diabetic and hypercholesterolemic rats.

Agaricus bisporus (white button mushroom; WBM) contains high levels of dietary fibers and antioxidants including vitamin C, D, and B(12); folates; and polyphenols that may provide beneficial effects on cardiovascular and diabetic diseases. The objective of this study was to examine the hypothesis that intake of the fruiting bodies of WBM regulates anticholesterolemic and antiglycemic responses in rats fed a hypercholesterolemic diet (0.5% cholesterol; 14% fat) and rats with type 2 diabetes induced by injection of streptozotocin (STZ) (50 mg/kg body weight), respectively. The STZ-induced diabetic male Sprague-Dawley rats fed the Agaricus bisporus powder (ABP; 200 mg/kg of body weight) for 3 weeks had significantly reduced plasma glucose and triglyceride (TG) concentrations (24.7% and 39.1%, respectively), liver enzyme activities, alanine aminotransferase and aspartate aminotransferase (11.7% and 15.7%, respectively), and liver weight gain (P < .05). In hypercholesterolemic rats, oral feeding of ABP for 4 weeks resulted in a significant decrease in plasma total cholesterol (TC) and low-density lipoprotein (LDL) (22.8% and 33.1%, respectively) (P < .05). A similar significant decrease in hepatic cholesterol and TG concentrations was observed (36.2% and 20.8%, respectively) (P < .05). Decrease in TC, LDL, and TG concentrations was accompanied by a significant increase in plasma high-density lipoprotein concentrations. It was concluded that A bisporus mushroom had both hypoglycemic and hypolipidemic activity in rats.

Vitamin B12 is the active corrinoid produced in cultivated white button mushrooms (Agaricus bisporus).

Analysis of vitamin B(12) in freshly harvested white button mushrooms ( Agaricus bisporus ) from five farms was performed by affinity chromatography and HPLC-ESI-MS techniques. The vitamin B(12) concentrations obtained varied from farm to farm, with higher concentrations of vitamin B(12) detected in outer peel than in cap, stalk, or flesh, suggesting that the vitamin B(12) is probably bacteria-derived. High concentrations of vitamin B(12) were also detected in the flush mushrooms including cups and flats. HPLC and mass spectrometry showed vitamin B(12) retention time and mass spectra identical to those of the standard vitamin B(12) and those of food products including beef, beef liver, salmon, egg, and milk but not of the pseudovitamin B(12), an inactive corrinoid in humans. The results suggest that the consumer may benefit from the consumption of mushroom to increase intake of this vitamin in the diet.

Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation.

Agaricus bisporus mushrooms contain an abundance of ergosterol, which on exposure to UV irradiation is converted to vitamin D2. The present study evaluated the effects UV-C irradiation on vitamin D2 formation and its bioavailability in rats. Fresh button mushrooms were exposed to UV-C irradiation at mean intensities of 0.403, 0.316, and 0.256 mW/cm(2) from respective distances of 30, 40, and 50 cm for periods ranging from 2.5 to 60 min. Vitamin D2 and ergosterol were measured by HPLC-MS/MS. The stability and retention of vitamin D2 were assessed including the extent of discoloration during storage at 4 degrees C or at room temperature. Exposure to UV-C irradiation at 0.403 mW/cm(2) intensity from 30 cm distance resulted in a time-dependent increase in vitamin D2 concentrations that was significantly higher than those produced at intensities of 0.316 and 0.256 mW/cm(2) from distances of 40 and 50 cm, respectively. Furthermore, the concentrations of vitamin D2 produced after exposure to UV-C irradiation doses of 0.125 and 0.25 J/cm(2) for, 2.5, 5, and 10 min were 6.6, 15.6, and 23.1 microg/g solids, equivalent to 40.6, 95.4, and 141 microg/serving, respectively. The data showed a high rate of conversion from ergosterol to vitamin D2 at short treatment time, which is required by the mushroom industry. The stability of vitamin D2 remained unchanged during storage at 4 degrees C and at room temperature over 8 days (P = 0.36), indicating no degradation of vitamin D2. By visual assessment or using a chromometer, no significant discoloration of irradiated mushrooms, as measured by the degree of "whiteness", was observed when stored at 4 degrees C compared to that observed with mushrooms stored at room temperature over an 8 day period (P < 0.007). Vitamin D2 was well absorbed and metabolized as evidenced by the serum response of 25-hydroxyvitamin D in rats fed the irradiated mushrooms. Taken together, the data suggest that commercial production of button mushrooms enriched with vitamin D2 for improving consumer health may be practical.

Selective Th2 pattern of cytokine secretion in Mycobacterium avium subsp. paratuberculosis infected Crohn's disease.

