• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.88-88
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• 2022

In this study, we investigated the effect of Solanum nigrum aerial parts (SNAP) on macrophage activation and macrophage autophagy in RAW264.7 cells. SNAP increased the production of immunostimulatory factors and phagocytosis in RAW264.7 cells. TLR4 inhibition blocked SNAP-mediated production of immunostimulatory factors. In addition, the JNK inhibition reduced the SNAP-mediated production of immunostimulatory factors, and the SNAP-mediated JNK activation was blocked by the TLR4 inhibition. SNAP activated macrophage autophagy. TLR4 inhibition blocked SNAP-mediated macrophage autophagy and inhibition of p38 and JNK attenuated SNAP-mediated macrophage autophagy. These findings indicate that SNAP may induce TLR4/JNK-mediated macrophage activation and TLR4/p38 and JNK-mediated macrophage autophagy.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.934-940
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• 2023

Syneilesis palmata (SP) is a traditional medicinal plant. SP has been reported to have anti-inflammatory, anticancer, and anti-human immunodeficiency virus (HIV) activities. However, there is currently no research available on the immunostimulatory activity of SP. Therefore, in this study, we report that S. palmata leaves (SPL) activate macrophages. Increased secretion of both immunostimulatory mediators and phagocytic activity was observed in SPL-treated RAW264.7 cells. However, this effect was reversed by the inhibition of TLR2/4. In addition, inhibition of p38 decreased the secretion of immunostimulatory mediators induced by SPL, and inhibition of TLR2/4 decreased the phosphorylation of p38 induced by SPL. SPL augmented p62/SQSTM1 and LC3-II expression. The increase in protein levels of p62/SQSTM1 and LC3-II induced by SPL was decreased by the inhibition of TLR2/4. The results obtained from this study suggest that SPL activates macrophages via TLR2/4-dependent p38 activation and induces autophagy in macrophages via TLR2/4 stimulation.

• BMB Reports
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• v.55 no.8
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• pp.407-412
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• 2022

A well-controlled inflammatory response is crucial for the recovery from injury and maintenance of tissue homeostasis. The anti-inflammatory response of 2-methoxycinnamaldehyde (2-MCA), a natural compound derived from cinnamon, has been studied; however, the underlying mechanism on macrophage has not been fully elucidated. In this study, LPS-stimulated production of TNF-α and NO was reduced by 2-MCA in macrophages. 2-MCA significantly activated the NRF2 pathway, and expression levels of autophagy-associated proteins in macrophages, including LC3 and P62, were enhanced via NRF2 activation regardless of LPS treatment, suggesting the occurrence of 2-MCA-mediated autophagy. Moreover, evaluation of autophagy flux using luciferase-conjugated LC3 revealed that incremental LC3 and P62 levels are coupled to enhanced autophagy flux. Finally, reduced expression levels of TNF-α and NOS2 by 2-MCA were reversed by autophagy inhibitors, such as bafilomycin A1 and NH4Cl, in LPS-stimulated macrophages. In conclusion, 2-MCA enhances autophagy flux in macrophages via NRF2 activation and consequently reduces LPS-induced inflammation.

• Korean Journal of Plant Resources
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• v.36 no.4
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• pp.275-281
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• 2023

Autophagy contributes to enhancing the immune system (innate and adaptive immune system) against foreign pathogens. Autophagy of macrophages is used as a major indicator for developing vaccine adjuvants to increase the adaptive immune response. In this study, PLR activated autophagy and increased p62/SQSTM1. The knockdown of p62/SQSTM1 attenuated PLR-mediated autophagy. Inhibition of TLR4 blocked PLR-mediated increase in p62/SQSTM1 level and autophagy induction. In addition, inhibition of PI3K blocked HSL-mediated increase of p62/SQSTM1. PLR increased Nrf2 level and the inhibition of TLR4 and PI3K reduced PLR-mediated increase of Nrf2. Taken together, it is believed that PLR may induce autophagy through upregulating p62/SQSTM1 via TLR4/PI3K/Nrf2 signaling pathway.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.93-93
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• 2022

