Ki-Young Sohn

EC-18, a synthetic monoacetyldiglyceride (1-palmitoyl-2-linoleoyl-3-acetylglycerol), attenuates the asthmatic response in an aluminum hydroxide/ovalbumin-induced model of asthma

EC-18 is a synthetic monoacetyldiaglyceride that is a major constituent in antlers of Sika deer (Cervus nippon Temmenick). In this study, we evaluated the protective effects of EC-18 on Th2-type cytokines, eosinophil infiltration, and other factors in an aluminum hydroxide/ovalbumin (OVA)-induced murine asthma model. Mice were sensitized on days 0 and 14 by intraperitoneal injection of OVA with aluminum hydroxide. On days 21, 22 and 23 after the initial sensitization, the mice received an airway challenge with OVA for 1h using an ultrasonic nebulizer. EC-18 was administered to mice by oral gavage at doses of 30mg/kg and 60mg/kg once daily from day 18 to 23. Methacholine responsiveness was measured 24h after the final OVA challenge, and the bronchoalveolar lavage fluid (BALF) was collected 48h after the final OVA challenge. EC-18 significantly reduced methacholine responsiveness, T helper type 2 (Th2) cytokines, eotaxin-1, immunoglobulin (Ig) E, IgG, and the number of inflammatory cells. In addition, EC-18-treated mice exhibited the reduction in the expression of inducible nitric oxide synthase (iNOS) in lung tissue. In the histological analysis using hematoxylin-eosin stain and periodic acid-Schiff stain, EC-18 attenuated the infiltration of inflammatory cells into the airway and reduced the level of mucus production. Our results showed that EC-18 effectively suppressed the asthmatic response induced by OVA challenge. These effects were considered to be associated with iNOS suppression. In conclusion, this study suggests that EC-18 may be a therapeutic agent for allergic asthma.

Protective effect of EC-18, a synthetic monoacetyldiglyceride on lung inflammation in a murine model induced by cigarette smoke and lipopolysaccharide

The antler of Sika deer (Cervus nippon Temminck) has been used a natural medicine in Korea, China and Japan, and a monoacetyldiaglyceride (1-palmitoyl-2-linoleoyl-3-acetylglycerol, PLAG) was found in the antler of Sika deer as a constituent for immunomodulation. In this study, we investigated protective effects of EC-18 (a synthetic copy of PLAG) on inflammatory responses using a cigarette smoke with lipopolysaccharide (LPS)-induced airway inflammation model. Mice were exposed to cigarette smoke for 1h per day for 3days. Ten micrograms of LPS dissolved in 50μL of PBS was administered intra nasally 1h after the final cigarette smoke exposure. EC-18 was administered by oral gavage at doses of 30 and 60mg/kg for 3days. EC-18 significantly reduced the number of neutrophils, reactive oxygen species production, cytokines and elastase activity in bronchoalveolar lavage fluid (BALF) compared with the cigarette smoke and LPS induced mice. Histologically, EC-18 attenuated airway inflammation with a reduction in myeloperoxidase expression in lung tissue. Additionally, EC-18 inhibited the phosphorylation of NF-κB and IκB induced by cigarette smoke and LPS exposure. Our results show that EC-18 effectively suppresses neutrophilic inflammation induced by cigarette smoke and LPS exposure. In conclusion, this study suggests that EC-18 has therapeutic potential for the treatment of chronic obstructive pulmonary disease.

The therapeutic effect of PLAG against oral mucositis in hamster and mouse model

Chemotherapy-induced mucositis can limit the effectiveness of cancer therapy and increase the risk of infections. However, no specific therapy for protection against mucositis is currently available. In this study, we investigated the therapeutic effect of PLAG (1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol, acetylated diglyceride) in 5-fluorouracil (5-FU)-induced oral mucositis animal models. Hamsters were administered 5-FU (80 mg/kg) intraperitoneally on days 0, 6, and 9. The animals’ cheek pouches were then scratched equally with the tip of an 18-gage needle on days 1, 2, and 7. PLAG was administered daily at 250 mg/kg/day. PLAG administration significantly reduced 5-FU/scratching-induced mucositis. Dramatic reversal of weight loss in PLAG-treated hamsters with mucositis was observed. Histochemical staining data also revealed newly differentiated epidermis and blood vessels in the cheek pouches of PLAG-treated hamsters, indicative of recovery. Whole blood analyses indicated that PLAG prevents 5-FU-induced excessive neutrophil transmigration to the infection site and eventually stabilizes the number of circulating neutrophils. In a mouse mucositis model, mice with 5-FU-induced disease treated with PLAG exhibited resistance to body-weight loss compared with mice that received 5-FU or 5-FU/scratching alone. PLAG also dramatically reversed mucositis-associated weight loss and inhibited mucositis-induced inflammatory responses in the tongue and serum. These data suggest that PLAG enhances recovery from 5-FU-induced oral mucositis and may therefore be a useful therapeutic agent for treating side effects of chemotherapy, such as mucositis and cachexia.

