Redundant effects of ketamine on the pathogenesis and severity of Brucella abortus infection

Tannic acid-mediated immune activation attenuates Brucella abortus infection in mice

Brucellosis is an emerging infectious disease affecting humans and animals. In this study, we investigated the in vitro and in vivo effects of tannic acid (TA) against Brucella abortus infection. After infection, F-actin polymerization and mitogen-activated protein kinases (MAPKs) (ERK 1/2 and p38α) phosphorylation were reduced in TA-treated cells compared with that in control cells. The mice were infected via an intraperitoneal route and were orally given TA or phosphate-buffered saline for 14 days. Spleen weights of the TA-treated and control mice were not different; however, splenic proliferation of B. abortus was significantly reduced in the TA-treated group. Immune response analysis showed that, compared with the control group, non-infected TA-treated mice displayed increased levels of interferon-γ (IFN-γ), monocyte chemoattractant protein-1 (MCP-1), and interleukin-10 at 3 days post-infection and a further increase in IFN-γ and MCP-1 at 14 days post-infection. In contrast, compared with the control group, infected TA-treated mice displayed elevated levels of IFN-γ at 3 days post-infection, which continued to increase at 14 days post-infection, as was also observed for tumor necrosis factor. Taken together, the results showing TA activation of cytokine production and inhibition of bacterial proliferation in the host highlight a potential use of TA treatment in the control of Brucella infection.

Inhibitory effect of red ginseng acidic polysaccharide from Korean red ginseng on phagocytic activity and intracellular replication of Brucella abortus in RAW 264.7 cells

Korean red ginseng (KRG) has long been used in traditional Korean and Oriental medicine. However, the anti-bacterial mechanism and therapeutic efficiency of KGR for intracellular Brucella infection are still unclear. In this study, the bactericidal activity of Korean red ginseng acidic polysaccharide (RGAP) on Brucella (B.) abortus and its cytotoxic effects on RAW 264.7 cells were evaluated. In addition, B. abortus internalization and intracellular replication in macrophages were investigated after RGAP treatment. RGAP-incubated cells displayed a marked reduction in the adherence, internalization and intracellular growth of B. abortus in macrophages. Furthermore, decreased F-actin fluorescence was observed relative to untreated B. abortus-infected cells. Western blot analysis of intracellular signaling proteins revealed reduced ERK, JNK and p38α phosphorylation levels in B. abortus-infected RGAP-treated cells compared to the control. Moreover, elevated co-localization of B. abortus-containing phagosomes with lysosome-associated membrane protein 1 (LAMP-1) were observed in RGAP-treated cells compared with the control. Overall, the results of this study suggest that RGAP can disrupt phagocytic activity of B. abortus via suppression of mitogen-activated protein kinases (MAPKs) signaling proteins ERK, JNK and p38 levels and inhibit intracellular replication of B. abortus by enhancing phagolysosome fusion, which may provide an alternative control of brucellosis.

The host immune enhancing agent Korean red ginseng oil successfully attenuates Brucella abortus infection in a murine model

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng Meyer (Araliaceae), is one of the most valuable traditional Chinese medicines and is used for the treatment of various human diseases. In this study, we elucidated the protective mechanism of the essential oil from Korean red ginseng (RGO) against Brucella infection.

MATERIALS AND METHODS

The effects of RGO on Brucella abortus viability, NO production, uptake and intracellular growth in macrophages were investigated. Mice were intraperitoneally infected with B. abortus and orally treated with RGO for 14 days. The weights and bacterial numbers from each spleen were monitored, and the sera were evaluated for cytokine production.

RESULTS

B. abortus viability was not affected, whereas NO production, internalization and intracellular replication were inhibited in RGO-treated macrophages. Bacterial adherence, F-actin polymerization and MAPK signaling protein phosphorylation (ERK1/2, JNK and p38α) were reduced and the co-localization of B. abortus-containing phagosomes with LAMP-1 was augmented in RGO-treated cells compared to untreated cells. RGO displayed protective effects against cell damage by inhibiting nitrite production during B. abortus infection in macrophages. Moreover, the spleen weight and bacterial burden were lower in the RGO-treated group than in the control group. The uninfected RGO-treated mice displayed increased TNF-α and IFN-γ production, whereas the B. abortus-infected RGO-treated mice showed reduced IL-10 production compared to the control.

CONCLUSION

RGO exhibits protective effects against B. abortus infection in vitro and in vivo, which emphasize the beneficial effects of RGO in the prevention and treatment of brucellosis.

Cervical Lymph Nodes as a Selective Niche for Brucella during Oral Infections

Cervical lymph nodes (CLN) are the first lymph nodes encountered by material taking the oral route. To study their role in orally acquired infections, we analyzed 307 patients of up to 14 years treated in the university clinic of Skopje, Macedonia, for brucellosis, a zoonotic bacterial disease frequently acquired by ingestion of contaminated dairy products. From these children, 36% had lymphadenopathy. Among orally infected children, lymphadenopathy with CLN being the only lymph nodes affected was significantly more frequent as compared to those infected by contact with animals (83% vs. 63%), suggesting a possible involvement of CLN during orally acquired human brucellosis. Using a murine model where bacteria are delivered into the oral cavity, we show that Brucella quickly and selectively colonize the CLN where they proliferate and persist over long periods of time for up to 50 days post-infection. A similar efficient though less specific drainage to CLN was found for Brucella, Salmonella typhimurium and fluorescent microspheres delivered by gavage, a pathway likely representing a mixed infection mode of intragastric and oral infection, suggesting a central pathway of drained material. Microspheres as well as bacteria drained to CLN predominately reside in cells expressing CD68 and no or low levels of CD11c. Even though no systemic response could be detected, Brucella induced a locally restricted inflammatory reaction with increased expression levels of interferon γ, interleukin (IL)-6, IL-12, granzyme B and a delayed induction of Nos2. Inflammation led to pronounced lymphadenopathy, infiltration of macrophages/monocytes expressing high levels of major histocompatibility complex II and to formation of epitheloid granulomas. Together, these results highlight the role of CLN in oral infections as both, an initial and efficient trap for bacterial invaders and as possible reservoir for chronic pathogens. They likewise cast a new light on the significance of oral routes for means of vaccination.