The Cytokine IL-17A Limits Th17 Pathogenicity via a Negative Feedback Loop Driven by Autocrine Induction of IL-24.

Dysregulated Th17 cell responses underlie multiple inflammatory and autoimmune diseases, including autoimmune uveitis and its animal model, EAU. However, clinical trials targeting IL-17A in uveitis were not successful. Here, we report that Th17 cells were regulated by their own signature cytokine, IL-17A. Loss of IL-17A in autopathogenic Th17 cells did not reduce their pathogenicity and instead elevated their expression of the Th17 cytokines GM-CSF and IL-17F. Mechanistic in vitro studies revealed a Th17 cell-intrinsic autocrine loop triggered by binding of IL-17A to its receptor, leading to activation of the transcription factor NF-κB and induction of IL-24, which repressed the Th17 cytokine program. In vivo, IL-24 treatment ameliorated Th17-induced EAU, whereas silencing of IL-24 in Th17 cells enhanced disease. This regulatory pathway also operated in human Th17 cells. Thus, IL-17A limits pathogenicity of Th17 cells by inducing IL-24. These findings may explain the disappointing therapeutic effect of targeting IL-17A in uveitis.

IL-27-producing B-1a cells suppress neuroinflammation and CNS autoimmune diseases.

Regulatory B cells (Breg cells) that secrete IL-10 or IL-35 (i35-Breg) play key roles in regulating immunity in tumor microenvironment or during autoimmune and infectious diseases. Thus, loss of Breg function is implicated in development of autoimmune diseases while aberrant elevation of Breg prevents sterilizing immunity, exacerbates infectious diseases, and promotes cancer metastasis. Breg cells identified thus far are largely antigen-specific and derive mainly from B2-lymphocyte lineage. Here, we describe an innate-like IL-27-producing natural regulatory B-1a cell (i27-Breg) in peritoneal cavity and human umbilical cord blood. i27-Bregs accumulate in CNS and lymphoid tissues during neuroinflammation and confers protection against CNS autoimmune disease. i27-Breg immunotherapy ameliorated encephalomyelitis and uveitis through up-regulation of inhibitory receptors (Lag3, PD-1), suppression of Th17/Th1 responses, and propagating inhibitory signals that convert conventional B cells to regulatory lymphocytes that secrete IL-10 and/or IL-35 in eye, brain, or spinal cord. Furthermore, i27-Breg proliferates in vivo and sustains IL-27 secretion in CNS and lymphoid tissues, a therapeutic advantage over administering biologics (IL-10, IL-35) that are rapidly cleared in vivo. Mutant mice lacking irf4 in B cells exhibit exaggerated increase of i27-Bregs with few i35-Bregs, while mice with loss of irf8 in B cells have abundance of i35-Bregs but defective in generating i27-Bregs, identifying IRF8/BATF and IRF4/BATF axis in skewing B cell differentiation toward i27-Breg and i35-Breg developmental programs, respectively. Consistent with its developmental origin, disease suppression by innate i27-Bregs is neither antigen-specific nor disease-specific, suggesting that i27-Breg would be effective immunotherapy for a wide spectrum of autoimmune diseases.

Autoimmunity to neuroretina in the concurrent absence of IFN-γ and IL-17A is mediated by a GM-CSF-driven eosinophilic inflammation.

IFN-γ and IL-17A can each elicit ocular autoimmunity independently of the other. Since absence of IFN-γ or IL-17A individually failed to abolish pathology of experimental autoimmune uveitis (EAU), we examined EAU development in the absence of both these cytokines. Ifng-/-Il17a-/- mice were fully susceptible to EAU with a characteristic eosinophilic ocular infiltrate, as opposed to a mononuclear infiltrate in WT mice. Retinal pathology in double-deficient mice was ameliorated when eosinophils were genetically absent or their migration was blocked, supporting a pathogenic role for eosinophils in EAU in the concurrent absence of IFN-γ and IL-17A. In EAU-challenged Ifng-/-Il17a-/- mice, ocular infiltrates contained increased GM-CSF-producing CD4+ T cells, and supernatants of retinal antigen-stimulated splenocytes contained enhanced levels of GM-CSF that contributed to activation and migration of eosinophils in vitro. Systemic or local blockade of GM-CSF ameliorated EAU in Ifng-/-Il17a-/- mice, reduced eosinophil peroxidase levels in the eye and in the serum and decreased eosinophil infiltration to the eye. These results support the interpretation that, in the concurrent absence of IFN-γ and IL-17A, GM-CSF takes on a major role as an inflammatory effector cytokine and drives an eosinophil-dominant pathology. Our findings may impact therapeutic strategies aiming to target IFN-γ and IL-17A in autoimmune uveitis.

