L. casei improves resistance against pneumococci in malnourished mice.Mechanisms involved

VILLENA JULIO; HARO CECILIA; RACEDO SILVIA; ALVAREZ SUSANA

Córdoba. Argentina

Congreso; VII Cong. Latinoamericano de Inmunología; 2005

Sociedad Latinoamericana de Inmunología

Feeding with Lactobacillus casei (Lc) improves pneumococci clearance in malnourished mice (MM) lungs. In order to elucidate the possible mechanisms involved in that effect, innate and humoral immune responses and cytokines profiles were studied. Weaned mice were fed a protein-free diet for 21 days to obtain MM. MM were fed a balanced diet for 7 days without (BM) or with Lc (LcM) supplementation. MM and well-nourished mice (WM) were used as controls. Mice were challenged intranasally with pneumococci and sacrificed on 1,5,10 and 15 days post-infection (dpi). Bronchoalveolar lavages were used to determine leukocytes, albumin (Ab), lactate dehydrogenase (LDH), anti-pneumococcal IgG and IgA, TNFa, IL1b, IL4, IL6 and IL10 concentrations. Histological examination and IgA+ cells (IgA+c) in lungs were also assessed. Lung injury was significantly higher in MM than WM, as seen by Ab, LDH and histological examination (1dpi-LDH: WM=20,5±4,2 MM=61,4±2,3U/l). MM had lower levels of cytokines, IgG, IgA and IgA+c than WM (1dpi-TNFa: WM=2002±198 MM=1656±123pg/ml; 10dpi-IL4: WM=213±23 MM=103±16pg/ml; 10dpi-IgA: WM=2,6±0,9 MM=1,3±1,2mg/L; 15dpi-IgA+c: WM=22,3±3,2 MM=13,1±2,8cells/field). LcM group showed reduced lung injuries (1dpi-LDH: 21,3±3,2U/l) and normal cytokine levels (1dpi-TNFa: 1983±231; 10dpi-IL4: 236±22pg/ml). IgA and IgA+c were higher in LcM compared with WM (10dpi-IgA: 4,69±0,93mg/L; 15dpi-IgA+c: 37,4±5,3cells/field). Parameters studied were higher in BM compared with MM, but did not reach levels of WM. This data suggests that Lc improves the immune response against pneumococci in malnourished mice by inducing different cytokine profiles