Kyungsook Jung

Activation of mitogen-activated protein kinases in experimental autoimmune encephalomyelitis

The expression of mitogen-activated protein (MAP) kinases, including extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal protein kinase (JNK), and p38, was analyzed in experimental autoimmune encephalomyelitis (EAE) in rats. Western blot analysis showed that the three MAP kinases (phosphorylated ERK (p-ERK), p-JNK, and p-p38) were increased significantly in the spinal cords of rats with EAE at the peak stage as compared with the levels in controls (p<0.05), and both p-ERK and p-JNK declined slightly in the recovery stage of EAE. Immunohistochemistry showed that p-ERK was constitutively expressed in brain cells, including astroglial cells, and showed enhanced immunoreactivity in those cells in EAE, while some T cells and macrophages were weakly immunopositive for p-ERK in EAE lesions. Both p-JNK and p-p38 were intensely immunostained in T cells in EAE lesions, while a few glial cells and astrocytes were weakly positive for both. Taking all these facts into consideration, we postulate that increased expression of the phosphorylated form of each MAP kinase plays an important role in the initiation of acute monophasic EAE. Differential expression of three MAP kinases was discerned in an animal model of human autoimmune central nervous system diseases, including multiple sclerosis.

Oral supplementation with Lactobacillus rhamnosus CGMCC 1.3724 prevents development of atopic dermatitis in NC/NgaTnd mice possibly by modulating local production of IFN-γ

Abstract:  Prevalence of allergies has increased during the last two decades. Alteration of the gut microbiota composition is thought to play a crucial role in development of atopic diseases. Oral administration of probiotics has been reported to treat and/or prevent symptoms of atopic diseases in infants, but the results are still controversial. We investigated the potential efficacy of dietary interventions by a probiotic strain on prevention and treatment of atopic dermatitis (AD) in a human‐like AD model, NC/NgaTnd mice by perinatal administration. Pregnant NC/NgaTnd mice were orally treated with the probiotic strain Lactobacillus rhamnosus CGMCC 1.3724 (LPR), which was followed by treatment of pups until 12 weeks of age. LPR‐treated mice exhibited significant lower clinical symptoms of dermatitis, reduced scratching frequency, lower levels of plasma total Immunoglobulin E and higher levels of interferon‐γ in skin biopsies, compared with untreated mice. The protective effect was also observed when mice started to be treated at weaning time (5 weeks of age) even with limited supplementation period of 2 weeks. However, treatment of mice with the probiotic starting 1 week after the onset of the disease (8 weeks of age) had limited effects. The usefulness of LPR for primary prevention of AD was supported.

Upregulation of phospholipase D1 in the spinal cords of rats with clip compression injury

This study examined phospholipase D 1 (PLD1) expression in the central nervous system following clip compression spinal cord injury (SCI) in Sprague-Dawley rats. After inducing SCI with a vascular clip, the expression of PLD1 in the affected spinal cord was analyzed by Western blot and immunohistochemistry. Western blot analysis showed that the expression of PLD1 gradually increased in the spinal cord on days 0.5, 1, 2, and 4 post injury. Immunohistochemistry showed that some cells, including neurons, astrocytes, and some inflammatory cells, were positive for PLD1 in the lesions at days 1 and 2 post injury. At day 4, the number of PLD1-positive cells in SCI lesions increased, largely matching the increases in ED1-positive macrophages and glial fibrillary acidic protein-positive astrocytes. At this time, macrophages expressed proliferating cell nuclear antigen in addition to PLD1. These results suggest that PLD1 expression is increased in injured spinal cords, and might be involved in the activation and proliferation of macrophages and astrocytes in SCI.

Peroxisome proliferator–activated receptor γ–mediated suppression of dendritic cell function prevents the onset of atopic dermatitis in NC/Tnd mice

