GroEL protein of the Leptospira spp. interacts with host proteins and induces cytokines secretion on macrophages.

BACKGROUND: Leptospirosis is a zoonotic disease caused by infection with spirochetes from Leptospira genus. It has been classified into at least 17 pathogenic species, with more than 250 serologic variants. This wide distribution may be a result of leptospiral ability to colonize the renal tubules of mammalian hosts, including humans, wildlife, and many domesticated animals. Previous studies showed that the expression of proteins belonging to the microbial heat shock protein (HSP) family is upregulated during infection and also during various stress stimuli. Several proteins of this family are known to have important roles in the infectious processes in other bacteria, but the role of HSPs in Leptospira spp. is poorly understood. In this study, we have evaluated the capacity of the protein GroEL, a member of HSP family, of interacting with host proteins and of stimulating the production of cytokines by macrophages. RESULTS: The binding experiments demonstrated that the recombinant GroEL protein showed interaction with several host components in a dose-dependent manner. It was also observed that GroEL is a surface protein, and it is secreted extracellularly. Moreover, two cytokines (tumor necrosis factor-α and interleukin-6) were produced when macrophages cells were stimulated with this protein. CONCLUSIONS: Our findings showed that GroEL protein may contribute to the adhesion of leptospires to host tissues and stimulate the production of proinflammatory cytokines during infection. These features might indicate an important role of GroEL in the pathogen-host interaction in the leptospirosis.

GroEL protein of the Leptospira spp. interacts with host proteins and induces cytokines secretion on macrophages

Background: Leptospirosis is a zoonotic disease caused by infection with spirochetes from Leptospira genus. It has been classified into at least 17 pathogenic species, with more than 250 serologic variants. This wide distribution may be a result of leptospiral ability to colonize the renal tubules of mammalian hosts, including humans, wildlife, and many domesticated animals. Previous studies showed that the expression of proteins belonging to the microbial heat shock protein (HSP) family is upregulated during infection and also during various stress stimuli. Several proteins of this family are known to have important roles in the infectious processes in other bacteria, but the role of HSPs in Leptospira spp. is poorly understood. In this study, we have evaluated the capacity of the protein GroEL, a member of HSP family, of interacting with host proteins and of stimulating the production of cytokines by macrophages. Results: The binding experiments demonstrated that the recombinant GroEL protein showed interaction with several host components in a dose-dependent manner. It was also observed that GroEL is a surface protein, and it is secreted extracellularly. Moreover, two cytokines (tumor necrosis factor-α and interleukin-6) were produced when macrophages cells were stimulated with this protein. Conclusions: Our findings showed that GroEL protein may contribute to the adhesion of leptospires to host tissues and stimulate the production of proinflammatory cytokines during infection. These features might indicate an important role of GroEL in the pathogen-host interaction in the leptospirosis.

Interaction and cellular uptake of surface-modified carbon dot nanoparticles by J774.1 macrophages.

Carbon dot (Cdot) nanoparticles are an emerging class of carbon nanomaterials with a promising potential for drug delivery and bio imaging applications. Although the interaction between Cdots and non-immune cell types has been well studied, Cdot interactions with macrophages have not been investigated. Exposure of Cdot nanoparticles to J774.1 cells, a murine macrophage cell line, resulted in minimal toxicity, where notable toxicity was only seen with Cdot concentrations higher than 0.5 mg/ml. Flow cytometric analysis revealed that Cdots prepared from citric acid were internalized at significantly higher levels by macrophages compared with those prepared from bamboo leaves. Interestingly, macrophages preferentially took up phenylboronic acid (PB)-modified nanoparticles. By fluorescence microscopy, strong blue light-specific punctate Cdot fluorescence resembling Cdot structures in the cytosolic space was mostly observed in J774.1 macrophages exposed to PB-modified nanoparticles and not unmodified Cdot nanoparticles. PB binds to sialic acid residues that are overexpressed on diseased cell surfaces. Our findings demonstrate that PB-conjugated Cdots can be taken up by macrophages with low toxicity and high efficiency. These modified Cdots can be used to deliver drugs to suppress or eliminate aberrant immune cells such as macrophages associated with tumors such as tumor-associated macrophages.

Immunostimulatory effect of dried bonito extract on mouse macrophage cell lines and mouse primary peritoneal macrophages.