PLAG (1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol) augments the therapeutic effect of pegfilgrastim on gemcitabine-induced neutropenia

Granulocyte colony-stimulating factor (G-CSF) is widely used for preventing neutropenia during chemotherapy. Polyethylene glycol-conjugated granulocyte colony-stimulating factor (PEG-G-CSF, pegfilgrastim) serves the same purpose but has a longer half-life and greater stability than G-CSF. In this study, we investigated whether 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol, acetylated diglyceride (PLAG), augments the therapeutic effect of pegfilgrastim on chemotherapy-induced neutropenia. We compared neutrophil counts in four groups of mice: control mice, gemcitabine-treated mice, gemcitabine/pegfilgrastim-treated mice, and gemcitabine/pegfilgrastim/PLAG-treated mice. PLAG (50 mg/kg) was orally administered every day during the treatment course. CBC analysis showed that the group treated with PLAG experienced a dramatically increased neutrophil counts on the third day following pegfilgrastim treatment. PLAG had no effect on blood cell apoptosis and neutrophil release from bone marrow. Additionally, pegfilgrastim-induced CXCR2 expression in neutrophils was markedly decreased in PLAG-treated animals. These results suggest that PLAG plays a role in inhibiting neutrophil extravasation, giving rise to an increased number of circulating neutrophils when used with pegfilgrastim during gemcitabine treatment. These data support the potential for PLAG to be used with pegfilgrastim to treat or prevent chemotherapy-induced neutropenia by modulating neutrophil transmigration.

PLAG (1-Palmitoyl-2-Linoleoyl-3-Acetyl-rac-Glycerol) Modulates Eosinophil Chemotaxis by Regulating CCL26 Expression from Epithelial Cells

Increased number of eosinophils in the circulation and sputum is associated with the severity of asthma. The respiratory epithelium produces chemokine (C-C motif) ligands (CCL) which recruits and activates eosinophils. A chemically synthesized monoacetyl-diglyceride, PLAG (1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol) is a major constituent in the antlers of Sika deer (Cervus nippon Temminck) which has been used in oriental medicine. This study was aimed to investigate the molecular mechanism of PLAG effect on the alleviation of asthma phenotypes. A549, a human alveolar basal epithelial cell, and HaCaT, a human keratinocyte, were activated by the treatment of interleukin-4 (IL-4), and the expression of chemokines, known to be effective on the induction of eosinophil migration was analyzed by RT-PCR. The expression of IL-4 induced genes was modulated by the co-treatment of PLAG. Especially, CCL26 expression from the stimulated epithelial cells was significantly blocked by PLAG, which was confirmed by ELISA. The transcriptional activity of signal transducer and activator of transcription 6 (STAT6), activated by IL-4 mediated phosphorylation and nuclear translocation, was down-regulated by PLAG in a concentration-dependent manner. In ovalbumin-induced mouse model, the infiltration of immune cells into the respiratory tract was decreased by PLAG administration. Cytological analysis of the isolated bronchoalveolar lavage fluid (BALF) cells proved the infiltration of eosinophils was significantly reduced by PLAG. In addition, PLAG inhibited the migration of murine bone marrow-derived eosinophils, and human eosinophil cell line, EoL-1, which was induced by the addition of A549 culture medium.

