Sea-cod oil supplementation alters the course of Streptococcus pneumoniae infection in BALB/c mice

The existing reports on the role of ω-3 polyunsaturated fatty acids (PUFA) in infectious diseases are contradictory. The present study was conducted to evaluate the effect of sea-cod oil on the course of respiratory tract infection by Streptococcus pneumoniae in BALB/c mice. Animals were given enteral sea-cod oil for a period of 30 and 60 days and challenged intra-tracheally with S. pneumoniae D39 serotype 2. The survival of animals and various inflammatory parameters, i.e. myeloperoxidase (MPO), malondialdehyde (MDA), nitric oxide (NO) and leukotriene B4 in the lung homogenates, were investigated. The inflammatory cytokines levels (IL-1β, TNF-α and IL-10) were also determined. Continuous sea-cod oil supplementation for 60 days significantly improved survival among the animals. A significant reduction in the bacterial load in the lungs of sea-cod oil-fed animals compared to the controls was observed. As the disease progressed, the reduced bacterial colonisation correlated well with the histopathological observation. This was accompanied by a decrease in the production of inflammatory mediators and cytokines in the lung homogenates. However, not even a minor difference was seen in animals given sea-cod oil supplementation for 30 days duration; therefore, long-term treatment was required to attain an effect. Sea-cod oil supplementation modulated the host immune response and, thus, protected the host from ensuing inflammatory damage due to S. pneumoniae-mediated infection.