Bletinib ameliorates neutrophilic inflammation and lung injury by
inhibiting Src family kinase phosphorylation and activity
Abstract
BACKGROUND AND PURPOSE Neutrophil overactivation is crucial in the
pathogenesis of acute lung injury (ALI). Bletinib
(3,3′-dihydroxy-2′,6′-bis(p-hydroxybenzyl)-5-methoxybibenzyl), a natural
bibenzyl first extracted from Bletilla striata in 1983, has
anti-inflammatory, antibacterial, and antimitotic potential. In this
study, we evaluated the therapeutic effects of Bletinib in human
neutrophilic inflammation and lipopolysaccharide (LPS)-mediated ALI.
EXPERIMENTAL APPROACH We assessed integrin expression, superoxide anion
production, degranulation, neutrophil extracellular trap (NET)
formation, and adhesion in activated human neutrophils through flow
cytometry, spectrophotometry, and immunofluorescence microscopy.
Moreover, phosphorylation of Src family kinases (SFKs) and downstream
proteins was evaluated through immunoblotting. Finally, a murine
LPS-induced ALI model was used to investigate the potential therapeutic
effects of Bletinib treatment. KEY RESULTS In activated human
neutrophils, Bletinib reduced degranulation, respiratory burst, NET
formation, adhesion, migration, and integrin expression; suppressed the
enzymatic activity of SFKs, including Src, Lyn, Fgr, and Hck; and
inhibited the phosphorylation of SFKs as well as Vav and Bruton’s
tyrosine kinase (Btk). In our mice with ALI, the pulmonary sections
demonstrated considerable amelioration of prominent inflammatory
changes, such as haemorrhage, pulmonary oedema, and neutrophil
infiltration, after Bletinib treatment. CONCLUSION AND IMPLICATIONS This
is the first study to provide evidence that Bletinib regulates
neutrophilic inflammation by inhibiting the SFKs–Btk–Vav pathway and
that Bletinib ameliorates LPS-induced ALI in mice. Further biochemical
optimisation of Bletinib may be a promising strategy for the development
of novel therapeutics for inflammatory diseases.