Tofacitinib inhibits the development of experimental autoimmune uveitis and reduces the proportions of Th1 but not of Th17 cells.

Purpose: Tofacitinib is a pan-Janus kinase (JAK) inhibitor that suppresses cytokine signaling and in turn, the cells that participate in inflammatory immunopathogenic processes. We examined the capacity of tofacitinib to inhibit the induction of experimental autoimmune uveitis (EAU) and related immune responses. Methods: EAU was induced in B10.A mice with immunization with bovine interphotoreceptor retinoid-binding protein (IRBP), emulsified in complete Freund's adjuvant (CFA), and a simultaneous injection of pertussis toxin. Tofacitinib, 25 mg/kg, was administered daily, and the vehicle was used for control. EAU development was assessed by histological analysis of the mouse eyes, and related immune responses were assessed by (i) the levels of interferon (IFN)-γ and interleukin (IL)-17, secreted by spleen cells cultured with IRBP; (ii) flow cytometric analysis of intracellular expression by spleen, or eye-infiltrating CD4 or CD8 cells of IFN-γ, IL-17, and their transcription factors, T-bet and RORγt. In addition, the inflammation-related cell markers CD44 and CD62L and Ki67, a proliferation marker, were tested. The proportions of T-regulatory cells expressing FoxP3 were determined by flow cytometric intracellular staining, while levels of antibody to IRBP were measured with enzyme-linked immunosorbent assay (ELISA). Results: Treatment with tofacitinib significantly suppressed the development of EAU and reduced the levels of secreted IFN-γ, but not of IL-17. Further, treatment with tofacitinib reduced in the spleen and eye-infiltrating cells the intracellular expression of IFN-γ and its transcription factor T-bet. In contrast, treatment with tofacitinib had essentially no effect on the intracellular expression of IL-17 and its transcription factor, RORγt. The selective effect of tofacitinib treatment was particularly evident in the CD8 population. Treatment with tofacitinib also increased the population of CD44, but reduced the populations of cells producing CD62L and Ki67. Treatment with tofacitinib had no effect on the proportion of FoxP3 producing regulatory cells and on the antibody production to IRBP. Conclusions: Treatment with tofacitinib inhibited the development of EAU, reduced the production of IFN-γ, but had essentially no effect on the production of IL-17.

TMP778, a selective inhibitor of RORγt, suppresses experimental autoimmune uveitis development, but affects both Th17 and Th1 cell populations.

Experimental autoimmune uveitis (EAU), an animal model for severe intraocular inflammatory eye diseases, is mediated by both Th1 and Th17 cells. Here, we examined the capacity of TMP778, a selective inhibitor of RORγt, to inhibit the development of EAU, as well as the related immune responses. EAU was induced in B10.A mice by immunization with interphotoreceptor retinoid-binding protein (IRBP). Treatment with TMP778 significantly inhibited the development of EAU, determined by histological examination. In addition, the treatment suppressed the cellular immune response to IRBP, determined by reduced production of IL-17 and IFN-γ, as well as lower percentages of lymphocytes expressing these cytokines, as compared to vehicle-treated controls. The inhibition of IFN-γ expression by TMP778 is unexpected in view of this compound being a selective inhibitor of RORγt. The observation was further confirmed by the finding of reduced expression of the T-bet (Tbx21) gene, the transcription factor for IFN-γ, by cells of TMP778-treated mice. Thus, these data demonstrate the capacity of TMP778 to inhibit pathogenic autoimmunity in the eye and shed new light on its mode of action in vivo.

AS101 ameliorates experimental autoimmune uveitis by regulating Th1 and Th17 responses and inducing Treg cells.

