Some nutritional components are able to modulate the inflammatory response and the immune response. They could be very useful in increasing the host resistance to infectious diseases, particularly in the P. aeruginosa pulmonary infection which is characterized by an excessive inflammatory response and the severity of which is associated with a Th2 type immune response. The first objective of this study was to test the anti-inflammatory effect of a diet enriched in n-3 polyunsaturated fatty acids (EPA/DHA) during an acute pulmonary infection with P. aeruginosa in mice deficient for the cftr gene. Because previous results suggested that female mice are more susceptible to infection than male mice, the benefits of this diet were analyzed according to the mice gender. The second objective was to study the effect of acidic oligosaccharides derived from citrus pectin (pAOS) during a chronic lung infection with P. aeruginosa. The hypothesis was that pAOS by promoting the balancing of the Th2 response towards a Th1 response could improve the prognosis of the infection. Their immunomodulatory effect was evaluated in two different murine genetic backgrounds: BALB/c and C57BL/6, known to develop respectively a Th2 and a Th1 immune response. These three studies are based on the endotracheal administration of a suspension of P. aeruginosa for the acute infection or P. aeruginosa embedded in agar beads for the chronic infection in mice fed a control diet or a specific diet for 6 weeks (cftr-/- mice) or 5 weeks (BALB/c and C57BL/6). The clinical parameters measured were survival and pulmonary bacterial clearance. Biological parameters for the inflammatory response were the polymorphonuclear cells and macrophages counting and pro- and anti-inflammatory cytokines assay in the bronchoalveolar lavage, and for the immune response the Th1 and Th2 cytokines assay, the expression of differentiation markers of Th1 and Th2 cells and M1 and M2 macrophages. BALB/c and C57BL/6 surviving at the first infection were reinfected and the pulmonary bacterial load was measured.