BACKGROUND Dendritic cells (DCs) are one of the key regulators for the initiation of allergic responses in patients with atopic dermatitis (AD), being strongly triggered by epithelial cell-derived thymic stromal lymphopoietin (TSLP). Because peroxisome proliferator-activated receptor (PPAR) γ acts as a negative regulator in immune cells, suppressive properties of PPARγ in allergic responses have been proposed. OBJECTIVE Because pieces of evidence must be organized to identify the exact role of PPARγ in immune regulation, we explored the suppressive effects of a PPARγ agonist on various functions of DCs and the onset of AD in a murine model. METHODS Effects of rosiglitazone (RSG) on DCs that were derived from NC/Tnd mice, a model for human AD, were analyzed. RSG was administered to NC/Tnd mice to evaluate its preventive and therapeutic effects on the development of AD. RESULTS RSG inhibited TSLP-induced DC maturation through downregulation of costimulatory molecules. TSLP-promoted expressions of chemokines in DCs were also suppressed by RSG treatment. Moreover, we showed the necessity of matrix metalloproteinase 9 in TSLP-promoted DC migration by using DCs derived from matrix metalloproteinase 9-deficient NC/Tnd mice, as well as the suppressive effect of PPARγ in the process. Daily oral administration of RSG to NC/Tnd mice before the onset of AD revealed a significant reduction in severity of skin lesions and scratching behavior. In mice treated with RSG, both expression of TSLP in the skin and maturation and migration of DCs were markedly suppressed. CONCLUSION PPARγ can be provided as an inhibitory regulator of TSLP-stimulated DCs in the onset of allergic reactions.

Nuclear factor-ĸB plays a critical role in both intrinsic and acquired resistance against endocrine therapy in human breast cancer cells

Since more than 75% of breast cancers overexpress estrogen receptors (ER), endocrine therapy targeting ER has significantly improved the survival rate. Nonetheless, breast cancer still afflicts women worldwide and the major problem behind it is resistance to endocrine therapy. We have previously shown the involvement of nuclear factor-κB (NF-κB) in neoplastic proliferation of human breast cancer cells; however, the association with the transformation of ER-positive cells remains unclear. In the current study, we focused on roles of NF-κB in the hormone dependency of breast cancers by means of ER-positive MCF-7 cells. Blocking of NF-κB signals in ER-negative cells stopped proliferation by downregulation of D-type cyclins. In contrast, the MCF-7 cells were resistant to NF-κB inhibition. Under estrogen-free conditions, the ER levels were reduced when compared with the original MCF-7 cells and the established cell subline exhibited tamoxifen resistance. Additionally, NF-κB participated in cell growth instead of the estrogen-ER axis in the subline and consequently, interfering with the NF-κB signals induced additive anticancer effects with tamoxifen. MMP-9 production responsible for cell migration, as well as the cell expansion in vivo, were suppressed by NF-κB inhibition. Therefore, we suggest that NF-κB is a master switch in both ER-positive and ER-negative breast cancers.

Increased expression of phospholipase D1 in the spinal cords of rats with experimental autoimmune encephalomyelitis.

Phospholipase D1 (PLD1) expression was studied in the central nervous system (CNS) under the condition of induced experimental autoimmune encephalomyelitis (EAE) in Lewis rats. After inducing EAE, the expression of PLD1 was analyzed by Western blot and immunohistochemistry. Western blot analysis showed that expression of the isozymes PLD1 significantly increased in the spinal cord at the peak stage of EAE, and declined thereafter. Immunohistochemistry showed that PLD1-positive cells increased in number in EAE lesions, which consisted mainly of ED1-positive macrophages and glial fibrillary acidic protein-positive astrocytes. In contrast, PLD1 was only weakly expressed in some spinal cord astrocytes in control rats. These results suggest that PLD1 is increased in autoimmune CNS inflammation, and possibly involved in the activation of macrophages and astrocytes in EAE lesions.

Skin pH is the Master Switch of Kallikrein 5-Mediated Skin Barrier Destruction in a Murine Atopic Dermatitis Model.

Elevated skin surface pH has been reported in patients with atopic dermatitis. In this study, we explored the role of skin pH in the pathogenesis of atopic dermatitis using the NC/Tnd murine atopic dermatitis model. Alkalinization of the skin of asymptomatic NC/Tnd mice housed in specific pathogen-free conditions induced kallikrein 5 and activated protease-activated receptor 2, resulting in thymic stromal lymphopoietin secretion and a cutaneous T-helper 2 allergic response. This was associated with increased transepidermal water loss and development of eczematous lesions in these specific pathogen-free NC/Tnd mice, which normally do not suffer from atopic dermatitis. Injection of recombinant thymic stromal lymphopoietin also induced scratching behavior in the specific pathogen-free NC/Tnd mice. Thymic stromal lymphopoietin production and dermatitis induced by alkalinization of the skin could be blocked by the protease-activated receptor 2 antagonist ENMD-1068. In contrast, weak acidification of eczematous skin in conventionally housed NC/Tnd mice reduced kallikrein 5 activity and ameliorated the dermatitis. Onset of the dermatitis was associated with increased epidermal filaggrin expression and impaired activity of the sodium/hydrogen exchanger 1, a known regulator of skin pH. We conclude that alterations in skin pH directly modulate kallikrein 5 activity leading to skin barrier dysfunction, itch, and dermatitis via the protease-activated receptor 2-thymic stromal lymphopoietin pathway.