Hovenia dulcis, one of the traditional medicinal plants, is currently being used as a functional ingredient for the development of health functional foods that protects the liver from alcohol damage in Korea. A variety of pharmacological effects of Hovenia dulcis have been reported so far, but studies on immune-enhancing activity are insufficient. Thus, in this study, we report that Hovenia dulcis branches (HDB) induce the activation of macrophages. HDB increased the production of immunostimulatory factors and phagocytosis in RAW264.7 cells. TLR4 inhibition blocked HDB-mediated production of immunostimulatory factors. In addition, the JNK inhibition reduced the HDB-mediated production of immunostimulatory factors, and the HDB-mediated JNK activation was blocked by the TLR4 inhibition. HDB increased the level of LC3-II and p62/SQSTM1. TLR4 inhibition blocked HDB-mediated increase in the level of LC3-II and p62/SQSTM1. These findings indicate that HDB may induce TLR4/JNK-dependent macrophage activation and TLR4-dependent macrophage autophagy.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.27-32
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• 2014

Autophagy is one of the lysosomal degradation pathways to maintain cellular homeostasis. The damaged proteins or organelles are uptaken through extra- and intra-cellular stress, starvation and infected pathogens, subsequently, autophagosomes are fused with lysosomes to break down the molecules. Salmonella enterica serovar Typhimurium (S. Typhimurium), intracellular bacteria, cause acute gastroenteritis and food poisoning. Given that autophagy induced by S. Typhimurium plays an important role in the cells to control the infection, we identify whether the induction of autophagy with rapamycin, chemical inducer of autophagy, before infection regulates S. Typhimurium infection. After treatment of rapamycin or 3-methyladenine (3-MA), autophagy inhibitor, RAW264.7 cells were infected with S. Typhimurium. Pretretment of rapamycin decreased the growth rate of S. Typhimurium in the cells; otherwise, pretreatment of 3-MA increased the growth rate of S. Typhimurium. The expression of autophagy-related genes was significantly increased in the S. Typhimurium-infected cells pretreated with rapamycin. To examine whether induced autophagy by rapamycin control the infection with increase the production of reactive oxygen species (ROS) and nitric oxide (NO), antibacterial radical substrates were measured in infected cells followed by the treatment with either rapamycin or 3-MA. NO production increased in RAW264.7 cells; otherwise, ROS production remained unchanged during the infection. These findings suggest that inducing autophagy with rapamycin reveals antimicrobial activity as producing NO against S. Typhimurium infection in mouse macrophages.

• International Journal of Oral Biology
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• v.42 no.1
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• pp.17-23
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• 2017

Background: Periodontitis is generally a chronic disorder characterized by the breakdown of tooth-supporting tissues. P. gingivalis, a Gram-negative anaerobic rod, is one of the major pathogens associated with periodontitis. Frequently, P. gingivalis infection leads to cell death. However, the correlation between P. gingivalis-induced cell death and periodontal inflammation remains to be elucidated. Among cell deaths, the death of immune cells appears to play a significant role in inflammatory response. Thus, the aim of this study was to examine P. gingivalis-induced cell death, focusing on autophagy and apoptosis in THP-1 cells. Methods: Human acute monocytic leukemia cell line (THP-1) was used for all experiments. Autophagy induced by P. gingivalis in THP-1 cells was examined by Cyto ID staining. Intracellular autophagic vacuoles were observed by fluorescence microscopy using staining Acridine orange (AO); and 3-methyladenine (3-MA) was used to inhibit autophagy. Total cell death was measured by LDH assay. Cytokine production was measured by an ELISA method. Results: P. gingivalis induced autophagy in an MOI-dependent manner in THP-1 cells, but 3-MA treatment decreased autophagy and increased the apoptotic blebs. P. gingivalis infection did not increase apoptosis compared to the control cells, whereas inhibition of autophagy by 3-MA significantly increased apoptosis in P. gingivalis-infected THP-1 cells. Inhibition of autophagy by 3-MA also increased total cell deaths and inflammatory cytokine production, including $IL-1{\beta}$ and $TNF-{\alpha}$. Conclusion: P. gingivalis induced autophagy in THP-1 cells, but the inhibition of autophagy by 3-MA stimulated apoptosis, leading to increased cell deaths and pro-inflammatory cytokines production. Hence, the modulation of cell deaths may provide a mechanism to fight against invading microorganisms in host cells and could be a promising way to control inflammation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.44-44
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• 2023