AS101 is an organotellurium compound with multifaceted immunoregulatory properties that is remarkable for its lack of toxicity. We tested the therapeutic effect of AS101 in experimental autoimmune uveitis (EAU), a model for human autoimmune uveitis. Unexpectedly, treatment with AS101 elicited Treg generation in vivo in otherwise unmanipulated mice. Mice immunized for EAU with the retinal antigen IRBP and treated with AS101 developed attenuated disease, as did AS101-treated recipients of retina-specific T cells activated in vitro. In both settings, eye-infiltrating effector T cells were decreased, whereas regulatory T (Treg) cells in the spleen were increased. Mechanistic studies in vitro revealed that AS101 restricted polarization of retina-specific T cells towards Th1 or Th17 lineage by repressing activation of their respective lineage-specific transcription factors and downstream signals. Retina-specific T cells polarized in vitro towards Th1 or Th17 in the presence of AS101 had impaired ability to induce EAU in naïve recipients. Finally, AS101 promoted differentiation of retina-specific T cells to Tregs in vitro independently of TGF-ß. We conclude that AS101 modulates autoimmune T cells by inhibiting acquisition and expression of effector function and by promoting Treg generation, and suggest that AS101 could be useful as a therapeutic approach for autoimmune uveitis.

Jeju ground water containing vanadium induces normal T cell development and immune activation in chronically stressed mice.

Containing high concentration of vanadium served by the volcanic bedrock, Jeju ground water has long been known for various implicit health benefits including immune-promotion. Exposure to stress has been reported to be associated with immunosuppression such as reducing lymphocyte population or antibody production due to stress hormones. In this study, we aimed at evaluating the effects of Jeju ground water on chronically stressed mice. C57BL/6 mice were subjected to various stressors such as restraint stress, water swimming stress, heat stress, acoustic stress, and Jeju ground water was supplied for 28 days with two different concentrations, S1 (vanadium 15-20 µg/l, pH 8.3) and S2 (vanadium 20-25 µg/l, pH 8.5). Treatment with Jeju ground water increased CD4+CD8- or CD4-CD8+ single-positive thymocytes. It also increased the proliferation of splenocytes and the populations of CD4+ T cells, CD45R/B220+ B cells, CD11b+ macrophages or Gr-1+ granulocytes in spleen. In addition, the production of IgG was increased in chronically stressed mice by treatment with Jeju ground water. These results suggest vanadium-rich Jeju ground water may be helpful in T cell development in thymus and immune cell proliferation and its function in spleen against chronic stress.

Beetroot (Beta vulgaris) rescues mice from γ-ray irradiation by accelerating hematopoiesis and curtailing immunosuppression.

CONTEXT: Beetroot [Beta vulgaris Linné (Chenopodiaceae)], a vegetable usually consumed as a food or a medicinal plant in Europe, has been reported to have antioxidant and anti-inflammatory properties. Since the lymphohematopoietic system is the most sensitive tissue to ionizing radiation, protecting it from radiation damage is one of the best ways to decrease detrimental effects from radiation exposure. OBJECTIVE: In this study, we evaluated the radio-protective effects of beetroot in hematopoietic stem cells (HSCs) and progenitor cells. MATERIALS AND METHODS: Beetroot extract was administered at a dose of 400 mg/mouse per os (p.o.) three times into C57BL/6 mice and, at day 10 after γ-ray irradiation, diverse molecular presentations were measured and compared against non-irradiated and irradiated mice with PBS treatments. Survival of beetroot-fed and unfed irradiated animal was also compared. RESULTS: Beetroot not only stimulated cell proliferation, but also minimized DNA damage of splenocytes. Beetroot also repopulated S-phase cells and increased Ki-67 or c-Kit positive cells in bone marrow. Moreover, beetroot-treated mice showed notable boosting of differentiation of HSCs into burst-forming units-erythroid along with increased production of IL-3. Also, beetroot-treated mice displayed enhancement in the level of hematocrit and hemoglobin as well as the number of red blood cell in peripheral blood. Beetroot diet improved survival rate of lethally exposed mice with a dose reduction factor (DRF) of 1.1. DISCUSSION AND CONCLUSION: These results suggest that beetroot has the potency to preserve bone marrow integrity and stimulate the differentiation of HSCs against ionizing radiation.

Citrus hallabong [(Citrus unshiu × C. sinensis) × C. reticulata)] exerts potent anti-inflammatory properties in murine splenocytes and TPA-induced murine ear oedema model.