BACKGROUND AND AIMS: The pathogenesis of Crohn's disease (CD) remains unclear. A major controversy has been whether infection with Mycobacterium avium subspecies paratuberculosis (MAP) plays a significant role. Current support for a role of MAP is largely based on epidemiological data. The aim of this study was to determine whether MAP detection in gut biopsies is associated with a different cytokine secretion profile as observed in whole blood culture. METHODS: A whole blood culture system was employed to measure cytokine secretion, using an ELISA assay, in subjects with CD (n = 46), ulcerative colitis (n = 30), irritable bowel syndrome (n = 22) and normal controls (n = 18). MAP status was defined by nested PCR using an IS900 sequence unique to MAP. RESULTS: Significantly higher levels of interleukin (IL)-4 (P < 0.05) and IL-2 (P < 0.05) were found in MAP+ CD compared to MAP- CD. This was selective, as MAP+ subjects in both normal and disease controls had similar levels of IL-4 and IL-2 to those with no detectable MAP. IL-4 secretion was correlated with IL-2 production in blood cultures in CD (P < 0.01), consistent with a skewed Th2 immune response. CONCLUSIONS: This data set provides the first evidence of altered T cell function linked to MAP infection in CD, and provides a link between detection of MAP and disease. The pattern of cytokine shift in CD is consistent with the concept that the increasing incidence of CD is in part related to the hygiene theory.

Probiotics--industry myth or a practical reality?

Probiotics are "bacteria that are good for you' evolving out of the food industry, without quality data or a framework in which to function. This review asks three questions, the answers to which dictate the level of success that probiotics have had in moving into the medical model. How do they work? Evidence is summarised to show that (at least) certain bacteria activate Peyer's patch T cells to drive the common mucosal system via toll-like receptors on antigen presenting cells. They influence distant mucosal sites, promoting Th1 cytokine responses while downregulating Th2 responses. New data is included. Are all probiotics the same? They clearly are not - variation occurs between different isolates and importantly within isolates due to variable production/storage and poor quality control. These latter issues, together with poor clinical trials lacking surrogate markers of activation, have made clinical assessment very difficult. Do they have a role in man? Yes they do, but whether that is now or in the future largely depends on the quality of studies done. There is clear evidence in man that mucosal INF-gamma secretion is stimulated, indicating promotion of immune protection, downregulation of hypersensitivity disease and (yet to be demonstrated) enhanced apoptosis to reduce cancer risk. Preliminary evidence suggests that certain probiotics may regulate cytokine secretion around a mean, ensuring optimal protection without non-specific damage. Thus probiotics appear to restore defective immunity rather than stimulate, an observation relevant to restoration of Th1 immunity in infants.

Selective reduction of anti-Helicobacter pylori IgG subclass antibody in gastric carcinoma.

BACKGROUND: Epidemiological studies have demonstrated strong links between Helicobacter pylori infection and gastric adenocarcinoma. Recent studies suggest that cell-mediated immunity influences the outcome of infection, including the development of gastric adenocarcinoma. The T-cell response can be characterized in terms of the secreted cytokine profile, which in turn influences the B-cell response including the balance of IgG subclass antibody. METHODS: Serum anti-H. pylori IgG, IgG1 and IgG2 antibodies were studied by ELISA in subjects with benign gastric diseases, gastric dysplasia and gastric adenocarcinoma. RESULTS: The distribution patterns of IgG subclass anti-H. pylori antibody varies significantly between H. pylori-linked benign and malignant disease in subjects infected with H. pylori. Significantly lower IgG2 levels were found in subjects with gastric adenocarcinoma compared with those with reflux esophagitis, chronic gastritis, gastric ulcer, and peptic ulcer, while IgG1 antibody remained at similar levels in both benign and malignant disease. A limited study of seropositive subjects with premalignant change was consistent with the fall in IgG2 antibody pre-dating malignant change, although pre-eradication results are needed to validate these data. CONCLUSIONS: These studies indicate that subjects with low levels of IgG2 anti-H. pylori antibody are at risk of gastric adenocarcinoma, and that the previously described linkage between gastric adenocarcinoma and low total IgG antibody does not simply reflect reduced gastric colonization. The diagnostic value of this assay for pre-endoscopy screening is attractive.

Innate versus adaptive immunity in Candida albicans infection.

