Early transcriptional responses of internalization defective Brucella abortus mutants in professional phagocytes, RAW 264.7

Abstract

BackgroundBrucella abortus is an intracellular zoonotic pathogen which causes undulant fever, endocarditis, arthritis and osteomyelitis in human and abortion and infertility in cattle. This bacterium is able to invade and replicate in host macrophage instead of getting removed by this defense mechanism. Therefore, understanding the interaction between virulence of the bacteria and the host cell is important to control brucellosis. Previously, we generated internalization defective mutants and analyzed the envelope proteins. The present study was undertaken to evaluate the changes in early transcriptional responses between wild type and internalization defective mutants infected mouse macrophage, RAW 264.7.ResultsBoth of the wild type and mutant infected macrophages showed increased expression levels in proinflammatory cytokines, chemokines, apoptosis and G-protein coupled receptors (Gpr84, Gpr109a and Adora2b) while the genes related with small GTPase which mediate intracellular trafficking was decreased. Moreover, cytohesin 1 interacting protein (Cytip) and genes related to ubiquitination (Arrdc3 and Fbxo21) were down-regulated, suggesting the survival strategy of this bacterium. However, we could not detect any significant changes in the mutant infected groups compared to the wild type infected group.ConclusionsIn summary, it was very difficult to clarify the alterations in host cellular transcription in response to infection with internalization defective mutants. However, we found several novel gene changes related to the GPCR system, ubiquitin-proteosome system, and growth arrest and DNA damages in response to B. abortus infection. These findings may contribute to a better understanding of the molecular mechanisms underlying host-pathogen interactions and need to be studied further.

Erythritol Availability in Bovine, Murine and Human Models Highlights a Potential Role for the Host Aldose Reductase during Brucella Infection

“…Indeed, because erythritol is present in comparatively large amounts in the placenta and genital tissues of ruminants and swine and because Brucella is found inside trophoblastic cells of ruminants and uses erythritol very efficiently, it has been widely assumed that trophoblasts produce erythritol. However, most evidence is limited to extracts of fetal allantoic and amniotic fluids, cotyledons, whole placenta, seminal vesicles and testis (Smith et al, 1962; Williams et al, 1962; Clark et al, 1967), and to the best of our knowledge, only one work has reported the presence of erythritol in trophoblasts of bovine origin (Enright and Samartino, 1994). Our work confirms this pattern and provides the first experimental data that support the presence of erythritol in human and murine trophoblastic cells.…”

“…Present in substantial amounts in fetal fluids, placenta, seminal vesicles and semen of several ungulate species (Smith et al, 1962; Keppie et al, 1965; Clark et al, 1967), this four carbon polyol promotes Brucella growth at low concentrations and is also a preferred carbon source (McCullough and Beal, 1951; Smith et al, 1962). Bovine fetal tissues that were obtained from 6 to 7 months pregnant cattle (the time after which Brucella abortion often occurs) (Williams et al, 1962) and chorioallantoic membrane explants (Enright and Samartino, 1994) have been described to produce high amounts of erythritol. Nevertheless, other observations are not consistent with erythritol being the only factor in Brucella localization in vivo.…”

Mitochondrial fragmentation affects neither the sensitivity to TNFα-induced apoptosis of Brucella-infected cells nor the intracellular replication of the bacteria

“…Indeed, Brucella is known to prevent the activation of IFNγ or FasL-induced apoptosis both in infected and non-infected monocytes, suggesting the involvement of soluble factors 49 . Additionally, Brucella- infected cells are known to secrete TNFα 50 , 56 , 58 , 59 , 80 – 82 , a cytokine with a known dual effect. On the one hand, TNFα induces pro-survival NF-κB signalling and, on the other hand, in cases of excessive stimulation, it promotes apoptosis 83 .…”

Global gene-expression profiles of intracellular survival of the BruAb2_1031 gene mutated Brucella abortus in professional phagocytes, RAW 264.7 cells

“…Therefore, characterization of the host macrophage- Brucella interaction is very important to identify the pathogenicity and infection mechanism of Brucella [ 22 ]. Microarray is a powerful approach that enables understanding the host responses at the global gene transcription level, thereby providing a plethora of information regarding the interactions associated with cell responses to antigens at the molecular level [ 15 , 23 ]. In this study, microarray analysis was used to compare the responses between macrophages infected with B. abortus wild-type and B. abortus mutant strains, to demonstrate the Brucella genes that affect the interactions between host immune cells and the bacteria.…”