Fig. 2

Osteopontin dampens inflammation and tissue injury in LPS-induced acute lung injury. To induce airway inflammation, LPS (2 µg/g derived from E. coli) was instilled intranasally in WT and OPN^−/− mice. The mice were killed 8 h after the LPS challenge, and BALF, lung tissue, and plasma were collected. a The levels of histone H3 in BALF of WT and OPN^−/− mice after LPS exposure were examined using western blot analysis. The graphical representation of pixel intensity (right panel) indicated significant differences between WT and OPN^−/− mice. n = 6 per group; *P = 0.0411 between groups. b The concentrations of OPN in the bronchoalveolar lavage fluid (BALF) of WT mice 8 h after instillation of LPS (n = 6 per group; **P = 0.0043 between groups). c The dry/wet ratios of lungs were determined to compare pulmonary edema in WT and OPN^−/− mice. n = 7 in WT group and n = 4 in OPN^−/− group; *P = 0.0121 between groups. d, e LDH and albumin levels in BALF of WT and OPN^−/− mice were determined in order to assess lung damage. n = 6 per group; *P = 0.0152, **P = 0.0082 between groups. OPN^−/− mice had higher levels of LDH and albumin, reflecting more damage to the lungs. f Blind evaluation of the tissue injury was performed on hematoxylin & eosin-stained slides using a lung injury scoring system, showing increased lung injury in OPN^−/− mice. n = 6 per group; **P = 0.0022 between groups. g Representative hematoxylin & eosin and scanning electron microscopy images of lung sections of LPS-induced ALI, showing differences in lung damage between WT and OPN^−/− mice. h Heat map representation of inflammatory mediators measured in the BALF of WT and OPN^−/− mice after LPS challenge, using multiplex bead assay. i Bar graph of some selected key pro-inflammatory mediators. n = 6 per LPS group, n = 3 per control group