Dietary supplementation with n3 polyunsaturated fatty acids ameliorates acute pneumonia induced by Klebsiella pneumoniae in BALB/c mice
Dietary supplementation with n3 polyunsaturated fatty acids ameliorates acute pneumonia induced by Klebsiella pneumoniae in BALB/c mice
Year: 2013
Authors: Sharma, S. Chibber, S. Mohan, H. Sharma, S.
Publication Name: Can. J. Microbiol.
Publication Details: dx.doi.org/10.1139/cjm-2012-0521
Abstract:
The immune benefits associated with the optimal intake of dietary fatty acids are widely known. The objective of the present investigation was to elucidate the role of n3 polyunsaturated fatty acids (n3 PUFA) food source on acute pneumonia induced by Klebsiella pneumoniae. Three different n3 PUFA preparations (cod liver oil, Maxigard, and flaxseed oil) were orally supplemented and infection was induced in different groups of experimental mice. Mice fed olive oil and normal saline served as oil and saline controls, respectively. After 2 weeks of fatty acid feeding, no effect on the establishment of infection was observed when acute pneumonia was induced in animals. On the other hand, 6 weeks of n3 PUFA administration was found to improve resistance in mice, as reduced lung bacterial load coupled with significant improvement in pathology was seen in infected mice. Alveolar macrophages collected from all 3 groups of mice fed n3 PUFA exhibited a significant decrease in the level of apoptosis following infection with K. pneumoniae and an enhanced in vitro phagocytic potential for the pathogen. Lower lung levels of nitric oxide, malondialdehyde, and lactate dehydrogenase were associated with a decrease in the severity of tissue damage. There was a significant increase in the lung levels of pro-inflammatory cytokines (tumor necrosis factor alpha (TNFa) and interleukin1 beta (IL1b)). No significant change was observed in the levels of interleukin10 (IL10). This study highlights that dietary n3 PUFA supplementation exerts an overall beneficial effect against acute experimental pneumonia. This mechanism is operative through upregulation of nonspecific and specific immune defenses of the host. (Authors abstract)
Respiratory tract infections continue to be a major cause of morbidity and mortality worldwide. Supplementation of diet with n3 PUFA has proven to be beneficial, mainly attributed to their antiinflammatory properties of n3 PUFA. The role of n3 PUFA supplementation in relation to infectious diseases is still controversial. The present study investigated and compared the effect of 3 commonly consumed preparations of n3 PUFA, cod liver oil, Maxigard, and flaxseed oil, on the establishment of acute pneumonia induced by Klebsiella pneumoniae in a mouse model. n3 PUFA supplementation did not show any change in the lung bacterial counts, corresponding pathology, or inflammatory parameters when acute pneumonia was induced with K. pneumoniae. On the other hand, 6 weeks of n3 PUFA feeding provided a distinct advantage to the host, as there was a significant decrease in lung bacterial burden coupled with significant improvement in lung pathology in infected mice. Severity of pneumonia was reduced in all the groups fed n3 PUFA. In the present study, there was no significant change in the lung levels of nitric oxide in the n3 PUFA fed and infected mice as compared with normal saline fed control group. There was an increase in the generation of lung MPO, indicating a high phagocyte infiltration, followed by significantly reduced levels of MDA and LDH enzyme. This could possibly account for the beneficial role of acute inflammatory response wherein the neutrophils played a significant role in reducing the severity of the infection following n3 PUFA supplementation. In the present study, significantly amplified phagocytic uptake and killing ability of alveolar macrophages was observed following n3 PUFA supplementation.
The present study highlights that dietary supplementation with all the 3 n3 PUFA preparations led to an increase in the host resistance against K. pneumonia mediated acute pneumonia. This beneficial effect was operative through the compartmentalized immune response in the lungs of animals, where alveolar macrophages played a key role in the host defense. It would also be interesting to observe the effect of n3 PUFA on other immune cell functions such as T helper type1 and 2 cells. This also forms the basis for future studies to elucidate the effect of dietary fatty acids on the respiratory tract infections by other pathogens.(Editirs comments)