1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol ameliorates arthritic joints through reducing neutrophil infiltration mediated by IL-6/STAT3 and MIP-2 activation

The pathogenesis of rheumatoid arthritis (RA) has been implicated neutrophil extracellular traps (NETs) formation which could generate autoantigen. Neutrophil contributes to initiate and maintain the inflammatory process in the joint. In this study, we show that 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) decreases neutrophil migration by regulating the activity of STAT3, a regulator of IL-6 and MIP-2 expression. PLAG caused a decrease in IL-6 production in the RAW264.7 macrophage cell line and in rheumatoid arthritis–fibroblast-like synoviocytes via the regulation of STAT3 signaling without affecting NF-κB signaling. In a mouse model of collagen-induced arthritis (CIA), arthritic symptoms were recapitulated, with increased IL-6 level in the synovium, and PLAG treatment restored IL-6 to a level comparable to that achieved with commercial therapeutics (such as Remicade or methotrexate). Staining of joint tissue with neutrophil-specific antibody showed that PLAG significantly reduced the infiltration of neutrophils into the joint synovium of CIA mice. The inhibitory effect of PLAG on IL-6/STAT3 or MIP-2 signaling also reduced the migration of differentiated neutrophils in vitro. Therefore, PLAG inhibits the infiltration of destructive neutrophils into inflammatory sites, and can be utilized as a potent therapeutic agent for the treatment of sustained inflammation and joint destruction.The pathogenesis of rheumatoid arthritis (RA) has been implicated neutrophil extracellular traps (NETs) formation which could generate autoantigen. Neutrophil contributes to initiate and maintain the inflammatory process in the joint. In this study, we show that 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) decreases neutrophil migration by regulating the activity of STAT3, a regulator of IL-6 and MIP-2 expression. PLAG caused a decrease in IL-6 production in the RAW264.7 macrophage cell line and in rheumatoid arthritis-fibroblast-like synoviocytes via the regulation of STAT3 signaling without affecting NF-κB signaling. In a mouse model of collagen-induced arthritis (CIA), arthritic symptoms were recapitulated, with increased IL-6 level in the synovium, and PLAG treatment restored IL-6 to a level comparable to that achieved with commercial therapeutics (such as Remicade or methotrexate). Staining of joint tissue with neutrophil-specific antibody showed that PLAG significantly reduced the infiltration of neutrophils into the joint synovium of CIA mice. The inhibitory effect of PLAG on IL-6/STAT3 or MIP-2 signaling also reduced the migration of differentiated neutrophils in vitro. Therefore, PLAG inhibits the infiltration of destructive neutrophils into inflammatory sites, and can be utilized as a potent therapeutic agent for the treatment of sustained inflammation and joint destruction.

PLAG alleviates chemotherapy-induced thrombocytopenia via promotion of megakaryocyte/erythrocyte progenitor differentiation in mice

Previously, PLAG (1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol, acetylated diglyceride) was reported to have an effect on the proliferation of hematopoietic stem cells (HSCs) or to contribute to the prevention of chemotherapy-induced neutropenia. In this study, we examined the role of PLAG in the differentiation of bone marrow cells from HSCs into progenitor cells in mice. After 15days, the lineage-negative cells, especially megakaryocyte/erythrocyte progenitors (MEP), were significantly increased in mice that received daily PLAG administration compared to those in the untreated mice. Furthermore, we explored the possibility that the PLAG-induced increase in MEP will contribute to reduction of chemotherapy-induced thrombocytopenia (CIT) in a thrombocytopenia mouse model. Mice were administrated 5-fluorouracil (5-FU) and PLAG. After 7days, bone marrow cells were analyzed. Treatment with 5-FU powerfully decreased myeloid precursor populations and treatment with 5-FU/PLAG resulted in reduction of decreased myeloid progenitor cell numbers. In addition, numbers of circulating platelets were also increased by PLAG treatment. Taken together, PLAG plays a role in differentiating HSCs toward MEP and alleviating chemotherapy-induced bone marrow cell reduction. Thus PLAG shows its potential to augment the therapeutic effect of anti-cancer drugs-induced thrombocytopenia.

1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) reduces hepatic injury in concanavalin A-treated mice†

