The underlying mechanisms by which eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affect host resistance to Pseudomonas aeruginosa are unclear. The aim of this study was to determine their role on the kinetic of pro- and antiinflammatory response in lung infection. Mice fed either a control diet or a diet enriched with EPA and DHA were infected intratracheally and we studied lung expression of proinflammatory markers [CXCL1, interleukin (IL)-6, tumor necrosis factor-alpha], antiinflammatory markers (IL-10, A20, and IkappaB alpha), and PPARalpha and PPARgamma. The inflammatory response was assessed using recruitment of neutrophils and macrophages into bronchoalveolar lavage fluid, bacterial clearance from the lung, pulmonary injury, and 7-d survival rate. Compared with the control group, EPA and DHA delayed the expression of proinflammatory markers during the first 2 h (P < 0.05), upregulated proinflammatory marker expression (P < 0.05), and induced overexpression of antiinflammatory markers at 8 h (P < 0.05), enhanced recruitment of neutrophils at 16 h (P < 0.05), and induced PPARalpha and PPARgamma overexpression at 4 and 8 h (P < 0.01), respectively. Pulmonary bacterial load decreased and pulmonary injury and mortality were reduced during the first 24 h (P < 0.05). In conclusion, EPA and DHA modulate the balance between pro- and antiinflammatory cytokines, alter the early response of the host to P. aeruginosa infection, and affect the early outcome of infection.

In insects, xenobiotic-metabolizing enzymes were demonstrated to regulate pheromones inactivation, clearing them from the olfactory periphery and keeping receptors ready for stimulation renewal. Here, we investigate whether similar processes could occur in mammals, focusing on the pheromonal communication between female rabbits and their newborns. Lactating rabbits emit in their milk a volatile aldehyde, 2-methylbut-2-enal, that elicits searching-grasping in neonates; called the mammary pheromone (MP), it is critical for pups which are constrained to find nipples within the 5 min of daily nursing. For newborns, it is thus essential to remain sensitive to this odorant during the whole nursing period to display several actions of sucking. Here, we show that the MP is enzymatically conjugated to glutathione in newborn olfactory epithelium (OE), in accordance with the high mRNA expression of glutathione transferases evidenced by quantitative reverse transcription-PCR. This activity in the nose is higher than in the liver and in OE of newborns compared with weanlings (no more responsive to the pheromone). Therefore, the results pinpoint the existence of a high level of MP-glutathione conjugation activity in the OE of young rabbits, especially in the developmental window where the perceptual sensitivity toward the MP is crucial for survival.

The aim of this study was to determine whether oral supplementation with EPA/DHA (10.5 and 5.1% of fat, respectively) could improve the outcome of pulmonary P. aeruginosa infection in cftr(-/-) mice compared with wild-type (Wt) mice similarly treated. Because gender could influence the susceptibility of cftr-deficient mice, results were analyzed by gender. Wt and (-/-) mice were randomized for 6 wk to consume a control or EPA/DHA diet, infected with endotracheal injection of 5 × 10(7) CFU/mouse of P. aeruginosa, and killed 24 h later. Cftr(-/-) mice were more susceptible to infection than were Wt mice; (-/-) males had more neutrophils (P < 0.01) and a higher keratinocyte-derived chemokine (KC) level (P < 0.05), and (-/-) females had greater lung injury and mortality (P < 0.05). Female (-/-) mice were more susceptible than (-/-) males with a higher mortality and lung injury (P < 0.05). The EPA/DHA diet reduced neutrophil numbers and KC and IL-6 levels (P < 0.05) in (-/-) males and reduced mortality rate (P < 0.001), lung permeability, and IL-6 level (P < 0.05) in (-/-) females compared with (-/-) mice fed the control diet. These results were associated with a reduction in the pulmonary bacterial load (P < 0.05), an increase in the EPA/DHA concentration in cell membranes of (-/-) males and females (P < 0.01), and an increased weight gain only in males compared with (-/-) mice fed the control diet (P < 0.01). In conclusion, EPA/DHA improves the host resistance of (-/-) mice, although the beneficial effect differed in males and females.