title: OMP31 ofBrucella melitensis16M impairs the apoptosis of macrophages triggered by TNF-α.
abstract: Outer membrane proteins (OMPs) of microorganisms play important roles in directly interacting with host cells.Brucellaspecies inhibit the apoptosis of host cells to benefit their own intracellular survival and replication. However, the association between OMP31 ofBrucellaand host cell apoptosis, and the underlying mechanism are unclear. In this study, anOMP31gene deletion mutant based onB. melitensis16M was constructed. Following the infection of RAW264.7 cells withB. melitensis16M or the mutant strain, colony formation, apoptosis, tumor necrosis factor (TNF)-α levels and the levels of key downstream factors of the apoptosis pathways triggered by TNF-α, namely caspase-3, -8 and -9, cytochromec, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were detected. The mutant strain was shown to have the same phenotype as the parent strain using traditional microbiological tests. However, the mutant strain had impaired intracellular survival, with higher levels of apoptosis and TNF-α expression in infected RAW164.7 macrophages than the parent strain. The downstream factors of apoptosis triggered by TNF-α, including increased caspase-8, -3 and -9, cytochromecand Bax, and decreased Bcl-2, indicated that the classical and mitochondrial cell death pathways were involved. It may be concluded that OMP31 fromBrucellainhibited apoptosis and benefitted the intracellular survival of this microorganism. Furthermore, TNF-α may have served as a switch triggering classical death and mitochondrial cell death pathways.
authors.affiliation: Department of Basic Medicine, School of Medicine, Pingdingshan University, Pingdingshan, Henan 467000, P.R. China.
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Geriatrics, Shihezi People's Hospital, Shihezi, Xinjiang 832000, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Basic Medicine, Shihezi University, Shihezi, Xinjiang 832003, P.R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Guo
authors.affiliation: Department of Basic Medicine, Shihezi University, Shihezi, Xinjiang 832003, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Basic Medicine, Shihezi University, Shihezi, Xinjiang 832003, P.R. China.
authors.forename: Wanjiang
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Basic Medicine, Shihezi University, Shihezi, Xinjiang 832003, P.R. China.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang 832003, P.R. China.
authors.forename: Chuangfu
authors.initials: C
authors.lastname: Chen
keywords: Brucella melitensis 16M; OMP31; apoptosis; tumor necrosis factor-α