Candida albicans is a common opportunistic pathogen, causing both superficial and systemic infection. Clinical observations indicate that mucocutaneous infections are commonly associated with defective cell-mediated immune responses, whereas systemic infection is more frequently seen in patients with deficiencies in neutrophil number or function. Analysis of mechanisms of host resistance against gastrointestinal and oral infection in mouse models has demonstrated an absolute dependence on CD4(+) T cells, although clearance also involves phagocytic cells. Both IL-12 and TNF-alpha appear to be important mediators, but mouse strain-dependent variations in susceptibility to infection may be related to T-cell enhancement of production of phagocytic cells by the bone marrow. In murine systemic infection, the role of innate and adaptive responses is less well defined. Studies in immunodeficient and T-cell-depleted mice suggest that clearance of the yeast may be predominantly a function of the innate response, whereas the adaptive response may either limit tissue damage or have the potential to cause immunopathology, depending on the host genetic context in which the infection takes place.

Can the response to eradication therapy in Helicobacter pylori infection be predicted?

The failure to eradicate Helicobacter pylori infection with antibiotic therapy has become a major clinical problem, not entirely accounted for by either poor compliance or antibiotic resistance. Recognition that failed eradication is one outcome of the host-parasite relationship focuses attention on impaired host protection as a determinant of nonresponse to antibiotics. A secreted interleukin (IL)-4 whole blood assay was developed to determine whether persistent infection was contributed to by impaired cytokine responses. The blood assay was shown to correlate well with mucosal organ cultures. Significantly lower levels of IL-4 were detected in the whole blood assays in 11 subjects with failed eradication compared with subjects with successful eradication (P<0.05). This latter group underwent a Th1 to Th0 "switch", which appears to be important to successful eradication. Detection of subjects at risk for failing to eradicate infection with standard combination therapy, by virtue of low secreted IL-4 in whole blood cultures, may have clinical value.

Development of surrogate markers for oral immunisation against Candida albicans.

We have developed an oral vaccine using the blastococcoid form of Candida albicans with a murine model of oral candidiasis with infection-resistant (BALB/c) and infection-prone (DBA/2) mice. Previous studies had demonstrated that enhanced clearance was linked to increased production of both Th1 and Th2 cytokines (IFN-gamma and IL-4, respectively) in regional lymph nodes, and increased secretion of IFN-gamma and NO in saliva. Subsequent study using oral Lactobacillus acidophilus (LAVRI-A1) induced a local cytokine pattern and enhanced clearance of intra-oral C. albicans similar to that noted in animals given killed candida vaccine. Thus, the experiment was repeated with a 2 month gap between completion of a vaccine course and challenge with live C. albicans. Compared to control mice, those given the oral vaccine had a 4 log reduction in colonisation on day 2, associated with twice the levels of secretion of IFN-gamma and IL-4 from the regional node cells, five times the level of nitric oxide in saliva, and suppression of NO production with MMLA induced a 2 log increase in oral colonisation. Thus while both IFN-gamma and IL-4 appear to contribute to clearance of oral C. albicans, IL-4 appears to act through a paracrine enhancement of NO production. Studies in man are in progress to define similar surrogate markers of immune protection, prior to oral vaccine trial.

Impaired host immunity contributes to Helicobacter pylori eradication failure.

OBJECTIVES: Effective eradication of Helicobacter pylori (H. pylori) infection has often proved more difficult than expected. Antimicrobial resistance incompletely explains eradication failure. This study tests the hypothesis that an impaired immune response may contribute to failed eradication after standard antibiotic therapy. METHODS: Parameters of host immunity were assessed as blood T lymphocyte production of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) being surrogate markers of mucosal Th1 and Th2 responses, respectively. The validity of using circulating T cell cytokines as surrogate markers of mucosal immunity was established (unstimulated lymphocyte IL-4 level correlation r2 = 0.549, p < 0.001; antigen-stimulated lymphocyte correlation r2 = 0.62, p < 0.001). RESULTS: A total of 52 dyspeptic patients and 11 patients with previous H. pylori eradication failure were recruited into the study. There was no significant difference in secretion of IFN-gamma from peripheral blood T cells, in either unstimulated or antigen-stimulated cultures, between clinical groups. There was, however, a significant reduction in secretion of IL-4 from blood T cells in subjects failing to eradicate H. pylori compared with those who successfully eradicated the infection in both unstimulated and stimulated cultures. A significant difference in IL-4 secretion was also detected in antigen-stimulated cultures compared with that in H. pylori-positive subjects (p < 0.05). Low levels of IL-4 secretion were detected irrespective of the number of courses of antibiotic therapy. Lower levels of IgG anti-H. pylori antibody were detected in both serum and saliva of subjects with persistent H. pylori infection after use of antibiotics compared with untreated H. pylori-positive subjects (difference not statistically significant). CONCLUSIONS: These results support the hypothesis that impaired mucosal immunity, particularly involving the secretion of IL-4, may contribute to H. pylori eradication failure. Measurement of whole blood secretion of IL-4 may predict which patients are more likely to fail standard antibiotic therapy.