• BMB Reports
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• v.53 no.11
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• pp.588-593
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• 2020

The accumulation of triglycerides (TGs) in macrophages induces cell death, a risk factor in the pathogenesis of atherosclerosis. We had previously reported that TG-induced macrophage death is triggered by caspase-1 and -2, therefore we investigated the mechanism underlying this phenomenon. We found that potassium efflux is increased in TG-treated THP-1 macrophages and that the inhibition of potassium efflux blocks TG-induced cell death as well as caspase-1 and -2 activation. Furthermore, reducing ATP concentration (known to induce potassium efflux), restored cell viability and caspase-1 and -2 activity. The activation of pannexin-1 (a channel that releases ATP), was increased after TG treatment in THP-1 macrophages. Inhibition of pannexin-1 activity using its inhibitor, probenecid, recovered cell viability and blocked the activation of caspase-1 and -2 in TG-treated macrophages. These results suggest that TG-induced THP-1 macrophage cell death is induced via pannexin-1 activation, which increases extracellular ATP, leading to an increase in potassium efflux.

• Korean Journal of Pharmacognosy
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• v.43 no.2
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• pp.157-162
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• 2012

In order to investigate the immunostimulating effect of mycelia extract of Phellinus linteus (PLM) on human monocyte THP-1 and rat peritoneal macrophage cell, we examined measuring cytokine secretion (IL-6 and TNF-${\alpha}$). The production of IL-6 and TNF-a in human monocyte THP-1 was slight increased dose-dependently when the cells were challenged with PLM for 72 hrs. It was also observed that the treatment of PLM with LPS augmented the production of IL-6 and TNF-a in human monocyte THP-1. It was also observed that the treatment of PLM with LPS augmented the production of IL-6 and TNF-${\alpha}$ in human monocyte THP-1. The production of IL-6 and TNF-${\alpha}$ in rat peritoneal macrophage was significantly enhanced when the cells were treated PLM with LPS for 72 hrs. Moreover, the proliferation rate of rat spleen cells was increased in a dose dependent manner as the cells were treated with PLM and Concanavalin A.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.3
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• pp.245-252
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• 2020

Macrophage cell death contributes to the formation of plaque, leading to the development of atherosclerosis. The accumulation of triglyceride (TG) is also associated with the pathogenesis of atherosclerosis. A previous study reported that TG induces the cell death of macrophages. This study examined whether the cytoplasmic release of cathepsin B from lysosome is associated with the TG-induced cell death of macrophage. The release of cathepsin B was increased in the TG-treated THP-1 macrophages, but the TG treatment did not affect cathepsin B expression. Furthermore, the inhibition of cathepsin B by its inhibitor, CA-074 Me, partially inhibited the TG-induced cell death of macrophage. TG-triggered macrophage cell death is mediated by the activation of caspase-1, -2, and apoptotic caspases. Therefore, this study investigated whether cathepsin B is implicated in the activation of these caspases. The inhibition of cathepsin B blocked the activation of caspase-7, -8, and -1 but did not affect the activity of caspase-3, -9, and -2. Overall, these results suggest that TG-induced cytoplasmic cathepsin B causes THP-1 macrophage cell death by activating caspase-1, leading to subsequent activation of the extrinsic apoptotic pathway.

• Biomedical Science Letters
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• v.22 no.4
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• pp.220-226
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• 2016

Hypertriglyceridemia induces atherosclerosis and accordingly is a major causative factor in cardiovascular diseases. Macrophages that develop into foam cells are a crucial component in the development of atherosclerosis. Monocytes can be differentiated into M1 or M2 macrophages. M1 macrophages promote inflammatory responses, whereas M2 macrophages exhibit anti-inflammatory activity. Recently, we found that triglyceride (TG)-treated THP-1 monocytes express a variety of macrophage-specific surface markers, indicating that TG treatment could trigger the differentiation of monocytes into macrophages. In this study, we investigated whether TG-induced macrophages express the M1 or the M2 macrophage phenotype. THP-1 cells were treated with various concentrations of TG for different times and the expression of M1- and M2-specific markers was evaluated by RT-PCR. We found increased expression of M1 markers (CD40, CD80, and CD86) in TG-treated THP-1 cells in a TG dose- and time-dependent manner. The expression of M2 markers (CD163, CD200R, and CD206) showed variable responses to TG treatment. Taken together, our results indicate that TG treatment triggers the differentiation of monocytes into M1 macrophages, rather than into M2 macrophages, suggesting that TG contributes to pro-inflammatory responses.

