Effect of dietary alpha-linolenic acid on endotoxin-induced production of tumor necrosis factor by peritoneal macrophages in horses.

The research article discusses a study that explored the impact of dietary alpha-linolenic acid on the way horse’s peritoneal macrophages, a type of immune cell, produce tumor necrosis factor in response to endotoxin, a potentially harmful substance.

Objective of the Study

• The study was designed to investigate the influence of dietary supplements enriched with alpha-linolenic acid on the capability of equine peritoneal macrophages to generate tumor necrosis factor (TNF) in reaction to endotoxin.

Methodology

• Peritoneal macrophages were collected from six healthy adult horses both before and after the animals were fed a nutritionally balanced diet containing 8% linseed oil, a significant source of alpha-linolenic acid.
• The macrophages were then cultivated in a medium devoid of any additives (control), endotoxin ranging from 0.5 to 50 ng/ml, or a calcium ionophore, A23187.
• After incubating the macrophages for 6 and 24 hours, the macrophage supernatants (the fluids lying over solid particulates) were retrieved and stored at a temperature of -70 degrees Celsius.
• To estimate the TNF activity, a modified in vitro cytotoxicity bioassay was employed. The bioassay used the murine fibrosarcoma cell line, WEHI 164 clone 13.

Findings

• The study found TNF activity after 6 and 24 hours was higher in macrophages exposed to endotoxin than in control macrophages. In the case of macrophages grown in a medium that contained endotoxin, the endotoxin concentration or the duration of incubation did not affect TNF activity.
• Notably, when horses were given the alpha-linolenic acid-rich diet for 8 weeks, endotoxin-induced macrophage TNF production significantly reduced. This indicates alpha-linolenic acid may play a pivotal role in attenuating the immune response triggered by the presence of endotoxins.