Syneilesis palmata (SP) has been used as a traditional medicinal plant and vegetable. SP was reported to exert pharmacological activities such as anti-inflammation, anti-cancer, and anti-HIV. However, there are no studies on the immunostimulatory activity of SP. Thus, in this study, we report that S. palmata leaves (SPL) induce the activation of macrophages. An increase in both secretions of immunostimulatory mediators and phagocytotic activity was observed in SPL-treated RAW264.7 cells. However, this was reversed by inhibition of TLR2/4. In addition, the p38 inhibition reduced the SPL-mediated secretion of immunostimulatory mediators, and the SPL-mediated p38 activation was blocked by the TLR2/4 inhibition. SPL augmented both p62/SQSTM1 and LC3-II. TLR2/4 inhibition blocked the SPL-mediated increase of p62/SQSTM1 and LC3-II. These findings indicate that SPL may activate macrophages through TLR2/4-dependent p38 activation and activate autophagy through TLR2/4 stimulation.

• Molecules and Cells
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• v.42 no.1
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• pp.1-7
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• 2019

Macrophage is an important innate immune cell that not only initiates inflammatory responses, but also functions in tissue repair and anti-inflammatory responses. Regulating macrophage activity is thus critical to maintain immune homeostasis. Tyro3, Axl, and Mer are integral membrane proteins that constitute TAM family of receptor tyrosine kinases (RTKs). Growing evidence indicates that TAM family receptors play an important role in anti-inflammatory responses through modulating the function of macrophages. First, macrophages can recognize apoptotic bodies through interaction between TAM family receptors expressed on macrophages and their ligands attached to apoptotic bodies. Without TAM signaling, macrophages cannot clear up apoptotic cells, leading to broad inflammation due to over-activation of immune cells. Second, TAM signaling can prevent chronic activation of macrophages by attenuating inflammatory pathways through particular pattern recognition receptors and cytokine receptors. Third, TAM signaling can induce autophagy which is an important mechanism to inhibit NLRP3 inflammasome activation in macrophages. Fourth, TAM signaling can inhibit polarization of M1 macrophages. In this review, we will focus on mechanisms involved in how TAM family of RTKs can modulate function of macrophage associated with anti-inflammatory responses described above. We will also discuss several human diseases related to TAM signaling and potential therapeutic strategies of targeting TAM signaling.

• Molecules and Cells
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• v.45 no.4
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• pp.257-272
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• 2022

In addition to inducing apoptosis, caspase inhibition contributes to necroptosis and/or autophagy depending on the cell type and cellular context. In macrophages, necroptosis can be induced by co-treatment with Toll-like receptor (TLR) ligands (lipopolysaccharide [LPS] for TLR4 and polyinosinic-polycytidylic acid [poly I:C] for TLR3) and a cell-permeable pan-caspase inhibitor zVAD. Here, we elucidated the signaling pathways and molecular mechanisms of cell death. We showed that LPS/zVAD- and poly I:C/zVAD-induced cell death in bone marrow-derived macrophages (BMDMs) was inhibited by receptor-interacting protein kinase 1 (RIP1) inhibitor necrostatin-1 and autophagy inhibitor 3-methyladenine. Electron microscopic images displayed autophagosome/autolysosomes, and immunoblotting data revealed increased LC3II expression. Although zVAD did not affect LPS- or poly I:C-induced activation of IKK, JNK, and p38, it enhanced IRF3 and STAT1 activation as well as type I interferon (IFN) expression. In addition, zVAD inhibited ERK and Akt phosphorylation induced by LPS and poly I:C. Of note, zVAD-induced enhancement of the IRF3/IFN/STAT1 axis was abolished by necrostatin-1, while zVAD-induced inhibition of ERK and Akt was not. Our data further support the involvement of autocrine IFNs action in reactive oxygen species (ROS)-dependent necroptosis, LPS/zVAD-elicited ROS production was inhibited by necrostatin-1, neutralizing antibody of IFN receptor (IFNR) and JAK inhibitor AZD1480. Accordingly, both cell death and ROS production induced by TLR ligands plus zVAD were abrogated in STAT1 knockout macrophages. We conclude that enhanced TRIF-RIP1-dependent autocrine action of IFNβ, rather than inhibition of ERK or Akt, is involved in TLRs/zVAD-induced autophagic and necroptotic cell death via the JAK/STAT1/ROS pathway.