Dried bonito is a preserved food used in Japan, which contains abundant flavor ingredients and functional substances. We focused on the immunostimulatory effect of dried bonito extract (DBE) on mouse macrophage-like J774.1 cells, RAW264.7 cells, and mouse primary peritoneal macrophages. DBE significantly stimulated the production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) by both J774.1 cells and peritoneal macrophages by enhancing the cytokine gene expression levels. In addition, DBE stimulated nitric oxide production by enhancing the expression of inducible nitric oxide synthase in RAW264.7 cells. DBE also increased the phagocytosis activity of J774.1 cells. Immunoblot analysis revealed that DBE has an immunostimulatory effect on macrophages through activation of mitogen-activated protein kinase and nuclear factor-κB cascades. TNF-α production enhanced by DBE was partially inhibited by treatment with TLR4 inhibitor TAK-242, whereas IL-6 production enhanced by DBE was almost inhibited. These results suggested that DBE is thought to strongly stimulate the TLR4 signaling pathway for macrophage activation, and its activation is also involved in other signaling. Finally, the phagocytosis activity of peritoneal macrophages from DBE-administered BALB/c mice increased significantly, suggesting that DBE has the potential to stimulate macrophage activity in vivo. In conclusion, these data indicated that DBE contributes to activating host defense against pathogens by activating innate immunity.

Zanthoxylum bungeanum pericarp extract prevents dextran sulfate sodium-induced experimental colitis in mice via the regulation of TLR4 and TLR4-related signaling pathways.

Zanthoxylum bungeanum, which belongs to the Zanthoxylum genus of the Rutaceae family, is now wildly distributed in most parts of China and some Southeast Asian countries. The pericarp of Zanthoxylum bungeanum has been known to exhibit antibacterial, anti-inflammatory and other important therapeutic activities. The purpose of this study was to investigate the effects and mechanisms of Zanthoxylum bungeanum pericarp extract (ZBE) on DSS-induced experimental colitis in mice. The results demonstrated that the major flavonoid composition of ZBE includes rutin (32.36%), quercetin (13.61%) and isoquercitrin (24.89%). ZBE alleviated DSS-induced body weight loss, colon length shortening and colonic pathological damage. Furthermore, ZBE inhibited the expression of TNF-α, IL-1ß and IL-12 via the regulation of TLR4 and TLR4-related pathways in DSS-induced experimental colitis in mice and LPS-triggered inflammation in J774.1 cells. Our findings suggest that ZBE is effective in ameliorating experimental colitis, and further investigation is necessary on the use of ZBE as a new dietary strategy to lower the risk of ulcerative colitis (UC).

Immunostimulatory effect of spinach aqueous extract on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages.

We herein report the immunostimulatory effect of spinach aqueous extract (SAE) on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages. SAE significantly enhanced the production of interleukin (IL)-6 and tumor necrosis factor-α by both J774.1 cells and peritoneal macrophages by enhancing the expression levels of these cytokine genes. In addition, the phagocytosis activity of J774.1 cells was facilitated by SAE. Immunoblot analysis revealed that SAE activates mitogen-activated protein kinase and nuclear factor-κB cascades. It was found that SAE activates macrophages through not only TLR4, but also other receptors. The production of IL-6 was significantly enhanced by peritoneal macrophages from SAE-administered BALB/c mice, suggesting that SAE has a potential to stimulate macrophage activity in vivo. Taken together, these data indicate that SAE would be a beneficial functional food with immunostimulatory effects on macrophages.

Immunostimulatory activity of snake fruit peel extract on murine macrophage-like J774.1 cells.

Snake fruit (Salacca edulis Reinw.) is a tropical fruit produced in Indonesia. Snake fruit peel is normally discarded as waste. In the present study, it was revealed that snake fruit peel has high bioactivities on stimulation of the immune system. Snake fruit peel extract (SFPE) was prepared by extracting snake fruit peel powder in water for 15 h at 4 °C. SFPE enhanced phagocytotic activity of murine macrophage-like J774.1 cells. Production of cytokine such as tumour necrosis factor (TNF)-α and interleukin (IL)-6 was also stimulated by SFPE. The gene expression levels for these cytokines were elevated. Immunoblot analysis revealed that SFPE enhanced not only nuclear factor (NF)-κB but also mitogen-activated protein kinases signalling cascades such as JNK and p38 in macrophage. Overall findings suggested that SFPE has a potential beneficial effect to promote our body health through the stimulation of macrophage.