Dihomo-γ-linolenic acid prevents the development of atopic dermatitis through prostaglandin D1 production in NC/Tnd mice

BACKGROUND Atopic dermatitis (AD) is a chronic and relapsing skin disorder with pruritic skin symptoms. We previously reported that dihomo-γ-linolenic acid (DGLA) prevented the development of AD in NC/Tnd mice, though the mechanism remained unclear. OBJECTIVE We attempted to investigate the mechanism of preventive effect of DGLA on AD development in NC/Tnd mice. METHODS The clinical outcomes of NC/Tnd mice that were given diets containing DGLA, arachidonic acid, or eicosapentaenoic acid were compared. Lipid mediator contents in the skin in each group were also quantified. In addition, release of lipid mediators from RBL-2H3 mast cells treated with either DGLA or prostaglandin D1 (PGD1) was measured. Furthermore, effect of PGD1 on gene expression of thymic stromal lymphopoietin (TSLP) in PAM212 keratinocyte cells was determined. RESULTS Only DGLA containing diet suppressed the development of dermatitis in vivo. By quantifying the 20-carbon fatty acid-derived eicosanoids in the skin, the application of DGLA was found to upregulate PGD1, which correlated with a better outcome in NC/Tnd mice. Moreover, we confirmed that mast cells produced PGD1 after DGLA exposure, thereby exerting a suppressive effect on immunoglobulin E-mediated degranulation. PGD1 also suppressed gene expression of TSLP in keratinocytes. CONCLUSION These results suggest that oral administration of DGLA causes preventive effects on AD development in NC/Tnd mice by regulating the PGD1 supply.

A novel NF-κB inhibitor improves glucocorticoid sensitivity of canine neoplastic lymphoid cells by up-regulating expression of glucocorticoid receptors

Lymphoid neoplasms including lymphoma and leukemia are one of the most life-threatening disorders in dogs. Many lymphoid malignancies are well-treated with glucocorticoid (GC); however, GC resistance sometimes develops and its mechanism remains uncertain. Since constitutive activation of nuclear factor-κB (NF-κB) has been reported to play roles in lymphoid malignancies, we examined whether inhibition of NF-κB activity with a synthetic inhibitor IMD-0354 affected GC sensitivity of canine neoplastic lymphoid cells, CL-1 and GL-1. Dexamethasone failed to inhibit proliferation of these cells, in which low expression of glucocorticoid receptors (GR) was identified. In the presence of IMD-0354, GR expressions in CL-1 and GL-1 were increased, consequently dexamethasone inhibited their proliferation. These results indicated that GR expression might be down-regulated by spontaneous activation of NF-κB, resulting in GC resistance. Taken together, interference of NF-κB activity may have the synergistic effect in combination chemotherapy with GC for treatment against lymphoid malignancies.

Stem cell factor contributes to tumorigenesis of mast cells via an autocrine/paracrine mechanism

Mastocytosis is a disease accompanied by the abnormal expansion and accumulation of mast cells. Although the D816V mutation is detected in most cases of systemic mastocytosis, the mutation is rarely observed in other forms of mastocytosis, such as cutaneous mastocytosis and mast cell leukemia/sarcoma, for which the mechanism of tumorigenesis remains unknown. In this study, we demonstrated a novel mechanism of mast cell tumorigenesis via SCF autocrine/paracrine release. SCF was highly expressed in a WT KIT‐expressing HRMC line, contributing to the phosphorylation of KIT. Neutralization of external SCF using a neutralizing antibody or suppression of SCF production by RNA interference inhibited the growth of HRMC cells, indicating the essential role of SCF in cell proliferation. To the best of our knowledge, this is the first report to determine the significant contribution of SCF autoproduction to neoplastic proliferation of mast cells. These results indicate the possibility that targeting SCF production may become a novel treatment for mast cell malignancies.