• BMB Reports
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• v.50 no.10
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• pp.510-515
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• 2017

Triglyceride (TG) accumulation causes macrophage cell death, which affects the development of atherosclerosis. Here, we examined whether caspase-2 is implicated in TG-induced macrophage cell death. We found that caspase-2 activity is increased in TG-treated THP-1 macrophages, and that inhibition of caspase-2 activity drastically inhibits TG-induced cell death. We previously reported that TG-induced macrophage cell death is triggered by caspase-1, and thus investigated the relationship between caspase-2 and caspase-1 in TG-induced macrophage cell death. Inhibition of caspase-2 activity decreased caspase-1 activity in TG-treated macrophages. However, caspase-1 inhibition did not affect caspase-2 activity, suggesting that caspase-2 is upstream of caspase-1. Furthermore, we found that TG induces activation of caspase-3, -7, -8, and -9, as well as cleavage of PARP. Inhibition of caspase-2 and -1 decreased TG-induced caspase-3, -7, -8, and -9 activation and PARP cleavage. Taken together, these results suggest that TG-induced macrophage cell death is mediated via the caspase-2/caspase-1/apoptotic caspases/PARP pathways.

• Journal of Microbiology and Biotechnology
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• v.28 no.10
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• pp.1736-1748
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• 2018

Brucella abortus can survive and replicate within host macrophages, and great efforts have been made to demonstrate the genes involved in pathogenicity, such as internalization, in Brucella research. Here, intracellular responses were compared between THP-1 macrophage cells stimulated with B. abortus wild-type and four mutants (C1, C10, C27, and C32) using microarray to demonstrate the role of genes related to intracellular survival and replication. These mutants were generated by deleting genes encoding BAB_RS13225 (4-hydrobenzoate 3-monooxygenase, PHBH), BAB_RS00455 (heme exporter protein cytochrome C, CcmC), BAB_RS03675 (exopolyphosphatase, PPX), and BAB_RS13225 (peptidase M24). The results showed that mutants C1 and C10 induced significant suppression of survival levels and cytokine expression relative to wild-type in the THP-1 macrophage cells. These findings suggest that the BAB_RS13225 and BAB_RS00455 genes play important roles in survival within human macrophages. Conversely, mutants C27 and C32 induced significantly higher survival level than wild-type in the cells inhibiting cellular signal transduction. It is assumed that the BAB_RS03675 and BAB_RS13225 genes play a role in cellular resistance to B. abortus. Therefore, the disrupted genes are involved in B. abortus intracellular growth, and especially in its survival, and they could be effective targets for understanding the intracellular bacterium, B. abortus.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.193-198
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• 2005

Background: Protease-activated receptor 2 (PAR2) belongs to a family of G protein coupled receptors activated by proteolytic cleavage. Trypsin-like serine proteases interact with PAR2 expressed by a variety of tissues and immune cells. The aim of our study was to investigate whether PAR2 stimulation can lead to the activation of human mac rophages. Methods: PAR2-mediated proliferation of human macrophage cell line THP-1 was measured with MTT assay. We also examined the extracellular regulated kinase (ERK) phosphorylation and cytokine production induced by trypsin and PAR2-agonist using western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Results: Treatment of trypsin or PAR2-activating peptide increased cell proliferation in a dose-dependent manner, and induced the activation of ERK1/2 in THP-1 cells. In addition, trypsin-induced cell proliferation was inhibited by pretreatment of an ERK inhibitor (pD98059) or trypsin inhibitor (SBTI). Moreover, PAR2 activation by trypsin increased the secretion of TNF-${\alpha}$ in THP-1 cells. Conclusion: There results suggest that P AR2 activation by trypsin-like serine proteases can induce cell proliferation through the activation of ERK in human macrophage and that PAR2 may playa crucial role in the cell proliferation and cytokine secretion induced by trypsin-like serine proteases.

