In vitro protective efficacy of Lithium chloride against Mycoplasma hyopneumoniae infection

Mycoplasma hyopneumoniae (M. hyopneumoniae) infection affects the swine industry. Lithium chloride (LiCl), is a drug used to treat bipolar disorder and has also shown activity against bacterial and viral infections. Herein, we evaluated the antibacterial activity of LiCl on PK-15 cells infected with M. hyopneumoniae. Incubation of LiCI (40 mM) with cells for 24 h, did not significantly affect the cell viability. The qRT-PCR showed similar to 80% reduction in M. hyopneumoniae genome when LiCl added post-infection. A direct effect of LiCl on bacteria was also observed. However, treatment of cells with LiCl prior infection, does not protect against the infection. Antibacterial activity of LiCl was further confirmed by IFA, which demonstrated a reduction in the bacterial protein. With 40 mM LiCl, the apoptotic cell death, production of nitric oxide and superoxide anion induced by M. hyopneumoniae, were prevented by similar to 80%, 60% and 58% respectively. Moreover, caspase-3 activity was also reduced (82%) in cells treated with 40 mM LiCl. LiCl showed activity against various strains of M. hyopneumoniae examined in our study. Collectively, our data showed that LiCl inhibited the infection of M. hyopneumoniae through anti-apoptotic mechanism. (C) 2016 Elsevier Ltd. All rights reserved.