ABSTRACT
OBJECTIVE Leukotriene B4 (LTB4) biosynthesis and subsequently neutrophilic inflam?mation may provide a potential strategy for the treatment of acute lung injury (ALI) or idiopathic pulmonary fibrosis (IPF). To provide a potential strategy for the treatment of ALI or IPF, we identified potent inhibi?tors of Leukotriene A4 hydrolase (LTA4H), a key enzyme in the biosynthesis of LTB4. METHODS In this study, we identified two known histone deacetylase (HDAC) inhibitors, suberanilohydroxamic acid (SAHA) and its analogue 4-(dimethylamino)-N-〔7-(hydroxyamino)-7-oxoheptyl〕benzamide (M344), as effective inhibitors of LTA4H using enzymatic assay, thermofluor assay, and X- ray crystallographic investigation. We next tested the effect of SAHA and M344 on endogenous LTB4 biosynthesis in neutrophils by ELISA and neutrophil migration by transwell migration assay. A murine experimental model of ALI was induced by lipopolysaccharide(LPS) inhalation. Histopathological analysis of lung tissue using H&E staining revealed the serious pulmonary damage caused by LPS treatment and the effect of the SAHA. We next examined mRNA and protein levels of pro-inflammatory cytokines in lung tissue and bronchoalveolar lavage fluid using qRT- PCR and ELISA to further investigate the underlying mechanisms of anti-inflammatory activities by SAHA. We also investigated the effects of SAHA and M344 on a murine experimental model of bleomycin (BLM)-induced IPF model. RESULTS The results of enzymatic assay and X-ray crystallography showed that both SAHA and M344 bind to LTA4H, signif?icantly decrease LTB4 levels in neutrophil, and markedly diminish early neutrophilic inflammation in mouse models of ALI and IPF under a clinical safety dose. CONCLUSION Collectively, SAHA and M344 would provide promising agents with well-known clinical safety for potential treatment in patients with ALI and IPF via pharmacologically inhibiting LAT4H and blocking LTB4 biosynthesis.