CONTEXT: Hallabong [(Citrus unshiu × C. sinensis) X C. reticulata)] (Rutaceae) is a hybrid citrus cultivated in temperate regions of South Korea. Its fruit is well-known for pharmacological properties. OBJECTIVE: This study examined the anti-inflammatory effect of 80% ethanol extract of Hallabong (HE) on concanavalin A (Con A)-stimulated splenocytes and mouse oedema model induced by 12-O-tetradecanoylphorbal acetate (TPA). MATERIALS AND METHODS: Murine splenocytes treated with HE were stimulated with Con A (10 µg/mL, for 24 h) were evaluated for T-cell population and production of inflammatory cytokines IL-2, IL-4 and IFN-γ. Anti-inflammatory effect of topically applied HE (100 µg/20 µL) on TPA (4 µg/20 µL/ear)-induced ear oedema was investigated in mouse model. RESULTS: HE-treated Con A-stimulated murine splenocytes showed a marked decrease in CD44/CD62L+ memory T-cell population, an important marker for anti-inflammatory activity, and a significant inhibition in the production of IL-2 and IFN-γ. HE treatment had reduced the mouse skin oedema (47%) and myeloperoxidase (MPO) activity significantly (40%) in TPA-challenged tissues. More importantly, immunohistochemical localization revealed the suppressed (p < 0.05) expression of inducible nitric oxide (iNOS), cyclooxygenase-2 (COX2). HE decreased the infiltration of CD3+ T cells and F4/80+ macrophages to the site of inflammation and a topical application of HE significantly suppressed the expression of TNF-α (20.2%). DISCUSSION AND CONCLUSION: A topical application of HE can exert a potential anti-inflammatory effect and HE can be explored further as a putative alternative therapeutic agent for inflammatory oedema.

Lipocalin-2 protein deficiency ameliorates experimental autoimmune encephalomyelitis: the pathogenic role of lipocalin-2 in the central nervous system and peripheral lymphoid tissues.

Lipocalin-2 (LCN2) plays an important role in cellular processes as diverse as cell growth, migration/invasion, differentiation, and death/survival. Furthermore, recent studies indicate that LCN2 expression and secretion by glial cells are induced by inflammatory stimuli in the central nervous system. The present study was undertaken to examine the regulation of LCN2 expression in experimental autoimmune encephalomyelitis (EAE) and to determine the role of LCN2 in the disease process. LCN2 expression was found to be strongly increased in spinal cord and secondary lymphoid tissues after EAE induction. In spinal cords astrocytes and microglia were the major cell types expressing LCN2 and its receptor 24p3R, respectively, whereas in spleens, LCN2 and 24p3R were highly expressed in neutrophils and dendritic cells, respectively. Furthermore, disease severity, inflammatory infiltration, demyelination, glial activation, the expression of inflammatory mediators, and the proliferation of MOG-specific T cells were significantly attenuated in Lcn2-deficient mice as compared with wild-type animals. Myelin oligodendrocyte glycoprotein-specific T cells in culture exhibited an increased expression of Il17a, Ifng, Rorc, and Tbet after treatment with recombinant LCN2 protein. Moreover, LCN2-treated glial cells expressed higher levels of proinflammatory cytokines, chemokines, and MMP-9. Adoptive transfer and recombinant LCN2 protein injection experiments suggested that LCN2 expression in spinal cord and peripheral immune organs contributes to EAE development. Taken together, these results imply LCN2 is a critical mediator of autoimmune inflammation and disease development in EAE and suggest that LCN2 be regarded a potential therapeutic target in multiple sclerosis.

The JNk/NFkappaB pathway is required to activate murine lymphocytes induced by a sulfated polysaccharide from Ecklonia cava.

