Immunomodulatory activity of extracts from five edible basidiomycetes mushrooms in Wistar albino rats

Abstract

Mushrooms are nutritious foods that are widely cultivated all over the world. They are rich in a range of compounds linked to improving functions of the immune system including carotenoids, alkaloids, lectins, enzymes, folates, fats, organic acids, minerals, polysaccharides, phenolics, proteins, tocopherols, terpenoids, and volatile compounds. In this study we investigated, the immunomodulatory activity in rats of the aqueous extracts of five of the most common edible mushrooms belonging to Family Basidiomycota-white-rot fungi including, Lentinula edodes, Agaricus bisporus, Pleurotus ostreatus, Pleurotus columbinus, and Pleurotus sajor-caju. Male Wistar albino rats were assigned to thirteen groups and Immunosuppression was induced by oral administration of dexamethasone (0.1 mg/kg), followed by oral administration of the mushroom extracts at low (200 mg/kg) and high (400 mg/kg) doses. A positive control group received the immune stimulant Echinacea extract Immulant® at (30 mg/kg), while the negative control group received only saline. From each animal, in each group, blood samples were collected after 15 days for complete blood counts and for measurement of immunologic parameters, including lysozyme activity, nitric oxide (NO) production and serum cytokines including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ) and interleukin 1 beta (IL-1β) levels. Results have shown that white blood cells (WBCs) and lymphocytic counts were significantly boosted by high doses of each of the five mushroom extracts (207-289% increase for WBC and 153-175% for lymphocytes) with a significant increase in lysozyme activity (110-136% increase), NO concentration (159-232% increase) and cytokines as compared to the negative control group. Histopathological examination of the rats' spleen and thymus tissues has shown marked lymphocytic proliferation that was more obvious at the higher doses. In conclusion, our results showed that the five edible mushroom extracts revealed significant immunostimulatory effects preclinically particularly, at the higher doses (400 mg/kg) which can be considered the effective dose.

Figure 1

Histopathological Findings of the spleen. Group 1 (A) for normal control group showing normal white pulp (WP) and red pulp (RP), Group 2 (B) for dexamethasone control group. Group 3 (C) for Echinacea extract treated group. Pleurotus ostreatus group for low dose (200 mg/Kg) Group 4 (D) and high dose (400 mg/Kg) Group 5 (E). Pleurotus columbinus low dose (200 mg/Kg) Group 6 (F) and high dose (400 mg/Kg) Group 7 (G). Pleurotus sajor-caju for low dose (200 mg/Kg) Group 8 (H) and high dose (400 mg/Kg) Group 9 (I). Lentinula edodes low dose (200 mg/Kg) Group 10 (J) and high dose (400 mg/Kg) Group 11 (K). Agaricus bisporus low dose (200 mg/Kg) Group 12 (L) and high dose (400 mg/Kg) Group 13 (M) (H& E).

Figure 2

Histopathological findings of the thymus. Group 1 (A) for normal control group showed normal cortex (C) and medulla (M), Group 2 (B) for dexamethasone control group. Group 3 (C) for Echinacea extract treated group. Pleurotus ostreatus group for low dose (200 mg/Kg) Group 4 (D) and high dose (400 mg/Kg) Group 5 (E). Pleurotus columbinus low dose (200 mg/Kg) Group 6 (F) and high dose (400 mg/Kg) Group 7 (G). Pleurotus sajor-caju for low dose (200 mg/Kg) Group 8 (H) and high dose (400 mg/Kg) Group 9 (I). Lentinula edodes low dose (200 mg/Kg) Group 10 (J) and high dose Group (400 mg/Kg) 11 (K). Agaricus bisporus low dose (200 mg/Kg) Group 12 (L) and high dose (400 mg/Kg) Group 13 (M). (H&E).