title: Transcriptional regulator GntR of Brucella abortus regulates cytotoxicity, induces the secretion of inflammatory cytokines and affects expression of the type IV secretion system and quorum sensing system in macrophages.
abstract: The pathogenic mechanisms of Brucella are still poorly understood. GntR is a transcriptional regulator and plays an important role in the intracellular survival of Brucella. To investigate whether GntR is involved in the cytotoxicity of Brucella abortus (B. abortus), we created a 2308ΔgntR mutant of B. abortus 2308 (S2308). Lactate dehydrogenase (LDH) cytotoxicity assays using a murine macrophage cell line (RAW 264.7) show that high-dose infection with the parental strain produces a high level of cytotoxicity to macrophages, but the 2308ΔgntR mutant exhibits a very low level of cytotoxicity, indicating that mutation of GntR impairs the cytotoxicity of B. abortus to macrophages. After the macrophages are infected with 2308ΔgntR, the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) increase and are slightly higher than that for the S2308 infected group, indicating that the 2308ΔgntR mutant could induce the secretion of inflammatory cytokines. The virulence factor detection experiments indicate that genes involved in the type IV secretion system (T4SS) and quorum sensing system (QSS) are down-regulated in 2308ΔgntR. The lower levels of survival of 2308ΔgntR under various stress conditions and the increased sensitivity of 2308ΔgntR to polymyxin B suggest that GntR is a virulence factor and that deletion of gntR reduces of B. abortus to stress conditions. Taken together, our results demonstrate that GntR is involved in the cytotoxicity, virulence and intracellular survival of B. abortus during its infection.
authors.affiliation: School of Biotechnology and Food, Shangqiu Normal University, Shangqiu, 476000, Henan, People's Republic of China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Li
authors.affiliation: School of Biotechnology and Food, Shangqiu Normal University, Shangqiu, 476000, Henan, People's Republic of China.
authors.forename: Shuli
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China. allanzhh@sohu.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Biotechnology and Food, Shangqiu Normal University, Shangqiu, 476000, Henan, People's Republic of China.
authors.forename: Jinliang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Biotechnology and Food, Shangqiu Normal University, Shangqiu, 476000, Henan, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Xi
authors.affiliation: College of Biology, Agriculture and Forestry, Tongren University, Tongren, 554300, Guizhou, People's Republic of China.
authors.forename: Junbo
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Animal Science and Technology, Shihezi University, Shihezi, 832003, Xinjiang, People's Republic of China.
authors.forename: Chuangfu
authors.initials: C
authors.lastname: Chen
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002003:Brucella abortus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D016207:Cytokines / Q000378:metabolism; D005786:Gene Expression Regulation; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D009154:Mutation; D053038:Quorum Sensing; D000067996:RAW 264.7 Cells; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000069319:Type IV Secretion Systems / Q000378:metabolism; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D016207:Cytokines; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D000069319:Type IV Secretion Systems; D037521:Virulence Factors
keywords: 2308ΔgntR; Brucella; Cytotoxicity; Virulence