BACKGROUND: The proven immunomodulatory and immune system activating properties of Ecklonia cava (E. cava) have been attributed to its plentiful polysaccharide content. Therefore, we investigated whether the sulfated polysaccharide (SP) of E. cava specifically activates the protein kinases (MAPKs) and nuclear factor-kappaB (NFkappaB) to incite immune responses. METHODS: To assess immune responsiveness, lymphocytes were isolated from spleens of ICR mice and cultured with SP and its inhibitors. Assays included 3H-thymidine incorporation, flow cytometry, real time polymerase chain reaction (rtPCR), enzyme linked immunosorbent assay (ELISA), intracellular cytokine assay. Western blot, and electrophoretic mobility shift assay (EMSA). RESULTS: SP dose-dependently increased the proliferation of lymphocytes without cytotoxicity. In particular, SP markedly enhanced the proliferation and differentiation of CD3+ mature T cells and CD45R/B220+ pan B cells. Additionally, SP increased the expression and/or production of IL-2, IgG(1a), and IgG(2b) compared to that in untreated cells. The subsequent application of JNK (SP600125), NFkappaB (PDTC), and serine protease (TPCK) inhibitors significantly inhibited the proliferation and IL-2 production of SP-treated lymphocytes as well as the phosphorylation of JNK and IkappaB, the activation of nuclear NFkappaB p65, and binding of NFkappaB p65 DNA. Moreover, co-application of both JNK and NFkappaB inhibitors completely blocked the proliferation of lymphocytes even in the presence of SP. CONCLUSION: These results suggest that SP induced T and B cell responses via both JNK and NFkappaB pathways. GENERAL SIGNIFICANCE: The effect of SP on splenic lymphocyte activation was assayed here for the first time and indicated the underlying functional mechanism.

Rational immunosilencing of a promiscuous T-cell epitope in the capsid of an adeno-associated virus.

Owing to the immunogenicity of adeno-associated viruses (AAVs), gene therapies using AAVs face considerable obstacles. Here, by leveraging ex vivo T-cell assays, the prediction of epitope binding to major histocompatibility complex class-II alleles, sequence-conservation analysis in AAV phylogeny and site-directed mutagenesis, we show that the replacement of amino acid residues in a promiscuous and most immunodominant T-cell epitope in the AAV9 capsid with AAV5 sequences abrogates the immune responses of peripheral blood mononuclear cells to the chimaeric vector while preserving its functions, potency, cellular specificity, transduction efficacy and biodistribution. This rational approach to the immunosilencing of capsid epitopes promiscuously binding to T cells may be applied to other AAV vectors and epitope regions.

Low cross reactivity between wild type and deamidated AAV can lead to false negative results in immune monitoring T-cell assays.

During gene therapy trials, immune responses against adeno-associated virus (AAV) vectors are monitored by antibody assays that detect the humoral and T-cell mediated cellular responses to AAV vectors. T cell assays commonly utilize the collection of patients' peripheral blood mononuclear cells (PBMCs) and stimulation with AAV-derived overlapping peptides. We recently described that spontaneous deamidation coincides with T cell epitopes in AAV capsids and that spontaneous deamidation may enhance or decrease immunogenicity in some individuals. This raised the concern for false negative results of antibody detection and PBMC immune monitoring assays because these assays use wild-type (WT) AAV or WT peptides for T cell re-stimulation and these peptides may not re-activate T cells that were stimulated with deamidated AAV capsid. To investigate this concern, we modeled the scenario by expanding T cells with deamidated peptides and evaluated the cross-reactivity of expanded T cells to WT peptides. In the majority of samples, cells that were expanded with deamidated peptides and restimulated with WT peptide had significantly lowered IL-2 and IFN-γ production. Spiking the four deamidated peptides to the WT peptide pool used for re-stimulation, restored the signal and corrected the performance of the assay. We also evaluated the impact of deamidation on anti AAV binding antibodies and did not observe a major impact on seroprevalence detection of AAV9. These data indicate that a high level of deamidation in AAV therapy may result in underestimation or even failure to detect immune responses against WT peptides during cellular immune monitoring.

Differential T cell immune responses to deamidated adeno-associated virus vector.

Despite the high safety profile demonstrated in clinical trials, the immunogenicity of adeno-associated virus (AAV)-mediated gene therapy remains a major hurdle. Specifically, T-cell-mediated immune responses to AAV vectors are related to loss of efficacy and potential liver toxicities. As post-translational modifications in T cell epitopes have the potential to affect immune reactions, the cellular immune responses to peptides derived from spontaneously deamidated AAV were investigated. Here, we report that highly deamidated sites in AAV9 contain CD4 T cell epitopes with a Th1 cytokine pattern in multiple human donors with diverse human leukocyte antigen (HLA) backgrounds. Furthermore, some peripheral blood mononuclear cell (PBMC) samples demonstrated differential T cell activation to deamidated or non-deamidated epitopes. Also, in vitro and in silico HLA binding assays showed differential binding to the deamidated or non-deamidated peptides in some HLA alleles. This study provides critical attributes to vector-immune-mediated responses, as AAV deamidation can impact the immunogenicity, safety, and efficacy of AAV-mediated gene therapy in some patients.

