It has been demonstrated that tranexamic acid (TXA), a synthetic derivative of lysine,
alleviates lung damage in a trauma-hemorrhagic shock (T/HS) model. Nevertheless, the
mechanism of TXA against acute lung injury (ALI) has not deeply elaborated. In this study,
we generated a T/HS rat model based on previous research, and TXA (50 mg/kg and 100 mg/kg)
was intravenously injected into these rats prior to or post T/HS. The results revealed
that the decreased survival rate and impaired lung permeability of the rats caused by T/HS
were improved by TXA pretreatment or posttreatment. T/HS-triggered over-generation of
interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in bronchoalveolar fluid and
serum was inhibited by TXA, and the enzymatic activity of myeloperoxidase (MPO) in lung
tissues was suppressed by TXA as well. Furthermore, TXA treatment deactivated the poly
ADP-ribose polymerase-1 (PARP1)/nuclear factor κB (NF-κB) signaling pathway in the lungs
of T/HS rats, as evidenced by increased IκBα expression, and decreased cleaved PARP1,
p-p65 (Ser276), p-p65 (Ser529), p-IκBα (ser32/ser36), and intercellular adhesion
molecule-1. While the expression level of total p65 did not change after T/HS, its DNA
binding activity was strengthened. Both TXA pretreatment and posttreatment suppressed this
effect on the DNA binding activity of NF-κB. Taken together, our results reveal that
administration of TXA effectively relieves T/HS-induced ALI, at least in part, by
attenuating the abnormal pulmonary inflammation.