Fig. 2

Oral supplementation with Trp, or dL.P. increases phagocytic activity and peroxynitrite production of alveolar macrophages under antibiotic treatment. C57BL/6 male mice received a combined intramuscular injection of antibiotics: ampicillin (1000 mg/l), vancomycin (500 mg/l), and metronidazole (1000 mg/l) at 100 μl/day for 6 days. Trp (250 mg per day) or dead L. plantarum (2 × 10⁸ CFU/ml) was given in drinking water for 6 days. a Antibiotic treatment for six days decreased P. aeruginosa killing activity of alveolar macrophage and oral feeding of trp, indole, or dead L. plantarum increased it. AMs were collected and resuspended in HBSS as 10⁶ cells/ml. After 5 min of pre-incubation, the cell suspension was incubated with P. aeruginosa (10⁸/ml). The cells were removed and P. aeruginosa in the supernatant was counted. Data are presented as mean ± SEM. b Antibiotic treatment for 6 days decreased AMs activity. Tryptophan feeding in mice receiving antibiotic treatment significantly increased the AMs activity. AMs were harvested from adult mice by bronchoalveolar lavage (BAL). Cells were then cultured in 96-well microtiter plates to remove nonadherent cells. Adherent monolayer cells were stimulated with 0.5 or 5 μg/ml of LPS (from Escherichia coli O26:B6 Sigma-Aldrich). Supernatants were assayed for TNF-α. Data are presented as mean ± SEM. c Intramuscular combined antibiotic was given to mice for 6 days and AMs were purified from BALF for peroxynitrite production assay. The collected AMs were cultured with phenol red containing 25 μM of 1,2,3-dihydrorhodamine. The cells were stimulated with E. coli LPS. Peroxynitrite was measured every 15 min for 75 min using excitation and emission wavelengths of 485 and 530 nm, respectively. Data are presented as mean ± SEM; PA, P. aeruginosa; *P < 0.05, **P < 0.01, ***P < 0.001