1,2,3,4,6-penta-O-galloyl-beta-D-glucose protects splenocytes against radiation-induced apoptosis in murine splenocytes.

Antioxidant property and hematopoietic repair capacity are important characteristics of radioprotective agents. Some studies have demonstrated that 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (PGG), a molecule isolated from the waterlily, has antioxidant, hematopoietic repair, and anti-inflammatory activities. In this study, we try to determine whether PGG extracted from a lily, Nymphaea tetragona var. angusta, has radioprotective effects on splenocytes in vitro against (60)Co gamma-ray irradiation with absorption doses of 2 Gy and 4 Gy. Results show that PGG treatment dramatically enhances the proliferation of splenocytes compared with irradiated but untreated controls. In addition, PGG treatment before irradiation protects the splenocytes from lethal effects of irradiation and decreases DNA damages as identified by the alkaline comet assay. PGG-treated cells also show less radiation-induced apoptosis. These cells have lower concentrations of the pro-apoptotic protein p53 and more of the anti-apoptotic protein Bcl-2. The results presented in this study suggest that PGG has a cytoprotective effect on immune cells exposed to normally damaging amount of radiation. Thus, PGG could be an effective, non-toxic radioprotective agent.

Sasa quelpaertensis leaves ameliorate alcohol-induced liver injury by attenuating oxidative stress in HepG2 cells and mice.

Oxidative stress plays a crucial role in the progression of alcoholic liver diseases and substances of antioxidant property are of special interest for therapeutic purposes. We investigated the hepatoprotective effect of leaf extracts of Sasa quelpaertensis, an edible bamboo mainly cultivated in Jeju Island, South Korea. We examined the cytotoxicity of different extracts (distilled water, 20-80% EtOH) of S. quelpaertensis on HepG2 cells and their hepatoprotective effect on HepG2 cells stimulated by ethanol (800 mM, 24 h). Furthermore, we measured reactive oxygen species (ROS) production, ethanol toxicity induced cell death, and the activity of antioxidant enzymes. In in vivo experiments, liver damage was induced by oral administration of 5 g/kg ethanol with or without potent ethanol extract of S. quelpaertensis (10 or 100 mg/kg) 12 h interval for a total of 3 doses. Only 80% ethanol extract of S. quelpaertensis (SQEE80) exhibited cytoprotective effect on HepG2 cells against alcohol-induced toxicity. SQEE80 treatment (250, 500 µg/mL) in ethanol exposed HepG2 cells showed significant attenuation of ROS production and ethanol toxicity induced cell death. Furthermore, SQEE80 markedly increased the activity of antioxidant enzyme glutathione peroxidase 1 in ethanol exposed HepG2 cells compared to ethanol stimulated cells. In in vivo experiments, SQEE80 treatment evidently suppressed the alcohol-induced histopathological changes in liver, serum ethanol content, and expression of cytochrome P450 2E1. Furthermore, SQEE80 significantly reversed the reduction of glutathione level in the ethanol challenged liver. Taken together, we suggest the possibility of developing SQEE80 as a natural hepatoprotective substance in attenuating alcohol-induced oxidative stress.

Geraniin Promotes Recovery of Hematopoietic Cells after Radiation Injury.

Cells of the hematopoietic system are uniquely radiosensitive due to their rapid proliferation. Consequently, immune suppression readily and undesirably results from irradiation. Our previous studies demonstrated that geraniin isolated from Nymphaea tetragona var. angusta (water lily) had a protective effect on the splenocytes and intestinal tract of irradiated mice. This study was designed to assess the effectiveness of geraniin, an ellagitannin isolated from the water lily, in decreasing gamma ray irradiation-induced destruction of the hematopoietic system in mice. Geraniin treatment improved the survival time of bone marrow cells and maintained bone marrow integrity and also up-regulated the expression of stem cell receptors and the extent of cell mitosis. Geraniin also enhanced the proliferation and differentiation of immune cells that had been suppressed by irradiation. These results suggest geraniin is a promising agent for reconstituting hematopoietic cells after exposure to irradiation.

Protective Effects on Central Nervous System by Acidic Polysaccharide of Panax ginseng in Relapse-Remitting Experimental Autoimmune Encephalomyelitis-Induced SJL/J Mice.

