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Direct and microsomal activated aflatoxin B1 exposure and its effects on turkey peritoneal macrophage functions in
D L Neldon-Ortiz1, M A Qureshi
1Department of Poultry Science, North Carolina State University, Raleigh 27695-7608.
Abstract:
Sephadex-elicited turkey peritoneal exudate cells were used to establish adherent macrophage monolayers on glass coverslips in order to determine the effects of aflatoxin B1 (AFB1) on macrophages. Adherent macrophage monolayers were exposed to increasing doses of AFB1 (5, 10, 20, and 40 micrograms), either directly, or to 0.01, 0.1, 0.5, 1, and 5 micrograms of AFB1 in the presence of a chicken microsomal mixed function oxidase system (MFO). Cultures were incubated with the appropriate treatments for 1 hr, then washed and allowed to recover in fresh growth medium for 2 hr. Direct exposure of macrophages to AFB1 had no detrimental effect on macrophage adherence, percentage damaged, percentage phagocytic, and the number of antibody-coated or uncoated sheep red blood cells internalized per phagocytic macrophage when compared with the sham or solvent treated cultures. However, the addition of MFOs to the cultures treated with much lower doses of AFB1 resulted in significantly higher morphological alterations along with a reduction in cell adherence and phagocytic potential. Addition of piperonyl butoxide (a P450 inhibitor) abrogated AFB1-MFO induced alterations. Data collected in this study suggest that turkey macrophages are resistant to the direct exposure of AFB1 and that AFB1 induced alterations in macrophage effector functions are due to metabolic activation of AFB1 by MFOs.
Insights
Turkey macrophages resist direct aflatoxin B1 (AFB1) exposure. However, metabolic activation of AFB1 by mixed function oxidases (MFOs) significantly impairs macrophage functions, indicating AFB1
Area of Science:
- Immunology
- Toxicology
- Cell Biology
Background:
- Aflatoxin B1 (AFB1) is a mycotoxin with potential adverse effects on animal health.
- Macrophages are critical immune cells involved in pathogen clearance and host defense.
- Understanding AFB1's impact on macrophage function is crucial for assessing its toxicological risks.
Purpose of the Study:
- To investigate the direct effects of AFB1 on turkey macrophage functions.
- To determine if metabolic activation of AFB1 by mixed function oxidases (MFOs) alters its toxicity to macrophages.
Main Methods:
- Established adherent turkey macrophage monolayers from peritoneal exudate cells.
- Exposed macrophages directly to varying doses of AFB1.
- Exposed macrophages to AFB1 in the presence of a chicken microsomal MFO system.
- Assessed macrophage adherence, cell damage, phagocytic activity, and AFB1-induced alterations.
- Utilized piperonyl butoxide (a P450 inhibitor) to investigate the role of MFOs.
Main Results:
- Direct exposure to AFB1 did not negatively impact macrophage adherence, damage, or phagocytosis.
- Co-incubation with MFOs and low doses of AFB1 caused significant morphological changes, reduced adherence, and impaired phagocytic potential.
- Piperonyl butoxide blocked the AFB1-MFO induced alterations, confirming the role of metabolic activation.
Conclusions:
- Turkey macrophages exhibit resistance to the direct cytotoxic effects of AFB1.
- Metabolic activation of AFB1 by MFOs is responsible for its detrimental effects on macrophage effector functions.
- These findings highlight the importance of metabolic activation in AFB1 toxicity to avian immune cells.