Abstract
Aflatoxin B2 (AFB2) is a carcinogenic and immunotoxic metabolite produced by Aspergillus flavus growing on crops and food. The immune functions of rat macrophages when exposed to sub-cytotoxic concentrations of AFB2 which may make exposed people susceptible to Candida albicans infections, have been assessed. This level of AFB2 significantly prevents immune functions of macrophages by inhibiting nitric oxide (NO) production, mitochondrial membrane potential and intracellular killing of C.albicans by macrophages even in the presence of activating signal, interferon-γ. AFB2-induced prevention of increased membrane potential and intracellular killing of C.albicans by macrophages may be due to the prevention of iNOS (inducible nitric oxide synthetase) activity which results in the suppression of NO production. This study provides an important clue to the possibility that macrophages may give refuge to C.albicans for survival and dissemination and thus C.albicans is capable of inducing self-protective effect by the action of AFB2. The presence of AFB2 would thus help the macrophages to allow the C.albicans to replicate and persist, while being invisible to the immune system. This plausibility will give impetus to medicinal development.
Highlights
Aflatoxins are mycotoxins formed as metabolites by certain Aspergillus species
This paper looks into the effects of Aflatoxin B2 (AFB2) on phagocytosis and intracellular killing of Candida albicans by rat peritoneal macrophages
We report in this paper that the exposure of aflatoxinB2 to macrophages has remarkably interfered with nitric oxide production and mitochondrial events in these macrophages, as is true with several carcinogenic compounds, causing the prevention of intracellular killing of Candida albicans
Summary
Aflatoxins are mycotoxins formed as metabolites by certain Aspergillus species (A. Flavus, A. parasiticus, A. nomius and A. niger) in/on foods and feeds. Aflatoxicosis affects agriculture, food, animals subsisting on them and exposed humans to the extent of mortality. Of the four major aflatoxins (B1, B2, G1 & G2), infection by the aflatoxin B2(AFB2) variety has been characterized by reduction in overall growth, liver. The mechanism of action of aflatoxinB2 is well established but the immunosuppressive aspect of sub-cytotoxic concentration of AFB2 has not yet been detailed. This paper looks into the effects of AFB2 on phagocytosis and intracellular killing of Candida albicans by rat peritoneal macrophages. The response of macrophages to AFB2 may be implicated in the effects of AFB2 on nitric oxide (NO) production[7]. The present authors are interested in the effects of sub-cytotoxic concentrations of AFB2 on the immune functions of macrophages which make AFB2-exposed people susceptible to fungal infections
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