Bearing pathologic and clinical similarities to human multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE) is used as a murine model to test potential therapeutic agents for MS. Recently, we reported the protective effects of an acidic polysaccharide of Panax ginseng (APG) in C57BL/6 strain-dependent EAE, a model of primary progressive MS. In this study, we extend our previous findings on the therapeutic capacity of APG in relapsing-remitting EAE (rr-EAE), the animal model to closely mimic recurrent inflammatory demyelination lesions of relapsing-remitting MS. Treatments with APG led to a significant reduction of clinical symptoms and the relapse rate of EAE than vehicle treatments. Consistent with this, histological examination revealed that APG markedly modulated the infiltration of CD4[Formula: see text] T cells and CD11b[Formula: see text] macrophages into the spinal cord and the APG-treated CNS was devoid of demyelination and axonal damages. In addition, APG decreased the proliferation of peripheral PLP-reactive T cells and the production of pro-inflammatory factors such as IFN-[Formula: see text], IL-17 and TNF-[Formula: see text]. The fact that APG can induce clinically beneficial effects to distinct types of EAE furthers our understanding on the basis of its immunosuppression in EAE and, possibly, in MS. Our results suggest that APG may serve as a new therapeutic agent for MS as well as other human autoimmune diseases, and warrants continued evaluation for its translation into therapeutic application.

IKKß-mediated inflammatory myeloid cell activation exacerbates experimental autoimmune encephalomyelitis by potentiating Th1/Th17 cell activation and compromising blood brain barrier.

BACKGROUND: The inflammatory myeloid cell activation is one of the hallmarks of experimental autoimmune encephalomyelitis (EAE), yet the in vivo role of the inflammatory myeloid cell activation in EAE has not been clearly resolved. It is well-known that IKK/NF-κB is a key signaling pathway that regulates inflammatory myeloid activation. METHODS: We investigated the in vivo role of inflammatory myeloid cell activation in myelin oligodendrocyte glycoprotein (MOG) peptides-induced EAE using myeloid cell type-specific ikkß gene conditional knockout-mice (LysM-Cre/Ikkß (F/F) ). RESULTS: In our study, LysM-Cre/Ikkß (F/F) mice had alleviated clinical signs of EAE corresponding to the decreased spinal demyelination, microglial activation, and immune cell infiltration in the spinal cord, compared to the wild-type mice (WT, Ikkß (F/F) ). Myeloid ikkß gene deletion significantly reduced the percentage of CD4(+)/IFN-γ(+) (Th1) and CD4(+)/IL-17(+) (Th17) cells but increased the percentages of CD4(+)/CD25(+)/Foxp3(+) (Treg) cells in the spinal cord and lymph nodes, corresponding to the altered mRNA expression of IFN-γ, IL-17, IL-23, and Foxp3 in the spinal cords of LysM-Cre/Ikkß (F/F) EAE mice. Also, the beneficial effect of myeloid IKKß deletion in EAE corresponded to the decreased permeability of the blood brain barrier (BBB). CONCLUSIONS: Our findings strongly suggest that IKK/NF-kB-induced myeloid cell activation exacerbates EAE by activating Th1 and Th17 responses and compromising the BBB. The development of NF-κB inhibitory agents with high efficacy through specific targeting of IKKß in myeloid cells might be of therapeutic potential in MS and other autoimmune disorders.

Emodin induces apoptosis of concanavalin A-stimulated murine splenocytes.

Emodin, one of the major compounds in the herb Reynoutria elliptica, is known to maintain immunosuppressive, anti-allergic, anti-cancer, and anti-inflammatory effects. In this study, we assessed the possibility of using emodin to induce apoptosis in stimulated immune cells in vitro. After treatment with emodin and concanavalin A (Con A), we observed DNA damage-induced apoptosis in splenocytes. Moreover, treatment with emodin and Con A increased the number of apoptotic splenocytes compared with untreated controls. Emodin also diminished the size of CD45R/B220+ cells, CD19+CD69+ cells, and cDC populations. These results indicate that emodin-induced apoptosis was involved in attenuating the immune activity promoted by DNA damage and in decreasing the number of CD45R/B220+ B cells and CD19+CD69+ activating B cells. This demonstration of emodin inducing apoptosis of Con A-stimulated immune cells indicates its potential utility as a therapy for diseases caused by abnormally activated immune cells.