1‐palmitoyl‐2‐linoleoyl‐3‐acetyl‐rac‐glycerol (PLAG), a chemically synthesized monoacetyldiaglyceride, is one of the constituents in Sika deer antlers and has been known traditionally as having immunomodulatory effects. However, the mechanism by which PLAG controls neutrophil migration, which evokes liver injury in the hepatitis animal model, remains largely unknown. This study was designed to evaluate the immunomodulatory effects of PLAG on cytokine secretion and neutrophil migration in vivo and in vitro. Concanavalin A (Con A) induced leukocyte infiltration in the liver and increased plasma cytokine levels. Pretreatment with PLAG reduced the levels of interleukin (IL)‐4, IL‐6, IL‐10, and CXCL2, but maintained interferon (IFN)‐γ levels and modulated neutrophil recruitment toward the liver. Furthermore, the mRNA and protein levels of IL‐4 and CXCL2 in liver tissue were also decreased in the Con A‐treated mice. Liver histology analyses showed that PLAG reduced Con A‐induced hepatic necrosis, which was accompanied by leukocyte infiltration. The in vitro studies revealed that PLAG reduced IL‐4 secretion in Con A stimulated T cell and blocked signal transducer and activator of transcription 6 (STAT6) Con A induced hepatocyte. PLAG attenuated IL‐4 induced activation of atypical protein kinase C (PKC)/STAT6 in hepatocytes and inhibited neutrophil migration toward the liver tissue through suppression of IL‐8/vascular cell adhesion molecule (VCAM) expression. These results suggest that PLAG could mitigate excess neutrophil migration into liver tissue and potentially have a therapeutic effect on immune‐mediated liver injury.

Abstract 5664: PLAG prevents the loss of circulating neutrophils in the chemotherapy induced neutropenia model

Chemotherapy-induced neutropenia (CIN) is a common dose-limiting toxicity in cancer patients undergoing cytotoxic chemotherapy. It is generally understood that myelosuppression is the major mechanism resulting in CIN. However, an excessive extravasation (diapedesis) of neutrophils in response to tissue damage-caused by anti-cancer agents is also a possible mechanism. In this study, we have investigated the effects of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) for the maintenance of circulating neutrophil in the gemcitabine induced neutropenia. In CIN mouse model using anticancer drugs, PLAG effectively protected the loss of circulating neutrophils as similar to CXCR2 antagonist, reparixin. And succeeded in vitro neutrophil migration assay also revealed that chemo-attractive activity of neutrophil induced by treatment of anticancer drugs was completely interrupted by PLAG addition. Chemokine (C-X-C motif) ligand 2 (CXCL2) and CXCL8 were effectively induced by treatment of gemcitabine with dose dependent manner in monocyte cell lines and mainly mediated via the signal transducer and activator of transcription 3 (STAT3) signaling pathway. PLAG effectively attenuated gemcitabine induced CXCL2 and CXCL8 expression via interrupting STAT3 activity and also regulated gemcitabine induced macrophage 1 antigen (MAC-1) and L-selectin expression, which means that PLAG interrupted the acceleration of neutrophil extravasation under CIN. Also we have verified that PLAG analogues and metabolites were not affected on neutrophil migration unlike PLAG, suggesting that acetylated diacylglycerol has a key role to regulate on neutrophil migration. Collectively, modulating effect of PLAG on excessive neutrophil extravasation by chemotherapy via attenuating STAT3/CXCL2(8) pathway could be used as very powerful regimen for preventing of neutropenia during diverse chemotherapy. Citation Format: Yong-Jae Kim, Jinseon Jung, Ha-Reum Lee, Ki-Young Sohn, Heung-Jae Kim, Sun Young Yoon, Jae Wha Kim. PLAG prevents the loss of circulating neutrophils in the chemotherapy induced neutropenia model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5664. doi:10.1158/1538-7445.AM2017-5664

Effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol on Immune Functions in Healthy Adults in a Randomized Controlled Trial

We previously reported that 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) accelerates hematopoiesis and has an improving effect on animal disease models such as sepsis and asthma. The effects of PLAG supplementation on immune modulation were assessed in healthy men and women. The objective was to evaluate the effects of PLAG supplementation on immune regulatory functions such as activities of immune cells and cytokine production. A randomized double blind placebo-controlled trial was conducted. Seventy-five participants were assigned to one of two groups; all participants had an appropriate number of white blood cells on the testing day. The PLAG group (n=27) received oral PLAG supplements and the control group (n=22) received oral soybean oil supplements. IL-4 and IL-6 production by peripheral blood mononuclear cells (PBMC) were lower (p<0.001 and p<0.001, respectively) with PLAG than with soybean oil. However, the production of IL-2 and IFN-γ by PBMC was unaltered with PLAG supplementation. The B cell proliferation decreased significantly in the PLAG group compared to the soybean oil control (p<0.05). The intake of PLAG in healthy adults for 4 weeks was deemed safe. These data suggest that PLAG has an immunomodulatory function that inhibits the excessive immune activity of immunological disorders such as atopic and autoimmune diseases. PLAG could improve the condition of these diseases safely as a health food supplement.