• IMMUNE NETWORK
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• v.10 no.5
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• pp.173-180
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• 2010

Background: APRIL, originally known as a cytokine involved in B cell survival, is now known to regulate the inflammatory activation of macrophages. Although the signal initiated from APRIL has been demonstrated, its role in cellular activation is still not clear due to the presence of BAFF, a closely related member of TNF superfamily, which share same receptors (TACI and BCMA) with APRIL. Methods: Through transfection of siRNA, BAFF-deficient THP-1 cells (human macrophage-like cells) were generated and APRIL-mediated inflammatory activities were tested. The expression patterns of APRIL were also tested in vivo. Results: BAFF-deficient THP-1 cells responded to APRIL-stimulating agents such as monoclonal antibody against APRIL and soluble form of TACI or BCMA. Furthermore, co-incubation of the siBAFF-deficient THP-1 cells with a human B cell line (Ramos) resulted in an activation of THP-1 cells which was dependent on interactions between APRIL and TACI/BCMA. Immunohistochemical analysis of human pathologic samples detected the expression of both APRIL and TACI in macrophage-rich areas. Additionally, human macrophage primary culture expressed APRIL on the cell surface. Conclusion: These observations indicate that APRIL, which is expressed on macrophages in pathologic tissues with chronic inflammation, may mediate activation signals through its interaction with its counterparts via cell-to-cell interaction.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.432-442
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• 2023

Background Macrophages play a major role in wound healing and prevent infection from the outside. Polarization conversion of macrophages regulates aspects of inflammation, and two macrophages, M1 (classically activated) and M2 (alternatively activated), exist at both ends of broad-spectrum macrophage polarization. Thus, we aimed to investigate whether macrophage polarization can be artificially regulated. To this end, MgSO4 and small-interfering RNA (siRNA) targeting magnesium transport 1 (MAGT1) were used to investigate the effects of intracellular magnesium (Mg2+) concentrations on the differentiation of macrophages in vitro. Methods THP-1 derived macrophages maintained in a culture medium containing 5 mM MgSO4 and siRNA to inhibit the expression of MAGT1. As comparative groups, THP-1 derived macrophages polarized into M1 and M2 macrophages by treatment with M1, M2 inducer cytokine. The polarization status of each group of cells was confirmed by cell surface antigen expression and cytokine secretion. Results We found that MgSO4 treatment increased CD163 and CD206, similar to the effect noted in the M2 group. The expression of CD80 and HLA-DR was increased in the group treated with MAGT1 siRNA, similar to the effect noted in the M1 group. Functional assays demonstrated that the group treated with MgSO4 secreted higher levels of IL-10, whereas the MAGT1 siRNA-treated group secreted higher levels of IL-6 cytokines. Additionally, the conditional medium of the Mg2+ treated group showed enhanced migration of keratinocytes and fibroblasts. Conclusion Mg2+ can help to end the delay in wound healing caused by persistent inflammation in the early stages.

• International Journal of Oral Biology
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• v.42 no.1
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• pp.33-38
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• 2017

Background: Periodontitis is an inflammatory disease characterized by the breakdown of tooth-supporting tissues, leading to tooth loss. Aggregatibacter actinomycetemcomitans are major etiologic bacterium causing aggressive periodontitis. Ursodeoxycholic acid (UDCA), a hydrophilic gall bladder acid, has been used as an effective drug for various diseases related to immunity. The aim of this study was to investigate the effect of UDCA on the inflammatory response induced by A. actinomycetemcomitans. Methods: A human acute monocytic leukemia cell line (THP-1) was differentiated to macrophage- like cells by treatment with phorbol 12-mystristate 13-acetate (PMA) and used for all experiments. The cytotoxic effect of UDCA was examined by MTT assay. THP-1 cells were pretreated with UDCA for 30 min before A. actinomycetemcomitans infection and the culture supernatant was analyzed for various cytokine production by ELISA. The effect of UDCA on bacterial growth was examined by measuring optical densities using a spectrophotometer. Results: UDCA showed no cytotoxic effect on THP-1 cells, up to $80{\mu}M$ Ed highlight: Please confirm technical meaning. UDCA pretreatment inhibited the A. actinomycetemcomitans-induced $IL-1{\beta}$, $TNF-{\alpha}$, and IL-17A secretion in a dose-dependent manner. UDCA also inhibited IL-21 production at $60{\mu}M$. The production of IL-12 and IL-4 was not influenced by A. actinomycetemcomitans infection. Conclusion: These findings indicate that UDCA inhibits the production of inflammatory cytokines involved in innate and Th17 immune responses in A. actinomycetemcomitans-infected THP-1- derived macrophages, which suggests its possible use for the control of aggressive periodontitis.