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The effects of direct and microsomal activated aflatoxin B1 on chicken peritoneal macrophages in vitro
D L Neldon-Ortiz1, M A Qureshi
1Department of Poultry Science, North Carolina State University, Raleigh 27695-7608.
Abstract:
Sephadex-elicited peritoneal exudate cells were cultured on glass coverslips in order to determine the effects of aflatoxin B1 (AFB1) on chicken macrophages. Adherent macrophage monolayers were exposed for 1 h to 5, 10, and 20 micrograms ml-1 of AFB1, directly or to 0.01, 0.1, 0.5, 1, and 5 micrograms ml-1 of AFB1 in the presence of a chicken microsomal mixed function oxidase system (MFO). After exposure, the macrophage cultures were washed and allowed to recover for 2 h in fresh culture medium. Parameters measured at 2 h post recovery period were the substrate adherence potential, morphological alterations, phagocytic ability, and number of sheep red blood cells (SRBC) internalized per phagocytic macrophage. Direct in vitro exposure to AFB1 resulted in a dose-dependent decrease in macrophage adherence potential, and an increase in cell damage as determined by nuclear disintegration and cytoplasmic blebbing, but no detrimental effects were observed on percent phagocytic cells or the number of internalized SRBC. However, significant reductions in adherence potential, increased morphological alterations, and reduced phagocytosis and internalization of SRBC were observed when MFOs were added to cultures treated with much lower doses of AFB1. Addition of piperonyl butoxide (a P-450 inhibitor) abrogated AFB1-MFO induced alterations. This study suggests that microsomal activated AFB1 causes significant alterations in chicken macrophage functions.
Insights
Aflatoxin B1 (AFB1) directly harms chicken macrophages, reducing adherence. However, when metabolized by mixed function oxidases (MFOs), AFB1 causes more severe damage, impairing macrophage function.
Area of Science:
- Immunology
- Toxicology
- Cell Biology
Background:
- Macrophages are crucial immune cells involved in pathogen clearance.
- Aflatoxin B1 (AFB1) is a mycotoxin with known toxic effects.
- Understanding AFB1's impact on avian immune cells is important for food safety and animal health.
Purpose of the Study:
- To investigate the effects of aflatoxin B1 (AFB1) on chicken macrophage functions.
- To compare the toxicity of direct AFB1 exposure versus AFB1 activated by a microsomal mixed function oxidase (MFO) system.
- To assess AFB1's impact on macrophage adherence, morphology, and phagocytic capacity.
Main Methods:
- Chicken peritoneal exudate cells were cultured to form macrophage monolayers.
- Macrophages were exposed to varying concentrations of AFB1 directly or in the presence of a chicken MFO system.
- Post-exposure, macrophage adherence, morphology, and phagocytosis of sheep red blood cells (SRBC) were evaluated.
Main Results:
- Direct AFB1 exposure decreased macrophage adherence and increased cell damage but did not affect phagocytosis.
- AFB1 activated by MFOs significantly reduced adherence, increased morphological alterations, and impaired phagocytosis of SRBC at lower doses.
- Piperonyl butoxide, a P-450 inhibitor, blocked the detrimental effects of AFB1-MFO exposure.
Conclusions:
- Microsomal activation of AFB1 leads to significant functional impairment of chicken macrophages.
- Metabolic activation is critical in determining the toxic potential of AFB1 on avian immune cells.
- These findings highlight the importance of AFB1 metabolism in its immunotoxicity.