Immunomodulatory effect of aqueous extract of Termitomyces striatus mushroom on enterohemorrhagic Escherichia coli-infected mice

Abstract

Enterohemorrhagic Escherichia coli (EHEC) generates Shiga toxins that causes immunosuppression and diarrhea. Synthetic immunomodulatory drugs are associated with numerous severe effects, necessitating the need for substitute therapeutic agents. This study aimed to determine the immunomodulatory activity of aqueous extract of Termitomyces striatus in in mice infected with EHEC. Mice in the positive control, negative control and two extract-treated groups were administered orally with 200µL of 9×108 CFU/mL EHEC. From day 5, the positive control, negative control, and extract-treated mice were orally administered with levamisole (50mg/kg body weight (bw)), phosphate-buffered saline (vehicle), and aqueous extract of Termitomyces striatus (200 and 400mg/kg body weight), respectively. The control mice received the vehicle only. After the experiment, the mice were euthanized, blood was collected, and white blood cells (WBCs) and differentials analyzed using a hematological analyzer. Immunoglobulin G (IgG), interleukin-4 (IL-4) and interferon-gamma (INF-γ) levels were also quantified using enzyme-linked immunosorbent assays. The extract significantly reduced elevated levels of WBCs, neutrophils, monocytes, eosinophils and basophils, as well as significantly enhanced the levels of lymphocytes in EHEC-infected mice (p<0.05). Besides, the extract significantly lowered the levels of INF-γ while significantly increasing the levels of IL-4 and IgG in EHEC-infected mice. Flavonoids, alkaloids, saponins, steroids and phenolics are some of the phytochemicals that were detected in T. striatus. Together, these finding revealed that T. striatus extract modulated immune response in EHEC- challenged mice by lowering leucocyte counts and INF-γ, enhancing lymphocytes, IL-4 and IgG, suggesting that the extract could be developed as an immunomodulatory agent.