RESUMEN
OBJECTIVE: Fish-oil enriched diet has a protective effect on experimental animals infected intramuscularly with Klebsiella pneumoniae. It also has beneficial effect in several other diseases, including autoimmune disorders. The pathophysiological effects of dietary fish-oil have still not been revealed although it is expected to influence the immune response. We have previously shown that dietary fish-oil has beneficial effect in mice infected intramuscularly with Klebsiella pneumoniae. If the beneficial effect of dietary fish-oil is due to influence on the immune response it should be independent of the infection site. We therefore investigated whether dietary fish-oil has beneficial effect in intrapulmonary infection with Klebsiella pneumoniae as it has on intramuscular infection with the same bacteria. MATERIALS AND METHODS: Sixty NMRI mice were fed diets enriched with fish-oil (30 mice) or corn-oil (30 mice) for six weeks. The mice were then infected in the lungs with Klebsiella pneumoniae and the survival was monitored. The experiment was performed twice. The results were compared to our earlier results with intramuscular infections. RESULTS: The survival of the mice fed the fish-oil enriched diet and infected in the lungs with Klebsiella pneumoniae was significantly better compared to the survival of mice fed the corn-oil enriched diet in both experiments (p=0.0001 and p=0.0013). These results are similar to our earlier findings when the mice were infected intramuscularly. CONCLUSIONS: These results indicate that the beneficial effect of dietary fish-oil on infection is independent of the site of infection. These results are in accordance with the hypothesis that dietary fish-oil influences the immune response.
RESUMEN
OBJECTIVE: Dietary fish-oil has beneficial effect in infections and in autoimmune disorders. This effect is thought to be associated with alterations in the immune system. The Gram negative organism Klebsiella pneumoniae has been used as an infective agent in most studies investigating the effect of dietary fish-oil on infection. The immune response against Gram positive bacteria is somewhat different to the response to Gram negative oeganisms. Moreover, the Gram positive bacteria Streptococcus pneumoniae is a very common pathogen, particularly in children. To investigate whether dietary fish-oil has different effect in infections by Gram positive or Gram negative bacteria, we studied the survival of mice fed with fish-oil or corn-oil supplemented diets and infected in the lungs with either Klebsiella pneumoniae or Streptococcus pneumoniae. MATERIALS AND METHODS: 120 NMRI mice were divided into four groups and fed diets supplemented with fish-oil (two groups, 30 mice in each group) or corn-oil (two groups, 30 mice in each group). After six weeks, the mice were infected with Klebsiella pneumoniae (fish-oil group and corn-oil group) or with Streptococcus pneumoniae serotype 3 (fish-oil group and corn-oil group). The survival was monitored. The experiment was performed twice. RESULTS: The survival of the mice infected with Klebsiella pneumoniae was significantly better in the groups receiving the fish-oil enriched diet as compared to the groups fed the corn-oil enriched diet (p=0.0001 and 0.0013). There was no difference in the survival of mice infected with Streptococcus pneumoniae serotype 3, receiving the fish-oil or corn-oil enriched diets (p=0.74 and p=0.15). CONCLUSIONS: These results indicate that dietary fish-oil has beneficial effect on survival of mice after experimental infection with the Gram negative bacteria Klebsiella pneumoniae but not on experimental infections with the Gram positive bacteria Streptococcus pneumoniae serotype 3.
